Year in Review Asthma, Airway Biology, and Allergic Rhinitis in AJRCCM 2000 MARTIN J. TOBIN Division of Pulmonary and Critical Care Medicine, Loyola University of Chicago Stritch School of Medicine and Edward Hines, Jr., Veterans Affairs Hospital, Hines, Illinois
Contents Asthma and Airway Biology Genetics (16) Epidemiology (3) Airway Inflammation Animal Models (5) Induced Sputum (5) Bronchoalveolar Specimens (4) Blood (3) Exhaled Nitric Oxide (6) Other Exhaled Markers (3) Ex Vivo Studies (2) Airway Hyperreactivity Animal Models: Antigen Challenge (7) Animal Models: Other Challenges and Mediators (9) Ex Vivo Studies (5) Early and Late Asthmatic Responses (5) Antigen and Methacholine Challenge (3) Exercise-Induced Asthma (6) Drugs (1) Other Pathophysiological Mechanisms in Asthma Tachykinins, Neural Activity (8) Deep Inspiration Bronchoconstriction (3) Blood Flow (2) Immunology (1) Airway Narrowing (4) Remodeling (1) Classic Mechanics (2) Treatment -Agonists (1) Inhaled Glucocorticoids (7) Glucocorticoids (1) Muscarinic Antagonists (2) Leukotriene Inhibitors (1) Combination Regimens (5) Specific Clinical Scenarios Nocturnal Asthma (3) Acute Severe and Fatal Asthma (4) Dyspnea (2) Quality of Life (2) Age (1) Differential Diagnosis: Eosinophilic Bronchitis (1)
Supported by a Merit Review grant from the Veterans Affairs Research Service. Correspondence and requests for reprints should be addressed to Martin J. Tobin, M.D., Division of Pulmonary and Critical Care Medicine, Edwards Hines, Jr., Veterans Affairs Hospital, Route 111N, Hines, IL 60141. E-mail:
[email protected] Am J Respir Crit Care Med Vol 164. pp 1559–1580, 2001 DOI: 10.1164/rccm2108114 Internet address: www.atsjournals.org
Occupational Asthma Diisocyanates (2) High Molecular Weight Agents (1) Farmers (1) Prevalence and Severity (2) Natural History (2) Allergic Rhinitis Risk Factors (2) Quality of Life (1) Inflammation and Hyperreactivity (6) Treatment (4) References
ASTHMA AND AIRWAY BIOLOGY Genetics
Because several reports have implicated the chromosomal region 5q31-q33 in harboring the gene for the 2-receptor, Ulbrecht and coworkers (1) undertook an association study focusing on bronchial hyperresponsiveness as a qualitative trait. From a population sample of 1,150 people, all 152 hyperreactive probands (index cases) were extracted and compared with 295 control subjects who had normal bronchial reactivity. All individuals were genotyped for three single nucleotide polymorphisms of the 2-receptor gene, resulting in variants at the amino acid positions 16, 27, and 164. No individual polymorphism (an allele with a frequency of at least 1%) was associated with bronchial hyperreactivity, but the Gly16/Gln27/Thr164 haplotype was underrepresented in the case group, indicating that this haplotype protects against hyperreactivity. The FCER2 gene encoding the low-affinity receptor for IgE has been mapped to chromosome 19p13 and is implicated as a candidate for IgE-mediated allergic disorders. Laitinen and coworkers (2) studied three phenotypic markers (asthma, total serum IgE, and IgE specific for aeroallergens) in 124 families from Finland and Catalonia. Eight polymorphic markers in a region around the FCER2 gene were analyzed. The allele and haplotype association study revealed a suggestive haplotype association for a high IgE response. (A haplotype consists of closely linked alleles on a single chromosome that are usually inherited as a group and determine a particular phenotype.) In families with two or more affected members, a single haplotype was highly enriched but sequence polymorphisms were not detected. The authors conclude that chromosome 19p13 might harbor a genetic determinant of IgE-related traits. Because variants of the FCER1B gene are associated with increased risk of atopy and asthma, Hizawa and coworkers (3) screened 24 patients with asthma for new mutations. A common 109C/T polymorphism at the promoter region of FCER1B was identified. Genotyping of this promoter polymorphism in 226 asthmatic and 226 control subjects revealed similar distri-
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bution. Homozygosity for the 109T allele was associated with increased IgE in the asthmatics. The authors conclude that the 109C/T polymorphism of the FCER1B promoter region is one of the genetic factors affecting serum IgE in the Japanese population. Because total IgE is related to active smoking in the general population, Oryszczyn and coworkers (4) studied 122 asthmatic probands, 430 first-degree relatives, and 190 control subjects to see whether asthma influenced the relationship. Levels of total IgE in first-degree relatives were intermediate between cases and control subjects, and current smokers had higher levels than never smokers. IgE was increased in female first-degree relatives in relation to passive smoking. The authors conclude that active smoking was related to higher total IgE independently of gender, or personal or family history of asthma, and that active smoking increased IgE even in asthmatic subjects. Genes on chromosomes 5q and 11q exhibit the most consistent association with the asthma-related phenotypes of bronchial hyperresponsiveness and atopy. Few studies have focused on genes protecting against oxidative stress, which plays a critical role in airway inflammation. Fryer and coworkers (5) undertook an association study to determine whether allelic variation at the glutathione S-transferase GSTP1 locus influences expression of bronchial hyperreactivity and atopy. (Locus is the site or location of a gene in a chromosome.) The enzyme encoded by GSTP1 uses a variety of lipid and DNA products of oxidative stress, and polymorphic variants of this gene are associated with altered catalytic function of this enzyme. The frequency of GSTP1 Val105/Val105 was significantly lower in asthmatic than in control subjects. The presence of this genotype conferred one-sixth the risk of asthma than did GSTP1 Ile105/Ile105. Val105 homozygotes had one-tenth the risk of atopy defined by IgE level. The authors conclude that GSTP1 polymorphism is strongly associated with asthma, and provides an alternative explanation for linkage of chromosome 11q13 with bronchial hyperreactivity and atopy. Because it is not known whether serum IgE and airway hyperresponsiveness arise from distinct or shared genetic determinants, Palmer and coworkers (6) investigated the genetic and environmental components of the variance of these two traits in 232 Australian nuclear families. Total serum IgE had a narrow-sense heritability (h2N of 47%); specific serum IgE had an h2N of 34%; and airway hyperreactivity had an h2N of 30%. Extended modeling revealed that the genetic determinants of total and specific IgE had 70% overlap, whereas determinants of IgE and airway hyperresponsiveness had less than 30% sharing. The authors conclude that the pathophysiologic traits associated with asthma have multiple genetic determinants and that airway hyperresponsiveness is genetically distinct from atopy. Because a marker locus on chromosome 5q23-31 is linked to asthma in Hutterites, Summerhill and coworkers (7) assessed whether the 2-adrenergic receptor gene is the 5qlinked asthma locus in this population. Genotyping 361 individuals for polymorphisms in the receptor gene showed that neither Arg16Gly nor Gln27Glu polymorphisms were linked to bronchial hyperresponsiveness or serum IgE. Individuals homozygous for the Arg16 allele had lower FEV1 and forced vital capacity (FVC). The authors conclude that the observed linkage to asthma in the 5q23-31 region is not related to variation in the 2-adrenergic receptor gene. Atopy has been linked to the chain of the high-affinity IgE receptor on chromosome 11q13, and polymorphisms of that gene (I181L, V183L, and E237G) are reported to be associated with asthma and atopy. Thomas and coworkers (8) investigated linkage to the IgE receptor in a sample of 131 fami-
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lies recruited at random and 109 families found via an asthmatic proband. Four microsatellite markers were genotyped, including the IgE receptor. The frequencies of I181L, V183L, and E237G polymorphisms were determined. No evidence for linkage to the high-affinity IgE receptor was found. The authors conclude that their study fails to strengthen the evidence for a candidate gene on chromosome 11q13. In 381 twin pairs (183 monozygous, 198 dizygous), Clarke and coworkers (9) measured asthma (diagnosed by a physician), atopy (skin tests), and bronchial hyperresponsiveness. Associations between monozygous pairs were greater than between dizygous pairs as shown by their respective odds ratios: asthma, 26 versus 2; atopy, 15 versus 3; and bronchial hyperreactivity, 14 versus 4. The associations between each pair of traits within an individual were slightly greater than the association between one trait in a twin and the other trait in the cotwin (cross-trait cross-pair concordance). The authors conclude that the strong cross-sectional associations between these three traits are due to overlap between the genetic factors involved in each of the traits. The role of Clara cell secretory protein in immunomodulation together with its chromosomal location suggests that the governing gene may be involved in the inheritance of asthma. To address this issue, Laing and coworkers (10) examined the relationship of the A38G polymorphism to gene expression of the Clara cell secretory protein in 100 children. Levels of Clara cell secretory protein were 20% lower in asthmatic children than in healthy controls, and 40% lower in 38A/38A subjects than in 38G/38G subjects; the predisposition, however, was reduced on correcting for plasma levels of the Clara cell secretory protein. The authors conclude that the 38A sequence was associated with less Clara cell secretory protein, and individuals with lower levels of this protein were more likely to have asthma. An increase in exhaled nitric oxide is a critical component of the asthmatic phenotype, but levels of nitric oxide are very variable among patients identified by a standard case definition of asthma. Because neurologic disorders are known to be associated with allelic variations of trinucleotide repeat sequences, Wechsler and coworkers (11) assessed whether exhaled nitric oxide is associated with various alleles at a trinucleotide repeat locus in a prominent asthma candidate gene (neuronal nitric oxide synthase, or NOS1). Individuals having at least 12 AAT repeats at a locus in intron 20 of the nitric oxide synthase 1 gene had both lower and less variable levels of exhaled nitric oxide. The addition of this genotype to the case definition of asthma allows a uniform cohort of patients to be identified that otherwise look phenotypically similar. The authors conclude that the data provide a link between a genotype in a candidate gene and an important component of the asthmatic phenotype. The variation in the response to certain pharmacological agents has been shown to be genetic in nature, but equivalent studies have not been conducted to explain the marked variation in response to bronchodilator agents. Niu and coworkers (12) investigated the degree of familial clustering for the response to inhaled albuterol in 1,161 index families with asthma in China. Each family unit consisted of a mother, a father, a first offspring, and a second offspring. Bronchodilator response showed correlations for: father–first offspring pairs, mother–first offspring pairs, mother–second offspring pairs, and first offspring–second offspring pairs. The correlations (0.09–0.16) suggest a modest degree of familial clustering. The largest odds ratio (3.1) was in a second offspring whose mother and first offspring had a bronchodilator response above the median. The authors conclude that the significant familial aggregation indicates that genetic factors influence bronchodilator responsiveness.
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Because regular use of -agonists may produce adverse effects in some patients, Israel and coworkers (13) studied 190 patients with asthma to determine whether polymorphism of the 2-adrenergic receptor might affect the response to regular versus as-needed use of albuterol. Among patients homozygous for arginine at 2-AR-16 (Arg/Arg), regular albuterol users had a lower morning peak flow (31 liters per minute) than the asneeded users. No significant differences in outcome between regular and as-needed use were associated with polymorphisms at position 27 of the 2-adrenergic receptor or in patients homozygous for glycine at 2-AR-16. The authors conclude that polymorphisms of the 2-adrenergic receptor may influence airway responses to regular inhaled -agonist treatment. Studying cells of human airway smooth muscle, Moore and coworkers (14) examined the influence of two polymorphic forms of the 2-adrenergic receptor, the Gly16 and Glu27 alleles, on acute and long-term desensitization of the receptor. When cells were pretreated with isoproterenol, they became less responsive to subsequent treatment with isoproterenol. When the data were stratified post hoc by genotype, cells containing at least one Glu27 allele showed greater acute and long-term desensitization than cells without that allele. Cells containing the Gly16Glu27 haplotype showed less acute and long-term desensitization than did cells without that haplotype, suggesting that the influence of Glu27 is not through its association with Gly16. The Glu27 allele was in strong linkage disequilibrium with the Arg19 allele, and cells containing any Arg19 allele showed greater acute and long-term desensitization. The authors conclude that the presence of the Glu27 allele is associated with greater acute and long-term desensitization of human airway smooth muscle. The results of gene mapping studies are critically dependent on a standardized definition of the asthma phenotype, and Panhuysen and coworkers developed an algorithm for this purpose in a Dutch population. Celedon and coworkers (15) used a modified version of this algorithm to classify members of 2,756 Chinese families. Among 4,097 Chinese parents, 10% were classified as definite asthma, 7% probable asthma, 15% unclassifiable airway obstruction, 15% chronic obstructive pulmonary disease (COPD), and 39% unaffected. Among 6,424 offspring, 17% were classified as definite asthma, 13% probable asthma, 31% unclassifiable airway obstruction, 4% COPD, and 36% unaffected. The use of this algorithm in a population with a high prevalence of smoking would exclude subjects with asthma who smoke or who have severe airway obstruction from linkage analysis, and hinder the exploration of any potential interaction between genetic factors and smoking. Dizier and coworkers (16) conducted a genome-wide search in 107 French families having at least two siblings with asthma as part of the EGEA (Epidemiological Study on the Genetics and Environment of Asthma, Bronchial Hyperresponsiveness and Atopy) study. Analysis had two stages: the total sample of 107 families was divided into two independent subsets, and the potential linkages detected in the first subset of 46 families were tested for replication in the second subset of 61 families. A total of 254 markers were typed in the first set and 70% in the second set. Linkage was investigated for asthma and four asthma-related phenotypes: bronchial responsiveness, skin tests, total IgE, and eosinophil count. Three regions were detected: 11p13 for IgE, 12q24 for eosinophils, and 17q12-21 for asthma and skin tests. All regions reported by published genome scans in different populations were examined, and seven were found: 11p13 for IgE, 12q24 for eosinophils, 17q12-21 for asthma and skin tests, 1p31 for asthma, 11q13 for IgE, 13q31 for eosinophils, and 9q13 for bronchial hyperresponsiveness. The authors conclude that they identified three regions involved in asthma-like phenotypes.
A series of review articles focus on the question, “What determines asthma phenotypes?” (17–21). Epidemiology
To determine asthma mortality in Hispanic populations in the United States, Homa and coworkers (22) used national vital statistics data for 1990 through 1995. Age-adjusted annual asthma mortality rate, on a per million basis, was Puerto Ricans 40.9, Cuban-Americans 15.8, and Mexican-Americans 9.2; for comparison, non-Hispanic whites 14.7, and non-Hispanic blacks 38.1. The northeast accounted for 81% of asthma deaths among Puerto Ricans. The authors conclude that Hispanics do not represent a uniform group in terms of health outcome. To estimate the sex-specific incidence of asthma from birth to 44 years, de Marco and coworkers (23) analyzed data on 18,659 participants in the European Community Respiratory Health Survey. During childhood, girls had a lower risk of developing asthma than boys (relative risk [RR]: 0.56 to 0.74). Around puberty, risk was almost equal. After puberty, risk in women was always higher than in men (RR: 1.38 to 5.91). A case-control analysis showed that the greater susceptibility in women was partly explained by their smaller airway caliber. Smoking did not increase risk. The authors conclude that the incidence of asthma shows a sex reversal around puberty. To determine the relationship between attacks of asthma and the menstrual cycle, Zimmerman and coworkers (24) studied 228 women presenting to an emergency department. Exclusions included pregnancy, hormonal therapy, postmenopausal state, and hysterectomy. Only 13% reported reproductive factors as an asthma trigger. Visits in the preovulatory phase (days 5–11) were more frequent (33%) than in the periovulatory phase (days 12–18; 26%), postovulatory phase (days 19–25; 20%), and perimenstrual phase (days 26–4; 21%). Asthma severity was not related to the cycle. The authors conclude that acute asthma is more frequent during the preovulatory phase of the menstrual cycle. Airway Inflammation
Animal models. Inoue and coworkers (25) investigated the contribution of endogenous nitric oxide to airway inflammation and hyperresponsiveness, and the potential involvement of interleukin-8. In transformed cells of the bronchial epithelium of humans, nitric oxide donors increased production of interleukin-8; production was also increased by tumor necrosis factor- plus interleukin-1 plus interferon-, and production was attenuated by a combination of nitric oxide synthase inhibitors (aminoguanidine and N4-nitro-L-arginine methyl ester [L-NAME]). Exposure of guinea pigs to ozone induced airway hyperresponsiveness and increased neutrophils in bronchoalveolar fluid; nitric oxide synthase inhibitors prevented these changes 5 hours after the exposure, and decreased interleukin-8 mRNA expression in epithelial cells. The authors conclude that endogenous nitric oxide may play a role in airway inflammation and hyperresponsiveness caused by ozone, presumably through upregulation of interleukin-8. To determine whether the migration of lymphocytes from the bloodstream is responsible for the increased number of lymphocytes in the lungs of patients with asthma, Schuster and coworkers (26) studied brown Norway rats that were sensitized and challenged with ovalbumin. The bronchoalveolar lavage fluid and lung parenchyma of challenged animals contained increased numbers of CD4 T cells, T cells positive for the interleukin-2 receptor, CD8 T cells, B cells, and natural killer cells. For direct proof of migration, lymphocytes were labeled with a fluorescent dye and injected intravenously the
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day before the aerosol challenge. Challenged animals had 15 times more labeled lymphocytes in lavage fluid than control animals; 52% of labeled cells were CD4 cells and 29% were interleukin-2 receptor positive. The authors conclude that migration from blood contributes to increases in lymphocytes in the lung of this animal model of asthma. CD23, the low-affinity receptor for IgE, is thought to be important in the regulation of IgE production by B cells. In a murine model of allergic sensitization, Haczku and coworkers (27) examined the effects of an antibody to CD23 in CD23deficient and CD23-overexpressing mice. Following exposure to ovalbumin, the antibody to CD23 decreased IgE and IgG1, abolished eosinophilia, and normalized airway hyperreactivity in CD23 overexpressing wild-type mice, but not in CD23 deficient mice. These changes were accompanied by increases in interferon-gamma and decreases in interleukin-4 production, suggesting that the CD23 antibody also affects the imbalance between type 1 (Th1) and type 2 (Th2) helper T cells. Compared with the wild-type mice, the absence of CD23 significantly enhanced the ovalbumin-specific IgE and IgG1 levels, airway eosinophilia, and airway hyperreactivity. The authors conclude that the low-affinity receptor for IgE is not essential for the development of airway hyperreactivity and that its expression is associated with negative regulatory effects on allergic inflammation in mice. Synthetic oligodeoxynucleotides that contain unmethylated CpG motifs are known to stimulate type 1 (Th1) helper T cell responses in mice. In an in vitro study, Fujieda and coworkers (28) determined whether the production of IgE that results from stimulating human peripheral blood monocytes with interleukin-4 and anti-CD40 antibody could be inhibited by oligodeoxynucleotides. IgE production was inhibited by oligodeoxynucleotides containing CGTACG or AACGTT, and also by sequences containing NACGTTCG and A/CTCGTTCG. Both interferon-gamma and interleukin-12 mediated the inhibition of IgE production. The authors conclude that synthetic oligodeoxynucleotides are candidates for treating allergic disease mediated by IgE. A model was developed in mice with severe combined immunodeficiency, whereby the mice are reconstituted with monocytes from patients sensitive to house dust mite, and, on inhaling the mite, the mice develop human IgE. Duez and coworkers (29) examined whether airway hyperresponsiveness occurs in this model. Airway hyperresponsiveness was found to be 2.5 times greater in allergic mice than in the mice that had not been reconstituted, and the degree of responsiveness was correlated with human IgE (r 0.64). The levels of human interleukin-5 were six times higher in allergic mice than in mice that had not been reconstituted, and the level was correlated with the degree of airway hyperresponsiveness. The authors conclude that airway hyperresponsiveness occurs after allergen exposure in this mouse model. Induced sputum. To develop reference standards for cell counts in induced sputum, Belda and coworkers (30) studied 118 healthy subjects. Adequate samples were obtained in 96 subjects. The mean total cell count was 4.1 106 cells per g, and proportions of eosinophils were 0.4%, neutrophils 37.5%, macrophages 58.8%, lymphocytes 1%, and bronchial epithelial cells 1.6%. Female gender and atopy were associated with increased eosinophils. To provide normal reference values for sputum cells, Spanevello and coworkers (31) studied 114 nonatopic nonsmoking volunteers with normal lung function. An adequate sputum sample was produced by 96 subjects (84%). The cell counts were: macrophages 69%, neutrophils 27%, eosinophils 0.6%, lymphocytes 1%, and epithelial cells 1.5%. Only the macrophages and neu-
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trophils conformed to a normal distribution. The authors conclude that the data serve as reference values for future work. To determine the relationship between severity of asthma and airway inflammation, Louis and coworkers (32) studied induced sputum in 74 asthmatic and 22 control subjects with disease severity classified according to the Global Initiative for Asthma (GINA) guidelines. Asthma severity was related to sputum eosinophilia, eosinophil cationic protein, and, less strongly, to sputum neutrophilia and myeloperoxidase. Tryptase, a marker of mast cell activation, was raised in patients with mild-to-moderate asthma. Despite treatment with high doses of corticosteroids, eosinophilic inflammation was prominent. The authors conclude that the severity of persistent asthma is related to airway inflammation that continues despite treatment with corticosteroids. In macrophages, eosinophils, and neutrophils of induced sputum, Taha and coworkers (33) studied expression of two isoforms of prostaglandin H synthase (also termed cyclooxygenase). Patients with asthma and COPD had increased levels of prostaglandin H synthase-1 (the constitutively expressed isoform) and prostaglandin H synthase-2 (the isoform induced by inflammatory stimuli). Levels were higher for asthma than for COPD, and evidence was also found in the airway epithelium and inflammatory infiltrates. The authors conclude that prostaglandin H synthase-2 may contribute to inflammation in patients with asthma. Gauvreau and coworkers (34) characterized the kinetics of basophil and mast cell recruitment to the airways of atopic asthmatic subjects after allergen inhalation. Of 19 subjects, 14 developed both early- and late-phase responses, and 5 developed only early responses. At 7 and 24 hours after allergen challenge, both groups had increased numbers of sputum eosinophils and basophils. The dual, but not early, responders also had an increased number of activated eosinophils and mast cells. Dual responders had higher levels of allergen-induced basophils than early responders, and sputum basophils were correlated with airway hyperresponsiveness at 24 hours (r 0.66). The authors conclude that late responders have higher levels of allergen-induced basophils than early responders, which may contribute to airway hyperresponsiveness. Bronchoalveolar specimens. Although interleukin-16 is one of the earliest chemoattractants found after antigen challenge, little is known about its activity beyond 6 hours. To address this issue, Krug and coworkers (35) performed segmental bronchial challenge in 13 patients with mild asthma. Levels of interleukin-16 in bronchoalveolar fluid were increased 24 hours after the challenge. T-cell chemoattractant activity was increased, and it was correlated with anti-interleukin 16 antibodies (r 0.90) and with the level of Fas ligand expression on CD4 cells (r 0.80). The authors conclude that increased chemotactic activity for T cells in patients with asthma 24 hours after a challenge is mainly attributable to interleukin-16. In patients with atopic asthma, Lamkhioued and coworkers (36) found an increase in monocyte chemoattractant protein-4, a CC chemokine, in bronchoalveolar fluid, and the levels were correlated with eosinophils and eotaxin, a chemokine that causes selective recruitment of eosinophils to sites of inflammation. In bronchial epithelium and submucosa, monocyte chemoattractant protein-4 mRNA and protein was significantly upregulated, and its expression could be induced in these cells by tumor necrosis factor- and interleukin-1. Interferon-gamma acted synergistically in inducing expression of the chemokine, whereas expression was decreased by dexamethasone. The authors conclude that monocyte chemoattractant protein-4 is upregulated in asthmatic airways and it plays a role in the recruitment of eosinophils.
Year in Review
Boulet and coworkers (37) studied two groups of patients with asthma: 16 diagnosed within the preceding 2 years and 16 carrying the diagnosis for at least 13 years. Baseline FEV1 was similar in the two groups, but PC20 on a methacholine challenge (the provocative dose of methacholine causing a 20% decrease in FEV1) was lower in the long-standing group than in the recently diagnosed group (0.44 and 3.37 mg per ml). Bronchial cell counts for CD3, CD4, CD8, CD25, EG1, CD45ro, and AA1 cells were similar in both groups, as was type 1 and type 3 collagen deposition. Inhaled fluticasone proprionate (1,000 g daily) for 8 weeks improved PC20 and decreased EG1, EG2, and AA1 counts equally in both groups, but decreased CD45ro only in the long-standing group. The authors conclude that the degree of airway inflammation and subepithelial fibrosis, and response to inhaled glucocorticoids are similar in patients with recent or long-standing asthma, although airway responsiveness in patients with long-standing asthma cannot be reverted to normal. To determine whether the cellular patterns of airway inflammation differ in atopic and nonatopic asthma, Amin and coworkers (38) did bronchial biopsies in 13 patients with atopic asthma, 9 patients with nonatopic asthma, and 7 healthy controls. Eosinophil and mast cell counts were increased in both asthmatic groups, and higher in patients with atopy. Neutrophils were increased only in nonatopic asthmatic patients. The number of T-lymphocytes (CD3-, CD4-, CD8-, CD25-positive cells) was higher in atopic than nonatopic asthmatic patients. Interleukin-4 and -5 positive cells were found in atopic asthmatic, and interleukin-8 positive cells in nonatopic asthmatic patients. Atopic asthmatic subjects had greater epithelial damage, and a thicker tenascin and laminin layer. In the atopic group, epithelial integrity was correlated with the eosinophil count and the number of CD25-positive cells. The authors conclude that atopic and nonatopic patients with asthma differ in bronchial mucosal membrane and airway inflammation. Blood. The view that atopy results from immune deviation towards activation of type 2 (Th2) helper T cells has arisen from studies mainly performed on purified cells. Because this approach may give an incomplete picture, Magnan and coworkers (39) reassessed the Th1/Th2 paradigm in whole blood from 69 subjects. Atopy was characterized by increased production of interleukin-4, which was correlated with total IgE levels, and by impairment of T cells to produce interferon-gamma, which was correlated with the number of positive skin tests. Asthma was also characterized by increased production of interleukin-4 if atopy was present, and, unexpectedly, by overproduction of interferon-gamma, which was related to increased capacity of CD8 T cells. The number of CD8 T cells producing interferon-gamma was related to asthma severity, bronchial hyperresponsiveness, blood eosinophilia, and interleukin-12 production. The authors conclude that CD8 T cells producing interferongamma are found in the blood of patients with asthma. To examine the influence of leukotrienes and leukotriene inhibitors on eosinophil survival, Lee and coworkers (40) obtained eosinophils and lymphocytes from the peripheral blood of patients with asthma. Eosinophil survival was promoted by leukotriene-B4, LTC4, and LTD4, granulocyte-macrophage colony-stimulating factor, and fibronectin. The increased survival of eosinophils induced by granulocyte-macrophage colony-stimulating factor was reversed by blockade of cysteinyl leukotriene receptors, and inhibition of 5-lipoxygenase and 5-lipoxygenase activating protein; these same compounds also increased basal rates of eosinophil apoptosis (programmed cell death). The authors conclude that the autocrine cysteinyl leukotriene pathway supports eosinophil survival. 1-Acid glycoprotein is an acute-phase protein containing
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five N-linked glycons, which differ in their degree of branching (i.e., relative proportions of di-, tri-, and tetraantennary glycons). To determine the degree of branching (which affects the protein’s immunomodulatory properties), Van Den Heuvel (41) measured plasma concentrations in three groups of patients. Atopic patients with asthma and atopic patients without asthma had normal levels of 1-acid glycoprotein, whereas patients with interstitial lung disease had increased levels. Only the patients with atopic asthma had altered branching, and the increased branching correlated with asthma symptoms, FEV1, response to histamine challenge, and eosinophils. The authors conclude that the changes in branching of 1-acid glycoprotein in asthma indicate an inflammatory reaction and differ markedly from the decreased branching of an acutephase response. Exhaled nitric oxide. In patients with acute asthma, Hunt and coworkers (42) measured the pH of exhaled vapor condensates. The pH was more than 2 log orders lower in the patients than in the controls. The values were highly reproducible and identical to samples from the lower airway. Glucocorticoid therapy caused the values to return to normal. Airway acidity appears to be relevant to asthma because it causes conversion of the endogenous airway compound, nitrite, to nitric oxide in quantities sufficient to account for the concentrations of nitric oxide in exhaled air, and it accelerates necrosis of human eosinophils. The authors conclude that regulation of airway pH plays a previously unsuspected role in asthma pathophysiology. An editorial commentary by Marshall and Stamler accompanies this article (43). To determine the usefulness of noninvasive markers of airway inflammation for monitoring the loss of asthma control, Jatakanon and coworkers (44) induced mild exacerbations of asthma in 15 patients by decreasing the dosage of inhaled glucocorticoids to one-quarter of baseline. Over the subsequent 8 weeks, seven patients developed mild exacerbations and eight did not. Sputum eosinophil count was the only measurement at baseline that discriminated between the groups. Decreases in morning FEV1 and peak expiratory flow were correlated with increases in sputum eosinophils and exhaled nitric oxide. The authors conclude that sputum eosinophils are useful in predicting loss of asthma control. To determine whether increased concentrations of nitric oxide in exhaled gas of asthmatics result from increased production or increased effectiveness of clearance from the airway wall to the lumen, Silkoff and coworkers (45) developed a model of nitric oxide diffusion in the airways. The airways diffusing capacity for nitric oxide was four-fold higher in 25 patients with asthma than in 10 healthy controls, but the concentration of nitric oxide in the airway wall was not different. Inhaled beclomethasone produced a decrease in nitric oxide in the airway wall in the patients, but no change in the nitric oxide diffusing capacity. The authors conclude that the increased airways diffusing capacity for nitric oxide in asthmatic patients may reflect upregulation of nonadrenergic, noncholinergic, nitric-oxide producing nerves in the airways in compensation for a decrease in the sensitivity of airway smooth muscle to the relaxant effects of endogenous nitric oxide. The 36% decrease in exhaled nitric oxide concentration that occurs in asthmatic patients performing repeated FVC maneuvers has been attributed to a decrease in neurally derived nitric oxide consequent to the deep breaths. To address this issue, Deykin and coworkers (46) studied 10 healthy subjects. FVC maneuvers repeated every 15 minutes over 1 hour produced a 25% decrease in mixed expired nitric oxide. Repeated measurements of airway resistance in a body plethysmograph had no effect. The authors conclude that the in-
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crease in exhaled nitric oxide after an FVC maneuver is related to volume history, rather a mechanism involved in the pathobiology of asthma. Symptoms of asthma often decrease or disappear in adolescence, but many subjects later relapse. van Den Toorn and coworkers (47) asked, “Do subjects in remission still have inflamed airways?” Exhaled nitric oxide was higher in 21 adolescents in remission (with no symptoms or medications for at least 1 year) than in 18 healthy controls (19 and 1 ppb), but not different from 21 patients with current asthma (22 ppb). Adolescents in remission had greater bronchial hyperresponsiveness to both methacholine and adenosine-5 -monophosphate (AMP) than the controls, but less than in patients with current asthma. Exhaled nitric oxide was correlated with responsiveness to AMP but not with responsiveness to methacholine. The authors conclude that airway inflammation persists during clinical remission of asthma. To determine whether the increase in exhaled nitric oxide in patients with asthma is mediated through an increase in eosinophils induced by leukotrienes, Deykin and coworkers (48) did bronchoprovocation challenges with methacholine and leukotriene E4 in 16 subjects with atopic asthma. Sputum eosinophils increased by 4.3% after inhaling leukotriene E4 and fell by 1.4% after methacholine. Exhaled nitric oxide did not change with either challenge. The authors conclude that neither leukotriene E4 nor recruitment of eosinophils is sufficient to acutely increase exhaled nitric oxide in patients with asthma. Other exhaled markers. A reaction between nitric oxide and superoxide anions results in the formation of peroxynitrite (a highly reactive oxidant species), which, in turn, reacts with tyrosine residues to form nitrotyrosine (a stable product). Hanazawa and coworkers (49) found that 15 patients with mild asthma had higher concentrations of nitrotyrosine in exhaled breath condensates than had 15 healthy controls (15.3 and 6.3 g/ml). The levels were lower in 12 patients with moderate asthma (5.0 g/ml) and 12 patients with severe asthma (3.3 g/ml). In patients with mild asthma, nitrotyrosine in breath condensate was correlated with exhaled nitric oxide (r 0.65). The authors conclude that nitrotyrosine in exhaled breath condensates may be a marker of oxidative stress in the airways of patients with asthma. Because oxidative stress plays a role in asthma, Paredi and coworkers (50) measured ethane, a product of lipid peroxidation that results from oxidative stress, in 26 patients with asthma. Ethane levels were higher in 12 patients not receiving glucocorticoids (2.1 ppb) than in 14 patients being treated with steroids (0.8 ppb) or 14 healthy controls (0.9 ppb). In patients not receiving steroids, ethane was correlated with nitric oxide (r 0.55) and with the ratio of residual volume to total lung capacity (r 0.60). The authors conclude that exhaled ethane is elevated in patients with asthma and is decreased by glucocorticoid therapy. Heme oxygenase is an antioxidant enzyme that catalyzes the oxidative degradation of heme to produce carbon monoxide and biliverdin. The enzyme has two isoforms: heme oxygenase-2 is constitutively expressed, and heme oxygenase-1 is inducible by agents that lead to oxidant stress. Lim and coworkers (51) investigated the expression of the enzymes in bronchial biopsies from 10 subjects with asthma and 10 healthy controls. Both enzymes were widely distributed in the submucosa, especially in the airway epithelium and submucosal macrophages; extent and intensity were the same in patients and controls. After a month of inhaled budesonide, expression of either enzyme did not change, although airway eosinophils and bronchial hyperresponsiveness decreased; levels of exhaled carbon monoxide were not changed by treatment. The authors conclude that both heme oxygenase isoforms are extensively and
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equally distributed in asthmatic and healthy subjects, and are not modulated by inhaled glucocorticoid therapy. Ex vivo studies. H2 synthase exists in two isoforms: cyclooxygenase (COX)-1, which is constitutively expressed in most cells, and cyclooxygenase (COX)-2, which is induced by inflammatory stimuli. In cells of human airway smooth muscle, Bonazzi and coworkers (52) studied the effect of prostaglandin E2 on the expression of cyclooxygenase-2 induced by interleukin-1. Treatment with exogenous prostaglandin E2 enhanced the expression of cyclooxygenase-2 induced by interleukin-1. A nonselective cyclooxygenase inhibitor decreased the production of prostaglandin E2 and reduced the expression of cyclooxygenase-2 induced by interleukin-1 (supporting a role for endogenous cyclooxygenase metabolites in modulating the expression of cyclooxygenase-2). Administration of blocking agents linked the effect of prostaglandin E2 to the transcriptional level of cyclooxygenase-2 mRNA. The authors conclude that the data support the involvement of prostaglandin E2 in a self-amplifying loop leading to increased biosynthesis of prostaglandin E2 during inflammatory events in the airways. Erjefalt and Persson discussed the degranulation and fate of airway mucosal eosinophils in a pulmonary perspective (53). A series of review articles focus on the question, “Why does inflammation persist in asthma?” (54–57). A comprehensive series of review articles focusing on allergic sensitization in the pathogenesis and maintenance of asthma arose from a symposium on this subject (58–74). A comprehensive series of review articles focusing on antigen processing presentation and immunomodulation arose from a symposium on this subject (75–88). The articles are focused especially on basic processes involved in the response of the respiratory immune system to antigens. Airway Hyperreactivity
Animal models: antigen challenge. To assess the effect of prolonged allergen exposure on the structure and function of airways, Palmans and coworkers (89) studied varying exposures to ovalbumin in sensitized brown Norway rats. Exposure for 2 weeks produced goblet-cell hyperplasia, increased bromodeoxyuridine-positive cells in airway epithelium, increased fibronectin deposition, and thickening of the wall of the inner airway. These changes coincided with increased airway responsiveness to aerosolized carbachol. Exposure for 12 weeks produced increased fibronectin and collagen deposition in the submucosa; neither area of the airway wall nor responsiveness to carbachol differed from controls. The authors conclude that the findings are similar to the airway remodeling in patients with asthma and that changes in the extracellular matrix can enhance or protect against airway hyperreactivity. CD4 T cells are thought to play a major role in initiating and perpetuating airway inflammation associated with the type 2 (Th2) helper T lymphocyte phenotype, but it is not known whether activation of resident specific CD4 T cells is sufficient to induce this phenotype. To address this issue, Knott and coworkers (90) used Balb/c DO11.10 mice that are transgenic for the T-cell receptor specific for the immunodominant epitope of ovalbumin. (A transgenic animal bears a foreign gene [termed a transgene] that is usually spliced to a tissue-specific or cell-specific promoter. The transgene is inserted into a fertilized egg in vitro, and thus becomes integrated into the animal’s germ line. An epitope is the structure on an antigen that is recognized by an antigen receptor.) An aerosol of ovalbumin produced marked neutrophilia and lesser eosinophilia in bronchoalveolar fluid of sensitized DO11.10 mice, but not in wild-type mice. In vivo depletion of CD4, but not CD8, T cells abrogated the response. Cytokines in the lavage fluid were indica-
Year in Review
tive of a type 1 (Th1) helper T cell-like immune response. Neutralizing interferon-gamma caused an increase in the eosinophilia, suggesting that production of interferon-gamma was limiting the development of a Th2 response. Multiple exposures to ovalbumin aerosol failed to induce airway hyperresponsiveness in the DO11.10 mice, unlike in the wild-type mice. The authors conclude that in vivo stimulation of resident CD4 T cells with antigen caused inflammation with characteristics of both a Th1 and Th2 response but was not sufficient to induce airway hyperresponsiveness. To examine the effect of inhibiting several critical molecules of the tyrosine kinase-signaling cascade, Tsang and Fred Wong (91) did in vitro studies of antigen challenge of guineapig airways. Inhibition of transmembrane protein tyrosine kinase caused a decrease in the bronchial contraction that results from anaphylaxis, and it facilitated relaxation. Selective inhibition of mitogen-activated protein kinase failed to suppress the contraction but it facilitated relaxation. In chopped lung, the inhibitors prevented the release of histamine and peptidoleukotrienes in response to allergen. The authors conclude that inhibition of tyrosine kinase signaling cascade can markedly attenuate contraction of the airways during anaphylaxis. Very late antigen-4, also known as 41 integrin, is expressed on eosinophils and lymphocytes and binds to its ligand, vascular-cell adhesion molecule 1. In allergic sheep, Abraham and coworkers (92) showed that BIO-1211, an inhibitor of 4, blocked the early- and late-asthmatic response and airway hyperresponsiveness induced by antigen. The inhibitor reduced eosinophils in bronchoalveolar tissue. The time to recover from airway hyperreactivity induced by antigen was decreased from 9 to 3 days. The authors conclude that an inhibitor of the integrin 41 effectively blocks antigen-induced airway responses. To determine the effect of prostaglandin E2, a product of the cyclooxygenase pathway, on cytokine secretion, Peebles and coworkers (93) used a murine model of allergic sensitization and airway hyperresponsiveness. Mice treated with indomethacin, a nonselective cyclooxygenase inhibitor, had greater airway hyperresponsiveness, increased interstitial eosinophilia, higher levels of interleukin-5 and -13, and increased lung mRNA expression of the CC chemokine, monocyte chemotactic protein (MCP)-1; levels of interleukin-4 and serum IgE were not different. The authors conclude that cyclooxygenase inhibition during allergen sensitization increases hyperresponsiveness of the airways, and causes interstitial eosinophilia and production of interleukin-5 and -13. In Sprague-Dawley rats, depletion of CD8 T cells causes an increase in the late airway response to antigen challenge. Allakhverdi and coworkers (94) used this model to investigate the pattern of chemokine and cytokine production. In CD8 depleted rats, a challenge with ovalbumin produced a 3-fold increase in the late response, accompanied by increased eosinophilic infiltration of the airway, increased expression of eotaxin, and decreased expression of interferon-gamma mRNA; expression of RANTES, monocyte chemoattractant protein-1, and interleukin-4 and -5 was not affected. The authors conclude that CD8 T cells in sensitized rats can suppress the late airway response, possibly through decreasing expression of eotaxin and increasing expression of interferon-gamma mRNA. Because the influx of eosinophils into the lungs is dependent on expression of very late activating antigen-4 (VLA-4), Kanehiro and coworkers (95) investigated the effect of administering an antibody to this antigen in BALB/c mice sensitized and challenged with ovalbumin. When given 2 hours before challenge, the antibody prevented the expected increase in lung resistance. Injecting the antibody from 2 hours before the
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challenge until 42 hours after the challenge prevented the increase in resistance, and inhibited the concentrations of interleukin-5 and leukotrienes in bronchoalveolar fluid. The antibody prevented changes in dynamic compliance and goblet cell metaplasia only if given 2 hours before the challenge. The authors conclude that the timing of administering an inhibitor of very late activating antigen-4 can selectively affect pathologic processes occurring in central and peripheral airways after allergen challenge. Animal models: other challenges and mediators. To determine the effect of pulmonary vascular engorgement on the response to inhaled methacholine, Uhlig and coworkers (96) inflated a balloon in the left atrium of six piglets. Congestion alone increased airway resistance by 15% and tissue resistance by 8%. A small dose of methacholine alone increased airway resistance by 11% and tissue resistance by 42%. The combination of congestion and methacholine increased airway resistance by 68% and tissue resistance by 38%. Morphometry of transverse sections showed that thickness of the inner airway wall was similar in the three groups. Thickness of the outer airway wall was greater in the two congested groups than in the methacholine alone group. The amount of shortening of the airway smooth muscle in the piglets experiencing both congestion and methacholine challenge was greater than in the other two groups. The authors conclude that pulmonary vascular engorgement increases the airway, but not lung tissue, response to inhaled methacholine. To better understand the importance of air pollution in the initiation of asthma, Hamada and coworkers (97) studied neonatal mice that were also exposed to residual oily fly ash, a surrogate for ambient air particles. Repeated exposure of the neonatal mice to allergen alone or pollutant alone had no effect on airway hyperresponsiveness and did not cause antibody production. Adult mice exposed to allergen or allergen plus pollutant did develop airway hyperreactivity, but the combination did not have an additive effect. Neonatal mice exposed to both allergen and pollutant developed greater airway hyperreactivity than on exposure to allergen alone, and reexposure to allergen produced IgE and IgG specific to ovalbumin. The authors conclude that exposure to pollutant aerosols can disrupt normal resistance to sensitization to inhaled allergens, and thereby promote the development of airway hyperreactivity. To assess the relationship between the transcription factor, nuclear factor- B, and acute airway obstruction, Bureau and coworkers (98) studied bronchial cells from horses experiencing heaves (acute airway obstruction that naturally occurs in horses when exposed to moldy hay). Bronchial cells from healthy horses had small amounts of the transcription factor, and all horses developed high levels during heaves. Three weeks later, the level of nuclear factor- B in horses affected by heaves was highly correlated with the degree of residual lung dysfunction. The active complexes of nuclear factor- B were mainly p65 homodimers, rather than the classic heterodimer composed of the p65 and p50 subunits. The activity of these homodimers was paralleled by expression of intercellular adhesion molecule-1. The authors conclude that the kinetics of nuclear factor- B is strongly related to the course of acute airway obstruction in horses. To determine relationships between airway responsiveness and in vitro measurements of smooth-muscle contractility, Duguet and coworkers (99) studied strains of mice with known interstrain differences in airway hyperresponsiveness. The rank order of hyperresponsiveness to methacholine among the strains was the same order as for velocity of shortening in explanted airways. Shortening velocity correlated with the achieved degree of airway narrowing. In contrast, airway hyperresponsiveness
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occurring in vivo did not correlate with generation of isometric tension in the trachealis, morphometric analysis of airway smooth muscle, or tracheal myosin content. The authors conclude that the dynamics of airway smooth muscle are important in understanding airway responsiveness. In guinea pigs, Folkerts and coworkers (100) investigated the role of bradykinin, a metabolite of the kallikrein–kinin system, on airway hyperresponsiveness arising from infection with parainfluenza-3 virus. Hoe 140, a 2-antagonist that also inhibits bradykinin, prevented the airway hyperresponsiveness that usually occurs 4 days after viral infection. Inhalation of bradykinin produced comparable airway hyperresponsiveness in captopril-treated animals. Viral infection produced an influx of cells in bronchoalveolar fluid that could not be prevented by pretreating with Hoe 140. The authors conclude that bradykinin is involved in events causing airway hyperresponsiveness after viral infection without affecting the influx of cells into bronchoalveolar fluid. The protease-activated receptor-2 (PAR-2) belongs to a family of G-protein-coupled receptors that are activated by proteolysis. Ricciardolo and coworkers (101) examined the location of this receptor in guinea pigs and the effect of its activation. The receptor was located in airway epithelial and smooth muscle cells. Trypsin, which cleaves the receptor and exposes an N-terminal tethered ligand (SLIGRL), caused bronchoconstriction that was inhibited by antagonists of tachykinin-NK1 and -NK2 and was potentiated by inhibiting nitric oxide synthase. Trypsin and the N-terminal tethered ligand caused contraction of isolated intrapulmonary bronchi and relaxation of the trachea and main bronchi; inhibitors of cyclooxygenase and nitric oxide synthase abolished the relaxation. Protease-activated receptors-1, -3, and -4 were not involved in the bronchomotor action of trypsin. The authors conclude that proteaseactivated receptor-2 is localized to the guinea-pig airway and is involved in multiple bronchomotor activities. The role of eotaxin, a chemokine that causes selective recruitment of eosinophils to sites of inflammation, in airway hyperresponsiveness is not clear. To address this issue, Fukuyama and coworkers (102) instilled eotaxin into the trachea of guinea pigs. Eosinophils accumulated in the airways but not in the alveoli, and airway hyperresponsiveness was not altered even when eotaxin was combined with subthreshold doses of interleukin-5 or leukotriene D4. Eotaxin combined with platelet-activating factor enhanced airway hyperresponsiveness, and produced a larger increase in eosinophils and peroxidase activity in bronchoalveolar fluid than seen with eotaxin alone. The authors conclude that eotaxin alone causes eosinophil accumulation in airways but not airway hyperresponsiveness, and that additional factors, such as platelet-activating factor, are needed to activate eosinophils for the development of airway hyperresponsiveness. Because heparin attenuates exercise-induced asthma, Suzuki and Freed (103) determined whether it would inhibit hyperventilation-induced bronchoconstriction in a canine model of exercise-induced asthma. Aerosolized heparin had no effect on baseline peripheral airway resistance, measured with a wedged bronchoscope. Heparin achieved a 50–60% decrease in bronchoconstriction caused by hyperventilation. Despite causing acute infiltration of macrophages and eosinophils into bronchoalveolar fluid, pretreatment with heparin attenuated or abolished the release of leukotrienes, prostaglandins, and thromboxane consequent to hyperventilation. The authors conclude that inhaled heparin inhibits the production and release of eicosanoid mediators caused by hyperventilation with dry air and attenuates hyperventilation-induced bronchoconstriction. Endotoxin is thought to contribute to pulmonary hyperre-
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sponsiveness in asthma and the acute respiratory distress syndrome. In an isolated mouse lung, Held and Uhlig (104) studied the effect of endotoxin on airway and vascular hyperreactivity. Infusion of lipopolysaccharide induced hyperreactivity of the airways to methacholine and of the pulmonary vasculature to platelet-activating factor. Both forms of hyperreactivity were completely prevented by blocking the thromboxane/endoperoxide receptor. Blocking cyclooxygenase-2 abolished vascular hyperreactivity, but it had only a marginal effect on airway hyperreactivity. Pretreatment with an oxygen-radical scavenger, N-acetylcysteine, partly protected against the increase in airway hyperreactivity. The authors conclude that endotoxin induces airway and vascular hyperreactivity by activating the thromboxane/endoperoxide receptor, that vascular hyperactivity depends on cyclooxygenase-2 activity, and that airway hyperactivity largely depends on other mechanisms. Ex vivo studies. Because in vitro contractility of human airways depends on sensitization status, Ammit and coworkers (105) asked whether increased contractility of sensitized airways was related to differences in content of isoforms of myosin light-chain kinase in smooth muscle. Immunoblotting of bundles of smooth muscle from five subjects with and five subjects without sensitized airways showed that the major isoform of myosin light-chain kinase was of the smooth muscle type. Sensitized airways contained about three times more myosin light-chain kinase; the content of myosin heavy chain did not differ. The authors conclude that an increase in myosin light-chain kinase in smooth muscle may be responsible for the increased contractile reactivity in sensitized tissue. Airway smooth muscle may participate in the airway inflammatory response by expressing various cytokines, but the intracellular signal regulating cytokine expression in airway smooth muscle has not been determined. Maruoka and coworkers (106) examined the role of p38 mitogen-activated protein (MAP) kinase and extracellular signal-regulated kinase (Erk) in the production of RANTES, a member of the C-C chemokine family, by airway smooth muscle cells that had been stimulated by platelet-activating factor and by tumor necrosis factor-. Platelet-activating factor induced the threonine and tyrosine phosphorylation of p38 mitogen-activated protein kinase and extracellular signal-regulated kinase. SB 203580 almost completely inhibited p38 mitogen-activated protein kinase activity, and PD98059 almost completely inhibited extracellular signal-regulated kinase activity. Both inhibitors acted additively to inhibit the production of RANTES induced by platelet-activating factor. The authors conclude that both p38 mitogen-activated protein kinase and extracellular signal-regulated kinase are involved in the production of RANTES by airway smooth muscle cells that are stimulated by platelet-activating factor. To determine whether smooth muscle in human bronchi contains ryanodine calcium-release channels and the associated calcium-induced calcium release (CICR) mechanism, Hyvelin and coworkers (107) obtained bronchial muscle samples during thoracotomy. Ryanodine and caffeine induced transient increases in cytoplasmic calcium concentration. Higher doses of ryanodine inhibited the caffeine-induced response, as did inhibitors of the calcium-induced calcium release mechanism. Additional studies revealed the existence of mRNAs encoding only the type 3 ryanodine calcium-release channel. The authors conclude that functional ryanodine calcium-release channels are present in human bronchial smooth muscle. To examine the relationship between allergic inflammation and changes in the production of extracellular matrix proteins by human smooth muscle, Johnson and coworkers (108) used an in vitro model of hyperresponsiveness (passive sensitiza-
Year in Review
tion). Sera from asthmatic patients caused smooth muscle cells to produce increased amounts of fibronectin, perlecan, laminin 1, and chondroitin sulfate. Beclomethasone did not reverse the increase in extracellular matrix protein. The authors conclude that an interaction between the allergic process and airway smooth muscle may alter components of the airway wall in asthma, and that glucocorticoids do not prevent the fibrosis induced by resident cells within the airways. In patients with asthma, desquamation of airway epithelial cells is often attributed to airway inflammation. Because this finding might be an artifact, Ordonez and coworkers (109) did bronchial biopsies in 14 subjects with mild-to-moderate asthma and 12 healthy subjects. The percentage of basement membrane denuded of epithelium was 11.4% in asthmatic subjects and 14.8% in healthy subjects. The percentage of basement membrane covered by a single layer of basal cells was 46% in asthmatic subjects and 55% in healthy subjects. Neither measurement was correlated with FEV1 or PC20 on methacholine provocation. The authors conclude that denudation of the bronchial epithelium in endobronchial biopsies is an artifact of tissue sampling. Early and late asthmatic responses. To determine the effect of allergen inhalation on eicosanoid mediators, Macfarlane and coworkers (110) sampled airway secretions in 14 patients with a confirmed late asthmatic response. At baseline, the percentage of eosinophils was correlated with the level of cysteinyl leukotrienes (r 0.84), but not with prostaglandin D2 or prostaglandin E2. Allergen challenge produced a 3.5-fold increase in cysteinyl leukotrienes, which were correlated with the eosinophilia (r 0.55), but no change in prostanoid mediators. The authors conclude that cysteinyl leukotrienes, but not prostanoids, are involved in the late asthmatic response. To determine whether the late asthmatic response could be predicted from baseline characteristics, Avila and coworkers (111) analyzed data in 60 subjects undergoing an allergen challenge. A fall in FEV1 of at least 15% between 3 and 7 hours occurred in 57% of the subjects. Classification tree analysis revealed that a threshold of 0.25 mg per ml for the PC20 on a methacholine challenge (dose producing a 20% decrease in FEV1) was the best predictor of a late response: 87% of subjects below this dose developed a late response compared with 38% of subjects above that dose. Baseline FEV1 or sputum eosinophils did not predict the late response. The authors conclude that a methacholine challenge helps in identifying subjects likely to develop a late response to an allergen challenge. Platelet-activating factor, an important lipid mediator in the pathogenesis of asthma, is degraded by platelet-activating factor-acetylhydrolase, resulting in inactive lyso-platelet activating factor. In 14 patients with asthma, Henig and coworkers (112) did a double-blind crossover study of the effect of recombinant platelet-activating factor-acetylhydrolase on the early and late response to allergen challenge. The early and late responses, sputum eosinophils, eosinophilic cationic protein, and tryptase were not influenced. The authors conclude that recombinant platelet-activating factor-acetylhydrolase was not effective in patients with dual asthmatic responses to allergen. Prostaglandin E2 inhibits the early and late response to allergen inhalation. To determine the mechanism of its bronchoprotective action, Hartert and coworkers (113) did a double-blind crossover study in 10 atopic asthmatic patients. Nebulized prostaglandin E2 was well tolerated; it caused a decrease in the levels of prostaglandin D2 in bronchoalveolar fluid that result with allergen challenge. The authors conclude that prostaglandin E2 blocks the early asthma response by decreasing prostaglandin D2. Because cyclosporin A is known to inhibit the late asth-
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matic reaction and the associated increase in blood eosinophils, Khan and coworkers (114) studied 24 atopic subjects to determine whether the effect was mediated by cytokines and chemokines. Cyclosporin A inhibited allergen-induced increases in interleukin-5 and granulocyte-macrophage colonystimulating factor in bronchoalveolar cells. The authors conclude that inhibition of the late asthmatic response by cyclosporin A may be related to inhibitory effects on eosinophilassociated cytokines and chemokines. Antigen and methacholine challenge. Persistent asthma is associated with deposition of extracellular matrix proteins, which may be mediated by release of matrix metalloproteinases and tissue inhibitor of metalloproteinase-1. To advance understanding, Kelly and coworkers (115) measured metalloproteases in bronchoalveolar fluid after segmental bronchoprovocation in 17 allergic subjects. Concentrations of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 were increased in the airway, but not in the serum, at 48 hours. Matrix metalloproteinase-9 was the predominant form, and it was correlated with airway neutrophils and less so with alveolar macrophages. The authors conclude that antigen challenge leads to the generation of matrix metalloproteinases, which may lead to remodeling in asthma. In patients being screened for bronchial hyperresponsiveness, Fowler and coworkers (116) compared methacholine and adenosine monophosphate challenges. Of 185 patients, 76% responded to methacholine and 56% responded to adenosine monophosphate. For those unresponsive to adenosine monophosphate, 57% responded to methacholine. For those unresponsive to methacholine, 11% responded to adenosine monophosphate. Patients who responded only to methacholine had a lower FEV1 and were receiving a higher dose of inhaled glucocorticoids. Subjects with the glycine allele at codon 16 had increased bronchial hyperresponsiveness to methacholine, but not to adenosine monophosphate. The authors conclude that a methacholine challenge is a more sensitive screening tool than a challenge with adenosine monophosphate. Guidelines for methacholine and exercise challenge testing are presented in an ATS statement (117). Exercise-induced asthma. Because of the suggestion that intense physical training may cause airway hyperresponsiveness, Langdeau and coworkers (118) compared the prevalence of physician-diagnosed asthma and airway hyperresponsiveness in 100 athletes involved in high-level competitions with 50 sedentary subjects. The prevalence of airway hyperresponsiveness in the controls was 28% versus 49% in the athletes; the prevalence was especially high in athletes breathing humid air (76%) or cold air (52%) during training. Parasympathetic tone, detected by a measure of heart rate variability, was increased in the athletes and weakly correlated with the PC20 on methacholine challenge. The authors conclude that airway hyperresponsiveness is increased in athletes, possibly because of the content of air inhaled during training. Because asthma-like symptoms are common in cross-country skiers, Karjalainen and coworkers (119) characterized the morphologic changes in the bronchial mucosa in 40 competitive skiers without a diagnosis of asthma, 12 subjects with mild asthma, and 12 healthy controls. Skiers had a 43-fold increase in T-lymphocytes, 26-fold increase in macrophages, and 26fold increase in eosinophils over the controls; respective values in the asthmatic subjects were 70-fold, 63-fold, and 8-fold. Skiers had twice the number of neutrophils as asthmatic subjects, whereas mast cell counts were normal. Expression of tenascin, an extracellular matrix protein in the basement membrane, was increased 8-fold in the skiers and 11-fold in the asthmatic subjects, and did not correlate with the inflamma-
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tory cell counts. The authors conclude that repeated exposure to poorly conditioned air may induce inflammation and remodeling in the airways of competitive skiers. Inhalation of mannitol provides an osmotic stimulus that identifies subjects who develop exercise-induced asthma. To improve understanding of its mechanism, Brannan and coworkers (120) did a randomized double-blind trial of necrodomil, which was given before progressively increasing doses of mannitol. The dose of mannitol producing a 15% decrease in FEV1 was increased 2.6-fold after necrodomil, and FEV1 never decreased by 15% in half of the subjects. The authors conclude that necrodomil significantly inhibits the airway response to inhaled mannitol. Exercise-induced bronchoconstriction is associated with increased airway osmolarity, resulting from water loss, and alterations in airway temperature, resulting from heat loss. To define the mechanisms involved, Hashimoto and coworkers (121) developed a model exposing human bronchial epithelial cells to hyperosmolarity, and cooling and rewarming. In this model, the production of RANTES, a member of the C-C chemokine family, and interleukin-8 was inhibited by beclo– methasone diproprionate and budesonide, but these agents failed to prevent the release of p38 mitogen-activated protein (MAP) kinase and c-Jun NH2-terminal kinase (JNK). The authors conclude that interleukin-8 and RANTES are produced in a model of hyperosmolarity and cooling and rewarming, and their production is inhibited by inhaled glucocorticoids. In 10 subjects with mild asthma, Gauvreau and coworkers (122) asked, “Is exercise-induced bronchoconstriction associated with airway inflammation and hyperresponsiveness?” Exercise produced a 21% fall in FEV1, which was comparable to the fall achieved with inhaled methacholine (30%) and inhaled allergen (29%). Allergen inhalation produced hyperresponsiveness and increased sputum eosinophils, whereas exercise had no effect on inflammatory cells or airway hyperresponsiveness. The authors conclude that exercise-induced bronchoconstriction does not cause airway inflammation or hyperresponsiveness. Because hyperemia of the bronchial circulation could contribute to the airway narrowing associated with hyperpneainduced bronchospasm, Kaminsky and Lynn (123) measured pulmonary blood volume in this setting. Hyperpnea produced a 26% decrease in FEV1 in 13 subjects with asthma, but neither diffusing capacity nor pulmonary capillary blood volume changed. The authors conclude that hyperpnea-induced bronchospasm is not accompanied by change in pulmonary capillary blood volume. Drugs. To determine whether angiotensin II receptors are involved in bronchial hyperresponsiveness, Myou and coworkers (124) did a double blind crossover study of losartan, a type 1 receptor antagonist, in 8 patients with asthma. Losartan produced an increase in PC35-PEF40 (the concentration of methacholine producing a 35% fall in standardized partial expiratory flow at 40% of FVC). The authors conclude that angiotensin II type 1 receptors are involved in bronchial hyperresponsiveness in asthmatic patients. A series of review articles focus on the question, “What makes the airways contract abnormally in asthma?” (125–129). Other Pathophysiological Mechanisms in Asthma
Tachykinins, neural activity. Because inhaling cigarette smoke causes transient bronchoconstriction through acting on pulmonary C-fiber afferent endings, Wu and coworkers (130) asked whether the effect would be enhanced in the presence of airway hyperresponsiveness. In guinea pigs sensitized with aerosolized ovalbumin, inhalation of cigarette smoke produced a
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6.3% greater increase in lung resistance than in nonsensitized controls. Smoke also produced greater increases in substance P-like immunoreactivity and calcitonin gene-related peptidelike immunoreactivity in bronchoalveolar fluid. Pretreatment with a selective neurokinin-2 receptor antagonist inhibited more than 85% of the enhanced bronchoconstrictive response to cigarette smoke. The authors conclude that airway hyperresponsiveness increases the bronchoconstrictive response to inhaled cigarette smoke, and that activation of lung C-fibers by endogenous tachykinins plays a primary role in this response. In rats, Ho and coworkers (131) investigated the action of prostaglandin E2 on vagal C-fiber afferents. Infusion of prostaglandin E2 did not alter baseline activity of vagal C-fibers but it markedly enhanced the effect of capsaicin, a potent and selective stimulant of these fibers. Prostaglandin E2 also increased the response of C-fibers to lactic acid, adenosine, and lung inflation, but it did not alter the responses of either slowly adapting or rapidly adapting pulmonary receptors to inflation. The authors speculate that release of prostaglandin E2 may contribute to the dyspnea and airway irritation caused by airway inflammation. Sensory innervation of the airway originates from afferent neurons whose somata reside in the superior (jugular) and inferior (nodose) vagal ganglia. In guinea pigs immunized with ovalbumin, Moore and coworkers (132) investigated whether airway inflammation caused by inhaling antigen would unmask neurokinin-2 tachykinin responses in vagal afferent somata. Within 24 hours of allergen inhalation, exogenously applied tachykinins acting on neurokinin-2 receptors depolarized 80% of nodose neurons. Vagotomy attenuated the antigen-induced unmasking of tachykinin responses. The authors conclude that the vagus is involved in the transduction of a signal essential for unmasking of tachykinin responses. Because toluene diisocyanate stimulates the release of substance P from sensory neurons in the airways, Hunter and coworkers (133) determined whether it also affected the levels of substance P and preprotachykinin mRNA in the sensory neurons that innervate the nasal epithelium. Fisher-344 rats were exposed to a vapor of toluene diisocyanate for 2 hours. The level of substance P in nerve fibers was increased at 12, 24, and 48 hours after exposure. The proportion of cell bodies expressing high levels of preprotachykinin mRNA was increased at 24 and 48 hours. The authors conclude that inhalation of toluene diisocyanate increases release of substance P and the levels of neuropeptide within nerve fibers of the nasal epithelium. To determine the effect of nerve growth factor on vagal neurons containing substance P, Hunter and coworkers (134) used immunochemistry and retrograde tracing techniques. In the trachea of untreated guinea pigs, more than 99% of neurons containing substance P were located in the jugular ganglia. These neurons were small in diameter (23 m) and negative for neurofilament immunoreactivity. In contrast, neurons in the nodose ganglia were large (40 m), did not contain substance P, and were positive for neurofilament immunoreactivity. Injections of nerve growth factor- into the tracheal wall caused 10% of the nodose neurons to become positive for substance P. The authors conclude that nerve growth factor increases expression of substance P in airway neurons, but also changes the neuronal phenotype such that large nodose neurons provide a component of the tachykinergic innervation. Because inhaled furosemide attenuates cough, bronchoconstriction, and dyspnea, Sudo and coworkers (135) examined its effects on tracheobronchial receptors of spontaneously breathing rats. Receptors were classified on the basis of single or pauci unit recordings from the vagus nerve. The slope of airway pressure versus spike frequency of slowly
Year in Review
adapting receptors was increased from 9 to 15 Hz per cm H2O by inhalation of furosemide. The activity of rapidly adapting receptors was attenuated by furosemide. The authors conclude that inhaled furosemide sensitizes slowly adapting receptors and desensitizes rapidly adapting receptors. Because of the link between the neurogenic and immune systems, Maghni and coworkers (136) assessed the effect of selectively inhibiting neurokinin-1 and -2 receptors on the airway inflammatory response in atopic rats sensitized to ovalbumin. Neither antagonist prevented the early airway response to allergen challenge, whereas both antagonists blocked the late response. The neurokinin-2, but not neurokinin-1, antagonist decreased bronchoalveolar eosinophilia, and both helper T cell Th1 (interferon-gamma) and Th2 (interleukin-4 and -5) cytokine expression in bronchoalveolar cells. The authors conclude that neurokinins are linked to the regulation of cytokine expression in cells without discrimination as to their phenotype, and that the dichotomy between neurokinin receptors has therapeutic implications. To determine whether trypsin, which activates protease-activated receptors 2 and 4, induces release of neurokinins from the sensory C-fibers that innervate airways of guinea pigs, Carr and coworkers (137) studied the isolated bronchus. Trypsin evoked contractions in proportion to its concentration, and the contractions were markedly attenuated in the presence of neurokinin receptor antagonists. Capsaicin, which depletes neurokinins in sensory nerves, also decreased trypsin’s ability to produce contractions. Trypsin did not evoke action potentials in C-fiber afferents whose receptive fields were located in the trachea or main bronchi. The authors conclude that trypsin enables the local release of sensory neurokinins from afferent C-fibers and that this release occurs independently of the sensory functions of these nerves. Deep inspiration bronchoconstriction. In healthy subjects, a deep inspiration produces bronchodilation and it also produces bronchoprotection. To determine which effect is stronger, Scichilone and coworkers (138) performed methacholine challenges at two doses in 10 healthy subjects. A bronchodilation index was derived from spirometry after methacholine, and a bronchoprotection index was derived from spirometry before methacholine. With mild obstruction (decrease in FEV1 of 10– 20%), the bronchodilator and bronchoprotector effects of a deep inspiration were equal. With greater obstruction (decrease in FEV1 of 20–40%), the bronchoprotector effect was twice as strong. The authors conclude that the bronchoprotector effect of lung inflation is stronger than the bronchodilator effect. When airway smooth muscle is contracted, a deep inhalation causes bronchodilation in healthy subjects and causes bronchoconstriction in asthmatic subjects. Reasoning that the difference relates to the dynamic behavior of airway smooth muscle and lung parenchyma, Brown and Mitzner (139) studied this issue in anesthetized dogs using high-resolution computed tomography. When the airways were contracted with methacholine, rapid lung inflation caused the airways to dilate at only one-quarter the rate of the parenchyma. The authors conclude that the slower dynamic response of the contracted airway probably involves intrinsic properties of the smoothmuscle contractile process. Healthy subjects develop a decrease in airway resistance with deep inspiration, whereas patients with asthma develop an increase in resistance or no change. Because usual pulmonary function tests do not measure airway dimensions with sufficient precision to resolve the different behaviors, Mitzner and Brown (140) measured the dimensions with direct imaging. Normal tidal stresses allowed airway smooth muscle to respond normally to deep inspiration. Removing tidal stresses after methacholine was sufficient to change the normal bron-
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chodilator response to a deep inspiration into an abnormal contraction response. The authors conclude that alterations in sensitivity of airway smooth muscle to normal tidal stresses may be involved in the pathogenesis of asthma. Blood flow. In 19 patients with mild asthma who had never used glucocorticoids, Brieva and coworkers (141) found that blood flow in their airway mucosa was 26% higher than in 12 healthy controls. Inhaled albuterol increased mucosal blood flow by 27% in the controls, but had no effect in the patients. A 2-week course of inhaled fluticasone (440 g daily) decreased mucosal blood flow by 11% in the patients, and restored its responsiveness to albuterol. The authors conclude that blood flow in the mucosa of asthmatic airways has a subnormal response to albuterol, which may be caused by airway inflammation. Because the vasoconstrictive action of corticosteroids on the skin (skin blanching) is used to assess relative potency, Kumar and coworkers (142) examined whether inhaled fluticasone causes vasoconstriction in the airway mucosa. At baseline, blood flow in the airway mucosa was 25% higher in 10 asthmatic than in 10 healthy subjects. Fluticasone decreased mucosal blood flow by 37% in the patients and by 21% in the controls; the change was transient and values approached normal after 90 minutes. The authors conclude that measurement of airway mucosal blood flow may provide a more relevant test of the potency of inhaled corticosteroids than skin blanching. Immunology. Because autoimmunity may explain the link between asthma and chronic inflammation of the airways mediated by T cells, Arnold and coworkers (143) measured the expression of perforin, a cytotoxic molecule implicated in autoimmunity. The percentage of lymphocytes expressing perforin was higher in 20 patients with asthma than in 18 controls. The subpopulations of lymphocytes with increased expression of perforin were CD3, CD4, CD5, and CD56 in 13 patients with extrinsic asthma, and CD4 and CD56 in 7 patients with intrinsic asthma. The authors conclude that allergic and intrinsic asthma is associated with increased expression of perforin in T-lymphocyte subsets. Airway narrowing. In 7 patients with asthma, Kaminsky and coworkers (144) determined the mechanisms responsible for increased resistance in the peripheral airways. The stop flow method during bronchoscopy was used to measure the decay of segment pressure over time. The absence of a sudden drop in pressure and its smooth decay suggest that airway resistance was negligible. The authors conclude that peripheral airway resistance in patients with asthma is predominantly located in the collateral airways rather than in the more proximal airways. To assess the presence and characteristics of airway wall thickening in patients with asthma, Niimi and coworkers (145) did helical computed tomography of the apical bronchus of the right upper lobe in 81 patients with asthma and 22 healthy controls. Airway wall thickness was increased in 13 patients with mild asthma, 39 patients with moderate asthma, and 22 patients with severe asthma, but not in 7 patients with intermittent asthma. Wall area alone, and corrected for body surface area, was weakly correlated with duration and severity of asthma, FEV1, and FEV1/FVC. Airway luminal area was not related to severity of disease. Intraobserver and interobserver reproducibility was good. The authors conclude that thickening of the airway wall in patients with asthma is not limited to those with severe disease, and the degree of thickening relates to the duration and severity of the disease. To determine the relationship between spirometric measures of airway obstruction and the area of the airway lumen, Brown and coworkers (146) performed high-resolution computed tomography and partial spirometry in five healthy subjects challenged with increasing doses of methacholine who
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were prohibited from taking a deep breath. Increasing doses of methacholine decreased progressively the airway area, reaching down to 80% of baseline. Change in airway area was correlated with partial FEV1 (r 0.46). The authors conclude that spirometric change consequent to methacholine is associated with decreased area of the conducting airways. King and coworkers (147) developed an automated algorithm for analyzing images of the lumen and wall thickness of airways seen on high-resolution computed tomography. For tubes of varying size, embedded in Styrofoam and scanned at different angles, the algorithm provided accurate estimates of the area of airway lumen; the area of the airway wall was overestimated in proportion to airway size. In two excised and inflated pig lungs, the mean error for area of the airway lumen was 0.52 mm2 and for area of the airway wall it was 0.17 mm2. The authors conclude that their automated algorithm provides accurate measurements of airway dimensions on high-resolution computed tomography. Remodeling. To determine whether structural remodeling alters the mechanical properties of the airways, Brackel and coworkers (148) used esophageal balloons and probes at five locations between the right lower lobe and midtrachea in 10 patients with asthma and 14 controls. Plots of area versus transmural pressure revealed a larger cross-sectional area in men than in women. Specific airway compliance was decreased in downstream locations. It was also decreased in the patients, although the difference from controls became less marked towards the trachea. The authors conclude that stiffening of the airways suggests the occurrence of remodeling in asthma. Classic mechanics. In 18 asthmatic patients (mean age 59 years) with irreversible lung function despite aggressive treatment, Gelb and Zamel (149) investigated the mechanism of airflow limitation. All patients had markedly abnormal flow– volume curves and hyperinflation, normal computed tomography, normal transdiaphragmatic strength, and normal or elevated diffusing capacity. All but three patients had marked loss of static elastic recoil pressure of the lung. Loss of lung elastic recoil explained the flow limitation on maximal expiration in only four elderly patients, and then only at low lung volumes. The loss of elastic recoil in the other 11 patients was estimated to account for 35–55% of the decrease in maximal expiratory flow. The authors conclude that loss of elastic recoil is unexpectedly common in patients with persistent asthma, and the mechanism of this loss is not known. To determine whether excessive airway narrowing during early expiration increases the vulnerability of asthmatic patients to severe attacks, in ‘t Veen and coworkers (150) compared 13 patients with difficult-to-control asthma and 15 patients with asthma of equal severity but easy to control. Patients were matched for sex, age, atopy, FEV1, and response to methacholine challenge. The patients did not differ in total lung capacity, residual volume, or slope of phase 3 on a singlebreath nitrogen washout. Patients with difficult-to-control asthma had a higher closing volume than the easy-to-control group (160 and 99% predicted), and a higher closing capacity (114 and 100% of predicted). The authors conclude that airway closure at a relatively high volume under stable conditions is a risk factor for severe exacerbations of asthma. A state-of-the-art review on asthma, from bronchoconstriction to airway inflammation and remodeling, was published by Bousquet and coworkers (151). Treatment
-Agonists. Because inhaled -agonists have been linked with cardiovascular mortality, Au and coworkers (152) examined
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whether their use was linked with myocardial infarction. Using data from a health maintenance organization, they identified 1,444 cases with an incident myocardial infarction and matched them with 4,094 controls. Subjects who filled one prescription for a -agonist inhaler in 3 months before their index date had a 1.7-fold increased risk of myocardial infarction; increased risk was limited to subjects with a history of cardiovascular disease, and among the latter group to new users of -agonists. The authors conclude that clinicians should exert caution in the initial prescription of a -agonist to patients with cardiovascular disease. Inhaled glucocorticoids. To determine whether inhaled glucocorticoids modulate the expression of nuclear factor- B, Hart and coworkers (153) did a double-blind, crossover study of inhaled fluticasone propionate (500 g twice daily) versus placebo in 15 patients with mild asthma. Fluticasone decreased the number of eosinophils in bronchoalveolar fluid and airway tissue, and reduced bronchial hyperresponsiveness; DNA-binding in macrophages and bronchial tissue was not affected. The authors conclude that the action of glucocorticoids in asthma may not involve binding and activation of nuclear factor- B. Jaffuel and coworkers (154) determined the transcriptional potencies of five inhaled glucocorticoids. The rank order for potency of trans-activation (i.e., increase in the transcription of genes involved in either beneficial or certain side effects) was fluticasone budesonide and triamcinolone beclomethasone and flunisolide. The rank order for the potency of transrepression (i.e., inhibition of the transcription factors nuclear factor- B and activator protein 1) was fluticasone budesonide beclomethasone, triamcinolone, and flunisolide. The authors conclude that determining the trans-repression potency of glucocorticoids may help predict capacity to produce antiinflammatory effects, while determining trans-activation potency may help predict side effects. To define the mechanisms by which inhaled glucocorticoids regulate allergen-mediated airway inflammation, Kelly and coworkers (155) did a double-blind crossover study of budesonide (400 g twice daily) for 4 weeks. Budesonide improved FEV1, attenuated both the early and late response to allergen, prevented the increase in bronchial hyperresponsiveness after allergen challenge, and decreased allergen-induced airway eosinophilia. Budesonide decreased the generation of interleukin-5 and interferon-gamma by bronchoalveolar cells; production of interleukin-5 was correlated with number of airway eosinophils (r 0.61) and level of eosinophil-derived neurotoxin (r 0.57). The authors conclude that budesonide reduces airway cell generation of interleukin-5, which then decreases circulating eosinophils and their availability for recruitment to the airway after allergen exposure. To compare the duration of action of two inhaled glucocorticoids, Miller-Larson and coworkers (156) instilled budesonide or fluticasone into the trachea of adrenalectomized rats, followed by instillation of lipopolysaccharide. When the glucocorticoids were instilled 1 hour before lipopolysaccharide, both agents reduced tumor necrosis factor- by 70% and mononuclear cells by 55%, without altering neutrophils. When instilled 6 hours before lipopolysaccharide, only budesonide produced a 59% decrease in tumor necrosis factor- and a 47% decrease in mononuclear cells. Systemic activity did not differ. The authors conclude that budesonide exerts a more prolonged topical anti-inflammatory action than fluticasone, possibly because of its reversible fatty acid esterification within airway tissue. Because dosage of aerosolized medications is commonly adjusted to age or body weight, Onhoj and coworkers (157) com-
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pared plasma concentrations in three groups of subjects inhaling a fixed dose of budesonide (4,000 g) from an inhaler and spacer: 8 children aged 2–3 years; 8 children aged 4–6 years; and 10 adults aged 20–41 years. The dose delivered to the patient (estimated as the delivered dose of the batch measured in vitro minus drug recovered from equipment, face and mouth rinses) was similar for the three age groups. Systemic exposure, estimated as area under the plasma concentration plotted over time, and terminal half-life were also similar in the three age groups. That adults had the same plasma concentrations as children for the same dose, despite a larger body size, indicates that lung deposition increases with age. The authors conclude that the same nominal dose of budesonide can be used in children and adults without increased risk of systemic toxicity. To determine the relative effect of two widely used topical glucocorticoids, Nielsen and Dahl (158) did a double-blind study in 66 patients with asthma. Patients were randomized to three consecutive 2-week periods of either fluticasone propionate (500, 1,000, and 2,000 g daily) or budesonide (800, 1,600, and 3,200 g daily). The relative potency of fluticasone to budesonide was 2.5 for PD20 on a bronchial methacholine challenge, and 0.6 for 24-hour urinary cortisol. The differential therapeutic ratio, based on PD20 and urinary cortisol, was 4.2. The authors conclude that the therapeutic ratio over a wide range of doses favors fluticasone over budesonide. In an in vitro study, Gauvreau and coworkers (159) examined the effect of inhaled budesonide on the common progenitor cell for eosinophils and basophils, the eosinophil/basophil colony-forming unit. Subjects with mild asthma were treated with budesonide or placebo for 8 days and then underwent allergen challenge. Budesonide decreased the eosinophilia after allergen by 39%, the eosinophil/basophil colony-forming unit by 34%, and the localization of granulocyte-macrophage colony-stimulating factor in these units by 35%; interleukin-5 was not affected. The authors conclude that inhaled budesonide attenuated the increase in circulating eosinophils induced by allergen and their progenitors grown in the presence of granulocyte-macrophage colony-stimulating factor. Glucocorticoids. To characterize the inflammatory process in glucocorticoid-dependent patients with asthma, Gagliardo and coworkers (160) examined cytokine release by peripheral blood mononuclear cells and dysregulation of the glucocorticoid receptor. Mononuclear cells released increased amounts of interleukin-8 and granulocyte-macrophage colony-stimulating factor in nine steroid-dependent patients; in contrast, the release of these cytokines was inhibited by a 10-day course of prednisolone in six patients with asthma who had previously been untreated. In the steroid-dependent group, release of the cytokines from the mononuclear cells was inhibited in vitro by glucocorticoids. The glucocorticoid receptor , the functional receptor, was similar in all groups and dominant over glucocorticoid receptor , the negative form of the receptor. The authors conclude that the persistent release of interleukin-8 and granulocyte-macrophage colony-stimulating factor in glucocorticoid-dependent patients is not associated with low expression of glucocorticoid receptor- or overexpression of glucocorticoid receptor . An editorial commentary by Leung and Chroussos (161) accompanies this article. Muscarinic antagonists. To determine whether high-dose ipratropium bromide combined with albuterol would be superior to albuterol alone in acute asthma, Rodrigo and Rodrigo (162) did a randomized double-blind trial in 180 patients presenting to the emergency room. Patients received both agents from an inhaler and spacer every 10 minutes for 3 hours (2,800 g albuterol, 504 g ipratropium). The combination achieved 48% greater improvement in FEV1 than albuterol alone, and
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decreased hospital admission by 49%. Subgroup analysis showed the patients most likely to benefit were those with FEV1 less than 30% predicted and those with symptoms for more than 24 hours before presenting to the emergency room. To determine the role of muscarinic receptors in the control of histamine release from airways, Reinheimer and coworkers (163) isolated human bronchi and rat tracheae and stimulated them with a calcium ionophore, which causes release of histamine. The released histamine was not blocked by acetylcholine or oxotremorine in the rat trachea, whereas acetylcholine suppressed 86% of the effect of released histamine in the human bronchus. The M1 subtype of the muscarinic receptor was found to be responsible for the inhibitory control of mast cell function in human airways. The authors conclude that a species difference exists in the cholinergic control of histamine release between human and rat airways. Leukotriene inhibitors. Because patients with asthma vary in their response to leukotriene inhibitors, Hasday and coworkers (164) determined whether patients differed in the production in leukotrienes after exposure to allergen. Of 18 patients with asthma exposed to segmental ragweed challenge, only 9 had at least a 4-fold increase in sulfidopeptide leukotrienes (LTC4/D4/E4) in bronchoalveolar fluid 24 hours after the challenge; the increase in the other 9 subjects was less than 2.2-fold. The high leukotriene producers also had increased LTB4, total protein, interleukin-5, interleukin-6, tumor necrosis factor-, and eosinophils. Treatment with the 5-lipoxygenase inhibitor, zileuton, decreased the eosinophil count by 68% in the high leukotriene producers, but had no effect in the low producers. The authors conclude that leukotriene inhibitors may be more effective in a subset of asthmatic patients. A comprehensive series of review articles focusing on leukotrienes as targets for treatment of asthma and other diseases arose from a symposium on this subject (165–194). The articles are focused especially on potential new areas and new indications where current and future antileukotriene drugs may have a place in the treatment of different diseases. Combination regimens. In 349 patients with asthma, Shapiro and coworkers (195) did a randomized comparison of four treatments: salmeterol 50 g, fluticasone 250 g, combination of salmeterol 50 g and fluticasone 250 g, and placebo. Each was given twice daily through a Diskus device. At 12 weeks, mean change in FEV1 was greater for the combination (0.48 L) than for salmeterol (0.05 L), fluticasone (0.25 L), or placebo (0.11 L). Patients receiving the combination used less supplemental albuterol, had fewer nighttime awakenings, and were less likely to drop out of the study because of symptoms. Adding a long-acting 2-agonist to a low dose of inhaled corticosteroid achieves better control of asthma, but may mask airway inflammation. To address this possibility, Kips and coworkers (196) randomly assigned 60 patients to three treatments: budesonide 400 g, budesonide 800 g, and budesonide 200 g plus formoterol 12 g. Over 1 year of treatment, the proportion of eosinophils, EG2 cells, other inflammatory cells, or levels of eosinophilic cationic protein in sputum were not different for combination therapy versus high-dose budesonide, nor did clinical control differ. The authors conclude that sputum markers of airway inflammation are not different in patients treated with low-dose budesonide plus formoterol than in patients treated with high-dose budesonide. Because regular use of -agonists may impair the antiinflammatory effects of glucocorticoids, Aldridge and coworkers (197) undertook a randomized, crossover comparison of 6 weeks of treatment with regular terbutaline (4 mg/day), regular budesonide (800 g/day), combined treatment, and placebo in 28 patients with mild-to-moderate asthma. The PD15
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for saline decreased (0.57-fold decrease) with terbutaline versus placebo, and it decreased (0.65-fold decrease) with combined therapy versus budesonide alone. The PD20 for methacholine was not affected by terbutaline, either alone or combined with budesonide. Eosinophils in sputum were higher in patients receiving terbutaline alone than placebo (8.3 and 4.4%); eosinophils were the same for terbutaline plus budesonide versus terbutaline alone. The authors conclude that -agonists have a permissive effect on airway inflammation. In 360 patients already receiving high-dose inhaled glucocorticoids (1,000–4,000 g/day), Virchow and coworkers (198) did a double-blind study of the benefit of adding a leukotriene receptor antagonist. Zafirlukast (80 mg twice daily) produced improvement in morning PEFR, symptom score, and use of 2-agonist; it also achieved a 39% decrease in the risk of exacerbations and a 60% decrease in the need for increase in controller medications. The authors conclude that adding zafirlukast improves asthma management in patients already taking high doses of inhaled glucocorticoids. Spoelstra and coworkers (199) determined whether budesonide and formoterol could inhibit the activation of eosinophils by fibroblast-conditioned medium. Applied directly to eosinophils while they were being stimulated by fibroblastconditioned medium, budesonide inhibited the modulation of CD11b and L-selectin; formoterol did not cause inhibition. On indirect testing, both medications inhibited lung fibroblast activation, resulting in diminished eosinophil activation. The authors conclude that budesonide inhibits eosinophil activation, primarily through effects on lung fibroblasts but also through a direct action; in contrast, formoterol inhibits eosinophil activation only through inhibitory effects on lung fibroblasts. Current understanding, recommendations, and unanswered questions about refractory asthma are discussed in the summary of an ATS workshop (200). Specific Clinical Scenarios
Nocturnal asthma. Because airway resistance normally decreases as lung volume increases, Irvin and coworkers (201) asked whether this relationship is found in patients with asthma after they fall asleep. In five patients with nocturnal asthma, changes in lung volume, achieved by varying negative pressure in a cuirass surrounding the chest wall, resulted in the expected changes in pulmonary resistance when patients were awake. After 30 minutes of sleep, functional residual capacity fell but resistance increased more than predicted for the decrease in lung volume. Raising lung volume to the level during wakefulness did not change resistance. The authors conclude that sleep causes an immediate uncoupling of the normal relationship between airway resistance and lung volume in patients with nocturnal asthma. Because uncertainty about the relationship between gastroesophageal reflux and nocturnal asthma may be the result of methodological limitations in previous studies, Cuttitta and coworkers (202) measured continuously and simultaneously esophageal pH and respiratory resistance during the night in seven patients with asthma who had moderate-to-severe reflux. Resistance was increased at the end of each reflux episode, and the severity and duration of airway narrowing were proportional to the duration of gastroesophageal reflux. The authors conclude that gastroesophageal reflux per se is capable of eliciting nocturnal bronchoconstriction, and the severity and duration of the bronchoconstriction are proportional to the duration of reflux. To determine the prevalence and severity of gastroesophageal reflux in patients with asthma, Harding and coworkers
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(203) performed esophageal manometry and 24-hour esophageal pH testing in 26 patients without reflux symptoms. Esophageal acid contact times were abnormal in 62% of the patients; these patients had higher amounts of exposure of the proximal esophagus to acid than did another group of asthmatic patients with complaints of reflux. Demographic variables did not predict the patients with abnormal tests. The authors conclude that gastroesophageal reflux occurs in patients with asthma, even when symptoms are absent. Acute severe and fatal asthma. The normal lung contains a network of elastic fibers that form discrete longitudinal bundles in the submucosa of the bronchial tree. Carroll and coworkers (204) compared the area and content of these bundles in health, nonfatal asthma, and fatal asthma (12 cases of each). The area of the bundles in patients with fatal asthma was twice as great as in the controls. Myofibroblasts and collagen content were increased in both asthmatic groups. The number of mucosal folds was related to the number of longitudinal bundles, but did not differ between fatal and nonfatal asthma. The authors conclude that changes in the structural proteins of the airway wall in patients with asthma affect the longitudinal as well as the transverse mechanical properties of the airways. In 10 patients with acute severe asthma progressing to acute respiratory failure, Ordonez and coworkers (205) assessed airway inflammatory events by analyzing tracheal aspirates collected within 12 hours of intubation. The number of neutrophils in tracheal aspirates was 10 times higher than in control subjects undergoing intubation for elective surgery. The number of eosinophils was also increased, but was oneeighth the number of neutrophils. Interleukin-8, a chemoattractant for neutrophils, was 19 times higher in the patients, and the level correlated with duration of mechanical ventilation (r 0.74). The authors conclude that neutrophils are the dominant inflammatory leukocyte of the airway inflammation of acute severe asthma, and that interleukin-8 is an important mediator of the neutrophilia. To determine whether interleukin-5 and CC chemokines are involved in status asthmaticus, Tillie-Leblond and coworkers (206) studied 10 patients with status asthmaticus requiring mechanical ventilation, 4 patients receiving mechanical ventilation for nonrespiratory reasons, 11 patients with asthma, and 8 healthy controls. Patients with status asthmaticus had higher levels of monocyte chemotactic protein-1, macrophage inflammatory peptide-1, RANTES (regulated on activation, normal T-cell expressed and secreted), and interleukin-5 than the other three groups; levels of monocyte chemotactic protein-3 and eotaxin were not different. Eosinophilic chemotactic activity was increased in bronchoalveolar fluid of both asthmatic groups, and higher in patients with status asthmaticus; activity was inhibited by neutralizing antibodies against interleukin-5, monocyte chemotactic protein-3, eotaxin, and RANTES. The authors conclude that patients with status asthmaticus have increased levels of various CC chemokines and interleukin-5 in their airways. If airway remodeling is related to duration of asthma, then the airways of older individuals with asthma should be thicker than those of younger individuals. To address this issue, Bai and coworkers (207) made measurements in 13 young (17–23 years) and 13 older (40–49 years) subjects with fatal asthma, and also age-matched controls. Wall area was greater in older asthmatic subjects, primarily due to greater adventitial area; young asthmatic subjects did not differ from controls. Within muscle bundles, the connective tissue matrix around individual cells was increased in asthmatic subjects, and unrelated to age. After adjustment for this change, smooth muscle area was still 4-fold greater in older and 2-fold greater in young asthmatic subjects. Area narrowing was increased in both asthmatic groups, but
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more so in older individuals. Intraluminal obstruction and subepithelial collagen were greater in asthmatic subjects, and unrelated to age. The authors conclude that airway wall area and airway narrowing increase with the duration of severe asthma. Dyspnea. Moy and coworkers (208) asked, “Does the quality of dyspnea differ between the bronchospastic and mechanical load components of mild asthma?” Eight patients described dyspnea according to a 19-item list. Of 26 trials of methacholine bronchoprovocation, “chest tightness” or “constriction” was chosen 92% of the time, whereas they were chosen for only 3% of the 72 trials of breathing through external resistors. The authors conclude that the sensation of chest tightness in mild asthma is distinct from that of effort and it is not related to the imposed mechanical load. Symptom perception and respiratory sensation in asthma are discussed in the summary of an NHLBI workshop by Banzett and colleagues (209). Quality of life. An understanding of variation in quality of life among patients with asthma may be important in assessing factors influencing health services. Osman and coworkers (210) administered two general quality of life scales (SF-12 and SF-38) and a specific respiratory quality of life scale (St. George’s Respiratory Questionnaire) to 396 adults with mild asthma. Physician contact for asthma in the year after the interview was related to the score on the three scales. When adjusted for symptoms at the time of the interview, however, only the respiratory scale predicted prospective physician contact. In 50 patients with symptomatic asthma, Juniper and coworkers (211) compared two instruments for measuring asthma control. The Asthma Control Questionnaire was completed in clinic, and was based on a patient’s recall and included a single measure of FEV1. An Asthma Control Diary was completed twice daily, and included daily measures of PEFR. Over a 9-week period, concordance between the two instruments was high (intraclass correlation coefficient 0.87), but the questionnaire achieved better reliability and responsiveness. The authors conclude that the questionnaire is stronger and more discriminating than the diary. Age. In 75 patients with asthma who were older than 60 years, Cassino and coworkers (212) found that 51% had been diagnosed for more than 26 years (median 40 years) and the remainder had asthma of shorter duration (median 9 years). FEV1 was lower in patients with a longstanding diagnosis than in those with a more recent diagnosis (60 and 74% predicted); FEV1 was related to the duration of asthma (r 0.26). Functional residual capacity was higher in patients with long-standing asthma (143 versus 124% predicted). Bronchodilator therapy achieved a normal FEV1 in 50% of patients with recently diagnosed asthma, but in only 18% of the patients with a long-standing diagnosis. The authors conclude that the degree of airflow limitation and hyperinflation is associated with the duration of asthma. Differential diagnosis: eosinophilic bronchitis. Eosinophilic bronchitis is characterized by chronic cough and sputum eosinophilia, but, unlike asthma, airflow obstruction and airway hyperresponsiveness are not found. Brightling and coworkers (213) measured inflammatory mediators in induced sputum in 8 patients with eosinophilic bronchitis, 17 patients with asthma matched for sputum eosinophil count (13%), and 10 healthy controls. Compared with controls, patients with eosinophilic bronchitis had a 1.6-fold increase in cysteinyl-leukotrienes and a 6.4-fold increase in eosinophilic cationic protein; values in patients with asthma were increased 1.9- and 7.7-fold, respectively. Patients with eosinophilic bronchitis had 6.7 times more histamine and 11 times more prostaglandin D2 in their sputum than asthmatic patients. The authors conclude that eosinophilic bronchitis is associated with increased release of inflammatory mediators in the airways.
Occupational Asthma
Diisocyanates. To determine the outcome of asthma induced by diisocyanates, Piirila and coworkers (214) studied 235 patients. Ten years after diagnosis, 82% reported symptoms of asthma and 35% used medication regularly. Patients with IgE antibodies to diisocyanates had 73% fewer asthmatic symptoms, and shorter duration of symptoms, latency period, and duration of exposure than IgE-negative patients. Patients with asthma due to hexamethylene (39% of the group) used 59% less medication than patients with asthma induced by diphenylmethane diisocyanate (39%) or toluene diisocyanate (17%). The authors conclude that asthma induced by diisocyanates is persistent, and a more favorable outcome is associated with IgE mediation and hexamethylene diisocyanate inducement. Diisocyanates are a leading cause of occupational asthma. Wisnewski and coworkers (215) identified proteins in epithelial cells of the human lung that become conjugated with hexamethylene diisocyanate, the most commonly used diphatic diisocyanate. After in vitro exposure of human airway epithelial cells to hexamethylene diisocyanate, keratin 18 and actin were identified as prominent conjugated proteins. After an in vivo inhalation of a hexamethylene diisocyanate aerosol, keratin 18 was identified as the predominant diisocyanate-conjugated protein in human endobronchial samples. The authors conclude that keratin and other proteins are potential carriers for diisocyanates, and conjugation of these proteins with hexamethylene diisocyanate may contribute to diisocyanateinduced asthma. High molecular weight agents. Because high molecular weight agents are related to the development of occupational asthma, Monso and coworkers (216) studied individuals commencing an apprenticeship involving exposure to such agents to determine whether health-related factors caused some to drop out. Of 769 apprentices, 89 (11.6%) quit. Of the quitters, 74 participated in the study. A history of hay fever was a significant determinant of quitting (odds ratio [OR] 1.7). In animal health technology programs, the main determinants of quitting were specific immunological sensitization at baseline and symptoms of asthma. The authors conclude that individuals quitting apprenticeships in certain occupations may be self-selected on the basis of health problems. Farmers. To determine the prevalence of symptoms of obstructive lung disease among European crop farmers, Monso and coworkers (217) analyzed data on 4,793 farmers from Denmark, Germany, Switzerland, and Spain. Reported symptoms included: wheezing 15%, asthma 3%, nasal allergy 14%, chronic phlegm 12%, organic dust exposure syndrome 15%, and symptoms at work 22%. On multivariate analysis, flower growing was a risk factor for asthma (OR 2.1), and cultivating oil plants was associated with symptoms at work (OR 1.4) and chronic phlegm (OR 1.3). The authors conclude that flower and oil plant production is associated with increased risk of respiratory symptoms in European crop farmers. Prevalence and severity. In a randomly selected population, Johnson and coworkers (218) studied the prevalence, determinants, and characteristics of occupational asthma. An initial questionnaire was completed by 18,701 subjects, and 2,974 of them attended the laboratory; of these, 383 carried a physician-made diagnosis of asthma. Subjects were classified as probable occupational asthma (if they developed asthma while working in a high-risk job) and possible occupational asthma (if they reported exposure to a substance that may cause asthma at the time of developing asthma). The prevalence of probable or possible occupational asthma was 36% among asthmatic subjects. Nursing was the occupation most commonly associated with probable occupational asthma, and
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clerical or food preparation for possible occupational asthma. The population attributable risk for adult-onset asthma in high-risk occupations was 18%. The authors conclude that recording occupation alone without assessing exposure may underestimate the prevalence of occupational asthma. To determine the frequency of hospitalization among workers with occupational asthma, Liss and coworkers (219) analyzed data in 844 subjects receiving compensation for occupational asthma. Compared with workers with musculoskeletal injuries, those with occupational asthma were 40% more likely to be hospitalized for all causes, 5.4 times more likely for respiratory disease, and 28 times more likely for asthma. Factors associated with increased hospitalization were older age and exposure to agents other than isocyanates. The authors conclude that workers with occupational asthma have higher rates of hospitalization than other workers. Natural history. To define the natural history of occupational asthma, Gautrin and coworkers (220) prospectively determined the incidence of work-related skin sensitization in a cohort of apprentices. Of 769 apprentices, 91% attended at least one visit during 6 to 44 months of follow-up, and 16% of these developed specific sensitization. The incidence of workrelated sensitization (per person-year) was 8.9% in animal health, 4.2% in pastry making, and 2.5% in dental hygiene programs. In animal health, risk of sensitization was increased by atopy, respiratory symptoms in the pollen season, and the number of hours in contact with rodents. The authors conclude that an apprenticeship in animal health technology carries a greater risk of developing specific sensitization than do apprenticeships in pastry making and dental hygiene. Many workers with occupational asthma recover completely on leaving the workplace, but it is not known whether they develop an asthmatic reaction on re-exposure to an offending agent. To address this issue, Lemiere and coworkers (221) studied 16 asymptomatic workers with normal lung function who had previously been diagnosed with asthma caused by high-molecular weight agents (flour, psyllium, or guar gum). The workers underwent a specific inhalation challenge in the same manner as at the time of diagnosis, 5.7 years before. Of the 16 workers, 11 developed an asthmatic reaction of the same severity as at the time of original diagnosis. Over the 5.7 years, specific IgE fell by 31% in the 11 responders and by 87% in the 5 nonresponders. The authors conclude that workers with occupational asthma remain sensitive to offending agents despite loss of asthmatic symptoms, and increased sensitivity is associated with specific immunization to the agent.
ALLERGIC RHINITIS Risk Factors
To determine risk factors for the onset of asthma and allergic rhinitis, Plaschke and coworkers (222) analyzed data from 1,370 subjects. Onset of allergic rhinitis was associated with sensitivity to birch (OR 6.5), sensitivity to Parietaria (OR 7.4), pets (OR 3.0), and being female (OR 1.9). Onset of asthma was associated with allergic rhinitis (OR 4.9), sensitization to pets (2.4), and smoking (OR 3.0). Among atopics, onset of asthma was associated with allergic rhinitis (OR 5.7). Among nonatopics, onset of asthma was associated with rhinitis (OR 3.5) and smoking (OR 5.7). The authors conclude that risk factors for the onset of allergic rhinitis are sensitization to pollen and pets, and risk factors for onset of asthma are allergic rhinitis, sensitization to pets, and smoking. In the transitional epithelium of the nose, ozone induces epithelial hyperplasia and mucous cell hyperplasia. To determine the role of neutrophils in causing these injuries, Cho and
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coworkers (223) used antiserum against neutrophils. Rats treated with the antiserum had 90% fewer circulating neutrophils than control rats. After 3 days of exposure to ozone, antiserum-treated rats had 89% fewer infiltrating neutrophils, 66% less stored mucosubstances, and 58% less mucous cells in the nasal transitional epithelium. Antiserum had no effect on ozone-induced epithelial cell proliferation or upregulation of mucin mRNA. The authors conclude that mucous cell metaplasia caused by ozone is dependent on neutrophils, whereas epithelial cell proliferation and mucin gene upregulation are independent of neutrophils. Quality of Life
To determine the relative burden and interaction of asthma and allergic rhinitis on quality of life, Leynaert and coworkers (224) analyzed answers to the SF-36 questionnaire by 850 participants in the European Community Respiratory Health Survey. Subjects who had allergic rhinitis alone were more likely to report problems with social activities and poorer mental health than were subjects without allergic rhinitis or asthma. Subjects who had both asthma and allergic rhinitis experienced more physical limitations than did patients with allergic rhinitis alone. Asthma did not impair social or mental health in subjects with allergic rhinitis. Inflammation and Hyperreactivity
To determine whether the respiratory epithelium of aspirinsensitive and aspirin-tolerant patients with rhinosinusitis differ in local production of eicosanoids, Kowalski and coworkers (225) cultured epithelial cells from removed nasal polyps. Without stimulation, epithelial cells from 10 aspirin-sensitive patients generated about one-third the amount of prostaglandin E2 generated by the aspirin-tolerant patients. The nasal level of 15-hydroxyeicosetetraenoic acid (15-HETE) did not differ between the groups. This eicosanoid increased 3.6 times when the cells of aspirin-sensitive patients were incubated with aspirin; no such change occurred in the aspirin-tolerant patients. The authors conclude that the epithelial cells in nasal polyps of aspirin-sensitive patients have abnormalities in eicosanoid generation. Because the link between airway inflammation and hyperresponsiveness is not clear, Sanico and coworkers (226) investigated the role of nerve growth factor as a mediator of increased sensorineural responsiveness. In 20 subjects with allergic rhinitis, concentrations of nerve growth factor protein were increased in nasal fluid and nerve growth factor mRNA was decreased in superficial nasal scraping. Nasal provocation with allergen produced an increase in nerve growth factor protein in nasal fluid in subjects with allergic rhinitis, but not in the controls; concentration of the protein did not change with histamine provocation. The authors conclude that expression and release of nerve growth factor in mucosa occurs in allergic rhinitis. To elucidate the mechanism of mucous hypersecretion in allergic inflammation, Shimizu and coworkers (227) developed a rat model of nasal allergy consisting of hypertrophy and metaplasia of goblet cells in the nasal epithelium in response to ovalbumin exposure. In this model, mucus production was inhibited by dexamethasone and by an inhibitor of cysteinyl-leukotrienes; eosinophilic infiltration was inhibited by a histamine-1 antagonist, dexamethasone, and anti-rat neutrophil antiserum. Instillation of lipopolysaccharide induced intraepithelial mucus production, which was inhibited by dexamethasone, indomethacin, and anti-rat neutrophil antiserum; an antagonist of cysteinyl-leukotrienes had no effect. The authors conclude that cysteinyl-leukotrienes may have a role in antigen-mediated mucus production, that eosinophil infiltra-
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tion does not relate to mucus production, and that different mechanisms control mucus production in allergic inflammation and endotoxin stimulation. To compare mucosal inflammation in the upper and lower airways of patients with allergic rhinitis, Braunstahl and coworkers (228) studied eight grass pollen-sensitive patients with allergic rhinitis but free of asthma. Segmental bronchial provocation produced an increase in eosinophils in blood and in bronchial mucosa (both challenged and unchallenged regions) at 24 hours. Eosinophils and eotaxin-positive cells were increased in the nasal lamina propria, and expression of interleukin-5 was increased in the nasal epithelium. The challenge produced nasal and bronchial symptoms and impaired function of both. A challenge in eight healthy controls had no effect. The authors conclude that patients with allergic rhinitis develop blood eosinophilia and allergic inflammation of the nose after a segmental bronchial provocation. To study the effect of a topical glucocorticoid on the response of the nasal mucosa to allergen challenge, Linden and coworkers (229) did a double-blind crossover trial in nine subjects with allergic rhinitis. Allergen challenge produced acute nasal symptoms, which peaked at 30 minutes and then tapered. Undiluted mucosal fluids from the nose revealed increased levels of granulocyte-macrophage colony-stimulating factor and interleukin-5 at 3, 5, 7, and 9 hours. Topical budesonide (256 g), 30 minutes before the challenge, had no effect on the symptoms but inhibited the increase in mediators. The authors conclude that granulocyte-macrophage colony-stimulating factor and interleukin-5 are induced in a nonsymptomatic, latephase response to nasal allergen challenge, and that this cytokine response is prevented by a single dose of budesonide. To determine the influence of airway production of cytokines on the outcome of rhinovirus infection, Gern and coworkers (230) studied 22 subjects with allergic rhinitis or asthma. Experimental infection with rhinovirus 16 produced neutrophilia in blood, and increases in granulocyte colonystimulated factor, interleukin-8, and neutrophils in nasal secretions. Granulocyte colony-stimulating factor in nasal secretions was correlated with nasal neutrophils (rs 0.87) and blood neutrophils (rs 0.69), and nasal neutrophils were correlated with interleukin-8 (rs 0.75). Similar relationships were seen in sputum, but the levels were more modest. The ratio of interferon-gamma-to-interleukin 5 mRNA, an indicator of the balance between T-helper cell type 1 (Th1) and Th2like cytokines, was inversely correlated with both the peak of cold symptoms (rs 0.60) and with the time of viral clearance. The authors conclude that airway interleukin-8 and granulocyte colony-stimulating factor are closely associated with neutrophilic inflammation during rhinovirus infection, and the balance between Th1- and Th2-like cytokines may influence outcome of common colds. Treatment
To assess the effect of ipratropium bromide on the nose’s ability to condition cold, dry air, Assanasen and coworkers (231) did a double-blind crossover study in healthy nonallergic subjects. Ipratropium (84 g) was sprayed into the nose 15 minutes before inspiring cold, dry air from a nasal mask. The nasal conditioning capacity, calculated by measuring the temperature and humidity of air entering and leaving the nose, was increased by ipratropium. Ipratropium lessened the fall in nasal volume resulting from cold, dry air, but it did not alter the decrease in nasal surface temperature. The authors conclude that ipratropium bromide increases the ability of the nose to condition cold, dry air. To assess the influence of nasal polyposis on pulmonary
function, Lamblin and coworkers (232) followed 46 patients over 4 years. At baseline, 34% of the patients had asthma and 54% had bronchial hyperresponsiveness. All 46 patients were initially treated with topical glucocorticoids for 6 weeks, and 39% experienced a decrease in nasal symptoms. Intranasal ethmoidectomy was performed in the nonresponders. Despite improvement in nasal symptoms in both groups at 1 and 4 years, patients not responding to topical glucocorticoids had a decrease in FEV1 at 4 years. The authors conclude that patients with nasal polyposis unresponsive to topical glucocorticoids develop worsening airway obstruction. Because the efficacy of specific immunotherapy in asthma is controversial, Grembiale and coworkers (233) did a doubleblind trial in 44 subjects with both perennial rhinitis and bronchial hyperresponsiveness. One year after monodesensitization to Dermatophagoides pteronyssinus (house dust mite), subjects had a 2.9-fold increase in PD20 (the provocative dose of methacholine producing a 20% decrease in FEV1); at the end of 2 years, PD20 increased to 4-fold. Although 9% of subjects in the placebo group developed asthma, none of the immunotherapy subjects did. The authors conclude that specific immunotherapy decreases airway hyperresponsiveness in carefully selected subjects with allergic rhinitis. In 14 patients with both allergic rhinitis and asthma, Wilson and coworkers (234) compared the efficacy of a 2-week course of an inhaled glucocorticoid (budesonide 400 g) combined with an intranasal glucocorticoid (budesonide 200 g) versus a histamine receptor antagonist (citirizine 10 mg orally) combined with a leukotriene receptor antagonist (montelukast 10 mg orally). Both treatments achieved equivalent improvements in peak flow. Bronchial hyperreactivity was improved with the histamine and leukotriene receptor antagonists, but not with the glucocorticoid combination. Exhaled nitric oxide was suppressed by glucocorticoids but not by the receptor antagonists. The authors conclude that combined mediator blockade and combined topical glucocorticoids were equally effective for controlling asthma in patients with both asthma and allergic rhinitis. References 1. Ulbrecht M, Hergeth MT, Wjst M, Heinrich J, Bickeboller H, Wichmann HE, Weiss EH. Association of 2-adrenoreceptor variants with bronchial hyperresponsiveness. Am J Respir Crit Care Med 2000;161:469–474. 2. Laitinen T, Ollikainen V, Lazaro C, Kauppi P, de Cid R, Anto JM, Estivill X, Lokki H, Mannila H, Laitinen LA, Kere J. Association study of the chromosomal region containing the FCER2 gene suggests it has a regulatory role in atopic disorders. Am J Respir Crit Care Med 2000;161:700–706. 3. Hizawa N, Yamaguchi E, Jinushi E, Kawakami Y. A common FCER1B gene promoter polymorphism influences total serum IgE levels in a Japanese population. Am J Respir Crit Care Med 2000;161:906–909. 4. Oryszczyn MP, Annesi-Maesano I, Charpin D, Paty E, Maccario J, Kauffmann F. Relationships of active and passive smoking to total IgE in adults of the Epidemiological Study of the Genetics and Environment of Asthma, Bronchial Hyperresponsiveness, and Atopy (EGEA). Am J Respir Crit Care Med 2000;161:1241–1246. 5. Fryer AA, Bianco A, Hepple M, Jones PW, Strange RC, Spiteri MA. Polymorphism at the glutathione S-transferase GSTP1 locus. A new marker for bronchial hyperresponsiveness and asthma. Am J Respir Crit Care Med 2000;161:1437–1442. 6. Palmer LJ, Burton PR, Faux JA, James AL, Musk AW, Cookson WO. Independent inheritance of serum immunoglobulin E concentrations and airway responsiveness. Am J Respir Crit Care Med 2000;161: 1836–1843. 7. Summerhill E, Leavitt SA, Gidley H, Parry R, Solway J, Ober C. 2-Adrenergic receptor Arg16/Arg16 genotype is associated with reduced lung function, but not with asthma, in the Hutterites. Am J Respir Crit Care Med 2000;162:599–602. 8. Thomas NS, Wilkinson J, Lonjou C, Morton NE, Holgate ST. Linkage
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oligodeoxynucleotides inhibit IgE induction in human lymphocytes. Am J Respir Crit Care Med 2000;162:232–239. Duez C, Kips J, Pestel J, Tournoy K, Tonnel AB, Pauwels R. House dust mite-induced airway changes in hu-SCID mice. Am J Respir Crit Care Med 2000;161:200–206. Belda J, Leigh R, Parameswaran K, O’Byrne PM, Sears MR, Hargreave FE. Induced sputum cell counts in healthy adults. Am J Respir Crit Care Med 2000;161:475–478. Spanevello A, Confalonieri M, Sulotto F, Romano F, Balzano G, Migliori GB, Bianchi A, Michetti G. Induced sputum cellularity. Reference values and distribution in normal volunteers. Am J Respir Crit Care Med 2000;162:1172–1174. Louis R, Lau LC, Bron AO, Roldaan AC, Radermecker M, Djukanovic R. The relationship between airways inflammation and asthma severity. Am J Respir Crit Care Med 2000;161:9–16. Taha R, Olivenstein R, Utsumi T, Ernst P, Barnes PJ, Rodger IW, Giaid A. Prostaglandin H synthase 2 expression in airway cells from patients with asthma and chronic obstructive pulmonary disease. Am J Respir Crit Care Med 2000;161:636–640. Gauvreau GM, Lee JM, Watson RM, Irani AM, Schwartz LB, O’Byrne PM. Increased numbers of both airway basophils and mast cells in sputum after allergen inhalation challenge of atopic asthmatics. Am J Respir Crit Care Med 2000;161:1473–1478. Krug N, Cruikshank WW, Tschernig T, Erpenbeck VJ, Balke K, Hohlfeld JM, Center DM, Fabel H. Interleukin 16 and T-cell chemoattractant activity in bronchoalveolar lavage 24 hours after allergen challenge in asthma. Am J Respir Crit Care Med 2000;162:105–111. Lamkhioued B, Garcia-Zepeda EA, Abi-Younes S, Nakamura H, Jedrzkiewicz S, Wagner L, Renzi PM, Allakhverdi Z, Lilly C, Hamid Q, Luster AD. Monocyte chemoattractant protein (MCP)-4 expression in the airways of patients with asthma. Induction in epithelial cells and mononuclear cells by proinflammatory cytokines. Am J Respir Crit Care Med 2000;162:723–732. Boulet LP, Turcotte H, Laviolette M, Naud F, Bernier MC, Martel S, Chakir J. Airway hyperresponsiveness, inflammation, and subepithelial collagen deposition in recently diagnosed versus long-standing mild asthma. Influence of inhaled corticosteroids. Am J Respir Crit Care Med 2000;162:1308–1313. Amin K, Ludviksdottir D, Janson C, Nettelbladt O, Bjornsson E, Roomans GM, Boman G, Seveus L, Venge P. Inflammation and structural changes in the airways of patients with atopic and nonatopic asthma. BHR Group. Am J Respir Crit Care Med 2000;162:2295–2301. Magnan AO, Mely LG, Camilla CA, Badier MM, Montero-Julian FA, Guillot CM, Casano BB, Prato SJ, Fert V, Bongrand P, Vervloet D. Assessment of the Th1/Th2 paradigm in whole blood in atopy and asthma. Increased IFN-gamma-producing CD8 T cells in asthma. Am J Respir Crit Care Med 2000;161:1790–1796. Lee E, Robertson T, Smith J, Kilfeather S. Leukotriene receptor antagonists and synthesis inhibitors reverse survival in eosinophils of asthmatic individuals. Am J Respir Crit Care Med 2000;161:1881–1886. Van Den Heuvel MM, Poland DC, De Graaff CS, Hoefsmit EC, Postmus PE, Beelen RH, Van Dijk W. The degree of branching of the glycans of 1-acid glycoprotein in asthma. A correlation with lung function and inflammatory parameters. Am J Respir Crit Care Med 2000;161:1972–1978. Hunt JF, Fang K, Malik R, Snyder A, Malhotra N, Platts-Mills TA, Gaston B. Endogenous airway acidification. Implications for asthma pathophysiology. Am J Respir Crit Care Med 2000;161:694–699. Marshall HE, Stamler JS. NO waiting to exhale in asthma. Am J Respir Crit Care Med 2000;161:685–687. Jatakanon A, Lim S, Barnes PJ. Changes in sputum eosinophils predict loss of asthma control. Am J Respir Crit Care Med 2000;161:64–72. Silkoff PE, Sylvester JT, Zamel N, Permutt S. Airway nitric oxide diffusion in asthma: role in pulmonary function and bronchial responsiveness. Am J Respir Crit Care Med 2000;161:1218–1228. Deykin A, Massaro AF, Coulston E, Drazen JM, Israel E. Exhaled nitric oxide following repeated spirometry or repeated plethysmography in healthy individuals. Am J Respir Crit Care Med 2000;161: 1237–1240. van Den Toorn LM, Prins JB, Overbeek SE, Hoogsteden HC, de Jongste JC. Adolescents in clinical remission of atopic asthma have elevated exhaled nitric oxide levels and bronchial hyperresponsiveness. Am J Respir Crit Care Med 2000;162:953–957. Deykin A, Belostotsky O, Hong C, Massaro AF, Lilly CM, Israel E. Exhaled nitric oxide following leukotriene E4 and methacholine inhalation in patients with asthma. Am J Respir Crit Care Med 2000;162:1685–1689.
Year in Review 49. Hanazawa T, Kharitonov SA, Barnes PJ. Increased nitrotyrosine in exhaled breath condensate of patients with asthma. Am J Respir Crit Care Med 2000;162:1273–1276. 50. Paredi P, Kharitonov SA, Barnes PJ. Elevation of exhaled ethane concentration in asthma. Am J Respir Crit Care Med 2000;162:1450– 1454. 51. Lim S, Groneberg D, Fischer A, Oates T, Caramori G, Mattos W, Adcock I, Barnes PJ, Chung KF. Expression of heme oxygenase isoenzymes 1 and 2 in normal and asthmatic airways: effect of inhaled corticosteroids. Am J Respir Crit Care Med 2000;162:1912–1918. 52. Bonazzi A, Bolla M, Buccellati C, Hernandez A, Zarini S, Vigano T, Fumagalli F, Viappiani S, Ravasi S, Zannini P, Chiesa G, Folco G, Sala A. Effect of endogenous and exogenous prostaglandin E2 on interleukin-1 beta-induced cyclooxygenase-2 expression in human airway smooth-muscle cells. Am J Respir Crit Care Med 2000;162:2272– 2277. 53. Erjefalt JS, Persson CG. New aspects of degranulation and fates of airway mucosal eosinophils. Am J Respir Crit Care Med 2000;161:2074–2085. 54. Holt PG. Key factors in the development of asthma: atopy. Am J Respir Crit Care Med 2000;161:S172–S175. 55. Barnes PJ. Endogenous inhibitory mechanisms in asthma. Am J Respir Crit Care Med 2000;161:S176–S181. 56. Pedersen S. Why does airway inflammation persist? Is it failure to treat early? Am J Respir Crit Care Med 2000;161:S182–S185. 57. O’Byrne PM. Why does airway inflammation persist? Is it leukotrienes? Am J Respir Crit Care Med 2000;161:S186–S187. 58. Aalberse RC, Sterk PJ. Introduction. Am J Respir Crit Care Med 2000;162:S61. 59. Herz U, Joachim R, Ahrens B, Scheffold A, Radbruch A, Renz H. Prenatal sensitization in a mouse model. Am J Respir Crit Care Med 2000;162:S62–S65. 60. Kips JC, Tournoy KG, Pauwels RA. Gene knockout models of asthma. Am J Respir Crit Care Med 2000;162:S66–S70. 61. Karnowski A, Yu P, Achatz G, Lamers MC. The road to the production of IgE is long and winding. Am J Respir Crit Care Med 2000;162: S71–S75. 62. Kapsenberg ML, Hilkens CM, van Der Pouw Kraan TC, Wierenga EA, Kalinski P. Atopic allergy: a failure of antigen-presenting cells to properly polarize helper T cells? Am J Respir Crit Care Med 2000;162: S76–S80. 63. Wierenga EA, Messer G. Regulation of interleukin 4 gene transcription: alterations in atopic disease? Am J Respir Crit Care Med 2000;162: S81–S85. 64. Vercelli D. One cytokine, two isotypes: a Trojan horse, Pandora’s box, and an evolving paradigm. Am J Respir Crit Care Med 2000;162:S86–S90. 65. Holt PG, Macaubas C, Prescott SL, Sly PD. Primary sensitization to inhalant allergens. Am J Respir Crit Care Med 2000;162:S91–S94. 66. Martinez FD. Viruses and atopic sensitization in the first years of life. Am J Respir Crit Care Med 2000;162:S95–S99. 67. Savelkoul HF. Immune parameters in high-risk atopic individuals during early childhood. Am J Respir Crit Care Med 2000;162:S100–S104. 68. Bjorksten B. Perinatal events in relation to sensitization in the human. Am J Respir Crit Care Med 2000;162:S105–S107. 69. Kimpen JL. Viral infections and childhood asthma. Am J Respir Crit Care Med 2000;162:S108–S112. 70. Holgate ST, Lackie P, Wilson S, Roche W, Davies D. Bronchial epithelium as a key regulator of airway allergen sensitization and remodeling in asthma. Am J Respir Crit Care Med 2000;162:S113–S117. 71. Postma DS, Koppelman GH, Meyers DA. The genetics of atopy and airway hyperresponsiveness. Am J Respir Crit Care Med 2000;162: S118–S123. 72. Aalberse RC. Specific IgE and IgG responses in atopic versus nonatopic subjects. Am J Respir Crit Care Med 2000;162:S124–S127. 73. Platts-Mills TA, Blumenthal K, Perzanowski M, Woodfolk JA. Determinants of clinical allergic disease. The relevance of indoor allergens to the increase in asthma. Am J Respir Crit Care Med 2000;162:S128–S133. 74. Weiss ST. Atopy as a risk factor for chronic obstructive pulmonary disease: epidemiological evidence. Am J Respir Crit Care Med 2000;162: S134–S136. 75. Wanner A, Boushey H, Lee TH, Perruchoud AP. Purpose of the conference. Am J Respir Crit Care Med 2000;162:S137. 76. Lamb JR. Chairman’s summary. Antigen processing, presentation, and immunomodulation. Am J Respir Crit Care Med 2000;162:S138–S140. 77. Howie S, Ramage R, Hewson T. Innate immune system damage in human immunodeficiency virus type 1 infection. Implications for acquired immunity and vaccine design. Am J Respir Crit Care Med 2000;162:S141–S145.
1577 78. Austyn JM. Antigen-presenting cells. Experimental and clinical studies of dendritic cells. Am J Respir Crit Care Med 2000;162:S146–S150. 79. Holt PG. Antigen presentation in the lung. Am J Respir Crit Care Med 2000;162:S151–S156. 80. Sinigaglia F, D’Ambrosio D. Regulation of helper T cell differentiation and recruitment in airway inflammation. Am J Respir Crit Care Med 2000;162:S157–S160. 81. Hayday AC, Roberts S, Ramsburg E. gammadelta cells and the regulation of mucosal immune responses. Am J Respir Crit Care Med 2000;162:S161–S163. 82. Bugeon L, Dallman MJ. Costimulation of T cells. Am J Respir Crit Care Med 2000;162:S164–S168. 83. Hoyne GF, Tan K, Corsin-Jimenez M, Wahl K, Stewart M, Howie SE, Lamb JR. Immunological tolerance to inhaled antigen. Am J Respir Crit Care Med 2000;162:S169–S174. 84. Smith KM, Eaton AD, Finlayson LM, Garside P. Oral tolerance. Am J Respir Crit Care Med 2000;162:S175–S178. 85. Coyle AJ, Lloyd CM, Gutierrez-Ramos JC. Biotherapeutic targets for the treatment of allergic airway disease. Am J Respir Crit Care Med 2000;162:S179–S184. 86. Asseman C, Fowler S, Powrie F. Control of experimental inflammatory bowel disease by regulatory T cells. Am J Respir Crit Care Med 2000;162:S185–S189. 87. Donnelly JJ, Liu MA, Ulmer JB. Antigen presentation and DNA vaccines. Am J Respir Crit Care Med 2000;162:S190–S193. 88. George AJ, Arancibia-Carcamo CV, Awad HM, Comer RM, Fehevari Z, King WJ, Kadifachi M, Hudde T, Kerouedan-Lebosse C, Mirza F, Barbaros OH, Rayner SA, Tan PH, Tay E, Larkin DF. Gene delivery to the corneal endothelium. Am J Respir Crit Care Med 2000;162: S194–S200. 89. Palmans E, Kips JC, Pauwels RA. Prolonged allergen exposure induces structural airway changes in sensitized rats. Am J Respir Crit Care Med 2000;161:627–635. 90. Knott PG, Gater PR, Bertrand CP. Airway inflammation driven by antigen-specific resident lung CD4 T cells in -T cell receptor transgenic mice. Am J Respir Crit Care Med 2000;161:1340–1348. 91. Tsang F, Fred Wong WS. Inhibitors of tyrosine kinase signaling cascade attenuated antigen challenge of guinea-pig airways in vitro. Am J Respir Crit Care Med 2000;162:126–133. 92. Abraham WM, Gill A, Ahmed A, Sielczak MW, Lauredo IT, Botinnikova Y, Lin KC, Pepinsky B, Leone DR, Lobb RR, Adams SP. A small-molecule, tight-binding inhibitor of the integrin 41 blocks antigen-induced airway responses and inflammation in experimental asthma in sheep. Am J Respir Crit Care Med 2000;162:603–611. 93. Peebles RS Jr, Dworski R, Collins RD, Jarzecka K, Mitchell DB, Graham BS, Sheller JR. Cyclooxygenase inhibition increases interleukin 5 and interleukin 13 production and airway hyperresponsiveness in allergic mice. Am J Respir Crit Care Med 2000;162:676–681. 94. Allakhverdi Z, Lamkhioued B, Olivenstein R, Hamid Q, Renzi PM. CD8 depletion-induced late airway response is characterized by eosinophilia, increased eotaxin, and decreased IFN-gamma expression in rats. Am J Respir Crit Care Med 2000;162:1123–1131. 95. Kanehiro A, Takeda K, Joetham A, Tomkinson A, Ikemura T, Irvin CG, Gelfand EW. Timing of administration of anti-VLA-4 differentiates airway hyperresponsiveness in the central and peripheral airways in mice. Am J Respir Crit Care Med 2000;162:1132–1139. 96. Uhlig T, Wildhaber JH, Carroll N, Turner DJ, Gray PR, Dore N, James AL, Sly PD. Pulmonary vascular congestion selectively potentiates airway responsiveness in piglets. Am J Respir Crit Care Med 2000; 161:1306–1313. 97. Hamada K, Goldsmith CA, Goldman A, Kobzik L. Resistance of very young mice to inhaled allergen sensitization is overcome by coexposure to an air-pollutant aerosol. Am J Respir Crit Care Med 2000; 161:1285–1293. 98. Bureau F, Bonizzi G, Kirschvink N, Delhalle S, Desmecht D, Merville MP, Bours V, Lekeux P. Correlation between nuclear factor- B activity in bronchial brushing samples and lung dysfunction in an animal model of asthma. Am J Respir Crit Care Med 2000;161:1314–1321. 99. Duguet A, Biyah K, Minshall E, Gomes R, Wang CG, TaoudiBenchekroun M, Bates JH, Eidelman DH. Bronchial responsiveness among inbred mouse strains. Role of airway smooth-muscle shortening velocity. Am J Respir Crit Care Med 2000;161:839–848. 100. Folkerts G, Vlieger JW, de Vries A, Faas S, van der Linde H, Engels F, de Jong JC, Verheyen FA, Heuven-Nolsen D, Nijkamp FP. Virusand bradykinin-induced airway hyperresponsiveness in guinea pigs. Am J Respir Crit Care Med 2000;161:1666–1671. 101. Ricciardolo FL, Steinhoff M, Amadesi S, Guerrini R, Tognetto M, Tre-
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visani M, Creminon C, Bertrand C, Bunnett NW, Fabbri LM, Salvadori S, Geppetti P. Presence and bronchomotor activity of proteaseactivated receptor-2 in guinea pig airways. Am J Respir Crit Care Med 2000;161:1672–1680. Fukuyama S, Inoue H, Aizawa H, Oike M, Kitaura M, Yoshie O, Hara N. Effect of eotaxin and platelet-activating factor on airway inflammation and hyperresponsiveness in guinea pigs in vivo. Am J Respir Crit Care Med 2000;161:1844–1849. Suzuki R, Freed AN. Heparin inhibits eicosanoid metabolism and hyperventilation-induced bronchoconstriction in dogs. Am J Respir Crit Care Med 2000;161:1850–1854. Held HD, Uhlig S. Mechanisms of endotoxin-induced airway and pulmonary vascular hyperreactivity in mice. Am J Respir Crit Care Med 2000;162:1547–1552. Ammit AJ, Armour CL, Black JL. Smooth-muscle myosin light-chain kinase content is increased in human sensitized airways. Am J Respir Crit Care Med 2000;161:257–263. Maruoka S, Hashimoto S, Gon Y, Takeshita I, Horie T. PAF-induced RANTES production by human airway smooth muscle cells requires both p38 MAP kinase and Erk. Am J Respir Crit Care Med 2000;161: 922–929. Hyvelin JM, Martin C, Roux E, Marthan R, Savineau JP. Human isolated bronchial smooth muscle contains functional ryanodine/ caffeine-sensitive Ca-release channels. Am J Respir Crit Care Med 2000;162:687–694. Johnson PR, Black JL, Carlin S, Ge Q, Underwood PA. The production of extracellular matrix proteins by human passively sensitized airway smooth-muscle cells in culture: the effect of beclomethasone. Am J Respir Crit Care Med 2000;162:2145–2151. Ordonez C, Ferrando R, Hyde DM, Wong HH, Fahy JV. Epithelial desquamation in asthma: artifact or pathology? Am J Respir Crit Care Med 2000;162:2324–2329. Macfarlane AJ, Dworski R, Sheller JR, Pavord ID, Kay AB, Barnes NC. Sputum cysteinyl leukotrienes increase 24 hours after allergen inhalation in atopic asthmatics. Am J Respir Crit Care Med 2000;161: 1553–1558. Avila PC, Segal MR, Wong HH, Boushey HA, Fahy JV. Predictors of late asthmatic response. Logistic regression and classification tree analyses. Am J Respir Crit Care Med 2000;161:2092–2095. Henig NR, Aitken ML, Liu MC, Yu AS, Henderson WR Jr. Effect of recombinant human platelet-activating factor-acetylhydrolase on allergen-induced asthmatic responses. Am J Respir Crit Care Med 2000;162:523–527. Hartert TV, Dworski RT, Mellen BG, Oates JA, Murray JJ, Sheller JR. Prostaglandin E2 decreases allergen-stimulated release of prostaglandin D2 in airways of subjects with asthma. Am J Respir Crit Care Med 2000;162:637–640. Khan LN, Kon OM, Macfarlane AJ, Meng Q, Ying S, Barnes NC, Kay AB. Attenuation of the allergen-induced late asthmatic reaction by cyclosporin A is associated with inhibition of bronchial eosinophils, interleukin-5, granulocyte macrophage colony-stimulating factor, and eotaxin. Am J Respir Crit Care Med 2000;162:1377–1382. Kelly EA, Busse WW, Jarjour NN. Increased matrix metalloproteinase-9 in the airway after allergen challenge. Am J Respir Crit Care Med 2000;162:1157–1161. Fowler SJ, Dempsey OJ, Sims EJ, Lipworth BJ. Screening for bronchial hyperresponsiveness using methacholine and adenosine monophosphate. Relationship to asthma severity and 2-receptor genotype. Am J Respir Crit Care Med 2000;162:1318–1322. Crapo RO, Casaburi R, Coates AL, Enright PL, Hankinson JL, Irvin CG, MacIntyre NR, McKay RT, Wanger JS, Anderson SD, Cockcroft DW, Fish JE, Sterk PJ. Guidelines for methacholine and exercise challenge testing—1999. Official statement of the American Thoracic Society (adopted by the ATS Board of Directors, July 1999). Am J Respir Crit Care Med 2000;161:309–329. Langdeau JB, Turcotte H, Bowie DM, Jobin J, Desgagne P, Boulet LP. Airway hyperresponsiveness in elite athletes. Am J Respir Crit Care Med 2000;161:1479–1484. Karjalainen EM, Laitinen A, Sue-Chu M, Altraja A, Bjermer L, Laitinen LA. Evidence of airway inflammation and remodeling in ski athletes with and without bronchial hyperresponsiveness to methacholine. Am J Respir Crit Care Med 2000;161:2086–2091. Brannan JD, Anderson SD, Freed R, Leuppi JD, Koskela H, Chan HK. Nedocromil sodium inhibits responsiveness to inhaled mannitol in asthmatic subjects. Am J Respir Crit Care Med 2000;161:2096–2099. Hashimoto S, Gon Y, Matsumoto K, Takeshita I, Maruoka S, Horie T. Inhalant corticosteroids inhibit hyperosmolarity-induced, and cool-
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ing and rewarming-induced interleukin-8 and RANTES production by human bronchial epithelial cells. Am J Respir Crit Care Med 2000;162:1075–1080. Gauvreau GM, Ronnen GM, Watson RM, O’Byrne PM. Exerciseinduced bronchoconstriction does not cause eosinophilic airway inflammation or airway hyperresponsiveness in subjects with asthma. Am J Respir Crit Care Med 2000;162:1302–1307. Kaminsky DA, Lynn M. Pulmonary capillary blood volume in hyperpneainduced bronchospasm. Am J Respir Crit Care Med 2000;162:1668–1673. Myou S, Fujimura M, Kamio Y, Ishiura Y, Kurashima K, Tachibana H, Hirose T, Hashimoto T. Effect of losartan, a type 1 angiotensin II receptor antagonist, on bronchial hyperresponsiveness to methacholine in patients with bronchial asthma. Am J Respir Crit Care Med 2000;162:40–44. Woolcock AJ, Peat J. What is the relationship between airway hyperresponsiveness and atopy? Am J Respir Crit Care Med 2000;161:S215– S217. Fredberg JJ. Airway smooth muscle in asthma. Perturbed equilibria of myosin binding. Am J Respir Crit Care Med 2000;161:S158–S160. Que CL, Maksym G, Macklem PT. Deciphering the homeokinetic code of airway smooth muscle. Am J Respir Crit Care Med 2000;161:S161–S163. Solway J. What makes the airways contract abnormally? Is it inflammation? Am J Respir Crit Care Med 2000;161:S164–S167. Elias JA. Airway remodeling in asthma. Unanswered questions. Am J Respir Crit Care Med 2000;161:S168–S171. Wu ZX, Zhou D, Chen G, Lee LY. Airway hyperresponsiveness to cigarette smoke in ovalbumin-sensitized guinea pigs. Am J Respir Crit Care Med 2000;161:73–80. Ho CY, Gu Q, Hong JL, Lee LY. Prostaglandin E2 enhances chemical and mechanical sensitivities of pulmonary C fibers in the rat. Am J Respir Crit Care Med 2000;162:528–533. Moore KA, Undem BJ, Weinreich D. Antigen inhalation unmasks NK-2 tachykinin receptor-mediated responses in vagal afferents. Am J Respir Crit Care Med 2000;161:232–236. Hunter DD, Satterfield BE, Huang J, Fedan JS, Dey RD. Toluene diisocyanate enhances substance P in sensory neurons innervating the nasal mucosa. Am J Respir Crit Care Med 2000;161:543–549. Hunter DD, Myers AC, Undem BJ. Nerve growth factor-induced phenotypic switch in guinea pig airway sensory neurons. Am J Respir Crit Care Med 2000;161:1985–1990. Sudo T, Hayashi F, Nishino T. Responses of tracheobronchial receptors to inhaled furosemide in anesthetized rats. Am J Respir Crit Care Med 2000;162:971–975. Maghni K, Taha R, Afif W, Hamid Q, Martin JG. Dichotomy between neurokinin receptor actions in modulating allergic airway responses in an animal model of helper T cell type 2 cytokine-associated inflammation. Am J Respir Crit Care Med 2000;162:1068–1074. Carr MJ, Schechter NM, Undem BJ. Trypsin-induced, neurokininmediated contraction of guinea pig bronchus. Am J Respir Crit Care Med 2000;162:1662–1667. Scichilone N, Kapsali T, Permutt S, Togias A. Deep inspirationinduced bronchoprotection is stronger than bronchodilation. Am J Respir Crit Care Med 2000;162:910–916. Brown RH, Mitzner W. Delayed distension of contracted airways with lung inflation in vivo. Am J Respir Crit Care Med 2000;162:2113–2116. Mitzner W, Brown RH. Potential mechanism of hyperresponsive airways. Am J Respir Crit Care Med 2000;161:1619–1623. Brieva JL, Danta I, Wanner A. Effect of an inhaled glucocorticosteroid on airway mucosal blood flow in mild asthma. Am J Respir Crit Care Med 2000;161:293–296. Kumar SD, Brieva JL, Danta I, Wanner A. Transient effect of inhaled fluticasone on airway mucosal blood flow in subjects with and without asthma. Am J Respir Crit Care Med 2000;161:918–921. Arnold V, Balkow S, Staats R, Matthys H, Luttmann W, Virchow JC Jr. Increase in perforin-positive peripheral blood lymphocytes in extrinsic and intrinsic asthma. Am J Respir Crit Care Med 2000;161:182–186. Kaminsky DA, Bates JH, Irvin CG. Effects of cool, dry air stimulation on peripheral lung mechanics in asthma. Am J Respir Crit Care Med 2000;162:179–186. Niimi A, Matsumoto H, Amitani R, Nakano Y, Mishima M, Minakuchi M, Nishimura K, Itoh H, Izumi T. Airway wall thickness in asthma assessed by computed tomography. Relation to clinical indices. Am J Respir Crit Care Med 2000;162:1518–1523. Brown RH, Croisille P, Mudge B, Diemer FB, Permutt S, Togias A. Airway narrowing in healthy humans inhaling methacholine without deep inspirations demonstrated by HRCT. Am J Respir Crit Care Med 2000;161:1256–1263.
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Year in Review 147. King GG, Muller NL, Whittall KP, Xiang QS, Pare PD. An analysis algorithm for measuring airway lumen and wall areas from high-resolution computed tomographic data. Am J Respir Crit Care Med 2000; 161:574–580. 148. Brackel HJ, Pedersen OF, Mulder PG, Overbeek SE, Kerrebijn KF, Bogaard JM. Central airways behave more stiffly during forced expiration in patients with asthma. Am J Respir Crit Care Med 2000;162: 896–904. 149. Gelb AF, Zamel N. Unsuspected pseudophysiologic emphysema in chronic persistent asthma. Am J Respir Crit Care Med 2000;162:1778–1782. 150. in ‘t Veen JCCM, Beekman AJ, Bel EH, Sterk PJ. Recurrent exacerbations in severe asthma are associated with enhanced airway closure during stable episodes. Am J Respir Crit Care Med 2000;161:1902–1906. 151. Bousquet J, Jeffery PK, Busse WW, Johnson M, Vignola AM. Asthma. From bronchoconstriction to airways inflammation and remodeling. Am J Respir Crit Care Med 2000;161:1720–1745. 152. Au DH, Lemaitre RN, Curtis JR, Smith NL, Psaty BM. The risk of myocardial infarction associated with inhaled -adrenoceptor agonists. Am J Respir Crit Care Med 2000;161:827–830. 153. Hart L, Lim S, Adcock I, Barnes PJ, Chung KF. Effects of inhaled corticosteroid therapy on expression and DNA-binding activity of nuclear factor B in asthma. Am J Respir Crit Care Med 2000;161:224–231. 154. Jaffuel D, Demoly P, Gougat C, Balaguer P, Mautino G, Godard P, Bousquet J, Mathieu M. Transcriptional potencies of inhaled glucocorticoids. Am J Respir Crit Care Med 2000;162:57–63. 155. Kelly EA, Busse WW, Jarjour NN. Inhaled budesonide decreases airway inflammatory response to allergen. Am J Respir Crit Care Med 2000;162:883–890. 156. Miller-Larsson A, Jansson P, Runstrom A, Brattsand R. Prolonged airway activity and improved selectivity of budesonide possibly due to esterification. Am J Respir Crit Care Med 2000;162:1455–1461. 157. Onhoj J, Thorsson L, Bisgaard H. Lung deposition of inhaled drugs increases with age. Am J Respir Crit Care Med 2000;162:1819–1822. 158. Nielsen LP, Dahl R. Therapeutic ratio of inhaled corticosteroids in adult asthma. A dose-range comparison between fluticasone propionate and budesonide, measuring their effect on bronchial hyperresponsiveness and adrenal cortex function. Am J Respir Crit Care Med 2000;162:2053–2057. 159. Gauvreau GM, Wood LJ, Sehmi R, Watson RM, Dorman SC, Schleimer RP, Denburg JA, O’Byrne PM. The effects of inhaled budesonide on circulating eosinophil progenitors and their expression of cytokines after allergen challenge in subjects with atopic asthma. Am J Respir Crit Care Med 2000;162:2139–2144. 160. Gagliardo R, Chanez P, Vignola AM, Bousquet J, Vachier I, Godard P, Bonsignore G, Demoly P, Mathieu M. Glucocorticoid receptor alpha and beta in glucocorticoid dependent asthma. Am J Respir Crit Care Med 2000;162:7–13. 161. Leung DY, Chrousos GP. Is there a role for glucocorticoid receptor beta in glucocorticoid-dependent asthmatics? Am J Respir Crit Care Med 2000;162:1–3. 162. Rodrigo GJ, Rodrigo C. First-line therapy for adult patients with acute asthma receiving a multiple-dose protocol of ipratropium bromide plus albuterol in the emergency department. Am J Respir Crit Care Med 2000;161:1862–1868. 163. Reinheimer T, Mohlig T, Zimmermann S, Hohle KD, Wessler I. Muscarinic control of histamine release from airways. Inhibitory M1receptors in human bronchi but absence in rat trachea. Am J Respir Crit Care Med 2000;162:534–538. 164. Hasday JD, Meltzer SS, Moore WC, Wisniewski P, Hebel JR, Lanni C, Dube LM, Bleecker ER. Anti-inflammatory effects of zileuton in a subpopulation of allergic asthmatics. Am J Respir Crit Care Med 2000;161:1229–1236. 165. Dahlen SE, Haeggstrom JZ, Samuelsson B, Rabe KF, Leff AR. Leukotrienes as targets for treatment of asthma and other diseases. Current basic and clinical research. Am J Respir Crit Care Med 2000;161:S1. 166. Samuelsson B. The discovery of the leukotrienes. Am J Respir Crit Care Med 2000;161:S2–S6. 167. Rodger IW. From bench to bedside. The hurdles of discovering a new leukotriene receptor antagonist. Am J Respir Crit Care Med 2000; 161:S7–S10. 168. Radmark OP. The molecular biology and regulation of 5-lipoxygenase. Am J Respir Crit Care Med 2000;161:S11–S15. 169. Lam BK, Frank AK. Leukotriene C4 synthase. A pivotal enzyme in the biosynthesis of the cysteinyl leukotrienes. Am J Respir Crit Care Med 2000;161:S16–S19. 170. Jakobsson PJ, Morgenstern R, Mancini J, Ford-Hutchinson A, Persson B. Membrane-associated proteins in eicosanoid and glutathione me-
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CM, Ian TG. Effects of terbutaline and budesonide on sputum cells and bronchial hyperresponsiveness in asthma. Am J Respir Crit Care Med 2000;161:1459–1464. Virchow JC, Prasse A, Naya I, Summerton L, Harris A. Zafirlukast improves asthma control in patients receiving high-dose inhaled corticosteroids. Am J Respir Crit Care Med 2000;162:578–585. Spoelstra FM, Kauffman HF, Hovenga H, Noordhoek JA, de Monchy JG, Postma DS. Effects of budesonide and formoterol on eosinophil activation induced by human lung fibroblasts. Am J Respir Crit Care Med 2000;162:1229–1234. American Thoracic Society. Proceedings of the ATS workshop on refractory asthma: current understanding, recommendations, and unanswered questions. Am J Respir Crit Care Med 2000;162:2341–2351. Irvin CG, Pak J, Martin RJ. Airway–parenchyma uncoupling in nocturnal asthma. Am J Respir Crit Care Med 2000;161:50–56. Cuttitta G, Cibella F, Visconti A, Scichilone N, Bellia V, Bonsignore G. Spontaneous gastroesophageal reflux and airway patency during the night in adult asthmatics. Am J Respir Crit Care Med 2000;161:177–181. Harding SM, Guzzo MR, Richter JE. The prevalence of gastroesophageal reflux in asthma patients without reflux symptoms. Am J Respir Crit Care Med 2000;162:34–39. Carroll NG, Perry S, Karkhanis A, Harji S, Butt J, James AL, Green FH. The airway longitudinal elastic fiber network and mucosal folding in patients with asthma. Am J Respir Crit Care Med 2000; 161:244–248. Ordonez CL, Shaughnessy TE, Matthay MA, Fahy JV. Increased neutrophil numbers and IL-8 levels in airway secretions in acute severe asthma: clinical and biologic significance. Am J Respir Crit Care Med 2000;161:1185–1190. Tillie-Leblond I, Hammad H, Desurmont S, Pugin J, Wallaert B, Tonnel AB, Gosset P. CC chemokines and interleukin-5 in bronchial lavage fluid from patients with status asthmaticus. Potential implication in eosinophil recruitment. Am J Respir Crit Care Med 2000;162:586–592. Bai TR, Cooper J, Koelmeyer T, Pare PD, Weir TD. The effect of age and duration of disease on airway structure in fatal asthma. Am J Respir Crit Care Med 2000;162:663–669. Moy ML, Woodrow WJ, Sparrow D, Israel E, Schwartzstein RM. Quality of dyspnea in bronchoconstriction differs from external resistive loads. Am J Respir Crit Care Med 2000;162:451–455. Banzett RB, Dempsey JA, O’Donnell DE, Wamboldt MZ. Symptom perception and respiratory sensation in asthma. Am J Respir Crit Care Med 2000;162:1178–1182. Osman LM, Calder C, Robertson R, Friend JA, Legge JS, Douglas JG. Symptoms, quality of life, and health service contact among young adults with mild asthma. Am J Respir Crit Care Med 2000;161:498–503. Juniper EF, O’Byrne PM, Ferrie PJ, King DR, Roberts JN. Measuring asthma control. Clinic questionnaire or daily diary? Am J Respir Crit Care Med 2000;162:1330–1334. Cassino C, Berger KI, Goldring RM, Norman RG, Kammerman S, Ciotoli C, Reibman J. Duration of asthma and physiologic outcomes in elderly nonsmokers. Am J Respir Crit Care Med 2000;162:1423–1428. Brightling CE, Ward R, Woltmann G, Bradding P, Sheller JR, Dworski R, Pavord ID. Induced sputum inflammatory mediator concentrations in eosinophilic bronchitis and asthma. Am J Respir Crit Care Med 2000;162:878–882. Piirila PL, Nordman H, Keskinen HM, Luukkonen R, Salo SP, Tuomi TO, Tuppurainen M. Long-term follow-up of hexamethylene diisocyanate-, diphenylmethane diisocyanate-, and toluene diisocyanateinduced asthma. Am J Respir Crit Care Med 2000;162:516–522. Wisnewski AV, Srivastava R, Herick C, Xu L, Lemus R, Cain H, Magoski NM, Karol MH, Bottomly K, Redlich CA. Identification of human lung and skin proteins conjugated with hexamethylene diisocyanate in vitro and in vivo. Am J Respir Crit Care Med 2000;162:2330–2336. Monso E, Malo JL, Infante-Rivard C, Ghezzo H, Magnan M, L’Archeveque J, Trudeau C, Gautrin D. Individual characteristics and quitting in apprentices exposed to high-molecular-weight agents. Am J Respir Crit Care Med 2000;161:1508–1512.
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217. Monso E, Magarolas R, Radon K, Danuser B, Iversen M, Weber C, Opravil U, Donham KJ, Nowak D. Respiratory symptoms of obstructive lung disease in European crop farmers. Am J Respir Crit Care Med 2000;162:1246–1250. 218. Johnson AR, Dimich-Ward HD, Manfreda J, Becklake MR, Ernst P, Sears MR, Bowie DM, Sweet L, Chan-Yeung M. Occupational asthma in adults in six Canadian communities. Am J Respir Crit Care Med 2000;162:2058–2062. 219. Liss GM, Tarlo SM, Macfarlane Y, Yeung KS. Hospitalization among workers compensated for occupational asthma. Am J Respir Crit Care Med 2000;162:112–118. 220. Gautrin D, Ghezzo H, Infante-Rivard C, Malo JL. Incidence and determinants of IgE-mediated sensitization in apprentices. A prospective study. Am J Respir Crit Care Med 2000;162:1222–1228. 221. Lemiere C, Cartier A, Malo JL, Lehrer SB. Persistent specific bronchial reactivity to occupational agents in workers with normal nonspecific bronchial reactivity. Am J Respir Crit Care Med 2000;162: 976–980. 222. Plaschke PP, Janson C, Norrman E, Bjornsson E, Ellbjar S, Jarvholm B. Onset and remission of allergic rhinitis and asthma and the relationship with atopic sensitization and smoking. Am J Respir Crit Care Med 2000;162:920–924. 223. Cho HY, Hotchkiss JA, Bennett CB, Harkema JR. Neutrophil-dependent and neutrophil-independent alterations in the nasal epithelium of ozone-exposed rats. Am J Respir Crit Care Med 2000;162:629–636. 224. Leynaert B, Neukirch C, Liard R, Bousquet J, Neukirch F. Quality of life in allergic rhinitis and asthma. A population-based study of young adults. Am J Respir Crit Care Med 2000;162:1391–1396. 225. Kowalski ML, Pawliczak R, Wozniak J, Siuda K, Poniatowska M, Iwaszkiewicz J, Kornatowski T, Kaliner MA. Differential metabolism of arachidonic acid in nasal polyp epithelial cells cultured from aspirin-sensitive and aspirin-tolerant patients. Am J Respir Crit Care Med 2000;161:391–398. 226. Sanico AM, Stanisz AM, Gleeson TD, Bora S, Proud D, Bienenstock J, Koliatsos VE, Togias A. Nerve growth factor expression and release in allergic inflammatory disease of the upper airways. Am J Respir Crit Care Med 2000;161:1631–1635. 227. Shimizu T, Hirano H, Majima Y, Sakakura Y. A mechanism of antigeninduced mucus production in nasal epithelium of sensitized rats. A comparison with lipopolysaccharide-induced mucus production. Am J Respir Crit Care Med 2000;161:1648–1654. 228. Braunstahl GJ, Kleinjan A, Overbeek SE, Prins JB, Hoogsteden HC, Fokkens WJ. Segmental bronchial provocation induces nasal inflammation in allergic rhinitis patients. Am J Respir Crit Care Med 2000;161:2051–2057. 229. Linden M, Svensson C, Andersson E, Andersson M, Greiff L, Persson CG. Immediate effect of topical budesonide on allergen challengeinduced nasal mucosal fluid levels of granulocyte-macrophage colony-stimulating factor and interleukin-5. Am J Respir Crit Care Med 2000;162:1705–1708. 230. Gern JE, Vrtis R, Grindle KA, Swenson C, Busse WW. Relationship of upper and lower airway cytokines to outcome of experimental rhinovirus infection. Am J Respir Crit Care Med 2000;162:2226–2231. 231. Assanasen P, Baroody FM, Rouadi P, Naureckas E, Solway J, Naclerio RM. Ipratropium bromide increases the ability of the nose to warm and humidify air. Am J Respir Crit Care Med 2000;162:1031–1037. 232. Lamblin C, Brichet A, Perez T, Darras J, Tonnel AB, Wallaert B. Long-term follow-up of pulmonary function in patients with nasal polyposis. Am J Respir Crit Care Med 2000;161:406–413. 233. Grembiale RD, Camporota L, Naty S, Tranfa CM, Djukanovic R, Marsico SA. Effects of specific immunotherapy in allergic rhinitic individuals with bronchial hyperresponsiveness. Am J Respir Crit Care Med 2000;162:2048–2052. 234. Wilson AM, Orr LC, Sims EJ, Dempsey OJ, Lipworth BJ. Antiasthmatic effects of mediator blockade versus topical corticosteroids in allergic rhinitis and asthma. Am J Respir Crit Care Med 2000;162: 1297–1301.
