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Infections associated with chronic granulomatous disease: linking genetics to phenotypic expression Expert Rev. Anti Infect. Ther. 10(8), 881–894 (2012)
Josef Ben-Ari1, Ofir Wolach2, Ronit Gavrieli3 and Baruch Wolach*3 Pediatric Intensive Care Unit, Meir Medical Center, Kfar Saba, Israel 2 Davidoff Cancer Center, Rabin Medical Center, Petah Tikva, Israel 3 The Laboratory for Leukocyte Functions & The Pediatric Immuno-Hematology Clinic, Meir Medical Center, Kfar Saba and The Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel *Author for correspondence:
[email protected] 1
Chronic granulomatous disease (CGD) is an inherited primary immunodeficiency characterized by the absence or malfunction of the NADPH oxidase in phagocytic cells. As a result, there is an impaired ability to generate superoxide anions and the subsequent reactive oxygen intermediates. Consequently, CGD patients suffer from two clinical manifestations: recurrent, life-threatening bacterial and fungal infections and excessive inflammatory reactions leading to granulomatous lesions. Although the genotype of CGD was linked to the phenotypic expression of the disease, this connection is still controversial and poorly understood. Certain correlations were reported, but the clinical expression of the disease is usually unpredictable, regardless of the pattern of inheritance. CGD mainly affects the lungs, lymph nodes, skin, GI tract and liver. Patients are particularly susceptible to catalase-positive microorganisms, including Staphyloccocus aureus, Nocardia spp. and Gram-negative bacteria, such as Serratia marcescens, Burkholderia cepacea and Salmonella spp. Unusually, catalase-negative microorganisms were reported as well. New antibacterial and antimycotic agents considerably improved the prognosis of CGD. Therapy with IFN-γ is still controversial. Bone marrow stem cell transplantation is currently the only curative treatment and gene therapy needs further development. In this article, the authors discuss the genetic, functional and molecular aspects of CGD and their impact on the clinical expression, infectious complications and the hyperinflammatory state. Keywords: azoles • bone marrow transplantation • chronic granulomatous disease • gene therapy • granulomata • NADPH oxidase • phagocytosis • primary immune deficiency • pyogenic infections • recombinant IFN-γ • trimethoprim–sulfamethoxazole
Chronic granulomatous disease (CGD) is a rare primary immunodeficiency, but is the most common inherited disorder of the phagocyte functions [1,2] . Phagocyte dysfunctions range from 8 to 18% of all primary immune deficiencies [3,4] . CGD was initially described in the 1950s [5,6] , with an incidence ranging from 1/140,000 in Denmark to 1/1,111,000 in Korea, 1/200,000–250,000 in the USA and Europe and 1/190,000 in Israel [7–10] . The National Laboratory for Leukocyte Functions evaluated 1296 patients in Israel over the past 24 years, referred because of recurrent, severe pyogenic infections and CGD was diagnosed in 51 patients (3.9%) (Figure 1) [1] . CGD is caused by defects in the genes encoding the phox protein subunits of the phagocyte NADPH oxidase. The mode of inheritance could be either X-linked or www.expert-reviews.com
10.1586/ERI.12.77
autosomal recessive (AR) [11,12] . There is a failure to activate the ‘respiratory burst’ that normally accompanies the phagocytic cells: neutrophils, monocytes, eosinophils and macrophages. The catalytic conversion of molecular oxygen into reactive oxygen intermediates (ROIs) is impaired, rendering the patient susceptible to recurrent infections. CGD still causes significant morbidity and mortality. Infections in CGD are caused by a narrow spectrum of catalase-positive microorganisms, Gram-positive and Gram-negative bacteria, opportunistic pathogens and fungi. Occasionally, the infecting etiological agent could be a catalasenegative microorganism, such as certain species of Staphylococcus aureus, Hemophilus influenza and Actinomyces [7–15] . Impaired bactericidal activity due to defective oxidative burst is the
© 2012 Expert Reviews Ltd
ISSN 1478-7210
881
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Ben-Ari, Wolach, Gavrieli & Wolach
complete myeloperoxidase deficiency, the cytochrome c reduction is normal but Primary phagocytic disorder the DHR flow cytometry is abnormal. The molecular and genetic studies will confirm (8.1%) the diagnosis of CGD. Routine diagnostics show great variability, so it would be advisable to have 7.2% all CGD patients analyzed at specialized Idiopathic 0.9% phagocytic laboratories, in major experience centers dysfunction [1,16,17] . Furthermore, two independent 26.4% blood samples and at least two different methods should always be used to estab66.4% lish a definite diagnosis of CGD. A large spectrum of CGD subtypes is determined by the various genetic mutations and the residual ROI production [18–20] . In CGD, hyperinflammatory responses to various stimuli lead to granuloma formation, hence its name CGD. The improved management of patients with CGD resulted Normal in more prominent manifestations of the evaluation autoinflammatory expression in adulthood. Studies on the underlying mechanisms Figure 1. Incidence of the phagocytic dysfunction in 1000 patients with of the excessive inflammatory reactions recurrent severe infections. Overall, 67.3% (66.4%+0.9%) had a normal evaluation are ongoing [21–23] . CGD patients are at and 33.7% (26.4%+7.2%) had impairment of one or more steps of phagocytic activity: impaired chemotaxis was shown in 16.6%, impaired superoxide production in 6% and risk of developing autoimmune diseases, impaired bactericidal activity in 24.5%. Diagnosis of a primary phagocytic disorder was as a number of autoimmune disorders established in 81 patients: chronic granulomatous disease (n = 48), neutrophil G6PD have been reported to be associated with deficiency (n = 3), leukocyte adhesion deficiency 1 (n = 4), Myeloperoxidase deficiency CGD, such as juvenile rheumatoid arthri(n = 2), hyper-IgE syndrome (n = 21), Chediak–Higashi syndrome (n = 3). Neutrophil tis, idiopathic thrombocytopenic purpura, function impairment was found in 7.2 % of these patients, yet nine patients (0.9%) had a normal phagocytic evaluation (two of three patients with neutrophil G6PD deficiency antiphospholipid syndrome, systemic and seven out of 21 with hyper-IgE syndrome). lupus erythematosus and IgA nephropathy [9,10,24] . Hemophagocytic lymphohistiocymain dysfunction of the phagocytic cells in CGD. Consequently, tosis (HPLH), characterized by hyperinflammation and excessive evaluation of neutrophil functions is the first-line screen required cytokine release, was also reported in CGD [25] . in such patients. The diagnosis requires the demonstration of The diagnosis and management of CGD require a careful defective NADPH oxidase by the flow cytometric evaluation with clinical approach and a meticulous evaluation of the patient. dihydrorhodamine 123 (DHR) fluorescence, which measures Early diagnosis is important for better care and for prolonging the intracellular NADPH oxidase activity, and the dismutase- CGD patient survival. Clues for considering the diagnosis are a inhibitable reduction of ferricytochrome c which measures suggestive family history, the type of infecting isolate, the severity extracellular NADPH oxidase activity. The nitroblue tetrazolium and recurrence of infections, tissue abscesses and granulomas, (NBT) assay using the subjective NBT slide test or the ‘modified and the patients’ response to antibiotic–antifungal therapy. The semiquantitative’ approach could be helpful but is sometimes family history of severe or unusual infections in males (for the confusing. Rather than detecting the ‘respiratory burst’ per se X-linked form of CGD) and consanguineous parents (for the AR the assay relies on the accumulation of formazan precipitate form of the disease) provide important clues for the clinician’s over time. Although it is often easy to discern slight blue or diagnosis. Furthermore, a past history of opportunistic infections purple from normally stained cells, in some cases it is difficult typical for this disease, such as pneumonia caused by Aspergillus to diagnose CGD even for skilled laboratory assistants. Thus, spp., Nocardia spp., Actinomyces spp. and Burkholderia cepacia, in some cases of ‘variants’ with low levels of oxidants, the NBT lymphadenitis or skin/subcutaneous abscesses caused by Serratia may give false-positive staining. Missing these CGD variants marcescens or Granulibacter bethedensis, or osteomyelitis caused may have potentially hazardous consequences to the patient. by S. marcescens or Aspergillus spp., should prompt an evaluation Methods enabling objective quantification of the production of the patient for CGD. Failure to thrive is a typical feature of of ROIs are cytochrome c reduction and DHR flow cytometry. children with CGD and is a result of repeated and/or prolonged They are precise and reliable, with high sensitivity, being able hospitalizations that are associated with the chronic nature of to detect the ‘classical’ and the ‘variant’ CGD. In patients with this disease and its complications. Thus, failure to thrive in 882
Expert Rev. Anti Infect. Ther. 10(8), (2012)
Infections associated with chronic granulomatous disease
the appropriate clinical context is an negative sign and should prompt the clinician to evaluate the immune system, including the possibility of CGD. Although for many years, CGD was believed to occur in early infancy with a fatal outcome, later reports indicate that the disorder may present in adulthood, with a variable clinical course [26,27] . Both prenatal and preimplantation diagnosis are now feasible. As in other immune deficiencies, malignancies may develop in CGD patients [28] . Leukemia and solid tumors were reported in patients with CGD, but whether malignancies occur at higher rates among these patients awaits further observations [9,29,30] . The advent of new antimicrobial and antifungal therapy, the use of prophylactic antibacterial along with antimycotic agents and the aggressive therapy of acute infections have markedly improved the clinical course of patients with CGD [31] . The use of prophylaxis with recombinant IFN-γ still remains controversial in most European countries. The International CGD Group showed efficacy of IFN-γ with a reduction of severe infections and hospitalizations, regardless of the pattern of inheritance, while others did not demonstrate such an efficacy [31–34] . Treatment of patients with allogeneic bone marrow transplantation (BMT) is currently the only established curative treatment for CGD and is increasingly used with encouraging results [35–38] . Gene therapy is promising, although needs further development [39,40] . The authors aim to review and discuss the genetic variability of CGD with its unpredictable clinical expression, the scope of infections reported in association with the disease and the specific management as reported at different medical centers in the USA, Europe and the Eastern world. The genetic variability of CGD & its clinical expression
CGD may be X-linked recessive (XLR) or an AR disorder [11,17–19,41] . Nonsense mutation, missense mutations, frameshift, deletions or insertions and splice site mutations were reported in CGD. The mutated CYBB gene, encoding the enzymatic center of the NADPH oxidase gp91phox is on the X chromosome. It accounts for approximately two-thirds of the CGD patients in the Western world, determining a significant male predominance (Table 1) . The AR expressions occur from mutations in CYBA, NCF1 and NCF2 genes, encoding the p22phox (
