Diseasespecific autoantibodies in patients with ... - Wiley Online Library

1096

CORRESPONDENCE

tion of TGF-␤ such as growth inhibition and apoptosis of hepatocytes. For example, Bcl-2 repression by TGF-␤ requires C-terminal phosphorylation of Smad3.6 To evade apoptosis, HCC might acquire Bcl-2 overexpression induced by pSmad3L pathway. Escaping apoptosis is a critical step in the progression to full malignancy of cancers, which overcome multiple fail-safe genetic controls. From the viewpoint of TGF-␤ signaling, a key therapeutic aim in cancer would be restoration of the lost tumor suppressor function observed in normal hepatocytes at the expense of effects promoting aggressive behavior in HCC. Our model suggests that specific inhibitors of the pSmad3L-mediated oncogenic/fibrogenic signaling should inhibit progression of HCC. KOICHI MATSUZAKI Departments of Gastroenterology and Hepatology, Kansai Medical University, Osaka, Japan IWATA OZAKI Health Administration Center, Saga Medical School, Saga University, Saga, Japan

References 1. Matsuzaki K, Murata M, Yoshida K, Sekimoto G, Uemura Y, Sakaida N, et al. Chronic inflammation associated with hepatitis C viral infection perturbs

HEPATOLOGY, March 2008

2. 3.

4.

5.

6.

hepatic TGF-␤ signaling, promoting cirrhosis and hepatocellular carcinoma. HEPATOLOGY 2007;46:48-57. Zavadil J, Bottinger EP. TGF-␤ and epithelial-to-mesenchymal transitions. Oncogene 2005;24:5764-5774. Weng HL, Ciuclan L, Liu Y, Hamzavi J, Godoy P, Gaitantzi H, et al. Profibrogenic transforming growth factor-␤/activin receptor-like kinase 5 signaling via connective tissue growth factor expression in hepatocytes. HEPATOLOGY 2007;46:1257-1270. Kaimori A, Potter J, Kaimori JY, Wang C, Mezey E, Koteish A. Transforming growth factor-beta1 induces an epithelial-to-mesenchymal transition state in mouse hepatocytes in vitro. J Biol Chem 2007;282:2208922101. Sekimoto G, Matsuzaki K, Yoshida K, Mori S, Murata M, Seki T, et al. Reversible Smad-dependent signaling between tumor suppression and oncogenesis. Cancer Res 2007;67:5090-5096. Yang YA, Zhang GM, Feigenbaum L, Zhang YE. Smad3 reduces susceptibility to hepatocarcinoma by sensitizing hepatocytes to apoptosis through downregulation of Bcl-2. Cancer Cell 2006;9:445-457.

Copyright © 2008 by the American Association for the Study of Liver Diseases. Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hep.22199 Potential conflict of interest: Nothing to report.

Disease-Specific Autoantibodies in Patients with Acute Liver Failure: The King’s College London Experience To the Editor: We read with interest the article by Leung et al.,1 who investigated the presence of antimitochondrial antibodies (AMAs), the hallmark of primary biliary cirrhosis, in patients with acute liver failure (ALF). This is a condition frequently characterized by oxidative stress,2 which is a possible trigger for AMA production3; this is the rationale of the study. As controls, antibodies to glycoprotein 210 kDa (gp210), speckled protein 100 kDa (sp100), centromere, chromatin, soluble liver antigen (SLA), tissue transglutaminase, and deaminated gliadin peptides were also studied. AMAs were sought by a highly sensitive and specific triple-hybrid (mitochondrial antigen 3 [MIT3]) enzyme-linked immunosorbent assay (ELISA) containing the immunodominant mitochondrial epitopes of E2 subunits of pyruvate dehydrogenase, branched chain 2-oxo-acid dehydrogenase, and 2-oxo-glutarate dehydrogenase and were found in 28/69 (40.6%) patients, 9 (13%) of whom had acetaminophen-related ALF. The only additional antibody reactivity present in a significant percentage (57.1%) was that against anti–tissue transglutaminase, whereas other autoantibodies such as those against SLA were practically absent when testing was performed with a commercially available ELISA.1 Investigating an autoimmune component of ALF, we recently described autoantibody reactivity in an ALF series in the United Kingdom comprising 73 patients4 and, in apparent contrast to Leung et al.,1 found virtually no AMAs (1/73, 1%) through testing with immunofluorescence but did find anti-SLA antibodies in 22% through testing with a sensitive radioligand assay.5 Because discrepancies between the two studies may be due to methodological differences, we retested 47 of our ALF patients in whom sera were available both by conventional indirect immunofluorescence6 and by an MIT3 ELISA similar to that used by Leung et al. Although all sera remained negative for AMA by immunofluorescence, 13/47 (28%) were positive by the MIT3 assay. Conversely, when for the detection of anti-SLA we used an ELISA kit similar to that used by Leung et al. which is less sensitive than a radioligand assay, we also found practically no antibody reac-

tivity. Our results indicate the influence of the methodological approach on the results obtained in comparable patient cohorts. We can anticipate anti-SLA to be present in the American series if a sensitive radioligand assay is used for their detection. We found no relation between the presence of anti-MIT3 AMAs and patient age, sex, biochemical parameters of liver injury, immunoglobulin response mode of presentation of ALF, or outcome of illness. Both Leung et al.’s study1 and our study show that autoantibody reactivity is frequent in a condition such as ALF characterized by extensive release of autoantigens subsequent to massive liver damage. This autoreactivity is, however, transient because, on repeat testing, AMAs in Leung et al.’s study and anti-SLA in our own cohort disappear. In conclusion, reactivities to antigens specific to autoimmune liver diseases are present in the course of ALF, although their detection depends on the methodology used. These specific autoimmune reactivities are likely to arise from the release of antigens from damaged hepatocytes and stimulation of lymphocytes that have escaped negative deletion, but they do not, however, progress to chronic autoimmune liver disease, probably because of the intervention of regulatory mechanisms after the acute phase of the disease is over. A deficiency of such mechanisms characterizes both autoimmune hepatitis and primary biliary cirrhosis.6-8 In view of the discrepancy in results when different techniques are used, standardization of methodological approaches for autoantibody detection is warranted to avoid confusing the clinician. WILLIAM BERNAL FRANCESCA MEDA YUN MA DIMITRIOS P. BOGDANOS DIEGO VERGANI Institute of Liver Studies King’s College London School of Medicine at King’s College Hospital London, United Kingdom

HEPATOLOGY, Vol. 47, No. 3, 2008

References 1. Leung PS, Rossaro L, Davis PA, Park O, Tanaka A, Kikuchi K, et al. Antimitochondrial antibodies in acute liver failure: implications for primary biliary cirrhosis. HEPATOLOGY 2007;46:1436-1442. 2. Ferret PJ, Hammoud R, Tulliez M, Tran A, Trebeden H, Jaffray P, et al. Detoxification of reactive oxygen species by a nonpeptidyl mimic of superoxide dismutase cures acetaminophen-induced acute liver failure in the mouse. HEPATOLOGY 2001;33:1173-1180. 3. Wu CT, Eiserich JP, Ansari AA, Coppel RL, Balasubramanian S, Bowlus CL, et al. Myeloperoxidase-positive inflammatory cells participate in bile duct damage in primary biliary cirrhosis through nitric oxide-mediated reactions. HEPATOLOGY 2003;38:1018-1025. 4. Bernal W, Ma Y, Smith HM, Portmann B, Wendon J, Vergani D. The significance of autoantibodies and immunoglobulins in acute liver failure: a cohort study. J Hepatol 2007;47:664-670. 5. Ma Y, Okamoto M, Thomas MG, Bogdanos DP, Lopes AR, Portmann B, et al. Antibodies to conformational epitopes of soluble liver antigen define a severe form of autoimmune liver disease. HEPATOLOGY 2002;35:658-664. 6. Longhi MS, Ma Y, Bogdanos DP, Cheeseman P, Mieli-Vergani G, Vergani D. Impairment of CD4(⫹)CD25(⫹) regulatory T-cells in autoimmune liver disease. J Hepatol 2004;41:31-37. 7. Longhi MS, Ma Y, Mitry RR, Bogdanos DP, Heneghan M, Cheeseman P, et al. Effect of CD4⫹ CD25⫹ regulatory T-cells on CD8 T-cell function in patients with autoimmune hepatitis. J Autoimmun 2005;25:63-71. 8. Longhi MS, Hussain MJ, Mitry RR, Arora SK, Mieli-Vergani G, Vergani D, et al. Functional study of CD4⫹CD25⫹ regulatory T cells in health and autoimmune hepatitis. J Immunol 2006;176:4484-4491.

CORRESPONDENCE

1097


Reply: Unless we are both studying the same sera, there is no basis of comparison. In our clinical cases and I assume their clinical series, many types of ALF were studied and we both found AMAs when we used the same method. It is also obvious that no international standardization exists, and measurements of all these antibodies will not be standardized until the release of the newer multiphasic kits in 2009 and beyond. M. ERIC GERSHWIN, M.D. Division of Rheumatology/Allergy University of California, Davis Medical Center Sacramento, CA


Adoptive Transfer of Regulatory T Cells in an Animal Model of a Diet-Induced Fatty Liver To the Editor: I read with interest an excellent study by Ma et al. that clarified the mechanisms of progression from hepatic steatosis to nonalcoholic steatohepatitis (NASH) in a mouse model of a high-dietinduced fatty liver.1 The authors revealed that CD4⫹ CD25⫹ forkhead box P3⫹ hepatic regulatory T cells (T regs) decreased during the administration of a high-fat diet, and the levels of T regs were less than half of those in control mice at the end of the 8-week experiment. Marked reduction of T regs, which was caused by apoptosis due to oxidative stress, was associated with enhanced expression of tumor necrosis factor (TNF) alpha and its intracellular mediators in liver. Adoptive-transferred T regs suppressed highfat diet-induced intrahepatic TNF alpha signaling. Mice in which T regs were depleted or T regs were transferred, both of which were fed diets containing a high amount of fat, were given a single relatively low dose of lipopolysaccharide (LPS) (100 ␮g/mouse) to induce hepatic injury. Six hours after injection of LPS, LPS-induced liver damage was compared between the groups. A pretreatment with adoptive transfer of T regs significantly attenuated hepatotoxicity of LPS in mice with hepatic steatosis. The authors speculate that enhanced LPS signaling followed by proinflammatory cytokine production as a second hit necessary for the progression from steatosis to nonalcoholic steatohepatitis can be reduced by restoring the function of T regs. T regs are engaged in the regulation of organ-specific immune responses to pathogens and self-proteins. A recent in vitro study indicates that activated T regs rapidly inhibit induction of Th1 cytokine mRNA, whereas suppression of anti-inflammatory Th2 cytokines is delayed.2 This article by Ma and colleagues may be the cornerstone for a better understanding of a variety of immunerelated liver diseases in addition to nonalcoholic liver disease. I would like to ask the authors whether animal models with chronic

endotoxemia, which are described in a recent article,3 are more suitable than those with acute endotoxemia for the study to investigate the role of T regs in liver disease. Mild chronic endotoxemia has been observed in chronic liver disease,4 chronic kidney disease,5 and chronic cardiovascular disease.6 TETSUJI FUJITA, M.D. Department of Surgery Jikei University School of Medicine Tokyo, Japan

References 1. Ma X, Hua J, Mohamood AR, Hamad ARA, Ravi R, Li Z. A high-fat diet and regulatory T cells influence susceptibility to endotoxin-induced liver injury. HEPATOLOGY 2007;46:1519-1529. 2. Oberle N, Eberhardt N, Falk CS, Krammer PH, Suri-Payer E. Rapid suppression of cytokine transcription in human CD4⫹CD25⫺ T cells by Foxp3⫹ regulatory T cells: independence of IL-2 consumption, TGF-␤, and various inhibitors of TCR signaling. J Immunol 2007;179:35783587. 3. Cani PD, Amar J, Iglesias MA, Poggi M, Knauf C, Bastelica D, et al. Metabolic endotoxemia initiates obesity and insulin resistance. Diabetes 2007;56:1761-1772. 4. Fukui K. Relation of endotoxin, endotoxin binding proteins and macrophages to severe alcoholic liver injury and multiple organ failure. Alcohol Clin Exp Res 2005;29:172S–179S. 5. Gonçalves S, Pecoits-Filho R, Perreto S, Barberato SH, Stinghen AEM, Lima EGA, et al. Association between renal function, volume status and endotoxaemia in chronic kidney disease patients. Nephrol Dial Transplant 2006;21:2788-2794.