Autoantibodies to a miRNA-binding protein Argonaute2 (Su antigen) in patients with hepatitis C virus infection

Objectives Chronic liver diseases caused by hepatitis B (HBV) or C virus (HCV) are common worldwide. Despite reports on autoimmunity in viral hepatitis, studies on autoantibodies associated with systemic rheumatic diseases are inconsistent. Testing of a small number of selected autoantibody specificities using ELISA appears to be one reason for inconsistency. Sera from patients with viral hepatitis were tested by immunoprecipitation that will allow unbiased screening of autoantibodies found in systemic rheumatic diseases. Methods Ninety Mexican patients (37 male, 53 female, 26 HBV, 6 HBV+HCV, 58 HCV) with chronic viral hepatitis, confirmed by nested or RT-nested-PCR, HBsAg and anti-HCV antibodies, were studied. Autoantibodies were tested by immunofluorescence, immunoprecipitation and ELISA. Specificities were verified using reference sera. Results Antinuclear antibodies were found in 38% HBV, 17% HBV+HCV, and 28% in HCV. Autontibodies to Argonaute (Ago2, Su antigen), a microRNA binding protein that plays a key role in RNA-induced silencing complex (RISC), was found in 5% (4164) of HCV or HBV+HCV coinfected patients but not in HBV (0126). Anti-Ago2/Su was found in 112 of I-IFN-treated case vs. 3162 in cases without 1-IFN. HCVdid not have other lupus autoantibodies whereas 19% (5126) of HBV had anti-UlRNP+Ku, Ro+La, RNA polymerase II, or possible U5snRNPs. Conclusion Lupus autoantibodies were uncommon in HCV except anti-Ago2/Su. HCV and I-IFN have many ways to affect TLR signaling, miRNA and miRNA binding protein Ago2/Su. To understand the mechanism of specific targeting of Ago2 in HCV may provide a clue to understand the mechanism of specific autoantibody production. Zapotitlán 2010 Copyright CLINICAL AND EXPERIMENTAL RHEUMATOLOGY