Serological tissue turnover profile of structural proteins in liver fibrosis associated with chronic hepatitis C

Abstract

Introduction: Liver fibrosis is a pathological change of the extracellular matrix (ECM) involving extensive connective tissue remodelling. Small fragments of ECM proteins are generated as a result of increased matrix metalloproteinase (MMP) activity, and the ends of these fragments present new antigenic sites (neo-epitopes), which can be measured in the circulation. We investigated the association between stages of liver fibrosis in chronic hepatitis C patients and neo-epitope markers of the following ECM components: Type I (C1M), type III (C3M) and type VI (C6M) collagen degraded by MMPs as well as the formation of type VI (P4NP 7S) collagen. Materials and methods: One-hundred four patients with hepatitis C virus (HCV) not previously submitted to antiviral treatment included from Hospital de Clínicas, Universidade Federal do Rio Grande do Sul, Brazil, and compared to 15 healthy controls, none of which were diagnosed with chronic liver disease. Liver biopsies were assessed for fibrotic stage (F) and inflammatory activity (A) according to the METAVIR criteria. The HCV diagnosis was documented by HCV RNA in the serum. Serum samples were collected from fasting hepatitis C patients at time of biopsy and stored at -80 o C until use. Serum C1M, C3M, C6M, P4NP 7S was assessed using newly developed and technically robust competitive ELISA platforms. Results: All ECM markers were elevated in patients without fibrosis (F0) by up to +139% compared to healthy controls (p > 0.0001) and C1M, C3M and P4NP 7S in patients with mild fibrosis (F1) by up to +138% compared to controls (p > 0.0001). None of the markers were elevated in score F2-4 except for C3M which also was elevated in the group F3-4. C3M was elevated in groups A0-1 and A2-3 (up to +133% compared to controls, p < 0.0001) and C1M in group A0-1 (p > 0.05). C6M and P4NP 7S was not related to the activity scores. Discussion and conclusion: We demonstrated that these novel biomarkers were elevated during early fibrosis in serum of hepatitis C patients compared to healthy controls. Data indicate that these markers are valuable for the evaluation of liver fibrosis progression as a panel of structural protein remodeling markers.