Immunodetection of collagen types I, II, III, and IV for differentiation of liver fibrosis stages in patients with chronic HCV.

The current study is aimed at evaluating serum collagens and other serum biochemical markers as useful, non-invasive markers of hepatic fibrosis associated with chronic hepatitis C virus (HCV). Collagen types I, II, III, and IV were detected in serum using ELISA and Western blot techniques. The ELISA levels of collagen I, II, III, and IV increased significantly with the progression of fibrosis staging. Based on receiver-operating characteristic (ROC) curve analysis, the collagen type III (70 kDa) and type IV (200 kDa) were more useful than other serum bio-markers for differentiating severe fibrosis from mild fibrosis. Multivariate discriminant analysis (MDA) selected a fibrosis discriminant score (FDS) = [2.345 + Collagen III (microg/mL) x 1.923 + Collagen IV (microg/mL) x 1.544 + ALT (U/mL) x 0.005] - [albumin(g/L) x 0.046]. The FDS correctly classified 87% of the severe fibrosis patients at a cut-off score = 2.2 (i.e., more than 2.2 indicated severe fibrotic liver and less than 2.2 indicated mild fibrotic liver) with specificity of 97%. In a validation study, the FDS was applied to the second cohort of patients and the results were reproduced without significant difference. In conclusion, the developed four-parameter based FDS is useful for identifying severe liver fibrosis in patients with chronic HCV infection.