Role of Angiopoietin-2 Serum Levels In Noninvasive Diagnosis of Different Stages of Liver Fibrosis In Chronic Hepatitis C Patients

Abstract

Angiopoietins are a family of vascular growth factors that play a role in embryonic and postnatal angiogenesis (Barton et al., 2005 ). It is responsible for assembling and disassembling the endothelial lining of blood vessels (Alves et al., 2010 ). Angiopoietin cytokines are involved in controlling microvascular permeability and allowing the smooth muscle cells and smooth muscle-like pericytes to cover the vessels making vasodilation and vasoconstriction possible (Scott, 2010 ). There are now 4 identified angiopoietins, called : angiopoietin-1, angiopoietin-2, angiopoietin-3, and angiopoietin-4. Angiopoietin-2, promotes cell death and disrupts vascularization. Yet, when it is in conjunction with vascular endothelial growth factors (VEGF), it can promote neo-vascularization (Fagiani and Christofori , 2013 ). Hepatitis C virus (HCV) infection is a major global health problem, because it leads to chronic injury of the liver in a high percentage of acutely infected patients (Seeff, 2002 ).The persistence of inflammatory responses and cellular damage promotes disease progression towards fibrosis, cirrhosis, and hepatocellular carcinoma (Zhang and Friedman, 2012). Thus, accurate evaluation of hepatic fibrosis has become the primary goal in managing the progression of chronic hepatitis C (CHC (Friedman, 2008 ). Based on the link between serum angiopoietin- 2 levels and CHC progression, a recent study in Madrid, aimed to determine its diagnostic value as a noninvasive biomarker of liver fibrosis. They proved that angiopoietin -2 serum concentrations rose progressively with the stage of fibrosis,a pattern that was significant between F1 and all other fibrosis stages and between F2 and F4. Notably, angiopoietin -2 increased with the stage of fibrosis and differentiated F2 and F3, as well as F3 and F4 (P<0.05) (Samuel et al., 2013 ). In addition, the decision of physicians to administer antiviral therapy depends on the stage of fibrosis. Liver biopsy (LB) is the standard for determining the stage of fibrosis, but due to its invasiveness, risk of complications, and potential for sampling errors, noninvasive markers are being sought as alternative diagnostic tools (Castera , 2012 ).