Advances in the clinical use of collagen as biomarker of liver fibrosis.

Introduction Hepatic fibrosis is the excessive synthesis and deposition of extracellular matrix including collagen in the tissue. Chronic liver insult leads to progressive parenchymal damage, portal hypertension, and cirrhosis. Determination of hepatic collagen by invasive liver biopsy is the gold-standard to estimate severity and stage of fibrosis. However, this procedure is associated with pain, carries the risk of infection and bleeding, and is afflicted with a high degree of sampling error. Therefore, there is an urgent need for serological collagen-derived markers to assess collagen synthesis or turnover. Areas covered Biochemical properties of collagens, cellular sources of hepatic collagen synthesis, and regulatory aspects in hepatic collagen expression. Markers are discussed suitable to estimate hepatic collagen synthesis and/or turnover. Discussed studies were identified through a PubMed search done in May 2020 and the authors' topic knowledge. Expert opinion Hepatic fibrosis is mainly characterized by accumulation of collagen-rich scar tissue. Although traditionally performed liver biopsy is still standard in estimating hepatic fibrosis, there is evidence that non-invasive diagnostic scores and collagen-derived neo-epitopes provide clinical useful information. These non-invasive tests are less expensive than liver biopsy, better tolerated, safer and more acceptable to patients. Therefore, these tests will lead to dramatic changes in diagnosis.