Clinical and experimental studies on collagen metabolism in hepatic disorders.

Collagen metabolism was studied in patients with viral hepatitis, chronic hepatic disorders as well as under experimental conditions, in rats with carbon tetrachloride-induced hepatic fibrosis. Changes in serum hydroxyproline, hydroxylysine and collagen-like protein levels, and collagen peptidase activity were observed in clinical investigations. An increase of collagen content and collagen-glycosaminoglycan interactions were found in the liver samples of rats with the hepatic fibrosis. An increase of collagenase activity in the course of fibrosis is due to an elevated biosynthesis of the enzyme de novo as well as to a decreased content of inhibitors. The activity of collagen peptidase and collagenolytic cathepsin were increased, and it was suggested that an increase of collagen degradation in the liver was a self-defensive mechanism against fibrosis but insufficient to protect the organ against it. This was caused probably by changes in susceptibility of collagen to degradating enzymes in the course of chronic hepatic disorders.