Semiquantitative evaluation of hepatic fibrosis by measuring tissue hydroxyproline

Abstract

Background/aims: It is important to evaluate the degree of hepatic fibrosis when diagnosing and treating hepatic cirrhosis. We focused on hydroxyproline, which is detected specifically in collagen, which plays a major role in hepatic fibrosis. The correlations between liver tissue hydroxyproline residue levels and the degree of hepatic fibrosis were examined in dogs with dimethylnitrosamine-induced fibrotic livers.

Methodology: Dimethylnitrosamine was administered to dogs to establish experimental hepatic fibrosis. Paraffinized sections of liver specimens, stained with hematoxylin-eosin and azan, were examined and the degree of hepatic fibrosis was graded. About three-milligram samples of liver tissue were loaded onto a fully automated liquid chromatograph and the levels of hydroxyproline residues were measured.

Results: The liver tissue hydroxyproline appeared to reflect the degree of hepatic fibrosis. The liver tissue hydroxyproline levels and pathological hepatic fibrosis grades correlated significantly (p<0.05).

Conclusions: Tissue hydroxyproline appears to be a more useful fibrosis marker, because hydroxyproline is influenced less by other factors. Furthermore, our results demonstrate that a very small amount of liver tissue (wet weight 3 mg) was enough to enable the levels of hydroxyproline residues to be measured by an automated amino acid analyzer (JLC-3000) and hepatic fibrosis is expressed as the numerical value by this analysis.