Serum hyaluronic acid level: Correlation with quantitative measurement of hepatic fibrosis in a cirrhotic rat model

BACKGROUNDS/AIMS: The serum level of hyaluronic acid (HA) has been suggested as a useful serologic marker for hepatic fibrosis. However, the relationship between serum HA levels and quantitative markers of fibrosis from liver tissue has not been reported. The aim of this study was to determine the correlation between serum HA level and quantitative measurement of hepatic fibrosis in a cirrhotic rat model. METHODS: Cirrhosis was produced by common bile duct ligation (BDL) in adult Sprague-Dawley rats. The animals were classified into four groups: (1) G1, sham operated (n=5); (2) G2, BDL for 2 weeks (n=6); (3) G3, BDL for 3 weeks (n=6); and (4) G4, BDL for 4 weeks (n=6). Hepatic fibrosis was analyzed histomorphologically using the Batts and Ludwig scoring system. Serum HA level and hepatic hydroxyproline content were quantified. The gene expressions in the liver of procollagen, collagen, and transforming growth factor-beta (TGF-beta) were measured by reverse transcriptase-polymerase chain reaction. RESULTS: In groups G1, G2, G3, and G4, the Batts and Ludwig scores (mean+/-SD) were 0, 1.3+/-0.5, 2.6+/-0.5, and 3.4+/-0.5, respectively (P<0.05), serum HA levels were 12.5+/-3.2, 30.0+/-4.3, 228.6+/-157.7, and 391.3+/-207.7 ng/mL (P<0.05), and the concentration of hydroxyproline was 12.4+/-2.8, 17.6+/-3.8, 17.9+/-2.4, and 33.4+/-3.4 microg/g liver tissue, and it was significantly higher in group G4 than in the other groups (P<0.05). The gene expressions of collagen, procollagen, and TGF-beta1 in the liver were also significantly higher in group G4 compared with the other groups (P<0.05). Direct linear correlations were observed between serum HA level and hepatic hydroxyproline content, hepatic gene expressions of collagen, procollagen, TGF-beta1, and histomorphological grade of hepatic fibrosis (P<0.001). CONCLUSIONS: These results indicate that serum HA is a useful and noninvasive serologic marker for the evaluation of advanced hepatic fibrosis.