OBJECTIVETo investigate the intrahepatic expression of inducible nitric oxide synthase (iNOS) in patients with chronic hepatitis B (CHB) and its relation to liver histopathology.

METHODSThe intensity and distribution of the immunohistochemical staining of intrahepatic iNOS were studied in the liver biopsy specimens obtained from 74 patients with CHB and statistical analyses were performed between intrahepatic iNOS and ALT, HbeAg, HBV DNA grading of liver inflammation and staging of fibrosis. Seven histologically normal liver sections were used as a control group.

RESULTSCompared with the control group, the intrahepatic iNOS immunoexpression was significantly higher in patients with CHB (P < 0.05), iNOS immunoreactivity was observed mainly in hepatocytes showing a predominant cytoplasmic staining, with the positive liver cells distributed diffusely throughout the hepatic lobule. Immunopositive staining could also be detected in Kupffer cells, sinusoidal lining cells and vascular endothelial cells. Compared with patients with normal ALT, the hepatocellular iNOS immunoexpression was significantly higher in patients with elevated ALT (P < 0.05) and the iNOS immunoexpression was significantly correlated with the serum level of ALT (r=0.601, P=0.000). Statistical analysis also showed that the intrahepatic iNOS immunoexpression was positively correlated with the grading of liver inflammation and the staging of liver fibrosis (r=0.660, P=0.000; r=0.507, P=0.000). No significant correlation between iNOS and HBeAg and HBV DNA was detected. CONCLUSION The intrahepatic expression of iNOS is elevated in chronic hepatitis B patients and correlated well with the severity of the disease, which indicated that inducible nitric oxide synthase may have a critical role in the pathogenesis of chronic viral hepatitis B.