Inducible nitric oxide synthase and histopathological correlation in chronic viral hepatitis

Chronic liver disorders represent a serious health problem. Nitric oxide (NO) synthesized by inducible nitric oxide synthase (iNOS) can function as an antimicrobial agent able to kill or reduce replication of microorganisms, and plays an important role in immune regulation. This study was undertaken to evaluate the expression of iNOS in chronic viral hepatitis and its relation to histopathology.

This study included 56 patients with chronic viral hepatitis (38 hepatitis B, 18 hepatitis C). There were 35 men and 21 women with a mean age of 38.6+/-21.731 years. A modified form of the histology activity index (HAI) designed by Ishak and colleagues was used to assess grading and staging of chronic viral hepatitis. The needle biopsy specimens were fixed in 10% formalin and routinely processed. Routine hematoxylin-eosin, periodic acid-Schiff, and reticulin staining, and iNOS immunoperoxidase technique were performed on paraffin-embedded tissues.

We demonstrated that all liver samples had a marked iNOS expression, with a diffuse distribution pattern. iNOS consistently labeled mononuclear cells infiltrating portal tracts in all samples. Statistical evaluation of data showed that the iNOS expression correlated with the HAI and fibrosis. Furthermore a correlation between iNOS and severity of disease was detected (r=0.772, p=0.000).

Further investigations are required to determine whether iNOS-related treatment protocols could be useful in reducing disease severity.