Overexpression of hepatic inducible nitric oxide synthase in biliary atresia

Aims: Biliary atresia (BA) is a rare and serious liver disease in infants characterized by progressive inflammatory cholangiopathy. The aims of this study were to investigate hepatic expression of inducible nitric oxide synthase (iNOS) in BA and to associate the iNOS expression with their early therapeutic outcome. Methods: Hepatic iNOS expression was determined using immunohistochemistry from liver biopsies of 24 BA patients, and 16 non‐BA patients whose liver tissues were needed in the treatment process. Six months after surgery, the BA patients were categorized into two groups;good and poor outcome. The iNOS expression of hepatocyte areas was evaluated based on its intensity using ImageJ software. Unpaired t‐tests were used for the comparisons of iNOS expression between groups. Results: Hepatic iNOS expression of BA patients was significantly stronger than that of non‐BA patients (P < 0.0001). The largest area of hepatic iNOS expression was the area of hepatocytes. Subgroup analysis of BA patients at 6 months post‐op revealed that there was no difference in iNOS expression between the patients with good outcome and those with poor outcome (P = 0.732). Conclusions: Overexpression of hepatic iNOS in BA patients was demonstrated. Within liver tissues, hepatocytes were the major source of hepatic iNOS production. However, the expression was not associated with the early therapeutic outcome. These results suggest that iNOS plays a role in the liver pathology of BA but its expression cannot be used as a predictor for therapeutic outcome.