Decreased Serum NAD Glycohydrolase Activities in Liver Cirrhosis

Ahn, Chul Min; Seo, Jae Seok; Kim, Dae Ghon; Ahn, Deuk Soo

Abstract

BACKGROUND/AIMS: NAD glycohydrolase (NADase) is abundantly expressed in the liver. This expression is prominent in Kupffer cells. Since it was recognized that reticulendothelial function is impaired in liver cirrhosis, we assessed how these enzyme activities were altered in patients with liver cirrhosis. METHODS: Serum samples were obtained from 61 patients with liver cirrhosis (according to the criteria of Child-Pugh 15 were classified A, 24 were classified B, and 22 were classified C) and 16 healthy subjects. NADase activities were measured fluorometrically with [adenine-14C] NAD. The reaction mixture contained [adenine-14C] NAD and enzyme (patient serum). The reaction was stopped after a 30 to 480 min incubation by the addition of 50 L of 25% trichloroacetic acid. RESULTS: Serum NADase activities in 61 patients with liver cirrhosis were significantly lower than those in healthy subjects (33+/-14 vs. 55.6+/-13 p<0.001). Serum NADase activities in severe cirrhotic patients were significantly lower than those in mild to moderate cirrhotic patients (criteria of Child-Pugh, A: 40.6+/-6.4 vs. B: 38.6+/-13 vs. C: 21.8+/-14, p<0.001). NADase activities were correlated to prothrombin time (r = 0.69), and Apo A1 (r = 0.58) that were useful in identifying high-risk subjects for severe liver disease, but not asparate aminotransferase (AST) and alanine aminotransferase (ALT). Also, NADase activities reciprocally correlated with PGAA index (r = -0.78), Child-Pugh's score (r = -0.48), and serum alpha-2-macroglobulin (r = -0.72). CONCLUSIONS: NADase activities could be used as a single diagnostic marker for liver cirrhosis in addition to the Child-Pugh's score and PGAA index.