Predictors reflecting the pathological severity of non-alcoholic fatty liver disease: comprehensive study of clinical and immunohistochemical findings in younger Asian patients.

BACKGROUND AND AIMS: The spectrum of non-alcoholic fatty liver disease (NAFLD) ranges from simple steatosis to severe steatohepatitis (NASH). The aim of our study was to identify clinical predictors distinguishing NASH from steatosis and to study the pathogenesis of NASH in a young Korean population.

METHODS: Clinical and biochemical variables from 39 biopsied NAFLD patients were retrospectively analyzed. All liver biopsy specimens were immunohistochemically examined for Kupffer cells (CD68, CD14), as well as expression of tumor necrosis factor-alpha (TNF-alpha) and mitochondrial uncoupling protein 2 (UCP-2).

RESULTS: There were no significant differences in serum biochemistry between the two groups (15 steatosis vs 24 NASH). There was a significant difference between the body mass index (BMI) values (kg/m(2)) of the NASH (28.4 +/- 3.4 kg/m(2)) and steatosis (25.8 +/- 2.8 kg/m(2)) patients (P < 0.025), with a BMI of 28.9 kg/m(2) representing the best threshold for distinguishing NASH from steatosis patients. BMI was significantly related to the degree of fibrosis (P < 0.01). CD68+ Kupffer cells were more common in the livers of NASH patients (P < 0.05), and TNF-alpha and UCP-2 were expressed in all NASH specimens and were related with the severity of inflammation and fibrosis (P < 0.05).

CONCLUSIONS: BMI could be used to distinguish NASH from steatosis in younger Korean patients. A high BMI with a low alanine aminotransferase (ALT) value tended to suggest the presence of severe fibrosis in NASH, while the number of CD68+ Kupffer cells and the staining intensity of TNF-alpha and UCP-2 were correlated with general pathologic severity in patients with NAFLD.