Search

In contrast to patients with viral hepatitis, patients with nonalcoholic fatty liver disease (NAFLD) can progress to hepatocellular carcinoma during the initial stages of liver fibrosis. Development and implementation of noninvasive methods for diagnosis and progression prediction are important for effective NAFLD surveillance. Mac‐2 binding protein (Mac‐2bp) is a useful nonalcoholic steatohepatitis (NASH) diagnosis biomarker and a powerful prediction biomarker for NAFLD fibrosis stage. Wisteria floribunda agglutinin (WFA)‐positive Mac‐2bp (WFA+‐M2BP) is a novel serum fibrosis biomarker for chronic hepatitis C that has clinical validity. Mac‐2bp and WFA+‐M2BP are also clinical NAFLD biomarker candidates. We examined the efficacy of Mac‐2bp and WFA+‐M2BP for NAFLD assessment using patients with biopsy‐proven NAFLD (n = 510; NAFLD cohort) and subjects who received a health check‐up (n = 2,122; check‐up cohort). In the NAFLD cohort, we set the fibrosis predicting cutoff values as 1.80 (F1), 2.21 (F2), and 2.24 μg/mL (F3). In the subjects with fatty liver from the check‐up cohort (n = 1,291), the serum Mac‐2bp levels were >1.80 μg/mL in 38.6% of the subjects (n = 498), and >2.24 μg/mL in 24.6% of the subjects (n = 318). The NAFLD cohort results indicated that Mac‐2bp and WFA+‐M2BP were equally useful for NASH diagnosis. During the early stages of fibrosis (F1, F2), the increase in Mac‐2bp was statistically significant but WFA+‐M2BP did not increase. Logistic regression analysis revealed that Mac‐2bp was an independent determinant for the prediction of advanced fibrosis stage (≥F2), even when adjusted for WFA+‐M2BP. Immunohistochemical staining of Mac‐2bp revealed that hepatocytes strongly expressed Mac‐2bp in patients with NAFLD. Conclusion: Our results indicated that hepatocyte‐derived Mac‐2bp would be a useful single biomarker for NASH diagnosis and fibrosis stage prediction in patients with NAFLD. (Hepatology Communications 2017;1:780–791)

Nonalcoholic fatty liver disease (NAFLD) includes a broad range of liver pathologies from simple steatosis to cirrhosis and fibrosis, in which a subtype accompanying hepatocyte degeneration and fibrosis is classified as nonalcoholic steatohepatitis (NASH). NASH accounts for approximately 10-30% of NAFLD and causes a higher frequency of liver-related death, and its progression of NASH has been considered to be complex involving multiple genetic factors interacting with the environment and lifestyle.To identify genetic factors related to NAFLD in the Japanese, we performed a genome-wide association study recruiting 529 histologically diagnosed NAFLD patients and 932 population controls. A significant association was observed for a cluster of SNPs in PNPLA3 on chromosome 22q13 with the strongest p-value of 1.4 × 10(-10) (OR = 1.66, 95%CI: 1.43-1.94) for rs738409. Rs738409 also showed the strongest association (p = 3.6 × 10(-6)) with the histological classifications proposed by Matteoni and colleagues based on the degree of inflammation, ballooning degeneration, fibrosis and Mallory-Denk body. In addition, there were marked differences in rs738409 genotype distributions between type4 subgroup corresponding to NASH and the other three subgroups (p = 4.8 × 10(-6), OR = 1.96, 95%CI: 1.47-2.62). Moreover, a subgroup analysis of NAFLD patients against controls showed a significant association of rs738409 with type4 (p = 1.7 × 10(-16), OR = 2.18, 95%CI: 1.81-2.63) whereas no association was obtained for type1 to type3 (p = 0.41). Rs738409 also showed strong associations with three clinical traits related to the prognosis of NAFLD, namely, levels of hyaluronic acid (p = 4.6 × 10(-4)), HbA1c (p = 0.0011) and iron deposition in the liver (p = 5.6 × 10(-4)).With these results we clearly demonstrated that Matteoni type4 NAFLD is both a genetically and clinically different subset from the other spectrums of the disease and that the PNPLA3 gene is strongly associated with the progression of NASH in Japanese population.