Serum exosomal mir-4668-5p in Non-alcoholic Fatty liver Disease (NAFLD) patients with significant liver fibrosis

초록

Background and aims: In worldwide, fatty liver disease in nonsignificant amount of alcoholic drinker (Non-alcoholic fatty liver disease (NAFLD)) are on the rise as obesity and diabetes increase. Among the histologic changes, degree of liver fibrosis is the most important factor for predicting long term outcomes. Although liver biopsy is the gold standard for diagnosis, serious complication and variability of sampling and interpretation made it difficulties in routine clinical practice. Aim of our study is to explore the clinical significance of serum exosomal miRNA in liver fibro-genesis of NAFLD patients. Method: 47 biopsy-proven NAFLD patients were included. Exosome was isolated from serum samples and serum exosomal miRNA was analyzed with GeneChip miRNA 4.0 array (Affymetrix, U.S.A). Also, we analyzed the expression of miRNA in liver tissues of the same patient who had been tested for serum exosomal miRNA. To define the role of miRNA in liver fibrogenesis, human hepatic stellate cell was transfected with miRNA of interests. Serum and liver samples from mice feed with high fat high fructose (HFHF) diet for 24 weeks were analyzed for comparison with human. Results: NAFLD patients with advance fibrosis group (Gr1) were older, having more metabolic syndrome, lower platelet counts, prolonged PT INR compared to that of non-significant fibrosis group (Gr2). A total of 86 serum exosomal miRNA were significantly changed between Gr.1 and Gr.2, Of which 42- and 44-miRNA showed significantly higher or lower expression in Gr.1 compared to Gr.2. Of them, MiR4668-5p was selected because of it were one of the highest altered miRNA in Gr.1 compare to Gr.2. When human hepatic stellate cell (LX2 cell) was transfected with 4668-5p mimics or inhibitors, mRNA of TGF-β, α-SMA and collagen1A1 expression were significantly elevated and reduced after each transfection. In mice feed with HFHF diets, mRNAs involved in lipid uptake, transport, and oxidation were altered. TGF-b1 and a-SMA and col1A1 expression were altered in HFHF group. Conclusion: Serum exosomal miRNAs were significantly altered in NAFLD patients with advanced fibrosis. Among them, serum exosomal miRNA-4668-5p has significant role in liver fibrosis. Although additional researches are required, serum exosomal miRNA may has a diagnostic value or therapeutic target of liver fibrosis in NAFLD patients.