Exosomal miRNA analysis for classifying severity of disease in biopsy-proven NAFLD patients

초록

Background and aims: Non-alcoholic fatty liver disease (NAFLD) is becoming leading cause of chronic liver disease. Although determining the exact mechanisms that lead to NAFLD and NASH is important for disease identification, factors that regulate disease progression are largely unknown. In this study, we analyzed serum exosomal miRNA from biopsy-proven NAFLD patients and compared miRNA expression according to disease severity. Method: Sera were collected from 41 patients with biopsy-proven NAFLD without other chronic liver disease from November 2016 to January 2018. Sera were stored at −20°C and thawed for isolation of the exosome. Exosomes were isolated from sera using an exosome isolation kit. Total RNA was extracted from exosomes and microarray was performed. Results: Mean age and BMI were 53.5 ± 12.3 years and 29.9 ± 4.6 kg/m2, respectively. Female was dominant (n = 34, 82.9%). In microarray analysis, total 2, 578 miRNAs were identified. We classified patients into non-significant fibrosis group (F0-2, n = 25) and significant fibrosis group (F3-4, n = 16). 40 miRNAs expression were significantly increased in advanced fibrosis group comparing with non-advanced fibrosis group. (Figure) Among them, miRNA4668 and miRNA3613 were increased more than 8 times in advanced fibrosis group comparing with non-advanced fibrosis group. Whereas 22 miRNAs expression were significantly increased in non-advanced fibrosis group comparing with advanced fibrosis group. When patients were classified into NASH group (n = 19) and non-NASH group (n = 22), 4 miRNAs showed higher expression comparing with NAFL group, whereas 1 miRNAs showed lower expression in NASH group comparing with NAFL group. In comparison between severe inflammation group (grade 2, 3, n = 25) and mid inflammation group (grade 0, 1, n = 16), severe inflammation group showed higher expression of 1 miRNA and lower expression of 9 miRNAs comparing with mid inflammation group. Conclusion: miRNA expression analysis showed significant differences according to status of fibrosis, NASH, and inflammation. These results mean miRNA expression might be important factor for disease progression in NALFD patients. Further validation studies are needed to identify the role of miRNA in disease progression of NAFLD.