Differential expression of serum exosomal miRNAs were detected for NAFLD patients and healthy controls, thereby determining the role of serum exosomal miRNAs in the pathogenesis, diagnosis, and treatment of NAFLD.

Four patients with S2-3 NAFLD who shared similar demographic features and personal histories, and matched healthy controls were recruited for high-throughput sequencing of serum exosomal miRNAs. Four miRNAs with the most significant differential expression were verified by qRT-PCR in three groups (S1, S2-3, and control groups) with 20 cases in each group. Target gene prediction was performed for these differentially-expressed miRNAs, along with GO and KEGG enrichment analyses for the target genes. T-test or ANOVA were used for normally distributed data. Wilcoxon rank sum test was used for ranked data and non-normally distributed data. The count data used Pearson chi-square test or Fisher's exact test.

There were 19 serum exosomal miRNAs with significantly different levels of expression (P < 0.05) and a fold-change > 2. The expression of hsa-miR-122-5p, hsa-miR-146b-5p, and hsa-miR-197-3P was highest in the S2-3 group, followed by the S1 and control groups (in order); hsa-miR-483-3p expression was higher in the NAFLD group (S1 or S2-3) than the control group. There were 84 pathways significantly enriched in target genes. From 20 pathways closely related to NAFLD, at least 5 target genes which were simultaneously correlated to all 10 pathways were screened (PIK3R2, AKT2, AKT3, MAPK1, and NFKB1).

Differential expression of serum exosomal miRNAs was detected in NAFLD patients and healthy controls. Four miRNAs with the greatest fold-changes were assessed to judge the severity of fatty degeneration of the liver. The research findings provide reference for non-invasive identification of new biomarkers and specific targets for NAFLD treatment.

Non-alcoholic fatty liver disease; MicroRNA; Exosome