Differential expression of miRNAs in the visceral adipose tissue of patients with non-alcoholic fatty liver disease.

Background: Progression of non-alcoholic fatty liver disease (NAFLD) can be facilitated by soluble molecules secreted by visceral adipose tissue (VAT). MicroRNAs (miRNAs) are likely to regulate some of these molecular pathways involved in pathogenesis of NAFLD.

Aim: To profile miRNA expression in the visceral adipose tissue of patients with NAFLD.

Methods: Visceral adipose tissue samples were collected from NAFLD patients and frozen. Patients with biopsy-proven NAFLD were divided into non-alcoholic steatohepatitis (NASH) (n = 12) and non-NASH (n = 12) cohorts controlled for clinical and demographic characteristics. Extracted total RNA was profiled using TaqMan Human MicroRNA arrays. Univariate Mann-Whitney comparisons and multivariate regression analysis were performed to compare miRNA profiles.

Results: A total of 113 miRNA differentially expressed between NASH patients and non-NASH patients (P < 0.05). Of these, seven remained significant after multiple test correction (hsa-miR-132, hsa-miR-150, hsa-miR-433, hsa-miR-28-3p, hsa-miR-511, hsa-miR-517a, hsa-miR-671). Predicted target genes for these miRNAs include insulin receptor pathway components (IGF1, IGFR13), cytokines (CCL3, IL6), ghrelin/obestatin gene, and inflammation-related genes (NFKB1, RELB, FAS). In addition, two miRNA species, hsa-miR-197 and hsa-miR-99, were significantly associated with pericellular fibrosis in NASH patients (P < 0.05). Levels of IL-6 in the serum negatively correlated with the expression levels of all seven miRNAs capable of down regulating IL-6 encoding gene.

Conclusions: miRNA expression from VAT may contribute to the pathogenesis of NAFLD - a finding which may distinguish relatively simple steatosis from NASH. This could help identify potential targets for pharmacological treatment regimens and candidate biomarkers for NASH.