Hepatic transcriptome signature correlated with HOMA-IR explains early nonalcoholic fatty liver disease pathogenesis.

INTRODUCTION AND OBJECTIVES: Non-alcoholic fatty liver disease (NAFLD) is multistage with heterogeneous outcomes. We studied the influence of insulin resistance (IR) on the hepatic transcriptome of early NAFLD stages, to understand disease development.

MATERIALS AND METHODS: In this cross-sectional study, possible clinicopathological risk factors were compared between mild-NAFL (N = 72) and non-alcoholic steatohepatitis (NASH; N = 51) patients. Liver tissue-transcriptome difference was studied between a subset of 25 mild-NAFL and 20 NASH biopsies and validated on another subset of 12 mild-NAFL and 13 NASH biopsies, using RT-PCR. The relationship between IR driven gene expression changes with fibrosis in NASH was investigated.

RESULTS: Significantly higher weight (p = 0.005) and elevated levels of HbA1c (p = 0.009), FBG (p = 0.03) and HOMA-IR (p = 0.009) were found in NASH patients. Five differentially expressed genes (DEGs, fold change > 1.5) were identified in NASH-FABP4, FABP5L2, CD24, PRAP1, and SPP1. The DEGs were positively associated with disease severity and HOMA-IR, and were found to be efficient classifiers of mild-NAFL and NASH. Additional 1218 genes identified related to IR (IrCGs), which can classify NASH-with-fibrosis patients separately from mild-NAFL and NASH patients. IrCGs can promote intra-hepatic fat accumulation, dysregulation of the lipid metabolism, lipotoxicity, and activation of cell survival pathways including activation of cell proliferation and differentiation pathways.

CONCLUSIONS: Hepatic expression of genes associated with insulin resistance may drive NAFLD development and progression.