[Analysis of hub genes and molecular mechanisms in non-alcoholic steatohepatitis based on the gene expression omnibus...

Objective: To explore the hub genes and mechanisms in the pathological process of non-alcoholic steatohepatitis (NASH) by bioinformatics methods. Methods: Microarray datasets GSE89632 were downloaded from the Gene Expression Omnibus (GEO) database, which including 20 simple non-alcoholic fatty liver disease patients, 19 NASH patients and 24 healthy control individuals. The differentially expressed genes (DEGs) in patients with simple non-alcoholic fatty liver disease and NASH were compared with healthy control individuals respectively, and the intersection of the two groups of DEGs was taken. GO functional annotation and KEGG pathway enrichment analysis of DEGs were performed with DAVID 6.8 and KOBAS 3.0 separately. Protein-protein interaction network (PPI) was constructed by STRING database, then the mRNA hub genes were selected by Cytoscape software. The Attie Lab Diabetes database was used to verify the relative expression of hub genes mRNA in the liver of 4 groups of C57BL/6 mice (4-week-old normal group, 4-week-old obese group, 10-week-old normal group and 10-week-old obese group, 5 mice in each group). Spearman's correlation analysis was performed to analyze the correlation between hub gens and prognostic clinical parameters. Results: From the GSE89632 dataset, 365 common DEGs (115 up-regulated genes and 250 down-regulated genes) were identified in patients with simple non-alcoholic fatty liver disease and NASH patients compared with control individuals. GO analysis showed that DEGs were mainly enriched in biological processes such as inflammatory response and immune response. KEGG pathway analysis showed that up-regulated genes were mainly enriched in cholesterol metabolism, bile secretion and fat digestion and absorption signal pathways. Down-regulated genes were mainly enriched in interleukin-17 signaling pathway, tumor necrosis factor signaling pathway, advanced glycation end products and their receptors of diabetic complications. Seven key hub genes were identified by PPI analysis, which were FOS, EGR1, FOSB, JUNB, FOSL1, MYC and NR4A1.The mRNA relative expression levels of EGR1 and JUNB in the liver of 10-week-old obese mice were lower than those of normal mice (P<0.05).The relative expression levels of NR4A1 in the liver of obese mice at 4-and 10-week-old were lower than those of normal mice at the same age (P values<0.05). Spearman's correlation analysis showed that the expression of EGR1 was negatively correlated with the degree of hepatic steatosis (r=-0.785, P<0.001).The expression levels of FOSB, MYC and NR4A1 were negatively correlated with the level of alanine aminotransferase (r=-0.649, -0.597 and-0.580 respectively, all P values<0.001). Conclusion: EGR1, FOSB, MYC, JUNB and NR4A1 might be the hub genes in the pathological process of NASH and the inflammatory and immune response in hepatocytes, IL-17 signaling pathway and TNF signaling pathway might be the key molecular mechanisms in the occurrence and development of NASH.