The differential expression of adipose tissue genes in short, medium and long-term periods after bariatric surgery

Bariatric surgery is an approved treatment for obesity that consistently improves metabolic syndrome, with well-documented beneficial effects on dyslipidemia, cardiovascular risk, nonalcoholic fatty liver disease and glucose homeostasis. In this study, we determined the differential expression genes in three periods after bariatric surgery: short-term (4-months), medium-term (1- and 2-years), and long-term (5-years) periods. Two microarray profiles were downloaded from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were identified by comparing the expression of adipose tissue genes before surgery compared to short, medium and long-term periods following surgery. Shared DEGs for the medium-term were evaluated by comparing the DEGs for both 1 and 2 years. 165, 65, and 59 DEGs were identified in short-medium-long periods. The protein-protein interactions were analyzed by STRING. A co-expression network was constructed by mapping the DEGs onto the GeneMANIA plugin of Cytoscape. Gene Ontology (GO) enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) and wikipathway analysis were done for each group of DEGs. Interleukin-8 receptor activity, complement receptor activity and opsonin receptor activity/N-formyl peptide receptor activity in GO Function enrichment and cellular response to interleukin-8, positive regulation of hippocampal neuron apoptotic process, and positive regulation of hippocampal neuron apoptotic process in GO Process showed the best scores in short-, medium-, and long-term periods, respectively. Eight genes, including CCL2 (Chemokine ligand 2), CXCR4 (CXC motif chemokine receptor 4), EGR2 (Early Growth Response 2), FPR1 (Formyl Peptide Receptor 1), IL6 (interleukin-6), RGS2 (regulator of gene protein signaling2), SELPLG (Selectin P Ligand), and THBS1 (Thrombospondin 1) were identified as shared DEGs in the three periods after surgery. Importantly, results of DAVID database analysis showed 7, 6, 4, and 4 of these genes have roles in immune/ cancer/cardiovascular diseases, type 2 diabetes, myocardial infarct, and atherosclerosis, respectively.