Analysis of gene expression and immune infiltration in white adipose tissue of patients with obesity: bioinformatics analysis and meta-analysis

Abstract

Background The physiological and pathological process of obesity involves inflammation and immunity. The alterations in the number and function of immune cells may have an effect on systemic inflammation and homeostasis. This study aimed to explore the different biological processes and immune infiltration landscape in obesity. Methods Nine obesity-related datasets were obtained from the Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs)in adipose tissues were identified by “limma” R package or GEO2R and then Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed. Meanwhile, we conducted the immune infiltration analysis with gene expression data and Meta-analysis was performed based on the results of immune infiltration. Finally, we selected hub genes and tried to find out the connection between hub genes and immune infiltration. Results 46 common DEGs were identified, among which the up-regulated genes were involved in biological processes such as the regulation of hemopoiesis, leukocyte differentiation, activation and migration, cell adhesion, cytokine secretion, and interactions. Immune infiltration analysis showed that the percentages of monocytes and macrophages were increased in obesity, while there was no significant difference in neutrophils. The obese patients had a higher proportion of CD4 T cells, induced regulatory T (iTreg) cells, T follicular helper (Tfh) cells, T helper 2 (Th2) cells, T regulatory type 1 (Tr1) cells, and natural killer (NK) cells, and lower levels of CD8 T cells, B cells, CD8 naive cells, exhausted T (Tex) cells, and γδ T cells compared with the controls. PTPRC、ITGAX、CD86、MMP9、ITGB2、CCR1、TLR8、CCL19、SPP1、TREM2 were identified as hub genes. Conclusion In obesity, genes related to immunity and inflammation are upregulated in adipose tissue, and the function and abundance of immune cells are changed. There are more monocytes and macrophages in obese people than those in non-obese individuals, and there are also differences in lymphocytes and their subsets.