Increased levels of adipose tissue-resident Th17 cells in obesity associated with miR-326.

miRNAs are important immune regulators in the control of the CD4 + T cells phenotype. miR-326 regulates the differentiation towards Th17 cells and the inhibition of miR-155 is associated with low levels of Treg cells. However, miRNAs expression and transcription factors associated with these lymphocyte subsets in obesity-induced adipose tissue inflammation is still unknown. The aim of this work was to identify Th17 cells in subcutaneous adipose tissue (SAT), proinflammatory cytokine production and their association with the miRNAs and transcription factors involved. We collected SAT samples obtained by lipoaspiration from individuals with normal weight, overweight and obesity. We obtained the stromal vascular fractions and then a Ficoll gradient was performed to obtain adipose tissue mononuclear cells (ATMC). Th17 cells were evaluated by flow cytometry and the expression of miR-326, miR-155, RORC2 and FOXP3 by qRT-PCR. We also analyzed cytokines from the supernatants of the ATMC culture and measured the FOXP3 methylation percentage by bisulfite conversion by PCR. According to the results, the frequency of Th17 cells and RORC2 expression was higher in individuals with obesity and associated with miR-326 expression. The ATMC from this group secreted a proinflammatory cytokine profile by in vitro assay. In contrast, lower levels of mRNA FOXP3 expression was detected in ATMC from individuals with obesity that correlated with methylation percentage of FOXP3 gene but no association with miR-155 was detected. Our results suggested that miR-326 participates in the polarization towards Th17 promoting the inflammatory state in the obesity-induced adipose tissue.