MiR-23a-3p-regulated abnormal acetylation of FOXP3 induces regulatory T cell function defect in Graves disease.

This study aims to investigate the mechanism of miR-23a-3p in regulating Treg dysfunction in Graves disease (GD). The percentage of Treg cells and IL-17+ T cells were determined by flow cytometry. The expression of FOXP3, SIRT1, RORγt and miR-23a-3p was analyzed by qRT-PCR or Western blot. CD4+ T cells were treated with SIRT1 specific inhibitor EX-527 or left untreated. MiR-23a-3p mimic or inhibitor were transfected into CD4+ T cells. Acetylation expression of FOXP3 was analyzed by immunoprecipitation. The suppressive function of Treg was analyzed by CFSE assay. The results showed that GD patients have significant less Treg cells and more IL-17+ T cells. FOXP3 and miR-23a-3p were significantly down-regulated meanwhile SIRT1 and RORγt were up-regulated in GD patients. FOXP3 acetylation level of GD group was lower than of control groups. After EX-527 treatment, the percentage of Treg cells, expression and acetylation level of FOXP3 were significantly increased in GD group. GD Tregs exhibited weaker suppressive activity, miR- 23a-3p mimic suppressed SIRT1 expression and suppressive-activity of Tregs whereas promoted expression and acetylation level of FOXP3 in GD group. Our findings suggest that Treg function defect in GD patients is mediated by the abnormal acetylation of FOXP3, which is regulated by miR-23a-3p via targeting SIRT1.