CD4+ CD25+ GARP+ regulatory T cells display a compromised suppressive function in patients with dilated cardiomyopathy

Summary Dilated cardiomyopathy (DCM) is a lethal inflammatory heart disease and closely connected with dysfunction of the immune system. Glycoprotein A repetitions predominant (GARP) expressed on activated CD4+ T cells with suppressive activity has been established. This study aimed to investigate the frequency and function of circulating CD4+ CD25+ GARP+ regulatory T (Treg) cells in DCM. Forty‐five DCM patients and 46 controls were enrolled in this study. There was a significant increase in peripheral T helper type 1 (Th1) and Th17 number and their related cytokines [interferon‐γ (IFN‐γ), interleukin (IL‐17)], and an obvious decrease in Treg number, transforming growth factor‐β1 (TGF‐β1) levels and the expression of forkhead box P3 (FOXP3) and GARP in patients with DCM compared with controls. In addition, the suppressive function of CD4+ CD25+ GARP+ Treg cells was impaired in DCM patients upon T‐cell receptor stimulation detected using CFSE dye. Lower level of TGF‐β1 and higher levels of IFN‐γ and IL‐17 detected using ELISA were found in supernatants of the cultured CD4+ CD25+ GARP+ Treg cells in DCM patients compared with controls. Together, our results indicate that CD4+ CD25+ GARP+ Treg cells are defective in DCM patients and GARP seems to be a better molecular definition of the regulatory phenotype. Therefore, it might be an attractive stategy to pay more attention to GARP in DCM patients.