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

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.