Changes in Treg cells and cytokines in the peripheral blood of patients with coronary artery disease combined with type 2 diabetes mellitus

Background: Patients with coronary artery disease (CAD) combined with type 2 diabetes mellitus (T2DM) develop serious atherosclerotic and diffuse lesions. Inadequate numbers and the dysfunction of CD4(+)CD25(+)Foxp3(+)regulatory T lymphocytes (Treg cells) are common mechanisms underlying the immunopathological damage in CAD and T2DM. Objectives: We aimed to explore Treg cell changes in patients with CAD complicated with T2DM and to investigate the association between Treg cells and the severity of CAD. Methods: A total of 257 participants were included in the study, divided into a healthy control group (HC, n = 63), CAD group (n = 106), and CAD complicated with T2DM group (CAD+T2DM, n = 88). Flow cytometry detected Treg cell levels, and serum IL-10, IL-6, and ELISA detected TGF-beta. Results: The sample for this study consisted of 170 males and 87 females, with 88 (34.24 %) participants having diabetes and 169 (65.76 %) without diabetes. The proportion of circulating Treg cells was lower in the CAD and CAD+T2DM groups than in the HC group, and it was lower in the CAD+T2DM group than in the CAD group. The plasma levels of IL-10 and TGF-beta were lower in the CAD than in the HC group, and the levels in the CAD+T2DM group were significantly lower than those in the CAD group. However, the plasma IL-6 level changed in the opposite direction. Gensini's score was negatively correlated with Treg cells (R = - 0.57, P < .05). Subgroup analyses and interaction analyses showed that the association of Treg with the Gensini score was robust. Conclusion: The level of Treg cells was an independent protective factor for patients with CAD and T2DM and was negatively correlated with the Gensini score. Therefore, Treg cells may be used as therapeutic targets for CAD with T2DM patients.