IL-35 promotes CD4+Foxp3+ Tregs and inhibits atherosclerosis via maintaining CCR5-amplified Treg-suppressive mechanisms
Ying Shao, William Y. Yang, Fatma Saaoud, Charles Drummer, Yu Sun, Keman Xu, Yifan Lu, Huimin Shan, Ethan M. Shevach, Xiaohua Jiang, Hong Wang, Xiaofeng Yang
Abstract
Tregs play vital roles in suppressing atherogenesis. Pathological conditions reshape Tregs and increase Treg-weakening plasticity. It remains unclear how Tregs preserve their function and how Tregs switch into alternative phenotypes in the environment of atherosclerosis. In this study, we observed a great induction of CD4+Foxp3+ Tregs in the spleen and aorta of ApoE-/- mice, accompanied by a significant increase of plasma IL-35 levels. To determine if IL-35 devotes its role in the rise of Tregs, we generated IL-35 subunit P35-deficient (IL-35P35-deficient) mice on an ApoE-/- background and found Treg reduction in the spleen and aorta compared with ApoE-/- controls. In addition, our RNA sequencing data show the elevation of a set of chemokine receptor transcripts in the ApoE-/- Tregs, and we have validated higher CCR5 expression in ApoE-/- Tregs in the presence of IL-35 than in the absence of IL-35. Furthermore, we observed that CCR5+ Tregs in ApoE-/- have lower Treg-weakening AKT-mTOR signaling, higher expression of inhibitory checkpoint receptors TIGIT and PD-1, and higher expression of IL-10 compared with WT CCR5+ Tregs. In conclusion, IL-35 counteracts hyperlipidemia in maintaining Treg-suppressive function by increasing 3 CCR5-amplified mechanisms, including Treg migration, inhibition of Treg weakening AKT-mTOR signaling, and promotion of TIGIT and PD-1 signaling.