DCAF1 regulates Treg senescence via the ROS axis during immunological ageing.

As a hallmark of immunological ageing, the low-grade, chronic inflammation with accumulation of effector-memory T cells contributes to the increased susceptibility of many ageing-related diseases. While the proinflammatory state of aged T cells indicates a dysregulation of immune homeostasis, whether and how ageing drives regulatory T (Treg) cell ageing and alters their function is not fully understood due to a lack of specific ageing markers. Here, by a combination of cellular, molecular and bioinformatic approaches, we discover that Treg cells senesce more severely than conventional T (Tconv) cells during ageing. We found Treg cells from aged mice were less efficient than young Treg cells to suppress Tconv cell function in an inflammatory-bowel-disease model and to prevent Tconv cell ageing in the irradiation-induced ageing model. Furthermore, we revealed that DCAF1 (DDB1 and CUL4 associated factor 1) was downregulated in aged Treg cells and was critical to restrain Treg cell ageing via glutathione S-transferase P (GSTP1) regulated reactive-oxygen-species (ROS). Importantly, interfering with GSTP1 and ROS pathways reinvigorated the proliferation and function of aged Treg cells. Therefore, our studies uncover an important role of DCAF1-GSTP1-ROS axis in Treg cell senescence, which leads to uncontrolled inflammation and immunological ageing.