ST2+ T-Regulatory Cells in Renal Inflammation and Fibrosis after Ischemic Kidney Injury
Vikram Sabapathy, AJ Price, Nardos Tesfaye Cheru, Rajkumar Venkatadri, Murat Doğan, Gabrielle Costlow, Saleh Mohammad, Rahul Sharma
Abstract
Key Points IL-33/ST2 alarmin pathway regulates inflammation, fibrosis, and resolution of ischemia-reperfusion injury of kidneys. ST2 regulates the transcriptome of T-regulatory cells related to suppressive and reparative functions. The secretome of ST2 + T-regulatory cells regulates hypoxic injury in an amphiregulin-dependent manner. Background Inflammation is a major cause of kidney injury. IL-1 family cytokine IL-33 is released from damaged cells and modulates the immune response through its receptor ST2 expressed on many cell types, including regulatory T cells (Tregs). Although a proinflammatory role of IL-33 has been proposed, exogenous IL-33 expanded Tregs and suppressed renal inflammation. However, the contribution of endogenous IL-33/ST2 for the role of Tregs in the resolution of kidney injury has not been investigated. Methods We used murine renal ischemia-reperfusion injury and kidney organoids (KDOs) to delineate the role of the ST2 and amphiregulin (AREG) specifically in Tregs using targeted deletion. Bulk and single-cell RNA sequencing were performed on flow-sorted Tregs from spleen and CD4 T cells from postischemic kidneys, respectively. The protective role of ST2-sufficient Tregs was analyzed using a novel coculture system of syngeneic KDOs and Tregs under hypoxic conditions. Results Bulk RNA sequencing of splenic and single-cell RNA sequencing of kidney CD4 T cells showed that ST2 + Tregs are enriched for genes related to Treg proliferation and function. Genes for reparative factors, such as Areg , were also enriched in ST2 + Tregs. Treg-specific deletion of ST2 or AREG exacerbated kidney injury and fibrosis in the unilateral ischemia-reperfusion injury model. In coculture studies, wild-type but not ST2-deficient Tregs preserved hypoxia-induced loss of kidney organoid viability, which was restored by AREG supplementation. Conclusions Our study identified the role of the IL-33/ST2 pathway in Tregs for resolution of kidney injury. The transcriptome of ST2 + Tregs was enriched for reparative factors including Areg . Lack of ST2 or AREG in Tregs worsened kidney injury. Tregs protected KDOs from hypoxia in a ST2- and AREG-dependent manner.