Ripk1 is critical for preserving effector regulatory T cells and the suppressive transcriptional program in regulatory T cells (RNA-Seq)

Ripk1 plays an important role as a regulator of programmed cell death processes such as apoptosis and necroptosis, and is involved in the initiation of pro-inflammatory NF-kB signaling. Immune tolerance depends on the proper function and homeostasis of regulatory T cells. Here, we show that Treg-specific ablation of Ripk1 in mice leads to a reduction of Treg cells and spontaneous systemic autoimmunity. Using chimeric mice that allowed us to study Treg cells in the absence of inflammatory conditions, we observed a disadvantage of Ripk1-deficient compared to Ripk1-proficient Treg cells. Importantly, we did not observe impaired viability of the Ripk1-deficient Treg cells. Furthermore, single-cell RNA sequencing revealed that Ripk1 is required for the maintenance of the Treg cell transcriptional signature, which is essential for the suppressive function of Treg cells. Together, these findings highlight the fundamental role of Ripk1 in maintaining immune homeostasis by preserving the suppressive phenotype of Treg cells Overall design: Comparative gene expression profilling analysis of Ripk1-proficient and Ripk1-deficient Treg cells. CD4+ CD25+ Treg cells were FACS sorted from pooled spleen+lymph nodes of chimeric mice carrying Ripk1-proficient and Ripk1-deficient Treg cells, which were generated using the loxp-Cre system. Ripk1 floxed mice were crossed to Foxp3Cre-YFP mice to obtain Ripk1fl/fl Foxp3Cre-YFP/wt chimeric female mice. Ripk1 -deficient Treg cells were sorted based on YFP expression.