IL-33 Signaling Alters Regulatory T Cell Diversity in Support of Tumor Development

Regulatory T cells (Tregs) can impair anti-tumor immune responses and are associated with poor prognosis in multiple cancer types. Tregs in human tumors span diverse transcriptional states distinct from those of peripheral Tregs, but their contribution to tumor development remains unknown. Here, we use single-cell RNA sequencing (RNA-seq) to longitudinally profile dynamic shifts in the distribution of Tregs in a genetically engineered mouse model of lung adenocarcinoma. In this model, interferon-responsive Tregs are more prevalent early in tumor development, whereas a specialized effector phenotype characterized by enhanced expression of the interleukin-33 receptor ST2 is predominant in advanced disease. Treg-specific deletion of ST2 alters the evolution of effector Treg diversity, increases infiltration of CD8+ T cells into tumors, and decreases tumor burden. Our study shows that ST2 plays a critical role in Treg-mediated immunosuppression in cancer, highlighting potential paths for therapeutic intervention. [Display omitted] •Single-cell profiling of CD4 T cells along tumor development in a mouse model•Treg diversity shifts to a Klrg1+Areg+ (KA) effector phenotype in advanced tumors•Il1rl1 (encoding ST2)+ Tregs have higher expression of KA effector Treg genes•Treg-specific ST2 loss enhances CD8+ T cell infiltration and decreases tumor burden Li et al. show in a genetic mouse model of lung adenocarcinoma that during tumor development regulatory T cell (Treg) diversity shifts from an interferon-responsive to a ST2-positive, Klrg1+Areg+ effector-like phenotype. Treg-specific deletion of ST2 alters Treg heterogeneity, increases tumor infiltration by CD8+ T cells, and decreases tumor burden.