Conserved transcriptional connectivity of regulatory T cells in the tumor microenvironment informs novel combination cancer therapy strategies [visium]

While regulatory T (Treg) cells are traditionally viewed as professional suppressors of antigen presenting and effector T cells in both autoimmunity and cancer, recent findings of distinct Treg functions in tissue maintenance suggest that their regulatory purview extends to a wider range of cells and is broader than previously assumed. To elucidate tumoral Treg “connectivity” to diverse tumor-supporting accessory cell types, we explored immediate early changes in their single cell transcriptomes upon punctual Treg depletion in experimental lung cancer and injury-induced inflammation. Prior to any notable T cell activation and inflammation, fibroblasts, endothelial and myeloid cells exhibited pronounced changes in their gene expression in both cancer and injury settings. Factor analysis revealed shared Treg-dependent gene programs, foremost, prominent upregulation of VEGF signaling-related genes upon Treg deprivation in either setting, as well as in Treg-poor vs Treg-rich human lung adenocarcinomas. Accordingly, punctual Treg depletion combined with short-term VEGF blockade showed markedly improved control of PD-1 blockade-resistant lung adenocarcinoma progression in mice compared to the corresponding monotherapies, highlighting a promising factor-based querying approach to elucidating novel rational combination treatments of solid organ cancers. Lungs were collected from KrasLSL-G12D/WTTrp53fl/fl Foxp3GFP-DTR (KP-DTR) mice harboring ~3 months old Adenicarcinomas, following 48 hr treatment with Diphteria toxin (DT) to deplete Tregs, or PBS as control. Lungs were perofused and snap-frozen in OCT. All samples were sections with a Cryostat to a thickness of 10um.