Adipose-tissue regulatory T cells are a consortium of subtypes that evolves with age and diet

Foxp3+CD4+ regulatory T (Treg) cells found within tissues regulate local immunity, inflammation and homeostasis. Tregs in epididymal visceral adipose tissue (eVAT) are critical regulators of local and systemic inflammation and metabolism. During aging and under obesogenic conditions, eVAT Tregs undergo transcriptional and phenotypic changes and are important for containing inflammation and normalizing metabolic indices. We have employed single-cell RNA sequencing, single-cell Tra and Trb sequencing, adoptive transfers, photoconvertible mice, cellular interaction analyses and in vitro cultures to dissect the evolving heterogeneity of eVAT Tregs with aging and obesity. Distinct Treg subtypes with distinguishable gene-expression profiles and functional roles were enriched at differing ages and with differing diets. Like those in lean mice, eVAT Tregs in obese mice were not primarily recruited from the circulation but instead underwent local expansion and had a distinct and diversified T cell receptor repertoire. The different eVAT-Treg subtypes specialized in different functions; for example, the subtypes enriched in lean, but not obese, mice suppressed adipogenesis. The existence of functionally divergent eVAT-Treg subtypes in response to obesogenic conditions presents possibilities for precision therapeutics in the context of obesity. Overall design: We investigated how the heterogeneity of the eVAT SVF and Treg compartments evolved with aging and obesity. 14-wk-old Foxp3-GFP mice were placed on a low-fat or high-fat diet for 16 weeks. For scRNA-seq, the total SVF and Tregs sorted from eVAT of the mice, hashed by individual groups, and encapsulated with the Chromium 3' v3 platform. For joint scRNA-seq and scTra/b-seq, Tregs sorted from eVAT and spleen of lean and obese mice were encapsulated using the Chromium Single Cell 5' v2 and V(D)J platform (10X Genomics). Data from two independent experiments.