Obesity disrupts cellular cholesterol homeostasis to inhibit the homeostatic clonal expansion of ST2hi VAT Treg cells

Regulatory T (Treg) cells are highly enriched in the visceral adipose tissue (VAT) to maintain metabolic homeostasis, but they are lost during obesity. Currently, how VAT Treg cells rewire cellular metabolism to support their homeostatic clonal expansion, and whether this process is disrupted in obesity, is unclear. Here, we found that cholesterol metabolism was uniquely upregulated in VAT-, but not other non-lymphoid-tissue Treg cells. Disrupting cholesterol homeostasis (CH) by Treg-specific deletion of Srebf2 led to a specific loss of VAT Treg cells and enhanced obesity-induced systemic metabolic dysfunction. Mechanistically, Srebf2-mediated CH potentiated strong TCR signaling, which specifically promoted the clonal expansion of ST2hi, but not other, VAT Treg subsets. However, long-term high-fat-diet feeding disrupted VAT Treg CH and impaired ST2hi VAT Treg clonal expansion. Restoring Treg CH rescued VAT Treg accumulation in obese mice, suggesting CH modulation could be a potential option for Treg-targeted therapies in obesity-associated metabolic diseases. VAT Treg cells were isolated from 25-week-old male Foxp3YFP-cre Srebf2WT/WT (n=4) and Srebf2flox/flox (n=4) mice at steady state and from 23-27-week-old male Foxp3thy1.1 PpargTdt mice fed a normal chow diet (NCD) (n=5) and high fat diet (HFD) (n=5) for 22 weeks.