Succinate drives gut inflammation by promoting FOXP3 degradation through a molecular switch

Succinate levels are increased in inflammatory bowel disease (IBD), but its role in disease pathogenicity remains unknown. Here we showed that succinate promoted colitis in mice by reducing the expression of FOXP3 and increasing the expression of interleukin-17 in regulatory T (T_reg) cells. Succinate selectively reduced the expression of 2-oxoglutarate dehydrogenase complex (OGDHc), the enzyme for succinyl-CoA synthesis, which in turn reduced FOXP3 succinylation and made FOXP3 lysine residues available for ubiquitination and FOXP3 protein degradation. Genetic deletion of Dlst, a member of OGDHc, in T_reg cells led to reduced expression of FOXP3, impaired T_reg cells function and severe gut inflammation. Restoring FOXP3 expression fully rescued the immune suppressive functions of Dlst-deficient T_reg cells. In individuals with IBD, FOXP3 and OGDHc levels were reduced in T_reg cells and negatively correlated with succinate levels and inflammation severity. This study identifies succinate as a pathogenic factor in IBD, uncovering a succinate-driven molecular switch that regulates FOXP3 stability and T_reg cells function during inflammation.