A-1

Rosacea, an inflammatory skin disorder, poses a dilemma owing to limited effectiveness of treatments for pathological vasodilation-mediated erythema. Here, we identify oxoglutaric acid (α-KG) as a rosacea-associated metabolite elevated in patients and correlated with erythema severity. Exogenous α-KG administration ameliorates rosacea-like manifestations in murine models. Mechanistically, α-KG activates OXGR1, a vascular smooth muscle cell (VSMC)-enriched G protein-coupled receptor (GPCR) to induce Gq signaling and enhance MYL9 phosphorylation, promoting VSMC contraction and limiting vasodilation. Cryo-electron microscopy (cryo-EM) structures of OXGR1-Gq complexes bound to α-KG or itaconate reveal a specific bipartite-acid pocket recognizing its endogenous agonist and an activation mechanism distinct from classical GPCRs. Building on these structures, we developed A-1, a synthetic selective OXGR1 agonist that mitigates erythema and inflammation with efficacy comparable to first-line therapy while offering enhanced safety in rosacea-like models. These findings link a metabolite to vascular dysfunction and nominate OXGR1 agonism for precision treatment of erythema and vascular disorders.