Prasugrel inhibits TLR7-driven autoimmunity in systemic lupus erythematosus by acetylating cGAS.

Systemic lupus erythematosus (SLE) has a complex, multifactorial etiology, which contributes to a lack of definitive cure and limited treatment efficacy. Here, we report that cyclic GMP-AMP synthase (cGAS) is significantly activated in SLE patients. We further demonstrate that cGAS deletion protects mice from lupus-like symptoms induced by the TLR7 agonist imiquimod (IMQ). In a screen of 3,159 FDA-approved drugs, we identify the antiplatelet agent prasugrel as a potent cGAS inhibitor. Mechanistically, prasugrel disrupts the DNA-triggered liquid phase condensation and activation of cGAS via direct acetylation. Strikingly, we find that prasugrel exhibits remarkable efficacy in treating SLE in both mouse models and patient cells. Importantly, we report elevated plasma cyclic GMP-AMP (cGAMP) in SLE patients and identify it as a potential biomarker for predicting prasugrel response. Thus, our work elucidates the essential role of cGAS in SLE pathogenesis and presents prasugrel as a promising therapeutic option with immediate translational potential.