cGAS-mediated type I IFN signaling contributes to disease progression in drug-refractory epilepsy.

Epilepsy is a prevalent neurological disease, with one-third of individuals becoming nonresponsive to antiepileptic drugs and developing drug-refractory epilepsy (DRE). Here we identify activation of cyclic GMP-AMP synthase (cGAS), a double-stranded DNA sensor that induces type I interferon (IFN) signaling, in human DRE brain tissue. Microglia from individuals with DRE exhibit a robust type I IFN signature and the activation of upstream cGAS-STING signaling. Further, in mouse models of Dravet syndrome, a genetic form of DRE, we similarly detect activation of the cGAS pathway. We show that microglial cGAS can be activated by DNA released from hyperexcitable neurons. Genetic reduction and pharmacological inhibition of cGAS attenuates seizure phenotypes, reduces glial inflammatory signatures and normalizes neuronal transcriptomic changes in mice with Dravet syndrome. Together, these findings identify cGAS-mediated neuroimmune signaling as a contributor to seizure pathology in Dravet syndrome and highlight this pathway as a potential therapeutic target.