Attenuating AAV-triggered innate immunity in the adult mouse nervous system via cGAS-STING pathway inhibition

While adeno-associated virus (AAV)-mediated gene delivery has emerged as a promising therapeutic modality for neurological disorders, dose-dependent immune responses remain a critical barrier to clinical translation. Here we reveal the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway as a key mediator of innate immune activation following intracranial AAV administration. Through comparative analyses in genetic and pharmacological intervention models, we demonstrate that STING signaling mediates key neuroinflammatory sequelae including glia reactivation, cytotoxic T cell infiltration, and neuronal injury. Mechanistically, microglia serve as the predominant sentinels detecting AAV immunogenicity via cGAS-STING activation. Therapeutic inhibition of this pathway by either microglia depletion or antagonism of STING by small molecules significantly mitigates high-dose AAV9-induced neurotoxicity while enhancing transgene delivery efficacy. Our work delineates a unified mechanistic framework linking AAV-triggered DNA sensing to neuroinflammatory pathology, and provides two clinically actionable approaches to decouple therapeutic gene delivery from detrimental immune activation in nervous system targeted gene therapy.