Astrocytic RIPK3 exerts protective anti-inflammatory activity in mice with viral encephalitis by transcriptional induction of serpins.

Flaviviruses pose a substantial threat to public health because of their ability to infect the central nervous system (CNS). Receptor-interacting protein kinase 3 (RIPK3) is a central coordinator that promotes neuroinflammation during viral infection of the CNS, a role that occurs independently of its canonical function in inducing necroptosis. Here, we used mouse genetic tools to induce astrocyte-specific deletion, overexpression, and chemogenetic activation of RIPK3 to demonstrate an anti-inflammatory function for astrocytic RIPK3. RIPK3 activation in astrocytes promoted host survival during flavivirus encephalitis by limiting immune cell recruitment to the CNS. Despite inducing a proinflammatory transcriptional program, astrocytic RIPK3 restrained neuroinflammation by increasing the abundance of the protease inhibitor SerpinA3N, which preserved blood-brain barrier integrity, reduced leukocyte infiltration, and improved survival outcomes during flavivirus encephalitis. These findings highlight a previously unappreciated role for astrocytic RIPK3 in suppressing pathologic neuroinflammation.