Toxoplasma gondii infection and chronic IL-1 elevation drive hippocampal DNA double-strand break signaling, leading to cognitive deficits.

Chronic inflammation, resulting from infections, is characterized by increased levels of cytokines including interleukin-1 (IL-1), but little is known about how IL-1 contributes to cognitive impairment, potentially via epigenetic processes. Here we demonstrate that mice chronically infected with the parasite Toxoplasma gondii exhibit impaired spatial memory, which is dependent on neuronal IL-1 signaling and mimicked by chronic exposure to IL-1β. Both T. gondii infection and chronic IL-1β drive H2A.X-dependent DNA double-strand break signaling in hippocampal neurons and invalidating neuronal H2A.X-dependent signaling blocks memory impairments caused by either exposure. Our results highlight the instrumental role of cytokine-induced double-strand-break-dependent signaling in spatial memory defects, which may be relevant to multiple brain diseases.