CCR2 restricts IFN-γ production by hippocampal CD8 TRM cells that impair learning and memory during recovery from WNV encephalitis
Shenjian Ai, Artem Arutyunov, Joshua Liu, Jeremy Hill, Xiaoping Jiang, R Klein
Abstract
Central nervous system (CNS) resident memory CD8 T cells (TRM) that express IFN-γ contribute to neurodegenerative processes, including synapse loss, leading to memory impairment. Here, we show that CCR2 signaling in CD8 TRM that persist within the hippocampus after recovery from CNS infection with West Nile virus (WNV) significantly prevents the development of memory impairments. Using CCR2-deficient mice, we determined that CCR2 expression is not essential for CNS T cell recruitment or virologic control during acute WNV infection. However, transcriptomic analyses of forebrain CCR2+ versus CCR2− CD8 TRM during WNV recovery reveal that CCR2 signaling significantly regulates hippocampal CD8 TRM phenotype and function via extrinsic and intrinsic effects, limiting expression of CD103, granzyme A and IFN-γ, respectively, and increasing the percentages of virus-specific CD8 T cells. Consistent with this, WNV-recovered Cd8acreCcr2fl/fl mice exhibit decreased recognition memory. Overall, these data implicate CCR2 signaling in the regulation of CD8 TRM phenotype, including antiviral specificity and IFN-γ expression, highlighing a neuroprotective role for CCR2 in limiting CD8 T cell-mediated neuroinflammation and cognitive deficits, providing insights into potential therapeutic targets for CNS infections.