CCR2 limits inflammatory functions of CD8 TRM cells that impair recognition memory during recovery from WNV encephalitis

Abstract

Central nervous system (CNS) resident memory CD8 T cells (TRM) that express IFN-{gamma} contribute to neurodegenerative processes, including synapse loss, leading to memory impairments. Here, we show that CCR2 signalling 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 signalling significantly regulates hippocampal CD8 TRM phenotype and function via extrinsic and intrinsic effects, decreasing the expression of CD103 and granzyme A and IFN-{gamma}, respectively. Consistent with this, WNV-recovered Cd8acreCcr2fl/fl mice exhibit decreased recognition memory. Our findings highlight a neuroprotective role for CCR2 in limiting CD8 T cell-mediated neuroinflammation and cognitive deficits, providing insights into potential therapeutic targets for CNS infections.