CCR2 limits inflammatory functions of CD8 TRM cells that impair recognition memory during recovery from WNV encephalitis [scRNA-seq]

Central nervous system (CNS) resident memory CD8 T cells (TRM) that express IFN-? have been shown to contribute to neurodegenerative processes, including synapse loss, causing memory impairment. Here, we show that CCR2 deficiency in CD8 TRM that persists within the hippocampus after recovery from CNS infection with West Nile virus (WNV) significantly contributes to poor cognitive outcomes. 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 expression significantly regulates hippocampal CD8 TRM phenotype and function, with increased expression of CD103, granzyme A and IFN-?. Consistent with this, WNV-recovered Cd8acreCcr2fl/fl mice exhibit decreased recognition memory. Our findings highlight CCR2's role in regulating CD8 T cell-mediated neuroinflammation and cognitive deficits, providing insights into potential therapeutic targets for CNS infections. To study the effect of CCR2, we infected CD8a-Cre- and CD8a-Cre+ CCR2 floxed mice with WNV-NS5-E218A intracranially. We isolated corteces and hippocampi at 30 days post infection. Brain tissues were processed into single cells suspension and RNA was extracted for sequencing.

表达干扰素-γ（IFN-γ）的中枢神经系统（CNS）组织驻留记忆CD8 T细胞（TRM）已被证实可参与包括突触丢失在内的神经退行性过程，进而导致记忆损伤。本研究发现，在西尼罗河病毒（WNV）感染中枢神经系统并康复后，持续存留于海马体的CD8 TRM中CCR2缺陷会显著加剧认知功能不良结局。我们利用CCR2缺陷小鼠开展实验，证实CCR2表达在急性WNV感染期间并非中枢神经系统T细胞募集或病毒学控制所必需。然而，对WNV康复期前脑CCR2阳性与CCR2阴性CD8 TRM的转录组分析显示，CCR2表达可显著调控海马体CD8 TRM的表型与功能，具体表现为CD103、颗粒酶A及IFN-γ的表达上调。与此一致的是，WNV康复后的Cd8acreCcr2fl/fl小鼠表现出识别记忆受损。本研究揭示了CCR2在调控CD8 T细胞介导的神经炎症与认知缺陷中的作用，为中枢神经系统感染的潜在治疗靶点提供了新见解。为研究CCR2的功能效应，我们通过颅内接种WNV-NS5-E218A，分别感染CD8a-Cre阴性与CD8a-Cre阳性CCR2 flox小鼠。于感染后30天分离大脑皮层与海马体组织，将脑组织制备为单细胞悬液并提取RNA用于测序。