CXCL10highTNFαhighKi67+ Microglia Recruit and Activate CD8+ T Cells in the Brainstem During Experimental Cerebral Malaria.

AIMS: This study aimed to investigate the heterogeneity of microglia and their role in recruiting and activating CD8+ T cells in experimental cerebral malaria (ECM).

METHODS

C57BL/6J mice were infected with Plasmodium berghei ANKA (PbA) to induce ECM. Morphology and distribution of microglia were assessed via immunofluorescence (IF) staining and electron microscopy. Single-cell RNA-sequencing (scRNA-seq) analyzed the activation characteristics of infiltrating CD8+ T cells and the transcriptional heterogeneity of microglia in ECM. In vitro, ECM-associated microglia were induced by TNFα, IFNγ, and parasite-infected red blood cells (pRBCs). The interaction between microglia and CD8+ T cells was explored in co-culture systems through transwell assay, adhesion assay, and cytotoxicity test.

RESULTS

In vivo, microglia were aggregated in the brainstem and olfactory bulb in the ECM brain, regions that exhibited more severe pathological injury. The transcriptional characteristics of ECM microglia distinguished from physiological microglia and exhibit morphological heterogeneity in the ECM brain. Infiltrating CD8+ T cells in the ECM brainstem exhibit sustained activation characteristics associated with microglia interaction. Based on subcluster analysis, a unique subtype of ECM-associated microglia was identified, characterized by CXCL10highTNFαhighKi67+. These microglia mediated the recruitment and sustained activation of CD8+ T cells through persistent interactions in co-culture systems.

CONCLUSIONS

Our study identified an ECM-associated microglia subtype and explored its interaction with CD8+ T cells, which deepened the understanding of the multifaceted role of microglia in the pathogenesis of CM neuroinflammation.