Expression of negative immune regulatory molecules, pro-inflammatory chemokine and cytokines in immunopathology of ECM developing mice

•P. berghei ANKA infection progresses via asymptomatic, symptomatic and ECM phases.•Rising brain PD1, CTLA4, LAG3 and CXCL4 expression precedes the symptomatic phase.•TNFα, CXCL10, MIP1β rise before the ECM, when PD-L1 and CTLA4 expression increase.•We characterize phase-specific immunopathology in P. berghei ANKA infection.

The pathological events in human cerebral malaria are mimicked in the experimental cerebral malaria (ECM) in Plasmodium berghei ANKA (PBA)-infected C57BL/6 mice. Although previously implied in ECM, the kinetics of cytokines and chemokines expression-an essential functional feature for defining causality in ECM development-remained untested. Herein, we characterized the immunopathological changes and the expression of negative immune regulatory molecules, cytokines and chemokines through asymptomatic (3 days after infection, 3 dpi), symptomatic (5 dpi) and ECM (7 dpi) stages in PBA-infected C57BL/6 mice. Parasitized RBCs were first detected in brain on 3 dpi, edema and tissue alterations on 5 dpi, and hemorrhages in different areas of brain on 7 dpi. Increased cerebellar PD-1, CTLA-4 and LAG-3 expression and reduced hippocampal CXCL-4 expression on 3 dpi were the first observed immunological changes. The negative immune regulatory molecules (PD-L1, CTLA-4), cytokines (TNF-α, sFAS-L), and chemokines (CXCL-10, MIP-1β) transcript levels varied in different brain areas in symptomatic and ECM phases. By 5 dpi, TNF-α, CXCL10 and MIP-1β significantly increased in all brain parts studied; IL-1RA in whole brain, whereas CXCL4 reduced in hippocampus and cerebrum. By 7 dpi, the hippocampal PD-1, CXCL4 and CTLA-4 expression decreased but the cerebral, cerebellar and hippocampal PD-L1 expression were elevated. TNF-α, CXCL10, MIP-1β, PD-1, CTLA-4 and PD-L1 expression were up-regulated in different brain areas. The TNFR2, IFN-gamma receptor, Lymphotoxin-β receptor and sFAS-L transcripts significantly increased in brain in ECM. Our data characterize key dynamic immunopathological changes in brain to imply relationship to ECM development.

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