Macrophage markers and gene signature profiling reveals mesenchymal stem cells mediated immune modulation in Plasmodium berghei ANKA infection.

BACKGROUND Cerebral malaria (CM) is a life-threatening neurological complication of Plasmodium falciparum infection characterized by excessive inflammation, blood-brain barrier (BBB) disruption, and immune dysregulation. Macrophage-mediated inflammatory responses play a central role in CM pathogenesis, where imbalanced activation contributes to disease progression and tissue damage. However, integrated analyses combining macrophage surface phenotyping with transcriptional profiling remain limited, restricting comprehensive understanding of immune modulation during CM.

OBJECTIVE To investigate the prophylactic immunomodulatory effects of MSCs administration in experimental CM and evaluate its impact on splenic macrophage responses.

METHODS C57BL/6 mice infected with Pb.ANKA received intravenous MSC administration on the day of infection and were monitored for parasitemia and survival. BBB integrity was assessed using Evans blue extravasation, and brain pathology was evaluated histologically. MSC biodistribution was analyzed using near-infrared labeling. Macrophage polarization in F4/80+CD11b+ splenic cells was assessed by flow cytometry using M1 markers (CD86, CD38) and M2 markers (CD163, CD206, EGR-2). Gene expression of macrophage-associated markers (iNOS-2, Arginase-1, FPR-1, GPR-18, PTGES-2, EGR-2) was analyzed by quantitative real-time PCR.

RESULTS MSC administration reduced parasitemia, improved survival, preserved BBB integrity, and attenuated brain pathology. MSCs showed systemic distribution, suggesting peripheral immune modulation. Flow cytometry revealed reduced M1 markers with maintained or enhanced M2 markers. Gene expression showed downregulation of iNOS-2 and upregulation of Arginase-1, EGR-2, GPR-18, FPR-1, and PTGES-2, indicating macrophage reprogramming toward a balanced M1/M2 continuum.

CONCLUSION MSC administration mitigates disease severity in experimental CM by modulating macrophage polarization, promoting a balanced M1/M2 response, attenuating inflammatory pathways, and preserving BBB integrity.