Interactions between Plasmodium falciparum-infected red blood cells and their extracellular vesicles with megakaryocytes: implications for platelet-like particle formation.

BACKGROUND: Thrombocytopenia commonly accompanies Plasmodium falciparum (P. falciparum) malaria, yet the role of impaired megakaryopoiesis and platelet production remains unclear. This study examined how P. falciparum-infected red blood cells (pRBCs) and their extracellular vesicles (EVs) modulate megakaryocytic differentiation and platelet-like particle (PLP) formation. METHODS: MEG-01 cell line, a human megakaryoblastic leukaemia model, was differentiated with phorbol 12-myristate 13-acetate (PMA) in the presence or absence of fetal bovine serum (FBS) and co-cultured with pRBCs, normal RBCs (nRBCs), or their EVs (nRBC-EVs/pRBC-EVs). Changes in cell phenotype, adhesion, and gene expression were analyzed by flow cytometry, confocal microscopy, and qPCR. PLP functionality was assessed by clotting assays, and cytokine secretion was quantified using cytometric bead array. RESULTS: pRBCs transiently adhered to MEG-01 cells but suppressed megakaryocytic marker expression, downregulated NOTCH3, and altered apoptosis- and stress-related genes. PLP production increased under some conditions, but clotting activity was impaired, indicating reduced functionality. In contrast, RBC-EVs, particularly pRBC-EVs, were internalized but induced minimal transcriptional or functional changes. Cytokine profiling revealed that pRBCs and their EVs selectively increased IL-8, RANTES, and MCP-1 levels. CONCLUSIONS: Intact pRBCs strongly inhibit megakaryocytic differentiation and disrupt PLP function through transcriptional dysregulation and inflammatory activation, whereas under our experimental conditions, RBC-EVs exert milder modulatory effects. These findings highlight defective platelet production as a novel mechanism contributing to malaria-associated thrombocytopenia.