ATP release and ectonucleotidase activity shape infected red blood cell adhesion in placental malaria

Abstract Placental malaria is characterized by the sequestration of Plasmodium falciparum –infected red blood cells (iRBCs) within the intervillous space through VAR2CSA-mediated adhesion to chondroitin sulfate A (CSA) expressed on trophoblasts. Although cytoadherence is a key pathogenic event, its impact on extracellular ATP (eATP) signaling remains poorly understood. Here, we investigated eATP dynamics during trophoblast–iRBC interactions using BeWo-derived cytotrophoblast (CTB) and syncytiotrophoblast (STB) models together with human placental explants. CSA-binding iRBCs induced significantly greater eATP accumulation than culture-matched RBCs or CD36-binding parasites. eATP accumulation required direct cell contact and was reduced by soluble CSA, indicating that it is closely associated with VAR2CSA-dependent adhesion. Degradation of eATP by apyrase markedly reduced cytoadherence, and pharmacological modulation of purinergic signaling similarly disrupted the adhesive interaction, indicating that eATP homeostasis contributes to efficient cytoadherence. CTB, STB and placental explants exhibited substantial ATP-hydrolyzing activity and expressed multiple ectoenzymes. Placental tissue displayed a markedly higher capacity to remove eATP than trophoblast cultures, which likely contributes to the absence of detectable eATP accumulation in explants exposed to iRBCs. A data-driven model fitted to the experimental eATP kinetics enabled estimation of the ATP efflux, showing that early eATP dynamics are dominated by ATP release, while ectoATPase-driven hydrolysis acts as a buffering mechanism whose contribution grows over time as eATP accumulates. Together, these findings identify eATP metabolism as a previously underappreciated component of trophoblast–parasite interactions and suggest that regulation of eATP availability contributes to host–parasite communication during placental malaria.