Endothelial Cell Uptake of Infected Erythrocytes in Cerebral Malaria

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 DESCRIPTION (provided by applicant): Malaria due to Plasmodium falciparum remains one of the largest global infectious disease burdens, infecting over 200 million and killing nearly 700,000 people annually. Of several possible disease manifestations, cerebral malaria has the worst survival outcomes. Cerebral malaria, characterized by coma and neurological deficits, ensues when parasitized red blood cells (pRBCs) sequester in the cerebral vasculature. Cytoadherence can contribute to disease by obstructing peripheral blood vessels, limiting oxygen delivery to tissue, and inducing significant inflammation. Cerebral pRBC sequestration is linked to breakdown of the blood brain barrier, yet the molecular mechanisms mediating vascular damage in cerebral malaria are poorly understood. The host inflammatory response plays a major role, but a more complete understanding of sequestration-related pathophysiology is necessary to develop adjunct therapies for cerebral malaria. Recent in vitro findings demonstrate that human brain endothelial cells (ECs) take up pRBCs via formation of an apical cup resembling endothelial protrusions known to mediate leukocyte transendothelial migration (TEM). ICAM1 binding in TEM activates signaling that induces cytoskeletal remodeling and junction opening to allow for migration either through or between ECs. Since pRBCs also bind ICAM1 and the cup- formation described in pRBC uptake resembles that associated with transcellular TEM, we hypothesize that pRBC cytoadherence can mistakenly induce uptake via TEM pathways and that this contributes to the pathology of cerebral malaria. Our aims seek: 1) to explore the relationship between cup formation and pRBC uptake by ECs, investigating the receptors involved and comparing different clinical isolates of P. falciparum for their ability to induce cup formation; and 2) to determine how pRBC-induced cups and uptake contribute to disruption of the EC barrier, whether this occurs by signaling pathways that open junctions or by inducing cell death. Our long term goal is to understand how pRBCs induce endothelial activation and blood brain barrier breakdown in order to improve therapeutic development. Not only is characterizing endothelial pRBC uptake in the context of leukocyte TEM pathways a novel idea, but exploring pRBC uptake has significant implications for understanding and controlling cerebral malaria pathology.