Molecular Mechanisms in Pediatric Cerebral Malaria Pathogenesis and Immunity

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PROJECT ABSTRACT The human malaria parasite Plasmodium falciparum remains one of the most important causes of childhood mortality in the world. Cerebral malaria, the most severe complication of P. falciparum infection, is caused by the sequestration of infected red blood cells in cerebral microvasculature. The var gene or P. falciparum erythrocyte membrane protein 1 (PfEMP1) is the major cytoadhesion ligand for the parasite. While progress has been made in understanding the structure and function of PfEMP1 proteins, the key parasite ligand- receptor interactions involved in cerebral binding remain unestablished. Our recent studies have shown that specific parasite adhesion types are increased in the blood of cerebral malaria patients, and that parasite adhesion to endothelial protein C receptor (EPCR) may impair a key anticoagulant and barrier protective pathway. Moreover, we have shown that hyperlactemia increases fatality risk in pediatric cerebral malaria. However, large knowledge gaps remain in parasite sequestration in brain, in large part due to its inaccessibility and the lack of appropriate in vitro models. We have recently developed an innovative technology using 3D human brain microvessels that recapitulates physiological flow characteristics in health and disease. We are able to fabricate 3D microvessels with different geometries and lumen dimensions, which allow us to study parasite adhesion across a range of flow velocities in a single device, as well as to investigate factors that contribute to microvascular obstruction in malaria. In this project, we will use 3D human brain microvessels in combination with parasite isolates from pediatric cerebral malaria cases to investigate parasite tropism for brain, to identify the precise steps of infected red blood cell capture and firm adhesion on brain endothelial cells, to characterize potential interactions between lactemia and parasite adhesiveness, and to investigate antibody protective mechanisms in cerebral malaria. The proposed studies will advance our understanding of the molecular mechanisms of P. falciparum binding in cerebral malaria and immune mechanisms in anti- disease immunity.