EphA2 prevents breakdown of the blood-brain barrier in experimental cerebral malaria.

Abstract

Cerebral malaria (CM) is a leading cause of death from Plasmodium falciparum infection, yet the mechanisms of disease pathology are poorly understood. While Eph receptors have been linked to several neurological disorders, their roles in malaria remain largely unknown. Experimental cerebral malaria (ECM) is a lethal condition resulting from Plasmodium berghei ANKA (PbANKA) infection of mice on a C57BL/6J background that recapitulates key features of human CM including blood-brain barrier (BBB) breakdown. Here we show that PbANKA-infected EphA2 −/− mice, but not EphA2 +/+ mice, have an intact BBB at ECM onset. CD8+ T cells mediate ECM development, and EphA2 −/− mice exhibit less accumulation of CD8+ T cells in the brain despite normal splenic expansion providing a mechanism by which EphA2 deficiency may preserve BBB integrity. Upregulation of EphA2 mRNA in brains of PbANKA-infected C57BL/6J mice is a feature of ECM absent in non-lethal Plasmodium infections such as PbNK65 where CD8+ T cells are present in the brain but do not disrupt the BBB. Unlike EphA2 +/+ mice, PbANKA-infected EphA2 −/− mice are protected from death even with peripheral and organ-sequestered parasite levels similar to EphA2 +/+ mice suggesting BBB integrity, not parasite burden, is responsible for improved survival in EphA2 −/− mice. Therapeutically targeting EphA2 by blocking EphA2 activation or interaction with membrane-bound ephrin-A ligands on T cells leads to increased survival of PbANKA-infected C57BL/6J mice. We also observe a parasite-dependent upregulation of both ephrin-A mRNA in CD3+ human PBMCs and EphA2 mRNA in human brain endothelial cells. Taken together, our data suggests a novel and crucial role for EphA2 in ECM with potential translation to human CM.