Bradykinin contributes to vasogenic edema in murine experimental cerebral malaria

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Abstract

Cerebral malaria (CM) from Plasmodium falciparum is a major cause of death in African children. Since bradykinin (BK) is a mediator of vasogenic edema, we hypothesized that it contributes to the pathogenesis of CM in Kenyan children and Plasmodium berghei ANKA–infected (PbA-infected) C57BL/6J mice in experimental CM (ECM). Cleaved plasma high-molecular-weight kininogen (cHK) is a marker for BK release. 40% of children with central nervous system malaria had plasma cHK versus 18% of children with uncomplicated malaria. Wild-type PbA-infected mice with ECM had circulating cHK, elevated BK levels, and reduced HK and prekallikrein activity/antigen levels. HK-null (Kng1–/–), combined BK B1– and B2 receptor–null (Bdkrb1–/–Bdkrb2–/–), BK B2 receptor–null (Bdkrb2–/–), or BK B1 receptor–null (Bdkrb1–/–) mice were protected significantly from neurologic deterioration and brain edema compared with wild-type mice. F12–/– mice were not protected from neurological deterioration. Prekallikrein-null (Klkb1–/–), prolylcarboxypeptidase hypomorph (Prcpgt/gt), and brain endothelial cell conditional KO of PRCP (Prcpfl/fl Cre) mice with ECM had reduced neurologic deterioration and brain edema. Adjuvant plasma kallikrein inhibition combined with artesunate treatment in PbA-infected mice reversed neurologic deterioration and brain edema and significantly prolonged survival over artesunate alone. BK-induced vasogenic edema contributes to human and murine CM.

Authors

Alessandro de Sa Pinheiro, Douglas E. Teixeira, Rodrigo P. Silva-Aguiar, Young Jun Shim, Alona A. Merkulova, Sadiq Silbak, Yelenna Skomorovska-Prokvolit, David Midem, Sidney Ogolla, Bjoern B. Burckhardt, Tanja Gangnus, Julio Scharfstein, Celso Caruso-Neves, Owen J.T. McCarty, David Gailani, Michael Bader, Philip J. Rosenthal, Arlene E. Dent, Chris J. Janse, Keith R. McCrae, Ana Acacia de Sa Pinheiro, James W. Kazura, Alvin H. Schmaier