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Testing the effect of PAR1 inhibitors on Plasmodium falciparum-induced loss of endothelial cell barrier function.

ABSTRACT: Background: Sequestration and cytoadherence of Plasmodium falciparum-infected erythrocytes (IE) to microvascular endothelium alters endothelial barrier function and plays a role in the pathogenesis of severe malaria. Binding of IE is mediated by P. falciparum erythrocyte membrane protein 1 (PfEMP1) and the PfEMP1 variants that binds to endothelial protein C receptor (EPCR) have, in particular, been associated with the dysregulation of the coagulation/inflammation pathways in endothelial cells. This has prompted speculation about the role of protease-activated receptor-1 (PAR1) activation and signalling in causing endothelial activation and loss of barrier function in cerebral malaria. Methods: We used a co-culture of primary human brain microvascular endothelial cells (HBMEC) with P. falciparum material, recombinant PfEMP1 or lysates from IE, and measured barrier function by trans endothelial electrical resistance (TEER). A selection of PAR1 inhibitors was tested for their ability to reverse the P. falciparum and thrombin induced decrease in barrier function. Results: An initial screen in the presence of recombinant PfEMP1 identified a few inhibitors that were able to reduce the rapid thrombin-induced barrier disruption even when activated protein C (aPC) was unable to do so. However, PAR1 inhibitors did not rescue the barrier dysfunction after co-culture with IE lysate. Conclusions: The selected PAR1 inhibitors were able to reverse the disruption of barrier function by thrombin but did not reverse the IE lysate induced disruption of barrier function, implicating a different PAR1-independent mechanism. These findings have implications for the design of adjunct therapies to reduce brain swelling in cerebral malaria.

SUBMITTER: Storm J

PROVIDER: S-EPMC7364184 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Testing the effect of PAR1 inhibitors on Plasmodium falciparum-induced loss of endothelial cell barrier function.

Storm Janet J Wu Yang Y Davies Jill J Moxon Christopher A CA Craig Alister G AG

Wellcome open research 20200707

Background: Sequestration and cytoadherence of Plasmodium falciparum-infected erythrocytes (IE) to microvascular endothelium alters endothelial barrier function and plays a role in the pathogenesis of severe malaria. Binding of IE is mediated by P. falciparum erythrocyte membrane protein 1 (PfEMP1) and the PfEMP1 variants that binds to endothelial protein C receptor (EPCR) have, in particular, been associated with the dysregulation of the coagulation/inflammation pathways in ...[more]

PMID: 32724861

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Project description:Cerebral malaria is a severe complication of Plasmodium falciparum infection characterized by the loss of blood-brain barrier (BBB) integrity, which is associated with brain swelling and mortality in patients. P. falciparum-infected red blood cells and inflammatory cytokines, like tumor necrosis factor alpha (TNF-α), have been implicated in the development of cerebral malaria, but it is still unclear how they contribute to the loss of BBB integrity. Here, a combination of transcriptomic analysis and cellular assays detecting changes in barrier integrity and endothelial activation were used to distinguish between the effects of P. falciparum and TNF-α on a human brain microvascular endothelial cell (HBMEC) line and in primary human brain microvascular endothelial cells. We observed that while TNF-α induced high levels of endothelial activation, it only caused a small increase in HBMEC permeability. Conversely, P. falciparum-infected red blood cells (iRBCs) led to a strong increase in HBMEC permeability that was not mediated by cell death. Distinct transcriptomic profiles of TNF-α and P. falciparum in HBMECs confirm the differential effects of these stimuli, with the parasite preferentially inducing an endoplasmic reticulum stress response. Our results establish that there are fundamental differences in the responses induced by TNF-α and P. falciparum on brain endothelial cells and suggest that parasite-induced signaling is a major component driving the disruption of the BBB during cerebral malaria, proposing a potential target for much needed therapeutics. IMPORTANCE Cerebral malaria is a severe complication of Plasmodium falciparum infection that causes the loss of blood-brain barrier integrity and frequently results in death. Here, we compared the effect of P. falciparum-infected red blood cells and inflammatory cytokines, like TNF-α, in the loss of BBB integrity. We observed that while TNF-α induced a small increase in barrier permeability, P. falciparum-infected red blood cells led to a severe loss of barrier integrity. Our results establish that there are fundamental differences in the responses induced by TNF-α and P. falciparum on brain endothelial cells and suggest that parasite-induced signaling is a major component driving the disruption of the BBB during cerebral malaria, proposing a potential target for much needed therapeutics.

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Testing the effect of PAR1 inhibitors on Plasmodium falciparum-induced loss of endothelial cell barrier function.

Publications

Testing the effect of PAR1 inhibitors on <i>Plasmodium falciparum</i>-induced loss of endothelial cell barrier function.

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