Angiotensin receptors and β-catenin regulate brain endothelial integrity in malaria
Julio Gallego-Delgado, … , Marta Ruiz-Ortega, Ana Rodriguez
Julio Gallego-Delgado, … , Marta Ruiz-Ortega, Ana Rodriguez
Published September 19, 2016
Citation Information: J Clin Invest. 2016;126(10):4016-4029. https://doi.org/10.1172/JCI87306.
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Research Article Infectious disease Vascular biology

Angiotensin receptors and β-catenin regulate brain endothelial integrity in malaria

Abstract

Cerebral malaria is characterized by cytoadhesion of Plasmodium falciparum–infected red blood cells (Pf-iRBCs) to endothelial cells in the brain, disruption of the blood-brain barrier, and cerebral microhemorrhages. No available antimalarial drugs specifically target the endothelial disruptions underlying this complication, which is responsible for the majority of malaria-associated deaths. Here, we have demonstrated that ruptured Pf-iRBCs induce activation of β-catenin, leading to disruption of inter–endothelial cell junctions in human brain microvascular endothelial cells (HBMECs). Inhibition of β-catenin–induced TCF/LEF transcription in the nucleus of HBMECs prevented the disruption of endothelial junctions, confirming that β-catenin is a key mediator of P. falciparum adverse effects on endothelial integrity. Blockade of the angiotensin II type 1 receptor (AT1) or stimulation of the type 2 receptor (AT2) abrogated Pf-iRBC–induced activation of β-catenin and prevented the disruption of HBMEC monolayers. In a mouse model of cerebral malaria, modulation of angiotensin II receptors produced similar effects, leading to protection against cerebral malaria, reduced cerebral hemorrhages, and increased survival. In contrast, AT2-deficient mice were more susceptible to cerebral malaria. The interrelation of the β-catenin and the angiotensin II signaling pathways opens immediate host-targeted therapeutic possibilities for cerebral malaria and other diseases in which brain endothelial integrity is compromised.

Authors

Julio Gallego-Delgado, Upal Basu-Roy, Maureen Ty, Matilde Alique, Cristina Fernandez-Arias, Alexandru Movila, Pollyanna Gomes, Ada Weinstock, Wenyue Xu, Innocent Edagha, Samuel C. Wassmer, Thomas Walther, Marta Ruiz-Ortega, Ana Rodriguez

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Figure 5

Modulators of Ang II receptors inhibit Pf-iRBC–induced β-catenin activation, detachment, and disruption of IEJs in HBMECs.

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Modulators of Ang II receptors inhibit Pf-iRBC–induced β-catenin activat...
(A) HBMEC monolayers were incubated with specific antibodies against AT1 and AT2 receptors followed by a secondary antibody (right panels) or with only the secondary antibody (left panels). (B and C) As in Figure 4A, HBMEC monolayers were infected with β-catenin reporter lentivirus before incubation with iRBCs alone (40:1) or together with losartan (10–5 M) or CGP-42112A (10–5 M) for 18 hours. (B) The same microscopic field is shown for eGFP alone and merged with mCherry and nuclei. (C) Quantification of eGFP fluorescence per cell. (D–H) HBMEC monolayers were incubated with Pf-iRBCs, losartan, and CGP-42112A as in B followed (D–G) or not (H) by immunostaining for β-catenin (green) and nuclei (blue). (E–G) Quantification of green fluorescence intensity per cell (E), green fluorescence intensity in the perinuclear and nuclear areas versus IEJs for each cell (F), and number of cells per microscopic field (G). (H) PrestoBlue determination of viable attached HBMECs. Results are representative of at least 2 independent experiments. Scale bar: 40 μm. Error bars represent ±SEM. **P < 0.01, ***P < 0.001 compared with control. Kruskal-Wallis test and pairwise comparisons using Dunn’s procedure with a Bonferroni correction for multiple comparisons.