Endothelial peroxiredoxin-4 is indispensable for blood–brain barrier integrity and long-term functional recovery after ischemic stroke

Is your competent? doctor and hospital going to ensure human testing gets done? Or don't you have a functioning stroke doctor or hospital? Why would your board of directors let incompetence fester so long? Don't they know what incompetence looks like?

 Endothelial peroxiredoxin-4 is indispensable for blood–brain barrier integrity and long-term functional recovery after ischemic stroke

Na Xu, Xiaoyan Jiang, Wenting Zhang https://orcid.org/0000-0002-2277-4686, +9 , and Jun Chen https://orcid.org/0000-0002-8077-3403 chenj2@upmc.eduAuthors Info & Affiliations

Edited by Jeremy Nathans, Johns Hopkins University School of Medicine, Baltimore, MD; received January 15, 2024; accepted January 16, 2024

March 4, 2024

121 (11) e2400272121

https://doi.org/10.1073/pnas.2400272121

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Vol. 121 | No. 11

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Significance

Using endothelium-specific gene knockout or overexpression, we demonstrate that Prx4 protects animals against blood–brain barrier (BBB) damage induced by cerebral ischemia/reperfusion (I/R) injury. Endothelial Prx4 preserves the functional integrity of the BBB by inhibiting myosin light chain/stress fiber formation and tight-junction protein disassembly during the early stages of cerebral I/R. Prx4-afforded endothelial protection blunts endothelial inflammation and leukocyte infiltration, thereby tempering cerebral inflammation and improving long-term stroke outcomes. These results uncover a critical role for Prx4 as an essential safeguard of the BBB after ischemic/reperfusion brain injury.

Abstract

The endothelial lining of cerebral microvessels is damaged relatively early after cerebral ischemia/reperfusion (I/R) injury and mediates blood–brain barrier (BBB) disruption, neurovascular injury, and long-term neurological deficits. I/R induces BBB leakage within 1 h due to subtle structural alterations in endothelial cells (ECs), including reorganization of the actin cytoskeleton and subcellular redistribution of junctional proteins. Herein, we show that the protein peroxiredoxin-4 (Prx4) is an endogenous protectant against endothelial dysfunction and BBB damage in a murine I/R model. We observed a transient upregulation of Prx4 in brain ECs 6 h after I/R in wild-type (WT) mice, whereas tamoxifen-induced, selective knockout of Prx4 from endothelial cells (eKO) mice dramatically raised vulnerability to I/R. Specifically, eKO mice displayed more BBB damage than WT mice within 1 to 24 h after I/R and worse long-term neurological deficits and focal brain atrophy by 35 d. Conversely, endothelium-targeted transgenic (eTG) mice overexpressing Prx4 were resistant to I/R-induced early BBB damage and had better long-term functional outcomes. As demonstrated in cultures of human brain endothelial cells and in animal models of I/R, Prx4 suppresses actin polymerization and stress fiber formation in brain ECs, at least in part by inhibiting phosphorylation/activation of myosin light chain. The latter cascade prevents redistribution of junctional proteins and BBB leakage under conditions of Prx4 repletion. Prx4 also tempers microvascular inflammation and infiltration of destructive neutrophils and proinflammatory macrophages into the brain parenchyma after I/R. Thus, the evidence supports an indispensable role for endothelial Prx4 in safeguarding the BBB and promoting functional recovery after I/R brain injury.