TIMP2 ameliorates blood-brain barrier disruption in traumatic brain injury by inhibiting Src-dependent VE-cadherin internalization
Jingshu Tang, Yuying Kang, Yujun Zhou, Nianying Shang, Xinnan Li, Hongyue Wang, Jiaqi Lan, Shuai Wang, Lei Wu, Ying Peng
Jingshu Tang, Yuying Kang, Yujun Zhou, Nianying Shang, Xinnan Li, Hongyue Wang, Jiaqi Lan, Shuai Wang, Lei Wu, Ying Peng
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Research Article Neuroscience Vascular biology

TIMP2 ameliorates blood-brain barrier disruption in traumatic brain injury by inhibiting Src-dependent VE-cadherin internalization

Abstract

Blood-brain barrier (BBB) disruption is a serious pathological consequence of traumatic brain injury (TBI), for which there are limited therapeutic strategies. Tissue inhibitor of metalloproteinase-2 (TIMP2), a molecule with dual functions of inhibiting MMP activity and displaying cytokine-like activity through receptor binding, has been reported to inhibit VEGF-induced vascular hyperpermeability. Here, we investigate the ability of TIMP2 to ameliorate BBB disruption in TBI and the underlying molecular mechanisms. Both TIMP2 and AlaTIMP2, a TIMP2 mutant without MMP-inhibiting activity, attenuated neurological deficits and BBB leakage in TBI mice; they also inhibited junctional protein degradation and translocation to reduce paracellular permeability in human brain microvascular endothelial cells (ECs) exposed to hypoxic plus inflammatory insult. Mechanistic studies revealed that TIMP2 interacted with α3β1 integrin on ECs, inhibiting Src activation–dependent VE-cadherin phosphorylation, VE-cadherin/catenin complex destabilization, and subsequent VE-cadherin internalization. Notably, localization of VE-cadherin on the membrane was critical for TIMP2-mediated EC barrier integrity. Furthermore, TIMP2-mediated increased membrane localization of VE-cadherin enhanced the level of active Rac1, thereby inhibiting stress fiber formation. All together, our studies have identified an MMP-independent mechanism by which TIMP2 regulates EC barrier integrity after TBI. TIMP2 may be a therapeutic agent for TBI and other neurological disorders involving BBB breakdown.

Authors

Jingshu Tang, Yuying Kang, Yujun Zhou, Nianying Shang, Xinnan Li, Hongyue Wang, Jiaqi Lan, Shuai Wang, Lei Wu, Ying Peng

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Figure 1

TIMP2 ameliorates neurological dysfunction and alleviates Evans blue extravasation in TBI.

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TIMP2 ameliorates neurological dysfunction and alleviates Evans blue ext...
(A) Experimental scheme for TBI establishment, rmTIMP2 administration, neurological behavior assessment, and BBB integrity analysis in mice. WDI, weight drop injury. (B–D) TBI mice were intravenously given rmTIMP2 (10, 30, and 100 μg/kg) or PBS for 3 consecutive days, and neurological function was assessed at 24, 48, and 72 hours after TBI (n = 7 per group). (B) Fall latency of accelerated rotarod of mice from the indicated treatment groups. (C) Beam balance scores for mice from the indicated treatment groups. (D) mNSS of mice from the indicated treatment groups. (E) Representative images of brain tissues from the indicated treatment groups at 72 hours after TBI. The blue area indicates extravasation of Evans blue dye. (F) Quantification of leaked Evans blue dye in the ipsilateral cerebral hemisphere of mice from the indicated groups (n = 7 per group). ##P < 0.01 vs. sham group, *P < 0.05 and **P < 0.01 vs. model group, by 1-way ANOVA.