Endothelial Von Willebrand Factor Promotes Blood–Brain Barrier Flexibility and Provides Protection From Hypoxia and Seizures in Mice

Abstract

Objective Aberrant blood-brain barrier (BBB) permeability is a hallmark pathology of many central nervous system diseases. von Willebrand factor (VWF) is stored in endothelial Weibel-Palade bodies from where it is released upon activation into plasma and basement membrane. VWF’s role in endothelial homeostasis is unclear. The goal of this study was to assess the role of VWF in disease models associated with increased BBB permeability. Approach and Results We did not find any differences in BBB permeability to Evan’s blue dye at baseline between wild-type (WT) and VWF−/− animals. We next utilized two models presenting with increased BBB permeability, hypoxia/reoxygenation and pilocarpine-induced status epilepticus, to assess the response of VWF−/− animals. In both models, VWF−/− mice maintained a tighter BBB than WT. VWF−/− mice fared worse in both conditions with nearly 100% of VWF−/− mice dying within 120 minutes after pilocarpine administration while more than 80% of WT animals survived. Investigation into the status of tight junction proteins revealed that VWF−/− mice expressed more claudin-5 at baseline. In vitro work confirmed that the presence of subendothelial VWF is inhibitory to claudin-5 expression. Conclusions VWF-deficiency confers partial preservation of BBB integrity after hypoxia/reoxygenation and seizures. Surprisingly, this decrease in BBB permeability did not result in protection of the animals as they demonstrated more severe pathology in both models when compared to WT animals. These data suggest that a rigid BBB is detrimental (to the organism) during certain disease states and that VWF release may provide desired flexibility under stress.

A novel role for von Willebrand factor in the pathogenesis of experimental cerebral malaria

“…38 In this study, we found that P berghei infection was associated with a significant increase in BBB permeability in both WT and VWF 2/2 mice. Interestingly, however, the degree of ECM-associated enhanced BBB permeability was significantly attenuated in the VWF 2/2 mice compared with WT controls.…”

“…54 In addition, endothelial VWF has recently been shown to play an important role in modulating permeability of the BBB under different pathological conditions. 38,39 Although the underlying biological mechanisms remain poorly understood, enhanced permeability of the BBB has also been implicated in the pathogenesis of CM. [55][56][57][58] We therefore investigated BBB permeability in VWF 2/2 mice compared with WT mice following infection with P berghei.…”

“…[55][56][57] In addition, recent studies have demonstrated that VWF plays an important role in regulating the BBB. 38,39 For example, significantly attenuated BBB permeability was observed in VWF 2/2 mice compared with WT controls in a hypoxia/reoxygenation model, and also in an experimental model of status epilepticus. 38 Although the molecular mechanisms through which VWF influences BBB integrity remain poorly understood, a significant increase in expression of the endothelial tight junction protein claudin-5 was demonstrated in the cerebral microvascular EC of VWF 2/2 mice compared with WT controls.…”

An integrative microfluidically supported in vitro model of an endothelial barrier combined with cortical spheroids simulates effects of neuroinflammation in neocortex development

“…In hCMEC/D3 cell layers, we analysed the expression of von Willebrand factor (vWF), a protein that is involved in regulation of coagulation and moreover is a central regulator of permeability and flexibility of the endothelial cell layer within the BBB. 18 In addition, we examined the expression of VE-cadherin and b-catenin, proteins required for the maintenance of endothelial barrier integrity and CNS homeostasis, 19 as well as the tight junction protein ZO-1. We observed no alterations in the protein expression of these proteins during adaption and subsequent culture of CMEC in CTM/ECM medium compared with ECM medium (Figure 4(b)).…”

“…HCMEC/D3 cell layers expressed central marker proteins known to regulate BBB integrity and flexibility in vivo, such as vWF, VE-cadherin, ZO-1, and b-catenin. [4][5][6]9,10,18,19 Furthermore, this model is able to reflect critical aspects of neuroinflammation, as depicted by its ability to specifically reproduce a cytokineinduced disruption of the endothelial barrier associated with subsequent alterations in neural cell morphology, increased neural cell death, and diminished expression of neural differentiation marker proteins. Our results are in agreement with the findings from studies in mice that analysed the development of the neocortex under inflammatory conditions.…”