Interendothelial Claudin-5 Expression Depends on Cerebral Endothelial Cell–Matrix Adhesion by β₁-Integrins

Abstract

The hypothesis tested by these studies states that in addition to interendothelial cell tight junction proteins, matrix adhesion by b 1 -integrin receptors expressed by endothelial cells have an important role in maintaining the cerebral microvessel permeability barrier. Primary brain endothelial cells from C57 BL/6 mice were incubated with b 1 -integrin function-blocking antibody (Ha2/5) or isotype control and the impacts on claudin-5 expression and microvessel permeability were quantified. Both flow cytometry and immunofluorescence studies demonstrated that the interendothelial claudin-5 expression by confluent endothelial cells was significantly decreased in a time-dependent manner by Ha2/5 exposure relative to isotype. Furthermore, to assess the barrier properties, transendothelial electrical resistance and permeability measurements of the monolayer, and stereotaxic injection into the striatum of mice were performed. Ha2/5 incubation reduced the resistance of endothelial cell monolayers significantly, and significantly increased permeability to 40 and 150 kDa dextrans. Ha2/5 injection into mouse striatum produced significantly greater IgG extravasation than the isotype or the control injections. This study demonstrates that blockade of b 1 -integrin function changes interendothelial claudin-5 expression and increases microvessel permeability. Hence, endothelial cell-matrix interactions via b 1 -integrin directly affect interendothelial cell tight junction claudin-5 expression and brain microvascular permeability.

PKC-βExacerbatesin vitroBrain Barrier Damage in Hyperglycemic Settings via Regulation of RhoA/Rho-kinase/MLC2 Pathway

“…32 Bearing HG-induced cytoskeletal reorganization in mind, possible changes exerted on HBMEC-matrix interactions regulated via b1-integrin may also contribute to barrier permeability by directly affecting claudin-5 expression as recently reported. 33 In conclusion, the current study demonstrates that activations of PKC-b or RhoA/Rho-kinase/p-MLC2 pathway under hyperglycemic conditions mediate the structural and functional impairment of an in vitro model of human cerebral barrier. Considering the regulatory effects of PKC-b on the expression, phosphorylation, and/or activity of RhoA/Rho-kinase/p-MLC2 pathway components and organization of cytoskeleton and TJ assembly, it is plausible to suggest that PKC-b may be an efficacious novel therapeutic target to stem the cerebral barrier dysfunction in hyperglycemic stroke.…”

Formation and maintenance of the BBB

“…There are two basement membranes at the BBB: the vascular basement membrane secreted by BECs and pericytes, and the glial basement membrane secreted by astrocytes. The ECM provides structural support for the vessels, a scaffold for growth factors such as PDGF-BB, VEGF, TGF-β, as well as providing a physical barrier for leukocyte migration into the parenchyma.The basement membrane also regulates BBB permeability.Osada et al demonstrated that endothelial cell adhesion to the ECM by β 1 -integrins increases CLDN-5 expression(Osada et al, 2011). Moreover,Menezes et al observed that Lama2-null mice display an increase in BBB permeability compared to wildtype littermates which correlated with a lower pericyte and astrocytic endfeet coverage, a lower expression of VE-cadherin, Cldn-5 and occludin and an increase of PLVAP expression(Menezes et al, 2014).…”

The effect of ASK1 on vascular permeability and edema formation in cerebral ischemia

“…We sorted genes that were increased over 2-fold in the MCAO group compared with normal group, then screened for genes that were down-regulated more than 2-fold in the si-ASK1 group compared with the MCAO group. Several genes were selected, including matrix metallopeptidase 3 (MMP3) (Ashina et al, 2010), integrin alpha 8 (Itga8) (Cucullo et al, 2011;Osada et al, 2011), cadherin 1 (Cdh1) (Zechariah et al, 2013), gap junction protein beta 1 (Gjb3) (Song et al, 2007), Selectin (Sele) (Jin et al, 2010), intercellular adhesion molecule 1 (Icam1) (An and Xue, 2009), aquaporin 8 (Aqp8) (Richard et al, 2003), aquaporin 12 (Aqp12) (Calvanese et al, 2013) related with vascular permeability. Also, vascular endothelial growth factor A (Vegfa) (Gong et al, 2014;Poittevin et al, 2014), and vascular endothelial growth factor C (Vegfc) (Foster et al, 2008;Xu et al, 2013) which are related with vascular permeability were down-regulated in the si-ASK1 group compared with the MCAO group slightly.…”