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Shear-dependent attenuation of cellular ROS levels can suppress proinflammatory cytokine injury to human brain microvascular endothelial barrier properties.

ABSTRACT: The regulatory interplay between laminar shear stress and proinflammatory cytokines during homeostatic maintenance of the brain microvascular endothelium is largely undefined. We hypothesized that laminar shear could counteract the injurious actions of proinflammatory cytokines on human brain microvascular endothelial cell (HBMvEC) barrier properties, in-part through suppression of cellular redox signaling. For these investigations, HBMvECs were exposed to either shear stress (8?dynes/cm(2), 24?hours) or cytokines (tumor necrosis factor-? (TNF-?) or interleukin-6 (IL-6), 0 to 100?ng/mL, 6 or 18?hours). Human brain microvascular endothelial cell 'preshearing'±cytokine exposure was also performed. Either cytokine dose-dependently decreased expression and increased phosphorylation (pTyr/pThr) of interendothelial occludin, claudin-5, and vascular endothelial-cadherin; observations directly correlating to endothelial barrier reduction, and in precise contrast to effects seen with shear. We further observed that, relative to unsheared cells, HBMvECs presheared for 24?hours exhibited significantly reduced reactive oxygen species production and barrier permeabilization in response to either TNF-? or IL-6 treatment. Shear also downregulated NADPH oxidase (nicotinamide adenine dinucleotide phosphate-oxidase) activation in HBMvECs, as manifested in the reduced expression and coassociation of gp91phox and p47phox. These findings lead us to conclude that physiologic shear can protect the brain microvascular endothelium from injurious cytokine effects on interendothelial junctions and barrier function by regulating the cellular redox state in-part through NADPH oxidase inhibition.

SUBMITTER: Rochfort KD

PROVIDER: S-EPMC4640321 | biostudies-literature | 2015 Oct

REPOSITORIES: biostudies-literature

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Shear-dependent attenuation of cellular ROS levels can suppress proinflammatory cytokine injury to human brain microvascular endothelial barrier properties.

Rochfort Keith D KD Collins Laura E LE McLoughlin Alisha A Cummins Philip M PM

Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism 20150520 10

The regulatory interplay between laminar shear stress and proinflammatory cytokines during homeostatic maintenance of the brain microvascular endothelium is largely undefined. We hypothesized that laminar shear could counteract the injurious actions of proinflammatory cytokines on human brain microvascular endothelial cell (HBMvEC) barrier properties, in-part through suppression of cellular redox signaling. For these investigations, HBMvECs were exposed to either shear stress (8 dynes/cm(2), 24 ...[more]

PMID: 25991069

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Project description:BackgroundThe endothelial cells that form the lumen of capillaries and microvessels are an important component of the blood-brain barrier. Cell phenotype is regulated by transducing a range of biomechanical and biochemical signals in the local microenvironment. Here we report on the role of shear stress in modulating the morphology, motility, proliferation, apoptosis, and protein and gene expression, of confluent monolayers of human brain microvascular endothelial cells derived from induced pluripotent stem cells.MethodsTo assess the response of derived human brain microvascular endothelial cells (dhBMECs) to shear stress, confluent monolayers were formed in a microfluidic device. Monolayers were subjected to a shear stress of 4 or 12 dyne cm-2 for 40 h. Static conditions were used as the control. Live cell imaging was used to assess cell morphology, cell speed, persistence, and the rates of proliferation and apoptosis as a function of time. In addition, immunofluorescence imaging and protein and gene expression analysis of key markers of the blood-brain barrier were performed.ResultsHuman brain microvascular endothelial cells exhibit a unique phenotype in response to shear stress compared to static conditions: (1) they do not elongate and align, (2) the rates of proliferation and apoptosis decrease significantly, (3) the mean displacement of individual cells within the monolayer over time is significantly decreased, (4) there is no cytoskeletal reorganization or formation of stress fibers within the cell, and (5) there is no change in expression levels of key blood-brain barrier markers.ConclusionsThe characteristic response of dhBMECs to shear stress is significantly different from human and animal-derived endothelial cells from other tissues, suggesting that this unique phenotype that may be important in maintenance of the blood-brain barrier. The implications of this work are that: (1) in confluent monolayers of dhBMECs, tight junctions are formed under static conditions, (2) the formation of tight junctions decreases cell motility and prevents any morphological transitions, (3) flow serves to increase the contact area between cells, resulting in very low cell displacement in the monolayer, (4) since tight junctions are already formed under static conditions, increasing the contact area between cells does not cause upregulation in protein and gene expression of BBB markers, and (5) the increase in contact area induced by flow makes barrier function more robust.

Dataset Information

Shear-dependent attenuation of cellular ROS levels can suppress proinflammatory cytokine injury to human brain microvascular endothelial barrier properties.

Publications

Shear-dependent attenuation of cellular ROS levels can suppress proinflammatory cytokine injury to human brain microvascular endothelial barrier properties.

Similar Datasets

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