Abstract
Herein we show that S1P rapidly and acutely reduces the focal adhesion strength and barrier tightness of brain endothelial cells. xCELLigence biosensor technology was used to measure focal adhesion, which was reduced by S1P acutely and this response was mediated through both S1P1 and S1P2 receptors. S1P increased secretion of several pro-inflammatory mediators from brain endothelial cells. However, the magnitude of this response was small in comparison to that mediated by TNFα or IL-1β. Furthermore, S1P did not significantly increase cell-surface expression of any key cell adhesion molecules involved in leukocyte recruitment, included ICAM-1 and VCAM-1. Finally, we reveal that S1P acutely and dynamically regulates microvascular endothelial barrier tightness in a manner consistent with regulated rapid opening followed by closing and strengthening of the barrier. We hypothesise that the role of the S1P receptors in this process is not to cause barrier dysfunction, but is related to controlled opening of the endothelial junctions. This was revealed using real-time measurement of barrier integrity using ECIS ZΘ TEER technology and endothelial viability using xCELLigence technology. Finally, we show that these responses do not occur simply though the pharmacology of a single S1P receptor but involves coordinated action of S1P1 and S1P2 receptors.
Highlights
We show that S1P rapidly and acutely reduces the focal adhesion strength and barrier tightness of brain endothelial cells. xCELLigence biosensor technology was used to measure focal adhesion, which was reduced by S1P acutely and this response was mediated through both S1P1 and S1P2 receptors
S1P is produced by platelets, immune cells, endothelial cells, and recent evidence has emerged for its production by astrocytes[1,2]
We used xCELLigence real time cell analyser (RTCA) biosensor technology to profile the temporal response of brain endothelial cells to various concentrations of S1P
Summary
We show that S1P rapidly and acutely reduces the focal adhesion strength and barrier tightness of brain endothelial cells. xCELLigence biosensor technology was used to measure focal adhesion, which was reduced by S1P acutely and this response was mediated through both S1P1 and S1P2 receptors. We show that S1P rapidly and acutely reduces the focal adhesion strength and barrier tightness of brain endothelial cells. S1P receptors of secondary lymphoid tissues, preventing the egress of T cells from lymphoid tissues back to the vascular circulation[1] This reduces the number of circulating lymphocytes and prevents the trafficking of autoimmune cells into CNS lesions across the blood brain barrier[8]. We propose it is likely that different vessel types or brain regions express a different profile of S1P receptor expression, which would influence the nature of the response to S1P in vivo. This has not been studied in detail in the human brain and warrants further investigation
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