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Open AccessArticle

Downregulation of S1P Lyase Improves Barrier Function in Human Cerebral Microvascular Endothelial Cells Following an Inflammatory Challenge

1
Institute of Pharmacology, University of Bern, Inselspital, INO-F, CH-3010 Bern, Switzerland
2
Department of Anesthesiology and Intensive Care Medicine, Jena University Hospital, D-07747 Jena, Germany
3
Septomics Research Center, Jena University Hospital, D-07747 Jena, Germany
4
Pharmazentrum Frankfurt/ZAFES, University Hospital, Goethe University Frankfurt am Main, Theodor-Stern Kai 7, D-60590 Frankfurt am Main, Germany
5
Center for Sepsis Control and Care, Jena University Hospital, D-07747 Jena, Germany
*
Author to whom correspondence should be addressed.
Int. J. Mol. Sci. 2020, 21(4), 1240; https://doi.org/10.3390/ijms21041240
Received: 19 December 2019 / Revised: 30 January 2020 / Accepted: 10 February 2020 / Published: 13 February 2020
(This article belongs to the Collection Sphingolipid Signaling in Health and Disease)
Sphingosine 1-phosphate (S1P) is a key bioactive lipid that regulates a myriad of physiological and pathophysiological processes, including endothelial barrier function, vascular tone, vascular inflammation, and angiogenesis. Various S1P receptor subtypes have been suggested to be involved in the regulation of these processes, whereas the contribution of intracellular S1P (iS1P) through intracellular targets is little explored. In this study, we used the human cerebral microvascular endothelial cell line HCMEC/D3 to stably downregulate the S1P lyase (SPL-kd) and evaluate the consequences on endothelial barrier function and on the molecular factors that regulate barrier tightness under normal and inflammatory conditions. The results show that in SPL-kd cells, transendothelial electrical resistance, as a measure of barrier integrity, was regulated in a dual manner. SPL-kd cells had a delayed barrier build up, a shorter interval of a stable barrier, and, thereafter, a continuous breakdown. Contrariwise, a protection was seen from the rapid proinflammatory cytokine-mediated barrier breakdown. On the molecular level, SPL-kd caused an increased basal protein expression of the adherens junction molecules PECAM-1, VE-cadherin, and β-catenin, increased activity of the signaling kinases protein kinase C, AMP-dependent kinase, and p38-MAPK, but reduced protein expression of the transcription factor c-Jun. However, the only factors that were significantly reduced in TNFα/SPL-kd compared to TNFα/control cells, which could explain the observed protection, were VCAM-1, IL-6, MCP-1, and c-Jun. Furthermore, lipid profiling revealed that dihydro-S1P and S1P were strongly enhanced in TNFα-treated SPL-kd cells. In summary, our data suggest that SPL inhibition is a valid approach to dampenan inflammatory response and augmente barrier integrity during an inflammatory challenge. View Full-Text
Keywords: blood–brain barrier; endothelial integrity; inflammation; S1P lyase; junctional molecules; PKC blood–brain barrier; endothelial integrity; inflammation; S1P lyase; junctional molecules; PKC
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MDPI and ACS Style

Stepanovska, B.; Lange, A.I.; Schwalm, S.; Pfeilschifter, J.; Coldewey, S.M.; Huwiler, A. Downregulation of S1P Lyase Improves Barrier Function in Human Cerebral Microvascular Endothelial Cells Following an Inflammatory Challenge. Int. J. Mol. Sci. 2020, 21, 1240.

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