Dataset Information

Pharmacological pre- and post-conditioning with the sphingosine-1-phosphate receptor modulator FTY720 after myocardial ischaemia-reperfusion.

ABSTRACT:

Background and purpose

Our recent experiments demonstrated that the Sphingosine-1-phosphate (S1P) receptor agonist FTY720 (2-amino-2-[2-(4-octylphenyl)ethyl]-1,3-propanediol hydrochloride) improves recovery of function after myocardial ischaemia-reperfusion ex vivo. Therefore, we tested the hypothesis that pharmacological post-conditioning with FTY720 reduces infarct size after myocardial ischaemia-reperfusion in vivo.

Experimental approach

Myocardial ischaemia was induced in Wistar rats by ligation of the left coronary artery for 45 min. FTY720 (0.5 mg kg(-1)) was applied i.p. either once, before reperfusion, or twice, 24 h before myocardial ischaemia and before reperfusion. After 24 h reperfusion, we determined infarct size by triphenyltetrazolium chloride staining and granulocyte infiltration by immunohistochemistry. Tumour necrosis factor-alpha (TNF)-alpha concentration was determined by elisa. S1P receptor expression was studied by Western blot. Calcium transients were evaluated in Indo-1-loaded cardiomyocytes.

Key results

In both groups, FTY720 significantly reduced lymphocyte count in peripheral blood. FTY720 treatment attenuated granulocyte infiltration and TNF-alpha protein expression in reperfused myocardium. However, both treatment regimens were not able to reduce infarct size. FTY720 increased mortality due to induction of fatal ventricular tachyarrhythmias when administered once before reperfusion, but protected against reperfusion arrhythmias when given 24 h prior to ischaemia. Pretreatment selectively down-regulated S1P(1) receptor expression within the myocardium. S1P receptor agonists did not induce calcium deregulation in cardiomyocytes.

Conclusions and implications

FTY720 applied during reperfusion did not reduce infarct size but increased mortality during myocardial ischaemia-reperfusion due to induction of arrhythmias. Pretreatment with FTY720 before ischaemia abrogated the deleterious pro-arrhythmic effects without reducing infarct size.

SUBMITTER: Hofmann U

PROVIDER: S-EPMC2936032 | biostudies-literature | 2010 Jul

REPOSITORIES: biostudies-literature

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Publications

Pharmacological pre- and post-conditioning with the sphingosine-1-phosphate receptor modulator FTY720 after myocardial ischaemia-reperfusion.

Hofmann U U Hu K K Walter F F Burkard N N Ertl G G Bauersachs J J Ritter O O Frantz S S Bonz A A

British journal of pharmacology 20100701 5

<h4>Background and purpose</h4>Our recent experiments demonstrated that the Sphingosine-1-phosphate (S1P) receptor agonist FTY720 (2-amino-2-[2-(4-octylphenyl)ethyl]-1,3-propanediol hydrochloride) improves recovery of function after myocardial ischaemia-reperfusion ex vivo. Therefore, we tested the hypothesis that pharmacological post-conditioning with FTY720 reduces infarct size after myocardial ischaemia-reperfusion in vivo.<h4>Experimental approach</h4>Myocardial ischaemia was induced in Wist ...[more]

PMID: 20590616

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Project description:Aims:Myocardial ischaemia followed by reperfusion (IR) causes an oxidative burst resulting in cellular dysfunction. Little is known about the impact of oxidative stress on cardiomyocyte lipids and their role in cardiac cell death. Our goal was to identify oxidized phosphatidylcholine-containing phospholipids (OxPL) generated during IR, and to determine their impact on cell viability and myocardial infarct size. Methods and results:OxPL were quantitated in isolated rat cardiomyocytes using mass spectrophotometry following 24?h of IR. Cardiomyocyte cell death was quantitated following exogenously added OxPL and in the absence or presence of E06, a 'natural' murine monoclonal antibody that binds to the PC headgroup of OxPL. The impact of OxPL on mitochondria in cardiomyocytes was also determined using cell fractionation and Bnip expression. Transgenic Ldlr-/- mice, overexpressing a single-chain variable fragment of E06 (Ldlr-/--E06-scFv-Tg) were used to assess the effect of inactivating endogenously generated OxPL in vivo on myocardial infarct size. Following IR in vitro, isolated rat cardiomyocytes showed a significant increase in the specific OxPLs PONPC, POVPC, PAzPC, and PGPC (P?<?0.05 to P?<?0.001 for all). Exogenously added OxPLs resulted in significant death of rat cardiomyocytes, an effect inhibited by E06 (percent cell death with added POVPC was 22.6?±?4.14% and with PONPC was 25.3?±?3.4% compared to 8.0?±?1.6% and 6.4?±?1.0%, respectively, with the addition of E06, P?<?0.05 for both). IR increased mitochondrial content of OxPL in rat cardiomyocytes and also increased expression of Bcl-2 death protein 3 (Bnip3), which was inhibited in presence of E06. Notably cardiomyocytes with Bnip3 knock-down were protected against cytotoxic effects of OxPL. In mice exposed to myocardial IR in vivo, compared to Ldlr-/- mice, Ldlr-/--E06-scFv-Tg mice had significantly smaller myocardial infarct size normalized to area at risk (72.4?±?21.9% vs. 47.7?±?17.6%, P?=?0.023). Conclusions:OxPL are generated within cardiomyocytes during IR and have detrimental effects on cardiomyocyte viability. Inactivation of OxPL in vivo results in a reduction of infarct size.

Project description:Vascular permeability is a hallmark of acute respiratory distress syndrome (ARDS) and ventilator-induced lung injury pathobiology; however, the mechanisms underlying this vascular dysregulation remain unclear, thereby impairing the development of desperately needed effective therapeutics. We have shown that sphingosine-1-phosphate (S1P) and 2-amino-2-(2-[4-octylphenyl]ethyl)-1,3-propanediol (FTY720) analogues are useful tools for exploring vascular barrier regulation mechanisms. To experimentally define the effects of FTY720 regioisomers on lung endothelial cell barrier regulation. Specific barrier-regulatory receptor and kinase inhibitors were utilized to probe signaling mechanisms involved in FTY720 regioisomer-mediated human lung endothelial cell barrier responses (trans-endothelial electrical resistance, TER). Docking simulations with the S1P1 receptor were performed to further evaluate FTY720 regioisomer signaling. FTY720 regioisomers produced potent endothelial cell barrier disruption reflected by declines in TER alterations. Pharmacologic inhibition of Gi-coupled S1P receptors (S1P1, S1P2, S1P3) failed to alter FTY720 regioisomer-mediated barrier disruption; findings that were corroborated by docking simulations demonstrating FTY720 regiosomers were repelled from S1P1 docking, in contrast to strong S1P1 binding elicited by S1P. Inhibition of either the barrier-disrupting PAR-1 receptor, the VEGF receptor, Rho-kinase, MAPK, NFkB, or PI3K failed to alter FTY720 regioisomer-induced endothelial cell barrier disruption. While FTY720 regioisomers significantly increased protein phosphatase 2 (PP2A) activity, PP2A inhibitors failed to alter FTY720 regioisomer-induced endothelial cell barrier disruption. Together, these results imply a vexing model of pulmonary vascular barrier dysregulation in response to FTY720-related compounds and highlight the need for further insights into mechanisms of vascular integrity required to promote the development of novel therapeutic tools to prevent or reverse the pulmonary vascular leak central to ARDS outcomes.

Project description:OBJECTIVE:Effective therapies are needed to reverse the increased vascular permeability that characterizes acute inflammatory diseases such as acute lung injury. FTY720 is a pharmaceutical analog of the potent barrier-enhancing phospholipid, sphingosine 1-phosphate. Because both FTY720 and sphingosine 1-phosphate have properties that may limit their usefulness in patients with acute lung injury, alternative compounds are needed for therapeutic use. The objective of this study is to characterize the effects of FTY720 (S)-phosphonate, a novel analog of FTY720-phosphate, on variables of pulmonary vascular permeability in vitro and alveolar-capillary permeability in vivo. SETTING:University-affiliated research institute. SUBJECTS:Cultured human pulmonary endothelial cells; C57BL/6 mice. INTERVENTIONS:Endothelial cells were stimulated with sphingosine 1-phosphate receptor 1 agonists to determine effects on sphingosine 1-phosphate receptor 1 expression. Acute lung injury was induced in C57BL/6 mice with bleomycin to assess effects of sphingosine 1-phosphate receptor 1 agonists. MEASUREMENTS AND MAIN RESULTS:FTY720 (S)-phosphonate potently increases human pulmonary endothelial cell barrier function in vitro as measured by transendothelial electrical resistance. Reduction of sphingosine 1-phosphate receptor 1 with small interference RNA significantly attenuates this transendothelial electrical resistance elevation. FTY720 (S)-phosphonate maintains endothelial sphingosine 1-phosphate receptor 1 protein expression in contrast to greater than 50% reduction after incubation with sphingosine 1-phosphate, FTY720, or other sphingosine 1-phosphate receptor 1 agonists. FTY720 (S)-phosphonate does not induce ?-arrestin recruitment, sphingosine 1-phosphate receptor 1 ubiquitination, and proteosomal degradation that occur after other agonists. Intraperitoneal administration of FTY720 (S)-phosphonate every other day for 1 week in normal or bleomycin-injured mice maintains significantly higher lung sphingosine 1-phosphate receptor 1 expression compared with FTY720. FTY720 fails to protect against bleomycin-induced acute lung injury in mice, while FTY720 (S)-phosphonate significantly decreases lung leak and inflammation. CONCLUSION:FTY720 (S)-phosphonate is a promising barrier-promoting agent that effectively maintains sphingosine 1-phosphate receptor 1 levels and improves outcomes in the bleomycin model of acute lung injury.

Dataset Information

Pharmacological pre- and post-conditioning with the sphingosine-1-phosphate receptor modulator FTY720 after myocardial ischaemia-reperfusion.

Background and purpose

Experimental approach

Key results

Conclusions and implications

Publications

Pharmacological pre- and post-conditioning with the sphingosine-1-phosphate receptor modulator FTY720 after myocardial ischaemia-reperfusion.

Similar Datasets

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