sphingosine-1-phosphate and Brain-Ischemia

Sphingosine 1-phosphate (S1P) is an important lipid biomolecule that exerts pleiotropic cellular actions as it binds to and activates its five G-protein-coupled receptors, S1P

Topics: Animals; Brain Damage, Chronic; Brain Ischemia; Clinical Trials as Topic; Disease Models, Animal; Drug Evaluation, Preclinical; Fingolimod Hydrochloride; Humans; Infarction, Middle Cerebral Artery; Inflammation; Ischemic Stroke; Lysophospholipids; Neovascularization, Physiologic; Nerve Tissue Proteins; Neuroprotective Agents; Phosphotransferases (Alcohol Group Acceptor); Rats; Signal Transduction; Sphingosine; Sphingosine-1-Phosphate Receptors

Finding novel and effective drugs for the treatment of ischemic stroke is warranted because there is not a definitive treatment for this prevalent disease. Due to the relevance between the sphingosine 1-phosphate (S1P) receptor and several neurological diseases including ischemic stroke, it seems that fingolimod (FTY720), as an agonist of S1P receptor, can be a useful therapeutic strategy in these patients. FTY720 is the first oral drug approved by the US food and drug administration for the treatment of multiple sclerosis. Three important mechanisms for neuroprotective effects of FTY720 have been described. First, the functional antagonistic mechanism that is associated with lymphopenia and reduced lymphocytic inflammation. This effect results from the down-regulation and degradation of lymphocytes' S1P receptors, which inhibits lymph node lymphocytes from entering the bloodstream. Second, a functional agonistic activity that is mediated through direct effects via targeting S1P receptors on the membrane of various cells including neurons, microglia, oligodendrocytes, astrocytes, and endothelial cells of blood vessels in the central nervous system (CNS), and the third, receptor-independent mechanisms that are displayed by binding to specific cellular proteins that modulate intracellular signaling pathways or affect epigenetic transcriptions. Therefore, we review these mechanisms in more detail and describe the animal model and in clinical trial studies that support these three mechanisms for the neuroprotective action of FTY720 in ischemic stroke.

Topics: Animals; Brain Ischemia; Endothelial Cells; Fingolimod Hydrochloride; Humans; Immunosuppressive Agents; Ischemic Stroke; Lysophospholipids; Propylene Glycols; Receptors, Lysosphingolipid; Sphingosine; Stroke

Cardiovascular diseases like stroke cause changes to sphingolipid mediators like sphingosine 1-phosphate (S1P) or its ceramide analogs, which bear the potential to either alleviate or exacerbate the neurological damage. Therefore, the precise identification of alterations within the sphingolipidome during ischemic stroke (IS) and hemorrhagic transformation (HT) harbors a putative therapeutic potential to orchestrate local and systemic immunomodulatory processes. Due to the scarcity of research in this field, we aimed to characterize the sphingolipidome in IS and HT.. C57BL/6 mice underwent middle cerebral artery occlusion (MCAO) and specimens of the peri-infarct tissue were taken for sphingolipid profiling.. Ischemic stroke resulted in reduced S1P whilst ceramides were elevated six hours post ischemia onset. However, these differences were nearly revoked at 24 hours post ischemia onset. Moreover, the topmost S1P and ceramide levels were linked to the presence of HT after MCAO. In this study we show the characterization of the sphingolipidomic landscape of the peri-infarct tissue after ischemic stroke and HT. Especially, highest values of S1P, C 18 lactosylceramide, C 18 glucosylceramide, and C 24:1 ceramide were nearly entirely expressed by mice with HT.. Our results warrant further investigations into the immunomodulatory consequences of altered sphingolipid species for the development of HT after IS.

Topics: Animals; Brain Ischemia; Ceramides; Disease Models, Animal; Infarction, Middle Cerebral Artery; Ischemic Stroke; Mice; Mice, Inbred C57BL; Sphingolipids; Stroke

The aim of this study was to examine whether sphingosine-1-phosphate (S1P) levels in patients with acute stroke are associated with stroke severity and outcome.. In a prospective stroke cohort (MARK-STROKE), 374 patients with acute ischemic stroke or transient ischemic attack were enrolled (mean age: 67.9±13.0 years, sex: 64.7% male), and serum-S1P at admission was analyzed with tandem mass spectrometry. In addition to cross-sectional analyses, 79 adverse events (death, stroke, myocardial infarction, rehospitalization) were recorded in 270 patients during follow-up. Regression analyses were adjusted for age, sex, low-density lipoprotein cholesterol, and vascular risk factors. Results were validated in an independent stroke cohort with 219 patients with acute ischemic stroke (CIRCULAS).. Low serum-S1P was associated with higher National Institutes of Health Stroke Scale score at admission and with anterior circulation nonlacunar infarcts determined by multivariate regression analyses. During a follow-up of 294±170 days, patients with S1P in the lowest tertile (<1.33 µmol/L) had more adverse events (Kaplan-Meier analysis,. Our findings imply a detrimental role of low S1P levels in acute stroke and therefore underpin the therapeutic potential of S1P-mimics.

Topics: Aged; Aged, 80 and over; Biomarkers; Brain Ischemia; Female; Humans; Ischemic Stroke; Lysophospholipids; Male; Middle Aged; Prognosis; Sphingosine

Sphingosine 1-phosphate (S1P) is a major bioactive lipid mediator in the vascular and immune system. Here, we have shown that inhibition of S1P signaling prevents blood-brain barrier (BBB) dysfunction after ischemia both in vitro and in vivo. In the in vitro BBB models, oxygen-glucose deprivation and reoxygenation (OGD/R) enhanced the expression of an S1P synthesizing enzyme (Sphk1) and S1P transporters (Abca1, Spns2), increasing S1P in culture media. Inhibitors of Sphk1 (SKI-II) or Abca1 (probucol) attenuated the decrease in transendothelial electrical resistance and the increase in permeability caused by OGD/R. In the middle cerebral artery occlusion and reperfusion (MCAO/R) model of mice, probucol administration after MCAO operation reduced the infarction area and vascular leakage, preserving the integrity of tight junction proteins. Furthermore, MCAO/R caused activation of STAT3, a downstream mediator of S1P signaling, which was suppressed by postoperative probucol administration. Accordingly, S1P activated STAT3, both in cultured vascular endothelial cells and pericytes, and STAT3 signaling inhibitor (Stattic) protected BBB dysfunction in OGD/R-treated in vitro BBB models. These results suggest that inhibition of S1P signaling is a strategy to treat BBB impairment after cerebral ischemia and highlight the potential alternative use of probucol, a classical anti-hyperlipidemic drug, for emergency treatment of stroke.

Topics: Animals; Biological Transport; Blood-Brain Barrier; Brain Ischemia; Endothelial Cells; Glucose; Infarction, Middle Cerebral Artery; Lysophospholipids; Mice; Pericytes; Rats, Wistar; Reperfusion Injury; Sphingosine; Stroke

Sphingosine kinase 1 (Sphk1) and the signaling molecule sphingosine-1-phosphate (S1P) are known to be key regulators of a variety of important biological processes, such as neovascularization. Nitric oxide (NO) is also known to play a role in vasoactive properties, whether Sphk1/S1P signaling is able to alter angiogenesis in the context of cerebral ischemia-reperfusion injury (IRI), and whether such activity is linked with NO production, however, remains uncertain.. We used immunofluorescence to detect the expression of Sphk1 and NOS in cerebral epithelial cells (EC) after IR or oxygen-glucose deprivation (OGDR). Western blotting was used to detect the Sphk1 and NOS protein levels in brain tissues or HBMECs. Adenovirus transfection was used to inhibit Sphk1 and NOS. An NO kit was used to detect NO contents in brain tissues and epithelial cells. Tube formation assays were conducted to measure angiogenesis.. We determined that EC used in a model of cerebral IRI expressed Sphk1, and that inhibiting this expression led to decreased expression of two isoforms of NO synthase (eNOS and iNOS), as well as to decrease neovascularization density and NO production following injury. In HBMECs, knocking down Sphk1 markedly reduced NO production owing to reduced eNOS activity, and inhibiting eNOS directly similarly decreased NO production in a manner which could be reversed via exogenously treating cells with S1P. We further found that knocking down Sphk1 reduced HBMEC eNOS expression, in addition to decreasing the adhesion, migration, and tube formation abilities of these cells under OGDR conditions.. Based on these results, we therefore postulate that Sphk1/S1P signaling is able to mediate angiogenesis following cerebral IRI via the regulation of eNOS activity and NO production. As such, targeting these pathways may potentially represent a novel means of improving patient prognosis in those suffering from cerebral IRI.

Topics: Animals; Brain Ischemia; Cells, Cultured; Humans; Lysophospholipids; Male; Neovascularization, Pathologic; Nitric Oxide; Nitric Oxide Synthase Type II; Phosphotransferases (Alcohol Group Acceptor); Rats; Rats, Wistar; Reperfusion Injury; Sphingosine

There is thought to be a strong relationship between sphingosine-1-phosphate (S1P) signaling and pathophysiolosy of cerebral ischemia. We examined the change of expression and distribution of S1P receptors (S1PRs) and sphingosine kinases (SphKs) after cerebral ischemia in male C57BL6/J mice using immunohistochemical analysis at 1, 5, 14, and 28 days after 30 min of transient middle cerebral artery occlusion (tMCAO). S1PR1, 3, and 5 were transiently induced in the cells, which were morphologically similar to neurons in the peri-infarct lesion with a peak seen at 1 day after tMCAO (p < 0.01 vs. sham control). S1PR2 appeared in the inner layer of vessels in the ischemic core (p < 0.01 vs. sham control) and the peri-infarct lesion (p < 0.01 vs. sham control) at the acute phase after tMCAO. However, SphK1 was strongly induced at 1 and 5 days after tMCAO (p < 0.01 vs. sham control) in the peri-infarct lesion, whereas SphK2 expression did not change. Western blot analysis at 1 and 5 days after 30 min of tMCAO revealed that the expression of S1PRs were transiently enhanced at the acute phase, which was consistent with the immunohistochemical results. Double immunofluorescent analysis revealed S1PR2/NG2- and S1PR2/CD31-, S1PR3/CD31-, and S1PR5/CD31-double positive cells in the peri-infarct lesion 1 day after tMCAO. The present results suggest that S1PRs and SphK1 may be important therapeutic targets for rescuing the peri-infarct lesion.

Topics: Animals; Brain Ischemia; Disease Models, Animal; Infarction, Middle Cerebral Artery; Lysophospholipids; Male; Mice; Mice, Inbred C57BL; Neurons; Phosphotransferases (Alcohol Group Acceptor); Receptors, Lysosphingolipid; Signal Transduction; Sphingosine; Sphingosine-1-Phosphate Receptors; Transcriptional Activation

Brain imaging in stroke diagnostics is a powerful tool, but one that can fail in more challenging cases, and one that is not particularly useful in identifying transient ischaemic attacks (TIAs). Thus, new reliable blood biomarkers of cerebral ischaemia are constantly sought.. We studied the potential usefulness of sphingolipids (SFs) as biomarkers of acute ischaemic stroke and TIA.. Levels of individual ceramide species and sphingosine-1-phosphate (Sph-1-P) in blood serum of patients with acute ischaemic stroke, TIA, and age-matched neurological patients without cerebral ischaemia, were assessed by tandem mass spectrometry liquid chromatography (LC- MS / MS).. We found significant increases of several sphingolipid levels, with particularly strong elevations of Cer-C20:0 in patients with acute stroke. Cer-C24:1 was the only ceramide species to decrease as a result of acute stroke. Moreover, its levels inversely correlated with the number of days after stroke onset, suggesting that Cer-C24:1 is an independent parameter related to the course of stroke. To increase the sensitivity of sphingolipid-based tests in stroke diagnostics, we calculated the values of ratios of Sph-1-P / individual ceramide species and Cer-C24:1 individual ceramide species. We found several ratios significantly changed in stroke patients. Two ratios, Sph-1-P / Cer-C24:1 and Cer-C24:0 / Cer-C24:1, presented especially strong increments in patients with acute stroke. Moreover, Sph-1-P / Cer-C24:1 values were augmented in TIA patients.. Serum SFs could be good candidates to be ischaemic stroke biomarkers. We have identified two SF ratios, Sph-1-P / Cer-C24:1 and Cer-C24:0 / Cer-C24:1, with strong diagnostic potential in ischaemic stroke. We found Sph-1-P / Cer-C24:1 ratio to be possibly useful in TIA diagnostics, also in the long term after ischaemic incidence.

Topics: Biomarkers; Brain Ischemia; Ceramides; Humans; Lysophospholipids; Sphingosine; Stroke

Topics: Animals; Brain; Brain Ischemia; Fingolimod Hydrochloride; Hemoglobins; Hemorrhage; Lymphocytes; Lysophospholipids; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Myeloid Cells; Reperfusion Injury; RNA, Messenger; Sphingosine; Sphingosine 1 Phosphate Receptor Modulators; Sphingosine-1-Phosphate Receptors; Stroke; T-Lymphocytes; Thrombocytopenia; Up-Regulation

Sphingolipids (SPLs) have been proposed as potential therapeutic targets for strokes, but no reports have ever profiled the changes of the entire range of SPLs after a stroke. This study applied sphingolipidomic methods to investigate the temporal and individual changes in the sphingolipidome including the effect of atorvastatin after ischemic brain injury. We conducted sphingolipidomic profiling of mouse brain tissue by liquid chromatography-electrospray ionization tandem mass spectrometry at 3 h and 24 h after 1 h of middle cerebral artery occlusion (MCAO), and SPL levels were compared with those of the

Topics: Animals; Atorvastatin; Brain; Brain Injuries; Brain Ischemia; Ceramides; Chromatography, High Pressure Liquid; Disease Models, Animal; Humans; Infarction, Middle Cerebral Artery; Lipidomics; Lysophospholipids; Mice; Sphingolipids; Sphingosine; Stroke; Tandem Mass Spectrometry

Topics: Animals; Brain; Brain Ischemia; Enzyme Inhibitors; Hemodynamics; Humans; Lysophospholipids; Male; Mice; Microscopy; Neuroprotection; Neuroprotective Agents; Oxygen; Phosphotransferases (Alcohol Group Acceptor); Photoacoustic Techniques; Sphingosine; Stroke

Microglial activation is one of the causative factors of neuroinflammation in cerebral ischemia/reperfusion (IR). Sphingosine kinase 1 (Sphk1), a key enzyme responsible for phosphorylating sphingosine into sphingosine-1-phosphate (S1P), plays an important role in the regulation of proinflammatory cytokines in activated microglia. Recent research demonstrated that S1P increased IL-17A-secretion and then worsened CNS (central nervous system) inflammation. Thus, in the present study, we sought to use microglial cells as the object of study to discuss the molecular mechanisms in Sphk1/S1P-regulated IL-17A-secretion in IR.. We used immunofluorescence and confocal microscopy to detect whether Sphk1 is expressed in microglia after cerebral IR or oxygen-glucose deprivation (OGDR). Western blot analysis was used to estimate the total Sphk1 protein level at different time points after OGDR. To detect cytokine secretion in microglial supernatants in response to OGDR, we measured the concentration of IL-17A in the culture supernatants using an enzyme-linked immunosorbent assay (ELISA). To evaluate whether microglia subjected to OGDR exhibited neuronal injury, we used a commercially available terminal transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) kit to detect apoptotic neurons.. Sphk1 was expressed in microglia in response to cerebral IR or OGDR at appointed time. Pre-injection with PF-543, an inhibitor of Sphk1, before IR clearly reduced the expression of Sphk1 in microglia relative to brain IR alone. The number of TUNEL-positive neurons was also decreased in the PF-543-pretreated animals before IR compared to the animals with IR alone. When S1P was administered in OGDR microglia, IL-17A expression and neuronal apoptosis were increased compared to OGDR alone and the administration of S1P alone. ELISA further confirmed the above results. Moreover, the inhibition of Sphk1 by siRNA reduced IL-17A production and relieved neuronal apoptosis in OGDR microglia.. These results indicated that Sphk1/S1P regulates the expression of IL-17A in activated microglia, inducing neuronal apoptosis in cerebral ischemia/reperfusion. The microglial Sphk1/S1P pathway may thus be a potential therapeutic target to control neuroinflammation in brain IR.

Topics: Animals; Apoptosis; Brain; Brain Ischemia; Cells, Cultured; Glucose; Hypoxia, Brain; Infarction, Middle Cerebral Artery; Interleukin-17; Lysophospholipids; Male; Methanol; Microglia; Neurons; Phosphotransferases (Alcohol Group Acceptor); Pyrrolidines; Rats, Sprague-Dawley; Reperfusion Injury; RNA, Small Interfering; Sphingosine; Sulfones

Initial and recurrent stroke produces central nervous system (CNS) damage, involving neuroinflammation. Receptor-mediated S1P signaling can influence neuroinflammation and has been implicated in cerebral ischemia through effects on the immune system. However, S1P-mediated events also occur within the brain itself where its roles during stroke have been less well studied. Here we investigated the involvement of S1P signaling in initial and recurrent stroke by using a transient middle cerebral artery occlusion/reperfusion (M/R) model combined with analyses of S1P signaling. Gene expression for S1P receptors and involved enzymes was altered during M/R, supporting changes in S1P signaling. Direct S1P microinjection into the normal CNS induced neuroglial activation, implicating S1P-initiated neuroinflammatory responses that resembled CNS changes seen during initial M/R challenge. Moreover, S1P microinjection combined with M/R potentiated brain damage, approximating a model for recurrent stroke dependent on S1P and suggesting that reduction in S1P signaling could ameliorate stroke damage. Delivery of FTY720 that removes S1P signaling with chronic exposure reduced damage in both initial and S1P-potentiated M/R-challenged brain, while reducing stroke markers like TNF-α. These results implicate direct S1P CNS signaling in the etiology of initial and recurrent stroke that can be therapeutically accessed by S1P modulators acting within the brain.

Topics: Animals; Blood-Brain Barrier; Brain Ischemia; Fingolimod Hydrochloride; Lysophospholipids; Male; Mice; Mice, Inbred ICR; Microinjections; Neuroglia; Phosphotransferases (Alcohol Group Acceptor); Receptors, Lysosphingolipid; Signal Transduction; Sphingosine; Stroke; Tumor Necrosis Factor-alpha

Sphingosine-1-phosphate (S1P) has been demonstrated to be an important regulator of cell death and survival. Although it has been suggested that the sphingolipid may act as a neuroprotector in the cell apoptosis induced by traumatic brain injury, the mechanisms involved in this action are unknown. In this study, the relationship between S1P and neuroprotective effect was studied in an in vitro model of ischemia, maintaining SH-SY5Y human neuroblastoma cells under oxygen-glucose deprivation (OGD). When cells were treated with 1 microM S1P simultaneously with OGD and recovery, cell viability increases in a dose-response manner. S1P treatment reduces significantly both necrosis and apoptosis cell death. On the other hand, the treatment with specific PKC epsilon (V1-2), prevents S1P protective effect of OGD/recovery-induced necrosis. Moreover, S1P treatment provokes the translocation of PKC epsilon to the mitochondria. From these results, it is reasonable to assume that S1P protection from necrosis is mediated by PKC epsilon. We also studied the action of S1P on mitochondrial inner membrane potential and mitochondrial Ca(2+) levels during ischemia. In this regard, we must point out that S1P treatment reduces the OGD-induced membrane depolarization and also reduces the increase of Ca(2+) in mitochondria during OGD. Results also indicate that mitochondria from OGD treated cells have significantly less ability to resist swelling on Ca(2+) loading than those obtained in presence of oxygen and glucose. Nevertheless, when S1P was added, this resistance increases considerably. These findings suggest that S1P may have a potential role as a neuroprotective agent in brain injury.

Topics: Biological Transport, Active; Brain Ischemia; Calcium; Cell Death; Cell Hypoxia; Cell Line, Tumor; Cell Survival; Cytosol; Glucose; Humans; Lysophospholipids; Membrane Potential, Mitochondrial; Mitochondria; Mitochondrial Swelling; Necrosis; Oxygen; Protein Kinase C-epsilon; Sphingosine; Time Factors

Cerebral ischemia is accompanied by fulminant cellular and humoral inflammatory changes in the brain which contribute to lesion development after stroke. A tight interplay between the brain and the peripheral immune system leads to a biphasic immune response to stroke consisting of an early activation of peripheral immune cells with massive production of proinflammatory cytokines followed by a systemic immunosuppression within days of cerebral ischemia that is characterized by massive immune cell loss in spleen and thymus. Recent work has documented the importance of T lymphocytes in the early exacerbation of ischemic injury. The lipid signaling mediator sphingosine 1-phosphate-derived stable analog FTY720 (fingolimod) acts as an immunosuppressant and induces lymphopenia by preventing the egress of lymphocytes, especially T cells, from lymph nodes. We found that treatment with FTY720 (1mg/kg) reduced lesion size and improved neurological function after experimental stroke in mice, decreased the numbers of infiltrating neutrophils, activated microglia/macrophages in the ischemic lesion and reduced immunohistochemical features of apoptotic cell death in the lesion.

Topics: Active Transport, Cell Nucleus; Animals; Apoptosis; Apoptosis Inducing Factor; Blood-Brain Barrier; Brain; Brain Ischemia; Fingolimod Hydrochloride; Immunosuppressive Agents; Lysophospholipids; Macrophages; Male; Mice; Mice, Inbred C57BL; Microglia; Neuroprotective Agents; Neutrophils; Propylene Glycols; Sphingosine

We have previously shown that the sphingosine 1-phosphate (S1P)/S1P receptor-1 (S1P(1)R) axis contributes to the migration of transplanted neural progenitor cells (NPCs) toward areas of spinal cord injury. In the current study, we examined a strategy to increase endogenous NPC migration toward the injured central nervous system to modify S1PR.. S1P concentration in the ischemic brain was measured in a mouse thrombosis model of the middle cerebral artery. NPC migration in vitro was assessed by a Boyden chamber assay. Endogenous NPC migration toward the insult was evaluated after ventricular administration of the S1P(2)R antagonist JTE-013.. The concentration of S1P in the brain was increased after ischemia and was maximal 14 days after the insult. The increase in S1P in the infarcted brain was primarily caused by accumulation of microglia at the insult. Mouse NPCs mainly expressed S1P(1)R and S1P(2)R as S1PRs, and S1P significantly induced the migration of NPCs in vitro through activation of S1P(1)R. However, an S1P(1)R agonist failed to have any synergistic effect on S1P-mediated NPC migration, whereas pharmacologic or genetic inhibition of S1P(2)R by JTE-013 or short hairpin RNA expression enhanced S1P-mediated NPC migration but did not affect proliferation and differentiation. Interestingly, administration of JTE-013 into a brain ventricle significantly enhanced endogenous NPC migration toward the area of ischemia.. Our findings suggest that S1P is a chemoattractant for NPCs released from an infarcted area and regulation of S1P(2)R function further enhances the migration of NPCs toward a brain infarction.

Topics: Animals; Brain; Brain Ischemia; Cell Differentiation; Cell Division; Cell Movement; Cells, Cultured; Cerebral Infarction; Chemotaxis; Drug Evaluation, Preclinical; Embryonic Stem Cells; Female; Injections, Intraventricular; Lymphocyte Subsets; Lysophospholipids; Mice; Mice, Inbred C57BL; Microglia; Pyrazoles; Pyridines; Receptors, Lysosphingolipid; RNA Interference; RNA, Small Interfering; Sphingosine; Sphingosine-1-Phosphate Receptors