S1P1 Agonist Research Articles

Exploration of Tetrahydroisoquinoline- and Benzo[c]azepine-Based Sphingosine 1-Phosphate Receptor 1 Agonists for the Treatment of Multiple Sclerosis.

Because of the wide use of Fingolimod for the treatment of multiple sclerosis (MS) and its cardiovascular side effects such as bradycardia, second-generation sphingosine 1-phosphate receptor 1 (S1P1) agonist drugs for MS have been developed and approved by FDA. The issue of bradycardia is still present with the new drugs, however, which necessitates further exploration of S1P1 agonists with improved safety profiles for next-generation MS drugs. Herein, we report a tetrahydroisoquinoline or a benzo[c]azepine core-based S1P1 agonists such as 32 and 60 after systematic examination of hydrophilic groups and cores. We investigated the binding modes of our representative compounds and their molecular interactions with S1P1 employing recent S1P1 cryo-EM structures. Also, favorable ADME properties of our compounds were shown. Furthermore, in vivo efficacy of our compounds was clearly demonstrated with PLC and EAE studies. Also, the preliminary in vitro cardiovascular safety of our compound was verified with human iPSC-derived cardiomyocytes.

Opposing Roles of Sphingosine 1-Phosphate Receptors 1 and 2 in Fat Deposition and Glucose Tolerance in Obese Male Mice.

Sphingosine 1-phosphate (S1P) is a bioactive sphingolipid that regulates fundamental cellular processes such as proliferation, migration, apoptosis, and differentiation through 5 cognate G protein-coupled receptors (S1P1-S1P5). We previously demonstrated that blockade of S1P2 signaling in S1P2-deficient mice attenuates high-fat diet-induced adipocyte hypertrophy and glucose intolerance and an S1P2-specific antagonist JTE-013 inhibits, whereas an S1P1/S1P3 dual antagonist (VPC23019) activates, adipogenic differentiation of preadipocytes. Based on those observations, this study examined whether an S1P1-specific agonist, SEW-2871, VPC23019, or their combination acts on obesity and glucose intolerance in leptin-deficient ob/ob mice. The oral administration of SEW-2871 or JTE-013 induced significant reductions in body/epididymal fat weight gains and epididymal/inguinal fat adipocyte sizes and improved glucose intolerance and adipocyte inflammation in ob/ob mice but not in their control C57BL/6J mice. Both SEW-2871 and JTE-013 decreased messenger RNA levels of tumor necrosis factor-α and CD11c, whereas they increased those of CD206 and adiponectin in the epididymal fats isolated from ob/ob mice with no changes in the levels of peroxisome proliferator activated receptor γ and its regulated genes. By contrast, VPC23019 did not cause any such alterations but counteracted with all those SEW-2871 actions in these mice. In conclusion, the S1P1 agonist SEW-2871 acted like the S1P2 antagonist JTE-013 to reduce body/epididymal fats and improve glucose tolerance in obese mice. Therefore, this study raises the possibility that endogenous S1P could promote obesity/type 2 diabetes through the S1P2, whereas exogenous S1P could act against them through the S1P1.

Promising Cerebral Blood Flow Enhancers in Acute Ischemic Stroke.

Ischemic stroke presents a major global economic and public health burden. Although recent advances in available endovascular therapies show improved functional outcome, a good number of stroke patients are either ineligible or do not have access to these treatments. Also, robust collateral flow during acute ischemic stroke independently predicts the success of endovascular therapies and the outcome of stroke. Hence, adjunctive therapies for cerebral blood flow (CBF) enhancement are urgently needed. A very clear overview of the pial collaterals and the role of genetics are presented in this review. We review available evidence and advancement for potential therapies aimed at improving CBF during acute ischemic stroke. We identified heme-free soluble guanylate cyclase activators; Sanguinate, remote ischemic perconditioning; Fasudil, S1P agonists; and stimulation of the sphenopalatine ganglion as promising potential CBF-enhancing therapeutics requiring further investigation. Additionally, we outline and discuss the critical steps required to advance research strategies for clinically translatable CBF-enhancing agents in the context of acute ischemic stroke models.

Drug Repurposing for Identification of S1P1 Agonists with Potential Application in Multiple Sclerosis Using In Silico Drug Design Approaches.

Purpose: Drug repurposing is an approach successfully used for discovery of new therapeutic applications for the existing drugs. The current study was aimed to use the combination of in silico methods to identify FDA-approved drugs with possible S1P1 agonistic activity useful in multiple sclerosis (MS). Methods: For this, a 3D-QSAR model for the known 21 S1P1 agonists were generated based on 3D-QSAR approach and used to predict the possible S1P1 agonistic activity of FDA-approved drugs. Then, the selected compounds were screened by docking into S1P1 and S1P3 receptors to select the S1P1 potent and selective compounds. Further evaluation was carried out by molecular dynamics (MD) simulation studies where the S1P1 binding energies of selected compounds were calculated. Results: The analyses resulted in identification of cobicistat, benzonatate and brigatinib as the selective and potent S1P1 agonists with the binding energies of -85.93, -69.77 and -67.44 kcal. mol-1, calculated using MM-GBSA algorithm based on 50 ns MD simulation trajectories. These values are better than that of siponimod (-59.35 kcal mol-1), an FDA approved S1P1 agonist indicated for MS treatment. Furthermore, similarity network analysis revealed that cobicistat and brigatinib are the most structurally favorable compounds to interact with S1P1. Conclusion: The findings in this study revealed that cobicistat and brigatinib can be evaluated in experimental studies as potential S1P1 agonist candidates useful in the treatment of MS.

Deconstructing the Pharmacological Contribution of Sphingosine-1 Phosphate Receptors to Mouse Models of Multiple Sclerosis Using the Species Selectivity of Ozanimod, a Dual Modulator of Human Sphingosine 1-Phosphate Receptor Subtypes 1 and 5.

Ozanimod, a sphingosine 1-phosphate (S1P) receptor modulator that binds with high affinity selectively to S1P receptor subtypes 1 (S1P1) and 5 (S1P5), is approved for the treatment of relapsing multiple sclerosis (MS) in multiple countries. Ozanimod profiling revealed a species difference in its potency for S1P5 in mouse, rat, and canine compared with that for human and monkey. Site-directed mutagenesis identified amino acid alanine at position 120 to be responsible for loss of activity for mouse, rat, and canine S1P5, and mutation back to threonine as in human/monkey S1P5 restored activity. Radioligand binding analysis performed with mouse S1P5 confirmed the potency loss is a consequence of a loss of affinity of ozanimod for mouse S1P5 and was restored with mutation of alanine 120 to threonine. Study of ozanimod in preclinical mouse models of MS can now determine the S1P receptor(s) responsible for observed efficacies with receptor engagement as measured using pharmacokinetic exposures of free drug. Hence, in the experimental autoimmune encephalomyelitis model, ozanimod exposures sufficient to engage S1P1, but not S1P5, resulted in reduced circulating lymphocytes, disease scores, and body weight loss; reduced inflammation, demyelination, and apoptotic cell counts in the spinal cord; and reduced circulating levels of the neuronal degeneration marker, neurofilament light. In the demyelinating cuprizone model, ozanimod prevented axonal degradation and myelin loss during toxin challenge but did not facilitate enhanced remyelination after intoxication. Since free drug levels in this model only engaged S1P1, we concluded that S1P1 activation is neuroprotective but does not appear to affect remyelination. SIGNIFICANCE STATEMENT: Ozanimod, a selective modulator of human sphingisone 1-phosphate receptor subtypes 1 and 5 (S1P1/5), displays reduced potency for rodent and dog S1P5 compared with human, which results from mutation of threonine to alanine at position 120. Ozanimod can thus be used as a selective S1P1 agonist in mouse models of multiple sclerosis to define efficacies driven by S1P1 but not S1P5. Based on readouts for experimental autoimmune encephalomyelitis and cuprizone intoxication, S1P1 modulation is neuroprotective, but S1P5 activity may be required for remyelination.

Abstract MP206: Cortical Bone Derived Stem Cells Modulate The Adaptive Immune Response Post-MI

Background: The inflammatory response mounted following myocardial infarction (MI) is closely coupled to myocardial wound healing processes such as angiogenesis, fibroblast maturation, and cardiomyocyte survival. A consortium of pro-reparative Tregs occupy the myocardium during ischemic injury and are essential in modulating cardiac homeostasis. However, Treg exposure to chronic, ischemic microenvironments compromises Tregs’ pro-reparative signatures and induces pathogenic remodeling of Tregs, compromising cardiac wound healing. Cortical Bone Derived Stem Cells (CBSCs) have superior engraftment capabilities compared to other stem cell types and can modulate the post-MI inflammatory response by establishing anti-inflammatory paracrine signaling dominance and the expansion of CD45+ leukocytes and CD4+ T cells residence in the MI heart. Therefore, we hypothesized CBSC cell therapy can modulate the recruitment and phenotype of Treg residence in the MI heart to permit their enhanced cardiogenic properties. Methods and Results: Animals that received intramyocardial injection of CBSCs along the infarct border zone of the permanently ligated LAD possessed smaller infarct sizes and improved cardiac function, that paralleled pro-reparative, TNFRII+ Treg expansion and repressed pathogenic TNFRI+, Treg residence 1- and 8- weeks post-MI compared to Mesenchymal Stem Cells (MSCs) or vehicle (PBS) treated animals. Similar TNFRI/II Treg dynamics were also observed in the spleen. Diphtheria toxin (DTR) mediated Treg ablation and S1P1 agonist administration, in the presence of CBSC therapy, reverted pro-reparative Treg expansion and solicited infarct size expansion and compromised cardiac function. The exposure of CBSC paracrine secretome to naïve CD4+ T cell cultures induces pro-reparative TNFRII+ Treg expansion. Paracrine profiling of CBSC secretome identifies Osteoprotegerin (OPG) enrichment and OPG depletion, via siRNA and lentivirus, compromises T cell survival signaling and pro-reparative, TNFRII+ Treg establishment both in vitro and in the MI heart. Conclusions: CBSCs can modulate the induction and preservation of pro-reparative TNFRII+ Tregs in the MI heart to solicit cardiac repair during acute and chronic ischemic injury.

ST-2191, an Anellated Bismorpholino Derivative of Oxy-Fingolimod, Shows Selective S1P1 Agonist and Functional Antagonist Potency In Vitro and In Vivo.

Sphingosine 1-phosphate (S1P) is an extensively studied signaling molecule that contributes to cell proliferation, survival, migration and other functions through binding to specific S1P receptors. The cycle of S1P1 internalization upon S1P binding and recycling to the cell surface when local S1P concentrations are low drives T cell trafficking. S1P1 modulators, such as fingolimod, disrupt this recycling by inducing persistent S1P1 internalization and receptor degradation, which results in blocked egress of T cells from the secondary lymphoid tissues. The approval of these compounds for the treatment of multiple sclerosis has placed the development of S1PR modulators in the focus of pharmacological research, mostly for autoimmune indications. Here, we report on a novel anellated bismorpholino derivative of oxy-fingolimod, named ST-2191, which exerts selective S1P1 agonist and functional antagonist potency. ST-2191 is also effective in reducing the lymphocyte number in mice, and this effect is not dependent on phosphorylation by sphingosine kinase 2 for activity. These data show that ST-2191 is a novel S1P1 modulator, but further experiments are needed to analyze the therapeutic impact of ST-2191 in animal models of autoimmune diseases.

More targeted endothelial protection

Pharmacology The bioactive lipid S1P exerts effects in diverse tissues. Unbiased agonists of the S1P receptor S1P1 trigger a reduced lymphocyte count, or lymphopenia, a useful feature when treating autoimmune diseases but an undesirable side effect when activating S1P1 in other cell types. Poirier et al. identified a G protein–biased S1P1 agonist, SAR247799, which maintained endothelial function and reduced tissue damage caused by ischemia-reperfusion injury in two different animal models. The characteristics of SAR247799 show that it is possible to target S1P1 in the endothelium without compromising immune responses. Sci. Signal. 12 , eaax8050 (2020).

Central Modulation of Selective Sphingosine-1-Phosphate Receptor 1 Ameliorates Experimental Multiple Sclerosis

Future treatments of multiple sclerosis (MS), a chronic autoimmune neurodegenerative disease of the central nervous system (CNS), aim for simultaneous early targeting of peripheral immune function and neuroinflammation. Sphingosine-1-phosphate (S1P) receptor modulators are among the most promising drugs with both “immunological” and “non-immunological” actions. Selective S1P receptor modulators have been recently approved for MS and shown clinical efficacy in its mouse model, the experimental autoimmune encephalomyelitis (EAE). Here, we investigated the anti-inflammatory/neuroprotective effects of ozanimod (RPC1063), a S1P1/5 modulator recently approved in the United States for the treatment of MS, by performing ex vivo studies in EAE brain. Electrophysiological experiments, supported by molecular and immunofluorescence analysis, revealed that ozanimod was able to dampen the EAE glutamatergic synaptic alterations, through attenuation of local inflammatory response driven by activated microglia and infiltrating T cells, the main CNS-cellular players of EAE synaptopathy. Electrophysiological studies with selective S1P1 (AUY954) and S1P5 (A971432) agonists suggested that S1P1 modulation is the main driver of the anti-excitotoxic activity mediated by ozanimod. Accordingly, in vivo intra-cerebroventricular treatment of EAE mice with AUY954 ameliorated clinical disability. Altogether these results strengthened the relevance of S1P1 agonists as immunomodulatory and neuroprotective drugs for MS therapy.

Test measuring signaling activity in live patient tumor cells to identify PI3KCA WT patients who may benefit from PI3K inhibitors.

e13000 Background: Biological factors other than PIK3CA status, such as aberrant GPCR-linked signaling, may be important to measure when identifying patients eligible for PI3K inhibitors. A new assay, the CELx PI3K test, using an impedance biosensor was developed to measure ex vivo live tumor cell response to specific S1P agonists and PI3K antagonists to diagnose breast tumors with PI3K-involved hyperactive signaling. This study set out to: 1) compare CELx PI3K test results and xenograft results using cell lines with PIK3CA mutations; and 2) assess whether PI3K-involved hyperactive S1P signaling is found in PIK3CA WT breast cancer patient tumors. Methods: A panel of 17 fresh HER2-/PIK3CA WT tumor cells from breast cancer patients and three PIK3CA mutated breast tumor cell lines were obtained. Live cell response to an S1P agonist, PI3K-α antagonist (alpelisib), PI3K-γ antagonist (IPI-549), and a pan-PI3K inhibitor (taselisib) were measured using an xCELLigence RTCA impedance biosensor. From these responses, PI3K-involved signaling was quantified and characterized as normal or abnormal using a previously determined cutpoint. For the xenograft study, 16 NSG mice were injected with HCC1954 PIK3CA mutated breast cancer cells and randomly assigned to either the control or taselisib group (10 mg/kg). Results: Four of the 17 PIK3CA WT tumor cells had abnormal levels of combined PI3K-α and PI3K-γ signaling. Only one of the three PIK3CA mutated breast tumor cell lines (BT20) had abnormal levels of PI3K-α and pan-PI3K involved signaling. The HCC1954 cell line had normal PI3K-α and abnormal pan-PI3K signaling. CAL-51 reported normal PI3K-α and pan-PI3K signaling. The normal levels of PI3K-α signaling found in the HCC1954 and CAL-51 cell lines correlated with previously reported xenograft studies that found alpelisib had no anti-tumor effect. The xenograft study reported here using HCC1954 cells found taselisib induces a significant anti-tumor effect (T/C ratio = 0.21; p = 0.009; t-test). Conclusions: A sub-set of PIK3CA WT patient breast cancer tumors had abnormal PI3K-involved signaling comparable to levels found in PI3KCA mutated cell lines. Abnormal pan-PI3K signaling and normal PI3K-α signaling in the HCC1954 cell line correlated with xenograft results. This study thus suggests that measurement of PI3K-involvement in hyperactive S1P signaling in live patient breast cancer cells may provide a means to identify breast cancer patients who may or may not benefit from treatment with PI3K inhibitors.

Non-Mitogenic Fibroblast Growth Factor 1 Enhanced Angiogenesis Following Ischemic Stroke by Regulating the Sphingosine-1-Phosphate 1 Pathway.

Ischemic strokes account for about 80% of all strokes and are associated with a high risk of mortality. Angiogenesis of brain microvascular endothelial cells may contribute to functional restoration following ischemia. Fibroblast growth factor 1 (FGF1), a member of FGF superfamily, involved in embryonic development, angiogenesis, wound healing, and neuron survival. However, the mitogenic activity of FGF1 is known to contribute to several human pathologies, thereby questioning the safety of its clinical applications. Here, we explored the effects and mechanism of action of non-mitogenic FGF1 (nmFGF1) on angiogenesis in mice after ischemia stroke and an oxygen-glucose deprivation (OGD)-induced human brain microvascular endothelial cells (HBMECs) injury model. We found that intranasal administration nmFGF1 significantly promoted angiogenesis in mice after stroke, and significantly increased the formation of matrigel tube and promoted scratch migration in a dose-dependent manner in OGD-induced HBMECs in vitro. However, the co-administration of an FGF receptor 1 (FGFR1)-specific inhibitor PD173074 significantly reversed the effects of nmFGF1 in vitro, suggesting that nmFGF1 functions via FGFR1 activation. Moreover, nmFGF1 activated sphingosine-1-phosphate receptor 1 (S1PR1, S1P1) in mice after stroke in vivo. S1P1 protein antagonist VPC23019 and agonist FTY720 were used to confirm that nmFGF1 promotes angiogenesis in vitro partially through the S1P1 pathway. OGD induced downregulation of S1P1 expression. The S1P1 antagonist VPC23019 blocked the stimulatory effects of nmFGF1, whereas the S1P1 agonist FTY720 exerted effects comparable with those of nmFGF1. Furthermore, PD173074 reversed the effect of nmFGF1 on upregulating S1P1 signaling. In conclusion, nmFGF1 enhanced angiogenesis in mice following stroke and OGD-induced HBMECs through S1P1 pathway regulation mediated via FGFR1 activation. This new discovery suggests the potential therapeutic role of nmFGF1 for the treatment of ischemic strokes.

A novel S1P1 modulator IMMH002 ameliorates psoriasis in multiple animal models

Psoriasis is characterized by abnormal proliferation of keratinocytes, as well as infiltration of immune cells into the dermis and epidermis, causing itchy, scaly and erythematous plaques of skin. The understanding of this chronic inflammatory skin disease remains unclear and all available treatments have their limitations currently. Here, we showed that IMMH002, a novel orally active S1P1 modulator, desensitized peripheral pathogenic lymphocytes to egress signal from secondary lymphoid organs and thymus. Using different psoriasis animal models, we demonstrated that IMMH002 could significantly relieve skin damage as revealed by PASI score and pathological injure evaluation. Mechanistically, IMMH002 regulated CD3+ T lymphocytes re-distribution by inducing lymphocytes’ homing, thus decreased T lymphocytes allocation in the peripheral blood and skin but increased in the thymus. Our results suggest that the novel S1P1 agonist, IMMH002, exert extraordinary capacity to rapidly modulate T lymphocytes distribution, representing a promising drug candidate for psoriasis treatment.

Sphingosine-1-phosphate receptor 2 modulates pain sensitivity by suppressing the ROS-RUNX3 pathway in a rat model of neuropathy.

Neuropathic pain correlates with a lesion or other dysfunction in the nervous system. Sphingosine-1-phosphate receptor 2 (S1P2) is expressed in the central nervous system and modulates synaptic plasticity. The present study aimed to investigate the role of S1P2 in neuropathic pain caused by chronic constriction injury (CCI). Sprague-Dawley rats were allocated into eight groups (n = 15 for each group): sham, CCI, CCI + green fluorescent protein, CCI + S1P2, CCI + Ctrl-short hairpin RNA (shRNA), CCI + S1P2 shRNA, CCI + S1P2 + CYM-5442, and CCI + S1P2 shRNA + CYM-5442. The CCI model was established via sciatic nerve ligation. S1P2 was overexpressed or knocked down by intrathecal injection of adeno-associated virus-S1P2 (AAV-S1P2) or AAV-S1P2 shRNA. The S1P1 agonist, CYM-5442 (1 mg/kg), was injected intraperitoneally after surgery. S1P2 expression, pain thresholds, apoptosis signaling, inflammation, and oxidative stress in rats were then examined. We found that sciatic nerve injury downregulated S1P2 expression in the spinal cords of rats. S1P2 overexpression enhanced pain thresholds. In contrast, S1P2 knockdown decreased pain thresholds in rats exposed to CCI. CCI and S1P2 silencing increased secretion of interleukin-1β (IL-1β), IL-6, and CCL2, whereas S1P2 overexpression decreased. S1P2 impeded CCI-induced reactive oxygen species (ROS) production and runt-related transcription factors 3 (RUNX3) downregulation, and S1P2 knockdown had the opposite effect. S1P2 overexpression suppressed Bax and active caspase 3 expression and promoted Bcl-2 expression, whereas loss of S1P2 reversed their expression. Additionally, S1P1 activation counteracted the effect of S1P2 on pain sensitivity. In conclusion, S1P2 is downregulated in CCI rats and may help modulate neuropathic pain via the ROS/RUNX3 pathway.

P5995A novel biased S1P1 agonist improves renal and cardiac functions in ZSF1 rats, a model of metabolic syndrome-associated Heart Failure with preserved Ejection Fraction

Abstract Background/Introduction Heart Failure with preserved ejection fraction (HFpEF) is a major cause of death worldwide with currently no approved treatment. Diastolic dysfunction, dyspnea, intolerance to effort, high cardiac filling pressure, and lung congestion coexist with normal ejection fraction in this clinical syndrome. Ageing, obesity, type 2 diabetes, hypertension and renal dysfunction are the main comorbidities found in this heterogeneous group of patients. Microvascular endothelial dysfunction, driven by these risk factors, may be a common link with other aspects of the HFpEF pathogenesis that include oxidative stress, inflammation, cardiomyocyte stiffness/hypertrophy, and myofibroblast accumulation. Sphingosine-1-phosphate type-1 receptor (S1P1), a G protein–coupled receptor highly expressed in endothelial cells, regulates vascular integrity, vascular development and immune cell trafficking. Compound A is a novel G protein-biased S1P1 agonist that lacks functional antagonism and has endothelial-protective properties. Purpose S1P1 activation could promote phosphorylation of endothelial nitric oxide synthase, restoration of endothelial structure and function, and thus diminish cardiac and vascular stiffness, hypertrophy and fibrosis. The aim of this study was to investigate if compound A could improve renal and cardiac functions in a rat model of HFpEF with metabolic syndrome. Methods 65-week-old obese ZSF1 rats were fed a chow diet containing compound A (8 mg/kg/day) or no compound for 4 weeks. Lean ZSF1 and Wistar rats were included in the study as control groups. Urinary protein/creatinine ratio was measured as an index of glomerular injury. Cardiac hypertrophy and function were assessed by two-dimensional and Doppler echocardiography. Total cardiac and atrial weights and pulmonary edema were assessed. Results The obese ZSF1 rat was confirmed as a relevant model of HFpEF with advanced renal dysfunction. These rats showed severe glomerular filtration impairment, left ventricular and atrial hypertrophy and pulmonary edema. Cardiac systolic function, cardiac output and chamber volumes were preserved, diastolic function was impaired, and left ventricular posterior walls and septal thicknesses were increased compared to control groups. Four weeks of compound A treatment reduced urinary protein/creatinine ratio, blunted cardiac and atrial hypertrophy, and partially restored diastolic function. Circulating lymphocytes were not reduced by compound A, confirming that these pharmacological effects were not associated with S1P1 desensitization. Conclusion Compound A, a novel S1P1 agonist with endothelial properties, improves cardiac and renal functions in a rat model of metabolic syndrome-associated HFpEF. Sustained S1P1 activation with compound A may be a promising strategy for HFpEF treatment.

ASP1126, a Novel Sphingosine-1-Phosphate–Selective Agonist With a Favorable Safety Profile, Prolongs Allograft Survival in Rats and Nonhuman Primates in Combination With Tacrolimus With a Broad Safety Margin for Bradycardia

Sphingosine-1-phosphate (S1P) is a biologically active sphingolipid that acts through the members of a family of 5 G protein–coupled receptors (S1P1 to S1P5). Among these, S1P1 is a major regulator of lymphocyte trafficking. Fingolimod, whose active metabolite, fingolimod phosphate, acts as a nonselective S1P-receptor agonist, exerts its immunomodulatory effect, at least in part, by regulating lymphocyte trafficking via downregulation of S1P1 expression on lymphocytes. Here, we describe the pharmacologic profile of a novel S1P1 agonist, ASP1126. ASP1126 preferentially activated S1P1 compared to S1P3 in rat and human guanosine-5'-(γ-thio)-triphosphate (GTPγS) assays. Oral single administration of ASP1126 decreased the number of peripheral lymphocytes and repeated dosing showed a cumulative effect on lymphopenia in both rats and monkeys. ASP1126 prolonged allograft survival in a rat heterotopic heart transplantation model in combination with a subtherapeutic dose of tacrolimus that was independent of drug-drug interactions. In addition, in nonhuman primate (NHP) renal transplantation, pretreatment with ASP1126 reduced not only the number of naive T cells and central memory T cells but also effector memory T cells in the peripheral blood, all of which could contribute to acute graft rejection and prolonged allograft survival in combination with tacrolimus. Further, we confirmed that ASP1126 has a broad ranging safety margin with respect to its effect on lung weight in rats and bradycardia in NHPs, which were the adverse events found in clinical studies of fingolimod. ASP1126 with improved safety profile has the potential to be an adjunct therapy in combination with tacrolimus in clinical transplantation.

Sphingosine 1-phosphate induces epicardial progenitor cell differentiation into smooth muscle-like cells.

Epicardial progenitor cells (EpiCs) which are derived from the proepicardium have the potential to differentiate into coronary vascular smooth muscle cells during development. Whether sphingosine 1-phosphate (S1P), a highly hydrophobic zwitterionic lysophospholipid in signal transduction, induces the differentiation of EpiCs is unknown. In the present study, we demonstrated that S1P significantly induced the expression of smooth muscle cell specific markers α-smooth muscle actin and myosin heavy chain 11 in the EpiCs. And the smooth muscle cells differentiated from the EpiCs stimulated by S1P were further evaluated by gel contraction assay. To further confirm the major subtype of sphingosine 1-phosphate receptors (S1PRs) involved in the differentiation of EpiCs, we used the agonists and antagonists of different S1PRs. The results showed that the S1P1/S1P3 antagonist VPC23019 and the S1P2 antagonist JTE013 significantly attenuated EpiCs differentiation, while the S1P1 agonist SEW2871 and antagonist W146 did not affect EpiCs differentiation. These results collectively suggested that S1P, principally through its receptor S1P3, increases EpiCs differentiation into VSMCs and thus indicated the importance of S1P signaling in the embryonic coronary vasculature, while S1P2 plays a secondary role.

Enantioselective C2-Alkylation of Indoles through a Redox-Relay Heck Reaction of 2-Indole Triflates.

A palladium-catalyzed enantioselective redox-relay Heck reaction of 2-indole triflates and disubstituted alkenes is reported. This process combines readily available indole triflates with a variety of alkenes to afford a range of indole derivatives bearing a stereocenter adjacent to C2. Enantioselectivity is achieved through use of a simple pyridine-oxazoline ligand. Tuning the electronics of the indole, through judicious choice of N-protecting group, is required to ensure selective β-hydride elimination away from the indole core. Utility of this method is highlighted in a modular formal synthesis of an S1P1 agonist precursor developed by Merck.

CYP2J2 is the major enzyme in human liver microsomes responsible for hydroxylation of SYL-927, a novel and selective sphingosine 1-phosphate receptor 1 (S1P1 ) agonist.

SYL-927, a novel and selective S1P1 agonist, is transferred to its active phosphate for the regulation of lymphocyte recirculation. This in vitro metabolism study is to elucidate the P450-mediated oxidation pathway of SYL-927 in human liver microsomes (HLMs). The results demonstrated that the ω-1 hydroxylated metabolite SYL-927-M was formed after incubation of SYL-927 with HLMs. Recombinant human CYP1A1 and CYP2J2 can efficiently catalyse SYL-927-M formation, followed by markedly less substrate conversion with CYP1A2, CYP2C19 and CYP2D6. Inhibition studies with chemical inhibitors and antibodies suggested that arachidonic acid, the substrate of CYP2J2, and CYP2J2-specific antibody effectively inhibited the formation of SYL-927-M in HLMs whereas no significant inhibition was observed with the inhibitors for CYP1A1, CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4, demonstrating that CYP2J2 was primarily responsible for the formation of SYL-927-M.

S1P1 receptor inhibits kidney epithelial mesenchymal transition triggered by ischemia/reperfusion injury via the PI3K/Akt pathway.

Ischemia/reperfusion (I/R) is a major cause of acute kidney injury (AKI), along with delayed graft function, which can trigger chronic kidney injury by stimulating epithelial to mesenchymal transition (EMT) in the kidney canaliculus. Sphingosine 1-phosphate receptor 1 (S1P1) is a G protein-coupled receptor that is indispensable for vessel homeostasis. This study aimed to investigate the influence of S1P1 on the mechanisms underlying I/R-induced EMT in the kidney using in vivo and in vitro models. Wild-type (WT) and S1P1-overexpressing kidney canaliculus cells were subject to hypoxic conditions followed by reoxygenation in the presence or absence of FTY720-P, a potent S1P1 agonist. In vivo, bilateral arteria renalis in wild-type mice and mice with silenced S1P1 were clamped for 30 min to obtain I/R models. We found that hypoxia/reoxygenation (H/R) significantly enhanced the expressions of EMT biomarkers and down-regulated S1P1 expression in wild-type canaliculus cells. In contrast, FTY720-P treatment or overexpression of S1P1 significantly suppressed EMT in wild-type canaliculus cells. Furthermore, after 48-72 h, a significant upregulation of EMT biomarker expression was triggered by I/R in mice with silenced S1P1, while the expressions of these markers did not change in wild-type mice. A kt activity was increased with H/R-induced EMT, suggesting that the protective influence of FTY720-P was due to its inhibition of PI3K/Akt. Therefore, the results of this study provide evidence that down-regulation of S1P1 expression is essential for the generation and progression of EMT triggered by I/R. S1P1 exhibits a prominent inhibitory effect on kidney I/R-induced EMT in the kidney by affecting the PI3K/Akt pathway.

Amelioration of colitis through blocking lymphocytes entry to Peyer's patches by sphingosine-1-phosphate lyase inhibitor.

Sphingosine-1-phosphate (S1P) receptor 1, a therapeutic target of the S1P1 agonist FTY720, plays a crucial role in lymphocyte migration and is expressed in several cells including naïve T lymphocytes and endothelial cells. 2-Acetyl-4-tetrahydroxybutyl imidazole (THI), an inhibitor of S1P lyase, exhibits immunomodulatory activity through increasing the S1P concentration in the secondary lymphoid organs, but its effects on colitis remain unclear. This study aimed to clarify how THI affects colitis and migration of naïve T lymphocytes in Peyer's patches (PPs). The effect of THI on gut immunity was investigated by analyzing the dextran sulfate sodium (DSS)-induced murine colitis model, lymphocyte components in thoracic duct lymphocytes (TDLs), and microscopic movement of TDLs in PPs. 2-Acetyl-4-tetrahydroxybutyl imidazole ameliorated DSS-induced colitis histologically by causing a significant decrease in colonic lymphocyte infiltration and expression of mucosal pro-inflammatory cytokines. THI suppressed the inflow of naïve T lymphocytes into the thoracic duct. Microscopic observation of PPs in control animals revealed that many TDLs egressed to the stroma and migrated to lymph capillaries after attaching to the high endothelial venules (HEVs). THI or FTY720 treatment in recipient animals blocked lymphocyte egression from the HEVs to the stroma. This is the first study to clarify the ameliorating effects of THI on DSS-induced colitis. Microscopic observations demonstrated the involvement of HEVs in the egression of S1P-dependent gut-tropic T lymphocytes to lymph capillaries. This S1P lyase inhibitor might become a novel immunosuppressant for inflammatory bowel disease therapy by blocking infiltration of lymphocytes through HEVs into the stroma in PPs.