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BACKGROUND: Ozanimod, a high selective sphingosine 1 phosphate (S1P) receptor (S1PR) 1/5 modulator was approved by the Food and Drug Administration for the treatment of adult patients with moderately to severely active ulcerative colitis. Additional S1PR modulators are being tested in clinical development programs for both ulcerative colitis and Crohn’s disease. AIM: To provide an overview of advances in understanding S1PRs biology and summarize preclinical and clinical investigations of S1P receptor modulators in chronic inflammatory disease with special emphasis on inflammatory bowel diseases (IBD). METHODS: We performed a narrative review using PubMed and ClinicalTrials.gov. RESULTS: Through S1PRs, S1P regulates multiple cellular processes, including proliferation, migration, survival, and vascular barrier integrity. The S1PRs function of regulating lymphocyte trafficking is well known, but new functions of S1PRs expand our knowledge of S1PRs biology. Several S1PR modulators are in clinical development for both ulcerative colitis and Crohn’s disease and have shown promise in phase II and III studies with Ozanimod now being approved for ulcerative colitis. CONCLUSIONS: S1P receptor modulators constitute a novel, promising, safe, and convenient strategy for the treatment of IBD.

Pediatric-onset multiple sclerosis (POMS) is a rare neuroinflammatory and neurodegenerative disease that has a significant impact on long-term physical and cognitive patient outcomes. A small percentage of multiple sclerosis (MS) diagnoses occur before the age of 18 years. Before treatment initiation, a careful differential diagnosis and exclusion of other similar acquired demyelinating syndromes such as anti-aquaporin-4-associated neuromyelitis optica spectrum disorder (AQP4-NMOSD) and myelin oligodendrocyte glycoprotein antibody spectrum disorder (MOGSD) is warranted. The recent 2017 changes to the McDonald criteria can successfully predict up to 71% of MS diagnoses and have good specificity of 95% and sensitivity of 71%. Additional measures such as the presence of T1-weighted hypointense lesions and/or contrast-enhancing lesions significantly increase the accuracy of diagnosis. In adults, early use of disease-modifying therapies (DMTs) is instrumental to a better long-term prognosis, including lower rates of relapse and disability worsening, and numerous FDA-approved therapies for adult-onset MS are available. However, unlike their adult counterparts, the development, testing, and regulatory approval of POMS treatments have been significantly slower and hindered by logistic and/or ethical considerations. Currently, only two MS DMTs (fingolimod and teriflunomide) have been tested in large phase III trials and approved by regulatory agencies for use in POMS. First-line therapies not approved by the FDA for use in children (interferon-β and glatiramer acetate) are also commonly used and result in a significant reduction in inflammatory activity when compared with non-treated POMS patients. An increasing number of POMS patients are now treated with moderate efficacy therapies such as dimethyl fumarate and high-efficacy therapies such as natalizumab, anti-CD20 monoclonal antibodies, anti-CD52 monoclonal antibodies, and/or autologous hematopoietic stem cell transplantation. These high-efficacy DMTs generally provide additional reduction in inflammatory activity when compared with the first-line medications (up to 62% of relapse-rate reduction). Therefore, a number of phase II and III trials are currently investigating their efficacy and safety in POMS patients. In this review, we discuss potential changes in the regulatory approval process for POMS patients that are recommended for DMTs already approved for the adult MS population, including smaller sample size for pharmacokinetic/pharmacodynamic studies, MRI-centered primary outcomes, and/or inclusion of teenagers in the adult trials.

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.

Multiple sclerosis (MS) is a complex disease of the central nervous system that can cause permanent disability in young adults. A large armamentarium is available for its management and is increasing over time. Ozanimod is an oral drug belonging to the sphingosine-1-phosphate receptor (S1PR) modulator family recently approved in different countries for MS with active disease. It selectively modulates S1PR1 and S1PR5 to prevent autoreactive lymphocytes from entering the central nervous system (CNS), where they can determine inflammation and neurodegeneration. Ozanimod was tested in one Phase II and two Phase III pivotal trials and was shown to be effective and well tolerated. Moreover, further investigations, including comparative trials with other S1P modulators and MS disease-modifying drugs, are needed to better define placement in MS treatment. Furthermore, ozanimod is currently under evaluation for inflammatory bowel diseases, such as ulcerative colitis and Crohn’s disease, in international phase III studies. This article retraces the itinerary leading to the approval of ozanimod for MS treatment and its peculiarities and potentiality inside the S1PR modulator family.

Background Patients with multiple sclerosis (MS) experience relapses and sustained disability progression. Since 2004, the number of disease-modifying therapies (DMTs) for MS has grown substantially. As a result, patients, healthcare providers, and insurers are increasingly interested in comparative efficacy and safety evaluations to distinguish between treatment options, but head-to-head studies between DMTs are limited. Objective The aim of the current study was to compare efficacy and safety outcomes with the DMTs ozanimod and dimethyl fumarate (DMF) using a matching-adjusted indirect comparison (MAIC) to adjust for cross-trial differences in study design and population. Methods A systematic literature review was performed to identify clinical studies evaluating the efficacy and safety of ozanimod compared with DMF. Individual patient-level data (IPD) for ozanimod were obtained from the SUNBEAM and RADIANCE Part B trials, and aggregate-level patient data (APD) for DMF were obtained from CONFIRM and DEFINE. A MAIC is used to weight IPD to APD based on important baseline patient characteristics considered to be effect modifiers or prognostic factors in order to balance the covariate distribution to establish more homogenous trial populations. Once trial populations are determined to be sufficiently homogenous, outcomes of interest are estimated and used to generate treatment effects between the weighted IPD and APD. We used MAIC methodology to compare efficacy and safety outcomes of interest between ozanimod 1.0 mg once daily (OD) and DMF 240 mg twice daily (BID), including confirmed disability progression (CDP) at 3 and 6 months, annualized relapse rate (ARR), proportion of patients relapsed, overall adverse events (AEs), serious AEs (SAEs), and discontinuations due to AEs. Results After matching patient data, baseline patient characteristics were balanced between patients receiving ozanimod and those receiving DMF. Compared with DMF, ozanimod demonstrated significantly improved CDP at 3 months (hazard ratio 0.67; 95% confidence interval [CI] 0.53–0.86), ARR (rate ratio [RR] 0.80; 95% CI 0.67–0.97), proportion of patients relapsed (odds ratio [OR] 0.66; 95% CI 0.52–0.83), overall AEs (OR 0.11; 95% CI 0.08–0.16), SAEs (OR 0.27; 95% CI 0.19–0.39), and discontinuations (OR 0.11; 95% CI 0.07–0.17). CDP at 6 months did not differ significantly between the two agents (RR 0.89; 95% CI 0.62–1.26). Conclusions After adjustment of baseline patient characteristics, the MAIC demonstrated that the efficacy and safety of ozanimod 1.0 mg OD was superior to that of DMF 240 mg BID. Although a MAIC is less likely to produce biased estimates than a naïve or a standard indirect treatment comparison via a common comparator, limitations include potential confounding due to unobserved and thus unaccounted for baseline differences., Plain Language Summary Ozanimod and dimethyl fumarate (DMF) are disease-modifying therapies used to treat relapsing-remitting multiple sclerosis (MS). Comparative efficacy and safety evaluation is important to key patients, healthcare providers, and health insurers; however, head-to-head studies between MS therapies are limited. In this analysis, we used an indirect treatment comparison method, specifically a matching-adjusted indirect comparison (MAIC), to compare results of clinical trials of ozanimod and DMF. In this MAIC, findings suggested that ozanimod was associated with greater reductions of relapses, a lowered risk of disability progression at 3 months, and improved safety outcomes compared with DMF. Although MAICs were conducted while adjusting for important treatment-effect modifiers and/or prognostic factors, the possibility of confounding as a result of unobserved baseline differences remains. Such an issue can be resolved only by conducting a head-to-head treatment comparison in a randomized clinical trial.

Ozanimod is approved for the treatment of relapsing forms of multiple sclerosis. Absorption, metabolism, and excretion of ozanimod were investigated after a single oral dose of 1.0 mg [14C]ozanimod hydrochloride to six healthy subjects. In vitro experiments were conducted to understand the metabolic pathways and enzymes involved in the metabolism of ozanimod and its active metabolites. The total mean recovery of the administered radioactivity was ∼63%, with ∼26% and ∼37% recovered from urine and feces, respectively. Based on exposure, the major circulating components were active metabolite CC112273 and inactive metabolite RP101124, which together accounted for 50% of the circulating total radioactivity exposure, whereas ozanimod accounted for 6.7% of the total radioactive exposure. Ozanimod was extensively metabolized, with 14 metabolites identified, including two major active metabolites (CC112273 and CC1084037) and one major inactive metabolite (RP101124) in circulation. Ozanimod is metabolized by three primary pathways, including aldehyde dehydrogenase and alcohol dehydrogenase, cytochrome P450 isoforms 3A4 and 1A1, and reductive metabolism by gut microflora. The primary metabolite RP101075 is further metabolized to form major active metabolite CC112273 by monoamine oxidase B, which further undergoes reduction by carbonyl reductases to form CC1084037 or CYP2C8-mediated oxidation to form RP101509. CC1084037 is oxidized rapidly to form CC112273 by aldo-keto reductase 1C1/1C2 and/or 3β- and 11β-hydroxysteroid dehydrogenase, and this reversible oxidoreduction between two active metabolites favors CC112273. The ozanimod example illustrates the need for conducting timely radiolabeled human absorption, distribution, metabolism, and excretion studies for characterization of disproportionate metabolites and assessment of exposure coverage during drug development. SIGNIFICANCE STATEMENT: Absorption, metabolism, and excretion of ozanimod were characterized in humans, and the enzymes involved in complex metabolism were elucidated. Disproportionate metabolites were identified, and the activity of these metabolites was determined.

The high incidence of obesity has increased the need to discover new therapeutic targets to combat obesity and obesity-related metabolic diseases. Obesity is defined as an abnormal accumulation of adipose tissue, which is one of the major metabolic organs that regulate energy homeostasis. However, there are currently no approved anti-obesity therapeutics that directly target adipose tissue metabolism. With recent advances in the understanding of adipose tissue biology, molecular mechanisms involved in brown adipose tissue expansion and metabolic activation have been investigated as potential therapeutic targets to increase energy expenditure. This review focuses on G-protein coupled receptors (GPCRs) as they are the most successful class of druggable targets in human diseases and have an important role in regulating adipose tissue metabolism. We summarize recent findings on the major GPCR classes that regulate thermogenesis and mitochondrial metabolism in adipose tissue. Improved understanding of GPCR signaling pathways that regulate these processes could facilitate the development of novel pharmacological approaches to treat obesity and related metabolic disorders.

BackgroundAdequate response to the SARS-CoV-2 vaccine represents an important treatment goal in caring for patients with multiple sclerosis (MS) during the ongoing COVID-19 pandemic. Previous data so far have demonstrated lower spike-specific IgG responses following two SARS-CoV-2 vaccinations in MS patients treated with sphingosine-1-phosphate (S1P) receptor modulators and anti-CD20 monoclonal antibodies (mAb) compared to other disease modifying therapies (DMTs). It is unknown whether subsequent vaccinations can augment antibody responses in these patients.ObjectivesThe goal of this observational study was to determine the effects of a third SARS-CoV-2 vaccination on antibody and T cell responses in MS patients treated with anti-CD20 mAb or S1P receptor modulators.MethodsVaccine responses in patients treated with anti-CD20 antibodies (ocrelizumab and ofatumumab) or S1P receptor modulators (fingolimod and siponimod) were evaluated before and after third SARS-CoV-2 vaccination as part of an ongoing longitudinal study. Total spike protein and spike receptor binding domain (RBD)-specific IgG responses were measured by Luminex bead-based assay. Spike-specific CD4+ and CD8+ T cell responses were measured by activation-induced marker expression.ResultsMS patients and healthy controls were enrolled before and following SARS-CoV-2 vaccination. A total of 31 MS patients (n=10 ofatumumab, n=13 ocrelizumab, n=8 S1P) and 10 healthy controls were evaluated through three SARS-CoV-2 vaccinations. Compared to healthy controls, total spike IgG was significantly lower in anti-CD20 mAb-treated patients and spike RBD IgG was significantly lower in anti-CD20 mAb and S1P-treated patients following a third vaccination. While seropositivity was 100% in healthy controls after a third vaccination, total spike IgG and spike RBD IgG seropositivity were lower in ofatumumab (60% and 60%, respectively), ocrelizumab (85% and 46%, respectively), and S1P-treated patients (100% and 75%, respectively). Longer treatment duration, including prior treatment history, appeared to negatively impact antibody responses. Spike-specific CD4+ and CD8+ T cell responses were well maintained across all groups following a third vaccination. Finally, immune responses were also compared in patients who were vaccinated prior to or following ofatumumab treatment. Antibody responses were significantly higher in those patients who received their primary SARS-CoV-2 vaccination prior to initiating ofatumumab treatment.ConclusionsThis study adds to the evolving understanding of SARS-CoV-2 vaccine responses in people with MS treated with disease-modifying therapies (DMTs) known to suppress humoral immunity. Our findings provide important information for optimizing vaccine immunity in at-risk MS patient populations.

ONO-4641 is a second-generation sphingosine 1-phosphate (S1P) receptor modulator that exhibits selectivity for S1P receptors 1 and 5. Treatment with ONO-4641 leads to a reduction in magnetic resonance imaging disease measures in patients with relapsing-remitting multiple sclerosis. The objective of this study was to explore the potential impact of ONO-4641 treatment based on its immunomodulatory effects. Severe aplastic anemia is a bone marrow (BM) failure disease typically caused by aberrant immune destruction of blood progenitors. Although the T helper type 1–mediated pathology is well described for aplastic anemia, the molecular mechanisms driving disease progression remain undefined. We evaluated the efficacy of ONO-4641 in a mouse model of aplastic anemia. ONO-4641 reduced the severity of BM failure in a dose-dependent manner, resulting in higher blood and BM cell counts. By evaluating the mode of action, we found that ONO-4641 inhibited the infiltration of donor-derived T lymphocytes to the BM. ONO-4641 also induced the accumulation of hematopoietic stem cells in the BM of model mice. These observations indicate, for the first time, that S1P receptor modulators demonstrate efficacy in the mouse model of aplastic anemia and suggest that treatment with ONO-4641 might delay the progression of aplastic anemia. SIGNIFICANCE STATEMENT ONO-4641 is a second-generation sphingosine 1-phosphate (S1P) receptor modulator selective for S1P receptors 1 and 5. In this study, we demonstrated that ONO-4641 regulates the trafficking of T lymphocytes along with hematopoietic stem and progenitor cells, leading to alleviation of pancytopenia and destruction of bone marrow in a bone marrow failure–induced mouse model mimicking human aplastic anemia.

Epilepsy is a devastating neurological condition characterized by long-term tendency to generate unprovoked seizures, affecting around 1-2 % of the population worldwide. Epilepsy is a serious health concern which often associates with other neurobehavioral comorbidities that further worsen disease conditions. Despite tremendous research, the mainstream anti-epileptic drugs (AEDs) exert only symptomatic relief leading to 30% of untreatable patients. This reflects the complexity of the disease pathogenesis and urges the precise understanding of underlying mechanisms in order to explore novel therapeutic strategies that might alter the disease progression as well as minimize the epilepsy-associated comorbidities. Unfortunately, the development of novel AEDs might be a difficult process engaging huge funds, tremendous scientific efforts and stringent regulatory compliance with a possible chance of end-stage drug failure. Hence, an alternate strategy is drug repurposing, where anti-epileptic effects are elicited from drugs that are already used to treat non-epileptic disorders. Herein, we provide evidence of the anti-epileptic effects of Fingolimod (FTY720), a modulator of sphingosine-1-phosphate (S1P) receptor, USFDA approved already for Relapsing-Remitting Multiple Sclerosis (RRMS). Emerging experimental findings suggest that Fingolimod treatment exerts disease-modifying anti-epileptic effects based on its anti-neuroinflammatory properties, potent neuroprotection, anti-gliotic effects, myelin protection, reduction of mTOR signaling pathway and activation of microglia and astrocytes. We further discuss the underlying molecular crosstalk associated with the anti-epileptic effects of Fingolimod and provide evidence for repurposing Fingolimod to overcome the limitations of current AEDs.

Aim: The bioactive lipid, sphingosine-1-phosphate (S1P), has various roles in the physiology and pathophysiology of many diseases. There are five S1P receptors; however, the role of each S1P receptor in atherogenesis is still obscure. Here we investigated the contribution of S1P receptor 2 (S1P2) to atherogenesis by using a specific S1P2 antagonist, ONO-5430514, in apolipoprotein E-deficient ( Apoe −/− ) mice. Methods: Apoe −/− mice fed with a western-type diet (WTD) received ONO-5430514 (30 mg/kg/day) or vehicle. To examine the effect on atherogenesis, Sudan IV staining, histological analysis, qPCR, and vascular reactivity assay was performed. Human umbilical vein endothelial cells (HUVEC) were used for in vitro experiments. Results: WTD-fed Apoe −/− mice had significantly higher S1P2 expression in the aorta compared with wild-type mice. S1P2 antagonist treatment for 20 weeks reduced atherosclerotic lesion development ( p ＜0.05). S1P2 antagonist treatment for 8 weeks ameliorated endothelial dysfunction ( p ＜0.05) accompanied with significant reduction of lipid deposition, macrophage accumulation, and inflammatory molecule expression in the aorta compared with vehicle. S1P2 antagonist attenuated the phosphorylation of JNK in the abdominal aorta compared with vehicle ( p ＜0.05). In HUVEC, S1P promoted inflammatory molecule expression such as MCP-1 and VCAM-1 ( p ＜0.001), which was attenuated by S1P2 antagonist or a JNK inhibitor ( p ＜0.01). S1P2 antagonist also inhibited S1P-induced JNK phosphorylation in HUVEC ( p ＜0.05). Conclusions: Our results suggested that an S1P2 antagonist attenuates endothelial dysfunction and prevents atherogenesis. S1P2, which promotes inflammatory activation of endothelial cells, might be a therapeutic target for atherosclerosis.

Neuropathic pain severely impairs rehabilitation and quality of life after spinal cord injury (SCI). The sphingosine-1-phosphate receptor agonist, FTY720, plays an important protective role in neuronal injury. This study aims to examine the effects of FTY720 in a rat acute SCI model, focusing on neuropathic pain. Female rats with SCI induced by 1-min clip compression were administered vehicle or 1.5 mg/kg of FTY720 24 h after the injury. Using the mechanical nociceptive threshold test, we monitored neuropathic pain and performed histological analysis of the pain pathway, including the μ opioid receptor (MOR), hydroxytryptamine transporter (HTT), and calcitonin gene-related peptide (CGRP). Motor score, SCI lesion volume, residual motor axons, inflammatory response, glial scar, and microvascular endothelial dysfunction were also compared between the two groups. FTY720 treatment resulted in significant attenuation of post-traumatic neuropathic pain. It also decreased systemic and local inflammation, thereby reducing the damaged areas and astrogliosis and resulting in motor functional recovery. Whereas there was no difference in the CGRP expression between the two groups, FTY720 significantly preserved the MOR in both the caudal and rostral areas of the spinal dorsal horn. Whereas HTT was preserved in the FTY720 group, it was significantly increased in the rostral side and decreased in the caudal side of the injury in the vehicle group. These results suggest that FTY720 ameliorates post-traumatic allodynia through regulation of neuroinflammation, maintenance of the blood-brain barrier, and inhibition of glial scar formation, thereby preserving the connectivity of the descending inhibitory pathway and reducing neuropathic pain.

Fingolimod is an approved treatment for relapsing–remitting multiple sclerosis (MS), and its properties in different pathways have raised interest in therapy research for other neurodegenerative diseases. Fingolimod is an agonist of sphingosine-1-phosphate (S1P) receptors. Its main pharmacologic effect is immunomodulation by lymphocyte homing, thereby reducing the numbers of T and B cells in circulation. Because of the ubiquitous expression of S1P receptors, other effects have also been described. Here, we review preclinical experiments evaluating the effects of treatment with fingolimod in neurodegenerative diseases other than MS, such as Alzheimer’s disease or epilepsy. Fingolimod has shown neuroprotective effects in different animal models of neurodegenerative diseases, summarized here, correlating with increased brain-derived neurotrophic factor and improved disease phenotype (cognition and/or motor abilities). As expected, treatment also induced reductions in different neuroinflammatory markers because of not only inhibition of lymphocytes but also direct effects on astrocytes and microglia. Furthermore, fingolimod treatment exhibited additional effects for specific neurodegenerative disorders, such as reduction of amyloid-β production, and antiepileptogenic properties. The neuroprotective effects exerted by fingolimod in these preclinical studies are reviewed and support the translation of fingolimod into clinical trials as treatment in neurodegenerative diseases beyond neuroinflammatory conditions (MS).

Purpose The goal of this study was to assess the safety, tolerability, pharmacodynamics (PD) and pharmacokinetics (PK) of intravenous (IV) siponimod in healthy subjects. Methods This randomized, open-label study was conducted in 2 parts. In Part 1, a total of 16 eligible subjects received either a single oral dose of siponimod (0.25 mg) followed by a single IV infusion (0.25 mg/3 h) in Sequence 1, or vice versa in Sequence 2. In Part 2, a total of 17 eligible subjects received single IV infusions of siponimod (1 mg/24 h). Findings No clinically relevant effect on mean 5-minute or hourly average heart rate was observed following the siponimod IV dosing regimens and both remained above 50 beats/min. Observed atrioventricular blocks and sinus pauses were asymptomatic. The mean change in absolute lymphocyte count from baseline was comparable for the siponimod 0.25 mg oral regimen and the two IV siponimod regimens. Oral siponimod displayed a good absolute bioavailability of 84%. The mean peak exposure of oral siponimod was approximately 48% lower than that of IV siponimod. The M17 metabolite was found to be the most prominent systemic metabolite of siponimod in humans. Implications Siponimod IV infusions were well tolerated, with safety and PD (absolute lymphocyte count) profiles similar to those of oral siponimod. The PD/PK findings supported the development of an innovative rapid IV titration regimen for patients with intracerebral hemorrhage.

As a critical sphingolipid metabolite, sphingosine-1-phosphate (S1P) plays an essential role in immune and vascular systems. There are five S1P receptors, designated as S1PR1-5, encoded in the human genome, and their activities are governed by endogenous S1P, lipid-like S1P mimics, or non-lipid-like therapeutic molecules. Among S1PRs, S1PR1 stands out due to its non-redundant functions, such as the egress of T and B cells from the thymus and secondary lymphoid tissues, making it a potential therapeutic target. However, the structural basis of S1PR1 activation and regulation by various agonists remains unclear. Here we reported four atomic resolution cryo-EM structures of Gi-coupled human S1PR1 complexes: bound to endogenous agonist d18:1 S1P, benchmark lipid-like S1P mimic phosphorylated Fingolimod ((S)-FTY720-P), or non-lipid-like therapeutic molecule CBP-307 in two binding modes. Our results revealed the similarities and differences of activation of S1PR1 through distinct ligands binding to the amphiphilic orthosteric pocket. We also proposed a two-step “shallow to deep” transition process of CBP-307 for S1PR1 activation. Both binding modes of CBP-307 could activate S1PR1, but from shallow to deep transition may trigger the rotation of the N-terminal helix of Gαi and further stabilize the complex by increasing the Gαi interaction with the cell membrane. We combine with extensive biochemical analysis and molecular dynamic simulations to suggest key steps of S1P binding and receptor activation. The above results decipher the common feature of the S1PR1 agonist recognition and activation mechanism and will firmly promote the development of therapeutics targeting S1P receptors.

Identifying the transition of relapsing-remitting multiple sclerosis (MS) to the secondary-progressive MS form remains a clinical challenge due to the gradual nature of the transition, superimposed relapses, the heterogeneous course of disease among patients and the absence of validated biomarkers and diagnostic tools. The uncertainty associated with the transition makes clinical care challenging for both patients and physicians. The emergence of new disease-modifying treatments for progressive MS and the increasing emphasis of nonpharmacological strategies mark a new era in the treatment of progressive MS. This article summarizes challenges in diagnosis and management, discusses novel treatment strategies and highlights the importance of establishing a clear diagnosis and instituting an interdisciplinary management plan in the care of patients with progressive MS.

FTY720 (fingolimod) is a FDA-approved sphingosine analog that is phosphorylated in vivo to modulate sphingosine-1-phosphate receptor (S1PR) signaling for immunosuppression in patients with refractory multiple sclerosis. FTY720 also exhibits promising anticancer efficacy in several preclinical models. While FTY720-induced cytotoxicity is not due to S1PR signaling, the mechanism remains unclear and is reported to occur through various cell death pathways. Here, we performed a systematic, mechanistic study of FTY720-induced cell death in acute myeloid leukemia (AML). We found that FTY720 induced cell death in a panel of genetically diverse AML cell lines that was accompanied by rapid phosphatidylserine (PS) externalization. Importantly, FTY720-induced PS exposure was not due to any direct effects on plasma membrane integrity and was independent of canonical signaling by regulated cell death pathways known to activate lipid flip-flop, including caspase-dependent apoptosis/pyroptosis, necroptosis, ferroptosis, and reactive oxygen species-mediated cell death. Notably, PS exposure required cellular vacuolization induced by defects in endocytic trafficking and was suppressed by the inhibition of PP2A and shedding of Annexin V-positive subcellular particles. Collectively, our studies reveal a non-canonical pathway underlying PS externalization and cell death in AML to provide mechanistic insight into the antitumor properties of FTY720.

BackgroundAll agents engaging sphongosine-1-phospate receptors (S1PRs) will have some cardiovascular effect. This study aimed to elucidate the risk of cardiovascular adverse events (AEs) in patients with multiple sclerosis (MS) treated with S1PR modulators (S1PRMs).MethodsWe systematically searched the PubMed, EMBASE, and Cochrane Library databases for randomised controlled trials (RCTs) published through January 5, 2021. Relative risks (RRs) and 95% confidence intervals (CIs) were calculated using the random-effects model. Sensitivity analyses and meta-regression were performed.ResultsSeventeen RCTs (12 for fingolimod; 3 for ozanimod; 2 for siponimod) involving 13,295 patients were included. Compared with the control treatment, S1PRMs significantly increased the risk of cardiovascular AEs (RR, 2.21; 95% CI, 1.58–3.10; I2, 75.6%). Notably, the high-risk cardiovascular AEs associated with S1PRMs were primarily bradyarrhythmia (RR, 2.92; 95% CI, 1.91–4.46; I2, 30.8%) and hypertension (RR, 2.00; 95% CI, 1.49–2.67; I2, 56.5%). Subgroup analysis results were consistent with the primary outcomes except that ozanimod was associated with a higher risk of hypertension only (RR, 1.76; 95% CI, 1.10–2.82; I2, 0.0%), while siponimod was associated with a higher risk of bradyarrhythmia only (RR, 2.75; 95% CI, 1.75–4.31; I2, 0.0%). No significant inter-subgroup differences were observed (Pinteraction > 0.05).ConclusionsS1PRM use increased the risk of cardiovascular AEs by 1.21 times in patients with MS, and increased risks for bradyarrhythmia and hypertension were at 2.92- and 2.00-fold, respectively. These findings can help clinicians assess the risk of cardiovascular AEs in patients treated with S1PRMs.Systematic Review RegistrationThe PROSPERO ID is CRD42020183215.

Pancreatic cancer is one of the leading causes of cancer-related mortality and has the lowest 5-year survival rate. Therefore, novel strategies are urgently required to treat pancreatic cancer. Pancreatic ductal adenocarcinoma (PDAC) cells rely on enhanced lysosomal function for survival and proliferation to facilitate the degradation of contents accumulated via autophagy and macropinocytosis. Previously, we have reported that the combination of epidermal growth factor receptor/HER2 inhibitor lapatinib and sphingosine analog fingolimod (FTY720) confers a significant cytostatic effect in lung cancer cells. In the present study, the combined effects of these drugs on PDAC cell lines, BxPC-3, KP-4, PANC-1 and MIA PaCa-2, were examined. It was observed that FTY720 enhanced the lapatinib-induced cytotoxic effect and caused non-canonical and lysosome-dependent death in PDAC cells. Lapatinib and FTY720 induced lysosomal swelling and inhibited lysosomal acidification. Combination treatment with lapatinib and FTY720 increased lysosomal membrane permeability, induced mitochondrial depolarization, induced endoplasmic reticulum stress and disturbed intracellular calcium homeostasis. Additionally, the cytotoxic effect of lapatinib was enhanced by hydroxychloroquine or the CDK4/6 inhibitor abemaciclib, both of which induce lysosomal dysfunction. Collectively, these results indicated that the lysosome-targeted drug combination induces multiple organelle dysfunction and exerts a marked cytotoxic effect in PDAC cells.

Background and ObjectivesTo investigate whether the formation or retention of meningeal ectopic lymphoid tissue (mELT) can be inhibited by the sphingosine 1-phosphate receptor 1,5 modulator siponimod (BAF312) in a murine model of multiple sclerosis (MS).MethodsA murine spontaneous chronic experimental autoimmune encephalomyelitis (EAE) model, featuring meningeal inflammatory infiltrates resembling those in MS, was used. To prevent or treat EAE, siponimod was administered daily starting either before EAE onset or at peak of disease. The extent and cellular composition of mELT, the spinal cord parenchyma, and the spleen was assessed by histology and immunohistochemistry.ResultsSiponimod, when applied before disease onset, ameliorated EAE. This effect was also present, although less prominent, when treatment started at peak of disease. Treatment with siponimod resulted in a strong reduction of the extent of mELT in both treatment paradigms. Both B and T cells were diminished in the meningeal compartment.DiscussionBeneficial effects on the disease course correlated with a reduction in mELT, suggesting that inhibition of mELT may be an additional mechanism of action of siponimod in the treatment of EAE. Further studies are needed to establish causality and confirm this observation in MS.

Background and Aims This analysis examined the long-term safety and efficacy of ozanimod in patients with moderately to severely active ulcerative colitis [UC] with ≥ 4 years of follow-up in the phase 2 TOUCHSTONE open-label extension [OLE]. Methods Patients receiving placebo or ozanimod HCl 0.5 mg or 1 mg during the double-blind period could enter the OLE [ozanimod HCl 1 mg daily]. Partial Mayo score [pMS] clinical response and remission were assessed through OLE week 200 and summarized descriptively using observed cases [OC] and non-responder imputation [NRI]. Endoscopy was required at OLE week 56 and the end of treatment. Parameters associated with endoscopy were summarized at weeks 56 and 104 [OC], and week 56 [NRI]. C-reactive protein and faecal calprotectin were assessed. Adverse events were monitored throughout the study. Results Of 197 patients receiving double-blind treatment, 170 entered the OLE. Discontinuation rates were 28% at year 1 and 15–18% annually through year 4. Partial Mayo measures indicated clinical response and remission rates at OLE week 200 of 93.3% and 82.7%, respectively, using OC and 41% and 37% with the more conservative NRI analysis. At weeks 56 and 104, respectively, histological remission rates were 46.3% and 38.5%, and endoscopic improvement rates were 46.4% and 46.5% [OC]. No new safety signals were identified during ≥ 4 years of follow-up. Conclusions There was a high rate of continued study participation and long-term benefit with ozanimod HCl 1 mg daily based on clinical, histological and biomarker measures in patients with moderately to severely active UC in the TOUCHSTONE OLE. [NCT02531126]

Multiple sclerosis (MS) is an inflammatory disease that causes chronic neurological disability in young adults. Modulation of sphingosine 1-phosphate (S1P) receptors, a group of receptors that, among other things, regulate egression of lymphocytes from lymph nodes, has proven to be effective in treating relapsing MS. Fingolimod, the first oral S1P receptor modulator, has demonstrated potent efficacy and tolerability, but can cause undesirable side effects due to its interaction with a wide range of S1P receptor subtypes. This review will focus on ozanimod, a more selective S1P receptor modulator, which has recently received approval for relapsing MS. We summarize ozanimod's mechanism of action, and efficacy and safety from clinical trials that demonstrate its utility as another treatment option for relapsing MS.Lay abstract There are increasing treatment options available for relapsing-remitting multiple sclerosis (MS). Ozanimod (ZEPOSIA) is a treatment that has recently received approval in many regions of the world for relapsing-remitting MS. Ozanimod acts on specific sphingosine 1-phosphate receptors, which are found in many tissues in the body, but also have known beneficial effects in MS. A robust clinical development program has demonstrated ozanimod’s efficacy in reducing clinical and radiological measures of MS disease activity, making it a useful addition to the ever-increasing treatment armamentarium for relapsing MS.

Chemotherapy-induced neuropathic pain (CINP) in both sexes compromises many current chemotherapeutics and lacks an FDA-approved therapy. We recently identified the sphingosine-1-phosphate receptor subtype 1 (S1PR1) and A3 adenosine receptor subtype (A3AR) as novel targets for therapeutic intervention. Our work in male rodents using paclitaxel, oxaliplatin, and bortezomib showed robust inhibition of CINP with either S1PR1 antagonists or A3AR agonists. The S1PR1 functional antagonist FTY720 (Gilenya) is FDA-approved for treating multiple sclerosis, and selective A3AR agonists are in advanced clinical trials for cancer and inflammatory disorders, underscoring the need for their expedited trials in patients with CINP as chemotherapy adjuncts. Our findings reveal that S1PR1 antagonists and A3AR agonists mitigate paclitaxel and oxaliplatin CINP in female and male rodents, but failed to block or reverse bortezomib-induced neuropathic pain (BINP) in females. Although numerous mechanisms likely underlie these differences, we focused on receptor levels. We found that BINP in male rats, but not in female rats, was associated with increased expression of A3AR in the spinal cord dorsal horn, whereas S1PR1 levels were similar in both sexes. Thus, alternative mechanisms beyond receptor expression may account for sex differences in response to S1PR1 antagonists. Morphine and duloxetine, both clinical analgesics, reversed BINP in female mice, demonstrating that the lack of response is specific to S1PR1 and A3AR agents. Our findings suggest that A3AR- and S1PR1-based therapies are not viable approaches in preventing and treating BINP in females and should inform future clinical trials of these drugs as adjuncts to chemotherapy.

Sphingosine-1-phosphate (S1P) receptor 1 subtype (S1PR1) activation by its ligand S1P in the dorsal horn of the spinal cord causes mechanohypersensitivity. The cellular and molecular pathways remain poorly understood. We report that the activation of S1PR1 with an intrathecal injection of the highly selective S1PR1 agonist SEW2871 led to the development of mechanoallodynia by activating the nod-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome (increased expression of NLRP3, cleaved caspase 1 and mature IL-1β) in the dorsal horn of the spinal cord. The functional S1PR1 antagonist FTY720 blocked NLRP3 activation and IL-1β production. Moreover, inhibiting IL-10 signaling with an intrathecal injection of an anti-IL-10 antibody attenuated the beneficial effects exerted by FTY720. This finding suggests that disrupting S1PR1 signaling engages beneficial IL-10-dependent pathways. Notably, we found that mice with astrocyte-specific deletions of S1pr1 did not develop mechanoallodynia after intrathecal injection of SEW2871 and exhibited decreased levels of cleaved caspase 1, identifying astrocytes as a key cellular locus for S1PR1 activity. Our findings provide novel mechanistic insights on how S1PR1 activation in the spinal cord contributes to the development of nociception while identifying the cellular substrate for these activities. PERSPECTIVE: This study is the first to link the activation of NLRP3 and IL-1β signaling in the spinal cord and S1PR1 signaling in astrocytes to the development of S1PR1-evoked mechanoallodynia. These findings provide critical basic science insights to support the development of therapies targeted toward S1PR1.

Parkinson's disease (PD) is a progressive aging disorder that affects millions worldwide, thus, disease-modifying-therapies are urgently needed. PD pathology includes α-synuclein (aSyn) accumulation as synucleinopathy. Loss of GM1 gangliosides occurs in PD brain, which is modeled in GM2 synthase transgenic mice. GM2+/- mice have low, not absent GM1 and develop age-onset motor deficits, making them an excellent PD drug testing model. FTY720 (fingolimod) reduces synucleinopathy in A53T aSyn mice and motor dysfunction in 6-OHDA and rotenone PD models, but no one has tested FTY720 in mice that develop age-onset PD-like motor problems. We confirmed that GM2+/-mice had equivalent rotarod, hindlimb reflexes, and adhesive removal functions at 9 mo. From 11 mo, GM2+/- mice received oral FTY720 or vehicle 3x/week to 16 mo. As bladder problems occur in PD, we also assessed GM2+/- bladder function. This allowed us to demonstrate improved motor and bladder function in GM2+/- mice treated with FTY720. By immunoblot, FTY720 reduced levels of proNGF, a biomarker of bladder dysfunction. In humans with PD, arm swing becomes abnormal, and brachial plexus modulates arm swing. Ultrastructure of brachial plexus in wild type and GM2 transgenic mice confirmed abnormal myelination and axons in GM2 transgenics. FTY720 treated GM2+/- brachial plexus sustained myelin associated protein levels and reduced aggregated aSyn and PSer129 aSyn levels. FTY720 increases brain derived neurotrophic factor (BDNF) and we noted increased BDNF in GM2+/- brachial plexus and cerebellum, which contribute to rotarod performance. These findings provide further support for testing low dose FTY720 in patients with PD.

Hemorrhagic transformation (HT) is a complication of severe ischemic stroke after revascularization. Patients with low platelet counts do not receive reperfusion therapies due to high risk of HT. The immunomodulatory drug fingolimod attenuated HT after tissue plasminogen activator in a thromboembolic stroke model, but the underlying mechanism is unknown. Fingolimod acts on several sphingosine-1-phosphate (S1P) receptors, prevents lymphocyte trafficking to inflamed tissues, and affects brain and vascular cells. This study aimed to investigate changes in S1P-signaling in response to brain ischemia/reperfusion and the effects of the S1P receptor modulator fingolimod on HT. We studied brain expression of S1P signaling components, S1P concentration, and immune cell infiltration after ischemia/reperfusion in mice. We administered fingolimod after ischemia to wild-type mice, lymphocyte-deficient Rag2 mice, and mice with low platelet counts. Ischemia increased S1P-generating enzyme SphK1 mRNA, S1P concentration, and S1P receptor-1 (S1P1) T-cells in the brain. Fingolimod prevented lymphocyte infiltration, and attenuated the severity of HT in Rag2 mice but it was ineffective under thrombocytopenia. Fingolimod prevented β-catenin degradation but not Evans blue extravasation. Ischemia/reperfusion upregulates brain S1P signaling pathway, and fingolimod exerts local effects that attenuate HT. Although fingolimod seems to act on the brain tissue, it did not prevent blood-brain barrier leakage., Supported by a grant from the Spanish Ministerio de Economía y Competitividad (SAF2017-87459-R to AMP), and a grant FIS (PI15/00430 to AC) co-financed by the Instituto de Salud Carlos III (ISCIII)-Subdirección General de Evaluación y el Fondo Europeo de Desarrollo Regional (FEDER).We are grateful to David Bellido from the Centres Científics i Tecnològics of the University of Barcelona for the mass spectrometry analyses. We thank the Pla Estratègic de Recerca i Innovació en Salut (PERIS) program of the Health Department of the Generalitat de Catalunya for supporting FMM, the Centre de Recerca Biomèdica Cellex, Barcelona, where part of this work was performed, and the Centres de Recerca de Catalunya (CERCA) Programme of the Generalitat de Catalunya for supporting the Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS).

Background and Purpose— The contribution of neuroinflammation and, in particular, the infiltration of the brain by lymphocytes is increasingly recognized as a substantial pathophysiological mechanism after stroke. The interaction of lymphocytes with endothelial cells and platelets, termed thromboinflammation, fosters microvascular dysfunction and secondary infarct growth. Siponimod is an S1PR (sphingosine-1-phosphate receptor) modulator, which blocks the egress of lymphocytes from lymphoid organs and has demonstrated beneficial effects in multiple sclerosis treatment. We investigated the effect of treatment with siponimod on stroke outcome in a mouse model of cerebral ischemia. Methods— Transient middle cerebral artery occlusion was induced in middle-aged wild-type mice. Animals were either treated with siponimod (3 mg/kg; intraperitoneal) or vehicle for 6 days. Stroke outcome was assessed by magnetic resonance imaging (spleen volume: prestroke, day 3, and day 7; infarct volume: days 1, 3, and 7) and behavioral tests (prestroke, day 2, and day 6). Immune cells of the peripheral blood and brain-infiltrating cells ipsilateral and contralateral were analyzed by VETScan and by flow cytometry. Results— Siponimod significantly induced lymphopenia on day 7 after transient middle cerebral artery occlusion and reduced T-lymphocyte accumulation in the central nervous system. No effect was detected for lesion size. Conclusions— For siponimod administered at 3 mg/kg in transient middle cerebral artery occlusion mouse model, our findings do not provide preclinical evidence for the use of S1PR1/5 modulators as neuroprotectant in stroke therapy.

As G protein coupled receptors, sphingosine-1-phosphate receptors (S1PRs) have recently gained attention for their role in modulating inflammatory bone loss diseases. Notably, in murine studies inhibiting S1PR2 by its specific inhibitor, JTE013, alleviated osteoporosis induced by RANKL and attenuated periodontal alveolar bone loss induced by oral bacterial inflammation. Treatment with a multiple S1PRs modulator, FTY720, also suppressed ovariectomy-induced osteoporosis, collagen or adjuvant-induced arthritis, and apical periodontitis in mice. However, most previous studies and reviews have focused mainly on how S1PRs manipulate S1P signaling pathways, subsequently affecting various diseases. In this review, we summarize the underlying mechanisms associated with JTE013 and FTY720 in modulating inflammatory cytokine release, cell chemotaxis, and osteoclastogenesis, subsequently influencing inflammatory bone loss diseases. Studies from our group and from other labs indicate that S1PRs not only control S1P signaling, they also regulate signaling pathways induced by other stimuli, including bacteria, lipopolysaccharide (LPS), bile acid, receptor activator of nuclear factor κB ligand (RANKL), IL-6, and vitamin D. JTE013 and FTY720 alleviate inflammatory bone loss by decreasing the production of inflammatory cytokines and chemokines, reducing chemotaxis of inflammatory cells from blood circulation to bone and soft tissues, and suppressing RANKL-induced osteoclast formation.

Ozanimod, recently approved for treating relapsing multiple sclerosis, produced a disproportionate, active, MAO B-catalyzed metabolite (CC112273) that showed remarkable interspecies differences and led to challenges in safety testing. This study explored the kinetics of CC112273 formation from its precursor RP101075. Incubations with human liver mitochondrial fractions revealed

Abuse and misuse of prescription drugs remains an ongoing concern in the USA and worldwide; thus, all centrally active new drugs must be assessed for abuse and dependence potential. Sphingosine-1-phosphate (S1P) receptor modulators are used primarily in the treatment of multiple sclerosis. Among the new S1P receptor modulators, siponimod, ozanimod, and ponesimod have recently been approved in the USA, European Union (EU), and other countries. This review of literature and other public data has been undertaken to assess the potential for abuse of S1P receptor modulators, including ozanimod, siponimod, ponesimod, and fingolimod, as well as several similar compounds in development. The S1P receptor modulators have not shown chemical or pharmacological similarity to known drugs of abuse; have not shown abuse or dependence potential in animal models for subjective effects, reinforcement, or physical dependence; and do not have adverse event profiles demonstrating effects of interest to individuals who abuse drugs (such as sedative, stimulant, mood-elevating, or hallucinogenic effects). In addition, no reports of actual abuse, misuse, or dependence were identified in the scientific literature for fingolimod, which has been on the market since 2010 (USA) and 2011 (EU). Overall, the data suggest that S1P receptor modulators are not associated with significant potential for abuse or dependence, consistent with their unscheduled status in the USA and internationally.

Sphingosine 1 phosphate (S1P) is a bioactive sphingolipid that exerts several functions in physiological and pathological conditions. The modulation of one of its receptors, S1P1, plays an important role in the egress of lymphocytes from lymph nodes and is a useful target in multiple sclerosis (MS) treatment. A new drug, siponimod (BAF-312) has been recently approved for the treatment of secondary progressive MS and has affinity for two S1P receptors, S1P1 and S1P5. The two receptors are expressed by endothelial cells that, as components of the blood–brain barrier (BBB), prevent the access of solutes and lymphocytes into the central nervous system, function often compromised in MS. Using an in vitro BBB model exposed to inflammatory cytokines (TNFα and IFNγ, 5 UI and 10 UI respectively), we evaluated the effects of BAF-312 (100 nM) on expression and function of endothelial tight junctional proteins (Zo-1 and claudin-5), regulation of transendothelial electrical resistance (TEER) and permeability to FITC-conjugated dextran. Zo-1 expression, as well as TEER values, were promptly recovered (24 h) when both S1P1 and S1P5 were activated by BAF-312. In contrast, at this time point, activation of S1P5 with the selective agonist UC-42-WP04 (300 nM) or with BAF-312, under blockade of S1P1 with the selective antagonist NIBR-0213 (1 μM), resulted in recovery of expression and localization of claudin-5 and reduction of TNFα/INFγ-induced expression of metalloproteinase 9. Only after a prolonged BAF-312 exposure (48 h), S1P1 was involved through activation of the PI3K/Akt pathway. The PI3K inhibitor LY294002 (10 µM) prevented in fact the effects of BAF-312 on all the parameters examined. In conclusion, BAF-312, by modulating both S1P1 and S1P5, may strengthen BBB properties, thus providing additional effects in the treatment of MS.

Background. Spinal cord injury (SCI) remains a challenge owing to limited therapies. The exosome of neural stem cells (NSCs-Exos) and FTY720 transplantation could improve SCI effectively. However, the effect and mechanism of NSCs-Exos combined with FTY720 (FTY720-NSCs-Exos) transplantation in the treatment of SCI are not fully understood. Methods. Sprague Dawley rats (8-week-old) were used to establish the SCI model, followed by the treatment of NSCs-Exos, FTY720, and FTY720-NSCs-Exos. The effect of FTY720, NSCs-Exos, and FTY720-NSCs-Exos combination treatment on hindlimb function, pathological changes, apoptosis activity, and the expression of spinal edema-related proteins and apoptosis-related proteins in SCI models were investigated by BBB scoring, HE staining, TUNEL staining and immunohistochemistry, and Western blotting. Meanwhile, the effect of these treatments on spinal cord microvascular endothelial cells (SCMECs) was detected under hypoxic circumstance. Results. Our results found that FTY720-NSCs-Exos could alleviate pathological alterations and ameliorate the hindlimb function and oxygen insufficiency in model mice after SCI. In addition, exosomes could ameliorate the morphology of neurons, reduce inflammatory infiltration and edema, decrease the expression of Bax and AQP-4, upregulate the expression of claudin-5 and Bcl-2, and inhibit cell apoptosis. At the same time, in vitro experiments showed that FTY720-NSCs-Exos could protect the barrier of SCMECs under hypoxic circumstance, and the mechanism is related to PTEN/AKT pathway. Conclusion. FTY720-NSCs-Exos therapy displayed a positive therapeutic effect on SCI by regulating PTEN/AKT pathway and offered a new therapy for SCI.

The sphingosine kinases, SK1 and SK2, catalyse the formation of the bioactive signalling lipid, sphingosine 1-phosphate (S1P), from sphingosine. SK1 and SK2 differ in their subcellular localisation, trafficking and regulation, but the isoforms are also distinct in their selectivity toward naturally occurring and synthetic ligands as substrates and inhibitors. To date, only the structure of SK1 has been determined, and a structural basis for selectivity differences in substrate handling by SK2 has yet to be established. Here we present a structural rationale, based on homology modelling and ligand docking, to account for the capacity of SK2, but not SK1, to efficiently process the pharmacologically active substances, fingolimod (FTY720) and safingol, as substrates. We propose that two key residue differences in hSK2 (Ser305/Thr584 in place of Ala175/Ala339 in hSK1) facilitate conformational switching in the lipid head group anchor residue, Asp308 (corresponding to Asp178 in hSK1), to accommodate substrate diversity for SK2. Our analysis accounts for the contrasting behaviour of fingolimod and safingol as non-turnover inhibitors of SK1, but substrates for SK2, and the observed stereoselectivity for phosphorylation of the pro-S hydroxymethyl group of fingolimod to generate (S)-FTY720-P in vivo. We also rationalise why methylation of the pro-R hydroxymethyl of FTY720 switches the behaviour of the resulting compound, (R)-FTY720 methyl ether (ROMe), to SK2-selective inhibition. Whilst the pharmacological significance of (S)-FTY720-P is firmly established, as the active principle of fingolimod in treating relapsing-remitting multiple sclerosis, the potential importance of SK-mediated phosphorylation of other substrates, such as safingol and non-canonical naturally occuring substrates such as (4E,nZ)-sphingadienes, is less widely appreciated. Thus, the contribution of SK2-derived safingol 1-phosphate to the anti-cancer activity of safingol should be considered. Similarly, the biological role of sphingadiene 1-phosphates derived from plant-based dietary sphingadienes, which we also show here are substrates for both SK1 and SK2, merits investigation.

Despite the recent announcement of promising drug candidates to treat COVID-19, there is currently no effective antiviral drug or vaccine. There is strong evidence that acute lung injury/acute respiratory distress syndrome (ALI/ARDS), likely triggered by a cytokine storm, is responsible for the severity of disease seen in COVID-19 patients. In support of this hypothesis, pilot studies using IL-6 receptor inhibitors such as tocilizumab have shown promising results. Therefore, the use of drugs or cocktails of drugs with broader ability to inhibit these cytokine receptors is likely to be effective. In this article, we propose the use of sphingosine analogues, which have been shown to mitigate acute lung damage in animal models of ALI/ARDS, as early adjuvant therapies to prevent and/or mitigate the cytokine response in COVID-19 patients. This proposal is based on the ability of these drugs to decrease the production of IL-6 and other cytokines. The potential application of fingolimod (FTY720), the oldest sphingosine analogue approved for the treatment of multiple sclerosis, in the early stages of COVID-19 is discussed in more detail as a prototype drug.

Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid that mediates a wide spectrum of biological processes including apoptosis, immune response and inflammation. Here, we sought to understand how S1P signaling affects neuronal excitability in the central amygdala (CeA), which is a brain region associated with fear learning, aversive memory, and the affective dimension of pain. Because the G-protein coupled S1P receptor 1 (S1PR1) has been shown to be the primary mediator of S1P signaling, we utilized S1PR1 agonist SEW2871 and S1PR1 antagonist NIBR to determine a potential role of S1PR1 in altering the cellular physiology of neurons in the lateral division of the CeA (CeL) that share the neuronal lineage marker somatostatin (Sst). CeL-Sst neurons play a critical role in expression of conditioned fear and pain modulation. Here we used transgenic breeding strategies to identify fluorescently labeled CeL-Sst neurons for electrophysiological recordings. Using principal component analysis, we identified two primary subtypes of Sst neurons within the CeL in both male and female mice. We denoted the two types regular-firing (type A) and late-firing (type B) CeL-Sst neurons. In response to SEW2871 application, Type A neurons exhibited increased input resistance, while type B neurons displayed a depolarized resting membrane potential and voltage threshold, increased current threshold, and decreased voltage height. NIBR application had no effect on CeL Sst neurons, indicating the absence of tonic S1P-induced S1PR1. Our findings reveal subtypes of Sst neurons within the CeL that are uniquely affected by S1PR1 activation, which may have implications for how S1P alters supraspinal circuits.

Fingolimod (FTY720), an FDA-approved immunomodulatory drug for treating multiple sclerosis, is an agonist of sphingosine-1-phosphate receptor (S1PR), which has been used as a research tool for inhibiting immune cell trafficking. FTY720 was recently reported to inhibit Chlamydia dissemination. Since genital Chlamydia spreading to the gastrointestinal tract correlated with its pathogenicity in the upper genital tract, we evaluated the effect of FTY720 on chlamydial pathogenicity in the current study. Following an intravaginal inoculation, live chlamydial organisms were detected in mouse rectal swabs. FTY720 treatment significantly delayed live organism shedding in the rectal swabs. However, FTY720 failed to block chlamydial spreading to the gastrointestinal tract. The live chlamydial organisms recovered from rectal swabs reached similar levels between mice with or without FTY720 treatment by day 42 in C57BL/6J and day 28 in CBA/J mice, respectively. Thus, genital Chlamydia is able to launch a 2nd wave of spreading via an FTY720-resistant pathway after the 1st wave of spreading is inhibited by FTY720. As a result, all mice developed significant hydrosalpinx. The FTY720-resistant spreading led to stable colonization of chlamydial organisms in the colon. Consistently, FTY720 did not alter the colonization of intracolonically inoculated Chlamydia. Thus, we have demonstrated that, following a delay in chlamydial spreading caused by FTY720, genital Chlamydia is able to both spread to the gastrointestinal tract via an FTY720-resistant pathway and maintain its pathogenicity in the upper genital tract. Further characterization of the FTY720-resistant pathway(s) explored by Chlamydia for spreading to the gastrointestinal tract may promote our understanding of Chlamydia pathogenic mechanisms.

Multiple sclerosis (MS) is an autoimmune inflammatory disease characterized by demyelination, axonal loss, and synaptic impairment in the central nervous system (CNS). The available therapies aim to reduce the severity of the pathology during the early inflammatory stages, but they are not effective in the chronic stage of the disease. In this phase, failure in endogenous remyelination is associated with the impairment of oligodendrocytes progenitor cells (OPCs) to migrate and differentiate into mature myelinating oligodendrocytes. Therefore, stimulating differentiation of OPCs into myelinating oligodendrocytes has become one of the main goals of new therapeutic approaches for MS. Different disease-modifying therapies targeting sphingosine-1-phosphate receptors (S1PRs) have been approved or are being developed to treat MS. Besides their immunomodulatory effects, growing evidence suggests that targeting S1PRs modulates mechanisms beyond immunomodulation, such as remyelination. In this context, this review focuses on the current understanding of S1PR modulators and their direct effect on OPCs and oligodendrocytes.

Oocytes are highly radiosensitive, so agents that prevent radiation-induced ovarian follicle destruction are important fertility preservation strategies. A previous study in rhesus macaques demonstrated that ovarian treatment with antiapoptotic agents, sphingosine-1-phosphate (S1P) and FTY720, its long-acting mimetic, preserved follicles following a single dose of 15 Gy X-ray radiation, and live offspring were obtained from FTY720-treated animals. However, it is unknown whether these antiapoptotic agents also protected the ovarian stroma from late effects of radiation, including vascular damage and fibrosis. Using ovarian histological sections from this study, we evaluated the vasculature and extracellular matrix in the following cohorts: vehicle + sham irradiation, vehicle + irradiation (OXI), S1P + irradiation (S1P), and FTY720 + irradiation (FTY720). One ovary from each animal was harvested prior to radiation whereas the contralateral ovary was harvested 10 months post-treatment. We assessed vasculature by immunohistochemistry with a PECAM1 antibody, hyaluronan by a hyaluronan binding protein assay, and collagen by picrosirius red and Masson’s trichrome staining. Disorganized vessels were observed in the medulla in the OXI and S1P cohorts relative to the sham, but the vasculature in the FTY720 cohort appeared intact, which may partially explain fertoprotection. There were no differences in the hyaluronan matrix among the cohorts, but there was thickening of the tunica albuginea and fibrosis in the OXI cohort relative to the sham, which was not mitigated by either S1P or FTY720 treatment. Thus, the fertoprotective properties of S1P and FTY720 may be limited given their inability to protect the ovarian stroma against the late effects of radiation-induced fibrosis.

Background and Purpose The inflammatory response after traumatic brain injury (TBI) can contribute to secondary brain injury. RP101075, a sphingosine-1-phosphate receptor modulator, can attenuate various inflammatory responses. Here, we hypothesized that consecutive administration of RP101075 over 3 days could broadly suppress the TBI-induced inflammatory response and ameliorate the outcomes of TBI. Methods and Results Young C57/BL6 mice were subjected to a controlled cortical impact (CCI) model. RP101075-treated mice exhibited significantly reduced scores on the modified neurological severity score (mNSS) test on days 3, 7, 14, and 21 after TBI, in comparison to TBI mice that received the vehicle. RP101075-treated mice had a remarkably decreased percentage of foot faults on the foot fault test on days 7, 14, and 21 after surgery, in comparison to TBI mice that received the vehicle. Using the wet brain weight/dry brain weight method, we found that RP101075 attenuated brain edema at 3 days post-TBI. According to the results of the Morris water maze (MWM), TBI mice treated with RP101075 exhibited reduced latency time and an increased percentage of target quadrant time from day 24 to day 25 after TBI, in comparison to TBI mice that received the vehicle. In addition, flow cytometry and immunohistochemistry showed that RP101075 markedly decreased the number of infiltrated T cells, B cells and NK cells at 3 days after TBI. Analysis of Western blot data showed that RP101075 lowered the expression of proinflammatory factors on day 3 after TBI. Conclusions Our study demonstrated that consecutive administration of RP101075 over 3 days suppressed the TBI-induced inflammatory response and ameliorated neurological deficits after TBI. Thus, this procedure may be a potential treatment strategy for TBI in the clinical setting.

Background: Although treatment of Crohn's disease has improved with development of tumour necrosis factor antagonists, fewer than 50% of patients have sustained benefit. Durable maintenance therapy with orally administered alternative treatments remains an unmet need. We aimed to evaluate the effects of ozanimod, an oral agent selectively targeting sphingosine-1-phosphate receptor subtypes 1 and 5, on endoscopic disease activity in Crohn's disease. Methods: STEPSTONE was a phase 2, uncontrolled, multicentre trial in adults with moderately to severely active Crohn's disease recruited at 28 hospital and community research centres in Canada, the USA, Hungary, Poland, and Ukraine. All patients began treatment with a 7-day dose escalation (4 days on ozanimod 0·25 mg daily followed by 3 days at 0·5 mg daily). Patients then received ozanimod 1·0 mg oral capsule daily for a further 11 weeks, for a 12-week induction period, followed by a 100-week extension. The primary endpoint was change in Simple Endoscopic Score for Crohn's Disease (SES-CD) from baseline to week 12, as determined by a blinded central reader. Data are reported for the intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT02531113 and EudraCT, number 2015–002025–19, and is completed. Findings: 69 patients were enrolled between Nov 17, 2015, and Aug 18, 2016. At week 12, the mean change from baseline in SES-CD was −2·2 (SD 6·0); 16 (23·2%, 95% CI 13·9–34·9) patients experienced endoscopic response. A reduction from baseline in Crohn's Disease Activity Index (CDAI) score also was observed (mean change −130·4 [SD 103·9]). Clinical remission (CDAI