Neurological S1P signaling as an emerging mechanism of action of oral FTY720 (fingolimod) in multiple sclerosis

Vasoactive Intestinal Polypeptide Plays a Key Role in the Microbial-Neuroimmune Control of Intestinal Motility

BACKGROUND & AIMS

Although chronic diarrhea and constipation are common, the treatment is symptomatic because their pathophysiology is poorly understood. Accumulating evidence suggests that the microbiota modulates gut function, but the underlying mechanisms are unknown. We therefore investigated the pathways by which microbiota modulates gastrointestinal motility in different sections of the alimentary tract.

METHODS

Gastric emptying, intestinal transit, muscle contractility, acetylcholine release, gene expression, and vasoactive intestinal polypeptide (VIP) immunoreactivity were assessed in wild-type and Myd88-/-Trif-/- mice in germ-free, gnotobiotic, and specific pathogen-free conditions. Effects of transient colonization and antimicrobials as well as immune cell blockade were investigated. VIP levels were assessed in human full-thickness biopsies by Western blot.

RESULTS

Germ-free mice had similar gastric emptying but slower intestinal transit compared with specific pathogen-free mice or mice monocolonized with Lactobacillus rhamnosus or Escherichia coli, the latter having stronger effects. Although muscle contractility was unaffected, its neural control was modulated by microbiota by up-regulating jejunal VIP, which co-localized with and controlled cholinergic nerve function. This process was responsive to changes in the microbial composition and load and mediated through toll-like receptor signaling, with enteric glia cells playing a key role. Jejunal VIP was lower in patients with chronic intestinal pseudo-obstruction compared with control subjects.

CONCLUSIONS

Microbial control of gastrointestinal motility is both region- and bacteria-specific; it reacts to environmental changes and is mediated by innate immunity-neural system interactions. By regulating cholinergic nerves, small intestinal VIP plays a key role in this process, thus providing a new therapeutic target for patients with motility disorders.

Current status and new developments in sphingosine-1-phosphate receptor antagonism: fingolimod and more

INTRODUCTION

Fingolimod was the first oral disease-modifying treatment approved for relapsing-remitting multiple sclerosis (MS) that serves as a sphingosine-1-phosphate receptor (S1PR) agonist. The efficacy is primarily mediated by S1PR subtype 1 activation, leading to agonist-induced down-modulation of receptor expression and further functional antagonism, blocking the egression of auto-aggressive lymphocytes from the lymph nodes in the peripheral compartment. The role of S1P signaling in the regulation of other pathways in human organisms through different S1PR subtypes has received much attention due to its immune-modulatory function and its significance for the regeneration of the central nervous system (CNS). The more selective second-generation S1PR modulators have improved safety and tolerability profiles.

AREAS COVERED

This review has been carried out based on current data on S1PR modulators, emphasizing the benefits of recent advances in this emergent class of immunomodulatory treatment for MS.

EXPERT OPINION

Ongoing clinical research suggests that S1PR modulators represent an alternative to first-line therapies in selected cases of MS. A better understanding of the relevance of selective S1PR pathways and the ambition to optimize selective modulation has improved the safety and tolerability of S1PR modulators in MS therapy and opened new perspectives for the treatment of other diseases.

Ponesimod inhibits astrocyte-mediated neuroinflammation and protects against cingulum demyelination via S1P1 -selective modulation

Ponesimod is a sphingosine 1‐phosphate (S1P) receptor (S1PR) modulator that was recently approved for treating relapsing forms of multiple sclerosis (MS). Three other FDA‐approved S1PR modulators for MS—fingolimod, siponimod, and ozanimod—share peripheral immunological effects via common S1P₁ interactions, yet ponesimod may access distinct central nervous system (CNS) mechanisms through its selectivity for the S1P₁ receptor. Here, ponesimod was examined for S1PR internalization and binding, human astrocyte signaling and single‐cell RNA‐seq (scRNA‐seq) gene expression, and in vivo using murine cuprizone‐mediated demyelination. Studies confirmed ponesimod’s selectivity for S1P₁ without comparable engagement to the other S1PR subtypes (S1P_2,3,4,5). Ponesimod showed pharmacological properties of acute agonism followed by chronic functional antagonism of S1P₁. A major locus of S1P₁ expression in the CNS is on astrocytes, and scRNA‐seq of primary human astrocytes exposed to ponesimod identified a gene ontology relationship of reduced neuroinflammation and reduction in known astrocyte disease‐related genes including those of immediate early astrocytes that have been strongly associated with disease progression in MS animal models. Remarkably, ponesimod prevented cuprizone‐induced demyelination selectively in the cingulum, but not in the corpus callosum. These data support the CNS activities of ponesimod through S1P₁, including protective, and likely selective, effects against demyelination in a major connection pathway of the brain, the limbic fibers of the cingulum, lesions of which have been associated with several neurologic impairments including MS fatigue.

Differential Effects of Fingolimod and Natalizumab on B Cell Repertoires in Multiple Sclerosis Patients

Natalizumab and fingolimod are effective multiple sclerosis (MS) therapies that disrupt lymphocyte migration but have differential effects on B cell maturation and trafficking. We investigated their effects on peripheral blood (PB) and cerebrospinal fluid (CSF) B cell repertoires using next-generation deep sequencing. Paired CSF and PB B cell subsets (naïve, CD27+ memory, and CD27-IgD- double-negative B cells and plasmablasts) were collected by applying flow cytometry at baseline and after 6 months of treatment and their respective heavy-chain variable region repertoires assessed by Illumina MiSeq. Treatment with fingolimod contracted, whereas natalizumab expanded circulating PB B cells. CSF B cell numbers remained stable following fingolimod treatment but decreased with natalizumab therapy. Clonal overlap between CSF and PB B cells was reduced with natalizumab treatment but remained stable with fingolimod therapy. Lineage analyses of pre- and posttreatment CSF B cell repertoires revealed large, clonally expanded B cell clusters in natalizumab-treated MS patients but no intrathecal clonal expansion following fingolimod therapy. Our findings suggest that natalizumab diminishes the exchange of peripheral and intrathecal B cells without impacting intrathecal clonal expansion. In contrast, fingolimod treatment fails to alter blood-brain barrier B cell exchange but diminishes intrathecal clonal expansion. Sphingosine-1 phosphate receptor inhibition may alter intrathecal B cell biology in MS.

Correlation between IL-31 and sCD40L plasma levels in Fingolimod-treated patients with Relapsing-Remitting Multiple Sclerosis (RRMS)

INTRODUCTION

Multiple Sclerosis (MS) is a chronic, autoimmune, demyelinating disease of the central nervous system (CNS). Currently, several protocols are described for the different phases of MS. In this longitudinal study, we aim to quantify the concentration of plasma cytokines of MS patients treated with Fingolimod alone or after Glatiramer Acetate (GA) or Interferon-beta (IFN-β), in order to compeer both treatments and describes if it is possible to use them as biomarkers.

OBJECTIVE

Compare the two different types of drug treatment and describes possible immune biomarkers in RRMS patients treated with Fingolimod alone or after GA or IFN-β.

MATERIALS AND METHODS

This is a controlled, non-randomized clinical trial. Plasma concentrations of IL-31, sCD40L and nine others cytokines were evaluated in two groups of patients with a one-year follow-up. Group 1 (n = 12): RRMS patients treated with GA or IFN-β for at least six months before the study who changed therapy to Fingolimod after six months, and Group 2 (n = 12): naïve RRMS patients who started treatment with Fingolimod. We used ANOVA two-way to analyze the cytokines and Spearman coefficient to evaluate the correlation.

RESULTS

Although Group 2 started with a greater number of relapses per disease duration, Fingolimod treatment was effective in decreasing this parameter, as well as EDSS over 12 months. However, the treatment with GA or IFN-β on Group 1 showed a tendency to increase the number of relapses after 6 months of follow-up, which decrease when the therapy was changed to Fingolimod. After the evaluation of 11 cytokines in one year, we found that IL-31 and sCD40L were the biomarkers that demonstrated a more difference when compared to the classical ones, following the clinical pattern over the treatment period.

CONCLUSIONS

Our study describes the existence of two promising plasmatic biomarkers (IL-31 and sCD40L), which reduced plasmatic levels in RRMS patients followed the treatment time of Fingolimod, despite that more studies are needed to prove their efficiency.

Pre-clinical and Clinical Implications of "Inside-Out" vs. "Outside-In" Paradigms in Multiple Sclerosis Etiopathogenesis

Multiple Sclerosis (MS) is an immune-mediated neurological disorder, characterized by central nervous system (CNS) inflammation, oligodendrocyte loss, demyelination, and axonal degeneration. Although autoimmunity, inflammatory demyelination and neurodegeneration underlie MS, the initiating event has yet to be clarified. Effective disease modifying therapies need to both regulate the immune system and promote restoration of neuronal function, including remyelination. The challenge in developing an effective long-lived therapy for MS requires that three disease-associated targets be addressed: (1) self-tolerance must be re-established to specifically inhibit the underlying myelin-directed autoimmune pathogenic mechanisms; (2) neurons must be protected from inflammatory injury and degeneration; (3) myelin repair must be engendered by stimulating oligodendrocyte progenitors to remyelinate CNS neuronal axons. The combined use of chronic and relapsing remitting experimental autoimmune encephalomyelitis (C-EAE, R-EAE) (“outside-in”) as well as progressive diphtheria toxin A chain (DTA) and cuprizone autoimmune encephalitis (CAE) (“inside-out”) mouse models allow for the investigation and specific targeting of all three of these MS-associated disease parameters. The “outside-in” EAE models initiated by myelin-specific autoreactive CD4⁺ T cells allow for the evaluation of both myelin-specific tolerance in the absence or presence of neuroprotective and/or remyelinating agents. The “inside-out” mouse models of secondary inflammatory demyelination are triggered by toxin-induced oligodendrocyte loss or subtle myelin damage, which allows evaluation of novel therapeutics that could promote remyelination and neuroprotection in the CNS. Overall, utilizing these complementary pre-clinical MS models will open new avenues for developing therapeutic interventions, tackling MS from the “outside-in” and/or “inside-out”.

Design and Development of Novel Urea, Sulfonyltriurea, and Sulfonamide Derivatives as Potential Inhibitors of phingosine Kinase 1

Sphingosine kinase 1 (SphK1) is one of the well-studied drug targets for cancer and inflammatory diseases. Recently discovered small-molecule inhibitors of SphK1 have been recommended in cancer therapeutics; however, selectivity and potency of first-generation inhibitors are great challenge. In search of effective SphK1 inhibitors, a set of small molecules have been designed and synthesized bearing urea, sulfonylurea, sulfonamide, and sulfonyltriurea groups. The binding affinity of these inhibitors was measured by fluorescence-binding assay and isothermal titration calorimetry. Compounds 1, 5, 6, and 7 showed an admirable binding affinity to the SphK1 in the sub-micromolar range and significantly inhibited SphK1 activity with admirable IC50 values. Molecular docking studies revealed that these compounds fit well into the sphingosine binding pocket of SphK1 and formed significant number of hydrogen bonds and van der Waals interactions. These molecules may be exploited as potent and selective inhibitors of SphK1 that could be implicated in cancer therapeutics after the required in vivo validation.

Sphingolipids in food and their critical roles in human health

Sphingolipids (SLs) are ubiquitous structural components of cell membranes and are essential for cell functions under physiological conditions or during disease progression. Abundant evidence supports that SLs and their metabolites, including ceramide (Cer), ceramide-1-phosphate (C1P), sphingosine (So), sphingosine-1-phosphate (S1P), are signaling molecules that regulate a diverse range of cellular processes and human health. However, there are limited reviews on the emerging roles of exogenous dietary SLs in human health. In this review, we discuss the ubiquitous presence of dietary SLs, highlighting their structures and contents in foodstuffs, particularly in sea foods. The digestion and metabolism of dietary SLs is also discussed. Focus is given to the roles of SLs in both the etiology and prevention of diseases, including bacterial infection, cancers, neurogenesis and neurodegenerative diseases, skin integrity, and metabolic syndrome (MetS). We propose that dietary SLs represent a "functional" constituent as emerging strategies for improving human health. Gaps in research that could be of future interest are also discussed.

Fingolimod for Relapsing-Remitting Multiple Sclerosis: The Experience From Saudi Arabia

BACKGROUND

Fingolimod (Gilenya, Novartis pharmaceuticals) is the first oral disease-modifying therapy for reducing the frequency of clinical relapses and delaying disability progression in patients with relapsing-remitting multiple sclerosis (RRMS). In this study, we aimed to evaluate the outcome of Saudi patients with active RRMS treated with fingolimod.

METHODS

We conducted a retrospective multicenter observational study at the King Abdulaziz Medical City in Jeddah and Riyadh, Saudi Arabia. The inclusion criteria consisted of patients 18 years and older who were diagnosed with RRMS according to the revised McDonald criteria who are currently receiving or received fingolimod treatment in the past for a minimum of 6 months.

RESULTS

A total of 100 patients were treated with fingolimod. The mean ± SD duration of the disease was 9.23 ± 6.63 years. The mean ± SD duration of using fingolimod was 32.00 ± 24.83 months. The mean ± SD baseline expanded disability status scale (EDSS) score was 2.95 ± 2.58. The mean ± SD EDSS score at last follow-up was 2.95 ± 2.65. The mean ± SD annualized relapse rate was significantly reduced from 1.24 ± 1.39 at baseline to 0.43 ± 1.15 at the last follow-up (P = 0.001). In addition, radiological activity was significantly improved at follow-up magnetic resonance imaging studies when compared with the baseline.

CONCLUSIONS

Our multicenter study provides further evidence for the efficacy of fingolimod in reducing clinical and radiological disease activity in patients with RRMS. The reduction in relapse rate, stabilization of the EDSS score, and improvement in magnetic resonance imaging images were similar to other observational studies conducted in different countries worldwide. Fingolimod seems to be well tolerated for our multiple sclerosis population.

Neuroinflammation after Intracerebral Hemorrhage and Potential Therapeutic Targets

Spontaneous intracerebral hemorrhage (ICH) is a catastrophic illness causing significant morbidity and mortality. Despite advances in surgical technique addressing primary brain injury caused by ICH, little progress has been made treating the subsequent inflammatory cascade. Pre-clinical studies have made advancements identifying components of neuroinflammation, including microglia, astrocytes, and T lymphocytes. After cerebral insult, inflammation is initially driven by the M1 microglia, secreting cytokines (e.g., interleukin-1β [IL-1β] and tumor necrosis factor-α) that are involved in the breakdown of the extracellular matrix, cellular integrity, and the blood brain barrier. Additionally, inflammatory factors recruit and induce differentiation of A1 reactive astrocytes and T helper 1 (Th1) cells, which contribute to the secretion of inflammatory cytokines, augmenting M1 polarization and potentiating inflammation. Within 7 days of ICH ictus, the M1 phenotype coverts to a M2 phenotype, key for hematoma removal, tissue healing, and overall resolution of inflammation. The secretion of anti-inflammatory cytokines (e.g., IL-4, IL-10) can drive Th2 cell differentiation. M2 polarization is maintained by the secretion of additional anti-inflammatory cytokines by the Th2 cells, suppressing M1 and Th1 phenotypes. Elucidating the timing and trigger of the anti-inflammatory phenotype may be integral in improving clinical outcomes. A challenge in current translational research is the absence of an equivalent disease animal model mirroring the patient population and comorbid pathophysiologic state. We review existing data and describe potential therapeutic targets around which we are creating a bench to bedside translational research model that better reflects the pathophysiology of ICH patients.

The S1P mimetic fingolimod phosphate regulates mitochondrial oxidative stress in neuronal cells

Fingolimod is one of the few oral drugs available for the treatment of multiple sclerosis (MS), a chronic, inflammatory, demyelinating and neurodegenerative disease. The mechanism of action proposed for this drug is based in the phosphorylation of the molecule to produce its active metabolite fingolimod phosphate (FP) which, in turns, through its interaction with S1P receptors, triggers the functional sequestration of T lymphocytes in lymphoid nodes. On the other hand, part if not most of the damage produced in MS and other neurological disorders seem to be mediated by reactive oxygen species (ROS), and mitochondria is one of the main sources of ROS. In the present work, we have evaluated the anti-oxidant profile of FP in a model of mitochondrial oxidative damage induced by menadione (Vitk3) on neuronal cultures. We provide evidence that incubation of neuronal cells with FP alleviates the Vitk3-induced toxicity, due to a decrease in mitochondrial ROS production. It also decreases regulated cell death triggered by imbalance in oxidative stress (restore values of advanced oxidation protein products and total thiol levels). Also restores mitochondrial function (cytochrome c oxidase activity, mitochondrial membrane potential and oxygen consumption rate) and morphology. Furthermore, increases the expression and activity of protective factors (increases Nrf2, HO1 and Trx2 expression and GST and NQO1 activity), being some of these effects modulated by its interaction with the S1P receptor. FP seems to increase mitochondrial stability and restore mitochondrial dynamics under conditions of oxidative stress, making this drug a potential candidate for the treatment of neurodegenerative diseases other than MS.

Sphingoid bases and their involvement in neurodegenerative diseases

Sphingoid bases (also known as long-chain bases) form the backbone of sphingolipids. Sphingolipids comprise a large group of lipid molecules, which function as the building blocks of biological membranes and play important signaling and regulatory roles within cells. The roles of sphingoid bases in neurotoxicity and neurodegeneration have yet to be fully elucidated, as they are complex and multi-faceted. This comprises a new frontier of research that may provide us with important clues regarding their involvement in neurological health and disease. This paper explores various neurological diseases and conditions which result when the metabolism of sphingoid bases and some of their derivatives, such as sphingosine-1-phosphate and psychosine, becomes compromised due to the inhibition or mutation of key enzymes. Dysregulation of sphingoid base metabolism very often manifests with neurological symptoms, as sphingolipids are highly enriched in the nervous system, where they play important signaling and regulatory roles.

Sphingolipids in neurodegeneration (with focus on ceramide and S1P)

For many decades, research on sphingolipids associated with neurodegenerative disease focused on alterations in glycosphingolipids, particularly glycosylceramides (cerebrosides), sulfatides, and gangliosides. This seemed quite natural since many of these glycolipids are constituents of myelin and accumulated in lipid storage diseases (sphingolipidoses) resulting from enzyme deficiencies in glycolipid metabolism. With the advent of recognizing ceramide and its derivative, sphingosine-1-phosphate (S1P), as key players in lipid cell signaling and regulation of cell death and survival, research focus shifted toward these two sphingolipids. Ceramide and S1P are invoked in a plethora of cell biological processes participating in neurodegeneration such as ER stress, autophagy, dysregulation of protein and lipid transport, exosome secretion and neurotoxic protein spreading, neuroinflammation, and mitochondrial dysfunction. Hence, it is timely to discuss various functions of ceramide and S1P in neurodegenerative disease and to define sphingolipid metabolism and cell signaling pathways as potential targets for therapy.

Regulation of lymphocyte trafficking in central nervous system autoimmunity

CD4⁺ T helper (Th) cells play a central role in orchestrating protective immunity but also in autoimmunity. Multiple Sclerosis (MS) is a human autoimmune disease of the central nervous system (CNS) characterized by the infiltration of inflammatory lymphocytes and myeloid cells into the brain and spinal cord, leading to demyelination, axonal damage, and progressive loss of motor functions. The release of T cells in the circulation and their migration in the central nervous system are key and tightly regulated processes which have been targeted to decrease CD4⁺ T cell presence in the CNS and limit disease progression. Here, we review two of these pathways and discuss how their blockade modulate different subsets of CD4⁺ T cells.

A Functionally Defined In Vivo Astrocyte Population Identified by c-Fos Activation in a Mouse Model of Multiple Sclerosis Modulated by S1P Signaling: Immediate-Early Astrocytes (ieAstrocytes)

Astrocytes have prominent roles in central nervous system (CNS) function and disease, with subpopulations defined primarily by morphologies and molecular markers often determined in cell culture. Here, we identify an in vivo astrocyte subpopulation termed immediate-early astrocytes (ieAstrocytes) that is defined by functional c-Fos activation during CNS disease development. An unbiased screen for CNS cells showing c-Fos activation during experimental autoimmune encephalomyelitis (EAE), a mouse model for multiple sclerosis (MS), was developed by using inducible, TetTag c-Fos reporter mice that label activated cells with a temporally stable, nuclear green fluorescent protein (GFP). Four-dimensional (3D over time) c-Fos activation maps in the spinal cord were produced by combining tissue clearing (iDISCO) and confocal microscopy that identified onset and expansion of GFP+ cell populations during EAE. More than 95% of the GFP+ cells showed glial fibrillary acidic protein (GFAP) immunoreactivity-in contrast to absent or rare labeling of neurons, microglia, and infiltrating immune cells-which constituted ieAstrocytes that linearly increased in number with progression of EAE. ieAstrocyte formation was reduced by either astrocyte-specific genetic removal of sphingosine 1-phosphate receptor 1 (S1P1) or pharmacological inhibition by fingolimod (FTY720), an FDA-approved MS medicine that can functionally antagonize S1P1. ieAstrocytes thus represent a functionally defined subset of disease-linked astrocytes that are the first and predominant CNS cell population activated during EAE, and that track with disease severity in vivo. Their reduction by a disease-modifying agent supports their therapeutic relevance to MS and potentially other neuroinflammatory and neurodegenerative diseases.

The S1P Axis: New Exciting Route for Treating Huntington's Disease

Huntington's disease (HD) is a single-gene inheritable neurodegenerative disorder with an associated complex molecular pathogenic profile that renders it the most 'curable incurable' brain disorder. Continuous effort in the field has contributed to the recent discovery of novel potential pathogenic mechanisms. Findings in preclinical models of the disease as well as in human post-mortem brains from affected patients demonstrate that alteration of the sphingosine-1-phosphate (S1P) axis may represent a possible key player in the pathogenesis of the disease and may act as a potential actionable drug target for the development of more targeted and effective therapeutic approaches. The relevance of the path of this new 'therapeutic route' is underscored by the fact that some drugs targeting the S1P axis are currently in clinical trials for the treatment of other brain disorders.

Sphingosine-1-Phosphate: A Potential Biomarker and Therapeutic Target for Endothelial Dysfunction and Sepsis?

Sepsis is an acute life-threatening multiple organ failure caused by a dysregulated host response to infection. Endothelial dysfunction, particularly barrier disruption leading to increased vascular permeability, edema, and insufficient tissue oxygenation, is critical to sepsis pathogenesis. Sphingosine-1-phosphate (S1P) is a signaling lipid that regulates important pathophysiological processes including vascular endothelial cell permeability, inflammation, and coagulation. It is present at high concentrations in blood and lymph and at very low concentrations in tissues due to the activity of the S1P-degrading enzyme S1P-lyase in tissue cells. Recently, four preclinical observational studies determined S1P levels in serum or plasma of sepsis patients, and all found reduced S1P levels associated with the disease. Based on these findings, this review summarizes S1P-regulated processes pertaining to endothelial functions, discusses the possible use of S1P as a marker and possibilities how to manipulate S1P levels and S1P receptor activation to restore endothelial integrity, dampens the inflammatory host response, and improves organ function in sepsis.

Sphingosine 1-phosphate receptor modulation suppresses pathogenic astrocyte activation and chronic progressive CNS inflammation

Multiple sclerosis (MS) is an autoimmune inflammatory demyelinating disease of the CNS that causes disability in young adults as a result of the irreversible accumulation of neurological deficits. Although there are potent disease-modifying agents for its initial relapsing-remitting phase, these therapies show limited efficacy in secondary progressive MS (SPMS). Thus, there is an unmet clinical need for the identification of disease mechanisms and potential therapeutic approaches for SPMS. Here, we show that the sphingosine 1-phosphate receptor (S1PR) modulator fingolimod (FTY720) ameliorated chronic progressive experimental autoimmune encephalomyelitis in nonobese diabetic mice, an experimental model that resembles several aspects of SPMS, including neurodegeneration and disease progression driven by the innate immune response in the CNS. Indeed, S1PR modulation by FTY720 in murine and human astrocytes suppressed neurodegeneration-promoting mechanisms mediated by astrocytes, microglia, and CNS-infiltrating proinflammatory monocytes. Genome-wide studies showed that FTY720 suppresses transcriptional programs associated with the promotion of disease progression by astrocytes. The study of the molecular mechanisms controlling these transcriptional modules may open new avenues for the development of therapeutic strategies for progressive MS.

Tp-Te interval predicts heart rate reduction after fingolimod administration in patients with multiple sclerosis

BACKGROUND

FTY720 (Fingolimod) is an immunosuppressive drug, which provides favourable effects in patients with multiple sclerosis (MS), albeit it induces heart rate (HR) and blood pressure (BP) reductions. Therefore, we tested potential factors able to predict HR response in MS patients treated with fingolimod.

METHODS

We analysed patients with MS followed at our Neurology Outpatient Clinic from May 2013 to June 2015. All patients underwent BP measurements and 12-lead ECG before and 6-h after drug administration. At these time intervals, conventional and new ECG indexes for cardiac damage, including Tp-Te interval, were measured. Univariate and multivariate analyses were performed to test the outcome of HR reduction more than median difference between baseline and final observations.

RESULTS

69 outpatients with MS (46 males, age 35.1±9.4years, BP 119.0±12.7/73.0±9.3mmHg, HR 73.5±11.4bpm) were included. No relevant adverse reactions were reported. Fingolimod induced progressive systolic (P=0.024) and diastolic (P<0.001) BP, as well as HR (P<0.001) reductions compared to baseline. Prolonged PQ (150.4±19.5 vs. 157.0±19.5ms; P<0.001), QT (374.9±27.0 vs. 400.0±25.8ms; P<0.001), Tp-Te (1.8±0.3 vs. 1.9±0.3mm; P=0.021), and reduced QTc (414.4±24.4 vs. 404.5±24.5ms; P<0.001) intervals were also recorded at final observation. Baseline HR, QT and Tp-Te intervals provided prognostic information at univariate analysis, although Tp-Te interval resulted the best independent predictor for HR reduction at multivariate analysis [0.057 (0.005-0.660); P=0.022].

CONCLUSIONS

This study firstly demonstrates that prolonged Tp-Te interval may identify those MS patients treated with fingolimod at higher risk of having significant, asymptomatic HR reduction during clinical observation.

Effect of FTY720 (fingolimod) on graft survival in renal transplant recipients: a systematic review protocol

INTRODUCTION

Studies have shown that FTY720 has inconsistent effects in kidney transplant recipients. Several review articles on FTY720 have been published, but most have focused on the mechanism of action of FTY720. Therefore, this review aims to evaluate and determine the beneficial and harmful effects of FTY720 therapy in kidney transplant recipients.

METHODS AND ANALYSIS

We electronically searched the following databases: PubMed, Scopus, the Web of Sciences, EMBASE, Cochrane databases and the Cochrane Central Registry of Controlled Trials. Any clinical, randomised controlled trials relating to FTY720 for treating kidney transplant recipients were included without publication status or language restriction. Study selection, data extraction and assessment of study quality were performed independently by two researchers. Data were synthesised by either the fixed effects or the random effects model according to a heterogeneity test. If the extracted data were suitable for meta-analysis, STATA software was used to combine the relative risks for dichotomous outcomes, and the mean differences for continuous outcomes with 95% CIs were measured. Death, loss of function and incidence of acute kidney rejection were assessed as the primary outcomes. Renal graft function, malignancy, delayed graft function and infection were evaluated as secondary outcomes.

ETHICS/DISSEMINATION

This review does not require formal ethics approval because the data are not individualised. The resulting review article will be submitted for publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

CRD42015024648.

GluN2B-containing NMDA receptors are upregulated in plasma membranes by the sphingosine-1-phosphate analog FTY720P

Sphingosine-1-phosphate (S1P) is a ceramide derivative serving not only as a regulator of immune properties but also as a modulator of brain functions. To better understand the mechanism underlying the effects of S1P on brain functions, we investigated the potential impact of S1P receptor (S1PR) activation on NMDA receptor subunits. We used acute rat hippocampal slices as a model system, and determined the effects of the active phosphorylated S1P analog, fingolimod (FTY720P) on various NMDA receptors. Treatment with FTY720P significantly increased phosphorylation of GluN2B-containing NMDA receptors at Tyr1472. This effect appears rather specific, as treatment with FTY720P did not modify GluN2B-Tyr1336, GluN2B-Ser1480, GluN2A-Tyr1325 or GluN1-Ser897 phosphorylation. Pre-treatment of hippocampal slices with the compounds W146 and PP1 indicated that FTY720P-induced GluN2B phosphorylation at Tyr1472 epitopes was dependent on activation of S1PR subunit 1 (S1PR1) and Src/Fyn kinase, respectively. Cell surface biotinylation experiments indicated that FTY720P-induced GluN2B phosphorylation at Tyr1472 was also associated with increased levels of GluN1 and GluN2B subunits on membrane surface, whereas no change was observed for GluN2A subunits. We finally demonstrate that FTY720P is inclined to favor Tau and Fyn accumulation on plasma membranes. These results suggest that activation of S1PR1 by FTY720P enhances GluN2B receptor phosphorylation in rat hippocampal slices, resulting in increased levels of GluN1 and GluN2B receptor subunits in neuronal membranes through a mechanism probably involving Fyn and Tau.

Investigating the molecular mechanisms through which FTY720-P causes persistent S1P1 receptor internalization

BACKGROUND AND PURPOSE

The molecular mechanism underlying the clinical efficacy of FTY720-P is thought to involve persistent internalization and enhanced degradation of the S1P1 receptor subtype (S1P1R). We have investigated whether receptor binding kinetics and β-arrestin recruitment could play a role in the persistent internalization of the S1P1R by FTY720-P.

EXPERIMENTAL APPROACH

[(3) H]-FTY720-P and [(33) P]-S1P were used to label CHO-S1P1/3Rs for binding studies. Ligand efficacy was assessed through [(35) S]-GTPγS binding and β-arrestin recruitment. Metabolic stability was evaluated using a bioassay measuring intracellular Ca(2+) release. CHO-S1P1/3R numbers were determined, following FTY720-P treatment using flow cytometry.

KEY RESULTS

The kinetic off-rate of [(3) H]-FTY720-P from the S1P1R was sixfold slower than from the S1P3R, and comparable to [(33) P]-S1P dissociation from S1P1/3Rs. S1P and FTY720-P stimulated [(35) S]-GTPγS incorporation to similar degrees, but FTY720-P was over 30-fold less potent at S1P3Rs. FTY720-P stimulated a higher level of β-arrestin recruitment at S1P1Rs, 132% of the total recruited by S1P. In contrast, FTY720-P was a weak partial agonist at S1P3R, stimulating just 29% of the total β-arrestin recruited by S1P. Internalization experiments confirmed that cell surface expression of the S1P1R but not the S1P3R was reduced following a pulse exposure to FTY720-P, which is metabolically stable unlike S1P.

CONCLUSIONS AND IMPLICATIONS

FTY720-P and S1P activation of the S1P1R results in receptor internalization as a consequence of an efficient recruitment of β-arrestin. The combination of slow off-rate, efficacious β-arrestin recruitment and metabolic stability all contribute to FTY720-P's ability to promote prolonged S1P1R internalization and may be critical factors in its efficacy in the clinic.

Immunohistochemical detection of sphingosine-1-phosphate receptor 1 and 5 in human multiple sclerosis lesions

AIMS

Sphingosine-1-phosphate receptor (S1PR) modulating therapies are currently in the clinic or undergoing investigation for multiple sclerosis (MS) treatment. However, the expression of S1PRs is still unclear in the central nervous system under normal conditions and during neuroinflammation.

METHODS

Using immunohistochemistry we examined tissues from both grey and white matter MS lesions for sphingosine-1-phosphate receptor 1 (S1P1 ) and 5 (S1P5 ) expression. Tissues from Alzheimer's disease (AD) cases were also examined.

RESULTS

S1P1 expression was restricted to astrocytes and endothelial cells in control tissues and a decrease in endothelial cell expression was found in white matter MS lesions. In grey matter MS lesions, astrocyte expression was lost in active lesions, while in quiescent lesions it was restored to normal expression levels. CNPase colocalization studies demonstrated S1P5 expression on myelin and both were reduced in demyelinated lesions. In AD tissues we found no difference in S1P1 expression.

CONCLUSION

These data demonstrate a differential modulation of S1PRs in MS lesions, which may have an impact on S1PR-directed therapies.

Apigenin attenuates heart injury in lipopolysaccharide-induced endotoxemic model by suppressing sphingosine kinase 1/sphingosine 1-phosphate signaling pathway

Sepsis is a cluster of heterogeneous syndromes associated with progressive endotoxemic developments, ultimately leading to damage of multiple organs, including the heart. This study is to investigate the effects of apigenin on heart injury in lipopolysaccharide-induced endotoxemic rat model. Normal Wistar rats were randomly divided into four groups: control group, LPS group (15 mg/kg), LPS plus apigenin groups with different apigenin doses (50 mg/kg, 100 mg/kg). Serum levels of creatine kinase (CK), lactate dehydrogenase (LDH), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β) were measured after the rats were sacrificed. SphK1/S1P signaling pathway proteins, cleaved caspase-3, cleaved caspase-9, Bax and Bcl-2 in heart were measured by Western blot. In vitro, we evaluated the protective effect of apigenin on rat embryonic heart-derived myogenic cell line H9c2 induced by LPS. Apigenin decreased serum levels of CK-MB, LDH, TNF-α, IL-6, IL-1β. SphK1/S1P signaling pathway proteins, cleaved caspase-3, cleaved caspase-9, Bax in heart were found inhibited and Bcl-2 increased in the apigenin groups in vivo. In addition, apigenin inhibited intracellular calcium, the MAPK pathway and SphK1/S1P signaling pathway in vitro. Apigenin exerts pronounced cardioprotection in rats subjected to LPS likely through suppressing myocardial apoptosis and inflammation by inhibiting the SphK1/S1P signaling pathway.

Sphingosine-1-phosphate receptor 1 signalling in T cells: trafficking and beyond

Sphingosine-1-phosphate (S1P) is a lipid second messenger that signals via five G protein-coupled receptors (S1P1-5 ). S1P receptor (S1PR) signalling is associated with a wide variety of physiological processes including lymphocyte biology, their recirculation and determination of T-cell phenotypes. The effect of FTY720 (Fingolimod, Gilenya™) to regulate lymphocyte egress and to ameliorate paralysis in experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis led to the use of FTY720 as a first-line oral agent for treatment of relapsing-remitting multiple sclerosis. However, a significant body of research suggests that S1P signalling may participate in diverse immune regulatory functions other than lymphocyte trafficking. This review article discusses the current knowledge of S1P signalling in the fate and function of T regulatory, T helper type 17 and memory T cells in health and disease.

Pharmacokinetic evaluation of fingolimod for the treatment of multiple sclerosis

INTRODUCTION

Fingolimod is a sphingosine 1-phosphate receptor modulator with a novel mechanism of action and the first oral drug approved for the treatment of relapsing forms of multiple sclerosis (MS). Fingolimod reduces relapses more effectively than intramuscular interferon β1a and delays disability progression. Associated safety risks are bradyarrhythmia and atrioventricular block following the initial dose, requiring monitoring.

AREAS COVERED

This article examines the characteristics of fingolimod, its pharmacokinetic properties and the efficacy and tolerability in MS. Information on the pharmacology and mechanisms of action is also provided.

EXPERT OPINION

Fingolimod is an effective therapy for relapsing forms of MS in a convenient oral dose. Fingolimod may target not only inflammation but potentially also neurodegeneration. Antagonizing astrocyte sphingosine signaling may help explain the reduction in cerebral atrophy observed in Phase III trials. Long-term data about the safety of fingolimod are needed.

Myelin recovery in multiple sclerosis: the challenge of remyelination

Multiple sclerosis (MS) is the most common demyelinating and an autoimmune disease of the central nervous system characterized by immune-mediated myelin and axonal damage, and chronic axonal loss attributable to the absence of myelin sheaths. T cell subsets (Th1, Th2, Th17, CD8⁺, NKT, CD4⁺CD25⁺ T regulatory cells) and B cells are involved in this disorder, thus new MS therapies seek damage prevention by resetting multiple components of the immune system. The currently approved therapies are immunoregulatory and reduce the number and rate of lesion formation but are only partially effective. This review summarizes current understanding of the processes at issue: myelination, demyelination and remyelination—with emphasis upon myelin composition/architecture and oligodendrocyte maturation and differentiation. The translational options target oligodendrocyte protection and myelin repair in animal models and assess their relevance in human. Remyelination may be enhanced by signals that promote myelin formation and repair. The crucial question of why remyelination fails is approached is several ways by examining the role in remyelination of available MS medications and avenues being actively pursued to promote remyelination including: (i) cytokine-based immune-intervention (targeting calpain inhibition), (ii) antigen-based immunomodulation (targeting glycolipid-reactive iNKT cells and sphingoid mediated inflammation) and (iii) recombinant monoclonal antibodies-induced remyelination.

Role of regulatory T cells in pathogenesis and biological therapy of multiple sclerosis

Multiple sclerosis (MS) is an inflammatory disease in which the myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms. It is caused by an autoimmune response to self-antigens in a genetically susceptible individual induced by unknown environmental factors. Principal cells of the immune system that drive the immunopathological processes are T cells, especially of T_H1 and T_H17 subsets. However, in recent years, it was disclosed that regulatory T cells took part in, too. Subsequently, there was endeavour to develop ways how to re-establish their physiological functions. In this review, we describe known mechanisms of action, efficacy, and side-effects of contemporary and emerging MS immunotherapeutical agents on Treg cells and other cells of the immune system involved in the immunopathogenesis of the disease. Furthermore, we discuss how laboratory immunology can offer physicians its help in the diagnosis process and decisions what kind of biological therapy should be used.

Fingolimod phosphate promotes the neuroprotective effects of microglia

Fingolimod phosphate (FTY720) is a sphingosine 1-phosphate (S1P) receptor agonist that is being used as a new oral drug for multiple sclerosis. FTY720 prevents lymphocytes from moving out of the lymphoid organs and inhibits autoreactive lymphocytes from infiltrating the central nervous system. Whether FTY720 directly affects microglia-the innate immune cells of the central nervous system-is unclear. Here we show that FTY720 binds S1P1 receptors to downregulate activated microglial production of such pro-inflammatory cytokines as tumor necrosis factor-α, interleukin-1β, and interleukin-6. FTY720 also upregulates microglial production of brain-derived neurotrophic factor and glial cell-derived neurotrophic factor. These results suggested that FTY720 directly promotes the neuroprotective effects of microglia. Therefore, FTY720 may be a potent therapeutic agent for not only multiple sclerosis but also other neurologic diseases associated with microglial activation.

Lysophospholipid receptor activation of RhoA and lipid signaling pathways

The lysophospholipids sphingosine 1-phosphate (S1P) and lysophosphatidic acid (LPA) signal through G-protein coupled receptors (GPCRs) which couple to multiple G-proteins and their effectors. These GPCRs are quite efficacious in coupling to the Gα(12/13) family of G-proteins, which stimulate guanine nucleotide exchange factors (GEFs) for RhoA. Activated RhoA subsequently regulates downstream enzymes that transduce signals which affect the actin cytoskeleton, gene expression, cell proliferation and cell survival. Remarkably many of the enzymes regulated downstream of RhoA either use phospholipids as substrates (e.g. phospholipase D, phospholipase C-epsilon, PTEN, PI3 kinase) or are regulated by phospholipid products (e.g. protein kinase D, Akt). Thus lysophospholipids signal from outside of the cell and control phospholipid signaling processes within the cell that they target. Here we review evidence suggesting an integrative role for RhoA in responding to lysophospholipids upregulated in the pathophysiological environment, and in transducing this signal to cellular responses through effects on phospholipid regulatory or phospholipid regulated enzymes. This article is part of a Special Issue entitled Advances in Lysophospholipid Research.

Sphingosine-1-phosphate receptors as emerging targets for treatment of pain

Lysolipids are important mediators of cellular communication in multiple physiological processes. Sphingosine-1-phosphate (S1P) is a major lysolipid in many organs, including the central nervous system (CNS). This commentary discusses recent findings on the role of S1P in regulating pain perception, and highlights advances and challenges in the field. S1P interacts with multiple cellular targets, including G-protein-coupled receptors. Known S1P receptors include five types, four of which are expressed in the CNS (S1P(1,2,3,5)) where they are localized on neurons and glia. S1P receptor-mediated G-protein activation has been demonstrated throughout the CNS, including regions that regulate nociception. S1P receptors couple to multiple G-proteins to produce various intracellular responses, and can mediate both excitatory and inhibitory neuromodulation, depending on the receptor type and cellular context. Both antinociceptive and pro-nociceptive effects of S1P have been reported, and both actions can involve S1P(1) receptors. Current evidence suggests that antinociception is mediated by CNS neurons, whereas pro-nociception is mediated by primary afferent neurons or immune cells in the periphery, or CNS glia. Nonetheless, peripheral administration of the S1P(1,3,4,5) agonist pro-drug, FTY720, produces antinociception. FTY720 is approved to treat multiple sclerosis, and produces potent anti-inflammatory effects, which suggests potential utility for painful autoimmune diseases. Furthermore, evidence suggests that the S1P system interacts with other pain-modulatory systems, such as endogenous cannabinoid and opioid systems, and putative novel sphingolipid targets in the CNS. These findings suggest that drugs targeting the S1P system could be developed as novel analgesics, either as monotherapy or potential adjuncts to established analgesics.

Lysophospholipids and their receptors in the central nervous system

Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P), two of the best-studied lysophospholipids, are known to influence diverse biological events, including organismal development as well as function and pathogenesis within multiple organ systems. These functional roles are due to a family of at least 11 G protein-coupled receptors (GPCRs), named LPA(1-6) and S1P(1-5), which are widely distributed throughout the body and that activate multiple effector pathways initiated by a range of heterotrimeric G proteins including G(i/o), G(12/13), G(q) and G(s), with actual activation dependent on receptor subtypes. In the central nervous system (CNS), a major locus for these signaling pathways, LPA and S1P have been shown to influence myriad responses in neurons and glial cell types through their cognate receptors. These receptor-mediated activities can contribute to disease pathogenesis and have therapeutic relevance to human CNS disorders as demonstrated for multiple sclerosis (MS) and possibly others that include congenital hydrocephalus, ischemic stroke, neurotrauma, neuropsychiatric disorders, developmental disorders, seizures, hearing loss, and Sandhoff disease, based upon the experimental literature. In particular, FTY720 (fingolimod, Gilenya, Novartis Pharma, AG) that becomes an analog of S1P upon phosphorylation, was approved by the FDA in 2010 as a first oral treatment for MS, validating this class of receptors as medicinal targets. This review will provide an overview and update on the biological functions of LPA and S1P signaling in the CNS, with a focus on results from studies using genetic null mutants for LPA and S1P receptors. This article is part of a Special Issue entitled Advances in Lysophospholipid Research.

G protein-coupled receptors as therapeutic targets for multiple sclerosis

G protein-coupled receptors (GPCRs) mediate most of our physiological responses to hormones, neurotransmitters and environmental stimulants. They are considered as the most successful therapeutic targets for a broad spectrum of diseases. Multiple sclerosis (MS) is an inflammatory disease that is characterized by immune-mediated demyelination and degeneration of the central nervous system (CNS). It is the leading cause of non-traumatic disability in young adults. Great progress has been made over the past few decades in understanding the pathogenesis of MS. Numerous data from animal and clinical studies indicate that many GPCRs are critically involved in various aspects of MS pathogenesis, including antigen presentation, cytokine production, T-cell differentiation, T-cell proliferation, T-cell invasion, etc. In this review, we summarize the recent findings regarding the expression or functional changes of GPCRs in MS patients or animal models, and the influences of GPCRs on disease severity upon genetic or pharmacological manipulations. Hopefully some of these findings will lead to the development of novel therapies for MS in the near future.

Oral fingolimod rescues the functional deficits of synapses in experimental autoimmune encephalomyelitis

BACKGROUND AND PURPOSE Alterations of glutamate-mediated synaptic transmission occur early during neuroinflammatory insults, and lead to degenerative neuronal damage in multiple sclerosis (MS) and also in experimental autoimmune encephalomyelitis (EAE), which is a murine model of MS. Fingolimod is an effective orally active agent for the treatment of MS, affecting lymphocyte invasion of the brain. However, it is still unclear if fingolimod can be neuroprotective in this disorder. EXPERIMENTAL APPROACH Using neurophysiological recordings and morphological evaluation of dendritic integrity, we evaluated the effects of oral fingolimod on the clinical score of EAE mice in order to determine whether the compound was associated with preservation of synaptic transmission. KEY RESULTS Oral fingolimod prevented and reversed the pre- and postsynaptic alterations of glutamate transmission in EAE mice. These effects were associated with a clear amelioration of the clinical deterioration seen in EAE mice, and with a significant inhibition of neuronal dendritic pathology. Fingolimod did not alter the spontaneous excitatory postsynaptic currents in control animals, suggesting that only the pathological processes behind the inflammation-induced defects in glutamate transmission were modulated by this compound. CONCLUSIONS AND IMPLICATIONS The beneficial effects of fingolimod on the clinical, synaptic and dendritic abnormalities of murine EAE might correlate with the neuroprotective actions of this agent, as observed in MS patients. LINKED ARTICLE This article is commented on by Gillingwater, pp. 858-860 of this issue. To view this commentary visit http://dx.doi.org/10.1111/j.1476-5381.2011.01612.x.

Signaling and regulatory functions of bioactive sphingolipids as therapeutic targets in multiple sclerosis

Spingolipids (SLs) are an important component of central nervous system (CNS) myelin sheaths and affect the viability of brain cells (oligodendrocytes, neurons and astrocytes) that is determined by signaling mediated by bioactive sphingoids (lyso-SLs). Recent studies indicate that two lipids, ceramide and sphingosine 1-phosphate (S1P), are particularly involved in many human diseases including the autoimmune inflammatory demyelination of multiple sclerosis (MS). In this review we: (1) Discuss possible sources of ceramide in CNS; (2) Summarize the features of the metabolism of S1P and its downstream signaling through G-protein-coupled receptors; (3) Link perturbations in bioactive SLs metabolism to MS neurodegeneration and (4) Compile ceramide and S1P relationships to this process. In addition, we described recent preclinical and clinical trials of therapies targeting S1P signaling, including 2-amino-2-propane-1,3-diol hydrochloride (FTY720, fingolimod) as well as proposed intervention to specify critical SL levels that tilt balances of apoptotic/active ceramide versus anti-apoptotic/inactive dihydroceramide that may offer a novel and important therapeutic approach to MS.

Novel methods for the quantification of (2E)-hexadecenal by liquid chromatography with detection by either ESI QTOF tandem mass spectrometry or fluorescence measurement

Sphingosine-1-phosphate lyase (SPL) is the only known enzyme that irreversibly cleaves sphingosine-1-phosphate (S1P) into phosphoethanolamine and (2E)-hexadecenal during the final step of sphingolipid catabolism. Because S1P is involved in a wide range of physiological and diseased processes, determining the activity of the degrading enzyme is of great interest. Therefore, we developed two procedures based on liquid chromatography (LC) for analysing (2E)-hexadecenal, which is one of the two S1P degradation products. After separation, two different quantification methods were performed, tandem mass spectrometry (MS) and fluorescence detection. However, (2E)-hexadecenal as a long-chain aldehyde is not ionisable by electrospray ionisation (ESI) for MS quantification and has an insufficient number of corresponding double bonds for fluorescence detection. Therefore, we investigated 2-diphenylacetyl-1,3-indandione-1-hydrazone (DAIH) as a derivatisation reagent. DAIH transforms the aldehyde into an ionisable and fluorescent analogue for quantitative analysis. Our conditions were optimised to obtain the outstanding limit of detection (LOD) of 1 fmol per sample (30 μL) for LC-MS/MS and 0.75 pmol per sample (200 μL) for LC determination with fluorescence detection. We developed an extraction procedure to separate and concentrate (2E)-hexadecenal from biological samples for these measurements. To confirm our new methods, we analysed the (2E)-hexadecenal level of different cell lines and human plasma for the first time ever. Furthermore, we treated HT-29 cells with different concentrations of 4-deoxypyridoxine (DOP), which competitively inhibits pyridoxal-5-phosphate (P5P), an essential cofactor for SPL activity, and observed a significant decrease in (2E)-hexadecenal relative to the untreated cells.

Fingolimod: a review of its use in the management of relapsing-remitting multiple sclerosis

Oral fingolimod (Gilenya™), a sphingosine 1-phosphate (S1P) receptor agonist, is the first oral agent and the first in a novel class of disease-modifying therapies (DMTs) to be approved for use in the US for the treatment of relapsing forms of multiple sclerosis (MS). In the EU, fingolimod is approved for use as a single-agent DMT in selected patients with highly-active, relapsing-remitting (RR) MS. This article reviews the pharmacological properties and clinical use of the drug in patients with RRMS. Fingolimod is rapidly converted in vivo to the active moiety S-fingolimod-phosphate, which binds with high affinity to S1P receptors, thereby sequestering lymphocytes in the lymph nodes and preventing their egress into the peripheral circulation. As a consequence, there is a reduction in the infiltration of autoaggressive lymphocytes into the CNS. Fingolimod-phosphate also acts as a functional antagonist, as its binding to S1P receptors results in their internalization and degradation, thereby downregulating S1P receptors on the lymphocyte cell surface. Since fingolimod crosses the blood : brain barrier, it also potentially acts at S1P receptors on neural cells in the CNS to mitigate neuropathological processes associated with MS. In large multinational trials in adult patients with RRMS, oral fingolimod 0.5 mg/day was more effective than oral placebo (FREEDOMS) and recommended dosages of intramuscular interferon-β (IFNβ)-1a (TRANSFORMS) in reducing the annualized relapse rate and was also generally more effective at slowing progression of neurological disability and at reducing the burden and activity of disease. Fingolimod was generally well tolerated in these trials of up to 2 years' duration, with most adverse events being manageable and of mild to moderate severity; there were two deaths from opportunistic infections, albeit these occurred with fingolimod 1.25 mg/day (higher than the recommended dosage). Limited long-term data indicated that no new safety concerns had arisen after 5 years of fingolimod treatment. However, further clinical experience is required to fully determine the long-term safety profile of fingolimod, particularly with regard to any potentially serious or life-threatening adverse events. In the absence of robust pharmacoeconomic studies and of head-to-head trials comparing fingolimod with other formulations of IFNβ and glatiramer acetate, the relative position of fingolimod with respect to other DMTs remains to be fully determined. In the meantime, given its convenient once-daily oral treatment regimen and better efficacy than intramuscular IFNβ-1a, fingolimod is a valuable emerging option for the treatment of adult patients with relapsing forms of MS.

There is more to a lipid than just being a fat: sphingolipid-guided differentiation of oligodendroglial lineage from embryonic stem cells

Dr. Robert K. Yu's research showed for the first time that the composition of glycosphingolipids is tightly regulated during embryo development. Studies in our group showed that the glycosphingolipid precursor ceramide is also critical for stem cell differentiation and apoptosis. Our new studies suggest that ceramide and its derivative, sphingosine-1-phosphate (S1P), act synergistically on embryonic stem (ES) cell differentiation. When using neural precursor cells (NPCs) derived from ES cells for transplantation, residual pluripotent stem (rPS) cells pose a significant risk of tumor formation after stem cell transplantation. We show here that rPS cells did not express the S1P receptor S1P1, which left them vulnerable to ceramide or ceramide analog (N-oleoyl serinol or S18)-induced apoptosis. In contrast, ES cell-derived NPCs expressed S1P1 and were protected in the presence of S1P or its pro-drug analog FTY720. Consistent with previous studies, FTY720-treated NPCs differentiated predominantly toward oligodendroglial lineage as tested by the expression of the oligodendrocyte precursor cell (OPC) markers Olig2 and O4. As the consequence, a combined administration of S18 and FTY720 to differentiating ES cells eliminated rPS cells and promoted oligodendroglial differentiation. In addition, we show that this combination promoted differentiation of ES cell-derived NPCs toward oligodendroglial lineage in vivo after transplantation into mouse brain.