sphingosine-1-phosphate and Inflammatory-Bowel-Diseases

Immune cell trafficking is a critical element of the intestinal immune response, both in homeostasis and in pathological conditions associated with inflammatory bowel disease (IBD). This process involves adhesion molecules, chemoattractants and receptors expressed on immune cell surfaces, blood vessels and stromal intestinal tissue as well as signalling pathways, including those modulated by sphingosine 1-phosphate (S1P). The complex biological processes of leukocyte recruitment, activation, adhesion and migration have been targeted by various monoclonal antibodies (vedolizumab, etrolizumab, ontamalimab). Promising preclinical and clinical data with several oral S1P modulators suggest that inhibition of lymphocyte egress from the lymph nodes to the bloodstream might be a safe and efficacious alternative mechanism for reducing inflammation in immune-mediated disorders, including Crohn's disease and ulcerative colitis. Although various questions remain, including the potential positioning of S1P modulators in treatment algorithms and their long-term safety, this novel class of compounds holds great promise. This Review summarizes the critical mediators and mechanisms involved in immune cell trafficking in IBD and the available evidence for efficacy, safety and pharmacokinetics of S1P receptor modulators in IBD and other immune-mediated disorders. Further, it discusses potential future approaches to incorporate S1P modulators into the treatment of IBD.

Topics: Colitis, Ulcerative; Humans; Inflammatory Bowel Diseases; Lysophospholipids; Sphingosine

Sphingosine-1-phosphate (S1P) belongs to the group of biologically active sphingolipids. Because of its ability to regulate the migration of lymphocytes, S1P constitutes an important element of pathophysiology of several diseases, such as: lupus erythematosus, multiple sclerosis or inflammatory bowel diseases. Inflammatory bowel diseases (IBD) are the group of chronic and recurrent diseases of the gastrointestinal tract. The most common among IBD are: Crohn’s disease and ulcerative colitis. Drugs that are currently used in the therapy of IBD alleviate symptoms, improve patients’ quality of life and induce remission but their efficacy is not satisfactory. Modulators of S1P receptors constitu­te an emerging option in the therapy of IBD. In this review we will discuss the role of S1P, its receptor and enzymes that participate in the metabolism of S1P under physiological conditions and in the course of IBD. Moreover, we will sum up the results of preclinical and clinical studies on S1P receptors modulators in IBD.. Sfingozyno-1-fosforan (S1P) jest przedstawicielem sfingolipidów o wysokiej aktywno-ści biologicznej. Ze względu na swój wpływ na migrację komórek odpornościowych uznawany jest za istotny element w patogenezie wielu chorób, takich jak: toczeń układowy, stwardnienie rozsiane czy nieswoiste choroby zapalne jelit (NChZJ). Nieswoiste choroby zapalne jelit to grupa przewlekłych i postępujących schorzeń układu pokarmowego, które przebiegają z okresami zaostrzeń i remisji. Do najczęstszych zalicza się: chorobę Leśniow-skiego-Crohna (ChLC) oraz wrzodziejące zapalenie jelita grubego (WZJG). Obecnie w le-czeniu NChZJ stosuje się związki o działaniu przeciwzapalnym i immunomodulującym, których zadaniem jest złagodzenie objawów oraz wprowadzenie pacjenta w stan remisji. W ramach tego artykułu omówiona zostanie rola S1P, receptora dla S1P oraz enzymów bio-rących udział w jego metabolizmie w warunkach fizjologicznych oraz w przebiegu NChZJ. Ponadto, podsumowane zostaną wyniki badań przedklinicznych i klinicznych nad skutecz-nością modulatorów receptora dla S1P w przebiegu NChZJ.

Topics: Colitis, Ulcerative; Crohn Disease; Humans; Inflammatory Bowel Diseases; Lysophospholipids; Quality of Life; Sphingosine

Studies in the 1990s using animal models of intestinal inflammation delineated the crucial molecules involved in leukocyte attraction and retention to the inflamed gut and associated lymphoid tissues. The first drug targeting leukocyte trafficking tested in inflammatory bowel diseases was the anti-ICAM-1 antisense oligonucleotide alicaforsen, showing only modest efficacy. Subsequently, the anti-α4 monoclonal antibody natalizumab proved efficacious for induction and maintenance of remission in Crohn's disease, but was associated with progressive multifocal leukoencephalopathy due to its ability to interfere with both α4β1 and α4β7 function. Later developments in this area took advantage of the fairly selective expression of MAdCAM-1 in the digestive organs, showing that vedolizumab, a more specific monoclonal antibody selectively blocking MAdCAM-1 binding to integrin α4β7, was efficacious for induction and maintenance of remission in ulcerative colitis and Crohn's disease, and it was not associated with neurological complications. Currently, other drugs targeting the β7 subunit, immunoglobulin superfamily molecules expressed on the endothelium, as well as blockade of lymphocyte recirculation in lymph nodes through modulation of sphingosine 1-phosphate receptors are under development. The potential use and risks of combined anti-trafficking therapy will be examined in this review.

Topics: Animals; Antibodies, Monoclonal, Humanized; Cell Adhesion Molecules; Cell Communication; Chemotaxis, Leukocyte; Endothelial Cells; Fingolimod Hydrochloride; Gastrointestinal Agents; Gastrointestinal Tract; Humans; Immunoglobulins; Immunosuppressive Agents; Indans; Inflammatory Bowel Diseases; Integrins; Intercellular Adhesion Molecule-1; Leukocytes; Lysophospholipids; Mucoproteins; Natalizumab; Oxadiazoles; Phosphorothioate Oligonucleotides; Receptors, Lysosphingolipid; Sphingosine

Beyond their role as structural molecules, sphingolipids are involved in many important cellular processes including cell proliferation, apoptosis, inflammation, and migration. Altered sphingolipid metabolism is observed in many pathological conditions including gastrointestinal diseases. Inflammatory bowel disease (IBD) represents a state of complex, unpredictable, and destructive inflammation of unknown origin within the gastrointestinal tract. The mechanisms explaining the pathophysiology of IBD involve signal transduction pathways regulating gastro-intestinal system's immunity. Progressive intestinal tissue destruction observed in chronic inflammation may be associated with an increased risk of colon cancer. Sphingosine-1-phosphate (S1P), a sphingolipid metabolite, functions as a cofactor in inflammatory signaling and becomes a target in the treatment of IBD, which might prevent its conversion to cancer. This paper summarizes new findings indicating the impact of (S1P) on IBD development and IBD-associated carcinogenesis.

Topics: Animals; Cell Transformation, Neoplastic; Colonic Neoplasms; Disease Progression; Humans; Inflammatory Bowel Diseases; Lysophospholipids; Models, Biological; Risk Factors; Signal Transduction; Sphingosine

Insights into the pathogenesis of inflammatory bowel diseases (IBDs) have provided important information for the development of therapeutics. Levels of interleukin 23 (IL23) and T-helper (Th) 17 cell pathway molecules are increased in inflamed intestinal tissues of patients with IBD. Loss-of-function variants of the IL23-receptor gene (IL23R) protect against IBD, and, in animals, blocking IL23 reduces the severity of colitis. These findings indicated that the IL23 and Th17 cell pathways might be promising targets for the treatment of IBD. Clinical trials have investigated the effects of agents designed to target distinct levels of the IL23 and Th17 cell pathways, and the results are providing insights into IBD pathogenesis and additional strategies for modulating these pathways. Strategies to reduce levels of proinflammatory cytokines more broadly and increase anti-inflammatory mechanisms also are emerging for the treatment of IBD. The results from trials targeting these immune system pathways have provided important lessons for future trials. Findings indicate the importance of improving approaches to integrate patient features and biomarkers of response with selection of therapeutics.

Topics: Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Cytokines; Humans; Inflammatory Bowel Diseases; Interleukin-23; Janus Kinases; Lysophospholipids; Molecular Targeted Therapy; Oligonucleotides; Piperidines; Protein Kinase Inhibitors; Pyrimidines; Pyrroles; Signal Transduction; Smad7 Protein; Sphingosine; Th17 Cells; Transforming Growth Factor beta; Ustekinumab

Inflammatory bowel diseases (IBD), including ulcerative colitis and Crohn's disease, involve an inappropriate immune reaction in the digestive tract, causing a variety of disabling symptoms. The advent of monoclonal antibodies (anti-tumor necrosis factor, anti-integrin, anti-interleukin -23) has revolutionized IBD management. Nevertheless, these agents, with potential for immunogenicity, are associated with high rates of response loss and disease relapse over time. They are also associated with high production costs. Sphingosine-1-phosphate (S1P), a membrane-derived lysophospholipid signaling molecule, is implicated in a vast array of physiological and pathophysiological processes, primarily via extracellular activation of S1P1-S1P5 receptors. S1P1, S1P4 and S1P5 are involved in regulation of the immune system, while S1P2 and S1P3 may be associated with cardiovascular, pulmonary, and theoretical cancer-related risks. Targeting S1P receptors for inflammatory conditions has been successful in clinical trials leading to approval of the non-selective S1P modulator, fingolimod, for relapsing forms of multiple sclerosis. However, the association of this non-selective S1P modulator with serious adverse events provides the rationale for developing more selective S1P receptor modulators. Until recently, three S1P modulators with differing selectivity for S1P receptors were in clinical development for IBD: ozanimod (RPC1063), etrasimod (APD334) and amiselimod (MT-1303). The development of amiselimod has been stopped as Biogen are currently focusing on other drugs in its portfolio. Following encouraging results from the Phase 2 TOUCHSTONE trial, a Phase 3 trial of the S1P modulator ozanimod in patients with moderate-to-severe ulcerative colitis is ongoing. Etrasimod is also being tested in a phase 2 trial in ulcerative colitis. These pipeline medications can be administered orally and may avoid the formation of anti-drug antibodies that can lead to treatment failure with injectable biologic therapies for IBD. Data from ongoing clinical trials will establish the relationship between the selectivity of S1P modulators and their safety and efficacy in IBD, as well as their potential place in the clinical armamentarium for IBD.

Topics: Humans; Inflammatory Bowel Diseases; Lysophospholipids; Sphingosine

An unmet medical need exists for the development of targeted therapies for the treatment of inflammatory bowel disease (IBD) with easily administered and stable oral drugs, particularly as most patients on biologics [i.e., tumor necrosis factor (TNF) inhibitors and anti-integrins] are either primary non-responders or lose responsiveness during maintenance treatment. A new class of small molecules, sphingosine-1-phosphate (S1P) receptor modulators, has recently shown efficacy in IBD. Here we provide an overview of the mechanism of action of this novel treatment principle in the context of intestinal inflammation. The remarkable impact of therapeutic modulation of the S1P/S1P receptor axis reflects the complexity of the pathogenesis of IBD and the fact that S1P receptor modulation may be a logical therapeutic approach for the future management of IBD.

Topics: Animals; Drug Discovery; Humans; Indans; Inflammatory Bowel Diseases; Lysophospholipids; Molecular Targeted Therapy; Oxadiazoles; Receptors, Lysosphingolipid; Signal Transduction; Small Molecule Libraries; Sphingosine

The gut is equipped with a unique immune system for maintaining immunological homeostasis, and its functional immune disruption can result in the development of immune diseases such as food allergy and intestinal inflammation. Accumulating evidence has demonstrated that nutritional components play an important role in the regulation of gut immune responses and also in the development of intestinal immune diseases. In this review, we focus on the immunological functions of lipids, vitamins, and nucleotides in the regulation of the intestinal immune system and as potential targets for the control of intestinal immune diseases.

Topics: Food; Food Hypersensitivity; Gastrointestinal Tract; Homeostasis; Humans; Inflammatory Bowel Diseases; Lipids; Lysophospholipids; Nucleotides; Nutritional Physiological Phenomena; Sphingosine; Vitamins

Present in the digestive system, sphingolipids are responsible for multiple important physiological and pathological processes. On the membrane of intestinal epithelial cells sphingolipids contribute to structural integrity, regulate absorption of nutrients and may act as receptors for some microorganisms and their toxins. Moreover, bioactive lipid messengers such as ceramide and sphingosine-1-phosphate influence cellular growth, differentiation and programmed cell death, apoptosis. Further studies are needed to fully explore the clinical implications of sphingolipids in neoplastic and inflammatory diseases in the gastrointestinal tract. Pharmacological compounds which regulate metabolism of sphingolipids can be potentially useful in treatment of colon cancer, inflammatory bowel diseases or nonalcoholic fatty liver disease. The aim of this work is to present a critical review of the physiological and pathological role of sphingolipids in the digestive system.

Topics: Apoptosis; Ceramides; Colonic Neoplasms; Gastrointestinal Diseases; Gastrointestinal Tract; Humans; Inflammatory Bowel Diseases; Intestinal Absorption; Lipid Metabolism; Lysophospholipids; Sphingolipids; Sphingosine

Sphingolipids are formed via the metabolism of sphingomyelin, a constituent of the plasma membrane, or by de novo synthesis. Enzymatic pathways result in the formation of several different lipid mediators, which are known to have important roles in many cellular processes, including proliferation, apoptosis and migration. Several studies now suggest that these sphingolipid mediators, including ceramide, ceramide 1-phosphate and sphingosine 1-phosphate (S1P), are likely to have an integral role in inflammation. This can involve, for example, activation of pro-inflammatory transcription factors in different cell types and induction of cyclooxygenase-2, leading to production of pro-inflammatory prostaglandins. The mode of action of each sphingolipid is different. Increased ceramide production leads to the formation of ceramide-rich areas of the membrane, which may assemble signalling complexes, whereas S1P acts via high-affinity G-protein-coupled S1P receptors on the plasma membrane. Recent studies have demonstrated that in vitro effects of sphingolipids on inflammation can translate into in vivo models. This review will highlight the areas of research where sphingolipids are involved in inflammation and the mechanisms of action of each mediator. In addition, the therapeutic potential of drugs that alter sphingolipid actions will be examined with reference to disease states, such as asthma and inflammatory bowel disease, which involve important inflammatory components. A significant body of research now indicates that sphingolipids are intimately involved in the inflammatory process and recent studies have demonstrated that these lipids, together with associated enzymes and receptors, can provide effective drug targets for the treatment of pathological inflammation.

Topics: Animals; Asthma; Ceramides; Humans; Inflammation; Inflammatory Bowel Diseases; Lysophospholipids; Prostaglandin-Endoperoxide Synthases; Sphingolipids; Sphingosine

Topics: Humans; Inflammatory Bowel Diseases; Lysophospholipids; Molecular Targeted Therapy; Signal Transduction; Sphingosine; Sphingosine-1-Phosphate Receptors

Topics: Humans; Inflammatory Bowel Diseases; Lysophospholipids; Molecular Targeted Therapy; Signal Transduction; Sphingosine; Sphingosine-1-Phosphate Receptors

Inflammatory bowel disease (IBD) is a common gastrointestinal disease in dogs. Decreased production of intestinal immunoglobulin A (IgA) has been suggested as a possible pathogenesis in a subset of canine IBD; however, the underlying cause remains unclear. Sphingosine-1-phosphate (S1P) is a lipid mediator that regulates intestinal IgA production by controlling lymphocyte trafficking in mice. The objectives of this study were to clarify the role of S1P in IgA production in dogs and to evaluate the expression of S1P-related molecules in dogs with IBD. First, an S1P receptor antagonist was administrated to five healthy dogs. The S1P receptor antagonist significantly decreased the IgA concentration in sera and feces but did not affect the IgG concentration. Moreover, the immunoreactivity of intestinal IgA was significantly decreased by S1P signal blockade. These results indicate that S1P signaling specifically regulates the intestinal IgA production in dogs. Subsequently, the intestinal S1P concentration and the expression of S1P-related molecules were measured in dogs with IBD and healthy dogs. The intestinal concentration of S1P was significantly lower in dogs with IBD than in healthy dogs. In addition, the gene expression levels of S1P receptor (S1P1) and S1P synthase (SK1) were significantly lower in dogs with IBD than in healthy dogs. Taken together, these observations suggest that decreased S1P production, likely caused by a lower expression of S1P synthetase, leads to attenuation of S1P/S1P1 signaling pathway and the production of intestinal IgA in dogs with IBD.

Topics: Animals; Dog Diseases; Dogs; Feces; Fingolimod Hydrochloride; Gene Expression; Immunoglobulin A; Inflammatory Bowel Diseases; Intestines; Lysophospholipids; Male; Sphingosine; Sphingosine 1 Phosphate Receptor Modulators; Sphingosine-1-Phosphate Receptors

Sphingosine 1 phosphate [S1P] is a bioactive lipid mediator involved in the regulation of several cellular processes though the activation of a G protein-coupled receptor family known as the S1P receptors [S1PRs]. Advances in the understanding of the biological activities mediated by S1PRs have sparked great interest in the S1P/S1PRs axes as new therapeutic targets for the modulation of several cellular processes. In particular, the S1P/S1PR1 axis has been identified as key regulator for lymphocyte migration from lymph nodes. The blockade of this axis is emerging as a new therapeutic approach to control the aberrant leukocyte migration into the mucosa in inflammatory bowel disease [IBD]. This review briefly summarises the current evidence coming from clinical studies, and discusses the future prospects of S1P inhibitors for treatment of inflammatory bowel disease.

Topics: Animals; Camphanes; Cell Movement; Fingolimod Hydrochloride; Humans; Immunosuppressive Agents; Indans; Inflammatory Bowel Diseases; Leukocytes; Lysophospholipids; Molecular Targeted Therapy; Oxadiazoles; Receptors, Lysosphingolipid; Signal Transduction; Sphingosine; Sulfhydryl Compounds; Sulfonamides

The aim of this study was to investigate gene expression levels of proteins involved in sphingosine-1-phosphate (S1P) metabolism and signaling in a pediatric inflammatory bowel disease (IBD) patient population.. IBD is a debilitating disease affecting 0.4% of the US population. The incidence of IBD in childhood is rising. Identifying effective targeted therapies that can be used safely in young patients and developing tools for selecting specific candidates for targeted therapies are important goals. Clinical IBD trials now underway target S1PR1, a receptor for the pro-inflammatory sphingolipid S1P. However, circulating and tissue sphingolipid levels and S1P-related gene expression have not been characterized in pediatric IBD.. Pediatric IBD patients and controls were recruited in a four-site study. Patients received a clinical score using PUCAI or PCDAI evaluation. Colon biopsies were collected during endoscopy. Gene expression was measured by qRT-PCR. Plasma and gut tissue sphingolipids were measured by LC-MS/MS.. Genes of S1P synthesis (SPHK1, SPHK2), degradation (SGPL1), and signaling (S1PR1, S1PR2, and S1PR4) were significantly upregulated in colon biopsies of IBD patients with moderate/severe symptoms compared with controls or patients in remission. Tissue ceramide, dihydroceramide, and ceramide-1-phosphate (C1P) levels were significantly elevated in IBD patients compared with controls.. A signature of elevated S1P-related gene expression in colon tissues of pediatric IBD patients correlates with active disease and normalizes in remission. Biopsied gut tissue from symptomatic IBD patients contains high levels of pro-apoptotic and pro-inflammatory sphingolipids. A combined analysis of gut tissue sphingolipid profiles with this S1P-related gene signature may be useful for monitoring response to conventional therapy.

Topics: Adolescent; Animals; Case-Control Studies; Ceramides; Child; Child, Preschool; Chromatography, Liquid; Colon; Female; Gene Expression; Humans; Infant; Inflammatory Bowel Diseases; Lysophospholipids; Male; Pilot Projects; Signal Transduction; Sphingosine; Tandem Mass Spectrometry; Young Adult

Colonic inflammation, a hallmark of inflammatory bowel disease, can be influenced by host intrinsic and extrinsic factors. There continues to be a need for models of colonic inflammation that can both provide insights into disease pathogenesis and be used to investigate potential therapies. Herein, we tested the utility of colonoscopic-guided pinch biopsies in mice for studying colonic inflammation and its treatment. Gene expression profiling of colonic wound beds after injury showed marked changes, including increased expression of genes important for the inflammatory response. Interestingly, many of these gene expression changes mimicked those alterations found in inflammatory bowel disease patients. Biopsy-induced inflammation was associated with increases in neutrophils, macrophages, and natural killer cells. Injury also led to elevated levels of sphingosine-1-phosphate (S1P), a bioactive lipid that is an important mediator of inflammation mainly through its receptor, S1P

Topics: Animals; Anti-Bacterial Agents; Biopsy; Cells, Cultured; Colon; Colonoscopy; Disease Models, Animal; Female; Gene Expression Profiling; Inflammation; Inflammatory Bowel Diseases; Intestinal Mucosa; Lysophospholipids; Male; Mice; Mice, Knockout; Microbiota; Receptors, Lysosphingolipid; Sphingosine; Sphingosine-1-Phosphate Receptors; Surgery, Computer-Assisted

Growing evidence supports a link between inflammation and cancer; however, mediators of the transition between inflammation and carcinogenesis remain incompletely understood. Sphingosine-1-phosphate (S1P) lyase (SPL) irreversibly degrades the bioactive sphingolipid S1P and is highly expressed in enterocytes but downregulated in colon cancer. Here, we investigated the role of SPL in colitis-associated cancer (CAC). We generated mice with intestinal epithelium-specific Sgpl1 deletion and chemically induced colitis and tumor formation in these animals. Compared with control animals, mice lacking intestinal SPL exhibited greater disease activity, colon shortening, cytokine levels, S1P accumulation, tumors, STAT3 activation, STAT3-activated microRNAs (miRNAs), and suppression of miR-targeted anti-oncogene products. This phenotype was attenuated by STAT3 inhibition. In fibroblasts, silencing SPL promoted tumorigenic transformation through a pathway involving extracellular transport of S1P through S1P transporter spinster homolog 2 (SPNS2), S1P receptor activation, JAK2/STAT3-dependent miR-181b-1 induction, and silencing of miR-181b-1 target cylindromatosis (CYLD). Colon biopsies from patients with inflammatory bowel disease revealed enhanced S1P and STAT3 signaling. In mice with chemical-induced CAC, oral administration of plant-type sphingolipids called sphingadienes increased colonic SPL levels and reduced S1P levels, STAT3 signaling, cytokine levels, and tumorigenesis, indicating that SPL prevents transformation and carcinogenesis. Together, our results suggest that dietary sphingolipids can augment or prevent colon cancer, depending upon whether they are metabolized to S1P or promote S1P metabolism through the actions of SPL.

Topics: Aldehyde-Lyases; Animals; Anion Transport Proteins; Biopsy; Cell Transformation, Neoplastic; Colonic Neoplasms; Down-Regulation; Gene Deletion; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; Humans; Inflammatory Bowel Diseases; Lysophospholipids; Mice; Mice, Transgenic; MicroRNAs; Neoplasm Proteins; Neoplasms, Experimental; RNA, Neoplasm; Signal Transduction; Sphingosine; STAT3 Transcription Factor

Sphingosine kinase 1 (SK1), one of two SK enzymes, is highly regulated and has been shown to act as a focal point for the action of many growth factors and cytokines. SK1 leads to generation of sphingosine-1-phosphate (S1P) and potentially the activation of S1P receptors to mediate biologic effects. Our previous studies implicated SK1/S1P in the regulation of inflammatory processes, specifically in inflammatory bowel disease (IBD). These studies were conducted using a total body knockout mouse for SK1 and were unable to determine the source of SK1/S1P (hematopoietic or extra-hematopoietic) involved in the inflammatory responses. Therefore, bone marrow transplants were performed with wild-type (WT) and SK1-/- mice and colitis induced with dextran sulfate sodium (DSS). Irrespective of the source of SK1/S1P, bone marrow or tissue, DSS induced colitis in all mice; however, mice lacking SK1 in both hematopoietic and extra-hematopoietic compartments exhibited decreased crypt damage. Systemic inflammation was assessed, and mice with WT bone marrow demonstrated significant neutrophilia in response to DSS. In the local inflammatory response, mice lacking SK1/S1P in either bone marrow or tissue exhibited decreased induction of cytokines and less activation of STAT3 (signal transducer and activator of transcription 3). Interestingly, we determined that extra-hematopoietic SK1 is necessary for the induction of cyclooxygenase 2 (COX2) in colon epithelium in response to DSS-induced colitis. Taken together our data suggest that hematopoietic-derived SK1/S1P regulates specific aspects of the systemic inflammatory response, while extra-hematopoietic SK1 in the colon epithelium is necessary for the autocrine induction of COX2 in DSS-induced colitis.

Topics: Animals; Colitis; Hematopoietic System; Inflammation; Inflammatory Bowel Diseases; Lysophospholipids; Mice; Mice, Inbred C57BL; Mice, Knockout; Phosphotransferases (Alcohol Group Acceptor); Receptors, Lysosphingolipid; Sphingosine

Pyridoxal-5-phosphate, the biologically active form of vitamin B6, is a cofactor for over 140 biochemical reactions. Although severe vitamin B6 deficiency is rare, mild inadequacy [plasma pyridoxal 5'-phosphate (PLP) <20 nmol/L] is observed in 19-27% of the US population. Plasma PLP concentrations are inversely related to markers of inflammation such as C-reactive protein. Furthermore, plasma PLP is diminished in those with inflammatory conditions and, in the case of inflammatory bowel disease (IBD), more so in those with active versus quiescent disease. Restricting B6 intake attenuates IBD pathology in mice; however, the effects of supplementation are unclear. We therefore sought to determine the effects of mild inadequacy and moderate supplementation of B6 on the severity of colonic inflammation. Weanling IL-10(-/-) (positive for Helicobacter hepaticus) mice were fed diets containing 0.5 (deficient), 6.0 (replete) or 24 (supplemented) mg/kg pyridoxine HCl for 12 weeks and then assessed for histological and molecular markers of colonic inflammation. Both low and high plasma PLP were associated with a significant suppression of molecular (TNFα, IL-6, IFN-γ, COX-2 and iNOS expression) and histological markers of inflammation in the colon. PLP is required for the breakdown of sphingosine 1-phosphate (S1P), a chemotactic lipid, by S1P lyase. Colonic concentrations of S1P and PLP were significantly and inversely correlated. If confirmed, vitamin B6 supplementation may offer an additional tool for the management of IBD. Although B6 is required in dozens of reactions, its role in the breakdown of S1P may explain the biphasic relationship observed between PLP and inflammation.

Topics: Animals; Biomarkers; C-Reactive Protein; Colon; Cyclooxygenase 2; Dietary Supplements; Disease Models, Animal; Female; Inflammatory Bowel Diseases; Interferon-gamma; Interleukin-10; Interleukin-6; Lysophospholipids; Male; Mice; Mice, Knockout; Nitric Oxide Synthase Type II; Sphingosine; Tumor Necrosis Factor-alpha; Vitamin B 6

Sphingosine kinase (Sphk) phosphorylates sphingosine into sphingosine-1-phosphate (S1P), but its recently identified isoform Sphk2 has been suggested to have distinct subcellular localization and substrate specificity. We demonstrate here that, surprisingly, Sphk2(-/-) CD4(+) T cells exhibit a hyperactivated phenotype with significantly enhanced proliferation and cytokine secretion in response to IL-2 as well as reduced sensitivity to regulatory T cell-mediated suppression in vitro, apparently independent of effects upon S1P. Such findings appear to reflect a requirement for Sphk2 to suppress IL-2 signaling because, in Sphk2(-/-) CD4(+) T cells, IL-2 induced abnormally accentuated STAT5 phosphorylation and small interfering RNA knockdown of STAT5 abrogated their hyperactive phenotype. This pathway physiologically modulates autoinflammatory responses, because Sphk2(-/-) T cells induced more rapid and robust inflammatory bowel disease in scid recipients. Thus, Sphk2 regulates IL-2 pathways in T cells, and the modulation of Sphk2 activity may be of therapeutic utility in inflammatory and/or infectious diseases.

Topics: Animals; Autoimmunity; Inflammatory Bowel Diseases; Interleukin-2; Intestinal Mucosa; Intestines; Lysophospholipids; Mice; Mice, Knockout; Phenotype; Phosphotransferases (Alcohol Group Acceptor); Signal Transduction; Sphingosine; T-Lymphocytes