Mitigation of myocardial ischemia/reperfusion-induced chronic heart failure via Shexiang Baoxin Pill-mediated regulation of the S1PR1 signaling pathway.

BACKGROUND: Well-defined and effective pharmacological interventions for clinical management of myocardial ischemia/reperfusion (MI/R) injury are currently unavailable. Shexiang Baoxin Pill (SBP), a traditional Chinese medicine Previous research on SBP has been confined to single-target treatments for MI/R injury, lacking a comprehensive examination of various aspects of MI/R injury and a thorough exploration of its underlying mechanisms. PURPOSE: This study aimed to investigate the therapeutic potential of SBP for MI/R injury and its preventive effects on consequent chronic heart failure (CHF). Furthermore, we elucidated the specific mechanisms involved, contributing valuable insights into the potential pharmacological interventions for the clinical treatment of MI/R injury. METHODS: We conducted a comprehensive identification of SBP components using high-performance liquid chromatography. Subsequently, we performed a network pharmacology analysis based on the identification results, elucidating the key genes influenced by SBP. Thereafter, through bioinformatics analysis of the key genes and validation through mRNA and protein assays, we ultimately determined the centralized upstream targets. Lastly, we conducted in vitro experiments using myocardial and endothelial cells to elucidate and validate potential underlying mechanisms. RESULTS: SBP can effectively mitigate cell apoptosis, oxidative stress, and inflammation, as well as promote vascular regeneration following MI/R, resulting in improved cardiac function and reduced CHF risk. Mechanistically, SBP treatment upregulates sphingosine-1-phosphate receptor 1 (S1PR1) expression and activates the S1PR1 signaling pathway, thereby regulating the expression of key molecules, including phosphorylated Protein Kinase B (AKT), phosphorylated signal transducer and activator of transcription 3, epidermal growth factor receptor, vascular endothelial growth factor A, tumor necrosis factor-α, and p53. CONCLUSION: This study elucidated the protective role of SBP in MI/R injury and its potential to reduce the risk of CHF. Furthermore, by integrating downstream effector proteins affected by SBP, this research identified the upstream effector protein S1PR1, enhancing our understanding of the pharmacological characteristics and mechanisms of action of SBP. The significance of this study lies in providing compelling evidence for the use of SBP as a traditional Chinese medicine for MI/R injury and consequent CHF prevention.

The coumarin component isofraxidin targets the G-protein-coupled receptor S1PR1 to modulate IL-17 signaling and alleviate ulcerative colitis.

OBJECTIVE: The increasing global prevalence of ulcerative colitis (UC) underscores the imperative to explore novel therapeutic approaches. Traditional Chinese medicine has historically shown potential in addressing this ailment. The current study aimed to elucidate the functional attributes and underlying mechanisms of isofraxidin, a coumarin derivative from Acanthopanax, in the context of UC. METHODS: A murine model of dextran sodium sulfate (DSS)-induced UC was established, and we conducted a comprehensive assessment of the influence of isofraxidin on UC symptomatology, colonic histopathological manifestations, the inflammatory response, and apoptosis. The potential receptor of isofraxidin was initially identified through the Target database and molecular docking analysis. Subsequent in vivo and in vitro experiments were conducted to determine the effects of isofraxidin on the identified receptor and associated signaling pathways. Transfection was used to examine the receptor's role in the regulatory mechanism of isofraxidin. RESULTS: Isofraxidin reduced UC symptoms and colonic histopathological impairments. Furthermore, isofraxidin ameliorated the DSS-induced inflammatory response and apoptosis in tissues. S1PR1 was identified as a target of isofraxidin and effectively suppressed activation of the IL-17 signaling pathway. Intriguingly, cellular experiments indicated that overexpression of S1PR1 counteracted the protective effect of isofraxidin. DISCUSSION: In summary, our investigation revealed that isofraxidin could modulate S1PR1 and regulate the IL-17 signaling pathway, thus ameliorating DSS-induced UC. These findings establish a robust foundation for considering isofraxidin as a prospective therapeutic intervention to treat UC.

Sphingosine-1-phosphate and ceramide-1-phosphate promote migration, pro-inflammatory and pro-fibrotic responses in retinal pigment epithelium cells.

Retinal pigment epithelium (RPE) cells, essential for preserving retina homeostasis, also contribute to the development of retina proliferative diseases, through their exacerbated migration, epithelial to mesenchymal transition (EMT) and inflammatory response. Uncovering the mechanisms inducing these changes is crucial for designing effective treatments for these pathologies. Sphingosine-1-phosphate (S1P) and ceramide-1-phosphate (C1P) are bioactive sphingolipids that promote migration and inflammation in several cell types; we recently established that they stimulate the migration of retina Müller glial cells (Simón et al., 2015; Vera et al., 2021). We here analyzed whether S1P and C1P regulate migration, inflammation and EMT in RPE cells. We cultured two human RPE cell lines, ARPE-19 and D407 cells, and supplemented them with either 5 µM S1P or 10 µM C1P, or their vehicles, for 24 h. Analysis of cell migration by the scratch wound assay showed that S1P addition significantly enhanced migration in both cell lines. Pre-treatment with W146 and BML-241, antagonists for S1P receptor 1 (S1P1) and 3 (S1P3), respectively, blocked exogenous S1P-induced migration. Inhibiting sphingosine kinase 1 (SphK1), the enzyme involved in S1P synthesis, significantly reduced cell migration and exogenous S1P only partially restored it. Addition of C1P markedly stimulated cell migration. Whereas inhibiting C1P synthesis did not affect C1P-induced migration, inhibiting S1P synthesis strikingly decreased it; noteworthy, addition of C1P promoted the transcription of SphK1. These results suggest that S1P and C1P stimulate RPE cell migration and their effect requires S1P endogenous synthesis. Both S1P and C1P increase the transcription of pro-inflammatory cytokines IL-6 and IL-8, and of EMT marker α-smooth muscle actin (α-SMA) in ARPE-19 cells. Collectively, our results suggest new roles for S1P and C1P in the regulation of RPE cell migration and inflammation; since the deregulation of sphingolipid metabolism is involved in several proliferative retinopathies, targeting their metabolism might provide new tools for treating these pathologies.

RTN4/Nogo-A-S1PR2 negatively regulates angiogenesis and secondary neural repair through enhancing vascular autophagy in the thalamus after cerebral cortical infarction.

Cerebral infarction induces angiogenesis in the thalamus and influences functional recovery. The mechanisms underlying angiogenesis remain unclear. This study aimed to investigate the role of RTN4/Nogo-A in mediating macroautophagy/autophagy and angiogenesis in the thalamus following middle cerebral artery occlusion (MCAO). We assessed secondary neuronal damage, angiogenesis, vascular autophagy, RTN4 and S1PR2 signaling in the thalamus. The effects of RTN4-S1PR2 on vascular autophagy and angiogenesis were evaluated using lentiviral and pharmacological approaches. The results showed that RTN4 and S1PR2 signaling molecules were upregulated in parallel with angiogenesis in the ipsilateral thalamus after MCAO. Knockdown of Rtn4 by siRNA markedly reduced MAP1LC3B-II conversion and levels of BECN1 and SQSTM1 in vessels, coinciding with enhanced angiogenesis in the ipsilateral thalamus. This effect coincided with rescued neuronal loss of the thalamus and improved cognitive function. Conversely, activating S1PR2 augmented vascular autophagy, along with suppressed angiogenesis and aggravated neuronal damage of the thalamus. Further inhibition of autophagic initiation with 3-methyladenine or spautin-1 enhanced angiogenesis while blockade of lysosomal degradation by bafilomycin A1 suppressed angiogenesis in the ipsilateral thalamus. The control of autophagic flux by RTN4-S1PR2 was verified in vitro. Additionally, ROCK1-BECN1 interaction along with phosphorylation of BECN1 (Thr119) was identified in the thalamic vessels after MCAO. Knockdown of Rtn4 markedly reduced BECN1 phosphorylation whereas activating S1PR2 increased its phosphorylation in vessels. These results suggest that blockade of RTN4-S1PR2 interaction promotes angiogenesis and secondary neural repair in the thalamus by suppressing autophagic activation and alleviating dysfunction of lysosomal degradation in vessels after cerebral infarction.Abbreviations: 3-MA: 3-methyladenine; ACTA2/ɑ-SMA: actin alpha 2, smooth muscle, aorta; AIF1/Iba1: allograft inflammatory factor 1; BafA1: bafilomycin A1; BMVECs: brain microvascular endothelial cells; BrdU: 5-bromo-2'-deoxyuridine; CLDN11/OSP: claudin 11; GFAP: glial fibrillary acidic protein; HUVECs: human umbilical vein endothelial cells; LAMA1: laminin, alpha 1; MAP2: microtubule-associated protein 2; MBP2: myelin basic protein 2; MCAO: middle cerebral artery occlusion; PDGFRB/PDGFRß: platelet derived growth factor receptor, beta polypeptide; RECA-1: rat endothelial cell antigen-1; RHOA: ras homolog family member A; RHRSP: stroke-prone renovascular hypertensive rats; ROCK1: Rho-associated coiled-coil containing protein kinase 1; RTN4/Nogo-A: reticulon 4; RTN4R/NgR1: reticulon 4 receptor; S1PR2: sphingosine-1-phosphate receptor 2; SQSTM1: sequestosome 1.

Berberine ameliorates erectile dysfunction in rats with streptozotocin-induced diabetes mellitus through the attenuation of apoptosis by inhibiting the SPHK1/S1P/S1PR2 and MAPK pathways.

BACKGROUND: The population with diabetes mellitus-induced erectile dysfunction is increasing rapidly, but current drugs are not effective in treating erectile dysfunction. Studies of the traditional Chinese medicine extract berberine on diabetes and its complications provide us with new ideas. OBJECTIVES: To evaluate the therapeutic effect and potential mechanism of berberine on the erectile function of diabetic rats. MATERIALS AND METHODS: Fifty male Sprague-Dawley rats were randomly grouped, and 42 rats were injected intraperitoneally with streptozotocin to establish a diabetes model. Erectile dysfunction rats were screened out through the apomorphine test and randomly divided into the diabetes mellitus and berberine groups, and these animals were administered berberine (200 mg/kg/day) and normal saline by gavage for 4 weeks. Primary corpus cavernous smooth muscle cells from healthy rats were cultured and treated with berberine. RESULTS: Fasting blood glucose in the diabetes mellitus group was significantly increased, while berberine showed no significant effect on glucose. Erectile function was obviously impaired in the diabetes mellitus group, and berberine administration partially rescued this impairment. The expression of sphingosine kinase 1, S1PR2, and sphingosine-1-phosphate in the diabetes mellitus group was increased. Berberine partially inhibited the expression of sphingosine kinase 1 and S1PR2, but the decrease in sphingosine-1-phosphate was not significant. Moreover, mitogen-activated protein kinase pathway factor expression was upregulated and eNOS activity was decreased in the diabetes mellitus group. Berberine treatment could partially reverse these alterations. Severe fibrosis and apoptosis were detected in diabetic rats, accompanied by higher expression of TGFß1, collagen I/IV, Bax/Bcl-2, and caspase 3 than in the other groups. However, supplementation with berberine inhibited the expression of these proteins and attenuated fibrosis and apoptosis. CONCLUSIONS: Berberine ameliorated erectile dysfunction in rats with diabetes mellitus, possibly by improving endothelial function and inhibiting apoptosis and fibrosis by suppressing the sphingosine kinase 1/sphingosine-1-phosphate/S1PR2 and mitogen-activated protein kinase pathways.

Inhibition of Sphingosine-1-Phosphate Receptor 2 by JTE013 Promoted Osteogenesis by Increasing Vesicle Trafficking, Wnt/Ca2+, and BMP/Smad Signaling.

Sphingosine-1-phosphate receptor 2 (S1PR2) is a G protein-coupled receptor that regulates various immune responses. Herein, we determine the effects of a S1PR2 antagonist (JTE013) or a S1PR2 shRNA on osteogenesis by culturing murine bone marrow stromal cells (BMSCs) in osteogenic media with JTE013, dimethylsulfoxide (DMSO), a S1PR2 shRNA, or a control shRNA. Treatment with JTE013 or the S1PR2 shRNA increased alkaline phosphatase and alizarin red s staining, and enhanced alkaline phosphatase, RUNX2, osteocalcin, and osterix mRNA levels in BMSCs compared with the controls. Protein analysis revealed that a high dose of JTE013 (4 or 8 µM) increased vesicle trafficking-associated proteins (F-actin, clathrin, Early Endosome Antigen 1 (EEA1), and syntaxin 6) and Wnt/Ca2+ signaling. On the other hand, a low dose of JTE013 (1 to 2 µM) increased BMP/Smad signaling. In contrast, the S1PR2 shRNA reduced vesicle trafficking-associated proteins and attenuated Wnts and BMP/Smad signaling, but enhanced p-CaMKII compared with the control, suggesting that the S1PR2 shRNA influenced osteogenesis via different signaling pathways. Moreover, inhibiting protein trafficking by brefeldin A in BMSCs suppressed Wnts and BMPRs expressions. These data supported that enhanced osteogenesis in JTE013-treated BMSCs is associated with increased vesicle trafficking, which promotes the synthesis and transport of osteogenic protein and matrix vesicles and enhances matrix mineralization.

Geniposide downregulates the VEGF/SphK1/S1P pathway and alleviates angiogenesis in rheumatoid arthritis in vivo and in vitro.

The VEGF/SphK1/S1P pathway is closely related to angiogenesis in rheumatoid arthritis (RA), but the precise underlying mechanisms are unclear at present. Here, we explored the involvement of the VEGF/SphK1/S1P cascade in RA models and determined the effects of GE intervention. Our results showed abnormal expression of proteins related to this pathway in RA synovial tissue. Treatment with GE effectively regulated the signal axis, inhibited angiogenesis, and alleviated RA symptoms. In vitro, TNF-ɑ enhanced the VEGF/SphK1/S1P pathway in a co-culture model of fibroblast-like synoviocytes (FLS) and vascular endothelial cells (VEC). GE induced downregulation of VEGF in FLS, restored the dynamic balance of pro-/antiangiogenic factors, and suppressed SphK1/S1P signaling in VEC, resulting in lower proliferation activity, migration ability, tube formation ability, and S1P secretion ability of VEC cells. Additionally, SphK1-specific small interfering RNA (siRNA) blocked the VEGF/SphK1/S1P cascade, which can effectively alleviate the stimulatory effect of FLS on VEC and further enhanced the therapeutic effect of GE. Taken together, our results demonstrate that GE suppresses the VEGF/SphK1/S1P pathway and alleviates the stimulation of VEC by FLS, thereby preventing angiogenesis and promoting therapeutic effects against RA.

JTE-013 Alleviates Inflammatory Injury and Endothelial Dysfunction Induced by Sepsis In Vivo and In Vitro.

BACKGROUND: Nowadays, there is no approved targeted agent for lung injury induced by sepsis. S1PR2 is confirmed to be a promising diagnosis and treatment target. JTE-013 as S1PR2 antagonists may be an agent of great potential. In this research, we sought to determine the functional role of JTE-013 in lung injury induced by sepsis. MATERIALS AND METHODS: Seventy-two rats were assigned into normal group, sepsis model group and JTE-013 group. The animal model of lung injury induced by sepsis was constructed by cecal ligation and puncture. The human pulmonary microvascular endothelial cells (HPMECs) were divided into control, LPS and LPS + JTE-013 group. HPMECs induced by LPS served as the cell model of lung injury induced by sepsis. HE staining assay was performed for assessment of the pathological condition and Evans blue was applied for assessment of pulmonary tissue permeability. Wet/dry ratio was measured as indicators of pulmonary edema degree and neutrophil count was measured as indicators of infection status. The levels of inflammatory factors were detected by corresponding kits, cell survival by CCK-8 assay and protein expression level by western blot. RESULTS: S1PR2 was highly expressed in vivo model of lung injury induced by sepsis. It was observed that JTE-013 as antagonist of S1PR2 alleviated the lung tissue injury, endothelial dysfunction and pulmonary edema induced by sepsis. In addition, JTE-013 reduced neutrophil count and levels of inflammatory factors. Moreover, results confirmed that JTE-013 enhanced cell viability and mitigated inflammatory response in cell model of sepsis. CONCLUSIONS: Overall, JTE-013 as an antagonist of S1PR2 could relieve inflammatory injury and endothelial dysfunction induced by sepsis in vivo and vitro, resulting in attenuation of lung injury. These findings elucidated that JTE-013 may be a promising targeted agent for lung injury induced by sepsis.

Targeting S1PRs as a Therapeutic Strategy for Inflammatory Bone Loss Diseases-Beyond Regulating S1P Signaling.

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.

Preclinical and Clinical Evidence for the Involvement of Sphingosine 1-Phosphate Signaling in the Pathophysiology of Vascular Cognitive Impairment.

Sphingosine 1-phosphates (S1Ps) are bioactive lipids that mediate a diverse range of effects through the activation of cognate receptors, S1P1-S1P5. Scrutiny of S1P-regulated pathways over the past three decades has identified important and occasionally counteracting functions in the brain and cerebrovascular system. For example, while S1P1 and S1P3 mediate proinflammatory effects on glial cells and directly promote endothelial cell barrier integrity, S1P2 is anti-inflammatory but disrupts barrier integrity. Cumulatively, there is significant preclinical evidence implicating critical roles for this pathway in regulating processes that drive cerebrovascular disease and vascular dementia, both being part of the continuum of vascular cognitive impairment (VCI). This is supported by clinical studies that have identified correlations between alterations of S1P and cognitive deficits. We review studies which proposed and evaluated potential mechanisms by which such alterations contribute to pathological S1P signaling that leads to VCI-associated chronic neuroinflammation and neurodegeneration. Notably, S1P receptors have divergent but overlapping expression patterns and demonstrate complex interactions. Therefore, the net effect produced by S1P represents the cumulative contributions of S1P receptors acting additively, synergistically, or antagonistically on the neural, vascular, and immune cells of the brain. Ultimately, an optimized therapeutic strategy that targets S1P signaling will have to consider these complex interactions.

Sphingosine 1-Phosphate Receptors in Cerebral Ischemia.

Sphingosine 1-phosphate (S1P) is an important lipid biomolecule that exerts pleiotropic cellular actions as it binds to and activates its five G-protein-coupled receptors, S1P1-5. Through these receptors, S1P can mediate diverse biological activities in both healthy and diseased conditions. S1P is produced by S1P-producing enzymes, sphingosine kinases (SphK1 and SphK2), and is abundantly present in different organs, including the brain. The medically important roles of receptor-mediated S1P signaling are well characterized in multiple sclerosis because FTY720 (Gilenya™, Novartis), a non-selective S1P receptor modulator, is currently used as a treatment for this disease. In cerebral ischemia, its role is also notable because of FTY720's efficacy in both rodent models and human patients with cerebral ischemia. In particular, some of the S1P receptors, including S1P1, S1P2, and S1P3, have been identified as pathogenic players in cerebral ischemia. Other than these receptors, S1P itself and S1P-producing enzymes have been shown to play certain roles in cerebral ischemia. This review aims to compile the current updates and overviews about the roles of S1P signaling, along with a focus on S1P receptors in cerebral ischemia, based on recent studies that used in vivo rodent models of cerebral ischemia.

Anti-inflammatory Efficacy of Combined Natural Alkaloid Berberine and S1PR Modulator Fingolimod at Low Doses in Ulcerative Colitis Preclinical Models.

The natural alkaloid berberine is being studied as a drug candidate for the treatment of ulcerative colitis (UC). Fingolimod is an immunomodulator approved for the treatment of multiple sclerosis. Whether fingolimod use can be extended to UC and how it interacts with berberine remain unclear. In the present study, the anti-inflammatory efficacies of berberine, fingolimod, and a combination of half-doses of them was examined in mice with dextran sulfate sodium-induced colitis. In mice with subchronic colitis, 14-day oral administration of fingolimod had greater efficacy than berberine in ameliorating the disease clinical severity and colon shortening. However, in mice with chronic colitis, 30-day oral administration of berberine was more effective than fingolimod except on splenic swelling. Notably, the combination of half-doses of each drug was equally effective as the superior single drugs for two models and resulted in reduced splenic swelling in the chronic colitis model. The inhibition of cytokine expression and STAT3 activation, as well as binding to the sphingosine 1-phosphate receptor by both drugs, contributed to the combination efficacy. Our findings suggest that fingolimod in combination with berberine at reduced doses represents a novel therapy for UC that attains satisfactory efficacy with reduced potentials for adverse effects.

Floralozone Ameliorated Atherosclerosis in Experimental Atherosclerotic Rats Involved with Sphingosine 1-Phosphate 1 Enhancement.

Atherosclerosis (AS) is a chronical pathological process of the arterial narrows due to the AS plaque formation. The aim of this study was to explore the therapeutic effect and the underlying mechanism of Floralozone on experimental atherosclerotic model rats. Experimental atherosclerotic model rats were induced by the right carotid artery balloon injury and intraperitoneal injection of vitamin D3 in rats after 4 weeks high-fat diet. The results exhibited that Floralozone could ameliorate vascular injury and vasorelaxation of descending aortas and increase the superoxide dismutase activity and the expression of sphingosine 1-phosphate (S1P) 1 and reduce the intercellular cell adhesion molecule-1, vascular cell adhesion molecule-1, interleukin (IL)-1, IL-6 level, and the malondialdehyde activity in experimental atherosclerotic rats. However, Fingolimod, an S1P1 inhibitor, could reverse these Floralozone effects in experimental atherosclerotic rats. Our results indicated that Floralozone could inhibit the atherosclerotic plaque formation and improves arterial stenosis and reduces endothelial dysfunction in experimental atherosclerotic rats, which might be involved with S1P1 enhancement.

Small molecule oral targeted therapies in ulcerative colitis.

The incidence and prevalence of ulcerative colitis are increasing globally. Although the exact cause and pathogenesis of this disease is unclear, research has led to a better understanding of the condition and to identification of new targets for therapy, which in turn has encouraged the development of new therapies. As well as biologic therapies, which have changed the way inflammatory bowel disease is managed, small molecules have been developed for the treatment of ulcerative colitis. These small molecule treatments are orally administered and are likely to bring a substantial shift in the way this chronic disease is treated. Oral therapies offer many advantages over infusion therapies, such as ease of use, increased acceptability by patients, and reduction of cost. This Review focuses not only on oral therapies that have been approved for use in ulcerative colitis, but also on those that are in development, providing a comprehensive overview for clinicians of available oral therapies and drugs that are likely to become available. We have also reviewed drugs that have shown promise in preclinical studies and could be effective future therapies.

SPHK1 deficiency protects mice from acetaminophen-induced ER stress and mitochondrial permeability transition.

Acetaminophen (APAP) is the leading cause of drug-induced acute liver failure. Sphingosine-1-phosphate (S1P), whose formation is catalyzed by sphingosine kinase (SPHK)-1 or -2, is a bioactive lipid implicated in human health and disease. Here, we show that APAP-treated sphK1-deficient (sphK1-/-) mice exhibited markedly less liver damage and reduced inflammation compared with the wild-type mice. SPHK1 deficiency alleviated APAP-induced endoplasmic reticulum (ER) stress by affecting the phosphorylation of inositol-requiring enzyme 1α (IRE1α) and protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK)-eukaryotic translation initiation factor 2α (eIF2α), levels of activating transcription factor 4 (ATF4), and activation of activating transcription factor 6 (ATF6). SPHK1 deficiency also inhibited mitochondrial permeability transition (MPT), as evidenced by the impaired phosphorylation of JNK, apoptosis signal-regulated kinase 1 (ASK1), and glycogen synthase kinase 3ß (GSK3ß). In addition, SPHK1 deficiency reduced the levels of histone deacetylase and promoted the acetylation of p65 and STAT1, thereby impairing the transcription of inflammatory genes. Supplementation with exogenous S1P significantly reversed the activation of the PERK-eIF2α-ATF4 pathway and ATF6 during ER stress as well as the activation of GSK3ß, ASK1, and JNK during MPT. Both FTY720, a functional S1P receptor antagonist, and PF543, an SPHK1 inhibitor, significantly ameliorated APAP-induced liver injury and improved animal survival. Our study reveals a critical role for SPHK1 in mediating APAP-induced hepatotoxicity by promoting ER stress and MPT.

Targeting the S1P receptor signaling pathways as a promising approach for treatment of autoimmune and inflammatory diseases.

The past two decades of intense research have revealed a key role of the sphingolipid molecule sphingosine 1-phosphate (S1P) in regulating multiple physiological and pathophysiological processes including cell proliferation and survival, cell migration, inflammatory mediator synthesis and tissue remodeling. S1P mainly acts through five high-affinity G protein-coupled S1P receptors, which are ubiquitously expressed and mediate a complex network of signaling in a cell type dependent manner. S1P receptors have become an attractive pharmacological target to interfere with S1P-mediated cellular responses, which contribute to various autoimmune and inflammatory diseases. Pioneering in this field was the synthesis of FTY720 (fingolimod, Gilenya®) from myriocin, one of the metabolites of the fungus Isaria sinclairii known from traditional Chinese medicine for its antibacterial and energy boosting effect. Fingolimod turned out as a very potent immunomodulatory agent that subsequently passed all clinical trials successfully and is now approved for the treatment of relapsing-remitting multiple sclerosis. Pharmacologically, fingolimod was characterized as a non-selective agonist of all of the S1P receptors (S1PR), with the exception of S1P2, and in addition, as a selective S1P1 functional antagonist by induction of irreversible S1P1 internalization and degradation. Since proper lymphocyte trafficking depends on the expression of S1P1 on lymphocytes, the degradation of S1P1 leads to trapping and accumulation of lymphocytes in secondary lymphoid tissue, and consequently to a depletion of lymphocytes from the blood. Novel S1PR modulators are now being developed with a more selective receptor activation profile and improved pharmacokinetic characteristics. In this review, we will summarize the state-of-the-art approaches that target directly or indirectly S1P signaling and may be useful as novel strategies to treat autoimmune and inflammatory diseases.

Beneficial Effects of Fingolimod in Alzheimer's Disease: Molecular Mechanisms and Therapeutic Potential.

Alzheimer's disease (AD), the most common cause of dementia remains of unclear etiology with current pharmacological therapies failing to halt disease progression. Several pathophysiological mechanisms have been implicated in AD pathogenesis including amyloid-ß protein (Aß) accumulation, tau hyperphosphorylation, neuroinflammation and alterations in bioactive lipid metabolism. Sphingolipids, such as sphingosine-1-phosphate (S1P) and intracellular ceramide/S1P balance are highly implicated in central nervous system physiology as well as in AD pathogenesis. FTY720/Fingolimod, a structural sphingosine analog and S1P receptor (S1PR) modulator that is currently used in the treatment of relapsing-remitting multiple sclerosis (RRMS) has been shown to exert beneficial effects on AD progression. Recent in vitro and in vivo evidence indicate that fingolimod may suppress Aß secretion and deposition, inhibit apoptosis and enhance brain-derived neurotrophic factor (BDNF) production. Furthermore, it regulates neuroinflammation, protects against N-methyl-D-aspartate (NMDA)-excitotoxicity and modulates receptor for advanced glycation end products signaling axis that is highly implicated in AD pathogenesis. This review discusses the underlying molecular mechanisms of the emerging neuroprotective role of fingolimod in AD and its therapeutic potential, aiming to shed more light on AD pathogenesis as well as direct future treatment strategies.

Vascular modulation through exercise improves chemotherapy efficacy in Ewing sarcoma.

Recent studies in mouse models of cancer have shown that exercise improves tumor vascular function, thereby improving chemotherapy delivery and efficacy. However, the mechanisms underlying this improvement remain unclear and the effect of exercise on Ewing sarcoma (ES), a pediatric bone and soft tissue cancer, is unknown. The effect of exercise on tumor vascular hyperpermeability, which inversely correlates with drug delivery to the tumor, has also not been evaluated. We hypothesized that exercise improves chemotherapy efficacy by enhancing its delivery through improving tumor vascular permeability. We treated ES-bearing mice with doxorubicin with or without moderate treadmill exercise. Exercise did not significantly alter ES tumor vessel morphology. However, compared to control mice, tumors of exercised mice had significantly reduced hyperpermeability, significantly decreased hypoxia, and higher doxorubicin penetration. Compared to doxorubicin alone, doxorubicin plus exercise inhibited tumor growth more efficiently. We evaluated endothelial cell sphingosine-1-phosphate receptors 1 and 2 (S1PR1 and S1PR2) as potential mediators of the improved vascular permeability and increased function afforded by exercise. Relative to tumors from control mice, vessels in tumors from exercised mice had increased S1PR1 and decreased S1PR2 expression. Our results support a model in which exercise remodels ES vasculature to reduce vessel hyperpermeability, potentially via modulation of S1PR1 and S1PR2, thereby improving doxorubicin delivery and inhibiting tumor growth more than doxorubicin alone does. Our data suggest moderate aerobic exercise should be tested in clinical trials as a potentially useful adjuvant to standard chemotherapy for patients with ES.

Sphingosine-1-phosphate receptor 1 activation in astrocytes contributes to neuropathic pain.

Neuropathic pain afflicts millions of individuals and represents a major health problem for which there is limited effective and safe therapy. Emerging literature links altered sphingolipid metabolism to nociceptive processing. However, the neuropharmacology of sphingolipid signaling in the central nervous system in the context of chronic pain remains largely unexplored and controversial. We now provide evidence that sphingosine-1-phosphate (S1P) generated in the dorsal horn of the spinal cord in response to nerve injury drives neuropathic pain by selectively activating the S1P receptor subtype 1 (S1PR1) in astrocytes. Accordingly, genetic and pharmacological inhibition of S1PR1 with multiple antagonists in distinct chemical classes, but not agonists, attenuated and even reversed neuropathic pain in rodents of both sexes and in two models of traumatic nerve injury. These S1PR1 antagonists retained their ability to inhibit neuropathic pain during sustained drug administration, and their effects were independent of endogenous opioid circuits. Moreover, mice with astrocyte-specific knockout of S1pr1 did not develop neuropathic pain following nerve injury, thereby identifying astrocytes as the primary cellular substrate of S1PR1 activity. On a molecular level, the beneficial reductions in neuropathic pain resulting from S1PR1 inhibition were driven by interleukin 10 (IL-10), a potent neuroprotective and anti-inflammatory cytokine. Collectively, our results provide fundamental neurobiological insights that identify the cellular and molecular mechanisms engaged by the S1PR1 axis in neuropathic pain and establish S1PR1 as a target for therapeutic intervention with S1PR1 antagonists as a class of nonnarcotic analgesics.