FTY720 Suppresses Pathogenic Retinal Müller Cell Activation and Chronic Progression by Inhibiting the mTOR/NF-κB Signaling Pathway and Regulating Autophagy.

PURPOSE: FTY720 is an agonist of the Sphingosine-1-phosphate (S1P) receptor 1, 3, 4, and 5 and a functional antagonist of the S1P1 receptor; it can inhibit the activation of mTOR/NF-κB and has therapeutic potential in inflammatory disease. This study was designed to determine the role of the inflammatory process in diabetic retinopathy and investigate the effect of FTY720 on high glucose (HG)-induced rat retinal Müller cells (rMC-1 cells). METHODS: In the present study, the role of FTY720 in inhibiting inflammation and its underlying mechanism were investigated. rMC-1 cells were treated without or with HG, FTY720, CQ, or RAP. Cell viability was examined by CCK-8 assay; cell activation was assessed by western blot analysis and IF staining; and cell migration was evaluated by a scratch wound healing assay. The expression of inflammation-associated proteins and autophagy-related proteins was evaluated by transmission electron microscopy, AO staining, MDC-labeled autophagic vacuoles, western blot analysis and ELISA. RESULTS: Western blot analysis and IF staining showed that the level of the rMC-1 cell marker GFAP was decreased, while GS was increased in FTY720 groups compared to that in the HG group. The healing assay results showed that compared with HG treatment, FTY720 treatment significantly reduced cell migration. Western blot analysis, ELISA and IF staining showed that compared with HG, FTY720 reduced proinflammatory proteins by inhibiting the mechanistic target of the mTOR/NF-κB signaling pathway and regulating autophagy. CONCLUSIONS: This study suggests that in an HG-induced rMC-1 cell model, FTY720 significantly inhibited the production of inflammatory cytokines by inhibiting mTOR/NF-κB signaling and regulating autophagy. These findings were associated with a decrease in rMC-1 cell injury, suggesting that FTY720 or related compounds may be valuable modulators of HG-induced retinal injury.

1-Phosphate receptor agonists: A promising therapeutic avenue for ischemia-reperfusion injury management.

Ischemia-reperfusion injury (IRI) - a complex pathological condition occurring when blood supply is abruptly restored to ischemic tissues, leading to further tissue damage - poses a significant clinical challenge. Sphingosine-1-phosphate receptors (S1PRs), a specialized set of G-protein-coupled receptors comprising five subtypes (S1PR1 to S1PR5), are prominently present in various cell membranes, including those of lymphocytes, cardiac myocytes, and endothelial cells. Increasing evidence highlights the potential of targeting S1PRs for IRI therapeutic intervention. Notably, preconditioning and postconditioning strategies involving S1PR agonists like FTY720 have demonstrated efficacy in mitigating IRI. As the synthesis of a diverse array of S1PR agonists continues, with FTY720 being a prime example, the body of experimental evidence advocating for their role in IRI treatment is expanding. Despite this progress, comprehensive reviews delineating the therapeutic landscape of S1PR agonists in IRI remain limited. This review aspires to meticulously elucidate the protective roles and mechanisms of S1PR agonists in preventing and managing IRI affecting various organs, including the heart, kidney, liver, lungs, intestines, and brain, to foster novel pharmacological approaches in clinical settings.

The Effects of the S1P Receptor Agonist Fingolimod (FTY720) on Central and Peripheral Myelin in Twitcher Mice.

Krabbe's disease (KD) is caused by mutations in the lysosomal enzyme galactocerebrosidase and is associated with psychosine toxicity. The sphingosine 1-phosphate receptor (S1PR) agonist fingolimod (FTY720) attenuates psychosine-induced cell death of human astrocytes, demyelination in cerebellar slices, as well as demyelination in the central nervous system of twitcher mice. Psychosine also accumulates in the peripheral nervous system in twitcher mice; however, effects of fingolimod on this peripheral myelin have not been examined. The aim of this study was to investigate the effects of fingolimod administration on peripheral and central markers of myelination. Here, we report that fingolimod administration (1 mg/kg/day) from postnatal day 5 (PND) onwards did not alter peripheral demyelination in the sciatic nerve of twitcher mice, despite significantly reducing myelin debris, glial reactivity, and neuronal damage in the cerebellum. We also find fingolimod administration improves twitching and mobility scores in twitcher mice. Importantly, we find that fingolimod significantly increases the lifespan of twitcher mice by approximately 5 days. These findings suggest differential effects of fingolimod on peripheral and central neuropathy in twitcher mice, which may explain its modest efficacy on behavior and lifespan.

Platelet Membrane Nanocarriers Cascade Targeting Delivery System to Improve Myocardial Remodeling Post Myocardial Ischemia-Reperfusion Injury.

Although treatments for myocardial infarction have advanced significantly, the global mortality due to ischemia and subsequent reperfusion injury remains high. Here, a platelet (PLT) membrane nanocarrier (PL720) that encapsulates L-arginine and FTY720 to facilitate the cascade-targeted delivery of these substances to the myocardial injury site and enable the controlled release of L-arginine and FTY720 is developed. Such an innovative approach shows enhanced cardioprotection through multiple target strategies involved in ischemia-reperfusion injury and late reperfusion inflammation. During the ischemia-reperfusion phase, PL720 targets and accumulates in damaged coronary arteries. PL720 rapidly releases L-arginine, stimulating endothelial cells to produce NO, thereby dilating blood vessels and promoting blood flow recovery, while FTY720's sustained release exerts anti-apoptotic effects. During the late reperfusion inflammatory phase, PL720 is captured by circulating inflammatory monocytes and transported into a deeper ischemic myocardial lesion. PL720 promotes macrophage polarization and accelerates the inflammatory repair. Furthermore, the issue of bradycardia associated with the clinical use of FTY720 is innovatively relieved. Therefore, PL720 is a vascular injury and inflammation dual targeting strategy, exhibiting significant potential for multi-targeted therapy and clinical translation for cardiac injury.

The sphingosine 1-phosphate analogue, FTY720, modulates the lipidomic signature of the mouse hippocampus.

The small-molecule drug, FTY720 (fingolimod), is a synthetic sphingosine 1-phosphate (S1P) analogue currently used to treat relapsing-remitting multiple sclerosis in both adults and children. FTY720 can cross the blood-brain barrier (BBB) and, over time, accumulate in lipid-rich areas of the central nervous system (CNS) by incorporating into phospholipid membranes. FTY720 has been shown to enhance cell membrane fluidity, which can modulate the functions of glial cells and neuronal populations involved in regulating behaviour. Moreover, direct modulation of S1P receptor-mediated lipid signalling by FTY720 can impact homeostatic CNS physiology, including neurotransmitter release probability, the biophysical properties of synaptic membranes, ion channel and transmembrane receptor kinetics, and synaptic plasticity mechanisms. The aim of this study was to investigate how chronic FTY720 treatment alters the lipid composition of CNS tissue in adolescent mice at a key stage of brain maturation. We focused on the hippocampus, a brain region known to be important for learning, memory, and the processing of sensory and emotional stimuli. Using mass spectrometry-based lipidomics, we discovered that FTY720 increases the fatty acid chain length of hydroxy-phosphatidylcholine (PCOH) lipids in the mouse hippocampus. It also decreases PCOH monounsaturated fatty acids (MUFAs) and increases PCOH polyunsaturated fatty acids (PUFAs). A total of 99 lipid species were up-regulated in the mouse hippocampus following 3 weeks of oral FTY720 exposure, whereas only 3 lipid species were down-regulated. FTY720 also modulated anxiety-like behaviours in young mice but did not affect spatial learning or memory formation. Our study presents a comprehensive overview of the lipid classes and lipid species that are altered in the hippocampus following chronic FTY720 exposure and provides novel insight into cellular and molecular mechanisms that may underlie the therapeutic or adverse effects of FTY720 in the central nervous system.

Pharmacological Effects of FTY720 and its Derivatives.

FTY720 is an analog of sphingosine-1-phosphate (S1P) derived from the ascomycete Cordyceps sinensis. As a new immunosuppressant, FTY720 is widely used to treat multiple sclerosis. FTY720 binds to the S1P receptor after phosphorylation, thereby exerting immunosuppressive effects. The nonphosphorylated form of FTY720 can induce cell apoptosis, enhance chemotherapy sensitivity, and inhibit tumor metastasis of multiple tumors by inhibiting SPHK1 (sphingosine kinase 1) and activating PP2A (protein phosphatase 2A) and various cell death pathways. FTY720 can induce neutrophil extracellular traps to neutralize and kill pathogens in vitro, thus exerting anti- infective effects. At present, a series of FTY720 derivatives, which have pharmacological effects such as anti-tumor and alleviating airway hyperresponsiveness, have been developed through structural modification. This article reviews the pharmacological effects of FTY720 and its derivatives.

FTY720 Nanoformulation Induces O-GlcNacylation of Synuclein to Alleviate Synucleinopathy.

The post-translational modification and aggregation of alpha-synuclein are one of the major causes of Parkinson's disease (PD) regulation. In that, the phosphorylation and nitration of synuclein elevate the aggregation, while O-GlcNacylation prevents the aggregation of synuclein. The inhibition of synuclein aggregation directs the development of PD therapy. The endowed O-GlcNacylation of synuclein could be a promising strategy to inhibit synucleinopathy. Therefore, the neuroprotective chitosan-based FTY720 nanoformulation, PP2A (Protein phosphatase 2) activator has been employed to evaluate the PP2A role in the O-GlcNacylation of synuclein in an in vivo PD model. The neuroprotective effect of our nanoformulation is attributed to the upregulation of tyrosine hydroxylase (TH), the PD therapeutic target, with behavioral improvement in animals against rotenone-induced PD deficits. The neuroprotective molecular insights revealed the camouflaged role of PP2A by endowing the OGT activity that induces O-GlcNacylation of synuclein in the reduction of synucleinopathy.

Presynaptic Release-Regulating Sphingosine 1-Phosphate 1/3 Receptors in Cortical Glutamatergic Terminals: Adaptations in EAE Mice and Impact of Therapeutic FTY720.

This study provides evidence of the existence of presynaptic inhibitory sphingosine-1-phosphate receptor 1 (S1P1R) and facilitatory S1P3R in cortical nerve endings (synaptosomes) of healthy mice. The conclusion relies on the findings that (i) the S1P1R agonist CS-2100 (0.1-30 nM) inhibits the 12 mM KCl-evoked glutamate exocytosis (quantified as the release of [3H]D-aspartate) while the S1P3R allosteric agonist CYM-5541 potentiates it and (ii) these effects are inhibited by the S1P1R antagonist Ex 26 (30-300 nM) and the S1P3R antagonist TY-52156 (100-1000 nM), respectively. Confocal microscopy and western blot analysis confirmed the presence of S1P1R and S1P3R proteins in cortical glutamatergic synaptosomes, which were scarcely accessible to biotin in a biotinylation study. Then, we demonstrated that S1P1R and S1P3R densities and their release activity are amplified in cortical synaptosomes of mice suffering from experimental autoimmune encephalomyelitis (EAE), despite receptors maintain their preferential internal distribution. Receptor changes recover following chronic oral therapeutic FTY720 (0.03 mg/Kg/day). These results improve our knowledge of the role of presynaptic release-regulating S1P1Rs and S1P3Rs controlling glutamate transmission in the CNS also unravelling functional adaptations during EAE that recover following chronic FTY720. In a whole, these findings provide new information on the central neuroprotectant activities of FTY720.

Red-Light-Activatable AND-Gated Antitumor Immunosuppressant.

Immunosuppressants are emerging as promising candidates for cancer therapy with lower cytotoxicity compared to traditional chemotherapy drugs; yet, the intrinsic side effects such as immunosuppression remain a critical concern. Herein, we introduce a photoactivatable antitumor immunosuppressant called dmBODIPY-FTY720 (BF) that shows no cytotoxicity but can be temporally and locally activated by deep-red light illumination to induce tumor cell apoptosis. To further reduce potential side effects, we integrate BF with another classic photosensitizer called methylene blue (MB) that is activated under the same wavelength of deep-red light (>650 nm) and successfully establish a red-light-activatable AND Boolean logic gate through a mechanism that we found to be synergetic apoptotic induction. At further decreased dosages, deep-red light illumination does not induce cell death in the presence of either BF or MB, but significant cancer cell death is triggered in the presence of both drugs. Therefore, the dosage of BF is further reduced, which will be highly beneficial to minimize any potential side effects of BF. This AND-gated strategy has been successfully applied in vivo for effective suppression of hepatocarcinoma tumors in living mice.

A Preliminary Study of Pharmacokinetics and Pharmacodynamics of Oral Fingolimod in Dogs.

BACKGROUND/AIM: Fingolimod is a sphingosine-1-phosphate receptor modulator that prevents lymphocytes egress from lymphoid organs. It has been used as a disease-modifying drug for human multiple sclerosis and has shown better therapeutic effects than other conventional therapies. Therefore, this study was performed to obtain preclinical data of fingolimod in dogs. MATERIALS AND METHODS: Nine laboratory Beagle dogs were used and randomized into three groups for pharmacokinetics (PK) and pharmacodynamics (PD). The dogs were administered once with a low-dose (0.01 mg/kg, n=3), medium-dose (0.05 mg/kg, n=3), and high-dose (0.1 mg/kg, n=3) of fingolimod, orally. Samples were collected serially at predetermined time points, and whole blood fingolimod concentrations were measured using high-performance liquid chromatography-mass spectrometry. Differential counts of leukocytes over time were determined to identify immune cells' response to fingolimod. RESULTS: Regarding PK, the concentration of fingolimod in the blood increased in a dose-dependent manner, but it was not proportional. Regarding PD, the number of lymphocytes significantly decreased compared to baseline in all dose groups (low-dose, p=0.0002; medium-dose, p<0.0001; high-dose, p=0.0012). Eosinophils were significantly reduced in low- (p=0.0006) and medium- (p=0.0006) doses, and neutrophils were also significantly reduced in medium-(p=0.0345) and high- (p=0.0016) doses. CONCLUSION: This study provides the basis for future clinical applications of fingolimod in dogs with immune-mediated diseases, such as meningoencephalitis of unknown etiology.

FTY720 attenuates acute colitis via colonic T cells reduction and inhibition of M1 macrophages polarization independent of CCR2-mediated monocytes input.

Ulcerative colitis (UC) is a complex multifactorial disease, of which the exact etiology is not fully understood. The inappropriate aggressive inflammatory response is closely related to the disease progression of UC. FTY720 is a sphingosine-1-phosphate receptor agonist and acts as a key immunomodulator in inflammation. This study aims to investigate the protective influence of FTY720 on inflammation in the DSS-induced colitis model. In the present study, the C57BL/6 mice and the CCR2-/- mice were exposed to 5% Dextran Sodium Sulfate (DSS) drinking water for 6 days followed by an injection of FTY720 (1 mg/kg/d) or vehicle (PBS) 6 times starting on the next day. The body weight, stool consistency, and occult blood were assessed daily. The inflammatory cytokines level in colon tissues and serum were assessed. Leukocyte subsets of bone marrow (BM), spleen, and colon were analyzed by flow cytometry. Our results demonstrated that FTY720 ameliorated the aberrant immune responses by trapping T cells and inhibiting the polarization of M1 macrophages in colitis mice. The effect of FTY720 on the increased number of colonic macrophages did not dependent on CCR2-mediated monocyte influx, despite most monocytes being reduced after DSS administration in the inflamed colon of CCR2-/- mice. Rather, depletion of CCR2 did not impact the protective influence of FTY720 on colonic injury in acute colitis. All these findings unravel a beneficial function of FTY720 in the inflammatory response to DSS-induced acute colitis, provided further insights into monocyte migration and might provide potential opportunities for UC therapeutic intervention.

Bifunctional Hydrogel-Integrated 3D Printed Scaffold for Repairing Infected Bone Defects.

The clinical treatment of infectious bone defects is difficult and time-consuming due to the coexistence of infection and bone defects, and the simultaneous control of infection and repair of bone defects is considered a promising therapy. In this study, a dual-drug delivery scaffold system was fabricated by the combination of a three-dimensional (3D) printed scaffold with hydrogel for infected bone defects repair. The 3D printed polycaprolactone scaffold was incorporated with biodegradable mesoporous silica nanoparticles containing the small molecular drug fingolimod (FTY720) to provide structural support and promote angiogenesis and osteogenesis. The vancomycin (Van)-loaded hydrogel was prepared from aldehyde hyaluronic acid (AHA) and carboxymethyl chitosan (NOCC) by the Schiff base reaction, which can fill the pores of the 3D-printed scaffold to produce a bifunctional composite scaffold. The in vitro results demonstrated that the composite scaffold had Van concentration-dependent antimicrobial properties. Furthermore, the FTY720-loaded composite scaffold demonstrated excellent biocompatibility, vascularization, and osteogenic ability in vitro. In the rat femoral defect model with bacterial infection, the dual-drug composite scaffold showed a better outcome in both infection control and bone regeneration compared to other groups. Therefore, the prepared bifunctional composite scaffold has potential application in the treatment of infected bone defects.

The impact of fingolimod on Treg function in brain ischaemia.

Fingolimod has generally shown neuroprotective effects in stroke models. Here, we tested the hypothesis that fingolimod modulates T-cell cytokine production towards a regulatory phenotype. Second, we investigated how fingolimod altered the Treg suppressive function and the sensitivity of effector T cells to regulation. Mice that had underwent the permanent electrocoagulation of the left middle cerebral artery received saline or fingolimod (0.5 mg/kg) daily for 10-days post-ischaemia. Fingolimod improved neurobehavioural recovery compared to saline control and increased Treg frequency in the periphery and brain. Tregs from fingolimod-treated animals had a higher expression of CCR8. Fingolimod increased the frequencies of CD4+ IL-10+ , CD4+ IFN-γ+ and CD4+ IL-10+ IFN-γ+ cells in spleen and blood, and CD4+ IL-17+ cells in the spleen, with only minor effects on CD8+ T-cell cytokine production. Treg from post-ischaemic mice had reduced suppressive function compared to Treg from non-ischaemic mice. Fingolimod treatment rescued this function against saline-treated but not fingolimod-treated CD4+ effector T cells. In conclusion, fingolimod seems to improve the suppressive function of Treg post-stroke while also increasing the resistance of CD4+ effector cells to this suppression. Fingolimod's capacity to increase both effector and regulatory functions may explain the lack of consistent improvement in functional recovery in experimental brain ischaemia.

Targeting p21-activated kinase 1 for development of a novel anti-arrhythmic drug class.

Evidence accumulated over the past decade suggests that p21-activated kinase 1 (PAK1) is a critical cardiac-protective signalling molecule. The present article provides an updated review of recent findings regarding the role of PAK1 in maintaining normal cardiac electrophysiological function through its regulation of membrane and Ca2+ clocks. We first overviewed the PAK1 activation mechanism. We then discussed recent updated results showing the action mechanisms of PAK1 signalling on Cav1.2/Cav1.3 (ICaL)-mediated Ca2+ entry, ryanodine receptor type 2-mediated sarcoplasmic reticulum (SR) Ca2+ release, transcriptional regulation of SR Ca2+-ATPase 2a, Na+/Ca2+ exchangers, and Ca2+/calmodulin-dependent protein kinase II. Finally, we proposed a new and exciting route for developing a PAK1-based therapeutic strategy for cardiac arrhythmias. This article is part of the theme issue 'The heartbeat: its molecular basis and physiological mechanisms'.

Targeting L-Selectin Lymphocytes to Deliver Immunosuppressive Drug in Lymph Nodes for Durable Multiple Sclerosis Treatment.

Inflammation induced by autoreactive CD4+ T lymphocytes is a major factor in the pathogenesis of multiple sclerosis (MS). Immunosuppressive drugs, such as FTY720, are subsequently developed to prevent the migration of CD4+ T lymphocytes to the central nervous system (CNS). However, these immunosuppressive drugs have limited accumulation in lymph nodes (LNs), resulting in poor efficacy. Here, this work develops a nanoplatform for delivering immunosuppressive drugs to LNs for durable MS treatment. Human CD47 peptide and L-selectin targeting aptamer are modified on the nanoparticles encapsulated with FTY720 (clnFTY) for self-passivation and the targeting of L-selectin on lymphocytes, a homing receptor for T-cells entering LNs. Using this natural process, clnFTY nanoparticles efficiently deliver FTY720 to LNs and delay disease progression in experimental autoimmune encephalomyelitis (EAE) mice following a single dose treatment over a 42-day observational period. Considering the daily dosing requirement of FTY720, this strategy greatly improves its therapeutic efficiency. The ability of clnFTY nanoparticles to target lymphocytes, reduce sphingosine-1-phosphate receptor 1 (S1PR1) expression, and suppress inflammatory cytokines release are demonstrated in clinical blood samples from MS patients. Taken together, this study demonstrates that targeted LNs delivery may greatly extend the treatment cycle of immunosuppressive drugs for durable MS treatment.

FTY720 in immuno-regenerative and wound healing technologies for muscle, epithelial and bone regeneration.

In 2010, the FDA approved the administration of FTY720, S1P lipid mediator, as a therapy to treat relapsing forms of multiple sclerosis. FTY720 was found to sequester pro-inflammatory lymphocytes within the lymph node, preventing them from causing injury to the central nervous system due to inflammation. Studies harnessing the anti-inflammatory properties of FTY720 as a pro-regenerative strategy in wound healing of muscle, bone and mucosal injuries are currently being performed. This in-depth review discusses the current regenerative impact of FTY720 due to its anti-inflammatory effect stratified into an assessment of wound regeneration in the muscular, skeletal, and epithelial systems. The regenerative effect of FTY720 in vivo was characterized in three animal models, with differing delivery mechanisms emerging in the last 20 years. In these studies, local delivery of FTY720 was found to increase pro-regenerative immune cell phenotypes (neutrophils, macrophages, monocytes), vascularization, cell proliferation and collagen deposition. Delivery of FTY720 to a localized wound environment demonstrated increased bone, muscle, and mucosal regeneration through changes in gene and cytokine production primarily by controlling the local immune cell phenotypes. These changes in gene and cytokine production reduced the inflammatory component of wound healing and increased the migration of pro-regenerative cells (neutrophils and macrophages) to the wound site. The application of FTY720 delivery using a biomaterial has demonstrated the ability of local delivery of FTY720 to promote local wound healing leveraging an immunomodulatory mechanism.

FTY-720 alleviates diabetes-induced liver injury by inhibiting oxidative stress and inflammation.

We aimed to investigate the protective effect of FTY-720 on liver injury and explore its potential mechanism in diabetic mice. The diabetic mouse model was induced with streptozotocin and FTY-720 was administered for 12 weeks. We assayed biocharacters and liver function and used histopathology staining to evaluate the protective effects of FTY-720 against diabetic liver injury. Levels of oxidative stress and inflammation in the liver were observed. mRNA and protein levels of essential enzymes for glucose metabolism were quantified in the liver and the protein expression of TLR4, HIF1α and NF-κB was determined. In vivo results revealed that FTY-720 significantly lowered blood glucose and lipids and improved liver function and alleviated liver fibrosis in diabetic mice. FTY-720 reduced oxidative stress and inflammation, with the increased catalase activity and reduced levels of malondialdehyde, myeloperoxidase, IL-1ß, IL-6, TNF-α, TGF-ß, and MCP1. Furthermore, FTY-720 modulated glucose metabolism in liver and elevated the ATP production, showing the promotion of glycogenesis and glycolysis and inhibition of gluconeogenesis. Moreover, FTY-720 inhibited the expression of TLR4 and HIF1α, contributing to restoration of liver function. In conclusion, FTY-720 ameliorates diabetes-induced liver injury and improves glucose homeostasis by inhibiting oxidative stress and inflammation and may be a promise drug for treatment of liver disease.

Repurposing drugs against Alzheimer's disease: can the anti-multiple sclerosis drug fingolimod (FTY720) effectively tackle inflammation processes in AD?

Therapeutic approaches providing effective medication for Alzheimer's disease (AD) patients after disease onset are urgently needed. Previous studies in AD mouse models and in humans suggested that physical exercise or changed lifestyle can delay AD-related synaptic and memory dysfunctions when treatment started in juvenile animals or in elderly humans before onset of disease symptoms. However, a pharmacological treatment that can reverse memory deficits in AD patients was thus far not identified. Importantly, AD disease-related dysfunctions have increasingly been associated with neuro-inflammatory mechanisms and searching for anti-inflammatory medication to treat AD seems promising. Like for other diseases, repurposing of FDA-approved drugs for treatment of AD is an ideally suited strategy to reduce the time to bring such medication into clinical practice. Of note, the sphingosine-1-phosphate analogue fingolimod (FTY720) was FDA-approved in 2010 for treatment of multiple sclerosis patients. It binds to the five different isoforms of Sphingosine-1-phosphate receptors (S1PRs) that are widely distributed across human organs. Interestingly, recent studies in five different mouse models of AD suggest that FTY720 treatment, even when starting after onset of AD symptoms, can reverse synaptic deficits and memory dysfunction in these AD mouse models. Furthermore, a very recent multi-omics study identified mutations in the sphingosine/ceramide pathway as a risk factor for sporadic AD, suggesting S1PRs as promising drug target in AD patients. Therefore, progressing with FDA-approved S1PR modulators into human clinical trials might pave the way for these potential disease modifying anti-AD drugs.

FTY720-P, a Biased S1PR Ligand, Increases Mitochondrial Function through STAT3 Activation in Cardiac Cells.

FTY720 is an FDA-approved sphingosine derivative drug for the treatment of multiple sclerosis. This compound blocks lymphocyte egress from lymphoid organs and autoimmunity through sphingosine 1-phosphate (S1P) receptor blockage. Drug repurposing of FTY720 has revealed improvements in glucose metabolism and metabolic diseases. Studies also demonstrate that preconditioning with this compound preserves the ATP levels during cardiac ischemia in rats. The molecular mechanisms by which FTY720 promotes metabolism are not well understood. Here, we demonstrate that nanomolar concentrations of the phosphorylated form of FTY720 (FTY720-P), the active ligand of S1P receptor (S1PR), activates mitochondrial respiration and the mitochondrial ATP production rate in AC16 human cardiomyocyte cells. Additionally, FTY720-P increases the number of mitochondrial nucleoids, promotes mitochondrial morphology alterations, and induces activation of STAT3, a transcription factor that promotes mitochondrial function. Notably, the effect of FTY720-P on mitochondrial function was suppressed in the presence of a STAT3 inhibitor. In summary, our results suggest that FTY720 promotes the activation of mitochondrial function, in part, through a STAT3 action.

Effect of FTY-720 on Pulmonary Fibrosis in Mice via the TGF-ß1 Signaling Pathway and Autophagy.

We investigated whether FTY-720 might have an effect on bleomycin-induced pulmonary fibrosis through inhibiting TGF-ß1 pathway, and up-regulating autophagy. The pulmonary fibrosis was induced by bleomycin. FTY-720 (1 mg/kg) drug was intraperitoneally injected into mice. Histological changes and inflammatory factors were observed, and EMT and autophagy protein markers were studied by immunohistochemistry and immunofluorescence. The effects of bleomycin on MLE-12 cells were detected by MTT assay and flow cytometry, and the related molecular mechanisms were studied by Western Blot. FTY-720 considerably attenuated bleomycin-induced disorganization of alveolar tissue, extracellular collagen deposition, and α-SMA and E-cadherin levels in mice. The levels of IL-1ß, TNF-α, and IL-6 cytokines were attenuated in bronchoalveolar lavage fluid, as well as protein content and leukocyte count. COL1A1 and MMP9 protein expressions in lung tissue were significantly reduced. Additionally, FTY-720 treatment effectively inhibited the expressions of key proteins in TGF-ß1/TAK1/P38MAPK pathway and regulated autophagy proteins. Similar results were additionally found in cellular assays with mouse alveolar epithelial cells. Our study provides proof for a new mechanism for FTY-720 to suppress pulmonary fibrosis. FTY-720 is also a target for treating pulmonary fibrosis.