Ozanimod (RPC1063), a selective S1PR1 and S1PR5 modulator, reduces chronic inflammation and alleviates kidney pathology in murine systemic lupus erythematosus

Neuroprotective mechanisms of A-971432: Targeting S1PR5 to modulate PI3K/Akt and MAPK pathways in cerebral ischemia/reperfusion injury

The regulation of sphingosine 1-phosphate receptor 5 (S1PR5) expression has been implicated in the pathogenesis of several neurological disorders. However, the role of the S1PR5 agonist A-971432 in cerebral ischemia/reperfusion (CI/R) injury remains unclear. In this study, we observed that the expression of S1PR5 elevated after middle cerebral artery occlusion (MCAO) in a mouse model. We administered S1PR5 intraperitoneally at a dose of 0.1 mg/kg for three consecutive days after MCAO to investigate the potential effects of A-971432. Our in vivo experiments revealed that A-971432 significantly mitigated neurological deficits and infarct volume, ameliorated neuronal injury in the ischemic cortex and hippocampus, and suppressed apoptosis and inflammatory responses. Mechanistically, A-971432 activated the PI3K/Akt/mTOR signaling pathway and inhibited the P38/ERK/JNK pathway, suggesting that both the PI3K/Akt and MAPK pathways are involved in the anti-inflammatory and anti-apoptotic effects of A-971432 in CI/R injury. Additionally, we constructed AAV-shRNA-S1pr5 viruses and found that silencing S1pr5 significantly exacerbated neuronal apoptosis and inflammatory responses in CI/R mice, exacerbating neurological deficits and expanding infarct volume. Based on these findings, we conclude that A-971432 mitigates CI/R injury-induced apoptosis and inflammatory responses through the PI3K/Akt and MAPK pathways, and S1PR5 can serve as a promising therapeutic target for ischemic stroke treatment.

Sphingolipid signaling in kidney diseases

Sphingolipids are a family of bioactive lipids. The key components include ceramides, ceramide-1-phosphate, sphingosine, and sphingosine-1-phosphate. Sphingolipids were originally considered to be primarily structural elements of cell membranes but were later recognized as bioactive signaling molecules that play diverse roles in cellular behaviors such as cell differentiation, migration, proliferation, and death. Studies have demonstrated changes in key components of sphingolipids in the kidneys under different conditions and their important roles in the renal function and the pathogenesis of various kidney diseases. This review summarizes the most recent advances in the role of sphingolipid signaling in kidney diseases.

The contribution of the sphingosine 1-phosphate signaling pathway to chronic kidney diseases: recent findings and new perspectives

Chronic kidney disease (CKD) is a multifactorial condition with diverse etiologies, such as diabetes mellitus, hypertension, and genetic disorders, often culminating in end-stage renal disease (ESRD). A hallmark of CKD progression is kidney fibrosis, characterized by the excessive accumulation of extracellular matrix components, for which there is currently no effective anti-fibrotic therapy. Recent literature highlights the critical role of sphingosine 1-phosphate (S1P) signaling in CKD pathogenesis and renal fibrosis. This review provides an in-depth analysis of the latest findings on S1P metabolism and signaling in renal fibrosis and in specific CKDs, including diabetic nephropathy (DN), lupus nephritis (LN), focal segmental glomerulosclerosis (FSGS), Fabry disease (FD), and IgA nephropathy (IgAN). Emerging studies underscore the therapeutic potential of modulating S1P signaling with receptor modulators and inhibitors, such as fingolimod (FTY720) and more selective agents like ozanimod and cenerimod. Additionally, the current knowledge about the effects of established kidney protective therapies such as glucocorticoids and SGLT2 and ACE inhibitors on S1P signaling will be summarized. Furthermore, the review highlights the potential role of S1P as a biomarker for disease progression in CKD models, particularly in Fabry disease and diabetic nephropathy. Advanced technologies, including spatial transcriptomics, are further refining our understanding of S1P's role within specific kidney compartments. Collectively, these insights emphasize the need for continued research into S1P signaling pathways as promising targets for CKD treatment strategies.

Screening and identification of key biomarkers associated with endometriosis using bioinformatics and next-generation sequencing data analysis

Background

Endometriosis is a common cause of endometrial-type mucosa outside the uterine cavity with symptoms such as painful periods, chronic pelvic pain, pain with intercourse and infertility. However, the early diagnosis of endometriosis is still restricted. The purpose of this investigation is to identify and validate the key biomarkers of endometriosis.

Methods

Next-generation sequencing dataset GSE243039 was obtained from the Gene Expression Omnibus database, and differentially expressed genes (DEGs) between endometriosis and normal control samples were identified. After screening of DEGs, gene ontology (GO) and REACTOME pathway enrichment analyses were performed. Furthermore, a protein–protein interaction (PPI) network was constructed and modules were analyzed using the Human Integrated Protein–Protein Interaction rEference database and Cytoscape software, and hub genes were identified. Subsequently, a network between miRNAs and hub genes, and network between TFs and hub genes were constructed using the miRNet and NetworkAnalyst tool, and possible key miRNAs and TFs were predicted. Finally, receiver operating characteristic curve analysis was used to validate the hub genes.

Results

A total of 958 DEGs, including 479 upregulated genes and 479 downregulated genes, were screened between endometriosis and normal control samples. GO and REACTOME pathway enrichment analyses of the 958 DEGs showed that they were mainly involved in multicellular organismal process, developmental process, signaling by GPCR and muscle contraction. Further analysis of the PPI network and modules identified 10 hub genes, including vcam1, snca, prkcb, adrb2, foxq1, mdfi, actbl2, prkd1, dapk1 and actc1. Possible target miRNAs, including hsa-mir-3143 and hsa-mir-2110, and target TFs, including tcf3 (transcription factor 3) and clock (clock circadian regulator), were predicted by constructing a miRNA-hub gene regulatory network and TF-hub gene regulatory network.

Conclusions

This investigation used bioinformatics techniques to explore the potential and novel biomarkers. These biomarkers might provide new ideas and methods for the early diagnosis, treatment and monitoring of endometriosis.

S1P/S1PR1 axis promotes macrophage M1 polarization through NLRP3 inflammasome activation in Lupus nephritis

Lupus nephritis (LN) is a common complication of systemic lupus erythematosus (SLE) as well as the leading cause of mortality in patients. Previous studies revealed that S1P level is elevated in plasma samples of SLE patients and murine lupus models. FTY720, targeting S1P receptors, exhibited therapeutic effects in improving the nephritis symptoms of lupus mouse models. However, few studies have discussed the potential relevance of S1P/S1PR to the pathogenesis of LN. Macrophages have been shown to be an important causative agent of renal inflammation, while the pro-inflammatory M1-type promotes kidney injury and inflammation during LN. Importantly, macrophages express various S1P receptors, and how they respond to S1P in the setting of LN remains unclear. Therefore, we examined the level of S1P in the lupus MRL/lpr mice and explored the ensuing interaction of macrophages and S1P. We found that S1P level was elevated in the MRL/lpr mice with a subsequent enhancement of the S1PR1 expression, and blocking S1PR1 by FTY720, the nephritis symptoms of MRL/lpr mice were improved. Mechanistically, we demonstrated that elevated S1P level increase the M1-type macrophage accumulation. And the in-vitro studies proved that S1P/S1PR1 was involved in the promotion of macrophage polarization towards M1 type through activation of NLRP3 inflammasome. These findings confer a novel role to macrophage S1PR1 and provide a new perspective for targeting S1P during LN.

Targeted Small Molecules for Systemic Lupus Erythematosus: Drugs in the Pipeline

Despite the uncertainty of the pathogenesis of systemic lupus erythematosus, novel small molecules targeting specific intracellular mechanisms of immune cells are being developed to reverse the pathophysiological processes. These targeted molecules have the advantages of convenient administration, lower production costs, and the lack of immunogenicity. The Janus kinases, Bruton's tyrosine kinases, and spleen tyrosine kinases are important enzymes for activating downstream signals from various receptors on immune cells that include cytokines, growth factor, hormones, Fc, CD40, and B-cell receptors. Suppression of these kinases impairs cellular activation, differentiation, and survival, leading to diminished cytokine actions and autoantibody secretion. Intracellular protein degradation by immunoproteasomes, levered by the cereblon E3 ubiquitin ligase complex, is an essential process for the regulation of cellular functions and survival. Modulation of the immunoproteasomes and cereblon leads to depletion of long-lived plasma cells, reduced plasmablast differentiation, and production of autoantibodies and interferon-α. The sphingosine 1-phosphate/sphingosine 1-phosphate receptor-1 pathway is responsible for lymphocyte trafficking, regulatory T-cell/Th17 cell homeostasis, and vascular permeability. Sphingosine 1-phosphate receptor-1 modulators limit the trafficking of autoreactive lymphocytes across the blood-brain barrier, increase regulatory T-cell function, and decrease production of autoantibodies and type I interferons. This article summarizes the development of these targeted small molecules in the treatment of systemic lupus erythematosus, and the future prospect for precision medicine.

Evaluation of advanced, pathophysiologic new targets for imaging of CNS

The inadequate information about the in vivo pathological, physiological, and neurological impairments, as well as the absence of in vivo tools for assessing brain penetrance and the efficiency of newly designed drugs, has hampered the development of new techniques for the treatment for variety of new central nervous system (CNS) diseases. The searching sites such as Science Direct and PubMed were used to find out the numerous distinct tracers across 16 CNS targets including tau, synaptic vesicle glycoprotein, the adenosine 2A receptor, the phosphodiesterase enzyme PDE10A, and the purinoceptor, among others. Among the most encouraging are [¹⁸ F]FIMX for mGluR imaging, [¹¹ C]Martinostat for Histone deacetylase, [¹⁸ F]MNI-444 for adenosine 2A imaging, [¹¹ C]ER176 for translocator protein, and [¹⁸ F]MK-6240 for tau imaging. We also reviewed the findings for each tracer's features and potential for application in CNS pathophysiology and therapeutic evaluation investigations, including target specificity, binding efficacy, and pharmacokinetic factors. This review aims to present a current evaluation of modern positron emission tomography tracers for CNS targets, with a focus on recent advances for targets that have newly emerged for imaging in humans.

Ceramides in Autoimmune Rheumatic Diseases: Existing Evidence and Therapeutic Considerations for Diet as an Anticeramide Treatment

Autoimmune rheumatic diseases (AIRDs) constitute a set of connective tissue disorders and dysfunctions with akin clinical manifestations and autoantibody responses. AIRD treatment is based on a comprehensive approach, with the primary aim being achieving and attaining disease remission, through the control of inflammation. AIRD therapies have a low target specificity, and this usually propels metabolic disturbances, dyslipidemias and increased cardiovascular risk. Ceramides are implicated in inflammation through several different pathways, many of which sometimes intersect. They serve as signaling molecules for apoptosis, altering immune response and driving endothelial dysfunction and as regulators in the production of other molecules, including sphingosine 1-phosphate (S1P) and ceramide 1-phosphate (C1P). With lipid metabolism being severely altered in AIRD pathology, several studies show that the concentration and variety of ceramides in human tissues is altered in patients with rheumatic diseases compared to controls. As a result, many in vitro and some in vivo (animal) studies research the potential use of ceramides as therapeutic targets in rheumatoid arthritis (RA), ankylosing spondylitis, systemic lupus erythematosus, fibromyalgia syndrome, primary Sjögren's syndrome, systemic sclerosis, myositis, systemic vasculitis and psoriatic arthritis. Furthermore, the majority of ceramide synthesis is diet-centric and, as a result, dietary interventions may alter ceramide concentrations in the blood and affect health. Subsequently, more recently several clinical trials evaluated the possibility of distinct dietary patterns and nutrients to act as anti-ceramide regimes in humans. With nutrition being an important component of AIRD-related complications, the present review details the evidence regarding ceramide levels in patients with AIRDs, the results of anti-ceramide treatments and discusses the possibility of using medical nutritional therapy as a complementary anti-ceramide treatment in rheumatic disease.

Sphingosine-1-Phosphate (S1P) and S1P Signaling Pathway Modulators, from Current Insights to Future Perspectives

Sphingosine-1-phosphate (S1P) and S1P receptors (S1PR) are bioactive lipid molecules that are ubiquitously expressed in the human body and play an important role in the immune system. S1P-S1PR signaling has been well characterized in immune trafficking and activation in both innate and adaptive immune systems. Despite this knowledge, the full scope in the pathogenesis of autoimmune disorders is not well characterized yet. From the discovery of fingolimod, the first S1P modulator, until siponimod, the new molecule recently approved for the treatment of secondary progressive multiple sclerosis (SPMS), there has been a great advance in understanding the S1P functions and their involvement in immune diseases, including multiple sclerosis (MS). Modulation on S1P is an interesting target for the treatment of various autoimmune disorders. Improved understanding of the mechanism of action of fingolimod has allowed the development of the more selective second-generation S1PR modulators. Subtype 1 of the S1PR (S1PR1) is expressed on the cell surface of lymphocytes, which are known to play a major role in MS pathogenesis. The understanding of S1PR1’s role facilitated the development of pharmacological strategies directed to this target, and theoretically reduced the safety concerns derived from the use of fingolimod. A great advance in the MS treatment was achieved in March 2019 when the Food and Drug Association (FDA) approved Siponimod, for both active secondary progressive MS and relapsing–remitting MS. Siponimod became the first oral disease modifying therapy (DMT) specifically approved for active forms of secondary progressive MS. Additionally, for the treatment of relapsing forms of MS, ozanimod was approved by FDA in March 2020. Currently, there are ongoing trials focused on other new-generation S1PR1 modulators. This review approaches the fundamental aspects of the sphingosine phosphate modulators and their main similarities and differences.

Sphingosine 1-phosphate receptor-targeted therapeutics in rheumatic diseases

Sphingosine 1-phosphate (S1P), which acts via G protein-coupled S1P receptors (S1PRs), is a bioactive lipid essential for vascular integrity and lymphocyte trafficking. The S1P-S1PR signalling axis is a key component of the inflammatory response in autoimmune rheumatic diseases. Several drugs that target S1PRs have been approved for the treatment of multiple sclerosis and inflammatory bowel disease and are under clinical testing for patients with systemic lupus erythematosus (SLE). Preclinical studies support the hypothesis that targeting the S1P-S1PR axis would be beneficial to patients with SLE, rheumatoid arthritis (RA) and systemic sclerosis (SSc) by reducing pathological inflammation. Whereas most preclinical research and development efforts are focused on reducing lymphocyte trafficking, protective effects of circulating S1P on endothelial S1PRs, which maintain the vascular barrier and enable blood circulation while dampening leukocyte extravasation, have been largely overlooked. In this Review, we take a holistic view of S1P-S1PR signalling in lymphocyte and vascular pathobiology. We focus on the potential of S1PR modulators for the treatment of SLE, RA and SSc and summarize the rationale, pathobiology and evidence from preclinical models and clinical studies. Improved understanding of S1P pathobiology in autoimmune rheumatic diseases and S1PR therapeutic modulation is anticipated to lead to efficacious and safer management of these diseases.

Lipids in Liver Failure Syndromes: A Focus on Eicosanoids, Specialized Pro-Resolving Lipid Mediators and Lysophospholipids

Lipids are organic compounds insoluble in water with a variety of metabolic and non-metabolic functions. They not only represent an efficient energy substrate but can also act as key inflammatory and anti-inflammatory molecules as part of a network of soluble mediators at the interface of metabolism and the immune system. The role of endogenous bioactive lipid mediators has been demonstrated in several inflammatory diseases (rheumatoid arthritis, inflammatory bowel disease, atherosclerosis, cancer). The liver is unique in providing balanced immunotolerance to the exposure of bacterial components from the gut transiting through the portal vein and the lymphatic system. This balance is abruptly deranged in liver failure syndromes such as acute liver failure and acute-on-chronic liver failure. In these syndromes, researchers have recently focused on bioactive lipid mediators by global metabonomic profiling and uncovered the pivotal role of these mediators in the immune dysfunction observed in liver failure syndromes explaining the high occurrence of sepsis and subsequent organ failure. Among endogenous bioactive lipids, the mechanistic actions of three classes (eicosanoids, pro-resolving lipid mediators and lysophospholipids) in the pathophysiological modulation of liver failure syndromes will be the topic of this narrative review. Furthermore, the therapeutic potential of lipid-immune pathways will be described.

A Rheostat of Ceramide and Sphingosine-1-Phosphate as a Determinant of Oxidative Stress-Mediated Kidney Injury

Reactive oxygen species (ROS) modulate sphingolipid metabolism, including enzymes that generate ceramide and sphingosine-1-phosphate (S1P), and a ROS-antioxidant rheostat determines the metabolism of ceramide-S1P. ROS induce ceramide production by activating ceramide-producing enzymes, leading to apoptosis, while they inhibit S1P production, which promotes survival by suppressing sphingosine kinases (SphKs). A ceramide-S1P rheostat regulates ROS-induced mitochondrial dysfunction, apoptotic/anti-apoptotic Bcl-2 family proteins and signaling pathways, leading to apoptosis, survival, cell proliferation, inflammation and fibrosis in the kidney. Ceramide inhibits the mitochondrial respiration chain and induces ceramide channel formation and the closure of voltage-dependent anion channels, leading to mitochondrial dysfunction, altered Bcl-2 family protein expression, ROS generation and disturbed calcium homeostasis. This activates ceramide-induced signaling pathways, leading to apoptosis. These events are mitigated by S1P/S1P receptors (S1PRs) that restore mitochondrial function and activate signaling pathways. SphK1 promotes survival and cell proliferation and inhibits inflammation, while SphK2 has the opposite effect. However, both SphK1 and SphK2 promote fibrosis. Thus, a ceramide-SphKs/S1P rheostat modulates oxidant-induced kidney injury by affecting mitochondrial function, ROS production, Bcl-2 family proteins, calcium homeostasis and their downstream signaling pathways. This review will summarize the current evidence for a role of interaction between ROS-antioxidants and ceramide-SphKs/S1P and of a ceramide-SphKs/S1P rheostat in the regulation of oxidative stress-mediated kidney diseases.

Cenerimod, a selective S1P1 receptor modulator, improves organ-specific disease outcomes in animal models of Sjögren's syndrome

Background

Sjögren’s syndrome is a systemic autoimmune disease characterized by immune cells predominantly infiltrating the exocrine glands and frequently forming ectopic lymphoid structures. These structures drive a local functional immune response culminating in autoantibody production and tissue damage, associated with severe dryness of mucosal surfaces and salivary gland hypofunction. Cenerimod, a potent, selective and orally active sphingosine-1-phosphate receptor 1 modulator, inhibits the egress of lymphocytes into the circulation. Based on the mechanism of action of cenerimod, its efficacy was evaluated in two mouse models of Sjögren’s syndrome.

Methods

Cenerimod was administered in two established models of Sjögren’s syndrome; firstly, in an inducible acute viral sialadenitis model in C57BL/6 mice, and, secondly, in the spontaneous chronic sialadenitis MRL/lpr mouse model. The effects of cenerimod treatment were then evaluated by flow cytometry, immunohistochemistry, histopathology and immunoassays. Comparisons between groups were made using a Mann-Whitney test.

Results

In the viral sialadenitis model, cenerimod treatment reduced salivary gland immune infiltrates, leading to the disaggregation of ectopic lymphoid structures, reduced salivary gland inflammation and preserved organ function. In the MRL/lpr mouse model, cenerimod treatment decreased salivary gland inflammation and reduced T cells and proliferating plasma cells within salivary gland ectopic lymphoid structures, resulting in diminished disease-relevant autoantibodies within the salivary glands.

Conclusions

Taken together, these results suggest that cenerimod can reduce the overall autoimmune response and improve clinical parameters in the salivary glands in models of Sjögren’s syndrome and consequently may reduce histological and clinical parameters associated with the disease in patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02673-x.

Target-Based Small Molecule Drug Discovery Towards Novel Therapeutics for Inflammatory Bowel Diseases

Inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), is a class of severe and chronic diseases of the gastrointestinal (GI) tract with recurrent symptoms and significant morbidity. Long-term persistence of chronic inflammation in IBD is a major contributing factor to neoplastic transformation and the development of colitis-associated colorectal cancer. Conversely, persistence of transmural inflammation in CD is associated with formation of fibrosing strictures, resulting in substantial morbidity. The recent introduction of biological response modifiers as IBD therapies, such as antibodies neutralizing tumor necrosis factor (TNF)-α, have replaced nonselective anti-inflammatory corticosteroids in disease management. However, a large proportion (~40%) of patients with the treatment of anti-TNF-α antibodies are discontinued or withdrawn from therapy because of (1) primary nonresponse, (2) secondary loss of response, (3) opportunistic infection, or (4) onset of cancer. Therefore, the development of novel and effective therapeutics targeting specific signaling pathways in the pathogenesis of IBD is urgently needed. In this comprehensive review, we summarize the recent advances in drug discovery of new small molecules in preclinical or clinical development for treating IBD that target biologically relevant pathways in mucosal inflammation. These include intracellular enzymes (Janus kinases, receptor interacting protein, phosphodiesterase 4, IκB kinase), integrins, G protein-coupled receptors (S1P, CCR9, CXCR4, CB2) and inflammasome mediators (NLRP3), etc. We will also discuss emerging evidence of a distinct mechanism of action, bromodomain-containing protein 4, an epigenetic regulator of pathways involved in the activation, communication, and trafficking of immune cells. We highlight their chemotypes, mode of actions, structure-activity relationships, characterizations, and their in vitro/in vivo activities and therapeutic potential. The perspectives on the relevant challenges, new opportunities, and future directions in this field are also discussed.

Role of sphingosine-1-phosphate mediated signalling in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a highly prevalent autoimmune disease characterized by the malfunction of the immune system and the persistent presence of an inflammatory environment. Multiple organs can be affected during SLE, leading to heterogeneous manifestations, which eventually result in the death of patients. Due to the lack of understanding regarding the pathogenesis of SLE, the currently available treatments remain suboptimal. Sphingosine-1-phosphate (S1P) is a central bioactive lipid of sphingolipid metabolism, which serves a pivotal role in regulating numerous physiological and pathological processes. As a well-recognized regulator of lymphocyte trafficking, S1P has been shown to be closely associated with autoimmune diseases, including SLE. Importantly, S1P levels have been found to be elevated in patients with SLE. In murine models of lupus, the increased levels of S1P also contribute to disease activity and organ impairment. Moreover, data from several studies also support the hypothesis that S1P receptors and its producer-sphingosine kinases (SPHK) may serve as the potential targets for the treatment of SLE and its co-morbidities. Given the significant success that intervening with S1P signaling has achieved in treating multiple sclerosis, further exploration of its role in SLE is necessary. Therefore, the aim of the present review is to summarize the recent advances in understanding the potential mechanism by which S1P influences SLE, with a primary focus on its role in immune regulation and inflammatory responses.

Investigation into MAO B-Mediated Formation of CC112273, a Major Circulating Metabolite of Ozanimod, in Humans and Preclinical Species: Stereospecific Oxidative Deamination of (S)-Enantiomer of Indaneamine (RP101075) by MAO B

Ozanimod, recently approved for treating relapsing multiple sclerosis, produced a disproportionate, active, MAO B-catalyzed metabolite (CC112273) that showed remarkable interspecies differences and led to challenges in safety testing. This study explored the kinetics of CC112273 formation from its precursor RP101075. Incubations with human liver mitochondrial fractions revealed K Mapp, V max, and intrinsic clearance (Clint) for CC112273 formation to be 4.8 μM, 50.3 pmol/min/mg protein, and 12 μl/min/mg, respectively, whereas Michaelis-Menten constant (K M) with human recombinant MAO B was 1.1 μM. Studies with liver mitochondrial fractions from preclinical species led to K Mapp, V max, and Clint estimates of 3.0, 35, and 33 μM, 80.6, 114, 37.3 pmol/min/mg, and 27.2, 3.25, and 1.14 μl/min/mg in monkey, rat, and mouse, respectively, and revealed marked differences between rodents and primates, primarily attributable to differences in the K M Comparison of Clint estimates revealed monkey to be ∼2-fold more efficient and the mouse and rat to be 11- and 4-fold less efficient than humans in CC112273 formation. The influence of stereochemistry on MAO B-mediated oxidation was also investigated using the R-isomer of RP101075 (RP101074). This showed marked selectivity toward catalysis of the S-isomer (RP101075) only. Docking into MAO B crystal structure suggested that although both the isomers occupied its active site, only the orientation of RP101075 presented the C-H on the α-carbon that was ideal for the C-H bond cleavage, which is a requisite for oxidative deamination. These studies explain the basis for the observed interspecies differences in the metabolism of ozanimod as well as the substrate stereospecificity for formation of CC112273. SIGNIFICANCE STATEMENT: This study evaluates the enzymology and the species differences of the major circulating metabolite of ozanimod, CC112273. Additionally, the study also explores the influence of stereochemistry on MAO B-catalyzed reactions. The study is of significance to the DMD readers given that this oxidation is catalyzed by a non-cytochrome P450 enzyme, and that marked species difference and notable stereospecificity was observed in MAO B-catalyzed biotransformation when the indaneamine enantiomers were used as substrates.

Preclinical to clinical translation of cenerimod, a novel S1P1 receptor modulator, in systemic lupus erythematosus

Objectives:

SLE is an autoimmune disease characterised by aberrant lymphocyte activation and autoantibody production. This study provides an in-depth preclinical and clinical characterisation of the treatment effect of cenerimod, a sphingosine-1-phosphate receptor type 1 (S1P₁) modulator, in SLE.

Methods:

Cenerimod effect on lymphocyte numbers, organ pathology, inflammation, and survival was evaluated in the MRL/lpr lupus mouse model. Lymphocytes from healthy subjects and patients with SLE were assessed for cenerimod-induced S1P₁ receptor internalisation. Lymphocyte subsets and inflammatory biomarkers were characterised in a 12-week phase 2 clinical study (NCT-02472795), where patients with SLE were treated with multiple doses of cenerimod or placebo.

Results:

In MRL/lpr mice treated with cenerimod, blood lymphocytes were reduced, leading to reduced immune infiltrates into tissue, and decreased tissue pathology, proteinuria, and inflammation, resulting in increased survival. Cenerimod was potent and efficacious in inducing S1P₁ receptor internalisation in lymphocytes in both healthy subjects and patients with SLE. In patients with SLE, 12-week cenerimod treatment resulted in a dose-dependent reduction of blood lymphocytes, antibody-secreting cells (ASC), and plasma IFN-α.

Conclusion:

Cenerimod significantly ameliorated systemic and organ-specific pathology and inflammation in a mouse model of SLE. In lymphocytes from patients with SLE, the S1P₁ receptor remained functional despite concomitant background medication. The preclinical lymphocyte reduction translated to patients with SLE and resulted in the normalisation of ASC and the reduction of IFN-associated biomarkers. The efficacy and safety of cenerimod is being further investigated in a long-term clinical study in patients with SLE (CARE; NCT-03742037).

Targeting Sphingosine-1-Phosphate Signaling in Immune-Mediated Diseases: Beyond Multiple Sclerosis

Sphingosine-1-phosphate (S1P) is a bioactive lipid metabolite that exerts its actions by engaging 5 G-protein-coupled receptors (S1PR1-S1PR5). S1P receptors are involved in several cellular and physiological events, including lymphocyte/hematopoietic cell trafficking. An S1P gradient (low in tissues, high in blood), maintained by synthetic and degradative enzymes, regulates lymphocyte trafficking. Because lymphocytes live long (which is critical for adaptive immunity) and recirculate thousands of times, the S1P-S1PR pathway is involved in the pathogenesis of immune-mediated diseases. The S1PR1 modulators lead to receptor internalization, subsequent ubiquitination, and proteasome degradation, which renders lymphocytes incapable of following the S1P gradient and prevents their access to inflammation sites. These drugs might also block lymphocyte egress from lymph nodes by inhibiting transendothelial migration. Targeting S1PRs as a therapeutic strategy was first employed for multiple sclerosis (MS), and four S1P modulators (fingolimod, siponimod, ozanimod, and ponesimod) are currently approved for its treatment. New S1PR modulators are under clinical development for MS, and their uses are being evaluated to treat other immune-mediated diseases, including inflammatory bowel disease (IBD), rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and psoriasis. A clinical trial in patients with COVID-19 treated with ozanimod is ongoing. Ozanimod and etrasimod have shown promising results in IBD; while in phase 2 clinical trials, ponesimod has shown improvement in 77% of the patients with psoriasis. Cenerimod and amiselimod have been tested in SLE patients. Fingolimod, etrasimod, and IMMH001 have shown efficacy in RA preclinical studies. Concerns relating to S1PR modulators are leukopenia, anemia, transaminase elevation, macular edema, teratogenicity, pulmonary disorders, infections, and cardiovascular events. Furthermore, S1PR modulators exhibit different pharmacokinetics; a well-established first-dose event associated with S1PR modulators can be mitigated by gradual up-titration. In conclusion, S1P modulators represent a novel and promising therapeutic strategy for immune-mediated diseases.

An Overview of the Efficacy and Safety of Ozanimod for the Treatment of Relapsing Multiple Sclerosis

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

Deletion of Mir223 Exacerbates Lupus Nephritis by Targeting S1pr1 in Faslpr/lpr Mice

Objective

The micro RNAs (miRNAs) and their target mRNAs are differentially expressed in various immune-mediated cells. Here, we investigated the role of Mir223 and sphingosine-1-phosphate receptor 1 (S1pr1) in the pathogenesis of systemic lupus erythematosus.

Methods

We analyzed miRNA and mRNA profiling data of CD4+ splenic T cells derived from MRL/MpJ-Faslpr /J mice. We performed 3' untranslated region (UTR) luciferase reporter gene assay using human umbilical vein endothelial cells (HUVECs). We generated the B6-Mir223-/-Faslpr/lpr mice and the lupus phenotypes were analyzed.

Results

In CD4+ splenic T cells, we identified upregulation of miR-223-3p and downregulation of the possible target, S1pr1 by RNA sequencing of MRL/MpJ-Faslpr /J mice. The transfection with miR-223-3p mimic significantly suppressed a luciferase activity in HUVEC treated with a Lentivirus vector containing 3' UTR of S1pr1. The mRNA levels of S1pr1 were significantly decreased after miR-223-3p overexpression. In B6-Mir223-/-Faslpr/lpr mice, the proportion of CD3+ T cells, CD3+CD4-CD8- cells, B cells, plasma cells, and S1PR1+CD4+ T cells in the spleen was significantly increased compared with that in B6-Mir223+/+Faslpr/lpr mice by flow cytometry. B6-Mir223-/-Faslpr/lpr mice demonstrated the elevation of glomerular and renal vascular scores associated with enhanced intraglomerular infiltration of S1PR1+CD4+ T cells.

Conclusion

Unexpectedly, the deletion of Mir223 exacerbated the lupus phenotypes associated with increased population of S1PR1+CD4+ T in spleen and the enhanced infiltration of S1PR1+CD4+ T cells in inflamed kidney tissues, suggesting compensatory role of Mir223 in the pathogenesis of lupus nephritis.

Sphingosine-1-Phosphate Metabolism and Signaling in Kidney Diseases

In the past few decades, sphingolipids and sphingolipid metabolites have gained attention because of their essential role in the pathogenesis and progression of kidney diseases. Studies in models of experimental and clinical nephropathies have described accumulation of sphingolipids and sphingolipid metabolites, and it has become clear that the intracellular sphingolipid composition of renal cells is an important determinant of renal function. Proper function of the glomerular filtration barrier depends heavily on the integrity of lipid rafts, which include sphingolipids as key components. In addition to contributing to the structural integrity of membranes, sphingolipid metabolites, such as sphingosine-1-phosphate (S1P), play important roles as second messengers regulating biologic processes, such as cell growth, differentiation, migration, and apoptosis. This review will focus on the role of S1P in renal cells and how aberrant extracellular and intracellular S1P signaling contributes to the pathogenesis and progression of kidney diseases.

Amiselimod, a sphingosine 1-phosphate receptor-1 modulator, for systemic lupus erythematosus: A multicenter, open-label exploratory study

OBJECTIVE

To evaluate the safety, pharmacokinetics, pharmacodynamics, and exploratory efficacy of amiselimod, an oral selective sphingosine 1-phosphate receptor-1 modulator, in patients with systemic lupus erythematosus (SLE).

METHODS

A multicenter, open-label phase Ib trial was conducted in Japan. Patients in Part 1 and Part 2-B received 0.2 mg amiselimod while those in Part 2-A received 0.4 mg amiselimod for 24 weeks.

RESULTS

Seventeen subjects received 0.2 or 0.4 mg amiselimod. Amiselimod and amiselimod-P plasma concentrations increased dose-dependently. Peripheral blood lymphocyte count decreased in all patients after amiselimod treatment, with no clear dose response. There were no serious/severe adverse events (AEs) or clinically meaningful cardiac effects. Five subjects were withdrawn from amiselimod treatment following a decrease in lymphocyte count to <200/μl. Anti-double stranded-DNA antibody decreased from baseline to Week 24/end of treatment (EOT), with those in 2 subjects (22.2%) decreasing to within the normal range. Total SLE disease activity index 2000 score decreased by ≥4 at EOT in 7 of 17 subjects.

CONCLUSIONS

Amiselimod was generally well tolerated. While no serious AEs or infectious AEs led to discontinuation, low lymphocyte counts of <200/μl were observed as a laboratory abnormality. Our findings suggest the potential efficacy of amiselimod for patients with SLE.Trial registration: ClinicalTrials.gov identifier: NCT02307643.

Sphingolipids and Diagnosis, Prognosis, and Organ Damage in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that involves multiple organs and disproportionality affects females, especially African Americans from 15 to 44 years of age. SLE can lead to end organ damage including kidneys, lungs, cardiovascular and neuropsychiatric systems, with cardiovascular complications being the primary cause of death. Usually, SLE is diagnosed and its activity is assessed using the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), Systemic Lupus International Collaborating Clinics Damage Index (SLICC/ACR), and British Isles Lupus Assessment Group (BILAG) Scales, which unfortunately often occurs after a certain degree of systemic involvements, disease activity or organ damage already exists. There is certainly a need for the identification of early biomarkers to diagnose and assess disease activity as well as to evaluate disease prognosis and response to treatment earlier in the course of the disease. Here we review advancements made in the area of sphingolipidomics as a diagnostic/prognostic tool for SLE and its co-morbidities. We also discuss recent reports on differential sphingolipid metabolism and blood sphingolipid profiles in SLE-prone animal models as well as in diverse cohorts of SLE patients. In addition, we address targeting sphingolipids and their metabolism as a method of treating SLE and some of its complications. Although such treatments have already shown promise in preventing organ-specific pathology caused by SLE, further investigational studies and clinical trials are warranted.

Bioactive lipids, inflammation and chronic diseases

Endogenous bioactive lipids are part of a complex network that modulates a plethora of cellular and molecular processes involved in health and disease, of which inflammation represents one of the most prominent examples. Inflammation serves as a well-conserved defence mechanism, triggered in the event of chemical, mechanical or microbial damage, that is meant to eradicate the source of damage and restore tissue function. However, excessive inflammatory signals, or impairment of pro-resolving/anti-inflammatory pathways leads to chronic inflammation, which is a hallmark of chronic pathologies. All main classes of endogenous bioactive lipids - namely eicosanoids, specialized pro-resolving lipid mediators, lysoglycerophopsholipids and endocannabinoids - have been consistently involved in the chronic inflammation that characterises pathologies such as cancer, diabetes, atherosclerosis, asthma, as well as autoimmune and neurodegenerative disorders and inflammatory bowel diseases. This review gathers the current knowledge concerning the involvement of endogenous bioactive lipids in the pathogenic processes of chronic inflammatory pathologies.

The ceramide-S1P pathway as a druggable target to alleviate peripheral neuropathic pain

Introduction: Neuropathic pain disorders are diverse, and the currently available therapies are ineffective in the majority of cases. Therefore, there is a major need for gaining novel mechanistic insights and developing new treatment strategies for neuropathic pain. Areas covered: We performed an in-depth literature search on the molecular mechanisms and systemic importance of the ceramide-to-S1P rheostat regulating neuron function and neuroimmune interactions in the development of neuropathic pain. Expert opinion: The S1P receptor modulator FTY720 (fingolimod, Gilenya®), LPA receptor antagonists and several mechanistically related compounds in clinical development raise great expectations for treating neuropathic pain disorders. Research on S1P receptors, S1P receptor modulators or SPHK inhibitors with distinct selectivity, pharmacokinetics and safety must provide more mechanistic insight into whether they may qualify as useful treatment options for neuropathic pain disorders. The functional relevance of genetic variations within the ceramide-to-S1P rheostat should be explored for an enhanced understanding of neuropathic pain pathogenesis. The ceramide-to-S1P rheostat is emerging as a critically important regulator hub of neuroimmune interactions along the pain pathway, and improved mechanistic insight is required to develop more precise and effective drug treatment options for patients suffering from neuropathic pain disorders.

The S1P-S1PR Axis in Neurological Disorders-Insights into Current and Future Therapeutic Perspectives

Sphingosine 1-phosphate (S1P), derived from membrane sphingolipids, is a pleiotropic bioactive lipid mediator capable of evoking complex immune phenomena. Studies have highlighted its importance regarding intracellular signaling cascades as well as membrane-bound S1P receptor (S1PR) engagement in various clinical conditions. In neurological disorders, the S1P–S1PR axis is acknowledged in neurodegenerative, neuroinflammatory, and cerebrovascular disorders. Modulators of S1P signaling have enabled an immense insight into fundamental pathological pathways, which were pivotal in identifying and improving the treatment of human diseases. However, its intricate molecular signaling pathways initiated upon receptor ligation are still poorly elucidated. In this review, the authors highlight the current evidence for S1P signaling in neurodegenerative and neuroinflammatory disorders as well as stroke and present an array of drugs targeting the S1P signaling pathway, which are being tested in clinical trials. Further insights on how the S1P–S1PR axis orchestrates disease initiation, progression, and recovery may hold a remarkable potential regarding therapeutic options in these neurological disorders.

Retinoic Acid Exerts Disease Stage-Dependent Effects on Pristane-Induced Lupus

We previously showed that all-trans-retinoic acid (tRA), an active metabolite of vitamin A, exacerbated pre-existing autoimmunity in lupus; however, its effects before the development of autoimmunity are unknown. Here, using a pristane-induced model, we show that tRA exerts differential effects when given at the initiation vs. continuation phase of lupus. Unlike tRA treatment during active disease, pre-pristane treatment with tRA aggravated glomerulonephritis through increasing renal expression of pro-fibrotic protein laminin β1, activating bone marrow conventional dendritic cells (cDCs), and upregulating the interaction of ICAM-1 and LFA-1 in the spleen, indicating an active process of leukocyte activation and trafficking. Transcriptomic analysis revealed that prior to lupus induction, tRA significantly upregulated the expression of genes associated with cDC activation and migration. Post-pristane tRA treatment, on the other hand, did not significantly alter the severity of glomerulonephritis; rather, it exerted immunosuppressive functions of decreasing circulatory and renal deposition of autoantibodies as well as suppressing the renal expression of proinflammatory cytokines and chemokines. Together, these findings suggest that tRA differentially modulate lupus-associated kidney inflammation depending on the time of administration. Interestingly, both pre- and post-pristane treatments with tRA reversed pristane-induced leaky gut and modulated the gut microbiota in a similar fashion, suggesting a gut microbiota-independent mechanism by which tRA affects the initiation vs. continuation phase of lupus.

Cutaneous Lupus Erythematosus: Current and Future Pathogenesis-Directed Therapies

Cutaneous lupus erythematosus (CLE) is an autoimmune disease of the skin with significant morbidity. Current treatments are often inadequate to control disease and there are no Food and Drug Administration (FDA)-approved therapies for this potentially debilitating disease, underscoring an unmet medical need. Recent insights into disease pathogenesis have implicated innate and adaptive immune components, including type I and type III interferons in the development of CLE. Promising clinical trials based on these insights are now underway. However, the full spectrum of immune cells, cytokines, and environmental triggers contributing to disease remain to be elucidated. In this review, we will highlight the current understanding of CLE immunopathogenesis, the ongoing clinical trial landscape, and provide a framework for designing future therapeutic strategies for CLE based on new insights into disease pathogenesis.

A novel S1P1 modulator IMMH002 ameliorates psoriasis in multiple animal models

Psoriasis is characterized by abnormal proliferation of keratinocytes, as well as infiltration of immune cells into the dermis and epidermis, causing itchy, scaly and erythematous plaques of skin. The understanding of this chronic inflammatory skin disease remains unclear and all available treatments have their limitations currently. Here, we showed that IMMH002, a novel orally active S1P₁ modulator, desensitized peripheral pathogenic lymphocytes to egress signal from secondary lymphoid organs and thymus. Using different psoriasis animal models, we demonstrated that IMMH002 could significantly relieve skin damage as revealed by PASI score and pathological injure evaluation. Mechanistically, IMMH002 regulated CD3⁺ T lymphocytes re-distribution by inducing lymphocytes’ homing, thus decreased T lymphocytes allocation in the peripheral blood and skin but increased in the thymus. Our results suggest that the novel S1P₁ agonist, IMMH002, exert extraordinary capacity to rapidly modulate T lymphocytes distribution, representing a promising drug candidate for psoriasis treatment.

Amiselimod (MT-1303), a Novel Sphingosine 1-Phosphate Receptor-1 Modulator, Potently Inhibits the Progression of Lupus Nephritis in Two Murine SLE Models

Amiselimod (MT-1303) is a novel and selective sphingosine 1-phosphate receptor-1 (S1P₁) modulator with a more favorable cardiac safety profile than other S1P₁ receptor modulators. In this study, we evaluated the effects of MT-1303 on the progression of lupus nephritis in two well-known murine systemic lupus erythematosus (SLE) models, MRL/lpr and NZBWF1 mice, compared with those of FK506. Daily oral doses of 0.1 and 0.3 mg/kg MT-1303 not only inhibited the development of lupus nephritis when administered before onset in MRL/lpr and NZBWF1 mice but also improved symptoms of lupus nephritis when administered after onset in MRL/lpr mice. Its efficacy in these models was more potent or comparable to that of FK506 (1 and 3 mg/kg). In histological analysis, treatment with MT-1303 inhibited infiltration of T cells into the kidneys, mesangial expansion, and glomerular sclerosis. MT-1303 treatment resulted in a marked reduction in T cells and B cells in the peripheral blood and significantly inhibited increases in the number of plasma cells in the spleen and T cells in the kidneys. In addition, administration of MT-1303 suppressed elevations in serum anti-dsDNA antibody levels in MRL/lpr mice, but not in NZBWF1 mice. Our findings show that MT-1303 exhibits marked therapeutic effects on lupus nephritis in two SLE models, likely by reducing the infiltration of autoreactive T cells into the kidneys. These results suggest that MT-1303 has the potential to be used as a therapeutic agent for patients suffering from SLE, including lupus nephritis.

Examination of the role of sphingosine kinase 2 in a murine model of systemic lupus erythematosus

Systemic lupus erythematosus is an autoimmune disease characterized by overproduction of type 1 IFN that causes multiple organ dysfunctions. Plasmacytoid dendritic cells (pDCs) that secrete large amounts of IFN have recently been implicated in the initiation of the disease in preclinical mouse models. Sphingosine-1-phosphate, a bioactive sphingolipid metabolite, is produced by 2 highly conserved isoenzymes, sphingosine kinase (SphK) 1 and SphK2, and regulates diverse processes important for immune responses and autoimmunity. However, not much is known about the role of SphK2 in autoimmune disorders. In this work, we examined the role of SphK2 in pDC development and activation and in the pristane-induced lupus model in mice that mimics the hallmarks of the human disease. Increases in pDC-specific markers were observed in peripheral blood of SphK2 knockout mice. In agreement, the absence of SphK2 increased the differentiation of FMS-like tyrosine kinase 3 ligand dendritic cells as well as expression of endosomal TLRs, TLR7 and TLR9, that modulate production of IFN. Surprisingly, however, SphK2 deficiency did not affect the initiation or progression of pristane-induced lupus. Moreover, although absence of SphK2 increased pDC frequency in pristane-induced lupus, there were no major changes in their activation status. Additionally, SphK2 expression was unaltered in lupus patients. Taken together, our results suggest that SphK2 may play a role in dendritic cell development. Yet, because its deletion had no effect on the clinical lupus parameters in this preclinical model, inhibitors of SphK2 might not be useful for treatment of this devastating disease.-Mohammed, S., Vineetha, N. S., James, S., Aparna, J. S., Lankadasari, M. B., Allegood, J. C., Li, Q.-Z., Spiegel, S., Harikumar, K. B. Examination of the role of sphingosine kinase 2 in a murine model of systemic lupus erythematosus.

An update on sphingosine-1-phosphate receptor 1 modulators

Sphingolipids represent an essential class of lipids found in all eukaryotes, and strongly influence cellular signal transduction. Autoimmune diseases like asthma and multiple sclerosis (MS) are mediated by the sphingosine-1-phosphate receptor 1 (S1P₁) to express a variety of symptoms and disease patterns. Inspired by its natural substrate, an array of artificial sphingolipid derivatives has been developed to target this specific G protein-coupled receptor (GPCR) in an attempt to suppress autoimmune disorders. FTY720, also known as fingolimod, is the first oral disease-modifying therapy for MS on the market. In pursuit of improved stability, bioavailability, and efficiency, structural analogues of this initial prodrug have emerged over time. This review covers a brief introduction to the sphingolipid metabolism, the mechanism of action on S1P₁, and an updated overview of synthetic sphingosine S1P₁ agonists.