Sphingosine-1-Phosphate and Its Signal Modulators Alleviate Psoriasis-Like Dermatitis: Preclinical and Clinical Evidence and Possible Mechanisms

BackgroundPsoriasis is an autoimmune skin disease associated with lipid metabolism. Sphingosine-1-phosphate (S1P) is a bioactive lipid that plays a key role in the development of autoimmune diseases. However, there is currently a lack of comprehensive evidence of the effectiveness of S1P on psoriasis.ObjectiveTo assess the efficacy and possible mechanism of S1P and its signal modulators in the treatment of psoriasis-like dermatitis.MethodsSix databases were searched through May 8, 2021, for studies reporting S1P and its signal modulators. Two reviewers independently extracted information from the enrolled studies. Methodological quality was assessed using SYRCLE’s risk of bias tool. RevMan 5.3 software was used to analyze the data. For clinical studies, the Psoriasis Area and Severity Index score were the main outcomes. For preclinical studies, we clarified the role of S1P and its regulators in psoriasis in terms of phenotype and mechanism.ResultsOne randomized double-blind placebo-controlled trial and nine animal studies were included in this study. The pooled results showed that compared with control treatment, S1P receptor agonists [mean difference (MD): −6.80; 95% confidence interval (CI): −8.23 to −5.38; p<0.00001], and sphingosine kinase 2 inhibitors (MD: −0.95; 95% CI: −1.26 to −0.65; p<0.00001) alleviated psoriasis-like dermatitis in mice. The mechanism of S1P receptor agonists in treating psoriasis might be related to a decrease in the number of white blood cells, topical lymph node weight, interleukin-23 mRNA levels, and percentage of CD3+ T cells (p<0.05). Sphingosine kinase 2 inhibitors ameliorated psoriasis in mice, possibly by reducing spleen weight and cell numbers (p<0.05).ConclusionsS1P receptor agonists and sphingosine kinase 2 inhibitors could be potential methods for treating psoriasis by decreasing immune responses and inflammatory factors.

Research Progress on the Effect of Sphingosine Kinase 2 on Glioma

Objective: The purpose of this study is to explore the role of sphingosine kinase 2 (SphK2) in the treatment of glioma, which is the most common primary tumor in the central nervous system. Methods: A total of 82 patients were included in this study, with 27 cases in the control group and 55 cases in the glioma group; the expressions of SphK2 and gp130 in the two groups were compared by immunohistochemical method, and the correlation between the two factors was analyzed. Results: Both SphK2 and gp130 were upregulated in the glioma group, and the two factors were significantly correlated. Conclusion: The high expression of SphK2 may play an important role in the occurrence, development, and diagnosis of glioma.

Islet Co-Expression of CD133 and ABCB5 in Human Retinoblastoma Specimens

Background The role of CD133 und ABCB5 is discussed in treatment resistance in several types of cancer. The objective of this study was to evaluate whether CD133+/ABCB5+ colocalization differs in untreated, in beam radiation treated, and in chemotherapy treated retinoblastoma specimens. Additionally, CD133, ABCB5, sphingosine kinase 1, and sphingosine kinase 2 gene expression was analyzed in WERI-RB1 (WERI RB1) and etoposide-resistant WERI RB1 subclones (WERI ETOR). Methods Active human untreated retinoblastoma specimens (n = 12), active human retinoblastoma specimens pretreated with beam radiation before enucleation (n = 8), and active human retinoblastoma specimens pretreated with chemotherapy before enucleation (n = 7) were investigated for localization and expression of CD133 and ABCB5 by immunohistochemistry. Only specimens with IIRC D, but not E, were included in this study. Furthermore, WERI RB1 and WERI ETOR cell lines were analyzed for CD133, ABCB5, sphingosine kinase 1, and sphingosine kinase 2 by the real-time polymerase chain reaction (RT-PCR). Results Immunohistochemical analysis revealed the same amount of CD133+/ABCB5+ colocalization islets in untreated and treated human retinoblastoma specimens. Quantitative RT-PCR analysis showed a statistically significant upregulation of CD133 in WERI ETOR (p = 0.002). No ABCB5 expression was detected in WERI RB1 and WERI ETOR. On the other hand, SPHK1 (p = 0.0027) and SPHK2 (p = 0.017) showed significant downregulation in WERI ETOR compared to WERI RB1. Conclusions CD133+/ABCB5+ co-localization islets were noted in untreated and treated human retinoblastoma specimens. Therefore, we assume that CD133+/ABCB5+ islets might play a role in retinoblastoma genesis, but not in retinoblastoma treatment resistance.

Arachnoid membrane as a source of sphingosine-1-phosphate that regulates mouse middle cerebral artery tone

Growing evidence indicates that perivascular tissue is critical to modulate vessel function. We hypothesized that the arachnoid membrane surrounding middle cerebral artery (MCA) regulates its function via sphingosine-1-phosphate (S1P)-induced vasoconstriction. The MCA from 3- to 9-month-old male and female wild-type (Oncine France 1 and C57BL/6) mice and sphingosine kinase 2 knockout (SphK2-/-) mice in the C57BL/6 background was mounted in pressure myographs with and without arachnoid membrane. Raman microspectroscopy and imaging were used for in situ detection of S1P. The presence of arachnoid tissue was associated with reduced external and lumen MCA diameters, and with an increase in basal tone regardless of sex and strain background. Strong S1P-positive signals were detected in the arachnoid surrounding the MCA wall in both mice models, as well as in a human post-mortem specimen. Selective S1P receptor 3 antagonist TY 52156 markedly reduced both MCA vasoconstriction induced by exogenous S1P and arachnoid-dependent basal tone increase. Compared to 3-month-old mice, the arachnoid-mediated contractile influence persisted in 9-month-old mice despite a decline in arachnoid S1P deposits. Genetic deletion of SphK2 decreased arachnoid S1P content and vasoconstriction. This is the first experimental evidence that arachnoid membrane regulates the MCA tone mediated by S1P.

Opaganib in COVID-19 pneumonia: Results of a randomized, placebo-controlled Phase 2a trial

Rationale: Opaganib, an oral sphingosine kinase-2 inhibitor with antiviral and anti-inflammatory properties, was shown to inhibit SARS-CoV-2 replication in vitro. We thus considered that opaganib could be beneficial for moderate to severe COVID-19 pneumonia. Objectives: To evaluate the effect of opaganib on supplemental oxygen requirements, time to hospital discharge and its safety in COVID-19 pneumonia hospitalized patients requiring supplemental oxygen. Methods: This Phase 2a, randomized, double-blind, placebo-controlled study, was conducted between July and December 2020 in eight sites in the USA. Forty-two enrolled patients received opaganib (n=23) or placebo (n=19) added to standard of care for up to 14 days and were followed up for 28 days after their last dose of investigational product. Main Results: By Day 14, 50.0% of patients in the opaganib and 22.2% in the placebo group no longer required supplemental oxygen for at least 24 hours, while 86.4% and 55.6%, respectively, were discharged from hospital. The relative decrease in total supplemental oxygen requirement from baseline to Day 14 was 61.6% in the opaganib versus 46.7% in the placebo arms. The incidence of ≥ Grade 3 treatment-emergent adverse events was 17.4% and 33.3% in the opaganib and placebo groups, respectively. Three deaths occurred in each group. Conclusions: In this proof-of-concept study, patients receiving oral opaganib required less supplemental oxygen, resulting in earlier hospital discharge, with no safety concerns arising. These findings support further evaluation of opaganib in this population.

ST-2191, an Anellated Bismorpholino Derivative of Oxy-Fingolimod, Shows Selective S1P1 Agonist and Functional Antagonist Potency In Vitro and In Vivo

Sphingosine 1-phosphate (S1P) is an extensively studied signaling molecule that contributes to cell proliferation, survival, migration and other functions through binding to specific S1P receptors. The cycle of S1P1 internalization upon S1P binding and recycling to the cell surface when local S1P concentrations are low drives T cell trafficking. S1P1 modulators, such as fingolimod, disrupt this recycling by inducing persistent S1P1 internalization and receptor degradation, which results in blocked egress of T cells from the secondary lymphoid tissues. The approval of these compounds for the treatment of multiple sclerosis has placed the development of S1PR modulators in the focus of pharmacological research, mostly for autoimmune indications. Here, we report on a novel anellated bismorpholino derivative of oxy-fingolimod, named ST-2191, which exerts selective S1P1 agonist and functional antagonist potency. ST-2191 is also effective in reducing the lymphocyte number in mice, and this effect is not dependent on phosphorylation by sphingosine kinase 2 for activity. These data show that ST-2191 is a novel S1P1 modulator, but further experiments are needed to analyze the therapeutic impact of ST-2191 in animal models of autoimmune diseases.

Ubiquitination Destabilizes Protein Sphingosine Kinase 2 to Regulate Glioma Malignancy

Gliomas are the most common and lethal malignant tumor in the central nervous system. The tumor oncogene sphingosine kinase 2 (SphK2) was previously found to be upregulated in glioma tissues and enhance glioma cell epithelial-to-mesenchymal transition through the AKT/β-catenin pathway. Nevertheless, ubiquitination of SphK2 protein has yet to be well elucidated. In this study, mass spectrometry analysis was performed to identify proteins that interacted with SphK2 protein. Co-immunoprecipitation (co-IP) and immunoblotting (IB) were used to prove the specific interaction between SphK2 protein and the neural precursor cell-expressed developmentally downregulated 4-like (NEDD4L) protein. Fluorescence microscopy was used for detecting the distribution of related proteins. Ubiquitylation assay was utilized to characterize that SphK2 was ubiquitylated by NEDD4L. Cell viability assay, flow cytometry assay, and transwell invasion assay were performed to illustrate the roles of NEDD4L-mediated SphK2 ubiquitination in glioma viability, apoptosis, and invasion, respectively. We found that NEDD4L directly interacted with SphK2 and ubiquinated it for degradation. Ubiquitination of SphK2 mediated by NEDD4L overexpression suppressed glioma cell viability and invasion but promoted glioma apoptosis. Knockdown of NEDD4L presented opposite results. Moreover, further results suggested that ubiquitination of SphK2 regulated glioma malignancy via the AKT/β-catenin pathway. in vivo assay also supported the above findings. This study reveals that NEDD4L mediates SphK2 ubiquitination to regulate glioma malignancy and may provide some meaningful suggestions for glioma treatment.