The role of sphingosine-1-phosphate in the gut mucosal microenvironment and inflammatory bowel diseases

The Current Sphingosine 1 Phosphate Receptor Modulators in the Management of Ulcerative Colitis

Sphingosine 1 phosphate receptor (S1PR) modulators are the latest drug class to have received approval for the treatment of ulcerative colitis, and have brought a new mechanism of action to this landscape. They target immune cell trafficking, specifically the egress of lymphocytes from lymph nodes to the bloodstream, and have proven to be an efficacious and safe anti-inflammatory mechanism. This narrative review aims to distil the key trial data on the efficacy and safety of ozanimod and etrasimod, the two S1PR modulators currently licensed for use in UC. We discuss the higher response rates in the advanced therapy naive versus exposed subgroups. We summarise their safety profiles, taking into consideration open label extension data. Finally, we consider where this class of drugs may be best placed in the treatment landscape and also provide a practical guide for their use in clinical practice.

Exosomal SphK1 from colorectal cancer cells promotes cancer cell migration and activates hepatic stellate cells

Exosomes are small extracellular vesicles that are naturally released into body fluids by cells. They are rich in bioactive molecules such as proteins. Sphingosine kinase 1 (SphK1) is an important potential drug target for the treatment of cancer due to its functions to regulate cancer cell migration, growth, apoptosis and angiogenesis. Tumor exosomes abundantly surround primary tumors, exchanging and transferring information between cells and modulating cancer progression. Given the importance of exosomes, the involvement of exosomal SphK1 from colorectal cancer (CRC) cells in the migration of these cells and the activation of hepatic stellate cells was investigated. Firstly, the plasma exosomal SphK1 protein expression, tested by ELISA, was compared between patients with CRC without metastasis and those with liver metastasis. The results revealed that plasma exosomal SphK1 levels were significantly upregulated in patients with liver metastasis of CRC. Secondly, exosomes with different expression levels of SphK1, which were regulated by cell transfection, were isolated from CRC cells to evaluate their effect on the expression levels of E‑cadherin and vimentin in these cells, as assessed by western blotting. The results demonstrated that depletion of exosomal SphK1 partially reversed the exosome‑induced migration of CRC cells, and caused decreased vimentin and increased E‑cadherin levels. Thirdly, the effects of exosomes from CRC cells, with different expression levels of SphK1, on hepatic stellate cell activation were investigated, with α‑SMA, TNF‑α and TGF‑β levels assessed by western blotting in LX‑2 cells. Moreover, AKT and phosphorylated (p‑)AKT levels were also assessed by western blotting. The results revealed that exosomes activated hepatic stellate cells by upregulating p‑AKT, and depletion of exosomal SphK1 partially reversed this effect. Furthermore, the application of an AKT agonist reversed the inhibition of hepatic stellate cell activation, which was induced by the depletion of exosomal SphK1. Finally, investigation of cell viability, analyzed by CCK‑8 assay, and assessment of PCNA as a proliferation marker, analyzed by western blot, revealed that the culture supernatant of the activated hepatic stellate cells promoted the viability of CRC cells. Overall, these results demonstrated that exosomal SphK1 increased the migration of CRC cells, and activated hepatic stellate cells by regulating p‑AKT. This suggests that exosomal SphK1 may serve a key role in the migration of CRC cells and potentially the liver metastasis of CRC.

Regulatory role of S1P and its receptors in sepsis-induced liver injury

As an immune and metabolic organ, the liver affects the progression and prognosis of sepsis. Despite the severe adverse effects of sepsis liver injury on the body, treatment options remain limited. Sphingosine-1-phosphate (S1P) is a widely distributed lipid signaling molecule that binds to five sphingosine-1-phosphate receptors (S1PR) to regulate downstream signaling pathways involved in the pathophysiological processes of sepsis, including endothelial permeability, cytokine release, and vascular tone. This review summarizes current research on the role of S1P in normal liver biology and describes the mechanisms by which changes in S1P/S1PR affect the development of liver-related diseases. At the same time, the pathological processes underlying liver injury, as evidenced by clinical manifestations during sepsis, were comprehensively reviewed. This paper focused on the mechanistic pathways through which S1P and its receptors modulate immunity, bile acid metabolism, and liver-intestinal circulation in septic liver injury. Finally, the relationships between S1P and its receptors with liver inflammation and metabolism and the use of related drugs for the treatment of liver injury were examined. By elucidating the role of S1P and its receptor in the pathogenesis of sepsis liver injury, this review established a molecular targeting framework, providing novel insights into clinical and drug development.

Sphingosine-1-phosphate receptor 3 promotes neuronal apoptosis via the TNF-α/caspase-3 signaling pathway after acute intracerebral hemorrhage

BACKGROUND

Intracerebral hemorrhage (ICH) has a high incidence and mortality rate among cerebrovascular diseases, and effective treatments are lacking. Sphingosine-1-phosphate receptor 3 (S1PR3) is associated with secondary immune inflammatory injury following ICH. However, its relationship with neuronal apoptosis and the specific underlying mechanism are not clear.

METHODS

We observed the effect of S1PR3 on neuronal apoptosis by assessing neurobehavioral scores, performing Western blot (WB) analysis, and performing TUNEL staining in a mouse model of ICH. Moreover, WBs and flow cytometry were used to study the specific mechanism and signaling pathways in HT22 cells in vitro.

RESULTS

The expression of S1PR3, CCL2, TNF-α, and cleaved-caspase-3 (c-caspase-3) and neuronal apoptosis were significantly increased after ICH, accompanied by neurobehavioral deterioration. These effects were significantly improved by treatment with CAY10444, a specific S1PR3 antagonist. After S1P stimulation of HT22 cells, the expression of S1PR3, CCL2, TNF-α and c-caspase-3 increased, and neuronal apoptosis increased by activating caspase-3 through the downstream PI3K/AKT apoptosis signaling pathway. After CAY10444 treatment, the expression of CCL2, TNF-α and c-caspase-3 was significantly reduced, and the PI3K/AKT apoptotic signaling pathway was regulated to reduce neuronal apoptosis.

CONCLUSION

An increase in S1P/S1PR3 after ICH may induce neuronal apoptosis by increasing TNF-α expression and activating the PI3K/AKT signaling pathway and the expression of caspase-3 effector proteins. CAY10444 can reduce neuronal apoptosis, improve symptoms and play a neuroprotective role by antagonizing S1PR3. S1PR3 may be a promising therapeutic target.

Protective Role of Sphingosine-1-Phosphate During Radiation-Induced Testicular Injury

The impact of ionizing radiation on the male reproductive system is gaining increasing attention, particularly when it comes to testicular damage, which may result in decreased sperm quality and hormonal imbalances. Finding effective protective measures to mitigate testicular damage caused by radiation has become a focal point in the biomedical field. S1P, an essential biological signaling molecule, has garnered significant interest due to its multiple roles in regulating cellular functions and its protective effects against radiation-induced testicular injury. S1P not only effectively reduces the generation of ROS induced by radiation but also alleviates oxidative stress by enhancing the activity of antioxidant enzymes. Furthermore, S1P inhibits radiation-induced cell apoptosis by regulating the expression of anti-apoptotic and pro-apoptotic proteins. Additionally, S1P alleviates radiation-induced inflammation by inhibiting the production of inflammatory factors, thereby further protecting testicular tissue. In summary, S1P effectively reduces radiation-induced testicular damage through multiple mechanisms, offering a promising therapeutic approach to safeguard male reproductive health. Future research should explore the specific mechanisms of action and clinical application potential of S1P, aiming to contribute significantly to the prevention and treatment of radiation damage.

Integrating 16 S rRNA gene sequencing and metabolomics analysis to reveal the mechanism of Angelica sinensis oil in alleviating ulcerative colitis in mice

Angelica sinensis (Oliv.) Diels (AS) is a commonly used herbal medicine and culinary spice known for its gastrointestinal protective properties. Angelica sinensis oil (AO) is the main bioactive component of AS. However, the therapeutic effects and mechanisms of AO on the gastrointestinal tract remain unclear. In this study, we aim to investigated the potential of AO in restoring gut microbiota disorder and metabolic disruptions associated with ulcerative colitis (UC). A systematic chemical characterization of AO was conducted using GC×GC-Q TOF-MS. A UC mouse model was established by freely drinking DSS to assess the efficacy of AO. Utilizing 16 S rRNA sequencing in combination with untargeted metabolomics analysis of serum, we identified alterations in gut microbiota, differential metabolites, and pathways influenced by AO in UC treatment, thereby elucidating the therapeutic mechanism of AO in UC management. Pharmacodynamic results indicated that AO effectively inhibited the content of inflammation mediators, such as Interleukin-1β, Interleukin-6 and tumor necrosis factor-α, and proserved colon tissue integrity in UC mice. Furthermore, AO significantly downregulated the abundance of pathogenic bacteria (Bacteroidetes, Proteobacteria, and Desulfobacteriaceae) while increasing the abundance of beneficial bacteria (Firmicutes, Blautia, Akkermansia, and Lachnospiraceae). Metabolomics analysis highlighted significant disruptions in endogenous metabolism in UC mice, with a notable restoration of SphK1 and S1P levels following AO administration. Besides, we discovered that AO regulated the balance of sphingolipid metabolism and protected the intestinal barrier, potentially through the SphK1/MAPK signaling pathway. Overall, this study indicated that AO effectively ameliorates the clinical manifestations of UC by synergistically regulating gut microbe and metabolite homeostasis. AO emerges as a potential functional and therapeutic ingredient for UC treatment.

GLP-1 receptor agonists alleviate colonic inflammation by modulating intestinal microbiota and the function of group 3 innate lymphoid cells

Glucagon-like peptide-1 receptor agonists (GLP-1RAs), which are drugs used for treating type 2 diabetes, have been reported to exert anti-inflammatory effects on inflammatory bowel disease (IBD), the mechanism of which remains elusive. Here, we report that GLP-1RAs ameliorate dextran sulfate sodium (DSS)-induced colitis in both wild-type and T/B-cell-deficient mice through modulating group 3 innate lymphoid cells (ILC3s), a subset of innate lymphoid cells that regulate intestinal immunity. GLP-1RAs promote IL-22 production by ILC3, and the protective effect of GLP-1RAs on DSS-induced colitis was abrogated in ILC3-deficient RORgtgfp/gfp mice. Furthermore, the treatment effect of GLP-RAs on colitis, as well as the generation of IL-22-producing ILC3s by GLP-RAs, is dependent on the gut microbiota. GLP-1RAs increase the abundance of Firmicutes and Proteobacteria in the gut, particularly beneficial bacteria such as Lactobacillus reuteri, and decrease the abundance of enteropathogenic Staphylococcus bacteria. The untargeted gas chromatography (GC)/liquid chromatography (LC)-mass spectrometry (MS) of faecal metabolites further revealed enrichment of N,N-dimethylsphingosine (DMS), an endogenous metabolite derived from sphingosine, in the GLP-1RA-treated group. Strikingly, DMS ameliorates colitis while promoting intestinal IL-22-producing ILC3s. Taken together, our findings show that GLP-1RAs exert a therapeutic effect on colitis possibly by regulating the microbiota-DMS-IL-22+ILC3 axis, highlighting the potential beneficial role of GLP-RAs in inflammatory intestinal disorders with diabetes complications.

Associations between sex hormones, receptors, binding proteins and inflammatory bowel disease: a Mendelian randomization study

Background

Gender differences existed in inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC). Observational studies have revealed associations between sex hormones and IBD, such as estrogen and testosterone. However, the exact relationship between these sex hormones and IBD is unclear.

Method

Based on the genome-wide association studies data of eight sex hormones, two sex hormone receptors, sex hormone-binding globulin (SHBG), total IBD and its two subtypes, we performed a two-sample Mendelian randomization (MR) study to analyze their mutual relationship. For estradiol (E2), progesterone (PROG), bioavailable testosterone (BAT), total testosterone (TT) and SHBG, sex-stratified MR analyses were also performed. Inverse variance weighted method, MR-Egger regression and Weighted median method were used for causal analyses. Sensitivity analyses were conducted to test the stability of causal relationships. Besides, a reverse MR analysis was performed to estimate the reverse causation.

Results

E2 (P=0.028) and TT (P=0.034) had protective effects on CD. Sex-stratified analyses revealed protective roles of E2 in males on total IBD (P=0.038) and CD (P=0.020). TT in females had protective effects on total IBD (P=0.025) and CD (P=0.029), and BAT in females decreased the risk of developing CD (P=0.047) and UC (P=0.036). Moreover, SHBG in males was also associated with a decreased risk of CD (P=0.021). The reversed MR analysis showed that CD was negatively correlated with estrogen receptor (P=0.046). UC was negatively correlated with PROG in females (P=0.015) and positively correlated with SHBG levels in males (P=0.046).

Conclusion

Findings of this study revealed the mutual causal associations between sex hormones and the risk of developing IBD.

Novel and emerging drugs for the treatment of Crohn's disease: a review of phase II and III trials

INTRODUCTION

Crohn's disease (CD) is a chronic inflammatory bowel disease characterized by unpredictable flare-ups and periods of remission. While several therapeutic options, such as anti-tumor necrosis factor (TNF), anti-integrin, and interleukin (IL) 12/23 inhibitors, as well as IL-23 and Janus kinase (JAK) inhibitors, have been approved for CD treatment, a substantial number of patients fail to respond adequately or experience a loss of response over time. In recent years, the scientific community has been actively investigating novel agents to address these challenges and improve the management of CD.

AREAS COVERED

This comprehensive narrative review provides an overview of recent developments in CD treatment, summarizing phase 2 and phase 3 clinical trial data. We delve into the clinical efficacy and safety profiles of emerging therapies, encompassing JAK inhibitors, IL-23 inhibitors, anti-adhesion molecules, S1P1 receptor modulators, and combined targeted treatments.

EXPERT OPINION

The armamentarium of CD therapeutic agents is constantly expanding. We analyze pivotal findings from phase 2 and phase 3 CD treatment trials. We also underscore the existing gaps in therapy and the paramount role of ongoing research and innovation in CD management.