S1P/S1PR signaling pathway advancements in autoimmune diseases

Therapeutic potential of apoptotic vesicles in modulating inflammation, immune responses, and tissue regeneration

The process of apoptosis plays a crucial role in tissue homeostasis, immune system regulation, and organ formation. Apoptotic vesicles (ApoEVs) are involved in efferocytosis, the process by which phagocytes ingest dead cells. ApoEVs also have potential therapeutic applications in cancer treatment, ischemic diseases, and their anti-inflammatory properties make them incredibly versatile for medical applications. These vesicles can induce apoptosis in cancer cells, provide tumor antigens for cancer vaccines, and even serve as effective drug delivery systems. Moreover, they can target hypoxic cells, inhibit inflammatory cell death pathways, and promote tissue regeneration. Also, their potential in addressing inflammatory disorders such as gastrointestinal ailments, osteoarthritis, and diabetes is promising. Additionally, ApoEVs can polarize anti-inflammatory immune cells and suppress inflammatory immune responses which make them a viable option for addressing the unmet need for novel anti-inflammatory medications. Despite a wealth of reviews examining the applications of ApoEVs, very few have thoroughly investigated the mechanisms underlying their anti-inflammatory effects. This distinctive approach positions the current review as timely and immensely relevant, illuminating the intriguing ways these entities function beyond their established advantages.

Opaganib Promotes Weight Loss and Suppresses High-Fat Diet-Induced Obesity and Glucose Intolerance

Introduction

Sphingolipid metabolism has been implicated in many diseases including cancer, pathologic inflammation, viral infection, neurologic pathologies and metabolic pathologies, including obesity and diabetes. We have previously shown that opaganib (aka ABC294640) inhibits three key enzymes in the sphingolipid metabolism pathway: sphingosine kinase-2, dihydroceramide desaturase and glucosylceramide synthase. We and others have demonstrated anticancer, anti-inflammatory and antiviral activities of opaganib in multiple experimental models. Furthermore, opaganib has been studied in clinical trials with patients having cancer or severe Covid-19. In the present studies, the effects of opaganib in the well-established model of High-Fat Diet (HFD)-induced obesity have been studied.

Methods

Male or female C57BL/6 mice were fed Control Diet (CD) or HFD and treated with vehicle or opaganib by oral gavage once daily, 5 days per week. Body weights were monitored and glucose tolerance was measured periodically for up to 16 weeks. In some experiments, obese HFD-fed mice were treated with vehicle, opaganib alone, semaglutide alone or opaganib plus semaglutide.

Results

Treatment with opaganib markedly suppressed weight gain in male mice fed the HFD but not in mice given the CD. Compared with mice given CD, mice on the HFD demonstrated poor glucose tolerance at 8, 12 and 16 weeks, consistent with the progression of obesity. Importantly, opaganib treatment of the HFD-fed mice abolished this developing glucose intolerance at all times of measurement. Opaganib treatment also reduced the elevation of hemoglobin A1c and the deposition of inguinal fat in HFD-fed mice. Similar results were obtained with female mice, indicating equivalent efficacy of opaganib in both sexes. Additionally, opaganib and semaglutide were equally effective in promoting body weight loss and improving glucose tolerance in obese mice. Opaganib administered either concurrently with semaglutide or as a single drug following cessation of semaglutide treatment eliminated weight rebound.

Conclusion

Overall, the data indicate that opaganib effectively suppresses the loss of metabolic control in mice on HFD, suggesting that opaganib may be useful alone or in combination with existing therapies for weight management and improve conditions associated with obesity and diabetes.

Sphingosine-1-phosphate in the regulation of diabetes mellitus: a scientometric study to an in-depth review

Diabetes is a significant global health issue, causing extensive morbidity and mortality, and represents a serious threat to human health. Recently, the bioactive lipid molecule Sphingosine-1-Phosphate has garnered considerable attention in the field of diabetes research. The aim of this study is to comprehensively understand the mechanisms by which Sphingosine-1-Phosphate regulates diabetes. Through comprehensive bibliometric analysis and an in-depth review of relevant studies, we investigated and summarized various mechanisms through which Sphingosine-1-Phosphate acts in prediabetes, type 1 diabetes, type 2 diabetes, and their complications (such as diabetic nephropathy, retinopathy, cardiovascular disease, neuropathy, etc.), including but not limited to regulating lipid metabolism, insulin sensitivity, and inflammatory responses. This scholarly work not only unveils new possibilities for using Sphingosine-1-Phosphate in diabetes treatment but also offers fresh insights and recommendations for future research directions to researchers.

A blood-based mRNA signature distinguishes people with Long COVID from recovered individuals

Introduction

Long COVID is a debilitating condition that lasts for more than three months post-infection by SARS-CoV-2. On average, one in ten individuals infected with SARS CoV- 2 develops Long COVID worldwide. A knowledge gap exists in our understanding of the mechanisms, genetic risk factors, and biomarkers that could be associated with Long COVID.

Methods

In this pilot study we used RNA-Seq to quantify the transcriptomes of peripheral blood mononuclear cells isolated from COVID-recovered individuals, seven with and seven without Long COVID symptoms (age- and sex-matched individuals), on average 6 months after infection.

Results

Seventy genes were identified as significantly up- or down-regulated in Long COVID samples, and the vast majority were downregulated. The most significantly up- or downregulated genes fell into two main categories, either associated with cell survival or with inflammation. This included genes such as ICOS (FDR p = 0.024) and S1PR1 (FDR p = 0.019) that were both up-regulated, indicating that a pro-inflammatory state is sustained in Long COVID PBMCs compared with COVID recovered PBMCs. Functional enrichment analysis identified that immune-related functions were expectedly predominant among the up- or down-regulated genes. The most frequently downregulated genes in significantly altered functional categories were two leukocyte immunoglobulin like receptors LILRB1 (FDR p = 0.005) and LILRB2 (FDR p = 0.027). PCA analysis demonstrated that LILRB1 and LILRB2 expression discriminated all of the Long COVID samples from COVID recovered samples.

Discussion

Downregulation of these inhibitory receptors similarly indicates a sustained pro-inflammatory state in Long COVID PBMCs. LILRB1 and LILRB2 should be validated as prospective biomarkers of Long COVID in larger cohorts, over time and against clinically overlapping conditions.

Engineering of Saccharomyces cerevisiae as a platform strain for microbial production of sphingosine-1-phosphate

BACKGROUND

Sphingosine-1-phosphate (S1P) is a multifunctional sphingolipid that has been implicated in regulating cellular activities in mammalian cells. Due to its therapeutic potential, there is a growing interest in developing efficient methods for S1P production. To date, the production of S1P has been achieved through chemical synthesis or blood extraction, but these processes have limitations such as complexity and cost. In this study, we generated an S1P-producing Saccharomyces cerevisiae strain by using metabolic engineering and introducing a heterologous sphingolipid biosynthetic pathway to demonstrate the possibility of microbial S1P production.

RESULTS

To construct the sphingosine-producing S. cerevisiae strain, both the sphingolipid delta 4 desaturase gene (DES1) and the alkaline ceramidase gene (ACER1) derived from Homo sapiens were introduced into the genome of S. cerevisiae by deleting the dihydrosphingosine phosphate lyase gene (DPL1) and the sphingoid long-chain base kinase gene (LCB5) to prevent S1P degradation and byproduct formation, respectively. The sphingosine-producing strain, DDLA, produced sphingolipids containing sphingosine. In flask fed-batch fermentation, the DDLA strain showed a higher production level of sphingosine under aerobic conditions with high initial cell density. The S1P-producing strain was generated by expressing the human sphingosine kinase gene (SPHK1) under the control of the inducible promoter, while deleting the ORM1 gene involved in the regulation of sphingolipid biosynthesis. The S1P-producing strain, DDLAOgS, exhibited the highest sphingosine production level under fed-batch fermentation in a bioreactor, achieving a 2.6-fold increase compared to flask fermentation. S1P biosynthesis in the DDLAOgS strain was verified by qualitative analysis using electrospray ionization mass spectrometry (ESI-MS).

CONCLUSIONS

We successfully developed a metabolically engineered S. cerevisiae as a platform strain for microbial production of S1P by introducing an exogenous pathway of sphingolipids metabolism. The engineered yeast strains showed significant capabilities for sphingolipid production, including S1P. To our knowledge, this is the first report demonstrating that engineered S. cerevisiae can be a major platform strain for producing microbial S1P.

Targeting sphingosine 1-phosphate and sphingosine kinases in pancreatic cancer: mechanisms and therapeutic potential

Pancreatic cancer is known to be the most lethal cancer. Fewer new treatments are being developed for pancreatic cancer as compared to other cancers. The bioactive lipid S1P, which is mainly regulated by sphingosine kinase 1 (SK1) and sphingosine kinase 2 (SK2) enzymes, plays significant roles in pancreatic cancer initiation and exacerbation. S1P controls many signaling pathways to modulate the progression of pancreatic cancer through the G-coupled receptor S1PR1-5. Several papers reporting amelioration of pancreatic cancer via modulation of S1P levels or downstream signaling pathways have previously been published. In this paper, for the first time, we have reviewed the results of previous studies to understand how S1P and its receptors contribute to the development of pancreatic cancer, and whether S1P can be a therapeutic target. In addition, we have also reviewed papers dealing with the effects of SK1 and SK2, which are kinases that regulate the level of S1P, on the pathogenesis of pancreatic cancer. We have also listed available drugs that particularly focus on S1P, S1PRs, SK1, and SK2 for the treatment of pancreatic cancer. Through this review, we would like to suggest that the SK/S1P/S1PR signaling system can be an important target for treating pancreatic cancer, where a new treatment target is desperately warranted.

T cell trafficking in human chronic inflammatory diseases

Circulating T cells, which migrate from the periphery to sites of tissue inflammation, play a crucial role in the development of various chronic inflammatory conditions. Recent research has highlighted subsets of tissue-resident T cells that acquire migratory capabilities and re-enter circulation, referred to here as "recirculating T cells." In this review, we examine recent advancements in understanding the biology of T cell trafficking in diseases where T cell infiltration is pivotal, such as multiple sclerosis and inflammatory bowel diseases, as well as in metabolic disorders where the role of T cell migration is less understood. Additionally, we discuss current insights into therapeutic strategies aimed at modulating T cell circulation across tissues and the application of state-of-the-art technologies for studying recirculation in humans. This review underscores the significance of investigating T trafficking as a novel potential target for therapeutic interventions across a spectrum of human chronic inflammatory diseases.

Chlorogenic acid attenuates cardiac hypertrophy via up-regulating Sphingosine-1-phosphate receptor1 to inhibit endoplasmic reticulum stress

AIMS

Cardiac hypertrophy, an adaptive response of the heart to stress overload, is closely associated with heart failure and sudden cardiac death. This study aimed to investigate the therapeutic effects of chlorogenic acid (CGA) on cardiac hypertrophy and elucidate the underlying mechanisms.

METHODS AND RESULTS

To simulate cardiac hypertrophy, myocardial cells were exposed to isoproterenol (ISO, 10 μM). A rat model of ISO-induced cardiac hypertrophy was also established. The expression levels of cardiac hypertrophy markers, endoplasmic reticulum stress (ERS) markers, and apoptosis markers were measured using quantitative reverse transcription PCR and western blotting. The apoptosis level, size of myocardial cells, and heart tissue pathological changes were determined by terminal deoxynucleotidyl transferase dUTP nick-end labelling staining, immunofluorescence staining, haematoxylin and eosin staining, and Masson's staining. We found that CGA treatment decreased the size of ISO-treated H9c2 cells. Moreover, CGA inhibited ISO-induced up-regulation of cardiac hypertrophy markers (atrial natriuretic peptide, brain natriuretic peptide, and β-myosin heavy chain), ERS markers (C/EBP homologous protein, glucose regulatory protein 78, and protein kinase R-like endoplasmic reticulum kinase), and apoptosis markers (bax and cleaved caspase-12/9/3) but increased the expression of anti-apoptosis marker bcl-2 in a dose-dependent way (0, 10, 50, and 100 μM). Knockdown of sphingosine-1-phosphate receptor 1 (S1pr1) reversed the protective effect of CGA on cardiac hypertrophy, ERS, and apoptosis in vitro (P < 0.05). CGA also restored ISO-induced inhibition on the AMP-activated protein kinase (AMPK)/sirtuin 1 (SIRT1) signalling in H9c2 cells, while S1pr1 knockdown abolished these CGA-induced effects (P < 0.05). CGA (90 mg/kg/day, for six consecutive days) protected rats against cardiac hypertrophy in vivo (P < 0.05).

CONCLUSIONS

CGA treatment attenuated ISO-induced ERS and cardiac hypertrophy by activating the AMPK/SIRT1 pathway via modulation of S1pr1.

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.