Sphingosine 1-phosphate and inflammation

Oncogenic small extracellular vesicles enriched in sphingosine-1-phosphate play a crucial role in pancreatic cancer progression

Small extracellular vesicles (sEVs) from tumour cells mediate intercellular communication and signalling to regulate the progression of pancreatic ductal adenocarcinoma (PDAC). While we and others have shown that PDAC-derived sEVs comprise oncogenic protein and nucleic acid cargo, understanding the lipid landscape of these sEVs remains unknown. Lipids influence both the composition of sEVs and their roles in lipid metabolism and signalling pathways within the tumour microenvironment and tumorigenesis. We hypothesised that specific lipids in oncogenic sEVs might provide insights into PDAC. Comprehensive mass spectrometry-based lipidomic analysis was performed using liquid chromatography-electrospray ionisation-tandem mass spectrometry on sEVs isolated from PDAC and non-malignant pancreatic cell lines, patient-derived xenograft cell lines and plasma from the PDAC transgenic mouse model KPC (KRASWT/G12D/ TP53WT/R172H/Pdx1-Cre+/+). The sEV lipidomic analyses identified over 700 lipid species from 25 lipid classes and subclasses. Our results showed that, compared to non-malignant cells, PDAC-derived sEVs were enriched in specific lysophospholipids, particularly sphingosine-1-phosphate (S1P), a lipid known for its pivotal role in cancer pathogenesis. S1P enrichment was validated in plasma-derived sEVs from KPC mice compared to WT. To explore the functional implications of S1P enrichment, we conducted assays demonstrating that S1P in sEVs facilitated tubule formation in human microvascular endothelial cells and promoted cancer-associated fibroblast cell migration. We show that PDAC-derived sEVs are differentially enriched in specific lipids associated with cancer phenotype. Our findings highlight that PDAC-derived sEVs are enriched in specific lipids, particularly S1P, which plays a crucial role in promoting cancer progression.

Stress Accelerates Depressive-Like Behavior through Increase of SPNS2 Expression in Tg2576 Mice

To investigate the relationship between depression and AD, water avoidance stress (WAS) was induced for 10 days in both Tg2576 mice and wild-type (WT) mice. After WAS, memory function and depressive-like behavior were investigated in Tg2576 mice. Tg2576 WAS mice exhibited more depressive-like behaviors than WT WAS and Tg2576 control (CON) mice. Strikingly, Tg2576 CON mice showed more depressive-like behaviors than WT mice. Moreover, corticosterone and phospho-glucocorticoid receptor (p-GR) levels were also higher in Tg2576 WAS mice in comparison to Tg2576 CON mice. Spinster homologue 2 (SPNS2) is a member of non-ATP-dependent transporter. The role of SPNS2 was widely known as a sphingosine-1-phosphate (S1P) transporter, which export intracellular S1P from cells. Using GEO database to analyze SPNS2 gene expression changes in patients with AD and depression, we show that SPNS2 gene expression correlates with AD and depression. Interestingly, Tg2576 WAS mice displayed significantly increased levels of SPNS2 w1hen compared to Tg2576 CON counterparts. SPNS2 levels were also higher in Tg2576 CON mice in comparison with WT CON mice. Remarkably, we found a decrease in S1P brain levels and an increase in S1P serum levels of Tg2576 WAS mice in comparison with Tg2576 CON mice. Accordingly, WAS induced group further decreased S1P levels in the brains. However, the level in the serum further increased in comparison with non-induced group. Therefore, these results suggest that AD and depression could be associated, and that Tg2576 transgenic mice are more susceptible to stress-induced depression through the release of S1P by SPNS2 up-regulation.

Dual action of sphingosine 1-phosphate pathway in in vitro models of global cerebral ischemia

It is well accepted that sphingolipids play an important role in the pathological process of cerebral ischemia. In the present study we have investigated the involvement of sphingosine 1-phosphate (S1P) pathway in two different in vitro models of global ischemia. In organotypic hippocampal slices exposed to oxygen and glucose deprivation (OGD) we evaluated the mRNA expression of S1P metabolic enzymes and receptors (S1P1-5) by Real Time-PCR. In the same model we investigated the effect of the inhibitor of S1P lyase (SPL), LX2931, the selective antagonists of S1P2, JTE-013, and S1P3, CAY10444, quantifying the cell death in the CA1 region by propidium iodide fluorescence, and morphological and tissue organization alterations by immunohistochemistry and confocal microscopy. Moreover, we performed extracellular recordings of field excitatory postsynaptic potentials in acute slices exposed to OGD. In organotypic slices OGD induced a significant increase of SPL at mRNA level and of S1P2 and S1P3 at both mRNA and protein level. The incubation with LX2931, JTE-013 or CAY10444 was able to reduce CA1 damage induced by OGD in organotypic slices and provoked a significant delay of the onset of anoxic depolarization on acute slices. Moreover, S1P2 and S1P3 antagonists prevented the increase of TREM2 induced by OGD. Our results reveal a dual role of S1P pathway in brain ischemia: intracellular S1P, degraded via SPL, appears to be beneficial whereas signaling via S1P2 and S1P3 is detrimental to the disease. These findings support the notion that SPL, S1P2 and S1P3 are promising therapeutic targets in brain ischemia.

Delineating the intricacies of polymorphisms, structures, functions and therapeutic applications of biological high-density lipoprotein-apolipoprotein M: A review

Apolipoprotein-M (ApoM), primarily associated with high-density lipoproteins (HDL), plays a crucial role in lipid metabolism and cardiovascular health. It facilitates the transport of lipids such as cholesterol and sphingosine-1-phosphate (S1P), contributing to reverse cholesterol transport (RCT), which removes excess cholesterol from peripheral tissues to the liver for excretion. Through its association with HDL and S1P, ApoM exerts anti-inflammatory, anti-thrombotic, and anti-apoptotic effects. The ApoM-S1P complex regulates various cellular, immunological, and physiological processes via S1P receptors, and its dysregulation is linked to metabolic and inflammatory disorders. Reduced plasma ApoM levels are associated with atherosclerosis, diabetes, and chronic systemic inflammation. ApoM levels and paraoxonase-1 activity in early pregnancy correlate with gestational hypertension risk, potentially affecting fetal vascular health. ApoM also functions as a S1P chaperone, and recent research highlights the roles of ApoM/S1P axis and the ApoA1-ApoM (A1M) complex in glucose and lipid metabolism, emphasizing its therapeutic relevance in cardiovascular diseases (CVD), cancer, and diabetes. The ApoM-Fc fusion protein exhibits promising therapeutic potential by reducing fibrosis, enhancing endothelial function, and promoting tissue regeneration. HDL-ApoM macromolecules bind bacterial endotoxins and aids in its clearance. This review explores ApoM gene organization, isoforms, point mutations, protein structure, functions and their relevance for developing novel therapeutics.

An unraveled mystery: What's the role of brain sphingolipids in neurodegenerative and psychiatric disorders

Sphingolipids are a class of lipids highly expressed in brain, especially in the myelin sheath of white matter. In recent years, with the development of lipidomics, the role of brain sphingolipids in neurological disorders have raised lots of interests due to their function in neuronal signal transduction and survival. Although not thoroughly investigated, some previous studies have indicated that sphingolipids homeostasis are closely linked to the etiology and development of some neurological disorders. For example, disrupted sphingolipids level have been found in clinic patients with neurological disorders, such as neurodegeneration and psychiatric disorders. Conversely, intervention of sphingolipids metabolism by modulating activity of related enzymes also could result in pathological deficits identified in neurological disorders. Moreover, the alteration of sphingolipids catabolic pathway in the brain could be partly represented in cerebrospinal fluid and blood tissues, which show diagnostic potential for neurological disorders. Therefore, our review aims to summarize and discuss the known contents of bioactive sphingolipid metabolism with their related studies in neurodegenerative and psychiatric disorders, to help understand the potential mechanism underlying sphingolipid regulation of neural function and provide possible directions for further study. The new perspectives in this promising field will open up new therapeutic options for neurological disorders.

Cerebrospinal fluid metabolomics in autistic regression reveals dysregulation of sphingolipids and decreased β-hydroxybutyrate

BACKGROUND

Autism is highly heritable, however actionable genetic findings are only found in a minority of patients. Many people with autism suffer loss of neurodevelopmental skills, known as autistic regression. The cause of regression is poorly understood, and the diagnostic and therapeutic pathways are lacking.

METHODS

We used untargeted metabolomics using a UPLC-Q-Exactive-HFx Mass Spectrometry to examine cerebrospinal fluid (CSF) from twenty-two patients with autistic regression compared to sixteen controls with neurodevelopmental disorders (but not autistic regression) and thirty-four controls with other neurological disease (headache, encephalitis, epilepsy). The twenty-two patients with autistic regression consisted of two groups: early (infantile) autistic regression <2 years of age (n = 8), and later regression of skills >4 years of age, often in the context of pre-existing developmental concerns (n = 14). Metabolites of interest were then quantified and validated using targeted assays.

FINDINGS

Untargeted case-control studies revealed good separation of patients from controls using multivariate analysis. β-hydroxybutyrate was significantly decreased in the CSF of patients with autistic regression, and the findings were validated using a targeted β-hydroxybutyrate assay. The sphingolipid, sphingosine-1-phosphate was significantly elevated in the discovery case-control studies, and sphingolipid metabolism pathways were also significantly dysregulated. We therefore developed a targeted metabolite assay of forty sphingolipids. After FDR correction, 21 of the 40 sphingolipids were significantly dysregulated (pFDR < 0.05) (Benjamini-Hochberg correction) in autistic regression compared to the neurodevelopmental controls, and 26 of the 40 sphingolipids were significantly dysregulated in autistic regression compared to other neurological controls, with elevated ceramides, hexosylceramides, sphingosines (including sphingosine-1-phosphate), and sulfatides. By contrast, sphingomyelin levels were generally decreased in autistic regression.

INTERPRETATION

Our data shows the potential utility of CSF metabolomics in the context of autistic regression, a clinical syndrome which has historically lacked pathophysiological biomarkers and disease modifying therapies.

FUNDING

Financial support for the study was granted by Dale NHMRC Investigator grant APP1193648, Petre Foundation, Cerebral Palsy Alliance, and Ainsworth and SCHF Neuroscience grant scheme.

Ex Vivo Overactivation of Lymphocyte Subsets in Fibrotic Hypersensitivity Pneumonitis Is Blunted by a Sphingosine-1-Phosphate Receptor Ligand

Lymphocytes are central to the pathogenesis of hypersensitivity pneumonitis and a strong body of evidence supports that lymphocytes are modulated by sphingosine-1-phosphate receptor-modifying drugs. This exploratory study aimed to determine if a pharmacological sphingosine-1-phosphate receptor ligand interfered with the activation of lymphocytes obtained from fibrotic hypersensitivity pneumonitis patients. Peripheral blood mononuclear cells of 12 patients and 10 control subjects were submitted to CD3/CD28 stimulation, isolated B cells were incubated with a TLR9 ligand; and we tested how these stimulations were impacted by ozanimod, a sphingosine-1-phosphate receptor ligand. T cell and B cell subsets from patients overexpressed CD69 and cytokines such as TNF and IL-4 in response to CD3/CD28 stimulation, compared to controls. In patients with fibrotic hypersensitivity pneumonitis, ozanimod alleviated CD3/CD28 induction of CD69, IL-4, and TNF in CD8, but not CD4 T cells. In isolated B cells stimulated with a TLR9 ligand, ozanimod reduced cell surface expression of CD69, CD86, and CD40, as well as TNF and IL-6 accumulation in supernatant. We conclude that lymphocyte subsets are functionally impacted in patients with fibrotic hypersensitivity pneumonitis and that ozanimod can interfere ex vivo with the overactivation of B cells and CD8 T cells in response to specific stimuli.

Lipid metabolism-associated metabolites on cardiovascular diseases: a two-sample Mendelian randomized study

Background

There is a growing body of evidence indicating that metabolites are associated with an increased risk of cardiovascular diseases (CVDs), the underlying causality of these associations remains largely unchallenged. Given the inherent difficulty in establishing causality using epidemiological data, we employed the technique of Mendelian randomization to investigate the potential role of plasma metabolite factors in influencing the risk of CVDs.

Methods

The exposure was based on 1,400 plasma metabolites, and outcomes involved four CVD datasets from public databases. Initial causality was assessed by inverse variance weighting (IVW), followed by sensitivity analyses using MR-Egger regression, weighted median, and Multiple Effectiveness Residual Sums and Outliers (MR-PRESSO) method. Potential heterogeneity and multivalence were assessed using the MR-Egger intercept and Cochran's Q statistic. After Bonferroni correction, causal associations were found to be significant with p-values less than 0.05. All statistical analyses were rigorously executed in R software.

Results

Our findings identified causal relationships between 15 metabolites and cardiovascular disease. Of these, 4 were associated with AA (aortic aneurysm), 7 with atrial fibrillation and flutter, 2 with HF (heart failure), and 3 with stroke.

Conclusion

This is the first systematic mendelian randomization analysis using genome-wide data to assess the causal relationship between serum metabolites and different cardiovascular diseases, providing preliminary evidence for the impact of lipid metabolism disorders on cardiovascular disease risk.

Adiponectin mediated metabolic and sphingolipid alterations in preventing endothelial dysfunction

Endothelial dysfunction is an early indicator of atherosclerosis. Adiponectin, a hormone secreted by adipose tissue with insulin-sensitizing and anti-inflammatory properties, offers protection against atherosclerosis. This study investigated the metabolic and sphingolipid alterations in endothelial cells linked to the protective effects of adiponectin against endothelial dysfunction. Human Umbilical Endothelial Cells (HUVECs) were treated with Tumor Necrosis Factor-alpha (TNF-α) to induce endothelial dysfunction. AdipoRon and SKI-I were used to study the effects of adiponectin and sphingosine kinase inhibition in HUVECs. Metabolic changes and sphingolipid alterations were assessed to understand changes in lipid metabolism, and RNA sequencing was used to quantify the transcriptomics changes. TNF-α treatment significantly upregulated glycolysis and downregulated long-chain fatty acid oxidation and mitochondrial ATP production, while AdipoRon co-treatment partially reversed these metabolic effects. In HUVECs, TNF-α treatment increased intracellular C16 and C18 ceramides and Sphingosine 1-Phosphate (S1P) while decreasing extracellular S1P. AdipoRon Co-treatment reversed these effects; AdipoRon also reversed the transcriptional changes induced by TNF-α. Sphingosine kinase inhibition in HUVECs led to mitochondrial dysfunction at the metabolic and transcriptional levels. This study provides insights into potential therapeutic strategies targeting endothelial metabolism while unraveling a novel mitochondrial modulation mediated by sphingosine kinases in endothelial cells.

Sphingosine-1-phosphate signaling regulates the ability of Müller glia to become neurogenic, proliferating progenitor-like cells

The purpose of these studies is to investigate how Sphingosine-1-phosphate (S1P) signaling regulates glial phenotype, dedifferentiation of Müller glia (MG), reprogramming into proliferating MG-derived progenitor cells (MGPCs), and neuronal differentiation of the progeny of MGPCs in the chick retina. We found that S1P-related genes are highly expressed by retinal neurons and glia, and levels of expression were dynamically regulated following retinal damage. Drug treatments that activate S1P receptor 1 (S1PR1) or increase levels of S1P suppressed the formation of MGPCs. Conversely, treatments that inhibit S1PR1 or decrease levels of S1P stimulated the formation of MGPCs. Inhibition of S1P receptors or S1P synthesis significantly enhanced the neuronal differentiation of the progeny of MGPCs. We report that S1P-related gene expression in MG is modulated by microglia and inhibition of S1P receptors or S1P synthesis partially rescues the loss of MGPC formation in damaged retinas missing microglia. Finally, we show that TGFβ/Smad3 signaling in the resting retina maintains S1PR1 expression in MG. We conclude that the S1P signaling is dynamically regulated in MG and MGPCs in the chick retina, and activation of S1P signaling depends, in part, on signals produced by reactive microglia.

Enhancing Lung Recovery: Inhaled Poly(lactic-co-glycolic) Acid Encapsulating FTY720 and Nobiletin for Lipopolysaccharide-Induced Lung Injury, with Advanced Inhalation Tower Technology

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), a rapidly progressing respiratory failure condition, results in a high mortality rate, especially in severe cases. Numerous trials have investigated various pharmacotherapy approaches, but their effectiveness remains uncertain. Here, we present an inhaled nanoformulation of fingolimod (FTY720)-nobiletin (NOB)- poly(lactic-co-glycolic) acid (PLGA) nanoparticles (NPs) with good biocompatibility and a sustained-release pharmacological effect. The formulation decreases the toxicity of FTY720 and increases the bioavailability of NOB since we use PLGA with a high biocompatibility to encapsulate FTY720 and NOB at the same time. In vitro, in comparison to treatment with the pure drug, we demonstrated that FTY720-NOB-PLGA NPs can reduce interleukin-6 (IL-6) and reactive oxygen species (ROS) release by macrophages after lipopolysaccharide (LPS) stimulation more efficiently. In vivo, we used an inhalation tower system that allowed the exposure of unanesthetized mice to aerosolized FTY720-NOB-PLGA NPs under controlled conditions. We demonstrated that inhaled FTY720-NOB-PLGA NPs can attenuate lung injury after LPS exposure by suppressing cytokine release, such as IL-6 and tumor necrosis factor-α (TNF-α). The trigger pathway of ALI, including nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) and p38 mitogen-activated protein kinase, was also efficiently inhibited. Furthermore, the inhalation treatment provided a good safety profile, without detrimental effects on biochemical markers and lung function. We provided the feasibility of administering inhalation of NPs noninvasively with continuous monitoring of lung function. The aerosolized FTY720-NOB-PLGA NPs we developed show excellent promise for acute lung injury therapy in the future.

Supplementation with Lentil (Lens culinaris) Hull Soluble Dietary Fiber Ameliorates Sodium Dextran Sulfate-Induced Colitis and Behavioral Deficits via the Gut-Brain Axis

In this study, the impact of lentil hull soluble dietary fibers (SDFs) on colitis and behavioral deficits in mice was assessed. Structural characterizations of SDFs confirmed that cellulase-modified soluble dietary fiber exhibited better physicochemical properties: more porous microstructure; similar polysaccharide structure; more stable particle size distribution; higher crystallinity; better adsorption capacity; and lower viscosity. Additionally, we explored its potential cognitive benefits via the gut-brain axis by behavioral tests, histopathology, 16S rRNA sequencing, gas chromatography and metabolomics analysis. The results showed that SDFs significantly improved inflammatory symptoms in colon and brain and cognitive behaviors. LSDF had better efficacy than HSDF. LSDF intervention decreased the harmful bacteria abundance (Bacteroides, Flexispira and Escherichia, etc.) and increased beneficial bacteria abundance (Aggregatibacter and Helicobacter, etc.). LSDF also affected brain metabolites through the sphingolipid metabolism. Spearman correlation analysis showed that there was a positive correlation between harmful bacteria with inflammatory factors (LPS, IL-1β, IL-6, and TNF-α, etc.) and sphingolipid metabolites, while beneficial bacteria were positively correlated with brain-derived neurotrophic factor (BDNF), IL-10, and cognitive behavior. This study highlights the value of SDFs in future diet-based therapeutic strategies targeting gut-brain interactions.

Small Molecules in the Treatment of Acute Severe Ulcerative Colitis: A Review of Current Evidence

Ulcerative colitis (UC) is an inflammatory bowel disease in which one-quarter of patients are at risk of developing a severe form of the disease known as acute severe UC (ASUC). This condition exposes patients to serious complications, including toxic megacolon, surgical intervention, and even death. The current therapeutic strategy relies on time-dependent, multi-step algorithms that integrate systemic corticosteroids, calcineurin inhibitors, and biologic agents (specifically infliximab) as medical therapy aimed at avoiding colectomy. Despite this approach, a significant proportion of patients fail to respond to either corticosteroids or infliximab and may require alternative therapeutic options if there is no urgent surgical necessity. These alternatives include other biologics or emerging small molecules, although the evidence supporting these treatments remains extremely low, even considering their well-documented and promising efficacy and safety in moderate-to-severe UC. Conversely, it is necessary to investigate whether infliximab can be effectively replaced or surpassed by other approved biological agents and small molecules as first-line therapy after steroid resistance. This review aims to summarise the available evidence on small molecules, specifically Janus kinase inhibitors and sphingosine-1-phosphate receptor modulators.

Sphingosine-1-phosphate signaling through Müller glia regulates neuroprotection and the accumulation of immune cells in the rodent retina

The purpose of this study was to investigate how Sphingosine-1-phosphate (S1P) signaling regulates glial phenotype, neuroprotection, and reprogramming of Müller glia (MG) into neurogenic MG-derived progenitor cells (MGPCs) in the adult mouse retina. We found that S1P-related genes were dynamically regulated following retinal damage. S1pr1 (encoding S1P receptor 1) and Sphk1 (encoding sphingosine kinase 1) are expressed at low levels by resting MG and are rapidly upregulated following acute damage. Overexpression of the neurogenic bHLH transcription factor Ascl1 in MG downregulates S1pr1, and inhibition of Sphk1 and S1pr1/3 enhances Ascl1-driven differentiation of bipolar-like cells and suppresses glial differentiation. Treatments that activate S1pr1 or increase retinal levels of S1P initiate pro-inflammatory NFκB-signaling in MG, whereas treatments that inhibit S1pr1 or decreased levels of S1P suppress NFκB-signaling in MG in damaged retinas. Conditional knock-out of NFκB-signaling in MG increases glial expression of S1pr1 but decreases levels of S1pr3 and Sphk1. Conditional knock-out (cKO) of S1pr1 in MG, but not Sphk1, enhances the accumulation of immune cells in acutely damaged retinas. cKO of S1pr1 is neuroprotective to ganglion cells, whereas cKO of Sphk1 is neuroprotective to amacrine cells in NMDA-damaged retinas. Consistent with these findings, pharmacological treatments that inhibit S1P receptors or inhibit Sphk1 had protective effects upon inner retinal neurons. We conclude that the S1P-signaling pathway is activated in MG after damage and this pathway acts secondarily to restrict the accumulation of immune cells, impairs neuron survival and suppresses the reprogramming of MG into neurogenic progenitors in the adult mouse retina.

PET Imaging of Sphingosine-1-Phosphate Receptor 1 with [18F]TZ4877 in Nonhuman Primates

PURPOSE

The sphingosine-1-phosphate receptor-1 (S1PR1) is involved in regulating responses to neuroimmune stimuli. There is a need for S1PR1-specific radioligands with clinically suitable brain pharmcokinetic properties to complement existing radiotracers. This work evaluated a promising S1PR1 radiotracer, [18F]TZ4877, in nonhuman primates.

PROCEDURES

[18F]TZ4877 was produced via nucleophilic substitution of tosylate precursor with K[18F]/F- followed by deprotection. Brain PET imaging data were acquired with a Focus220 scanner in two Macaca mulatta (6, 13 years old) for 120-180 min following bolus injection of 118-163 MBq [18F]TZ4877, with arterial blood sampling and metabolite analysis to measure the parent input function and plasma free fraction (fP). Each animal was scanned at baseline, 15-18 min after 0.047-0.063 mg/kg of the S1PR1 inhibitor ponesimod, 33 min after 0.4-0.8 mg/kg of the S1PR1-specific compound TZ82112, and 167-195 min after 1 ng/kg of the immune stimulus endotoxin. Kinetic analysis with metabolite-corrected input function was performed to estimate the free fraction corrected total distribution volume (VT/fP). Whole-body dosimetry scans were acquired in 2 animals (1M, 1F) with a Biograph Vision PET/CT System, and absorbed radiation dose estimates were calculated with OLINDA.

RESULTS

[18F]TZ4877 exhibited fast kinetics that were described by the reversible 2-tissue compartment model. Baseline [18F]TZ4877 fP was low (<1%), and [18F]TZ4877 VT/fP values were 233-866 mL/cm3. TZ82112 dose-dependently reduced [18F]TZ4877 VT/fP, while ponesimod and endotoxin exhibited negligible effects on VT/fP, possibly due to scan timing relative to dosing. Dosimetry studies identified the critical organs of gallbladder (0.42 (M) and 0.31 (F) mSv/MBq) for anesthetized nonhuman primate.

CONCLUSIONS

[18F]TZ4877 exhibits reversible kinetic properties, but the low fP value limits reproducible quantification with this radiotracer. S1PR1 is a compelling PET imaging target, and these data support pursuing alternative F-18 labeled radiotracers for potential future human studies.

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.

Relationship between Abnormal Lipid Metabolism and Gallstone Formation

Cholelithiasis is a common biliary system disease with a high incidence worldwide. Abnormal lipid metabolism has been shown to play a key role in the mechanism of gallstones. Therefore, recent research literature on the genes, proteins, and molecular substances involved in lipid metabolism during the pathogenesis of gallstones has been conducted. This study aimed to determine the role of lipid metabolism in the pathogenesis of gallstones and provide insights for future studies using previous research in genomics, metabolomics, transcriptomics, and other fields.

Sphingosine-1-phosphate signaling regulates the ability of Müller glia to become neurogenic, proliferating progenitor-like cells

The purpose of these studies is to investigate how Sphingosine-1-phosphate (S1P) signaling regulates glial phenotype, dedifferentiation of Müller glia (MG), reprogramming into proliferating MG-derived progenitor cells (MGPCs), and neuronal differentiation of the progeny of MGPCs in the chick retina. We found that S1P-related genes are highly expressed by retinal neurons and glia, and levels of expression were dynamically regulated following retinal damage. Drug treatments that activate S1P receptor 1 (S1PR1) or increase levels of S1P suppressed the formation of MGPCs. Conversely, treatments that inhibit S1PR1 or decrease levels of S1P stimulated the formation of MGPCs. Inhibition of S1P receptors or S1P synthesis significantly enhanced the neuronal differentiation of the progeny of MGPCs. We report that S1P-related gene expression in MG is modulated by microglia and inhibition of S1P receptors or S1P synthesis partially rescues the loss of MGPC formation in damaged retinas missing microglia. Finally, we show that TGFβ/Smad3 signaling in the resting retina maintains S1PR1 expression in MG. We conclude that the S1P signaling is dynamically regulated in MG and MGPCs in the chick retina, and activation of S1P signaling depends, in part, on signals produced by reactive microglia.

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.

Lipid remodeling in context of cellular senescence

Cellular senescence is a response that irreversibly arrests stressed cells thus providing a potent tumor suppressor mechanism. In parallel, senescent cells exhibit an immunogenic secretome called SASP (senescence-associated secretory phenotype) that impairs tissue homeostasis and is involved in numerous age-related diseases. Senescence establishment is achieved through the unfolding of a profound transcriptional reprogramming together with morphological changes. These alterations are accompanied by important metabolic adaptations characterized by biosynthetic pathways reshuffling and lipid remodeling. In this mini-review we highlight the intricate links between lipid metabolism and the senescence program and we discuss the potential interventions on lipid pathways that can alleviate the senescence burden.

A role for plasma membrane Ca2+ ATPases in regulation of cellular Ca2+ homeostasis by sphingosine kinase-1

Sphingosine-1-phosphate (S1P) is a ubiquitous lipid mediator, acting via specific G-protein-coupled receptors (GPCR) and intracellularly. Previous work has shown that deletion of S1P lyase caused a chronic elevation of cytosolic [Ca2+]i and enhanced Ca2+ storage in mouse embryonic fibroblasts. Here, we studied the role of sphingosine kinase (SphK)-1 in Ca2+ signaling, using two independently generated EA.hy926 cell lines with stable knockdown of SphK1 (SphK1-KD1/2). Resting [Ca2+]i and thapsigargin-induced [Ca2+]i increases were reduced in both SphK1-KD1 and -KD2 cells. Agonist-induced [Ca2+]i increases, measured in SphK1-KD1, were blunted. In the absence of extracellular Ca2+, thapsigargin-induced [Ca2+]i increases declined rapidly, indicating enhanced removal of Ca2+ from the cytosol. In agreement, plasma membrane Ca2+ ATPase (PMCA)-1 and -4 and their auxiliary subunit, basigin, were strongly upregulated. Activation of S1P-GPCR by specific agonists or extracellular S1P did not rescue the effects of SphK1 knockdown, indicating that S1P-GPCR were not involved. Lipid measurements indicated that not only S1P but also dihydro-sphingosine, ceramides, and lactosylceramides were markedly depleted in SphK1-KD2 cells. SphK2 and S1P lyase were upregulated, suggesting enhanced flux via the sphingolipid degradation pathway. Finally, histone acetylation was enhanced in SphK1-KD2 cells, and the histone deacetylase inhibitor, vorinostat, induced upregulation of PMCA1 and basigin on mRNA and protein levels in EA.hy926 cells. These data show for the first time a transcriptional regulation of PMCA1 and basigin by S1P metabolism. It is concluded that SphK1 knockdown in EA.hy926 cells caused long-term alterations in cellular Ca2+ homeostasis by upregulating PMCA via increased histone acetylation.

Evaluation of proximod, a selective agonist of sphingosine-1-phosphate receptor-1, in healthy volunteers and patients with rheumatoid arthritis: a phase 1, double-blind, randomised, placebo-controlled, ascending dose trial

BACKGROUND

Proximod is a selective agonist of sphingosine-1-phosphate receptor-1 (S1PR1). It acts by redirecting lymphocytes from the circulation to secondary lymph nodes, and is under development as an immunomodulator for rheumatoid arthritis. We aimed to evaluate the safety, pharmacokinetics, and preliminary efficacy of proximod in healthy volunteers and patients with rheumatoid arthritis.

METHODS

We did a two part, phase 1, double-blind, randomised, placebo-controlled, ascending dose trial at a single centre in China. Eligible participants were adults aged 18-50 years with a BMI of 18-28 kg/m2 for healthy volunteers and aged 18-70 years with a BMI of 18-30 kg/m2 for patients with rheumatoid arthritis. In part 1, healthy volunteers were randomly assigned within ten cohorts to receive a single oral dose of proximod (0·125 mg, 0·25 mg, 0·5 mg, 1 mg, 1·5 mg, 2 mg, 3 mg, 5 mg, 10 mg, or 15 mg in cohorts 1-10) or placebo. In part 2, healthy volunteers were randomly assigned to receive once-daily doses of proximod 5 mg or placebo, and patients with rheumatoid arthritis were randomly assigned to receive once-daily doses of proximod 5 mg, proximod 10 mg, or placebo, for 28 days. Patients and investigators were masked to treatment assignment. The primary outcomes were safety, tolerability, and pharmacokinetic profile of proximod for 72 days in healthy volunteers and for 48 days in patients with rhematoid arthritis, assessed in all treated participants. This trial is registered with ClinicalTrials.gov (NCT06361199, NCT06361186), and is complete.

FINDINGS

Between Nov 1, 2017, and June 22, 2021, 124 healthy volunteers were randomly assigned in part 1 of the study and 124 were included in the analyses (mean age 34·3 years [SD 6·9], 62 [50%] of 124 participants were women and 62 [50%] were men, and 116 [94%] were Han Chinese ethnicity). Between Feb 16, 2022, and Oct 8, 2023, 113 participants were screened for inclusion in part 2 (80 healthy volunteers and 33 patients with rheumatoid arthritis). 79 participants were excluded and 34 were randomly assigned (10 healthy participants and 24 patients with rheumatoid arthritis), 34 of whom were included in the analyses. Ten (100%) of ten healthy participants were Han Chinese ethnicity, with a mean age of 39·9 years (SD 7·3). Five (50%) of ten healthy volunteers were women and five (50%) were men). 22 (92%) of 24 participants with rheumatoid arthritis were Han Chinese ethnicity, with a mean age of 52·7 years (SD 6·8). 22 (92%) of 24 patients with rheumatoid arthritis were women and two (8%) were men. In part 1, all doses of proximod were well tolerated, with no dose-related adverse reactions or serious adverse events observed. In part 2, 74 adverse reactions were reported in eight (80%) of ten healthy volunteers and 22 (92%) of 24 patients with rheumatoid arthritis. Adverse events associated with proximod were predominantly mild or moderate. In part 2, the concentration of proximod and its active metabolite, proximod-phosphate, gradually increased in all three groups receiving proximod and the EC50 of the S1PR1 agonist for proximod-phosphate (6·1 ng/mL) was reached on day 14 for both 5 mg groups, and on day 7 for the 10 mg group. The mean Ctrough values for proximod-phosphate on day 28 were 7·7 ng/mL and 10·2 ng/mL for 5 mg in healthy volunteers and patients with rheumatoid arthritis, respectively, and 15·3 ng/mL for 10 mg in patients with rheumatoid arthritis. In patients with rheumatoid arthritis, lymphocyte count decreased after treatment in all proximod groups reaching nadir at approximately day 28, with a corresponding percentage decline from baseline of 65·25% in the 5 mg group, 71·64% in the 10 mg group, and 20·57% in the placebo group.

INTERPRETATION

Proximod exhibited good tolerability over the 28-day treatment period, demonstrating its potential in reducing blood lymphocyte count. These results highlight the promise of the S1PR1 agonist proximod as a potential candidate for rheumatoid arthritis treatment, warranting further investigation in subsequent clinical studies.

FUNDING

Beijing Union Pharmaceutical Factory and Jian Kuan (Suzhou) Biotechnology.

Sphingosine-1-phosphate signalling in the heart: exploring emerging perspectives in cardiopathology

Cardiometabolic disorders contribute to the global burden of cardiovascular diseases. Emerging sphingolipid metabolites like sphingosine-1-phosphate (S1P) and its receptors, S1PRs, present a dynamic signalling axis significantly impacting cardiac homeostasis. S1P's intricate mechanisms extend to its transportation in the bloodstream by two specific carriers: high-density lipoprotein particles and albumin. This intricate transport system ensures the accessibility of S1P to distant target tissues, influencing several physiological processes critical for cardiovascular health. This review delves into the diverse functions of S1P and S1PRs in both physiological and pathophysiological conditions of the heart. Emphasis is placed on their diverse roles in modulating cardiac health, spanning from cardiac contractility, angiogenesis, inflammation, atherosclerosis and myocardial infarction. The intricate interplays involving S1P and its receptors are analysed concerning different cardiac cell types, shedding light on their respective roles in different heart diseases. We also review the therapeutic applications of targeting S1P/S1PRs in cardiac diseases, considering existing drugs like Fingolimod, as well as the prospects and challenges in developing novel therapies that selectively modulate S1PRs.

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.

Protective Role of High-Density Lipoprotein in Multiple Sclerosis

Multiple sclerosis (MS) is a chronic, progressive demyelinating disease with a most likely autoimmune background and a neurodegenerative component. Besides the demyelinating process caused by autoreactive antibodies, an increased permeability in the blood-brain barrier (BBB) also plays a key role. Recently, there has been growing interest in assessing lipid profile alterations in patients with MS. As a result of myelin destruction, there is an increase in the level of cholesterol released from cells, which in turn causes disruptions in lipid metabolism homeostasis both in the central nervous system (CNS) and peripheral tissues. Currently, there is a growing body of evidence suggesting a protective role of HDL in MS through its effect on the BBB by decreasing its permeability. This follows from the impact of HDL on the endothelium and its anti-inflammatory effect, mostly by interacting with adhesion molecules like vascular cell adhesion molecule 1 (VCAM-1), intercellular adhesion molecule 1 (ICAM-1), and E-selectin. HDL, through its action via sphingosine-1-phosphate, exerts an inhibitory effect on leukocyte migration, and its antioxidant properties contribute to the improvement of the BBB function. In this review, we want to summarize these studies and focus on HDL as a mediator of the anti-inflammatory response in MS.

Novel triazine-tyrosine hybrids containing thiyazol or pyridine fragment as anti-multiple sclerosis agents: Design, synthesis, biological evaluation, and molecular docking study

In this study novel triazine-tyrosine hybrids containing thiazole or pyridine fragments were introduced as anti- Multiple Sclerosis agents. The compounds were designed according to the structure of the Sphingosine-1-phosphate receptor subtype 1 (S1P1) modulator, fingolimode. At first, docking studies was performed using crystal structures of S1P1 and Sphingosine-1-phosphate receptor subtype 3 (S1P3) to theoretically identify the selectivity of the compounds towards the S1P1 isoform. The docking results showed better binding energy (lower ΔGb) and therefore higher selectivity for S1P1 receptor than S1P3 receptor. Subsequently the designed compounds were synthesized according to proper chemical reactions and structurally analyzed with FTIR and NMR spectrophotometers. Considering the importance of the S1P1 receptor in release of lymphocytes and therefore inflammation produced in Multiple Sclerosis disease, the synthesized compounds were investigated to study lymphocyte reduction in an animal model. Compound (8e) with 2-mercaptobenzothiazole substitution at doses of 1 and 3 mg/kg showed significant reduction effect on the percentage of lymphocytes (68.80 %, 56.75 %) compared to the fingolimod (65.73 %, 20.66 %), as the positive control group.

The adipocyte apolipoprotein M is negatively associated with inflammation

Obesity is associated with the development of local adipose tissue (AT) and systemic inflammation. Most adipokines are upregulated with obesity and have pro-inflammatory properties. Few are downregulated and possess beneficial anti-inflammatory effects. The apolipoprotein M (APOM) is an adipokine whose expression is low during obesity and associated with a metabolically healthy AT. Here, the role of adipose-derived APOM on obesity-associated AT inflammation was investigated by measuring the expression of pro-inflammatory genes in human and mouse models. In 300 individuals with obesity, AT APOM mRNA level was negatively associated with plasma hs-CRP. The inflammatory profile was assessed in Apom-/- and WT mice fed a normal chow diet (NCD), or a high-fat diet (HFD) to induce AT inflammation. After HFD, mice had a higher inflammatory profile in AT and liver, and a 50% lower Apom gene expression compared with NCD-fed mice. Apom deficiency was associated with a higher inflammatory signature in AT compared with WT mice but not in the liver. Adeno-associated viruses encoding human APOM were used to induce APOM overexpression: in vivo, in WT mice AT prior to HFD; in vitro, in human adipocytes which conditioned media was applied to ThP-1 macrophages. The murine AT overexpressing APOM gene had a reduced inflammatory profile. The macrophages treated with APOM-enriched media from adipocytes exhibited lower IL6 and MCP1 gene expression compared with macrophages treated with control media, independently of S1P. Our study highlights the protective role of adipocyte APOM against obesity-induced AT inflammation.

Emerging Roles for Sphingolipids in Cardiometabolic Disease: A Rational Therapeutic Target?

Cardiovascular disease is a leading cause of morbidity and mortality. New research elucidates increasingly complex relationships between cardiac and metabolic health, giving rise to new possible therapeutic targets. Sphingolipids are a heterogeneous class of bioactive lipids with critical roles in normal human physiology. They have also been shown to play both protective and deleterious roles in the pathogenesis of cardiovascular disease. Ceramides are implicated in dysregulating insulin signalling, vascular endothelial function, inflammation, oxidative stress, and lipoprotein aggregation, thereby promoting atherosclerosis and vascular disease. Ceramides also advance myocardial disease by enhancing pathological cardiac remodelling and cardiomyocyte death. Glucosylceramides similarly contribute to insulin resistance and vascular inflammation, thus playing a role in atherogenesis and cardiometabolic dysfunction. Sphingosing-1-phosphate, on the other hand, may ameliorate some of the pathological functions of ceramide by protecting endothelial barrier integrity and promoting cell survival. Sphingosine-1-phosphate is, however, implicated in the development of cardiac fibrosis. This review will explore the roles of sphingolipids in vascular, cardiac, and metabolic pathologies and will evaluate the therapeutic potential in targeting sphingolipids with the aim of prevention and reversal of cardiovascular disease in order to improve long-term cardiovascular outcomes.

Sphingosine 1-phosphate receptor 2 in keratinocytes plays a key role in reducing inflammation in psoriasis

Background

Psoriasis is an inflammatory skin condition where immune cells play a significant role. The importance of the cross-talk between keratinocytes and immune cells in the pathogenesis of psoriasis has recently been reaffirmed. Recent studies have found that several S1PR functional antagonists, other than S1PR2, are effective in improving psoriasis. This study aims to investigate the role of S1PR2 in psoriasis, that has not been investigated before.

Methods

Spatial transcriptomics, RT-qPCR, and flow cytometry were used to map the immune cell landscape and its association with metabolic pathways in an imiquimod (IMQ)-induced psoriasis-like inflammation in S1pr2fl/fl K14-Cre mice that could not sense sphingosine-1-phosphate (S1P) in the epidermis through the S1PR2 receptor.

Results

Our analysis suggests that S1PR2 in keratinocytes plays a major role in psoriasis-like inflammation compared to other S1PRs. It acts as a down-regulator, inhibiting the recruitment of Th17 cells into the skin. In IMQ-induced psoriasis skin, both S1pr2-/- and S1pr2fl/fl K14-Cre mice showed higher expressions of proinflammatory cytokines such as TNF-α, IL-17A, and IL-1β together with higher expressions of MyD88/NF-κB pathway compared to the wild-type mice. Remarkably, in IMQ-treated mice, the deletion of S1pr2 in keratinocytes only resulted in a larger population of Th17 cells in skin-draining lymph nodes. Other S1PR modulators did not improve the worsening of psoriasis-like inflammation caused by S1PR2 deficiency in keratinocytes.

Conclusion

This study reaches two main conclusions: signals from keratinocytes play a central role in creating an immune environment that promotes the development of psoriasis, and stimulating S1PR2, instead of suppressing it, represents a potential therapeutic approach for psoriasis.

An overview of sphingosine-1-phosphate receptor 2: Structure, biological function, and small-molecule modulators

Over the past decade, there has been a notable increase in research on sphingosine-1-phosphate receptor 2 (S1PR2), which is a type of G-protein-coupled receptor. Upon activation by S1P or other ligands, S1PR2 initiates downstream signaling pathways such as phosphoinositide 3-kinase (PI3K), Mitogen-activated protein kinase (MAPK), Rho/Rho-associated coiled-coil containing kinases (ROCK), and others, contributing to the diverse biological functions of S1PR2 and playing a pivotal role in various physiological processes and disease progressions, such as multiple sclerosis, fibrosis, inflammation, and tumors. Due to the extensive biological functions of S1PR2, many S1PR2 modulators, including agonists and antagonists, have been developed and discovered by pharmaceutical companies (e.g., Novartis and Galapagos NV) and academic medicinal chemists for disease diagnosis and treatment. However, few reviews have been published that comprehensively overview the functions and regulators of S1PR2. Herein, we provide an in-depth review of the advances in the function of S1PR2 and its modulators. We first summarize the structure and biological function of S1PR2 and its pathological role in human diseases. We then focus on the discovery approach, design strategy, development process, and biomedical application of S1PR2 modulators. Additionally, we outline the major challenges and future directions in this field. Our comprehensive review will aid in the discovery and development of more effective and clinically applicable S1PR2 modulators.

Serum metabolomics analysis of patients with chronic obstructive pulmonary disease and 'frequent exacerbator' phenotype

Chronic obstructive pulmonary disease (COPD) exacerbations accelerate loss of lung function and increased mortality. The complex nature of COPD presents challenges in accurately predicting and understanding frequent exacerbations. The present study aimed to assess the metabolic characteristics of the frequent exacerbation of COPD (COPD‑FE) phenotype, identify potential metabolic biomarkers associated with COPD‑FE risk and evaluate the underlying pathogenic mechanisms. An internal cohort of 30 stable patients with COPD was recruited. A widely targeted metabolomics approach was used to detect and compare serum metabolite expression profiles between patients with COPD‑FE and patients with non‑frequent exacerbation of COPD (COPD‑NE). Bioinformatics analysis was used for pathway enrichment analysis of the identified metabolites. Spearman's correlation analysis assessed the associations between metabolites and clinical indicators, while receiver operating characteristic (ROC) analysis evaluated the ability of metabolites to distinguish between two groups. An external cohort of 20 patients with COPD validated findings from the internal cohort. Out of the 484 detected metabolites, 25 exhibited significant differences between COPD‑FE and COPD‑NE. Metabolomic analysis revealed differences in lipid, energy, amino acid and immunity pathways. Spearman's correlation analysis demonstrated associations between metabolites and clinical indicators of acute exacerbation risk. ROC analysis demonstrated that the area under the curve (AUC) values for D‑fructose 1,6‑bisphosphate (AUC=0.871), arginine (AUC=0.836), L‑2‑hydroxyglutarate (L‑2HG; AUC=0.849), diacylglycerol (DG) (16:0/20:5) (AUC=0.827), DG (16:0/20:4) (AUC=0.818) and carnitine‑C18:2 (AUC=0.804) were >0.8, highlighting their discriminative capacity between the two groups. External validation results demonstrated that DG (16:0/20:5), DG (16:0/20:4), carnitine‑C18:2 and L‑2HG were significantly different between patients with COPD‑FE and those with COPD‑NE. In conclusion, the present study offers insights into early identification, mechanistic understanding and personalized management of the COPD‑FE phenotype.

New and emerging oral therapies for psoriasis

Psoriasis is a chronic inflammatory skin disease affecting 2-3% of the global population. Traditional systemic treatments, such as methotrexate, cyclosporine, acitretin and fumaric acid esters, have limited efficacy and are associated with significant adverse effects, necessitating regular monitoring and posing risks of long-term toxicity. Recent advancements have introduced biologic drugs that offer improved efficacy and safety profiles. However, their high cost and the inconvenience of parenteral administration limit their accessibility. Consequently, there is a growing interest in developing new, targeted oral therapies. Small molecules, such as phosphodiesterase 4 inhibitors (e.g. apremilast) and TYK2 inhibitor (e.g. deucravacitinib), have shown promising results with favourable safety profiles. Additionally, other novel oral agents targeting specific pathways, including IL-17, IL-23, TNF, S1PR1 and A3AR, are under investigation. These treatments aim to combine the efficacy of biologics with the convenience and accessibility of oral administration, addressing the limitations of current therapies. This narrative review synthesizes the emerging oral therapeutic agents for psoriasis, focusing on their mechanisms of action, stages of development and clinical trial results.

New markers in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD), a global healthcare and socioeconomic burden, is a multifaceted respiratory disorder that results in substantial decline in health status and life quality. Acute exacerbations of the disease contribute significantly to increased morbidity and mortality. Consequently, the identification of reliable and effective biomarkers for rapid diagnosis, prediction, and prognosis of exacerbations is imperative. In addition, biomarkers play a crucial role in monitoring responses to therapeutic interventions and exploring innovative treatment strategies. Although established markers such as CRP, fibrinogen and neutrophil count are routinely used, a universal marker is lacking. Fortunately, an increasing number of studies based on next generation analytics have explored potential biomarkers in COPD. Here we review those advances and the need for standardized validation studies in the appropriate clinical setting.

Myeloid Cells and Sphingosine-1-Phosphate Are Required for TCRαβ Intraepithelial Lymphocyte Recruitment to the Colon Epithelium

Intraepithelial lymphocytes (IELs) are T cells important for the maintenance of barrier integrity in the intestine. Colon IELs are significantly reduced in both MyD88-deficient mice and those lacking an intact microbiota, suggesting that MyD88-mediated detection of bacterial products is important for the recruitment and/or retention of these cells. Here, using conditionally deficient MyD88 mice, we show that myeloid cells are the key mediators of TCRαβ+ IEL recruitment to the colon. Upon exposure to luminal bacteria, myeloid cells produce sphingosine-1-phosphate (S1P) in a MyD88-dependent fashion. TCRαβ+ IEL recruitment may be blocked using the S1P receptor antagonist FTY720, confirming the importance of S1P in the recruitment of TCRαβ+ IELs to the colon epithelium. Finally, using the TNFΔARE/+ model of Crohn's-like bowel inflammation, we show that disruption of colon IEL recruitment through myeloid-specific MyD88 deficiency results in reduced pathology. Our results illustrate one mechanism for recruitment of a subset of IELs to the colon.

PET Imaging of Sphingosine-1-Phosphate Receptor 1 with [18F]TZ4877 in Nonhuman Primates

Purpose

The sphingosine-1-phosphate receptor-1 (S1PR1) is involved in regulating responses to neuroimmune stimuli. There is a need for S1PR1-specific radioligands with clinically suitable brain pharmcokinetic properties to complement existing radiotracers. This work evaluated a promising S1PR1 radiotracer, [18F]TZ4877, in nonhuman primates.

Procedures

[18F]TZ4877 was produced via nucleophilic substitution of tosylate precursor with K[18F]/F- followed by deprotection. Brain PET imaging data were acquired with a Focus220 scanner in two Macaca mulatta (6, 13 years old) for 120-180 min following bolus injection of 118-163 MBq [18F]TZ4877, with arterial blood sampling and metabolite analysis to measure the parent input function and plasma free fraction (f P). Each animal was scanned at baseline, 15-18 min after 0.047-0.063 mg/kg of the S1PR1 inhibitor ponesimod, 33 min after 0.4-0.8 mg/kg of the S1PR1-specific compound TZ82112, and 167-195 min after 1 ng/kg of the immune stimulus endotoxin. Kinetic analysis with metabolite-corrected input function was performed to estimate the free fraction corrected total distribution volume (V T/f P). Whole-body dosimetry scans were acquired in 2 animals (1M, 1F) with a Biograph Vision PET/CT System, and absorbed radiation dose estimates were calculated with OLINDA.

Results

[18F]TZ4877 exhibited fast kinetics that were described by the reversible 2-tissue compartment model. Baseline [18F]TZ4877 f P was low (< 1%), and [18F]TZ4877 V T/f P values were 233-866 mL/cm3. TZ82112 dose-dependently reduced [18F]TZ4877 V T/f P, while ponesimod and endotoxin exhibited negligible effects on V T/f P, possibly due to scan timing relative to dosing. Dosimetry studies identified the critical organs of gallbladder (0.42 (M) and 0.31 (F) mSv/MBq) for anesthetized nonhuman primate.

Conclusions

[18F]TZ4877 exhibits reversible kinetic properties, but the low f P value limits quantification with this radiotracer. S1PR1 is a compelling PET imaging target, and these data support pursuing alternative F-18 labeled radiotracers for potential future human studies.

Multilineage-differentiating stress-enduring cells: a powerful tool for tissue damage repair

Multilineage-differentiating stress-enduring (Muse) cells are a type of pluripotent cell with unique characteristics such as non-tumorigenic and pluripotent differentiation ability. After homing, Muse cells spontaneously differentiate into tissue component cells and supplement damaged/lost cells to participate in tissue repair. Importantly, Muse cells can survive in injured tissue for an extended period, stabilizing and promoting tissue repair. In addition, it has been confirmed that injection of exogenous Muse cells exerts anti-inflammatory, anti-apoptosis, anti-fibrosis, immunomodulatory, and paracrine protective effects in vivo. The discovery of Muse cells is an important breakthrough in the field of regenerative medicine. The article provides a comprehensive review of the characteristics, sources, and potential mechanisms of Muse cells for tissue repair and regeneration. This review serves as a foundation for the further utilization of Muse cells as a key clinical tool in regenerative medicine.

METTL5 promotes gastric cancer progression via sphingomyelin metabolism

BACKGROUND

The treatment of gastric cancer (GC) has caused an enormous social burden worldwide. Accumulating studies have reported that N6-methyladenosine (m6A) is closely related to tumor progression. METTL5 is a m6A methyltransferase that plays a pivotal role in maintaining the metabolic stability of cells. However, its aberrant regulation in GC has not been fully elucidated.

AIM

To excavate the role of METTL5 in the development of GC.

METHODS

METTL5 expression and clinicopathological characteristics were analyzed via The Cancer Genome Atlas dataset and further verified via immunohistochemistry, western blotting and real-time quantitative polymerase chain reaction in tissue microarrays and clinical samples. The tumor-promoting effect of METTL5 on HGC-27 and AGS cells was explored in vitro by Cell Counting Kit-8 assays, colony formation assays, scratch healing assays, transwell assays and flow cytometry. The tumor-promoting role of METTL5 in vivo was evaluated in a xenograft tumor model. The EpiQuik m6A RNA Methylation Quantification Kit was used for m6A quantification. Next, liquid chromatography-mass spectrometry was used to evaluate the association between METTL5 and sphingomyelin metabolism, which was confirmed by Enzyme-linked immunosorbent assay and rescue tests. In addition, we investigated whether METTL5 affects the sensitivity of GC cells to cisplatin via colony formation and transwell experiments.

RESULTS

Our research revealed substantial upregulation of METTL5, which suggested a poor prognosis of GC patients. Increased METTL5 expression indicated distant lymph node metastasis, advanced cancer stage and pathological grade. An increased level of METTL5 correlated with a high degree of m6A methylation. METTL5 markedly promotes the proliferation, migration, and invasion of GC cells in vitro. METTL5 also promotes the growth of GC in animal models. METTL5 knockdown resulted in significant changes in sphingomyelin metabolism, which implies that METTL5 may impact the development of GC via sphingomyelin metabolism. In addition, high METTL5 expression led to cisplatin resistance.

CONCLUSION

METTL5 was found to be an oncogenic driver of GC and may be a new target for therapy since it facilitates GC carcinogenesis through sphingomyelin metabolism and cisplatin resistance.

Signaling controversy and future therapeutical perspectives of targeting sphingolipid network in cancer immune editing and resistance to tumor necrosis factor-α immunotherapy

Anticancer immune surveillance and immunotherapies trigger activation of cytotoxic cytokine signaling, including tumor necrosis factor-α (TNF-α) and TNF-related apoptosis-inducing ligand (TRAIL) pathways. The pro-inflammatory cytokine TNF-α may be secreted by stromal cells, tumor-associated macrophages, and by cancer cells, indicating a prominent role in the tumor microenvironment (TME). However, tumors manage to adapt, escape immune surveillance, and ultimately develop resistance to the cytotoxic effects of TNF-α. The mechanisms by which cancer cells evade host immunity is a central topic of current cancer research. Resistance to TNF-α is mediated by diverse molecular mechanisms, such as mutation or downregulation of TNF/TRAIL receptors, as well as activation of anti-apoptotic enzymes and transcription factors. TNF-α signaling is also mediated by sphingosine kinases (SphK1 and SphK2), which are responsible for synthesis of the growth-stimulating phospholipid, sphingosine-1-phosphate (S1P). Multiple studies have demonstrated the crucial role of S1P and its transmembrane receptors (S1PR) in both the regulation of inflammatory responses and progression of cancer. Considering that the SphK/S1P/S1PR axis mediates cancer resistance, this sphingolipid signaling pathway is of mechanistic significance when considering immunotherapy-resistant malignancies. However, the exact mechanism by which sphingolipids contribute to the evasion of immune surveillance and abrogation of TNF-α-induced apoptosis remains largely unclear. This study reviews mechanisms of TNF-α-resistance in cancer cells, with emphasis on the pro-survival and immunomodulatory effects of sphingolipids. Inhibition of SphK/S1P-linked pro-survival branch may facilitate reactivation of the pro-apoptotic TNF superfamily effects, although the role of SphK/S1P inhibitors in the regulation of the TME and lymphocyte trafficking should be thoroughly assessed in future studies.

Expression of sphingosine-1-phosphate receptor 1 in neuroinflammation of canine brains

Sphingosine-1-phosphate (S1P) is a signaling lipid mediator that is involved in multiple biological processes. The S1P/S1P receptor (S1PR) signaling pathway has an important role in the central nervous system. It contributes to physiologic cellular homeostasis and is also associated with neuroinflammation. Therefore, this study was performed to evaluate the expression of S1PR in dogs with meningoencephalitis of unknown etiology (MUE) and experimental autoimmune encephalomyelitis (EAE). The analysis used 12 brain samples from three neurologically normal dogs, seven dogs with MUE, and two canine EAE models. Anti-S1PR1 antibody was used for immunohistochemistry. In normal brain tissues, S1PR1s were expressed on neurons, astrocytes, oligodendrocytes, and endothelial cells. In MUE and EAE lesions, there was positive staining of S1PR1 on leukocytes. Furthermore, the expression of S1PR1 on neurons, astrocytes, oligodendrocytes, and endothelial cells was upregulated compared to normal brains. This study shows that S1PR1s are expressed in normal brain tissues and leukocytes in inflammatory lesions, and demonstrates the upregulation of S1PR1 expression on nervous system cells in inflammatory lesions of MUE and EAE. These findings indicate that S1P/S1PR signaling pathway might involve physiologic homeostasis and neuroinflammation and represent potential targets for S1PR modulators to treat MUE.

SMPDL3B is palmitoylated and stabilized by ZDHHC5, and its silencing aggravates diabetic retinopathy of db/db mice: Activation of NLRP3/NF-κB pathway

Abnormal inflammation of vascular endothelial cells occurs frequently in diabetic retinopathy (DR). Sphingomyelin phosphodiesterase acid-like 3B (SMPDL3B) is a lipid raft enzyme and plays an anti-inflammatory role in various diseases but its function in DR-related vascular endothelial dysfunction remains unknown. We first found that SMPDL3B expression was upregulated from week 10 to 18 in the retinal tissues of db/db mice. Particularly, the high expression of SMPDL3B was mainly observed in retinal vascular endothelium of DR mice. To interfere retinal SMPDL3B expression, adeno-associated viruses 2 (AAV-2) containing SMPDL3B specific shRNA (1233-1253 bp) were injected into the vitreous cavity of db/db mice. SMPDL3B silencing exacerbated the spontaneous DR by further activating the NF-κB/NLRP3 pro-inflammatory pathway. In vitro, human retinal microvascular endothelial cells (HRVECs) were infected with SMPDL3B-shRNA lentiviruses and then stimulated with 30 mM glucose (HG) for 24 h. SMPDL3B-silenced HRVECs secreted more interleukin-1β and had enhanced nuclear p65 translocation. Notably, HG treatment induced the palmitoylation of SMPDL3B. Zinc finger DHHC-type palmitoyltransferase 5 (ZDHHC5) is a palmitoyltransferase that catalyzes the palmitoylation of its substrates, HG exposure increased the interaction between ZDHHC5 and SMPDL3B in HRVECs. 2-BP, a palmitoylation inhibitor, accelerated the protein degradation of SMPDL3B, whereas palmostatin B, a depalmitoylation inhibitor, decreased its turnover rate in HRVECs. Collectively, the present study suggests a compensatory increase of SMPDL3B in HG-treated HRVECs and the retinal tissues of DR mice, indicating that SMPDL3B may be a potential target for DR treatment.

Exploring Skin Wound Healing Models and the Impact of Natural Lipids on the Healing Process

Cutaneous wound healing is a complex biological process involving a series of well-coordinated events aimed at restoring skin integrity and function. Various experimental models have been developed to study the mechanisms underlying skin wound repair and to evaluate potential therapeutic interventions. This review explores the diverse array of skin wound healing models utilized in research, ranging from rodent excisional wounds to advanced tissue engineering constructs and microfluidic platforms. More importantly, the influence of lipids on the wound healing process is examined, emphasizing their role in enhancing barrier function restoration, modulating inflammation, promoting cell proliferation, and promoting remodeling. Lipids, such as phospholipids, sphingolipids, and ceramides, play crucial roles in membrane structure, cell signaling, and tissue repair. Understanding the interplay between lipids and the wound microenvironment provides valuable insights into the development of novel therapeutic strategies for promoting efficient wound healing and tissue regeneration. This review highlights the significance of investigating skin wound healing models and elucidating the intricate involvement of lipids in the healing process, offering potential avenues for improving clinical outcomes in wound management.

Targeting Sphingosine-1-Phosphate Signaling in Breast Cancer

In recent years, newly emerging therapies, such as immune checkpoint inhibitors and antibody-drug conjugates, have further improved outcomes for breast cancer patients. However, recurrent and metastatic breast cancer often eventually develops resistance to these drugs, and cure is still rare. As such, the development of new therapies for refractory breast cancer that differ from conventional mechanisms of action is necessary. Sphingosine-1-phosphate (S1P) is a key molecule with a variety of bioactive activities, including involvement in cancer cell proliferation, invasion, and metastasis. S1P also contributes to the formation of the cancer microenvironment by inducing surrounding vascular- and lymph-angiogenesis and regulating the immune system. In this article, we outline the basic mechanism of action of S1P, summarize previous findings on the function of S1P in cancer cells and the cancer microenvironment, and discuss the clinical significance of S1P in breast cancer and the therapeutic potential of targeting S1P signaling.

How do sphingosine-1-phosphate affect immune cells to resolve inflammation?

Inflammation is an important immune response of the body. It is a physiological process of self-repair and defense against pathogens taken up by biological tissues when stimulated by damage factors such as trauma and infection. Inflammation is the main cause of high morbidity and mortality in most diseases and is the physiological basis of the disease. Targeted therapeutic strategies can achieve efficient toxicity clearance at the inflammatory site, reduce complications, and reduce mortality. Sphingosine-1-phosphate (S1P), a lipid signaling molecule, is involved in immune cell transport by binding to S1P receptors (S1PRs). It plays a key role in innate and adaptive immune responses and is closely related to inflammation. In homeostasis, lymphocytes follow an S1P concentration gradient from the tissues into circulation. One widely accepted mechanism is that during the inflammatory immune response, the S1P gradient is altered, and lymphocytes are blocked from entering the circulation and are, therefore, unable to reach the inflammatory site. However, the full mechanism of its involvement in inflammation is not fully understood. This review focuses on bacterial and viral infections, autoimmune diseases, and immunological aspects of the Sphks/S1P/S1PRs signaling pathway, highlighting their role in promoting intradial-adaptive immune interactions. How S1P signaling is regulated in inflammation and how S1P shapes immune responses through immune cells are explained in detail. We teased apart the immune cell composition of S1P signaling and the critical role of S1P pathway modulators in the host inflammatory immune system. By understanding the role of S1P in the pathogenesis of inflammatory diseases, we linked the genomic studies of S1P-targeted drugs in inflammatory diseases to provide a basis for targeted drug development.

Expression levels of GSDMB and ORMDL3 are associated with relapsing-remitting multiple sclerosis and IKZF3 rs12946510 variant

Multiple sclerosis (MS), a noncurable autoimmune neurodegenerative disease, requires constant research that could improve understanding of both environmental and genetic factors that lead to its occurrence and/or progression. Recognition of the genetic basis of MS further leads to an investigation of the regulatory role of genetic variants on gene expression. Among risk variants for MS, Ikaros zinc finger 3 (IKZF3) gene variant rs12946510 was identified as one of the top-ranked and the expression quantitative trait loci (eQTL) for genes residing in chromosomal locus 17q12-21. The study aimed to investigate the association of gene expression of the immunologically relevant genes, which map to indicated locus, ORMDL3, GSDMB, and IKZF3, with MS and rs12946510 genotype, taking into account disease phase, clinical parameters of disease progression, and severity and immunomodulatory therapy. We used TaqMan® technology for both allelic discrimination and gene expression determination in 67 relapsing MS patients and 50 healthy controls. Decreased ORMDL3 and GSDMB mRNA levels had significant associations with MS and rs12946510 TT rare homozygote among patients. Significant positive correlations between ORMDL3 and GSDMB mRNA expression were observed in both patients and controls. We detected the significant between-effect of sex and rs12946510 on the expression of ORMDL3 in the patient group and interferon β therapy and rs12946510 on GSDMB expression. Our results show the association of ORMDL3 and GSDMB mRNA expression with the clinical manifestation of MS and confirm that IKZF3 rs12946510 exerts the eQTL effect on both genes in multiple sclerosis. Besides providing novel insight related to MS phases and interferon β therapy, the study results confirm previous studies on regulatory genetic variants, autoimmunity, and MS.

New and Emerging Oral/Topical Small-Molecule Treatments for Psoriasis

The introduction of biologic therapies has led to dramatic improvements in the management of moderate-to-severe psoriasis. Even though the efficacy and safety of the newer biologic agents are difficult to match, oral administration is considered an important advantage by many patients. Current research is focused on the development of oral therapies with improved efficacy and safety compared with available alternatives, as exemplified by deucravacitinib, the first oral allosteric Tyk2 inhibitor approved for the treatment of moderate to severe psoriasis in adults. Recent advances in our knowledge of psoriasis pathogenesis have also led to the development of targeted topical molecules, mostly focused on intracellular signaling pathways such as AhR, PDE-4, and Jak-STAT. Tapinarof (an AhR modulator) and roflumilast (a PDE-4 inhibitor) have exhibited favorable efficacy and safety outcomes and have been approved by the FDA for the topical treatment of plaque psoriasis. This revision focuses on the most recent oral and topical therapies available for psoriasis, especially those that are currently under evaluation and development for the treatment of psoriasis.

Metabolism, fibrosis, and apoptosis: The effect of lipids and their derivatives on keloid formation

Keloids, pathological scars resulting from skin trauma, have traditionally posed significant clinical management challenges due to their persistence and high recurrence rates. Our research elucidates the pivotal roles of lipids and their derivatives in keloid development, driven by underlying mechanisms of abnormal cell proliferation, apoptosis, and extracellular matrix deposition. Key findings suggest that abnormalities in arachidonic acid (AA) synthesis and non-essential fatty acid synthesis are integral to keloid formation. Further, a complex interplay exists between lipid derivatives, notably butyric acid (BA), prostaglandin E2 (PGE2), prostaglandin D2 (PGD2), and the regulation of hyperfibrosis. Additionally, combinations of docosahexaenoic acid (DHA) with BA and 15-deoxy-Δ12,14-Prostaglandin J2 have exhibited pronounced cytotoxic effects. Among sphingolipids, ceramide (Cer) displayed limited pro-apoptotic effects in keloid fibroblasts (KFBs), whereas sphingosine 1-phosphate (S1P) was found to promote keloid hyperfibrosis, with its analogue, FTY720, demonstrating contrasting benefits. Both Vitamin D and hexadecylphosphorylcholine (HePC) showed potential antifibrotic and antiproliferative properties, suggesting their utility in keloid management. While keloids remain a prevalent concern in clinical practice, this study underscores the promising potential of targeting specific lipid molecules for the advancement of keloid therapeutic strategies.

Specialized Retinal Endothelial Cells Modulate Blood-Retina Barrier in Diabetic Retinopathy

Endothelial cells (EC) play essential roles in retinal vascular homeostasis. This study aimed to characterize retinal EC heterogeneity and functional diversity using single-cell RNA sequencing. Systematic analysis of cellular compositions and cell-cell interaction networks identified a unique EC cluster with high inflammatory gene expression in diabetic retina; sphingolipid metabolism is a prominent aspect correlated with changes in retinal function. Among sphingolipid-related genes, alkaline ceramidase 2 (ACER2) showed the most significant increase. Plasma samples of patients with nonproliferative diabetic retinopathy (NPDR) with diabetic macular edema (DME) or without DME (NDME) and active proliferative DR (PDR) were collected for mass spectrometry analysis. Metabolomic profiling revealed that the ceramide levels were significantly elevated in NPDR-NDME/DME and further increased in active PDR compared with control patients. In vitro analyses showed that ACER2 overexpression retarded endothelial barrier breakdown induced by ceramide, while silencing of ACER2 further disrupted the injury. Moreover, intravitreal injection of the recombinant ACER2 adeno-associated virus rescued diabetes-induced vessel leakiness, inflammatory response, and neurovascular disease in diabetic mouse models. Together, this study revealed a new diabetes-specific retinal EC population and a negative feedback regulation pathway that reduces ceramide content and endothelial dysfunction by upregulating ACER2 expression. These findings provide insights into cell-type targeted interventions for diabetic retinopathy.

ARTICLE HIGHLIGHTS

MicroRNA-10a enrichment in factor VIIa-released endothelial extracellular vesicles: potential mechanisms

BACKGROUND

Factor VIIa induces the release of extracellular vesicles (EVs) from endothelial cells (EEVs). Factor VIIa-released EEVs are enriched with microRNA-10a (miR10a) and elicit miR10a-dependent cytoprotective responses.

OBJECTIVES

To investigate mechanisms by which FVIIa induces miR10a expression in endothelial cells and sorts miR10a into the EVs.

METHODS

Activation of Elk-1 and TWIST1 expression was analyzed by immunofluorescence microscopy and immunoblot analysis. Small interfering RNA silencing approach was used to knock down the expression of specific genes in endothelial cells. EVs secreted from endothelial cells or released into circulation in mice were isolated by centrifugation and quantified by nanoparticle tracking analysis. Factor VIIa or EVs were injected into mice; mice were challenged with lipopolysaccharides to assess the cytoprotective effects of FVIIa or EVs.

RESULTS

FVIIa activation of ERK1/2 triggered the activation of Elk-1, which led to the induction of TWIST1, a key transcription factor involved in miR10a expression. Factor VIIa also induced the expression of La, a small RNA-binding protein. Factor VIIa-driven acid sphingomyelinase (ASM) activation and the subsequent activation of the S1P receptor pathway were responsible for the induction of La. Silencing of ASM or La significantly reduced miR10a levels in FVIIa-released EEVs without affecting the cellular expression of miR10a. Factor VIIa-EEVs from ASM knocked-down cells failed to provide cytoprotective responses in cell and murine model systems. Administration of FVIIa protected wild-type but not ASM-/- mice against lipopolysaccharide-induced inflammation and vascular leakage.

CONCLUSION

Our data suggest that enhanced cellular expression of miR10a coupled with La-dependent sorting of miR10a is responsible for enriching FVIIa-released EVs with miR10a.

Sphingosine 1-Phosphate Regulates Obesity and Glucose Homeostasis

One of the major global health and welfare issues is the treatment of obesity and associated metabolic disorders, such as type 2 diabetes mellitus and nonalcoholic fatty liver disease. Obesity, caused by the excessive accumulation of triglycerides in adipose tissues, induces adipocyte dysfunction, followed by inflammation, in adipose tissues and lipotoxicity in nonadipose tissues. Several studies have shown that obesity and glucose homeostasis are influenced by sphingolipid mediators, including ceramide and sphingosine 1-phosphate (S1P). Cellular accumulation of ceramide impairs pancreatic β-cell survival, confers insulin resistance in the liver and the skeletal muscle, and deteriorates adipose tissue inflammation via unknown molecular mechanisms. The roles of S1P are more complicated, because there are five cell-surface S1P receptors (S1PRs: S1P1-5) which have altered functions, different cellular expression patterns, and inapparent intracellular targets. Recent findings, including those by our group, support the notable concept that the pharmacological activation of S1P1 or S1P3 improves obesity and associated metabolic disorders, whereas that of S1P2 has the opposite effect. In addition, the regulation of S1P production by sphingosine kinase (SphK) is an essential factor affecting glucose homeostasis. This review summarizes the current knowledge on SphK/S1P/S1PR signaling in and against obesity, insulin resistance, and associated disorders.

CD69 is a Promising Immunotherapy and Prognosis Prediction Target in Cancer

Immunotherapy utilizing T cells that attack tumors is a promising strategy for treatment, but immune suppressive T cell subsets, such as regulatory T cell (Treg), and immune checkpoint molecules, including programmed death-1 (PD-1), can suppress the intensity of a T cell immune reaction and thereby impair tumor clearance. Cluster of differentiation 69 (CD69), known as an early leukocyte activation marker, can be used as a measure or early marker of T cell activation. In recent years, the functions of CD69 in the regulation of Treg/Th17 (T helper cell 17) differentiation and in the tissue retention of T cells have attracted considerable interest. These functions are related to the role of CD69 in immune suppression in tumor environments (TME). In this review, we first summarized current perspectives in the biological function of CD69 and demonstrated that CD69 acts as a regulator of T cell activation, differentiation, retention, and exhaustion. Then, we discussed recent advances in understanding of CD69 deficiency and anti-CD69 antibody administration and shed light on the value of targeting on CD69 for cancer immunotherapy and prognosis prediction.