Sphingolipids in metabolic disease: The good, the bad, and the unknown

OASL activates MAPK to drive psoriatic pathogenesis: Astilbin targeting this axis improves metabolic-inflammation crosstalk

AIMS

This study aimed to elucidate the role of oligoadenylate synthase-like protein (OASL) as a pivotal regulator integrating keratinocyte hyperproliferation, inflammation, and lipid metabolic dysregulation in psoriasis pathogenesis.

MATERIALS AND METHODS

Clinical analyses compared epidermal OASL expression levels between psoriasis patients and healthy individuals. Functional studies in HaCaT cells employed OASL knockdown and overexpression to assess effects on proliferation, inflammatory responses, and lipid metabolism. The JAK1-STAT1-OASL regulatory axis was investigated using the JAK1 inhibitor Upadacitinib. The natural flavonoid Astilbin was screened as an OASL inhibitor, and its therapeutic efficacy was evaluated in imiquimod-induced psoriatic mice.

KEY FINDINGS

OASL was significantly upregulated in psoriatic epidermis. Knockdown of OASL suppressed keratinocyte proliferation and inflammation, while its overexpression promoted hyperproliferation, inflammation, and lipid metabolic dysregulation via p38 MAPK pathway activation. Mechanistically, Upadacitinib reduced OASL expression by inhibiting STAT1, confirming the JAK1-STAT1-OASL axis. Astilbin markedly alleviated imiquimod-induced psoriasiform dermatitis in mice.

SIGNIFICANCE

This study reveals OASL's pivotal regulatory role in psoriasis and its associated pathways, providing novel therapeutic targets and a potential natural drug candidate. These findings establish a theoretical foundation for developing multi-targeted strategies against psoriasis.

Spatial lipidomics reveals sphingolipid metabolism as anti-fibrotic target in the liver

BACKGROUND AND AIMS

Steatotic liver disease (SLD), which encompasses various causes of fat accumulation in the liver, is a major cause of liver fibrosis. Understanding the specific mechanisms of lipotoxicity, dysregulated lipid metabolism, and the role of different hepatic cell types involved in fibrogenesis is crucial for therapy development.

METHODS

We analysed liver tissue from SLD patients and 3 mouse models. We combined bulk/spatial lipidomics, transcriptomics, imaging mass cytometry (IMC) and analysis of published spatial and single-cell RNA sequencing (scRNA-seq) data to explore the metabolic microenvironment in fibrosis. Pharmacological inhibition of sphingolipid metabolism with myriocin, fumonisin B1, miglustat and D-PDMP was carried out in hepatic stellate cells (HSCs) and human precision cut liver slices (hPCLSs).

RESULTS

Bulk lipidomics revealed increased glycosphingolipids, ether lipids and saturated phosphatidylcholines in fibrotic samples. Spatial lipidomics detected >40 lipid species enriched within fibrotic regions, notably sphingomyelin (SM) 34:1. Using bulk transcriptomics (mouse) and analysis of published spatial transcriptomics data (human) we found that sphingolipid metabolism was also dysregulated in fibrosis at transcriptome level, with increased gene expression for ceramide and glycosphingolipid synthesis. Analysis of human scRNA-seq data showed that sphingolipid-related genes were widely expressed in non-parenchymal cells. By integrating spatial lipidomics with IMC of hepatic cell markers, we found excellent spatial correlation between sphingolipids, such as SM(34:1), and myofibroblasts. Inhibiting sphingolipid metabolism resulted in anti-fibrotic effects in HSCs and hPCLSs.

CONCLUSIONS

Our spatial multi-omics approach suggests cell type-specific mechanisms of fibrogenesis involving sphingolipid metabolism. Importantly, sphingolipid metabolic pathways are modifiable targets, which may have potential as an anti-fibrotic therapeutic strategy.

Roles of HDL function and sphingosine-1-phosphate in vasospastic angina

BACKGROUND

High-density lipoprotein cholesterol (HDL-C) levels are often reduced in patients with vasospastic angina (VSA), but the relevance of HDL functionality to VSA pathogenesis remains unclear. Cholesterol uptake capacity (CUC), a novel cell-free assay reflecting HDL-mediated cholesterol efflux, offers a practical measure of HDL functionality. In parallel, sphingosine-1-phosphate (S1P), an HDL-associated bioactive sphingolipid with vasoprotective properties, may also contribute to VSA. This study aimed to evaluate CUC and vasodilatory HDL components, including S1P, in patients with VSA.

METHODS AND RESULTS

Seventy-seven patients, comprising 53 patients who underwent an acetylcholine (Ach) provocation test (32 VSA at diagnosis and 21 non-VSA) and an additional 24 VSA outpatients were included. Patients with VSA had higher triglyceride levels compared with non-VSA patients, but HDL-C levels were not different. Further analysis revealed that CUC was lower in VSA patients at diagnosis compared with non-VSA patients. Serum levels of sphingosine-1-phosphate (S1P), a sphingolipid associated with HDL, were elevated in the VSA group (1.74 ± 0.76 vs. 1.31 ± 0.49 µM; p < 0.01). In the VSA outpatient and Non-VSA groups, S1P levels in crude analysis were significantly associated with VSA (OR = 3.14, 95 % CI: 1.25-7.88, p = 0.01). This association remained significant across all adjusted models (Models 1-4).

CONCLUSIONS

The present study found that CUC was a novel indicator of vasospasm-related HDL dysfunctionality and that S1P is a promising biomarker for treated patients with VSA. The cholesterol efflux pathway and sphingolipid metabolism could contribute to the etiology of vasospasm.

STUDY REGISTRATION

This clinical study was registered with the University Hospital Medical Information Network Clinical Trials Registry (UMIN000020942).

A meta-analysis of genome-wide association studies revealed significant QTL and candidate genes for loin muscle area in three breeding pigs

Loin muscle area (LMA) is an important production trait in pigs and is highly correlated with lean meat percentage. However, the genetic architecture of LMA has not yet been fully elucidated. This study conducted genome-wide association studies (GWAS) and meta-analyses of LMA in Duroc (n = 337), Landrace (n = 662), and Yorkshire pigs (n = 3,176) using imputed whole-genome sequencing to identify new QTLs and candidate genes associated with LMA traits. A total of 108, 34, and 232 significant variants were identified in the Duroc, Landrace, and Yorkshire populations, respectively. The meta-analysis revealed 143 genome-wide significant SNPs and 276 suggestive SNPs, among which 213 were not identified in single population GWAS. Notably, 229 and 413 SNPs were located on SSC16 in the Yorkshire population and meta-analysis, respectively. Based on the 2-LOD drop-off interval, the SSC16 QTL in the Yorkshire population was further narrowed to a 679.835 kb interval (from 32.818 Mb to 33.498 Mb). The most significant variant within this QTL, 16_33228254 (P = 4.45 × 10-9), explained 1.11% phenotypic variance, representing a potential novel locus for LMA. Further bioinformatics analysis determined seven promising candidate genes (NDUFS4, ARL15, FST, ADAM12, DAB2, PLPP1, and SGMS2) with biological processes such as myoblast fusion and positive regulation of transforming growth factor beta receptor signaling pathway. Among them, ARL15 was previously reported in LMA studies, while the other six genes represent novel candidate genes. These findings reveal potential functional genes and pathways associated with LMA, providing valuable insights for future genetic improvement in pigs.

Association of the circulating lipid panel, PCPro, with clinical outcomes in metastatic hormone-sensitive prostate cancer: post-hoc analysis of the ENZAMET Phase 3 randomised trial (ANZUP 1304)

BACKGROUND

Enzalutamide significantly improves overall survival (OS) of patients with metastatic hormone- sensitive prostate cancer (mHSPC). However, ∼10% of patients will die within 2 years. PCPro is a plasma lipid panel associated with decreased OS in metastatic castration-resistant prostate cancer. In this study, we assessed the association between PCPro and clinical outcomes in mHSPC by performing a post-hoc analysis of ENZAMET, the landmark phase 3 trial comparing enzalutamide to non-steroidal anti-androgen (NSAA).

PATIENTS AND METHODS

PCPro status was determined by liquid chromatography-mass spectrometry analysis of plasma samples from 866 participants (77% of ENZAMET trial cohort), before treatment (n=866) and at first progression (n=282). Outcomes examined were OS and clinical progression-free survival (clinPFS).

RESULTS

Participants with a positive PCPro status at baseline (13.4%), had significantly shorter OS and clinPFS compared to those with a negative PCPro status (OS HR=1.81; clinPFS HR=1.65; p<0.0001). PCPro is an independent prognostic factor when modelled with key clinical prognostic factors (p<0.001). Enzalutamide (compared to NSAA) improved the OS of PCPro-negative participants (HR = 0.61, p<0.0001), but not the survival of PCPro-positive participants (HR=1.10, p=0.69; interaction p=0.024). Participants, who were PCPro-positive at progression, have shorter OS than those who were negative, irrespective of baseline status (median OS 24-28 months versus 42-45 months).

CONCLUSION

PCPro status is a prognostic biomarker and predictive of the lack of OS benefit from enzalutamide compared to NSAA in mHSPC. These findings provide a rationale for testing therapeutic agents that can modify circulating lipid profiles in mHSPC.

Lipid Subclasses Differentiate Insulin Resistance by Triglyceride-Glucose Index

BACKGROUND

Insulin resistance is a key driver of metabolic syndrome and related disorders, yet its underlying metabolic alterations remain incompletely understood. The Triglyceride-Glucose (TyG) index is an emerging, accessible marker for insulin resistance, with growing evidence supporting its clinical utility. This study aimed to characterize the metabolic profiles associated with insulin resistance using the TyG index in a large, population-based cohort, and to identify metabolic pathways potentially implicated in insulin resistance.

METHODS

Here, we conducted a cross-sectional study using data from the Qatar Biobank, including 1255 participants without diabetes classified as insulin-sensitive or insulin-resistant based on TyG index tertiles. Untargeted serum metabolomics profiling was performed using high-resolution mass spectrometry. Our statistical analyses included orthogonal partial least squares discriminate analysis and linear models.

RESULTS

Distinct metabolic signatures differentiated insulin-resistant from insulin-sensitive participants. Phosphatidylethanolamines, phosphatidylinositols, and phosphatidylcholines, were strongly associated with insulin resistance, while plasmalogens and sphingomyelins were consistently linked to insulin sensitivity.

CONCLUSIONS

Lipid-centric pathways emerge as potential biomarkers and therapeutic targets for the early detection and personalized management of insulin resistance and related metabolic disorders. Longitudinal studies are warranted to validate causal relationships.

Expanding the understanding of insulin resistance in brain and periphery

Insulin resistance is a central feature of metabolic disorders such as type 2 diabetes (T2D). While studies on this disorder have largely been linked to glucose metabolism and intracellular signaling, recent advances reveal that insulin resistance extends beyond traditional glucose regulatory pathways, impacting multiple organs including the brain, contributing to cognitive dysfunction and neurodegenerative diseases such as Alzheimer's disease (AD). This opinion revisits insulin resistance through molecular, cellular, and systemic perspectives, emphasizing the intersection between peripheral and brain insulin resistance (BIR), the role of the blood-brain barrier (BBB), and emerging biomarkers. Furthermore, we integrate insights from multi-omics and neuroimaging studies to refine our understanding, advocating for a broader perspective that informs early detection and intervention in metabolic and neurodegenerative diseases.

Hepatic sphingomyelin phosphodiesterase 3 promotes steatohepatitis by disrupting membrane sphingolipid metabolism

Metabolic-dysfunction-associated steatohepatitis (MASH) remains a major health challenge. Herein, we identify sphingomyelin phosphodiesterase 3 (SMPD3) as a key driver of hepatic ceramide accumulation through increasing sphingomyelin hydrolysis at the cell membrane. Hepatocyte-specific Smpd3 gene disruption or pharmacological inhibition of SMPD3 alleviates MASH, whereas reintroducing SMPD3 reverses the resolution of MASH. Although healthy livers express low-level SMPD3, lipotoxicity-induced DNA damage suppresses sirtuin 1 (SIRT1), triggering an upregulation of SMPD3 during MASH. This disrupts membrane sphingomyelin-ceramide balance and promotes disease progression by enhancing caveolae-dependent lipid uptake and extracellular vesicle secretion from steatotic hepatocytes to exacerbate inflammation and fibrosis. Consequently, SMPD3 acts as a central hub integrating key MASH hallmarks. Notably, we discovered a bifunctional agent that simultaneously activates SIRT1 and inhibits SMPD3, which shows significant therapeutic potential in MASH treatment. These findings suggest that inhibition of hepatic SMPD3 restores membrane sphingolipid metabolism and holds great promise for developing novel MASH therapies.

Eggshell depigmentation in the late phase of production is associated with altered Microbiota and Metabolism of the uterus in laying hens

The significant depigmentation of brown eggshells occurs in the in the late-phase laying hens, which directly affects consumer acceptance. However, the biological mechanism of eggshell depigmentation based on uterine metabolism has not been elucidated. In this study, a total of 4 group were as follows: 1) 65-week-old laying hens with normal color; 2) 65-week-old laying hens with light color; 3) 80-week-old laying hens with normal color; 4) 80-week-old laying hens with light color. Variations in the pigment contents, uterine antioxidant capacity, uterine microbiota, and uterine metabolomics were examined in current study. Results showed that significantly decreased L* values and increased a* and b* values were observed in the depigmentation group (P < 0.05). The protoporphyrin IX content of the uterus with eggshell depigmentation was significantly decreased in 65-week-old laying hens (P < 0.05). Uterine MDA content was significantly increased in the depigmentation groups at 65 and 80 weeks of age, accompanied by reduced SOD and increased IgA levels (P > 0.05). The abundance of Proteobacteria and Campilobacterota was markedly reduced in the uterus with eggshell depigmentation, whereas Firmicutes was elevated at 65 weeks of age (P < 0.05). Further, Psychrobacte as biomarkers can accurately distinguish between normal color and depigmentation in eggshells (AUC = 0.91). A total of 51 differential metabolites were significantly enriched in the down-regulated sphingolipid metabolism, linoleic acid metabolism, citrate cycle, oxidative phosphorylation, PPAR signaling pathway, FoxO signaling pathway, and apoptosis at 65 weeks of age (P < 0.05). Meanwhile, there were 82 differential metabolites were significantly up-regulated at 80 weeks of age, which mainly enriched in up-regulated linoleic acid metabolism, purine metabolism, and pentose phosphate pathway (P < 0.05). These findings elucidate the specific metabolic mechanisms responsible for eggshell depigmentation in 65- and 80-week-old laying hens, contributing to the improvement of eggshell depigmentation by the precise nutritional modulation in the late-phase laying hens.

Metabolic profiling of abdominal subcutaneous adipose tissue reveals effects of apple polyphenols for reversing high-fat diet induced obesity in C57BL/6 J mice

Apple polyphenols (APP) can reduce obesity. However, the effects of APP on abdominal subcutaneous adipose tissue (aSAT) at metabolic level were unclear. In this study, 5-week APP intervenes were conducted on 10-week high-fat diet (HFD) feeding mice with doses of 200 and 500 mg/kg b.w./day, followed by ultra-high-performance liquid chromatography-mass spectrometry based untargeted metabolomics analysis. As expected, APP obviously reversed aSAT weight and index, as well as activities of myeloperoxidase, glutathione peroxidase, superoxide dismutase and catalase. Euclidean distance between HFD and normal chow diet (NCD) group was shortened. 64 and 127 differential metabolites were found in 200 and 500 mg/kg b.w./day group, with 12 and 13 changed pathways, respectively. Specifically, APP restored glycolysis, tricarboxylic acid cycle, amino acid metabolism, and lipid metabolism as dose-dependent manner. Finally, glucose-6-phosphate, xanthine and tyrosine were selected as critical junctures. Collectively, these findings underscore the potential of APP in reversing molecular alterations in aSAT.

Cross-talk between signal transduction systems and metabolic networks in antibiotic resistance and tolerance

The comprehensive antibiotic resistance of pathogens signifies the oneset of the "post-antibiotic era", and the myriad treatment challenges posed by "superbugs" have emerged as the primary threat to human health. Recent studies indicate that bacterial resistance and tolerance development are mediated at the metabolic level by various signalling networks (e.g., quorum sensing systems, second messenger systems, and two-component systems), resulting in metabolic rearrangements and alterations in bacterial community behaviour. This review focuses on current research, highlighting the intrinsic link between signalling and metabolic networks in bacterial resistance and tolerance.

Role of Canonical and Non-Canonical Sphingolipids and their Metabolic Enzymes in Bone Health

PURPOSE OF REVIEW

This review summarizes the recently published scientific evidence regarding the role of enzymes engaged in de novo anabolic biosynthesis, catabolic, and salvage pathways of ceramide bioactive sphingolipids in bone dynamics and skeletal health.

RECENT FINDINGS

Ceramides are precursors for bioactive sphingolipids, including sphingosine, sphingosine-1-phosphate, and others. Studies of bone metabolism and bone-related cells demonstrated that ceramide and sphingosine-1-phosphate control levels of bone remodeling and resorption generated by osteoblasts and osteoclasts. Multiple published studies demonstrated the critical role of enzymes in regulating the ceramide/sphingosine-1-phosphate ratio relative to bone physiology and the promotion of inflammatory osteolysis. Accordingly, emerging evidence suggests that targeting sphingolipid metabolism has the potential to alleviate inflammatory osteolysis and accelerate bone regeneration. Therefore, this study aimed to discuss current knowledge about crosstalk between sphingolipids and their metabolic enzymes within osteoclast and osteoblast coupling in bone remodeling and pathogenic osteolysis. This review highlights the complexity of de novo sphingolipid biosynthesis and knowledge gaps in bone physiology and pathology. We also discuss the importance of canonical and non-canonical mammalian and bacterial-derived sphingolipids relative to bone health.

Sphingolipid Metabolism and Signalling Pathways in Heart Failure: From Molecular Mechanism to Therapeutic Potential

Sphingolipids are essential components of cell membranes and lipoproteins. They are synthesized de novo in the endoplasmic reticulum and subsequently undergo various enzymatic modifications in different organelles, giving rise to a diverse range of biologically active compounds. These molecules play a critical role in regulating cell growth, senescence, migration, apoptosis, and signaling. In recent years, the sphingolipid metabolic pathway has been recognized as a key factor in heart failure (HF) pathophysiology. Abnormal levels of sphingolipid metabolites, such as ceramide (Cer) and sphingomyelin (SM), contribute to oxidative stress and inflammatory responses, ultimately promoting cardiomyocyte apoptosis. Conversely, sphingosine-1-phosphate (S1P) and ceramide-1-phosphate (C1P) regulate vascular function and influence cardiac remodeling. Additionally, enzymes such as diacylglycerol acyltransferase 1 (DGAT1) and sphingosine-1-phosphate lyase 1 (SGPL1) modulate cardiac lipid metabolism. Given their role in HF progression, monitoring sphingolipid alterations offers potential as valuable biomarkers for assessing disease severity, prognosis, and diagnosis. Given the complexity of sphingolipid metabolism and its involvement in diverse regulatory biological processes, a comprehensive understanding of its roles at both the cellular and organismal levels in physiopathology remains incomplete. Therefore, this review aims to explore the physiological functions, regulatory mechanisms, and therapeutic potential of sphingolipid metabolism. It will summarize the specific molecular mechanisms driving key pathological processes in HF, including ventricular remodeling, myocardial fibrosis, vascular dysfunction, and metabolic disorders. Finally, the review will highlight targeted sphingolipid metabolites as potential therapeutic strategies, offering new insights into HF diagnosis and treatment, with the goal of advancing adjunctive clinical therapies.

Transcriptomics and metabolomics analysis of the pathogenesis of a novel hyperlipidemia-susceptible rat strain

Wistar-SD Hypercholesterolemia (WSHc) Rat is a novel hyperlipidemia-susceptible rat that we discovered and bred earlier, which can be used as an ideal animal model for the study of non-alcoholic fatty liver disease (NAFLD). However, its pathogenesis of hyperlipidemia and genetic and biological characteristics need to be further investigated. In the current study, WSHc rats were fed a high-fat diet (HFD) and standard chow (SC), with age-matched Wistar rats as the control group undergoing the same treatment, followed by serum lipid level measurement. It was found that HFD-fed WSHc rats developed dyslipidemia. Transcriptomic analysis was performed to detect genes associated with cholesterol metabolism in the liver, and 119 differentially expressed genes were discovered through bioinformatics analysis and molecular biology verification. Additionally, Srebf1 was identified as a HUB gene and Nr1d1 as an independent key gene using the protein-protein interaction network and one-cluster clustering analysis. The two genes had also been further validated in molecular biology experiments and were consistent with transcriptomic results. Serum lipid metabolomics analysis identified 7 lipid subclasses and 84 lipid molecules using UHPLC-Q-TOF/MS. There were 62 and 70 lipid molecules with significant differences in the metabolic profiles of serum lipid mediators in the WSHc+HFD group compared to the WSHc+SC and Wistar+HFD groups, respectively, and the differential metabolites were mainly produced via sphingolipid and glycerophospholipid metabolism. In sum, the hypercholesterolemia model can be established with WSHc rats after the HFD induction, and the pathogenesis involves the Srebf1 and Nr1d1 genes and the sphingolipid and glycerophospholipid metabolism pathways.

The Bioactive Sphingolipid Playbook. A Primer for the Uninitiated as well as Sphingolipidologists

Sphingolipids and glycosphingolipids are among the most structurally diverse and complex compounds in the mammalian metabolome. They are well known to play important roles in biological architecture, cell-cell communication and cellular regulation, and for many biological processes, multiple sphingolipids are involved. Thus, it is not surprising that untargeted genetic/transcriptomic/pharmacologic/metabolomic screens have uncovered changes in sphingolipids and sphingolipid genes/proteins while studying physiological and pathological processes. Consequently, with increasing frequency, both targeted and untargeted mass spectrometry methodologies are being used to conduct sphingolipidomic analyses. Interpretation of such large data sets and design of follow-up experiments can be daunting for investigators with limited expertise with sphingolipids (and sometimes even for someone well-versed in sphingolipidology). Therefore, this review gives an overview of essential elements of sphingolipid structure and analysis, metabolism, functions, and roles in disease, and discusses some of the items to consider when interpreting lipidomics data and designing follow-up investigations.

The carotenoid torularhodin alleviates NAFLD by promoting Akkermanisa muniniphila-mediated adenosylcobalamin metabolism

Torularhodin, a unique carotenoid, confers beneficial effects on nonalcoholic fatty liver disease (NAFLD). However, the precise mechanism underlying its therapeutic effects remains unknown. Here, we report that torularhodin alleviates NAFLD in male mice by modulating the gut microbiota. Additionally, transplanting fecal microbiota from torularhodin-treated mice to germ-free mice also improves NAFLD. Mechanistically, torularhodin specifically enriches the abundance of Akkermansia muciniphila, which alleviates NAFLD by promoting the synthesis of adenosylcobalamin. Utilizing a human gastrointestinal system and a colonic organoid model, we further demonstrate that adenosylcobalamin confers protective effects against NAFLD through reducing ceramides, a well-known liver damaging compound, and this effect is mediated by inhibition of the hypoxia-inducible factor 2α pathway. Notably, we construct electrospun microsphere-encapsulated torularhodin, which facilitates the slow release of torularhodin in the colon. Together, our findings indicate the therapeutic potential of microbial utilization of carotenoids, such as torularhodin, for treating NAFLD.

Unveiling the Antiobesity Mechanism of Sweet Potato Extract by Microbiome, Transcriptome, and Metabolome Analyses in Mice

This study aimed to elucidate the antiobesity mechanisms of sweet potato extract (SPE) through biochemical, gut microbiome, liver transcriptome, and metabolome analyses. Administration of SPE to high-fat-diet-fed mice significantly reduced body weight gain, serum low-density lipoprotein cholesterol, hepatic lipid accumulation, and adipocyte hypertrophy, which were closely linked to gut microbiome composition. SPE notably increased the abundance of Eubacterium_coprostanoligenes_group_unclassified and decreased that of Kineothrix, both of which were strongly associated with short-chain fatty acid (SCFA) production. LC-QTOF-MS analysis identified resin glycoside compounds from SPE with reduced levels in mouse feces, suggesting their utilization in vivo. SPE also promoted dietary fat excretion. Liver transcriptomic and metabolomic profiling revealed that SPE may exert antiobesity effects by modulating the bile-sphingolipid metabolism, which was closely correlated with the reshaped gut microbiomes and SCFAs. These findings provide new insights into the antiobesity effects and mechanisms of SPE.

Application of metabolomics in the classification of traditional Chinese medicine syndromes in rheumatoid arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is frequently treated with traditional Chinese medicine (TCM), where patients are classified into distinct syndromes, such as heat-dampness syndrome (HD) and kidney-liver deficiency syndrome (KLD). However, an objective and systematic approach to differentiate these TCM syndromes remains lacking. This study is aimed at analyzing serum metabolomics to identify differential metabolites and pathways associated with HD and GS syndromes in RA patients and at evaluating their potential as diagnostic biomarkers.

METHODS

Serum samples from RA patients classified into HD and KLD groups were analyzed using metabolomics. Partial least squares discriminant analysis was employed to identify significant metabolites, while pathway analysis was conducted using the Kyoto Encyclopedia of Genes and Genomes database. Receiver operating characteristic (ROC) curve analysis was performed to assess the diagnostic potential of key metabolites.

RESULTS

Fifteen differential metabolites and two perturbed pathways-sphingolipid and D-amino acid metabolism-were identified between the KLD and HD groups. Notably, several metabolites, including C17-sphinganine and leucyl-alanine, demonstrated high diagnostic efficacy, with area under the curve (AUC) values exceeding 0.90. Correlation analysis revealed significant associations between certain metabolites and clinical indices, further substantiating their role in syndrome differentiation.

CONCLUSION

This study presents a comprehensive analysis of serum metabolites in RA patients under different TCM syndromes. The identified metabolites hold potential as biomarkers for distinguishing HD and KLD groups, paving the way for more objective and evidence-based diagnostic approaches in TCM. Key Points • Differential metabolites were identified in the serum of RA patients with heat-dampness syndrome and kidney-liver deficiency syndrome, with their metabolic pathways primarily involving sphingolipid metabolism and D-amino acid metabolism. • Serum metabolites demonstrate high efficacy in distinguishing RA patients with different TCM syndromes. • Significant correlations were observed between serum differential metabolites and clinical indicators in RA patients with varying TCM syndromes.

Effects of acute low intensity aerobics and blueberry juice on arterial stiffness in young adults

Arterial stiffness, a cardiovascular disease (CVD) predictor starting from youth, is under-researched in young adults. Low-intensity aerobic exercise (LAE) is generally more accessible than higher-intensity exercise and may be more sustainable for young individuals. Blueberries, renowned for vascular health benefits, may reduce arterial stiffness. This study examines the effects of LAE and blueberry juice on arterial stiffness in 48 young adults. Participants were randomized into LAE, low-, mid-, or high-volume blueberry juice (LB, MB, HB), LAE + LB, LAE + MB, LAE + HB, and control groups. Arterial stiffness was measured at baseline and at 15-, 30-, 45-, and 60 min post-intervention. Blood samples were collected pre-intervention and 30-min post-intervention for metabolomic analysis. Repeated ANOVA revealed LAE + MB significantly reduced arterial stiffness. Metabolomic analysis revealed changes in linoleic acid, sphingolipid, phenylalanine, nicotinate and nicotinamide, glycerophospholipid, and lysine degradation metabolic pathways. These findings suggest a feasible exercise-diet strategy for CVD prevention in young adults and provide metabolic insights into the mechanisms.

Sphingosine-1-Phosphate-Cathelicidin Axis Plays a Pivotal Role in the Development of Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma (cSCC) is a common skin cancer caused by mutagenesis resulting from excess UVR or other types of oxidative stress. These stressors also upregulate the production of a cutaneous innate immune element, cathelicidin antimicrobial peptide (CAMP), through endoplasmic reticulum stress-initiated, sphingosine-1-phosphate (S1P) signaling pathway. Although CAMP has beneficial antimicrobial activities, it also can be proinflammatory and procarcinogenic. We addressed whether and how S1P-induced CAMP production leads to cSCC development. Our study demonstrated that (i) CAMP expression is increased in cSCC cells and skin from patients with cSCC; (ii) S1P levels are elevated in cSCC cells, whereas inhibition of S1P production attenuates CAMP-stimulated cSCC growth; (iii) exogenous CAMP stimulates cSCC but not normal human keratinocyte growth; (iv) blockade of FPRL1 protein, a CAMP receptor, attenuates cSCC growth as well as the growth and invasion of cSCC cells mediated by CAMP into an extracellular matrix-containing fibroblast substrate; (v) FOXP3+ regulatory T-cell (which decreases antitumor immunity) levels increase in cSCC skin; and (vi) CAMP induces endoplasmic reticulum stress in cSCC cells. Together, the endoplasmic reticulum stress-S1P-CAMP axis forms a vicious circle, creating a favorable environment for cSCC development, that is, cSCC growth and invasion impede anticancer immunity.

How Effectively Can Oxidative Stress and Inflammation Be Reversed When CFTR Function Is Pharmacologically Improved?

A critical challenge in the age of advanced modulator therapies is to understand and determine how effectively chronic oxidative stress and oxidative stress-induced inflammation can be reversed and physiological balance restored when CFTR function is pharmacologically improved. The triple therapy with elexacaftor-tezacaftor-ivacaftor (ETI) suggests that CFTR activity in individuals with at least one F508del mutation can be partially restored to about 50% of normal levels. Although incomplete, the partial recovery of CFTR function has been shown to drastically lower sputum pathogen content, enhance microbiome diversity, and lower inflammation markers within the first year of treatment in adolescents and adults with cystic fibrosis. However, despite these advancements, residual airway infection, oxidative stress and inflammation persist, with levels similar to other chronic lung conditions, like non-CF bronchiectasis. This persistence highlights the necessity for innovative antioxidant and anti-inflammatory treatments, in particular for individuals with advanced lung disease. To address this issue, emerging multi-omics technologies offer valuable tools to investigate the impact of modulator therapies on various molecular pathways. By analyzing changes in gene expression, epigenetic modifications, protein profiles and metabolic processes in airway-derived samples, it could be possible to uncover the mechanisms driving persistent oxidative stress and inflammation. These insights could pave the way for identifying new therapeutic targets to fully restore airway health and overall physiological balance.

Ceramide in Coronary Artery Disease: Troublesome or Helpful Future Tools in the Assessment of Risk Prediction and Therapy Effectiveness?

Lipids are a complex entity of different molecules, among which ceramides (Cers), ubiquitous sphingolipids with remarkable biological activity, can represent a potential additive biomarker that can be used to better understand the underlying mechanisms which drive the onset and development of atherosclerotic damage and plaque vulnerability and facilitate coronary disease management, as possible risk/prognostic biomarkers and targets for therapeutic intervention. Accordingly, this review aims to discuss the available results on the role Cersplay in contributing to atherosclerosis development and acute coronary event precipitation, their impact on complications and adverse prognosis, as well as the impact of treatment options in modulating Cerlevels.

Sphingolipid metabolites involved in the pathogenesis of atherosclerosis: perspectives on sphingolipids in atherosclerosis

Atherosclerosis, with its complex pathogenesis, is a leading underlying cause of many cardiovascular diseases, which are increasingly prevalent in the population. Sphingolipids play an important role in the development of atherosclerosis. Key metabolites and enzymes in sphingolipid metabolism influence the pathogenesis of atherosclerosis in a variety of ways, including inflammatory responses and oxidative stress. Thus, an investigation of sphingolipid metabolism-related metabolites and key enzymes may provide novel insights and treatment targets for atherosclerosis. This review discusses various mechanisms and research progress on the relationship between various sphingolipid metabolites, related enzymes, and atherosclerosis. Finally, we look into the future research direction of phytosphingolipids.

Thyroid hormone receptor-beta agonist HSK31679 alleviates MASLD by modulating gut microbial sphingolipids

BACKGROUND & AIMS

As the first approved medication for metabolic dysfunction-associated steatohepatitis (MASH), the thyroid hormone receptor-β (THR-β) agonist MGL-3196 (resmetirom) has garnered much attention as a liver-directed, bioactive oral drug. However, studies on MGL-3196 have also identified remarkable heterogeneity of individual clinical efficacy and its interference with gut microbiota in host hepatoenteral circulation remains to be elucidated.

METHODS

We compared MASH attenuation by MGL-3196 and its derivative drug HSK31679 between germ-free (GF) and specific-pathogen free (SPF) mice to evaluate the role of gut microbiota. Then cross-omics analyses of microbial metagenome, metabolome and single-cell RNA-sequencing were applied to a randomized, double-blind, placebo-controlled multiple ascending dose cohort receiving HSK31679 treatment (n = 32) or placebo (n = 8), to comprehensively investigate the altered gut microbiota metabolism and circulating immune signatures.

RESULTS

HSK31679 outperformed MGL-3196 in ameliorating MASH diet-induced steatohepatitis of SPF mice but not GF mice. In the multiple ascending dose cohort of HSK31679, the relative abundance of B. thetaiotaomicron was significantly enriched, impairing glucosylceramide synthase (GCS)-catalyzed monoglucosylation of microbial Cer(d18:1/16:0) and Cer(d18:1/24:1). In contrast to the non-inferior effect of MGL-3196 and HSK31679 on MASH resolution in GFBTΔGCS mice, HSK31679 led to superior benefit on steatohepatitis in GFBTWT mice, due to its steric hindrance of R123 and Y401 of gut microbial GCS. For participants with high fecal GCS activity, the administration of 160 mg HSK31679 induced a shift in peripheral compartments towards an immunosuppressive niche, characterized by decreased CD8α+ dendritic cells and MINCLE+ macrophages.

CONCLUSIONS

This study provided novel insights into the gut microbiota that are key to the efficacy of HSK31679 treatment, revealing microbial GCS as a potential predictive biomarker in MASH, as well as a new target for further microbiota-based treatment strategies for MASH.

IMPACT AND IMPLICATIONS

Remarkable heterogeneity in individual clinical efficacy of thyroid hormone receptor-β agonists and their interferences with the microbiome in host hepatoenteral circulation are poorly understood. In our current germ-free mouse models and a randomized, double-blind, multiple-dose cohort study, we identified microbial glucosylceramide synthase as a key mechanistic node in the resolution of metabolic dysfunction-associated steatohepatitis. Microbial glucosylceramide synthase activity could be a predictive biomarker of response to HSK31679 treatment or a new target for microbiota-based therapeutics in metabolic dysfunction-associated steatohepatitis.

Multiple sphingolipid-metabolizing enzymes modulate influenza virus replication

The sphingolipid network is sustained principally by the balance of bioactive sphingolipid molecules and their regulation by sphingolipid-metabolizing enzymes. The components in the lipid system display key functions in numerous cellular and disease conditions including virus infections. During the COVID-19 pandemic, there was a fruitful effort to use an inhibitor that blocks the activity of sphingosine kinase (SphK) 2 to cure the devastating disease. Support for the inhibitor came from pre-clinical research on influenza where the inhibitor demonstrated effective protection of mice from influenza-induced morbidity and mortality. This highlights the importance of basic and translational research on the sphingolipid system for improving human health. Multiple sphingolipid-metabolizing enzymes have been reported to regulate influenza virus replication and propagation. In this review, the emphasis is placed on the roles of these enzymes that impact influenza virus life cycle and the conceivable mechanisms for the interplay between influenza virus and the sphingolipid pathway.

Lipidomics reveals the lipid-lowering and hepatoprotective effects of Celosia Semen on high-fat diet-induced NAFLD mice

ETHNOPHARMACOLOGICAL RELEVANCE

Celosia Semen (CS) serves as a traditional Chinese medicine (TCM) for promoting liver health and enhancing vision, with extensive clinical applications. Triterpenoid saponins represent the primary active components of CS, with the highest concentration of Celosin I (CI) detected. The urgent need for effective NAFLD treatments motivated us assess the beneficial effects of total saponins from CS (TSCS) and CI.

AIMS OF THE STUDY

To investigate the therapeutic effects of TSCS and CI on NAFLD and its underlying molecular mechanisms.

MATERIALS AND METHODS

The impact of TSCS and CI on NAFLD was evaluated through in vitro and in vivo methodologies, utilizing high-fat diet (HFD) and palmitic acid/oleic acid modeling on C57BL/6J mice and AML12 cells, respectively. Biochemical analysis, H&E and Oil red O staining were used to characterize the lipid-lowering and hepatoprotective activities of TSCS and CI. Lipidomics discerned the impact of TSCS and CI interventions on liver lipid composition, distribution and alteration in NFALD mice. RT-qPCR and western blotting detected the influence of TSCS and CI on genes linked to de novo lipogenesis, fat calculation uptake, oxidation and esterification. The docking analysis anticipated the interaction of six major triterpenoid saponins within TSCS with SREBP1.

RESULTS

TSCS and CI markedly diminished lipid accumulation induced by high fat both in vivo and in vitro. TSCS and CI also mitigated hepatic steatosis and liver injury induced by HFD through the reduction of TC, TG, FAs, ALT, and AST, even at minimal dose of 25 mg/kg. Lipidomics indicated that TSCS and CI had the potential to modulate the lipid metabolism network, rectify lipid metabolic dysregulation induced by NAFLD, decrease the levels of harmful lipids, and elevate the levels of advantageous lipids. Furthermore, TSCS and CI exhibited a strong affinity to SREBP1, thereby might directly influence the expression of SREBP1 and a cascade of essential enzymes involved in de novo lipogenesis, and finally resulting in a diminished synthesis of novel lipids.

CONCLUSION

TSCS and CI were confirmed firstly as key active components of CS in amending hepatic steatosis and mitigate liver damage in NAFLD, outlining the preliminary mechanism. They warrant further exploration as drug candidates for NAFLD treatment, especially in light of the current shortage of medications and limited therapeutic options.

Pediococcus acidilactici Y01 reduces HFD-induced obesity via altering gut microbiota and metabolomic profiles and modulating adipose tissue macrophage M1/M2 polarization

Obesity-related metabolic syndrome is intimately associated with infiltrated adipose tissue macrophages (ATMs), gut microbiota, and metabolic disorders. Pediococcus acidilactici holds the potential to mitigate obesity; however, there exist strain-specific functionalities and diverse mechanisms, which deserve extensive exploration. This study aims to explore the potential of P. acidilactici Y01, isolated from traditional sour whey, in alleviating HFD-induced metabolic syndrome in mice and elucidating its underlying mechanism. The results showed that P. acidilactici Y01 could inhibit the increase of body weight gain, the deposition of fat, lipid disorders and chronic low-grade inflammation, improve glucose tolerance and insulin resistance, and could reduce adipose tissue inflammation by decreasing M1-type ATMs and increasing M2-type ATMs. Meanwhile, P. acidilactici Y01 significantly increased the abundance of potentially beneficial intestinal bacteria, such as Akkermansia, Alistipes, Bifidobacterium, Lachnospiraceae_NK4A136_group, Lactobacillus, norank_f__Muribaculaceae, and Parabacteroides, and partially restored the levels of metabolites, such as phosphatidylcholines, glycerophosphocholines, sphingolipids and unsaturated fatty acids. The fecal microbiota transplantation experiment demonstrated that P. acidilactici Y01 ameliorated obesity-related metabolic syndrome by modulating the polarization of M1/M2 ATMs mediated by gut microbiota. Overall, as a dietary supplement, P. acidilactici Y01 has good potential in the prevention and treatment of obesity.

Genetically predicted causal link between the plasma lipidome and pancreatic diseases: a bidirectional Mendelian randomization study

Background

Recent studies have increasingly emphasized the strong correlation between the lipidome and the risk of pancreatic diseases. To determine causality, a Mendelian randomization (MR) analysis was performed to identify connections between the lipidome and pancreatic diseases.

Methods

Statistics from a genome-wide association study of the plasma lipidome, which included a diverse array of 179 lipid species, were obtained from the GeneRISK cohort study with 7,174 participants. Genetic associations with four types of pancreatitis and pancreatic cancer were sourced from the R11 release of the FinnGen consortium. Two pancreatitis datasets from UK Biobank were employed as the validation cohort. MR analysis was conducted to assess the relationship between the genetically predicted plasma lipidome and these pancreatic diseases. Inverse variance weighted was adopted as the main statistical method. Bayesian weighted MR was employed for further verification. The MR-Egger intercept test for pleiotropy and Cochrane's Q statistics test for heterogeneity were performed to ensure the robustness.

Results

MR analysis yielded significant evidence that 26, 25, 2, and 19 lipid species were correlated with diverse outcomes of pancreatitis, and 8 lipid species were correlated with pancreatic cancer. Notably, sterol ester (27:1/20:2) levels (OR: 0.84, 95% CI: 0.78-0.90, P = 5.79 × 10-7) were significantly associated with acute pancreatitis, and phosphatidylcholine (17:0_20:4) levels (OR: 0.89, 95% CI: 0.84-0.94, P = 1.78 × 10-4) and sterol ester (27:1/20:4) levels (OR: 0.90, 95% CI: 0.86-0.95, P = 2.71 × 10-4) levels were significantly associated with chronic pancreatitis after the Bonferroni-corrected test. As for validation, 14 and 9 lipid species were correlated with acute and chronic pancreatitis of UK Biobank. Some lipid classes showed significant effects both in the FinnGen consortium and UK Biobank datasets.

Conclusions

The findings of this study indicate a potential genetic predisposition linking the plasma lipidome to pancreatic diseases and good prospects for future pancreatic disease clinical trials.

Don't Be Surprised When These Surprise You: Some Infrequently Studied Sphingoid Bases, Metabolites, and Factors That Should Be Kept in Mind During Sphingolipidomic Studies

Sphingolipidomic mass spectrometry has provided valuable information-and surprises-about sphingolipid structures, metabolism, and functions in normal biological processes and disease. Nonetheless, many noteworthy compounds are not routinely determined, such as the following: most of the sphingoid bases that mammals biosynthesize de novo other than sphingosine (and sometimes sphinganine) or acquire from exogenous sources; infrequently considered metabolites of sphingoid bases, such as N-(methyl)n-derivatives; "ceramides" other than the most common N-acylsphingosines; and complex sphingolipids other than sphingomyelins and simple glycosphingolipids, including glucosyl- and galactosylceramides, which are usually reported as "monohexosylceramides". These and other subspecies are discussed, as well as some of the circumstances when they are likely to be seen (or present and missed) due to experimental conditions that can influence sphingolipid metabolism, uptake from the diet or from the microbiome, or as artifacts produced during extraction and analysis. If these compounds and factors are kept in mind during the design and interpretation of lipidomic studies, investigators are likely to be surprised by how often they appear and thereby advance knowledge about them.

Clinical presentation and management challenges of sphingosine-1-phosphate lyase insufficiency syndrome associated with an SGPL1 variant: a case report

BACKGROUND

This case report describes a unique presentation of sphingosine-1-phosphate lyase insufficiency syndrome (SPLIS) caused by a rare SGPL1 variant, highlighting the diagnostic and management challenges associated with this condition.

CASE PRESENTATION

A 2-year-old Iranian female presented with steroid-resistant nephrotic syndrome (NS), primary adrenal insufficiency (AI), growth delay, seizures, and hyperpigmentation. Laboratory evaluation revealed hypoalbuminemia, significant proteinuria, hyperkalemia, and elevated adrenocorticotropic hormone (ACTH) levels. The patient was diagnosed with SPLIS through genetic testing, revealing a c.1018 C > T variant in SGPL1. Despite supportive treatment, including corticosteroids and cyclosporine, the patient's condition deteriorated, leading to end-stage renal disease and sepsis, ultimately resulting in death.

CONCLUSIONS

This case underscores the clinical heterogeneity of SPLIS and the importance of early genetic evaluation in patients with combined NS and AI. Personalized management approaches and increased awareness among clinicians are essential to improve patient outcomes.

Optical control of sphingolipid biosynthesis using photoswitchable sphingosines

Sphingolipid metabolism comprises a complex interconnected web of enzymes, metabolites, and modes of regulation that influence a wide range of cellular and physiological processes. Deciphering the biological relevance of this network is challenging as numerous intermediates of sphingolipid metabolism are short-lived molecules with often opposing biological activities. Here, we introduce clickable, azobenzene-containing sphingosines, termed caSphs, as light-sensitive substrates for sphingolipid biosynthesis. Photo-isomerization of the azobenzene moiety enables reversible switching between a straight trans- and curved cis-form of the lipid's hydrocarbon tail. Combining in vitro enzyme assays with metabolic labeling studies, we demonstrate that trans-to-cis isomerization of caSphs profoundly stimulates their metabolic conversion by ceramide synthases and downstream sphingomyelin synthases. These light-induced changes in sphingolipid production rates are acute, reversible, and can be implemented with great efficiency in living cells. Our findings establish caSphs as versatile tools for manipulating sphingolipid biosynthesis and function with the spatiotemporal precision of light.

Deciphering the role of sphingosine 1-phosphate in central nervous system myelination and repair

Sphingosine 1-phosphate (S1P) is a bioactive lipid of the sphingolipid family and plays a pivotal role in the mammalian nervous system. Indeed, S1P is a therapeutic target for treating demyelinating diseases such as multiple sclerosis. Being part of an interconnected sphingolipid metabolic network, the amount of S1P available for signalling is equilibrated between its synthetic (sphingosine kinases 1 and 2) and degradative (sphingosine 1-phosphate lyase) enzymes. Once produced, S1P exerts its biological roles via signalling to a family of five G protein-coupled S1P receptors 1-5 (S1PR1-5). Despite significant progress, the precise roles that S1P metabolism and downstream signalling play in regulating myelin formation and repair remain largely opaque and somewhat controversial. Genetic or pharmacological studies adopting various model systems identify that stimulating S1P-S1PR signalling protects myelin-forming oligodendrocytes after central nervous system (CNS) injury and attenuates demyelination in vivo. However, evidence to support its role in remyelination of the mammalian CNS is limited, although blocking S1P synthesis sheds light on the role of endogenous S1P in promoting CNS remyelination. This review focuses on summarising the current understanding of S1P in CNS myelin formation and repair, discussing the complexity of S1P-S1PR interaction and the underlying mechanism by which S1P biosynthesis and signalling regulates oligodendrocyte myelination in the healthy and injured mammalian CNS, raising new questions for future investigation.

Human genetic defects of sphingolipid synthesis

Sphingolipids are ubiquitous lipids, present in the membranes of all cell types, the stratum corneum and the circulating lipoproteins. Autosomal recessive as well as dominant diseases due to disturbed sphingolipid biosynthesis have been identified, including defects in the synthesis of ceramides, sphingomyelins and glycosphingolipids. In many instances, these gene variants result in the loss of catalytic function of the mutated enzymes. Additional gene defects implicate the subcellular localization of the sphingolipid-synthesizing enzyme, the regulation of its activity, or even the function of a sphingolipid-transporter protein. The resulting metabolic alterations lead to two major, non-exclusive types of clinical manifestations: a neurological disease, more or less rapidly progressive, associated or not with intellectual disability, and an ichthyotic-type skin disorder. These phenotypes highlight the critical importance of sphingolipids in brain and skin development and homeostasis. The present article reviews the clinical symptoms, genetic and biochemical alterations, pathophysiological mechanisms and therapeutic options of this relatively novel group of metabolic diseases.

Flotillins in membrane trafficking and physiopathology

Flotillin 1 and 2 are highly conserved and homologous members of the stomatin, prohibitin, flotillin, HflK/C (SPFH) family. These ubiquitous proteins assemble into hetero-oligomers at the cytoplasmic membrane in sphingolipid-enriched domains. Flotillins play crucial roles in various cellular processes, likely by concentrating sphingosine. They primarily act as scaffolding protein complexes within membrane microdomains (also called lipid rafts) and induce endocytosis and trafficking. Their diverse cargos in the upregulated flotillin-induced trafficking (UFIT) pathway, including tyrosine kinase receptors, adhesion molecules, and neurotransmitter receptors, link them to a wide range of cellular processes and diseases. Consequently, flotillin upregulation has been associated with various pathological conditions such as cancer, metabolic disorders, and neurodegenerative diseases. Flotillins may also be co-opted by pathogens to facilitate their entry and growth within host cells. In this review, we examined recent advancements in elucidating the structure and functions of the flotillin protein complex, including its implications in favoring the generation of sphingosine 1-phosphate, an essential bioactive lipid. We emphasized how the recent cryo-electron microscopy (cryo-EM) structure of a truncated cone-shaped cage composed of 22 copies of flotillin 1 and 2 subunits has enhanced our understanding of the flotillin complex organization within membrane microdomains and its role in membrane remodeling. We also explored how flotillin upregulation can perturb endosomal trafficking and contribute to various pathologies. A comprehensive understanding of flotillin oligomer organization and function is crucial to developing targeted therapies for diseases associated with flotillin overexpression.

Early Recognition of Secondary Asthma Caused by Lower Respiratory Tract Infection in Children Based on Multi-Omics Signature: A Retrospective Cohort Study

Objective

To explore the types of pathogens causing lower respiratory tract infections (LTRIs) in children and construction of a predictive model for monitoring secondary asthma caused by LTRIs.

Methods

Seven hundred and seventy-five children with LTRIs treated from June 2017 to July 2024 were selected as research subjects. Bacterial isolation and culture were performed on all children, and drug sensitivity tests were conducted on the isolated pathogens; And according to whether the child developed secondary asthma during treatment, they were divided into asthma group (n = 116) and non-asthma group (n = 659); Using logistic regression model to analyze the risk factors affecting secondary asthma in children with LTRIs, and establishing machine learning (ie nomogram and decision tree) prediction models; Using ROC curve analysis machine learning algorithms to predict AUC values, sensitivity, and specificity of secondary asthma in children with LTRIs.

Results

792 pathogenic bacteria were isolated from 775 children with LTRIs through bacterial culture, including 261 Gram positive bacteria (32.95%) and 531 Gram negative bacteria (67.05%). Logistic regression model analysis showed that Glycerophospholipids, Sphingolipids and radiomics characteristics were risk factors for secondary asthma in children with LTRIs (P < 0.05). The AUC, sensitivity, and specificity of nomogram prediction for secondary asthma in children with LTRIs were 0.817(95CI: 0.760-0.874), 82.3%, and 76.6%, respectively; The AUC of decision tree prediction for secondary asthma in children with LTRIs is 0.926(95% CI: 0.869-0.983), with a sensitivity of 96.7% and a specificity of 87.8%.

Conclusion

LTRIs in children are mainly caused by Staphylococcus aureus, Streptococcus pneumoniae, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa; In addition, machine learning combined with multi-omics prediction models has shown good ability in predicting LTRIs combined with asthma, providing a non-invasive and effective method for clinical decision-making.

Sphingosine kinase 2 (SphK2) depletion alters redox metabolism and enhances inflammation in a diet-induced MASH mouse model

BACKGROUND

Sphingosine-1 phosphate (S1P) is a bioactive lipid molecule that modulates inflammation and hepatic lipid metabolism in MASLD, which affects 1 in 3 people and increases the risk of liver fibrosis and hepatic cancer. S1P can be generated by 2 isoforms of sphingosine kinase (SphK). SphK1 is well-studied in metabolic diseases. In contrast, SphK2 function is not well characterized. Both sphingolipid and redox metabolism dysregulation contribute to MASLD pathologic progression. While SphK2 localizes to both the nucleus and mitochondria, its specific role in early MASH is not well defined.

METHODS

This study examined SphK2 depletion effects on hepatic redox metabolism, mitochondrial function, and inflammation in a 16-week western diet plus sugar water (WDSW)-induced mouse model of early MASH.

RESULTS

WDSW-SphK2-/- mice exhibit increased hepatic lipid accumulation and hepatic redox dysregulation. In addition, mitochondria-localized cholesterol and S1P precursors were increased. We traced SphK2-/--mediated mitochondrial electron transport chain impairment to respiratory complex-IV and found that decreased mitochondrial redox metabolism coincided with increased oxidase gene expression and oxylipin production. Consistent with this relationship, we observed pronounced increases in hepatic inflammatory gene expression, prostaglandin accumulation, and innate immune homing in WDSW-SphK2-/- mice compared to WDSW-wild-type mice.

CONCLUSIONS

These studies suggest SphK2-derived S1P maintains hepatic redox metabolism and describe the potential consequences of SphK2 depletion on proinflammatory gene expression, lipid mediator production, and immune infiltration in MASH progression.

Chronic UVB exposure induces hepatic injury in mice: Mechanistic insights from integrated multi-omics

Chronic UVB exposure poses a significant threat to both skin and visceral health. In recent years, the adverse role of chronic UVB exposure in liver health has been suggested but not fully elucidated. This study aims to comprehensively investigate the effects of chronic UVB exposure on liver health in male SKH-1 hairless mice and clarify potential mechanisms through multi-omics approaches. The findings suggested that 10-week chronic skin exposure to UVB not only triggers hepatic inflammation and oxidative stress but also, more importantly, results in lipid metabolism abnormalities in the liver. Hepatic transcriptomic analysis revealed significant alterations in various signaling pathways and physiological processes associated with inflammation, oxidative stress, and lipid metabolism. Further lipidomic analysis illustrated significant changes in the metabolism of glycerolipids, sphingolipids, and glycerophospholipids in the liver following chronic UVB exposure. The 16S rRNA sequencing analysis indicated that chronic UVB exposure disrupts the structure and function of the microbiota. In search of potential mechanisms used by the microbiome to regulate the hepatic disease morphology, we filtered mouse fecal supernatants and cultured the supernatants with HepG2 cells. Fecal supernatant from UVB-exposed mice induced increased secretion of the inflammatory cytokine IL-8, accumulation of MDA, reduced SOD activity, and decreased lipid content in normal hepatic cells. In summary, skin chronic exposure to UVB induces multiple liver injuries and gut microbiota dysbiosis in mice and gut microbiota metabolites may be one of the contributing factors to hepatic injury caused by chronic UVB exposure. These discoveries deepen the comprehension of the health risks associated with chronic UVB exposure.

DHRS2-induced SPHK1 downregulation contributes to the cell growth inhibition by Trichothecin in colorectal carcinoma

BACKGROUND

Deregulation of lipid metabolism is one of the most prominent metabolic features in cancer. The activation of sphingolipid metabolic pathways affects the proliferation, invasion, angiogenesis, chemoresistance, and immune escape of tumors, including colorectal cancer (CRC). Dehydrogenase/reductase member 2 (DHRS2), which belongs to the short-chain dehydrogenase/reductase (SDR) family, has been reported to participate in the regulation of lipid metabolism and impact on cancer progression. Trichothecin (TCN) is a sesquiterpenoid metabolite originating from an endophytic fungus of the herbal plant Maytenus hookeri Loes. Studies have shown that TCN exerts a broad-spectrum antitumor activity.

METHODS

We evaluated the proliferative ability of CRC cells by CCK8 and colony formation assays. A metabolite profiling using liquid chromatography coupled with mass spectrometry (LC/MS) was adopted to identify the proximal metabolite changes linked to DHRS2 overexpression. RNA stability assay and RNA immunoprecipitation (RIP) experiments were applied to determine the post-transcriptional regulation of SPHK1 expression by DHRS2. We used flow cytometry to detect changes in cell cycle and cell apoptosis of CRC cells in the absence or presence of TCN.

RESULTS

We demonstrate that DHRS2 hampers the sphingosine kinases 1 (SPHK1)/sphingosine 1-phosphate (S1P) metabolic pathway to inhibit CRC cell growth. DHRS2 directly binds to SPHK1 mRNA to accelerate its degradation in a post-transcriptionally regulatory manner. Moreover, we illustrate that SPHK1 downregulation induced by DHRS2 contributes to TCN-induced growth inhibition of CRC.

CONCLUSIONS

The present study provides a mechanistic connection among metabolic enzymes, metabolites, and the malignant progression of CRC. Moreover, TCN could be developed as a potential pharmacological tool against CRC by the induction of DHRS2 and targeting SPHK1/S1P metabolic pathway.

Potential Vitamin E Signaling Mediators in Skeletal Muscle

Vitamin E (Vit E) deficiency studies underline the relevance of this vitamin in skeletal muscle (SkM) homeostasis. The knowledge of the effectors and modulators of Vit E action in SkM cells is limited, especially in aging and chronic diseases characterized by a decline in musculoskeletal health. Vit E comprises eight fat-soluble compounds grouped into tocopherols and tocotrienols, which share the basic chemical structure but show different biological properties and potentials to prevent diseases. Vit E has antioxidant and non-antioxidant activities and both favorable and adverse effects depending on the specific conditions and tissues. In this review, we focus on the actual knowledge of Vit E forms in SkM functions and new potential signaling effectors (i.e., bioactive sphingolipids and myokines). The possible advantages of Vit E supplementation in counteracting SkM dysfunctions in sarcopenia and under microgravity will also be discussed.

Untargeted and Targeted Lipidomics Unveil Dynamic Lipid Metabolism Alterations in Type 2 Diabetes

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a complex metabolic disorder with a growing body of evidence suggesting the central role of lipid metabolism in its pathogenesis. However, the dynamic changes in lipid metabolism across different stages of T2DM remain understudied.

OBJECTIVE

This study aimed to elucidate the temporal alterations in lipid metabolism in T2DM using an integrated lipidomics approach.

METHOD

Serum samples from 155 subjects were analyzed using LC-MS-based lipidomics, including untargeted and targeted approaches.

RESULTS

We identified significant alterations in 44 lipid metabolites in newly diagnosed T2DM patients and 29 in high-risk individuals, compared with healthy controls. Key metabolic pathways such as sphingomyelin, phosphatidylcholine, and sterol ester metabolism were disrupted, highlighting the involvement of insulin resistance and oxidative stress in T2DM progression. Moreover, 13 lipid metabolites exhibited diagnostic potential for T2DN, showing consistent trends of increase or decrease as the disease progressed.

CONCLUSION

Our findings underscore the importance of lipid metabolism in T2D development and identify potential lipid biomarkers for early diagnosis and monitoring of disease progression, which contribute to paving the way for novel therapeutic strategies.

A systematic evaluation of quenching, extraction and analysis procedures for metabolomics study of the mechanism of QYSLD intervention in A549 cells

The preparation of cellular metabolomics samples and how to achieve comprehensive coverage of different polar metabolites in cell samples in the analysis pose a challenge for cellular metabolomics. In this study, we optimized a metabolomics protocol based on ultra-high-performance liquid chromatography high-resolution mass spectrometry (UPLC/HRMS) for the extraction and detection of metabolites in A549 cells and exploration of the intervention effect of Qi-Yu-San-Long decoction (QYSLD) on A549 cells. The results indicate that the lowest level of ATP leakage was observed when A549 cells were quenched under liquid nitrogen. MeOH/chloroform/H2O (1:2:1) extraction yielded more chromatographic peaks and excellent reproducibility, and the relative extraction efficiency of most target metabolites was also high. And we optimized the chromatographic separation conditions in both HILIC and RPLC modes, enabling comprehensive detection and analysis of metabolites with varying polarities. Then, we applied the optimized method to UPLC-Q-TOF/MS-based metabolomics of A549 cells to study the mechanism of QYSLD intervention in non-small cell lung cancer (NSCLC). The CCK-8, EdU staining, and cell cycle assay showed that QYSLD inhibited the proliferation of A549 cells by interfering with the cell cycle and blocking them in the G1 phase. A total of 36 differential metabolites associated with the antitumor effects of QYSLD on NSCLC were identified, mainly involving nicotinate and nicotinamide metabolism, sphingolipid metabolism, and glycerophospholipid metabolism. And western blotting confirmed that the change in 1-methylnicotinamide levels after QYSLD intervention was associated with the inhibition of nicotinamide N-methyltransferase expression in A549 cells.

Integrated bulk and single-cell profiling characterize sphingolipid metabolism in pancreatic cancer

BACKGROUND

Abnormal sphingolipid metabolism (SM) is closely linked to the incidence of cancers. However, the role of SM in pancreatic cancer (PC) remains unclear. This study aims to explore the significance of SM in the prognosis, immune microenvironment, and treatment of PC.

METHODS

Single-cell and bulk transcriptome data of PC were acquired via TCGA and GEO databases. SM-related genes (SMRGs) were obtained via MSigDB database. Consensus clustering was utilized to construct SM-related molecular subtypes. LASSO and Cox regression were utilized to build SM-related prognostic signature. ESTIMATE and CIBERSORT algorithms were employed to assess the tumour immune microenvironment. OncoPredict package was used to predict drug sensitivity. CCK-8, scratch, and transwell experiments were performed to analyze the function of ANKRD22 in PC cell line PANC-1 and BxPC-3.

RESULTS

A total of 153 SMRGs were acquired, of which 48 were linked to PC patients' prognosis. Two SM-related subtypes (SMRGcluster A and B) were identified in PC. SMRGcluster A had a poorer outcome and more active SM process compared to SMRGcluster B. Immune analysis revealed that SMRGcluster B had higher immune and stromal scores and CD8 + T cell abundance, while SMRGcluster A had a higher tumour purity score and M0 macrophages and activated dendritic cell abundance. PC with SMRGcluster B was more susceptible to gemcitabine, paclitaxel, and oxaliplatin. Then SM-related prognostic model (including ANLN, ANKRD22, and DKK1) was built, which had a very good predictive performance. Single-cell analysis revealed that in PC microenvironment, macrophages, epithelial cells, and endothelial cells had relatively higher SM activity. ANKRD22, DKK1, and ANLN have relatively higher expression levels in epithelial cells. Cell subpopulations with high expression of ANKRD22, DKK1, and ANLN had more active SM activity. In vitro experiments showed that ANKRD22 knockdown can inhibit the proliferation, migration, and invasion of PC cells.

CONCLUSION

This study revealed the important significance of SM in PC and identified SM-associated molecular subtypes and prognostic model, which provided novel perspectives on the stratification, prognostic prediction, and precision treatment of PC patients.

Lipidomic perturbations of normal-weight adiposity phenotypes and their mediations on diet-adiposity associations

BACKGROUND & AIMS

Normal-weight obesity (NWO) and normal-weight central obesity (NWCO) have been linked to higher cardiometabolic risks, but their etiological bases and attributable dietary factors remain unclear. In this study we therefore aimed to identify lipidomic signatures and dietary factors related to NWO and NWCO and to explore the mediation associations of lipids in diet-adiposity associations.

METHODS

Using a high-coverage targeted lipidomic approach, we quantified 1245 serum lipids in participants with NWO (n = 150), NWCO (n = 150), or propensity-score-matched normal-weight controls (n = 150) based on the Regional Ethnic Cohort Study in Northwest China. Consumption frequency of 28 major food items was recorded using a food frequency questionnaire.

RESULTS

Profound lipidomic perturbations of NWCO relative to NWO were observed, and 249 (dominantly glycerolipids) as well as 48 (dominantly glycerophospholipids) lipids were exclusively associated with NWCO or NWO. Based on strong lipidomic signatures identified by a LASSO model, phospholipid biosynthesis was the top enriched pathway of NWCO, and sphingolipid metabolism was the top pathway of NWO. Remarkably, sphingolipids were positively associated with NWO and NWCO, but lyso-phosphatidylcholines were negatively associated with them. Rice, fruit juice, and carbonated drink intakes were positively associated with the risk of NWCO. Both global and individual lipidomic signatures, including SE(28:1_22:6) and HexCer(d18:1/20:1), mediated these diet-NWCO associations (mediation proportion: 15.92%-26.10%).

CONCLUSIONS

Differential lipidomic signatures were identified for overall and abdominal adiposity accumulation in normal-weight individuals, underlining their core mediation roles in dietary contributions to adiposity deposition.

Effect of Hepatic Lipid Overload on Accelerated Hepatocyte Proliferation Promoted by HGF Expression via the SphK1/S1PR2 Pathway in MCD-diet Mouse Partial Hepatectomy

Metabolic dysfunction-associated steatotic liver disease (MASLD) is becoming a major health problem worldwide. Liver regeneration is crucial for restoring liver function, and is regulated by extraordinary complex process, involving numerous factors under both physiologic and pathologic conditions. Sphingosine-1-phosphate (S1P), a bioactive sphingolipid synthesized by sphingosine kinase 1 (SphK1), plays an important role in liver function through S1P receptors (S1PRs)-expressing cells. In this study, we investigated the effect of lipid overload on hepatocyte proliferation in a mouse hepatic steatosis model induced by feeding a methionine- and choline-deficient (MCD) diet. After 50% partial hepatectomy (PHx), liver tissues were sampled at various timepoints and then analyzed by immunohistochemistry, oil Red-O staining, quantitative-polymerase chain reaction (qPCR), and flow cytometry. In mice fed the MCD-diet, significantly exacerbated hepatic steatosis and accelerated liver regeneration were observed. After PHx, hepatocyte proliferation peaked at 48 and 36 hr in the liver of chow- and MCD-diet fed mice, respectively. By contrast, increased expression of S1PR2 was observed in hepatic neutrophils and macrophages of MCD-diet fed mice. Flow cytometry and qPCR experiments demonstrated that levels of HGF and FGF2 released by neutrophils and macrophages were significantly higher in MCD-diet fed mice. In conclusion, hepatic lipid overload recruits Kupffer cells and neutrophils that release HGF and FGF2 via SphK1/S1PR2 activation to accelerate hepatocyte proliferation.

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.

Role of Sphingosine-1-Phosphate Signaling Pathway in Pancreatic Diseases

Sphingosine-1-phosphate (S1P) is a sphingolipid metabolic product produced via the phosphorylation of sphingosine by sphingosine kinases (SPHKs), serving as a powerful modulator of various cellular processes through its interaction with S1P receptors (S1PRs). Currently, this incompletely understood mechanism in pancreatic diseases including pancreatitis and pancreatic cancer, largely limits therapeutic options for these disorders. Recent evidence indicates that S1P significantly contributes to pancreatic diseases by modulating inflammation, promoting pyroptosis in pancreatic acinar cells, regulating the activation of pancreatic stellate cells, and affecting organelle functions in pancreatic cancer cells. Nevertheless, no review has encapsulated these advancements. Thus, this review compiles information about the involvement of S1P signaling in exocrine pancreatic disorders, including acute pancreatitis, chronic pancreatitis, and pancreatic cancer, as well as prospective treatment strategies to target S1P signaling for these conditions. The insights presented here possess the potential to offer valuable guidance for the implementation of therapies targeting S1P signaling in various pancreatic diseases.

Optical control of sphingolipid biosynthesis using photoswitchable sphingosines

Sphingolipid metabolism comprises a complex interconnected web of enzymes, metabolites and modes of regulation that influence a wide range of cellular and physiological processes. Deciphering the biological relevance of this network is challenging as numerous intermediates of sphingolipid metabolism are short-lived molecules with often opposing biological activities. Here, we introduce clickable, azobenzene-containing sphingosines, termed caSphs, as light-sensitive substrates for sphingolipid biosynthesis. Photo-isomerization of the azobenzene moiety enables reversible switching between a straight trans- and curved cis-form of the lipid's hydrocarbon tail. Combining in vitro enzyme assays with metabolic labeling studies, we demonstrate that trans-to-cis isomerization of caSphs profoundly stimulates their metabolic conversion by ceramide synthases and downstream sphingomyelin synthases. These light-induced changes in sphingolipid production rates are acute, reversible, and can be implemented with great efficiency in living cells. Our findings establish caSphs as versatile tools with unprecedented opportunities to manipulate sphingolipid biosynthesis and function with the spatiotemporal precision of light.

Unveiling Lipidomic Alterations in Metabolic Syndrome: A Study of Plasma, Liver, and Adipose Tissues in a Dietary-Induced Rat Model

Metabolic syndrome (MetS) is a complex condition characterized by fat accumulation, dyslipidemia, impaired glucose control and hypertension. In this study, rats were fed a high-fat high-fructose (HFF) diet in order to develop MetS. After ten weeks, the dietary-induced MetS was confirmed by higher body fat percentage, lower HDL-cholesterol and increased blood pressure in the HFF-fed rats compared to the normal-fed control animals. However, the effect of MetS development on the lipidomic signature of the dietary-challenged rats remains to be investigated. To reveal the contribution of specific lipids to the development of MetS, the lipid profiling of rat tissues particularly susceptible to MetS was performed using untargeted UHPLC-QTOF-MS/MS lipidomic analysis. A total of 37 lipid species (mainly phospholipids, triglycerides, sphingolipids, cholesterol esters, and diglycerides) in plasma, 43 lipid species in liver, and 11 lipid species in adipose tissue were identified as dysregulated between the control and MetS groups. Changes in the lipid signature of selected tissues additionally revealed systemic changes in the dietary-induced rat model of MetS.

High temperature ameliorates high-fat diet-induced obesity by promoting ceramide breakdown in skeletal muscle tissue

Obesity is considered an epidemic often accompanied by insulin resistance (IR). Heat treatment (HT) has been shown to prevent high-fat diet-induced IR in skeletal muscle, but the underlying mechanisms are poorly understood. In this study, we discovered that high temperature alleviated the hallmarks of obesity by promoting glycogen synthesis and lowering blood glucose levels in skeletal muscle tissue (SMT). Additionally, HT maintained the decay phase of heat shock factor 1 (HSF1), leading to the activation of gene expression of heat shock proteins (HSPs), which contributed to the alleviation of IR in SMT of diet-induced obese (DIO) mice. Metabolomics and lipidomics analyses showed that HT promoted ceramide (Cer) breakdown, resulting in an elevation of both sphingomyelin (SM) and sphingosine, which further contributed to the amelioration of IR in SMT of DIO mice. Importantly, the increase in sphingosine was attributed to the heightened expression of the acid ceramidase N-acylsphingosine amidohydrolase 1 (ASAH1), and the inhibition of ASAH1 attenuated HT-relieved IR in SMT of DIO mice. Surprisingly, high temperature increased the composition of Cer and cholesteryl ester in lipid droplets of skeletal muscle cells. This not only helped alleviate IR but also prevented lipotoxicity in SMT of DIO mice. These findings revealed a previously unknown connection between a high-temperature environment and sphingolipid metabolism in obesity, suggesting that high temperature can improve IR by promoting Cer catabolism in SMT of obese mice.

The sphingosine kinase 2 inhibitors ABC294640 and K145 elevate (dihydro)sphingosine 1-phosphate levels in various cells

Sphingosine kinases (SphKs), enzymes that produce the bioactive lipids dihydrosphingosine 1-phosphate (dhS1P) and sphingosine 1-phosphate (S1P), are associated with various diseases, including cancer and infections. For this reason, a number of SphK inhibitors have been developed. Although off-target effects have been described for selected agents, SphK inhibitors are mostly used in research without monitoring the effects on the sphingolipidome. We have now investigated the effects of seven commonly used SphK inhibitors (5c, ABC294640 (opaganib), N,N-dimethylsphingosine, K145, PF-543, SLM6031434, and SKI-II) on profiles of selected sphingolipids in Chang, HepG2, and human umbilical vein endothelial cells. While we observed the expected (dh)S1P reduction for N,N-dimethylsphingosine, PF-543, SKI-II, and SLM6031434, 5c showed hardly any effect. Remarkably, for K145 and ABC294640, both reported to be specific for SphK2, we observed dose-dependent strong increases in dhS1P and S1P across cell lines. Compensatory effects of SphK1 could be excluded, as this observation was also made in SphK1-deficient HK-2 cells. Furthermore, we observed effects on dihydroceramide desaturase activity for all inhibitors tested, as has been previously noted for ABC294640 and SKI-II. In additional mechanistic studies, we investigated the massive increase of dhS1P and S1P after short-term cell treatment with ABC294640 and K145 in more detail. We found that both compounds affect sphingolipid de novo synthesis, with 3-ketodihydrosphingosine reductase and dihydroceramide desaturase as their targets. Our study indicates that none of the seven SphK inhibitors tested was free of unexpected on-target and/or off-target effects. Therefore, it is important to monitor cellular sphingolipid profiles when SphK inhibitors are used in mechanistic studies.