Role of Ceramidases in Sphingolipid Metabolism and Human Diseases

Sphingolipid metabolism and regulated cell death in malignant melanoma

Malignant melanoma (MM) is a highly invasive and therapeutically resistant skin malignancy, posing a significant clinical challenge in its treatment. Programmed cell death plays a crucial role in the occurrence and progression of MM. Sphingolipids (SP), as a class of bioactive lipids, may be associated with many kinds of diseases. SPs regulate various forms of programmed cell death in tumors, including apoptosis, necroptosis, ferroptosis, and more. This review will delve into the mechanisms by which different types of SPs modulate various forms of programmed cell death in MM, such as their regulation of cell membrane permeability and signaling pathways, and how they influence the survival and death fate of MM cells. An in-depth exploration of the role of SPs in programmed cell death in MM aids in unraveling the molecular mechanisms of melanoma development and holds significant importance in developing novel therapeutic strategies.

Integrated metabolome and microbiome strategy reveals the therapeutic effect of nervonic acid on Alzheimer's disease rats

Alzheimer's disease (AD) is a complex neurodegenerative disease. Nervonic acid is a component of breast milk and is also found in fish oil and specific vegetable oils. Studies have shown that nervonic acid is essential for the development of the human nervous system. In this study, Morris water maze (MWM) test and pathological analysis showed that nervonic acid could improve cognitive deficits and brain nerve damage in AD rats. Then, through sequencing, we found that nervonic acid increased the abundance of beneficial bacteria such as Lactobacillus and Bacteroides, and decreased the abundance of Pseudomonadaceae_Pseudomonas. Not only that, nervonic acid also regulates the production of short-chain fatty acids (SCFA) and the levels of 29 fecal metabolites, and affects the metabolism of linoleic acid, α-linolenic acid, arachidonic acid, and sphingolipid. Finally, we verified the regulatory effect of nervonic acid on metabolic enzyme activity.

The role of ACER2 in intestinal sphingolipid metabolism and gastrointestinal cancers

Sphingolipids, particularly sphingosine-1-phosphate (S1P), are bioactive lipids involved in regulating cellular processes such as proliferation, apoptosis, inflammation, and tumor progression. Alkaline ceramidase 2 (ACER2) plays a critical role in sphingolipid metabolism by catalyzing the hydrolysis of ceramide to sphingosine, which is subsequently converted to S1P. Dysregulation of ACER2 has been implicated in various gastrointestinal cancers, including colorectal cancer, gastric cancer, and hepatocellular carcinoma. ACER2-mediated sphingolipid signaling, particularly through the SphK/S1P pathway, influences cancer development by modulating immune responses, inflammation, and the balance between cell survival and death. This review examines the physiological functions of ACER2, and its role in sphingolipid metabolism, and its contribution to the pathogenesis of gastrointestinal cancers. Understanding the mechanisms by which ACER2 regulates tumor progression and immune modulation may open new avenues for targeted therapies in gastrointestinal malignancies.

A New Strategy to Inhibit Scar Formation by Accelerating Normal Healing Using Silicate Bioactive Materials

Inspired by the scar-free wound healing in infants, an anti-scar strategy is proposed by accelerating wound healing using silicate bioactive materials. Bioglass/alginate composite hydrogels are applied, which significantly inhibit scar formation in rabbit ear scar models. The underlining mechanisms include stimulation of Integrin Subunit Alpha 2 expression in dermal fibroblasts to accelerate wound healing, and induction of apoptosis of hypertrophic scar fibroblasts by directly stimulating the N-Acylsphingosine Amidohydrolase 2 expression in hypertrophic scar fibroblasts, and indirectly upregulating the secretion of Cathepsin K in dermal fibroblasts. Considering specific functions of the bioactive silicate materials, two scar treatment regimes are tested. For severe scars, a regenerative intervention is applied by surgical removal of the scar followed by the treatment with bioactive hydrogels to reduce the formation of scars by activating dermal fibroblasts. For mild scars, the bioactive dressing is applied on the formed scar and reduces scar by inducing scar fibroblasts apoptosis.

MCL restrained ROS/AKT/ASAH1 pathway to therapy tamoxifen resistance breast cancer by stabilizing NRF2

Tamoxifen resistance is a common and difficult problem in the clinical treatment of breast cancer (BC). As a novel antitumor agent, Micheliolide (MCL) has shown a better therapeutic effect on tumours; however, little is known about MCL and its role in BC therapy. With tamoxifen stimulation, drug-resistant BC cells MCF7TAMR and T47DTAMR obtained a high oxidative status and Amidohydrolase 1 (ASAH1) was abnormally activated. The inhibition of ASAH1 rescued the sensitivity of resistant cells to tamoxifen. We found that MCL inhibited the expression of ASAH1 and cell proliferation, especially in MCF7TAMR and T47DTAMR cells. The high oxidative stress status of resistant cells stimulated the expression of ASAH1 by positively regulating AKT, which was restrained by MCL. MCL activated NRF2 by directly binding to KEAP1 and promoting the antioxidant level of tamoxifen-resistant (TAMR) cells. In addition, ACT001, the prodrug of MCL, significantly inhibited the tumour growth of TAMR cells in preclinical xenograft tumour models. In conclusion, ASAH1 mediates tamoxifen resistance in ER-positive BC cells. MCL could activate the cellular antioxidant system via NRF2/KEAP1 and inhibit ASAH1 expression through the ROS/AKT signalling pathway, thus suppressing cell proliferation. MCL could be used as a potential treatment for TAMR-BC.

Atractylodin modulates ASAH3L to improve galactose metabolism and inflammation to alleviate acute lung injury

Acute lung injury (ALI) is a lung disease characterized by an excessive inflammatory response and damage to lung epithelial cells. Atractylodin (ATL) has good anti-inflammatory activity and protects the integrity of the epithelial cell barrier. However, the efficacy of ATL in the treatment of ALI and its mechanism is unclear. We investigated the efficacy of ATL in treating ALI and explored its targets and mechanisms. The results showed that ATL significantly reduced the wet-dry ratio of lungs of rats with ALI, improved the pathological changes, and lowered the expression of the inflammatory factors. Combined metabolomic and transcriptomic analyses showed that ATL can reduce inflammation by inhibiting and activating the HIF-1 signaling pathway and modulating ASAH3L to improve galactose metabolism, thereby alleviating ALI. In conclusion, ATL may be a potential drug for the treatment of acute lung injury.

Immunofluorescence-Verified Sphingolipid Signatures Indicate Improved Prognosis in Liver Cancer Patients

Background: Hepatocellular carcinoma (HCC) is a highly heterogeneous malignancy, with its pathogenesis involving a complex interplay of molecular mechanisms, including cell cycle dysregulation, evasion of apoptosis, enhanced angiogenesis, and aberrant immune responses. Precision medicine approaches that target specific molecular subtypes through multi-omics integration hold promise for improving patient survival. Among the various molecular players, sphingolipids have emerged as pivotal regulators of tumor growth and apoptosis, positioning them as key targets in the search for novel anticancer therapies. Methods: To identify critical genes involved in sphingolipid metabolism (SM), we employed the AUCell algorithm and correlation analysis in conjunction with scRNA-seq data. A robust prognostic risk model was developed using Cox proportional hazards and Lasso regression, and its predictive performance was validated using an independent cohort from the International Cancer Genome Consortium (ICGC). The model's evaluation also incorporated analyses of the tumor microenvironment (TME), immunotherapy responses, mutational landscape, and pathway enrichment across different risk strata. Finally, we conducted multiplex immunofluorescence assays to investigate the functional role of ZC3HAV1 in HCC. Results: Our analysis yielded a 9-gene signature risk model with strong prognostic capabilities, effectively stratifying HCC patients into high- and low-risk groups, with significant differences in survival outcomes. Notably, the model revealed distinct variations in the immune microenvironment and responsiveness to immunotherapy between the risk groups. Further experimental validation identified ZC3HAV1 as a key gene, with multiplex immunofluorescence suggesting its involvement in promoting malignant progression in HCC through modulation of the epithelial-mesenchymal transition (EMT). Conclusion: This sphingolipid metabolism-based prognostic model is not only predictive of survival in HCC but also indicative of immunotherapy efficacy in certain patient subsets. Our findings underscore the crucial role of sphingolipid metabolism in shaping the immune microenvironment, offering new avenues for targeted therapeutic interventions.

Deciphering the role of sphingolipid metabolism in the immune microenvironment and prognosis of esophageal cancer via single-cell sequencing and bulk data analysis

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) stands as a significant global health challenge, distinguished by its aggressive progression from the esophageal epithelium. Central to this malignancy is sphingolipid metabolism, a critical pathway that governs key cellular processes, including apoptosis and immune regulation, thereby influencing tumor behavior. The advent of single-cell and transcriptome sequencing technologies has catalyzed significant advancements in oncology research, offering unprecedented insights into the molecular underpinnings of cancer.

METHODS

We explored sphingolipid metabolism-related genes in ESCC using scRNA-seq data from GEO and transcriptome data from TCGA. We assessed 97 genes in epithelial cells with AUCell, UCell, and singscore algorithms, followed by bulk RNA-seq and differential analysis to identify prognosis-related genes. Immune infiltration and potential immunotherapeutic strategies were also investigated, and tumor gene mutations and drug treatment strategies were analyzed.

RESULT

Our study identified distinct gene expression patterns, highlighting ARSD, CTSA, DEGS1, and PPTQ's roles in later cellular stages. We identified seven independent prognostic genes and created a precise nomogram for prognosis.

CONCLUSION

This study integrates single-cell and transcriptomic data to provide a reliable prognostic model associated with sphingolipid metabolism and to inform immunotherapy and pharmacotherapy for ESCC at the genetic level. The findings have significant implications for precision therapy in esophageal cancer.

Gut microbiota metabolites: potential therapeutic targets for Alzheimer's disease?

Background

Alzheimer's disease (AD) is a neurodegenerative disease characterized by progressive decline in cognitive function, which significantly increases pain and social burden. However, few therapeutic interventions are effective in preventing or mitigating the progression of AD. An increasing number of recent studies support the hypothesis that the gut microbiome and its metabolites may be associated with upstream regulators of AD pathology.

Methods

In this review, we comprehensively explore the potential mechanisms and currently available interventions targeting the microbiome for the improvement of AD. Our discussion is structured around modern research advancements in AD, the bidirectional communication between the gut and brain, the multi-target regulatory effects of microbial metabolites on AD, and therapeutic strategies aimed at modulating gut microbiota to manage AD.

Results

The gut microbiota plays a crucial role in the pathogenesis of AD through continuous bidirectional communication via the microbiota-gut-brain axis. Among these, microbial metabolites such as lipids, amino acids, bile acids and neurotransmitters, especially sphingolipids and phospholipids, may serve as central components of the gut-brain axis, regulating AD-related pathogenic mechanisms including β-amyloid metabolism, Tau protein phosphorylation, and neuroinflammation. Additionally, interventions such as probiotic administration, fecal microbiota transplantation, and antibiotic use have also provided evidence supporting the association between gut microbiota and AD. At the same time, we propose an innovative strategy for treating AD: a healthy lifestyle combined with targeted probiotics and other potential therapeutic interventions, aiming to restore intestinal ecology and microbiota balance.

Conclusion

Despite previous efforts, the molecular mechanisms by which gut microbes act on AD have yet to be fully described. However, intestinal microorganisms may become an essential target for connecting the gut-brain axis and improving the symptoms of AD. At the same time, it requires joint exploration by multiple centers and multiple disciplines.

Modulation of oxidative stress and apoptosis by alteration of bioactive lipids in the pancreas, and effect of zinc chelation in a rat model of Alzheimer's disease

INTRODUCTION

Increasing epidemiological evidence highlights the association between systemic insulin resistance and Alzheimer's disease (AD). It is known that peripheral insulin resistance in the early stages of AD precedes and is a precursor to amyloid-β (Aβ) deposition. Although it is known that improving the CNS insulin sensitivity of AD patients is an important therapeutic goal and that the majority of insulin in the brain comes from the periphery, there has been little attention to the changes that occur in the pancreatic tissue of AD patients. Therefore, it is crucial to elucidate the mechanisms affecting insulin resistance in pancreatic tissue in AD. It is known that zinc (Zn2+) chelation is effective in reducing peripheral insulin resistance, cell apoptosis, cell death, and oxidative stress.

OBJECTIVE

It was aimed to determine the changes in bioactive lipids, amylin (AIPP), oxidative stress and apoptosis in pancreatic cells in the early stages of Alzheimer's disease. The main aim is to reveal the therapeutic effect of the Cyclo-Z agent on these changes seen in the pancreas due to AD disease.

METHODS

AD and ADC rats were intracerebroventricular (i.c.v.) Aβ1-42 oligomers. Cyclo-Z gavage was applied to ADC and SHC rats for 21 days. First of all, the effects of AIPP, bioactive ceramides, apoptosis and oxidative stress on the pancreatic tissue of AD group rats were evaluated. Then, the effect of Cyclo-Z treatment on these was examined. ELISA kit was used in biochemical analyses.

RESULTS

AIPP and ceramide (CER) levels and CER/ sphingosine-1 phosphate (S1P) ratio were increased in the pancreatic tissue of AD rats. It also increased the level of CER kinase (CERK), which is known to increase the concentration of CER 1-phosphate (C1P), which is known to be toxic to cells in the presence of excessive CER concentration. Due to the increase in CER level, it was observed that apoptosis and oxidative stress increased in the pancreatic cells of AD group rats.

CONCLUSION

Cyclo-Z, which has Zn2+ chelating properties, reduced AD model rats' AIPP level and oxidative stress and could prevent pancreatic apoptosis. Similar therapeutic effects were not observed in the pancreatic tissue of Cyclo-Z administered to the SH group. For this reason, it is thought that Cyclo-Z agent may have a therapeutic effect on the peripheral hyperinsulinemia observed in the early stages of AD disease and the resulting low amount of insulin transported to the brain, by protecting pancreatic cells from apoptosis and oxidative stress by regulating their bioactive metabolites.

Ceramides-Emerging Biomarkers of Lipotoxicity in Obesity, Diabetes, Cardiovascular Diseases, and Inflammation

Abnormalities in lipid homeostasis have been associated with many human diseases, and the interrelation between lipotoxicity and cellular dysfunction has received significant attention in the past two decades. Ceramides (Cers) are bioactive lipid molecules that serve as precursors of all complex sphingolipids. Besides their function as structural components in cell and mitochondrial membranes, Cers play a significant role as key mediators in cell metabolism and are involved in numerous cellular processes, such as proliferation, differentiation, inflammation, and induction of apoptosis. The accumulation of various ceramides in tissues causes metabolic and cellular disturbances. Recent studies suggest that Cer lipotoxicity has an important role in obesity, metabolic syndrome, type 2 diabetes, atherosclerosis, and cardiovascular diseases (CVDs). In humans, elevated plasma ceramide levels are associated with insulin resistance and impaired cardiovascular and metabolic health. In this review, we summarize the role of ceramides as key mediators of lipotoxicity in obesity, diabetes, cardiovascular diseases, and inflammation and their potential as a promising diagnostic tool.

Glycolipid Metabolic Disorders, Metainflammation, Oxidative Stress, and Cardiovascular Diseases: Unraveling Pathways

Glycolipid metabolic disorders (GLMDs) are various metabolic disorders resulting from dysregulation in glycolipid levels, consequently leading to an increased risk of obesity, diabetes, liver dysfunction, neuromuscular complications, and cardiorenal vascular diseases (CRVDs). In patients with GLMDs, excess caloric intake and a lack of physical activity may contribute to oxidative stress (OxS) and systemic inflammation. This study aimed to review the connection between GLMD, OxS, metainflammation, and the onset of CRVD. GLMD is due to various metabolic disorders causing dysfunction in the synthesis, breakdown, and absorption of glucose and lipids in the body, resulting in excessive ectopic accumulation of these molecules. This is mainly due to neuroendocrine dysregulation, insulin resistance, OxS, and metainflammation. In GLMD, many inflammatory markers and defense cells play a vital role in related tissues and organs, such as blood vessels, pancreatic islets, the liver, muscle, the kidneys, and adipocytes, promoting inflammatory lesions that affect various interconnected organs through their signaling pathways. Advanced glycation end products, ATP-binding cassette transporter 1, Glucagon-like peptide-1, Toll-like receptor-4, and sphingosine-1-phosphate (S1P) play a crucial role in GLMD since they are related to glucolipid metabolism. The consequences of this is system organ damage and increased morbidity and mortality.

Polyploid giant cancer cells: origin, possible pathways of formation, characteristics, and mechanisms of regulation

Polyploid giant cancer cells (PGCCs) are characterized by the presence of either a single enlarged nucleus or multiple nuclei and are closely associated with tumor progression and treatment resistance. These cells contribute significantly to cellular heterogeneity and can arise from various stressors, including radiation, chemotherapy, hypoxia, and environmental factors. The formation of PGCCs can occur through mechanisms such as endoreplication, cell fusion, cytokinesis failure, mitotic slippage, or cell cannibalism. Notably, PGCCs exhibit traits similar to cancer stem cells (CSCs) and generate highly invasive progeny through asymmetric division. The presence of PGCCs and their progeny is pivotal in conferring resistance to chemotherapy and radiation, as well as facilitating tumor recurrence and metastasis. This review provides a comprehensive analysis of the origins, potential formation mechanisms, stressors, unique characteristics, and regulatory pathways of PGCCs, alongside therapeutic strategies targeting these cells. The objective is to enhance the understanding of PGCC initiation and progression, offering novel insights into tumor biology.

Contribution of sphingomyelin phosphodiesterase acid-like 3B to the proliferation, migration, and invasion of ovarian cancer cells

Background

Cancer has the highest mortality rate among gynecological cancers and poses a serious threat to women's lives. However, the treatment options for ovarian cancer are still limited, and exploring effective targeted biomarkers is particularly important for predicting and treating ovarian cancer. Therefore, it is necessary to explore the molecular mechanisms of the occurrence and development of ovarian cancer.

Methods

This investigation encompassed the analysis of gene expression profiles, measurement of transcription levels of potential target genes in peripheral blood samples from ovarian cancer patients and characterization of the ovarian cancer-related secretory protein sphingomyelin phosphodiesterase acid-like 3B (SMPDL3B). Through bioinformatics analysis, potential target genes were identified, and their association with overall survival (OS) and progression-free survival (PFS) in ovarian cancer patients was assessed utilizing relevant databases. Subsequently, differences in target gene expression in ovarian cancer tissue samples were validated through protein blotting and quantitative real-time PCR (qRT-qPCR). Cell proliferation assays using the cell count kit-8 (CCK-8) method, as well as transwell chamber assay and pre coated matrix gel chamber assay were employed to elucidate the role of SMPDL3B in ovarian cancer cell migration and invasion.

Results

This study revealed a substantial upregulation of SMPDL3B in the serum of ovarian cancer patients, correlating with an unfavorable prognosis. High SMPDL3B expression was linked not only to increased proliferation of ovarian cancer cells, but also enhanced migration and invasion. Remarkably, the knockdown the human alkaline ceramidase 2 (ACER2) gene in cancer cells with heightened SMPDL3B expression significantly inhibited cell proliferation, migration, and invasion induced by SMPDL3B activation (P<0.05), highlighting the functional interplay between ACER2 and SMPDL3B in ovarian cancer.

Conclusions

In summary, this study proposes SMPDL3B as a prognostic marker for ovarian cancer, with implications for potential therapeutic intervention targeting the ACER2-SMPDL3B axis.

Targeting IDH1-Mutated Oligodendroglioma with Acid Ceramidase Inhibitors

Oligodendroglioma is genetically defined as a tumor harboring isocitrate dehydrogenase 1 or 2 mutations (IDH1 mut /IDH2 mut ) and 1p/19q co-deletions. Previously, we reported that in IDH1 mut gliomas, D-2HG, the product of IDH1 mutant enzyme produces an increase in monounsaturated fatty acid levels that are incorporated into ceramides, tilting the S1P-to-ceramide rheostat toward apoptosis. Herein, we exploited this imbalance to further induce and IDH mut -specific glioma cell death. We report for the first time that the inhibition of acid ceramidase (AC) induces apoptosis and provides a benefit in mice survival in IDH1 mut oligodendroglioma. We demonstrated an IDH1 mut -specific cytotoxicity of SABRAC, an irreversible inhibitor of AC, in patient-derived oligodendroglioma cells. Exploring the mechanism of action of this drug, we found that SABRAC activates both extrinsic and intrinsic apoptosis in an ER stress-independent manner, pointing to a direct action of AC-related ceramides in mitochondria permeability. The activation of apoptosis detected under SABRAC treatment was associated with up to 30-fold increase in some ceramide levels and its derivatives from the salvage pathway. We propose that this novel enzyme, AC, has the potential to increase survival in oligodendroglioma with IDH1 mut and should be considered in the future.

Gut microbiota-host lipid crosstalk in Alzheimer's disease: implications for disease progression and therapeutics

Trillions of intestinal bacteria in the human body undergo dynamic transformations in response to physiological and pathological changes. Alterations in their composition and metabolites collectively contribute to the progression of Alzheimer's disease. The role of gut microbiota in Alzheimer's disease is diverse and complex, evidence suggests lipid metabolism may be one of the potential pathways. However, the mechanisms that gut microbiota mediate lipid metabolism in Alzheimer's disease pathology remain unclear, necessitating further investigation for clarification. This review highlights the current understanding of how gut microbiota disrupts lipid metabolism and discusses the implications of these discoveries in guiding strategies for the prevention or treatment of Alzheimer's disease based on existing data.

Alterations in urinary ceramides, sphingoid bases, and their phosphates among patients with kidney disease

Background

To avoid an invasive renal biopsy, noninvasive laboratory testing for the differential diagnosis of kidney diseases is a desirable goal. As sphingolipids are demonstrated to be involved in the pathogenesis of various kidney diseases, we investigated the possible usefulness of the simultaneous measurement of urinary sphingolipids for differentiating kidney diseases.

Materials and methods

Residual urine specimens were collected from patients who had been clinically diagnosed with chronic glomerulonephritis (CGN), diabetic mellitus (DM), systemic lupus erythematosus (SLE), and arterial hypertension (AH). The urinary sphingolipids-CERs C16:0, C18:0, C18:1, C20:0, C22:0, and C24:0; sphingosine [Sph]; dihydrosphingosine; sphingosine 1-phosphate [S1P]; and dihydroS1P [dhS1P]-were measured by liquid chromatography-tandem mass spectrometry. Based on the results, machine learning models were constructed to differentiate the various kidney diseases.

Results

The urinary S1P was higher in patients with DM than in other participants (P < 0.05), whereas dhS1P was lower in the CGN and AH groups compared with control participants (P < 0.05). Sph and dhSph were higher in patients with CGN, AH, and SLE than in those with control participants (P < 0.05). The urinary CERs were significantly higher in patients with CGN, AH, and SLE than in those with control participants (P < 0.05). As a results of constructing a machine learning model discriminating kidney diseases, the resulting diagnostic accuracy and precision were improved from 94.03% and 66.96% to 96.10% and 78.26% respectively, when the urinary CERs, Sph, dhSph, S1P, dhS1P, and their ratios were added to the models.

Conclusion

The urinary CERs, sphingoid bases, and their phosphates show alterations among kidney diseases, suggesting their potential involvement in the development of kidney injury.

Expression of Ceramide Synthases in Mice and Their Roles in Regulating Acyl-Chain Sphingolipids: A Framework for Baseline Levels and Future Implications in Aging and Disease

Sphingolipids are an important class of lipids present in all eukaryotic cells that regulate critical cellular processes. Disturbances in sphingolipid homeostasis have been linked to several diseases in humans. Ceramides are central in sphingolipid metabolism and are largely synthesized by six ceramide synthase (CerS) isoforms (CerS1-6), each with a preference for different fatty acyl chain lengths. Although the tissue distribution of CerS mRNA expression in humans and the roles of CerS isoforms in synthesizing ceramides with different acyl chain lengths are known, it is unknown how CerS expression dictates ceramides and downstream metabolites within tissues. In this study, we analyzed sphingolipid levels and CerS mRNA expression in 3-month-old C57BL/6J mouse brain, heart, kidney, liver, lung, and skeletal muscle. The results showed that CerS expression and sphingolipid species abundance varied by tissue and that CerS expression was a predictor of ceramide species within tissues. Interestingly, although CerS expression was not predictive of complex sphingolipid species within all tissues, composite scores for CerSs contributions to total sphingolipids measured in each tissue correlated to CerS expression. Lastly, we determined that the most abundant ceramide species in mouse tissues aligned with CerS mRNA expression in corresponding human tissues (based on chain length preference), suggesting that mice are relevant preclinical models for ceramide and sphingolipid research. SIGNIFICANCE STATEMENT: The current study demonstrates that ceramide synthase (CerS) expression in specific tissues correlates not only with ceramide species but contributes to the generation of complex sphingolipids as well. As many of the CerSs and/or specific ceramide species have been implicated in disease, these studies suggest the potential for CerSs as therapeutic targets and the use of sphingolipid species as diagnostics in specific tissues.

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.

Application of SWATH Mass Spectrometry and Machine Learning in the Diagnosis of Inflammatory Bowel Disease Based on the Stool Proteome

Inflammatory bowel disease (IBD) flare-ups exhibit symptoms that are similar to other diseases and conditions, making diagnosis and treatment complicated. Currently, the gold standard for diagnosing and monitoring IBD is colonoscopy and biopsy, which are invasive and uncomfortable procedures, and the fecal calprotectin test, which is not sufficiently accurate. Therefore, it is necessary to develop an alternative method. In this study, our aim was to provide proof of concept for the application of Sequential Window Acquisition of All Theoretical Mass Spectra-Mass spectrometry (SWATH-MS) and machine learning to develop a non-invasive and accurate predictive model using the stool proteome to distinguish between active IBD patients and symptomatic non-IBD patients. Proteome profiles of 123 samples were obtained and data processing procedures were optimized to select an appropriate pipeline. The differentially abundant analysis identified 48 proteins. Utilizing correlation-based feature selection (Cfs), 7 proteins were selected for proceeding steps. To identify the most appropriate predictive machine learning model, five of the most popular methods, including support vector machines (SVMs), random forests, logistic regression, naive Bayes, and k-nearest neighbors (KNN), were assessed. The generated model was validated by implementing the algorithm on 45 prospective unseen datasets; the results showed a sensitivity of 96% and a specificity of 76%, indicating its performance. In conclusion, this study illustrates the effectiveness of utilizing the stool proteome obtained through SWATH-MS in accurately diagnosing active IBD via a machine learning model.

A Systematic Review of Lipid-Focused Cardiovascular Disease Research: Trends and Opportunities

Lipids are important modifiers of protein function, particularly as parts of lipoproteins, which transport lipophilic substances and mediate cellular uptake of circulating lipids. As such, lipids are of particular interest as blood biological markers for cardiovascular disease (CVD) as well as for conditions linked to CVD such as atherosclerosis, diabetes mellitus, obesity and dietary states. Notably, lipid research is particularly well developed in the context of CVD because of the relevance and multiple causes and risk factors of CVD. The advent of methods for high-throughput screening of biological molecules has recently resulted in the generation of lipidomic profiles that allow monitoring of lipid compositions in biological samples in an untargeted manner. These and other earlier advances in biomedical research have shaped the knowledge we have about lipids in CVD. To evaluate the knowledge acquired on the multiple biological functions of lipids in CVD and the trends in their research, we collected a dataset of references from the PubMed database of biomedical literature focused on plasma lipids and CVD in human and mouse. Using annotations from these records, we were able to categorize significant associations between lipids and particular types of research approaches, distinguish non-biological lipids used as markers, identify differential research between human and mouse models, and detect the increasingly mechanistic nature of the results in this field. Using known associations between lipids and proteins that metabolize or transport them, we constructed a comprehensive lipid-protein network, which we used to highlight proteins strongly connected to lipids found in the CVD-lipid literature. Our approach points to a series of proteins for which lipid-focused research would bring insights into CVD, including Prostaglandin G/H synthase 2 (PTGS2, a.k.a. COX2) and Acylglycerol kinase (AGK). In this review, we summarize our findings, putting them in a historical perspective of the evolution of lipid research in CVD.

Metabolome and Transcriptome Association Analysis Reveals the Link Between Pigmentation and Nutrition Utilization in the Juveniles of Sea Cucumber Holothuria leucospilota

The sea cucumber Holothuria leucospilota is an economically and ecologically important tropical species. Following development into juveniles, H. leucospilota undergoes a color change from white to black, involving a pigmentation process for over a period of several months. In this study, a combination of liquid chromatography-tandem mass spectrometry (LC-MS/MS) and Next-Generation sequencing (NGS) were employed to investigate the changes in metabolomic and transcriptomic profiles during pigmentation in H. leucospilota juveniles. The metabolomic analysis identified a total of 341 metabolites, of which 52 were found to be differentially regulated (P < 0.05 and VIP > 1), with 27 being upregulated in white individuals and 25 in black individuals. Additionally, 632 differentially expressed genes (DEGs) were identified, with 380 genes upregulated in white samples and 252 genes upregulated in black samples. Interestingly, the melanin content and tyrosinase transcript levels did not display significant differences between the two groups. Metabolomic data suggested the involvement of the linoleic acid metabolic pathway in pigmentation. Transcriptomic analysis, coupled with realtime PCR validation, revealed a decrease in the transcript levels of digestive enzymes like α-amylase, maltase-glucoamylase, and trehalase after the juveniles changed to black. Furthermore, the mRNA expressions of major yolk proteins showed a decline, indicating a shift in the accumulation of protein nutrient sources. Overall, our findings suggest that during the pigmentation process in H. leucospilota, no significant changes were observed in the classical melanin pathway, while notable alterations were observed in their nutritional status. This study provides valuable insights into the regulatory mechanisms of pigmentation in marine organisms.

Cell and rat serum, urine and tissue metabolomics analysis elucidates the key pathway changes associated with chronic nephropathy and reveals the mechanism of action of rhein

BACKGROUND

Rhein can significantly delay the progression of chronic nephropathy. However, its mechanism of action has not been adequately elaborated, which hinders its extensive clinical application. In this work, the effects of rhein on models of TGF-β-induced NRK-49F cellular fibrosis and rat renal ischemia-reperfusion fibrosis were evaluated using metabolomics and western blotting.

METHODS

The metabolic profiles of NRK-49F cells and rat urine, serum, and kidney tissues in the control, model, and rhein groups were investigated using UPLC-QTOF-MS. The levels of p-P65, p-IKK, p-AKT, p-P38, p-JNK and AP-1 in NRK-49F cells were measured using western blotting and immunofluorescence methods. Molecular docking and network pharmacology methods were employed to explore the relationship between the potential targets of rhein and key proteins in the NF-κB and MAPK signaling pathways.

RESULTS

Various potential metabolites, including sphingolipids, ceramides, phosphatidylcholine, and lysophosphatidylcholine,14-hydroxy-E4-neuroprostane E, and 5-HPETE, were present in the cell, tissue, urine, and serum samples; however, few metabolites matches exactly among the four type of biological samples. These differential metabolites can effectively differentiated between the control, model, and rhein groups. Pathway enrichment analysis of differential metabolites unveiled that sphingolipid metabolism, arachidonic acid metabolism, and glycerophospholipid metabolism were closely related to nephropathy. Phosphorylation levels of AKT, IKK, P65 and AP-1 in NRK-49F cells was reduced by rhein treatment. Network pharmacology and molecular docking showed that the potential targets of rhein might regulated the expression of MAPK and AKT in the NF-κB and MAPK signaling pathways.

CONCLUSION

In brief, rhein might delays the progression of chronic nephropathy via the metabolic pathways, NF-κB and MAPKs signaling pathways, which provides the foundation for its development and clinical application.

Sphingolipids in mitochondria-from function to disease

Sphingolipids are not only structural components of cellular membranes but also play vital roles in cell signaling and modulation of cellular processes. Within mitochondria, sphingolipids exert diverse effects on mitochondrial dynamics, energy metabolism, oxidative stress, and cell death pathways. In this review, we summarize literature addressing the crucial role of sphingolipids in mitochondria, highlighting their impact on mitochondrial dynamics, cellular bioenergetics, and important cell processes including apoptosis and mitophagy.

Lipid-lowering drugs affect lung cancer risk via sphingolipid metabolism: a drug-target Mendelian randomization study

Background: The causal relationship between lipid-lowering drug (LLD) use and lung cancer risk is controversial, and the role of sphingolipid metabolism in this effect remains unclear. Methods: Genome-wide association study data on low-density lipoprotein (LDL), apolipoprotein B (ApoB), and triglycerides (TG) were used to develop genetic instrumental variables (IVs) for LLDs. Two-step Mendelian randomization analyses were performed to examine the causal relationship between LLDs and lung cancer risk. The effects of ceramide, sphingosine-1-phosphate (S1P), and ceramidases on lung cancer risk were explored, and the proportions of the effects of LLDs on lung cancer risk mediated by sphingolipid metabolism were calculated. Results: APOB inhibition decreased the lung cancer risk in ever-smokers via ApoB (odds ratio [OR] 0.81, 95% confidence interval [CI] 0.70-0.92, p = 0.010), LDL (OR 0.82, 95% CI 0.71-0.96, p = 0.040), and TG (OR 0.63, 95% CI 0.46-0.83, p = 0.015) reduction by 1 standard deviation (SD), decreased small-cell lung cancer (SCLC) risk via LDL reduction by 1 SD (OR 0.71, 95% CI 0.56-0.90, p = 0.016), and decreased the plasma ceramide level and increased the neutral ceramidase level. APOC3 inhibition decreased the lung adenocarcinoma (LUAD) risk (OR 0.60, 95% CI 0.43-0.84, p = 0.039) but increased SCLC risk (OR 2.18, 95% CI 1.17-4.09, p = 0.029) via ApoB reduction by 1 SD. HMGCR inhibition increased SCLC risk via ApoB reduction by 1 SD (OR 3.04, 95% CI 1.38-6.70, p = 0.014). The LPL agonist decreased SCLC risk via ApoB (OR 0.20, 95% CI 0.07-0.58, p = 0.012) and TG reduction (OR 0.58, 95% CI 0.43-0.77, p = 0.003) while increased the plasma S1P level. PCSK9 inhibition decreased the ceramide level. Neutral ceramidase mediated 8.1% and 9.5% of the reduced lung cancer risk in ever-smokers via ApoB and TG reduction by APOB inhibition, respectively, and mediated 8.7% of the reduced LUAD risk via ApoB reduction by APOC3 inhibition. Conclusion: We elucidated the intricate interplay between LLDs, sphingolipid metabolites, and lung cancer risk. Associations of APOB, APOC3, and HMGCR inhibition and LPL agonist with distinct lung cancer risks underscore the multifaceted nature of these relationships. The observed mediation effects highlight the considerable influence of neutral ceramidase on the lung cancer risk reduction achieved by APOB and APOC3 inhibition.

CSF proteomics in autosomal dominant Alzheimer's disease highlights parallels with sporadic disease

Autosomal dominant Alzheimer's disease (ADAD) offers a unique opportunity to study pathophysiological changes in a relatively young population with few comorbidities. A comprehensive investigation of proteome changes occurring in ADAD could provide valuable insights into AD-related biological mechanisms and uncover novel biomarkers and therapeutic targets. Furthermore, ADAD might serve as a model for sporadic AD, but in-depth proteome comparisons are lacking. We aimed to identify dysregulated CSF proteins in ADAD and determine the degree of overlap with sporadic AD. We measured 1472 proteins in CSF of PSEN1 or APP mutation carriers (n = 22) and age- and sex-matched controls (n = 20) from the Amsterdam Dementia Cohort using proximity extension-based immunoassays (PEA). We compared protein abundance between groups with two-sided t-tests and identified enriched biological pathways. Using the same protein panels in paired plasma samples, we investigated correlations between CSF proteins and their plasma counterparts. Finally, we compared our results with recently published PEA data from an international cohort of sporadic AD (n = 230) and non-AD dementias (n = 301). All statistical analyses were false discovery rate-corrected. We detected 66 differentially abundant CSF proteins (65 increased, 1 decreased) in ADAD compared to controls (q < 0.05). The most strongly upregulated proteins (fold change >1.8) were related to immunity (CHIT1, ITGB2, SMOC2), cytoskeletal structure (MAPT, NEFL) and tissue remodelling (TMSB10, MMP-10). Significant CSF-plasma correlations were found for the upregulated proteins SMOC2 and LILR1B. Of the 66 differentially expressed proteins, 36 had been measured previously in the sporadic dementias cohort, 34 of which (94%) were also significantly upregulated in sporadic AD, with a strong correlation between the fold changes of these proteins in both cohorts (rs = 0.730, P < 0.001). Twenty-nine of the 36 proteins (81%) were also upregulated among non-AD patients with suspected AD co-pathology. This CSF proteomics study demonstrates substantial biochemical similarities between ADAD and sporadic AD, suggesting involvement of the same biological processes. Besides known AD-related proteins, we identified several relatively novel proteins, such as TMSB10, MMP-10 and SMOC2, which have potential as novel biomarkers. With shared pathophysiological CSF changes, ADAD study findings might be translatable to sporadic AD, which could greatly expedite therapy development.

Altered sphingolipid pathway in SARS-CoV-2 infected human lung tissue

Introduction

The SARS-CoV-2 mediated COVID-19 pandemic has impacted millions worldwide. Hyper-inflammatory processes, including cytokine storm, contribute to long-standing tissue injury and damage in COVID-19. The metabolism of sphingolipids as regulators of cell survival, differentiation, and proliferation has been implicated in inflammatory signaling and cytokine responses. Sphingosine-kinase-1 (SK1) and ceramide-synthase-2 (CERS2) generate metabolites that regulate the anti- and pro-apoptotic processes, respectively. Alterations in SK1 and CERS2 expression may contribute to the inflammation and tissue damage during COVID-19. The central objective of this study is to evaluate structural changes in the lung post-SARS-CoV-2 infection and to investigate whether the sphingolipid rheostat is altered in response to SARS-CoV-2 infection.

Methods

Central and peripheral lung tissues from COVID-19+ or control autopsies and resected lung tissue from COVID-19 convalescents were subjected to histologic evaluation of airspace and collagen deposisiton, and immunohistochemical evaluation of SK1 and CERS2.

Results

Here, we report significant reduction in air space and increase in collagen deposition in lung autopsy tissues from patients who died from COVID-19 (COVID-19+) and COVID-19 convalescent individuals. SK1 expression increased in the lungs of COVID-19+ autopsies and COVID-19 convalescent lung tissue compared to controls and was mostly associated with Type II pneumocytes and alveolar macrophages. No significant difference in CERS2 expression was noted. SARS-CoV-2 infection upregulates SK1 and increases the ratio of SK1 to CERS2 expression in lung tissues of COVID-19 autopsies and COVID-19 convalescents.

Discussion

These data suggest an alteration in the sphingolipid rheostat in lung tissue during COVID-19, suggesting a potential contribution to the inflammation and tissue damage associated with viral infection.

Ceramide synthase CERS4 gene downregulation is associated with KRAS mutation in colorectal cancer

Ceramide, the central molecule in sphingolipid synthesis, is a bioactive lipid that serves as a regulatory molecule in the anti-inflammatory responses, apoptosis, programmed necrosis, autophagy, and cell motility of cancer cells. In particular, the authors have reported differences in sphingolipid content in colorectal cancer tissues. The associations among genetic mutations, clinicopathological factors, and sphingolipid metabolism in colorectal cancer (CRC) have not been investigated. The objective of this study is to investigate the association between genes associated with sphingolipid metabolism, genetic variations in colorectal cancer (CRC), and clinicopathological factors in CRC patients. We enrolled 82 consecutive patients with stage I-IV CRC who underwent tumor resection at a single institution in 2019-2021. We measured the expression levels of genes related to sphingolipid metabolism and examined the relationships between CRC gene mutations and the clinicopathological data of each individual patient. The relationship between CRC gene mutations and expression levels of ceramide synthase (CERS), N-acylsphingosine amidohydrolase (ASAH), and alkaline ceramidase (ACER) genes involved in sphingolipid metabolism was examined CRES4 expression was significantly lower in the CRC KRAS gene mutation group (p = 0.004); vascular invasion was more common in colorectal cancer patients with high CERS4 expression (p = 0.0057). By examining the correlation between sphingolipid gene expression and clinical factors, we were able to identify cancer types in which sphingolipid metabolism is particularly relevant. CERS4 expression was significantly reduced in KRAS mutant CRC. Moreover, CRC with decreased CERS4 showed significantly more frequent venous invasion.

Metabolite Alterations and Interactions with Microbiota in Helicobacter pylori-Associated Gastric Lesions

Metabolites and their interactions with microbiota may be involved in Helicobacter pylori-associated gastric lesion development. This study aimed to explore metabolite alterations upon H. pylori eradication and possible roles of microbiota-metabolite interactions in progression of precancerous lesions. Targeted metabolomics assays and 16S rRNA gene sequencing were conducted to investigate metabolic and microbial alterations of paired gastric biopsy specimens in 58 subjects with successful and 57 subjects with failed anti-H. pylori treatment. Integrative analyses were performed by combining the metabolomics and microbiome profiles from the same intervention participants. A total of 81 metabolites were significantly altered after successful eradication compared to failed treatment, including acylcarnitines, ceramides, triacylglycerol, cholesterol esters, fatty acid, sphingolipids, glycerophospholipids, and glycosylceramides, with P values of <0.05 for all. The differential metabolites showed significant correlations with microbiota in baseline biopsy specimens, such as negative correlations between Helicobacter and glycerophospholipids, glycosylceramide, and triacylglycerol (P < 0.05 for all), which were altered by eradication. The characteristic negative correlations between glycosylceramides and Fusobacterium, Streptococcus, and Gemella in H. pylori-positive baseline biopsy specimens were further noticed in active gastritis and intestinal metaplasia (P < 0.05 for all). A panel including differential metabolites, genera, and their interactions may help to discriminate high-risk subjects who progressed from mild to advanced precancerous lesions in short-term and long-term follow-up periods with areas under the curve (AUC) of 0.914 and 0.801, respectively. Therefore, our findings provide new insights into the metabolites and microbiota interactions in H. pylori-associated gastric lesion progression. IMPORTANCE In this study, a panel was established including differential metabolites, genera, and their interactions, which may help to discriminate high-risk subjects for progression from mild lesions to advanced precancerous lesions in short-term and long-term follow-up.

Immune System and Brain/Intestinal Barrier Functions in Psychiatric Diseases: Is Sphingosine-1-Phosphate at the Helm?

Over the past few decades, extensive research has shed light on immune alterations and the significance of dysfunctional biological barriers in psychiatric disorders. The leaky gut phenomenon, intimately linked to the integrity of both brain and intestinal barriers, may play a crucial role in the origin of peripheral and central inflammation in these pathologies. Sphingosine-1-phosphate (S1P) is a bioactive lipid that regulates both the immune response and the permeability of biological barriers. Notably, S1P-based drugs, such as fingolimod and ozanimod, have received approval for treating multiple sclerosis, an autoimmune disease of the central nervous system (CNS), and ulcerative colitis, an inflammatory condition of the colon, respectively. Although the precise mechanisms of action are still under investigation, the effectiveness of S1P-based drugs in treating these pathologies sparks a debate on extending their use in psychiatry. This comprehensive review aims to delve into the molecular mechanisms through which S1P modulates the immune system and brain/intestinal barrier functions. Furthermore, it will specifically focus on psychiatric diseases, with the primary objective of uncovering the potential of innovative therapies based on S1P signaling.

Debaryomyces hansenii supplementation in low fish meal diets promotes growth, modulates microbiota and enhances intestinal condition in juvenile marine fish

BACKGROUND

The development of a sustainable business model with social acceptance, makes necessary to develop new strategies to guarantee the growth, health, and well-being of farmed animals. Debaryomyces hansenii is a yeast species that can be used as a probiotic in aquaculture due to its capacity to i) promote cell proliferation and differentiation, ii) have immunostimulatory effects, iii) modulate gut microbiota, and/or iv) enhance the digestive function. To provide inside into the effects of D. hansenii on juveniles of gilthead seabream (Sparus aurata) condition, we integrated the evaluation of the main key performance indicators coupled with the integrative analysis of the intestine condition, through histological and microbiota state, and its transcriptomic profiling.

RESULTS

After 70 days of a nutritional trial in which a diet with low levels of fishmeal (7%) was supplemented with 1.1% of D. hansenii (17.2 × 10⁵ CFU), an increase of ca. 12% in somatic growth was observed together with an improvement in feed conversion in fish fed a yeast-supplemented diet. In terms of intestinal condition, this probiotic modulated gut microbiota without affecting the intestine cell organization, whereas an increase in the staining intensity of mucins rich in carboxylated and weakly sulphated glycoconjugates coupled with changes in the affinity for certain lectins were noted in goblet cells. Changes in microbiota were characterized by the reduction in abundance of several groups of Proteobacteria, especially those characterized as opportunistic groups. The microarrays-based transcriptomic analysis found 232 differential expressed genes in the anterior-mid intestine of S. aurata, that were mostly related to metabolic, antioxidant, immune, and symbiotic processes.

CONCLUSIONS

Dietary administration of D. hansenii enhanced somatic growth and improved feed efficiency parameters, results that were coupled to an improvement of intestinal condition as histochemical and transcriptomic tools indicated. This probiotic yeast stimulated host-microbiota interactions without altering the intestinal cell organization nor generating dysbiosis, which demonstrated its safety as a feed additive. At the transcriptomic level, D. hansenii promoted metabolic pathways, mainly protein-related, sphingolipid, and thymidylate pathways, in addition to enhance antioxidant-related intestinal mechanisms, and to regulate sentinel immune processes, potentiating the defensive capacity meanwhile maintaining the homeostatic status of the intestine.

Regulation mechanism of lipids for extracellular yellow pigments production by Monascus purpureus BWY-5

The biosynthesis and secretion of Monascus pigments are closely related to the integrity of the cell membrane, which determines the composition of lipids and its content in cell membrane. The present study aimed to thoroughly describe the changes of lipid profiling in Monascus purpureus BWY-5, which was screened by carbon ion beam irradiation (¹²C⁶⁺) to almost single yield extracellular Monascus yellow pigments (extra-MYPs), by absolute quantitative lipidomics and tandem mass tags (TMT) based quantitative proteomic. ¹²C⁶⁺ irradiation caused non-lipid oxidation damage to Monascus cell membrane, leading to an imbalance in cell membrane lipid homeostasis. This imbalance was attributed to significant changes not only in the composition but also in the content of lipids in Monascus, especially the inhibition of glycerophospholipid biosynthesis. Integrity of plasma membrane was maintained by the increased production of ergosterol, monogalactosylmonoacylglycerol (MGMG) and sulfoquinovosylmonoacylglycerol (SQMG), while mitochondrial membrane homeostasis was maintained by the increase of cardiolipin production. The growth and extra-MYPs production of Monascus BWY-5 have been regulated by the promotion of sphingolipids (ceramide and sulfatide) biosynthesis. Simultaneous, energy homeostasis may be achieved by increase of TG synthesis and Ca²⁺/Mg²⁺-ATPase activity. These finding suggest ergosterol, cardiolipin, sphingolipids, MGMG and SQMG play a key facilitating role in cytomembrane lipid homeostasis maintaining for Monascus purpureus BWY-5, and then it is closely related to cell growth and extra-MYPs production. KEY POINTS: 1. Energy homeostasis in Monascus purpureus BWY-5 was achieved by increase of TG synthesis and Ca²⁺/Mg²⁺-ATPase activity. 2. Integrity of plasma membrane in Monascus purpureus BWY-5 was maintained by the increased production of ergosterol. 3. Mitochondrial membrane homeostasis in Monascus purpureus BWY-5 was maintaed by the increase of cardiolipin synthesis.

Proteins journey-from marine to freshwater ecosystem: blood plasma proteomic profiles of pink salmon Oncorhynchus gorbuscha Walbaum, 1792 during spawning migration

The pink salmon (Oncorhynchus gorbuscha) is a commercial anadromous fish species of the family Salmonidae. This species has a 2-year life cycle that distinguishes it from other salmonids. It includes the spawning migration from marine to freshwater environments, accompanied by significant physiological and biochemical adaptive changes in the body. This study reveals and describes variability in the blood plasma proteomes of female and male pink salmon collected from three biotopes-marine, estuarine and riverine-that the fish pass through in spawning migration. Identification and comparative analysis of blood plasma protein profiles were performed using proteomics and bioinformatic approaches. The blood proteomes of female and male spawners collected from different biotopes were qualitatively and quantitatively distinguished. Females differed primarily in proteins associated with reproductive system development (certain vitellogenin and choriogenin), lipid transport (fatty acid binding protein) and energy production (fructose 1,6-bisphosphatase), and males in proteins involved in blood coagulation (fibrinogen), immune response (lectins) and reproductive processes (vitellogenin). Differentially expressed sex-specific proteins were implicated in proteolysis (aminopeptidases), platelet activation (β- and γ-chain fibrinogen), cell growth and differentiation (a protein containing the TGF_BETA_2 domain) and lipid transport processes (vitellogenin and apolipoprotein). The results are of both fundamental and practical importance, adding to existing knowledge of the biochemical adaptations to spawning of pink salmon, a representative of economically important migratory fish species.

Expression of Ceramide-Metabolizing Enzymes in the Heart Adipose Tissue of Cardiovascular Disease Patients

Here, we examined the expression of ceramide metabolism enzymes in the subcutaneous adipose tissue (SAT), epicardial adipose tissue (EAT) and perivascular adipose tissue (PVAT) of 30 patients with coronary artery disease (CAD) and 30 patients with valvular heart disease (VHD) by means of quantitative polymerase chain reaction and fluorescent Western blotting. The EAT of patients with CAD showed higher expression of the genes responsible for ceramide biosynthesis (SPTLC1, SPTLC2, CERS1, 5, 6, DEGS1, and SMPD1) and utilization (ASAH1, SGMS1). PVAT was characterized by higher mRNA levels of CERS3, CERS4, DEGS1, SMPD1, and ceramide utilization enzyme (SGMS2). In patients with VHD, there was a high CERS4, DEGS1, and SGMS2 expression in the EAT and CERS3 and CERS4 expression in the PVAT. Among patients with CAD, the expression of SPTLC1 in SAT and EAT, SPTLC2 in EAT, CERS2 in all studied AT, CERS4 and CERS5 in EAT, DEGS1 in SAT and EAT, ASAH1 in all studied AT, and SGMS1 in EAT was higher than in those with VHD. Protein levels of ceramide-metabolizing enzymes were consistent with gene expression trends. The obtained results indicate an activation of ceramide synthesis de novo and from sphingomyelin in cardiovascular disease, mainly in EAT, that contributes to the accumulation of ceramides in this location.

Quantification of α-hydroxy ceramides in mice serum by LC-MS/MS: Application to sepsis study

Alpha-hydroxy ceramides are not only the precursors of many complex sphingolipids, also play a major role in membrane homeostasis and cellular signal transduction. However, current research rarely involved quantitative methods for α-hydroxy ceramides, which greatly restricts the study of its biological function. This work aimed to develop a reliable assay for the accurate quantification of α-hydroxy ceramides in vivo study. LC-MS/MS method was developed for the accurate quantification of six α-hydroxy ceramides of Cer(d18:1/16:0(2OH)), Cer(d18:1/18:0(2OH)), Cer(d18:1/18:1(2OH)), Cer(d18:1/20:0(2OH)), Cer(d18:1/22:0(2OH)) and Cer(d18:1/24:1(2OH)) in mice serum. This assay was validated with low limit of quantitation of 3.125 ng/mL, a dynamic range of 3.125-400 ng/mL (R2 > 0.99), precision (<15 %), and accuracy (88 % to 115 %). Applying the method to the determination of α-hydroxy ceramides in the serum of sepsis mice, the levels of Cer(d18:1/16:0(2OH)), Cer(d18:1/20:0(2OH)), Cer(d18:1/24:1(2OH)) were significantly elevated in LPS-induced septic as compared to the normal control. In conclusion, this LC-MS method was qualified in α-hydroxy ceramides quantification in vivo and a significant association was found between α-hydroxy ceramides and sepsis.

Induction of Inflammation Disrupts the Negative Interplay between STING and S1P Axis That Is Observed during Physiological Conditions in the Lung

The stimulator of interferon genes (STING) is a master regulator of innate immunity, involved in several inflammatory diseases. Our previous data showed that sphingosine-1-phosphate (S1P) is released during inflammatory conditions in the lung. The aim of this study was to understand the interplay between S1P and STING during both physiological and pathological conditions. The mRNA levels of ceramidase (ASAH1), S1P precursor enzyme, and STING were inversely correlated in healthy lung tissues, but positively correlated in tumor tissues. The activation of STING induced higher expression of ASAH1 and was accompanied by IFN-β and IL-6 release. ASAH1 and sphingosine kinases (SPHK I/II) blockade significantly reduced IL-6, but not IFNβ, after STING activation. In support of this, taking advantage of a mouse model, we found that inflamed lungs had higher levels of inactive ASAH1 when STING was inhibited. This confirmed the human data, where higher levels of STING promoted the activation of ASAH1. Lung cancer patients positive to STING and ASAH1 mRNA levels had a dismal prognosis in that the overall survival was reduced compared to STING/ASAH1 negative patients. These data highlight that during physiological conditions, STING and the S1P axis do not interfere, whereas in lung cancer patients their interplay is associated to poor prognosis.

Evolving Diagnostic and Treatment Strategies for Pediatric CNS Tumors: The Impact of Lipid Metabolism

Pediatric neurological tumors are a heterogeneous group of cancers, many of which carry a poor prognosis and lack a "standard of care" therapy. While they have similar anatomic locations, pediatric neurological tumors harbor specific molecular signatures that distinguish them from adult brain and other neurological cancers. Recent advances through the application of genetics and imaging tools have reshaped the molecular classification and treatment of pediatric neurological tumors, specifically considering the molecular alterations involved. A multidisciplinary effort is ongoing to develop new therapeutic strategies for these tumors, employing innovative and established approaches. Strikingly, there is increasing evidence that lipid metabolism is altered during the development of these types of tumors. Thus, in addition to targeted therapies focusing on classical oncogenes, new treatments are being developed based on a broad spectrum of strategies, ranging from vaccines to viral vectors, and melitherapy. This work reviews the current therapeutic landscape for pediatric brain tumors, considering new emerging treatments and ongoing clinical trials. In addition, the role of lipid metabolism in these neoplasms and its relevance for the development of novel therapies are discussed.

Identifying the intervention mechanisms of polydatin in hyperuricemia model rats by using UHPLC-Q-Exactive Orbitrap mass spectroscopy metabonomic approach

Introduction

Polydatin is a biologically active compound found in mulberries, grapes, and Polygonum cuspidatum, and it has uric acid-lowering effects. However, its urate-lowering effects and the molecular mechanisms underlying its function require further study.

Methods

In this study, a hyperuricemic rat model was established to assess the effects of polydatin on uric acid levels. The body weight, serum biochemical indicators, and histopathological parameters of the rats were evaluated. A UHPLC-Q-Exactive Orbitrap mass spectrometry-based metabolomics approach was applied to explore the potential mechanisms of action after polydatin treatment.

Results

The results showed a trend of recovery in biochemical indicators after polydatin administration. In addition, polydatin could alleviate damage to the liver and kidneys. Untargeted metabolomics analysis revealed clear differences between hyperuricemic rats and the control group. Fourteen potential biomarkers were identified in the model group using principal component analysis and orthogonal partial least squares discriminant analysis. These differential metabolites are involved in amino acid, lipid, and energy metabolism. Of all the metabolites, the levels of L-phenylalanine, L-leucine, O-butanoylcarnitine, and dihydroxyacetone phosphate decreased, and the levels of L-tyrosine, sphinganine, and phytosphingosine significantly increased in hyperuricemic rats. After the administration of polydatin, the 14 differential metabolites could be inverted to varying degrees by regulating the perturbed metabolic pathway.

Conclusion

This study has the potential to enhance our understanding of the mechanisms of hyperuricemia and demonstrate that polydatin is a promising potential adjuvant for lowering uric acid levels and alleviating hyperuricemia-related diseases.

Untargeted Lipidomic Profiling Reveals Lysophosphatidylcholine and Ceramide as Atherosclerotic Risk Factors in apolipoprotein E Knockout Mice

Despite the availability and use of numerous cholesterol-lowering drugs, atherosclerotic cardiovascular disease (ASCVD) remains the leading cause of mortality globally. Many researchers have focused their effort on identifying modified lipoproteins. However, lipid moieties such as lysophosphatidylcholine (LPC) and ceramide (CER) contribute to atherogenic events. LPC and CER both cause endothelial mitochondrial dysfunction, leading to fatty acid and triglyceride (TG) accumulation. In addition, they cause immune cells to differentiate into proinflammatory phenotypes. To uncover alternative therapeutic approaches other than cholesterol- and TG-lowering medications, we conducted untargeted lipidomic investigations to assess the alteration of lipid profiles in apolipoprotein E knockout (apoE^-/-) mouse model, with or without feeding a high-fat diet (HFD). Results indicated that, in addition to hypercholesterolemia and hyperlipidemia, LPC levels were two to four times higher in apoE^-/- mice compared to wild-type mice in C57BL/6 background, regardless of whether they were 8 or 16 weeks old. Sphingomyelin (SM) and CER were elevated three- to five-fold in apoE^-/- mice both at the basal level and after 16 weeks when compared to wild-type mice. After HFD treatment, the difference in CER levels elevated more than ten-fold. Considering the atherogenic properties of LPC and CER, they may also contribute to the early onset of atherosclerosis in apoE^-/- mice. In summary, the HFD-fed apoE^-/- mouse shows elevated LPC and CER contents and is a suitable model for developing LPC- and CER-lowering therapies.

Plasma sphingolipids, lung function and COPD: the Cardiovascular Health Study

Rationale

COPD is the third leading cause of death in the United States. Sphingolipids, structural membrane constituents that play a role in cellular stress and apoptosis signalling, may be involved in lung function.

Methods

In the Cardiovascular Health Study, a prospective cohort of older adults, we cross-sectionally examined the association of plasma levels of 17 sphingolipid species with lung function and COPD. Multivariable linear regression and logistic regression were used to evaluate associations of sphingolipid concentrations with forced expiratory volume in 1 s (FEV1) and odds of COPD, respectively.

Results

Of the 17 sphingolipids evaluated, ceramide-18 (Cer-18) and sphingomyelin-18 (SM-18) were associated with lower FEV1 values (-0.061 L per two-fold higher Cer-18, p=0.001; -0.092 L per two-fold higher SM-18, p=0.002) after correction for multiple testing. Several other associations were significant at a 0.05 level, but did not reach statistical significance after correction for multiple testing. Specifically, Cer-18 and SM-18 were associated with higher odds of COPD (odds ratio per two-fold higher Cer-18 1.29, p=0.03 and SM-18 1.73, p=0.008). Additionally, Cer-16 and SM-16 were associated with lower FEV1 values, and Cer-14, SM-14 and SM-16 with a higher odds of COPD.

Conclusion

In this large cross-sectional study, specific ceramides and sphingomyelins were associated with reduced lung function in a population-based study. Future studies are needed to examine whether these biomarkers are associated with longitudinal change in FEV1 within individuals or with incident COPD.

Role of ceramides in diabetic foot ulcers (Review)

Diabetes mellitus (DM) is a metabolic disorder, which if not managed properly, can lead to serious health problems over time and impose significant financial burden on the patient, their family and society as a whole. The study of this disease and the underlying biological mechanism is gaining momentum. Multiple pieces of conclusive evidence show that ceramides are involved in the occurrence and development of diabetes. The present review focuses on the function of ceramides, a type of sphingolipid signaling molecule, to provide a brief description of ceramides and their metabolism, discuss the significant roles of ceramides in the healthy skin barrier, and speculate on the potential involvement of ceramides in the pathogenesis and development of diabetic foot ulcers (DFUs). Understanding these aspects of this disease more thoroughly is crucial to establish how ceramides contribute to the etiology of diabetic foot infections and identify possible therapeutic targets for the treatment of DFUs.

GAP-43 closely interacts with BDNF in hippocampal neurons and is associated with Alzheimer's disease progression

Introduction

Growth-associated protein 43 (GAP-43) is known as a neuronal plasticity protein because it is widely expressed at high levels in neuronal growth cones during axonal regeneration. GAP-43 expressed in mature adult neurons is functionally important for the neuronal communication of synapses in learning and memory. Brain-derived neurotrophic factor (BDNF) is closely related to neurodegeneration and synaptic plasticity during the aging process. However, the molecular mechanisms regulating neurodegeneration and synaptic plasticity underlying the pathogenesis and progression of Alzheimer's disease (AD) still remain incompletely understood.

Methods

Remarkably, the expressions of GAP-43 and BDNF perfectly match in various neurons in the Human Brain Atlas database. Moreover, GAP-43 and BDNF are highly expressed in a healthy adults' hippocampus brain region and are inversely correlated with the amyloid beta (Aβ), which is the pathological peptide of amyloid plaques found in the brains of patients with AD.

Results

These data led us to investigate the impact of the direct molecular interaction between GAP-43 and BDNF in hippocampal neuron fate. In this study, we show that GAP-43 and BDNF are inversely associated with pathological molecules for AD (Tau and Aβ). In addition, we define the three-dimensional protein structure for GAP-43 and BDNF, including the predictive direct binding sites via analysis using ClusPro 2.0, and demonstrate that the deprivation of GAP-43 and BDNF triggers hippocampal neuronal death and memory dysfunction, employing the GAP-43 or BDNF knock-down cellular models and 5XFAD mice.

Conclusion

These results show that GAP-43 and BDNF are direct binding partners in hippocampal neurons and that their molecular signaling might be potential therapeutic targets for AD.

ACER2 forms a cold tumor microenvironment and predicts the molecular subtype in bladder cancer: Results from real-world cohorts

Background: ACER2 is a critical gene regulating cancer cell growth and migration, whereas the immunological role of ACER2 in the tumor microenvironment (TME) is scarcely reported. Thus, we lucubrate the potential performance of ACER2 in bladder cancer (BLCA). Methods: We initially compared ACER2 expressions in BLCA with normal urothelium tissues based on data gathered from the Cancer Genome Atlas (TCGA) and our Xiangya cohort. Subsequently, we systematically explored correlations between ACER2 with immunomodulators, anti-cancer immune cycles, tumor-infiltrating immune cells, immune checkpoints and the T-cell inflamed score (TIS) to further confirm its immunological role in BLCA TME. In addition, we performed ROC analysis to illustrate the accuracy of ACER2 in predicting BLCA molecular subtypes and explored the response to several cancer-related treatments. Finally, we validated results in an immunotherapy cohort and Xiangya cohort to ensure the stability of our study. Results: Compared with normal urinary epithelium, ACER2 was significantly overexpressed in several cell lines and the tumor tissue of BLCA. ACER2 can contribute to the formation of non-inflamed BLCA TME supported by its negative correlations with immunomodulators, anti-cancer immune cycles, tumor-infiltrating immune cells, immune checkpoints and the TIS. Moreover, BLCA patients with high ACER2 expression were inclined to the luminal subtype, which were characterized by insensitivity to neoadjuvant chemotherapy, chemotherapy and radiotherapy but not to immunotherapy. Results in the IMvigor210 and Xiangya cohort were consistent. Conclusion: ACER2 could accurately predict the TME and clinical outcomes for BLCA. It would be served as a promising target for precision treatment in the future.

Impact of Visceral Obesity on Structural and Functional Alterations of Gut Microbiota in Polycystic Ovary Syndrome (PCOS): A Pilot Study Using Metagenomic Analysis

OBJECTIVE

We aimed to identify structural and functional alterations of gut microbiota associated with visceral obesity in adult women with polycystic ovary syndrome (PCOS).

METHODS

Twenty-seven adults with PCOS underwent stool and fasting blood collection, oral glucose tolerance testing, and visceral fat area (VFA) measurement via dual-bioimpedance technique. Metagenomic analysis was used to analyze gut microbiota.

RESULTS

PCOS patients were divided into three groups: visceral obesity group (PCOS-VO, n=9, age 28.33±5.68 years, BMI 37.06±4.27 kg/m², VFA 128.67±22.45 cm²), non-visceral obesity group (PCOS-NVO, n=10, age 25.40±4.53, BMI 30.74±3.95, VFA 52.00±24.04), normal BMI group (PCOS-NB, n=8, age 27.88±2.53, BMI 21.56±2.20, VFA 27.00±21.18), with no statistical difference in age (P>0.05) and significantly statistical differences in BMI and VFA (P<0.05). The groups showed a significant difference in microbial β-diversity between PCOS-VO and PCOS-NVO (P=0.002) and no difference between PCOS-NVO and PCOS-NB (P=0.177). Bacteroidetes was the phylum with the highest relative abundance among all patients, followed by Firmicutes. Those with visceral obesity had a higher abundance of Prevotella, Megamonas, and Dialister genera, positively correlated with metabolic markers (r>0.4, P<0.05), and lower abundance of Phascolarctobacterium and Neisseria genera, negatively correlated with metabolic markers (r<-0.4, P<0.05). Functional annotation analysis showed significant differences in relative abundance of ribosome pathway, fatty acid biosynthesis pathway, and sphingolipid signaling pathway between groups, affecting lipid homeostasis and visceral fat accumulation.

CONCLUSION

Alteration in β-diversity of gut microbiota exists in PCOS with visceral obesity versus those without visceral obesity and relates to functional differences in ribosomes, fatty acid biosynthesis, and sphingolipid signaling pathways.

Presence of Ceramidase Activity in Electronegative LDL

Electronegative low-density lipoprotein (LDL(-)) is a minor modified fraction of human plasma LDL with several atherogenic properties. Among them is increased bioactive lipid mediator content, such as lysophosphatidylcholine (LPC), non-esterified fatty acids (NEFA), ceramide (Cer), and sphingosine (Sph), which are related to the presence of some phospholipolytic activities, including platelet-activating factor acetylhydrolase (PAF-AH), phospholipase C (PLC), and sphingomyelinase (SMase), in LDL(-). However, these enzymes' activities do not explain the increased Sph content, which typically derives from Cer degradation. In the present study, we analyzed the putative presence of ceramidase (CDase) activity, which could explain the increased Sph content. Thin layer chromatography (TLC) and lipidomic analysis showed that Cer, Sph, and NEFA spontaneously increased in LDL(-) incubated alone at 37 °C, in contrast with native LDL(+). An inhibitor of neutral CDase prevented the formation of Sph and, in turn, increased Cer content in LDL(-). In addition, LDL(-) efficiently degraded fluorescently labeled Cer (NBD-Cer) to form Sph and NEFA. These observations defend the existence of the CDase-like activity's association with LDL(-). However, neither the proteomic analysis nor the Western blot detected the presence of an enzyme with known CDase activity. Further studies are thus warranted to define the origin of the CDase-like activity detected in LDL(-).

Spatial proteomics in three-dimensional intact specimens

Spatial molecular profiling of complex tissues is essential to investigate cellular function in physiological and pathological states. However, methods for molecular analysis of large biological specimens imaged in 3D are lacking. Here, we present DISCO-MS, a technology that combines whole-organ/whole-organism clearing and imaging, deep-learning-based image analysis, robotic tissue extraction, and ultra-high-sensitivity mass spectrometry. DISCO-MS yielded proteome data indistinguishable from uncleared samples in both rodent and human tissues. We used DISCO-MS to investigate microglia activation along axonal tracts after brain injury and characterized early- and late-stage individual amyloid-beta plaques in a mouse model of Alzheimer's disease. DISCO-bot robotic sample extraction enabled us to study the regional heterogeneity of immune cells in intact mouse bodies and aortic plaques in a complete human heart. DISCO-MS enables unbiased proteome analysis of preclinical and clinical tissues after unbiased imaging of entire specimens in 3D, identifying diagnostic and therapeutic opportunities for complex diseases. VIDEO ABSTRACT.

Assessing potential liver injury induced by Polygonum multiflorum using potential biomarkers via targeted sphingolipidomics

CONTEXT

Polygonum multiflorum Thunb. (Polygonaceae) (PM) can cause potential liver injury which is typical in traditional Chinese medicines (TCMs)-induced hepatotoxicity. The mechanism involved are unclear and there are no sensitive evaluation indicators.

OBJECTIVE

To assess PM-induced liver injury, identify sensitive assessment indicators, and screen for new biomarkers using sphingolipidomics.

MATERIALS AND METHODS

Male Sprague-Dawley (SD) rats were randomly divided into four groups (control, model with low-, middle- and high-dose groups, n = 6 each). Rats in the three model groups were given different doses of PM (i.g., low/middle/high dose, 2.7/8.1/16.2 g/kg) for four months. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels in the plasma and liver were quantitatively analyzed. Fixed liver tissue sections were stained with haematoxylin and eosin and examined under a light microscope. The targeted sphingolipidomic analysis of plasma was performed using high-performance liquid chromatography tandem mass spectrometry.

RESULTS

The maximal tolerable dose (MTD) of PM administered intragastrically to mice was 51 g/kg. Sphingolipid profiling of normal and PM-induced liver injury SD rats revealed three potential biomarkers: ceramide (Cer) (d18:1/24:1), dihydroceramide (d18:1/18:0)-1-phosphate (dhCer (d18:1/18:0)-1P) and Cer (d18:1/26:1), at 867.3-1349, 383.4-1527, and 540.5-658.7 ng/mL, respectively. A criterion for the ratio of Cer (d18:1/24:1) and Cer (d18:1/26:1) was suggested and verified, with a normal range of 1.343-2.368 (with 95% confidence interval) in plasma.

CONCLUSIONS

Three potential biomarkers and one criterion for potential liver injury caused by PM that may be more sensitive than ALT and AST were found.

Galactosylceramidase deficiency and pathological abnormalities in cerebral white matter of Krabbe disease

Krabbe Disease (KD) is an autosomal recessive disorder that results from loss-of-function mutations in the GALC gene, which encodes lysosomal enzyme galactosylceramidase (GALC). Functional deficiency of GALC is toxic to myelin-producing cells, which leads to progressive demyelination in both the central and peripheral nervous systems. It is hypothesized that accumulation of psychosine, which can only be degraded by GALC, is a primary initiator of pathologic cascades. Despite the central role of GALC in KD pathomechanism, investigations of GALC deficiency at a protein level are largely absent, due in part, to the lack of sensitive antibodies in the field. Leveraging two custom antibodies that can detect GALC at endogenous levels, we demonstrated that GALC protein is predominantly localized to oligodendrocytes in cerebral white matter of an infant brain, consistent with its functional role in myelination. Mature GALC could also be quantitatively detected as a 26 kDa band by western blotting and correlated to enzyme activity in brain tissues. The p.Ile562Thr polymorphic variant, which is over-represented in the KD population, was associated with reduced mature GALC protein and activity. In three infantile KD cases, homozygous null mutations in GALC lead to deficiency in total GALC protein and activity. Interestingly, although GALC activity was absent, normal levels of total GALC protein were detected by a sandwich ELISA using our custom antibodies in a later-onset KD brain, which suggests that the assay has the potential to differentiate infantile- and later-onset KD cases. Among the infantile KD cases, we quantified a 5-fold increase in psychosine levels, and observed increased levels of acid ceramidase, a key enzyme for psychosine production, and hyperglycosylated lysosomal-associated membrane protein 1, a marker for lysosomal activation, in periventricular white matter, a major pathological brain region, when compared with age-matched normal controls. While near complete demyelination was observed in these cases, we quantified that an early-infantile case (age of death at 10 months) had about 3-fold increases in both globoid cells, a pathological hallmark for KD, and CD8-positive T lymphocytes, a pathological marker for multiple sclerosis, in the white matter when compared with a slower progressing infantile case (age of death at 21 months), which suggests a positive correlation between clinical severity and neuropathology. Taken together, our findings have advanced the understanding of GALC protein biology in the context of normal and KD brain white matter. We also revealed new neuropathological changes that may provide insights to understand KD pathogenesis.

The feto-placental metabolome of spontaneous labour is not reproduced following induction of labour

INTRODUCTION

The mechanism for human labour remains poorly understood, limiting our ability to manage complications including spontaneous preterm birth and induction of labour (IOL). The study of fetal signals poses specific challenges. Metabolomic analysis of maternal blood, the cord artery (CA), and cord vein (CV), allows simultaneous interrogation of multiple metabolic pathways associated with different modes of labour onset and birth.

METHODS

Global mass spectrometry metabolomics analysis was performed on serial samples collected from participants during pregnancy, in latent phase of labour, and following birth (CA, CV, and intervillous (IV) blood), from those who spontaneously laboured and birthed vaginally (SL group), had IOL and birthed vaginally (IOL group), or birthed via elective caesarean section (no labour; ECS group).

RESULTS

There were clear differences in fetal and maternal steroid, arachidonate and sphingosine pathways between the SL and IOL groups, despite similar uterine contractions and vaginal birth. The CA/CV ratio for key steroids of the IOL group were more alike the ECS group than the SL group, including progesterone (CA/CV ratio for: SL group=3.5; IOL group=0.5; and ECS group=0.5), and oestriol (CA/CV ratio for: SL group=4.3; IOL group=0.4; and for ECS group=0.2). There were no such changes in the maternal samples.

DISCUSSION

These findings indicate that IOL does not reproduce the pathways activated in spontaneous labour. The decreased placental progesterone production observed with spontaneous labour may represent a local intrauterine progesterone withdrawal, which, together with other signals, would activate parturition pathways involving arachidonate and sphingosine metabolism.