Untargeted lipidomics analysis in women with morbid obesity and type 2 diabetes mellitus: A comprehensive study.

There is a phenotype of obese individuals termed metabolically healthy obese that present a reduced cardiometabolic risk. This phenotype offers a valuable model for investigating the mechanisms connecting obesity and metabolic alterations such as Type 2 Diabetes Mellitus (T2DM). Previously, in an untargeted metabolomics analysis in a cohort of morbidly obese women, we observed a different lipid metabolite pattern between metabolically healthy morbid obese individuals and those with associated T2DM. To validate these findings, we have performed a complementary study of lipidomics. In this study, we assessed a liquid chromatography coupled to a mass spectrometer untargeted lipidomic analysis on serum samples from 209 women, 73 normal-weight women (control group) and 136 morbid obese women. From those, 65 metabolically healthy morbid obese and 71 with associated T2DM. In this work, we find elevated levels of ceramides, sphingomyelins, diacyl and triacylglycerols, fatty acids, and phosphoethanolamines in morbid obese vs normal weight. Conversely, decreased levels of acylcarnitines, bile acids, lyso-phosphatidylcholines, phosphatidylcholines (PC), phosphatidylinositols, and phosphoethanolamine PE (O-38:4) were noted. Furthermore, comparing morbid obese women with T2DM vs metabolically healthy MO, a distinct lipid profile emerged, featuring increased levels of metabolites: deoxycholic acid, diacylglycerol DG (36:2), triacylglycerols, phosphatidylcholines, phosphoethanolamines, phosphatidylinositols, and lyso-phosphatidylinositol LPI (16:0). To conclude, analysing both comparatives, we observed decreased levels of deoxycholic acid, PC (34:3), and PE (O-38:4) in morbid obese women vs normal-weight. Conversely, we found elevated levels of these lipids in morbid obese women with T2DM vs metabolically healthy MO. These profiles of metabolites could be explored for the research as potential markers of metabolic risk of T2DM in morbid obese women.

Dynamic Simulations of Interaction of the PEG-DPPE Micelle-Encapsulated Short-Chain Ceramides with the Raft-Included Membrane.

The lipid raft subdomains in cancer cell membranes play a key role in signal transduction, biomolecule recruitment, and drug transmembrane transport. Augmented membrane rigidity due to the formation of a lipid raft is unfavorable for the entry of drugs, a limiting factor in clinical oncology. The short-chain ceramide (CER) has been reported to promote drug entry into membranes and disrupt lipid raft formation, but the underlying mechanism is not well understood. We recently explored the carrier-membrane fusion dynamics of PEG-DPPE micelles in delivering doxorubicin (DOX). Based on the phase-segregated membrane model composed of DPPC/DIPC/CHOL/GM1/PIP2, we aim to explore the dynamic mechanism of the PEG-DPPE micelle-encapsulating DOXs in association with the raft-included cell membrane modulated by C8 acyl tail CERs. The results show that the lipid raft remains integrated and DOX-resistant subjected to free DOXs and the micelle-encapsulating ones. Addition of CERs disorganizes the lipid raft by pushing CHOL aside from DPPC. It subsequently allows for a good permeability for PEG-DPPE micelle-encapsulated DOXs, which penetrate deeper as CER concentration increases. GM1 is significant in guiding drugs' redistributing between bilayer phases, and the anionic PIP2 further helps DOXs attain the inner bilayer surface. These results elaborate on the perturbing effect of CERs on lipid raft stability, which provides a new comprehensive approach for further design of drug delivery systems.

A Novel Non-Psychoactive Fatty Acid from a Marine Snail, Conus inscriptus, Signals Cannabinoid Receptor 1 (CB1) to Accumulate Apoptotic C16:0 and C18:0 Ceramides in Teratocarcinoma Cell Line PA1.

The cannabinoid-type I (CB1) receptor functions as a double-edged sword to decide cell fate: apoptosis/survival. Elevated CB1 receptor expression is shown to cause acute ceramide accumulation to meet the energy requirements of fast-growing cancers. However, the flip side of continual CB1 activation is the initiation of a second ceramide peak that leads to cell death. In this study, we used ovarian cancer cells, PA1, which expressed CB1, which increased threefold when treated with a natural compound, bis(palmitoleic acid) ester of a glycerol (C2). This novel compound is isolated from a marine snail, Conus inscriptus, using hexane and the structural details are available in the public domain PubChem database (ID: 14275348). The compound induced two acute ceramide pools to cause G0/G1 arrest and killed cells by apoptosis. The compound increased intracellular ceramides (C:16 to 7 times and C:18 to 10 times), both of which are apoptotic inducers in response to CB1 signaling and thus the compound is a potent CB1 agonist. The compound is not genotoxic because it did not induce micronuclei formation in non-cancerous Chinese hamster ovarian (CHO) cells. Since the compound induced the cannabinoid pathway, we tested if there was a psychotropic effect in zebrafish models, however, it was evident that there were no observable neurobehavioral changes in the treatment groups. With the available data, we propose that this marine compound is safe to be used in non-cancerous cells as well as zebrafish. Thus, this anticancer compound is non-toxic and triggers the CB1 pathway without causing psychotropic effects.

Intravenous immunoglobulin alleviates Japanese encephalitis virus-induced peripheral neuropathy by inhibiting the ASM/ceramide pathway.

Japanese encephalitis virus (JEV) infection is considered a global public health emergency. Severe peripheral neuropathy caused by JEV infection has increased disability and mortality rates in recent years. Because there are very few therapeutic options for JEV infection, prompt investigations of the ability of clinically safe, efficacious and globally available drugs to inhibit JEV infection and ameliorate peripheral neuropathy are urgently needed. In this study, we found that high doses of intravenous immunoglobulin, a function inhibitor of acid sphingomyelinase (FIASMA), inhibited acid sphingomyelinase (ASM) and ceramide activity in the serum and sciatic nerve of JEV-infected rats, reduced disease severity, reversed electrophysiological and histological abnormalities, significantly reduced circulating proinflammatory cytokine levels, inhibited Th1 and Th17 cell proliferation, and suppressed the infiltration of inflammatory CD4 + cells into the sciatic nerve. It also maintained the peripheral nerve-blood barrier without causing severe clinical side effects. In terms of the potential mechanisms, ASM was found to participate in immune cell differentiation and to activate immune cells, thereby exerting proinflammatory effects. Therefore, immunoglobulin is a FIASMA that reduces abnormal immune responses and thus targets the ASM/ceramide system to treat peripheral neuropathy caused by JEV infection.

Ceramide sorting into non-vesicular transport is independent of acyl chain length in budding yeast.

The transport of ceramide from the endoplasmic reticulum (ER) to the Golgi is a key step in the synthesis of complex sphingolipids, the main building blocks of the plasma membrane. In yeast, ceramide is transported to the Golgi either through ATP-dependent COPII vesicles of the secretory pathway or by ATP-independent non-vesicular transport that involves tethering proteins at ER-Golgi membrane contact sites. Studies in both mammalian and yeast cells reported that vesicular transport mainly carries ceramide containing very long chain fatty acids, while the main mammalian non-vesicular ceramide transport protein CERT only transports ceramides containing short chain fatty acids. However, if non-vesicular ceramide transport in yeast similarly favors short chain ceramides remained unanswered. Here we employed a yeast GhLag1 strain in which the endogenous ceramide synthase is replaced by the cotton-derived GhLag1 gene, resulting in the production of short chain C18 rather than C26 ceramides. We show that block of vesicular transport through ATP-depletion or the use of temperature-sensitive sec mutants caused a reduction in inositolphosphorylceramide (IPC) synthesis to similar extent in WT and GhLag1 backgrounds. Since the remaining IPC synthesis is a readout for non-vesicular ceramide transport, our results indicate that non-vesicular ceramide transport is neither blocked nor facilitated when only short chain ceramides are present. Therefore, we propose that the sorting of ceramide into non-vesicular transport is independent of acyl chain length in budding yeast.

Effects on keratinocytes of the traditional combination of herb extract (Royal Oji Complex) implicated the improvement of young children's skin moisture and barrier.

BACKGROUND: Natural products are often friendly and can be used on children's skin after systematic and careful research. Therefore, in this study, the Royal Oji Complex (ROC), a product with natural ingredients, was used to study their effectiveness on keratinocytes taken from the skin of children from 0 to 3 years old. METHOD: Normal human epidermal keratinocytes and tissue-isolated keratinocytes (TIKC) from young donors were treated with three different concentrations of ROC: 0.1, 1, and 10 ppm. The mRNA expression of the epidermal barrier's essential genes, such as hyaluronic acid synthase 3 (Has3), involucrin (IVL), loricrin (LOR), and claudin-1 (CLD1) was investigated using qRT-PCR. Ceramide content was measured by ELISA, with retinoic acid (R.A.) and amarogentin (AMA) serving as positive controls. RESULTS: ROC significantly elevated HAS3 gene expression in HEKn cells, especially at 10 ppm, indicating potential advantages for skin hydration in young infants. IVL increased at first but decreased as ROC concentrations increased. LOR was upregulated at lower ROC concentrations but reduced at higher doses. CLD1 gene expression increased considerably in HEKn but reduced with increasing ROC doses. Ceramide concentration increased somewhat but not significantly at 10 ppm. CONCLUSION: ROC shows potential in altering keratinocyte gene expression, with unique responses in HEKn and TIKC from young donors. While changes in ceramide content were insignificant, these results help to comprehend ROC's multiple effects on young children's skin.

Association of cardiac biomarkers with long-term cardiovascular events in a community cohort.

MATERIALS AND METHODS: The study assessed major adverse cardiac events (MACE) (myocardial infarction, coronary artery bypass graft, percutaneous intervention, stroke, and death. Cox proportional hazards models assessed apolipoprotein AI (ApoA1), apolipoprotein B (ApoB), ceramide score, cystatin C, galectin-3 (Gal3), LDL-C, Non-HDL-C, total cholesterol (TC), N-terminal B-type natriuretic peptide (NT proBNP), high-sensitivity cardiac troponin (HscTnI) and soluble interleukin 1 receptor-like 1. In adjusted models, Ceramide score was defined by from N-palmitoyl-sphingosine [Cer(16:0)], N-stearoyl-sphingosine [Cer(18:0)], N-nervonoyl-sphingosine [Cer(24:1)] and N-lignoceroyl-sphingosine [Cer(24:0)]. Multi-biomarker models were compared with C-statistics and Integrated Discrimination Index (IDI). RESULTS: A total of 1131 patients were included. Adjusted NT proBNP per 1 SD resulted in a 31% increased risk of MACE/death (HR = 1.31) and a 31% increased risk for stroke/MI (HR = 1.31). Adjusted Ceramide per 1 SD showed a 13% increased risk of MACE/death (HR = 1.13) and a 29% increased risk for stroke/MI (HR = 1.29). These markers added to clinical factors for both MACE/death (p = 0.003) and stroke/MI (p = 0.034). HscTnI was not a predictor of outcomes when added to the models. DISCUSSION: Ceramide score and NT proBNP improve the prediction of MACE and stroke/MI in a community primary prevention cohort.

In a community cohort, where a wide range of biomarkers were evaluated, Ceramide score provided additive value over traditional cardiac risk factors alone for predicting stroke/MI. NT ProBNP provided additive value in prediction of MACE/death. Other biomarkers failed to improve the discrimination of these models.

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

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

Bile acid metabolism and signaling in health and disease: molecular mechanisms and therapeutic targets.

Bile acids, once considered mere dietary surfactants, now emerge as critical modulators of macronutrient (lipid, carbohydrate, protein) metabolism and the systemic pro-inflammatory/anti-inflammatory balance. Bile acid metabolism and signaling pathways play a crucial role in protecting against, or if aberrant, inducing cardiometabolic, inflammatory, and neoplastic conditions, strongly influencing health and disease. No curative treatment exists for any bile acid influenced disease, while the most promising and well-developed bile acid therapeutic was recently rejected by the FDA. Here, we provide a bottom-up approach on bile acids, mechanistically explaining their biochemistry, physiology, and pharmacology at canonical and non-canonical receptors. Using this mechanistic model of bile acids, we explain how abnormal bile acid physiology drives disease pathogenesis, emphasizing how ceramide synthesis may serve as a unifying pathogenic feature for cardiometabolic diseases. We provide an in-depth summary on pre-existing bile acid receptor modulators, explain their shortcomings, and propose solutions for how they may be remedied. Lastly, we rationalize novel targets for further translational drug discovery and provide future perspectives. Rather than dismissing bile acid therapeutics due to recent setbacks, we believe that there is immense clinical potential and a high likelihood for the future success of bile acid therapeutics.

mARC1 in MASLD: Modulation of lipid accumulation in human hepatocytes and adipocytes.

BACKGROUND: Mutations in the gene MTARC1 (mitochondrial amidoxime-reducing component 1) protect carriers from metabolic dysfunction-associated steatohepatitis (MASH) and cirrhosis. MTARC1 encodes the mARC1 enzyme, which is localized to the mitochondria and has no known MASH-relevant molecular function. Our studies aimed to expand on the published human genetic mARC1 data and to observe the molecular effects of mARC1 modulation in preclinical MASH models. METHODS AND RESULTS: We identified a novel human structural variant deletion in MTARC1, which is associated with various biomarkers of liver health, including alanine aminotransferase levels. Phenome-wide Mendelian Randomization analyses additionally identified novel putatively causal associations between MTARC1 expression, and esophageal varices and cardiorespiratory traits. We observed that protective MTARC1 variants decreased protein accumulation in in vitro overexpression systems and used genetic tools to study mARC1 depletion in relevant human and mouse systems. Hepatocyte mARC1 knockdown in murine MASH models reduced body weight, liver steatosis, oxidative stress, cell death, and fibrogenesis markers. mARC1 siRNA treatment and overexpression modulated lipid accumulation and cell death consistently in primary human hepatocytes, hepatocyte cell lines, and primary human adipocytes. mARC1 depletion affected the accumulation of distinct lipid species and the expression of inflammatory and mitochondrial pathway genes/proteins in both in vitro and in vivo models. CONCLUSIONS: Depleting hepatocyte mARC1 improved metabolic dysfunction-associated steatotic liver disease-related outcomes. Given the functional role of mARC1 in human adipocyte lipid accumulation, systemic targeting of mARC1 should be considered when designing mARC1 therapies. Our data point to plasma lipid biomarkers predictive of mARC1 abundance, such as Ceramide 22:1. We propose future areas of study to describe the precise molecular function of mARC1, including lipid trafficking and subcellular location within or around the mitochondria and endoplasmic reticulum.

Intranasal administration of ceramide liposome suppresses allergic rhinitis by targeting CD300f in murine models.

Allergic rhinitis (AR) is caused by type I hypersensitivity reaction in the nasal tissues. The interaction between CD300f and its ligand ceramide suppresses immunoglobulin E (IgE)-mediated mast cell activation. However, whether CD300f inhibits the development of allergic rhinitis (AR) remains elusive. We aimed to investigate the roles of CD300f in the development of AR and the effectiveness of intranasal administration of ceramide liposomes on AR in murine models. We used ragweed pollen-induced AR models in mice. Notably, CD300f deficiency did not significantly influence the ragweed-specific IgE production, but increased the frequency of mast cell-dependent sneezing as well as the numbers of degranulated mast cells and eosinophils in the nasal tissues in our models. Similar results were also obtained for MCPT5-exprssing mast cell-specific loss of CD300f. Importantly, intranasal administration of ceramide liposomes reduced the frequency of sneezing as well as the numbers of degranulated mast cells and eosinophils in the nasal tissues in AR models. Thus, CD300f-ceramide interaction, predominantly in mast cells, alleviates the symptoms and progression of AR. Therefore, intranasal administration of ceramide liposomes may be a promising therapeutic approach against AR by targeting CD300f.

Models of the Three-Component Bilayer of Stratum Corneum: A Molecular Simulation Study.

The construction of the stratum corneum (SC) is crucial to the problems of transdermal drug delivery. SC consists of the keratinocyte layers and the lipid matrix surrounding it. Among them, the lipid matrix is the barrier for many exogenous molecules, mainly composed of ceramides (CERs), free fatty acids (FFA), and cholesterol (CHOL). In this work, we developed single-component (CERs, CER-NS, and CER-EOS) and six three-component models, and each model was simulated by using the GROMOS-54A7 force field. Short-period phase (SPP) and long-period phase (LPP) systems were established separately, and area per lipid (APL), thickness, order of carbon chain (SCD), and density distribution were analyzed. The transition of CER-NS and CER-EOS in LPP was observed. The results of hydrogen bonds in the lipid systems indicated that a strong hydrogen-bond network was formed between the skin-lipid bilayers. Umbrella sampling method simulations were performed to calculate the free energy change of ethanol moving into the skin-lipid bilayer. The results revealed that ethanol molecules pulled some water molecules into the membrane when they passed through SPP-1. Our findings provided some insights and models of the stratum corneum that could be used for the subsequent mechanism of macromolecule permeation through membranes in drugs, cosmetics, and so on.

Circulating ceramide levels and ratios in Emirati youth under 18 years: associations with cardiometabolic risk factors.

BACKGROUND: Circulating ceramide (Cer) drives various pathological processes associated with cardiovascular diseases, liver illness, and diabetes mellitus. Although recognized as predictors of cardiometabolic diseases (CMD) in research and clinical settings, their potential for predicting CMD risk in individuals under 18 remains unexplored. OBJECTIVES: This study was designed to utilize Liquid Chromatography-Mass Spectrometry (LC-MS/MS) methodology to determine the biological reference ranges for Cer in plasma samples of Emirati children and develop a risk assessment score (CERT-1) based on Cer concentrations. METHODS: Using LC-MS/MS, we developed a method to measure five Cer species in plasma samples of 582 Emirati participants aged 5-17. We used the circulating concentrations of these Cer to determine their reference intervals in this population. We employed traditional statistical analyses to develop a risk score (CERT-1) and assess the association between Cer levels and conventional biomarkers of CMD. RESULTS: We validated a high-throughput methodology using LC-MS/MS to quantify five Cer species in human plasma. Reference values for this population (n = 582) were quantified: CerC16:0 (0.12-0.29 µmol/L), CerC18:0 (0.019-0.067 µmol/L), CerC22:0 (0.102-0.525 µmol/L), CerC24:0 (0.65-1.54 µmol/L) and CerC24:1 (0.212-0.945 µmol/L). We devised a risk assessment score (CERT-1) based on plasma Cer content in the study participants, showing that 72.5% have low to moderate risk and 9.3% are at a higher risk of developing CMD. Our analyses also revealed a significant correlation (P < 0.05) between this score and the conventional risk factors linked to CMD, indicating its potential clinical implication. CONCLUSION: This study presents a clinical-scaled LC-MS/MS methodology for assessing clinically relevant Cer, setting reference ranges, and developing a risk score (CERT-1) for young Emirati individuals. Our findings can enhance primary risk prediction and inform the management and follow-up of CMD from an early age.

Proapoptotic effects of ceranib-2 in combination with radiation therapy on human breast cancer cells.

OBJECTIVE: Strategies for cancer therapy involve radiation therapy (RT), which accounts for about 40% of all cancer treatment types. As to current chemotherapeutics, cancer cells also develop resistance that remains a clinical problem, such as disease recurrence. Recent studies focused on understanding the molecular mechanisms of radiation-induced cell death. Conventional RT aims at treatment with a single fraction per day of 8-30 Gy per fraction. Radiotherapy increases intracellular ceramide levels that trigger cell death. Additionally, increasing intracellular ceramide by radiation may restore therapeutic sensitivity to cancer treatments. Drugs that inhibit ceramide-metabolizing enzymes like ceramidases are expected to be radiotherapy sensitizers. MATERIALS AND METHODS: In this research, we investigated the proapoptotic effects of SRS alone and in combination with ceranib-2, a ceramidase inhibitor in human breast adenocarcinoma cells. The molecular mechanism of action of RT and ceranib-2 was investigated on MCF-7 cells exposed to 13 µM ceranib-2 for 24 hours following 20 Gy radiation using MTT, radiotherapy, and annexin-V analyses. RESULTS: Results indicated that the dose of 20 Gy radiation induces apoptosis on human breast cancer cells with and without co-treatment with ceranib-2 by causing cytotoxicity in the cells. Based on the results of ceranib-2 exposure, it can be concluded that the mechanism of action may rely on an increase of intracellular ceramides, also called apoptotic lipids. CONCLUSIONS: The study results suggest that co-treatment of human breast adenocarcinoma cells with a ceramidase inhibitor, ceranib-2, and a high dose of radiation of 20 Gy exerted cytotoxicity and apoptosis and might be a solid, potent alternative to current therapy strategies.

Regio-specific lipid fingerprinting of edible sea cucumbers using LC/MS.

Sea cucumbers are a rich source of bioactive compounds and are gaining popularity as nutrient-rich seafood. They are consumed as a whole organism in Pacific regions. However, limited data are available on the comparison of their lipid composition and nutritional value. In this study, untargeted liquid chromatography/mass spectrometry was applied to comprehensively profile lipids in the skin, meat, and intestinal contents of three color-distinct edible sea cucumbers. Multivariate principal component analysis revealed that the lipid composition of the intestinal contents of red, black, and blue sea cucumbers differs from that of skin, and meats. Polyunsaturated fatty acids (PUFAs) are abundant in the intestinal contents, followed by meats of sea cucumber. Lipid nutritional quality assessments based on fatty acid composition revealed a high P:S ratio, low index of atherogenicity, and high health promotion indices for the intestinal contents of red sea cucumber, suggesting its potential health benefits. In addition, hierarchical cluster analysis revealed that the intestinal contents of sea cucumbers were relatively high in PUFA-enriched phospholipids and lysophospholipids. Ceramides are abundant in black skin, blue meat, and red intestinal content samples. Overall, this study provides the first insights into a comprehensive regio-specific profile of the lipid content of sea cucumbers and their potential use as a source of lipid nutrients in food and nutraceuticals.

Roles and therapeutic targeting of ceramide metabolism in cancer.

BACKGROUND: Ceramides are sphingolipids that act as signaling molecules involved in regulating cellular processes including apoptosis, proliferation, and metabolism. Deregulation of ceramide metabolism contributes to cancer development and progression. Therefore, regulation of ceramide levels in cancer cells is being explored as a new approach for cancer therapy. SCOPE OF THE REVIEW: This review discusses the multiple roles of ceramides in cancer cells and strategies to modulate ceramide levels for cancer therapy. Ceramides attenuate cell survival signaling and metabolic pathways, while activating apoptotic mechanisms, making them tumor-suppressive. Approaches to increase ceramide levels in cancer cells include using synthetic analogs, inhibiting ceramide degradation, and activating ceramide synthesis. We also highlight combination therapies such as use of ceramide modulators with chemotherapies, immunotherapies, apoptosis inducers, and anti-angiogenics, which offer synergistic antitumor effects. Additionally, we also describe ongoing clinical trials evaluating ceramide nanoliposomes and analogs. Finally, we discuss the challenges of these therapeutic approaches including the complexity of ceramide metabolism, targeted delivery, cancer heterogeneity, resistance mechanisms, and long-term safety. MAJOR CONCLUSIONS: Ceramide-based therapy is a potentially promising approach for cancer therapy. However, overcoming hurdles in pharmacokinetics, specificity, and resistance is needed to optimize its efficacy and safety. This requires comprehensive preclinical/clinical studies into ceramide signaling, formulations, and combination therapies. Ceramide modulation offers opportunities for developing novel cancer treatments, but a deeper understanding of ceramide biology is vital to advance its clinical applications.

Sphingolipid biosynthetic inhibitor L-Cycloserine prevents oxidative-stress-mediated death in an in vitro model of photoreceptor-derived 661W cells.

Oxidative stress plays a pivotal role in the pathogenesis of several neurodegenerative diseases. Retinal degeneration causes irreversible death of photoreceptor cells, ultimately leading to vision loss. Under oxidative stress, the synthesis of bioactive sphingolipid ceramide increases, triggering apoptosis in photoreceptor cells and leading to their death. This study investigates the effect of L-Cycloserine, a small molecule inhibitor of ceramide biosynthesis, on sphingolipid metabolism and the protection of photoreceptor-derived 661W cells from oxidative stress. The results demonstrate that treatment with L-Cycloserine, an inhibitor of Serine palmitoyl transferase (SPT), markedly decreases bioactive ceramide and associated sphingolipids in 661W cells. A nontoxic dose of L-Cycloserine can provide substantial protection of 661W cells against H2O2-induced oxidative stress by reversing the increase in ceramide level observed under oxidative stress conditions. Analysis of various antioxidant, apoptotic and sphingolipid pathway genes and proteins also confirms the ability of L-Cycloserine to modulate these pathways. Our findings elucidate the generation of sphingolipid mediators of cell death in retinal cells under oxidative stress and the potential of L-Cycloserine as a therapeutic candidate for targeting ceramide-induced degenerative diseases by inhibiting SPT. The promising therapeutic prospect identified in our findings lays the groundwork for further validation in in-vivo and preclinical models of retinal degeneration.

Lipidomics reveals the significance and mechanism of the cellular ceramide metabolism for rotavirus replication.

As one of the most important causative agents of severe gastroenteritis in children, piglets, and other young animals, species A rotaviruses have adversely impacted both human health and the global swine industry. Vaccines against rotaviruses (RVs) are insufficiently effective, and no specific treatment is available. To understand the relationships between porcine RV (PoRV) infection and enterocytes in terms of the cellular lipid metabolism, we performed an untargeted liquid chromatography mass spectrometry (LC-MS) lipidomics analysis of PoRV-infected IPEC-J2 cells. Herein, a total of 451 lipids (263 upregulated lipids and 188 downregulated lipids), spanning sphingolipid, glycerolipid, and glycerophospholipids, were significantly altered compared with the mock-infected group. Interestingly, almost all the ceramides among these lipids were upregulated during PoRV infection. LC-MS analysis was used to validated the lipidomics data and demonstrated that PoRV replication increased the levels of long-chain ceramides (C16-ceramide, C18-ceramide, and C24-ceramide) in cells. Furthermore, we found that these long-chain ceramides markedly inhibited PoRV infection and that their antiviral actions were exerted in the replication stage of PoRV infection. Moreover, downregulation of endogenous ceramides with the ceramide metabolic inhibitors enhanced PoRV propagation. Increasing the levels of ceramides by the addition of C6-ceramide strikingly suppressed the replication of diverse RV strains. We further found that the treatment with an apoptotic inhibitor could reverse the antiviral activity of ceramide against PoRV replication, demonstrating that ceramide restricted RV infection by inducing apoptosis. Altogether, this study revealed that ceramides played an antiviral role against RV infection, providing potential approaches for the development of antiviral therapies.IMPORTANCERotaviruses (RVs) are among the most important zoonosis viruses, which mainly infected enterocytes of the intestinal epithelium causing diarrhea in children and the young of many mammalian and avian species. Lipids play an essential role in viral infection. A comprehensive understanding of the interaction between RV and lipid metabolism in the enterocytes will be helpful to control RV infection. Here, we mapped changes in enterocyte lipids following porcine RV (PoRV) infection using an untargeted lipidomics approach. We found that PoRV infection altered the metabolism of various lipid species, especially ceramides (derivatives of the sphingosine). We further demonstrated that PoRV infection increased the accumulation of ceramides and that ceramides exerted antiviral effects on RV replication by inducing apoptosis. Our findings fill a gap in understanding the alterations of lipid metabolism in RV-infected enterocytes and highlight the antiviral effects of ceramides on RV infection, suggesting potential approaches to control RV infection.

Cadmium exacerbates liver injury by remodeling ceramide metabolism: Multiomics and laboratory evidence.

Cadmium (Cd) is a toxic heavy metal that primarily targets the liver. Cd exposure disrupts specific lipid metabolic pathways; however, the underlying mechanisms remain unclear. This study aimed to investigate the lipidomic characteristics of rat livers after Cd exposure as well as the potential mechanisms of Cd-induced liver injury. Our analysis of established Cd-exposed rat and cell models showed that Cd exposure resulted in liver lipid deposition and hepatocyte damage. Lipidomic detection, transcriptome sequencing, and experimental analyses revealed that Cd mainly affects the sphingolipid metabolic pathway and that the changes in ceramide metabolism are the most significant. In vitro experiments revealed that the inhibition of ceramide synthetase activity or activation of ceramide decomposing enzymes ameliorated the proapoptotic and pro-oxidative stress effects of Cd, thereby alleviating liver injury. In contrast, the exogenous addition of ceramide aggravated liver injury. In summary, Cd increased ceramide levels by remodeling ceramide synthesis and catabolism, thereby promoting hepatocyte apoptosis and oxidative stress and ultimately aggravating liver injury. Reducing ceramide levels can serve as a potential protective strategy to mitigate the liver toxicity of Cd. This study provides new evidence for understanding Cd-induced liver injury at the lipidomic level and insights into the health risks and toxicological mechanisms associated with Cd.