Ceramide Content Research Articles

Clinical evaluation of a topical ceramide lotion on skin hydration and skin barrier in healthy volunteers with dry skin

Objectives: Ceramides are epidermal lipids important for normal skin barrier function. Reduced ceramide content is associated with dry skin and atopic dermatitis (AD) due to increased transepidermal water loss (TEWL) and worsening symptoms. Topical ceramide application restores barrier function and improves hydration by reducing TEWL. The objective of the present study was to evaluate the effect of a test product on skin hydration and TEWL on the volar forearms of adults, by comparing measurements at 12 and 24 h post-application. Materials and Methods: This single-center and non-randomized study evaluated the effect of Venusia CeraPlus lotion on volar forearms in volunteers with dry skin. Primary outcomes included MoistureMeterSC reading for hydration and VapoMeter reading for TEWL at 12- and 24-h post-application, comparing occluded and unoccluded sites. Results: The study enrolled 32 subjects with a mean age of 34.03 ± 9.41 years, out of which 87.5% were female. Application of Venusia CeraPlus lotion enhanced skin hydration compared to the control under both occluded and unoccluded conditions. Hydration increased from 13.57 ± 2.67 at baseline to 31.61 ± 11.34 at 12 h and 36.36 ± 10.77 at 24 h under occlusion (P < 0.001). TEWL was lower at the test site, with VapoMeter readings of 3.08 ± 2.32 at 24 h compared to 4.54 ± 2.76 at the control site, suggesting that the test product effectively preserved skin hydration and reduced TEWL compared to the control. No adverse reactions were reported. Conclusion: This study demonstrates that Venusia CeraPlus Lotion effectively maintains optimal skin hydration for up to 24 h and enhances barrier function, making it a promising option for treating dry skin and improving overall skin health in adults.

Effect of changes in skin properties due to diabetes mellitus on the titration period of transdermal fentanyl: single-center retrospective study and diabetic animal model study

BackgroundIn the dose titration of transdermal fentanyl to prevent unrelieved pain, it is important to consider not only dose adjustment, but also the titration period, which is influenced by the time required to reach the steady state. Many patients with cancer pain experience comorbidities that might affect the skin properties and influence transdermal absorption. We hypothesized that skin changes due to diabetes mellitus (DM) would affect the titration period of transdermal fentanyl. We conducted a retrospective study and diabetic animal model study to test this hypothesis.MethodsIn the retrospective study, the titration period was defined in terms of “dose change” and “number of rescue opioids” in patients initiated on transdermal fentanyl. Multiple logistic regression analysis was performed to analyze the relation between the titration period and comorbidities, including DM. In the diabetic animal model study, intercellular lipids of stratum corneum (SC) were analyzed in Goto-Kakizaki (GK) rats, a model of DM, and the pharmacokinetics of intravenously or transdermally administered fentanyl was examined.ResultsIn the retrospective study, the titration period ranged from 5 to 39 days (n = 387), and the patients taking a longer period (6 days or more) was significantly related to in patients with unspecified DM: AOR (95% confidence interval), 0.438 (0.217–0.884). In the diabetic animal model study, the ceramides (CERs) content in the SC was decreased by approximately 30% in GK rats compared to Wistar rats. The absorption rate constant (ka) of fentanyl administered transdermally was increased approximately 1.4-fold in GK rats, though there was no difference in transdermal bioavailability (F) or systemic clearance (CLtot).ConclusionOur results suggest that the steady state of transdermally administered fentanyl is reached sooner in cancer patients with DM as a comorbidity. Earlier pain assessment and dose adjustment may be possible in these patients.

Modulation of the Plasma Lipidomic Profile in Piglets Fed Polar Lipid-Rich Diets.

Background: Polar lipids from dairy are novel sources of energy that may replace other dietary lipids and impact plasma lipidomic profiles in piglets. This study evaluated the impact of feeding diets rich in polar lipids on the plasma lipidome of piglets during the weaning period. Material and Methods: Weaned male piglets (n = 240; 21 days of age; 6.3 ± 0.5 kg of BW) were blocked by initial weight and distributed into 48 pens of five animals each in a complete randomized block design with a 2 × 3 factorial arrangement of treatments as follows: a plant-based diet rich in neutral lipids from soybeans (24 pens; SD) or a polar lipid-rich diet by-product of cheese making (24 pens; PD) from weaning until the 21st day of the nursery phase. Within each diet group, animals received one of three milk replacers (MR; 0.5 L/d/animal) for the first 7 days after weaning: (1) commercial MR containing animal and coconut lipids (CO); (2) polar lipid-based MR (PO); or (3) soybean lipids-based MR (SO). Results: The PD diet group increased the plasma concentrations of sphingolipids, phospholipids, and cholesterol esters, but did not impact the concentrations of glycerolipids (GLs). Both the PO and CO milk replacers increased the plasma concentrations of ceramide, acyl-chain phosphatidyl choline, and cholesterol esters. The plasma concentrations of GLs containing 18-carbon fatty acids such as 18:0, 18:1, 18:2, and 18:3, were higher in SD, whereas GLs containing 16:0 and 20:3 were higher in PD. Conclusions: In summary, the diet lipid type significantly modulated the plasma lipid composition in piglets 7 days after weaning. The dietary inclusion of polar lipids in diets for growing pigs can modulate the plasma lipidomic profile, relative to plant-based diets rich in soybean lipids. Cost may be a major consideration when using these lipids in pig diets. Their health benefits need to be further characterized in other models of stress and inflammation.

Prognostic Value of Ceramide Dynamics in Patients with Acute Coronary Syndrome.

A dynamic study of ceramide concentrations and their association with recurrent event risk could enhance our understanding of cardiovascular complications. To assess the prognostic value of ceramide concentrations (Cer(d18:1/16:0), Cer(d18:1/18:0), Cer(d18:1/24:1), Cer(d18:1/24:0)) and their dynamics in combination with standard clinical and laboratory parameters and therapeutic interventions in ACS patients. Among 110 ACS patients, triple blood sampling was performed for targeted lipidomic analysis using high-performance liquid chromatography-tandem mass spectrometry. All ceramide concentrations peaked at admission and decreased by the 3rd day of hospitalization and at the 3-month follow-up. The difference between Cer(d18:1/18:0) concentration 3 months after hospital discharge and its baseline value on admission was strongly associated with recurrent events, independent of prior statin treatment. The association of the Cer(d18:1/18:0) change from 3rd day of hospitalization and its baseline concentration on admission with prognosis varied depending on the glycemic profile.

Sparstolonin B Reduces Estrogen-Dependent Proliferation in Cancer Cells: Possible Role of Ceramide and PI3K/AKT/mTOR Inhibition.

Background: The aim of this study was to determine the effect of Sparstolonin B (SsnB) on cell proliferation and apoptosis in human breast cancer (MCF-7) and human ovarian epithelial cancer (OVCAR-3) cell lines in the presence and absence of estradiol hemihydrate (ES). Phosphoinositol-3 kinase (PI3K), phosphorylated protein kinase B alpha (p-AKT), phosphorylated mTOR (mechanistic target of rapamycin) signaling proteins, and sphingomyelin/ceramide metabolites were also measured within the scope of the study. Methods: The anti-proliferative effects of SsnB therapy were evaluated over a range of times and concentrations. Cell proliferation was determined by measuring the Proliferating Cell Nuclear Antigen (PCNA). PCNA was quantified by ELISA and cell distribution was assessed by immunofluorescence microscopy. MTT analysis was used to test the vitality of the cells, while LC-MS/MS was used to analyze the amounts of ceramides (CERs), sphingosine-1-phosphate (S1P), and sphingomyelins (SMs). TUNEL labeling was used to assess apoptosis, while immunofluorescence staining and enzyme-linked immunosorbent assay (ELISA) were used to measure the levels of PI3K, p-AKT, and p-mTOR proteins. Results: Sparstolonin B administration significantly decreased cell viability in MCF-7 and OVCAR-3 cells both in the presence and absence of ES, while it did not cause toxicity in healthy human fibroblasts. In comparison to controls, cancer cells treated with SsnB showed a significant drop in the levels of S1P, PI3K, p-AKT, and p-mTOR. In cancer cells cultured with SsnB, a significant increase in intracellular concentrations of C16-C24 CERs and apoptosis was observed. Conclusions: SsnB downregulated the levels of S1P, PI3K, p-AKT, and p-mTOR while reducing cell proliferation and promoting ceramide buildup and apoptosis.

Trophoblast-specific overexpression of adiponectin receptor 2 causes fetal growth restriction in pregnant mice.

Maternal obesity in pregnancy is strongly associated with complications such as fetal overgrowth and infants of obese mothers have an increased risk to develop obesity, diabetes, and cardiovascular disease later in life. However, the underlying mechanisms are not well established. Circulating levels of adiponectin are low in obese pregnant women and maternal circulating adiponectin is negatively associated with birth weight. We have reported that normalizing maternal adiponectin in obese pregnant mice prevents placental dysfunction, fetal overgrowth, and programming of offspring cardio-metabolic disease. However, the mechanistic link between maternal adiponectin, placental function, and fetal growth remains to be established. We hypothesized that trophoblast-specific overexpression of the adiponectin receptor 2 (Adipor2) in healthy pregnant mice inhibits placental mTORC1 signaling and nutrient transport, resulting in fetal growth restriction. Using lentiviral transduction of blastocysts with a mammalian gene expression lentiviral vector for up-regulation of Adipor2 (Adipor2-OX), we achieved a ~ 3-fold increase in placenta Adipor2 mRNA levels and a 2-fold increase of the ADIPOR2 protein in the trophoblast plasma membrane. Placenta-specific Adipor2-OX increased placental peroxisome proliferator-activated receptor-α phosphorylation, ceramide synthase expression and ceramide concentrations. Furthermore, Adipor2-OX inhibited placental mTORC1 signaling and reduced invivo placental transport of glucose and amino acids. Lastly, Adipor2-OX reduced fetal weight by 11%. These data provide mechanistic evidence that placental Adipor2 signaling directly affects fetal growth. We propose that low circulating adiponectin in maternal obesity causes fetal overgrowth and programs the offspring for cardio-metabolic disease mediated by a direct effect on placental function.

Concordant inter-laboratory derived concentrations of ceramides in human plasma reference materials via authentic standards

In this community effort, we compare measurements between 34 laboratories from 19 countries, utilizing mixtures of labelled authentic synthetic standards, to quantify by mass spectrometry four clinically used ceramide species in the NIST (National Institute of Standards and Technology) human blood plasma Standard Reference Material (SRM) 1950, as well as a set of candidate plasma reference materials (RM 8231). Participants either utilized a provided validated method and/or their method of choice. Mean concentration values, and intra- and inter-laboratory coefficients of variation (CV) were calculated using single-point and multi-point calibrations, respectively. These results are the most precise (intra-laboratory CVs ≤ 4.2%) and concordant (inter-laboratory CVs < 14%) community-derived absolute concentration values reported to date for four clinically used ceramides in the commonly analyzed SRM 1950. We demonstrate that calibration using authentic labelled standards dramatically reduces data variability. Furthermore, we show how the use of shared RM can correct systematic quantitative biases and help in harmonizing lipidomics. Collectively, the results from the present study provide a significant knowledge base for translation of lipidomic technologies to future clinical applications that might require the determination of reference intervals (RIs) in various human populations or might need to estimate reference change values (RCV), when analytical variability is a key factor for recall during multiple testing of individuals.

The Effect of FTY720 on Sphingolipid Imbalance and Cognitive Decline in Aged EFAD Mice.

During Alzheimer's disease (AD) progression, there is a decline in the bioactive sphingolipid sphingosine-1-phosphate (S1P). Previous research showed that FTY720, an S1P mimetic, prevented cognitive decline and reduced ceramide levels in transgenic mice with familial AD carrying the human APOE4 gene (E4FAD) at 6-7 months of age. The objective of this study is to explore the protective effects of FTY720 at late-stage AD. Male mice aged 9.5 to 10.5 months were orally administered FTY720 (0.1 mg/kg) via oral gavage for 6 weeks. A pre-test of water maze was used for evaluating the pathological status. After 4 weeks of administration, memory, locomotion, and anxiety were assessed. Cortex samples were analyzed for amyloid-β (Aβ) and sphingolipid levels. Compared with APOE3 mice, APOE4, E3FAD and E4FAD mice exhibited significant memory deficits. After 6 weeks administration, FTY720 did not alleviate memory deficits in EFAD mice. Lipid analysis revealed that S1P was significantly reduced in EFAD mice (E3FAD or E4FAD) compared to controls (APOE3 and APOE4). Ceramide level alterations were predominantly dependent on APOE isoforms rather than AD transgenes. Interestingly, Cer (d18 : 1/22 : 1) was elevated in APOE4 mice compared to APOE3, and FTY720 reduced it. E4FAD and APOE4 mice exhibited significant spatial memory deficits and higher ceramide concentrations compared to APOE3 mice. FTY720 did not reverse memory deficits in E4FAD and APOE4 mice but reduced specific ceramide species. This study provides insights into the association between sphingolipids and APOE4 in advanced AD stages, exploring potential therapeutic targeting of sphingolipid metabolism.

Effect of Weight Loss on Skeletal Muscle Bioactive Lipids in People With Obesity and Type 2 Diabetes.

Muscle sn-1,2-diacylglycerol (DAG) and C18:0 ceramide accumulation in sarcolemmal and mitochondrial compartments have been proposed to regulate muscle insulin sensitivity. Here, we evaluated whether weight loss-induced improvements in insulin sensitivity were associated with changes in muscle sn-1,2-DAG and ceramide content in people with obesity and type 2 diabetes. We measured skeletal muscle insulin sensitivity, assessed by using the hyperinsulinemic-euglycemic clamp procedure in conjunction with stable isotopically labeled glucose tracer infusion, and skeletal muscle sn-1,2-DAG and ceramide contents by using liquid chromatography-tandem mass spectrometry after subcellular fractionation and DAG isomer separation in 14 adults with obesity and type 2 diabetes before and after marked (18.6 ± 2.1%) weight loss. Whole-body insulin sensitivity doubled after weight loss. Sarcolemmal sn-1,2-DAG and C18:0 ceramide contents after weight loss were not different than values before weight loss. In contrast, mitochondrial/ER C18:0 ceramide content decreased by ∼20% after weight loss (from 2.16 ± 0.08 to 1.71 ± 0.13 nmol/g, P<0.005). These results suggest a decrease in muscle mitochondrial/ER C18:0 ceramide content could contribute to the beneficial effect of weight loss on skeletal muscle insulin sensitivity.

Sphingolipid homeostasis: How do cells know when enough is enough? Implications for plant pathogen responses.

Sphingolipid homeostatic regulation is important for balancing plant life and death. Plant cells finely tune sphingolipid biosynthesis to ensure sufficient levels to support growth through their basal functions as major components of endomembranes and the plasma membrane. Conversely, accumulation of sphingolipid biosynthetic intermediates, long-chain bases (LCBs) and ceramides, is associated with programmed cell death. Limiting these apoptotic intermediates is important for cell viability, while overriding homeostatic regulation permits cells to generate elevated LCBs and ceramides to respond to pathogens to elicit the hypersensitive response in plant immunity. Key to sphingolipid homeostasis is serine palmitoyltransferase (SPT), an endoplasmic reticulum-associated, multi-subunit enzyme catalyzing the first step in the biosynthesis of LCBs, the defining feature of sphingolipids. Across eukaryotes, SPT interaction with its negative regulator Orosomucoid-like (ORM) is critical for sphingolipid biosynthetic homeostasis. The recent cryo-electron microscopy structure of the Arabidopsis SPT complex indicates that ceramides bind ORMs to competitively inhibit SPT activity. This system provides a sensor for intracellular ceramide concentrations for sphingolipid homeostatic regulation. Combining the newly elucidated Arabidopsis SPT structure and mutant characterization, we present a model for the role of the 2 functionally divergent Arabidopsis ceramide synthase classes to produce ceramides that form repressive (trihydroxy LCB-ceramides) or nonrepressive (dihydroxy LCB-ceramides) ORM interactions to influence SPT activity. We describe how sphingolipid biosynthesis is regulated by the interplay of ceramide synthases with ORM-SPT when "enough is enough" and override homeostatic suppression when "enough is not enough" to respond to environmental stimuli such as microbial pathogen attack.

Changes in ceramide concentrations and their association with clinical and anamnestic parameters in patients with acute coronary syndrome

Background. Given the metabolic dynamics of acute coronary syndrome (ACS), the study of molecular lipid metabolites is of particular importance because their composition most rapidly reflects the changes occurring at the time of the acute event. Several prospective studies have demonstrated the prognostic value of ceramides, however, the study of their dynamics and association with clinical parameters of patients with ACS is underrepresented. Objective. To investigate changes in Cer(d18:1/16:0), Cer(d18:1/18:0), Cer(d18:1/24:0), and Cer(d18:1/24:1) ceramide concentrations and their association with clinical and anamnestic parameters in patients with ACS. Design and methods. Lipidomic analysis by high-performance liquid chromatography tandem mass spectrometry was performed among 110 patients with ACS. Results. At admission to the hospital the ceramide level was the highest and decreased with time (for all p &lt; 0.001). The peculiarities of ceramide concentrations depending on clinical and anamnestic parameters of patients with ACS are shown. Ceramides were found to be weakly correlated with age and high-sensitivity troponin I, and moderately correlated with lipid profile at different time periods. For the first time, information on Cer(d18:1/16:0) and Cer(d18:1/24:0) levels depending on disease debut, Cer(d18:1/16:0) concentration depending on duration of the pain attack, and Cer(d18:1/18:0) level depending on the presence of family history of cardiovascular disease is presented. Conclusion. The dynamics of ceramide concentrations over time and the peculiarities of their levels depending on the clinical and anamnestic parameters of patients with ACS expand the understanding of the importance of lipid metabolites.

Placental ceramide content is decreased in maternal obesity and GDM, independent of fetal sex.

Placental ceramide content is decreased in maternal obesity and GDM, independent of fetal sex.

Basal and post-stress ceramide-based risk score CERT1 predicts all-cause mortality and nonfatal myocardial infarction in patients with suspected or established coronary artery disease undergoing stress myocardial perfusion scintigraphy

Background and aimWe examined whether a plasma ceramide-based risk score (CERT1 score), a newly proposed tool for cardiovascular risk prediction, is associated with an increased risk of all-cause mortality and nonfatal myocardial infarction in patients with suspected or known coronary artery disease (CAD). Methods and resultsWe studied 167 ambulatory patients who consecutively underwent stress myocardial perfusion scintigraphy (MPS) for clinical reasons in 2017 (at baseline) and then followed for a median of 6 years (inter-quartile range: 4.7–6.6 years). For the calculation of the CERT1 score, both before and after stress MPS, we measured three specific plasma ceramide concentrations [Cer(d18:1/16:0), Cer(d18:1/18:0) and Cer(d18:1/24:1)] and their ratio to Cer(d18:1/24:0) using a targeted liquid chromatography-tandem mass spectrometry assay. The primary outcome of the study was a composite of all-cause mortality or nonfatal myocardial infarction. During a median of 6 years, a total of 50 events occurred (26 all-cause deaths and 24 nonfatal myocardial infarctions). There was a significant association between pre-stress CERT1 risk categories (high vs. low risk) at baseline and the risk of developing the primary composite outcome (unadjusted HR 1.78, 95% CI 1.02–3.14). This risk remained significant after adjustment for age, sex, smoking, diabetes, pre-existing CAD, left ventricular ejection fraction, and stress-induced inducible myocardial ischemia on MPS (adjusted HR 2.28, 95% CI 1.17–4.41, p = 0.015). Almost identical results were observed for post-stress CERT1 risk categories. ConclusionsPre-stress and post-stress CERT1 high-risk categories at baseline were strongly associated with an increased long-term risk of all-cause mortality or nonfatal myocardial infarction in patients with suspected or established CAD.

Dried Blood Spot Metabolome Features of Ischemic-Hypoxic Encephalopathy: A Neonatal Rat Model.

Hypoxic-ischemic encephalopathy (HIE) is a severe neurological disorder caused by perinatal asphyxia with significant consequences. Early recognition and intervention are crucial, with therapeutic hypothermia (TH) being the primary treatment, but its efficacy depends on early initiation of treatment. Accurately assessing the HIE severity in neonatal care poses challenges, but omics approaches have made significant contribution to understanding its complex pathophysiology. Our study further explores the impact of HIE on the blood metabolome over time and investigated changes associated with hypothermia's therapeutic effects. Using a rat model of hypoxic-ischemic brain injury, we comprehensively analyzed dried blood spot samples for fat-soluble compounds using HPLC-MS. Our research shows significant changes in the blood metabolome after HIE, with a particularly rapid recovery of lipid metabolism observed. Significant changes in lipid metabolites were observed after 3 h of HIE, including increases in ceramides, carnitines, certain fatty acids, phosphocholines, and phosphoethanolamines, while sphingomyelins and N-acylethanolamines (NAEs) decreased (p < 0.05). Furthermore, NAEs were found to be significant features in the OPLS-DA model for HIE diagnosis, with an area under the curve of 0.812. TH showed a notable association with decreased concentrations of ceramides. Enrichment analysis further corroborated these observations, showing modulation in several key metabolic pathways, including arachidonic acid oxylipin metabolism, eicosanoid metabolism via lipooxygenases, and leukotriene C4 synthesis deficiency. Our study reveals dynamic changes in the blood metabolome after HIE and the therapeutic effects of hypothermia, which improves our understanding of the pathophysiology of HIE and could lead to the development of new rapid diagnostic approaches for neonatal HIE.

Investigating a New Way to Assess Metabolic Risk in Pregnant Females with Prior RYGB Surgery.

Obesity in pregnancy is linked to adverse clinical outcomes such as gestational diabetes. Recently, a risk score calculated by different ceramide concentrations was recognized as a new way to investigate cardiovascular risk. The aim was to analyze if the ceramide risk score and cardiometabolic risk vary between normal-weight, obese, and females with prior Roux-en-Y bypass surgery (RYGB) during pregnancy. Three cohorts were investigated: first, 25 pregnant females with a history of RYGB; second, 19 with preconception BMI ≥ 35 kg/m2; and third, 19 normal-weight (preconception BMI < 25 kg/m2). Around the 24th to 28th weeks of gestation routine laboratory assessments, 3 h 75 g oral and intravenous glucose tolerance tests were carried out. The correlation of ceramide risk scores and ceramide ratios (Cer(d18:1/18:0)/Cer(d18:1/16:0)) with metabolic parameters was analyzed via Pearson correlation. The cohorts were compared via ANOVA and unpaired t-tests. The RYGB cohort had lower ceramide risk scores and ratios compared to obese pregnant females (7.42 vs. 9.34, p = 0.025; 0.33 vs. 0.47, p < 0.001). Ceramide risk score and ratio were found to correlate negatively with insulin sensitivity (measured with the Matsuda (r = -0.376, p = 0.031; r = -0.455, p = 0.008) and calculated sensitivity index (r = -0.358, p = 0.044; r = -0.621, p < 0.001) in females without RYGB. The ceramide risk score correlated positively with body fat in RYGB females (r = 0.650, p = 0.012). We found that females after RYGB have lower ceramide risk scores and ceramide ratios compared to obese pregnant females, possibly indicating lower metabolic risk.

Fine-tuned protein-lipid interactions in biological membranes: exploration and implications of the ORMDL-ceramide negative feedback loop in the endoplasmic reticulum.

Biological membranes consist of a lipid bilayer in which integral membrane proteins are embedded. Based on the compositional complexity of the lipid species found in membranes, and on their specific and selective interactions with membrane proteins, we recently suggested that membrane bilayers can be best described as "finely-tuned molecular machines." We now discuss one such set of lipid-protein interactions by describing a negative feedback mechanism operating in the de novo sphingolipid biosynthetic pathway, which occurs in the membrane of the endoplasmic reticulum, and describe the atomic interactions between the first enzyme in the pathway, namely serine palmitoyl transferase, and the product of the fourth enzyme in the pathway, ceramide. We explore how hydrogen-bonding and hydrophobic interactions formed between Asn13 and Phe63 in the serine palmitoyl transferase complex and ceramide can influence the ceramide content of the endoplasmic reticulum. This example of finely-tuned biochemical interactions raises intriguing mechanistic questions about how sphingolipids and their biosynthetic enzymes could have evolved, particularly in light of their metabolic co-dependence.

Decreased placental ceramide content relates to adaptations in mitochondrial function in gestational diabetes mellitus

Decreased placental ceramide content relates to adaptations in mitochondrial function in gestational diabetes mellitus

Targeted metabolomics identifies accurate CSF metabolite biomarkers for the differentiation between COVID-19 with neurological involvement and CNS infections with neurotropic viral pathogens

BackgroundCOVID-19 is primarily considered a respiratory tract infection, but it can also affect the central nervous system (CNS), which can result in long-term sequelae. In contrast to CNS infections by classic neurotropic viruses, SARS-CoV-2 is usually not detected in cerebrospinal fluid (CSF) from patients with COVID-19 with neurological involvement (neuro-COVID), suggesting fundamental differences in pathogenesis.MethodsTo assess differences in CNS metabolism in neuro-COVID compared to CNS infections with classic neurotropic viruses, we applied a targeted metabolomic analysis of 630 metabolites to CSF from patients with (i) COVID-19 with neurological involvement [n = 16, comprising acute (n = 13) and post-COVID-19 (n = 3)], (ii) viral meningitis, encephalitis, or myelitis (n = 10) due to herpes simplex virus (n = 2), varicella zoster virus (n = 6), enterovirus (n = 1) and tick-borne encephalitis virus (n = 1), and (iii) aseptic neuroinflammation (meningitis, encephalitis, or myelitis) of unknown etiology (n = 21) as additional disease controls.ResultsStandard CSF parameters indicated absent or low neuroinflammation in neuro-COVID. Indeed, CSF cell count was low in neuro-COVID (median 1 cell/µL, range 0–12) and discriminated it accurately from viral CNS infections (AUC = 0.99) and aseptic neuroinflammation (AUC = 0.98). 32 CSF metabolites passed quality assessment and were included in the analysis. Concentrations of differentially abundant (fold change ≥|1.5|, FDR ≤ 0.05) metabolites were both higher (9 and 5 metabolites) and lower (2 metabolites) in neuro-COVID than in the other two groups. Concentrations of citrulline, ceramide (d18:1/18:0), and methionine were most significantly elevated in neuro-COVID. Remarkably, triglyceride TG(20:1_32:3) was much lower (mean fold change = 0.09 and 0.11) in neuro-COVID than in all viral CNS infections and most aseptic neuroinflammation samples, identifying it as highly accurate biomarker with AUC = 1 and 0.93, respectively. Across all samples, TG(20:1_32:3) concentration correlated only moderately with CSF cell count (ρ = 0.65), protein concentration (ρ = 0.64), and Q-albumin (ρ = 0.48), suggesting that its low levels in neuro-COVID CSF are only partially explained by less pronounced neuroinflammation.ConclusionsThe results suggest that CNS metabolite responses in neuro-COVID differ fundamentally from viral CNS infections and aseptic neuroinflammation and may be used to discover accurate diagnostic biomarkers in CSF and to gain insights into differences in pathophysiology between neuro-COVID, viral CNS infections and aseptic neuroinflammation.

Palmitic acid induces β-cell ferroptosis by activating ceramide signaling pathway

Individuals with type 2 diabetes mellitus frequently display heightened levels of palmitic acid (PA) in their serum, which may lead to β-cell damage. The involvement of ferroptosis, a form of oxidative cell death in lipotoxic β-cell injury remains uncertain. Here, we have shown that PA induces intracellular lipid peroxidation, increases intracellular Fe2+ content and decreases intracellular glutathione peroxidase 4 (GPX4) expression. Furthermore, PA causes distinct changes in pancreatic islets and INS-1 cells, such as mitochondrial atrophy and increased membrane density. Furthermore, the presence of the ferroptosis inhibitor has a significant mitigating effect on PA-induced β-cell damage. Mechanistically, PA increased ceramide content and c-Jun N-terminal kinase (JNK) phosphorylation. The ceramide synthase inhibitor effectively attenuated PA-induced β-cell damage and GPX4/Fe2+ abnormalities, while inhibiting JNK phosphorylation. Additionally, the JNK inhibitor SP600125 improved PA-induced cell damage. In conclusion, by promoting ceramide synthesis, PA inhibited GPX4 expression and increased intracellular Fe2+ to induce β-cell ferroptosis. Moreover, JNK may be a downstream mechanism of ceramide-triggered lipotoxic ferroptosis in β-cells.

The skin barrier and microbiome in infantile atopic dermatitis development: can skincare prevent onset?

Atopic dermatitis (AD), a prevalent Th2-dominant skin disease, involves complex genetic and environmental factors, including mutations in the Filaggrin gene and dysbiosis of skin microbiota characterized by an increased abundance of Staphylococcus aureus. Our recent findings emphasize the pivotal role of the skin barrier's integrity and microbial composition in infantile AD and allergic diseases. Early skin dysbiosis predisposes infants to AD, suggesting targeted skincare practices as a preventive strategy. The effects of skincare interventions, particularly the application of moisturizers with the appropriate molar concentration of ceramides, cholesterol, and fatty acids, play a crucial role in restoring the skin barrier. Notably, our study revealed that appropriate skincare can reduce Streptococcus abundance while supporting Cutibacterium acnes presence, thus directly linking skincare practices to microbial modulation in neonatal skin. Despite the mixed outcomes of previous Randomized Controlled Trials on the efficacy of moisturizers in AD prevention, our research points to the potential of skincare intervention as a primary preventive method against AD by minimizing the impact of genetic and environmental factors. Furthermore, our research supports the notion that early aggressive management of eczema may reduce the incidence of food allergies, highlighting the necessity for multifaceted prevention strategies that address both the skin barrier and immune sensitization. By focusing on repairing the skin barrier and adjusting the skin's microbiome from birth, we propose a novel perspective on preventing infantile AD and allergic diseases, opening new avenues for future studies, and practices in allergy prevention.