Circulating Ceramides- Are Origins Important for Sphingolipid Biomarkers and Treatments?

Molecular pathological characteristics and mechanisms of the liver in metabolic disease-susceptible transgenic pigs

AIMS

This study aimed to explore the molecular pathological mechanisms of the liver in metabolic disease-susceptible transgenic pigs via multiomics analysis.

MATERIALS AND METHODS

The triple-transgenic (PNPLA3I148M-GIPRdn-hIAPP) pig model (TG pig) was successfully constructed in our laboratory via the CRISPR/Cas9 technique previously described. Wild-type (WT) pigs and TG pigs after 2 or 12 months of high-fat and high-sucrose diet (HFHSD) induction (WT2, TG2, WT12, and TG12 groups, respectively) were used as materials. The transcriptome, metabolome, and lipidome were used to investigate the molecular mechanisms of the liver in pigs.

KEY FINDINGS

The TG2 pigs presented mild metaflammation and insulin resistance (IR) which was similar to WT12 pigs. Compared with the other three groups, the TG12 pigs presented severe hepatocyte ballooning, fat deposition, and portal area fibrosis. The transcriptome data suggested that the TG2 pigs presented upregulated gene expression in the extracellular matrix (ECM). The TG12 pigs presented more severe metaflammation and exhibited imbalanced glycolipid metabolism. Interestingly, genes such as ETNPPL, GABBR2, and BMP8B might be key regulatory targets for liver injury. The metabolome and lipidome suggested that long-chain polyunsaturated fatty acids (LCPUFAs) and phospholipids with corresponding LCPUFAs were remodelled. Importantly, bis(monoacylglycerol) phosphates (BMPs) and sulfatides (SLs) could be the key regulatory metabolites in liver injury.

SIGNIFICANCE

ETNPPL, GABBR2, and BMP8B might be potential therapeutic targets for liver injury. BMPs and SLs might be biomarkers for the diagnosis and treatment of liver diseases.

High-fat feeding drives the intestinal production and assembly of C16:0 ceramides in chylomicrons

Consumption of a diet rich in saturated fat increases lipid absorption from the intestine, assembly into chylomicrons, and delivery to metabolic tissues via the lymphatic and circulatory systems. Accumulation of ceramide lipids, composed of sphingosine and a fatty acid, in metabolic tissues contributes to the pathogenesis of cardiovascular diseases, type 2 diabetes mellitus and cancer. Using a mesenteric lymph duct cannulated rat model, we showed that ceramides are generated by the intestine and assembled into chylomicrons, which are transported via the mesenteric lymphatic system. A lipidomic screen of intestinal-derived chylomicrons identified a diverse range of fatty acid, sphingolipid, and glycerolipid species that have not been previously detected in chylomicrons, including the metabolically deleterious C16:0 ceramide that increased in response to high-fat feeding in rats and human high-lipid meal replacement enteral feeding. In conclusion, high-fat feeding increases the export of intestinal-derived C16:0 ceramide in chylomicrons, identifying a potentially unknown mechanism through which ceramides are transported systemically to contribute to metabolic dysfunction.

Associations of plasma sphingolipids with measures of insulin sensitivity, β-cell function, and incident diabetes in Japanese Americans

BACKGROUND AND AIMS

To prospectively investigate associations of plasma sphingolipids with insulin sensitivity, β-cell function, and incident diabetes in the Japanese American Community Diabetes Study.

METHODS AND RESULTS

Baseline plasma samples from adults without diabetes (n = 349; mean age 56.7 years, 51 % men) were assayed for circulating ceramide and sphingomyelin species. Adjusted regression models examined cross-sectional and longitudinal associations with insulin sensitivity (HOMA2-%S), β-cell function (oral disposition index: DIo) and with incident diabetes over 5 years follow-up. Concentrations of four species (Ceramide C16:0, C18:0, C20:0, and C22:0) were inversely associated with HOMA2-%S at baseline (all P values < 0.05, Q values < 0.05) and change in HOMA2-%S over 5 years (all P values < 0.05, Q values < 0.05). No sphingolipids were associated with baseline or change in DIo. Of the four species associated with HOMA2-%S, only Ceramide C18:0 was significantly and positively associated with incident diabetes (RR/1SD 1.44, 95 % CI 1.10-1.80, P = 0.006, Q = 0.024). The association of plasma Ceramide C18:0 with the risk of diabetes was partially mediated by change in HOMA2-%S between baseline and 5 years (mediation proportion: 61.5 %, 95 % CI 21.1%-212.5 %).

CONCLUSION

Plasma Ceramide C18:0 was associated with higher risk of incident diabetes which was partially mediated through a decrease in insulin sensitivity between baseline and five years. Circulating Ceramide C18:0 could be a potential biomarker for identifying those at risk of developing diabetes.

Inter-organ crosstalk during development and progression of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is characterized by tissue-specific insulin resistance and pancreatic β-cell dysfunction, which result from the interplay of local abnormalities within different tissues and systemic dysregulation of tissue crosstalk. The main local mechanisms comprise metabolic (lipid) signalling, altered mitochondrial metabolism with oxidative stress, endoplasmic reticulum stress and local inflammation. While the role of endocrine dysregulation in T2DM pathogenesis is well established, other forms of inter-organ crosstalk deserve closer investigation to better understand the multifactorial transition from normoglycaemia to hyperglycaemia. This narrative Review addresses the impact of certain tissue-specific messenger systems, such as metabolites, peptides and proteins and microRNAs, their secretion patterns and possible alternative transport mechanisms, such as extracellular vesicles (exosomes). The focus is on the effects of these messengers on distant organs during the development of T2DM and progression to its complications. Starting from the adipose tissue as a major organ relevant to T2DM pathophysiology, the discussion is expanded to other key tissues, such as skeletal muscle, liver, the endocrine pancreas and the intestine. Subsequently, this Review also sheds light on the potential of multimarker panels derived from these biomarkers and related multi-omics for the prediction of risk and progression of T2DM, novel diabetes mellitus subtypes and/or endotypes and T2DM-related complications.

Ceramide d18:1/24:1 as a potential biomarker to differentiate obesity subtypes with unfavorable health outcomes

BACKGROUND

The criteria for metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO) remain controversial. This research aimed to identify a potential biomarker to differentiate the subtypes of obesity.

METHODS

The study conducted a lipidomic evaluation of ceramide in the serum of 77 Chinese adults who had undergone hyperinsulinemic-euglycemic clamps. These adults were divided into three groups according to the clinical data: normal weight control group (N = 21), MHO (N = 20), and MUO (N = 36).

RESULTS

The serum Cer d18:1/24:1 level in the MHO group was lower than that in the MUO group. As the Cer d18:1/24:1 level increased, insulin sensitivity decreased, and the unfavorable parameters increased in parallel. Multivariate logistic regression analysis revealed that serum Cer d18:1/24:1 levels were independently correlated with MUO in obesity. Individuals with higher levels of Cer d18:1/24:1 also had an elevated risk of cardiovascular disease. Most ceramide subtype levels increased in obesity compared to normal-weight individuals, but the levels of serum Cer d18:0/18:0 and Cer d18:1/16:0 decreased in obesity.

CONCLUSIONS

The relationships between ceramide subtypes and metabolic profiles might be heterogeneous in populations with different body weights. Cer d18:1/24:1 could be a biomarker that can be used to differentiate MUO from MHO, and to better predict who will develop unfavorable health outcomes among obese individuals.

TRIAL REGISTRATION

The First Affiliated Hospital of Nanjing Medical University's Institutional Review Board authorized this study protocol, and all participants provided written informed consent (2014-SR-003) prior to study entry.

Marked elevations in lung and plasma ceramide in COVID-19 linked to microvascular injury

The pathogenesis of the marked pulmonary microvasculature injury, a distinguishing feature of COVID-19 acute respiratory distress syndrome (COVID-ARDS), remains unclear. Implicated in the pathophysiology of diverse diseases characterized by endothelial damage, including ARDS and ischemic cardiovascular disease, ceramide and in particular palmitoyl ceramide (C16:0-ceramide) may be involved in the microvascular injury in COVID-19. Using deidentified plasma and lung samples from COVID-19 patients, ceramide profiling by mass spectrometry was performed. Compared with healthy individuals, a specific 3-fold C16:0-ceramide elevation in COVID-19 patient plasma was identified. Compared with age-matched controls, autopsied lungs of individuals succumbing to COVID-ARDS displayed a massive 9-fold C16:0-ceramide elevation and exhibited a previously unrecognized microvascular ceramide-staining pattern and markedly enhanced apoptosis. In COVID-19 plasma and lungs, the C16-ceramide/C24-ceramide ratios were increased and reversed, respectively, consistent with increased risk of vascular injury. Indeed, exposure of primary human lung microvascular endothelial cell monolayers to C16:0-ceramide-rich plasma lipid extracts from COVID-19, but not healthy, individuals led to a significant decrease in endothelial barrier function. This effect was phenocopied by spiking healthy plasma lipid extracts with synthetic C16:0-ceramide and was inhibited by treatment with ceramide-neutralizing monoclonal antibody or single-chain variable fragment. These results indicate that C16:0-ceramide may be implicated in the vascular injury associated with COVID-19.

The Key Role of Mitochondrial Function in Health and Disease

The role of mitochondrial function in health and disease has become increasingly recognized, particularly in the last two decades. Mitochondrial dysfunction as well as disruptions of cellular bioenergetics have been shown to be ubiquitous in some of the most prevalent diseases in our society, such as type 2 diabetes, cardiovascular disease, metabolic syndrome, cancer, and Alzheimer's disease. However, the etiology and pathogenesis of mitochondrial dysfunction in multiple diseases have yet to be elucidated, making it one of the most significant medical challenges in our history. However, the rapid advances in our knowledge of cellular metabolism coupled with the novel understanding at the molecular and genetic levels show tremendous promise to one day elucidate the mysteries of this ancient organelle in order to treat it therapeutically when needed. Mitochondrial DNA mutations, infections, aging, and a lack of physical activity have been identified to be major players in mitochondrial dysfunction in multiple diseases. This review examines the complexities of mitochondrial function, whose ancient incorporation into eukaryotic cells for energy purposes was key for the survival and creation of new species. Among these complexities, the tightly intertwined bioenergetics derived from the combustion of alimentary substrates and oxygen are necessary for cellular homeostasis, including the production of reactive oxygen species. This review discusses different etiological mechanisms by which mitochondria could become dysregulated, determining the fate of multiple tissues and organs and being a protagonist in the pathogenesis of many non-communicable diseases. Finally, physical activity is a canonical evolutionary characteristic of humans that remains embedded in our genes. The normalization of a lack of physical activity in our modern society has led to the perception that exercise is an "intervention". However, physical activity remains the modus vivendi engrained in our genes and being sedentary has been the real intervention and collateral effect of modern societies. It is well known that a lack of physical activity leads to mitochondrial dysfunction and, hence, it probably becomes a major etiological factor of many non-communicable diseases affecting modern societies. Since physical activity remains the only stimulus we know that can improve and maintain mitochondrial function, a significant emphasis on exercise promotion should be imperative in order to prevent multiple diseases. Finally, in populations with chronic diseases where mitochondrial dysfunction is involved, an individualized exercise prescription should be crucial for the "metabolic rehabilitation" of many patients. From lessons learned from elite athletes (the perfect human machines), it is possible to translate and apply multiple concepts to the betterment of populations with chronic diseases.

Sphingolipidomic profile and HDL subfractions in obese dyslipidemic type 2 diabetic patients

PURPOSE

The aim of the study was to investigate changes in serum sphingolipid levels and high density lipoprotein (HDL) subtypes with relation to low-density lipoprotein cholesterol (LDL-C), non-HDL-C and triglyceride (TG) levels in type 2 diabetes mellitus (T2DM) patients.

METHODS

Blood was obtained from 60 patients with T2DM. Levels of sphingosine-1-phosphate (S1P), C16-C24 sphingomyelins (SMs), C16-C24 ceramides (CERs), and C16 CER-1 P were determined by LC-MS/MS. Serum concentrations of cholesterol ester transfer protein (CETP), lecithin-cholesterol acyltransferase (LCAT) and apolipoprotein A-1 (apoA-I) were analyzed by enzyme-linked immunosorbent assay (ELISA). HDL subfraction analysis was performed by Disc polyacrylamide gel electrophoresis.

RESULTS

C16 SM, C24 SM, C24-C16 CER and C16 CER-1 P levels were significantly increased in T2DM patients with LDL-C above 160 mg/dL, compared to those with LDL-C below 100 mg/dL. A significant correlation was observed between C24:C16 SM, C24:C16 CER ratios and LDL-C, non HDL-C levels. Higher serum levels of C24 SM, C24-C18 CER and C24:C16 SM ratio was seen in obese T2DM patients (BMI>30) compared to those with BMI 27-30. Patients with fasting TG levels below 150 mg/dL had significantly increased HDL-large and significantly decreased HDL-small fractions compared to those with fasting TG levels above 150 mg/dL.

CONCLUSION

Obese dyslipidemic T2DM patients had increased levels of serum sphingomyelins, ceramides and HDL-small fractions. The ratio of serum C24:C16 SM, C24:C16 CER and long chain CER levels may be used as diagnostic and prognostic indicators of dyslipidemia in T2DM.

Characterization of a Neutral Sphingomyelinase Activity in Human Serum and Plasma

Alterations of sphingolipids and their metabolizing enzymes play a role in various diseases. However, peripheral biomarkers for such changes are limited. Particularly, in the increasingly reported involvement of neutral sphingomyelinase (NSM) with four described isoforms in tissues or cells, a peripheral marker is lacking. We here describe the detection of an NSM activity in human serum and plasma samples which hydrolyses fluorescently labeled sphingomyelin to ceramide in a time- and volume-dependent manner. Reaction rates were linear up to 10 days, and serum volumes above 2 vol-% were inhibitory. Biochemical properties were different from acid sphingomyelinase (ASM) with respect to detergent specificity (sodium deoxycholate), pH profile (pH 7-9), and cation dependence: Serum NSM activity was inhibited by EDTA ≥ 1 µM and restored in EDTA-anticoagulated plasma with the addition of ≥ 100 µM Co²⁺. It was independent of Mg²⁺, the typical cofactor of cellular NSM species, and even inhibited by [Mg²⁺] ≥ 20 mM. Serum NSM activity was not correlated with ASM activity and was independent of sex and age in 24 healthy adults. Since human peripheral NSM activity is very low and activities in rodents are even lower or undetectable, future research should aim to increase the reaction rate and determine the source of this enzymatic activity. The established activity could serve as a future biomarker or therapeutic target in diseases affected by sphingolipid derangements.

Ceramides in Autoimmune Rheumatic Diseases: Existing Evidence and Therapeutic Considerations for Diet as an Anticeramide Treatment

Autoimmune rheumatic diseases (AIRDs) constitute a set of connective tissue disorders and dysfunctions with akin clinical manifestations and autoantibody responses. AIRD treatment is based on a comprehensive approach, with the primary aim being achieving and attaining disease remission, through the control of inflammation. AIRD therapies have a low target specificity, and this usually propels metabolic disturbances, dyslipidemias and increased cardiovascular risk. Ceramides are implicated in inflammation through several different pathways, many of which sometimes intersect. They serve as signaling molecules for apoptosis, altering immune response and driving endothelial dysfunction and as regulators in the production of other molecules, including sphingosine 1-phosphate (S1P) and ceramide 1-phosphate (C1P). With lipid metabolism being severely altered in AIRD pathology, several studies show that the concentration and variety of ceramides in human tissues is altered in patients with rheumatic diseases compared to controls. As a result, many in vitro and some in vivo (animal) studies research the potential use of ceramides as therapeutic targets in rheumatoid arthritis (RA), ankylosing spondylitis, systemic lupus erythematosus, fibromyalgia syndrome, primary Sjögren's syndrome, systemic sclerosis, myositis, systemic vasculitis and psoriatic arthritis. Furthermore, the majority of ceramide synthesis is diet-centric and, as a result, dietary interventions may alter ceramide concentrations in the blood and affect health. Subsequently, more recently several clinical trials evaluated the possibility of distinct dietary patterns and nutrients to act as anti-ceramide regimes in humans. With nutrition being an important component of AIRD-related complications, the present review details the evidence regarding ceramide levels in patients with AIRDs, the results of anti-ceramide treatments and discusses the possibility of using medical nutritional therapy as a complementary anti-ceramide treatment in rheumatic disease.

Insights into the roles and pathomechanisms of ceramide and sphigosine-1-phosphate in nonalcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD), as one of the main causes of chronic liver disease worldwide, encompasses a spectrum of liver conditions that are not caused by other etiology, such as overt alcohol consumption, from simple steatosis to more aggressive non-alcoholic steatohepatitis (NASH) that involves liver inflammation and fibrosis, and to the lethal cirrhosis that may result in liver cancer and liver failure. The molecular mechanisms governing the transition from steatosis to NASH remain not fully understood, but the hepatic lipidome is extensively altered in the setting of steatosis and steatohepatitis, which also correlate with disease progression. With the tremendous advancement in the field of lipidomics in last two decades, a better understanding of the specific role of sphingolipids in fatty liver disease has taken shape. Among the numerous lipid subtypes that accumulate, ceramides are particularly impactful. On the one hand, excessive ceramides deposition in the liver cause hepatic steatosis. On the other hand, ceramides as lipotoxic lipid have significant effects on hepatic inflammation, apoptosis and insulin resistance that contribute to NAFLD. In this review, we summarize and evaluate current understanding of the multiple roles of ceramides in the onset of fatty liver disease and the pathogenic mechanisms underlying their effects, and we also discuss recent advances and challenges in pharmacological interventions targeting ceramide metabolism for the treatment of NAFLD.

Serum Ceramide Species Are Associated with Liver Cirrhosis and Viral Genotype in Patients with Hepatitis C Infection

Hepatitis C virus (HCV) infection affects ceramide metabolism, and, here, we have evaluated associations of eight serum ceramide species with viral load, viral genotype, and disease markers in 178 patients with chronic HCV. In this cohort, ceramide d18:1;O2/16:0 was higher in the serum of the 20 diabetic patients compared to the patients without this complication. Moreover, ceramide d18:1;O2/24:0 was negatively correlated with age. Of note, all but ceramide d18:1;O2/16:0 and 26:0 were diminished in the serum of patients with liver cirrhosis and, with the exception of ceramide d18:1;O2/16:0, were negatively correlated with the model for end-stage liver disease (MELD) score. Most of the serum ceramides are carried in low-density lipoprotein (LDL), which rises following effective direct-acting antiviral (DAA) therapy. Ceramide d18:1;O2/24:0 recovered in parallel with LDL, whereas ceramide d18:1;O2/18:0 declined. Genotype-3-infected patients had the lowest ceramide levels, which were comparable to other genotypes after DAA treatment. Notably, ceramide d18:1;O2/23:0 and 24:0 were negatively correlated with the MELD score in patients with liver cirrhosis at the end of DAA therapy. Long-chain (LC) ceramides show adverse effects, whereas very-long-chain (VL) species have protective functions in the liver. The ratio of VL/LC ceramides was higher in non-cirrhosis patients than cirrhosis patients and further increased at the end of therapy in this subgroup. In summary, our study shows that serum ceramide levels are related to liver cirrhosis and viral genotype. Whether the more favorable serum ceramide profile in non-cirrhosis patients, before and after DAA therapy, is of pathophysiological importance needs further investigation.

The Lard Works in Mysterious Ways: Ceramides in Nutrition-Linked Chronic Disease

Diet influences onset, progression, and severity of several chronic diseases, including heart failure, diabetes, steatohepatitis, and a subset of cancers. The prevalence and clinical burden of these obesity-linked diseases has risen over the past two decades. These metabolic disorders are driven by ectopic lipid deposition in tissues not suited for fat storage, leading to lipotoxic disruption of cell function and survival. Sphingolipids such as ceramides are among the most deleterious and bioactive metabolites that accrue, as they participate in selective insulin resistance, dyslipidemia, oxidative stress and apoptosis. This review discusses our current understanding of biochemical pathways controlling ceramide synthesis, production and action; influences of diet on ceramide levels; application of circulating ceramides as clinical biomarkers of metabolic disease; and molecular mechanisms linking ceramides to altered metabolism and survival of cells. Development of nutritional or pharmacological strategies to lower ceramides could have therapeutic value in a wide range of prevalent diseases.

Metabolomics Profiling of Vitamin D Status in Relation to Dyslipidemia

Vitamin D deficiency is a global disorder associated with several chronic illnesses including dyslipidemia and metabolic syndrome. The impact of this association with both dyslipidemia and vitamin D deficiency on metabolomics profile is not yet fully understood. This study analyses the metabolomics and lipidomic signatures in relation to vitamin D status and dyslipidemia. Metabolomics data were collected from Qatar Biobank database and categorized into four groups based on vitamin D and dyslipidemia status. Metabolomics multivariate analysis was performed using the orthogonal partial least square discriminate analysis (OPLS-DA) whilst linear models were used to assess the per-metabolite association with each of the four dyslipidemia/vitamin D combination groups. Our results indicate a high prevalence of vitamin D deficiency among the younger age group, while dyslipidemia was more prominent in the older group. A significant alteration of metabolomics profile was observed among the dyslipidemic and vitamin D deficient individuals in comparison with control groups. These modifications reflected changes in some key pathways including ceramides, diacylglycerols, hemosylceramides, lysophospholipids, phosphatidylcholines, phosphatidylethanol amines, and sphingomyelins. Vitamin D deficiency and dyslipidemia have a deep impact on sphingomyelins profile. The modifications were noted at the level of ceramides and are likely to propagate through downstream pathways.

Sphingolipids as Functional Food Components: Benefits in Skin Improvement and Disease Prevention

Sphingolipids are ubiquitous components in eukaryotic organisms and have attracted attention as physiologically functional lipids. Sphingolipids with diverse structures are present in foodstuffs as these structures depend on the biological species they are derived from, such as mammals, plants, and fungi. The physiological functions of dietary sphingolipids, especially those that improve skin barrier function, have recently been noted. In addition, the roles of dietary sphingolipids in the prevention of diseases, including cancer and metabolic syndrome, have been studied. However, the mechanisms underlying the health-improving effects of dietary sphingolipids, especially their metabolic fates, have not been elucidated. Here, we review dietary sphingolipids, including their chemical structures and contents in foodstuff; digestion, intestinal absorption, and metabolism; and nutraceutical functions, based on the available evidence and hypotheses. Further research is warranted to clearly define how dietary sphingolipids can influence human health.

The sphingolipidome of plasma, liver, and adipose tissues and its association with insulin response to oral glucose testing in Icelandic horses

Insulin dysregulation (ID) is a determinant of equine metabolic syndrome. Among the sphingolipids, ceramides contribute to the development of ID; however, the crosstalk between the liver and adipose tissue (AT) depots and the variation among AT depots in terms of ceramide metabolism are not well-understood. We aimed to characterize the sphingolipidome of plasma, liver, and AT (nuchal, NUAT; subcutaneous, SCAT; omental, OMAT; retroperitoneal, RPAT) and their associations with insulin response to oral glucose testing (OGT) in normoinsulinemic and hyperinsulinemic horses. Plasma, liver, and AT samples were collected from 12 Icelandic horses upon euthanasia and analyzed by liquid chromatography-mass spectrometry. Eighty-four targeted compounds were effectively quantified. Comparing the AT depots, greater (FDR < 0.05) ceramide, dihydroceramide, and sphingomyelin concentrations and lower glucosyl- and galactosyl-ceramides were found in RPAT and OMAT than in NUAT and SCAT. Hyperinsulinemic response to OGT was associated with sphingolipidome alterations primarily in the RPAT and OMAT, while the NUAT sphingolipidome did not show signs of ceramide accumulation, which was inconsistent with the previously proposed role of nuchal adiposity in ID. The plasma sphingolipidome was not significantly associated with the liver or AT sphingolipidomes, indicating that plasma profiles are determined by an interplay of various organs. Further, hepatic sphingolipid profiles were not correlated with the profiles of AT depots. Finally, statistically valid partial least square regression models predicting insulin response were found in the plasma (Q²= 0.58, R²= 0.98), liver (Q²= 0.64, R²= 0.74), and RPAT (Q²= 0.68, R²= 0.79) sphingolipidome, but not in the other adipose tissues.

Plasma Ceramide Levels Are Elevated in Patients With Early Coronary Atherosclerosis and Endothelial Dysfunction

Background

Elevated plasma ceramides are independent predictors of cardiovascular disease and mortality in patients with advanced epicardial coronary artery disease. Our understanding of plasma ceramides in early epicardial coronary artery disease, however, remains limited. We examined the role of plasma ceramides in early coronary atherosclerosis characterized by coronary endothelial dysfunction.

Methods and Results

Participants presenting with chest pain and nonobstructive epicardial coronary artery disease underwent coronary endothelial function. Patients (n=90) demonstrated abnormal coronary endothelial function with acetylcholine (≥20% decrease in coronary artery diameter or ≤50% increase in coronary blood flow). A total of 30 controls had normal coronary endothelial function. Concentrations of plasma ceramide 18:0 (P=0.038), 16:0 (P=0.021), and 24:0 (P=0.019) differed between participants with normal and abnormal coronary endothelial function. Ceramide 24:0 (odds ratio [OR], 2.23 [95% CI, 1.07–4.66]; P=0.033) and 16:0 (OR, 1.91×10⁶ [95% CI, 11.93–3.07×10¹¹]; P=0.018) were independently associated with coronary endothelial dysfunction. Among participants with endothelium‐dependent coronary dysfunction (n=78), ceramides 16:0 (OR, 5.17×10⁵ [95% CI, 2.83–9.44×10¹⁰]; P=0.033), 24:0 (OR, 2.98 [95% CI, 1.27–7.00]; P=0.012), and 24:1/24:0 (OR, 4.39×10⁻⁴ [95% CI, 4×10⁻⁷–0.48]; P=0.030) were more likely to be elevated.

Conclusions

The current study demonstrated an association between increased circulating ceramide levels and coronary endothelial dysfunction in the absence of epicardial coronary artery disease. This study supports the role of plasma ceramides as a potential biomarker or a therapeutic target for early coronary atherosclerosis in humans.

Lipid Metabolism Disorders in the Comorbid Course of Nonalcoholic Fatty Liver Disease and Chronic Obstructive Pulmonary Disease

Non-alcoholic fatty liver disease (NAFLD) is currently among the most common liver diseases. Unfavorable data on the epidemiology of metabolic syndrome and obesity have increased the attention of clinicians and researchers to the problem of NAFLD. The research results allow us to emphasize the systemicity and multifactoriality of the pathogenesis of liver parenchyma lesion. At the same time, many aspects of its classification, etiology, and pathogenesis remain controversial. Local and systemic metabolic disorders are also a part of the pathogenesis of chronic obstructive pulmonary disease and can influence its course. The present article analyzes the metabolic pathways mediating the links of impaired lipid metabolism in NAFLD and chronic obstructive pulmonary disease (COPD). Free fatty acids, cholesterol, and ceramides are involved in key metabolic and inflammatory pathways underlying the pathogenesis of both diseases. Moreover, inflammation and lipid metabolism demonstrate close links in the comorbid course of NAFLD and COPD.