Associations between specific plasma ceramides and severity of coronary-artery stenosis assessed by coronary angiography

Withdrawn: Combinatorial lipidomics and proteomics underscore erythrocyte lipid membrane aberrations in the development of adverse cardio-cerebrovascular complications in maintenance hemodialysis patients

This article has been withdrawn: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/policies/article-withdrawal). The authors reached out to the Publisher to alert the Publisher to incorrect text published in the article. After investigating the situation, the journal came to the conclusion that the wrong version of the file was sent by the authors to the production team during the proof stage and the misplaced text was not noticed by the authors when they approved the final version. After consulting with the Editor-in-Chief of the journal, the decision was made to withdraw the current version of the article.

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 AIM

We 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 RESULTS

We 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.

CONCLUSIONS

Pre-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.

Plasma 16:0 ceramide as a marker of cardiovascular risk estimated by carotid intima-media thickness in people with type 2 diabetes

AIM

New tools are required to better assess cardiovascular risk in individuals with type 2 diabetes mellitus (T2DM). Plasma ceramides emerge as promising candidates, given their substantial influence on the pathogenesis of both T2DM and atherosclerosis. The current study aimed to investigate whether plasma ceramides in patients with T2DM are a predictive factor for carotid intima-media thickness (CIMT), a well-established noninvasive marker for atherosclerosis that predicts adverse cardiovascular outcomes.

METHODS

A lipidomic analysis was carried out on the circulating ceramides of a large cohort consisting of 246 patients with T2DM who underwent a high-resolution real-time B ultrasonography to measure CIMT.

RESULTS

Both plasma 16:0 ceramide and the 16:0/24:0 ceramide ratio were positively associated with CIMT, even after adjustment for traditional cardiovascular risk factors [standardized β ± standard error: 0.168 ± 0.072 (P = 0.020) and 0.180 ± 0.068 (P = 0.009), respectively]. Similar independent associations were found with respect to the prediction of CIMT ≥ 0.80 mm [β = 8.07 ± 3.90 (P = 0.038) and 16.5 ± 7.0 (P = 0.019), respectively]. The goodness-of-fit for multivariate models in predicting CIMT was 5.7 and 7.6 times higher when plasma 16:0 ceramide or the 16:0/24:0 ceramide ratio were included in combination with traditional cardiovascular risk factors (P = 0.020 and 0.015, respectively). This reached a 3.1 and 10.0-fold increase regarding the ability to predict CIMT ≥ 0.80 mm (P = 0.039 and 0.008, respectively).

CONCLUSIONS

Our findings suggest that 16:0 ceramide and the 16:0/24:0 ceramide ratio may serve as plasma biomarkers to improve cardiovascular risk assessment in individuals with T2DM.

The Essence of Lipoproteins in Cardiovascular Health and Diseases Treated by Photodynamic Therapy

Lipids, together with lipoprotein particles, are the cause of atherosclerosis, which is a pathology of the cardiovascular system. In addition, it affects inflammatory processes and affects the vessels and heart. In pharmaceutical answer to this, statins are considered a first-stage treatment method to block cholesterol synthesis. Many times, additional drugs are also used with this method to lower lipid concentrations in order to achieve certain values of low-density lipoprotein (LDL) cholesterol. Recent advances in photodynamic therapy (PDT) as a new cancer treatment have gained the therapy much attention as a minimally invasive and highly selective method. Photodynamic therapy has been proven more effective than chemotherapy, radiotherapy, and immunotherapy alone in numerous studies. Consequently, photodynamic therapy research has expanded in many fields of medicine due to its increased therapeutic effects and reduced side effects. Currently, PDT is the most commonly used therapy for treating age-related macular degeneration, as well as inflammatory diseases, and skin infections. The effectiveness of photodynamic therapy against a number of pathogens has also been demonstrated in various studies. Also, PDT has been used in the treatment of cardiovascular diseases, such as atherosclerosis and hyperplasia of the arterial intima. This review evaluates the effectiveness and usefulness of photodynamic therapy in cardiovascular diseases. According to the analysis, photodynamic therapy is a promising approach for treating cardiovascular diseases and may lead to new clinical trials and management standards. Our review addresses the used therapeutic strategies and also describes new therapeutic strategies to reduce the cardiovascular burden that is induced by lipids.

Structure and mechanism of a eukaryotic ceramide synthase complex

Ceramide synthases (CerS) catalyze ceramide formation via N-acylation of a sphingoid base with a fatty acyl-CoA and are attractive drug targets for treating numerous metabolic diseases and cancers. Here, we present the cryo-EM structure of a yeast CerS complex, consisting of a catalytic Lac1 subunit and a regulatory Lip1 subunit, in complex with C26-CoA substrate. The CerS holoenzyme exists as a dimer of Lac1-Lip1 heterodimers. Lac1 contains a hydrophilic reaction chamber and a hydrophobic tunnel for binding the CoA moiety and C26-acyl chain of C26-CoA, respectively. Lip1 interacts with both the transmembrane region and the last luminal loop of Lac1 to maintain the proper acyl chain binding tunnel. A lateral opening on Lac1 serves as a potential entrance for the sphingoid base substrate. Our findings provide a template for understanding the working mechanism of eukaryotic ceramide synthases and may facilitate the development of therapeutic CerS modulators.

Searching for Atherosclerosis Biomarkers by Proteomics: A Focus on Lesion Pathogenesis and Vulnerability

Plaque rupture and thrombosis are the most important clinical complications in the pathogenesis of stroke, coronary arteries, and peripheral vascular diseases. The identification of early biomarkers of plaque presence and susceptibility to ulceration could be of primary importance in preventing such life-threatening events. With the improvement of proteomic tools, large-scale technologies have been proven valuable in attempting to unravel pathways of atherosclerotic degeneration and identifying new circulating markers to be utilized either as early diagnostic traits or as targets for new drug therapies. To address these issues, different matrices of human origin, such as vascular cells, arterial tissues, plasma, and urine, have been investigated. Besides, proteomics was also applied to experimental atherosclerosis in order to unveil significant insights into the mechanisms influencing atherogenesis. This narrative review provides an overview of the last twenty years of omics applications to the study of atherogenesis and lesion vulnerability, with particular emphasis on lipoproteomics and vascular tissue proteomics. Major issues of tissue analyses, such as plaque complexity, sampling, availability, choice of proper controls, and lipoproteins purification, will be raised, and future directions will be addressed.

Ceramides as Risk Markers for Future Cardiovascular Events and All-Cause Mortality in Long-standing Type 1 Diabetes

Ceramides are lipid molecules involved in inflammation-related signaling. Recent studies have shown that higher amounts of specific circulating ceramides and their ratios are associated with future development of cardiovascular (CV) disease (CVD). We examined the associations between serum ceramide levels with CVD, kidney failure, and all-cause mortality in individuals with long-standing type 1 diabetes (T1D). We included 662 participants with T1D and 6-year follow-up, with a mean age of 55 years and mean diabetes duration of 33 years. Baseline serum samples were analyzed using liquid chromatography-mass spectrometry. Six predefined ceramide levels were measured, and predefined ratios were calculated. Adjusted Cox regression analyses on ceramide levels in relation to future CV events (CVE), kidney failure, and all-cause mortality were performed, with and without adjustment for age, sex, BMI, LDL, triglycerides, systolic blood pressure, HbA1c, history of CVD, smoking status, statin use, estimated glomerular filtration rate (eGFR), and urinary albumin excretion rate (UAER). The ceramide ratio cer(d18:1/18:0)/cer(d18:1/24:0) was significantly associated with risk of CVE (hazard ratio [HR] = 1.33, P = 0.01) and all-cause mortality (HR = 1.48, P = 0.01) before and after adjustments. All five investigated ceramide ratios were associated with kidney failure, before adjusting for the kidney markers eGFR and UAER. In this study, we demonstrate specific ceramides and ratios associated with 6-year cardiovascular risk and all-cause mortality in a T1D cohort. This highlights the strength of ceramide association with vascular complications and presents a new potential tool for early risk assessment if validated in other cohorts.

ARTICLE HIGHLIGHTS

Improved tools for assessing risk for diabetes complication before onset will help in complication prevention. We investigated a set of six predefined ceramides and their ratios versus 6-year outcomes of cardiovascular events, kidney failure, and all-cause mortality in people with long-standing type 1 diabetes, using Cox regression with and without adjustment for potential confounders. We found that several ceramides and ceramide ratios associated with cardiovascular events and all-cause mortality. The ratio of cer(d18:1/18:0)/cer(d18:1/24:0) was an especially robust marker. These finding show that ceramides can be biomarkers of cardiovascular disease and all-cause mortality in individuals with long-standing type 1 diabetes.

Sphingosine-1-Phosphate Signaling in Cardiovascular Diseases

Sphingosine-1-phosphate (S1P) is an important sphingolipid molecule involved in regulating cardiovascular functions in physiological and pathological conditions by binding and activating the three G protein-coupled receptors (S1PR1, S1PR2, and S1PR3) expressed in endothelial and smooth muscle cells, as well as cardiomyocytes and fibroblasts. It exerts its actions through various downstream signaling pathways mediating cell proliferation, migration, differentiation, and apoptosis. S1P is essential for the development of the cardiovascular system, and abnormal S1P content in the circulation is involved in the pathogenesis of cardiovascular disorders. This article reviews the effects of S1P on cardiovascular function and signaling mechanisms in different cell types in the heart and blood vessels under diseased conditions. Finally, we look forward to more clinical findings with approved S1PR modulators and the development of S1P-based therapies for cardiovascular diseases.

The Dark Side of Sphingolipids: Searching for Potential Cardiovascular Biomarkers

Cardiovascular diseases (CVDs) are the leading cause of death and illness in Europe and worldwide, responsible for a staggering 47% of deaths in Europe. Over the past few years, there has been increasing evidence pointing to bioactive sphingolipids as drivers of CVDs. Among them, most studies place emphasis on the cardiovascular effect of ceramides and sphingosine-1-phosphate (S1P), reporting correlation between their aberrant expression and CVD risk factors. In experimental in vivo models, pharmacological inhibition of de novo ceramide synthesis averts the development of diabetes, atherosclerosis, hypertension and heart failure. In humans, levels of circulating sphingolipids have been suggested as prognostic indicators for a broad spectrum of diseases. This article provides a comprehensive review of sphingolipids' contribution to cardiovascular, cerebrovascular and metabolic diseases, focusing on the latest experimental and clinical findings. Cumulatively, these studies indicate that monitoring sphingolipid level alterations could allow for better assessment of cardiovascular disease progression and/or severity, and also suggest them as a potential target for future therapeutic intervention. Some approaches may include the down-regulation of specific sphingolipid species levels in the circulation, by inhibiting critical enzymes that catalyze ceramide metabolism, such as ceramidases, sphingomyelinases and sphingosine kinases. Therefore, manipulation of the sphingolipid pathway may be a promising strategy for the treatment of cardio- and cerebrovascular diseases.

Sphingolipids and Atherosclerosis: The Dual Role of Ceramide and Sphingosine-1-Phosphate

Sphingolipids are bioactive molecules that play either pro- and anti-atherogenic roles in the formation and maturation of atherosclerotic plaques. Among SLs, ceramide and sphingosine-1-phosphate showed antithetic properties in regulating various molecular mechanisms and have emerged as novel potential targets for regulating the development of atherosclerosis. In particular, maintaining the balance of the so-called ceramide/S1P rheostat is important to prevent the occurrence of endothelial dysfunction, which is the trigger for the entire atherosclerotic process and is strongly associated with increased oxidative stress. In addition, these two sphingolipids, together with many other sphingolipid mediators, are directly involved in the progression of atherogenesis and the formation of atherosclerotic plaques by promoting the oxidation of low-density lipoproteins (LDL) and influencing the vascular smooth muscle cell phenotype. The modulation of ceramide and S1P levels may therefore allow the development of new antioxidant therapies that can prevent or at least impair the onset of atherogenesis, which would ultimately improve the quality of life of patients with coronary artery disease and significantly reduce their mortality.

Circulating Biomarkers for Laboratory Diagnostics of Atherosclerosis-Literature Review

Atherosclerosis is still considered a disease burden with long-term damaging processes towards the cardiovascular system. Evaluation of atherosclerotic stages requires the use of independent markers such as those already considered traditional, that remain the main therapeutic target for patients with atherosclerosis, together with emerging biomarkers. The challenge is finding models of predictive markers that are particularly tailored to detect and evaluate the evolution of incipient vascular lesions. Important advances have been made in this field, resulting in a more comprehensible and stronger linkage between the lipidic profile and the continuous inflammatory process. In this paper, we analysed the most recent data from the literature studying the molecular mechanisms of biomarkers and their involvement in the cascade of events that occur in the pathophysiology of atherosclerosis.

Ceramides and Phosphatidylcholines Associate with Cardiovascular Diseases in the Elderly

Background

The ceramide- and phospholipid-based cardiovascular risk score (CERT2) has been found to predict the risk for cardiovascular disease (CVD) events, especially cardiovascular mortality. In the present study, our aim was to estimate the predictive ability of CERT2 for mortality of CVD, coronary artery disease (CAD), and stroke in the elderly and to compare these results with those of conventional lipids.

Methods

We conducted a prospective study with an 18-year follow-up period that included a total of 1260 participants ages ≥64 years. Ceramides and phosphatidylcholines were analyzed using a LC-MS. Total cholesterol and triglycerides were performed by enzymatic methods and HDL cholesterol was determined by a direct enzymatic method. Concentrations of LDL-cholesterol were calculated according to the Friedewald formula.

Results

A higher score of CERT2 was significantly associated with higher CVD, CAD, and stroke mortality during the 18-year follow-up both in unadjusted and adjusted Cox regression models. The unadjusted hazard ratios (HRs) of CERT2 (95% CI) per SD for CVD, CAD, and stroke were 1.72 (1.52–1.96), 1.76 (1.52–2.04), and 1.63 (1.27–2.10), respectively, and the corresponding adjusted HRs (95% CI) per SD for CERT2 were 1.48 (1.29–1.69), 1.50 (1.28–1.75), and 1.41 (1.09–1.83). For conventional lipids, HRs per SD were lower than for CERT2.

Conclusions

The risk score CERT2 associated strongly with CVD, CAD, and stroke mortality in the elderly, while the association between these events and conventional lipids was weak.

Molecular Characterization of Plasma HDL, LDL, and VLDL Lipids Cargos from Atherosclerotic Patients with Advanced Carotid Lesions: A Preliminary Report

Carotid atherosclerosis represents a relevant healthcare problem, since unstable plaques are responsible for approximately 15% of neurologic events, namely transient ischemic attack and stroke. Although statins treatment has proven effective in reducing LDL-cholesterol and the onset of acute clinical events, a residual risk may persist suggesting the need for the detection of reliable molecular markers useful for the identification of patients at higher risk regardless of optimal medical therapy. In this regard, several lines of evidence show a relationship among specific biologically active plasma lipids, atherosclerosis, and acute clinical events. We performed a Selected Reaction Monitoring-based High Performance Liquid Chromatography-tandem Mass Spectrometry (SRM-based HPLC-MS/MS) analysis on plasma HDL, LDL, and VLDL fractions purified, by isopycnic salt gradient ultracentrifugation, from twenty-eight patients undergoing carotid endarterectomy, having either a “hard” or a “soft” plaque, with the aim of characterizing the specific lipidomic patterns associated with features of carotid plaque instability. One hundred and thirty lipid species encompassing different lipid (sub)classes were monitored. Supervised multivariate analysis showed that lipids belonging to phosphatidylethanolamine (PE), sphingomyelin (SM), and diacylglycerol (DG) classes mostly contribute to discrimination within each lipoprotein fraction according to the plaque typology. Differential analysis evidenced a significant dysregulation of LDL PE (38:6), SM (32:1), and SM (32:2) between the two groups of patients (adj. p-value threshold = 0.05 and log₂FC ≥ |0.58|). Using this approach, some LDL-associated markers of plaque vulnerability have been identified, in line with the current knowledge of the key roles of these phospholipids in lipoprotein metabolism and cardiovascular disease. This proof-of-concept study reports promising results, showing that lipoprotein lipidomics may present a valuable approach for identifying new biomarkers of potential clinical relevance.

Sphingolipid metabolism and signaling in cardiovascular diseases

Sphingolipids are a structural component of the cell membrane, derived from sphingosine, an amino alcohol. Its sphingoid base undergoes various types of enzymatic transformations that lead to the formation of biologically active compounds, which play a crucial role in the essential pathways of cellular signaling, proliferation, maturation, and death. The constantly growing number of experimental and clinical studies emphasizes the pivotal role of sphingolipids in the pathophysiology of cardiovascular diseases, including, in particular, ischemic heart disease, hypertension, heart failure, and stroke. It has also been proven that altering the sphingolipid metabolism has cardioprotective properties in cardiac pathologies, including myocardial infarction. Recent studies suggest that selected sphingolipids may serve as valuable biomarkers useful in the prognosis of cardiovascular disorders in clinical practice. This review aims to provide an overview of the current knowledge of sphingolipid metabolism and signaling in cardiovascular diseases.

Ceramidas Plasmáticas na Estratificação de Risco das Doenças Cardiovasculares

A produção de ceramida ocorre em todo o corpo e desempenha um papel importante na manutenção da fisiologia normal. No entanto, os níveis de ceramidas são alterados em estados de doença, principalmente durante o desenvolvimento de diabetes e dislipidemia. A produção de ceramidas também está associada à instabilidade das placas ateroscleróticas. Estudos recentes revelam que pacientes com doença arterial coronariana instável apresentam níveis plasmáticos aumentados de ceramidas (principalmente C16, C18 e C24:1). Atualmente, são consideradas biomarcadores emergentes nas doenças cardiovasculares, sendo utilizadas na predição de instabilidade da placa aterosclerótica e eventos cardiovasculares adversos de forma independente aos fatores de risco tradicionais. Com o objetivo de descrever e discutir o papel das ceramidas na estratificação das doenças cardiovasculares, o desenvolvimento desta revisão narrativa contextualiza a importância desse biomarcador no cenário atual da cardiologia.

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.

Ceramides as Mediators of Oxidative Stress and Inflammation in Cardiometabolic Disease

Ceramides, composed of a sphingosine and a fatty acid, are bioactive lipid molecules involved in many key cellular pathways (e.g., apoptosis, oxidative stress and inflammation). There is much evidence on the relationship between ceramide species and cardiometabolic disease, especially in relationship with the onset and development of diabetes and acute and chronic coronary artery disease. This review reports available evidence on ceramide structure and generation, and discusses their role in cardiometabolic disease, as well as current translational chances and difficulties for ceramide application in the cardiometabolic clinical settings.

Ceramides and Cardiovascular Risk Factors, Inflammatory Parameters and Left Ventricular Function in AMI Patients

Background: Ceramides, biologically active lipids correlated to oxidative stress and inflammation, have been associated with adverse outcomes in acute myocardial infarction (AMI). The purpose of this study was to assess the association between ceramides/ratios included in the CERT1 score and increased cardiovascular (CV) risk, inflammatory and left ventricular function parameters in AMI. Methods: high performance liquid chromatography-tandem mass spectrometry was used to identify Cer(d18:1/16:0), Cer(d18:1/18:0), and Cer(d18:1/24:1) levels and their ratios to Cer(d18:1/24:0), in 123 AMI patients (FTGM coronary unit, Massa, Italy). Results: Cer(d18:1/16:0): higher in female patients (<0.05), in patients with dyslipidemia (<0.05), and it directly and significantly correlated with aging, brain natriuretic peptide-BNP, erythrocyte sedimentation rate-ESR and fibrinogen. Cer(d18:1/18:0): higher in females (<0.01) and patients with dyslipidemia (<0.01), and increased according to the number of CV risk factors (considering hypertension, dyslipidemia and diabetes). Moreover, it significantly correlated with BNP, troponin at admission, ESR, C reactive protein-CRP, and fibrinogen. Cer(d18:1/24:1): significantly correlated with aging, BNP, fibrinogen and neutrophils. Cer(d18:1/16:0)/Cer(d18:1/24:0): higher in female patients (<0.05), and in patients with higher wall motion score index-WMSI (>1.7; ≤0.05), and in those with multivessel disease (<0.05). Moreover, it significantly correlated with aging, BNP, CRP, ESR, neutrophil-to-lymphocyte ratio-NRL, and fibrinogen. Cer(d18:1/18:0)/Cer(d18:1/24:0): higher in female patients (<0.001), and increased according to age. Moreover, it was higher in patients with lower left ventricular ejection fraction (<35%, ≤0.01), higher WMSI (>1.7, <0.05), and in those with multivessel disease (0.13 ± 0.06 vs. 0.10 ± 0.05 µM, <0.05), and correlates with BNP, ESR, CRP, fibrinogen and neutrophils, platelets, NLR, and troponin at admission. Multiple regression analysis showed that Cer(d18:1/16:0)/Cer(d18:1/24:0) and Cer(d18:1/18:0)/Cer(d18:1/24:0) remained as independent determinants for WMSI after multivariate adjustment (Std coeff 0.17, T-value 1.9, ≤0.05; 0.21, 2.6, <0.05, respectively). Conclusion: Distinct ceramide species are associated with CV risk, inflammation and disease severity in AMI. Thus, a detailed analysis of ceramides may help to better understand CV pathobiology and suggest these new biomarkers as possible risk predictors and pharmacological targets in AMI patients.

Cholesterol - the devil you know; ceramide - the devil you don't

Ectopic lipids play a key role in numerous pathologies, including heart disease, stroke, and diabetes. Of all the lipids studied, perhaps the most well understood is cholesterol, a widely used clinical biomarker of cardiovascular disease and a target of pharmacological interventions (e.g., statins). Thousands of studies have interrogated the regulation and action of this disease-causing sterol. As a growing body of literature indicates, a new class of lipid-based therapies may be on the horizon. Ceramides are cholesterol-independent biomarkers of heart disease and diabetes in humans. Studies in rodents suggest that they are causative agents of disease, as lowering ceramides through genetic or pharmacological interventions prevents cardiovascular disease and diabetes. Herein, we discuss the evidence supporting the potential of therapeutics targeting ceramides to treat cardiometabolic disease, contrasting it with the robust datasets that drove the creation of cholesterol-lowering pharmaceuticals.

Ceramides and other sphingolipids as drivers of cardiovascular disease

Increases in calorie consumption and sedentary lifestyles are fuelling a global pandemic of cardiometabolic diseases, including coronary artery disease, diabetes mellitus, cardiomyopathy and heart failure. These lifestyle factors, when combined with genetic predispositions, increase the levels of circulating lipids, which can accumulate in non-adipose tissues, including blood vessel walls and the heart. The metabolism of these lipids produces bioactive intermediates that disrupt cellular function and survival. A compelling body of evidence suggests that sphingolipids, such as ceramides, account for much of the tissue damage in these cardiometabolic diseases. In humans, serum ceramide levels are proving to be accurate biomarkers of adverse cardiovascular disease outcomes. In mice and rats, pharmacological inhibition or depletion of enzymes driving de novo ceramide synthesis prevents the development of diabetes, atherosclerosis, hypertension and heart failure. In cultured cells and isolated tissues, ceramides perturb mitochondrial function, block fuel usage, disrupt vasodilatation and promote apoptosis. In this Review, we discuss the body of literature suggesting that ceramides are drivers - and not merely passengers - on the road to cardiovascular disease. Moreover, we explore the feasibility of therapeutic strategies to lower ceramide levels to improve cardiovascular health.

Predictive Added Value of Selected Plasma Lipids to a Re-estimated Minimal Risk Tool

Background: Lipidomics is emerging for biomarker discovery in cardiovascular disease, and circulating lipids are increasingly incorporated in risk models to predict cardiovascular events. Moreover, specific classes of lipids, such as sphingomyelins, ceramides, and triglycerides, have been related to coronary artery disease (CAD) severity and plaque characteristics. To avoid unnecessary testing, it is important to identify individuals at low CAD risk. The only pretest model available so far to rule out the presence of coronary atherosclerosis in patients with chest pain, but normal coronary arteries, is the minimal risk tool (MRT).

Aim: Using state-of-the-art statistical methods, we aim to verify the additive predictive value of a set of lipids, derived from targeted plasma lipidomics of suspected CAD patients, to a re-estimated version of the MRT for ruling out the presence of coronary atherosclerosis assessed by coronary CT angiography (CCTA).

Methods: Two hundred and fifty-six subjects with suspected stable CAD recruited from five European countries within H2020-SMARTool, undergoing CCTA and blood sampling for clinical biochemistry and lipidomics, were selected. The MRT was validated by regression methods and then re-estimated (reMRT). The reMRT was used as a baseline model in a likelihood ratio test approach to assess the added predictive value of each lipid from 13 among ceramides, triglycerides, and sphingomyelins. Except for one lipid, the analysis was carried out on more than 240 subjects for each lipid. A sensitivity analysis was carried out by considering two alternative models developed on the cohort as baseline models.

Results: In 205 subjects, coronary atherosclerosis ranged from minimal lesions to overt obstructive CAD, while in 51 subjects (19.9%) the coronary arteries were intact. Four triglycerides and seven sphingomyelins were significantly (p < 0.05) and differentially expressed in the two groups and, at a lesser extent, one ceramide (p = 0.067). The probability of being at minimal risk was significantly better estimated by adding either Cer(d18:1/16:0) (p = 0.01), SM(40:2) (p = 0.04), or SM(41:1) at a lesser extent (p = 0.052) to reMRT than by applying the reMRT alone. The sensitivity analysis confirmed the relevance of these lipids. Furthermore, the addition of SM(34:1), SM(38:2), SM(41:2), and SM(42:4) improved the predictive performance of at least one of the other baseline models. None of the selected triglycerides was found to provide an added value.

Conclusions: Plasma lipidomics can be a promising source of diagnostic and prognostic biomarkers in cardiovascular disease, exploitable not only to assess the risk of adverse events but also to identify subjects without coronary atherosclerosis, thus reducing unnecessary further testing in normal subjects.

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

Biomarkers are important tools for describing the adequacy or inadequacy of biological processes (to allow for the early and accurate diagnosis) and monitoring the biological effects of intervention strategies (to identify and develop optimal dose and treatment strategies). A number of lipid biomarkers are implicated in metabolic disease and the circulating levels of these biomarkers are used in clinical settings to predict and monitor disease severity. There is convincing evidence that specific circulating ceramide species can be used as biological predictors and markers of cardiovascular disease, atherosclerosis and type 2 diabetes mellitus. Here, we review the existing literature that investigated sphingolipids as biomarkers for metabolic disease prediction. What are the advantages and disadvantages? Are circulating ceramides predominantly produced in the liver? Will hepatic sphingolipid inhibitors be able to completely prevent and treat metabolic disease? As sphingolipids are being employed as biomarkers and potential metabolic disease treatments, we explore what is currently known and what still needs to be discovered.

Ceramide ratios are affected by cigarette smoke but not heat-not-burn or e-vapor aerosols across four independent mouse studies

AIMS

Smoking is an important risk factor for the development of chronic obstructive pulmonary disease and cardiovascular diseases. This study aimed to further elucidate the role of ceramides, as a key lipid class dysregulated in disease states.

MAIN METHODS

In this article we developed and validated LC-MS/MS method for ceramides (Cer(d18:1/16:0), Cer(d18:1/18:0), Cer(d18:1/24:0) and Cer(d18:1/24:1(15Z)) for the absolute quantification. We deployed it together with proteomics and transcriptomic analysis to assess the effects of cigarette smoke (CS) from the reference cigarette as well as aerosols from heat-not-burn (HnB) tobacco and e-vapor products in apolipoprotein E-deficient (ApoE^-/-) mice over several time points.

KEY FINDINGS

In the lungs, CS exposure substantially elevated the ratios of Cer(d18:1/24:0) and Cer(d18:1/24:1) to Cer(d18:1/18:0) in two independent ApoE^-/- mouse inhalation studies. Data from previous studies, in both ApoE^-/- and wild-type mice, further confirmed the reproducibility of this finding. Elevation of these ceramide ratios was also observed in plasma/serum, the liver, and-for the Cer(d18:1/24:1(15Z)) to Cer(d18:1/18:0) ratio-the abdominal aorta. Also, the levels of acid ceramidase (Asah1) and glucocerebrosidase (Gba)-lysosomal enzymes involved in the hydrolysis of glucosylceramides-were consistently elevated in the lungs after CS exposure. In contrast, exposure to HnB tobacco product and e-vapor aerosols did not induce significant changes in the ceramide profiles or associated enzymes.

SIGNIFICANCE

Our work in mice contributes to the accumulating evidence on the importance of ceramide ratios as biologically relevant markers for respiratory disorders, adding to their already demonstrated role in cardiovascular disease risk assessment in humans.

Relation between plasma ceramides and cardiovascular death in chronic heart failure: A subset analysis of the GISSI-HF trial

AIMS

Ceramides exert several biological activities that may contribute to the pathophysiology of cardiovascular disease and heart failure (HF). The association between plasma levels of distinct ceramides (that have been previously associated with increased cardiovascular risk) and cardiovascular mortality in patients with chronic HF has received little attention.

METHODS AND RESULTS

In a post hoc ancillary analysis of the Gruppo Italiano per lo Studio della Sopravvivenza nella Insufficienza Cardiaca-Heart Failure (GISSI-HF; NCT00336336) trial, we randomly selected a sample of 200 ambulatory patients with chronic HF who died due to cardiovascular causes and 200 patients who were alive at the end of the trial (after a median follow-up period of 3.9 years). We measured baseline plasma concentrations of six previously identified high-risk ceramide species [Cer(d18:1/16:0), Cer(d18:1/18:0), Cer(d18:1/20:0), Cer(d18:1/22:0), Cer(d18:1/24:0), and Cer(d18:1/24:1) and their individual plasma ratios with Cer(d18:1/24:0)]. Patients who died due to cardiovascular causes had significantly (P < 0.05 or less) higher levels of plasma Cer(d18:1/16:0) and Cer(d18:1/24:1), but lower levels of plasma Cer(d18:1/22:0) and Cer(d18:1/24:0) than had those who did not. All plasma ratios of each ceramide with Cer(d18:1/24:0) were significantly higher in patients who died due to cardiovascular causes. In Cox regression analyses, all five plasma ratios of each ceramide with Cer(d18:1/24:0) were significantly associated with a greater risk of cardiovascular mortality (with unadjusted hazard ratios ranging from 1.23 to 1.59; P < 0.001 or less). These significant associations were attenuated after adjustment for multiple established risk factors, New York Heart Association functional class, left ventricular ejection fraction, use of medications, plasma pentraxin-3 levels, and, especially, plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) levels. When we applied a Bonferroni correction for multiple comparisons (using a P-threshold 0.05/5 ceramide ratios = 0.01), none of the five plasma ratios of each ceramide with Cer(d18:1/24:0) remained statistically associated with the risk of cardiovascular mortality (with adjusted hazard ratios ranging from 1.10 to 1.23).

CONCLUSIONS

Higher levels of specific plasma ceramides [especially when used in ratios with Cer(d18:1/24:0)] are associated with increased cardiovascular mortality in ambulatory patients with chronic HF. However, these associations are weakened after adjustment for established cardiovascular risk factors, medication use, and plasma NT-proBNP concentrations.

Ceramides in Metabolism: Key Lipotoxic Players

The global prevalence of metabolic diseases such as type 2 diabetes mellitus, steatohepatitis, myocardial infarction, and stroke has increased dramatically over the past two decades. These obesity-fueled disorders result, in part, from the aberrant accumulation of harmful lipid metabolites in tissues not suited for lipid storage (e.g., the liver, vasculature, heart, and pancreatic beta-cells). Among the numerous lipid subtypes that accumulate, sphingolipids such as ceramides are particularly impactful, as they elicit the selective insulin resistance, dyslipidemia, and ultimately cell death that underlie nearly all metabolic disorders. This review summarizes recent findings on the regulatory pathways controlling ceramide production, the molecular mechanisms linking the lipids to these discrete pathogenic events, and exciting attempts to develop therapeutics to reduce ceramide levels to combat metabolic disease.

NAFLD and increased risk of cardiovascular disease: clinical associations, pathophysiological mechanisms and pharmacological implications

Non-alcoholic fatty liver disease (NAFLD) is a public health problem, affecting up to a third of the world's adult population. Several cohort studies have consistently documented that NAFLD (especially in its more advanced forms) is associated with a higher risk of all-cause mortality and that the leading causes of death among patients with NAFLD are cardiovascular diseases (CVDs), followed by extrahepatic malignancies and liver-related complications. A growing body of evidence also indicates that NAFLD is strongly associated with an increased risk of major CVD events and other cardiac complications (ie, cardiomyopathy, cardiac valvular calcification and cardiac arrhythmias), independently of traditional cardiovascular risk factors. This narrative review provides an overview of the literature on: (1) the evidence for an association between NAFLD and increased risk of cardiovascular, cardiac and arrhythmic complications, (2) the putative pathophysiological mechanisms linking NAFLD to CVD and other cardiac complications and (3) the current pharmacological treatments for NAFLD that might also benefit or adversely affect risk of CVD.

Association between ceramides and coronary artery stenosis in patients with coronary artery disease

BACKGROUND

Coronary artery stenosis induces heart diseases including acute coronary syndrome (ACS). Some studies reported the ceramide species are associated with the ACS and major adverse cardia and cerebrovascular events (MACE). However, few studies investigated the association between plasma ceramide levels and the severity of stenosis, together with the onset of diseases. This aim of the present study was to investigate the association betweencertain ceramide species, coronary artery stenosis and acute coronary syndrome.

METHODS

Five hundred fifty-three patients with definite or suspected CAD were recruited and received angiography. Subjects were assigned into 4 groups according to the severity of coronary artery stenosis. The measurements of 4 plasma ceramide species, namely, Cer (d18:1/16:0), Cer (d18:1/18:0), Cer (d18:1/24:1), Cer (d18:1/24:0) were carried out by Liquid chromatography-tandem mass spectrometry (LC-MS/MS) and the ratio of Cer (d18:1/16:0), Cer (d18:1/18:0) and Cer (d18:1/24:1) to Cer (18:1/24:0), respectively, were calculated as index to evaluate the association between plasma ceramides levels and coronary artery stenosis. Multiple logistic regression analysis was used to establish the prognostic model for the prediction of ACS risk.

RESULTS

After the adjustment by multiple clinical risk factors including age, gender, pre-existing myocardial/cerebral infarction, hemoglobin A1c% (HbA1c%), smoking and the diagnosis during index hospitalization, multiple logistic regression analysis showed that the high ratio of Cer (d18:1/24:1) to Cer (d18:1/24:0), female gender, HbA1c%, unstable angina (UAP) and acute myocardial infarction (AMI) diagnosis (compared with atherosclerosis) during index hospitalization were associated with more severe coronary artery stenosis. Furthermore, the prognostic model was established after adjustment of risk factors and the area under curve (AUC) of receiver operating characteristics (ROC) for the prognostic model was 0.732 and 95% CI was 0.642-0.822.

CONCLUSION

The severity of coronary artery stenosis is associated with high ratio of Cer (d18:1/24:1) to Cer (d18:1/24:0), female gender, HbA1c% and AMI. Although the reported prognostic model showed a good discrimination, further investigation on long term MACE is needed to evaluate the role of ceramide for the prediction of MACE risk.

DES1: A Key Driver of Lipotoxicity in Metabolic Disease

Ceramides have emerged as important regulators of tissue metabolism that play essential roles in cardiometabolic disease. They are potent biomarkers of diabetes and heart disease and are now being measured clinically as predictors of major adverse cardiac events. Moreover, studies in rodents reveal that inhibitors of ceramide synthesis prevent or reverse the pathogenic features of type 2 diabetes, nonalcoholic fatty liver disease, atherosclerosis, and cardiomyopathy. Herein the authors discuss inhibition of dihydroceramide desaturase-1, the final enzyme in the ceramide biosynthesis pathway, as a potential therapeutic approach to lower ceramides and combat cardiometabolic disease.

Ceramides and risk of major adverse cardiovascular events: A meta-analysis of longitudinal studies

BACKGROUND

Recent cohort studies evaluated the association between some previously identified high-risk ceramides [Cer(d18:1/16:0), Cer(d18:1/18:0), Cer(d18:1/22:0), Cer(d18:1/24:0) and Cer(d18:1/24:1)] and risk of major adverse cardiovascular events in adult population.

OBJECTIVE

The objective of this meta-analysis was to investigate the magnitude of such associations.

METHODS

We searched publication databases using appropriate keywords to identify cohort studies (published up to July 30, 2019), in which association between previously identified high-risk ceramides and major adverse cardiovascular events was reported. Data from eligible studies were extracted and meta-analysis was performed using random-effects modeling.

RESULTS

Seven cohort studies with aggregate data on 29,818 individuals (2736 new cases of cardiovascular events over a median follow-up of 6 years) were included. Higher plasma levels of Cer(d18:1/16:0) (random effects hazard ratio [HR] per standard deviation 1.21, 95% confidence interval [CI] 1.11-1.32, I² = 88%), Cer(d18:1/18:0) (HR 1.19, 95% CI 1.10-1.27, I² = 68%), and Cer(d18:1/24:1) (HR 1.17, 95% CI 1.08-1.27, I² = 83%) were associated with major adverse cardiovascular events. Conversely, no association with plasma levels of Cer(d18:1/22:0) (HR 1.14 95% CI 0.88-1.47, I² = 88%) and Cer(d18:1/24:0) (HR 0.97, 95% CI 0.89-1.05, I² = 73%) was found. Subgroup analyses did not substantially modify the findings.

CONCLUSIONS

Higher plasma levels of Cer(d18:1/16:0), Cer(d18:1/18:0) and Cer(d18:1/24:1) were associated with major adverse cardiovascular events, whereas plasma levels of Cer(d18:1/22:0) and Cer(d18:1/24:0) were not. Additional research is required to elucidate the different role of ceramides on pathways involved in cardiovascular disease.