Ceramides are decreased after liraglutide treatment in people with type 2 diabetes: a post hoc analysis of two randomized clinical trials

A novel regulator of NLRP3 inflammasome: Peptides

The NLRP3 inflammasome plays a crucial role as a critical regulator of the immune response and has been implicated in the pathogenesis of numerous diseases. Peptides, known for their remarkable potency, selectivity, and low toxicity, have been extensively employed in disease treatment. Recent research has unveiled the potential of peptides in modulating the activity of the NLRP3 inflammasome. This review begins by examining the structure of the NLRP3 inflammasome, encompassing NLRP3, ASC, and Caspase-1, along with the three activation pathways: canonical, non-canonical, and alternative. Subsequently, we provide a comprehensive summary of peptide modulators targeting the NLRP3 inflammasome and elucidate their underlying mechanisms. The efficacy of these modulators has been validated through in vitro and in vivo experiments on NLRP3 inflammasome regulation. Furthermore, we conduct sequence alignment of the identified peptides and investigate their binding sites on the NLRP3 protein. This work is a foundational exploration for advancing peptides as potential therapeutic agents for NLRP3-related diseases.

Ceramides may Play a Central Role in the Pathogenesis of Alzheimer's Disease: a Review of Evidence and Horizons for Discovery

While several hypotheses have been proposed to explain the underlying mechanisms of Alzheimer's disease, none have been entirely satisfactory. Both genetic and non-genetic risk factors, such as infections, metabolic disorders and psychological stress, contribute to this debilitating disease. Multiple lines of evidence indicate that ceramides may be central to the pathogenesis of Alzheimer's disease. Tumor necrosis factor-α, saturated fatty acids and cortisol elevate the brain levels of ceramides, while genetic risk factors, such as mutations in APP, presenilin, TREM2 and APOE ε4, also elevate ceramide synthesis. Importantly, ceramides displace sphingomyelin and cholesterol from lipid raft-like membrane patches that connect the endoplasmic reticulum and mitochondria, disturbing mitochondrial oxidative phosphorylation and energy production. As a consequence, the flattening of lipid rafts alters the function of γ-secretase, leading to increased production of Aβ42. Moreover, ceramides inhibit the insulin-signaling cascade via at least three mechanisms, resulting in the activation of glycogen synthase kinase-3 β. Activation of this kinase has multiple consequences, as it further deteriorates insulin resistance, promotes the transcription of BACE1, causes hyperphosphorylation of tau and inhibits the transcription factor Nrf2. Functional Nrf2 prevents apoptosis, mediates anti-inflammatory activity and improves blood-brain barrier function. Thus, various seemingly unrelated Alzheimer's disease risk factors converge on ceramide production, whereas the elevated levels of ceramides give rise to the well-known pathological features of Alzheimer's disease. Understanding and targeting these mechanisms may provide a promising foundation for the development of novel preventive and therapeutic strategies.

Lipid profiling identifies modifiable signatures of cardiometabolic risk in children and adolescents with obesity

Pediatric obesity is a progressive, chronic disease that can lead to serious cardiometabolic complications. Here we investigated the peripheral lipidome in 958 children and adolescents with overweight or obesity and 373 with normal weight, in a cross-sectional study. We also implemented a family-based, personalized program to assess the effects of obesity management on 186 children and adolescents in a clinical setting. Using mass spectrometry-based lipidomics, we report an increase in ceramides, alongside a decrease in lysophospholipids and omega-3 fatty acids with obesity metabolism. Ceramides, phosphatidylethanolamines and phosphatidylinositols were associated with insulin resistance and cardiometabolic risk, whereas sphingomyelins showed inverse associations. Additionally, a panel of three lipids predicted hepatic steatosis as effectively as liver enzymes. Lipids partially mediated the association between obesity and cardiometabolic traits. The nonpharmacological management reduced levels of ceramides, phospholipids and triglycerides, indicating that lowering the degree of obesity could partially restore a healthy lipid profile in children and adolescents.

Role of dietary and nutritional interventions in ceramide-associated diseases

Ceramides are important intermediates in sphingolipid metabolism and serve as signaling molecules with independent biological significance. Elevated cellular and circulating ceramide levels are consistently associated with pathological conditions including cardiometabolic diseases, neurological diseases, autoimmune diseases, and cancers. Although pharmacological inhibition of ceramide formation often protects against these diseases in animal models, pharmacological modulation of ceramides in humans remains impractical. Dietary interventions including the Mediterranean diet, lacto-ovo-vegetarian diet, calorie-restricted diet, restriction of dairy product consumption, and dietary supplementation with polyunsaturated fatty acids, dietary fibers, and polyphenols, all have beneficial effects on modulating ceramide levels. Mechanistic insights into these interventions are discussed. This article reviews the relationships between ceramides and disease pathogenesis, with a focus on dietary intervention as a viable strategy for lowering the concentration of circulating ceramides.

Combined diet and exercise training decreases serum lipids associated with insulin resistance

OBJECTIVE

Circulating lipids are linked with insulin resistance and increased cardiovascular disease risk. We previously reported that dihydroceramides, a specific type of sphingolipid, are elevated in insulin-resistant individuals; however, little is known regarding whether insulin-sensitizing lifestyle interventions can improve profiles of sphingolipids and other lipid species.

METHODS

A total of 21 individuals with obesity participated in a 3-month lifestyle intervention of combined weight loss and exercise training. Insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamps, and serum lipidomics was conducted.

RESULTS

Following the intervention, BMI was significantly reduced by 10%; VO2peak and insulin sensitivity increased by 12% and 57%, respectively; and total serum triacylglycerol (TAG), diacylglycerol, dihydroceramides, sphingosine-1-phosphate, and sphinganine-1-phosphate were significantly reduced, as were specific species of dihydroceramides (C18:0 and C24:1). Individuals with higher preintervention TAG concentrations had significant decreases in serum lipids, which were not significantly changed in individuals with lower preintervention TAG.

CONCLUSIONS

These data show that serum sphingolipid species previously linked to insulin resistance in humans can be reduced with insulin-sensitizing lifestyle interventions. Furthermore, individuals with elevated serum TAG may significantly benefit from lifestyle interventions that increase insulin sensitivity due to a greater decrease in serum lipids related to insulin resistance.

Therapeutic implications for sphingolipid metabolism in metabolic dysfunction-associated steatohepatitis

The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD), a leading cause of chronic liver disease, has increased worldwide along with the epidemics of obesity and related dysmetabolic conditions characterized by impaired glucose metabolism and insulin signaling, such as type 2 diabetes mellitus (T2D). MASLD can be defined as an excessive accumulation of lipid droplets in hepatocytes that occurs when the hepatic lipid metabolism is totally surpassed. This metabolic lipid inflexibility constitutes a central node in the pathogenesis of MASLD and is frequently linked to the overproduction of lipotoxic species, increased cellular stress, and mitochondrial dysfunction. A compelling body of evidence suggests that the accumulation of lipid species derived from sphingolipid metabolism, such as ceramides, contributes significantly to the structural and functional tissue damage observed in more severe grades of MASLD by triggering inflammatory and fibrogenic mechanisms. In this context, MASLD can further progress to metabolic dysfunction-associated steatohepatitis (MASH), which represents the advanced form of MASLD, and hepatic fibrosis. In this review, we discuss the role of sphingolipid species as drivers of MASH and the mechanisms involved in the disease. In addition, given the absence of approved therapies and the limited options for treating MASH, we discuss the feasibility of therapeutic strategies to protect against MASH and other severe manifestations by modulating sphingolipid metabolism.

Proinflammatory stress activates neutral sphingomyelinase 2 based generation of a ceramide-enriched β cell EV subpopulation

β cell extracellular vesicles (EVs) play a role as paracrine effectors in islet health, yet mechanisms connecting β cell stress to changes in EV cargo and potential impacts on diabetes remain poorly defined. We hypothesized that β cell inflammatory stress engages neutral sphingomyelinase 2 (nSMase2)-dependent EV formation pathways, generating ceramide-enriched EVs that could impact surrounding β cells. Consistent with this, proinflammatory cytokine treatment of INS-1 β cells and human islets concurrently increased β cell nSMase2 and ceramide expression, as well as EV ceramide staining. Direct chemical activation or genetic knockdown of nSMase2, or treatment with a GLP-1 receptor agonist also modulated cellular and EV ceramide. Small RNA sequencing of ceramide-enriched EVs identified a distinct set of miRNAs linked to β cell function and identity. Coculture experiments using CD9-GFP tagged INS-1 cell EVs demonstrated that either cytokine treatment or chemical nSMase2 activation increased EV transfer to recipient cells. Children with recent-onset T1D showed no abnormalities in circulating ceramide-enriched EVs, suggesting a localized, rather than systemic phenomenon. These findings highlight nSMase2 as a regulator of β cell EV cargo and identify ceramide-enriched EV populations as a contributor to EV-related paracrine signaling under conditions of β cell inflammatory stress.

Article Highlights

a. Why did we undertake this study?: Mechanisms connecting β cell stress to changes in extracellular vesicle (EV) cargo and potential impacts on diabetes are poorly defined.b. What is the specific question we wanted to answer?: Does β cell inflammatory stress engage neutral sphingomyelinase 2 (nSMase2)-dependent EV formation pathways to generate ceramide-enriched EVs.c. What did we find?: Proinflammatory cytokine treatment of β cells increased β cell ceramide expression, along with EV ceramide in part via increases in nSMase2. Ceramide-enriched EVs housed a distinct set of miRNAs linked to insulin signaling. Both cytokine treatment and nSMase2 activation increase EV transfer to other β cells.d. What are the implications of our findings?: Our findings highlight nSMase2 as a regulator of β cell EV cargo and identify ceramide-enriched EV populations as a contributor to EV-related paracrine signaling under conditions of β cell inflammatory stress.

Lysophosphatidic Acid-Mediated Inflammation at the Heart of Heart Failure

PURPOSE OF REVIEW

The primary aim of this review is to provide an in-depth examination of the role bioactive lipids-namely lysophosphatidic acid (LPA) and ceramides-play in inflammation-mediated cardiac remodeling during heart failure. With the global prevalence of heart failure on the rise, it is critical to understand the underlying molecular mechanisms contributing to its pathogenesis. Traditional studies have emphasized factors such as oxidative stress and neurohormonal activation, but emerging research has shed light on bioactive lipids as central mediators in heart failure pathology. By elucidating these intricacies, this review aims to: Bridge the gap between basic research and clinical practice by highlighting clinically relevant pathways contributing to the pathogenesis and prognosis of heart failure. Provide a foundation for the development of targeted therapies that could mitigate the effects of LPA and ceramides on heart failure. Serve as a comprehensive resource for clinicians and researchers interested in the molecular biology of heart failure, aiding in better diagnostic and therapeutic decisions.

RECENT FINDINGS

Recent findings have shed light on the central role of bioactive lipids, specifically lysophosphatidic acid (LPA) and ceramides, in heart failure pathology. Traditional studies have emphasized factors such as hypoxia-mediated cardiomyocyte loss and neurohormonal activation in the development of heart failure. Emerging research has elucidated the intricacies of bioactive lipid-mediated inflammation in cardiac remodeling and the development of heart failure. Studies have shown that LPA and ceramides contribute to the pathogenesis of heart failure by promoting inflammation, fibrosis, and apoptosis in cardiac cells. Additionally, recent studies have identified potential targeted therapies that could mitigate the effects of bioactive lipids on heart failure, including LPA receptor antagonists and ceramide synthase inhibitors. These recent findings provide a promising avenue for the development of targeted therapies that could improve the diagnosis and treatment of heart failure. In this review, we highlight the pivotal role of inflammation induced by bioactive lipid signaling and its influence on the pathogenesis of heart failure. By critically assessing the existing literature, we provide a comprehensive resource for clinicians and researchers interested in the molecular mechanisms of heart failure. Our review aims to bridge the gap between basic research and clinical practice by providing actionable insights and a foundation for the development of targeted therapies that could mitigate the effects of bioactive lipids on heart failure. We hope that this review will aid in better diagnostic and therapeutic decisions, further advancing our collective understanding and management of heart failure.