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Current Opinion in Lipidology Aug 2023Nonalcoholic fatty liver disease (NAFLD) is a highly prevalent progressive condition that lacks a specific pharmacological treatment. ATP-citrate lyase (ACLY) is one of... (Review)
Review
PURPOSE OF REVIEW
Nonalcoholic fatty liver disease (NAFLD) is a highly prevalent progressive condition that lacks a specific pharmacological treatment. ATP-citrate lyase (ACLY) is one of the emergent targets for the treatment of NAFLD. This review aims to summarize the role of ACLY in NAFLD, provide evidence of the beneficial effects of the ACLY inhibitor bempedoic acid (BemA) in NAFLD and discuss the mechanisms involved.
RECENT FINDINGS
BemA is effective in reducing hepatic steatosis in several animal models that recapitulate different stages of the disease. Thus, in a dietary model of simple hepatic steatosis in female rats, BemA abrogates the accumulation of liver fat. Apart from ACLY inhibition, BemA has several functions in the liver that contribute to the antisteatotic effect: inhibition of ketohexokinase, induction of patatin-like phospholipase domain-containing protein 3 and increases in both fatty acid β-oxidation activity and hepatic H 2 S production. In models of the advanced phases of NAFLD, BemA reduces not only steatosis, but also ballooning, lobular inflammation and hepatic fibrosis, by mechanisms involving both hepatocytes and hepatic stellate cells.
SUMMARY
BemA, an ACLY inhibitor currently approved for the treatment of hypercholesterolemia, may be a useful drug to treat NAFLD through its antisteatotic, anti-inflammatory and antifibrotic effects.
Topics: Female; Animals; Rats; Non-alcoholic Fatty Liver Disease; Liver; Fatty Acids; Dicarboxylic Acids
PubMed: 36942869
DOI: 10.1097/MOL.0000000000000878 -
Biochimica Et Biophysica Acta.... Feb 2024Succinate, one of the intermediates of the tricarboxylic acid (TCA) cycle, plays an essential role in the metabolism of mitochondria and the production of energy, and is... (Review)
Review
Succinate, one of the intermediates of the tricarboxylic acid (TCA) cycle, plays an essential role in the metabolism of mitochondria and the production of energy, and is considered as a signaling molecule in metabolism as well as in initiation and progression of hepatic diseases. Of note, succinate activates a downstream signaling pathway through GPR91, and elicits a variety of intracellular responses, such as succinylation, production of reactive oxygen species (ROS), stabilization of hypoxia-inducible factor-1α (HIF-1α), and significant impact in cellular metabolism because of the pivotal role in the TCA cycle. Therefore, it is intriguing to deeply elucidate signaling mechanisms of succinate in hepatic fibrosis, metabolic reprogramming in inflammatory or immune responses, as well as carcinogenesis. This manuscript intends to review current understanding of succinate in mediating metabolism, inflammatory and immunologic reactions in liver diseases in order to establish molecular basis for the development of therapeutic strategies.
Topics: Humans; Succinic Acid; Succinates; Signal Transduction; Citric Acid Cycle; Liver Cirrhosis
PubMed: 37976628
DOI: 10.1016/j.bbadis.2023.166935 -
JCI Insight Oct 2023Modulation of the immune response to initiate and halt the inflammatory process occurs both at the site of injury as well as systemically. Due to the evolving role of...
Modulation of the immune response to initiate and halt the inflammatory process occurs both at the site of injury as well as systemically. Due to the evolving role of cellular metabolism in regulating cell fate and function, tendon injuries that undergo normal and aberrant repair were evaluated by metabolic profiling to determine its impact on healing outcomes. Metabolomics revealed an increasing abundance of the immunomodulatory metabolite itaconate within the injury site. Subsequent single-cell RNA-Seq and molecular and metabolomic validation identified a highly mature neutrophil subtype, not macrophages, as the primary producers of itaconate following trauma. These mature itaconate-producing neutrophils were highly inflammatory, producing cytokines that promote local injury fibrosis before cycling back to the bone marrow. In the bone marrow, itaconate was shown to alter hematopoiesis, skewing progenitor cells down myeloid lineages, thereby regulating systemic inflammation. Therapeutically, exogenous itaconate was found to reduce injury-site inflammation, promoting tenogenic differentiation and impairing aberrant vascularization with disease-ameliorating effects. These results present an intriguing role for cycling neutrophils as a sensor of inflammation induced by injury - potentially regulating immune cell production in the bone marrow through delivery of endogenously produced itaconate - and demonstrate a therapeutic potential for exogenous itaconate following tendon injury.
Topics: Humans; Neutrophils; Succinates; Macrophages; Inflammation
PubMed: 37707952
DOI: 10.1172/jci.insight.169208 -
Microbiology Resource Announcements Oct 2023We report draft genome sequences for 15 non-conventional Saccharomycotina yeast strains obtained from public culture repositories. Included in our collection are eight...
We report draft genome sequences for 15 non-conventional Saccharomycotina yeast strains obtained from public culture repositories. Included in our collection are eight strains of with broad tolerance to dicarboxylic acids. The genome sequences of these strains will enable comparative genomics of acid-tolerant phenotypes and strain engineering of non-conventional hosts.
PubMed: 37747226
DOI: 10.1128/MRA.00337-23 -
Bioresource Technology Sep 2023Microbial biomanufacturing is a promising approach to produce high-value compounds with low-carbon footprint and significant economic benefits. Among twelve "Top... (Review)
Review
Microbial biomanufacturing is a promising approach to produce high-value compounds with low-carbon footprint and significant economic benefits. Among twelve "Top Value-Added Chemicals from Biomass", itaconic acid (IA) stands out as a versatile platform chemical with numerous applications. IA is naturally produced by Aspergillus and Ustilago species through a cascade enzymatic reaction between aconitase (EC 4.2.1.3) and cis-aconitic acid decarboxylase (EC 4.1.1.6). Recently, non-native hosts such as Escherichia coli, Corynebacterium glutamicum, Saccharomyces cerevisiae, and Yarrowia lipolytica have been genetically engineered to produce IA through the introduction of key enzymes. This review provides an up-to-date summary of the progress made in IA bioproduction, from native to engineered hosts, covers in vivo and in vitro approaches, and highlights the prospects of combination tactics. Current challenges and recent endeavors are also addressed to envision comprehensive strategies for renewable IA production in the future towards sustainable development goals (SDGs).
Topics: Genetic Engineering; Aspergillus; Succinates; Saccharomyces cerevisiae; Metabolic Engineering
PubMed: 37290713
DOI: 10.1016/j.biortech.2023.129280 -
Frontiers in Endocrinology 2023Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors originating from chromaffin cells, holding significant clinical importance due to their... (Review)
Review
Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors originating from chromaffin cells, holding significant clinical importance due to their capacity for excessive catecholamine secretion and associated cardiovascular complications. Roughly 80% of cases are associated with genetic mutations. Based on the functionality of these mutated genes, PPGLs can be categorized into distinct molecular clusters: the pseudohypoxia signaling cluster (Cluster-1), the kinase signaling cluster (Cluster-2), and the WNT signaling cluster (Cluster-3). A pivotal factor in the pathogenesis of PPGLs is hypoxia-inducible factor-2α (HIF2α), which becomes upregulated even under normoxic conditions, activating downstream transcriptional processes associated with pseudohypoxia. This adaptation provides tumor cells with a growth advantage and enhances their ability to thrive in adverse microenvironments. Moreover, pseudohypoxia disrupts immune cell communication, leading to the development of an immunosuppressive tumor microenvironment. Within Cluster-1a, metabolic perturbations are particularly pronounced. Mutations in enzymes associated with the tricarboxylic acid (TCA) cycle, such as succinate dehydrogenase (SDHx), fumarate hydratase (FH), isocitrate dehydrogenase (IDH), and malate dehydrogenase type 2 (MDH2), result in the accumulation of critical oncogenic metabolic intermediates. Notable among these intermediates are succinate, fumarate, and 2-hydroxyglutarate (2-HG), which promote activation of the HIFs signaling pathway through various mechanisms, thus inducing pseudohypoxia and facilitating tumorigenesis. SDHx mutations are prevalent in PPGLs, disrupting mitochondrial function and causing succinate accumulation, which competitively inhibits α-ketoglutarate-dependent dioxygenases. Consequently, this leads to global hypermethylation, epigenetic changes, and activation of HIFs. In FH-deficient cells, fumarate accumulation leads to protein succination, impacting cell function. FH mutations also trigger metabolic reprogramming towards glycolysis and lactate synthesis. IDH1/2 mutations generate D-2HG, inhibiting α-ketoglutarate-dependent dioxygenases and stabilizing HIFs. Similarly, MDH2 mutations are associated with HIF stability and pseudohypoxic response. Understanding the intricate relationship between metabolic enzyme mutations in the TCA cycle and pseudohypoxic signaling is crucial for unraveling the pathogenesis of PPGLs and developing targeted therapies. This knowledge enhances our comprehension of the pivotal role of cellular metabolism in PPGLs and holds implications for potential therapeutic advancements.
Topics: Humans; Pheochromocytoma; Citric Acid Cycle; Ketoglutaric Acids; Paraganglioma; Adrenal Gland Neoplasms; Mutation; Succinates; Succinic Acid; Signal Transduction; Fumarates; Dioxygenases; Tumor Microenvironment
PubMed: 37867526
DOI: 10.3389/fendo.2023.1274239 -
Journal of Clinical Lipidology 2024Bempedoic acid is an oral adenosine triphosphate citrate lyase (ACL) inhibitor that lowers low-density lipoprotein cholesterol (LDL-C) blood levels. The Cholesterol... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
Bempedoic acid is an oral adenosine triphosphate citrate lyase (ACL) inhibitor that lowers low-density lipoprotein cholesterol (LDL-C) blood levels. The Cholesterol Lowering via Bempedoic acid, an ACL-Inhibiting Regimen (CLEAR) Outcomes study demonstrated that bempedoic acid reduced cardiovascular (CV) risk in patients at high risk for CV events who were unwilling or unable to take guideline-recommended doses of statins.
OBJECTIVE
To describe detailed safety information from CLEAR Outcomes, including events in the United States (US) prescribing information based on previous phase 3 hyperlipidemia studies.
METHODS
CLEAR Outcomes was a double-blind trial conducted in 13,970 patients randomized to oral bempedoic acid 180 mg daily or placebo and followed for a median of 3.4 years.
RESULTS
In patients who received at least one dose (7,001 bempedoic acid, 6,964 placebo), treatment emergent adverse events (AE) occurred in 86.3 % and 85 % of patients, respectively. COVID-19 was the most frequently reported AE in both groups. Changes in serum creatinine, blood urea nitrogen, hemoglobin, aminotransaminases, and uric acid were consistent with the known safety profile of bempedoic acid. Gout or gouty arthritis occurred in 3.2 % of bempedoic acid and 2.2 % of placebo patients. AE associated with tendinopathies, including tendon rupture, occurred in 2 % of patients in both treatment groups. Cholelithiasis occurred in 2.2 % of bempedoic acid and 1.2 % of placebo patients; AE related to gallbladder disease were similar between treatment groups.
CONCLUSIONS
Bempedoic acid was well-tolerated compared with placebo. Safety data from the long-term CLEAR Outcomes study reinforce the positive benefit-risk profile of bempedoic acid.
Topics: Humans; Cardiovascular Diseases; Cholesterol; Dicarboxylic Acids; Fatty Acids; Heart Disease Risk Factors; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Hypercholesterolemia; Risk Factors; Double-Blind Method
PubMed: 37951797
DOI: 10.1016/j.jacl.2023.10.011 -
The American Journal of Cardiology Oct 2023Bempedoic acid is a selective inhibitor of the adenosine triphosphate citrate lyase that reduces low-density lipoprotein cholesterol (LDLc) levels by 17% to 28%.... (Meta-Analysis)
Meta-Analysis
Bempedoic acid is a selective inhibitor of the adenosine triphosphate citrate lyase that reduces low-density lipoprotein cholesterol (LDLc) levels by 17% to 28%. Although the Evaluation of Major Cardiovascular Events in Patients With, or at High Risk for, Cardiovascular Disease Who Are Statin Intolerant Treated With Bempedoic Acid (CLEAR-OUTCOMES) trials demonstrated the efficacy on cardiovascular outcomes there is a controversy related to the possible net clinical benefit. Thereafter, we performed an intention-to-treat meta-analysis in line with recommendations from the Cochrane Collaboration and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The primary outcome of the metanalysis was the incidence of major adverse cardiovascular events, defined by each study protocol. Secondary outcomes for the analyses were myocardial infarction, stroke, myocardial revascularization, cardiovascular death, and all-cause death. Results of 4 clinical trials evaluated contained a total of 17,324 patients; 9,236 received bempedoic acid for a median of 46.6 months. The mean baseline LDLc was 129.4 (22.8) mg/100 ml and treatment was associated with a mean LDLc reduction of 26.0 (12.6) mg/100 ml. Treatment with bempedoic acid significantly reduced the incidence of major adverse cardiovascular events (hazard ratio [HR] 0.88, 95% confidence interval [CI] 0.81 to 0.96), myocardial infarction (HR 0.76, 95% CI 0.66 to 0.89) and myocardial revascularization (HR 0.82, 95% CI 0.73 to 0.92); the crude incidence of stroke, cardiovascular or all-cause mortality were lower in patients in the bempedoic acid groups although no significant risk reduction was observed. No heterogeneity was observed in any of the end points. In conclusion, the metanalysis of the 4 clinical trials currently available with bempedoic acid provides reliable evidence of its clinical benefit with no signs of heterogeneity or harm.
Topics: Humans; Randomized Controlled Trials as Topic; Dicarboxylic Acids; Fatty Acids; Myocardial Infarction; Stroke
PubMed: 37633067
DOI: 10.1016/j.amjcard.2023.07.145 -
Aging Cell Oct 2023The metabolic consequences of mitophagy alterations due to age-related stress in healthy aging brains versus neurodegeneration remain unknown. Here, we demonstrate that...
The metabolic consequences of mitophagy alterations due to age-related stress in healthy aging brains versus neurodegeneration remain unknown. Here, we demonstrate that ceramide synthase 1 (CerS1) is transported to the outer mitochondrial membrane by the p17/PERMIT transporter that recognizes mislocalized mitochondrial ribosomes (mitoribosomes) via 39-FLRN-42 residues, inducing ceramide-mediated mitophagy. P17/PERMIT-CerS1-mediated mitophagy attenuated the argininosuccinate/fumarate/malate axis and induced d-glucose and fructose accumulation in neurons in culture and brain tissues (primarily in the cerebellum) of wild-type mice in vivo. These metabolic changes in response to sodium-selenite were nullified in the cerebellum of CerS1to/to (catalytically inactive for C18-ceramide production CerS1 mutant), PARKIN-/- or p17/PERMIT-/- mice that have dysfunctional mitophagy. Whereas sodium selenite induced mitophagy in the cerebellum and improved motor-neuron deficits in aged wild-type mice, exogenous fumarate or malate prevented mitophagy. Attenuating ceramide-mediated mitophagy enhanced damaged mitochondria accumulation and age-dependent sensorimotor abnormalities in p17/PERMIT-/- mice. Reinstituting mitophagy using a ceramide analog drug with selenium conjugate, LCL768, restored mitophagy and reduced malate/fumarate metabolism, improving sensorimotor deficits in old p17/PERMIT-/- mice. Thus, these data describe the metabolic consequences of alterations to p17/PERMIT/ceramide-mediated mitophagy associated with the loss of mitochondrial quality control in neurons and provide therapeutic options to overcome age-dependent sensorimotor deficits and related disorders like amyotrophic lateral sclerosis (ALS).
Topics: Mice; Animals; Mitophagy; Malates; Ceramides; Motor Neurons; Fumarates; Ubiquitin-Protein Ligases
PubMed: 37614052
DOI: 10.1111/acel.13954 -
Current Cardiology Reports Sep 2023To provide an updated review of bempedoic acid's clinical application in lowering LDL-C in the setting of statin intolerance and the recent findings in the CLEAR... (Review)
Review
PURPOSE OF REVIEW
To provide an updated review of bempedoic acid's clinical application in lowering LDL-C in the setting of statin intolerance and the recent findings in the CLEAR Outcomes trial as well as summarize and synthesize the current state of knowledge regarding bempedoic acid while providing an in-depth analysis of the drug's pharmacological properties, mechanism of action, clinical trials, safety, and efficacy.
RECENT FINDINGS
The CLEAR Outcomes trial has provided evidence to support bempedoic acid as a viable alternative to statins for the primary and secondary prevention of cardiovascular disease. Bempedoic acid is a promising treatment option for patients with hypercholesterolemia who are unable to tolerate statin therapy or require additional LDL-C reduction in the treatment of cardiovascular disease, with the newest lipid-lowering cardiovascular outcomes trials expanding on their generalizability particularly in the inclusion of women.
Topics: Humans; Female; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Cholesterol, LDL; Cardiovascular Diseases; Hypercholesterolemia; Dicarboxylic Acids; Fatty Acids
PubMed: 37405598
DOI: 10.1007/s11886-023-01911-9