Bempedoic acid and its role in contemporary management of hyperlipidemia in atherosclerosis

Role of gut microbiota in bempedoic acid against hyperlipidemia: a new candidate target for bempedoic acid on the therapeutic regulation

Background

Bempedoic acid (BA), an oral synthetic dicarboxylic acid derivative, has been widely used to treat patients with hyperlipidemia who are intolerant to statins. Both clinical and preclinical studies have reported the protective effects of BA against hyperlipidemia. However, the mechanisms of BA for hyperlipidemia treatment remain largely obscured. This study aimed to evaluate the effects of BA on hyperlipidemia and investigate the mechanism underlying its correlation with gut microbiota and serum metabolite regulation.

Methods

Four-week-old male C57BL/6J mice were fed a high-fat diet (HFD) and treated with BA daily for 20 weeks. Biochemical changes of serum were assessed, covering lipid metabolism, inflammation, and endothelial function. Moreover, 16S rRNA sequencing of gut microbiota as well as untargeted metabolomics analysis of serum were performed.

Results

The results showed that BA exerted potent efficacy against hyperlipidemia by attenuating serum lipid profiles, inhibiting vascular inflammation, and improving endothelial function. 16S rRNA sequencing revealed that BA improved the disorder of gut microbiota biodiversity. Specifically, BA significantly enriched the abundance of Akkermansia, Bacteroides, Roseburia, Faecalibacterium and Uncultured_bacterium_f_Muribaculaceae, which were closely associated with BA's therapeutic effects. Serum metabolomics analysis indicated that BA recovered the disturbances of serum metabolic phenotypes. A total of 20 differential metabolites were significantly regulated by BA treatment, suggesting that BA might exert effects by ameliorating relevant metabolic pathways, including bile acid biosynthesis, glycerophospholipid metabolism, β-oxidation of fatty acids and sphingolipid metabolism.

Conclusion

Taken together, the present study demonstrated that BA could inhibit the development of hyperlipidemia, and its protective effects may be related to alterations in gut microbiota composition and changes in serum metabolite abundances.

"Are new lipid lowering agents a good option for achieving lipid goals in people living with HIV? A case report"

The dyslipidemia in people living with HIV differs from the general population because combination antiretroviral therapy may not only induce dyslipidemia but also interact with lipid-lowering agents.Monoclonal antibodies that target proprotein convertase subtilisin/kexin type 9 (PCSK9) have recently been demonstrated to dramatically reduce LDL-C level (>60%) in the majority of cases, and another interesting new option is inclisiran, a first-in-class, cholesterol-lowering small interfering RNA (siRNA) targeting PCSK9 mRNA and conjugated to triantennary N-acetylgalactosamine carbohydrates (GalNAc).We present the clinical case of a 62-year-old man living with HIV and dyslipidemia in whom new hypolipidemic drugs were fundamental in achieving adequate LDL values to prevent cardiovascular events.

2024 KSoLA Update on New Lipid-Lowering Agents: Inclisiran and Bempedoic Acid

Inclisiran and bempedoic acid (BA) are non-statin lipid-lowering agents that have been approved for use in the US and Europe. Inclisiran, a subcutaneously administered small interfering RNA targeting proprotein convertase subtilisin/kexin type 9 messenger RNA, is effectively delivered to the liver via lipid nanoparticles and conjugation. In several phase 3 trials, it has successfully reduced low-density lipoprotein cholesterol (LDL-C) by 50% and has an acceptable safety profile. Currently, the results of clinical outcome studies are awaited. While it is indicated for both primary and secondary cardiovascular prevention, it is selectively recommended after statin-based regimens. BA, an oral inhibitor of adenosine triphosphate-citrate lyase, decreases cholesterol production and enhances LDL uptake by hepatocytes. This enzyme is absent in muscle cells, and BA has fewer muscle-related adverse events. In clinical trials, it lowered LDL-C by 17%-21% compared to placebo and showed a clinical outcome benefit in patients with statin intolerance. This agent modestly increases the incidence of gout and cholelithiasis. For primary and secondary prevention, it may be recommended as a non-first-line agent, either alone or in combination therapy.

Impact of payer rejections and out-of-pocket costs on patient access to bempedoic acid therapy

Background

Early uptake of novel cholesterol-lowering therapies was limited by extensive utilization management practices and high cost. Whether similar challenges affected access to bempedoic acid (BA) is unknown.

Methods

For all patients prescribed BA from the date of FDA approval (February 2020) through 12/31/2022 identified using nationwide pharmacy transaction data, we assessed whether their first prescription was approved or rejected. Multivariable logistic regression was performed to assess factors associated with approval. Among those approved, prescription fill rates were evaluated by out-of-pocket cost. For those with rejected prescriptions, changes in lipid-lowering therapy after rejection were described.

Results

Of 116,176 patients (median age 67 years; 56.6 % women) initially prescribed BA, 80,056 (68.9 %) received approval. Factors associated with approval included: commercial insurance (odds ratio [OR] 1.62 [95 % confidence interval (CI) 1.56, 1.68] vs. government insurance, P < 0.001), cardiology specialty prescriber (OR 1.39 [1.34, 1.44] vs. primary care physicians, P < 0.001), and prescriber volume (OR 1.44 [1.38, 1.51] for fourth [highest] quartile vs. first [lowest] quartile prescribers, P < 0.001). Of those who received approval, 82.4 % (n = 65,969) filled the prescription, while 17.3 % (n = 14,087) abandoned the prescription. Abandonment rates increased with increasing patient OOP costs. Escalation in an alternative lipid-lowering therapy over the subsequent year was observed in 36.2 % and 33.3 % of patients with rejected and abandoned prescriptions, respectively.

Conclusion

Nearly half of patients prescribed BA failed to receive therapy due to a combination of payer rejections and prescription abandonment. Arduous utilization management criteria or high OOP costs put patients at high risk for failure of therapy initiation.

Managing Myotonic Dystrophy Type 1 Complicated by Metabolic Syndrome

Myotonic dystrophy type 1 (MD1) is the most common form of muscular dystrophy in adults. MD1 is caused by the expansion of CTG repeats in the DMPK gene and affects various organs beyond muscles. We present a case of a patient with MD1 exhibiting features of metabolic syndrome (MetS), including insulin resistance and dyslipidemia. The patient was treated with PCSK9 inhibitors, ezetimibe, and bempedoic acid because of intolerance. Metabolic syndrome is more prevalent in patients with muscle disorders like MD1, primarily caused by the sedentary lifestyle associated with muscle weakness. Although no specific studies on MetS frequency in MD1 exist, data on its components are available. This case highlights the management of MetS in MD1 with innovative therapies. Managing metabolic syndrome in MD1 patients requires personalized therapies. This case introduces a promising therapeutic approach for statin-intolerant patients.

Sex differences in LDL-C reduction response to evolocumab: A propensity score matching analysis

BACKGROUND

Proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9i) have been shown to improve cardiovascular outcomes by reducing low-density lipoprotein cholesterol (LDL-C). However, sex differences in the efficacy of evolocumab remain unclear. This study aimed to investigate sex differences in the efficacy of evolocumab using real-world data.

METHOD

Data were collected from the First Affiliated Hospital of Guangxi Medical University. A total of 416 eligible patients were selected from 1463 patients treated with evolocumab for secondary prevention. Clinical data, including individual characteristics and lipids profiles, were recorded. Propensity score matching (PSM) was used to control for potential confounders, with covariates including age, body mass index, smoking status, and diabetes. All eligible participants were propensity-matched 1:1 for female versus male with a match tolerance of 0.02. The efficacy of evolocumab in females and males was compared by PSM-adjusted analysis.

RESULTS

In the PSM analysis, a significant difference was found in the relative percentage reduction of LDL-C between females and males (-42.7% vs. -54.4%, p < 0.001). In addition, the absolute LDL-C reduction was lower in females compared to males (interquartile range: -1.5 [-2.2, -0.8] mmol/L vs. -1.9 [-2.5, -1.0] mmol/L, p = 0.018). The rate of target LDL-C attainment was lower in females than in males after treatment with evolocumab (21.6% vs. 39.8%, p = 0.009).

CONCLUSION

These results suggest that males have a better response to evolocumab in term of LDL-C reduction compared to females.

Effects of bempedoic acid on markers of inflammation and Lp(a)

PURPOSE OF REVIEW

To study the effect of bempedoic acid on markers of inflammation and lipoprotein (a) to help determine if the drug would be useful to treat patients with elevated cardiovascular risks and residual cardiovascular risk despite optimal low-density lipoprotein cholesterol (LDL-C) levels.

RECENT FINDINGS

Bempedoic acid is found to cause significant reduction in LDL-C and high-sensitivity C-reactive protein (hs-CRP) in various randomized clinical trials. Multiple meta-analyses have also found that bempedoic acid therapy leads to reduction in non-high-density lipoprotein cholesterol (non-HDL-C), total cholesterol (TC) and apolipoprotein B (ApoB) levels. However, it has minimal effect on lipoprotein (a) (Lp(a)) level.

SUMMARY

Bempedoic acid is a new lipid-lowering agent that inhibits enzyme ATP-citrate lyase in the cholesterol biosynthesis pathway. Major risk of cardiovascular events and its associated morbidity and mortality are proportional to LDL-C and inflammatory markers levels. It was found that bempedoic acid significantly lowers LDL-C, hs-CRP and other inflammatory markers levels. This drug could potentially be used in patients with elevated cardiovascular risk, in patients with residual cardiovascular risk despite attaining LDL-C goal and in statin intolerant patients.

The regulatory effect of polysaccharides on the gut microbiota and their effect on human health: A review

Polysaccharides with low toxicity and high biological activities are a kind of biological macromolecule. Recently, growing studies have confirmed that polysaccharides could improve obesity, diabetes, tumors, inflammatory bowel disease, hyperlipidemia, diarrhea, and liver-related diseases by changing the intestinal micro-environment. Moreover, polysaccharides could promote human health by regulating gut microbiota, enhancing production of short-chain fatty acids (SCFAs), improving intestinal mucosal barrier, regulating lipid metabolism, and activating specific signaling pathways. Notably, the biological activities of polysaccharides are closely related to their molecular weight, monosaccharide composition, glycosidic bond types, and regulation of gut microbiota. The intestinal microbiota can secrete glycoside hydrolases, lyases, and esterases to break down polysaccharides chains and generate monosaccharides, thereby promoting their absorption and utilization. The degradation of polysaccharides can produce SCFAs, further regulating the proportion of gut microbiota and achieving the effect of preventing and treating various diseases. This review aims to summarize the latest studies: 1) effect of polysaccharides structures on intestinal flora; 2) regulatory effect of polysaccharides on gut microbiota; 3) effects of polysaccharides on gut microbe-mediated diseases; 4) regulation of gut microbiota on polysaccharides metabolism. The findings are expected to provide important information for the development of polysaccharides and the treatment of diseases.

Coronary Plaque Erosion: Epidemiology, Diagnosis, and Treatment

Plaque erosion (PE), a distinct etiology of acute coronary syndromes (ACSs), is often overshadowed by plaque ruptures (PRs). Concerning its epidemiology, PE has garnered increasing recognition, with recent studies revealing its prevalence to be approximately 40% among ACS patients, challenging earlier assumptions based on autopsy data. Notably, PE exhibits distinct epidemiological features, preferentially affecting younger demographics, particularly women, and often manifesting as a non-ST-segment elevation myocardial infarction. There are seasonal variations, with PE events being less common in winter, potentially linked to physiological changes and cholesterol solidification, while peaking in summer, warranting further investigation. Moving to molecular mechanisms, PE presents a unique profile characterized by a lesser degree of inflammation compared to PR, with endothelial shear stress emerging as a plausible molecular mechanism. Neutrophil activation, toll-like receptor-2 pathways, and hyaluronidase 2 expression are among the factors implicated in PE pathophysiology, underscoring its multifactorial nature. Advancements in intravascular imaging diagnostics, particularly optical coherence tomography and near-infrared spectroscopy coupled with intravascular ultrasound, offer unprecedented insights into plaque composition and morphology. Artificial intelligence algorithms show promise in enhancing diagnostic accuracy and streamlining image interpretation, augmenting clinician decision-making. Therapeutically, the management of PE evolves, with studies exploring less invasive approaches such as antithrombotic therapy without stenting, particularly in cases identified early through intravascular imaging. Additionally, the potential role of drug-coated balloons in reducing thrombus burden and minimizing future major adverse cardiovascular events warrants further investigation. Looking ahead, the integration of advanced imaging modalities, biomarkers, and artificial intelligence promises to revolutionize the diagnosis and treatment of coronary PE, ushering in a new era of personalized and precise cardiovascular care.

Efficacy and Safety of Bempedoic Acid in Patients With Hyperlipidemia and Non-alcoholic Fatty Liver Disease

Hyperlipidemia and its association with cardiovascular diseases have been significant public health concerns for many decades. Statins have long been the primary therapeutic option for lowering cholesterol levels and reducing cardiovascular mortality. However, a substantial number of patients either do not achieve optimal lipid goals with maximally tolerated statin doses or experience statin intolerance. In recent years, there have been remarkable developments in the field of hyperlipidemia management, leading to the approval of novel hypolipidemic drugs in North America and Europe. This article reviews the clinical development of bempedoic acid, a promising new drug, alone and in combination with ezetimibe, as an alternative approach to managing hyperlipidemia. The Phase I trials established the safety and tolerability of bempedoic acid, paving the way for further investigation in Phase II and Phase III trials. Multiple phase II studies evaluated the lipid-lowering efficacy of bempedoic acid as monotherapy or in combination with other hypolipidemic agents, showing significant improvements in lipid levels and inflammatory markers. The recently approved fixed drug combination of bempedoic acid and ezetimibe presents a viable option for patients who need additional LDL-C lowering alongside dietary modifications and maximally tolerated statin therapy.

Bempedoic acid: new evidence and recommendations on use

PURPOSES OF REVIEW

Cardiovascular diseases (CVDs) are the leading cause of mortality and morbidity worldwide. Recognizing the importance of dyslipidemia treatment in the prevention of cardiovascular events has become a part of standard clinical practice. Desired values of LDL cholesterol (LDL-C) have become lower and lower in the last few decades, as evidenced by the most recent guidelines. Therefore, efforts to lower LDL cholesterol concentrations with conventional therapies and combinations of lipid-lowering therapy may not be successful in a high proportion of patients.

RECENT FINDINGS

Bempedoic acid is a novel agent, first in-class ATP Citrate Lyase (ACL) inhibitor, which targets biosynthesis of the cholesterol in the liver. Considering the results of phase 3 studies, it has been approved for sole use for dyslipidemia treatment for patients who are statin-intolerant or in combination with statin-ezetimibe for those suffering from familial hypercholesterolemia or ASCVD and unable to reach targeted LDL-C values.

SUMMARY

Bempedoic acid has proven beneficial for further reduction of LDL cholesterol for targeted groups of patients. It is not only efficient but also a well tolerated, affordable, and available agent whose place in lipid-lowering management is yet to be fully understood with new data collected from ongoing clinical research. In this review we suggest the place of bempedoic acid in lipid-lowering management.

Efficacy and Safety of Bempedoic Acid in Patients with High Cardiovascular Risk: An Update

Statins play a significant role in the prevention of cardiovascular (CV) diseases (CVDs); however, non-adherence with statin treatment or statin intolerance (mainly attributed to muscleassociated side effects) is not uncommon. New agents such as bempedoic acid (BA) can provide more treatment options. BA is administered orally, once daily, at a dose of 180 mg in current clinical practice. It can decrease circulating low-density lipoprotein cholesterol (LDL-C) levels by nearly 30% as monotherapy or by 20% as an add-on to statins. CV outcome studies have shown that BA decreases major adverse CV event risk in patients with established CVD or high CV risk by 13%. When patients with high CV risk were analyzed alone, the risk reduction was 30%. Its side effects include a rise in serum uric acid levels and liver enzyme activity, whereas it does not increase diabetes risk as statins do. BA can be used as adjunctive therapy to statins in patients at high CV risk in whom lipid targets cannot be achieved or as an alternative to statins in patients with statin intolerance.

Lovastatin Treatment Inducing Apoptosis in Human Pancreatic Cancer Cells by Inhibiting Cholesterol Rafts in Plasma Membrane and Mitochondria

Resistance to anticancer drugs is a problem in the treatment of pancreatic ductal carcinoma (PDAC) and overcoming it is an important issue. Recently, it has been reported that statins induce apoptosis in cancer cells but the mechanism has not been completely elucidated. We investigated the antitumor mechanisms of statins against PDAC and their impact on resistance to gemcitabine (GEM). Lovastatin (LOVA) increased mitochondrial oxidative stress in PDAC cells, leading to apoptosis. LOVA reduced lipid rafts in the plasma membrane and mitochondria, suppressed the activation of epithelial growth factor receptor (EGFR) and AKT in plasma membrane rafts, and reduced B-cell lymphoma 2 (BCL2)-Bcl-2-associated X protein (BAX) binding and the translocation of F1F0 ATPase in mitochondrial rafts. In the three GEM-resistant cell lines derived from MIA and PANC1, the lipid rafts in the cell membrane and the mitochondria were increased to activate EGFR and AKT and to increase BCL2-BAX binding, which suppressed apoptosis. LOVA abrogated these anti-apoptotic effects by reducing the rafts in the resistant cells. By treating the resistant cells with LOVA, GEM sensitivity improved to the level of the parental cells. Therefore, cholesterol rafts contribute to drug resistance in PDAC. Further clinical research is warranted on overcoming anticancer drug resistance by statin-mediated intracellular cholesterol regulation.

Machine Learning Applied to Cholesterol-Lowering Pharmacotherapy: Proof-of-Concept in High-Risk Patients Treated in Primary Care

Objectives: Machine learning has potential to improve the management of lipid disorders. We explored the utility of machine learning in high-risk patients in primary care receiving cholesterol-lowering medications. Methods: Machine learning algorithms were created based on lipid management guidelines for England [National Institute for Health and Care Excellence (NICE) CG181] to reproduce the guidance with >95% accuracy. Natural language processing and therapy identification algorithms were applied to anonymized electronic records from six South London primary care general practices to extract medication information from free text fields. Results: Among a total of 48,226 adult patients, a subset of 5630 (mean ± standard deviation, age = 67 ± 13 years; male:female = 55:45) with a history of lipid-lowering therapy were identified. Additional major cardiometabolic comorbidities included type 2 diabetes in 13% (n = 724) and hypertension in 32% (n = 1791); all three risk factors were present in a further 28% (n = 1552). Of the 5630 patients, 4290 (76%) and 1349 (24%) were in primary and secondary cardiovascular disease prevention cohorts, respectively. Statin monotherapy was the most common current medication (82%, n = 4632). For patients receiving statin monotherapy, 71% (n = 3269) were on high-intensity therapy aligned with NICE guidance with rates being similar for the primary and secondary prevention cohorts. In the combined cohort, only 46% of patients who had been prescribed lipid-lowering therapy in the previous 12 months achieved the NICE treatment goal of >40% reduction in non-high-density lipoprotein cholesterol from baseline pretreatment levels. Based on the most recent data entry for patients not at goal the neural network recommended either increasing the dose of statin, adding complementary cholesterol-lowering medication, or obtaining an expert lipid opinion. Conclusions: Machine learning can be of value in (a) quantifying suboptimal lipid-lowering prescribing patterns, (b) identifying high-risk patients who could benefit from more intensive therapy, and (c) suggesting evidence-based therapeutic options.

Pathophysiology of Acute Coronary Syndromes-Diagnostic and Treatment Considerations

Coronary artery disease and acute coronary syndromes are accountable for significant morbidity and mortality, despite the preventive measures and technological advancements in their management. Thus, it is mandatory to further explore the pathophysiology in order to provide tailored and more effective therapies, since acute coronary syndrome pathogenesis is more varied than previously assumed. It consists of plaque rupture, plaque erosion, and calcified nodules. The advancement of vascular imaging tools has been critical in this regard, redefining the epidemiology of each mechanism. When it comes to acute coronary syndrome management, the presence of ruptured plaques almost always necessitates emergent reperfusion, whereas the presence of plaque erosions may indicate the possibility of conservative management with potent antiplatelet and anti-atherosclerotic medications. Calcified nodules, on the other hand, are an uncommon phenomenon that has largely gone unexplored in terms of the best management plan. Future studies should further establish the importance of detecting the underlying mechanism and the role of various treatment plans in each of these distinct entities.

Tyrosine kinase inhibitors and atherosclerosis: A close but complicated relationship

Targeted cancer therapies have revolutionized the treatment of the disease in the past decade. The tyrosine kinase inhibitor (TKI) class of drugs is a widely used option for treating various cancers. Despite numerous advances, clinical and experimental studies have demonstrated the atherosclerosis-inducing properties of these drugs that can cause adverse cardiovascular events. TKIs also have an atherosclerosis-preventing role in patients with cancer through different mechanisms under various conditions, suggesting that specific drugs play different roles in atherosclerosis regulation. Given these contradictory properties, this review summarizes the outcomes of previously performed clinical and basic experiments and shows how the targeted effects of novel TKIs affect atherosclerosis. Future collaborative efforts are warranted to enhance our understanding of the association between TKIs and atherosclerosis.

Assessment of hypolipidemic and anti-inflammatory properties of walnut (Juglans regia) seed coat extract and modulates some metabolic enzymes activity in triton WR-1339-induced hyperlipidemia in rat kidney, liver, and heart

Atherosclerosis and cognitive impairment are both influenced by hyperlipidemia. Due to their high margin of safety and low cost, natural chemicals have recently attracted particular attention in the context of the treatment of disease. Hence, the purpose of this study was to investigate the possible amendatory impact of ethanol extract walnut (Juglans regia) seed coat (E-WSC) on some metabolic enzymes (glutathione reductase (GR), paraoxonase-1 (PON1), aldose reductase (AR), sorbitol dehydrogenase (SDH), acetylcholinesterase (AChE), glutathione S-transferase (GST), and butyrylcholinesterase (BChE)) activity in the liver, kidney, and heart of rats with Triton WR-1339-induced hyperlipidemia. Rats were divided into five groups: control group, HL-Control group (Triton WR-1339 400 mg/kg, i.p administered group), E- WSC + 150 (150 mg/kg,o.d given group), E- WSC + 300 (E- WSC 300 mg/kg, o.d given group) and HL+ E-WSC + 300 (Group receiving E- WSC 300 mg/kg, o.d 30 min prior to administration of Triton WR-1339 400 mg/kg, i.p). In HL-Control, AR, SDH, and BChE enzyme activity was significantly increased in all tissues compared to the control, while the activity of other studied enzymes was significantly decreased. The effects of hyperlipidemia on balance were improved and alterations in the activity of the investigated metabolic enzymes were prevented by E-WSC. As a result, promising natural compounds that can be used as adjuvant therapy in the treatment of cognitive disorders and hyperlipidemia may be found in E-WSC powder.

Serum Low Density Lipoprotein Cholesterol Concentration Is Not Dependent on Cholesterol Synthesis and Absorption in Healthy Humans

Introduction. Pharmacological reduction of cholesterol (C) synthesis and C absorption lowers serum low-density lipoprotein C (LDL-C) concentrations. We questioned whether high baseline C synthesis or C absorption translates into high serum LDL-C concentrations or if there was no connection. Therefore, we studied the association between serum LDL-C and C synthesis or C absorption in healthy subjects. Methods. Three published data sets of young subjects on different diets (study 1), mildly hypercholesterolemic subjects without cardiovascular disease (study 2) and healthy controls of the Framingham study (study 3) were used. The three study populations varied in sex, age, and weight. C synthesis and C fractional absorption rate (FAR) were measured with fecal sterol balance and stable isotope techniques (studies 1 and 2). Additionally, serum lathosterol and campesterol concentrations corrected for the serum total C concentration (R_lathosterol and R_campesterol) were used as markers for hepatic C synthesis and C FAR, respectively (studies 1−3). Linear regression analysis was applied to evaluate associations between LDL-C, C synthesis, and C absorption. Results. Seventy-three, 37, and 175 subjects were included in studies 1, 2, and 3, respectively. No statistically significant associations were found between LDL-C and the measured C synthesis and C FAR, nor for R_lathosterol and R_campesterol in any of the study groups. This lack of associations was confirmed by comparing the male subjects of studies 1 and 2. Study 1 subjects had a 50% lower serum LDL-C than the study 2 subjects (p < 0.01), but not a lower C synthesis, C FAR, R-lathosterol, or R_campesterol. Conclusions. Under physiological conditions, C synthesis and C FAR are not major determinants of circulating serum LDL-C concentrations in healthy subjects. The results need to be confirmed in large-scale studies in healthy subjects and patients at risk for cardiovascular disease.

Ergosterol increases 7-dehydrocholesterol, a cholesterol precursor, and decreases cholesterol in human HepG2 cells

Current treatment approaches for hyperlipidemia rely mainly on reducing the cholesterol level by inhibiting 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), which is involved in the presqualene pathway of cholesterol biosynthesis. Finding a compound that instead targets the postsqualene pathway could aid in the treatment of hyperlipidemia and synergistically reduce the cholesterol level when used in conjunction with HMGCR inhibitors. Ergosterol is a fungal sterol that is converted to brassicasterol by 7-dehydrocholesterol reductase (DHCR7). DHCR7 is also a cholesterol biosynthesis enzyme, and thus ergosterol may cause the accumulation of 7-dehydrocholesterol, a precursor of cholesterol and vitamin D₃ , by a competitive effect. In this study, we examined the effect of ergosterol on the postsqualene pathway by quantifying cholesterol precursors and related sterols using gas chromatography-mass spectrometry and by conducting quantitative RT-PCR and western blot analysis for human HepG2 hepatoma cells. We found that ergosterol is converted into brassicasterol by the action of DHCR7 from HepG2 cells and that it induced the accumulation of cholesterol precursors (lathosterol, 7-dehydrocholesterol, and desmosterol) and decreased the cholesterol level by altering the mRNA and protein levels of cholesterol biosynthesis enzymes (increase of sterol 8,7-isomerase [EBP] and decrease of DHCR7 and 24-dehydrocholesterol reductase [DHCR24]). These results demonstrate that ergosterol inhibits the postsqualene pathway and may be useful for the prevention of hyperlipidemia.

Regulatory Effects of Statins on SIRT1 and Other Sirtuins in Cardiovascular Diseases

Adverse cardiovascular disease (CVD) outcomes, such as sudden cardiac death, acute myocardial infarction, and stroke, are often catastrophic. Statins are frequently used to attenuate the risk of CVD-associated morbidity and mortality through their impact on lipids and they may also have anti-inflammatory and other plaque-stabilization effects via different signaling pathways. Different statins, including atorvastatin, rosuvastatin, pravastatin, pitavastatin, and simvastatin, are administered to manage circulatory lipid levels. In addition, statins are potent inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMGCoA) reductase via modulating sirtuins (SIRTs). During the last two decades, SIRTs have been investigated in mammals and categorized as a family of nicotinamide adenine dinucleotide (NAD)-dependent histone deacetylases (HDACs) with significant oxidative stress regulatory function in cells-a key factor in extending cell lifespan. Recent work has demonstrated that statins upregulate SIRT1 and SIRT2 and downregulate SIRT6 in both in vitro and in vivo experiments and clinical trials. As statins show modulatory properties, especially in CVDs, future investigations are needed to delineate the role of SIRT family members in disease and to expand knowledge about the effects of statins on SIRTs. Here, we review what is currently known about the impact of statins on SIRTs and how these changes correlate with disease, particularly CVDs.