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1.
Targeting the Cholesterol Paradigm in the Risk Reduction for Atherosclerotic Cardiovascular Disease: Does the Mechanism of Action of Pharmacotherapy Matter for Clinical Outcomes?
Zhou, R, Stouffer, GA, Smith, SC
Journal of cardiovascular pharmacology and therapeutics. 2021;(6):533-549
Abstract
Hypercholesterolemia is a well-established risk factor for atherosclerotic cardiovascular disease (ASCVD). Low-density lipoprotein cholesterol (LDL-C) has been labeled as "bad" cholesterol and high-density lipoprotein cholesterol (HDL-C) as "good" cholesterol. The prevailing hypothesis is that lowering blood cholesterol levels, especially LDL-C, reduces vascular deposition and retention of cholesterol or apolipoprotein B (apoB)-containing lipoproteins which are atherogenic. We review herein the clinical trial data on different pharmacological approaches to lowering blood cholesterol and propose that the mechanism of action of cholesterol lowering, as well as the amplitude of cholesterol reduction, are critically important in leading to improved clinical outcomes in ASCVD. The effects of bile acid sequestrants, fibrates, niacin, cholesteryl ester transfer protein (CETP) inhibitors, apolipoprotein A-I and HDL mimetics, apoB regulators, acyl coenzyme A: cholesterol acyltransferase (ACAT) inhibitors, cholesterol absorption inhibitors, statins, and proprotein convertase subtilisin kexin 9 (PCSK9) inhibitors, among other strategies are reviewed. Clinical evidence supports that different classes of cholesterol lowering or lipoprotein regulating approaches yielded variable effects on ASCVD outcomes, especially in cardiovascular and all-cause mortality. Statins are the most widely used cholesterol lowering agents and have the best proven cardiovascular event and survival benefits. Manipulating cholesterol levels by specific targeting of apoproteins or lipoproteins has not yielded clinical benefit. Understanding why lowering LDL-C by different approaches varies in clinical outcomes of ASCVD, especially in survival benefit, may shed further light on our evolving understanding of how cholesterol and its carrier lipoproteins are involved in ASCVD and aid in developing effective pharmacological strategies to improve the clinical outcomes of ASCVD.
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2.
Umbrella Review on Non-Statin Lipid-Lowering Therapy.
Beshir, SA, Hussain, N, Elnor, AA, Said, ASA
Journal of cardiovascular pharmacology and therapeutics. 2021;(5):437-452
Abstract
OBJECTIVES The main aim of this review was to summarize current evidence on approved and emerging non-statin lipid-lowering therapies. METHODS AND MATERIALS Recent literature on U.S. FDA approved non-statin lipid-lowering therapies and evolving lipid-lowering drugs currently under development was reviewed. RESULTS AND DISCUSSION In the past 20 years, the emergence of non-statin cholesterol-lowering drugs has changed the landscape of dyslipidemia management. Food and Drug Administration approval of non-statin lipid-lowering therapies such as ezetimibe, proprotein convertase subtilisin/Kexin type 9 (PCSK9) inhibitors (evolocumab, alirocumab), bempedoic acid and combination of bempedoic acid and ezetimibe, evinacumab and other triglyceride-lowering agents (eg, icosapent ethyl) has emerged. The European Commission has also recently approved inclisiran for treatment of hypercholesterolemia and mixed hypercholesterolemia even though FDA has put the approval of this drug on hold. Recent guidelines have incorporated PCSK9 inhibitors to treat patients with primary hyperlipidemia and patients with very high-risk ASCVD, who could not achieve adequate lipid-lowering with combination therapy of maximally tolerated statin and ezetimibe. Icosapent ethyl use as an adjunct therapy to statins is also recommended to reduce the risk of ASCVD in patients with hypertriglyceridemia. CONCLUSION Despite cost limitations, the uptake of PCSK9 inhibitors is increasing. Approval of bempedoic acid alone or in combination with ezetimibe has provided additional oral lipid-lowering drug alternatives to ezetimibe. Various lipid-lowering drug targets are under investigation.
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3.
Natural products: The role and mechanism in low-density lipoprotein oxidation and atherosclerosis.
Zhang, S, Li, L, Chen, W, Xu, S, Feng, X, Zhang, L
Phytotherapy research : PTR. 2021;(6):2945-2967
Abstract
Atherosclerosis is a chronic inflammatory, metabolic, and epigenetic disease, which leads to the life-threatening coronary artery disease. Emerging studies from bench to bedside have demonstrated the pivotal role of low-density lipoprotein (LDL) oxidation in the initiation and progression of atherosclerosis. This article hereby reviews oxidation mechanism of LDL, and the pro-atherogenic and biomarker role of oxidized LDL in atherosclerosis. We also review the pharmacological effects of several representative natural products (vitamin E, resveratrol, quercetin, probucol, tanshinone IIA, epigallocatechin gallate, and Lycopene) in protecting against LDL oxidation and atherosclerosis. Clinical and basic research supports the beneficial effects of these natural products in inhibiting LDL oxidation and preventing atherosclerosis, but the data are still controversial. This may be related to factors such as the population and the dosage and time of taking natural products involved in different studies. Understanding the mechanism of LDL oxidation and effect of oxidized LDL help researchers to find novel therapies against atherosclerosis.
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4.
Lipoprotein(a): is it more, less or equal to LDL as a causal factor for cardiovascular disease and mortality?
Langsted, A, Nordestgaard, BG
Current opinion in lipidology. 2020;(3):125-131
Abstract
PURPOSE OF REVIEW To summarize the recent studies directly comparing LDL and lipoprotein(a) as causal factors for cardiovascular disease and mortality. RECENT FINDINGS In approximately 100,000 individuals from the Copenhagen General Population Study for risk of myocardial infarction, in observational analyses per 39 mg/dl (1 mmol/l) cholesterol increase, the hazard ratio was 1.3 (95% confidence interval: 1.2-1.3) for LDL cholesterol and 1.6 (1.4-1.9) for lipoprotein(a) cholesterol. In corresponding genetic analyses, the causal risk ratio was 2.1 (1.3-3.4) for LDL and 2.0 (1.6-2.6) for lipoprotein(a). Also, a 15 mg/dl (0.39 mmol/l) cholesterol increase was associated with a hazard ratio for cardiovascular mortality of 1.05 (1.04-1.07) for LDL cholesterol and 1.18 (1.12-1.25) for lipoprotein(a) cholesterol. Corresponding values for all-cause mortality were 1.01 (1.00-1.01) for LDL cholesterol and 1.07 (1.04-1.10) for lipoprotein(a) cholesterol. In genetic, causal analyses, the mortality increases for elevated lipoprotein(a) appeared to be through apolipoprotein(a) kringle IV-2 rather than through lipoprotein(a) levels per se. SUMMARY On cholesterol scales, lipoprotein(a) and LDL appeared equal as causal factors for myocardial infarction; however, lipoprotein(a) was most important for mortality. Lipoprotein(a) effects may not only be due to cholesterol content but could also be due to the structure of lipoprotein(a) resembling plasminogen.
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5.
The Role of Halogenative Stress in Atherogenic Modification of Low-Density Lipoproteins.
Panasenko, OM, Torkhovskaya, TI, Gorudko, IV, Sokolov, AV
Biochemistry. Biokhimiia. 2020;(Suppl 1):S34-S55
Abstract
This review discusses formation of reactive halogen species (RHS) catalyzed by myeloperoxidase (MPO), an enzyme mostly present in leukocytes. An imbalance between the RHS production and body's ability to remove or neutralize them leads to the development of halogenative stress. RHS reactions with proteins, lipids, carbohydrates, and antioxidants in the content of low-density lipoproteins (LDLs) of the human blood are described. MPO binds site-specifically to the LDL surface and modifies LDL properties and structural organization, which leads to the LDL conversion into proatherogenic forms captured by monocytes/macrophages, which causes accumulation of cholesterol and its esters in these cells and their transformation into foam cells, the basis of atherosclerotic plaques. The review describes the biomarkers of MPO enzymatic activity and halogenative stress, as well as the involvement of the latter in the development of atherosclerosis.
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6.
The LDL-Receptor and its Molecular Properties: From Theory to Novel Biochemical and Pharmacological Approaches in Reducing LDL-cholesterol.
Petroglou, D, Kanellos, I, Savopoulos, C, Kaiafa, G, Chrysochoou, A, Skantzis, P, Daios, S, Hatzitolios, AI, Giannoglou, G
Current medicinal chemistry. 2020;(2):317-333
Abstract
BACKGROUND The Low-Density Lipoprotein (LDL) Receptor (LDL-R) is a transmembrane protein playing a crucial role in effective lipid homeostasis. Various therapeutic agents have been used in the management of dyslipidemias, however, the outcome of therapeutic target is debated. OBJECTIVE The aim of this review is to summarize and fully understand the current concept regarding LDL-R and its molecular properties, metabolic pathway, factors affecting LDL-R activity and all available pharmacological interventions. Additionally, non-lipid related properties of LDL-R are also referred. METHODS Literature from the PubMed database was extracted to identify papers between 1984 to 2017 regarding LDL-R and therapeutic agents on dyslipidemia management. RESULTS We analyzed basic data regarding agents associated with LDL-R (Sterol Regulating Element-Binding Proteins - SREBPs, Protein ARH, IDOL, Thyroid Hormones, Haematologic Disorders, Protein convertase subtilisin kexintype 9 - PCSK-9, ApoC-III) as well as non-lipid related properties of LDL-R, while all relevant (common and novel) pharmacological interventions (statins, fibrates, cholesterol absorption inhibitors, bile acid sequestrants and PCSK- 9) are also referred. CONCLUSION LDL-R and its molecular properties are involved in lipid homeostasis, so potentially sets the therapeutic goals in cardiovascular patients, which is usually debated. Further research is needed in order to fully understand its properties, as well as to find the potential pharmacological interventions that could be beneficial in cholesterol homeostasis and various morbidities in order to reach the most appropriate therapeutic goal.
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7.
Non-HDL-cholesterol and apolipoprotein B compared with LDL-cholesterol in atherosclerotic cardiovascular disease risk assessment.
Carr, SS, Hooper, AJ, Sullivan, DR, Burnett, JR
Pathology. 2019;(2):148-154
Abstract
Low density lipoprotein (LDL) is the predominant atherogenic lipoprotein particle in the circulation. Conventionally, a fasting lipid profile has been used for atherosclerotic cardiovascular disease (ASCVD) risk assessment. A non-fasting sample is now regarded as a suitable alternative to a fasting sample. In routine clinical practice, the Friedewald equation is used to estimate LDL-cholesterol, but it has limitations. Commercially available direct measures of LDL-cholesterol are not standardised. LDL-cholesterol is a well-established risk factor for ASCVD, being the primary therapeutic target in both primary and secondary prevention. Non-high-density lipoprotein (HDL)-cholesterol is a measure of the cholesterol content in the atherogenic lipoproteins, but it does not reflect the particle number. Non-HDL-cholesterol has the advantage over LDL-cholesterol of including remnant cholesterol and being independent of triglyceride variability, but it is compromised by the non-specificity bias of direct HDL-cholesterol methods used in the calculation. Apolipoprotein (apo) B, the major structural protein in very low-density lipoprotein, intermediate density lipoprotein, LDL and lipoprotein (a), is a measure of the number of atherogenic lipoproteins. ApoB methods are standardised, but the assay comes at an additional, albeit relatively low cost. Non-HDL-cholesterol and apoB are more accurate measures than LDL-cholesterol in hypertriglyceridaemic individuals, non-fasting samples, and in those with very-low LDL-cholesterol concentrations. Accumulating evidence suggests that non-HDL-cholesterol and apoB are superior to LDL-cholesterol in predicting ASCVD risk, and both have been designated as secondary targets in some treatment guidelines. We review the measurement, potential role, utility and current status of non-HDL-cholesterol and apoB when compared with LDL-cholesterol in ASCVD risk assessment.
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8.
Incretins and Lipid Metabolism.
Tsimihodimos, V, Elisaf, M
Current medicinal chemistry. 2018;(18):2133-2139
Abstract
BACKGROUND Recent findings indicate that incretin hormones and incretin-based therapies may affect the metabolism of lipoproteins, although the corresponding mechanisms are not clearly defined. OBJECTIVE To summarize the available data on the mechanisms linking incretins with the characteristics of serum lipoproteins and discuss the clinical implications of these relationships. METHODS PubMed was searched using the terms "incretins", "GLP-1", "GIP" and "lipids", "dyslipidemia", "triglycerides", "apolipoprotein B48". All articles published in the English language until June 2016 were assessed and the relevant information is presented here. RESULTS GLP-1, and therapies that increase its activity, exert a beneficial effect on lipoprotein metabolism that is translated in a reduction in the fasting and postprandial concentration of triglycerides and a small improvement in the concentration and function of HDLs. In addition, a shift towards larger, less atherogenic particles usually follows the administration of GLP-1 receptor agonists. The mechanisms that underlie these changes involve a direct effect of GLP- 1 on the hepatic and intestinal production of triglyceride-rich lipoproteins, the GLP-1 induced increase in the production and function of insulin, the activation of specific areas of central nervous system as well as the increase in the peripheral utilization of triglycerides for energy production. On the other hand, GLP-2 increases the absorption of dietary fat and the production of triglyceride-rich lipoproteins while the role of GIP on lipid metabolism remains indeterminate. CONCLUSION GLP-1 and incretin-based therapies favorably affect lipid metabolism. These effects may contribute to the beneficial effects of incretin-based therapies on atherosclerosis and fatty liver disease.
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9.
Favorable effects of hydroxychloroquine on serum low density lipid in patients with systemic lupus erythematosus: A systematic review and meta-analysis.
Babary, H, Liu, X, Ayatollahi, Y, Chen, XP, Doo, L, Uppaluru, LK, Kwak, MK, Kulaga, C, Modjinou, D, Olech, E, et al
International journal of rheumatic diseases. 2018;(1):84-92
Abstract
AIMS: Hydroxychloroquine (HCQ) has shown to have significant immunomodulatory effects in the treatment of systemic lupus erythematosus (SLE). Current studies show favorable effects of HCQ on traditional cardiac risk factors in patients with SLE. This review examined the effects of HCQ on serum low-density lipoprotein (LDL) level in patients with SLE. METHODS A systematic search of seven major literature search databases from their inception until 3 April, 2017 identified nine studies. Random-effects pooled mean difference with corresponding 95% confidence intervals (CI) were estimated. Heterogeneity was measured by I2 . Publication bias was assessed by visual inspection of funnel plots. Sensitivity analysis examined whether HCQ effect on serum total cholesterol level was similar to the main analysis. The Grading of Recommendations Assessment, Development, and Evaluation system was used to assess the overall quality of evidence. RESULTS Pooled study participants were 559 patients from eight observation studies (two before-after studies; six case-control studies) examining the effects of HCQ on serum LDL. Pooled study participants' characteristics were as follows: mean age 45.719, female 95.262%, and prednisone use 58.366%. HCQ reduced mean LDL levels by 24.397 mg/dL (95% CI 8.921-39.872; P = 0.002). The number of studies identifying statin use was too few to perform meta-regression analysis of statin use. Heterogeneity was extensive (I2 = 94.739%). Symmetrical funnel plot visualized no evidence of publication bias. CONCLUSION HCQ was associated with serum LDL level reduction by mean 24.397 mg/dL in patients with SLE. Future prospective studies are need to fully characterize the treatment effect.
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10.
The enigmatic membrane fatty acid transporter CD36: New insights into fatty acid binding and their effects on uptake of oxidized LDL.
Jay, AG, Hamilton, JA
Prostaglandins, leukotrienes, and essential fatty acids. 2018;:64-70
Abstract
The scavenger receptor CD36 binds numerous small biomolecules, including fatty acids, and even large ligands such as oxidized LDL, for which it is considered a receptor. Although CD36 has often been postulated to "transport" fatty acids across the plasma membrane, fatty acids translocation (mass transport or kinetics) was not affected by expression of CD36 in HEK293 cells; however, esterification of fatty acids (cellular uptake) was increased. These recent results from our lab are consistent with the established mechanism of fatty acid entry into cells by passive diffusion (flip-flop) and also with the well-documented enhancement of uptake of fatty acids by CD36 in other cell types. A fascinating new discovery is that CD36 has multiple fatty acid binding sites on the extracellular domain of CD36. As illuminated by new methodologies that we have applied, these sites have high affinity and exhibit rapid exchange with the medium. In an initial study of functional consequences of binding, several dietary fatty acids enhanced uptake of oxidized LDL into HEK293 cells expressing CD36. This is the first established link between physical binding of fatty acids and a function of CD36, and has implications for obesity and atherosclerosis. New methods as those used in our study could also be applied to elucidate other functional roles of fatty acid binding to CD36.