Effects of fenofibrate on atherogenic dyslipidemia in hypertriglyceridemic subjects

The effect of lipid-lowering therapy on lipid-related residual risk factors: a prospective study

BACKGROUND

Remnant cholesterol (RC) and nonhigh-density lipoprotein cholesterol (nonHDL-C) are key risk factors for atherosclerotic cardiovascular disease (ASCVD), with apolipoprotein B (apoB) and lipoprotein(a) [Lp(a)] also contributing to its residual risk. However, real-world population-based evidence regarding the impact of current clinical LDL-C-centric lipid-lowering therapy (LLT) on achieving RC and nonHDL-C goals, as well as on modifying residual CVD risk factors is limited.

METHODS

This prospective observational study enrolled 897 CVD patients from September, 2020 to July, 2021. All participants had previously received low-/moderate-intensity LLT and were discharged with either low-/moderate-intensity LLT or high-intensity LLT. After a median follow-up of 3 months, changes in RC, nonHDL-C, and other biomarkers were assessed. Multivariate logistic regression was performed to analyze the impact of the LLT on goal attainment.

RESULTS

Among all patients, 83.50% transitioned to high-intensity LLT from low or moderate. After follow-up, the high-intensity group saw significantly greater reductions in RC (-20.51% vs. -3.90%, P = 0.025), nonHDL-C (-25.12% vs. 0.00%, P < 0.001), apoB (-19.35% vs. -3.17%, P < 0.001), triglycerides (-17.82% vs. -6.62%, P < 0.001), and LDL-C and total cholesterol. Spearman correlation analysis revealed that LDL-C reduction from current LLT was strongly correlated with nonHDL-C reduction (r = 0.87, P < 0.001). Patients who received high-intensity LLT had significant improvements in attainment of RC (from 44.2% to 60.7%, χ² = 39.23, P < 0.001) and nonHDL-C (from 19.4% to 56.9%, χ² = 226.06, P < 0.001) goals. Furthermore, multivariate logistic regression showed that high-intensity LLT was a protective factor for RC [odds ratio (OR) = 0.66; 95% confidence intervals (CI), 0.45-0.97; P = 0.033] and nonHDL-C goal attainment (OR = 0.51; 95% CI, 0.34-0.75; P < 0.001), without a significant increase of adverse reactions.

CONCLUSION

Current levels of clinically prescribed LDL-C-centric treatment can reduce RC and other lipid-related residual risk factors, but high-intensity LLT is better at achieving nonHDL-C and RC goals than low-/moderate-intensity LLT, with a good safety profile. More targeted RC treatments are still needed to reduce residual lipid risk further.

Atherogenic Lipoproteins for the Statin Residual Cardiovascular Disease Risk

Randomized controlled trials (RCTs) show that decreases in low-density lipoprotein cholesterol (LDL-C) by the use of statins cause a significant reduction in the development of cardiovascular disease (CVD). However, one of our previous studies showed that, among eight RCTs that investigated the effect of statins vs. a placebo on CVD development, 56–79% of patients had residual CVD risk after the trials. In three RCTs that investigated the effect of a high dose vs. a usual dose of statins on CVD development, 78–87% of patients in the high-dose statin arms still had residual CVD risk. The risk of CVD development remains even when statins are used to strongly reduce LDL-C, and this type of risk is now regarded as statin residual CVD risk. Our study shows that elevated triglyceride (TG) levels, reduced high-density lipoprotein cholesterol (HDL-C), and the existence of obesity/insulin resistance and diabetes may be important metabolic factors that determine statin residual CVD risk. Here, we discuss atherogenic lipoproteins that were not investigated in such RCTs, such as lipoprotein (a) (Lp(a)), remnant lipoproteins, malondialdehyde-modified LDL (MDA-LDL), and small-dense LDL (Sd-LDL). Lp(a) is under strong genetic control by apolipoprotein (a), which is an LPA gene locus. Variations in the LPA gene account for 91% of the variability in the plasma concentration of Lp(a). A meta-analysis showed that genetic variations at the LPA locus are associated with CVD events during statin therapy, independent of the extent of LDL lowering, providing support for exploring strategies targeting circulating concentrations of Lp(a) to reduce CVD events in patients receiving statins. Remnant lipoproteins and small-dense LDL are highly associated with high TG levels, low HDL-C, and obesity/insulin resistance. MDA-LDL is a representative form of oxidized LDL and plays important roles in the formation and development of the primary lesions of atherosclerosis. MDA-LDL levels were higher in CVD patients and diabetic patients than in the control subjects. Furthermore, we demonstrated the atherogenic properties of such lipoproteins and their association with CVD as well as therapeutic approaches.

Preparation of stabilized submicron fenofibrate crystals on niacin as a hydrophilic hydrotropic carrier

Fenofibrate is antihyperlipidemic which has low and variable oral bioavailability due to erratic dissolution characteristics. Niacin showed a potential atheroprotective effects suggesting possible co-administration with fenofibrate with a potential for development of fixed dose combination. The chemical structure of both drugs highlights the opportunity for interaction upon co-processing due to the existence of complementary hydrogen bonding sites. Accordingly, fenofibrate and niacin were co-processed by wet co-grinding and the resulting product was assessed using scanning electron microscopy, FTIR, thermal analysis and X-ray diffraction in addition to dissolution studies. The instrumental analysis indicated the development of submicron fenofibrate crystals stabilized over the surface of niacin crystals. The developed submicron crystals showed fast dissolution of fenofibrate depending on the relative proportions of fenofibrate to niacin. Co-processing of both drugs at dose ratio which contained higher proportion of niacin resulted in further enhancement in the dissolution rate. This further enhancement was attributed to the hydrotropic effect of niacin which was proved by solubility study in addition to size reduction. This supposition was confirmed from the inferior dissolution of fenofibrate from the physical mixture. The study introduces fenofibrate/niacin as potential fixed dose combination for augmented dissolution rate and pharmacological effects.

Effect of fenofibrate on plasma apolipoprotein C-III levels: a systematic review and meta-analysis of randomised placebo-controlled trials

OBJECTIVES

This meta-analysis of randomised placebo-controlled clinical trials aimed to assess the effect of fenofibrate on apolipoprotein C-III (apo C-III), a key regulator of triglyceride metabolism.

MATERIALS AND METHODS

Randomised placebo-controlled trials investigating the impact of fenofibrate treatment on apo C-III levels were searched in PubMed-Medline, Scopus, Web of Science and Google Scholar databases from inception to 18 August 2017. Quantitative data synthesis was determined by a random-effects model and generic inverse variance method. Sensitivity analysis was conducted using the leave-one-out method. A weighted random-effects meta-regression was performed to evaluate glycaemic parameter confounders.

RESULTS

Meta-analysis of 10 clinical trials involving 477 subjects showed fenofibrate therapy decreased apo C-III levels (weighted mean difference (WMD) -4.78 mg/dL, 95% CI -6.95 to -2.61, p<0.001; I²66.87%). Subgroup analysis showed that fenofibrate reduced plasma apo C-III concentrations in subgroups of trials with treatment durations of either <12 weeks (WMD -4.50 mg/dL, p=0.001) or ≥12 weeks (WMD: -4.73 mg/dL, p=0.009) and doses of fenofibrate <200 mg/day (WMD -6.33 mg/dL, p<0.001) and >200 mg/day (p=0.006), with no significant difference between the subgroups.

CONCLUSION

This meta-analysis found that fenofibrate therapy significantly decreases apo C-III levels, an effect evident with both short-term treatment and doses less than 200 mg/day.

Life-style-induced metabolic derangement and epigenetic changes promote diabetes and oxidative stress leading to NASH and atherosclerosis severity

Energy imbalance resulting from high calorie food intake and insufficient metabolic activity leads to increased body mass index (BMI) and sets the stage for metabolic derangement influencing lipid and carbohydrate metabolism and ultimately leading to insulin resistance, dyslipidemia, and type 2 diabetes. 70% of cardiovascular disease (CVD) deaths occur in patients with diabetes. Environment-induced physiological perturbations trigger epigenetic changes through chromatin modification and leads to type 2 diabetes and progression of nonalcoholic fatty liver disease (NAFLD) and CVD. Thus, in terms of disease progression and pathogenesis, energy homeostasis, metabolic dysregulation, diabetes, fatty liver, and CVD are interlinked. Since advanced glycation end products (AGEs) and low-grade inflammation in type 2 diabetes play definitive roles in the pathogenesis of liver and vascular diseases, a natural checkpoint to prevent diabetes and associated complications appears to be the identification and management of prediabetes together with weight management, since 70% of prediabetic individuals develop diabetes during their life time, and every kg of weight increase is associated with up to 9% increase in diabetes risk. A good proportion of diabetes and obesity population have fatty liver that progresses to non-alcoholic steatohepatitis (NASH) and cirrhosis, and increased risk of hepatocellular carcinoma. Diabetes and NASH both have elevated oxidative stress, impaired cholesterol elimination, and increased inflammation that leads to CVD risk. This review addresses life-style-induced metabolic pathway derangement and how it contributes to epigenetic changes, type 2 diabetes and NASH progression, which collectively lead to increased risk of CVD.

Pharmacologic Treatment of Dyslipidemia in Diabetes: A Case for Therapies in Addition to Statins

PURPOSE OF REVIEW

The purpose of the study is to review the use of statins and the role of both non-statin lipid-lowering agents and diabetes-specific medications in the treatment of diabetic dyslipidemia.

RECENT FINDINGS

Statins have a primary role in the treatment of dyslipidemia in people with type 2 diabetes, defined as triglyceride levels >200 mg/dl and HDL cholesterol levels <40 mg/dL. A number of clinical trials suggest that treatment with a fibrate may reduce cardiovascular events. However, the results of these trials are inconsistent, probably because many of their participants did not have dyslipidemia. The choice of medications used to treat diabetes can have major implications regarding management of dyslipidemia; metformin, GLP-1 agonists, and pioglitazone all have favorable lipid effects. These agents, as well as the new SGLT2 inhibitors, may reduce cardiovascular events. Management of dyslipidemia in people with type 2 diabetes should start with statin therapy and optimal glycemic control with agents that have favorable lipid and cardiovascular effects. We believe that there is a role for adding fenofibrate to moderate-intensity statins in selected patients with true dyslipidemia. We propose an algorithm for selecting add-on medications for diabetes (after metformin) based on lipid status.

The future of n-3 polyunsaturated fatty acid therapy

PURPOSE OF REVIEW

This article focuses on the potential role by which a complex mixture of omega-3 fatty acids (OM3-FAs) may beneficially modify cardiovascular risk by modifying the cholesterol composition of atherogenic lipoproteins. This hypothesis is being tested in the STRENGTH trial, which is enrolling 13 000 patients on statins at high cardiovascular risk with hypertriglyceridemia and low HDL cholesterol (HDL-C) treated with an OM3-carboxylic acid.

RECENT FINDINGS

Complex mixtures of OM3-FAs containing predominately eicosapentanoic acid and docosahexanoic acid in combination with statins lowers non-HDL by reducing triglyceride-rich lipoprotein cholesterol (TRL-C) while shifting small LDL cholesterol (LDL-C) to large LDL-C. Recent genomic and epidemiological studies have implicated TRL-C and small LDL-C as causal for cardiovascular disease. Therefore OM3-FAs containing both eicosapentanoic acid and docosahexanoic acid in combination with statins may beneficially modify the high residual risk for patients with hypertriglyceridemia and low HDL-C.

SUMMARY

Although outcome trials are underway, subgroup analyses of data from previous randomized controlled trials are suggestive of a reduction in coronary artery disease and atherosclerotic cardiovascular disease event rates with triglyceride and TRL-C lowering therapies, particularly if accompanied by low HDL-C. Although the limitations of such data are acknowledged, clinicians must make treatment decisions while awaiting more definitive results from well-designed large-scale randomized controlled trials.

Triglyceride-rich lipoproteins as a causal factor for cardiovascular disease

Approximately 25% of US adults are estimated to have hypertriglyceridemia (triglyceride [TG] level ≥150 mg/dL [≥1.7 mmol/L]). Elevated TG levels are associated with increased cardiovascular disease (CVD) risk, and severe hypertriglyceridemia (TG levels ≥500 mg/dL [≥5.6 mmol/L]) is a well-established risk factor for acute pancreatitis. Plasma TG levels correspond to the sum of the TG content in TG-rich lipoproteins (TRLs; ie, very low-density lipoproteins plus chylomicrons) and their remnants. There remains some uncertainty regarding the direct causal role of TRLs in the progression of atherosclerosis and CVD, with cardiovascular outcome studies of TG-lowering agents, to date, having produced inconsistent results. Although low-density lipoprotein cholesterol (LDL-C) remains the primary treatment target to reduce CVD risk, a number of large-scale epidemiological studies have shown that elevated TG levels are independently associated with increased incidence of cardiovascular events, even in patients treated effectively with statins. Genetic studies have further clarified the causal association between TRLs and CVD. Variants in several key genes involved in TRL metabolism are strongly associated with CVD risk, with the strength of a variant's effect on TG levels correlating with the magnitude of the variant's effect on CVD. TRLs are thought to contribute to the progression of atherosclerosis and CVD via a number of direct and indirect mechanisms. They directly contribute to intimal cholesterol deposition and are also involved in the activation and enhancement of several proinflammatory, proapoptotic, and procoagulant pathways. Evidence suggests that non-high-density lipoprotein cholesterol, the sum of the total cholesterol carried by atherogenic lipoproteins (including LDL, TRL, and TRL remnants), provides a better indication of CVD risk than LDL-C, particularly in patients with hypertriglyceridemia. This article aims to provide an overview of the available epidemiological, clinical, and genetic evidence relating to the atherogenicity of TRLs and their role in the progression of CVD.

Effects of omega-3 carboxylic acids on lipoprotein particles and other cardiovascular risk markers in high-risk statin-treated patients with residual hypertriglyceridemia: a randomized, controlled, double-blind trial

Background

This study examined the effects of a mixture of highly bioavailable omega-3 carboxylic acids (OM3-CA) on nuclear magnetic resonance spectroscopy–assessed lipoprotein particle concentrations and sizes and other cardiovascular risk markers in statin-treated patients with fasting triglycerides (TG) ≥2.3 mmol/L (200 mg/dL) and <5.6 mmol/L (500 mg/dL) and at high cardiovascular risk.

Methods

After a diet lead-in and statin-stabilization period, 647 patients were randomly assigned to receive capsules of control (olive oil, OO) 4 g/d, OM3-CA 2 g/d (plus OO 2 g/d), or OM3-CA 4 g/d for 6 weeks.

Results

Compared with OO, low-density lipoprotein (LDL) particle size was increased with OM3-CA 2 g/d (p < 0.01) and 4 g/d (p < 0.001), and very low-density lipoprotein (VLDL) and high-density lipoprotein (HDL) particle sizes were decreased with both OM3-CA dosages vs. OO (p < 0.001 and p < 0.05 for VLDL and HDL, respectively). Total VLDL/chylomicron remnant particle concentration was reduced by 8.5 and 16.0 % with OM3-CA 2 and 4 g/d, respectively, vs. a 6.9 % reduction with OO (p < 0.001 for OM3-CA 4 g/d vs. OO). Total HDL particle concentration was also reduced by 1.5 and 3.2 % with OM3-CA 2 and 4 g/d, respectively, vs. a 0.6 % increase with OO (at least p < 0.05 for both comparisons). Changes in total LDL particle concentration were not significantly different for OO vs. OM3-CA at either dosage. Apolipoprotein (Apo) CIII levels decreased by 7.6 and 13.1 % with OM3-CA 2 and 4 g/d, respectively, vs. 3.2 % with OO (p < 0.001 for OM3-CA 4 g/d vs. OO). Lipoprotein-associated phospholipase A₂ (Lp-PLA₂) mass was reduced by 6.2 and 10.7 % with OM3-CA 2 and 4 g/d, respectively, vs. a 0.1 % increase with OO (p < 0.001 for both vs. OO). There were no significant differences between treatments in high-sensitivity C-reactive protein responses.

Conclusion

OM3-CA were associated with shifts in lipoprotein particle sizes and concentrations, and reductions in Apo CIII and Lp-PLA₂, in patients with hypertriglyceridemia while taking a statin.

Trial registration

ClinicalTrials.gov Identifier NCT01408303.

A double-blind, double-dummy, randomized, placebo-controlled trial to evaluate the effect of statin therapy on triglyceride levels in Mexican hypertriglyceridemic patients

OBJECTIVE

The most prevalent dyslipidemias in Mexico are low high-density lipoprotein (HDL) and high triglyceride (TG) levels. Hypertriglyceridemia (HTG) has been considered an independent risk factor for cardiovascular disease (CVD). The aim of this study was to evaluate the efficacy of rosuvastatin (RSV) in reducing TG levels in Mexican patients.

METHODS

A randomized, double-blind, double-dummy, parallel-group, placebo-controlled, multicenter, phase IV study was conducted. Patients were of both genders, ≥ 18 years old, with basal TG levels between 200 and 800 mg/dl, LDL levels ≤ 190 mg/dl. Patients were randomized to receive rosuvastatin 10 mg (Group 1), 20 mg (Group 2) or placebo (Group 3) once daily for 8 weeks. Primary efficacy was TG level; secondary efficacy was non-HDL; HDL, low-density lipoprotein (LDL), total cholesterol (TC), Apo (apolipoprotein) A1, and ApoB. Safety data were evaluated up to 30 days after the last dose of medication. The Mann-Whitney U-test was performed to contrast each RSV groups against placebo; p < 0.05 was considered significant. Trial registry number is NCT00473655.

RESULTS

A total of 334 patients were randomized: Group 1 = 111, Group 2 = 112, and Group 3 = 111. Basal TG median value levels were 278 mg/dl, 266 mg/dl, 279 mg/dl with median reduction (MdR) at 8 weeks of 26.6%, 32.19% and 7.58%, respectively, (Group 1 vs. Group 3 p = 0.002, and Group 2 vs. Group 3 p < 0.0001). Basal non-HDL values were 179 mg/dl, 180 mg/dl and 179 mg/dl with a MdR of 27%, 32% and 8%, respectively (Group 1 vs. Group 3 p < 0.0001, and Group 2 vs. Group 3 p < 0.0001); basal LDL vales were 130 mg/dl, 130 mg/dl and 127 mg/dl with MdR 35%, 44% and -4% (Group 1 vs. Group 3 p < 0.0001, Group 2 vs. Group 3 p < 0.0001); basal ApoB values were 114 mg/dl, 115 mg/dl and 110.5 mg/dl with MdR 25%, 33% and -0.5% (Group 1 vs. Group 3 p < 0.0001, Group 2 vs. Group 3 p < 0.001).

CONCLUSION

Rosuvastatin 10 and 20 mg/day significantly reduced triglycerides and improved atherogenic lipid profile in HTG Mexican patients. The main limitation was the short follow-up time period.

Relative Efficacy of Antilipemic Agents in Non–High-Density Lipoprotein Cholesterol Reduction

The investigators sought to summarize the percentage reduction in non–high-density lipoprotein cholesterol (non-HDL-C) achieved with various antilipemic regimens and to determine whether certain antilipemic regimens have been proven more effective in lowering non-HDL-C. A search of MEDLINE, International Pharmaceutical Abstracts, and Iowa Drug Information Service Database from 1970 to May 2011 was performed. Criteria were used to exclude studies not published in English, studies with methodology limitations, and studies with variables that may affect efficacy beyond the antilipemic agent administered. Only randomized, controlled trials comparing medications approved by the Food and Drug Administration were reviewed to determine whether significant differences in percentage reduction in non-HDL-C had been observed between different medication regimens. A total of 51 trials reported data that could be used to determine the range of percentage reduction in non-HDL-C achieved by select antilipemic regimens. Of these 51 trials, 38 provided head-to-head comparisons of antilipemic regimens. Rosuvastatin and atorvastatin are the most potent 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) in lowering non-HDL-C. Adding ezetimibe, fibric acid derivatives, and omega-3 fatty acids to antilipemic monotherapy may result in further reduction in non-HDL-C. Subjects with certain characteristics (eg, nonwhite) were not prevalent in these studies.

Treatment options for the management of hypertriglyceridemia: strategies based on the best-available evidence

A severe elevation in triglycerides (TG; ≥500 mg/dL) increases the risk for pancreatitis. TG levels ≥200 mg/dL are associated with a greater risk of atherosclerotic coronary heart disease (CHD). However, no outcomes trials exist to assess the efficacy of TG lowering for preventing pancreatitis in patients with severe hypertriglyceridemia. Similarly, no completed prospective outcomes trial exists to support or refute a reduction in CHD risk resulting from lipid-altering therapy in patients specifically selected for the presence of hypertriglyceridemia. This review examines the available evidence for the use of statins, omega-3 fatty acids, fibrates, and niacin in the management of hypertriglyceridemic patients. Results from CHD outcomes trials support statins as the first-line lipid-altering drug therapy to reduce CHD in hypercholesterolemic patients, and subgroup analyses suggest statins are efficacious in hypertriglyceridemic patients with fasting TG levels <500 mg/dL. Omega-3 fatty acids and fibrates are reasonable first drug options for patients with TG ≥500 mg/dL and often are used to lower TG levels with the objective of reducing pancreatitis risk, although a statin or niacin may also be reasonable options. Combination lipid drug therapy may be needed to achieve both low-density lipoprotein cholesterol and non-high-density lipoprotein cholesterol treatment goals for CHD prevention in patients with elevated TG levels, particularly those with TG ≥500 mg/dL. Additional clinical outcomes data are needed to provide a more evidence-based rationale for clinical lipid management of hypertriglyceridemic patients.

Effects of prescription omega-3-acid ethyl esters on fasting lipid profile in subjects with primary hypercholesterolemia

This double-blind, randomized crossover study investigated the effects of 6 weeks of treatment with prescription omega-3-acid ethyl esters (POM3, 4 g/day) versus placebo (soy oil) on low-density lipoprotein cholesterol (LDL-C) and other aspects of the fasting lipid profile in 31 men and women with primary, isolated hypercholesterolemia (LDL-C 130-220 mg/dL and triglycerides less than 150 mg/dL while free of lipid-altering therapies). Mean ± standard error of the mean baseline concentrations of total cholesterol, LDL-C, high-density lipoprotein cholesterol (HDL-C), very-low-density lipoprotein cholesterol, and triglycerides were 229 ± 3, 146 ± 3, 60 ± 2, 23 ± 2, and 113 ± 8 mg/dL, respectively. POM3 produced a modest increase from baseline in LDL-C (3.4%) versus the placebo response (-0.7%, P = 0.010). Significant changes (P < 0.05) for POM3 (placebo-corrected) were observed for very-low-density lipoprotein cholesterol (-18.8%), triglycerides (-18.7%), and HDL-C (3.3%). Nuclear magnetic resonance-determined very-low-density lipoprotein particle concentration and size and HDL particle concentration decreased significantly more with POM3 versus placebo, whereas LDL and HDL particle sizes increased significantly more with POM3 versus placebo. Total cholesterol, non-HDL-C, apolipoproteins A1 and B, and LDL particle concentration responses did not differ between treatments. These results did not confirm the hypothesis that POM3 treatment would lower LDL-C in primary, isolated hypercholesterolemia. Effects on other variables were consistent with prior results in mixed dyslipidemia.

Dyslipidaemia of obesity, metabolic syndrome and type 2 diabetes mellitus: the case for residual risk reduction after statin treatment

Dyslipidaemia is frequently present in obesity, metabolic syndrome (MetS) and type 2 diabetes mellitus (T2DM). The predominant features of dyslipidaemia in these disorders include increased flux of free fatty acids (FFA), raised triglyceride (TG) and low high density lipoprotein cholesterol (HDL-C) levels, a predominance of small, dense (atherogenic) low density lipoprotein cholesterol (LDL) particles and raised apolipoprotein (apo) B values Posprandial hyperlipidaemia may also be present. Insulin resistance (IR) appears to play an important role in the pathogenesis of dyslipidaemia in obesity, MetS and T2DM. The cornerstone of treatment of this IR-related dyslipidaemia is lifestyle changes and in diabetic patients, tight glycaemic control. In addition to these measures, recent clinical trials showed benefit with statin treatment. Nevertheless, a substantial percentage of patients treated with statins still experience vascular events. This residual vascular risk needs to be addressed. This review summarizes the effects of hypolipidaemic drug combinations (including statins with cholesterol ester protein inhibitors, niacin, fibrates or fish oil, as well as fibrate-ezetimibe combination) on the residual vascular risk in patients with obesity, MetS or T2DM.

Comparison of fibrate, ezetimibe, low- and high-dose statin therapy for the dyslipidemia of the metabolic syndrome in a mouse model

BACKGROUND AND AIM

The treatment-of-choice for the optimal management of the dyslipidemia of the metabolic syndrome (MetS) is not clearly defined. We compared the efficacy of 4 drug regimes for the management of this dyslipidemia in a mouse model.

MATERIALS AND METHODS

A total of 60 C57Bl6 mice comprised the study group. The first 10 received standard mouse food for the whole experiment (control group). The remaining 50 mice received atherogenic diet for 14 weeks until the development of the MetS. The mice were then divided into 5 groups: the 1st group continued receiving atherogenic diet, while the other 4 groups received atherogenic diet plus ezetimibe (10 mg/kg per day), fenofibrate (100 mg/kg per day), low-dose atorvastatin (10 mg/kg per day), or high-dose (40 mg/kg per day) atorvastatin, respectively, for another 8 weeks.

RESULTS

High-dose atorvastatin treatment achieved the best lipid profile compared with low-dose atorvastatin, ezetimibe, and fibrate therapy. The lipid profile of mice receiving atherogenic diet plus high-dose atorvastatin treatment was similar with mice on regular chow.

CONCLUSIONS

High-dose atorvastatin treatment resulted in optimization of the lipid profile in the presence of a high-fat atherogenic diet in a mouse model. Our results suggest that high-dose atorvastatin treatment may be the optimal treatment option for the dyslipidemia associated with MetS. Nevertheless, verification of these results in humans is required before any definite conclusions can be drawn.

Are post-treatment low-density lipoprotein subclass pattern analyses potentially misleading?

BACKGROUND

Some patients administered cholesterol-lowering therapies may experience an increase in the proportion of small LDL particles, which may be misinterpreted as a worsening of atherosclerotic coronary heart disease risk. This study assessed the lipid effects of adding ezetimibe to atorvastatin or doubling the atorvastatin dose on low-density lipoprotein cholesterol (LDL-C) levels (and the cholesterol content of LDL subclasses), LDL particle number (approximated by apolipoprotein B), and LDL particle size. This was a multicenter, double-blind, randomized, parallel-group study of hypercholesterolemic, high atherosclerotic coronary heart disease risk patients. After stabilization of atorvastatin 40 mg, 579 patients with LDL-C >70 mg/dL were randomized to 6 weeks of ezetimibe + atorvastatin 40 mg or atorvastatin 80 mg. Efficacy parameters included changes from baseline in LDL-C, apolipoprotein B, non-high-density lipoprotein cholesterol (non-HDL-C), and lipoprotein subclasses (Vertical Auto Profile II) and pattern for the overall population, as well as patient subgroups with baseline triglyceride levels <150 mg/dL or ≥150 mg/dL.

RESULTS

Both treatments significantly reduced LDL-C (and the cholesterol content of most LDL subfractions [LDL1-4]) apolipoprotein B, non-HDL-C levels, but did not reduce the proportion of smaller, more dense LDL particles; in fact, the proportion of Pattern B was numerically increased. Results were generally similar in patients with triglyceride levels <150 or ≥150 mg/dL.

CONCLUSIONS

When assessing the effects of escalating cholesterol-lowering therapy, effects upon Pattern B alone to assess coronary heart disease risk may be misleading when interpreted without considerations of other lipid effects, such as reductions in LDL-C, atherogenic lipoprotein particle concentration, and non-HDL-C levels.

TRIAL REGISTRATION

(Registered at clinicaltrials.gov: Clinical trial # NCT00276484).

Fenofibrate and metabolic syndrome

The fibric acid derivative, fenofibrate (FF) has been used in the US since 1998 to manage patients with dyslipidemia. Typical changes in serum lipids as result a of FF treatment include clinically important mean reductions of serum triglycerides (TG) by a mean change of -93.7 mg/dL (-39.3%), increases of high density lipoprotein cholesterol (HDLC) by +5.5 mg/dL (+12.4%), and reductions in low density lipoprotein cholesterol (LDLC) by -17.9 mg/dL (-12.3%). The greatest reductions in serum TG are usually observed in subjects with elevated baseline TGs including those with the metabolic syndrome (MetS). Although statins remain the mainstay of therapy for most dyslipidemic patients, their combined use with FF would be expected to address residual risk resulting from less than optimal TG and HDLC levels in such patients. Clinical trials examining the cardiovascular benefits of FF alone or combined with statins have produced mixed results. These observations underscore our lack of understanding of which patients may benefit from FF therapy and which do not. Although FF's basic mechanism of action is known to involve PPAR-alpha agonist activity resulting in altered transcription of several genes, the actual genetic bases for variability in lipid response is poorly understood. Studies, such as our GOLDN study and others designed to better understand the genetic determinants of variability in the response to FF treatment and lipid levels. As a result several important genetic determinants of lipid levels have been identified. For example, in the GOLDN study SNPs from different genes were significantly associated with baseline lipid levels before treatment (APOA5- rs662799, rs3135506; APOC3- rs5128, rs2854117, rs4520); APOA4- rs5104; PPARA- rs9626730, rs135543, rs11703495; LPL- rs1801177), after treatment PPARA- rs11708495; LPL- rs1801177, and appeared to modulate overall response to FF treatment (NOS3- rs1799983). In this article, we will review the literature leading up to the contemporary use of FF as an agent to manage patients with dyslipidemia and focus on emerging understanding of the genetic variability in response to FF treatment. On the basis of the available evidence, we conclude that FF is of benefit in the treatment of dyslipidemia, especially among those with MetS. However, more work is needed to specifically identify which individuals derive a benefit from FF administration in terms of clinical outcomes and which do not - particularly in the context of type 2 diabetes.

Effect of fibrates on lipid profiles and cardiovascular outcomes: a systematic review

OBJECTIVE

Fibrates might represent a viable treatment option for patients who do not meet their target low-density lipoprotein levels on statins or who are resistant or intolerant to statins. New data from fibrate trials can be synthesized with the existing literature to better estimate their effects.

METHODS

We systematically searched the literature to identify randomized, double-blind, placebo-controlled trials examining the effect of fibrates on lipid profiles or cardiovascular outcomes. We estimated the effect of fibrates on the incidence of nonfatal myocardial infarction and all-cause mortality using random effects models.

RESULTS

Compared with placebo, fibrates were associated with greater reductions in total cholesterol (range: -101.3 mg/dL to -5.0 mg/dL) and triglycerides (range: -321.3 mg/dL to -20.8 mg/dL), and a greater increase in high-density lipoprotein (range: +1.1 mg/dL to +17.9 mg/dL) in all trials. Fibrates tended to be associated with a greater reduction in low-density lipoprotein (range: -76.3 mg/dL to +38.7 mg/dL) than placebo, although these results were not consistent across all trials. Fibrates were more efficacious than placebo at preventing nonfatal myocardial infarction (odds ratio=0.78; 95% confidence interval, 0.69-0.89), but not all-cause mortality (odds ratio=1.05; 95% confidence interval, 0.95-1.15).

CONCLUSION

In addition to improving lipid profiles, fibrates are associated with an important decrease in nonfatal myocardial infarction, but do not substantially affect all-cause mortality. Potential applications include treatment for patients with statin resistance or isolated hypertriglyceridemia, or as an adjunct to other lipid-lowering therapies.

Fenofibrate: treatment of hyperlipidemia and beyond

Fenofibrate is a PPAR-alpha agonist indicated for the treatment of hypertriglyceridemia and mixed dyslipidemia, and is approved for the treatment of hypercholesterolemia, lipid abnormalities commonly observed in patients at high risk of cardiovascular disease, including Type 2 diabetes and/or metabolic syndromes. Treatment with fenofibrate lowers triglycerides, raises HDL-cholesterol and decreases concentrations of small LDL-cholesterol particles and apolipoprotein B. Fenofibrate is particularly effective for reducing postprandial VLDL and LDL particle concentrations, and the increased oxidative stress and inflammatory response that occurs after a fatty meal. In addition, nonlipid pleiotropic effects mediated by PPAR-alpha are likely to contribute to the reduction in atherosclerosis progression and cardiovascular events, and have beneficial effects on diabetes-related microvascular diseases. While current approaches to treating dyslipidemia to prevent cardiovascular diseases focus on statin therapy, it is increasingly clear that substantial residual risk persists. The clinical significance of combination therapy with fenofibrate and a statin to macrovascular and microvascular risk is being evaluated in a large outcomes study.

The Residual Risk Reduction Initiative: a call to action to reduce residual vascular risk in dyslipidaemic patient

Despite current standards of care aimed at achieving targets for low-density lipoprotein (LDL) cholesterol, blood pressure and glycaemia, dyslipidaemic patients remain at high residual risk of vascular events. Atherogenic dyslipidaemia, specifically elevated triglycerides and low levels of high-density lipoprotein (HDL) cholesterol, often with elevated apolipoprotein B and non-HDL cholesterol, is common in patients with established cardiovascular disease, type 2 diabetes, obesity or metabolic syndrome and is associated with macrovascular and microvascular residual risk. The Residual Risk Reduction Initiative (R3I) was established to address this important issue. This position paper aims to highlight evidence that atherogenic dyslipidaemia contributes to residual macrovascular risk and microvascular complications despite current standards of care for dyslipidaemia and diabetes, and to recommend therapeutic intervention for reducing this, supported by evidence and expert consensus. Lifestyle modification is an important first step. Additionally, pharmacotherapy is often required. Adding niacin, a fibrate or omega-3 fatty acids to statin therapy improves achievement of all lipid risk factors. Outcomes studies are evaluating whether these strategies translate to greater clinical benefit than statin therapy alone. In conclusion, the R3I highlights the need to address with lifestyle and/or pharmacotherapy the high level of residual vascular risk among dyslipidaemic patients who are treated in accordance with current standards of care.

Activation of peroxisome proliferator-activated receptor-alpha in mice induces expression of the hepatic low-density lipoprotein receptor

Background and purpose:

Mutations in the low-density lipoprotein receptor (LDLR) gene cause familial hypercholesterolaemia in humans and deletion of the LDLR induces lesion development in mice fed a high-fat diet. LDLR expression is predominantly regulated by sterol regulatory element-binding protein 2 (SREBP2). Fenofibrate, a peroxisome proliferator-activated receptor α (PPARα) ligand, belongs to a drug class used to treat dyslipidaemic patients. We have investigated the effects of fenofibrate on hepatic LDLR expression.

Experimental approach:

The effects of fenofibrate on hepatic LDLR expression (mRNA and protein) and function were evaluated by both in vitro (with AML12 cells) and in vivo experiments in mice.

Key results:

Fenofibrate increased LDLR expression and LDL binding in a mouse hepatoma cell line, AML12 cells. Fenofibrate restored sterol-inhibited hepatocyte LDLR expression. Mechanistic studies demonstrated that induction of LDLR expression by fenofibrate was dependent on PPARα and sterol regulatory elements (SRE). Specifically, fenofibrate induced LDLR expression by increasing maturation of SREBP2 and phosphorylation of protein kinase B (Akt) but had no effect on SREBP cleavage-activating protein. In vivo, a high-fat diet suppressed LDLR expression in mouse liver while elevating total and LDL cholesterol levels in plasma. However, fenofibrate restored LDLR expression inhibited by high-fat diets in the liver and reduced LDL cholesterol levels in plasma.

Conclusions and implications:

Our data suggest that fenofibrate increased hepatic LDLR expression in mice by a mechanism involving Akt phosphorylation and LDLR gene transcription mediated by SREBP2.

PAI-1 activity, but not fibrinogen or von Willebrand factor, is inversely related to LDL particle size in type 2 diabetes

BACKGROUND

Levels of fibrinogen, von Willebrand factor (vWF) and plasminogen activator inhibitor-1 (PAI-1) have been associated with small low-density lipoprotein (LDL) particles. However, it is not clear whether these associations are independent of visceral adiposity or other components of the metabolic syndrome such as triglycerides or insulin resistance.

METHODS

Visceral adipose tissue (VAT; CT-scan), fibrinogen, von Willebrand factor antigen (vWF:Ag), PAI-1 activity and different metabolic parameters such as total cholesterol (chol), HDL-chol, triglycerides, insulin resistance (homeostasis model assessment; HOMA-IR) were determined in 41 women and 78 men with type 2 diabetes. LDL particle size was assessed by polyacrylamide gradient gel electrophoresis.

RESULTS

PAI-1 activity was inversely related to LDL particle size after adjustment for age and body mass index (BMI) (r=-0.28; p=0.006) or age and VAT (r=-0.26; p=0.01), but not after adjustment for age and HOMA-IR (r=-0.15; p=0.148) or age and triglycerides (r=-0.04; p=0.679). In multiple regression analysis, LDL particle size did not independently determine PAI-1 activity levels. Fibrinogen and vWF:Ag did not seem to be related to LDL size.

CONCLUSIONS

PAI-1 activity levels, in contrast to fibrinogen and vWF:Ag, seem to be related to the small LDL phenotype in patients with type 2 diabetes. However, this relationship was not independent of insulin resistance or triglycerides.

The clinical significance of the size of low-density-lipoproteins and the modulation of subclasses by fibrates

BACKGROUND

Beyond total low-density-lipoproteins (LDL) levels, increasing evidence suggests that the 'quality' of LDL exerts a great influence on the cardiovascular risk. Several studies have also shown that the therapeutic modulation of LDL size is of benefit in reducing the risk of cardiovascular events. Hypolipidaemic treatment is able to alter LDL subclass distribution but strong variations have been noticed among different agents. Fibrates have a major impact on triglyceride metabolism and in modulating LDL size and subclasses, but variations exist among the different molecules.

METHODOLOGY

A literature search (by Medline and Scopus) was performed using the following headings: 'small dense LDL', 'LDL size', 'LDL subfractions', 'LDL subclasses', 'LDL distribution' and 'fenofibrate', 'bezafibrate', 'ciprofibrate' and 'gemfibrozil' up to 20 January 2007. The authors also manually reviewed the references of selected articles for any pertinent material.

RESULTS

Analysis of all published studies revealed that treatment with fenofibrate, ciprofibrate, bezafibrate and gemfibrozil is usually beneficial, and fenofibrate may be more efficacious than the other molecules. This is supported by using all the available techniques in subjects with a very wide range of lipid alterations.

CONCLUSION

Among the different agents, fenofibrate has been found to be particularly effective in modulating LDL size and subclasses in patients at higher cardiovascular risk, such as those with type 2 diabetes or the metabolic syndrome.

Global risk management in patients with type 2 diabetes mellitus

It is well established that aggressive risk factor modification results in improved cardiovascular disease (CVD) outcomes. Yet, patients with type 2 diabetes mellitus have a much higher baseline risk for cardiovascular events. As type 2 diabetes and hypertension commonly coexist, achieving recommended targets for diabetes, hypertension, and CVD requires aggressive management. Global risk reduction with aggressive low-density lipoprotein reduction and through the additional normalization of glucose levels and blood pressure can help to reduce absolute risk in this very high-risk population.

Clinical importance and therapeutic modulation of small dense low-density lipoprotein particles

The National Cholesterol Education Programme Adult Treatment Panel III accepted the predominance of small dense low-density lipoprotein (sdLDL) as an emerging cardiovascular disease (CVD) risk factor. Most studies suggest that measuring low-density lipoprotein (LDL) particle size, sdLDL cholesterol content and LDL particle number provides additional assessment of CVD risk. Therapeutic modulation of small LDL size, number and distribution may decrease CVD risk; however, no definitive causal relationship is established, probably due to the close association between sdLDL and triglycerides and other risk factors (e.g., high-density lipoprotein, insulin resistance and diabetes). This review addresses the formation and measurement of sdLDL, as well as the relationship between sdLDL particles and CVD. The effect of hypolipidaemic (statins, fibrates and ezetimibe) and hypoglycaemic (glitazones) agents on LDL size and distribution is also discussed.