Novel insights of dietary polyphenols and obesity

The prevalence of obesity has steadily increased over the past three decades both in the United States and worldwide. Recent studies have shown the role of dietary polyphenols in the prevention of obesity and obesity-related chronic diseases. Here, we evaluated the impact of commonly consumed polyphenols, including green tea catechins, especially epigallocatechin gallates, resveratrol and curcumin, on obesity and obesity-related inflammation. Cellular studies demonstrated that these dietary polyphenols reduce viability of adipocytes and proliferation of preadipocytes, suppress adipocyte differentiation and triglyceride accumulation, stimulate lipolysis and fatty acid β-oxidation, and reduce inflammation. Concomitantly, the polyphenols modulate signaling pathways including the adenosine-monophosphate-activated protein kinase, peroxisome proliferator activated receptor γ, CCAAT/enhancer binding protein α, peroxisome proliferator activator receptor gamma activator 1-alpha, sirtuin 1, sterol regulatory element binding protein-1c, uncoupling proteins 1 and 2, and nuclear factor-κB that regulate adipogenesis, antioxidant and anti-inflammatory responses. Animal studies strongly suggest that commonly consumed polyphenols described in this review have a pronounced effect on obesity as shown by lower body weight, fat mass and triglycerides through enhancing energy expenditure and fat utilization, and modulating glucose hemostasis. Limited human studies have been conducted in this area and are inconsistent about the antiobesity impact of dietary polyphenols probably due to the various study designs and lengths, variation among subjects (age, gender, ethnicity), chemical forms of the dietary polyphenols used and confounding factors such as other weight-reducing agents. Future randomized controlled trials are warranted to reconcile the discrepancies between preclinical efficacies and inconclusive clinic outcomes of these polyphenols.

Prevalence and trends of metabolic syndrome in the adult U.S. population, 1999-2010

OBJECTIVES

This study sought to characterize the prevalence of metabolic syndrome (MetS), its 5 components, and their pharmacological treatment in U.S. adults by sex and race/ethnicity over time.

BACKGROUND

MetS is a constellation of clinical risk factors for cardiovascular disease, stroke, kidney disease, and type 2 diabetes mellitus.

METHODS

Prevalence estimates were estimated in adults (≥ 20 years of age) from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2010 (in 2-year survey waves). The biological thresholds, defined by the 2009 Joint Scientific Statement, were: 1) waist circumference ≥ 102 cm (males adults) and ≥ 88 cm (female adults); 2) fasting plasma glucose ≥ 100 mg/dl; 3) blood pressure of ≥ 130/85 mm Hg; 4) triglycerides ≥ 150 mg/dl; and 5) high-density lipoprotein-cholesterol (HDL-C) <40 mg/dl (male adults) and <50 mg/dl (female adults). Prescription drug use was estimated for lipid-modifying agents, anti-hypertensives, and anti-hyperglycemic medications.

RESULTS

From 1999 and 2000 to 2009 and 2010, the age-adjusted prevalence of MetS (based on biologic thresholds) decreased from 25.5% (95% confidence interval [CI]: 22.5% to 28.6%) to 22.9% (95% CI: 20.3% to 25.5%). During this period, hypertriglyceridemia prevalence decreased (33.5% to 24.3%), as did elevated blood pressure (32.3% to 24.0%). The prevalence of hyperglycemia increased (12.9% to 19.9%), as did elevated waist circumference (45.4% to 56.1%). These trends varied considerably by sex and race/ethnicity. Decreases in elevated blood pressure, suboptimal triglycerides, and high-density lipoprotein-cholesterol prevalence have corresponded with increases in anti-hypertensive and lipid-modifying drugs, respectively.

CONCLUSIONS

The increasing prevalence of abdominal obesity, particularly among female adults, highlights the urgency of addressing abdominal obesity as a healthcare priority. The use of therapies for MetS components aligns with favorable trends in their prevalence.

Friedewald-estimated versus directly measured low-density lipoprotein cholesterol and treatment implications

OBJECTIVES

The aim of this study was to compare Friedewald-estimated and directly measured low-density lipoprotein cholesterol (LDL-C) values.

BACKGROUND

LDL-C is routinely estimated by the Friedewald equation to guide treatment; however, compatibility with direct measurement has received relatively little scrutiny, especially at levels <70 mg/dl now targeted in high-risk patients.

METHODS

We examined 1,340,614 U.S. adults who underwent lipid profiling by vertical spin density gradient ultracentrifugation (Atherotech, Birmingham, Alabama) from 2009 to 2011. Following standard practice, Friedewald LDL-C was not estimated if triglyceride levels were ≥ 400 mg/dl (n = 30,174), yielding 1,310,440 total patients and 191,333 patients with Friedewald LDL-C <70 mg/dl.

RESULTS

Patients were 59 ± 15 years of age and 52% were women. Lipid distributions closely matched those in the National Health and Nutrition Examination Survey. A greater difference in the Friedewald-estimated versus directly measured LDL-C occurred at lower LDL-C and higher triglyceride levels. If the Friedewald-estimated LDL-C was <70 mg/dl, the median directly measured LDL-C was 9.0 mg/dl higher (5th to 95th percentiles, 1.8 to 15.4 mg/dl) when triglyceride levels were 150 to 199 mg/dl and 18.4 mg/dl higher (5th to 95th percentiles, 6.6 to 36.0 mg/dl) when triglyceride levels were 200 to 399 mg/dl. Of patients with a Friedewald-estimated LDL-C <70 mg/dl, 23% had a directly measured LDL-C ≥ 70 mg/dl (39% if triglyceride levels were concurrently 150 to 199 mg/dl; 59% if triglyceride levels were concurrently 200 to 399 mg/dl).

CONCLUSIONS

The Friedewald equation tends to underestimate LDL-C most when accuracy is most crucial. Especially if triglyceride levels are ≥ 150 mg/dl, Friedewald estimation commonly classifies LDL-C as <70 mg/dl despite directly measured levels ≥ 70 mg/dl, and therefore additional evaluation is warranted in high-risk patients.

Relationship of apolipoproteins A-1 and B, and lipoprotein(a) to cardiovascular outcomes: the AIM-HIGH trial (Atherothrombosis Intervention in Metabolic Syndrome with Low HDL/High Triglyceride and Impact on Global Health Outcomes)

OBJECTIVES

This study sought to examine the relationship between baseline and on-study apolipoproteins (apo) A-1 and B and lipoprotein(a) [Lp(a)] levels and the development of subsequent cardiovascular (CV) events in the AIM-HIGH (Atherothrombosis Intervention in Metabolic Syndrome with Low HDL/High Triglyceride and Impact on Global Health Outcomes) trial.

BACKGROUND

Niacin has been reported to lower apoB and Lp(a) and to raise apoA-1.

METHODS

Individuals with CV disease and low baseline levels of high-density lipoprotein cholesterol were randomized to simvastatin plus placebo or simvastatin, plus extended-release niacin ([ERN], 1,500 to 2,000 mg/day), with ezetimibe added as needed, in both groups, to maintain an on-treatment low-density lipoprotein cholesterol in the range of 40 to 80 mg/dl. Hazard ratios (HRs) were used to evaluate the relationship between levels of apoA-1, apoB, and Lp(a), and CV events in each treatment group.

RESULTS

Baseline apoB and the apoB/apoA-I ratio were significantly predictive of CV events only for the placebo group (HR: 1.17 [p = 0.018] and HR: 1.19 [p = 0.016]). Baseline and on-study Lp(a) were predictive of CV events in both simvastatin plus placebo (baseline HR: 1.24 [p = 0.002] and on-study HR: 1.21 [p = 0.017]) and the simvastatin plus ERN group (baseline HR: 1.25 [p = 0.001] and on-study HR: 1.18 [p = 0.028]). The ERN modestly increased 1-year apoA-1 (7%), decreased apoB (13%), decreased the ApoB/ApoA-1 ratio (19%), and decreased Lp(a) 21%, but did not reduce CV events.

CONCLUSIONS

Lp(a) was associated with increased CV risk in both treatment groups indicating that it contributes to residual CV risk. However, there was no evidence that ERN reduced CV risk, despite favorable lipoprotein changes.

Prevalence of metabolic syndrome and its influencing factors among the Chinese adults: the China Health and Nutrition Survey in 2009

OBJECTIVE

We aimed to estimate the up-to-date prevalence of metabolic syndrome (MS) and its influencing factors among the Chinese adults.

METHODS

Data were obtained from the China Health and Nutrition Survey conducted in 2009, which was a cross-sectional and partially nationally representative study including a total of 7488 Chinese adults (age ≥18 years).

RESULTS

The overall age-standardized prevalence estimates of the MS were 21.3% (95%confidence interval (CI): 20.4%-22.2%), 18.2% (95%CI: 17.3%-19.1%) and 10.5% (95%CI: 9.8%-11.2%) based on definitions of revised NCEP ATPIII, IDF and CDS criteria, respectively. Individuals who were women (compared to men: odds ratio [OR]=1.37, 95% CI=1.16-1.61), 40 years or older (compared to less than 40 years old: OR=2.82, 95%CI=2.37-3.34 for 40-59 years; OR=4.41, 95%CI=3.68-5.29 for 60 years or older), overweight/obese (compared to normal weight: OR=4.32, 95%CI=3.77-4.95 for overweight; OR=11.24, 95%CI=9.53-13.26 for obese), and living in urban area (compared to living in rural area: OR=1.27, 95%CI=1.12-1.43) were more likely to have a higher prevalence estimate of MS. In addition, frequency of alcohol consumption and cigarette intake were also found to be significantly associated with probability of MS.

CONCLUSIONS

Our results suggest an urgent need to develop national strategies for the prevention, detection, treatment and control of obesity and MS in China.

MicroRNA-33 deficiency reduces the progression of atherosclerotic plaque in ApoE-/- mice

Background

Cholesterol efflux from cells to apolipoprotein A-I (apoA-I) acceptors via the ATP-binding cassette transporters ABCA1 and ABCG1 is thought to be central in the antiatherogenic mechanism. MicroRNA (miR)-33 is known to target ABCA1 and ABCG1 in vivo.

Methods and Results

We assessed the impact of the genetic loss of miR-33 in a mouse model of atherosclerosis. MiR-33 and apoE double-knockout mice (miR-33^−/−Apoe^−/−) showed an increase in circulating HDL-C levels with enhanced cholesterol efflux capacity compared with miR-33^+/+Apoe^−/− mice. Peritoneal macrophages from miR-33^−/−Apoe^−/− mice showed enhanced cholesterol efflux to apoA-I and HDL-C compared with miR-33^+/+Apoe^−/− macrophages. Consistent with these results, miR-33^−/−Apoe^−/− mice showed reductions in plaque size and lipid content. To elucidate the roles of miR-33 in blood cells, bone marrow transplantation was performed in these mice. Mice transplanted with miR-33^−/−Apoe^−/− bone marrow showed a significant reduction in lipid content in atherosclerotic plaque compared with mice transplanted with miR-33^+/+Apoe^−/− bone marrow, without an elevation of HDL-C. Some of the validated targets of miR-33 such as RIP140 (NRIP1) and CROT were upregulated in miR-33^−/−Apoe^−/− mice compared with miR-33^+/+Apoe^−/− mice, whereas CPT1a and AMPKα were not.

Conclusions

These data demonstrate that miR-33 deficiency serves to raise HDL-C, increase cholesterol efflux from macrophages via ABCA1 and ABCG1, and prevent the progression of atherosclerosis. Many genes are altered in miR-33-deficient mice, and detailed experiments are required to establish miR-33 targeting therapy in humans.

Irisin in patients with nonalcoholic fatty liver disease

OBJECTIVE

Irisin is a recently discovered myokine proposed to increase thermogenesis-related energy expenditure and improve metabolism. We aimed to comparatively evaluate serum irisin levels in patients with biopsy-proven nonalcoholic fatty liver disease (NAFLD) vs. controls and study their association with disease severity.

METHODS

Fifteen and 16 consecutively enrolled patients with biopsy-proven nonalcoholic simple steatosis (NAFL) and steatohepatitis (NASH), respectively, and 24 lean and 28 obese controls without NAFLD were recruited. Irisin, established adipokines and biochemical tests were measured.

RESULTS

Serum irisin levels were statistically different in obese controls (33.7±2.7 ng/mL; p<0.001) and patients with NAFL (30.5±1.5 ng/mL; p<0.001) and NASH (35.8±1.9 ng/mL; p=0.001) compared with lean controls (47.7±2.0 ng/mL), but were similar among patients with NAFL, NASH and obese controls. This difference remained significant after adjustment for body mass index (or waist circumference), gender, age, insulin resistance (assessed by HOMA-IR or QUICKI), exercise and time since blood collection. Serum leptin and adiponectin, but not irisin, levels were independently from BMI correlated with insulin resistance and cardiometabolic factors. Serum irisin tended to be higher in patients with (36.7±2.4 ng/mL) than without (30.8±1.2 ng/mL; p=0.02) portal inflammation and independently associated with the latter; these data need to be confirmed by future studies.

CONCLUSIONS

Serum irisin levels differ between lean controls and obese controls or NAFLD patients. Despite similar circulating irisin levels between NAFL and NASH groups, irisin may be independently and positively associated with the presence of portal inflammation. Future clinical and mechanistic studies are needed to confirm and extend these data.

Efficacy and safety of a novel dual modulator of adenosine triphosphate-citrate lyase and adenosine monophosphate-activated protein kinase in patients with hypercholesterolemia: results of a multicenter, randomized, double-blind, placebo-controlled, parallel-group trial

OBJECTIVES

The aim of this study was to assess the lipid-altering efficacy and safety of ETC-1002 in subjects with hypercholesterolemia.

BACKGROUND

ETC-1002 is a small molecule that modulates pathways of cholesterol, fatty acid, and carbohydrate metabolism and may have therapeutic benefits in treating hypercholesterolemia and other cardiometabolic risk factors.

METHODS

This multicenter, randomized, double-blind, placebo-controlled, parallel-group trial evaluated patients (n = 177) with elevated low-density lipoprotein cholesterol (LDL-C) (130 to 220 mg/dl), who were stratified by baseline triglycerides (not elevated [<150 mg/dl] or elevated [150-<400 mg/dl]) and randomized to receive 40, 80, or 120 mg of ETC-1002 or placebo once daily for 12 weeks. Outcomes included changes in LDL-C (primary endpoint), other lipids, and cardiometabolic risk factors; and safety.

RESULTS

ETC-1002 40, 80, and 120 mg lowered least-squares mean ± SE LDL-C levels by 17.9 ± 2.2%, 25.0 ± 2.1%, and 26.6 ± 2.2%, respectively, versus a reduction of 2.1 ± 2.2% with placebo (all, p < 0.0001); LDL-C lowering was similar between the subgroups with nonelevated and elevated triglycerides. ETC-1002 also lowered non-high-density lipoprotein cholesterol (non-HDL-C), apolipoprotein B, and LDL particle number (all, p < 0.0001) in a dose-dependent manner; HDL-C and triglyceride levels were relatively unchanged. Post-hoc analyses suggest that ETC-1002 may have favorable effects on other cardiometabolic risk factors. The ETC-1002 and placebo groups did not demonstrate clinically meaningful differences in adverse events or other safety assessments.

CONCLUSIONS

ETC-1002 significantly lowered LDL-C levels up to 27% across a broad range of baseline triglycerides and was generally safe and well tolerated. ETC-1002 has a novel mechanism of action and may be useful for reducing LDL-C. (A Study to Assess the Efficacy and Safety of ETC-1002 in Subjects With Elevated Blood Cholesterol and Either Normal or Elevated Triglycerides; NCT01262638).

Statin non-adherence and residual cardiovascular risk: There is need for substantial improvement

Although statin therapy has proven to be the cornerstone for prevention and treatment of cardiovascular disease (CVD), there are many patients for whom long-term therapy remains suboptimal. The aims of this article are to review the current complex issues associated with statin use and to explore when novel treatment approaches should be considered. Statin discontinuation as well as adherence to statin therapy remain two of the greatest challenges for lipidologists. Evidence suggests that between 40 and 75% of patients discontinue their statin therapy within one year after initiation. Furthermore, whilst the reasons for persistence with statin therapy are complex, evidence shows that low-adherence to statins negatively impacts clinical outcomes and residual CV risk remains a major concern. Non-adherence or lack of persistence with long-term statin therapy in real-life may be the main cause of inadequate low density lipoprotein cholesterol lowering with statins. There is a large need for the improvement of the use of statins, which have good safety profiles and are inexpensive. On the other hand, in a non-cost-constrained environment, proprotein convertase subtilisin/kexin type 9 inhibitors should arguably be used more often in those patients in whom treatment with statins remains unsatisfactory.

Relationship of lipoproteins to cardiovascular events: the AIM-HIGH Trial (Atherothrombosis Intervention in Metabolic Syndrome With Low HDL/High Triglycerides and Impact on Global Health Outcomes)

OBJECTIVES

This study sought to examine the relationship between niacin treatment, lipoproteins, and cardiovascular (CV) outcomes in this secondary analysis of the AIM-HIGH (Atherothrombosis Intervention in Metabolic Syndrome With Low HDL/High Triglycerides and Impact on Global Health Outcomes) trial.

BACKGROUND

During a 3-year follow-up in 3,414 patients with established CV disease and low high-density lipoprotein cholesterol (HDL-C) levels, combined niacin + low-density lipoprotein cholesterol (LDL-C)-lowering therapy did not reduce CV events compared with LDL-C-lowering therapy alone.

METHODS

Subjects taking simvastatin and/or ezetimibe were randomized to receive extended-release (ER) niacin 1,500 to 2,000 mg or minimal immediate-release niacin (≤ 150 mg) as placebo at bedtime. LDL-C levels in both groups were maintained from 40 to 80 mg/dl. Hazard ratios were estimated by using Cox proportional hazards models for relationships between lipoproteins and the composite endpoint of CV death, myocardial infarction, acute coronary syndrome, ischemic stroke, or symptom-driven revascularization.

RESULTS

CV outcomes were not associated with ER niacin in any baseline lipoprotein tertile. In a subset of patients in both the highest triglyceride (≥ 198 mg/dl) and lowest HDL-C (<33 mg/dl) tertiles, ER niacin showed a trend toward benefit (hazard ratio: 0.74, p = 0.073). In-trial LDL-C levels, non-HDL-C levels, and the total cholesterol/HDL-C ratio were positively associated with CV events in the control group, but these relationships were absent in the ER niacin group.

CONCLUSIONS

Baseline lipoprotein tertiles did not predict differential benefit or harm with ER niacin added to LDL-C-lowering therapy, but a small dyslipidemic subgroup may benefit. ER niacin attenuated expected relationships of lipoprotein risk factors with CV events, raising the possibility that nonlipoprotein actions of niacin could affect risk. (Niacin Plus Statin to Prevent Vascular Events [AIM-HIGH]; NCT00120289).

Dietary share of ultra-processed foods and metabolic syndrome in the US adult population

This study sought to examine the relationship between dietary share of ultra-processed foods and metabolic syndrome among US adults. We studied 6, 385 participants from the cross-sectional National Health and Nutrition Examination Survey 2009-2014, aged 20+ years, with blood tests under fasting conditions and at least one 24-hour dietary recall. Food items were classified according to the extent and purpose of industrial food processing. Ultra-processed foods (UPF) are formulations of many ingredients, mostly of exclusive industrial use, that result from a sequence of industrial processes (hence ultra-processed). Metabolic Syndrome (MetS) was defined according to the 2009 Joint Scientific Statement as meeting three or more of the following criteria: (1) elevated waist circumference (2) elevated fasting plasma glucose (3) elevated blood pressure (4) elevated triglycerides (5) reduced high-density lipoprotein (HDL-C). Poisson regression models with robust variance adjusted for age, sex, race/ethnicity, family income, education, physical activity and smoking showed significant linear association between the dietary contribution of UPF and the prevalence of MetS (a 10% increase in contribution was associated with a 4% prevalence increase) (prevalence ratio -PR- = 1.04; 95% CI 1.02, 1.07). A dietary UPF contribution of >71% (5th population quintile) was associated with 28% higher prevalence of MetS compared to a contribution below 40% (1st population quintile) (PR = 1.28; 95% CI 1.09, 1.50). The association was stronger in young adults (PR between upper and lower quintiles = 1.94; 95% CI 1.39, 2.72) and decreased with age. These findings add to the growing evidence that UPF consumption is associated with diet-related non-communicable diseases.

The impact of obesity on risk factors and prevalence and prognosis of coronary heart disease-the obesity paradox

Obesity is associated with a host of cardiovascular risk factors and its prevalence is rising rapidly. Despite strong evidence that obesity predisposes to the development and progression of coronary heart disease (CHD), numerous studies have shown an inverse relationship between various measures of obesity (most commonly body mass index) and outcomes in established CHD. In this article we review the evidence surrounding the ≪obesity paradox≫ in the secondary care of CHD patients and the CHD presentations where a paradox has been found. Finally we discuss the impact of cardiorespiratory fitness and a number of mechanisms which may offer potential explanations for this puzzling phenomenon.

Plasma fatty acid composition, estimated desaturase activities, and their relation with the metabolic syndrome in a population at high risk of cardiovascular disease

BACKGROUND & AIMS

The metabolic syndrome (MetS) is a clustering of various metabolic abnormalities which is associated with increased risk of cardiovascular disease (CVD) and type 2 diabetes mellitus. Due to its increasing prevalence, it has become an important public health concern. Altered fatty acid (FA) composition and desaturase activities have been associated with several metabolic diseases, including MetS. The aim of the present study was to evaluate the relationship of the plasma FA profile and desaturase activities with the MetS in a Mediterranean population at high risk of CVD.

METHODS

Baseline data from 427 participants aged 55-80 years who took part in the interventional PREDIMED study were obtained. Individual FA was determined in plasma and desaturase activities were estimated from product/precursor ratios. Odds ratios (OR) and partial correlation coefficients were used to examine these relations with MetS and its components, respectively.

RESULTS

We found higher levels of C14:0, C16:0, C16:1n-7, estimated Δ(9)- or stearoyl-CoA desaturase (SCD), and estimated Δ(6) desaturase (D6D), and lower levels of C18:2n-6 in people with MetS compared to those without it. After adjustment for several confounders, only higher quartiles of C14:0, C16:0, C16:1n-7, and D6D were found to be associated with an increasing prevalence of MetS, while higher quartiles of C18:2n-6 were inversely associated with MetS. High proportions of C14:0, C16:0, C16:1n-7, C20:3n-6, SCD, and D6D, and decreased proportions of C18:2n-6 and estimated Δ(5)-desaturase (D5D) were associated with adverse profiles of several metabolic risk factors. Women showed more unhealthy FA pattern and lipid profiles than men, but only among those with MetS.

CONCLUSION

A FA composition and estimated desaturase activities consisting in high levels of SFA, SCD and D6D, and low levels of PUFA and D5D are associated with increased MetS probability and are characteristic of people presenting MetS, especially women. These findings support those observed in non-Mediterranean populations in which an altered FA profile and estimated desaturase activities are associated with MetS.

Sleep duration and quality in relation to non-alcoholic fatty liver disease in middle-aged workers and their spouses

BACKGROUND & AIMS

Although accumulated evidence implies that short sleep duration and poor sleep quality may lead to an altered metabolic milieu, potentially triggering the development of non-alcoholic fatty liver disease (NAFLD), no studies have explored this association. This study sought to examine whether short sleep duration or poor sleep quality is associated with NAFLD in the general population.

METHODS

We assessed sleep duration and quality using the Pittsburgh Sleep Quality Index in 69,463 middle-aged workers and their spouses and carried out biochemical and anthropometric measurements. The presence of fatty liver was determined using ultrasonographic findings. Logistic regression models were used to evaluate the association of sleep duration and quality with NAFLD, after adjusting for potential confounders.

RESULTS

After controlling for the relevant confounding factors (age, alcohol intake, smoking, physical activity, systolic blood pressure, education level, marital status, presence of job, sleep apnea, and loud snoring), the adjusted odds ratio (95% confidence interval) for NAFLD comparing sleep duration ≤5 h to the reference (>7h) was 1.28 (1.13-1.44) in men and 1.71 (1.38-2.13) in women. After further adjustments for BMI, this association was not significant in men (OR: 1.03, 95% CI: 0.90-1.19) but remained significant in women (OR: 1.59, 95% CI: 1.23-2.05). The multivariate-adjusted odds ratio comparing participants with poor sleep quality vs. participants with good sleep quality was 1.10 (95% CI 1.02-1.19) and 1.36 (95% CI 1.17-1.59) in men and women, respectively.

CONCLUSIONS

In the middle-aged, general population, short sleep duration, and poor sleep quality were significantly associated with an increased risk of NAFLD. Prospective studies are required to confirm this association.

Genetic Dissection of the Impact of miR-33a and miR-33b during the Progression of Atherosclerosis

As an important regulator of macrophage cholesterol efflux and HDL biogenesis, miR-33 is a promising target for treatment of atherosclerosis, and numerous studies demonstrate that inhibition of miR-33 increases HDL levels and reduces plaque burden. However, important questions remain about how miR-33 impacts atherogenesis, including whether this protection is primarily due to direct effects on plaque macrophages or regulation of lipid metabolism in the liver. We demonstrate that miR-33 deficiency in Ldlr^-/- mice promotes obesity, insulin resistance, and hyperlipidemia but does not impact plaque development. We further assess how loss of miR-33 or addition of miR-33b in macrophages and other hematopoietic cells impact atherogenesis. Macrophage-specific loss of miR-33 decreases lipid accumulation and inflammation under hyperlipidemic conditions, leading to reduced plaque burden. Therefore, the pro-atherogenic effects observed in miR-33-deficient mice are likely counterbalanced by protective effects in macrophages, which may be the primary mechanism through which anti-miR-33 therapies reduce atherosclerosis.

Obesity-Related Changes in High-Density Lipoprotein Metabolism and Function

In obese individuals, atherogenic dyslipidemia is a very common and important factor in the increased risk of cardiovascular disease. Adiposity-associated dyslipidemia is characterized by low high-density lipoprotein cholesterol (HDL-C) levels and an increase in triglyceride-rich lipoproteins. Several factors and mechanisms are involved in lowering HDL-C levels in the obese state and HDL quantity and quality is closely related to adiponectin levels and the bioactive lipid sphingosine-1-phosphate. Recent studies have shown that obesity profoundly alters HDL metabolism, resulting in altered HDL subclass distribution, composition, and function. Importantly, weight loss through gastric bypass surgery and Mediterranean diet, especially when enriched with virgin olive oil, is associated with increased HDL-C levels and significantly improved metrics of HDL function. A thorough understanding of the underlying mechanisms is crucial for a better understanding of the impact of obesity on lipoprotein metabolism and for the development of appropriate therapeutic approaches. The objective of this review article was to summarize the newly identified changes in the metabolism, composition, and function of HDL in obesity and to discuss possible pathophysiological consequences.

Inhibition of pancreatic lipase, α-glucosidase, α-amylase, and hypolipidemic effects of the total flavonoids from Nelumbo nucifera leaves

ETHNOPHARMACOLOGICAL RELEVANCE

Nelumbo nucifera Gaertn. leaves have been used as medicinal herbs in the past 1300 years, specifically utilized to cure hyperlipidemia, hyperglycemia, and obesity. It has been recorded in the most famous medicinal book in China for more than 400 years. The present study aims to identify the potential therapeutic activities of the flavonoids isolated from Nelumbo nucifera leaves.

MATERIALS AND METHODS

Nelumbo nucifera leaf flavonoids (NLF) were tested for the inhibition of lipase, α-glucosidase, and α-amylase activities in vitro. A single dose of NLF was administered by oral gavage in mice for acute toxicity. Wistar rats with high-fat diet-induced hyperlipidemia and two other animal models were used to evaluate the hypolipidemic effects of NLF.

RESULTS

Our in vitro biochemistry tests revealed that the NLF showed high inhibitory activity against porcine pancreatic lipase, α-amylase, and α-glucosidase with IC50 values of 0.38 ± 0.022, 2.20 ± 0.18, and 1.86 ± 0.018 mg/mL, respectively. Furthermore, the NLF significantly lowered the lipid components, such as the total cholesterol, triglycerides, low-density lipoprotein cholesterol, and malondialdehyde, in various established in vivo systems and raised the high-density lipoprotein cholesterol. Moreover, the NLF alleviated high-fat diet-induced lipid accumulation in the liver.

CONCLUSIONS

The results demonstrate that NLFs can effectively ameliorate hyperlipidemia and inhibit the key enzymes related to type 2 diabetes mellitus. Our findings may provide new pharmacological basis for the treatment of hyperlipidemia, hyperglycemia, and obesity using NLFs.

The Role of the ATP-Binding Cassette A1 (ABCA1) in Human Disease

Cholesterol homeostasis is essential in normal physiology of all cells. One of several proteins involved in cholesterol homeostasis is the ATP-binding cassette transporter A1 (ABCA1), a transmembrane protein widely expressed in many tissues. One of its main functions is the efflux of intracellular free cholesterol and phospholipids across the plasma membrane to combine with apolipoproteins, mainly apolipoprotein A-I (Apo A-I), forming nascent high-density lipoprotein-cholesterol (HDL-C) particles, the first step of reverse cholesterol transport (RCT). In addition, ABCA1 regulates cholesterol and phospholipid content in the plasma membrane affecting lipid rafts, microparticle (MP) formation and cell signaling. Thus, it is not surprising that impaired ABCA1 function and altered cholesterol homeostasis may affect many different organs and is involved in the pathophysiology of a broad array of diseases. This review describes evidence obtained from animal models, human studies and genetic variation explaining how ABCA1 is involved in dyslipidemia, coronary heart disease (CHD), type 2 diabetes (T2D), thrombosis, neurological disorders, age-related macular degeneration (AMD), glaucoma, viral infections and in cancer progression.

Epigenome-wide association study (EWAS) on lipids: the Rotterdam Study

BACKGROUND

DNA methylation is a key epigenetic mechanism that is suggested to be associated with blood lipid levels. We aimed to identify CpG sites at which DNA methylation levels are associated with blood levels of triglycerides, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and total cholesterol in 725 participants of the Rotterdam Study, a population-based cohort study. Subsequently, we sought replication in a non-overlapping set of 760 participants.

RESULTS

Genome-wide methylation levels were measured in whole blood using the Illumina Methylation 450 array. Associations between lipid levels and DNA methylation beta values were examined using linear mixed-effect models. All models were adjusted for sex, age, smoking, white blood cell proportions, array number, and position on array. A Bonferroni-corrected p value lower than 1.08 × 10^-7 was considered statistically significant. Five CpG sites annotated to genes including DHCR24, CPT1A, ABCG1, and SREBF1 were identified and replicated. Four CpG sites were associated with triglycerides, including CpG sites annotated to CPT1A (cg00574958 and cg17058475), ABCG1 (cg06500161), and SREBF1 (cg11024682). Two CpG sites were associated with HDL-C, including ABCG1 (cg06500161) and DHCR24 (cg17901584). No significant associations were observed with LDL-C or total cholesterol.

CONCLUSIONS

We report an association of HDL-C levels with methylation of a CpG site near DHCR24, a protein-coding gene involved in cholesterol biosynthesis, which has previously been reported to be associated with other metabolic traits. Furthermore, we confirmed previously reported associations of methylation of CpG sites within CPT1A, ABCG1, and SREBF1 and lipids. These results provide insight in the mechanisms that are involved in lipid metabolism.

The Triglyceride/High-Density Lipoprotein Cholesterol (TG/HDL-C) Ratio as a Risk Marker for Metabolic Syndrome and Cardiovascular Disease

Atherosclerosis is an immunoinflammatory pathological procedure in which lipid plaques are formed in the vessel walls, partially or completely occluding the lumen, and is accountable for atherosclerotic cardiovascular disease (ASCVD). ACSVD consists of three components: coronary artery disease (CAD), peripheral vascular disease (PAD) and cerebrovascular disease (CCVD). A disturbed lipid metabolism and the subsequent dyslipidemia significantly contribute to the formation of plaques, with low-density lipoprotein cholesterol (LDL-C) being the main responsible factor. Nonetheless, even when LDL-C is well regulated, mainly with statin therapy, a residual risk for CVD still occurs, and it is attributable to the disturbances of other lipid components, namely triglycerides (TG) and high-density lipoprotein cholesterol (HDL-C). Increased plasma TG and decreased HDL-C levels have been associated with metabolic syndrome (MetS) and CVD, and their ratio, TG/HDL-C, has been proposed as a novel biomarker for predicting the risk of both clinical entities. Under these terms, this review will present and discuss the current scientific and clinical data linking the TG/HDL-C ratio with the presence of MetS and CVD, including CAD, PAD and CCVD, in an effort to prove the value of the TG/HDL-C ratio as a valuable predictor for each aspect of CVD.

Lipoprotein(a), cardiovascular disease, and contemporary management

Elevated lipoprotein(a) (Lp[a]) is a causal genetic risk factor for cardiovascular disease. To determine if current evidence supports both screening and treatment for elevated Lp(a) in high-risk patients, an English-language search of PubMed and MEDLINE was conducted. In population studies, there is a continuous association between Lp(a) concentrations and cardiovascular risk, with synergistic effects when low-density lipoprotein (LDL) is also elevated. Candidates for Lp(a) screening include patients with a personal or family history of premature cardiovascular disease, familial hypercholesterolemia, recurrent cardiovascular events, or inadequate LDL cholesterol (LDL-C) responses to statins. Given the comparative strength of clinical evidence, reducing LDL-C to the lowest attainable value with a high-potency statin should be the primary focus of lipid-modifying therapies. If the Lp(a) level is 30 mg/dL or higher in a patient who has the aforementioned characteristics plus residual LDL-C elevations (≥70-100 mg/dL) despite maximum-potency statins or combination statin therapy, the clinician may consider adding niacin (up to 2 g/d). If, after these interventions, the patient has progressive coronary heart disease (CHD) or LDL-C levels of 160-200 mg/dL or higher, LDL apheresis should be contemplated. Although Lp(a) is a major causal risk factor for CHD, no currently available controlled studies have suggested that lowering it through either pharmacotherapy or LDL apheresis specifically and significantly reduces coronary risk. Further research is needed to (1) optimize management in order to reduce CHD risk associated with elevated Lp(a) and (2) determine what other intermediate- or high-risk groups might benefit from Lp(a) screening.

Polygenic risk score predicts prevalence of cardiovascular disease in patients with familial hypercholesterolemia

BACKGROUND

Although familial hypercholesterolemia (FH) is a severe monogenic disease, it has been shown that clinical risk factors and common genetic variants can modify cardiovascular disease (CVD) risk.

OBJECTIVE

The aim of the study was to evaluate the polygenic contribution to lipid traits and CVD in FH using genetic risk scores (GRSs).

METHODS

Among the 20,434 subjects attending the lipid clinic, we identified and included 725 individuals who carried an FH causing mutation in this retrospective cohort study. We evaluated the association of GRSs for several traits including coronary artery disease (CAD; GRS_CAD) as well as plasma concentrations of low-density lipoprotein cholesterol (LDL-C; GRS_LDL-C), high-density lipoprotein cholesterol (GRS_HDL-C) and triglycerides (GRS_TG).

RESULTS

A total of 32% (n = 231) of FH subjects presented a CVD event before their first visit. Patients in the highest GRS_LDL-C tertile presented an LDL-C 0.4 mmol/L (15.5 mg/dL) higher than the subjects in the lowest tertile (P = .01). The GRS_CAD was strongly associated with CVD events (odds ratio 1.80; 95% confidence interval 1.14-2.85; P = .01) even after adjustment for cardiovascular risk factors. Compared with subjects in the first tertile, those in the third GRS_CAD tertile had a significantly higher prevalence of events (40.9% vs 24.7%, P < .0001) and a significantly higher number of events (average 0.97 vs 0.57 [P = .0001] events per individual).

CONCLUSION

These results indicate that even in the context of a severe monogenic disease such as FH, common genetic variants can significantly modify the disease phenotype. The use of the 192-SNPs GRS_CAD may refine CVD risk prediction in FH patients and this could lead to a more personalized approach to therapy.

Monascin and ankaflavin act as natural AMPK activators with PPARα agonist activity to down-regulate nonalcoholic steatohepatitis in high-fat diet-fed C57BL/6 mice

Yellow pigments monascin (MS) and ankaflavin (AK) are secondary metabolites derived from Monascus-fermented products. The hypolipidemic and anti-inflammatory effects of MS and AK indicate that they have potential on preventing or curing nonalcoholic fatty liver disease (NAFLD). Oleic acid (OA) and high-fat diet were used to induce steatosis in FL83B hepatocytes and NAFLD in mice, respectively. We found that both MS and AK prevented fatty acid accumulation in hepatocytes by inhibiting fatty acid uptake, lipogenesis, and promoting fatty acid beta-oxidation mediated by activating peroxisome proliferator-activated receptor (PPAR)-α and AMP-activated kinase (AMPK). Furthermore, MS and AK significantly attenuated high-fat diet-induced elevation of total cholesterol (TC), triaceylglycerol (TG), free fatty acid (FFA), and low density lipoprotein-cholesterol (LDL-C) in plasma. MS and AK promoted AMPK phosphorylation, suppressed the steatosis-related mRNA expression and inflammatory cytokines secretion, as well as upregulated farnesoid X receptor (FXR), peroxisome proliferator-activated receptor gamma co-activator (PGC)-1α, and PPARα expression to induce fatty acid oxidation in the liver of mice. We provided evidence that MS and AK act as PPARα agonists to upregulate AMPK activity and attenuate NAFLD. MS and AK may be supplied in food supplements or developed as functional foods to reduce the risk of diabetes and obesity.

Molecular functions of the iron-regulated metastasis suppressor, NDRG1, and its potential as a molecular target for cancer therapy

N-myc down-regulated gene 1 (NDRG1) is a known metastasis suppressor in multiple cancers, being also involved in embryogenesis and development, cell growth and differentiation, lipid biosynthesis and myelination, stress responses and immunity. In addition to its primary role as a metastasis suppressor, NDRG1 can also influence other stages of carcinogenesis, namely angiogenesis and primary tumour growth. NDRG1 is regulated by multiple effectors in normal and neoplastic cells, including N-myc, histone acetylation, hypoxia, cellular iron levels and intracellular calcium. Further, studies have found that NDRG1 is up-regulated in neoplastic cells after treatment with novel iron chelators, which are a promising therapy for effective cancer management. Although the pathways by which NDRG1 exerts its functions in cancers have been documented, the relationship between the molecular structure of this protein and its functions remains unclear. In fact, recent studies suggest that, in certain cancers, NDRG1 is post-translationally modified, possibly by the activity of endogenous trypsins, leading to a subsequent alteration in its metastasis suppressor activity. This review describes the role of this important metastasis suppressor and discusses interesting unresolved issues regarding this protein.

Association between high-normal levels of alanine aminotransferase and risk factors for atherogenesis

BACKGROUND & AIMS

Liver disease has been associated with cardiovascular disorders, but little is known about the relationship between serum levels of alanine aminotransferase (ALT) and markers of atherogenesis. We investigated the relationship between low-normal and high-normal levels of ALT and an extended panel of cardiovascular risk factors among individuals with no known diseases in a primary care setting.

METHODS

We performed a retrospective analysis of data collected from 6442 asymptomatic patients at wellness visits to a primary care setting in central Virginia from 2010 through 2011. Serum levels of ALT were compared with levels of lipids and lipoproteins, as well as metabolic, inflammatory, and coagulation-related factors associated with risk for cardiovascular disease.

RESULTS

Serum levels of ALT were higher than 40 IU/L in 12% of subjects, and in the high-normal range (19-40 IU/L in women and 31-40 IU/L in men) in 25% of subjects. ALT level was associated with the apolipoprotein B level, concentration and particle size of very-low-density lipoproteins, concentration of low-density lipoprotein (LDL) particles (LDL-P), and percentages of small dense LDL (sdLDL) and sdLDL-cholesterol (sdLDL-C) (P < .0001 for all). A high-normal level of ALT was associated with higher levels of LDL-C, LDL-P, sdLDL-C, and sdLDL particles (P < .001 for all). These effects were independent of age, body mass index, and hyperinsulinemia. Increasing levels of ALT and fasting hyperinsulinemia (>12 μU/mL) synergized with increasing levels of triglycerides, very-low-density lipoprotein particles, LDL-P, sdLDL-C, and percentage of sdLDL-C. Levels of APOA1, high-density lipoprotein-cholesterol, and high-density lipoprotein-class 2 were associated inversely with serum level of ALT (P < .0001 for all).

CONCLUSIONS

In an analysis of asymptomatic individuals, increased serum levels of ALT (even high-normal levels) are associated with markers of cardiovascular disease.