Comparison of the metabolic profiles and their cardiovascular event risks of metformin users versus insulin users. A cohort study of people with type 2 diabetes from the UK Biobank

AIM

The aims of this study were to compare the metabolic profiles of type 2 diabetes mellitus patients with metformin and insulin monotherapy, to assess the associations of metabolites with major adverse cardiovascular events (MACE) distinctly for metformin-only and insulin-only users, and to test for effect modification by the glucose-lowering treatment.

METHODS

We included 3,058 metformin-only and 558 insulin-only users from the UK Biobank. Mean concentrations of 249 metabolites of metformin and insulin users were compared with Cohen's d, their associations with MACE were assessed with Cox regression and interaction terms were tested.

RESULTS

Mean VLDL size, HDL size, and concentrations of large and very large HDL molecules differed between insulin-only and metformin-only users. Overall, 75 metabolomic biomarkers were significantly associated with MACE in insulin-only users and 57 in metformin-only users. Significant interaction terms were observed between treatment group and albumin (protective in metformin users only) and 86 lipids/fatty acids, which were all statistically significantly associated with MACE among insulin users only.

CONCLUSION

Metformin and insulin users have different metabolic profiles and a consistent pattern emerged that the metabolic profile of metformin users is favorable compared to the one of insulin users due to a lower associated MACE risk.

Higher high-density lipoprotein cholesterol levels increased vertebral osteoporotic fracture, but reduced hip fracture in men based on the National Health Insurance Service-National Health Screening Cohort

BACKGROUND CONTEXT

Lipids are currently known to play an important role in bone metabolism.

PURPOSE

This study aimed to investigate the effect of high-density lipoprotein cholesterol (HDL-C) on osteoporotic fractures beyond its beneficial effects on the cardiovascular system.

STUDY DESIGN/SETTING

This was a retrospective, observational study that used data from the National Health Insurance Service-Health Screening cohort database.

PATIENT SAMPLE

This study included 318,237 participants who were 50 years or older and with HDL-C levels of 10 to 200 mg/dL.

OUTCOMES MEASURES

Physiologic measure-Diagnosis of osteoporotic fracture during the follow-up period.

METHODS

The study participants were categorized into four quartiles according to baseline HDL-C levels. The Cox proportional hazards model was used to assess osteoporotic fracture risk according to HDL-C levels.

RESULTS

After full adjustment and with the Q1 group as the reference group, estimates of hazard ratios (HRs; 95% confidence intervals [CIs]) for any osteoporotic fracture in men were 1.03 (0.94-1.12), 1.02 (0.93-1.11), and 1.07 (0.98-1.18) for the Q2, Q3, and Q4 groups, respectively. After classifying osteoporotic fractures according to the body location, the fully adjusted HRs for vertebral and hip fractures in the men's Q4 groups were 1.16 (1.02-1.31) and 0.74 (0.57-0.96), respectively. In women, fully adjusted HRs (95% CIs) of the female Q4 group for any osteoporotic, vertebral, and hip fractures were 1.03 (0.95-1.11), 0.96 (0.86-1.07), and 1.06 (0.80-1.41), respectively.

CONCLUSION

In this study, HDL-C levels were positively associated with vertebral fractures in both men and women but inversely related to hip fractures in men. Therefore, monitoring the lipid profiles of patients with osteoporosis may be beneficial for the prevention of osteoporotic fractures.

Apolipoprotein A1 is associated with osteocalcin and bone mineral density rather than high-density lipoprotein cholesterol in Chinese postmenopausal women with type 2 diabetes mellitus

Objective

Disturbances in high-density lipoprotein cholesterol (HDL-c) metabolic pathways can affect bone metabolism, which may rely on the particle function of apolipoprotein rather than HDL-c levels. This study aimed to evaluate the correlation of serum HDL-c and apolipoprotein A1 (APOA1) with bone metabolism in Chinese postmenopausal women with type 2 diabetes mellitus (T2DM).

Method

A total of 1,053 participants with complete data were enrolled and separated into three groups based on the HDL-c and APOA1 tertiles. The trained reviewer collected demographic and anthropometric information. Bone turnover markers (BTMs) were determined by standard methods. Bone mineral density (BMD) was measured by dual-energy x-ray absorptiometry.

Results

Overall, the prevalence of osteoporosis was 29.7%. Groups with higher APOA1 have a remarkably more elevated level of osteocalcin (OC), L1-L4 BMD, and T-score across the APOA1 tertiles. APOA1 presented a positive correlation with OC (r = 0.194, p < 0.001), L1-L4 BMD (r = 0.165, p < 0.001), and T-score (r = 0.153, p < 0.001) rather than HDL-c. Meanwhile, APOA1 remained independently associated with OC (β = 0.126, p < 0.001), L1-L4 BMD (β = 0.181, p < 0.001), and T-score (β = 0.180, p < 0.001) after adjustment for confounding factors. APOA1 is also shown to be independently correlated with osteoporosis after adjustment for confounding factors, and the OR (95%CI) was 0.851 (0.784-0.924). In contrast, there was no significant association between HDL-c and osteoporosis. Furthermore, APOA1 seemed to have the largest areas under the curve (AUC) for osteoporosis. The AUC (95% CI) of APOA1 identifying osteoporosis was 0.615 (0.577-0.652). The optimal cut-off value of APOA1 was 0.89 g/L (sensitivity: 56.5%, specificity: 67.9%).

Conclusion

APOA1 is independently associated with OC, L1-L4 BMD, and osteoporosis rather than HDL-c in Chinese postmenopausal women with T2DM.

High-Density Lipoprotein in Metabolic Disorders and Beyond: An Exciting New World Full of Challenges and Opportunities

High-density lipoprotein (HDL) is an enigmatic member of the plasma lipid and lipoprotein transport system, best known for its ability to promote the reverse cholesterol efflux and the unloading of excess cholesterol from peripheral tissues. More recently, data in experimental mice and humans suggest that HDL may play important novel roles in other physiological processes associated with various metabolic disorders. Important parameters in the HDL functions are its apolipoprotein and lipid content, further reinforcing the principle that HDL structure defines its functionality. Thus, based on current evidence, low levels of HDL-cholesterol (HDL-C) or dysfunctional HDL particles contribute to the development of metabolic diseases such as morbid obesity, type 2 diabetes mellitus, and nonalcoholic fatty liver disease. Interestingly, low levels of HDL-C and dysfunctional HDL particles are observed in patients with multiple myeloma and other types of cancer. Therefore, adjusting HDL-C levels within the optimal range and improving HDL particle functionality is expected to benefit such pathological conditions. The failure of previous clinical trials testing various HDL-C-raising pharmaceuticals does not preclude a significant role for HDL in the treatment of atherosclerosis and related metabolic disorders. Those trials were designed on the principle of "the more the better", ignoring the U-shape relationship between HDL-C levels and morbidity and mortality. Thus, many of these pharmaceuticals should be retested in appropriately designed clinical trials. Novel gene-editing-based pharmaceuticals aiming at altering the apolipoprotein composition of HDL are expected to revolutionize the treatment strategies, improving the functionality of dysfunctional HDL.

A New Look at Novel Cardiovascular Risk Biomarkers: The Role of Atherogenic Lipoproteins and Innovative Antidiabetic Therapies

The presence of residual cardiovascular disease (CVD) risk is a current dilemma in clinical practice; indeed, despite optimal management and treatment, a considerable proportion of patients still undergo major CV events. Novel lipoprotein biomarkers are suggested as possible targets for improving the outcomes of patients at higher risk for CVD, and their impact on major CV events and mortality have previously been investigated. Innovative antidiabetic therapies have recently shown a significant reduction in atherogenic lipoproteins, beyond their effects on glucose parameters; it has also been suggested that such anti-atherogenic effect may represent a valuable mechanistic explanation for the cardiovascular benefit of, at least, some of the novel antidiabetic agents, such as glucagon-like peptide-1 receptor agonists. This emphasizes the need for further research in the field in order to clearly assess the effects of innovative treatments on different novel biomarkers, including atherogenic lipoproteins, such as small dense low-density lipoprotein (LDL), lipoprotein(a) (Lp(a)) and dysfunctional high-density lipoprotein (HDL). The current article discusses the clinical importance of novel lipid biomarkers for better management of patients in order to overcome residual cardiovascular risk.

High density lipoprotein in atherosclerosis and coronary heart disease: Where do we stand today?

Epidemiological studies during the last five years suggest that a relation between high density lipoprotein cholesterol (HDL-C) levels and the risk for cardiovascular disease (CVD) does exist but follows rather a "U-shaped" curve with an optimal range of HDL-C concentration between 40 and 70 mg/dl for men and 50-70 mg/dl for women. Moreover, as research in the field of lipoproteins progresses it becomes increasingly apparent that HDL particles possess different attributes and depending on their structural and functional characteristics, they may be "antiatherogenic" or "proatherogenic". In light of this information, it is highly doubtful that the choice of experimental drugs and the design of respective clinical trials that put the HDL-C raising hypothesis at test, were the most suitable. Here, we compile the existing literature on HDL, providing a critical up-to-date view that focuses on key data from the biochemistry, epidemiology and pharmacology of HDL, including data from clinical trials. We also discuss the most up-to-date information on the contribution of HDL structure and function to the prevention of atherosclerosis. We conclude by summarizing important differences between mouse models and humans, that may explain why pharmacological successes in mice turn out to be failures in humans.

HDL and type 2 diabetes: the chicken or the egg?

HDL is a complex macromolecular cluster of various components, such as apolipoproteins, enzymes and lipids. Quality evidence from clinical and epidemiological studies led to the principle that HDL-cholesterol (HDL-C) levels are inversely correlated with the risk of CHD. Nevertheless, the failure of many cholesteryl ester transfer protein inhibitors to protect against CVD casts doubts on this principle and highlights the fact that HDL functionality, as dictated by its proteome and lipidome, also plays an important role in protecting against metabolic disorders. Recent data indicate that HDL-C levels and HDL particle functionality are correlated with the pathogenesis and prognosis of type 2 diabetes mellitus, a major risk factor for CVD. Hyperglycaemia leads to reduced HDL-C levels and deteriorated HDL functionality, via various alterations in HDL particles' proteome and lipidome. In turn, reduced HDL-C levels and impaired HDL functionality impact the performance of key organs related to glucose homeostasis, such as pancreas and skeletal muscles. Interestingly, different structural alterations in HDL correlate with distinct metabolic abnormalities, as indicated by recent data evaluating the role of apolipoprotein A1 and lecithin-cholesterol acyltransferase deficiency in glucose homeostasis. While it is becoming evident that not all HDL disturbances are causatively associated with the development and progression of type 2 diabetes, a bidirectional correlation between these two conditions exists, leading to a perpetual self-feeding cycle.

The Lipoprotein Transport System in the Pathogenesis of Multiple Myeloma: Advances and Challenges

Multiple myeloma (MM) is an incurable neoplastic hematologic disorder characterized by malignant plasma cells, mainly in the bone marrow. MM is associated with multiple factors, such as lipid metabolism, obesity, and age-associated disease development. Although, the precise pathogenetic mechanisms remain unknown, abnormal lipid and lipoprotein levels have been reported in patients with MM. Interestingly, patients with higher APOA1 levels, the major apolipoprotein of high density lipoprotein (HDL), have better overall survival. The limited existing studies regarding serum lipoproteins in MM are inconclusive, and often contradictory. Nevertheless, it appears that deregulation of the lipoprotein transport system may facilitate the development of the disease. Here, we provide a critical review of the literature on the role of lipids and lipoproteins in MM pathophysiology. We also propose novel mechanisms, linking the development and progression of MM to the metabolism of blood lipoproteins. We anticipate that proteomic and lipidomic analyses of serum lipoproteins along with analyses of their functionality may improve our understanding and shed light on novel mechanistic aspects of MM pathophysiology.

Tissue-specific functional interaction between apolipoproteins A1 and E in cold-induced adipose organ mitochondrial energy metabolism

White (WAT) and brown (BAT) adipose tissue, the two main types of adipose organ, are responsible for lipid storage and non-shivering thermogenesis, respectively. Thermogenesis is a process mediated by mitochondrial uncoupling protein 1 (UCP1) which uncouples oxidative phosphorylation from ATP production, leading to the conversion of free fatty acids to heat. This process can be triggered by exposure to low ambient temperatures, caloric excess, and the immune system. Recently mitochondrial thermogenesis has also been associated with plasma lipoprotein transport system. Specifically, apolipoprotein (APO) E3 is shown to have a bimodal effect on WAT thermogenesis that is highly dependent on its site of expression. Similarly, APOE2 and APOE4 differentially affect BAT and WAT mitochondrial metabolic activity in processes highly modulated by APOA1. Furthermore, the absence of classical APOA1 containing HDL (APOA1-HDL), is associated with no measurable non-shivering thermogenesis in WAT of mice fed high fat diet. Based on these previous observations which indicate important regulatory roles for both APOA1 and APOE in adipose tissue mitochondrial metabolic activity, here we sought to investigate the potential roles of these apolipoproteins in BAT and WAT metabolic activation in mice, following stimulation by cold exposure (7 °C). Our data indicate that APOA1-HDL promotes metabolic activation of BAT only in the presence of very low levels (virtually undetectable) of APOE3-containing HDL (APOE3-HDL), which acts as an inhibitor in this process. In contrast, induction of WAT thermogenesis is subjected to a more complicated regulation which requires the combined presence of both APOA1-HDL and APOE3-HDL.

Interaction between high-density lipoproteins and inflammation: Function matters more than concentration!

High-density lipoprotein (HDL) plays an important role in lipid metabolism and especially contributes to the reverse cholesterol transport pathway. Over recent years it has become clear that the effect of HDL on immune-modulation is not only dependent on HDL concentration but also and perhaps even more so on HDL function. This review will provide a concise general introduction to HDL followed by an overview of post-translational modifications of HDL and a detailed overview of the role of HDL in inflammatory diseases. The clinical potential of HDL and its main apolipoprotein constituent, apoA-I, is also addressed in this context. Finally, some conclusions and remarks that are important for future HDL-based research and further development of HDL-focused therapies are discussed.

High-Density Lipoproteins and Apolipoprotein A1

High-density lipoprotein (HDL) and its main protein component apolipoprotein (apo)A-I, play an important role in cholesterol homeostasis. It has been demonstrated that HDLs comprise of a very heterogeneous group of particles, not only regarding size but also composition. HDL's best described function is its role in the reverse cholesterol transport, where lipid-free apoA-I or small HDLs can accept and take up cholesterol from peripheral cells and subsequently transport this to the liver for excretion. However, several other functions have also been described, like anti-oxidant, anti-inflammatory and anti-thrombotic effects. In this article, the general features, synthesis and metabolism of apoA-I and HDLs will be discussed. Additionally, an overview of HDL functions will be given, especially in the context of some major pathologies like cardiovascular disease, cancer and diabetes mellitus. Finally, the therapeutic potential of raising HDL will be discussed, focussing on the difficulties of the past and the promises of the future.

Τhe Antioxidant Function of HDL in Atherosclerosis

Atherosclerosis is a multistep process that progresses over a long period of time and displays a broad range of severity. In its final form, it manifests as a lesion of the intimal layer of the arterial wall. There is strong evidence supporting that oxidative stress contributes to coronary heart disease morbidity and mortality and antioxidant high-density lipoprotein (HDL) could have a beneficial role in the prevention and prognosis of the disease. Indeed, certain subspecies of HDL may act as natural antioxidants preventing oxidation of lipids on low-density lipoprotein (LDL) and biological membranes. The antioxidant function may be attributed to inhibition of synthesis or neutralization of free radicals and reactive oxygen species by HDL lipids and associated enzymes or transfer of oxidation prone lipids from LDL and biological membranes to HDL for catabolism. A limited number of clinical trials suggest that the increased antioxidant potential of HDL correlates with decreased risk for atherosclerosis. Some nutritional interventions to increase HDL antioxidant activity have been proposed with limited success so far. The limitations in measuring and understanding HDL antioxidant function in vivo are also discussed.

Apolipoprotein CIII and diabetes. Is there a link?

Apolipoprotein CIII (ApoCIII), a small protein that resides on the surface of lipoprotein particles, is a key regulator of triglyceride metabolism. The inhibition of lipoprotein lipase (LPL), the increased assembly and secretion of very low-density lipoproteins (VLDL) and the decreased reuptake of triglyceride-rich lipoproteins (TRLs) by the liver are mechanisms associating elevated serum ApoCIII levels and hypertriglyceridemia. ApoCIII concentration is high in individuals with diabetes mellitus, indicating a possible positive correlation with impairment of glucose metabolism. The aim of this review (based on a Pubmed search until August 2018) is to present the possible mechanisms linking ApoCIII and deterioration of carbohydrate homeostasis. ApoCIII enhances pancreatic β-cells apoptosis via an increase of the cytoplasmic Ca²⁺ levels in the insulin-producing cells. In addition, overexpression of ApoCIII enhances non-alcoholic fatty liver disease and exacerbates inflammatory pathways in skeletal muscles, affecting insulin signalling and thereby inducing insulin resistance. Moreover, recent studies reveal a possible mechanism of body weight increase and glucose production through a potential ApoCIII-induced LPL inhibition in the hypothalamus. Also, the presence of ApoCIII on the surface of high-density lipoprotein particles is associated with impairment of their antiglycemic and atheroprotective properties. Modulating ApoCIII may be a potent therapeutic approach to manage hypertriglyceridemia and improve carbohydrate metabolism.

The effects of cigarette smoking and smoking cessation on high-density lipoprotein functions: implications for coronary artery disease

BACKGROUND

Smoking cessation was associated with improved prognosis of coronary artery disease. This study was designed to investigate the effect of smoking cessation on high-density lipoprotein functionality in coronary artery disease patients.

METHODS

In this prospective, randomized and parallel controlled study, coronary artery disease smokers ( n = 28) and healthy smokers ( n = 30) were divided into smoking cessation group and continuous smoking group, respectively. Blood samples were collected before and after three-month smoking cessation. Plasma high-density lipoprotein was isolated by density gradient centrifugation. The ability of high-density lipoprotein against copper-induced oxidation of lipoprotein was determined to evaluate the antioxidative property of high-density lipoprotein, and the macrophage migration inhibited by high-density lipoprotein was tested to identify the antichemotactic property of high-density lipoprotein. High-density lipoprotein-induced macrophage cholesterol efflux was measured by fluorescence spectrometry using NBD cholesterol analogue. Healthy non-smoking volunteers were enrolled as the baseline control.

RESULTS

The baseline antioxidative, antichemotactic ability of high-density lipoprotein and high-density lipoprotein-induced cellular cholesterol efflux in coronary artery disease smokers and healthy smokers were significantly attenuated when compared with those in healthy non-smokers. After three-month smoking cessation, both the antioxidative ability and antichemotactic ability of high-density lipoprotein were improved significantly in coronary artery disease smokers. However, high-density lipoprotein-induced cellular cholesterol efflux was not increased by smoking cessation. In in vitro experiments, carbon monoxide reduced the antioxidative ability and nicotine enhanced the antichemotactic ability of high-density lipoprotein.

CONCLUSIONS

Smoking cessation is an effective measure to improve high-density lipoprotein functions in coronary artery disease smokers. Our study re-emphasizes the importance of smoking cessation in the secondary prevention of coronary artery disease.

Pharmacological Management of Dyslipidemia in Atherosclerosis: Limitations, Challenges, and New Therapeutic Opportunities

Clinical and epidemiological studies during the last 7 decades indicated that elevated low-density lipoprotein cholesterol (LDL-C) levels and reduced high-density lipoprotein cholesterol (HDL-C) levels correlate with the pathogenesis and progression of atherosclerotic lesions in the arterial wall. This observation led to the development of LDL-C-lowering drugs for the prevention and treatment of atherosclerosis, some with greater success than others. However, a body of recent clinical evidence shows that a substantial residual cardiovascular risk exists even at very low levels of LDL-C, suggesting that new therapeutic modalities are still needed for reduction of atherosclerosis morbidity and mortality. Unfortunately, HDL-C-raising drugs developed toward this goal had disappointing results thus far. Here, we critically review the literature presenting available evidence and challenges that need to be met and discuss possible new avenues for the development of novel lipid pharmacotherapeutics to reduce the burden of atherosclerosis.

Nordic Walking Training Causes a Decrease in Blood Cholesterol in Elderly Women Supplemented with Vitamin D

OBJECTIVE

Different studies have demonstrated that regular exercise can induce changes in the lipid profile, but results remain inconclusive. Available data suggest that correction of vitamin D deficiency can improve the lipid profile. In this study, we have hypothesized that Nordic Walking training will improve lipid profile in elderly women supplemented with vitamin D.

METHODS

A total of 109 elderly women (68 ± 5.12 years old) took part in the study. First group [experimental group (EG): 35 women] underwent 12 weeks of Nordic Walking (NW) training combined with vitamin D supplementation (4,000 IU/day), second group [supplementation group (SG): 48 women] was only supplemented with vitamin D (4,000 IU/day), and third group [control group (CG): 31 women] was not subject to any interventions. Blood analysis of total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and 25-OH-D₃ was performed at baseline and after the 12 weeks of NW training. Additionally, a battery of field tests specifically developed for older adults was used to assess the components of functional fitness. The same blood analysis was repeated for the EG 6 months after the main experiment.

RESULTS

After 12 weeks of NW training and vitamin D supplementation, in the EG a decrease in TC, LDL-C, and TG was observed. In the SG, no changes in the lipid profile were observed, whereas in the CG an increase in the HDL-C level was noticed. Positive physical fitness changes were only observed in the EG.

CONCLUSION

Our obtained data confirmed baseline assumption that regular exercise induces positive alternations in lipid profile in elderly women supported by supplementation of vitamin D.

Pleiotropic effects of apolipoprotein C3 on HDL functionality and adipose tissue metabolic activity

APOC3 is produced mainly by the liver and intestine and approximately half of plasma APOC3 associates with HDL. Though it was believed that APOC3 associates with HDL by simple binding to preexisting particles, recent data support that biogenesis of APOC3-containing HDL (APOC3-HDL) requires Abca1. Moreover, APOC3-HDL contributes to plasma triglyceride homeostasis by preventing APOC3 association with triglyceride-rich lipoproteins. Interestingly, APOC3-HDL also shows positive correlation with the morbidly obese phenotype. However, the roles of APOC3 in HDL functionality and adipose tissue metabolic activity remain unknown. Therefore, here we investigated the direct effects of APOC3 expression on HDL structure and function, as well as white adipose tissue (WAT) and brown adipose tissue (BAT) metabolic activity. C57BL/6 mice were infected with an adenovirus expressing human APOC3 or a recombinant attenuated control adenovirus expressing green fluorescent protein and blood and tissue samples were collected at 5 days postinfection. HDL was then analyzed for its apolipoprotein and lipid composition and particle functionality. Additionally, purified mitochondria from BAT and WAT were analyzed for uncoupling protein 1, cytochrome c (Cytc), and Cytc oxidase subunit 4 protein levels as an indirect measure of their metabolic activity. Serum metabolomic analysis was performed by NMR. Combined, our data show that APOC3 modulates HDL structure and function, while it selectively promotes BAT metabolic activation.

High-density lipoprotein (HDL) metabolism and bone mass

It is well appreciated that high-density lipoprotein (HDL) and bone physiology and pathology are tightly linked. Studies, primarily in mouse models, have shown that dysfunctional and/or disturbed HDL can affect bone mass through many different ways. Specifically, reduced HDL levels have been associated with the development of an inflammatory microenvironment that affects the differentiation and function of osteoblasts. In addition, perturbation in metabolic pathways of HDL favors adipoblastic differentiation and restrains osteoblastic differentiation through, among others, the modification of specific bone-related chemokines and signaling cascades. Increased bone marrow adiposity also deteriorates bone osteoblastic function and thus bone synthesis, leading to reduced bone mass. In this review, we present the current knowledge and the future directions with regard to the HDL-bone mass connection. Unraveling the molecular phenomena that underline this connection will promote the deeper understanding of the pathophysiology of bone-related pathologies, such as osteoporosis or bone metastasis, and pave the way toward the development of novel and more effective therapies against these conditions.

Distinct Roles of Apolipoproteins A1 and E in the Modulation of High-Density Lipoprotein Composition and Function

In addition to high-density lipoprotein cholesterol (HDL-C) levels, HDL quality also appears to be very important for atheroprotection. Analysis of various clinical paradigms suggests that the lipid and apolipoprotein composition of HDL defines its size, shape, and functions and may determine its beneficial effects on human health. Previously, we reported that like apolipoprotein A-I (Apoa1), apolipoprotein E (Apoe) is also capable of promoting the de novo biogenesis of HDL with the participation of ATP binding cassette A lipid transporter member 1 (Abca1) and plasma enzyme lecithin:cholesterol acyltransferase (Lcat), in a manner independent of a functional Apoa1. Here, we performed a comparative analysis of the functions of these HDL subpopulations. Specifically, Apoe and Apoa1 double-deficient (Apoe(-/-) × Apoa1(-/-)) mice were infected with APOA1- or APOE3-expressing adenoviruses, and APOA1-containing HDL (APOA1-HDL) and APOE3-containing HDL (APOE3-HDL), respectively, were isolated and analyzed by biochemical and physicochemical methods. Western blot and lipidomic analyses indicated significant differences in the apolipoprotein and lipid composition of the two HDL species. Moreover APOE3-HDL presented a markedly reduced antioxidant potential and Abcg1-mediated cholesterol efflux capacity. Surprisingly, APOE3-HDL but not APOA1-HDL attenuated LPS-induced production of TNFα in RAW264.7 cells, suggesting that the anti-inflammatory effects of APOA1 are dependent on APOE expression. Taken together, our data indicate that APOA1 and APOE3 recruit different apolipoproteins and lipids on the HDL particle, leading to structurally and functionally distinct HDL subpopulations. The distinct role of these two apolipoproteins in the modulation of HDL functionality may pave the way toward the development of novel pharmaceuticals that aim to improve HDL functionality.

The effect of red grape seed extract on serum paraoxonase activity in patients with mild to moderate hyperlipidemia

CONTEXT AND OBJECTIVE

Red grape seed extract (RGSE) contains oligomeric proanthocyanidin complexes as a class of flavonoids. These compounds are potent antioxidants and exert many health-promoting effects. This study aimed to determine the effects of RGSE on serum levels of triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein AI (apo-AI) levels and paraoxonase (PON) activity in patients with mild to moderate hyperlipidemia (MMH).

DESIGN AND SETTINGS

A randomized double-blind placebo-controlled clinical trial was conducted at Shahid-Modarres Hospital (Tehran, Iran) and Tabriz University of Medical Sciences. Seventy MMH patients were randomly assigned to receive treatment (200 mg/day of RGSE) or placebo for eight weeks.

RESULTS

Significant elevation in serum levels of apo-AI (P = 0.001), HDL-C (P = 0.001) and PON activity (P = 0.001) and marked decreases in concentrations of TC (P = 0.015), TG (P = 0.011) and LDL-C (P = 0.014) were found in the cases. PON activity was significantly correlated with apo-AI (r = 0.270; P < 0.01) and HDL-C (r = 0.45; P < 0.001). Significant differences between the RGSE and control groups (before and after treatment) for TC (P = 0.001), TG (P = 0.001), PON (P = 0.03), apo-AI (P = 0.001) and LDL-C (P = 0.002) were seen.

CONCLUSION

It is possible that RGSE increases PON activity mostly through increasing HDL-C and apo-AI levels in MMH patients. It may thus have potential beneficial effects in preventing oxidative stress and atherosclerosis in these patients.

Advances in high-density lipoprotein physiology: surprises, overturns, and promises

Emerging evidence strongly supports that changes in the HDL metabolic pathway, which result in changes in HDL proteome and function, appear to have a causative impact on a number of metabolic disorders. Here, we provide a critical review of the most recent and novel findings correlating HDL properties and functionality with various pathophysiological processes and disease states, such as obesity, type 2 diabetes mellitus, nonalcoholic fatty liver disease, inflammation and sepsis, bone and obstructive pulmonary diseases, and brain disorders.

Effects of Initiating Moderate Alcohol Intake on Cardiometabolic Risk in Adults With Type 2 Diabetes: A 2-Year Randomized, Controlled Trial

BACKGROUND

Recommendations for moderate alcohol consumption remain controversial, particularly in type 2 diabetes mellitus (T2DM). Long-term randomized, controlled trials (RCTs) are lacking.

OBJECTIVE

To assess cardiometabolic effects of initiating moderate alcohol intake in persons with T2DM and whether the type of wine matters.

DESIGN

2-year RCT (CASCADE [CArdiovaSCulAr Diabetes & Ethanol] trial). (ClinicalTrials.gov: NCT00784433).

SETTING

Ben-Gurion University of the Negev-Soroka Medical Center and Nuclear Research Center Negev, Israel.

PATIENTS

Alcohol-abstaining adults with well-controlled T2DM.

INTERVENTION

Patients were randomly assigned to 150 mL of mineral water, white wine, or red wine with dinner for 2 years. Wines and mineral water were provided. All groups followed a Mediterranean diet without caloric restriction.

MEASUREMENTS

Primary outcomes were lipid and glycemic control profiles. Genetic measurements were done, and patients were followed for blood pressure, liver biomarkers, medication use, symptoms, and quality of life.

RESULTS

Of the 224 patients who were randomly assigned, 94% had follow-up data at 1 year and 87% at 2 years. In addition to the changes in the water group (Mediterranean diet only), red wine significantly increased high-density lipoprotein cholesterol (HDL-C) level by 0.05 mmol/L (2.0 mg/dL) (95% CI, 0.04 to 0.06 mmol/L [1.6 to 2.2 mg/dL]; P < 0.001) and apolipoprotein(a)1 level by 0.03 g/L (CI, 0.01 to 0.06 g/L; P = 0.05) and decreased the total cholesterol-HDL-C ratio by 0.27 (CI, -0.52 to -0.01; P = 0.039). Only slow ethanol metabolizers (alcohol dehydrogenase alleles [ADH1B*1] carriers) significantly benefited from the effect of both wines on glycemic control (fasting plasma glucose, homeostatic model assessment of insulin resistance, and hemoglobin A1c) compared with fast ethanol metabolizers (persons homozygous for ADH1B*2). Across the 3 groups, no material differences were identified in blood pressure, adiposity, liver function, drug therapy, symptoms, or quality of life, except that sleep quality improved in both wine groups compared with the water group (P = 0.040). Overall, compared with the changes in the water group, red wine further reduced the number of components of the metabolic syndrome by 0.34 (CI, -0.68 to -0.001; P = 0.049).

LIMITATION

Participants were not blinded to treatment allocation.

CONCLUSION

This long-term RCT suggests that initiating moderate wine intake, especially red wine, among well-controlled diabetics as part of a healthy diet is apparently safe and modestly decreases cardiometabolic risk. The genetic interactions suggest that ethanol plays an important role in glucose metabolism, and red wine's effects also involve nonalcoholic constituents.

PRIMARY FUNDING SOURCE

European Foundation for the Study of Diabetes.

HDL/ApoA-1 infusion and ApoA-1 gene therapy in atherosclerosis

The HDL hypothesis stating that simply raising HDL cholesterol (HDL-C) may produce cardiovascular benefits has been questioned recently based on several randomized clinical trials using CETP inhibitors or niacin to raise HDL-C levels. However, extensive pre-clinical data support the vascular protective effects of administration of exogenous ApoA-1 containing preβ-HDL like particles. Several small proof-of-concept clinical trials using such HDL/ApoA-1 infusion therapy have shown encouraging results but definitive proof of efficacy must await large scale clinical trials. In addition to HDL infusion therapy an alternative way to exploit beneficial cardiovascular effects of HDL/ApoA-1 is to use gene transfer. Preclinical studies have shown evidence of benefit using this approach; however clinical validation is yet lacking. This review summarizes our current knowledge of the aforementioned strategies.