High density lipoprotein cholesterol: an evolving target of therapy in the management of cardiovascular disease

High density lipoprotein: When to rethink too much of a good thing

High density lipoprotein cholesterol (HDL-C) is a known contributor to atherosclerotic cardiovascular disease (ASCVD) risk when HDL-C <40 mg/dL in men and <50 mg/dL in women. There has been much interest in the potential cardioprotective properties of HDL-C, as it removes cholesterol from the periphery to the liver for exertion and holds inherent anti-thrombotic and anti-inflammatory properties. However, clinical trials raising HDL-C pharmacologically have not shown to improve cardiovascular outcomes. In fact, observational studies have demonstrated an increased risk of non-cardiovascular mortality and infection when HDL-C >90 mg/dL and >70 mg/dL in women and men, respectively. The ability for the HDL particle to effectively transport cholesterol from the periphery for excretion in bile is more complex than illustrated on a standard cholesterol panel. There is variability in its function, size, density, subclass, reverse cholesterol transport, and cholesterol efflux capacity, which impact the particles ability to effectively reduce cardiovascular disease (CVD) risk. Research has shown that HDL particles are prone to have a reduction in its efficacy in response to infection, auto-immune disease, menopause and cardiometabolic conditions during pregnancy. Additionally, recent studies have shown that low HDL-C may not adequately influence ASCVD risk in Black adults. The purpose of this contemporary review is to highlight the utility of using HDL-C in assessing CVD risk.

Antidyslipidemic Potential of Water-Soluble Polysaccharides of Ganoderma applanatum in MACAPOS-2-Induced Obese Rats

Increased consumption of high-calorie foods leads to obesity usually associated with metabolic disorders including diabetes, hyperglycemia, and dyslipidemia. Ganoderma applanatum is a nonedible mushroom traditionally used in West Cameroon for the treatment of many diseases including hypertension, diabetes, and hepatitis. This study was designed to investigate the antidyslipidemic potential of water-soluble polysaccharides of G. applanatum in MACAPOS-2- (maize, cassava, palm oil, and sugar) induced obese rats. For this purpose, obesity was induced on 6–8-week-old male Wistar rats with a local high-fat diet for four months. G. applanatum polysaccharides (GAPs) obtained by hot water extraction were orally administered to obese rats for two months at different dose levels (50, 100, and 150 mg/kg bodyweight), and its potential was investigated on food consumption, bodyweight gain, serum, and tissue lipids parameters. GAP extract increased the bodyweight gain by raising the food intake of obese rats. Furthermore, the administration of GAP extract at different dose levels significantly decreased the total cholesterol, triglyceride, low-density lipoprotein cholesterol levels, and the atherogenic index from 50 to 150 mg/kg bodyweight. Conversely, GAP extract improved the high-density lipoprotein cholesterol level in obese rats compared with untreated rats after two months' study period. These results indicated that GAP extract may be considered as a novel bioactive compound against dyslipidemia and its associated complications.

In vitro and in vivo anti-salmonella properties of hydroethanolic extract of Detarium microcarpum Guill. & Perr. (Leguminosae) root bark and LC-MS-based phytochemical analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Typhoid fever treatment remains a challenge in endemic countries. Detarium microcarpum is traditionally used to manage typhoid.

AIM OF THE STUDY

The study aims to explore the efficacy of hydroethanolic extract of Detarium microcarpum root bark in rats infected with salmonella.

MATERIAL AND METHODS

The phytochemical profile of the extract was obtained by UHPLC-MS analysis in an attempt of standardization. The in vitro antimicrobial activity was determined using broth dilution method. Salmonella infection was induced by oral administration of S. thyphimurium to immunosuppressed rats. Infected rats were then treated 2 h later with the extract (75, 150 and 300 mg/kg), distilled water (normal and salmonella control) and ciprofloxacin (8 mg/kg) for control. Body weight was monitored and stools were cultured to determine the number of colony-forming units. At the end of treatment, animals were sacrificed, blood and organs were collected for hematological, biochemical and histopathological analyses.

RESULTS

Detarium microcarpum extract as well as the isolated compound (rhinocerotinoic acid) exhibited good antimicrobial activity in vitro with bacteriostatic effects. The plant extract significantly (p < 0.05) inhibited the bacterial development in infected animals with an effective dose (ED₅₀) of 75 mg/kg. In addition, the extract prevented body weight loss, hematological, biochemical and histopathological damages in treated rats.

CONCLUSION

Detarium microcarpum extract possesses antisalmonella properties justifying its traditional use for the typhoid fever management.

The relationship between plasma lipids, oxidant-antioxidant status, and glycated proteins in individuals at risk for atherosclerosis

Objective: Ageing is one of the major risks for atherosclerosis. The age-related changes of interactions between plasma lipids, oxidative stress, antioxidant defense, and glycation processes are still not established while we age. Thus, the aim of the study was to analyze such relationships in individuals at risk for atherosclerosis due to their age.

Methods: Elderly and middle-aged persons with no acute disease or severe chronic disorder were assessed. Fasting plasma lipids (total cholesterol (T-C), high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol, and triacylglycerols), thiobarbituric acid reacting substances (TBARS), plasma total antioxidant status (TAS), and glucose and glycated proteins (fructosamine (FA) and glycated hemoglobin (HbA_1c)) were determined. An oral glucose tolerance test allowed exclusion of persons with type 2 diabetes.

Results: Lipid profiles were significantly profitable, increased HDL-C especially (p<0.0001), in the elderly versus middle-aged group. Decreased TBARS and TAS were found in the elderly versus middle-aged group (p=0.0001 and p=0.00002, respectively). Increased fructosamine was found in the elderly (255±30 μmol/L) versus middle-aged (236±33 μmol/L) group (p=0.006). Multiple regression analysis showed that in the middle-aged group TBARS correlated with T-C and HDL-C, and in the elderly group with HbA_1c and FA independently of other factors.

Conclusion: The factors which have an impact on oxidant–antioxidant status are crucial to understanding the pathomechanisms of senescence as well as the development of chronic diseases. Healthy aging may be maintained throughout proper lipid control. Moreover, data support the premise that the balance between lipid metabolism and oxidative stress may play a role in the initial phases of glycation plasma proteins particularly among elderly persons.

Tangier disease may cause early onset of atherosclerotic cerebral infarction: A case report

RATIONALE

The present study explored the relationship between the adenosine triphosphate (ATP)-binding cassette A1 (ABCA1) gene, atherosclerosis, and cerebral infarction. The diagnosis and treatment ideas of stroke caused by Tangier disease via the summary of the diagnosis and treatment process of one case with juvenile stroke were explored. The relevant literature on the clinical manifestations, laboratory examinations, and treatment of Tangier disease was reviewed.

PATIENT CONCERNS

The brain magnetic resonance imaging (MRI) of a juvenile man with acute onset of sudden right limb weakness and speechlessness revealed infarct lesions. The laboratory tests found low serum high-density lipoprotein (HDL), while further genetic testing identified ABCD1 gene mutation. The mother also carried the mutant gene.

DIAGNOSES

Tangier disease was diagnosed.

INTERVENTIONS

Statin treatment was administered for platelet aggregation.

OUTCOMES

After 3 years of follow-up, the patient was declared to be in a stable condition.

LESSONS

ABCA1 gene mutation caused early onset of atherosclerosis, leading to the occurrence of cerebral infarction. The cerebral infarction associated with reduced high-density lipoprotein (HDL), was under intensive focus with respect to ABCA1 gene. Child and Juvenile stroke patients with low HDL should not be excluded from the possibility of Tangier disease.

Using Zebrafish for High-Throughput Screening of Novel Cardiovascular Drugs

Cardiovascular diseases remain a major challenge for modern drug discovery. The diseases are chronic, complex, and the result of sophisticated interactions between genetics and environment involving multiple cell types and a host of systemic factors. The clinical events are often abrupt, and the diseases may be asymptomatic until a highly morbid event. Target selection is often based on limited information, and though highly specific agents are often identified in screening, their final efficacy is often compromised by unanticipated systemic responses, a narrow therapeutic index, or substantial toxicities. Our understanding of complexity of cardiovascular disease has grown dramatically over the past 2 decades, and the range of potential disease mechanisms now includes pathways previously thought only tangentially involved in cardiac or vascular disease. Despite these insights, the majority of active cardiovascular agents derive from a remarkably small number of classes of agents and target a very limited number of pathways. These agents have often been used initially for particular indications and then discovered serendipitously to have efficacy in other cardiac disorders or in a manner unrelated to their original mechanism of action. In this review, the rationale for in vivo screening is described, and the utility of the zebrafish for this approach and for complementary work in functional genomics is discussed. Current limitations of the model in this setting and the need for careful validation in new disease areas are also described. An overview is provided of the complex mechanisms underlying most clinical cardiovascular diseases, and insight is offered into the limits of single downstream pathways as drug targets. The zebrafish is introduced as a model organism, in particular for cardiovascular biology. Potential approaches to overcoming the hurdles to drug discovery in the face of complex biology are discussed, including in vivo screening of zebrafish genetic disease models.

Predictive and Prognostic Value of High-density Lipoprotein Cholesterol in Young Male Patients with Acute Myocardial Infarction

Background:

The level of high-density lipoprotein cholesterol (HDL-C) is an important risk indicator and used in risk factor counting and quantitative risk assessment; however, the effect of HDL-C in young male patients with acute myocardial infarction (AMI) is unclear. The aim of this study was to investigate the effect of HDL-C in young male patients.

Methods:

We recruited 267 consecutive young male patients (≤44 years) diagnosed with AMI. Other 247 participants free from coronary heart disease were enrolled as controls. HDL-C levels of AMI patients and controls were evaluated to analyze the predictive value on AMI. According to the cutoff point of 1.04 mmol/L HDL-C, patients of AMI were divided into two subgroups (normal HDL-C group and low HDL-C group) and were followed up for 2 years. Clinical end points included all major adverse coronary events (MACEs): the main cause of death, nonfatal myocardial infarction, readmissions for acute coronary syndrome, arrhythmias, or revascularization. The prognostic value of HDL-C was evaluated using Cox regression according to MACE.

Results:

Patients of AMI had decreased proportion in normal HDL-C group compared to controls (47.2% vs. 57.9%; P = 0.017). Logistic regression analysis showed that there was an inverse relationship between HDL-C and AMI in young males. In the low HDL-C subgroup of AMI patients (n = 141), 34 (24.1%) patients experienced a MACE during the 2-year follow-up, compared with 15 (11.9%) patients in normal HDL-C subgroup (n = 126). The Cox regression analysis showed that HDL-C was an independent predictor of a MACE during the follow-up period (hazard ratio = 0.354, P = 0.006).

Conclusion:

HDL-C was an important parameter for predicting the risk and the clinical outcomes of AMI in young male patients.

Dan-Qi prescription ameliorates insulin resistance through overall corrective regulation of glucose and fat metabolism

ETHNOPHARMACOLOGICAL RELEVANCE

Danshen and Sanqi Prescription (Dan-Qi) is commonly used to treat cardiovascular diseases (CVD) in China. Since Danshen and Sanqi are reported to ameliorate lipid metabolism disorders at treatment of cardiovascular diseases. Meanwhile, it is reported that co-administration of Danshen and Sanqi exhibited significant pharmacokinetic herb-herb interactions. We reasoned that Danshen and Sanqi combination could be potentially function synergistically in treating diet induced insulin resistance.

MATERIALS AND METHODS

Using high calori food induced Drosophila and mice models, we assessed Danshen and Sanqi treatment for their anti-diabetic effects.

RESULTS

The combination of Danshen and Sanqi (Dan-Qi) effectively improved fat and glucose metabolism of the high-sugar and high-fat diet fed fruit flies. More importantly, Dan-Qi significantly ameliorated hyperlipidemia and hyperglycemia phenotype caused in high-fat diet induced obesity (DIO) mouse model. The Dan-Qi treated DIO mice showed lower fasting insulin, triglycerides, total and low-density lipoprotein cholesterol (LDL-C) levels in plasma, much better than Danshen or Sanqi treated alone. It was shown that Dan-Qi prescription reduced fat accumulation in the liver with Sanqi playing the major role. Interestingly, it was not Danshen or Sanqi alone, but the combination markedly increased glycogen deposition in mice liver. Quantitative RT-PCR showed Dan-Qi increased liver glycogen synthesis gene like Glut-1, GK, and Glut-4, reduced fat and cholesterol anabolism genes such as SREBP-1c, ACC, ATP-CL, ACS. Meanwhilpose tissues and muscle tissues, the glucose and fat metabolism genes are changed accordingly to pro-catabolism status. Notably, endogenous plasma metabolites of Dan-Qi treated mice displayed much better overral rectifying effects than the Danshen or Sanqi alone.

CONCLUSIONS

Our data demonstrated that Danshen and Sanqi combination exerted significant anti-diabetic efficacy, and Dan-Qi prescription could be potentially considered as a therapeutic application in diabetes.

Beta-Glucan-Rich Extract from Pleurotus sajor-caju (Fr.) Singer Prevents Obesity and Oxidative Stress in C57BL/6J Mice Fed on a High-Fat Diet

Mushrooms have been used in folk medicine for thousands of years. In this study, the effect of β-glucan-rich extract of P. sajor-caju (GE) on lipid lowering and antioxidant potential was assessed in C57BL/6J mice fed on a high-fat diet. Obesity was induced in C57BL/6J mice by feeding a high-fat diet. The control groups in this study were ND (for normal diet) and HFD (for high-fat diet). The treated groups were ND240 (for normal diet) (240 mg/kg b.w) and HFD60, HFD120, and HFD240 (for high-fat diet), where the mice were administrated with three dosages of GE (60, 120, and 240 mg GE/kg b.w). Metformin (2 mg/kg b.w) served as positive control. GE-treated groups showed significantly reduced body weight, serum lipid, and liver enzymes levels. GE also attenuated protein carbonyl and lipid hydroperoxide levels by increasing the enzymic antioxidants (SOD, CAT, and GPx) activities in the mice. GE-treated groups induced the expression of hormone sensitive lipase (HSL) and adipose triglyceride lipase (ATGL) while downregulated the expression of peroxisome proliferator-activated receptor gamma (PPAR-γ), sterol regulatory binding protein-1c (SREBP-1c), and lipoprotein lipase (LPL). Hence, GE prevented weight gain in the mice by inducing lipolysis and may be valuable in the formulation of adjuvant therapy for obesity.

Emerging LDL therapies: Using human genetics to discover new therapeutic targets for plasma lipids

In humans, genetic variation occurs through different types of alleles that vary in frequency and severity of effect. Mendelian mutations, such as those in the low-density lipoprotein (LDL) receptor (LDLR) that result in familial hypercholesterolemia, are rare and have powerful phenotypic effects. Conversely, alleles that are common in the population (such that homozygotes for the minor allele are present even in modest sample sizes) typically have very modest phenotypic effects. In the middle of the spectrum are "Goldilocks" alleles such as mutations in the gene for proprotein convertase subtilisin/kexin type 9 (PCSK9). Loss-of-function mutations in PCSK9 result in significantly decreased LDL-cholesterol levels and a disproportionately large reduction in coronary heart disease risk by reducing the exposure to LDL-cholesterol throughout life. Several agents to inhibit PCSK9 are currently in development, demonstrating the potential utility of translating genetics into clinical therapeutics. To date, most investigations aimed at identifying the genes responsible for hypercholesterolemia have used linkage analysis, which requires samples collected from multiple families with defects in the same gene, or common variant analysis which requires thousands of samples from the population. However, case studies have shown that with advances in whole genome sequencing or exome sequencing (targeted exome capture), the process of discovering causal genetic mutations can be significantly streamlined. Astute clinical observation of individual patients and their families with atypical lipid profiles, followed by sequencing of the affected individual, has the potential to lead to important findings regarding the genetic mutations that cause lipid abnormalities.

The effects of fenofibrate on inflammation and cardiovascular markers in patients with active rheumatoid arthritis: a pilot study

Peroxisome proliferator-activated receptors α (PPARα) agonists, or fibrates, are used in the treatment for dyslipidemia. Experimental data suggest that fibrates have anti-inflammatory properties, and PPARα is essential for the differentiation of endothelial progenitor cells (EPC) which diminished pool in rheumatoid arthritis (RA) contributes to accelerated atherosclerosis. The data on fibrates' effects in patients with RA are limited. The aim of this study was to investigate changes in disease activity, inflammatory markers, lipid profile, and circulating EPC in active RA patients treated with fenofibrate. Twenty-seven patients with active RA taking traditional disease-modifying antirheumatic drugs (DMARDs) were prescribed fenofibrate (145 mg/day) for 3 months. All patients received background traditional DMARDs in stable doses. The outcomes measured were clinical disease activity variables, circulating cytokines, adipokines, lipids, and EPC. Twenty-five patients completed the study. At the end of treatment, there was a significant reduction in DAS28, all individual DAS28 components except tender joint count, the duration of morning stiffness, and in the patient's assessment of disease activity. Fifteen (60 %) patients achieved good/moderate EULAR response, while 10 (40 %) patients satisfied ACR20 response criteria. Treatment with fenofibrate resulted in significant decrease in CRP and IL-6 concentrations and improvement in lipid profile. There was no change in the concentrations of circulating EPC. In conclusion, fenofibrate treatment is associated with reduced inflammation and improved lipid profile in RA patients. Large randomized controlled studies are needed to confirm these results and to define the role of fibrates in the treatment for RA.

Reduced exposure evaluation of an Electrically Heated Cigarette Smoking System. Part 7: A one-month, randomized, ambulatory, controlled clinical study in Poland

This randomized, open-label, ambulatory, controlled clinical study investigated biomarkers associated with cardiovascular risk and biomarkers of exposure to 10 selected harmful and potentially harmful constituents (HPHC) in cigarette smoke in 316 male and female Polish smokers. Subjects were randomized to continue smoking conventional cigarettes (CC; N=79) or switch to smoking the Electrically Heated Cigarette Smoking System series-K cigarette (EHCSS-K6; N=237). Biomarker assessments were performed at several time points during the study at baseline and during the 1-month investigational period. The primary biomarkers were high-sensitivity C-reactive protein and white blood cell counts. No statistically significant differences in the two primary biomarkers were found between the study groups at the end of the study. End-of-study comparisons of secondary biomarkers between study groups indicated an increase in high-density lipoprotein cholesterol, and reductions in red blood cell count, hemoglobin, and hematocrit levels in the EHCSS-K6 group. All biomarkers of exposure to cigarette smoke HPHC were decreased in the EHCSS-K6 group, despite an increase in cigarette consumption, compared to the CC group. There were no apparent differences in any of the safety assessment parameters between the groups, and the overall incidence of study-related adverse events was low.

The impact of a disease management program (COACH) on the attainment of better cardiovascular risk control in dyslipidaemic patients at primary care centres (The DISSEMINATE Study): a randomised controlled trial

BACKGROUND

To evaluate the efficacy of Counselling and Advisory Care for Health (COACH) programme in managing dyslipidaemia among primary care practices in Malaysia. This open-label, parallel, randomised controlled trial compared the COACH programme delivered by primary care physicians alone (PCP arm) and primary care physicians assisted by nurse educators (PCP-NE arm).

METHODS

This was a multi-centre, open label, randomised trial of a disease management programme (COACH) among dyslipidaemic patients in 21 Malaysia primary care practices. The participating centres enrolled 297 treatment naïve subjects who had the primary diagnosis of dyslipidaemia; 149 were randomised to the COACH programme delivered by primary care physicians assisted by nurse educators (PCP-NE) and 148 to care provided by primary care physicians (PCP) alone. The primary efficacy endpoint was the mean percentage change from baseline LDL-C at week 24 between the 2 study arms. Secondary endpoints included mean percentage change from baseline of lipid profile (TC, LDL-C, HDL-C, TG, TC: HDL ratio), Framingham Cardiovascular Health Risk Score and absolute risk change from baseline in blood pressure parameters at week 24. The study also assessed the sustainability of programme efficacy at week 36.

RESULTS

Both study arms demonstrated improvement in LDL-C from baseline. The least squares (LS) mean change from baseline LDL-C were -30.09% and -27.54% for PCP-NE and PCP respectively. The difference in mean change between groups was 2.55% (p=0.288), with a greater change seen in the PCP-NE arm. Similar observations were made between the study groups in relation to total cholesterol change at week 24. Significant difference in percentage change from baseline of HDL-C were observed between the PCP-NE and PCP groups, 3.01%, 95% CI 0.12-5.90, p=0.041, at week 24. There was no significant difference in lipid outcomes between 2 study groups at week 36 (12 weeks after the programme had ended).

CONCLUSION

Patients who received coaching and advice from primary care physicians (with or without the assistance by nurse educators) showed improvement in LDL-cholesterol. Disease management services delivered by PCP-NE demonstrated a trend towards add-on improvements in cholesterol control compared to care delivered by physicians alone; however, the improvements were not maintained when the services were withdrawn.

TRIAL REGISTRATION

National Medical Research Registration (NMRR) Number: NMRR-08-287-1442Trial Registration Number (ClinicalTrials.gov Identifier): NCT00708370.

Low HDL-C predicts risk and PCI outcomes in the Han Chinese population

BACKGROUND

High-density lipoprotein cholesterol (HDL-C) can predict the occurrence and prognosis of coronary heart disease (CHD) in the Western population; however, the role of HDL-C in Chinese populations is unclear. Thus, we investigated the predictive value of HDL-C on the risk and clinical outcomes of CHD in the Han Chinese population.

METHODS

In a case-control study, plasma HDL-C levels of CHD patients and controls were evaluated to analyse the diagnostic value of HDL-C on CHD. In a prospective cohort study, the predictive value of HDL-C on the development of major adverse cardiovascular events (MACE) was determined in CHD patients who underwent a percutaneous coronary intervention (PCI).

RESULTS

In the case-control study, HDL-C levels were significantly lower in patients with CHD (n = 375) compared to the controls (n = 328, P < 0.05). There were more male patients in the CHD group than in the control group. Logistic regression analysis showed that, relative to other lipid parameters, the relationship between HDL-C levels and CHD showed the strongest association. A stratified analysis showed that gender did not affect the relationship between HDL-C levels and CHD. The prospective cohort study found that in the low HDL-C subgroup of CHD patients (n = 249) who underwent PCI, 62 (24.9%) patients experienced a MACE during the 120-week follow-up period. However, only 15 (6.8%) patients experienced a MACE in the high HDL-C subgroup (n = 219; P < 0.05). Kaplan-Meier analysis revealed that the MACE rate and death rate were significantly higher in the low HDL-C subgroup than in their counterparts with high HDL-C levels (P < 0.05). The Cox regression analysis showed that HDL-C was an independent predictor of a MACE during the follow-up period (hazard ratio = 0.395, P = 0.005).

CONCLUSIONS

Low HDL-C was the most powerful lipid parameter for predicting the risk and the clinical outcome of CHD in the Han Chinese population.

High Density Lipoprotein and it's Dysfunction

Plasma high-density lipoprotein cholesterol(HDL-C) levels do not predict functionality and composition of high-density lipoprotein(HDL). Traditionally, keeping levels of low-density lipoprotein cholesterol(LDL-C) down and HDL-C up have been the goal of patients to prevent atherosclerosis that can lead to coronary vascular disease(CVD). People think about the HDL present in their cholesterol test, but not about its functional capability. Up to 65% of cardiovascular death cannot be prevented by putative LDL-C lowering agents. It well explains the strong interest in HDL increasing strategies. However, recent studies have questioned the good in using drugs to increase level of HDL. While raising HDL is a theoretically attractive target, the optimal approach remains uncertain. The attention has turned to the quality, rather than the quantity, of HDL-C. An alternative to elevations in HDL involves strategies to enhance HDL functionality. The situation poses an opportunity for clinical chemists to take the lead in the development and validation of such biomarkers. The best known function of HDL is the capacity to promote cellular cholesterol efflux from peripheral cells and deliver cholesterol to the liver for excretion, thereby playing a key role in reverse cholesterol transport (RCT). The functions of HDL that have recently attracted attention include anti-inflammatory and anti-oxidant activities. High antioxidant and anti-inflammatory activities of HDL are associated with protection from CVD.This review addresses the current state of knowledge regarding assays of HDL functions and their relationship to CVD. HDL as a therapeutic target is the new frontier with huge potential for positive public health implications.

HDL mimetics inhibit tumor development in both induced and spontaneous mouse models of colon cancer

Recent studies suggest that high-density lipoprotein (HDL) levels are inversely related to colon cancer risk. HDL mimetics constructed from a number of peptides and proteins with varying structures possess anti-inflammatory and antioxidant properties reminiscent of HDL. In this article, we examined whether HDL mimetics, L-4F (an apolipoprotein A-I mimetic peptide) and G* (an apolipoprotein J mimetic peptide) affect tumor growth and development in mouse models of colon cancer. HDL mimetics reduced viability and proliferation of CT26 cells, a mouse colon adenocarcinoma cell line, and decreased CT26 cell-mediated tumor burden in BALB/c mice when administered subcutaneously or orally. Plasma levels of lysophosphatidic acid (LPA), a serum biomarker for colon cancer, were significantly reduced in mice that received HDL mimetics, suggesting that binding and removal of proinflammatory lipids is a potential mechanism for the inhibition of tumor development by HDL mimetics. Furthermore, L-4F significantly reduced size and number of polyps in APC(min/+) mice, a mouse model for human familial adenomatous polyposis, suggesting that HDL mimetics are effective in inhibiting the development of both induced and spontaneous cancers of the colon. Our results, for the first time, identify HDL mimetics as a novel therapeutic strategy for the treatment of colon cancer.

Low high density lipoprotein cholesterol: prevalence and associated risk-factors in a large French population

PURPOSE

High density lipoprotein-cholesterol (HDL-C) is a strong predictor of cardiovascular risk. We investigated the distribution of HDL-C in a French general population according to age, sex, and the risk factors associated with low HDL-C values.

METHODS

A group of 18,483 men and 22,047 women 16-79 years of age were investigated during a medical check-up. Relevant parameters were studied in three groups according to age and gender-specific percentile classes (≤5th [HDL₅] median and >95th). Gender-specific logistic regression models selected variables associated with HDL₅.

RESULTS

Using the National Cholesterol Education Program Adult Treatment Panel III criteria (threshold: 40 mg/dL in men, 50 mg/dL in women) the prevalence of low HDL-C was 11.1% and 26.4% in men and women and it decreased with age. Mean HDL-C levels increased with age. HDL₅ was positively associated with a sedentary lifestyle and deprivation (p < 0.00001) even after adjustment on alcohol consumption and smoking. Abdominal obesity, smoking, hypertriglyceridemia, hyperleucocytosis, and low alcohol consumption were associated with HDL₅ for both genders.

CONCLUSIONS

The prevalence of low HDL-C was similar to that observed in other Europeans but lower than in the United States. HDL₅ was associated with cardiovascular risk factors, metabolic syndrome, and social deprivation. A prevention policy to increase HDL-C levels should focus on reducing smoking and abdominal obesity, particularly in deprived subjects.

The Scl1 of M41-type group A Streptococcus binds the high-density lipoprotein

Streptococcal collagen-like protein 1 (Scl1) is a virulence factor on the surface of group A Streptococcus (GAS). We have reported previously that several Scl1 proteins derived from various M-type GAS strains, including M41, can bind to low-density lipoprotein, but the Scl1 protein derived from the M6-type GAS strain cannot. Here, we demonstrated that recombinant protein, designated C176, derived from Scl1.41 of the GAS M41-type strain also binds both plasma and purified high-density lipoprotein (HDL). Next, we determined that the intact noncollagenous region of C176 was necessary and sufficient for HDL binding. C176-HDL interaction could be eliminated by the presence of low concentrations of the nonionic detergent, Tween 20, indicating the hydrophobic nature of this interaction. We finally showed that whole GAS cells expressing native Scl1.41 protein absorbed HDL from human plasma in the absence of Tween 20, but M6-type GAS cells did not. Altogether, our results add further evidence to the importance of GAS-lipoprotein binding.

The ectopic F(O)F(1) ATP synthase of rat liver is modulated in acute cholestasis by the inhibitor protein IF1

Rat liver plasma membranes contain F(O)F(1) complexes (ecto-F(O)F(1)) displaying a similar molecular weight to the mitochondrial F(O)F(1) ATP synthase, as evidenced by Blue Native PAGE. Their ATPase activity was stably reduced in short-term extra-hepatic cholestasis. Immunoblotting and immunoprecipitation analyses demonstrated that the reduction in activity was not due to a decreased expression of ecto-F(O)F(1) complexes, but to an increased level of an inhibitory protein, ecto-IF(1), bound to ecto-F(O)F(1). Since cholestasis down regulates the hepatic uptake of HDL-cholesterol, and ecto-F(O)F(1) has been shown to mediate SR-BI-independent hepatic uptake of HDL-cholesterol, these findings provide support to the hypothesis that ecto-F(O)F(1) contributes to the fine control of reverse cholesterol transport, in parallel with SR-BI. No activity change of the mitochondrial F(O)F(1) ATP synthase (m-F(O)F(1)), or any variation of its association with m-IF(1) was observed in cholestasis, indicating that ecto-IF(1) expression level is modulated independently from that of ecto-F(O)F(1), m-IF(1) and m-F(O)F(1).

Extracellular hydrophobic regions in scavenger receptor BI play a key role in mediating HDL-cholesterol transport

The binding of high density lipoprotein (HDL) to scavenger receptor BI (SR-BI) is responsible for whole-body cholesterol disposal via reverse cholesterol transport. The extracellular domain of SR-BI is required for HDL binding and selective uptake of HDL-cholesterol. We identified six highly hydrophobic regions in this domain that may be important for receptor activity and performed site-directed mutagenesis to investigate the importance of these regions in SR-BI-mediated cholesterol transport. Non-conservative mutation of the regions encompassing V67, L140/L142, V164 or V221 reduced hydrophobicity and impaired the ability of SR-BI to bind HDL, mediate selective uptake of HDL-cholesterol, promote cholesterol efflux, and enlarge the cholesterol oxidase-sensitive pool of membrane free cholesterol. In contrast, conservative mutations at V67, V164 or V221 did not affect the hydrophobicity or these cholesterol transport activities. We conclude that the hydrophobicity of N-terminal extracellular regions of SR-BI is critical for cholesterol transport, possibly by mediating receptor-ligand and/or receptor-membrane interactions.

Plasma Protein Biomarkers Correlated with the Development of Diet-Induced Type 2 Diabetes in Mice

INTRODUCTION: Early detection, assessment of disease progression, and application of an appropriate therapeutic intervention are all important for the care of patients with type 2 diabetes. Currently, however, there is no simple test for early detection of type 2 diabetes. Established diagnostic tests for the disease including oral glucose tolerance, fasting blood glucose, and hemoglobin A1c are relatively late markers where the disease has already progressed. Since blood is in direct contact with many tissues, we hypothesized that pathological tissue changes are likely to be reflected in proteomic profiles of plasma. METHODS: Mice were reared either on regular chow or a high-fat diet at weaning and several physiological responses (i.e., weight, fasting plasma glucose and insulin, and glucose tolerance) were monitored at regular time intervals. Plasma was collected at regular intervals for proteomic analysis by two-dimensional gel electrophoresis and subsequent mass spectrometry. RESULTS: Onset of hyperinsulinemia with corresponding glucose intolerance was observed in 2 weeks and fasting blood glucose levels rose significantly after 4 weeks on the high-fat diet. Many proteins were found to exist in multiple forms (isoforms). Levels of some isoforms including plasma retinol binding protein, transthyretin, Apolipoprotein A1, and kininogen showed significant changes as early as 4 weeks which coincided with the very early development of glucose intolerance. CONCLUSIONS: These results show that a proteomic approach to study the development of type 2 diabetes may uncover unknown early post-translationally modified diagnostic and/or therapeutic protein targets.

Update on statin-mediated anti-inflammatory activities in atherosclerosis

Anti-inflammatory activities of statins in atherosclerosis have been well documented by both basic research and clinical studies. Statins have been introduced in the 1980s as 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors to block cholesterol synthesis and lower cholesterol serum levels. In the last three decades, statins have been shown to possess several anti-inflammatory and antioxidant activities resulting in the beneficial reduction of atherosclerotic processes and cardiovascular risk in both humans and animal models. Inflammatory intracellular pathways involving kinase phosphorylation and protein prenylation are modulated by statins. The same intracellular mechanisms might also cause statin-induced myotoxicity. In the present review, we will update evidence on statin-mediated regulation of inflammatory pathways in atherogenesis.

Beta-glucans in the treatment of diabetes and associated cardiovascular risks

Diabetes mellitus is characterized by high blood glucose level with typical manifestations of thirst, polyuria, polydipsia, and weight loss. It is caused by defects in insulin-mediated signal pathways, resulting in decreased glucose transportation from blood into muscle and fat cells. The major risk is vascular injury leading to heart disease, which is accelerated by increased lipid levels and hypertension. Management of diabetes includes: control of blood glucose level and lipids; and reduction of hypertension. Dietary intake of beta-glucans has been shown to reduce all these risk factors to benefit the treatment of diabetes and associated complications. In addition, beta-glucans also promote wound healing and alleviate ischemic heart injury. However, the mechanisms behind the effect of beta-glucans on diabetes and associated complications need to be further studied using pure beta-glucan.

Clinical review: impact of statin substitution policies on patient outcomes

BACKGROUND

The increasing awareness of cost issues in health care has led to the increasing use of policy-driven substitution of branded for generic medications, particularly relative to statin treatment for cardiovascular diseases. While there are potential short-term health care savings, the consequences for primary care are under-researched. Our objective was to review data on intensive statin therapy and generic substitution in patients at high cardiovascular risk.

RESULTS

Current treatment guidelines for the prevention of cardiovascular disease are consistent in their recommendations regarding statin therapy and treatment targets. Clinical trials demonstrate that to reduce cardiovascular events, a statin is more effective than placebo, intensive statin therapy is more effective than moderate statin therapy in patients with established coronary disease, and in patients receiving intensive statin therapy the lowest risk is associated with the lowest low-density lipoprotein levels. However, in clinical practice, patients at high cardiovascular risk are prone to be undertreated. Observational studies suggest that mandatory statin substitution may increase the gap between achieved and recommended therapeutic targets.

CONCLUSIONS

Substitution of generic statins may be cost-saving, particularly at the primary prevention level. However, statin substitution policies have not been adequately studied on a population level. Data raise concern that mandated statin substitution may lead to unfavourable treatment choices at the level of the individual high-risk patient.