Elevated HDL is a risk factor for recurrent coronary events in a subgroup of non-diabetic postinfarction patients with hypercholesterolemia and inflammation

Associations between neighborhood socioeconomic deprivation, IFNγ, and high-density lipoprotein particle size: Data from the Washington, D.C. cardiovascular health and needs assessment

INTRODUCTION

Neighborhood socioeconomic deprivation is associated with increased cardiovascular risk factors, including inflammation. Inflammation plays an important role in modifying the cardioprotective function of high-density lipoprotein (HDL). Moreover, recent studies suggest that very high HDL is associated with adverse cardiovascular disease (CVD) outcomes. Thus, we sought to explore the relationships between neighborhood socioeconomic deprivation as a marker of chronic stress, inflammation, proprotein convertase subtilisin/kexin type 9 (PCSK9) (a core component of the HDL proteome), HDL characterisitcs, and biological aging as a predictor of CVD and all-cause mortality.

METHODS

Sixty African American subjects were recruited to the NIH Clinical Center as part of a community-based participatory research-designed observational study. Neighborhood deprivation index (NDI), a marker of neighborhood socioeconomic deprivation, was measured using US Census data. HDL characteristics (cholesterol, particle number, size, subspecies) were determined from NMR lipoprotein profiling, and plasma cytokines (IL-1β, IL-6, IL-8, TNFα, IFNγ) were measured using an ELISA-based multiplex technique. Epigenetic clock biomarkers of aging were measured using DNA methylation data obtained from participants' buffy coat samples. We used linear regression modeling adjusted for atherosclerotic cardiovascular disease (ASCVD) risk score, body mass index (BMI), and lipid-lowering medication use to investigate relationships of interest.

RESULTS

NDI directly associated with large HDL particle count (H7P) and IFNγ and trended toward significance with HDL-C and PCSK9. IFNγ and PCSK9 then directly associated with H7P. H7P also directly associated with higher DNA methylation phenotypic age (PhenoAge).

CONCLUSION

We highlight associations between neighborhood socioeconomic deprivation, IFNγ, PCSK9, HDL subspecies, and epigenetic biomarkers of aging. Taken together, our findings suggest indirect pathways linking neighborhood deprivation-related stress and inflammation to HDL and immune epigenetic changes. Moreover, these results add to recent work showing the pathogenicity of high HDL levels and underscore the need to understand how chronic stress-related inflammation and lipoprotein subspecies relate to CVD risk across diverse populations.

Inflammation Alters Relationship Between High-Density Lipoprotein Cholesterol and Cardiovascular Risk in Patients With Chronic Kidney Disease: Results From KNOW-CKD

Background

The function of high‐density lipoprotein can change from protective to proatherosclerotic under inflammatory conditions. Herein, we studied whether inflammation could modify the relationship between high‐density lipoprotein level and risk of adverse outcomes in patients with chronic kidney disease .

Methods and Results

In total, 1864 patients from the prospective KNOW‐CKD (Korean Cohort Study for Outcome in Patients With Chronic Kidney Disease) were enrolled. The main predictor was high‐density lipoprotein cholesterol (HDL‐C) level. Presence of inflammation was defined by hs‐CRP (high‐sensitivity C‐reactive protein) level of ≥1.0 mg/L. The primary outcome was extended major adverse cardiovascular events. During 9231.2 person‐years of follow‐up, overall incidence of the primary outcome was 15.8 per 1000 person‐years. In multivariable Cox analysis after adjusting for confounders, HDL‐C level was not associated with the primary outcome. There was a significant interaction between the inflammatory status and HDL‐C for risk of extended major adverse cardiovascular events (P=0.003). In patients without inflammation, the hazard ratios (HRs) (95% CIs) for HDL‐C levels <40, 50 to 59, and ≥60 mg/dL were 1.10 (0.50–1.82), 0.95 (0.50–1.82), and 0.42 (0.19–0.95), respectively, compared with HDL‐C of 40 to 49 mg/dL. However, the significant association for HDL‐C ≥60 mg/dL was not seen after Bonferroni correction. In patients with inflammation, we observed a trend toward increased risk of extended major adverse cardiovascular events in higher HDL‐C groups (HRs [95% CIs], 0.73 [0.37–1.43], 1.24 [0.59–2.61], and 1.56 [0.71–3.45], respectively), but without statistical significance.

Conclusions

The association between HDL‐C level and adverse cardiovascular outcomes showed reverse trends based on inflammation status in Korean patients with chronic kidney disease.

Registration

URL: https://www.clinicaltrials.gov; Unique identifier: NCT01630486.

Association Between Serum High-Density Lipoprotein Cholesterol Levels and Progression of Chronic Kidney Disease: Results From the KNOW-CKD

Background High-density lipoprotein cholesterol ( HDL -C) levels are generally decreased in patients with chronic kidney disease ( CKD ). However, studies on the relationship between HDL -C and CKD progression are scarce. Methods and Results We studied the association between serum HDL -C levels and the risk of CKD progression in 2168 participants of the KNOW - CKD (Korean Cohort Study for Outcome in Patients With Chronic Kidney Disease). The primary outcome was the composite of a 50% decline in estimated glomerular filtration rate from baseline or end-stage renal disease. The secondary outcome was the onset of end-stage renal disease. During a median follow-up of 3.1 (interquartile range, 1.6-4.5) years, the primary outcome occurred in 335 patients (15.5%). In a fully adjusted Cox model, the lowest category with HDL -C of <30 mg/dL (hazard ratio, 2.21; 95% CI, 1.30-3.77) and the highest category with HDL -C of ≥60 mg/dL (hazard ratio, 2.05; 95% CI , 1.35-3.10) were associated with a significantly higher risk of the composite renal outcome, compared with the reference category with HDL -C of 50 to 59 mg/dL. This association remained unaltered in a time-varying Cox analysis. In addition, a fully adjusted cubic spline model with HDL -C being treated as a continuous variable yielded similar results. Furthermore, consistent findings were obtained in a secondary outcome analysis for the development of end-stage renal disease. Conclusions A U-shaped association was observed between serum HDL -C levels and adverse renal outcomes in this large cohort of patients with CKD . Our findings suggest that both low and high serum HDL -C levels may be detrimental to patients with nondialysis CKD .

Inflammatory markers modify the risk of recurrent coronary events associated with apolipoprotein A-I in postinfarction patients

BACKGROUND

Laboratory findings have suggested that systemic and vascular inflammation can impair the antiatherogenic function of high-density lipoproteins (HDLs). However, evidence from population studies is sparse.

OBJECTIVE

The objective of the study was to assess if blood inflammatory markers modify the risk of recurrent coronary events associated with apolipoprotein A-I (apoA-I) and HDL cholesterol (HDL-C) among postinfarction patients.

METHODS

ApoA-I, HDL-C, and inflammatory markers (C-reactive protein [CRP], serum amyloid A (SAA), fibrinogen, von Willebrand factor [vWF], and D-dimer) were measured from blood samples of 1028 patients drawn 2 months after an index myocardial infarction (MI). Patients were followed up for the composite coronary endpoint (nonfatal MI, coronary death, or unstable angina) for an average of 26 months. Cox proportional hazard models were used to assess effect modifications for the association of apoA-I and HDL-C with coronary risk by each inflammatory marker.

RESULTS

CRP significantly modified the risk of recurrent coronary events associated with apoA-I. Among the entire population, multivariable-adjusted hazard ratios associated with each standard deviation increase in apoA-I for those with low and high CRP levels were 0.89 and 1.35, respectively (P value for interaction = .008). vWF was a significant effect modifier of the apoA-I/coronary risk association only among diabetic patients (hazard ratios were 0.56 and 1.43, for diabetic patients with low and high vWF levels, respectively; P value for interaction = .002). No effect modification was observed for the HDL-C/coronary risk association.

CONCLUSION

Among stable post-MI patients, CRP modified the risk of recurrent coronary events associated with apoA-I. VWF modified this association only among the diabetic subgroup.

Hepatic aberrant glycosylation by N-acetylglucosaminyltransferase V accelerates HDL assembly

Glycosylation is involved in various pathophysiological conditions. N-Acetylglucosaminyltransferase V (GnT-V), catalyzing β1-6 branching in asparagine-linked oligosaccharides, is one of the most important glycosyltransferases involved in cancer and the immune system. Recent findings indicate that aberrant N-glycan structure can modify lipid metabolism. In this study, we investigated the effects of aberrant glycosylation by GnT-V on high-density lipoprotein cholesterol (HDL) assembly. We used GnT-V transgenic (Tg) mice and GnT-V Hep3B cell (human hepatoma cell line) transfectants. The study also included 96 patients who underwent medical health check-ups. Total serum cholesterol levels, particularly HDL-cholesterol (HDL-C) levels, were significantly increased in Tg vs. wild-type (WT) mice. Hepatic expression of apolipoprotein AI (ApoAI) and ATP-binding cassette subfamily A member 1 (ABCA1), two important factors in HDL assembly, were higher in Tg mice compared with WT mice. ApoAI and ABCA1 were also significantly elevated in GnT-V transfectants compared with mock-transfected cells. Moreover, ApoAI protein in the cultured media of GnT-V transfectants was significantly increased. Finally, we found a strong correlation between serum GnT-V activity and HDL-C concentration in human subjects. Multivariate logistic analyses demonstrated that GnT-V activity was an independent and significant determinant for serum HDL-C levels even adjusted with age and gender differences. Further analyses represented that serum GnT-V activity had strong correlation especially with the large-size HDL particle concentration. These findings indicate that enhanced hepatic GnT-V activity accelerated HDL assembly and could be a novel mechanism for HDL synthesis.

Low levels of high-density lipoprotein cholesterol increase the risk of incident kidney disease and its progression

Available experimental evidence suggests a role for high-density lipoprotein cholesterol (HDL-C) in incident chronic kidney disease (CKD) and its progression. However, clinical studies are inconsistent. We therefore built a cohort of 1,943,682 male US veterans and used survival models to examine the association between HDL-C and risks of incident CKD or CKD progression (doubling of serum creatinine, eGFR decline of 30% or more), or a composite outcome of ESRD, dialysis, or renal transplantation. Models were adjusted for demographics, comorbid conditions, eGFR, body mass index, lipid parameters, and statin use over a median follow-up of 9 years. Compared to those with HDL-C of 40 mg/dl or more, low HDL-C (under 30 mg/dl) was associated with increased risk of incident eGFR under 60 ml/min/1.73 m(2) (hazard ratio: 1.18; confidence interval: 1.17-1.19) and risk of incident CKD (1.20; 1.18-1.22). Adjusted models demonstrate an association between low HDL-C and doubling of serum creatinine (1.14; 1.12-1.15), eGFR decline of 30% or more (1.13; 1.12-1.14), and the composite renal end point (1.08; 1.06-1.11). Cubic spline analyses of the relationship between HDL-C levels and renal outcomes showed a U-shaped relationship, where risk was increased in lowest and highest deciles of HDL-C. Thus, a significant association exists between low HDL-C levels and risks of incident CKD and CKD progression. Further studies are needed to explain the increased risk of adverse renal outcomes in patients with high HDL-C.

HDL Cholesterol Efflux Predicts Graft Failure in Renal Transplant Recipients

High-density lipoprotein (HDL) particles are involved in the protection against cardiovascular disease by promoting cholesterol efflux, in which accumulated cholesterol is removed from macrophage foam cells. We investigated whether HDL cholesterol efflux capacity is associated with cardiovascular mortality, all-cause mortality, and graft failure in a cohort of renal transplant recipients (n=495, median follow-up 7.0 years). Cholesterol efflux capacity at baseline was quantified using incubation of human macrophage foam cells with apolipoprotein B-depleted plasma. Baseline efflux capacity was not different in deceased patients and survivors (P=0.60 or P=0.50 for cardiovascular or all-cause mortality, respectively), whereas recipients developing graft failure had lower efflux capacity than those with functioning grafts (P<0.001). Kaplan-Meier analysis demonstrated a lower risk for graft failure (P=0.004) but not cardiovascular (P=0.30) or all-cause mortality (P=0.31) with increasing gender-stratified tertiles of efflux capacity. Cox regression analyses adjusted for age and gender showed that efflux capacity was not associated with cardiovascular mortality (hazard ratio [HR], 0.89; 95% confidence interval [95% CI], 0.67 to 1.19; P=0.43). Furthermore, the association between efflux capacity and all-cause mortality (HR, .79; 95% CI, 0.63 to 0.98; P=0.031) disappeared after further adjustment for potential confounders. However, efflux capacity at baseline significantly predicted graft failure (HR, 0.43; 95% CI, 0.29 to 0.64; P<0.001) independent of apolipoprotein A-I, HDL cholesterol, or creatinine clearance. In conclusion, this prospective study shows that cholesterol efflux capacity from macrophage foam cells is not associated with cardiovascular or all-cause mortality but is a strong predictor of graft failure independent of plasma HDL cholesterol levels in renal transplant recipients.

Cross Sectional and Longitudinal Associations between Cardiovascular Risk Factors and Age Related Macular Degeneration in the EPIC-Norfolk Eye Study

Purpose

To examine the cross sectional and longitudinal relationship between cardiovascular risk factors and age-related macular degeneration (AMD) in a large British cohort study.

Methods

The EPIC Norfolk Eye study is nested in a larger prospective cohort study. Data on cardiovascular risk factors were collected at baseline (1993-1997) and follow up (2006-2011) via clinical examination, validated lifestyle questionnaires and serum blood samples. AMD was ascertained using standardised grading of fundus photographs at the follow up. Logistic regression was used to examine associations between baseline and follow up risk factors with AMD.

Results

5,344 pairs (62.0% of total 8623) of fundus photographs were of sufficient quality for grading of AMD in participants with mean age of 67.4 years old (range 44-91) at diagnosis. There were 28 cases of late AMD (0.5%, 95% confidence interval (CI)=0.3-0.8%) and 645 cases of early AMD (12.1%, 95%CI=11.2-13.0.%). In multivariable analysis, older people with higher levels of baseline high density lipoprotein- cholesterol (HDL-C ) and C-reactive protein (CRP) were more likely to have any signs of AMD, after adjusting for sex, education, smoking, and systolic blood pressure. In cross sectional analysis, only older age and higher HDL were significantly associated with AMD.

Conclusions

We have found that older age and higher levels of CRP and HDL-C were associated with increased odds of AMD in this population in the longitudinal analysis, but older age and HDL-C, not CRP was significantly associated with AMD in the cross sectional analysis. The prevalence of AMD in this cohort was low compared to other cohorts in Europe, the US and Australia, and probably reflects the some selection biases in follow up participation as well as the low rate of smoking among our healthy participants.

Residual Cardiovascular Risk in Chronic Kidney Disease: Role of High-density Lipoprotein

Although reducing low-density lipoprotein-cholesterol (LDL-C) levels with lipid-lowering agents (statins) decreases cardiovascular disease (CVD) risk, a substantial residual risk (up to 70% of baseline) remains after treatment in most patient populations. High-density lipoprotein (HDL) is a potential contributor to residual risk, and low HDL-cholesterol (HDL-C) is an established risk factor for CVD. However, in contrast to conventional lipid-lowering therapies, recent studies show that pharmacologic increases in HDL-C levels do not bring about clinical benefits. These observations have given rise to the concept of dysfunctional HDL where increases in serum HDL-C may not be beneficial because HDL loss of function is not corrected by or even intensified by the therapy. Chronic kidney disease (CKD) increases CVD risk, and patients whose CKD progresses to end-stage renal disease (ESRD) requiring dialysis are at the highest CVD risk of any patient type studied. The ESRD population is also unique in its lack of significant benefit from standard lipid-lowering interventions. Recent studies indicate that HDL-C levels do not predict CVD in the CKD population. Moreover, CKD profoundly alters metabolism and composition of HDL particles and impairs their protective effects on functions such as cellular cholesterol efflux, endothelial protection, and control of inflammation and oxidation. Thus, CKD-induced perturbations in HDL may contribute to the excess CVD in CKD patients. Understanding the mechanisms of vascular protection in renal disease can present new therapeutic targets for intervention in this population.

HDL and atherothrombotic vascular disease

High-density lipoproteins (HDLs) exert many beneficial effects which may help to protect against the development or progression of atherosclerosis or even facilitate lesion regression. These activities include promoting cellular cholesterol efflux, protecting low-density lipoproteins (LDLs) from modification, preserving endothelial function, as well as anti-inflammatory and antithrombotic effects. However, questions remain about the relative importance of these activities for atheroprotection. Furthermore, the many molecules (both lipids and proteins) associated with HDLs exert both distinct and overlapping activities, which may be compromised by inflammatory conditions, resulting in either loss of function or even gain of dysfunction. This complexity of HDL functionality has so far precluded elucidation of distinct structure-function relationships for HDL or its components. A better understanding of HDL metabolism and structure-function relationships is therefore crucial to exploit HDLs and its associated components and cellular pathways as potential targets for anti-atherosclerotic therapies and diagnostic markers.

Elevated high-density lipoprotein cholesterol and cardiovascular mortality in maintenance hemodialysis patients

BACKGROUND

High-density lipoprotein (HDL) confers protection against atherosclerosis by several different mechanisms. Although in the general population, increasing levels of HDL are associated with reduced cardiovascular (CV) mortality, this association is not well known in patients with chronic disease states such as end-stage renal disease. We hypothesize that the association of serum HDL concentration and its ratio to total cholesterol with all-cause and CV mortality in hemodialysis patients is different from the general population.

METHODS

A 3-year (July 2004 to June 2007) cohort of 33 109 chronic hemodialysis patients was studied in the USA in the dialysis clinics where lipid profile was measured in at least 50% of all outpatients of the clinic during a given calendar quarter. Cox proportional hazard models were adjusted for demographics and case-mix variables and cubic splines were plotted.

RESULTS

Higher HDL concentrations up to 50 mg/dL were associated with better overall survival, while HDL at 60 mg/dL and above was associated with a rise in all-cause and CV mortality. All-cause and CV mortality hazard ratio was 1.28 (1.20-1.38) and 1.08 (1.01-1.16) for HDL <30 mg/dL and 1.05 (1.00-1.10) and 1.08 (1.00-1.16) for HDL ≥ 60 mg/dL, respectively (reference: HDL: 30-<60 mg/dL).

CONCLUSIONS

In contrast to the general population, low total cholesterol to HDL ratio was associated with higher mortality in hemodialysis patients. A U-shaped association between HDL cholesterol level and all-cause and CV mortality exists in hemodialysis patients with HDL between 50 and <60 mg/dL exhibiting the best survival. The underlying mechanisms responsible for these seemingly paradoxical associations await further investigation.

Disease-associated marked hyperalphalipoproteinemia

Marked hyperalphalipoproteinemia (HAL) is a heterogeneous syndrome. To clarify the pathophysiological significance of HAL, we compared clinical profiles between marked HAL subjects with and without cholesteryl ester transfer protein (CETP) deficiency. CETP deficiency was associated with cardiovascular diseases and strokes in the HAL population, particularly in female. HAL women without CETP deficiency tended to have higher prevalence with cancer history. HAL may not always be a longevity marker, but be sometimes accompanied with pathological conditions.

High-density lipoprotein cholesterol, high-sensitivity C-reactive protein, and cardiovascular disease in United States adults

High-density lipoprotein (HDL) cholesterol is inversely associated with the risk of cardiovascular disease (CVD). However, whether the protective effect of HDL becomes impaired by elevated high-sensitivity C-reactive protein (hs-CRP) is not well-established. We evaluated 13,572 United States adults aged ≥18 years who participated in the cross-sectional National Health and Nutrition Examination Survey 1999-2008. The subjects were classified according to the recognized cutpoints of HDL cholesterol elevations of ≥60 mg/dl, hs-CRP of >3 mg/L, and by a history of self-reported coronary heart disease (CHD) or CVD. Multivariate logistic regression analysis was used to assess the odds of prevalent CHD and CVD according to HDL cholesterol/hs-CRP group, after adjusting for known risk factors. Those with HDL cholesterol of ≥60 mg/dl and CRP >3 mg/L versus HDL cholesterol <60 mg/dl and CRP ≤3 mg/L had as high or a greater prevalence of CHD (5.5% and 5.3%, respectively) and CVD (8.6% and 6.9%, respectively). Compared to those with HDL cholesterol of ≥60 mg/dl and CRP ≤3 mg/L, those with HDL cholesterol ≥60 mg/dl and hs-CRP >3 mg/L had a 1.38 (95% confidence interval 0.94 to 2.02) adjusted odds of CHD and 1.38 (95% confidence interval 1.00 to 1.90) adjusted odds of CVD. Those with an HDL cholesterol <60 mg/dl and CRP >3 mg/L had the greatest adjusted odds of both CHD (1.75, 95% confidence interval 1.28 to 2.38) and CVD (1.74, 95% confidence interval 1.33 to 2.28). In conclusion, an hs-CRP >3 mg/L in the presence of HDL cholesterol of ≥60 mg/dl is associated with an attenuation in the protective association of HDL cholesterol ≥60 mg/dl and CRP of ≤3 mg/L with CHD and CVD.

Reactive Oxygen Species, SUMOylation, and Endothelial Inflammation

Although the exact mechanism through which NADPH oxidases (Nox's) generate reactive oxygen species (ROS) is still not completely understood, it is widely considered that ROS accumulation is the cause of oxidative stress in endothelial cells. Increasing pieces of evidence strongly indicate the role for ROS in endothelial inflammation and dysfunction and subsequent development of atherosclerotic plaques, which are causes of various pathological cardiac events. An overview for a causative relationship between ROS and endothelial inflammation will be provided in this review. Particularly, a crucial role for specific protein SUMOylation in endothelial inflammation will be presented. Given that SUMOylation of specific proteins leads to increased endothelial inflammation, targeting specific SUMOylated proteins may be an elegant, effective strategy to control inflammation. In addition, the involvement of ROS production in increasing the risk of recurrent coronary events in a sub-group of non-diabetic, post-infarction patients with elevated levels of HDL-cholesterol will be presented with the emphasis that elevated HDL-cholesterol under certain inflammatory conditions can lead to increased incidence of cardiovascular events.

Increased LCAT activity and hyperglycaemia decrease the antioxidative functionality of HDL

BACKGROUND

Type 2 diabetes mellitus increases the risk of atherosclerotic cardiovascular disease. Antioxidative properties of high density lipoprotein (HDL) are important for atheroprotection. This study investigated whether the antioxidative functionality of HDL is altered in type 2 diabetes mellitus and aimed to identify potential determinants of this parameter.

MATERIALS AND METHODS

In a cross-sectional study, we investigated 74 patients with type 2 diabetes and 75 control subjects. Antioxidative properties of HDL were measured and expressed as either (i) HDL antioxidative capacity or (ii) HDL antioxidation index after multiplying HDL antioxidative capacity results with individual plasma HDL cholesterol concentrations. Lecithin:cholesterol acyltransferase (LCAT) and paraoxonase-1 (PON-1) activities were determined.

RESULTS

HDL antioxidative capacity was similar in patients with diabetes and controls, while the HDL antioxidation index was decreased in patients with diabetes (P = 0.005) owing to lower plasma HDL cholesterol (P < 0.001). LCAT activity was higher and PON-1 activity lower in type 2 diabetes mellitus (each P < 0.001). In the combined subjects, HDL antioxidative capacity was inversely related to LCAT activity (P < 0.01). The HDL antioxidation index correlated negatively with blood glucose (P < 0.001), HbA1c and LCAT activity (each P < 0.01), and positively with PON-1 activity (P < 0.01). Multiple linear regression analysis demonstrated that high LCAT activity was associated with both decreased HDL antioxidation capacity (P < 0.05) and index (P < 0.001) independent of diabetes status, glycaemic control and PON-1.

CONCLUSIONS

Overall, the antioxidative functionality of HDL is impaired in type 2 diabetes mellitus mostly because of lower HDL cholesterol. Hyperglycaemia, increased LCAT activity and lower PON-1 activity likely contribute to impaired antioxidative functionality of HDL.

Metabolic syndrome: nature, therapeutic solutions and options

INTRODUCTION

Metabolic syndrome (MetS) defines the clustering in an individual of multiple metabolic abnormalities, based on central obesity and insulin resistance. In addition to its five components, prothrombotic and proinflammatory states are essential features. The significance of MetS lies in its close association with the risk of type 2 diabetes and cardiovascular disease (CVD). This field being an evolving one necessitated the current review.

AREAS COVERED

The areas covered in this review include the so far unproven concept that enhanced low-grade inflammation often leads to dysfunction of the anti-inflammatory and atheroprotective properties of apolipoprotein A-I (apoA-I) and HDL particles, which further increases the risk of diabetes and CVD. It was emphasized that lifestyle modification is essential in the prevention and management of MetS, which includes maintenance of optimal weight by caloric restriction, adherence to a diet that minimizes postprandial glucose and triglyceride fluctuations, restricting alcohol consumption, smoking cessation and engaging in regular exercise. Drug therapy should target the dyslipoproteinemia and the often associated hypertension or dysglycemia.Statins are the drugs of first choice, to be initiated in patients with MetS at high 10-year cardiovascular risk. Such treatment is inadequate if fasting serum triglycerides remain at > 150 mg/dl, when niacin should be combined. Fibrates, omega 3 fatty acids, metformin, angiotensin-converting enzyme inhibitors and pioglitazone are additional options in drug therapy.

EXPERT OPINION

Research on MetS in subpopulations prone to impaired glucose tolerance and insulin resistance has indicated that proinflammatory state and oxidative stress are often prominently involved in MetS, to the extent that evidence of impaired function of HDL and apo A-I particles is discernible by biological evidence of functional defectiveness via outcomes studies and/or correlations with inflammatory and anti-inflammatory biomarkers. A sex difference has been clear in this development.

HDL and cardiovascular disease: atherogenic and atheroprotective mechanisms

The lipoprotein HDL has two important roles: first, it promotes reverse cholesterol transport, and second, it modulates inflammation. Epidemiological studies show that HDL-cholesterol levels are inversely correlated with the risk of cardiovascular events. However, many patients who experience a clinical event have normal, or even high, levels of HDL cholesterol. Measuring HDL-cholesterol levels provides information about the size of the HDL pool, but does not predict HDL composition or function. The main component of HDL, apolipoprotein A-I (apo A-I), is largely responsible for reverse cholesterol transport through the macrophage ATP-binding cassette transporter ABCA1. Apo A-I can be damaged by oxidative mechanisms, which render the protein less able to promote cholesterol efflux. HDL also contains a number of other proteins that are affected by the oxidative environment of the acute-phase response. Modification of the protein components of HDL can convert it from an anti-inflammatory to a proinflammatory particle. Small peptides that mimic some of the properties of apo A-I have been shown in preclinical models to improve HDL function and reduce atherosclerosis without altering HDL-cholesterol levels. Robust assays to evaluate the function of HDL are needed to supplement the measurement of HDL-cholesterol levels in the clinic.

Inflammation reduces HDL protection against primary cardiac risk

BACKGROUND

We recently reported high high-density lipoprotein (HDL) cholesterol as a predictor of recurrent risk in a subgroup of postinfarction patients defined by hypercholesterolemia and high C-reactive protein (CRP) levels. We investigated whether a similar high-risk subgroup might exist for incident cardiovascular disease.

MATERIAL AND METHODS

A graphical exploratory data analysis tool was used to identify high-risk subgroups in a male population-based cohort (n = 3405) from the prevention of renal and vascular end-stage disease study by generating 3-dimensional mappings of risk over the HDL-cholesterol/CRP domain with subsequent use of Kaplan-Meier analysis to verify high-risk. Within-subgroup risk was assessed using Cox proportional hazards regression and Kaplan-Meier analysis.

RESULTS

Mappings revealed two high-risk subgroups: a low HDL-cholesterol/high CRP subgroup and a high HDL-cholesterol/high CRP subgroup. The low HDL-cholesterol subgroup demonstrated a pattern of metabolic syndrome dyslipidemia contrasted with a predominantly unremarkable biomarker pattern for the high HDL-cholesterol subgroup. However, in the high HDL-cholesterol subgroup, CRP levels were higher than the low HDL-cholesterol subgroup; and within the high HDL-cholesterol subgroup, CRP predicted risk. Moreover, in the high HDL-cholesterol subgroup, risk was associated with lower triglyceride levels in conjunction with presumptively larger HDL particles.

CONCLUSIONS

High HDL-cholesterol and high CRP levels define a subgroup of men at high-risk for incident cardiovascular disease. High HDL cholesterol-associated risk likely relates to impaired HDL particle remodelling in the setting of inflammation. This approach may facilitate identification of additional inflammation-related mechanisms underlying high HDL cholesterol-associated risk; and potentially influence management of such patients.

Cholesteryl ester transfer protein polymorphism (TaqIB) associates with risk in postinfarction patients with high C-reactive protein and high-density lipoprotein cholesterol levels

OBJECTIVE

To investigate the roles of inflammation and a cholesteryl ester transfer protein (CETP) polymorphism potentially related to recent findings demonstrating coronary risk with increasing high-density lipoprotein cholesterol (HDL-C) level.

METHODS AND RESULTS

A novel graphical exploratory data analysis tool allowed the examination of coronary risk in postinfarction patients relating to HDL-C and C-reactive protein levels. Results demonstrated a high-risk subgroup, defined by high HDL-C and C-reactive protein levels, exhibiting larger HDL particles and lower lipoprotein-associated phospholipaseA(2) levels than lower-risk patients. Subgroup CETP-associated risk was probed using a functional CETP polymorphism (TaqIB, rs708272). In the high-risk subgroup, multivariable modeling revealed greater risk for B2 allele carriers (less CETP activity) versus B1 homozygotes (hazard ratio, 2.41; 95% CI, 1.04 to 5.60; P=0.04). Within the high-risk subgroup, B2 allele carriers had higher serum amyloid A levels than B1 homozygotes. Evidence also demonstrates that CETP genotypic differences in HDL subfraction distributions regarding non-HDL-C and lipoprotein-associated phospholipaseA(2) may potentially relate to impaired HDL remodeling.

CONCLUSIONS

Postinfarction patients with high HDL-C and C-reactive protein levels demonstrate increased risk for recurrent events. Future studies should aim at characterizing altered HDL particles from such patients and at elucidating the mechanistic details related to inflammation and HDL particle remodeling. Such patients should be considered in drug trials involving an increase in HDL-C level.

Prospective studies on the relationship between high-density lipoprotein cholesterol and cardiovascular risk: a systematic review

Epidemiological studies have extensively evaluated the association between high-density lipoprotein cholesterol (HDL-C) and cardiovascular disease (CVD) risk. The objective of this systematic review was to enumerate the number of original prospective studies that showed a significant association between HDL-C and CVD risk and provided evidence of the consistency of this association across other lipid risk factors. A systematic MEDLINE literature search identified 53 prospective cohort and five nested case-control studies that provided multivariate assessments of the association between HDL-C and CVD risk. Among these 58 prospective studies, 31 studies found a significant inverse association between HDL-C and CVD risk for all CVD outcomes and subpopulations studied, whereas 17 studies found a significant association for some CVD outcomes and/or subpopulations assessed. The ratio of studies that found a significant association out of the total studies identified was similar across all CVD outcomes, although there was less evidence for stroke and atherosclerotic outcomes. Only seven studies tested for the consistency of this association across other lipid risk factors, of which six studies suggested that the association was consistent across other lipid levels. In conclusion, the association between HDL-C and CVD risk is significant and strong, although further evidence may be needed to establish whether this association is consistent across other lipid risk factors. Furthermore, uncertainties remain regarding the mechanism in which HDL-C exerts its effects, suggesting a need for further research focused on new methods for reliable measurement.

Apolipoprotein A-I versus HDL cholesterol in the prediction of risk for myocardial infarction and stroke

PURPOSE OF REVIEW

To compare the potential of high-density lipoprotein (HDL) cholesterol and apolipoprotein (apo) A-I, the major protein in HDL particles, in predicting cardiovascular risk. Pros and cons for using these risk markers are discussed.

RECENT FINDINGS

Both HDL cholesterol and apoA-I are in most clinical conditions antiatherogenic - the higher the values, the lower the cardiovascular risk. Methodological and physiological factors speak in favour of using apoA-I rather than HDL cholesterol as a marker of risk. In prospective risk studies and in lipid-lowering trials it has been shown that the apoB/A-I ratio, which reflects the cholesterol balance between all potentially atherogenic (apoB) and antiatherogenic lipoproteins (apoA-I), is a better risk marker than low-density lipoprotein cholesterol, HDL cholesterol and lipid ratios in predicting cardiovascular risk and response to lipid lowering induced by statins. Practical advantages speak in favour of using apoB and apoA-I - fasting is not needed to analyze and interpret the values of apoB and apoA-I.

SUMMARY

New guidelines should be developed in which target values for apoB and apoA-I are defined to enable the use of these new strong risk markers/factors in clinical practice.

Plasminogen activator inhibitor-1 polymorphism (4G/5G) predicts recurrence in nonhyperlipidemic postinfarction patients

OBJECTIVE

Nonhyperlipidemic postinfarction patients are at high risk for recurrent coronary events by virtue of incident myocardial infarction (MI); however, few studies assess risk beyond incident MI. The aim of this study was to assess such risk as a function of 37 atherosclerosis-associated genetic polymorphisms and 17 blood marker variables.

METHODS AND RESULTS

Screening of polymorphisms in nonhyperlipidemic postinfarction patients revealed significant risk only for the 4G/5G insertion/deletion polymorphism in the promoter of the plasminogen-activator inhibitor-1 (PAI-1) gene. Outcome event mapping, an exploratory data analysis tool, was then applied to define a subgroup (182 patients from total study population of 846 nondiabetic patients) exhibiting maximal functional dependence of risk on the PAI-1 polymorphism. Cox multivariable regression analyses within the subgroup adjusted for significant clinical covariates and medication use as a function of the PAI-1 polymorphism and 17 atherosclerosis-associated blood markers revealed significant risk for patients homozygous for the 4G allele (hazard ratio 4.30, 95% CI 1.98 to 9.33, P=0.00023), and lack of significant risk-association with any blood marker.

CONCLUSIONS

In a subgroup of normolipidemic postinfarction patients, only the PAI-1 4G/5G polymorphism was associated with recurrent risk from a set of atherosclerosis-associated genetic polymorphisms and blood markers.

Inflammatory and anti-inflammatory variable clusters and risk prediction in acute coronary syndrome patients: A factor analysis approach

BACKGROUND

Numerous inflammatory mediators such as C-reactive protein (CRP), fibrinogen, interleukin-18 (IL-18), and inter-cellular adhesion molecule-1 (ICAM-1) have been proposed for risk stratification in acute coronary syndrome (ACS) patients. However, interactions between these markers have made it difficult to assess their true role in risk prediction. Factor analysis is a multivariable statistical technique that reduces a large number of intercorrelated variables to a smaller set of independent clusters, underlining physiological relationships. The aim of this study was to investigate, using factor analysis, a clustering of pro-inflammatory markers, anti-inflammatory cytokines such as interleukin-10 (IL-10) and HDL cholesterol, and to determine their role in prediction of risk of recurrent coronary events in ACS patients.

METHODS

We assessed 320 consecutive patients (236 men; 67 years; IQ 58-74 years) admitted with ACS. The composite of cardiac death and re-hospitalization with non-fatal myocardial infarction, or unstable angina, was the pre-specified study end-point. Serum CRP, fibrinogen, HDL cholesterol, IL-10, IL-18 and ICAM-1 levels were measured at study entry. We assessed independent predictors of the combined end-point during a 1-year follow-up using multiple logistic regression analysis.

RESULTS

Factor analysis identified three clusters which were arbitrarily interpreted as (1) a "systemic inflammation" cluster with positive loadings of CRP and fibrinogen, (2) a "local inflammation-endothelial dysfunction" cluster with positive loadings of IL-18 and ICAM-1 and (3) an "anti-inflammation" cluster comprising IL-10 and HDL cholesterol. Only the "anti-inflammation" cluster was a significant predictor (OR 0.66, 95% CI: 0.49-0.89) of adverse cardiac events during a 1-year follow-up and remained significant (OR 0.65, 95% CI: 0.48-0.88) in a multivariate model that included all three factors.

CONCLUSIONS

Although inflammatory markers such as CRP predict future cardiovascular events in ACS patients, when all inflammatory mediators are taken into account in a prospective analysis of risk, markers reflecting anti-inflammatory mechanisms are better prognostic markers.

NAD(P)H oxidase polymorphism (C242T) and high HDL cholesterol associate with recurrent coronary events in postinfarction patients

We recently identified a subgroup of postinfarction patients at high-risk for recurrent coronary events defined by inflammation (high C-reactive protein) (CRP) and hypercholesterolemia. Within this subgroup, only elevated high-density lipoprotein cholesterol (HDL-C) from a set of metabolic, inflammatory and thrombogenic blood markers was associated with additional risk. To investigate the role of oxidative stress in this high-risk subgroup, we examined effects on risk of a polymorphism known to affect functional activity of NAD(P)H oxidase, an oxidative enzyme associated with generation of reactive oxygen species. The study population comprised non-diabetic patients of thrombogenic factors and recurrent coronary events (THROMBO) postinfarction study having complete blood marker and genotyping results (N=663) for C242T polymorphism of p22phox subunit (T allele associated with decreased activity). Cox multivariable regression, adjusted for significant clinical covariates, was used to assess within-subgroup risk associated with blood markers and polymorphism. In addition to elevated HDL-C (hazard ratio, 95% CI and p-value; 2.62, 1.05-6.55 and 0.039), significant independent risk was found for C242T (CC versus CT plus TT: 3.14, 1.34-7.35 and 0.0084). We conclude that oxidative stress plays a significant role in establishment of risk for recurrent coronary events in a high-risk subgroup of postinfarction patients defined by inflammation and hypercholesterolemia.