Genetic variation in Fc gamma receptor IIa and risk of coronary heart disease: negative results from two large independent populations

Low testosterone concentrations and prediction of future heart failure in men and in women: evidence from the large FINRISK97 study

Aims

The increased incidence of heart failure in men suggests that endogenous sex hormones might play a role in the development of heart failure, but epidemiological data remain sparse. Here, we evaluated the predictive value of low testosterone levels on future heart failure in the large population‐based FINRISK97 study.

Methods and results

Baseline serum testosterone concentrations were measured in 7855 subjects (3865 men and 3990 women) of the FINRISK97 study. During a median follow‐up (FU) of 13.8 years, a total of 564 heart failure events were recorded. The age‐adjusted baseline testosterone levels did not differ significantly between subjects developing incident heart failure during FU and those without incident events during FU (men: 16.6 vs. 17.1 nmol/L, P = 0.75; women: 1.15 vs. 1.17 nmol/L, P = 0.32). Relevant statistically significant correlations of testosterone levels were found with high‐density lipoprotein cholesterol levels (R = 0.22; P < 0.001), body mass index (R = −0.23; P < 0.001), and waist‐to‐hip ratio (R = −0.21; P < 0.001) in men, while statistically significant correlations in women were negligible in effect size. In sex‐stratified Cox regression analyses, taking age into account, a quite strong association between low testosterone and incident heart failure was found in men [hazard ratio (HR) 1.51 (95% confidence interval, CI: 1.09–2.10); P = 0.020 for lowest vs. highest quarter], but not in women [HR 0.70 (95% CI: 0.49–0.98); P = 0.086 for lowest vs. highest quarter]. Nevertheless, this association turned non‐significant after full adjustment including body mass index and waist‐to‐hip ratio, and testosterone levels were no longer predictive for incident heart failure—neither in men [HR 0.99 (95% CI: 0.70–1.42); P = 0.77 for lowest vs. highest quarter] nor in women [HR 0.92 (95% CI: 0.64–1.33); P = 0.99 for lowest vs. highest quarter]. Accordingly, Kaplan–Meier analyses did not reveal significant association of testosterone levels with heart failure.

Conclusions

Low levels of testosterone do not independently predict future heart failure.

Plasma protein expression profiles, cardiovascular disease, and religious struggles among South Asians in the MASALA study

Blood protein concentrations are clinically useful, predictive biomarkers of cardiovascular disease (CVD). Despite a higher burden of CVD among U.S. South Asians, no CVD-related proteomics study has been conducted in this sub-population. The aim of this study is to investigate the associations between plasma protein levels and CVD incidence, and to assess the potential influence of religiosity/spirituality (R/S) on significant protein-CVD associations, in South Asians from the MASALA Study. We used a nested case–control design of 50 participants with incident CVD and 50 sex- and age-matched controls. Plasma samples were analyzed by SOMAscan for expression of 1305 proteins. Multivariable logistic regression models and model selection using Akaike Information Criteria were performed on the proteins and clinical covariates, with further effect modification analyses conducted to assess the influence of R/S measures on significant associations between proteins and incident CVD events. We identified 36 proteins that were significantly expressed differentially among CVD cases compared to matched controls. These proteins are involved in immune cell recruitment, atherosclerosis, endothelial cell differentiation, and vascularization. A final multivariable model found three proteins (Contactin-5 [CNTN5], Low affinity immunoglobulin gamma Fc region receptor II-a [FCGR2A], and Complement factor B [CFB]) associated with incident CVD after adjustment for diabetes (AUC = 0.82). Religious struggles that exacerbate the adverse impact of stressful life events, significantly modified the effect of Contactin-5 and Complement factor B on risk of CVD. Our research is this first assessment of the relationship between protein concentrations and risk of CVD in a South Asian sample. Further research is needed to understand patterns of proteomic profiles across diverse ethnic communities, and the influence of resources for resiliency on proteomic signatures and ultimately, risk of CVD.

Iron Metabolism Contributes to Prognosis in Coronary Artery Disease: Prognostic Value of the Soluble Transferrin Receptor Within the AtheroGene Study

Background

Coronary heart disease is a leading cause of mortality worldwide. Iron deficiency, a frequent comorbidity of coronary heart disease, causes an increased expression of transferrin receptor and soluble transferrin receptor levels (sTfR) levels, while iron repletion returns sTfR levels to the normal physiological range. Recently, sTfR levels were proposed as a potential new marker of iron metabolism in cardiovascular diseases. Therefore, we aimed to evaluate the prognostic value of circulating sTfR levels in a large cohort of patients with coronary heart disease.

Methods and Results

The disease cohort comprised 3423 subjects who had angiographically documented coronary heart disease and who participated in the AtheroGene study. Serum levels of sTfR were determined at baseline using an automated immunoassay (Roche Cobas Integra 400). Two main outcomes were considered: a combined end point of myocardial infarction and cardiovascular death and cardiovascular death alone. During a median follow‐up of 4.0 years, 10.3% of the patients experienced an end point. In Cox regression analyses for sTfR levels, the hazard ratio (HR) for future cardiovascular death and/or myocardial infarction was 1.27 (95% CI, 1.11–1.44, P<0.001) after adjustment for sex and age. This association remained significant (HR, 1.23; 95% CI, 1.03–1.46, P=0.02) after additional adjustment for body mass index, smoking status, hypertension, diabetes mellitus, dyslipidemia, C‐reactive protein, and surrogates of cardiac function, size of myocardial necrosis (hs‐Tnl), and hemoglobin levels.

Conclusions

In this large cohort study, sTfR levels were strongly associated with future myocardial infarction and cardiovascular death. This implicates a role for sTfR in secondary cardiovascular risk prediction.

Predictive value of low testosterone concentrations regarding coronary heart disease and mortality in men and women - evidence from the FINRISK97 study

INTRODUCTION

The relevance of low testosterone concentrations for incident coronary heart disease (CHD) and mortality has been discussed in various studies. Here, we evaluate the predictive value of low baseline testosterone levels in a large population-based cohort.

METHODS

We measured the serum levels of testosterone in 7671 subjects (3710 male, 3961 female) of the population-based FINRISK97 study.

RESULTS

The median follow-up (FU) was 13.8 years. During the FU, a total of 779 deaths from any cause, and 395 incident CHD events were recorded. The age-adjusted baseline testosterone levels were similar in subjects suffering incident events during FU and those without incident events during FU (men: 15.80 vs. 17.01 nmol L-1 ; P = 0.69, women: 1.14 vs. 1.15 nmol L-1 ; P = 0.92). Weak correlations of testosterone levels were found with smoking (R = 0.09; P < 0.001), HDL cholesterol levels (R = 0.22, P < 0.001), systolic blood pressure (R = -0.05; P = 0.011), BMI (R = -0.23; P < 0.001) and waist-hip-ratio (R = -0.21; P < 0.001) in men, and with eGFR (R = -0.05; P = 0.009) in women. Kaplan-Meier analyses did not reveal a positive association of testosterone levels with incident CHD or mortality. Accordingly, also in Cox regression analyses, testosterone levels were not predictive for incident CHD or mortality - neither in men (HR 1.02 [95%CI: 0.70-1.51]; P = 0.79 for lowest versus highest quarter regarding CHD and HR 1.06 [95%CI: 0.80-1.39]; P = 0.67 regarding mortality), nor in women (HR 1.13 [95%CI: 0.69-1.85]; P = 0.56 for lowest versus highest quarter regarding CHD and HR 0.99 [95%CI: 0.71-1.39]; P = 0.80 regarding mortality).

CONCLUSIONS

Low levels of testosterone are not predictive regarding future CHD or mortality - neither in men, nor in women.

Intrinsic Iron Release Is Associated with Lower Mortality in Patients with Stable Coronary Artery Disease-First Report on the Prospective Relevance of Intrinsic Iron Release

Intrinsic iron release is discussed to have favorable effects in coronary artery disease (CAD). The aim of this study was to evaluate the prognostic relevance of intrinsic iron release in patients with CAD. Intrinsic iron release was based on a definition including hepcidin and soluble transferrin receptor (sTfR). In a cohort of 811 patients with angiographically documented CAD levels of hepcidin and sTfR were measured at baseline. Systemic body iron release was defined as low levels of hepcidin (<24 ng/mL) and high levels of sTfR (≥2 mg/L). A commercially available ELISA (DRG) was used for measurements of serum hepcidin. Serum sTfR was determined by using an automated immunoassay (). Cardiovascular mortality was the main outcome measure. The criteria of intrinsic iron release were fulfilled in 32.6% of all patients. Significantly lower cardiovascular mortality rates were observed in CAD patients with systemic iron release. After adjustment for body mass index, smoking status, hypertension, diabetes, dyslipidemia, sex, and age, the hazard ratio for future cardiovascular death was 0.41. After an additional adjustment for surrogates of the size of myocardial necrosis (troponin I), anemia (hemoglobin), and cardiac function and heart failure severity (N-terminal pro B-type natriuretic peptide), this association did not change (Hazard ratio 0.37 (95% confidence interval 0.14⁻0.99), p = 0.047). In conclusion, significantly lower cardiovascular mortality rates were observed in CAD patients with intrinsic iron release shown during follow-up.

Biomarkers Related to Carotid Intima-Media Thickness and Plaques in Long-Term Survivors of Ischemic Stroke

Lifestyle risk factors, inflammation and genetics play a role in the development of atherosclerosis. We therefore studied Fc gamma receptor (FcγR) polymorphisms, interleukin (IL)-10 polymorphisms and other biomarkers related to carotid intima-media thickness (cIMT) in patients with ischemic stroke at a young age. Patients were evaluated 12 years after stroke occurrence. Patients (n = 232) 49 years of age or younger with an index stroke between 1988 and 1997 were retrospectively selected. Blood samples were taken at a first follow-up 6 years after the stroke. At a second follow-up, additional arterial events were registered for 140 patients, new blood samples were taken, and measurements of cIMT and blood pressure (BP) were performed. Unadjusted logistic regression analysis showed that cIMT ≥1 mm was associated with age, male gender, additional arterial events, BP, cholesterol, sedimentation rate, haemoglobin, triglycerides, creatinine, glycolysed haemoglobin (HbA1c) and FcγRIIIB-NaII/NaII. Adjusted backward stepwise logistic regression showed significance for age (odds ratio (OR) 1.13, 95 % confidence interval (CI) 1.04 to1.23, p = 0.003), male gender (OR 4.07, 95 % CI 1.15 to 14.5, p = 0.030), HbA1c (OR 6.65, 95 % CI 1.21 to 36.5, p = 0.029) and FcγRIIIB-NaII/NaII (OR 3.94, 95 % CI 1.08 to 14.3, p = 0.037). In this long-term follow-up study of patients with ischemic stroke at a young age, FcγRIIIB-NaII/NaII was identified as a possible contributing factor for cIMT ≥1 mm together with known risk factors, such as age, male gender, systolic BP, additional arterial events and HbA1c.

Fcγ receptors and ligands and cardiovascular disease

Fcγ receptors (FcγRs) classically modulate intracellular signaling on binding of the Fc region of IgG in immune response cells. How FcγR and their ligands affect cardiovascular health and disease has been interrogated recently in both preclinical and clinical studies. The stimulation of activating FcγR in endothelial cells, vascular smooth muscle cells, and monocytes/macrophages causes a variety of cellular responses that may contribute to vascular disease pathogenesis. Stimulation of the lone inhibitory FγcR, FcγRIIB, also has adverse consequences in endothelial cells, antagonizing NO production and reparative mechanisms. In preclinical disease models, activating FcγRs promote atherosclerosis, whereas FcγRIIB is protective, and activating FcγRs also enhance thrombotic and nonthrombotic vascular occlusion. The FcγR ligand C-reactive protein (CRP) has undergone intense study. Although in rodents CRP does not affect atherosclerosis, it causes hypertension and insulin resistance and worsens myocardial infarction. Massive data have accumulated indicating an association between increases in circulating CRP and coronary heart disease in humans. However, Mendelian randomization studies reveal that CRP is not likely a disease mediator. CRP genetics and hypertension warrant further investigation. To date, studies of genetic variants of activating FcγRs are insufficient to implicate the receptors in coronary heart disease pathogenesis in humans. However, a link between FcγRIIB and human hypertension may be emerging. Further knowledge of the vascular biology of FcγR and their ligands will potentially enhance our understanding of cardiovascular disorders, particularly in patients whose greater predisposition for disease is not explained by traditional risk factors, such as individuals with autoimmune disorders.

High-sensitivity C-reactive protein and atherosclerotic disease: from improved risk prediction to risk-guided therapy

There is compelling experimental and clinical evidence suggesting a crucial role for inflammation in the initiation and also the progression of atherosclerosis. Numerous biomarkers involved at various levels of the inflammation cascade have been shown to be associated with adverse cardiovascular outcomes. Yet, to date, it is not clear whether inflammation simply accompanies the atherosclerotic process or represents a major driver. Among all blood biomarkers, C-reactive protein (CRP), the classical acute phase reactant that can be measured with high-sensitivity (hs) assays seems to be the most promising candidate. It has already found its way into the guidelines in primary prevention. Hs-CRP can also be used to identify a high-risk group for recurrent events in patients with manifest atherosclerosis. Several post hoc analyses of large-scale randomized clinical trials testing various statins have indicated that, besides low density lipoprotein (LDL) cholesterol, hs-CRP levels might also further aid in tailoring statin treatment. The large JUPITER trial has prospectively confirmed these findings in primary prevention in patients with elevated hs-CRP but normal LDL cholesterol levels. Still, statin therapy is not a specific anti-inflammatory regime acting on the inflammation cascade. Thus, to directly test the inflammation hypothesis, a novel, more proximally located cytokine-based approach is needed. Canakinumab, a fully human monoclonal antibody against interleukin-1β, might represent a promising compound in this regard and provide a proof of concept. If successful, this may become a novel strategy to treat high-risk patients with stable atherosclerotic disease to prevent recurrent events on top of standard medical care.

Patients with unstable angina pectoris show an increased frequency of the Fc gamma RIIa R131 allele

Patients with Systemic Lupus Erythematosus (SLE) carry an increased risk for the development of coronary artery disease (CAD). The R131 allele of the Fc gamma receptor IIa (FcγRIIa) is associated with SLE incidence and disease severity but also with CAD. Compared to stable angina pectoris (SAP) the unstable angina (UAP), as a manifestation of destabilizing CAD, is associated with increased risk of persistent instability, myocardial infarction, and death. Identification of clinically relevant determinants for unstable angina promises reduction of UAP-associated mortality in patients with SLE. We conducted a clinical study among 553 consecutive patients with stable angina pectoris (n = 330) and unstable angina pectoris (n = 223). All patients were genotyped for a frequent functional variant at position 131 of the mature FcγRIIa. UAP, but not SAP was significantly associated with the R/R131 genotype (P < 0.001). In troponin-negative patients with angina carrying the R/R131 genotype the odds ratio for suffering from UAP was 4.02 (95% confidence interval, 2.52-6.41) compared to those with non-R/R131 genotypes. In a multivariable analysis, the R/R131 genotype independently predicted the risk for development of UAP in a model adjusted for classical atherogenic risk factors. Our data imply that risk stratification of SLE- and other high risk patients with troponin-negative angina could be significantly improved by FcγRIIa genotyping.

The role of Fcγ receptors in atherosclerosis

Atherosclerosis is widely considered to be an immune-mediated process. Fcγ receptors (Fcγ Rs) contribute to the regulation of a multitude of immune and inflammatory responses and are implicated in human atherosclerotic lesions. Major cell types involved in the pathogenesis of atherosclerosis express Fcγ Rs and their proatherogenic ligands such as immune complexes and C-reactive protein, which act to activate Fcγ R signaling pathways. This review summarizes recent significant progress addressing the multifaceted roles of Fcγ Rs in atherogenesis which comes from the studies of Fcγ R-deficient animal models, clinical investigations and in vitro molecular and cellular studies. These new findings help us appreciate the emerging role of Fcγ Rs in atherosclerosis, and suggest Fcγ Rs as a potential therapeutic target for atherosclerosis.

The Fcγ receptor IIA R131H gene polymorphism is associated with endothelial function in patients with hypercholesterolaemia

OBJECTIVE

A gene polymorphism substituting arginine (R) for histidine (H) at position 131 has been described within the Fcγ receptor IIa (FcγRIIa). The R allele is associated with increased binding of CRP and enhanced activation of monocytes. FcγRIIa is also expressed on endothelial cells, and we hypothesized this polymorphism would be associated with alterations of endothelial function.

METHODS

Genomic DNA was extracted and allele-specific PCR reactions were used to determine the FcγRIIa H131R polymorphism in 78 hypercholesterolaemic subjects. Using strain gauge plethysmography, forearm blood flow (FBF) responses were determined to intra-arterial infusion of acetylcholine (ACH), for endothelium-dependent vasodilatation (EDV), to nitroprusside (NP), for endothelium-independent vasodilatation (EIV), to NG-monomethyl-l-arginine (l-NMMA), for basal NO activity, and to ACH in the presence of l-NMMA, to assess the contribution of NO release to EDV.

RESULTS

Homozygous carriers of the H allele (n=30) had significantly better EDV than homozygous carriers of the R allele (n=15), while heterozygotes showed an intermediate phenotype (n=33) (e.g. % increase of FBF to ACH 48μg/min: 527±359% in H/H versus 452±262% in H/R versus 332±413% in R/R, p=0.0012 by 2-way ANOVA). EIV and basal NO activity were not affected by genotype, and co-infusion of l-NMMA abolished the differences in EDV.

CONCLUSIONS

The R allele of the FcγRIIa polymorphism is associated with impaired EDV and reduced NO activity during endothelial cell stimulation. These data suggest that the functional effects of the FcγRIIa H131R gene polymorphism previously observed in vitro translate into clinically relevant alterations of endothelial function in vivo.

Lipopolysaccharide-binding protein (LBP) is associated with total and cardiovascular mortality in individuals with or without stable coronary artery disease--results from the Ludwigshafen Risk and Cardiovascular Health Study (LURIC)

BACKGROUND

Atherosclerosis of coronary arteries is hallmarked by non-specific local inflammatory processes accompanied by a systemic response. Lipopolysaccharide-binding protein (LBP) has been suggested to be associated with coronary artery disease (CAD) in a previous study without follow-up.

PATIENTS AND METHODS

LBP plasma levels were measured in 2959 participants of the Ludwigshafen Risk and Cardiovascular Health (LURIC) cohort study referred to coronary angiography at baseline between 1997 and 2000. Median follow-up time was 8.0 years. Primary and secondary end points were cardiovascular and all-cause mortality, respectively. Multivariable adjusted logistic regression analyses were conducted to investigate the role of LBP.

RESULTS

Serum LBP concentration was significantly increased in 2298 patients with angiographically confirmed CAD compared to 661 individuals without coronary atherosclerosis (6.78 μg/mL (5.46-8.84) vs. 6.13 μg/mL (5.05-7.74), respectively; p<0.001). Moreover in multivariable logistic regression analyses, adjusted for established cardiovascular risk factors and markers of systemic inflammation, LBP was a significant and independent predictor of total and cardiovascular mortality (hazard ratio (HR) for all cause mortality: 1.43, 95% CI: 1.06-1.94, p=0.024; HR for cardiovascular mortality in the 4th quartile of LBP: 1.55, 95% CI: 1.06-2.27, p=0.025).

CONCLUSION

The present results add information on LBP in CAD. The data underscore the potential importance of innate immune mechanisms for atherosclerosis. Further studies are needed to clarify the pathways between innate immune system activation and atherosclerosis.

Platelet receptor polymorphisms do not influence Staphylococcus aureus-platelet interactions or infective endocarditis

Cardiac vegetations result from bacterium–platelet adherence, activation and aggregation, and are associated with increased morbidity and mortality in infective endocarditis. The GPIIb/IIIa and FcγRIIa platelet receptors play a central role in platelet adhesion, activation and aggregation induced by endocarditis pathogens such as Staphylococcus aureus, but the influence of known polymorphisms of these receptors on the pathogenesis of infective endocarditis is unknown. We determined the GPIIIa platelet antigen Pl^A1/A2 and FcγRIIa H131R genotype of healthy volunteers (n = 160) and patients with infective endocarditis (n = 40), and investigated the influence of these polymorphisms on clinical outcome in infective endocarditis and S. aureus–platelet interactions in vitro. Platelet receptor genotype did not correlate with development of infective endocarditis, vegetation characteristics on echocardiogram or the composite clinical end-point of embolism, heart failure, need for surgery or mortality (P > 0.05 for all), even though patients with the GPIIIa Pl^A1/A1 genotype had increased in vivo platelet activation (P = 0.001). Furthermore, neither GPIIIa Pl^A1/A2 nor FcγRIIa H131R genotype influenced S. aureus-induced platelet adhesion, activation or aggregation in vitro (P > 0.05). Taken together, our data suggest that the GPIIIa and FcγRIIa platelet receptor polymorphisms do not influence S. aureus–platelet interactions in vitro or the clinical course of infective endocarditis.

Neuronal thread protein regulation and interaction with microtubule-associated proteins in SH-Sy5y neuronal cells

In Alzheimer's disease (AD), neuronal thread protein (NTP) accumulates in cortical neurons and colocalizes with phospho- tau-immunoreactive cytoskeletal lesions that correlate with dementia. To generate additional information about the potential role of NTP in AD, we characterized its expression and regulation in human SH-Sy5y neuronal cells. Quantitative real-time reverse transcription-polymerase chain reactin and Western blot analysis demonstrated prominent insulin, moderate insulin-like growth factor, type 1 (IGF-1) and minimal nerve growth factor stimulation of NTP expression. In addition, NTP protein was more stable and it progressively accumulated in cells that were stimulated with insulin for 24 or 48 h. Metabolic labeling and phospho-amino acid analysis demonstrated phosphorylation of NTP on Serine residues, 30-60 min after insulin or IGF-1 stimulation, when glycogen synthase kinase 3beta (GSK-3beta) activity would no longer have been suppressed. Kinase inhibitor and in vitro phosphorylation studies demonstrated a role for GSK-3beta in the positive regulation of NTP expression and phosphorylation. Coimmunoprecipitation studies demonstrated physical interactions between NTP and tau or microtubule-associated protein 1b (MAP-1b), and ubiquitin immunoreactivity in NTP immunoprecipitates. In summary, these studies showed that (i) NTP expression is regulated at the level of transcription by insulin and IGF-1 stimulation; (ii) NTP is phosphorylated by GSK-3beta; (iii) NTP can physically interact with tau and MAP-1b and (iv) NTP-MAP complexes are ubiquitinated. The results suggest a functional role for NTP in relation to the turnover or processing of neuronal cytoskeletal proteins, attributes that may be modulated by insulin/IGF-1-mediated signaling.