High plasma concentrations of autoantibodies against native peptide 210 of apoB-100 are related to less coronary atherosclerosis and lower risk of myocardial infarction.

AIMS: We examined whether antibodies against peptides 45 and 210 of apoB-100 are related to myocardial infarction (MI) and severity of coronary atherosclerosis. METHODS AND RESULTS: Three hundred and eighty-seven survivors of a first MI (aged <60 years) and 387 sex- and age-matched controls were characterized in detail. IgG and IgM autoantibodies against native and malondialdehyde (MDA)-modified peptides 45 and 210 of apoB-100 (amino acids 661-680 and 3136-3155) were quantified in plasma and quantitative coronary angiography was performed in 243 patients. Post-infarction patients had significantly lower IgG against the native peptide 210 (IgG-p210(nat)) and higher IgM against the MDA-modified peptide 210 (IgM-p210(MDA)) compared with controls, whereas no differences were found for other antibodies. Plasma concentrations of IgG-p210(nat), but not IgM-p210(MDA), were independently and inversely related to the degree of coronary atherosclerosis in patients. In multiple logistic regression analysis (including established risk indicators), MI risk was 0.55 (95%CI: 0.37-0.81) for individuals in the IgG-p210(nat) upper quartile compared with the remaining individuals. CONCLUSION: Circulating IgG antibodies against the native peptide 210 of apoB-100 are inversely related to the severity of coronary atherosclerosis and associated with lower risk of MI. Epitope 210 of apoB-100 emerges as a target for immunization against atherosclerosis in humans.

A high-fat meal is accompanied by increased plasma interleukin-6 concentrations.

BACKGROUND AND AIM: Enhanced and prolonged postprandial lipaemia is associated with coronary heart disease (CHD). However, the mechanisms linking postprandial lipaemia to the increased risk of atherosclerosis and CHD remain to be determined. The aim of the present study was to examine the effects of a high-fat meal on plasma levels of the pro-inflammatory cytokine interleukin-6 (IL-6) and cellular adhesion molecules in CHD patients and control subjects. METHODS AND RESULTS: Forty-one middle-aged men with premature CHD and 26 healthy male controls were investigated. The plasma triglyceride response to the high-fat meal was significantly greater among cases than controls. The oral fat load induced a twofold increase in plasma concentrations of IL-6, an increase that was similar in CHD patients and control subjects. No changes could be detected in plasma concentrations of cellular adhesion molecules in response to postprandial lipaemia in either CHD patients or control subjects. CONCLUSION: The results of the present study suggest that a high-fat meal affects mechanisms that induce increased inflammatory activity, which is recognised as a key modulator in the development of atherosclerosis and CHD. However, the increased levels of plasma IL-6 appear not to be determined by the magnitude of the postprandial triglyceridaemia.

Epistatic and pleiotropic effects of polymorphisms in the fibrinogen and coagulation factor XIII genes on plasma fibrinogen concentration, fibrin gel structure and risk of myocardial infarction.

An intricate interplay between the genes encoding fibrinogen gamma (FGG), alpha (FGA) and beta (FGB), coagulation factor XIII (F13A1) and interleukin 6 (IL6) and environmental factors is likely to influence plasma fibrinogen concentration, fibrin clot structure and risk of myocardial infarction (MI). In the present study, the potential contribution of SNPs harboured in the fibrinogen, IL6 and F13A1 genes to these biochemical and clinical phenotypes was examined. A database and biobank based on 387 survivors of a first MI and population-based controls were used. Sixty controls were selected according to FGG 9340T > C [rs1049636] genotype for studies on fibrin clot structure using the liquid permeation method. The multifactor dimensionality reduction method was used for interaction analyses. We here report that the FGA 2224G > A [rs2070011] SNP (9.2%), plasma fibrinogen concentration (13.1%) and age (8.1%) appeared as independent determinants of fibrin gel porosity. The FGA 2224G > A SNP modulated the relation between plasma fibrinogen concentration and fibrin clot porosity. The FGG-FGA*4 haplotype, composed of the minor FGG 9340C and FGA 2224A alleles, had similar effects, supporting its reported protective role in relation to MI. Significant epistasis on plasma fibrinogen concentration was detected between the FGA 2224G > A and F13A1 Val34Leu [rs5985] SNPs (p < 0.001). The FGG 9340T > C and FGB 1038G > A [rs1800791] SNPs appeared to interact on MI risk, explaining the association of FGG-FGB haplotypes with MI in the absence of effects of individual SNPs. Thus, epistatic and pleiotropic effects of polymorphisms contribute to the variation in plasma fibrinogen concentration, fibrin clot structure and risk of MI.

A novel common single nucleotide polymorphism in the promoter region of the C-reactive protein gene associated with the plasma concentration of C-reactive protein.

The plasma CRP concentration has consistently been shown to be associated with the risk of future coronary heart disease (CHD) and recent studies have suggested that CRP has a pathogenic role in CHD. Family studies and genotype-phenotype association studies of known polymorphisms in the intron, second exon and 3'-untranslated region (UTR) have suggested that plasma CRP concentrations are under genetic control. However, no functional polymorphisms have so far been reported in the promoter region of the CRP gene. Screening of 1600 base pair (bp) of the promoter region of the CRP gene, using denaturing high performance liquid chromatography, revealed two novel common single nucleotide polymorphisms (SNPs). One of them, a three allelic SNP located at position -286 from the transcription start, was strongly associated with the plasma CRP concentration, predominantly in patients with CHD. No difference in allele frequency was seen between middle-aged post-infarction patients and population-based controls. The prognostic role and therapeutic implications in CHD and the functionality of this polymorphism remain to be determined.

Genotype-specific increase in plasma concentrations of activated coagulation factor VII in response to experimental inflammation. A link between infection and acute myocardial infarction?

There is evidence that infection and inflammation might trigger an acute coronary event, but the mechanisms are unclear. Activated factor VII (FVIIa) is a potent coagulant that is under genetic control and a potential determinant of the outcome of acute myocardial infarction. This study investigated the acute FVIIa response to experimental inflammation. Forty healthy men and women were vaccinated with 1 ml of Salmonella Typhii vaccine. Plasma levels of FVIIa, FVII antigen (FVIIag), tissue factor (TF) activity and thrombin-antithrombin complex (TAT) were measured at baseline and up to 24 hours after inoculation. All subjects were genotyped for the FVII gene Arg353Gln polymorphism. Plasma concentrations of FVIIa, but not FVIIag, increased significantly with a peak at 10 hrs after vaccination. At 24 hrs FVIIa levels had returned to baseline. The FVIIa response to vaccination was significantly greater in subjects with the ArgArg genotype compared with ArgGln subjects. TAT increased, but TF activity was unchanged after vaccination. The results are of interest from a mechanistic viewpoint, since one explanation for the link between infection and acute myocardial infarction might be activation of coagulation. However, there is a need for further studies of the role of infection and inflammation in haemostasis.

Contribution of haplotypes across the fibrinogen gene cluster to variation in risk of myocardial infarction.

Fibrinogen has consistently been recognized as an independent predictor of myocardial infarction (MI). Multiple mechanisms link fibrinogen to MI; therefore disentangling the factors underlying variation in plasma fibrinogen concentration is essential. Candidate regions in the fibrinogen gamma (FGG), alpha (FGA) and beta (FGB) genes were screened for single nucleotide polymorphisms (SNPs). Several novel SNPs were detected in the FGG and FGA genes in addition to the previously known SNPs in the fibrinogen genes. Tight linkage disequilibrium extending over various physical distances was observed between most SNPs. Consequently, eight SNPs were chosen and determined in 377 postinfarction patients and 387 healthy individuals. None of the SNPs were associated with plasma fibrinogen concentration or MI. Haplotype analyses revealed a consistent pattern of haplotypes associated with variation in risk of MI. Of the four haplotypes inferred using the FGA -58G>A and FGG 1299 +79T>C SNPs, the most frequent haplotype, FGG-FGA*1 (prevalence 46.6%), was associated with increased risk of MI (OR 1.51; 95%CI 1.18, 1.93), whereas the least frequent haplotype, FGG-FGA*4 (11.8%), was associated with lower risk of MI (OR 0.79 95%CI 0.64, 0.98). In conclusion, fibrinogen haplotypes, but not SNPs in isolation, are associated with variation in risk of MI.

Human evidence that the cystatin C gene is implicated in focal progression of coronary artery disease.

OBJECTIVE: Overexpression of elastolytic cysteine and aspartic proteases, known as cathepsins, is implicated in atherogenesis. The potential significance of imbalance in expression between cathepsins and their inhibitor cystatin C in cardiovascular disease has been highlighted by the demonstration of cystatin C deficiency in human atherosclerosis and abdominal aortic aneurysms. METHODS AND RESULTS: We identified and characterized physiologically relevant polymorphisms in the promoter region of the cystatin C gene that influence cystatin C production and used these polymorphisms as a tool to examine the significance of cystatin C in coronary atherosclerosis in vivo in humans. Seven polymorphisms, all in strong-linkage disequilibrium, were identified in the cystatin C gene, of which 2 promoter polymorphisms (-82G/C and -78T/G) were functional in vitro in electromobility shift and transient transfection assays. Genotyping of 1105 individuals (237 survivors of a first myocardial infarction before age 60 and 2 independent groups comprising a total of 868 healthy individuals) revealed that the plasma cystatin C concentration was significantly lower in carriers of the mutant haplotype. Furthermore, the mutant haplotype was associated with a higher average number of stenoses per coronary artery segment in unselected postinfarction patients (N=237) undergoing routine coronary angiography. CONCLUSIONS: These results provide human evidence for an important role of cystatin C in coronary artery disease.

Prognostic value of plasma interleukin-6 concentrations and the -174 G > C and -572 G > C promoter polymorphisms of the interleukin-6 gene in patients with acute myocardial infarction treated with thrombolysis.

The present study was performed to investigate the prognostic value of plasma interleukin-6 (IL-6) concentrations and promoter polymorphisms of the IL-6 gene in patients with acute myocardial infarction treated with thrombolysis. Two hundred and eight patients with myocardial infarction treated with thrombolysis were included and followed for 2-5 years. Plasma concentrations of IL-6 were measured at admission and 48 h after admission. Genotyping for the -174 G > C and -572 G > C IL-6 polymorphisms was performed. Patients who died of cardiovascular causes or suffered a new myocardial infarction during follow-up had increased plasma concentrations of IL-6 at admission (P < 0.002) and at 48 h after admission (P < 0.05) compared with patients who had an uneventful course. IL-6 levels above the median at admission were independently associated with a worse prognosis. No associations were found between IL-6 levels and the promoter polymorphisms. The -174 G > C polymorphism was not associated with cardiovascular death or a new myocardial infarction, whereas the -572 G > C polymorphism showed a borderline significant increase in risk (P = 0.05) in univariate analysis. In conclusion, the early IL-6 response during myocardial infarction is associated with prognosis in patients with Q-wave myocardial infarction, whereas no associations were found between IL-6 genotype and phenotype.

Relationships of plasma factor VIIa-antithrombin complexes to manifest and future cardiovascular disease.

BACKGROUND: Low levels of free activated coagulation factor VII (VIIa) are normally present in plasma to prime the coagulation of blood in normal hemostasis and during thrombus formation. VIIa also circulates in inactive form, in complex with antithrombin (VIIaAT) formed when VIIa is bound to tissue factor (TF). This study evaluated VIIaAT in relation to cardiovascular disease (CVD). METHODS: We determined the plasma VIIaAT concentration in samples from the Stockholm Coronary Atherosclerosis Risk Factor (SCARF) study, a population-based case-control study of myocardial infarction (MI) and in samples from the Stockholm study of 60-years-old individuals, a prospective study of CVD. VIIaAT was measured with a sandwich ELISA that captures the complex between a monoclonal antibody to VIIa and a polyclonal antibody to AT. RESULTS: In the SCARF study (200 post-MI cases, 340 controls), VIIaAT was statistically significantly associated with patient status [odds ratio (95% confidence interval (CI)] 1.51 (1.09-2.08), p=0.0126). The case-control differences were however small, with VIIaAT values that largely overlap between the two groups. When a nested case-control design (211 incident CVD cases and 633 matched controls) was applied on 5- to 7-year follow-up results of the Stockholm prospective study of 60-year-olds, plasma VIIaAT concentration was not associated with incident CVD (odds ratio (95% CI) 1.001 (0.997-1.005), p=0.5447). CONCLUSIONS: Plasma VIIaAT concentration had no predictive value for future CVD in our study population. Slightly increased plasma VIIaAT concentrations observed after MI may reflect processes that occur in connection with the acute event when TF and VIIa availability is increased.

Genetic and environmental influences on the plasma interleukin-6 concentration in patients with a recent myocardial infarction: a case-control study.

The aim was to study the stimuli responsible for triggering and sustaining the plasma concentration of the inflammatory marker interleukin-6 (IL-6) in patients with a first myocardial infarction before the age of 60 and healthy control subjects matched for age and sex. The plasma IL-6 concentration, antibodies against Chlamydia pneumoniae, cytomegalovirus, Epstein-Barr virus, Helicobacter pylori, herpes simplex type 1 and 2, and genotype for the IL6-174 G>C single-nucleotide polymorphism were determined 3 months after the acute event. The results showed that patients had higher IL-6 levels than control subjects, whereas there were no differences regarding individual or total number (pathogen burden) of positive antibody tests against the different pathogens or IL6 genotype distribution. The plasma IL-6 concentration was associated with the number of positive antibody tests in patients and control subjects, whereas patients irrespective of IL6 genotype had increased IL-6. Multivariate analysis, including traditional coronary heart disease risk factors, antibodies against pathogens, and IL6 genotype, explained 17% of the variation of the plasma IL-6 concentration. Neither pathogen burden nor IL6 genotype did contribute to the variation of plasma IL-6 levels, whereas smoking, body-mass index, hypertension, case-control status, and age were determinants of the plasma IL-6 concentration.

Gender specific associations between matrix metalloproteinases and inflammatory markers in post myocardial infarction patients.

OBJECTIVE: Atherothrombotic disease in the coronary arteries leads to myocardial infarction (MI) through plaque rupture or erosion of the endothelium, the former mechanism predominating in men and the latter in women. Inflammation is a key feature of these processes, and the interplay between inflammation and matrix metalloproteinases (MMPs) in this context is not fully understood. In this study, we investigated the association between inflammatory markers and MMPs in men and women. METHODS: Blood samples were drawn 3 months after a first MI in 387 patients and 387 sex- and age-matched controls (82% men). C-reactive protein (CRP), interleukin-6 (IL-6), IL-8, -18, tumour necrosis factor-alpha (TNF-alpha), macrophage chemoattractant protein-1 (MCP-1), MMP-1, -3 and -9 were measured. Coronary angiography was performed in 243 of the patients, and they were classified into 0-, 1-, 2- or 3-vessel disease groups. RESULTS: CRP, IL-6, -8, -18 and TNF-alpha were higher, and MMP-3 and -9 were lower, in patients than in controls. A greater proportion of women (49%) had 0-vessel disease than men (16%, p<0.0001). A gender specific pattern of associations between inflammatory markers and MMPs was found as IL-6 (r(S)=0.29, p<0.05), IL-18 (r(S)=0.34, p<0.01) and MCP-1 (r(S)=0.35, p<0.01) correlated with MMP-3 in female patients, whereas CRP (r(S)=0.23, p<0.0001), IL-6 (r(S)=0.13, p<0.05) and IL-8 (r(S)=-0.21, p<0.01) correlated with MMP-9 in male patients. CONCLUSIONS: The present study demonstrates different patterns of association between inflammatory markers and MMPs in men and women, strengthening the hypothesis of gender specific differences in pathophysiological mechanisms of MI.

Human genetic evidence that OX40 is implicated in myocardial infarction.

We recently showed that genetic variants in OX40L are associated with myocardial infarction (MI) and severity of coronary artery disease in human. A number of studies also suggest a possible role for OX40 (the OX40L receptor) as a factor contributing to atherosclerosis. In the present study, the OX40 gene was screened for variants associated with precocious MI, using individuals with MI before the age of 60 and controls. Despite the fact that the OX40 gene is highly conserved between species and that relatively few common genetic variants were encountered, an association with MI was seen for a polymorphism in intron 5 (rs2298212). In silico investigation suggested that genetic variation (rs2298211), linked to this intronic variant, is possibly affecting spliceosome function. Our results provide evidence that variants in human OX40 might influence susceptibility to MI. The relevance of these findings is supported by the vital functions fulfilled by OX40 in mammals as reflected by the high level of evolutionary conservation.

Plasma C-reactive protein and lipoprotein levels, and progression of coronary artery disease after myocardial infarction treated with thrombolysis.

BACKGROUND: There is a paucity of studies using quantitative coronary angiography (QCA) to determine progression of coronary artery disease (CAD) after an acute coronary event. Furthermore, despite a great interest in effects of inflammation and 'early' lipid lowering therapy, no data have been published on the role of plasma C-reactive protein (CRP) and lipoprotein levels in CAD progression after myocardial infarction. METHODS: Seventy-two patients with myocardial infarction treated with thrombolysis, but not with statins, were investigated with QCA during admission and after 6 months. Plasma CRP concentrations were measured by a high sensitive method 2 days after the acute event, and plasma high-sensitive CRP and lipoprotein levels were determined 3 months after myocardial infarction. RESULTS: Overall, there was no significant progression of CAD, but when stenoses were grouped into those reducing the lumen diameter greater or less than 50%, progression was seen in stenoses originally <50%, whereas regression was seen in stenoses >50%. No consistent associations were seen between plasma CRP, lipoprotein lipid or lipoprotein(a) levels and CAD. CONCLUSIONS: Progression of stenoses <50% might be of clinical importance since these stenoses are more prone to rupture. Furthermore, the lack of associations between change in minimum lumen diameter and plasma CRP and lipoprotein concentrations suggests that positive effects on CAD progression of early treatment with anti-inflammatory or lipid-lowering drug therapy may not be expected in this subset of patients.

Genetic predisposition of the interleukin-6 response to inflammation: implications for a variety of major diseases?

BACKGROUND: A single-nucleotide polymorphism (SNP) in the promoter region of the interleukin-6 (IL-6) gene at position -174 (G>C) has been reported to be associated with a variety of major diseases, such as Alzheimer disease, atherosclerosis, and cardiovascular disease, cancer, non-insulin-dependent diabetes mellitus, osteoporosis, sepsis, and systemic-onset juvenile chronic arthritis. However, authors of previous in vitro and in vivo studies have reported conflicting results regarding the functionality of this polymorphism. We therefore aimed to clarify the role of the -174 SNP for the induction of IL-6 in vivo. METHODS: We vaccinated 20 and 18 healthy individuals homozygous for the -174 C and G alleles, respectively, with 1 mL of Salmonella typhii vaccine. IL-1beta, IL-6, and tumor necrosis factor-alpha (TNF-alpha) were measured in the blood at baseline and up to 24 h after vaccination. RESULTS: Individuals with the G genotype had significantly higher plasma IL-6 values at 6, 8, and 10 h after vaccination than did individuals with the C genotype (P <0.005). There were no differences between the two genotypes regarding serum concentrations of IL-1beta and TNF-alpha before or after vaccination. CONCLUSIONS: The -174 G>C SNP in the promoter region of the IL-6 gene is functional in vivo with an increased inflammatory response associated with the G allele. Considering the central role of IL-6 in a variety of major diseases, the present finding might be of major relevance.