Eight genetic loci associated with variation in lipoprotein-associated phospholipase A2 mass and activity and coronary heart disease: meta-analysis of genome-wide association studies from five community-based studies.

AIMS: Lipoprotein-associated phospholipase A2 (Lp-PLA2) generates proinflammatory and proatherogenic compounds in the arterial vascular wall and is a potential therapeutic target in coronary heart disease (CHD). We searched for genetic loci related to Lp-PLA2 mass or activity by a genome-wide association study as part of the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Consortium. METHODS AND RESULTS: In meta-analyses of findings from five population-based studies, comprising 13 664 subjects, variants at two loci (PLA2G7, CETP) were associated with Lp-PLA2 mass. The strongest signal was at rs1805017 in PLA2G7 [P = 2.4 × 10(-23), log Lp-PLA2 difference per allele (beta): 0.043]. Variants at six loci were associated with Lp-PLA2 activity (PLA2G7, APOC1, CELSR2, LDL, ZNF259, SCARB1), among which the strongest signals were at rs4420638, near the APOE-APOC1-APOC4-APOC2 cluster [P = 4.9 × 10(-30); log Lp-PLA2 difference per allele (beta): -0.054]. There were no significant gene-environment interactions between these eight polymorphisms associated with Lp-PLA2 mass or activity and age, sex, body mass index, or smoking status. Four of the polymorphisms (in APOC1, CELSR2, SCARB1, ZNF259), but not PLA2G7, were significantly associated with CHD in a second study. CONCLUSION: Levels of Lp-PLA2 mass and activity were associated with PLA2G7, the gene coding for this protein. Lipoprotein-associated phospholipase A2 activity was also strongly associated with genetic variants related to low-density lipoprotein cholesterol levels.

Duffy antigen receptor for chemokines (Darc) polymorphism regulates circulating concentrations of monocyte chemoattractant protein-1 and other inflammatory mediators.

To identify the genetic basis of circulating concentrations of monocyte chemoattractant protein-1 (MCP-1), we conducted genome-wide association analyses for MCP-1 in 3 independent cohorts (n = 9598). The strongest association was for serum MCP-1 with a nonsynonymous polymorphism, rs12075 (Asp42Gly) in DARC, the gene for Duffy antigen receptor for chemokines, a known vascular reservoir of proinflammatory cytokines (minor allele frequency, 45.6%; P < 1.0 * 10(-323)). This association was supported by family-based genetic linkage at a locus encompassing the DARC gene (genome-wide P = 8.0 * 10(-13)). Asp42Gly accounted for approximately 20% of the variability in serum MCP-1 concentrations and also was associated with serum concentrations of interleukin-8 and RANTES. While exploring a lack of association between this polymorphism and EDTA plasma MCP-1 concentrations (P = .82), we determined that both clotting and exogenous heparan sulfate (unfractionated heparin) released substantial amounts of MCP-1 from Darc. Quantitative immunoflow cytometry failed to identify meaningful Asp42Gly-associated differences in Darc expression, suggesting that a functional change is responsible for the differential cytokine binding. We conclude that Asp42Gly is a major regulator of erythrocyte Darc-mediated cytokine binding and thereby the circulating concentrations of several proinflammatory cytokines. We have also identified for the first time 2 mechanisms for the release of reservoir chemokines with possible clinical implications.

Determinants of the acute-phase protein C-reactive protein in myocardial infarction survivors: the role of comorbidities and environmental factors.

BACKGROUND: C-reactive protein (CRP), a sensitive marker of the acute-phase response, has been associated with future cardiovascular endpoints independently of other risk factors. A joint analysis of the role of risk factors in predicting mean concentrations and variation of high-sensitivity CRP (hsCRP) in serum has not been carried out previously. METHODS: We used data from 1003 myocardial infarction (MI) survivors who had hsCRP measured monthly up to 8 times and multivariate mixed effects statistical models to study the role of time-variant and -invariant factors on the geometric mean of and the intraindividual variation in hsCRP concentrations. RESULTS: Patients with > or =6.5% glycosylated hemoglobin (HbA1c) had 26.2% higher hsCRP concentrations (95% CI, 7.2%-48.6%) and 20.7% greater variation in hsCRP values (P = 0.0034) than patients with lower baseline Hb A(1c) values (<6.5%). Similar but less pronounced differences were seen in patients with a self-reported diagnosis of type 2 diabetes. hsCRP concentrations showed less variation in patients who reported angina pectoris, congestive heart failure, or emphysema (-11.0%, -24.9%, and -41.6%, respectively, vs patients without these conditions) but greater variation in males and smokers (+24.8% and +27.3%, respectively, vs females and nonsmokers). Exposures in the 24 h before blood sampling, including exposure to environmental tobacco smoke, alcohol consumption, and extreme stress, did not have a major impact. CONCLUSIONS: One or 2 hsCRP measurements may not be sufficient to adequately characterize different patient groups after MI with similar precisions. We found hsCRP concentrations to be especially variable in males, smokers, and patients with increased Hb A(1c) values.

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

BACKGROUND: The role of the Fc gamma receptor IIa (Fc gamma RIIa), a receptor for C-reactive protein (CRP), the classical acute phase protein, in atherosclerosis is not yet clear. We sought to investigate the association of Fc gamma RIIa genotype with risk of coronary heart disease (CHD) in two large population-based samples. METHODS: Fc gamma RIIa-R/H131 polymorphisms were determined in a population of 527 patients with a history of myocardial infarction and 527 age and gender matched controls drawn from a population-based MONICA- Augsburg survey. In the LURIC population, 2227 patients with angiographically proven CHD, defined as having at least one stenosis >or= 50%, were compared with 1032 individuals with stenosis <50%. RESULTS: In both populations genotype frequencies of the Fc gamma RIIa gene did not show a significant departure from the Hardy-Weinberg equilibrium. Fc gamma RIIa R(-131) --> H genotype was not independently associated with lower risk of CHD after multivariable adjustments, neither in the MONICA population (odds ratio (OR) 1.08; 95% confidence interval (CI) 0.81 to 1.44), nor in LURIC (OR 0.96; 95% CI 0.81 to 1.14). CONCLUSION: Our results do not confirm an independent relationship between Fc gamma RIIa genotypes and risk of CHD in these populations.

Lipoprotein-associated and secretory phospholipase A2 in cardiovascular disease: the epidemiological evidence.

INTRODUCTION: Among other lipid related biomarkers, lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) and type II secretory phospholipase A(2) (sPLA(2)) represent emerging candidates for refined assessment of future cardiovascular disease (CVD) risk. Indeed, emerging evidence from more than prospective 15 studies conducted since 2000, clearly demonstrate the prognostic ability of increased Lp-PLA(2) concentrations or elevated activity for risk of future coronary heart disease (CHD) and stroke. Moreover, Lp-PLA(2) might have similar predictive power for both, incident CHD in initially healthy subjects, as well as for recurrent events in those with clinically manifest atherosclerosis. DISCUSSION: By contrast, to date, there are only few prospective studies that have investigated the relationship of sPLA(2) with future CVD risk. However, most of them show a positive association between increased mass or elevated activity and future atherosclerotic complications. Nonetheless, since inhibitors of Lp-PLA(2) and sPLA(2) have already been developed, these enzymes may be considered as novel therapeutic targets to treat residual risk in certain high risk patient groups. CONCLUSION: This review summarizes the epidemiologic evidence on the association between increased mass or elevated activity of these two phospholipases and risk of CVD.

DNA variants, plasma levels and variability of C-reactive protein in myocardial infarction survivors: results from the AIRGENE study.

AIMS: C-reactive protein represents the classical acute-phase protein produced in the liver in response to inflammatory stimuli. This study evaluated the association of gene polymorphisms with differences in C-reactive protein concentrations and assessed its intra-individual variability as a marker of individual response. METHODS AND RESULTS: One thousand and three myocardial infarction (MI) survivors were recruited in six European cities, and C-reactive protein concentrations were measured repeatedly during a 6-month period. We investigated 114 polymorphisms in 13 genes, all involved in the innate inflammatory pathway. We found two polymorphisms within the C-reactive protein (CRP) gene rs1800947 and rs1205, of which the minor alleles were strongly associated with lower levels of C-reactive protein (P < 10(-6)). A haplotype, identified by those two polymorphisms, was associated with the lowest C-reactive protein concentrations (P < 10(-6)). Additionally, the minor alleles of several variants were significantly associated with greater individual variability of C-reactive protein concentrations (P < 10(-3)). CONCLUSION: The present study investigated the association of polymorphisms with inter- and intra-individual variability of C-reactive protein levels. Two minor alleles of C-reactive protein variants were associated with lower C-reactive protein concentrations. Regarding intra-individual variability, we observed associations with the minor alleles of several variants in selected candidate genes, including the CRP gene itself.

Association between variations in the TLR4 gene and incident type 2 diabetes is modified by the ratio of total cholesterol to HDL-cholesterol.

BACKGROUND: Toll-like receptor 4 (TLR4), the signaling receptor for lipopolysaccharides, is an important member of the innate immunity system. Since several studies have suggested that type 2 diabetes might be associated with changes in the innate immune response, we sought to investigate the association between genetic variants in the TLR4 gene and incident type 2 diabetes. METHODS: A case-cohort study was conducted in initially healthy, middle-aged subjects from the MONICA/KORA Augsburg studies including 498 individuals with incident type 2 diabetes and 1,569 non-cases. Seven SNPs were systematically selected in the TLR4 gene and haplotypes were reconstructed. RESULTS: The effect of TLR4 SNPs on incident type 2 diabetes was modified by the ratio of total cholesterol to high-density lipoprotein cholesterol (TC/HDL-C). In men, four out of seven TLR4 variants showed significant interaction with TC/HDL-C after correction for multiple testing (p < 0.01). The influence of the minor alleles of those variants on the incidence of type 2 diabetes was observed particularly for male patients with high values of TC/HDL-C. Consistent with these findings, haplotype-based analyses also revealed that the effect of two haplotypes on incident type 2 diabetes was modified by TC/HDL-C in men (p < 10-3). However, none of the investigated variants or haplotypes was associated with type 2 diabetes in main effect models without assessment of effect modifications. CONCLUSION: We conclude that minor alleles of several TLR4 variants, although not directly associated with type 2 diabetes might increase the risk for type 2 diabetes in subjects with high TC/HDL-C. Additionally, our results confirm previous studies reporting sex-related dissimilarities in the development of type 2 diabetes.

Biomarkers of atherosclerotic plaque instability and rupture.

Basic research over the last two decades has identified a large number of molecules pertinent to the atherosclerotic process, which have clearly improved our understanding of the underlying pathology. It is now well established that inflammation represents a major feature which is present in the vessel wall throughout all stages of the disease until the final pathophysiologic steps, representing plaque destabilization and eventually plaque rupture. Several cells typical for the atherosclerotic plaque, like monocyte-derived macrophages and T-lymphocytes are able to produce and secrete such mediator molecules, like cytokines, chemokines, growth-factors, enzymes, and disintegrins, which lead to activation of endothelial cells, proliferation of smooth muscle cells, lesion progression, and finally to the weakening of a vulnerable plaque by matrix degradation of its fibrous cap. Today, many of these molecules involved can be measured systemically by sensitive assays, and elevated concentrations in the circulation have been shown to be associated with future cardiovascular events. Determination of several of these molecules carries important prognostic information, independent of traditional risk factors, and may turn out to be useful in improving risk stratification. However, for most of these biomarkers the clinical utility has not yet been established.

Increased concentrations of C-reactive protein and IL-6 but not IL-18 are independently associated with incident coronary events in middle-aged men and women: results from the MONICA/KORA Augsburg case-cohort study, 1984-2002.

OBJECTIVE: We performed a prospective case-cohort study in initially healthy, middle-aged men and women from the MONICA/KORA Augsburg studies conducted between 1984 and 2002 to assess the role of IL-18 in comparison with IL-6 and CRP in the prediction of incident coronary heart disease (CHD). METHODS AND RESULTS: Concentrations of IL-18 were measured in 382 case subjects with incident CHD and 1980 noncases. Mean follow-up was 11 years. Baseline concentrations of IL-18 were slightly higher in cases than in noncases (172.4 [1.0] versus 161.3 [1.0] pg/mL, respectively; P=0.114), but were clearly elevated for C-reactive protein (CRP) and IL-6 in cases compared with noncases. In multivariable analyses, accounting for classical cardiovascular risk factors and inflammatory markers, no statistically significant association was seen between increased concentrations of IL-18 and incident CHD both in men (hazard ratio [HR] and 95% confidence intervals [CIs] comparing extreme tertiles, 1.20; 95% CI, 0.85 to 1.69), and in women (HR, 1.25; 95% CI, 0.67 to 2.34). However, in this population increased concentrations of CRP and IL-6 were found to be independent predictors of future CHD events, even after multivariable adjustment. CONCLUSIONS: Elevated concentrations of CRP and IL-6, but not IL-18, were independently associated with risk of CHD in subjects from an area with moderate absolute risk.

Periodontal infections and coronary heart disease: role of periodontal bacteria and importance of total pathogen burden in the Coronary Event and Periodontal Disease (CORODONT) study.

BACKGROUND: Chronic inflammation from any source is associated with increased cardiovascular risk. Periodontitis is a possible trigger of chronic inflammation. We investigated the possible association between periodontitis and coronary heart disease (CHD), focusing on microbiological aspects. METHODS: A total of 789 subjects (263 patients with angiographically confirmed, stable CHD and 526 population-based, age- and sex-matched controls without a history of CHD) were included in the Coronary Event and Periodontal Disease (CORODONT) study. Subgingival biofilm samples were analyzed for periodontal pathogens Actinobacillus actinomycetemcomitans, Tannerella forsythensis, Porphyromonas gingivalis, Prevotella intermedia, and Treponema denticola using DNA-DNA hybridization. The need for periodontal treatment in each subject was assessed using the Community Periodontal Index of Treatment Needs (CPITN). The main outcome measures included total periodontal pathogen burden, number of the various periodontal pathogens in the subgingival biofilm, and periodontal treatment needs (according to the CPITN). RESULTS: In multivariable analyses, we found a statistically significant association between the periodontal pathogen burden (log10 of the sum of all pathogens) (odds ratio [OR], 1.92; 95% confidence interval [CI], 1.34-2.74; P<.001) or the number of A actinomycetemcomitans in periodontal pockets (log10) (OR, 2.70; 95% CI, 1.79-4.07; P<.001) and the presence of CHD. In addition, a statistically significant association between an increase in mean CPITN score by 1 and the presence of CHD (OR, 1.67; 95% CI, 1.08-2.58; P = .02) was observed. CONCLUSIONS: Our findings suggest an association between periodontitis and presence of CHD. Periodontal pathogen burden, and particularly infection with A actinomycetemcomitans, may be of special importance.

Plasma oxidized low-density lipoprotein, a strong predictor for acute coronary heart disease events in apparently healthy, middle-aged men from the general population.

BACKGROUND: Oxidized LDL (oxLDL) is thought to play a key role in the inflammatory response in the arterial vessel wall. METHODS AND RESULTS: In a prospective, nested, case-control study, the association between plasma oxLDL and risk of an acute coronary heart disease (CHD) event was investigated in men without prevalent CHD or diabetes mellitus at baseline. Subjects came from 2 population-based MONICA/KORA Augsburg surveys conducted in the years 1989-1990 and 1994-1995 with follow-up in 1998 (mean+/-SD follow-up time, 5.6+/-2.6 years). OxLDL was determined by ELISA in 88 men with incident CHD and in 258 age- and survey-matched controls. Hazard ratios (HRs) were estimated from conditional logistic-regression models with matching for age and survey. Baseline mean plasma oxLDL concentrations were significantly higher in subjects who subsequently experienced an event compared with controls (mean+/-SD, 110+/-32 versus 93+/-28 U/L; P< or =0.001). After adjustment for smoking, hypertension, obesity, physical activity, education, and alcohol consumption, the HR for a future CHD event in a comparison of the upper tertile of the oxLDL distribution with the lower tertile was 4.25 (95% confidence interval, 2.09 to 8.63; P<0.001). Plasma oxLDL was the strongest predictor of CHD events compared with a conventional lipoprotein profile and other traditional risk factors for CHD. When both oxLDL and C-reactive protein were simultaneously assessed in the same model, they still predicted future CHD events even after multivariable adjustment. CONCLUSIONS: Elevated concentrations of oxLDL are predictive of future CHD events in apparently healthy men. Thus, oxLDL may represent a promising risk marker for clinical CHD complications and should be evaluated in further studies.

Lipoprotein-associated phospholipase A2 adds to risk prediction of incident coronary events by C-reactive protein in apparently healthy middle-aged men from the general population: results from the 14-year follow-up of a large cohort from southern Germany.

BACKGROUND: Chronic inflammation represents an essential feature of the atherosclerotic process. Lipoprotein-associated phospholipase A2 (Lp-PLA2), an enzyme mainly produced by monocytes/macrophages, generates potent proinflammatory products. METHODS AND RESULTS: Plasma concentrations of Lp-PLA2 were determined by ELISA in 934 apparently healthy men aged 45 to 64 years sampled from the general population in 1984 and followed up until 1998. During this period, 97 men experienced a coronary event diagnosed according to the MONICA (MONItoring of trends and determinants in CArdiovascular disease) protocol. Baseline levels of Lp-PLA2 were higher in subjects who experienced an event than in event-free subjects (295+/-113 versus 263+/-79 ng/mL, P<0.01). Lp-PLA2 was positively correlated with total cholesterol (R=0.30, P<0.0001) and age (R=0.12, P=0.001), was only slightly correlated with HDL cholesterol (R=0.09, P=0.005) and C-reactive protein R=0.06, P=0.06), but was not correlated with body mass index or blood pressure. In a Cox model, a 1-SD increase in Lp-PLA2 was associated with risk of future coronary events (hazard ratio [HR] 1.37, 95% CI 1.16 to 1.62). After controlling for potential confounders, the HR was attenuated but remained statistically significant (HR 1.23, 95% CI 1.02 to 1.47). Further inclusion of C-reactive protein in the model did not appreciably affect its predictive ability (HR 1.21, 95% CI 1.01 to 1.45). CONCLUSIONS: Elevated levels of Lp-PLA2 appeared to be predictive of future coronary events in apparently healthy middle-aged men with moderately elevated total cholesterol, independent of CRP. This suggests that Lp-PLA2 and CRP may be additive in their ability to predict risk of coronary heart disease.

CD14 C(-260)-->T polymorphism, plasma levels of the soluble endotoxin receptor CD14, their association with chronic infections and risk of stable coronary artery disease.

OBJECTIVES: We sought to investigate the association of CD14 genotype and plasma levels of soluble (s)CD14 with risk of stable coronary artery disease (CAD), chronic infections and sensitive markers of systemic inflammation. BACKGROUND: It has been suggested that genetic variation of the CD14 receptor with increased CD14 gene expression might play a role in atherogenesis. A mechanistic link would consist in its contribution to the inflammatory response seen in this disease. METHODS: We measured levels of sCD14 (microg/ml; ELISA) in 312 patients with angiographically proven CAD and stable angina pectoris, and in 477 age- and gender-matched healthy blood donors. CD14 genotype was determined by polymerase chain reaction. In addition, seropositivity to Chlamydia pneumoniae and Helicobacter pylori, a complete lipid profile and various sensitive systemic markers of inflammation were measured. RESULTS: CD14 C(-260)-->T genotype was not independently associated with increased risk of CAD after multivariable adjustments (odds ratio [OR] 1.34; 95% confidence interval [CI] 0.84 to 2.16). However, sCD14 plasma levels were higher in subjects with TT genotype compared with those with CT or CC genotype (p = 0.005). Plasma levels were not different between cases and controls (4.2 +/- 1.3 microg/ml vs. 4.3 +/- 1.3 microg/ml, p = NS). In multivariable logistic regression, the OR for the presence of CAD was 1.11 (95% CI, 0.65 to 1.91) if the top quintile of the sCD14 distribution was compared with the bottom quintile. There was no consistent association between seropositivity to either C. pneumoniae or H. pylori, or both, and sCD14 levels and between sCD14 levels or CD14 genotype and the various markers of inflammation. CONCLUSIONS: These results do not confirm an independent relationship between CD14 genotypes or plasma levels of sCD14 and risk of stable CAD in this population.

Association between Lp-PLA2 and coronary artery disease: focus on its relationship with lipoproteins and markers of inflammation and hemostasis.

Lipoprotein-associated phospholipase A2 (Lp-PLA2) generates pro-inflammatory molecules from oxidized LDL. We examined the association between Lp-PLA2 plasma concentrations and risk of stable coronary artery disease (CAD) in a large case-control study and further assessed the relationship between Lp-PLA2 and various lipid, inflammatory and hemostatic parameters. Lp-PLA2 concentrations were measured in 312 patients with CAD and in 479 age- and gender-matched blood donors. Various sensitive inflammatory and hemostatic markers and a complete lipoprotein profile were obtained. Lp-PLA2 concentrations were significantly higher in cases than in controls (296.1 ng/mL versus 266.0 ng/mL, p<0.0001). In multivariable logistic regression, the age- and gender-adjusted OR for the presence of CAD was 1.61 (95% CI, 1.07-2.44) if the top quartile of the Lp-PLA2 distribution was compared to the bottom quartile. Adjustment for traditional cardiovascular risk factors and statin use resulted in an OR of 2.04 (95% CI, 1.19-3.48). After additional controlling for vWF, the OR was slightly attenuated but still remained statistically significant (OR 1.91; 95% CI, 1.12-3.28). Thus, elevated Lp-PLA2 concentrations were associated with the presence of stable CAD, independent of various biochemical markers. Our results support the hypothesis that Lp-PLA2 may be a novel, independent risk marker for CAD.

Prospective study of high-sensitivity C-reactive protein as a determinant of mortality: results from the MONICA/KORA Augsburg Cohort Study, 1984-1998.

BACKGROUND: C-reactive protein (CRP), an exquisitely sensitive systemic marker of inflammation, has emerged as an independent predictor of cardiovascular diseases (CVD). Because other chronic diseases are also associated with an inflammatory response, we sought to assess the association of high-sensitivity CRP (hsCRP) with total and cause-specific mortality in a large cohort of middle-aged men. METHODS: We measured hsCRP at baseline in 3620 middle-aged men, randomly drawn from 3 samples of the general population in the Augsburg area (Southern 0Germany) in 1984-85, 1989-90, and 1994-95. Outcome was defined as all deaths, fatal CVD, fatal coronary heart disease (CHD) including sudden cardiac deaths, and cancer deaths. RESULTS: During an average follow-up of 7.1 years, 408 deaths occurred (CVD 196, CHD 129, cancer 127). In multivariable Cox regression analysis, subjects with hsCRP >3 mg/L at baseline showed an almost 2-fold increased risk to die vs those with hsCRP <1 mg/L [hazard ratio (HR) 1.88, 95% CI 1.41-2.52]. HRs were 2.15 (95% CI 1.39-3.34) for fatal CVD, 1.74 (1.04-2.92) for fatal CHD, and 1.65 (1.01-2.68) for cancer mortality. In contrast, neither total nor HDL cholesterol significantly predicted all-cause or cancer mortality, and cholesterol had only modest effects on CVD mortality. CONCLUSIONS: Our results suggest that increased circulating hsCRP concentrations are associated with an increased risk of death from several widespread chronic diseases. Persistently increased hsCRP is a sensitive and valuable nonspecific indicator of an ongoing disease process that deserves serious and careful medical attention.

Lipoprotein-associated phospholipase A2 concentrations in plasma are associated with the extent of coronary artery disease and correlate to adipose tissue levels of marine n-3 fatty acids.

Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) is an emerging risk factor for cardiovascular disease. In the present study, plasma levels of Lp-PLA(2) were measured in patients (n=301) admitted to elective coronary angiography because of suspected coronary artery disease (CAD). In a multiple linear regression analysis, the degree of CAD (0-, 1-, 2- or 3-vessel disease) and plasma LDL cholesterol significantly correlated to Lp-PLA(2) levels. Also the content of the marine n-3 fatty acid, eicosapentaenoic acid (EPA) in adipose tissue, a measure of long-term intake of seafood independently and inversely (r=-0.18, p<0.01) correlated with plasma levels of Lp-PLA(2). The results support the view that Lp-PLA(2) may relate to CAD and that intake of marine n-3 fatty acids might reduce plasma Lp-PLA(2) suggesting another mechanism by which n-3 fatty acids could reduce the risk of cardiovascular disease.

Variability of serial lipoprotein-associated phospholipase A2 measurements in post myocardial infarction patients: results from the AIRGENE Study Center Augsburg.

BACKGROUND: Of the numerous emerging biomarkers for coronary heart disease (CHD), lipoprotein-associated phospholipase A(2) (Lp-PLA(2)), an enzyme involved in lipid metabolism and inflammatory pathways, seems to be a promising candidate. Implementation of Lp-PLA(2) measurement into clinical practice, however, requires data on the reliability of such measurements. METHODS: We measured Lp-PLA(2) concentrations by ELISA in blood samples drawn from 200 post-myocardial infarction patients (39-76 years) at 6 monthly intervals between May 2003 and February 2004, for a total of 1143 samples. We estimated analytical, within-individual, and between-individual variation, the critical difference, and the intraclass correlation coefficient of reliability (ICC) to assess the reliability of serial Lp-PLA(2) measurements. RESULTS: The mean (SD) plasma Lp-PLA(2) concentration for the study participants was 188.7 (41.8) microg/L, with no significant difference between men and women. The analytical CV for Lp-PLA(2) was 4.4%, the within-individual biological CV was 15%, and the between-individual CV was 22%. The ICC was 0.66. An important part of the total variation in plasma Lp-PLA(2) concentration was explained by the between-individual variation (as a percentage of the total variance, 66.1%), whereas the within-individual variance was 31.3%. The analytical variance was as low as 2.6%. CONCLUSIONS: Between-individual variation in Lp-PLA(2) concentration was substantially greater than within-individual variation. In general, our data demonstrate considerable stability and good reproducibility of serial Lp-PLA(2) measurements, results that compared favorably with those for the more commonly measured lipid markers.

Macrophage migration inhibitory factor (MIF) and risk for coronary heart disease: results from the MONICA/KORA Augsburg case-cohort study, 1984-2002.

OBJECTIVE: Macrophage migration inhibitory factor (MIF), a central cytokine of the innate immunity, has been reported to contribute to the development of cardiovascular disease. MIF is expressed in atherosclerotic lesions in humans, and gene deletion and antibody inhibition studies in animal models indicated that MIF may be cause rather than consequence of atherosclerosis. We sought to assess the triangular association between MIF genotypes, circulating MIF levels and risk for incident coronary heart disease (CHD) in the large, prospective, population-based MONICA/KORA case-cohort study (Augsburg, Southern Germany). METHODS: MIF genotypes, haplotypes and serum concentrations were determined in 363 individuals with incident CHD and 1908 individuals without CHD during follow-up (mean follow-up time 10.3 years). RESULTS: Circulating MIF concentrations were not associated with the risk for CHD. In women, carriers of the minor alleles rs755622C and rs2070766G had a higher risk for incident CHD, and a haplotype that contained these two minor alleles was significantly associated with increased risk for CHD (HR 2.44, 95%CI 1.30-4.59). CONCLUSION: The lack of association between serum levels and incident CHD indicates that MIF may not be a novel biomarker for CHD risk. However, the association of a haplotype containing the rs755622C allele, which has been reported before to increase the susceptibility for various other proinflammatory conditions, with CHD points towards a role for MIF in local vascular inflammation and atherogenesis.

RANTES/CCL5 gene polymorphisms, serum concentrations, and incident type 2 diabetes: results from the MONICA/KORA Augsburg case-cohort study, 1984-2002.

OBJECTIVE: Regulated on activation, normal T-cell expressed and secreted (RANTES)/chemokine(C-C motif) ligand (CCL5) is expressed by adipocytes, and serum levels of RANTES are increased in obesity and type 2 diabetes. The aim of this study was to test the hypothesis that RANTES is involved in the pathogenesis of type 2 diabetes by analyzing the triangular association between CCL5 gene polymorphisms, systemic RANTES concentrations, and incident type 2 diabetes in a large prospective study. SUBJECTS AND METHODS: The study is based on 502 individuals (293 men and 209 women) and 1632 individuals (859 men and 773 women) with and without incident type 2 diabetes from the population-based MONItoring of Trends and Determinants in Cardiovascular Disease (MONICA)/Cooperative Health Research in the Region of Augsburg (KORA) case-cohort study respectively (mean follow-up time+/-s.d. 10.1+/-4.9 years). CCL5 genotypes and RANTES serum concentrations were determined and associations between genotypes, haplotypes, serum levels, and incident type 2 diabetes were assessed. Results Minor alleles of four single nucleotide polymorphisms were associated with lower RANTES levels (P(additive) between 1.2 x 10(-9) and 3.1 x 10(-8)), but neither genotypes, haplotypes, nor serum levels were associated with incident type 2 diabetes. CONCLUSIONS: Our data suggest that RANTES/CCL5 gene variants and serum levels are not causally related with type 2 diabetes and that elevated RANTES levels in patients with type 2 diabetes may be a consequence of hyperglycemia. However, our findings cannot preclude a local role in adipose tissue where RANTES expression may contribute to leukocyte infiltration and a proinflammatory state.