Complement Activation in Association with Markers of Neutrophil Extracellular Traps and Acute Myocardial Infarction in Stable Coronary Artery Disease.

Complement activation and neutrophil extracellular traps (NETs) have both been suggested to drive atherosclerotic plaque progression. Although experimental studies suggest interplay between these two innate immunity components, the relevance in patients with coronary artery disease (CAD) is unclear. The aim of this study was to assess associations between complement activation and NETs in patients with stable CAD and examine the role of complement activation on clinical outcome. Blood samples from a cohort of patients with angiographically verified stable CAD (n = 1001) were analyzed by ELISA for the terminal complement complex (TCC) and by relative quantification for gene expression of the C5a receptor 1 (C5aR1) as markers of complement activation. As markers of NETs, dsDNA was analyzed by fluorescent nucleic acid stain and myeloperoxidase-DNA (MPO-DNA) by ELISA. Clinical outcome was defined as unstable angina, nonhemorrhagic stroke, acute myocardial infarction (MI), or death (n = 106, whereof 36 MI). Levels of TCC and C5aR1 were not significantly correlated to dsDNA (TCC: r = -0.045, p = 0.153; C5aR1: r = -0.060, p = 0.434) or MPO-DNA (TCC: r = 0.026, p = 0.414; C5aR1: r = 0.123, p = 0.107). When dividing TCC and C5aR1 levels into quartiles (Q), levels of MPO-DNA differed significantly across quartiles (TCC: p = 0.008, C5aR1: 0.049), while dsDNA did not (TCC: p = 0.181, C5aR1: p = 0.771). Patients with TCC levels in Q4 had significantly higher levels of MPO-DNA than Q1-3 (p = 0.019), and C5aR1 levels in Q3-4 had significantly higher levels of MPO-DNA than Q1-2 (p = 0.046). TCC levels did not differ between patients experiencing a clinical endpoint or not, but high levels were associated with increased risk of acute MI (OR. 1.97, 95% CI: 0.99-3.90, p = 0.053) during two-year follow up, also when adjusted for relevant covariates. In conclusion, TCC and C5aR1 were moderately associated with the NET marker MPO-DNA, and TCC levels were related to the risk of future MI in this cohort of patients with stable CAD.

Circulating levels of IL-18 are significantly influenced by the IL-18 +183 A/G polymorphism in coronary artery disease patients with diabetes type 2 and the metabolic syndrome: an observational study.

BACKGROUND: Increased IL-18 serum levels have been associated with diabetes type 2, metabolic syndrome and the severity of atherosclerosis. The present study investigated the presence and influence of IL-18 genetic variants on gene- and protein expression in stable coronary artery disease (CAD) patients. METHODS: The +183 A/G (rs 5744292), -137 G/C (rs 187238) and -607 C/A (rs 1946518) polymorphisms were determined in 1001 patients with angiographically verified stable CAD, and in 204 healthy controls. IL-18 gene-expression was measured in circulating leukocytes in 240 randomly selected patients. Circulating IL-18 and IL-18 binding protein levels were measured immunologically in all patients. RESULTS: The +183 G-allele associated significantly with lower serum levels of IL-18 (p = 0.002, adjusted for age, glucose, body mass index and gender) and a 1.13- fold higher IL-18 gene-expression (p = 0.010). No influence was observed for the -137 G/C and -607 C/A polymorphisms. The IL-18 binding protein levels were not influenced by IL-18 genotypes. IL-18 levels were significantly higher in men as compared to women, and in patients with diabetes type 2 and metabolic syndrome compared to those without (p ≤ 0.001, all). The reduction in IL-18 levels according to the +183 G-allele was 3-4 fold more pronounced in diabetes and metabolic syndrome as compared to unaffected patients.Finally, the +183 AA genotype was more frequent in patients with hypertension (p = 0.042, adjusted for age, body mass index and gender). CONCLUSION: The reduction in serum IL-18 levels across increasing numbers of +183 G-alleles was especially apparent in patient with diabetes type 2 and metabolic syndrome, suggesting a beneficial GG genotype in relation to cardiovascular outcome in these patients. CLINICAL TRIAL REGISTRATION NUMBER: ClinicalTrials.gov: NCT00222261.

The MMP-9 -1562 C/T polymorphism in the presence of metabolic syndrome increases the risk of clinical events in patients with coronary artery disease.

BACKGROUND AND OBJECTIVES: Elevated levels of matrix metalloproteinase (MMP)-9 have been associated with the metabolic syndrome (MetS) and cardiovascular events. The MMP-9 -1562 C/T polymorphism has furthermore been shown as a risk factor for coronary artery disease (CAD). The non-favourable cardiometabolic state in MetS may increase the risk. We aimed to investigate the influence of MMP-9 -1562 C/T polymorphism in subjects with CAD and MetS. METHODS: Patients (n = 1000) with verified CAD stratified in Mets +/- (n = 244/756), were analyzed for the MMP-9 -1562 C/T polymorphism and related to clinical events after 2 years follow-up. Serum levels of total MMP-9 and tissue inhibitor of matrix metalloproteinases (TIMP)-1 were analyzed in all, whereas MMP-9 activity, extracellular matrix metalloproteinase inducer (EMMPRIN), and expression of the two genes were analyzed in a subset of 240 randomly selected patients. RESULTS: Totally, 106 clinical endpoints were recorded. In MetS; the T-allele associated with 5.5 fold increase in event rate (p<0.0001), increased with number of MetS components, a 117% increase in total MMP-9 levels (TT homozygous, p = 0.05), significantly higher total- and endogenous active MMP-9 and TIMP-1 levels (p<0.01 all), and EMMPRIN was inversely correlated with pro- and endogenous active MMP-9 (p<0.05, both). In non-MetS; the T-allele was not associated with new events, nor higher MMP-9 levels. EMMPRIN was significantly correlated with total MMP-9 and TIMP-1 (p<0.01, both) and the two genes were inter-correlated (p<0.001). CONCLUSION: In CAD patients with MetS, the MMP-9 T-allele increased the risk of clinical events, probably mediated through elevated MMP-9 levels and altered MMP-9 regulation.

The co-existence of the IL-18+183 A/G and MMP-9 -1562 C/T polymorphisms is associated with clinical events in coronary artery disease patients.

OBJECTIVE: Interleukin (IL)-18 has been associated with severity of atherosclerosis and discussed to predict cardiovascular (CV) events. We have previously shown that the IL-18+183 G-allele significantly reduces IL-18 levels. This study was aimed to investigate the prognostic significance of the IL-18+183 A/G polymorphism (rs5744292), single and in coexistence with the matrix metalloproteinase (MMP)-9 -1562 C/T (rs3918242) polymorphism, in patients with stable coronary artery disease (CAD). Serum levels of IL-18, MMP-9 and tissue inhibitor of matrix metalloproteinase (TIMP)-1 were additionally assessed. METHODS: 1001 patients with angiographically verified CAD were genotyped and the biomarkers were measured accordingly. After two years follow-up, 10.6% experienced new clinical events; acute myocardial infarction (AMI), stroke, unstable angina pectoris and death. RESULTS: The IL-18+183 G-allele associated with 35% risk reduction in composite endpoints after adjusting for potential covariates (p = 0.044). The IL-18+183 AA/MMP-9 -1562 CT/TT combined genotypes associated with a significant increase in risk of composite endpoints (OR = 1.87; 95% CI = 1.13-3.11, p = 0.015, adjusted). Patients with clinical events presented with significantly higher IL-18 levels as compared to patients without (p = 0.011, adjusted). The upper tertile of IL-18 levels associated with an increase in risk of AMI as compared to lower tertiles (OR = 2.36; 95% CI = 1.20-4.64, p = 0.013, adjusted). CONCLUSION: The IL-18+183 A/G polymorphism, single and in combination with MMP-9 genotypes, may influence the risk of clinical events in stable CAD patients.