Circulating cells as predictors of secondary manifestations of cardiovascular disease: design of the CIRCULATING CELLS study

Identification of a gene network driving the attenuated response to lipopolysaccharide of monocytes from hypertensive coronary artery disease patients

Introduction

The impact of cardiovascular disease (CVD) risk factors, encompassing various biological determinants and unhealthy lifestyles, on the functional dynamics of circulating monocytes-a pivotal cell type in CVD pathophysiology remains elusive. In this study, we aimed to elucidate the influence of CVD risk factors on monocyte transcriptional responses to an infectious stimulus.

Methods

We conducted a comparative analysis of monocyte gene expression profiles from the CTMM - CIRCULATING CELLS Cohort of coronary artery disease (CAD) patients, at baseline and after lipopolysaccharide (LPS) stimulation. Gene co-expression analysis was used to identify gene modules and their correlations with CVD risk factors, while pivotal transcription factors controlling the hub genes in these modules were identified by regulatory network analyses. The identified gene module was subjected to a drug repurposing screen, utilizing the LINCS L1000 database.

Results

Monocyte responsiveness to LPS showed a highly significant, negative correlation with blood pressure levels (ρ< -0.4; P<10-80). We identified a ZNF12/ZBTB43-driven gene module closely linked to diastolic blood pressure, suggesting that monocyte responses to infectious stimuli, such as LPS, are attenuated in CAD patients with elevated diastolic blood pressure. This attenuation appears associated with a dampening of the LPS-induced suppression of oxidative phosphorylation. Finally, we identified the serine-threonine inhibitor MW-STK33-97 as a drug candidate capable of reversing this aberrant LPS response.

Conclusions

Monocyte responses to infectious stimuli may be hampered in CAD patients with high diastolic blood pressure and this attenuated inflammatory response may be reversed by the serine-threonine inhibitor MW-STK33-97. Whether the identified gene module is a mere indicator of, or causal factor in diastolic blood pressure and the associated dampened LPS responses remains to be determined.

Sex-specific differences in cytokine signaling pathways in circulating monocytes of cardiovascular disease patients

BACKGROUND AND AIMS

This study aims to identify sex-specific transcriptional differences and signaling pathways in circulating monocytes contributing to cardiovascular disease.

METHODS AND RESULTS

We generated sex-biased gene expression signatures by comparing male versus female monocytes of coronary artery disease (CAD) patients (n = 450) from the Center for Translational Molecular Medicine-Circulating Cells Cohort. Gene set enrichment analysis demonstrated that monocytes from female CAD patients carry stronger chemotaxis and migratory signature than those from males. We then inferred cytokine signaling activities based on CytoSig database of 51 cytokine and growth factor regulation profiles. Monocytes from females feature a higher activation level of EGF, IFN1, VEGF, GM-CSF, and CD40L pathways, whereas IL-4, INS, and HMGB1 signaling was seen to be more activated in males. These sex differences were not observed in healthy subjects, as shown for an independent monocyte cohort of healthy subjects (GSE56034, n = 485). More pronounced GM-CSF signaling in monocytes of female CAD patients was confirmed by the significant enrichment of GM-CSF-activated monocyte signature in females. As we show these effects were not due to increased plasma levels of the corresponding ligands, sex-intrinsic differences in monocyte signaling regulation are suggested. Consistently, regulatory network analysis revealed jun-B as a shared transcription factor activated in all female-specific pathways except IFN1 but suppressed in male-activated IL-4.

CONCLUSIONS

We observed overt CAD-specific sex differences in monocyte transcriptional profiles and cytokine- or growth factor-induced responses, which provide insights into underlying mechanisms of sex differences in CVD.

Prediction Power on Cardiovascular Disease of Neuroimmune Guidance Cues Expression by Peripheral Blood Monocytes Determined by Machine-Learning Methods

Atherosclerosis is the underlying pathology in a major part of cardiovascular disease, the leading cause of mortality in developed countries. The infiltration of monocytes into the vessel walls of large arteries is a key denominator of atherogenesis, making monocytes accountable for the development of atherosclerosis. With the development of high-throughput transcriptome profiling platforms and cytometric methods for circulating cells, it is now feasible to study in-depth the predicted functional change of circulating monocytes reflected by changes of gene expression in certain pathways and correlate the changes to disease outcome. Neuroimmune guidance cues comprise a group of circulating- and cell membrane-associated signaling proteins that are progressively involved in monocyte functions. Here, we employed the CIRCULATING CELLS study cohort to classify cardiovascular disease patients and healthy individuals in relation to their expression of neuroimmune guidance cues in circulating monocytes. To cope with the complexity of human datasets featured by noisy data, nonlinearity and multidimensionality, we assessed various machine-learning methods. Of these, the linear discriminant analysis, Naïve Bayesian model and stochastic gradient boost model yielded perfect or near-perfect sensibility and specificity and revealed that expression levels of the neuroimmune guidance cues SEMA6B, SEMA6D and EPHA2 in circulating monocytes were of predictive values for cardiovascular disease outcome.

Association of Factor V Leiden With Subsequent Atherothrombotic Events: A GENIUS-CHD Study of Individual Participant Data

BACKGROUND

Studies examining the role of factor V Leiden among patients at higher risk of atherothrombotic events, such as those with established coronary heart disease (CHD), are lacking. Given that coagulation is involved in the thrombus formation stage on atherosclerotic plaque rupture, we hypothesized that factor V Leiden may be a stronger risk factor for atherothrombotic events in patients with established CHD.

METHODS

We performed an individual-level meta-analysis including 25 prospective studies (18 cohorts, 3 case-cohorts, 4 randomized trials) from the GENIUS-CHD (Genetics of Subsequent Coronary Heart Disease) consortium involving patients with established CHD at baseline. Participating studies genotyped factor V Leiden status and shared risk estimates for the outcomes of interest using a centrally developed statistical code with harmonized definitions across studies. Cox proportional hazards regression models were used to obtain age- and sex-adjusted estimates. The obtained estimates were pooled using fixed-effect meta-analysis. The primary outcome was composite of myocardial infarction and CHD death. Secondary outcomes included any stroke, ischemic stroke, coronary revascularization, cardiovascular mortality, and all-cause mortality.

RESULTS

The studies included 69 681 individuals of whom 3190 (4.6%) were either heterozygous or homozygous (n=47) carriers of factor V Leiden. Median follow-up per study ranged from 1.0 to 10.6 years. A total of 20 studies with 61 147 participants and 6849 events contributed to analyses of the primary outcome. Factor V Leiden was not associated with the combined outcome of myocardial infarction and CHD death (hazard ratio, 1.03 [95% CI, 0.92-1.16]; I2=28%; P-heterogeneity=0.12). Subgroup analysis according to baseline characteristics or strata of traditional cardiovascular risk factors did not show relevant differences. Similarly, risk estimates for the secondary outcomes including stroke, coronary revascularization, cardiovascular mortality, and all-cause mortality were also close to identity.

CONCLUSIONS

Factor V Leiden was not associated with increased risk of subsequent atherothrombotic events and mortality in high-risk participants with established and treated CHD. Routine assessment of factor V Leiden status is unlikely to improve atherothrombotic events risk stratification in this population.

NFAT activating protein with ITAM motif 1 (NFAM1) is upregulated on circulating monocytes in coronary artery disease and potentially correlated with monocyte chemotaxis

BACKGROUND AND AIMS

Circulating monocytes have been proven to be critical mediators in the propagation and progression of atherosclerosis and myocardial infarction. The present study was designed to characterise a new transmembrane protein-NFAT activating protein with ITAM motif 1 (NFAM1)-on monocytes and uncover the potential effects and underlying mechanisms in coronary artery disease.

METHODS

Monocytes from a population of four controls, five stable coronary artery disease patients and five acute coronary syndrome patients were isolated for RNA sequencing. A potential monocyte biomarker molecule was discovered and then validated with a group of 79 controls, 70 stable coronary artery disease patients and 183 acute coronary syndrome patients. A stable cell line was generated as an in vitro model to determine chemotaxis migration and chemokine receptor expression.

RESULTS

NFAM1 was identified through RNA sequencing analysis. The validation results confirmed that NFAM1 expression on monocytes was significantly increased by coronary artery disease status. A higher expression level of NFAM1 on classical and intermediate monocytes was observed compared with that on nonclassical monocytes. As shown in the in vitro cell model, knockdown of NFAM1 significantly attenuated chemotactic migration of monocytes by downregulating chemokine receptor expression and the p38 MAPK signalling pathway. Multivariable regression analysis of a group of 16 individuals suggested that NFAM1 was positively correlated with CCR2 expression.

CONCLUSIONS

The present study reported for the first time that distinctive alterations of NFAM1 expression on monocytes may correlate with atherosclerosis pathobiology and serve as a potential monocyte biomarker and therapeutic target for coronary artery disease.

Platelet RNA modules point to coronary calcification in asymptomatic women with former preeclampsia

BACKGROUND AND AIMS

Women who develop preeclampsia during pregnancy are at a higher risk for developing cardiovascular disease. As platelets are affected by preeclampsia, we set out to identify whether platelets carry information in their transcriptome on cardiovascular risk in women with former preeclampsia.

METHODS

Platelets were isolated from asymptomatic women with previous preeclampsia, who underwent screening with coronary computed tomography angiography. Platelet RNA was isolated and used to construct gene networks using an unbiased approach. Platelet gene modules assembled from the network were related to risk factors and clinical traits of these women, including coronary artery calcium scores (CACS).

RESULTS

We found multiple gene modules which correlated with CACS (correlation coefficients: 0.44 to 0.59, p = 0.05 to 0.007). The genes from two clinically relevant modules were expressed at a higher level in the group with calcifications (p = 3.9 × 10^-10 and 0.02) and enriched for platelet-related gene-sets such as platelet activation. The first of these modules was also enriched (p_permutation = 0.0546) for genes mapped to known coronary artery disease susceptibility loci. Additional unbiased network analyses in platelet RNA of patients with overt cardiovascular disease underlined the importance of the identified modules for disease by high preservation. (p = 1.6 × 10^-9 to 1.7 × 10^-47).

CONCLUSIONS

We found platelet RNA modules that correlated with CACS in asymptomatic women with previous preeclampsia. Whether or not platelets directly contribute to this disease trajectory, or reflect the underlying plaque substrate remains to be determined, but enrichment for coronary artery disease susceptibility genes emphasizes the importance for the disease.

Monocyte gene expression in childhood obesity is associated with obesity and complexity of atherosclerosis in adults

Childhood obesity coincides with increased numbers of circulating classical CD14⁺⁺CD16^- and intermediate CD14⁺⁺CD16⁺ monocytes. Monocytes are key players in the development and exacerbation of atherosclerosis, which prompts the question as to whether the monocytosis in childhood obesity contributes to atherogenesis over the years. Here, we dissected the monocyte gene expression profile in childhood obesity using an Illumina microarray platform on sorted monocytes of 35 obese children and 16 lean controls. Obese children displayed a distinctive monocyte gene expression profile compared to lean controls. Upon validation with quantitative PCR, we studied the association of the top 5 differentially regulated monocyte genes in childhood obesity with obesity and complexity of coronary atherosclerosis (SYNTAX score) in a cohort of 351 adults at risk for ischemic cardiovascular disease. The downregulation of monocyte IMPDH2 and TMEM134 in childhood obesity was also observed in obese adults. Moreover, downregulation of monocyte TMEM134 was associated with a higher SYNTAX atherosclerosis score in adults. In conclusion, childhood obesity entails monocyte gene expression alterations associated with obesity and enhanced complexity of coronary atherosclerosis in adults.

Classical determinants of coronary artery disease as predictors of complexity of coronary lesions, assessed with the SYNTAX score

Background

We need new biomarkers that can predict cardiovascular disease to improve both diagnosis and therapeutic strategies. The CIRCULATING CELLS study was designed to study the role of several cellular mediators of atherosclerosis as biomarkers of coronary artery disease (CAD). An objective and reproducible method for the quantification of CAD extension is required to establish relationships with these potential biomarkers. We sought to analyse the correlation of the SYNTAX score with known CAD risk factors to test it as a valid marker of CAD extension.

Methods and results

A subgroup of 279 patients (67.4% males) were included in our analysis. Main exclusion criteria were a history of previous percutaneous coronary intervention or surgical revascularisation that prevent an accurate assessment of the SS. Diabetes mellitus, smoking, renal insufficiency, body mass index and a history of CAD and myocardial infarction were all positively and strongly associated with a higher SYNTAX score after adjustment for the non-modifiable biological factors (age and sex). In the multivariate model, age and male sex, along with smoking and renal insufficiency, remain statistical significantly associated with the SYNTAX score.

Conclusion

In a selected cohort of revascularisation-naive patients with CAD undergoing coronary angiography, non-modifiable cardiovascular risk factors such as advanced age, male sex, as well as smoking and renal failure were independently associated with CAD complexity assessed by the SYNTAX score. The SYNTAX score may be a valid marker of CAD extension to establish relationships with potential novel biomarkers of coronary atherosclerosis.

Additional Candidate Genes for Human Atherosclerotic Disease Identified Through Annotation Based on Chromatin Organization

Background—

As genome-wide association efforts, such as CARDIoGRAM and METASTROKE, are ongoing to reveal susceptibility loci for their underlying disease—atherosclerotic disease—identification of candidate genes explaining the associations of these loci has proven the main challenge. Many disease susceptibility loci colocalize with DNA regulatory elements, which influence gene expression through chromatin interactions. Therefore, the target genes of these regulatory elements can be considered candidate genes. Applying these biological principles, we used an alternative approach to annotate susceptibility loci and identify candidate genes for human atherosclerotic disease based on circular chromosome conformation capture followed by sequencing.

Methods and Results—

In human monocytes and coronary endothelial cells, we generated 63 chromatin interaction data sets for 37 active DNA regulatory elements that colocalize with known susceptibility loci for coronary artery disease (CARDIoGRAMplusC4D) and large artery stroke (METASTROKE). By circular chromosome conformation capture followed by sequencing, we identified a physical 3-dimensional interaction with 326 candidate genes expressed in at least 1 of these cell types, of which 294 have not been reported before. We highlight 16 genes based on expression quantitative trait loci.

Conclusions—

Our findings provide additional candidate-gene annotation for 37 disease susceptibility loci for human atherosclerotic disease that are of potential interest to better understand the complex pathophysiology of cardiovascular diseases.

Circulating 'lncRNA OTTHUMT00000387022' from monocytes as a novel biomarker for coronary artery disease

AIMS

Long non-coding RNAs (lncRNAs) have been found to be involved in the pathogenesis of coronary artery disease (CAD). However, it remains to be established whether or not circulating lncRNAs can serve as biomarkers of CAD.

METHODS AND RESULTS

Using a microarray-based lncRNA expression profiling, we found 86 lncRNAs that were differentially expressed in circulating peripheral blood monocytes and plasma from 15 CAD patients and 15 control subjects. After choosing a consistent criterion (average normalized intensity ≥7 with significance <0.005) and confirmed by quantitative PCR, only three lncRNAs (CoroMarker, BAT5, and IL21R-AS1) remained as candidate CAD biomarkers. Using the analysis of area under the curve (AUC) of the receiver-operating characteristic in another pilot group and another larger cohort, CoroMarker was found to be the best candidate biomarker for CAD with an AUC of 0.920 and 95% confidence interval of 0.892-0.947. CoroMarker was independent from known CAD risk factors and other cardiovascular diseases. In a prospective study, we found that the sensitivity and specificity of CoroMarker were 76 and 92.5%, respectively. Functional enrichment analysis showed CoroMarker to be clustered with genes positively associated with signal transduction, transmembrane transport, synaptic transmission, and innate immunity and negatively associated with inflammation. These findings were validated in THP-1 cells; CoroMarker siRNA treatment decreased the concentrations of proinflammatory cytokines [interleukin (IL)-1β, IL-6, and tumour necrosis factor α] in the culture medium.

CONCLUSION

The present study suggests that CoroMarker is a novel and specific biomarker of CAD.

Treatment variation in stent choice in patients with stable or unstable coronary artery disease

AIM

Variations in treatment are the result of differences in demographic and clinical factors (e.g. anatomy), but physician and hospital factors may also contribute to treatment variation. The choice of treatment is considered important since it could lead to differences in long-term outcomes. This study explores the associations with stent choice: i.e. drug-eluting stent (DES) versus bare-metal stents (BMS) for Dutch patients diagnosed with stable or unstable coronary artery disease (CAD).

METHODS & RESULTS

Associations with treatment decisions were based on a prospective cohort of 692 patients with stable or unstable CAD. Of those patients, 442 patients were treated with BMS or DES. Multiple logistic regression analyses were performed to identify variables associated with stent choice. Bivariate analyses showed that NYHA class, number of diseased vessels, previous percutaneous coronary intervention, smoking, diabetes, and the treating hospital were associated with stent type. After correcting for other associations the treating hospital remained significantly associated with stent type in the stable CAD population.

CONCLUSIONS

This study showed that several factors were associated with stent choice. While patients generally appear to receive the most optimal stent given their clinical characteristics, stent choice seems partially determined by the treating hospital, which may lead to differences in long-term outcomes.

Platelet density per monocyte predicts adverse events in patients after percutaneous coronary intervention

Monocyte recruitment to damaged endothelium is enhanced by platelet binding to monocytes and contributes to vascular repair. Therefore, we studied whether the number of platelets per monocyte affects the recurrence of adverse events in patients after percutaneous coronary intervention (PCI). Platelet-monocytes complexes with high and low median fluorescence intensities (MFI) of the platelet marker CD42b were isolated using cell sorting. Microscopic analysis revealed that a high platelet marker MFI on monocytes corresponded with a high platelet density per monocyte while a low platelet marker MFI corresponded with a low platelet density per monocyte (3.4 ± 0.7 vs 1.4 ± 0.1 platelets per monocyte, P=0.01). Using real-time video microscopy, we observed increased recruitment of high platelet density monocytes to endothelial cells as compared with low platelet density monocytes (P=0.01). Next, we classified PCI scheduled patients (N=263) into groups with high, medium and low platelet densities per monocyte and assessed the recurrence of adverse events. After multivariate adjustment for potential confounders, we observed a 2.5-fold reduction in the recurrence of adverse events in patients with a high platelet density per monocyte as compared with a low platelet density per monocyte [hazard ratio=0.4 (95% confidence interval, 0.2-0.8), P=0.01]. We show that a high platelet density per monocyte increases monocyte recruitment to endothelial cells and predicts a reduction in the recurrence of adverse events in patients after PCI. These findings may imply that a high platelet density per monocyte protects against recurrence of adverse events.

Effects of Exercise on Gene Expression of Inflammatory Markers in Human Peripheral Blood Cells: A Systematic Review

Regular physical activity seems to be one of the most important contributors to prevent disease and promote health. Being physically active reduces the risk of developing chronic diseases such as cardiovascular disease, diabetes, and some types of cancers. The molecular mechanisms are however not fully elucidated. Depending on duration and intensity, exercise will cause disruption of muscle fibers triggering a temporary inflammatory response. This response may not only involve the muscle tissue, but also peripheral tissues such as white blood cells, which are important components of the immune system. The immune system plays a vital role in the development of atherosclerosis, thereby making white blood cells relevant to study when looking at molecular mechanisms induced by physical activity. In this review, we summarize the existing literature on exercise and gene expression in human white blood cells, and discuss these results in relation to inflammation and atherosclerosis.

Investigating the role of acute mental stress on endothelial dysfunction: a systematic review and meta-analysis

Chronic stress is a known risk factor for both endothelial dysfunction and cardiovascular disease (CVD), but less is known of how acute mental stress affects the vasculature. In this systematic review and meta-analysis, we analyzed the impact of acute mental stress on flow-mediated dilation (FMD), an indicator of endothelial function. We searched the Medline, Cochrane, EMBASE, and ISI Web of Knowledge databases through May 2014, to identify publications in English-language journals. The primary outcome was the change in FMD from baseline to the time of measurement. We also assessed the risk of bias and the heterogeneity of included studies. Our search identified eight prospective studies, which displayed significant heterogeneity. Four studies measured FMD while the subject was performing the task; six measured FMD after the task had been completed. The total number of participants was 164. The pooled results indicate that FMD did not change significantly while the task was being performed (pooled difference in means: -0.853; 95 % confidence interval (CI), -3.926/2.220; P = 0.586); however, FMD measured after the task was completed was significantly less than baseline (pooled difference in means: -2.450; 95 %CI, -3.925/-0.975; P = 0.001). In conclusions, our findings provide evidence that an acute stressful experience has a delayed, negative impact on the function of the endothelium. Repeated exposure to short-term stress may lead to permanent injury of the vasculature. Therefore, assessment of patients' exposure to both repeated acute mental stress and chronic stress may be useful in determining their risk of developing CVD.

Nighttime aircraft noise impairs endothelial function and increases blood pressure in patients with or at high risk for coronary artery disease

Aims

Epidemiological studies suggest the existence of a relationship between aircraft noise exposure and increased risk for myocardial infarction and stroke. Patients with established coronary artery disease and endothelial dysfunction are known to have more future cardiovascular events. We therefore tested the effects of nocturnal aircraft noise on endothelial function in patients with or at high risk for coronary artery disease.

Methods

60 Patients (50p 1–3 vessels disease; 10p with a high Framingham Score of 23 %) were exposed in random and blinded order to aircraft noise and no noise conditions. Noise was simulated in the patients’ bedroom and consisted of 60 events during one night. Polygraphy was recorded during study nights, endothelial function (flow-mediated dilation of the brachial artery), questionnaires and blood sampling were performed on the morning after each study night.

Results

The mean sound pressure levels L_eq(3) measured were 46.9 ± 2.0 dB(A) in the Noise 60 nights and 39.2 ± 3.1 dB(A) in the control nights. Subjective sleep quality was markedly reduced by noise from 5.8 ± 2.0 to 3.7 ± 2.2 (p < 0.001). FMD was significantly reduced (from 9.6 ± 4.3 to 7.9 ± 3.7 %; p < 0.001) and systolic blood pressure was increased (from 129.5 ± 16.5 to 133.6 ± 17.9 mmHg; p = 0.030) by noise. The adverse vascular effects of noise were independent from sleep quality and self-reported noise sensitivity.

Conclusions

Nighttime aircraft noise markedly impairs endothelial function in patients with or at risk for cardiovascular disease. These vascular effects appear to be independent from annoyance and attitude towards noise and may explain in part the cardiovascular side effects of nighttime aircraft noise.

Total calcium-sensing receptor expression in circulating monocytes is increased in rheumatoid arthritis patients with severe coronary artery calcification

Introduction

Human circulating monocytes express the calcium-sensing receptor (CaSR) and are involved in atherosclerosis. This study investigated the potential association between vascular calcification in rheumatoid arthritis (RA) and CaSR expression in circulating monocytes.

Methods

In this cross-sectional study, 50 RA patients were compared to 25 control subjects matched for age and gender. Isolation of peripheral blood mononuclear cells and flow cytometry analysis were performed to study the surface and total CaSR expression in circulating monocytes. Coronary artery calcium (CAC) and abdominal aortic calcification (AAC) scores were evaluated by computed tomography and an association between these scores and the surface and/or total CaSR expression in circulating monocytes in RA patients was investigated.

Results

The two groups were similar in terms of age (RA: 60.9 ± 8.3 years, versus controls: 59.6 ± 5.3 years) and gender (RA: 74.0% females versus 72.0% females). We did not find a higher prevalence and greater burden of CAC or AAC in RA patients versus age- and gender-matched controls. When compared with control subjects, RA patients did not exhibit greater total CaSR (101.6% ± 28.8 vs. 99.9% ± 22.0) or surface CaSR (104.6% ± 20.4 vs. 99.9% ± 13.7) expression, but total CaSR expression in circulating monocytes was significantly higher in RA patients with severe CAC (Agatston score ≥200, n = 11) than in patients with mild-to-moderate CAC (1 to 199, n = 21) (P = 0.01).

Conclusions

This study demonstrates for the first time that total CaSR expression in human circulating monocytes is increased in RA patients with severe coronary artery calcification.

Increased platelet reactivity is associated with circulating platelet-monocyte complexes and macrophages in human atherosclerotic plaques

OBJECTIVE

Platelet reactivity, platelet binding to monocytes and monocyte infiltration play a detrimental role in atherosclerotic plaque progression. We investigated whether platelet reactivity was associated with levels of circulating platelet-monocyte complexes (PMCs) and macrophages in human atherosclerotic carotid plaques.

METHODS

Platelet reactivity was determined by measuring platelet P-selectin expression after platelet stimulation with increasing concentrations of adenosine diphosphate (ADP), in two independent cohorts: the Circulating Cells cohort (n = 244) and the Athero-Express cohort (n = 91). Levels of PMCs were assessed by flow cytometry in blood samples of patients who were scheduled for percutaneous coronary intervention (Circulating Cells cohort). Monocyte infiltration was semi-quantitatively determined by histological examination of atherosclerotic carotid plaques collected during carotid endarterectomy (Athero-Express cohort).

RESULTS

We found increased platelet reactivity in patients with high PMCs as compared to patients with low PMCs (median (interquartile range): 4153 (1585-11267) area under the curve (AUC) vs. 9633 (3580-21565) AUC, P<0.001). Also, we observed increased platelet reactivity in patients with high macrophage levels in atherosclerotic plaques as compared to patients with low macrophage levels in atherosclerotic plaques (mean ± SD; 8969 ± 3485 AUC vs. 7020 ± 3442 AUC, P = 0.02). All associations remained significant after adjustment for age, sex and use of drugs against platelet activation.

CONCLUSION

Platelet reactivity towards ADP is associated with levels of PMCs and macrophages in human atherosclerotic carotid plaques.

Low levels of natural IgM antibodies against phosphorylcholine are independently associated with vascular remodeling in patients with coronary artery disease

Low anti-phosphorylcholine (PC) IgM plasma levels have been associated with increased incidence of adverse events in coronary artery disease (CAD). The underlying mechanisms are unclear. We hypothesized that atheroprotection mediated by anti-PC IgM antibodies is associated with reduced vascular remodeling and therefore tested whether anti-PC IgM plasma levels independently predict vascular remodeling. In a prospective cross-sectional study, anti-PC IgM plasma levels were measured in 175 consecutive patients with suspected CAD undergoing cardiac computed tomography angiography. Plaque morphology was thoroughly analyzed. Vascular remodeling was defined by a change in the vessel diameter at the plaque site in comparison to the reference segment proximal to the lesion (reference diameter) of ≥10%. Mean age of the patients was 64.8 ± 10.7 years, 48.6% were female. In 98 patients CAD was diagnosed, 57 (58.2%) of which displayed non-obstructive CAD (stenosis <50%), whereas 41 (41.8%) exhibited obstructive CAD (stenosis ≥50%). In 34 of 98 (34.7%) CAD patients vascular remodeling was present. Mean anti-PC IgM levels did not differ between patients with and without CAD (70.8 ± 52.7 vs. 69.1 ± 55.1 U/mL). However, anti-PC IgM levels were significantly lower in CAD patients compared to those without vascular remodeling (46.6 ± 31.6 vs. 73.3 ± 58.5 U/mL, P = 0.024). Using multivariate logistic regression, anti-PC IgM plasma levels independently predicted coronary vascular remodeling (HR 0.322, 95% confidence interval 0.121-0.856, P = 0.023). In conclusion, low anti-PC IgM levels are independently associated with coronary vascular remodeling. These findings may represent the link between in vitro studies demonstrating atheroprotective effects of anti-PC IgM and clinical data demonstrating that low anti-PC IgM levels are associated with adverse outcome in CAD patients.

Increased cytokine response after toll-like receptor stimulation in patients with stable coronary artery disease

OBJECTIVE

Atherosclerosis is associated with increased levels of plasma cytokines and expression of Toll-like receptors (TLRs). Yet, little is known about the potential use of TLR ligand induced cytokine release as a biomarker of coronary artery disease (CAD). In this study, we investigated whether TLR ligand induced cytokine release is associated with atherosclerotic disease severity and its predictive value for future cardiovascular events.

METHODS

Blood samples were obtained from 260 patients with stable angina and 15 healthy controls. Cytokine levels of TNFα, IL-8 and IL-6 were measured after 2 h of whole blood stimulation with 10 ng/ml lipopolysaccharide (LPS, TLR4 ligand) and P3C 500 ng/ml (TLR2 ligand). In a subgroup, dose-response curves were created using additional LPS concentrations.

RESULTS

LPS induced whole blood release of TNFα and IL-6, but not IL-8, was significantly higher in patients compared to healthy controls. Among CAD patients, TLR responses did hardly differ when associated with the presence of traditional risk factors and atherosclerotic disease severity (number of diseased vessels and coronary stenosis degree). Patients with secondary events during follow-up showed a trend towards an increased TLR response. Furthermore, positive associations were found between CRP levels and TLR-induced TNFα (CRP<2: 2055 pg/ml; CRP>2: 2364 pg/ml) and IL-6 production (CRP<2: 1742 pg/ml; CRP>2: 2250 pg/ml).

CONCLUSION

In conclusion, TLR-induced whole blood cytokine release in patients with stable angina indicates the presence of coronary atherosclerosis but does not reflect its severity.