CDC/AHA Workshop on Markers of Inflammation and Cardiovascular Disease

Targeted anti-inflammatory therapy is a new insight for reducing cardiovascular events: A review from physiology to the clinic

Despite considerable progressions, cardiovascular disease (CVD) is still one of the major causes of mortality around the world, indicates an important and unmet clinical need. Recently, extensive studies have been performed on the role of inflammatory factors as either a major or surrogate factor in the pathophysiology of CVD. Epidemiological observations suggest the theory of the role of inflammatory mediators in the development of cardiovascular events. This may support the idea that targeted anti-inflammatory therapies, on the background of traditional validated medical therapies, can play a significant role in prevention and even reduction of cardiovascular disorders. Many randomized controlled trials have shown that drugs commonly useful for primary and secondary prevention of CVD have an anti-inflammatory mechanism. Further, many anti-inflammatory drugs are being examined because of their potential to reduce the risk of cardiovascular problems. In this study, we review the process of inflammation in the development of cardiovascular events, both in vivo and clinical evidence in immunotherapy for CVD.

Serum Cystatin C and Arterial Stiffness in Middle-Aged and Elderly Adults without Chronic Kidney Disease: A Population-Based Study

BACKGROUND Cystatin C is a protease inhibitor that is increased in the serum of patients with chronic kidney disease (CKD) and is associated with an increased risk of developing cardiovascular disease (CVD). This study aimed to evaluate the association between serum levels of cystatin C and arterial stiffness, associated with dyslipidemia, obesity, and increased pulse pressure, in middle-aged and elderly individuals without CKD in a population in China. MATERIAL AND METHODS A cross-sectional population-based study included 1,138 patients aged ≥40 years without CKD, defined as an estimated glomerular filtration rate measured by serum creatinine (eGFRSCr) ≥60 ml/min/1.73 m². Study participants provided clinical details, including height and weight, and blood samples for serum measurements of cystatin C and lipid profiles and completed a clinical questionnaire. Pulse pressure was calculated as the mean systolic pressure (SBP) minus the diastolic pressure (DBP). Data underwent multivariate logistic regression analysis. RESULTS An increase in serum levels of cystatin C was associated with an increased risk of arterial stiffness. Each standard deviation in the increase of cystatin C resulted in a 22% increased risk of dyslipidemia, a 27% increased risk of obesity, and a 24% increased risk of increased pulse pressure, after adjusting for confounders. These associations were further confirmed in a sensitivity analysis by excluding participants with hypertension, diabetes, and patients with obstructive sleep apnea-hypopnea syndrome (OSAHS). CONCLUSIONS In middle-aged and elderly individuals without CKD, arterial stiffness determined by obesity, dyslipidemia and increased pulse pressure, was significantly associated with increased serum levels of cystatin C.

Interleukin-1 blockade in cardiovascular diseases: a clinical update

Interleukin-1 (IL-1) is the prototypical pro-inflammatory cytokine. IL-1 was implicated as a cardiodepressant factor in septic shock, and subsequent pre-clinical and clinical research has defined important roles for IL-1 in atherosclerosis, acute myocardial infarction (AMI), and heart failure (HF). IL-1 promotes the formation of the atherosclerotic plaque and facilitates its progression and complication. In a large phase III clinical trial of stable patients with prior AMI, blocking IL-1 activity using a monoclonal antibody prevented recurrent atherothrombotic cardiovascular events. IL-1 also contributes to adverse remodelling and left ventricular dysfunction after AMI, and in phase II studies, IL-1 blockade quenched the inflammatory response associated with ST-segment elevation AMI and prevented HF. In patients with established HF, IL-1 is thought to impair beta-adrenergic receptor signalling and intracellular calcium handling. Phase II studies in patients with HF show improved exercise capacity with IL-1 blockade. Thus, IL-1 blockade is poised to enter the clinical arena as an additional strategy to reduce the residual cardiovascular risk and/or address inflammatory cardiovascular conditions refractory to standard treatments. There are several IL-1 blockers available for clinical use, which differ in mechanism of action, and potentially also efficacy and safety. While IL-1 blockade is not immunosuppressive and not associated with opportunistic infections or an increased risk of cancer, fatal infections may occur more frequently while on treatment with IL-1 blockers likely due to a blunting of the inflammatory signs of infection leading to delayed presentation and diagnosis. We discuss the practical use of IL-1 blockade, including considerations for patient selection and safety monitoring.

Change of Inflammatory Factors in Patients with Acute Coronary Syndrome

BACKGROUND

Acute coronary syndrome (ACS) is closely related to unstable plaques and secondary thrombosis. The inflammatory cells in plaques and their inflammatory products may be the cause for plaque instability and ruptures. The study aimed to disclose the changes of inflammatory factors including serum intracellular adhesion molecule-1 (ICAM-1), chitinase-3-like protein 1 (YKL-40), and lipoprotein-associated phospholipase A2 (Lp-PLA2) in patients with ACS and its clinical significance.

METHODS

A total of 120 patients with coronary heart disease (CHD) were categorized into 2 groups: 69 with ACS and 51 with stable angina pectoris (SAP); 20 patients with chest pain and normal angiography served as a control group. The 120 patients with CHD were categorized into single-vessel disease group, double-vessel disease group, and three-vessel disease group based on the number of coronary artery stenosis. The severity of coronary artery stenosis was quantified based on coronary angiography using Gensini score. They were further divided into mild CHD group with its Gensini score <26 (n = 36), moderate CHD group with its Gensini score being 26-54 (n = 48) and severe CHD group with its Gensini score >54 (n = 36). Serum levels of ICAM-1, YKL-40, and Lp-PLA2 of different groups were determined by enzyme-linked immunosorbent assay. Correlation between ICAM-1, YKL-40, Lp-PLA2, and Gensini score was analyzed.

RESULTS

The levels of serum inflammatory factors ICAM-1, YKL-40, and Lp-PLA2 were significantly higher in the ACS group than those in control group and SAP group (all P < 0.05); and compared with control group, no significant difference was observed in terms of the serum ICAM-1, YKL-40, and Lp-PLA2 levels in the SAP group (P > 0.05).The levels of serum ICAM-1, YKL-40, and Lp-PLA2 were not significantly different among control group, single-vessel disease group, double-vessel disease group, and three-vessel disease group (all P > 0.05). The levels of serum ICAM-1, YKL-40, and Lp-PLA2 were not significantly different among control group, mild CHD group (Gensini score <26), moderate CHD group (Gensini score 26-54), and severe CHD group (Gensini score >54) (all P > 0.05). Nonparametric Spearman correlation analysis showed that the levels of serum ICAM-1, YKL-40, and Lp-PLA2 were not correlated with the Gensini score in CHD patients (r = 0.093, r = -0.149, and r = -0.085, all P > 0.05; respectively).

CONCLUSIONS

The serum levels of ICAM-1, YKL-40, and Lp-PLA2 were correlated with different clinical types of CHD, but not well correlated the severity and extent of artery stenosis, suggesting that ICAM-1, YKL-40, and Lp-PLA2 might be involved in occurrence of instability of atherosclerotic plaque, and might reflect the severity of CHD mostly through reflecting the plaque stability.

Prenatal and early postnatal stress and later life inflammation

BACKGROUND

Evidence suggests that maternal psychological and social stress during the prenatal period and in childhood represent an important condition that may adversely impact the anatomy and physiology of the developing child with implications for a number of health-related conditions and disorders. In a large prospective study, we aim to address if social stressors in the prenatal and early postnatal periods, as individual exposures as well as their accumulation, are associated with a range of inflammatory markers in late middle-aged offspring.

METHODS

The study sample includes Danish men and women born between 1959 and 1961 (n = 1206) who were members of the Copenhagen Perinatal Cohort and participated in the Copenhagen Aging and Midlife Biobank in 2009-2011 (age 49-52). Information on social stressors was collected through an interview with the mothers at the first antenatal visit and postnatal stressor data was collected at year one follow-up. A series of ordinary least square regression models were performed with the stress measures as the exposures and C-reactive protein (CRP), Interleukin-6 (IL-6), Interleukin-10 (IL-10), and Tumor necrosis factor α (TNF-α) separately as the outcomes.

RESULTS

The individual prenatal maternal stressors (being unmarried and having an unwanted pregnancy) and the prenatal index were associated with higher levels of CRP and IL-6 among offspring but not with IL-10 or TNF-α. Low social status, but not living away from parents or having an unmarried mother in the first year of life, was associated with higher levels of CRP and IL-6. The accumulation of social stressors in the early postnatal period was associated with higher levels of CRP and IL-6 but not IL-10 and TNF-α. The accumulation of stressors in the prenatal and postnatal periods combined was associated with higher levels of CRP and IL-6, but not with IL-10 or TNF-α.

CONCLUSIONS

The findings suggest that exposure to the accumulation of prenatal and early life stressors, is associated with higher levels of CRP and IL-6 in later life. This may indicate that the effects of early stressors on later inflammation operate through pathways with clear links to cardiovascular disease.

Mango Supplementation Has No Effects on Inflammatory Mediators in Obese Adults

This pilot study examined the effects of freeze-dried mango (Mangifera indica L.) supplementation on anthropometric measurements, lipid parameters, and inflammatory mediators in obese individuals. A total of 20 obese (body mass index [BMI]: 30-35 kg/m2) adults (11 men and 9 women), aged 20 to 50 years, received 10 g/d of ground freeze-dried mango pulp for 12 weeks. Anthropometrics, lipids, and inflammatory mediators were assessed at baseline and after 12 weeks of mango supplementation. There were no differences between baseline and final visits in inflammatory mediators, lipids, diet, physical activity, and anthropometrics. Relationships were present at baseline and final visits between adiponectin and high-density lipoprotein cholesterol and between leptin and fat mass. Correlations were found after 12 weeks of mango supplementation between leptin and the following variables: waist-to-height ratio, BMI, percent fat, and fat mass. Our findings demonstrate that 12-week consumption of freeze-dried mango by obese individuals has no impact on obesity-related inflammation.

Relationship between two blood stasis syndromes and inflammatory factors in patients with acute coronary syndrome

OBJECTIVE

To investigate the relationship between inflammatory factors and two Chinese medicine (CM) syndrome types of qi stagnation and blood stasis (QSBS) and qi deficiency and blood stasis (QDBS) in patients with acute coronary syndrome (ACS).

METHODS

Sixty subjects with ACS, whose pathogenesis changes belongs to qi disturbance blood stasis syndrome, were divided into 2 groups: 30 in the QSBS group and 30 in the QDBS group. The comparative analysis on them was carried out through comparing general information, coronary angiography and inflammatory factors including intracellular adhesion molecule-1 (ICAM-1), chitinase-3-like protein 1 (YKL-40) and lipoprotein-associated phospholipase A2 (Lp-PLA2).

RESULTS

Compared with the QSBS group, Lp-PLA2 and YKL-40 levels in the QDBS group showed no-significant difference (P>0.05); ICAM-1 was significantly higher in the QDBS group than in the QSBS group in the pathological processes of qi disturbance and blood stasis syndrome of ACS (P<0.05).

CONCLUSIONS

Inflammatory factor ICAM-1 may be an objective basis for syndrome typing of QSBS and QDBS, which provides a research direction for standardization research of CM syndrome types.

Risk Stratification for Primary Prevention of Coronary Artery Disease: Roles of C-Reactive Protein and Coronary Artery Calcium

Risk stratification of individuals at risk for atherosclerotic cardiovascular disease (ASCVD) plays an important role in primary prevention of cardiovascular disease. In addition to risk scores derived from conventional cardiovascular risk factors, high sensitivity C-reactive protein (hs-CRP) and coronary artery calcium (CAC) have emerged as two of the widely accepted non traditional risk factors for atherosclerotic disease that have shown incremental prognostic value in predicting cardiovascular events. This review systematically assesses the role of hs-CRP and CAC in various studies and demonstrates meta-analyses of the incremental prognostic value of hs-CRP and CAC in identifying patients at risk of future CVD events. Compared with this, CAC showed better incremental prognostic value and might be a better indicator of ASCVD risk in asymptomatic adults.

Reduced Kidney Function Is Associated With Cardiometabolic Risk Factors, Prevalent and Predicted Risk of Cardiovascular Disease in Chinese Adults: Results From the REACTION Study

Background

Chronic kidney disease (CKD) increases cardiovascular disease (CVD) risk. However, the association of mildly reduced kidney function with CVD risk is unclear.

Methods and Results

This study investigated the association of estimated glomerular filtration rate (eGFR) with prevalent CVDs, 10‐year Framingham risk for coronary heart disease (CHD), and 10‐year risk of atherosclerotic cardiovascular diseases (ASCVD) in 239 832 participants from the baseline of the Risk Evaluation of cAncers in Chinese diabeTic Individuals: a lONgitudinal study. With an interviewer‐assisted questionnaire, we collected information on CVD, including reported CHD, stroke, or myocardial infarction. Chronic Kidney Disease–Epidemiology Collaboration (CKD‐EPI) equation was used to calculate eGFR. Compared with individuals with normal eGFR (≥90 mL/min per 1.73 m²), those with decreased eGFR (75–89, 60–74, and <60 mL/min per 1.73 m²) had higher risk of prevalent obesity, diabetes mellitus, hypertension, and dyslipidemia in both men and women (P for trend all <0.001). Moreover, a significantly higher 10‐year Framingham risk for CHD and 10‐year risk for ASCVD was observed in both men and women with mildly decreased eGFR (60–89 mL/min per 1.73 m²).

Conclusions

Even mildly reduced eGFR (under 90 mL/min per 1.73 m²) is associated with elevated 10‐year Framingham risk for CHD and 10‐year ASCVD risk among Chinese adults.

Exposure to polycyclic aromatic hydrocarbons and serum inflammatory markers of cardiovascular disease

Polycyclic aromatic hydrocarbons (PAHs) are environmental and occupational carcinogens produced by the incomplete combustion of organic materials, such as coal and petroleum product combustion, tobacco smoking, and food cooking, that may be significant contributors to the burden of cardiovascular disease in human populations. The purpose of this study was to investigate associations between ten monohydroxy urinary metabolites of four PAHs and three serum biomarkers of cardiovascular disease (fibrinogen, homocysteine, and white blood cell count). Using data on 3219 participants aged 20 years and older from the National Health and Nutrition Examination Survey (NHANES) 2001-2004 dataset, the associations between PAH metabolites and serum inflammatory markers were analyzed using the Spearman correlations and multiple linear regression modeling. The PAH metabolites of naphthalene, fluorene, phenanthrene, and pyrene each showed both positive and negative correlations with homocysteine, fibrinogen, and white blood cell count (correlation coefficient range: -0.077-0.143) in nonsmoking participants. Using multiple linear regression models adjusted for age, gender, race/ethnicity, and body mass index, estimates of weighted geometric means of inflammatory marker levels were not significantly different between high and low levels (75th vs. 25th percentiles) for all PAH metabolites in nonsmoking subjects. The results of this study do not provide evidence for a relationship between PAH exposure (as measured by urinary levels of PAH metabolites) and serum biomarkers of cardiovascular disease after controlling for tobacco use.

Clustering of depression and inflammation in adolescents previously exposed to childhood adversity

BACKGROUND

There is mounting interest in the hypothesis that inflammation contributes to the pathogenesis of depression and underlies depressed patients' vulnerability to comorbid medical conditions. However, research on depression and inflammation has yielded conflicting findings, fostering speculation that these conditions associate only in certain subgroups, such as patients exposed to childhood adversity.

METHODS

We studied 147 female adolescents. All were in good health at baseline but at high risk for depression because of family history or cognitive vulnerability. Subjects were assessed every 6 months for 2.5 years, undergoing diagnostic interviews and venipuncture for measurement of two inflammatory biomarkers, C-reactive protein (CRP) and interleukin-6 (IL-6). Childhood adversity was indexed by parental separation, low socioeconomic status, and familial psychopathology.

RESULTS

Multilevel models indicated that childhood adversity promotes clustering of depression and inflammation. Among subjects exposed to high childhood adversity, the transition to depression was accompanied by increases in both CRP and IL-6. Higher CRP remained evident 6 months later, even after depressive symptoms had abated. These lingering effects were bidirectional, such that among subjects with childhood adversity, high IL-6 forecasted depression 6 months later, even after concurrent inflammation was considered. This coupling of depression and inflammation was not apparent in subjects without childhood adversity.

CONCLUSIONS

These findings suggest that childhood adversity promotes the formation of a neuroimmune pipeline in which inflammatory signaling between the brain and periphery is amplified. Once established, this pipeline leads to a coupling of depression and inflammation, which may contribute to later affective difficulties and biomedical complications.

Von Willebrand factor predicts major bleeding and mortality during oral anticoagulant treatment

AIMS

Oral anticoagulation (OAC), predominantly with warfarin, is an effective treatment to prevent thromboembolic events. Serious bleeding is a frequent and feared treatment complication. In this longitudinal cohort study of OAC-treated patients, we aimed to evaluate the relationship between von Willebrand factor (VWF) levels and risk of bleeding complications, cardiovascular mortality and all-cause mortality.

METHODS AND RESULTS

A total of 719 patients receiving warfarin treatment were observed for a mean duration of 4.2 years. All bleeding complications causing hospitalization were registered and classified into clinically relevant bleeding (CRB) and major bleeding. Ischaemic stroke, peripheral arterial embolism, myocardial infarction, and death were also recorded. We identified 113 cases of CRB and 73 of major bleeding. In total, 161 deaths occurred during follow-up with cardiovascular disease identified as the cause of death in 110 patients. Patients in the highest tertile of VWF had a significantly increased risk of bleeding complications: hazard ratio (HR) 2.53 (95% CI 1.41-4.56) for major bleeding and HR 2.19 (95% CI 1.38-3.48) for CRB. VWF, expressed either in tertiles or as a continuous variable, showed a significant association with cardiovascular mortality (HR 1.68, 95% CI 1.40-2.01) and all-cause mortality (HR 1.77, 95% CI 1.52-2.05). In multivariate Cox regression analysis, the findings remained significant after adjusting for age, high-sensitivity C-reactive protein and creatinine.

CONCLUSIONS

Patients with high levels of VWF had an increased risk of bleeding complications, cardiovascular mortality and all-cause mortality during OAC treatment. Our findings imply that the use of VWF as a risk marker for thromboembolic events is complicated by the association of VWF with bleeding complications.

Assessment of high-sensitivity CRP as a marker of micro-inflammation in irritable bowel syndrome

BACKGROUND

The diagnosis of irritable bowel syndrome (IBS) is symptom-based. Although considered a functional disease, accumulating evidence supports a low-grade gut inflammation as an element of its pathophysiology. Thus, high-sensitivity C-reactive protein (hs-CRP), a marker of micro inflammation, may be elevated in IBS. Our aim was to assess whether hs-CRP is higher in IBS patients compared to healthy controls (HC) and does it differ among the IBS clinical subgroups and correlate with disease severity.

METHODS

A diagnostic case control study was conducted in two gastroenterology departments. Eighty-eight IBS patients who were recruited prospectively answered the Rome III diagnostic questionnaire. They all completed the Functional Bowel Disorder Severity Index (FBDSI), dietary, and general health questionnaires. All patients underwent blood sampling for hs-CRP levels. Each IBS patient was matched to four HC by age, gender, and BMI. Blood samples were obtained from the HC at a periodic health survey.

KEY RESULTS

The mean hs-CRP level in the IBS group was significantly higher than in HC (1.17±1.26mg L(-1) vs 0.72±0.91mg L(-1) respectively, P=0.001). Hs-CRP levels were highest in patients with diarrhea-predominant IBS and in patients with greater disease severity. A cut-off value of 1.08mg L(-1) had a sensitivity of 60.2% and a specificity of 68% for differentiating IBS from HC.

CONCLUSIONS & INFERENCES

Hs-CRP levels are higher in IBS patients than HC, but still in the normal laboratory range. This may reflect the low-grade gut inflammation believed to occur in IBS and support its existence.

Status and prospects for discovery and verification of new biomarkers of cardiovascular disease by proteomics

Despite unmet needs for cardiovascular biomarkers, few new protein markers have been approved by the US Food and Drug Administration for the diagnosis or screening of cardiovascular diseases. Mass spectrometry-based proteomics technologies are capable of identifying hundreds to thousands of proteins in cells, tissues, and biofluids. Proteomics may therefore provide the opportunity to elucidate new biomarkers and pathways without a prior known association with cardiovascular disease; however, important obstacles remain. In this review, we focus on emerging techniques that may form a coherently integrated pipeline to overcome present limitations to both the discovery and validation processes.

Atherosclerosis drug development in jeopardy: the need for predictive biomarkers of treatment response

The limited predictability of phase II biomarkers for atherosclerosis outcomes in phase III studies stands in contrast to the number and varied types of biomarkers--soluble, imaging, and functional--that have been used in a diverse array of trials. Although collectively abundant, these biomarker data exist in a fragmented state. Most biomarkers are studied one at a time, only measure a specific aspect of atherosclerosis, are not integrated in a substantive way, and compete with one another for validation; in the end, progress is slow. The proposed solution from the Atherosclerosis Working Group, a committee of experts from academia, the pharmaceutical industry, government, and the nonprofit sector and managed by the Foundation for the National Institutes of Health Biomarkers Consortium, is to integrate these different measures into an in silico model of atherosclerosis. Through integration of diverse biomarker measurements and outcomes in silico, we may be able to improve trial design as well as the predictive power of short-term markers for longer-term outcomes.

Inflammatory markers in coronary heart disease

INTRODUCTION

Inflammation plays a key role in the development of atherosclerosis and coronary heart disease (CHD).

SOURCES OF DATA

Peer-reviewed studies published in English-language journals were reviewed with a focus on C-reactive protein (CRP) and lipoprotein-associated phospholipase A(2) (Lp-PLA2).

AREAS OF AGREEMENT

Elevated levels of serum CRP and Lp-PLA2 are associated with an increased risk of incident CHD events in both primary and secondary prevention studies across a wide range of age, gender and ethnic groups.

AREAS OF CONTROVERSY

The utility of inflammatory markers in predicting CHD risk when added to traditional risk factors is under debate. They are most useful in subjects in the intermediate-risk category.

GROWING POINTS

Treatment with a statin in subjects with elevated CRP but without hyperlipidemia can reduce the risk of CHD.

AREAS TIMELY FOR DEVELOPING RESEARCH

Extensive research is under way to identify additional novel serum markers with higher specificity for coronary artery plaque inflammation. Specific inhibitors against vascular inflammation in combination with medications to lower low-density lipoprotein cholesterol, i.e. statins, may help prevent cardiovascular events in the future.

[Perioperative myocardial damage in non-cardiac surgery patients]

Perioperative myocardial damage occurs with a high incidence depending on the operative procedure and the patients examined and is considered to be among the most relevant risk factors for increased perioperative morbidity and mortality in patients undergoing non-cardiac surgery. The pathophysiology of myocardial damage in the perioperative period is still not well understood. Both ischemia with and without acute coronary occlusion and non-ischemic stimuli can put a substantial strain on the heart in the perioperative period. However, in many cases the clinical presentation does not allow a clear differentiation between ischemic and non-ischemic myocardial damage. In the majority of cases perioperative myocardial infarctions occur with only mild or even without any clinical symptoms. This is probably due to a considerable difference in phenotype and pathophysiology between perioperative and non-perioperative myocardial infarctions. As a result of this unexplained etiology of perioperative myocardial infarction it remains an open question whether the contemporary diagnostic and therapeutic recommendations for the acute coronary syndrome can be extrapolated to the perioperative situation. The present review reflects the current state of knowledge and presents an optional approach to the diagnosis and therapy of perioperative myocardial injury.

Depression and the metabolic syndrome: gender-dependent associations

This study was designed to test the extent to which depressive symptoms are associated with the presence of the metabolic syndrome (MS) and each of its components, and whether these relationships are gender dependent. Participants were apparently healthy employed men (N=2,355) and women (N=1,525) who underwent a routine health check between the years 2003 and 2005. We used logistic regression analysis, predicting the MS by depressive symptoms, as assessed by the Patient Health Questionnaire, and the following control variables: age, education, smoking status, physical exercise, anxiety, and burnout. As hypothesized, we found that depression among women, but not men, was associated with a 1.94-fold risk of having the MS, and with an elevated risk of having two of its five components: elevated waist circumference (odds ratio, OR=2.23) and elevated glucose levels (OR=2.44). In addition, a positive trend was observed toward an association with the other three components: low high-density lipoprotein, hypertension, and elevated triglycerides. Among men depression was associated with elevated waist circumference only (OR=1.77). These findings suggest that especially among women, the association between depression and cardiovascular diseases might be linked to metabolic processes. If replicated in longitudinal studies, these findings may have important health-care policy implications with regard to depression management interventions.

Computational biology for cardiovascular biomarker discovery

Computational biology is essential in the process of translating biological knowledge into clinical practice, as well as in the understanding of biological phenomena based on the resources and technologies originating from the clinical environment. One such key contribution of computational biology is the discovery of biomarkers for predicting clinical outcomes using 'omic' information. This process involves the predictive modelling and integration of different types of data and knowledge for screening, diagnostic or prognostic purposes. Moreover, this requires the design and combination of different methodologies based on statistical analysis and machine learning. This article introduces key computational approaches and applications to biomarker discovery based on different types of 'omic' data. Although we emphasize applications in cardiovascular research, the computational requirements and advances discussed here are also relevant to other domains. We will start by introducing some of the contributions of computational biology to translational research, followed by an overview of methods and technologies used for the identification of biomarkers with predictive or classification value. The main types of 'omic' approaches to biomarker discovery will be presented with specific examples from cardiovascular research. This will include a review of computational methodologies for single-source and integrative data applications. Major computational methods for model evaluation will be described together with recommendations for reporting models and results. We will present recent advances in cardiovascular biomarker discovery based on the combination of gene expression and functional network analyses. The review will conclude with a discussion of key challenges for computational biology, including perspectives from the biosciences and clinical areas.

Cardiovascular biomarkers in groups of established smokers after a decade of smoking

To investigate tools for evaluation of smoking-associated disease initiation and progression, we examined basic clinical parameters and biomarkers of cardiovascular disease risk, in a group of healthy volunteers with an average 10-year smoking history. A small cross-sectional study of never-smokers, moderate smokers and smokers was performed. Caucasians were recruited to match pre-defined cigarette tar yields and cigarettes smoked per day. For haematological parameters, significant differences between never-smokers and all female smokers combined were seen for haemoglobin concentration, haematocrit, total leucocyte count, neutrophil count and lymphocyte count. For all male smokers combined, only total leucocyte count was statistically different. Analysis of exhaled CO and other smoke exposure biomarker (nicotine and its metabolites) data showed a statistically significant increase in all groups of smokers with a trend related to the number of cigarettes smoked per day. Thromboxane urinary metabolites 11-dehydro-thromboxane B(2) and 2,3-dinor-thromboxane B(2) were statistically significantly elevated in smokers. Significant statistical differences between smokers with approximately 10 years of smoking history and non-smokers in white cells count, hemoglobin and thromboxane turnover were seen, although they did not reach levels associated with overt diseases. These data could provide insight into early biomarkers predictive of risk for coronary and vascular disease.

The association of active and passive smoking with peripheral arterial disease: results from NHANES 1999-2004

We aim to quantify the association between different forms of tobacco use and peripheral arterial disease (PAD) and to characterize the association between secondhand smoke exposure and PAD in a large nationally representative sample of the US population. We observed significant associations between current and former cigarette smoking and PAD. The association between noncigarette forms of tobacco and PAD was not significant even after adjustment for clinical and demographic variables. Secondhand smoke was not significantly associated with PAD. Interestingly, a ;;threshold phenomenon'' for tobacco exposure was demonstrated for PAD occurrence. Individuals with serum cotinine >155 ng/ mL were at significantly higher risk of having PAD as compared with a nonexistent or a minimal risk below this threshold value. Lack of association between PAD and secondhand smoke exposure in conjunction with the threshold phenomenon described above leads us to speculate existence of striking differences between the systemic circulation and lower extremity vasculature in terms of pathogenesis of atherosclerosis.

Socioeconomic position and inflammatory and immune biomarkers of cardiovascular disease: applications to the Panel Study of Income Dynamics

Biomarkers are an important aspect of research linking psychosocial stress and health. This article aims to characterize the biological pathways that may mediate the relationship between socioeconomic position (SEP) and cardiovascular disease (CVD) and address opportunities for further research within the Panel Study of Income Dynamics (PSID), with a focus on psychosocial stressors related to SEP. We review the literature on CVD biomarkers, including adhesion and proinflammatory molecules (interleukin-6, other cytokines, C-reactive proteins, fibrinogen, etc.) and microbial pathogens. The impact of socioeconomic determinants and related psychosocial stressors on CVD biomarkers mediated by behavioral and central nervous system pathways are described. We also address measurement and feasibility issues, including specimen collection methods, processing and storage procedures, laboratory error, and within-person variability. In conclusion, we suggest that PSID consider adding important assessments of specific CVD biomarkers and mediating behavioral measures, health, and medications that will ultimately address many of the gaps in the literature regarding the relationship between SEP and cardiovascular health.

Ten-year risk prediction in French men using the Framingham coronary score: results from the national SU.VI.MAX cohort

OBJECTIVE

To evaluate the ability of the Framingham risk function to predict the 10-year coronary heart disease (CHD) risk in French men.

METHODS

3440 men, aged 45 to 60 years, free of CHD at baseline, were selected from the SU.VI.MAX cohort. The expected number of event, obtained from applying the Framingham risk score to the baseline SU.VI.MAX biological and clinical data of 1994/1996, were compared to the actual risks observed in the cohort. The accuracy of the Framingham risk function was assessed using the area under the receiver operating characteristic (ROC) curve.

RESULTS

The overall Framingham risk function predicted twice as many CHD events than observed. The area under the ROC curve for Framingham risk score was 74%.

CONCLUSION

The Framingham risk function may discriminate between high risk from low risk subjects, but it is not valid for estimating absolute 10-year CHD risk in this French population.

Association between C-reactive protein level and peripheral arterial disease among US adults without cardiovascular disease, diabetes, or hypertension

BACKGROUND

Inflammatory processes are implicated in the development and progression of atherosclerotic cardiovascular disease (CVD). C-reactive protein (CRP), a specific marker of inflammation, has been found to be related to CVD and subclinical atherosclerosis, including peripheral arterial disease (PAD). However, it is not entirely clear whether CRP levels are related to subclinical CVD independent of traditional risk factors, including diabetes and hypertension. We examined the association between CRP levels and PAD among US adults free of CVD, diabetes, and hypertension.

METHODS

Cross-sectional study was performed among 1611 National Health and Nutrition Examination Survey 1999-2002 participants aged > or = 40 years and without CVD, diabetes, or hypertension. Main outcome of interest was PAD defined as ankle-brachial index < 0.9.

RESULTS

Higher CRP levels were positively associated with PAD, independent of smoking, waist circumference, body mass index, blood pressure, glycosylated hemoglobin, serum total cholesterol, and other confounders. Multivariable odds ratio (95% CI) comparing quartile 4 of CRP (> 0.54 mg/dL) to quartile 1 (< 0.09 mg/dL) was 6.38 (1.77-22.96); P trend = .005. This association persisted in separate analysis in men and women. Furthermore, the results were consistent in subgroup analyses by categories of age, education, smoking, and body mass index. In nonparametric models, the positive association between CRP and PAD seemed to be present across the full range of CRP without any apparent threshold.

CONCLUSIONS

Higher CRP levels are associated with PAD among US adults free of CVD, diabetes, and hypertension. These results suggest that inflammatory mechanisms related to atherosclerosis may be operative even among clinically healthy adults.

Cellular alternans: a mechanism linking calcium cycling proteins to cardiac arrhythmogenesis

Essentially all previous research on alternans has been restricted to normal myocardium, whereas sudden cardiac death (SCD) occurs most commonly in patients with ventricular dysfunction (i.e., heart failure), which is associated with marked disruption of proteins responsible for normal calcium cycling in myocytes. Several lines of evidence from studies in normal hearts suggest a link between impaired calcium cycling which characterizes ventricular mechanical dysfunction and impaired calcium cycling that is responsible for alternans. In normal myocardium, cells which exhibit the slowest calcium cycling, and not the slowest repolarization, are most susceptible to alternans. Decreased expression of key calcium cycling proteins is observed in alternans-prone cells. Sarcoplasmic reticulum ATPase (SERCA2a) expression is decreased, suggesting a mechanism for the slower sarcoplasmic reticulum (SR) calcium reuptake observed in alternans-prone cells. In addition, diminished ryanodine receptor (RyR) function leading to abnormal calcium release from the SR is also linked to cellular alternans. Although impaired contractile function clearly predisposes to SCD, the mechanisms linking mechanical to electrophysiological dysfunction in the heart are unclear. We propose that cellular calcium alternans may be an important mechanism linking mechanical dysfunction to cardiac arrhythmogenesis.

New biochemical markers: from bench to bedside

BACKGROUND

Evaluation of patients presenting to hospital with chest pain or other signs or symptoms suggesting acute coronary syndrome (ACS) is problematic, time-consuming and sometimes expensive, even if new biochemical markers, such as troponins, have improved the ability to detect cardiac injury. However, patients with normal troponin values are not necessarily risk-free for major cardiac events.

METHODS

Recent investigations indicate that the overall patient risk may be assessed earlier than before, thanks to new knowledge acquired concerning the pathobiology of atherosclerosis and molecular events involved in the progression of disease, thus allowing the development of new biochemical markers. Some selected markers are released during the different phases of development of cardiovascular disease and may be useful for the diagnosis of patients with cardiovascular disease. In particular, the identification of emerging markers that provide relevant information on the inflammatory process, and the development of biomarkers whose circulating concentrations suggest the status of plaque instability and rupture, seems to be of particular value in prognosis and risk stratification. The overall expectations for a cardiovascular biochemical marker are not only its biological plausibility but also the availability at a reasonable cost of rapid, high quality assays, and their correct interpretation by clinicians using optimal cut-offs.

CONCLUSION

The crossing from bench to bedside for each new marker discovered, must be associated with concurrent advances in the characterization of analytical features and the development of routine assay, in the assessment of analytical performance and in interpretative reporting of test results as well as in the training of physicians to use the array of biomarkers available appropriately and to interpret them correctly. This approach calls for the coordinated support of clinicians, technology experts, statisticians and the industry so that new biochemical developments can be of optimal value.

The epidemiology of Lp-PLA2: Distribution and correlation with cardiovascular risk factors in a population-based cohort

Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) is an enzyme that is produced by inflammatory cells (macrophages, T-lymphocytes and mast cells) and hydrolyzes oxidized phospholipids in LDL. Several epidemiology studies indicate that Lp-PLA(2) appears to be an independent marker of cardiovascular risk. This study was conducted to define the distribution of Lp-PLA(2) in a large population-based cohort and to determine associations between Lp-PLA(2) and other risk factors for CVD. The study group consisted of participants from the Malmö Diet and Cancer study (1992-1994). Lp-PLA(2) (activity and mass) was measured from samples obtained at baseline for 5402 participants (3167 women). A strong correlation was observed between Lp-PLA(2) activity and mass in this study (r=0.57). Highest correlations were observed between Lp-PLA(2) activity and LDL (r=0.45) and LDL/HDL ratio (r=0.54) and a strong inverse correlation to HDL (r=-0.31). The correlations between Lp-PLA(2) mass and lipids were not as strong as the correlation between activity and lipids. Lp-PLA(2) activity and mass were correlated with increased ultrasound determined carotid intima-media thickness. We conclude that Lp-PLA(2) is strongly correlated with several cardiovascular risk factors, especially lipid fractions, and with the degree of carotid artery atherosclerosis. However, the measured variables accounted for only 19% and 35% of the variation in Lp-PLA(2) mass and activity respectively.

Coronary artery disease screening, treatment, and follow-up

Heart disease causes more than 30% of US deaths. Evidence-based screening allows a primary care physician to identify patients at risk before symptom onset. Estimating disease probability before screening affects which tests are appropriate. Low-risk adults should not be screened. ECG, exercise treadmill testing, cardiac stress imaging, electron beam computed tomography, and angiography are possible screening tests. Special populations may have additional screening indications. Management of patients who have coronary artery disease includes antiplatelet therapy; aggressive lipid lowering; management of hypertension with beta blockers and angiotensin-converting enzyme inhibitors; risk factor management, including smoking cessation, diet, and exercise; symptom management; and sometimes revascularization. Primary care physicians are well-suited to the monitoring and care of patients who have known coronary artery disease.

Intermittent peripheral tissue ischemia during coronary ischemia reduces myocardial infarction through a KATP-dependent mechanism: first demonstration of remote ischemic perconditioning

Remote ischemic preconditioning reduces myocardial infarction (MI) in animal models. We tested the hypothesis that the systemic protection thus induced is effective when ischemic preconditioning is administered during ischemia (PerC) and before reperfusion and examined the role of the K(+)-dependent ATP (K(ATP)) channel. Twenty 20-kg pigs were randomized (10 in each group) to 40 min of left anterior descending coronary artery occlusion with 120 min of reperfusion. PerC consisted of four 5-min cycles of lower limb ischemia by tourniquet during left anterior descending coronary artery occlusion. Left ventricular (LV) function was assessed by a conductance catheter and extent of infarction by tetrazolium staining. The extent of MI was significantly reduced by PerC (60.4 +/- 14.3 vs. 38.3 +/- 15.4%, P = 0.004) and associated with improved functional indexes. The increase in the time constant of diastolic relaxation was significantly attenuated by PerC compared with control in ischemia and reperfusion (P = 0.01 and 0.04, respectively). At 120 min of reperfusion, preload-recruitable stroke work declined 38 +/- 6% and 3 +/- 5% in control and PerC, respectively (P = 0.001). The force-frequency relation was significantly depressed at 120 min of reperfusion in both groups, but optimal heart rate was significantly lower in the control group (P = 0.04). There were fewer malignant arrhythmias with PerC during reperfusion (P = 0.02). These protective effects of PerC were abolished by glibenclamide. Intermittent limb ischemia during myocardial ischemia reduces MI, preserves global systolic and diastolic function, and protects against arrhythmia during the reperfusion phase through a K(ATP) channel-dependent mechanism. Understanding this process may have important therapeutic implications for a range of ischemia-reperfusion syndromes.

Gender-Specific Prediction of Cardiac Disease

Current guidelines recommend targeting the intensity of preventive cardiovascular interventions to the level of the patient's risk, which is usually obtained from a global risk score such as the Framingham equations. However, a large proportion of asymptomatic U.S. women (approximately 80-90%) are classified as low risk by the Framingham score, although they have a 1 in 2 chance of dying from cardiovascular disease (CVD) during their lifetime. A promising avenue for improving CVD risk stratification has come from recent studies evaluating the prognostic value of exercise testing in asymptomatic populations using test variables that are not related to exercise-induced ST-segment depression. In particular, it has been shown that 2 easily obtained noninvasive measures, low exercise capacity and slow heart rate recovery, have been linked to increased CVD and all-cause death in both women and men. These 2 simple yet powerful measures of risk that are readily available are useful tools for the practicing cardiologist who desires more accurate assessment of risk in a female patient, particularly if she is deemed as intermediate risk by the Framingham score. In addition, both exercise capacity and heart rate recovery are at least partially modifiable by regular physical activity. Exercise recommendations of at least 30 minutes of moderate physical activity most days of the week have been associated with 30% to 50% reductions in coronary events and coronary mortality and should be recommended to all patients regardless of their Framingham risk score.

Systemic immune mediators and lifestyle changes in the prevention of type 2 diabetes: results from the Finnish Diabetes Prevention Study

The Finnish DPS (Diabetes Prevention Study) demonstrated that lifestyle intervention, aimed at increasing physical activity, improving diet, and decreasing body weight, reduced the incidence of type 2 diabetes in individuals with overweight and impaired glucose tolerance by 58%. Here, we studied which immunological markers at baseline predicted subsequent type 2 diabetes and whether there are immunologically defined subsets of subjects who are more or less responsive to the protective effects of lifestyle intervention. We randomly assigned 522 participants to a control group (n = 257) or a lifestyle intervention group (n = 265). Immunological parameters at baseline included high-sensitivity C-reactive protein (CRP), serum amyloid A, interleukin-6, regulated on activation normal T-cell expressed and secreted (RANTES), macrophage migration inhibitory factor (MIF), and soluble intercellular adhesion molecule. In the control group, CRP was the best immunological predictor for progression to overt type 2 diabetes. In the intervention group, progression to type 2 diabetes was significantly higher in subjects with the highest RANTES concentrations and was lower in subjects with the highest MIF levels. Ratios of RANTES to MIF in the upper tertile were highly predictive of incident type 2 diabetes in the intervention group (P = 0.006), whereas the association was less pronounced in the control group (P = 0.088). Thus, systemic concentrations of immune mediators appear to be associated with the progression to type 2 diabetes and the prevention of type 2 diabetes by lifestyle changes.

Additive value of immunoassay-measured fibrinogen and high-sensitivity C-reactive protein levels for predicting incident cardiovascular events

BACKGROUND

Current guidelines suggest measuring high-sensitivity C-reactive protein (hs-CRP) as an aid to coronary risk assessment in adults without cardiovascular disease (CVD). Whether other inflammatory biomarkers, such as fibrinogen, add further prognostic information is uncertain.

METHODS AND RESULTS

In a prospective study of 27,742 initially healthy middle-aged women, the associations of baseline immunoassay fibrinogen and hs-CRP measurements with incident CVD were examined over a 10-year follow-up period. Compared with women in the bottom biomarker quintile, age-adjusted hazard ratios (95% confidence intervals [CIs]) for incident CVD for quintiles 2 to 5 of fibrinogen were 1.10 (0.86 to 1.41), 1.30 (1.03 to 1.65), 1.46 (1.16 to 1.85), and 2.43 (1.95 to 3.02); for hs-CRP they were 1.48 (1.06 to 2.05), 1.70 (1.24 to 2.33), 2.20 (1.63 to 2.96), and 3.24 (2.43 to 4.31). After further adjustment for established risk factors, both biomarkers remained associated (P for trend < or = 0.001) with incident CVD (hazard ratio, 1.35; 95% CI, 1.07 to 1.71 for top fibrinogen quintile; and hazard ratio, 1.68; 95% CI, 1.22 to 2.29 for top hs-CRP quintile compared with the bottom quintiles). Further adjustment for the other biomarker resulted in hazard ratios of 1.23 and 1.56 (P for trend = 0.02 and 0.002), respectively. Although fibrinogen correlated positively with hs-CRP (rs = 0.41, P < 0.001), the highest CVD risk was associated with elevated levels of both fibrinogen and hs-CRP: age-adjusted hazard ratio of 3.45 (95% CI, 2.60 to 4.57) for women with fibrinogen > 393 mg/dL and hs-CRP > 3 mg/L compared with < 329 mg/dL and < 1 mg/L, respectively.

CONCLUSIONS

In this cohort of initially healthy women, baseline levels of fibrinogen measured with a high-quality immunoassay provided additive value to hs-CRP and traditional risk factors in predicting incident CVD.

Overview of hemostatic factors involved in atherosclerotic cardiovascular disease

Hemostatic factors associated with the development of cardiovascular disease (CVD) include fibrinogen, von Willebrand factor, tissue plasminogen activator (tPA) antigen, plasminogen activator inhibitor-1 (PAI-1), and factor VII. Each SD increment of these increases the association by 24-30%. Most hemostatic factors are intercorrelated with inflammatory markers [e.g., C-reactive protein (CRP)] and LDL cholesterol. Fibrinogen seems the most fundamental hemostatic risk factor for CVD. The Framingham Study reaffirms the significant linear risk factor trends across fibrinogen tertiles (P< 0.001) for age, body mass index, smoking, diabetes mellitus, total cholesterol, HDL cholesterol, and TG in both sexes. Fibrinogen may also directly increase CVD risk because of its role in platelet aggregation, plasma viscosity, and fibrin formation. Fibrinogen is also an acute-phase reactant that is elevated in inflammatory states. Fibrinogen mediates the thrombogenic effect of other risk factors. Fibrinogen levels increase with the number of cigarettes smoked and quickly fall after smoking cessation. This rapid fibrinogen decline may be a mechanism for CVD risk reduction after smoking cessation. Weight loss is accompanied by reduced fibrinogen. The correlation between fibrinogen and LDL cholesterol suggests that lipid-imposed CVD risk is mediated partly through fibrinogen. Hyperreactive platelets of diabetics may result in part from their increased fibrinogen. Elevated fibrinogen and CRP of unstable angina suggest an acute-phase reaction. Prevalence, case-control, angiographic, and echocardiogram investigations incriminate hemostatic and inflammatory markers as strong independent risk factors for initial and recurrent CVD. Framingham Study data indicate that each SD increase in fibrinogen imposes a 20% independent increment in risk. It may be concluded that fibrinogen and CRP determination may be useful screening tools to identify individuals at added risk for thrombotic complications of CVD.