Serum neopterin and complex stenosis morphology in patients with unstable angina

Assessment of Inflammatory and Oxidative Stress Biomarkers for Predicting of Patients with Asymptomatic Carotid Artery Stenosis

Background/Objectives: Asymptomatic carotid artery stenosis is usually detected by physicians in patients, coincidentally, during an ultrasound examination of the neck. Therefore, measurable biomarkers in blood are needed to define the presence and severity of atherosclerotic plaque in patients to identify and manage it. We hypothesized that biomarkers that indicate pathways related to the pathogenesis of atherosclerosis could be used to identify the presence and severity of atherosclerotic plaque. For this purpose, the levels of participants' inflammatory and oxidative stress biomarkers were determined. Kynurenine/tryptophan and neopterin levels were measured as relatively new biomarkers of inflammation in this study. Methods: Our study included 57 patients diagnosed with asymptomatic carotid artery stenosis and 28 healthy volunteers. Blood kynurenine and tryptophan levels were measured with LCMS/MS. Blood catalase, total superoxide dismutase (t-SOD), glutathione peroxidase (GPx), malondialdehyde, and neopterin levels were measured using the ELISA assay method. Result: The kynurenine/tryptophan ratio reflecting IDO activity was higher in patients than in healthy volunteers. Decreased tryptophan levels and increased kynurenine and neopterin levels were observed in patients who underwent carotid endarterectomy. In patients, catalase, t-SOD, and malondialdehyde levels were higher, while GPx activity was lower. These differences were found to be more significant in patients who underwent carotid endarterectomy. Conclusions: Increased kynurenine/tryptophan ratio and neopterin levels in patients with asymptomatic carotid artery stenosis were associated with the inflammatory status of the patients. Oxidative stress and inflammatory biomarkers can be considered effective diagnostic and severity indicators for asymptomatic carotid artery stenosis.

Evaluation of neopterin levels and kynurenine pathway in patients with acute coronary syndrome

BACKGROUND

Coronary atherosclerosis is the leading cause of coronary artery disease. Several investigations have indicated that tear-sensitive plaques contain macrophages and T cells. Neopterin is an essential cellular immune response biomarker. The main goal of this study was to see if there were any changes in biomarkers like unconjugated pteridines, neopterin, and biopterin, as well as kynurenine pathway enzymes like indoleamine 2,3-dioxygenase (IDO), which catalyzes the rate-limiting step in tryptophan degradation, in patients with the acute coronary syndrome (ACS) caused by angiographic atherosclerosis.

METHODS

High-performance liquid chromatography was used to determine the amounts of neopterin, biopterin, and creatinine in urine samples, as well as tryptophan and kynurenine in serum samples. The enzyme-linked immunosorbent assay was used to assess the amounts of neopterin in serum samples. The measured parameters were evaluated between ACS patients and controls.

RESULTS

The measured levels of neopterin, biopterin and the kynurenine to tryptophan ratio reflecting IDO activity, and the specifically known biomarkers such as cardiac troponin, creatine kinase, myoglobin, and natriuretic peptides are statistically higher in ACS patients compared to control subjects. On the other hand, the measured parameters are inadequate to classify the conventional kinds of ACS, ST-elevation- and non-ST-elevation- myocardial infarction.

CONCLUSIONS

The study found that determining and using neopterin and IDO parameters as biomarkers in individuals with the ACS can support traditional biomarkers. However, it can be concluded that evaluating pteridine biomarkers solely have no privilege to clinical findings in ACS diagnosis and classification.

The role of immune activation in endotoxin-induced atherogenesis

Some infectious agents may contribute to atherosclerosis by maintaining a heightened state of inflammatory response. Although the risk for atherosclerosis was associated with elevated plasma levels of endotoxin, it is difficult to firmly establish what place endotoxin assumes in the etiology of this disease. As the ability for endotoxin to promote disease may depend on its ability to initiate an inflammatory response, it may be controlled by additional regulatory factors. We measured plasma levels of endotoxin and serum levels of neopterin and soluble interleukin-2 receptor in a random population of 402 men and women, 50—79 years old at the 1990 baseline evaluation (Bruneck Study). End point of the prospective survey was incident (early) atherosclerosis in the carotid arteries as assessed with duplex ultrasound. Subjects with high endotoxin levels (90th percentile) in combination with low neopterin or soluble interleukin-2 receptor levels (below median) did not differ from those with low endotoxin in their risk of incident atherosclerosis. The risk associated with high endotoxin, however, was markedly elevated in subjects with high (above median) neopterin or soluble interleukin-2 receptor levels. The study provides epidemiological evidence that the atherogenic potential of endotoxemia is affected by concomitant immune activation.

Folate, neopterin and kynurenine pathway in patients with statin therapy

Statins, widely used antihyperlipidemic drugs, also have immunomodulatory properties independent from their lipid lowering effect. Even with slight modulations in the immune system, pteridine levels can display changes. The effect of statins on pteridines and related pathways has been demonstrated in a limited number of studies. The aim of the study was to evaluate the possible changes in neopterin and folate levels, and tryptophan (Trp) degradation in hyperlipidemic patients. Patients who were admitted to the cardiology clinic were randomly grouped if they were having statin treatment (n=69) or not (n=36). Serum Trp and kynurenine (Kyn), erythrocyte folate, and urinary neopterin levels were measured. It was found that urinary neopterin levels were significantly higher in patients on statin treatment (p<0.05) while levels of folate, Trp, Kyn, and Kyn-to-Trp ratios (Kyn/Trp) presented no significant changes (all, p>0.05). The correlation of the measured parameters was also evaluated and neopterin, folate and tryptophan degradation were found to be positively correlated. According to the results, neopterin levels, folate status and Trp degradation were altered in patients with statin treatment in comparison with the patients not receiving statin therapy. In order to point out the direct effect of statins on pteridines, further studies presenting both pre- and post-statin treatment of these parameters are needed.

Serum macrophage migration inhibitory factor levels are associated with angiographically complex coronary lesions in patients with coronary artery disease

BACKGROUND

Rupture of vulnerable plaque with subsequent thrombus formation has been implicated as the most common pathogenic mechanism responsible for acute coronary syndrome (ACS). Angiographic coronary lesion complexity has been reported to reflect plaque vulnerability. Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine and might be involved in the pathophysiology of atherosclerotic plaque destabilization.

OBJECTIVE

This study was designed to investigate if serum MIF levels are associated with angiographic coronary lesion complexity in patients with coronary artery disease (CAD).

MATERIALS AND METHODS

A total of 232 consecutive CAD patients and 76 controls were recruited. CAD patients were subdivided according to the presence of ACS (n=138) or stable angina pectoris (SAP) (n=98). Coronary lesion morphology was assessed by coronary angiography. Serum MIF levels were measured by an enzyme-linked immunosorbent assay.

RESULTS

SAP patients had significantly higher serum MIF levels compared with healthy controls, and ACS patients had significantly higher serum MIF levels compared with SAP patients. In SAP patients, serum MIF levels were independently associated with the presence of complex coronary lesion. In ACS patients, serum MIF levels increased in conjunction with the extent of complex lesions.

CONCLUSIONS

Serum MIF levels are a potential biomarker for reflecting the presence and severity of angiographically complex coronary lesion in CAD patients.

Estimation of serum neopterin in patients with acute coronary syndrome

BACKGROUND

The aim of our study was to determine neopterin levels in patients with acute coronary syndrome, in which the release of various cytokines activates the cellular immune system. There is an increase in the number and activity of T-cells in unstable atherosclerotic plaques, and of type 1 helper T-cells that produce interferon γ, which in turn produces neopterin, a byproduct of the guanosine triphosphate-biopterin pathway and a marker for activated macrophages.

METHODS

We studied 600 subjects consisting of healthy volunteers and patients with noncardiac chest pain, ST-segment elevation myocardial infarction, non-ST-segment elevation myocardial infarction, or unstable angina. Neopterin levels were determined by high-performance liquid chromatography.

RESULTS

Mean serum neopterin levels in ST-segment elevation myocardial infarction (11.5 ± 3.2 nmol·L(-1)), non-ST-segment elevation myocardial infarction (9.8 ± 2.9 nmol·L(-1)), and unstable angina patients (9.4 ± 2.3 nmol·L(-1)) were significantly higher than those in noncardiac chest pain patients (7.4 ± 1.9 nmol·L(-1)) and healthy volunteers (7.2 ± 0.6 nmol·L(-1); p < 0.001).

CONCLUSION

These findings suggest that serum neopterin levels may be a useful marker of systemic inflammation, and measurement of serum neopterin may be helpful in assessing the risk of developing coronary heart disease.

Levels of circulating neopterin in patients with severe carotid artery stenosis undergoing carotid stenting

AIMS

The association between an elevated serum neopterin level and the development of coronary artery complex lesions has been extensively assessed; however, the correlation between the serum neopterin level and the development of carotid artery stenosis has seldom been reported. This study tested whether this biomarker is increased in patients with severe carotid artery stenosis(≥70%) undergoing carotid artery(CA) stenting and investigated independent predictors of an increased circulating neopterin level.

METHODS

Fifty patients with severe CA stenosis(CAS) undergoing CA stenting were consecutively enrolled in this study from January 2009 through December 2011. The serum neopterin levels of age- and gender-matched acute ischemic stroke(AIS) patients(n=120) and control subjects(CS)(n=33) were also measured. A blood sample was prospectively collected from each patient in the catheterization room.

RESULTS

The serum levels of neopterin were significantly higher in the CAS patients than in the AIS patients or CS and significantly higher in the AIS patients than in the CS(all p＜0.001). An analysis of the variables of 170 patients(CAS＋AIS) demonstrated that age, a previous history of stroke and severe CAS were significantly correlated with an increased serum level of neopterin(all p＜0.005). A multivariate binary logistic regression analysis of the severe CAS patients(n=50) demonstrated that age and the creatinine level were independent predictors of a high neopterin level(neopterin level ≥16.52 ng/dL, i.e., according to the median value of neopterin)(all p＜0.05).

CONCLUSIONS

The circulating neopterin levels are significantly higher in patients with severe CAS than in those with AIS. The presence of CAS, age and the creatinine level were significantly correlated with an increased serum neopterin level.

Pathophysiological roles and clinical importance of biomarkers in acute coronary syndrome

Early diagnosis of acute coronary syndrome (ACS) is important to guide appropriate therapy at a time when it is most likely to be of value. Accurate prognostic and risk stratification will facilitate high-risk patients to have early advanced diagnostic investigations and early appropriate interventions in a cost-effective and efficient manner, while those patients at low risk of ACS complications do not need such costly diagnostic tests and unnecessary hospital admission. Recent investigations have demonstrated that elevation of biomarkers upstream from acute-phase biomarkers, biomarkers of plaque destabilization and rupture, biomarkers of myocardial ischemia, necrosis, and dysfunction may provide an earlier assessment of patient risk and identify patients with higher risk of having an adverse event. This review provides an overview of the pathophysiology and clinical characteristics of several well-established biomarkers as well as emerging biomarkers that may have potential clinical utility in patients with ACS. Such emerging biomarkers hold promise and need to be more thoroughly evaluated before utilization in routine clinical practice.

Association between serum neopterin and inflammatory activation in chronic kidney disease

Background. The serum levels of neopterin, a marker associated with cell-mediated immunity are elevated in chronic kidney disease (CKD). We evaluated serum neopterin levels and investigated its association with markers of inflammation in a cross-section of CKD subjects without known cardiovascular disease. Methods. Serum neopterin levels were measured in 118 patients with stage 3–5 CKD and 41 healthy subjects with normal kidney function (HC). Patients with known cardiovascular disease were excluded. We also estimated highly sensitive CRP (hsCRP) and interluekin-6 (IL-6), tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) in the CKD subjects. All assays were done using commercially available ELISA kits. The correlation between neopterin and markers of inflammation were investigated. Results. Of the CKD population, 82 were in stage 5 (60 stage 5 D), 24 in stage 4, and 12 in stage 3. The mean age was 51.04 ± 1.3 years and 66% were males. The commonest cause of CKD was diabetes (36%). Serum neopterin levels were 5-fold higher in CKD patients as compared to HC (74.8 ± 3.6 versus 15.0 ± 2.8 nmol/L, P < 0.0001). There was a graded increase of serum neopterin from stages 3 to 4 and 5. CKD 5 D patients exhibited significantly higher levels compared to nondialysis stage 5 patients (P < 0.0001). An inverse correlation was noted between serum neopterin and eGFR (r = −0.359, P < 0.0001). Serum neopterin correlated with hsCRP (r = 0.285, P = 0.002), IL-6 (r = 0.212, P = 0.034), and IFN-γ (r = 0.32, P = 0.001) but not with TNF-α. Conclusion. Serum neopterin level is elevated and correlates with the severity of CKD. The elevation correlates with elevation of most, but not all, inflammatory markers. Its role in future development of cardiovascular disease and modulation with anti-inflammatory therapies needs further studies.

Serum level and prognostic value of neopterin in patients after ischemic stroke

BACKGROUND

We hypothesized that serum level of neopterin is significantly predictive of prognostic outcome in patients after acute ischemic stroke (IS).

METHODS

Between November 2008 and May 2010, serum levels of neopterin were prospectively collected at 48 h after acute IS in 157 patients.

RESULTS

Serum neopterin levels were substantially higher in patients with severe neurological impairment [National institutes of Health Stroke Scale (NIHSS) score ≥12] than in those with NIHSS <12 (p<0.008). Furthermore, Spearman's test showed a strongly positive correlation between neopterin level and NIHSS (p=0.003). Multiple logistic regression analysis demonstrated that serum neopterin level was strongly and independently predictive of NIHSS ≥12 (p=0.002) at 48 h after acute IS and 90-day major adverse clinical outcome (defined as NIHSS≥12, recurrent stroke or death) (p=0.003).

CONCLUSION

Serum level of neopterin was notably increased after acute IS. This biomarker was strongly and independently predictive of 90-day unfavorable clinical outcome in patients after acute IS.

Novel serum biomarkers in carotid artery stenosis: useful to identify the vulnerable plaque?

OBJECTIVES

Serum biomarkers representing inflammatory activity in vulnerable carotid plaques may be used to identify high-risk patients for cerebral ischemic events. We aimed to analyze the relationship between concentrations of four novel biomarkers and neurological symptoms: Neopterin, PTX3, sCD163, and sTREM-1. In addition, we analyzed the relationship between these markers and the presence of coronary (CAD) and peripheral (PAD) artery disease.

DESIGN AND METHODS

Serum biomarker levels were determined in 100 patients undergoing carotid endarterectomy; 33 for stroke, 32 for transient ischemic attack, and 23 for amaurosis fugax. 12 Patients were asymptomatic. Risk factors for atherosclerotic disease and history of CAD and PAD were also assessed.

RESULTS

Symptomatic patients did not show significantly elevated biomarker levels compared to asymptomatic patients and levels did not differ among symptomatic subgroups. Neopterin levels were elevated in patients with concomitant coronary and peripheral artery disease (CAD (32%) 10.2 ± 6.6 vs no CAD (68%) 7.6 ± 2.9 nmol/L, PAD (20%) 12.3 ± 7.4 vs no PAD (80%) 7.5 ± 3.0 nmol/L, p<0.05). sTREM-1 was elevated in patients with CAD (50.8 ± 53.2 vs 28.0 ± 31.6 ng/L, p<0.05). PTX3 and sCD163 were not significantly elevated in CAD nor PAD.

CONCLUSION

Our findings suggest that serum neopterin and sTREM-1 levels may be related to the presence of atherosclerotic disease, but not to carotid plaque vulnerability.

Gender-specific differences in biomarkers responses to acute coronary syndromes and revascularization procedures

A growing body of gender-related research in coronary artery disease is beginning to gradually elucidate differences between women and men. In patients presenting with acute coronary syndromes (ACS), these sex differences include varying risk factor profiles, accuracy of diagnostic testing, clinical presentations, treatment practices and outcomes. There is also a differential expression of cardiac biomarkers by sex, which remains unexplained. This paper reviews all the available information on the effect of gender on cardiac biomarkers by search of MEDLINE using the terms gender differences, biomarkers, ACS and revascularization procedures. A better understanding of the sex disparities in biomarkers along with all other clinical information is essential to optimal management and patient care in the future.

Circulating soluble lectin-like oxidized low-density lipoprotein receptor-1 levels are associated with angiographic coronary lesion complexity in patients with coronary artery disease

BACKGROUND

Angiographic coronary lesion complexity has been reported to predict plaque vulnerability. It is important to develop a noninvasive blood biomarker for accurate prognostication of angiographically complex lesions in patients with coronary artery disease (CAD).

HYPOTHESIS

Serum soluble lectin-like oxidized low-density lipoprotein receptor-1 (sLOX-1) levels may be correlated with coronary lesion complexity in patients with CAD.

METHODS

We measured serum sLOX-1 levels in 180 consecutive patients undergoing coronary angiography for the evaluation of CAD. Coronary lesions were classified as simple or complex lesions based on coronary plaque morphology.

RESULTS

Stable CAD patients with complex lesions (n=50) had significantly higher serum sLOX-1 levels than those with simple lesions (n=72), at 0.914 ng/mL (range, 0.489-1.296 ng/mL) vs 0.426 ng/mL (range, 0.195-1.075 ng/mL), respectively, P<0.01. Multivariate logistic regression analysis revealed that sLOX-1 levels were independently associated with the presence of complex lesions in patients with stable CAD (odds ratio [OR]: 1.964, 95% confidence interval [CI]: 1.149-3.356, P<0.05). Among patients with acute coronary syndrome (n=58), who had significantly higher circulating sLOX-1 levels than stable CAD patients (n=122) at 1.610 ng/mL (range, 0.941-2.264 ng/mL) vs 0.579 ng/mL (range, 0.265-1.172 ng/mL), respectively, P<0.01, sLOX-1 levels were independently associated with the presence of multiple complex coronary lesions (OR: 1.967, 95% CI: 1.075-3.600, P < 0.05).

CONCLUSIONS

Serum sLOX-1 levels were associated with complex lesions that might predict vulnerable plaques. This study suggested sLOX-1 might be a useful biomarker of coronary plaque vulnerability in patients with CAD.

Neopterin and atherosclerotic plaque instability in coronary and carotid arteries

Inflammation plays a key role in atherosclerosis and plaque vulnerability, and monocyte/macrophage activation contributes to these processes. Neopterin, a by-product of the guanosine triphosphate pathway, is produced by activated macrophages on stimulation with interferon-γ released from T lymphocytes, and is an activation marker for monocytes/macrophages. Coronary angiographic studies have shown a relationship between increased circulating levels of neopterin and the presence of complex coronary lesions in patients with unstable angina pectoris (UAP). Furthermore, in an immunohistochemical study performed using coronary atherectomy specimens, a significantly higher prevalence of neopterin-positive macrophages was found in culprit lesions in patients with UAP than in those with stable angina pectoris (SAP). We recently clarified that the presence of complex carotid plaques detected by carotid ultrasound was related to increased circulating levels of neopterin, and immunohistochemical localization of neopterin was observed in complex carotid lesions obtained from carotid endarterectomy in patients with SAP. These findings suggest that neopterin is an important biomarker of plaque instability in both coronary and carotid atherosclerotic lesions.

Levels of sCD40 ligand in chronic and acute coronary syndromes and its relation to angiographic extent of coronary arterial narrowing

We determined the serum levels of soluble CD40 ligand (sCD40L) in patients with chronic coronary artery disease (CAD) and acute coronary syndrome (ACS). Patients with unstable angina (UA) and myocardial infarction (MI) showed significantly higher levels (P < .001) of sCD40L compared with patients with stable angina (SA) and controls; particularly, high levels occurred in patients with UA (UA: 9.23 +/- 2.92, MI: 7.38 +/- 1.05, SA: 4.42 +/- 1.08; control: 4.01 +/- 0.87 ng/mL). There was no significant difference in sCD40L levels between patients with UA and MI or between patients with SA and controls. Levels of sCD40L did not show any significant correlation with peak creatine kinase (CK), CK-MB isoenzyme activity in patients with MI, troponin T serum levels in patients with UA or with culprit vessel (CV) complexity score (CVCS), type of CV lesion, or vessel score in patients with UA or MI. These results suggest that CD40L plays a pathogenic role in triggering ACS.

Elevated levels of neopterin are associated with carotid plaques with complex morphology in patients with stable angina pectoris

OBJECTIVE

Neopterin is an activation marker for monocytes/macrophages, and circulating levels of neopterin are elevated in patients with coronary complex lesions in unstable angina pectoris. We investigated the possible association between neopterin and complex carotid plaques which may be associated with the risk of ischemic stroke in patients with stable angina pectoris (SAP).

METHODS

We measured plasma levels of neopterin in 102 patients with SAP and carotid ultrasound was performed for evaluation of the presence of carotid plaques and plaque surface characteristics categorized as complex or noncomplex. In addition, endarterectomy specimens of extracranial high-grade carotid stenosis with complex plaques from five patients with SAP were immunohistochemically examined with antibodies to smooth muscle cells, endothelial cells, platelets, macrophages, and T cells.

RESULTS

Plasma neopterin levels were significantly higher in patients with complex carotid plaques than in those with noncomplex plaques (median [interquartile range]: 24.2 [19.2-39.3]nmol/L vs. 19.4 [11.9-25.1]nmol/L; P=0.01) or without any plaques (18.8 [14.9-23.6]nmol/L; P=0.001). On multivariate logistic analyses after adjustment for traditional atherosclerotic risk factors, multi-vessel coronary disease and high sensitivity C-reactive protein, neopterin levels were independently associated with the presence of complex carotid plaques (adjusted OR 2.21 per SD increase, 95%CI 1.13-4.33, P=0.02). Immunohistochemical staining revealed abundant neopterin-positive macrophages in carotid complex lesions.

CONCLUSION

These findings demonstrate that carotid plaques with complex morphology have increased circulating neopterin levels and immunohistochemical localization of neopterin in patients with SAP. Neopterin can be considered an important biomarker of plaque destabilization in carotid artery atherosclerotic lesions in this population.

Elevation of the glycoxidation product N(epsilon)-(carboxymethyl)lysine in patients presenting with acute myocardial infarction

BACKGROUND

An important role in the acceleration of vascular disease has been previously suggested for advanced glycation end products. N(epsilon)-(carboxymethyl)lysine (CML) is an advanced glycation end product formed on protein by combined non-enzymatic glycation and glycoxidation reactions. CML reacts with the receptor of advanced glycation end products inducing impairment of endothelium dependent relaxation and is a marker of oxidative stress.

METHODS

A total of 40 patients with acute myocardial infarction (17 patients with ST-elevation myocardial infarction, 23 patients with non-ST-elevation myocardial infarction) and 40 patients with stable coronary artery disease were included consecutively in this study. During coronary angiography, peripheral venous blood sample was taken for measuring CML.

RESULTS

Serum levels of CML were significantly increased in patients with acute myocardial infarction [17.9+/-10.7 vs. 6.6+/-3.1 arbitrary units (AU)/mg protein, p<0.001]. A cut-off value of CML>9.5 AU/mg protein was associated with an odds ratio of acute myocardial infarction of 39.7 [95% confidence interval (CI): 11.1-142, p<0.001], a sensitivity of 0.85 (95% CI: 0.70-0.94) and a specificity of 0.88 (95% CI: 0.73-0.96).

CONCLUSIONS

CML levels are significantly elevated in patients presenting with acute myocardial infarction. These results suggest the involvement of endothelial dysfunction (through receptor interaction) and oxidative stress in acute myocardial infarction.

Neopterin as a Predictor of Total and Cardiovascular Mortality in Individuals Undergoing Angiography in the Ludwigshafen Risk and Cardiovascular Health Study

Background: Neopterin is produced upon activation of the cell-mediated immune response, and may be a novel risk marker for adverse outcomes resulting from coronary artery disease.

Methods: We measured neopterin in 1801 study participants with and 511 without angiographic coronary artery disease. Rates of death were determined after a median follow-up of 8.0 years.

Results: Estimated glomerular filtration rate and N-terminal pro-B–type natriuretic peptide (NT-proBNP) were the strongest predictors of neopterin. Neopterin was positively related to age and inversely related to LDL cholesterol, HDL cholesterol, and triglycerides. Use of lipid-lowering drugs lowered neopterin. Sex, body mass index, diabetes mellitus, hypertension, smoking status, Friesinger coronary score, and clinical instability at presentation were not associated with neopterin. Unlike C-reactive protein, neopterin was not increased in unstable angina pectoris, non–ST–elevation myocardial infarction, or ST-elevation myocardial infarction. In the third and fourth quartiles of neopterin, unadjusted hazard ratios for death from any cause were 1.94 (95% CI 1.44–2.61) and 3.32 (95% CI 2.53–4.30) compared to individuals in the first quartile, whereas hazard ratios for death from cardiovascular causes were 2.14 (95% CI 1.44–3.18) and 3.84 (95% CI 2.67–5.52), respectively. Neopterin remained predictive of total and cardiovascular mortality after adjusting for sex, age, body mass index, type 2 diabetes, hypertension, smoking status, LDL cholesterol, HDL cholesterol, triglycerides, estimated glomerular filtration rate, NT-proBNP, and clinical status at presentation, but NT-proBNP substantially weakened this association.

Conclusions: Neopterin is an independent predictor of all-cause and cardiovascular mortality in individuals with or without stable coronary artery disease.

Neopterin predicts the risk for fatal ischemic heart disease in type 2 diabetes mellitus: long-term follow-up of the HUNT 1 study

AIMS

Neopterin has emerged as a novel predictor of coronary events. The study aim was to compare the predictive value of neopterin and C-reactive protein (CRP) on long-term risk for fatal ischemic heart disease (IHD) in persons with newly diagnosed diabetes compared to persons without diabetes.

METHODS AND RESULTS

In 1984-1986 a large population study, HUNT 1, was conducted in Norway. During the study, 205 patients were diagnosed with formerly unknown diabetes. A matched control group without diabetes was selected from the HUNT 1 population. Fatal IHD was registered until 2004. Blood samples were drawn at baseline and serum was analysed for neopterin and CRP. Cox regression analysis with correction for age, gender, hypertension, body mass index, established cardiovascular disease and total cholesterol was used to estimate hazard ratios (HR) for fatal IHD. In the diabetes group, neopterin and CRP were independent predictors of fatal IHD, HR 2.59 (1.11-6.01) and 2.45 (1.05-5.69), respectively. Neither CRP nor neopterin were significant predictors of fatal IHD in the control group.

CONCLUSION

In subjects with diabetes, both neopterin and CRP were independent predictors of fatal IHD, suggesting that these two markers reflect different aspects of the pathogenesis underlying fatal coronary events.

Association between plasma thiols and immune activation marker neopterin in stable coronary heart disease

BACKGROUND

Studies have associated elevated plasma levels of the thiols homocysteine and cysteine with an increased risk of atherosclerosis. Their relationship with systemic inflammatory parameters and sclerosis scores was investigated in this study.

METHODS

Total homocysteine, total cysteine, neopterin and C-reactive protein (CRP) concentrations were measured in blood samples of 242 patients undergoing elective coronary angiography. A total of 181 patients had coronary artery disease (CAD), as defined by occlusion of > 75% of at least one of the three main coronary arteries, and 61 subjects did not have relevant coronary stenoses.

RESULTS

Total cysteine concentrations were higher in patients suffering from coronary artery sclerosis with stepwise increases relative to the extent of coronary artery sclerosis (p < 0.001). In contrast, neither total homocysteine nor the inflammatory markers, CRP and neopterin, differed between patients and controls. However, total homocysteine concentrations correlated with total cysteine (r = 0.468) and neopterin concentrations (r = 0.290), as well as serum creatinine (r = 0.226; all p < 0.001), the latter indicating a dependence of total homocysteine concentrations on kidney function. Total cysteine concentrations were associated with increased neopterin levels (r = 0.231, p < 0.001).

CONCLUSIONS

Total cysteine concentrations were well suited to estimate the extent of coronary artery sclerosis, while in our study of stable CAD patients total homocysteine was not increased compared to controls. The association between homocysteine, cysteine and parameters of immune activation and inflammation in our study suggests that these markers of CAD may be interdependent.

Elevated serum neopterin levels and adverse cardiac events at 6 months follow-up in Mediterranean patients with non-ST-segment elevation acute coronary syndrome

BACKGROUND

Little information exists regarding the prognostic role of biomarkers of inflammation in Mediterranean patients. High C-reactive protein and neopterin levels - a marker of macrophage activation - predict cardiovascular events in stable angina patients and patients with acute coronary syndromes (ACS). We sought to assess whether plasma neopterin levels predict adverse clinical outcomes in Mediterranean patients with non-ST elevation (NSTE) ACS, i.e. unstable angina (UA) and NSTE myocardial infarction (MI).

METHODS

We prospectively assessed 397 patients (74% men) admitted with NSTEACS, 147 (37%) had unstable angina and 250 (63%) NSTEMI. Blood samples for neopterin and CRP assessment were obtained at admission. The study endpoint was the composite of cardiac death, acute myocardial infarction and unstable angina at 180 days.

RESULTS

Baseline neopterin concentrations (nmol/L) were similar in unstable angina and NSTEMI patients (8.3 [6.6-10.7] vs. 7.9 [6.2-10.9]; p=0.4). Fifty-nine patients (14.9%) had events during follow-up. Twenty-nine (21.5%) patients with neopterin levels in the highest third experienced the combined endpoint, compared to 30 (11.5%) patients with neopterin levels in the second and the lowest thirds (log-rank 7.435, p=0.024). On multivariable hazard Cox regression, neopterin (highest vs. 1st and 2nd thirds, HR 1.762, 95% CI [1.023-3.036]) was independently associated with the combined endpoint.

CONCLUSION

Increased neopterin levels are an independent predictor of 180-day adverse cardiac events in Mediterranean patients with NSTEACS.

Altered plasma versus vascular biopterins in human atherosclerosis reveal relationships between endothelial nitric oxide synthase coupling, endothelial function, and inflammation

BACKGROUND

Tetrahydrobiopterin (BH4) is a key regulator of endothelial nitric oxide synthase (eNOS) activity and coupling. However, the extent to which vascular and/or systemic BH4 levels are altered in human atherosclerosis and the importance of BH4 bioavailability in determining endothelial function and oxidative stress remain unclear. We sought to define the relationships between plasma and vascular biopterin levels in patients with coronary artery disease and to determine how BH4 levels affect endothelial function, eNOS coupling, and vascular superoxide production.

METHODS AND RESULTS

Samples of saphenous veins and internal mammary arteries were collected from 219 patients with coronary artery disease undergoing coronary artery bypass grafting. We determined plasma and vascular levels of biopterins, vasomotor responses to acetylcholine, and vascular superoxide production in the presence and absence of the eNOS inhibitor N(G)-nitro-L-arginine methyl ester. High vascular BH4 was associated with greater vasorelaxations to acetylcholine (P<0.05), whereas high plasma BH4 was associated with lower vasorelaxations in response to acetylcholine (P<0.05). Furthermore, an inverse association was observed between plasma and vascular biopterins (P<0.05 for both saphenous veins and internal mammary arteries). High vascular (but not plasma) BH4 was associated with reduced total and N(G)-nitro-L-arginine methyl ester-inhibitable superoxide, suggesting improved eNOS coupling. Finally, plasma but not vascular biopterin levels were correlated with plasma C-reactive protein levels (P<0.001).

CONCLUSIONS

An inverse association exists between plasma and vascular biopterins in patients with coronary artery disease. Vascular but not plasma BH4 is an important determinant of eNOS coupling, endothelium-dependent vasodilation, and superoxide production in human vessels, whereas plasma biopterins are a marker of systemic inflammation.

Neopterin is associated with plaque inflammation and destabilisation in human coronary atherosclerotic lesions

BACKGROUND

Previous studies have shown that recent activation of the inflammatory response in coronary atherosclerotic lesions contributes to rapid progressive plaque destabilisation. Neopterin, a by-product of the guanosine triphosphate pathway, is produced by activated macrophages and serves as an activation marker for monocytes/macrophages.

OBJECTIVE

To elucidate the role of neopterin in coronary plaque destabilisation by immunohistochemical study of the presence of neopterin in coronary atherectomy specimens obtained from patients with stable angina pectoris (SAP) and unstable angina pectoris (UAP).

PATIENTS AND METHODS

All patients underwent atherectomy of the primary atherosclerotic lesions responsible for SAP (n = 25) and UAP (n = 25). Frozen samples were studied with antibodies against smooth muscle cells, macrophages, T cells, neutrophils and neopterin.

RESULTS

In 22/25 patients with UAP, abundant neopterin-positive macrophages were found at the sites of coronary culprit lesions. However, in 25 lesions from patients with SAP, only 11 lesions showed neopterin positivity. Quantitatively, the neopterin-positive macrophage score was significantly higher (p<0.001) in patients with UAP than in patients with SAP. Moreover, the neopterin-positive macrophage score showed a significant positive correlation with the number of neutrophils or T cells, respectively (neutrophils, r = 0.55, p<0.001; T cells, r = 0.70, p<0.001).

CONCLUSIONS

Neopterin can be considered as one of the significant factors in the process of plaque inflammation and destabilisation in human coronary atherosclerotic lesions. Its exact role in the process needs to be investigated further.

Potential to inhibit growth of atherosclerotic plaque development through modulation of macrophage neopterin/7,8-dihydroneopterin synthesis

The rise in plasma neopterin observed with increasing severity of vascular disease is a strong indicator of the inflammatory nature of atherosclerosis. Plasma neopterin originates as the oxidation product of 7,8-dihydroneopterin secreted by gamma-interferon stimulated macrophages within atherosclerotic plaques. Neopterin is increasingly being used as a marker of inflammation during clinical management of patients with a range of disorders including atherosclerosis. Yet the role of 7,8-dihydroneopterin/neopterin synthesis during the inflammatory process and plaque formation remains poorly understood and controversial. This is partially due to the unresolved role oxidants play in atherosclerosis and the opposing roles of 7,8-dihydroneopterin/neopterin. Neopterin can act as pro-oxidant, enhancing oxidant damage and triggering apoptosis in a number of different cell types. Neopterin appears to have some cellular signalling properties as well as being able to chelate and enhance the reactivity of transition metal ions during Fenton reactions. In contrast, 7,8-dihydroneopterin is also a radical scavenger, reacting with and neutralizing a range of reactive oxygen species including hypochlorite, nitric oxide and peroxyl radicals, thus protecting lipoproteins and various cell types including macrophages. This has led to the suggestion that 7,8-dihydroneopterin is synthesized to protect macrophages from the oxidants released during inflammation. The oxidant/antioxidant activity observed in vitro appears to be determined both by the relative concentration of these compounds and the specific chemistry of the in vitro system under study. How these activities might influence or modulate the development of atherosclerotic plaque in vivo will be explored in this review.

Plaque vulnerability and related coronary event prediction by intravascular ultrasound with virtual histology: "it's a long way to tipperary"?

Identification of so-called "vulnerable plaque" or "high-risk" plaques have spawned manifold attempts to develop diagnostic tools capable to afford this task. This task is particularly challenging but the reward is high: local intervention on identified "vulnerable plaque" could preclude plaque thrombosis and possibly prevent acute coronary syndromes. Various imaging techniques are currently under investigation by extensive clinical testing to identify which could become the most sensible and specific modality for vulnerable plaque detection. Noninvasive techniques are fascinating for their easily applicability to a broad population but nowadays are not sufficiently powered for this task. The emerging technologies with the greatest resolution are indeed catheter-based and many intravascular modalities have been developed for identification of "vulnerable plaque". Among these, IVUS-Virtual Histology (IVUS-VH) is the most promising technique in the field. IVUS-VH offers an in vivo opportunity to assess plaque morphology and histology. IVUS-VH uses underlying frequency information along with echoes intensity, while grey-scale IVUS data are obtained from echoes of different intensity or amplitude. The major advantage of IVUS-VH is that it is based on a device that is practical for use in the clinical setting and that it generates a real-time assessment of plaque morphology. Unfortunately, numerous challenging issues still need to be overcome until the numerous "vulnerable plaques" could be identified and successfully treated. Future efforts may identify plaques that are on a trajectory of evolution toward a vulnerable state, and help us target interventions to those plaques most likely to develop plaque disruption and related complications.

Homocysteine-lowering therapy does not affect inflammatory markers of atherosclerosis in patients with stable coronary artery disease

OBJECTIVES

A high level of total homocysteine (tHcy) is a risk marker for cardiovascular disease (CVD), and is related to inflammation. We wanted to test the effect of homocysteine-lowering B-vitamin therapy, as used in the Western Norway B-vitamin Intervention Trial (WENBIT), on inflammatory markers associated with atherosclerosis.

DESIGN

Single centre, prospective double-blind clinical interventional study, randomised in a 2 x 2 factorial design.

SUBJECTS AND METHODS

Ninety patients (21 female) with suspected coronary artery disease (CAD), aged 38-80 years, were blindly randomised into one of four groups of daily oral treatment with (A) folic acid (0.8 mg)/vitamin B12 (0.4 mg)/vitamin B6 (40 mg), (B) folic acid/vitamin B12, (C) vitamin B6 alone or (D) placebo. Blood samples were collected before and after 6 months of treatment.

RESULTS

Before intervention, median levels of the analytes were: tHcy 11.0 micromol L(-1), neopterin 8.1 nmol L(-1), soluble CD40 ligand (sCD40L) 3.9 ng mL(-1), interleukin (IL)-6 1.9 pg mL(-1), C-reactive protein (CRP) 1.9 mg L(-1) and low-density lipoprotein (LDL) cholesterol 3.3 mmol L(-1). tHcy was significantly associated with neopterin (r = 0.49, P < 0.001) and with IL-6 (r = 0.29, P = 0.01), but not with CRP or sCD40L. Neither treatment with folic acid/B12 nor with B6 induced significant changes in any of these inflammatory biomarkers (P >or= 0.14). In patients receiving folic acid/B12 (groups A and B), tHcy was reduced with 33% (P < 0.001).

CONCLUSIONS

In patients with stable CAD, homocysteine-lowering therapy with B-vitamins does not affect levels of inflammatory markers associated with atherogenesis. Failure to reverse inflammatory processes, may partly explain the negative results in clinical secondary B-vitamin intervention trials.

Elevated levels of neopterin in sleep-disordered breathing

BACKGROUND

Sleep-disordered breathing (SDB) is increasingly being recognized as an independent risk factor for hypertension and cardiovascular disease. Recent evidence suggests that the maladaptive physiologic response to SDB, particularly cardiovascular effects, may result in part from systemic inflammation. Although abnormal cytokine levels have been documented in SDB, data on whether SDB is associated with cellular activation are limited. Thus, this investigation sought to determine whether neopterin, a marker released by activated macrophages, is increased in SDB.

METHODS AND RESULTS

Fifty-five men, free of medical comorbidity, undergoing polysomnography had fasting serum tested for neopterin levels. Multivariable regression methods were used to quantify the association between neopterin and quartiles of the apnea hypopnea index (AHI) while accounting for body mass index, waist circumference, and percentage of body fat. Quartiles of AHI (I: < 3.83 events per hour; II: 3.83 to 11.98 events per hour; III: 11.99 to 36.82 events per hour; IV > 36.82 events per hour) indicated a range from no SDB through severe SDB. Compared to the subjects in the first AHI quartile, serum neopterin levels were higher by 3.0%, 10.9%, and 26.5% in the second, third, and fourth AHI quartiles, respectively (p < 0.001for linear trend). Neopterin levels also were higher in those with greater degree of sleep-related hypoxemia, more stage 1 sleep, and less stage 2 sleep.

CONCLUSION

The results of this study indicate that severity of SDB independently associates with serum levels of neopterin, a marker for macrophage activation that may play an important role in the pathogenesis of SDB-related cardiovascular disease.

Long-term prognostic value of neopterin: a novel marker of monocyte activation in patients with acute coronary syndrome

BACKGROUND

Monocyte activation is believed to play an important role in the pathogenesis of acute coronary syndromes (ACS). Neopterin is a soluble marker of monocyte activation, and elevated levels are of prognostic value in patients with stable coronary artery disease.

METHODS AND RESULTS

Neopterin levels were measured on average at 7 days (in 3946 patients) and at 4 months (in 3369 patients) after ACS in the PRavastatin Or atorVastatin Evaluation Infection Therapy-Thrombolysis In Myocardial Infarction (PROVE IT-TIMI 22) trial. We assessed the relationship between plasma neopterin levels and the risk of death and death or acute coronary events (nonfatal myocardial infarction or unstable angina) over 2 years. Seven days after an ACS event, neopterin levels > or = 12.11 nmol/L (upper quartile, derived from a post hoc analysis) were associated with an increased risk of death and an increased risk of death or acute coronary events after adjustment for age, gender, history of diabetes mellitus, history of hypertension, history of smoking, type of ACS presentation, use of percutaneous coronary intervention for the index event, statin regimen, low-density lipoprotein cholesterol, and high-sensitivity C-reactive protein (hazard ratio, 1.86 [95% CI, 1.24 to 2.77], P=0.003; and hazard ratio, 1.33 [95% CI, 1.09 to 1.63] P=0.006, respectively). Neopterin levels > or = 12.11 nmol/L at 4 months remained a predictor of death alone and of death or acute coronary events after multivariable adjustment that included adjustment for month 4 low-density lipoprotein cholesterol, high-sensitivity C-reactive protein, and statin regimen (hazard ratio, 2.39 [95% CI, 1.43 to 3.99], P=0.001; and hazard ratio, 1.60 [95% CI, 1.21 to 2.11], P=0.001). High-dose atorvastatin significantly attenuated the risk among subjects with neopterin levels > or = 12.11 nmol/L at baseline (interaction P for death or acute coronary event, 0.018).

CONCLUSIONS

Increased monocyte activation detected by an elevated plasma neopterin level identifies patients at long-term risk of death or recurrent acute coronary events after ACS. Intensive statin therapy significantly attenuates the risk of recurrent events among patients with an elevated neopterin level.

Total cholesterol content of erythrocyte membranes is increased in patients with acute coronary syndrome: a new marker of clinical instability?

OBJECTIVES

We hypothesized that cholesterol content is increased in the circulating erythrocytes of patients with acute coronary syndrome (ACS) and may be a marker of clinical instability. We therefore sought to investigate whether cholesterol content differs in erythrocyte membranes of patients presenting with ACS compared to patients with chronic stable angina (CSA).

BACKGROUND

Plaque rupture in ACS depends at least partly on the volume of the necrotic lipid core. Histopathologic studies have suggested that cholesterol transported by erythrocytes and deposited into the necrotic core of atheromatous plaques contributes to lipid core growth.

METHODS

Consecutive angina patients were prospectively assessed; 120 had CSA (83 men, age 64 +/- 11 years) and 92 ACS (67 men, 66 +/- 11 years). Total cholesterol content in erythrocyte membranes (CEM) was measured using an enzymatic assay, and protein content was assessed by the Bradford method.

RESULTS

The CEM (median and interquartile range) was higher (p < 0.001) in ACS patients (184 microg/mg; range 130.4 to 260.4 microg/mg) compared with CSA patients (81.1 microg/mg; range 53.9 to 109.1 microg/mg) (analysis of covariance). Total plasma cholesterol concentrations did not correlate with CEM levels (r = -0.046, p = 0.628).

CONCLUSIONS

This study shows, for the first time, that CEM is significantly higher in patients with ACS compared with CSA patients. These findings suggest a potential role of CEM as a marker of atheromatous plaque growth and vulnerability. Large ad hoc studies are required to establish the clinical importance and pathogenic significance of CEM measurement.

Neopterin induces pro-atherothrombotic phenotype in human coronary endothelial cells

BACKGROUND

Inflammation plays a pivotal role in atherothrombosis. Recent data indicate that serum levels of neopterin, a marker of inflammation and immune modulator secreted by monocytes/macrophages, are elevated in patients with acute coronary syndromes and seem to be a prognostic marker for major cardiovascular events. The aim of the present study was to determine whether neopterin might affect the thrombotic and atherosclerotic characteristics of human coronary artery endothelial cells (HCAECs).

METHODS AND RESULTS

In HCAECs, neopterin induced TF-mRNA transcription as demonstrated by real time polymerase chain reaction and expression of functionally active tissue factor (TF) as demonstrated by procoagulant activity assay, and of cellular adhesion molecules (CAMs) as demonstrated by FACS analysis, in a dose-dependent fashion. These neopterin effects were prevented by lovastatin, a HMG-CoA reductase inhibitor. Neopterin-induced TF and CAMs expression was mediated by oxygen free radicals through the activation of the transcription factor, nuclear factor-kappa B (NF-kappaB), as demonstrated by electrophoretic mobility shift assay and by suppression of CAMs and TF expression by superoxide dismutase and by NF-kappaB inhibitor, pyrrolidine-dithio-carbamate ammonium.

CONCLUSIONS

These data indicate that neopterin exerts direct effects on HCAECs by promoting CAMs and TF expression and support the hypothesis that neopterin, besides representing a marker of inflammation, might be an effector molecule able to induce a pro-atherothrombotic phenotype in cells of the coronary circulation.

Enhanced inflammatory response following coronary stent implantation in stable angina patients

BACKGROUND

Percutaneous coronary intervention (PCI) is associated with an increase in inflammatory activity. However, little is known about the association between the inflammatory response post-PCI and plaque morphology. The objective of this study was to characterize the inflammatory response following coronary stent implantation (CSI) of stable atherosclerotic plaques, according to plaque morphology.

METHODS

The study population consisted of 62 patients with stable angina that had an elective indication of CSI. Immediately before CSI, the patients underwent intravascular ultrasound (IVUS) for determination of the predominant plaque morphology of the target lesion: calcified (C, n=15), fibrocalcified (FC, n=16), fibrolipidic (FL, n=16), or lipidic (L, n=15). Angiographic lesion types were also determined. Coronary sinus samples were collected at baseline (BL) and 15 min after CSI for measuring inflammatory mediators (IM): interleukin-6 (IL-6, in pg/ml), tumoral necrosis factor-alpha (TNF, in pg/ml), interferon-gamma (IFN, in IU/ml), and neopterin (N, in ng/ml).

RESULTS

BL IL-6, TNF, IFN, and N were, respectively, for C plaques (mean+/-S.D.): 1.3+/-3.0, 8.0+/-3.5, 0.1+/-0.2, and 3.2+/-0.8; for FC plaques: 6.7+/-3.3, 1.9+/-2.0, 0.1+/-0.1, and 3.8+/-2.0; for FL plaques: 0.7+/-0.9, 8.7+/-4.3, 0.1+/-0.2, and 4.0+/-2.4; and, for L plaques: 1.9+/-2.8, 0.9+/-1.4, 0.0+/-0.1, and 5.2+/-3.3. After 15 min of CSI, percentual changes of IL-6, TNF, IFN, and N, respectively, were for C plaques: 43.8+/-19.6%, 7.7+/-5.5%, -7.5+/-5.3%, and -20.0+/-11.2%; for FC plaques: 7.7+/-5.5%, 168.4+/-56.9%, 311.1+/-159.9%, and 0%; for FL plaques: 147.5+/-16.1%*, 714.3+/-34.4%*, 116.1+/-9.9%*, and 3000.0+/-230.0%*; and, for L plaques: 147.7+/-14.4%*, 140.3+/-15.0%*, 131.6+/-11.9%*, and 2300.0+/-25.9%*. Moreover, B1 (n=28) and B2 (n=32) predominated and resulted in significant changes only for IL-6 and IFN, respectively. *P<0.05: 15 min vs BL.

CONCLUSIONS

These data suggest that stable angina patients with predominant lipidic (L and FL) plaques present a greater inflammatory response after CSI in than those with predominant calcified (C and FC) plaques.

Plasma adiponectin levels are associated with coronary lesion complexity in men with coronary artery disease

OBJECTIVES

We sought to assess whether plasma adiponectin levels correlate with angiographic coronary lesion complexity in patients with coronary artery disease (CAD).

BACKGROUND

Metabolic disorders, including diabetes mellitus and metabolic syndrome, are important risk factors for acute cardiovascular events, and adiponectin is a key molecule of metabolic disorders, with anti-atherogenic properties. Low plasma adiponectin levels are associated with CAD and future incidence of myocardial infarction. The involvement of adiponectin in coronary plaque vulnerability, which may be reflected by angiographic complex lesions, remains to be elucidated.

METHODS

We measured plasma adiponectin levels in 207 men (152 with stable CAD and 55 with acute coronary syndromes [ACS]). Coronary lesions were classified as of simple or complex appearance.

RESULTS

Plasma adiponectin levels were significantly lower in stable CAD patients with complex coronary lesions (n = 60) than in those with simple lesions (n = 92) (4.14 [range 2.95 to 6.02] vs. 5.27 [range 3.67 to 8.12] microg/ml, p = 0.006). Multiple logistic regression analysis demonstrated that adiponectin level was independently associated with complex lesions (odds ratio 0.514, 95% confidence interval 0.278 to 0.951; p = 0.034). Polytomous logistic regression revealed that adiponectin correlated independently with both single and multiple complex lesions. Among patients with ACS, who had lower adiponectin levels than stable CAD patients, those with multiple complex lesions had significantly lower adiponectin than those with a single complex lesion (3.26 [range 2.26 to 4.46] vs. 4.21 [range 3.36 to 5.41] microg/ml, p = 0.032).

CONCLUSIONS

Plasma adiponectin levels are significantly associated with coronary lesion complexity in men with CAD. Low adiponectin levels may contribute to coronary plaque vulnerability.

Carotid atherosclerotic plaque instability in patients with acute myocardial infarction

The instability of atherosclerotic plaque is partly determined by local factors, but systemic factors such as infection, inflammation, autoimmunity or genes might also be important. We aimed to analyze whether patients with acute myocardial infarction (AMI) might have a higher proportion of unstable plaques in the carotid arteries compared with patients who had had no acute coronary events.

METHODS

Sixty-nine consecutive patients with AMI (Group 1) and 95 patients without acute coronary events (Group 2) had carotid artery duplex ultrasounds. Carotid atherosclerosis was quantified by number of plaques in the two carotid arteries, intimal media thickening and degree of maximal stenosis. According to their morphology, plaques were divided into stable (fibrocalcific) and unstable (soft and/or not homogeneous).

RESULTS

The two groups did not differ as regards age (66+/-8 vs. 68+/-19; p=0.3), female sex (13% vs. 21%; p=0.3), mean number of carotid plaques (2.8+/-1 vs. 2.5+/-2; p=0.2), degree of stenosis (59+/-2% vs. 36+/-1%; p=0.2) or intimal media thickening (1.04+/-0.2 vs. 1.06+/-0.2; p=0.8). However, Group 1 pts more frequently had unstable carotid plaques compared with Group 2 (43% vs. 15%; p=0.004), and had a greater number of unstable carotid plaques (0.51+/-0.6 vs. 0.16+/-0.4: p<0.0001) and a higher ratio of unstable to stable plaque (19% vs. 8%; p=0.005). In the overall population, logistic regression analysis showed that after adjustment for degree of maximal stenosis, the presence of coronary artery event (AMI pts) predicted the presence of unstable carotid plaque (OR: 4.3 95% CI: 2.0-9.2; p=0.0002).

CONCLUSION

Patients with unstable coronary artery disease expressed clinically as AMI, frequently had unstable atherosclerotic plaques in other arterial sites such as carotid arteries. This finding supports the hypothesis that plaque instability might reflect a systemic process.

Relationship among pregnancy associated plasma protein-A levels, clinical characteristics, and coronary artery disease extent in patients with chronic stable angina pectoris

AIMS

To assess, in chronic stable angina (CSA) patients, the relationship among clinical characteristics and cardiovascular risk factors, extent of coronary artery disease (CAD), and pregnancy-associated plasma protein-A (PAPP-A) levels.

METHODS AND RESULTS

We studied 643 CSA patients (63+/-10 years, 482 men) undergoing diagnostic coronary angiography; 97 with angiographically normal coronary arteries or <50% stenosis, 127 with single vessel disease (VD), and 419 with multi-VD. Patients' age, gender, cardiovascular risk factors, body mass index, history of previous myocardial infarction, angina class, left ventricular ejection fraction (LVEF), and treatment were assessed at study entry. PAPP-A levels (mIU/L) were higher in men than in women (6.2+/-2.4 vs. 5.2+/-1.8; P<0.001) and in hypertensive vs. normotensive patients (6.4+/-2.8 vs. 5.8+/-2.1; P=0.01). PAPP-A correlated directly with age (r=0.19, P<0.001) and inversely with LVEF (r=-0.11, P=0.01). Patients with multivessel disease (VD) had higher PAPP-A levels (6.45+/-2.58) than those with single-VD (5.49+/-1.54, P<0.001) or normal coronaries (4.62+/-1.17, P<0.001). Male gender, age, history of a previous MI, hypercholesterolaemia, and PAPP-A levels were independent predictors for the presence of CAD.

CONCLUSION

In CSA patients PAPP-A levels correlate with age, male gender, hypertension, and CAD extent. In the present study, PAPP-A was an independent predictor for the presence and extent of CAD.

Plasma levels of oxidized-low-density lipoproteins are higher in patients with unstable angina and correlated with angiographic coronary complex plaques

OBJECTIVES

To measure circulating levels of oxidized-low-density lipoproteins (ox-LDL) in patients with stable and unstable angina and controls, and to investigate their correlation with the extent of coronary artery disease (CAD) and the presence of complex plaques at coronary angiography.

METHODS AND RESULTS

Circulating ox-LDL were assessed, using ELISA, in patients with unstable angina (UA, n=26), stable angina (SA, n=29) and in controls (C, n=27). All patients underwent coronary angiography. The extent of CAD was evaluated using a quantitative score, while the presence of complex, vulnerable plaques was angiographically assessed. Ox-LDL were higher in UA patients than in SA patients and in C subjects, and in SA patients than in C subjects (C, 45.6+/-12.8 U/L; SA, 58.8+/-11.0 U/L; UA, 73.7+/-13.6 U/L; p<0.001). No correlation was found with the extent of atherosclerotic disease in the coronary tree. Patients with angiographic complex lesions showed significantly higher levels of ox-LDL (68.4+/-13.9 U/L versus 55.2+/-16.4 U/L, p<0.001). Multiple regression analysis showed that ox-LDL were independent predictors of the presence of complex plaques (p<0.023).

CONCLUSIONS

Ox-LDL levels are higher in unstable patients and correlate with the presence of angiographically documented complex plaques. Ox-LDL might be markers of destabilization of CAD.

Mechanism of neopterin-induced myocardial dysfunction in the isolated perfused rat heart

Neopterin is a sensitive marker for diseases involving increased activity of the cellular immune system in humans. Many studies, however, provide evidence for neopterin not only as a marker, but also for its characteristic effects. Recently, we were able to demonstrate a considerable influence of exogenous neopterin at a concentration of 100 mumol/l on cardiac performance in the Langendorff model of isolated perfused rat hearts. The present study was designed to investigate its possible mechanism. During co-infusion of neopterin at a concentration of 100 mumol/l with the unspecific nitric oxide synthase inhibitor N(G)-monomethyl-l-arginine monoacetate, the nitric oxide donor PAPA NONOate, the free radical scavenger N-acetylcysteine, or the pro-inflammatory cytokine tumor necrosis factor-alpha the effects on cardiac contractility parameters and coronary vascular resistance were studied in 67 male Sprague-Dawley rats. The temperature-controlled and pressure-constant Langendorff apparatus was used with retrograde perfusion of the aorta and a Krebs-Henseleit buffer. Neither the unspecific nitric oxide synthase inhibitor nor the nitric oxide donor excludes nitric oxide from playing a mechanistic role in our perfusion studies. Tumor necrosis factor-alpha was without any synergistic or antagonistic effects when co-treated with neopterin. N-acetylcysteine was most effective in abolishing neopterin-dependent effects on cardiac function. The negative effects of neopterin on cardiac performance might be due to an enhancement of oxidative stress by neopterin that can be attenuated by the antioxidant N-acetylcysteine. Neopterin has to be considered a pathogenic factor in the development of cardiac dysfunction in chronic disease states with high neopterin levels secondary to activation of the immune system.

Diffuse and Active Inflammation Occurs in Both Vulnerable and Stable Plaques of the Entire Coronary Tree

OBJECTIVES

This study was undertaken to define and compare geographic coronary artery inflammation in patients who were dying of acute myocardial infarction (AMI), chronic stable angina (SA), and noncardiac causes (CTRL).

BACKGROUND

Biochemical markers and flow cytometry provide indirect evidence of diffuse coronary inflammation in patients dying of acute coronary syndromes. Yet no histopathologic studies have corroborated these findings. A key unanswered question is whether the inflammatory burden involves the entire coronary tree or is limited to a few plaques.

METHODS

We examined 544 coronary artery segments from 16 patients with AMI, 109 segments from 5 patients with SA, and 304 coronary segments from 9 patients with CTRL.

RESULTS

An average of 6.8 +/- 0.5 vulnerable segments per patient were found in the AMI group (in addition to culprit lesions) compared with an average of 0.8 +/- 0.3 and 1.4 +/- 0.3 vulnerable lesions/patient in the SA and CTRL groups, respectively. The AMI group, independent of the type of plaque observed, showed significantly more inflammatory infiltrates compared with the SA and CTRL groups (121.6 +/- 12.4 cell x mm2 vs. 37.3 +/- 11.9 cell x mm2 vs. 26.6 +/- 6.8 cell x mm2, p = 0.0001). In AMI patients, active inflammation was not only evident within the culprit lesion and vulnerable plaques but also involved stable plaques. These showed a three- to four-fold higher inflammation than vulnerable and stable plaques from the SA and CTRL groups, respectively.

CONCLUSIONS

This histopathologic study found that both vulnerable and stable coronary plaques of patients dying of AMI are diffusely infiltrated by inflammatory cells.