Increased neopterin in patients with chronic and acute coronary syndromes

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.

Role of neopterin as an inflammatory biomarker in congestive heart failure with insights on effect of drug therapies on its level

Inflammation has a major role in the pathogenesis of heart failure (HF). It triggers a cascade that leads to the release of pro-inflammatory cytokines which in turn cause cardiac hypertrophy, fibrosis, apoptosis, negative inotorpy and leukocyte recruitment which worsen the condition. Neopterin is an inflammatory biomarker which is released as a response to macrophage activation. Levels of neopterin are elevated in conditions which has an immunological component such as autoimmune disease, viral and bacterial infections and malignancy. Neopterin levels were found to be elevated in patients with HF. This is due to the fact that inflammation takes place during the development of the condition. Studies demonstrated that neopterin can be used as a biomarker for diagnosing HF, determining severity of the disease and monitoring its progression. Neopterin levels were higher in patients with New York Heart Association classification (NYHA) III–IV more than class I–II. Moreover, neopterin levels correlated well with morbidity and mortality. It has been suggested that neopterin be monitored levels to determine effectiveness of HF treatment options.

Neopterin derivatives - a novel therapeutic target rather than biomarker for atherosclerosis and related diseases

This review provides an updated overview of the emerging roles of neopterin derivatives in atherosclerosis. Neopterin, a metabolite of guanosine triphosphate, is produced by interferon-γ-activated macrophages and is expressed at high levels in atheromatous plaques within the human carotid and coronary arteries as well as in the aorta. Plasma concentrations of neopterin are higher in patients with carotid, cerebral, and coronary artery diseases as well as aortic aneurysm. The concentration of neopterin is positively correlated with the severity of coronary artery disease. However, a prospective cohort study showed that neopterin contributes to protection against plaque formation in carotid arteries in patients with atherosclerosis. Moreover, using both in vitro and in vivo experiments, a recent study has shown the atheroprotective effects of neopterin. Neopterin suppresses the expression of monocyte chemotactic protein-1, vascular cell adhesion molecule-1, and intercellular adhesion molecule-1 in endothelial cells, and thereby suppresses the adhesion of monocytes to endothelial cells. It also suppresses the inflammatory phenotype of monocyte-derived macrophages. In addition, neopterin suppresses oxidized low-density lipoprotein-induced foam cell formation in macrophages and the migration and proliferation of vascular smooth muscle cells. Neopterin injection into apolipoprotein E-deficient (Apoe^-/-) mice suppresses the development of atherosclerotic lesions. A neopterin derivative tetrahydroneopterin (BH4), also known as a cofactor for nitric oxide (NO) synthases, suppresses atherosclerosis and vascular injury-induced neointimal hyperplasia in Apoe^-/- mice. BH4 administration improves endothelial dysfunction in patients with coronary artery disease. These findings suggest that neopterin production may increase to counteract the progression of atherosclerosis, as neopterin contributes to atheroprotection. Otherwise, the increased neopterin levels in atherosclerosis may reflect a compensatory mechanism associated with inducible NO synthase upregulation in macrophages to supply BH4 for high output NO production caused by decreased endothelial NO synthase in atherosclerosis. Therefore, neopterin derivatives are a novel therapeutic target for atherosclerosis and related diseases.

Prognostic effects of SuPAR and Neopterin Levels on Patients with Lung Cancer

Background: Two unique biomarkers, soluble form of the urokinase-type plasminogen activator receptor (suPAR) and neopterin, play a crucial role in inflammatory processes. This study aimed to reveal whether it is possible to utilize these biomarkers in predicting tumor prognosis in patients with lung cancers.

Methods: The present study was designed as a single center, prospective, and controlled research. The study was conducted with forty patients with lung cancer (case group) and 41 healthy individuals (control group) in Kırıkkale University, Faculty of Medicine between 2016-2020. The case group was also divided into two of the early and advanced stages. The blood samples were drawn to evaluate suPAR and neopterin levels, and these parameters were compared between the case and control groups. Also, the prognostic effects of age, stage of the tumor, and the levels of mentioned parameters were investigated with the survival analysis.

Results: The median duration of the follow-up was 32 (4-75) months. suPAR and neopterin levels were found to be higher in the case group than in the control group. Cox regression showed that the high levels of neopterin and suPAR increased mortality risk [p=0.002, HR: 1.25 (1.08-1.45 95%CI) and p=0.023, HR:1.07 (1.01-1.13), respectively]. Finally, age and stage of the tumor were found to have no relationship with survival.

Conclusion: suPAR and neopterin as members of the inflammatory pathway were found to be higher in cancer cases. Furthermore, both suPAR and neopterin levels were found to be predictive for the mortality of patients with lung cancers; therefore, they are thought to be used for the management of cancer.

L-sepiapterin restores SLE serum-induced markers of endothelial function in endothelial cells

OBJECTIVE

SLE serves as an independent risk factor` for endothelial dysfunction (ED) not explained by Framingham risk factors. We sought to understand the development of SLE-induced ED on a cellular level in order to develop strategies aimed at reversing cellular abnormalities. This study assessed the impact of SLE patient serum on endothelial nitric oxide synthase (eNOS), nitric oxide (NO) production and functional changes in the cell.

METHODS

Human umbilical vein endothelial cells (HUVECs) cultured in serum of either SLE (n=25) or healthy patients (n=14) or endothelial basal medium 2 (EBM-2) culture media supplemented with fetal bovine serum with or without L-sepiapterin were used for our studies. We applied the fluorescent probe DAF-FM diacetate for intracellular NO detection using flow cytometry. Total RNA isolates were analysed using reverse transcription PCR for eNOS mRNA expression. Oxygen consumption rate was determined using seahorse analysis. Neutrophil adhesion and migration were determined using a calcein AM microscopy assay.

RESULTS

The mRNA expression of eNOS was increased in SLE cultured HUVECs compared with healthy control (p<0.05). The SLE eNOS mRNA level correlated with SLE patient age (p=0.008); however, this trend was not observed with healthy patients. SLE serum reduced NO production in HUVECs compared with EBM-2 cultured cells (p<0.05). Co-treatment of endothelial cells with L-sepiapterin preserved HUVEC capacity to produce NO in SLE conditions (p<0.01). SLE serum enhanced neutrophil migration (p<0.01) but not neutrophil adhesion compared with healthy controls. The bioenergetic health index was not different.

CONCLUSIONS

SLE likely causes disruption of endothelial cell eNOS function and NO modulated pathways.

Neopterin Counters Vascular Inflammation and Atherosclerosis

BACKGROUND

Neopterin, a metabolite of GTP, is produced by activated macrophages and is abundantly expressed within atherosclerotic lesions in human aorta and carotid and coronary arteries. We aimed to clarify the influence of neopterin on both vascular inflammation and atherosclerosis, as neither effect had been fully assessed.

METHODS AND RESULTS

We investigated neopterin expression in coronary artery lesions and plasma from patients with coronary artery disease. We assessed the atheroprotective effects of neopterin in vitro using human aortic endothelial cells, human monocyte-derived macrophages, and human aortic smooth muscle cells. In vivo experiments included a study of aortic lesions in apolipoprotein E-deficient mice. Neopterin expression in coronary artery lesions and plasma was markedly increased in patients with versus without coronary artery disease. In human aortic endothelial cells, neopterin reduced proliferation and TNF-α (tumor necrosis factor α)-induced upregulation of MCP-1 (monocyte chemotactic protein 1), ICAM-1 (intercellular adhesion molecule 1), and VCAM-1 (vascular cell adhesion molecule 1). Neopterin attenuated TNF-α-induced monocyte adhesion to human aortic endothelial cells and the inflammatory macrophage phenotype via NF-κB (nuclear factor-κB) downregulation. Neopterin suppressed oxidized low-density lipoprotein-induced foam cell formation associated with CD36 downregulation and upregulation of ATP-binding cassette transporters A1 and G1 in human monocyte-derived macrophages. In human aortic smooth muscle cells, neopterin suppressed angiotensin II-induced migration and proliferation via c-Src/Raf-1/ERK1/2 downregulation without inducing apoptosis. Exogenous neopterin administration and endogenous neopterin attenuation with its neutralizing antibody for 4 weeks retarded and promoted, respectively, the development of aortic atherosclerotic lesions in apolipoprotein E-deficient mice.

CONCLUSIONS

Our results indicate that neopterin prevents both vascular inflammation and atherosclerosis and may be induced to counteract the progression of atherosclerotic lesions. Consequently, neopterin could be of use as a novel therapeutic target for atherosclerotic cardiovascular diseases.

Important Biomarkers that Play a Role in the Chronic Obstructive Pulmonary Disease Process

BACKGROUND

Chronic obstructive pulmonary disease (COPD) that includes multiple mechanisms such as inflammation, infection, smoking, hypoxia, and lack of antioxidant response can cause oxidative stress. In our study, we aimed to determine the changes in some oxidative stress [malondialdehyde and glutathione] and some cellular immunity markers (neopterin and TGF-b) in patients diagnosed with COPD and determine the damage to the organism.

METHODS

While the high-performance liquid chromatography (HPLC) method (Immuchrom kit, Germany) was utilized to determine MDA, GSH and NP levels, the ELISA method was used for TGF-b levels.

RESULTS

All obtained data regarding each parameter were compared with both COPD and healthy individuals and between parameters. There was a statistically significant difference between the control group of healthy subjects and COPD group in all parameters (p<0.05). A negative and correlation between oxidant MDA and antioxidant GSH parameters was determined (p=-0.394).

CONCLUSIONS

As a result, it was seen that oxidative balance changed in the patient group and cellular immunity increased. When the obtained data and literature are taken into account, these changes occurring in oxidative balance and cellular immunity are of importance in determining the development in the pathogenesis of COPD, treatment op - tions and their risks for heart disease in advance.

Neopterin as an Effect Modifier of the Cardiovascular Risk Predicted by Total Homocysteine: A Prospective 2-Cohort Study

BACKGROUND

Plasma total homocysteine (tHcy) is related to plasma neopterin, an indicator of interferon-γ-mediated immune activation, and both biomarkers positively predict cardiovascular risk. We examined whether the association between tHcy and subsequent risk of acute myocardial infarction (AMI) was modified by systemic concentrations of neopterin and C-reactive protein among patients with coronary heart disease.

METHODS AND RESULTS

By Cox modeling, we explored the association between tHcy and risk of AMI in 4164 patients with suspected stable angina pectoris. Subgroup analyses were performed according to median levels of neopterin and C-reactive protein. A replication study was performed among 3749 patients with AMI at baseline. Median follow-up was 7.3 and 8.3 years among patients with stable angina pectoris and AMI, respectively. tHcy and neopterin correlated in both cohorts (rs=0.34 and rs=0.30 among stable angina pectoris and AMI patients, respectively, both P<0.001). tHcy predicted AMI in both cohorts, independent of B-vitamin treatment. However, significant risk associations were confined to patients with plasma neopterin above the median (hazard ratios [95% confidence interval] per 1-SD increment of log-transformed tHcy 1.38 [1.26-1.50] and 1.18 [1.10-1.26] among stable angina pectoris and AMI patients, respectively) (Pint<0.005 in both cohorts). Further, adding information on the interaction between tHcy and neopterin improved model discrimination and reclassification. tHcy and C-reactive protein were weakly related, and no effect modification was found by C-reactive protein.

CONCLUSIONS

Among patients with coronary heart disease, tHcy predicted risk of AMI only in subjects with concomitantly elevated plasma neopterin. Our results motivate further research on the relationship between homocysteine metabolism, cellular immune activation, and atherothrombosis.

Neopterin and 7,8-dihydroneopterin are generated within atherosclerotic plaques

Plasma neopterin correlates with the level of cardiovascular disease. Neopterin is the oxidation product of 7,8-dihydroneopterin, which is released by γ-interferon-stimulated macrophages. 7,8-Dihydroneopterin is a potent antioxidant, which inhibits lipid oxidation, macrophage cell death and scavenger receptor CD36 expression. The concentration of neopterin within atherosclerotic plaques was measured in tissue removed from carotid and femoral arteries. The excised plaques were cut into 3-mm-thick sections, and each section was analysed for neopterin, total neopterin, cholesterol, lipid peroxides, α-tocopherol and protein-bound 3,4-dihydroxyphenylalanine. Selected plaques were placed in tissue culture, and the media was analysed for 7,8-dihydroneopterin and neopterin release. Total neopterin levels ranged from 14 to 18.8 nmol/g of tissue. Large ranges of values were seen both within the same plaque and between plaques. No correlation between neopterin and any of the other analytes was observed, nor was there any significant trend in levels along the length of the plaques. γ-Interferon stimulation of cultured plaque generated total neopterin concentrations from 1 to 4 nmol/(g 24 h). The level of 7,8-dihydroneopterin generated within the plaque was within the range that inhibits lipid oxidation. The data show that atherosclerotic plaques are extremely dynamic in biochemistry and are the likely source of the plasma 7,8-dihydroneopterin and neopterin.

Tetrahydrobiopterin in cardiovascular health and disease

Tetrahydrobiopterin (BH4) functions as a cofactor for several important enzyme systems, and considerable evidence implicates BH4 as a key regulator of endothelial nitric oxide synthase (eNOS) in the setting of cardiovascular health and disease. BH4 bioavailability is determined by a balance of enzymatic de novo synthesis and recycling, versus degradation in the setting of oxidative stress. Augmenting vascular BH4 levels by pharmacological supplementation has been shown in experimental studies to enhance NO bioavailability. However, it has become more apparent that the role of BH4 in other enzymatic pathways, including other NOS isoforms and the aromatic amino acid hydroxylases, may have a bearing on important aspects of vascular homeostasis, inflammation, and cardiac function. This article reviews the role of BH4 in cardiovascular development and homeostasis, as well as in pathophysiological processes such as endothelial and vascular dysfunction, atherosclerosis, inflammation, and cardiac hypertrophy. We discuss the therapeutic potential of BH4 in cardiovascular disease states and attempt to address how this modulator of intracellular NO-redox balance may ultimately provide a powerful new treatment for many cardiovascular diseases.

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.

Serum neopterin is not increased in obese juveniles

Objective. Cardiovascular disease is associated with inflammation and immune activation, concentrations of immune activation markers like neopterin predict outcome in adults. Methods. Serum neopterin concentrations and early metabolic and pre-atherosclerotic symptoms were analyzed in 295 obese juveniles and 101 normal weight controls of similar age. Additionally, the influence of a 12 months weight reduction program on neopterin levels was investigated in 31 obese juveniles. Results. Intima-media thickness of common carotid arteries (IMT) and the concentrations of C-reactive protein (CRP) were increased in the obese juveniles (P < .001). Also triglycerides, oxidized LDL, fasted insulin levels, HOMA-index, leptin, liver transaminases and uric acid were increased compared to the controls. However, serum neopterin was decreased in the obese versus non-obese juveniles (P < .03). The intervention consisting of regular sports, nutritional devices, and a psychologic attendance led after 12 months to an increase of neopterin concentration (P < .05; paired test). Conclusions. Neopterin concentrations in juvenile obesity behaved considerably different from what was demonstrated in adults, levels did not correlate with metabolic and pre-atherosclerotic symptoms found in early phases although early vascular burden and chronic low grade inflammation was indicated by increased IMT and CRP. Neopterin concentrations increased after a 12 months intervention program.

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.

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.

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.

Relations between concentrations of asymmetric dimethylarginine and neopterin as potential risk factors for cardiovascular diseases in haemodialysis-treated patients

OBJECTIVES

To investigate the correlation between concentrations of asymmetric dimethylarginine (ADMA) and neopterin (NP) as potential risk factors for cardiovascular diseases in chronic renal failure patients.

METHOD

In this study, 33 patients with renal failure before and after haemodialysis were compared with healthy control subjects. Serum ADMA and NP levels were measured using high performance liquid chromatography (HPLC).

RESULTS

When ADMA and NP concentrations in renal failure patients were compared before and after dialysis, before dialysis ADMA and NP concentrations were higher than those in the control group. However, ADMA and NP levels showed a falling mean and clear after dialysis. While there is no correlation between ADMA and NP levels before dialysis, there is a mean and positive correlation between ADMA and NP levels after dialysis.

CONCLUSION

Potential risk factors for cardiovascular diseases include high concentrations of both ADMA and NP levels in chronic renal failure patients. A correlation mean between ADMA and NP levels after dialysis was found, but no correlation between ADMA and NP levels before haemodialysis was discovered. These can be evaluated as two different risk factors independent from each other.

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.

Sorting through new biomarkers

Early diagnosis of acute coronary syndromes (ACS) allows for efficient risk stratification, appropriate targeted therapies, and faster patient disposition within crowded emergency departments. Although only troponin testing is recommended for routine use in the 2007 American College of Cardiology/American Heart Association guidelines for non-ST-elevation ACS, emerging data support selected use of other biomarkers, including B-type natriuretic peptides (BNPs) and C-reactive protein. There remains a need to identify additional biomarkers in ACS to enhance risk stratification and to help guide therapeutic decisions in this increasingly complex area of cardiovascular medicine. Cardiac biomarkers may help to diagnosis ACS before cardiomyocyte necrosis, to influence the decision for early invasive treatment, and to provide a means of monitoring response to therapy. In this review, we assess new data in ACS with respect to troponins, BNPs, myeloperoxidase, fatty acid-binding protein, and monocyte chemoattractant protein-1. We also discuss novel biomarkers including growth deficient factor-15 and neopterin.

Association between serum neopterin, obesity and daytime sleepiness in patients with obstructive sleep apnea

OBJECTIVE

Obesity and obstructive sleep apnea (OSA) and systemic inflammation may interact through biochemical pathways. Neopterin (NP) is a monocyte/macrophage activation marker produced by macrophages in response to interferon-gamma secreted by activated T-lymphocytes. This study examines the association between NP, obesity and OSA.

PATIENTS AND METHODS

The study included 22 newly diagnosed OSA (+) patients and 18 OSA (-) patients. Subjects with history of coronary artery disease, transplant patients, history of alcohol and drug abuse, history of HIV and any other significant medical illnesses such as active infections, autoimmune disease, malignancy, liver disease, pulmonary disease (COPD, asthma,...), neuromuscular disease, patients on immunomodulating therapy or HMG-CoA reductase inhibitors were excluded.

RESULTS

There were no significant differences in age, body mass index (BMI), and smoking habits of the OSA (+) patients and OSA (-) patients. Serum NP levels did not show any significant difference between the OSA (+) patients and OSA (-) patients, however, NP levels were positively correlated with BMI (r=0.320, p=0.044). There was no significant correlation between NP and any of the polysomnographic parameters. The result of stepwise regression analyses (r(2)=0.320, p<0.001) showed that high serum NP levels (p=0.004) and apnea-hypopnea index (AHI) were a risk factor for elevated Epworth sleepiness score, independent of BMI.

CONCLUSION

We suggest that serum NP levels correlate with BMI. There was a significant relationship between serum NP levels and excessive daytime sleepiness in OSA patients.

Inverse association between serum concentrations of neopterin and antioxidants in patients with and without angiographic coronary artery disease

Neopterin is released from human monocyte-derived macrophages upon stimulation with interferon-gamma and is a sensitive indicator for cellular immune activation. Furthermore, reactive oxygen species (ROS) are produced in case of immune activation and inflammation. In a cross-sectional approach, plasma concentrations of neopterin and of antioxidant compounds and vitamins were compared in 1463 patients investigated by coronary angiography, which were recruited within the LUdwigshafen RIsk and Cardiovascular Health (LURIC) study. Serum neopterin concentrations were higher in patients with coronary artery disease (CAD; mean+/-S.D.: 8.7+/-7.3 nmol/L) compared to controls (7.4+/-5.0 nmol/L; Welch's t-test: p<0.001). Mean concentrations of ascorbic acid (p<0.0001), gamma-tocopherol (p<0.05), lycopene (p<0.001), lutein+zeaxanthin (p<0.05), alpha-carotene (p<0.05) and beta-carotene (p<0.05) were lower in CAD than in controls. Neopterin concentrations correlated with CAD-score (r(s)=0.156; p<0.0001) and inversely with antioxidants lycopene (r(s)=-0.277; p<0.0001) and lutein+zeaxanthin (r(s)=-0.175; p<0.0001) levels and with vitamins ascorbic acid (r(s)=-0.207; p<0.0001) and alpha-tocopherol (r(s)=-0.105; p<0.0001). The study demonstrates that higher neopterin production is associated with lower concentrations of antioxidant compounds in patients at risk for atherosclerosis. Results suggest that lower concentrations of antioxidant compounds may relate to higher grade of chronic immune activation in patients.

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.

Non-traditional biomarkers of atherosclerosis in stable and unstable coronary artery disease, do they differ?

BACKGROUND

Biomarkers of atherosclerosis are emerging as a potential tool for assessment of coronary artery disease (CAD) patients. As acute coronary syndrome (ACS), and stable CAD are distinguished in their pathophysiology it is conceivable that they are also characterized by different biomarkers of atherosclerosis.

METHODS

We systematically reviewed the literature for clinical studies of several non-traditional biomarkers of atherosclerosis reflecting various pathophysiological processes, namely macrophage-activity, oxidative-stress, tissue remodeling, and thrombosis in ACS and stable CAD to determine whether circulating biomarkers are differently expressed/predict outcome in these two clinical conditions.

RESULTS

Macrophage-activity (monocyte chemoattractant protein-1, neopterin), tissue-remodeling (matrix metalloproteinase-9) and thrombosis (tissue-factor) related biomarkers were consistently elevated in ACS compared to stable CAD, in accordance with the pathophysiological role of these mediators in plaque rupture, characterizing ACS. Thus, these biomarkers may be applicable for diagnosis of ACS. Additionally, neopterin was consistently shown to predict outcome in both stable and ACS patients and myeloperoxidase was strongly shown to predict outcome in ACS, implying for their potential role in risk stratification of these patients.

CONCLUSIONS

As ACS and stable CAD are characterized by different pathophysiological processes, it appears that the biomarkers that are associated with them are differently expressed in these two clinical conditions

Inflammatory and Apoptotic Markers in Ischemic Heart Disease Patients

Ischemic heart disease is the most frequent cause of cardiovascular morbidity and mortality. It is developed on the basis of atherosclerosis which is today considered a chronic inflammatory disease. It is documented by an increase in inflammatory and immune biomarkers, such as C-reactive protein, fibrinogen, neopterin, leukocytes, lymphocytes and others, that are significantly changed in patients with unstable angina or acute myocardial infarction. CRP is mostly studied. Increased concentrations of CRP are associated with a series of risk factors. CRP may predict recurrent events and mortality independently of cardiac troponin levels, and it is also an independent predictor of a cardiovascular event after adjustment for traditional risk factors. Although CRP currently appears to be the most promising biological marker, there is still controversy regarding its use in clinical practice. Both necrotic and apoptotic cell death are documented during atherogenesis, however, limited data are available about apoptotic markers in ischemic heart disease patients. Increasing evidence supports the existence of apoptotic death initiated by ligation of membrane-bound death receptors or by release of cytochrome c from mitochondria, as well as their regulators in the heart. The studies of serum markers show that the apoptotic process is disregulated in ischemic heart disease patients. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is present in stable atherosclerotic lesions, is increased in vulnerable plaques, but its serum levels are reduced significantly in patients with unstable angina. Serum Fas concentrations are increased and FasL are decreased in subjects at high cardiovascular risk. The results of our study show significant changes in serum Fas, FasL, and Bcl-2 concentrations, and lymphocyte caspase-3 activity in different stages of ischemic heart disease. For now, there is evidence that statins are effective in the regulation of some apoptotic markers. The better understanding of the pathways of apoptosis and their regulation is promissing in yielding novel therapeutic targets for cardiovascular disease.

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.

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.

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.