HMG-CoA reductase inhibitors are associated with decreased serum neopterin levels in stable coronary artery disease

Does smoking influence tryptophan metabolism in periodontal inflammation? A cross-sectional study

OBJECTIVES

The aim of this study was to identify the effects of smoking and periodontal inflammation on tryptophan-kynurenine metabolism as well as the correlation between these findings and clinical periodontal parameters.

BACKGROUND

It has been shown that the tryptophan amino acid's primary catabolic pathway, the kynurenine pathway (KP), may serve as a key biomarker for periodontal disease. Although there are studies investigating the effect of smoking on KYN-TRP metabolism, the effect of smoking on periodontal disease through KP has not been revealed so far.

METHODS

The salivary and serum samples were gathered from 24 nonsmoker (NS-P) stage III, grade B generalized periodontitis and 22 smoker (S-P) stage III, grade C generalized periodontitis patients, in addition to 24 nonsmoker (NS-C) and 24 smoker (S-C) periodontally healthy control individuals. Saliva and serum IL-6, kynurenine (KYN), and tryptophan (TRP) values, and KYN/TRP ratio were analyzed by liquid chromatography-mass spectrometry. Clinical periodontal measurements were recorded.

RESULTS

Salivary TRP values were significantly higher in both periodontitis groups than control groups (p < .05). Salivary KYN values were highest in NS-P group (p < .05). Salivary KYN values did not differ significantly between periodontitis groups (p = .84). Salivary KYN/TRP ratio was significantly lower in NS-P group compared to other groups (p < .001). Serum TRP value is higher in S-P group than other groups; however, significant difference was found in S-C group (p < .05). Serum KYN values were significantly lower in smokers than nonsmokers. Serum KYN/TRP ratio is higher in NS-P group. NS-P group has the highest salivary IL-6 levels, NS-C group has the lowest values (p < .05).

CONCLUSIONS

Our results point out that smoking exacerbates inflammation in the periodontium and increases TRP destruction and decreases IDO activity by suppressing KP in serum. As a result, kynurenine and its metabolites may be significant biomarkers in the link between smoking and periodontal disease.

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.

Statin use and markers of immunity in the Doetinchem cohort study

It has been suggested that statins can both stimulate and suppress the immune system, and thereby, may influence autoimmune diseases. Therefore, we studied effects of statins on innate and adaptive immunity, and self-tolerance by measuring serological levels of C-reactive protein (CRP), neopterin, immunoglobulin E (IgE) antibodies and the presence of autoantibodies (antinuclear antibodies (ANA) and IgM rheumatoid factor (RF)) in the general population. We conducted a nested case-control study within the population-based Doetinchem cohort. Data from health questionnaires, serological measurements and information on medication from linkage to pharmacy-dispensing records were available. We selected 332 statin users (cases) and 331 non-users (controls), matched by age, sex, date of serum collection, history of cardiovascular diseases, diabetes mellitus type II and stroke. Multivariate regression analyses were performed to estimate effect of statins on the immune system. The median level of CRP in statin users (1.28 mg/L, interquartile range (IQR): 0.59-2.79) was lower than in non-users (1.62 mg/L, IQR: 0.79-3.35), which after adjustment was estimated to be a 28% lower level. We observed an inverse association between duration of statin use and CRP levels. Elevated levels of IgE (>100 IU/mL) were more prevalent in statin users compared to non-users. A trend towards increased levels of IgE antibodies in statin users was observed, whereas no associations were found between statin use and levels of neopterin or the presence of autoantibodies. In this general population sub-sample, we observed an anti-inflammatory effect of statin use and a trend towards an increase of IgE levels, an surrogate marker for Th (helper) 2 responses without a decrease in neopterin levels, a surrogate marker for Th1 response and/or self-tolerance. We postulate that the observed decreased inflammatory response during statin therapy may be important but is insufficient to induce loss of self-tolerance.

Endocrine and immunological parameters in individuals involved in Prestige spill cleanup tasks seven years after the exposure

In November 2002 the oil tanker Prestige spilled 63,000tonnes of heavy oil off the northwest coast of Spain, impacting more than 1000km of coastline. A general concern led to a huge mobilization of human and technical resources, and more than 300,000 people participated in cleanup activities, which lasted up to 10months. Some endocrine and immunological alterations were reported in Prestige oil exposed subjects for several months. Therefore, the objective of this study was to evaluate if these alterations are still present seven years after the exposure. Fifty-four individuals exposed for at least 2months were compared to 50 matched referents. Prolactin and cortisol plasma concentrations, percentages of lymphocyte subsets (CD3(+), CD4(+), CD8(+), CD19(+), and CD56(+)16(+)), plasma levels of circulating cytokines (interleukin (IL) 2, IL4, IL6, IL10, tumour necrosis factor α, and interferon γ), and serum concentrations of neopterin, tryptophan and kynurenine were determined in peripheral blood samples. Results showed significant differences in exposed individuals vs. referents only in cortisol (increase), kynurenine and %CD16(+)56(+) lymphocytes (both decrease). Time of exposure to the oil or using protective clothes did not influence the results, but effect of using protective mask was observed on neopterin, %CD8(+), CD4(+)/CD8(+) ratio and IL4. Surveillance of the exposed individuals for early detection of possible health problems related to the endocrine or immunological systems is recommended.

Assessment of immunotoxicity parameters in individuals occupationally exposed to lead

Although adverse health effects produced by lead (Pb) have long been recognized, studies regarding the immunotoxic effects of occupational exposure report conflicting results. In a previous study, alterations in some immunological parameters were noted in 70 Pb-exposed workers. In view of these results, it was of interest to extend this study comprising a larger population and increasing the number of immunological endpoints assessed. Accordingly, in this study the immunotoxic effects of occupational exposure to Pb were assessed by analyzing (1) percentages of lymphocyte subsets (CD3⁺, CD4⁺, CD8⁺, CD19⁺, and CD56⁺/16⁺); (2) concentration of plasma cytokines, namely, interleukin (IL) 2, IL4, IL6, IL10, tumor necrosis factor (TNF) α, and interferon (IFN) γ; and (3) plasma concentrations of neopterin, tryptophan (Trp), and kynurenine (Kyn). In addition, the possible influence of genetic polymorphisms in the vitamin D receptor (VDR) and δ-aminolevulinic acid dehydratase (ALAD) genes on immunotoxicity parameters was studied. Exposed workers showed significant decreases in %CD3⁺, %CD4⁺/%CD8⁺ ratio, IL4, TNFα, IFNγ, and Kyn to Trp ratio (Kyn/Trp), and significant increases in %CD8⁺, IL10, and Trp levels. All these parameters, except Trp, were significantly correlated with exposure biomarkers. No significant influence of genetic polymorphisms was observed. Significant correlation between Kyn/Trp and neopterin concentrations suggests an involvement of indoleamine 2,3-dioxygenase in the Trp metabolic alterations, which may contribute to some of the immune alterations observed. Results obtained suggest that occupational exposure to PB may influence the immune system by impairing several mechanisms, which might ultimately produce deregulation of the immune response and diminish immunosurveillance in exposed individuals.

Association of detectable cytomegalovirus (CMV) DNA in monocytes rather than positive CMV IgG serology with elevated neopterin levels in community-dwelling older adults

In immunocompetent persons, cytomegalovirus (CMV) is thought to persist primarily in monocytes and myeloid progenitor cells, establishing a chronic infection. In older adults, chronic CMV infection is typically diagnosed by a positive IgG serology. While many studies have shown CMV-specific T-cell expansion in CMV seropositive older individuals, significant heterogeneity has also been observed in this elderly population. In a study of 71 community-dwelling older adults, we assessed CMV viral DNA in peripheral monocytes by nested PCR and compared the relationships of detectable CMV DNA and IgG serology with serum levels of neopterin, a marker for monocyte/macrophage-mediated immune activation. The results showed that 52 (73.2%) participants were CMV seropositive, of whom 30 (57.5%) had detectable CMV DNA. CMV seropositive and seronegative participants did not differ in their neopterin levels, but individuals with detectable CMV DNA had higher neopterin than those without (10.6 ± 4.4 vs 8.0 ± 1.9 nM, respectively, p<.0001) adjusting for demographic and clinical covariates and interferon (IFN)-γ levels. In addition, there was no association between IgG titers and neopterin. These findings suggest that detection of CMV viral DNA in monocytes may be an informative tool to evaluate chronic CMV infection and its potential role in monocyte/macrophage-mediated immune activation in the elderly.

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.

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.

Alterations in serum neopterin correlate with thrombolysis in myocardial infarction risk scores in acute coronary syndromes

OBJECTIVES

Using serum neopterin as a marker of macrophage activation, we sought to examine the relationship between serum neopterin levels, thrombolysis in myocardial infarction (TIMI) risk scores, and how different treatments of acute coronary syndromes affect change in neopterin.

METHODS

We examined serum neopterin concentrations at presentation and 72 h after treatment in 70 patients with acute coronary syndromes (35 with medical therapy, 25 with uncoated coronary stents, and 10 received rapamycin-eluting stents) using a commercially available immunoassay. Serum neopterin levels were determined for 36 patients with stable coronary artery disease. TIMI risk scores were calculated when appropriate (n=58).

RESULTS

Serum neopterin had a strong correlation with the TIMI risk score on admission (P<0.0001). The mean baseline neopterin levels in patients with acute coronary syndromes stratified with TIMI scores between 1 and 7 were the following: patients with TIMI 1 scores had a level of 3.3+/-0.4 nmol/l, TIMI 2 patients 4.6+/-0.6 nmol/l, TIMI 3 patients 5.5+/-1.4 nmol/l, TIMI 4 patients 7.5+/-2.4 nmol/l, TIMI 5 patients 10.8+/-3.3 nmol/l, TIMI 6 patients 17.5+/-4.0 nmol/l, and TIMI 7 patients 23.0+/-7.1 nmol/l. Mean changes in serum neopterin were significantly higher for the uncoated stent group than for each of the other three groups (P<0.05).

CONCLUSIONS

Serum neopterin concentrations have a high correlation with TIMI risk scores and may represent a marker useful in stratifying patients with acute coronary syndromes. Our results also suggest that the use of uncoated coronary stents results in macrophage activation not found with other treatment modalities.

Atorvastatin suppresses homocysteine formation in stimulated human peripheral blood mononuclear cells

Hyperhomocysteinemia is regarded as an independent risk factor for vascular diseases, and homocysteine is supposed to contribute to oxidative stress and endothelial damage. Statin therapy is an established intervention to reduce the risk of acute events in patients suffering from cardiovascular diseases. Apart from their lipid-lowering capacity, statins also exert anti-inflammatory and antioxidant effects. As cellular immune activation and oxidative stress play a major role in the pathogenesis of cardiovascular diseases, the anti-inflammatory capacity of statins could partly be responsible for the beneficial effects observed in patients. Earlier we reported that stimulated peripheral blood mononuclear cells (PBMCs) release homocysteine. Here we studied the influence of atorvastatin on homocysteine production in stimulated PBMCs and compared changes in cysteine concentrations and in neopterin production, which is a sensitive indicator of cellular immune activation. Stimulation of human PBMCs with the mitogens concanavalin A and phytohemagglutinin induced significant homocysteine and neopterin production compared to unstimulated cells, whereas cysteine concentrations remained unchanged. Treatment of PBMCs with increasing doses of atorvastatin (10-100 microM) suppressed both biochemical pathways in a dose-dependent manner, and cell proliferation was inhibited in parallel. Again, cysteine levels were not influenced by any treatment. The down-regulating effect of atorvastatin on homocysteine formation in vitro indicates that statins may prevent homocysteine accumulation in the blood via immunosuppression.

Increased inflammatory markers in children with familial hypercholesterolaemia

BACKGROUND

While data are abundant on increased levels of inflammatory markers in adult patients with hypercholesterolaemia, such data in children are limited. Therefore, we sought to investigate the degree and character of inflammation in children with heterozygous familial hypercholesterolaemia (FH) by measuring levels of neopterin, high-sensitivity C-reactive protein (hsCRP), and soluble CD40 ligand (sCD40L).

MATERIALS AND METHODS

In the present study, we compared the concentration of inflammatory markers in children suffering from heterozygous FH (n = 207) with those in unaffected siblings (n = 84). Furthermore, we investigated the effect of 2-year treatment with pravastatin (20-40 mg qd) or placebo on plasma levels of those markers.

RESULTS

Our main finding was that serum levels of neopterin and hsCRP were significantly higher in FH children compared with healthy siblings, whereas sCD40L was not. Body mass index and high-density lipoprotein cholesterol levels were significant independent predictors of hsCRP and neopterin. Furthermore, pravastatin therapy decreased neopterin, but not hsCRP and sCD40L, in the FH children, but these changes were not different from the placebo group.

CONCLUSION

These findings indicate low-grade monocyte/macrophage hyperactivity in the early stages of atherogenesis, but our findings also suggest that inflammation as well as anti-inflammatory effects of statins are less prominent features of atherosclerosis in FH children than in FH adults.

Biomarkers of cardiac disease

The challenge of medical practice today is to identify individuals who are at risk of developing disease, determine the severity of the disease and distinguish the responders from the nonresponders to therapy (individualized medicine). Advances in molecular genetics and biology have shifted the paradigm for identification of markers from large-scale epidemiologic studies to studies on genomic- and proteomic-based techniques. Consequently, a large number of biologic markers, referred to as biomarkers, are being identified and validated to serve for risk stratification, prognostication and individualization of therapy. Identification of biomarkers for cardiovascular diseases could also provide insight into the pathogenesis of the phenotype, which is fundamental for the development of specific therapies. The list of biomarkers for cardiovascular disease is expanding rapidly. Nonetheless, the field is in the early stages of evolution and large-scale clinical studies are required to validate the utility of newly identified biomarkers in diagnosis, risk stratification and treatment of cardiovascular diseases. Selected biomarkers for coronary atherosclerosis, acute coronary syndromes and heart failure are discussed in this review.