Plasma and exhaled breath condensate nitrite–nitrate level in relation to environmental exposures in adults in the EGEA study
Highlights
► We studied associations of nitrite/nitrate level and four environmental exposures. ► In plasma nitrite/nitrate level increased with consumption of leafy vegetables. ► In EBC nitrite/nitrate level decreased with exposure to ambient ozone. ► Tobacco smoke was associated with lower plasma and EBC nitrite/nitrate level. ► Environmental exposures may modify plasma and EBC nitrite/nitrate levels.
Introduction
Known biological markers involved in the nitrosative pathway, also called the “nitrate–nitrite–nitric oxide” pathway, are nitric oxide (NO), nitrites () and nitrates (), which are indirect stable indicators of NO synthesis. These biological markers play a key role in several physiological functions ranging from neuromodulation to regulation of vascular tone [1], and are involved in local host defense, gut mucosal integrity and also in cardiovascular [2] and airway diseases [3]. Pharmacological and dietary interventions on prevention and treatment of diseases are now under study [4]. Until now, epidemiological studies have been mainly conducted on the fraction of exhaled NO (FeNO). Diet is the most important source of both (mostly from cured meats) and (mostly from leafy vegetables) [5]. Formation of and can also take place after inhalation of exogenous compounds like oxidants from cigarette smoke [6], [7], nitrogen dioxide (NO2) and ozone (O3) from air pollution [8], and chlorine from cleaning agents [9].
The negative association between exposure to tobacco smoke and FeNO is well known [10], while the association between FeNO with other environmental exposures has been explored more in children [11], [12] than in adults [13]. However, few epidemiological and clinical studies have focused on the associations between environmental exposures and /. In the occupational setting, Gube et al. [14] reported that welders had high concentrations, and Ghasemi et al. [15] found increasing serum / levels in smokers compared to non- and ex-smokers.
In biological fluids, the half-life of nitric oxide (NO) is extremely short owing to its rapid oxidation to nitrites () and nitrates () [16]. Total / levels are usually measured in blood (plasma or serum) but can also be measured in exhaled breath condensate (EBC). Interest in the analysis of EBC constituents has increased in the last 10 years, because EBC is viewed as a promising tool for non-invasive evaluation of lung diseases [17]. As plasma and EBC are two distinct body constituents, we hypothesized that direct or indirect environmental sources of and might have differential effects on / levels in plasma and EBC. Production of / in plasma is more complex than in EBC. In the latter, ionized and (not volatile) may be produced from NO after reaction with oxygen [18] or from activated immune cells present in the lining of the lungs [19]. In plasma, / production derives from several sources, such as bacteria, enzymatic production and dietary sources [16]. To clarify the role of environmental exposures on levels of biological markers in the nitrosative pathway, associations between smoking, dietary habits, ambient air pollution, and chlorine products with total / level both in plasma and EBC were evaluated in adults from the Epidemiological study on the Genetics and Environment of Asthma (EGEA).
Section snippets
Study population
Data used for the analyses were collected in the framework of the 12-year follow-up of the EGEA study (http://cesp.vjf.inserm.fr/egeanet/). The EGEA study has been described elsewhere [20], [21]. Briefly, it combines a case-control study with a family study of asthma cases (children or adults) conducted between 1991 and 1995 in 2047 subjects from five French cities. A follow-up of the initial cohort was conducted between 2003 and 2007 [22]. Among the alive cohort (n = 2002), 92% (n = 1845)
Results
Characteristics of the 949 adults according to their asthma status and sex are summarized in Table 1. EBC / levels did not vary with storage time and plasma / slightly decreased with storage time (Beta for linear regression model = −0.03, P = 0.03).
Analysis of variations according to sex and 10-year age classes was first performed (see Supplementary Fig. A.1). It showed that women older than 45 years had higher total plasma / levels (P-value for interaction between age and
Discussion
The present study focused for the first time on the associations between four environmental exposures and total / levels measured both in plasma and in EBC among nearly 1000 adults. Total plasma / levels were higher in menopausal women, increased with leafy vegetable consumption, and decreased in current smokers. A similar association with smoking was observed in EBC. Lower levels of total EBC /− were found in association with increasing annual ambient concentration
Conclusion
In conclusion, we report for the first time that environmental and behavioral risk factors may modify / levels. Our results suggest specificities of NO metabolism in EBC and in plasma and highlight the importance of studying the same biological marker in different compartments. These findings could have implications for several diseases for which oxidative and nitrosative stresses are involved in their physiopathological pathways. Further studies are needed especially in the general
Acknowledgments
The authors thank all those who participated in the study and in the various aspects of the examinations and all those who supervised the study in all centers. The authors are grateful to the three CIC-Inserm units of Necker, Grenoble and Marseille which supported the study and where subjects were examined. They are also grateful to the three biobanks in Lille (CIC-Inserm), Evry (Centre National de Genotypage) and Annemasse (Etablissement francais du sang) where biological samples are stored.
References (50)
- et al.
Reactive nitrogen species in the respiratory tract
Eur. J. Pharmacol.
(2006) - et al.
Chlorine-induced injury to the airways in mice
Am. J. Respir. Crit. Care Med.
(2003) - et al.
The effect of ambient air pollution on exhaled nitric oxide in the Children’s Health Study
Eur. Respir. J.
(2000) Exhaled breath condensate: an evolving tool for noninvasive evaluation of lung disease
J. Allergy. Clin. Immunol.
(2002)Exhaled breath condensate: an overview
Immunol. Allergy Clin. North Am.
(2007)- A.M. Fitzpatrick, L.A. Brown, F. Holguin, W.G. Teague, Levels of nitric oxide oxidation products are increased in the...
- et al.
Nitrite and nitrate determinations in plasma: a critical evaluation
Clin. Chem.
(1995) - et al.
Nitric oxide and exhaled breath nitrite/nitrates in chronic obstructive pulmonary disease patients
Respiration
(2007) - et al.
Influence of sex and age on serum nitrite/nitrate concentration in healthy subjects
Clin. Chim. Acta.
(2000) - et al.
Serum nitric oxide metabolite (NO(x)) levels in hypertensive patients at rest: a comparison of age, gender, blood pressure and complications using normotensive controls
Clin. Exp. Pharmacol. Physiol.
(2007)
Validation of nitrite and nitrate measurements in exhaled breath condensate
Respiration
All-natural nitrite and nitrate containing dietary supplement promotes nitric oxide production and reduces triglycerides in humans
Nutr. Res.
Inorganic nitrate supplementation lowers blood pressure in humans: role for nitrite-derived NO
Hypertension
Negative feedback regulation of endothelial cell function by nitric oxide
Circ. Res.
Dietary nitrite in nitric oxide biology: A redox interplay with implications for pathophysiology and therapeutics
Curr Drug Targets.
Nitrate and nitrite in biology, nutrition and therapeutics
Nat. Chem. Biol.
Biology of nitrogen oxides in the gastrointestinal tract
Gut
Assessment of dietary exposure of nitrate and nitrite in France
Food Addit. Contam. Part A Chem. Anal. Control Expo Risk Assess
Oxidants in cigarette smoke. Radicals, hydrogen peroxide, peroxynitrate, and peroxynitrite
Ann. N. Y. Acad. Sci.
Increased nitric oxide metabolites in exhaled breath condensate after exposure to tobacco smoke
Thorax
Health effects of air pollution
J. Allergy Clin. Immunol.
Exhaled nitric oxide and influencing factors in a random population sample
Respir. Med.
Exhaled NO among inner-city children in New York City
J. Asthma
A cross-shift study of lung function, exhaled nitric oxide and inflammatory markers in blood in Norwegian cement production workers
Occup Environ Med.
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