Cytokine concentrations in exhaled breath condensates in systemic sclerosis

Inflammatory Biomarkers in Exhaled Breath Condensate: A Systematic Review

Inflammation is a comprehensive set of physiological processes that an organism undertakes in response to a wide variety of foreign stimuli, such as viruses, bacteria, and inorganic particles. A key role is played by cytokines, protein-based chemical mediators produced by a broad range of cells, including the immune cells recruited in the inflammation site. The aim of this systematic review is to compare baseline values of pro/anti-inflammatory biomarkers measured in Exhaled Breath Condensate (EBC) in healthy, non-smoking adults to provide a summary of the concentrations reported in the literature. We focused on: interleukin (IL)-1β, IL-4, IL-6, IL-8, IL-10, tumour necrosis factor-alpha (TNF-α), and C reactive protein (CRP). Eligible articles were identified in PubMed, Embase, and Cochrane CENTRAL. Due to the wide differences in methodologies employed in the included articles concerning EBC sampling, storage, and analyses, research protocols were assessed specifically to test their adherence to the ATS/ERS Task Force guidelines on EBC. The development of reference intervals for these biomarkers can result in their introduction and use in both research and clinical settings, not only for monitoring purposes but also, in the perspective of future longitudinal studies, as predictive parameters for the onset and development of chronic diseases with inflammatory aetiology.

Exhaled Breath Condensate: Pilot Study of the Method and Initial Experience in Healthy Subjects

Analysis of Exhaled breath condensate (EBC) is a re-discovered approach to monitoring the course of the disease and reduce invasive methods of patient investigation. However, the major disadvantage and shortcoming of the EBC is lack of reliable and reproducible standardization of the method. Despite many articles published on EBC, until now there is no clear consensus on whether the analysis of EBC can provide a clue to diagnosis of the diseases. The purpose of this paper is to investigate our own method, to search for possible standardization and to obtain our own initial experience. Thirty healthy volunteers provided the EBC, in which we monitored the density, pH, protein, chloride and urea concentration. Our results show that EBC pH is influenced by smoking, and urea concentrations are affected by the gender of subjects. Age of subjects does not play a role. The smallest coefficient of variation between individual volunteers is for density determination. Current limitations of EBC measurements are the low concentration of many biomarkers. Standardization needs to be specific for each individual biomarker, with focusing on optimal condensate collection. EBC analysis has a potential become diagnostic test, not only for lung diseases.

The role of interleukin-4 in rheumatic diseases

Rheumatism is a group of diseases, most of which are autoimmune diseases, that violate joints, bones, muscles, blood vessels and related soft tissue. As is well known, cytokines play a role in the pathogenesis of several rheumatic diseases, such as rheumatoid arthritis, spondyloarthritides, and systemic lupus erythematosus. Recently, the role of interleukin-4 (IL-4), which may participate in the mechanism of rheumatism, have been discovered. It is reported that IL-4 takes part in the regulation of T cell activation, differentiation, proliferation, and survival of different T cell types. IL-4 also has an immunomodulatory effect on B cells, mast cells, macrophages, and many cell types. A review of the literature on functions of IL-4 in rheumatic diseases is presented.

Exhaled breath NOx levels in a middle-aged adults population-based study: reference values and association with the smoking status

BACKGROUND

Biomarkers in exhaled breath condensate (EBC) are potentially sensitive indicators of early biochemical changes in airways following exposure to pneumotoxic substances, particularly in susceptible subjects. NOx are the stable end products of the nitrite-nitrate-NO oxidative stress pathway and can be used to monitor airway inflammatory diseases, especially in asthma. Nevertheless, population-based surveys are needed to better interpret EBC NOx levels in clinical studies. The aim of this study was to establish reference values of EBC NOx in a large group of middle-aged, healthy adults of a sample of the general population with particular focus on the smoking status.

METHODS

The EBC NOx levels were analysed from 2872 subjects among the ELISABET population-based cross sectional study including a representative sample of men and women aged from 40 to 66 years olds conducted in northern France, which included comprehensive questionnaires by interview and spirometry data. Healthy participants were defined as participants with no self-reported respiratory disease.

RESULTS

For the healthy subjects (n = 1251), the median NOx concentration (IQR) was equal to 7.2  μM (3.12) and concentrations of NOx in EBC did not differ significantly according to smoking status. The upper fifth percentile (95%) (ULN) of NOx concentrations among healthy subjects was equal to 13.6  μM, ranging from 12.7  μM (smokers) to 14.4  μM (ex smokers). Among subjects with EBC NOx values higher than the ULN and compared with subjects that had EBC NOx values lower than the ULN, we found a significant higher proportion of subjects with current asthma (10.5% vs 6.5%) or with chronic bronchitis symptoms (7.6% vs 3.3%).

CONCLUSION

This population-based study has provided the distribution and the upper limit reference value of a nitrosative stress biomarker (NOx) in EBC of middle aged, healthy adults. EBC NOx levels were not associated with smoking status.

Influence of air pollution on airway inflammation and disease activity in childhood-systemic lupus erythematosus

Exposure to fine particles may trigger pulmonary inflammation/systemic inflammation. The objective of this study was to investigate the association between daily individual exposure to air pollutants and airway inflammation and disease activity in childhood-onset systemic lupus erythematosus (cSLE) patients. A longitudinal panel study was carried out in 108 consecutive appointments with cSLE patients without respiratory diseases. Over four consecutive weeks, daily individual measures of nitrogen dioxide (NO₂), fine particulate matter (PM_2.5), ambient temperature, and humidity were obtained. This cycle was repeated every 2.5 months along 1 year, and cytokines of exhaled breath condensate-EBC [interleukins (IL) 6, 8, 17 and tumoral necrose factor-α (TNF-α)], fractional exhaled NO (FeNO), and disease activity parameters were collected weekly. Specific generalized estimation equation models were used to assess the impact of these pollutants on the risk of Systemic Lupus Erythematous Disease Activity Index 2000 (SLEDAI-2K) ≥ 8, EBC cytokines, and FeNO, considering the fixed effects for repetitive measurements. The models were adjusted for inflammatory indicators, body mass index, infections, medication, and weather variables. An IQR increase in PM_2.5 4-day moving average (18.12 μg/m³) was associated with an increase of 0.05 pg/ml (95% CI 0.01; 0.09, p = 0.03) and 0.04 pg/ml (95% CI 0.02; 0.06, p = 0.01) in IL-17 and TNF-α EBC levels, respectively. Additionally, a short-term effect on FeNO was observed: the PM_2.5 3-day moving average was associated with a 0.75 ppb increase (95% CI 0.38; 1.29, p = 0.03) in FeNO. Also, an increase of 1.47 (95% CI 1.10; 1.84) in the risk of SLEDAI-2K ≥ 8 was associated with PM_2.5 7-day moving average. Exposure to inhalable fine particles increases airway inflammation/pulmonary and then systemic inflammation in cSLE patients.

Prognostic Role of Exhaled Breath Condensate pH and Fraction Exhaled Nitric Oxide in Systemic Sclerosis Related Interstitial Lung Disease

INTRODUCTION

Interstitial lung disease (ILD) is one of the major causes of death in systemic sclerosis (SSc). This study investigated exhaled breath (EB) and exhaled breath condensate (EBC) biomarkers in patients with SSc and analyzed their role as a prognostic tool in SSc-related ILD.

METHODS

Fraction exhaled nitric oxide (FeNO) and exhaled carbon monoxide (eCO) measured in EB, together with pH, nitrite, nitrate and interleukin-6 levels measured in EBC were prospectively analyzed in 35 patients with SSc. Twelve patients had established ILD by chest high-resolution computed tomography (HRCT), and 23 patients showed no evidence of ILD. EB and EBC biomarkers were determined at inclusion, and pulmonary function tests were annually performed during 4 years of follow-up.

RESULTS

No differences at baseline biomarkers levels were found between groups. In all patients studied, low EBC pH levels were associated with a decreased diffusing capacity for carbon monoxide (DLCO) during follow-up. Low FeNO levels were correlated with lower forced vital capacity (FVC) at baseline, 4years of follow-up and with a decrease in FVC and DLCO during monitoring. Among ILD patients, high eCO levels were correlated with lower baseline FVC. In the global cohort, a worse progression-free survival was identified in patients with EBC pH values lower than 7.88 and FeNO levels lower than 10.75ppb (Log Rank P=.03 and P<.01, respectively).

CONCLUSIONS

EB and EBC could help to detect patients likely to present a deterioration on lung function during follow up.

Th-17 cytokines and interstitial lung involvement in systemic sclerosis

The two phenotypes of both limited and diffuse systemic sclerosis (SSc) have different forms of pulmonary involvement: pulmonary arterial hypertension (limited phenotype) or interstitial lung disease (ILD) (diffuse phenotype). We aimed to investigate whether Th17-related cytokines, as measured in exhaled breath condensate (EBC) and in serum were connected to ILD in diffuse SSc patients. We found that for both limited and diffuse SSc, the EBC levels of all cytokines and most of the cytokine serum levels were significantly higher in patients than in controls, while, the EBC levels of Th-17 cytokines and the serum levels of IL-10 and TNF-α were significantly higher in diffuse than in limited SSc. Moreover, the thoracic CT-scan score of ILD was significantly associated with the EBC levels of IL-1 beta and with the serum IL-23, TNF-α and IL-10 levels, whereas lung carbon monoxide diffusing capacity was negatively related to the EBC levels of IL-1 beta, IL-17 and serum IL-10. Serum IL-23 was also inversely correlated with vital capacity. In conclusion, in diffuse SSc patients our results show a clear link between Th-17 cytokines measured both in EBC and in serum with interstitial lung involvement. This highlights how important it is to target Th-17 cytokines when developing new treatments for lung fibrosis.

Assessment of nanoparticles and metal exposure of airport workers using exhaled breath condensate

Aircraft engine exhaust increases the number concentration of nanoparticles (NP) in the surrounding environment. Health concerns related to NP raise the question of the exposure and health monitoring of airport workers. No biological monitoring study on this profession has been reported to date. The aim was to evaluate the NP and metal exposure of airport workers using exhaled breath condensate (EBC) as a non-invasive biological matrix representative of the respiratory tract. EBC was collected from 458 French airport workers working either on the apron or in the offices. NP exposure was characterized using particle number concentration (PNC) and size distribution. EBC particles were analyzed using dynamic light scattering (DLS) and scanning electron microscopy coupled to x-ray spectroscopy (SEM-EDS). Multi-elemental analysis was performed for aluminum (Al), cadmium (Cd) and chromium (Cr) EBC contents. Apron workers were exposed to higher PNC than administrative workers (p  <  0.001). Workers were exposed to very low particle sizes, the apron group being exposed to even smaller NP than the administrative group (p  <  0.001). The particulate content of EBC was brought out by DLS and confirmed with SEM-EDS, although no difference was found between the two study groups. Cd concentrations were higher in the apron workers (p  <  0.001), but still remained very low and close to the detection limit. Our study reported the particulate and metal content of airport workers airways. EBC is a potential useful tool for the non-invasive monitoring of workers exposed to NP and metals.

T-bet and interleukin-27: possible TH1 immunomodulators of sarcoidosis

Background

Sarcoidosis has often been termed an “immune paradox” as there is peripheral anergy to common recall antigens despite pronounced T_H1-dominant inflammation at disease sites, such as the lung, with up-regulation of interferon γ, IL-27 and transcription factors. Peripheral blood may reflect the anergic state, while exhaled breath condensate (EBC) analysis may offer insights into the lung disease.

Methods

A cross-sectional study was conducted to investigate the expression of T_H1 cytokines and transcription factors (IFNγ, IL-27 and T-bet) in the peripheral blood and/or EBC of sarcoidosis patients and healthy controls. Whole blood and EBC were collected from sarcoidosis patients and healthy controls. T_H1 cytokine expression levels were then measured in peripheral blood mononuclear cells (PBMCs) and/or plasma and EBC using quantitative real-time PCR, ELISA and via Western blotting.

Results

Compared to healthy controls, PBMC IL-27 mRNA was higher in patients (p = 0.0019). There were no significant differences in plasma IL-27 protein between patients and controls (p = 0.20). T-bet mRNA and protein were lower (p = 0.010 and p = 0.0043, respectively) in patients compared to controls. There were no significant differences in PBMC IFNγ mRNA and protein expression (p = 0.68 and p = 0.74, respectively) nor in EBC IL-27 levels.

Conclusions

Our data indicate that depressed T-bet mRNA and protein expression could contribute to the peripheral anergy in sarcoidosis and that IL-27 mRNA levels are elevated in the PBMC from those with sarcoidosis.

Electronic supplementary material

The online version of this article (doi:10.1007/s10787-015-0247-y) contains supplementary material, which is available to authorised users.

[Angiogenesis and its association with inflammation and fibrosis in course of the development of scleroderma systematica]

Scleroderma systematica (SDS) is a chronic autoimmune disease characterized by severe fibrosis of the skin and visceral organs. Vascular disorders are an important component of the disease, but the mechanisms of vascular injury and their prevention are unknown. Angiogenesis in SDS is accompanied by the apparent expression of angiogenic factors, such as vascular endothelial growth factor and basal or fibroblast growth factor. Imbalance of these markers with endostatin expression is noted. This disease is characterized by inflammation and the intensity of neoangiogenesis correlates with its activity. The fact that there may be a pathogenic relationship between the processes of angiogenesis and the intensity of further fibrosis is shown. There is a vicious circle of the induction and maintenance of the processes of angiogenesis, inflammation, and fibrosis in SDS.

Inflammatory cytokines in exhaled breath condensate in children with inflammatory bowel diseases

BACKGROUND

Although inflammatory bowel diseases (IBD) affect mainly the gastrointestinal tract, the extra-intestinal manifestations are not uncommon. Different diagnostic methods have been applied to assess pulmonary involvement in patients with IBD, but majority of these methods show significant limitations in children. The aim of our study was to evaluate the usefulness of exhaled breath condensate (EBC) measurements of pro-inflammatory cytokines in children with IBD.

MATERIAL AND METHODS

Twenty-two children with Crohn's disease (CD) (mean age 13.8 ± 3.3 years), 25 with ulcerative colitis (UC) (mean age 14.1 ± 3.3 years) and 37 healthy volunteers (mean age 13.9 ± 3.6 years) were studied. IBD activity was assessed using appropriate scoring systems. None of the patients had signs or symptoms of pulmonary disease. Exhaled breath condensate was collected and EBC concentration of interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin 8 (IL-8) was measured.

RESULTS

The concentrations of all the assessed cytokines were significantly higher in the study group as compared to controls. A negative correlation between IL-1β and CD activity index was found. There were no significant relationships between TNF-α, IL-6, or IL-8 level and CD activity index as well as between IL-1β, TNF-α, IL-6, IL-8 and UC activity index. No significant correlation between the concentration of IL-1β, TNF-α, IL-6, IL-8, and IBD duration or treatment duration was found.

CONCLUSIONS

Elevated concentration of pro-inflammatory cytokines in EBC in children with IBD may suggest the presence of asymptomatic inflammation in the lower airways.

Manganese in exhaled breath condensate: a new marker of exposure to welding fumes

OBJECTIVE

To evaluate manganese in exhaled breath condensate (Mn-EBC) as an indicator of exposure to fumes from metal inert gas welding process.

METHODS

We collected EBC and urine from 17 welders and 16 unexposed control subjects after 5 days exposure. Concentrations of manganese (Mn), nickel (Ni), iron (Fe) and chromium (Cr) were measured in EBC and urine samples and correlated with cumulative exposure indices for the working week (CIW) and for the total welding years (WY), based on duration of welding activity and atmospheric metal measurements.

RESULTS

Concentrations of Mn and Ni in EBC were significantly higher among welders than controls whereas this difference was not significant for Mn in urine. Levels of Mn and Ni in EBC were not correlated with their respective levels in urine. The linear regressions found significant positive coefficients between Mn-EBC, Ni-EBC, Ni-U and Cr-U concentrations and the cumulative exposure indices. Taking into account tobacco use, statistical analysis showed the same trends except for the relationship between Mn-U and CIW.

CONCLUSION

This pilot study showed that Mn-EBC, as well as Ni-EBC, can serve as reliable indices of occupational exposure to welding fumes and provide complimentary toxicokinetic information to that provided by urine analyses.

Exhaled breath condensate: a comprehensive update

Since the late 1990s, a surge in interest in the analysis of exhaled breath condensate (EBC) resulted in the American Thoracic Society and European Respiratory Society (ATS/ERS) organising a Task Force in 2001 to develop guidelines on EBC collection and measurement of biomarkers. This Task Force published their guidelines in 2005 based on literature and expert opinions at that time, and multiple shortcomings and knowledge deficits were also identified. The clinical application of EBC collection and its biomarkers are currently still limited by several of these knowledge gaps, hence further guidelines for standardisation are required to ensure external validity. Using related articles produced since the publication of the ATS/ERS Task Force report, this paper attempts to provide a comprehensive update to the original guideline and review the methodological shortcomings identified. This review can hopefully serve as a yardstick for future studies involving this emerging clinical tool.

Induced sputum, exhaled NO, and breath condensate in occupational medicine

OBJECTIVE

Studies of fractional exhaled NO (FeNO) or induced sputum are now well standardized and the exponential increase in publications about exhaled breath condensate reflects growing interest in a noninvasive diagnosis of pulmonary diseases in occupational medicine.

METHODS

This review describes current techniques (FeNO, induced sputum, and exhaled breath condensate) for the study of inflammation and oxidative stress biomarkers.

RESULTS

These biomarkers are FeNO, cytokines, H2O2, 8-isoprostane, malondialdehyde, and nitrogen oxides. These techniques also include the study of markers of the toxic burden in the lungs (heavy metals and mineral compounds) that are important in occupational health exposure assessment.

CONCLUSIONS

In occupational medicine, the study of both volatile and nonvolatile respiratory biomarkers can be useful in medical surveillance of exposed workers, the early identification of respiratory diseases, or the monitoring of their development.

Methodological aspects of exhaled breath condensate collection and analysis

The collection and analysis of exhaled breath condensate (EBC) may be useful for the management of patients with chronic respiratory disease at all ages. It is a promising technique due to its apparent simplicity and non-invasiveness. EBC does not disturb an ongoing respiratory inflammation. However, the methodology remains controversial, as it is not yet standardized. The current diversity of the methods used to collect and preserve EBC, the analytical pitfalls and the high degree of within-subject variability are the main issues that hamper further development into a clinical useful technique. In order to facilitate the process of standardization, a simplified schematic approach is proposed. An update of available data identified open issues on EBC methodology. These issues were then classified into three separate conditions related to their influence before, during or after the condensation process: (1) pre-condenser conditions related to subject and/or environment; (2) condenser conditions related to condenser equipment; and (3) post-condenser conditions related to preservation and/or analysis. This simplified methodological approach highlights the potential influence of the many techniques used before, during and after condensation of exhaled breath. It may also serve as a methodological checklist for a more systematical approach of EBC research and development.

Exhaled breath condensate (EBC) biomarkers in pulmonary fibrosis

The diffuse parenchymal lung diseases (DPLDs) are a group of clinicopathological entities which have recently undergone reclassification. The commonest type of idiopathic DPLD is interstitial pulmonary fibrosis (PF), which is histologically characterized by usual interstitial pneumonia (UIP), with inflammatory changes in the alveoli and subsequent collagen deposition. A similar type of inflammatory change can also be seen with connective tissue disorders. Many mediators are involved, but it is difficult to study these in a non-invasive manner in patients. The aim of the study detailed in this paper was to investigate inflammatory and oxidative stress biomarkers in PF and correlate these with lung function. 20 PF patients and 20 controls participated in the study. Exhaled breath condensate (EBC) was collected over 10 min using a refrigerated condenser, after fractional exhaled nitric oxide (FeNO) and carbon monoxide (eCO) measurement. EBC total nitrogen oxides (NOx), hydrogen peroxide (H(2)O(2)), 8-isoprostane (8-iso), 3-nitrotyrosine (3-NT), pH and total protein were measured. EBC biomarkers were significantly raised in PF compared with controls: EBC 3-NT (2.5 (0.7-8.9) versus 0.3 (0.1-1.1) ng ml(-1), p = 0.02); pH (7.6 ± 0.3 versus 7.4 ± 0.2, p = 0.004); 8-isoprostane (0.2 (0.1-0.4) versus 0.08 (0.04-0.2) ng ml(-1), p = 0.04) and total protein (24.7 ± 21.1 versus 10.7 ± 7.0 µg ml(-1), p = 0.008). FeNO and eCO were also increased (8.6 (7.1-10.4) versus 6.6 (5.6-7.8) ppb, p = 0.04, and 4.5 ± 1.7 versus 2.7 ± 0.7 ppm, p = 0.001, respectively), but no significant differences were found for NOx or H(2)O(2). In conclusion, inflammatory and oxidative stress biomarkers are raised in patients with PF compared with controls. EBC may be useful for detecting and monitoring lung inflammation in PF.

Interest of exhaled biomarkers in occupational asthma to latex: a case report

New methods for exploring pulmonary inflammation might be useful: measurements of exhaled nitric oxide (NO) and hydrogen peroxide (H(2)O(2)) in exhaled breath condensate (EBC). The authors describe the application and utility of these methods in a case report of pediatric nurse presenting an occupational asthma to latex. Despite compliance with avoidance measures, respiratory discomfort had worsened during work. Classical tests (spirometry, monitoring of peak expiratory flow) were not contributing to objectify the discomfort. Exhaled NO and H(2)O(2) in EBC increased immediately after work periods, compared with rest periods. Application of these new methods, at the same time, in workplace appears useful in the objective demonstration of a temporal relation between work and respiratory problems. The results allowed the occupational physician to transfer the patient to a new work station more appropriate for her respiratory health status.

Analysis of nitrogen oxides (NOx) in the exhaled breath condensate (EBC) of subjects with asthma as a complement to exhaled nitric oxide (FeNO) measurements: a cross-sectional study

Background

The study of pulmonary biomarkers with noninvasive methods, such as the analysis of exhaled breath condensate (EBC), provides a useful approach to the pathophysiology of asthma. Although many recent publications have applied such methods, numerous methodological pitfalls remain. The first stage of our study consisted of validating methods for the collection, storage and analysis of EBC; we next sought to clarify the utility of analysing nitrogen oxides (NOx) in the EBC of asthmatics, as a complement to measuring exhaled nitric oxide (FeNO).

Methods

This hospital-based cross-sectional study included 23 controls matched with 23 asthmatics. EBC and FeNO were performed and respiratory function measured. Intra-assay and intra-subject reproducibility were assessed for the analysis of NOx in the EBC of 10 healthy subjects.

Results

The intraclass correlation coefficient (ICC) was excellent for intra-assay reproducibility and was moderate for intra-subject reproducibility (Fermanian's classification). NOx was significantly higher in asthmatics (geometric mean [IQR] 14.4 μM [10.4 - 19.7] vs controls 9.9 μM [7.5 - 15.0]), as was FeNO (29.9 ppb [17.9 - 52.4] vs controls 9.6 ppb [8.4 - 14.2]). FeNO also increased significantly with asthma severity.

Conclusions

We validated the procedures for NOx analysis in EBC and confirmed the need for assays of other biomarkers to further our knowledge of the pathophysiologic processes of asthma and improve its treatment and control.