Breath condensate pH in children with cystic fibrosis and asthma: a new noninvasive marker of airway inflammation?

Detection of respiratory inflammation biomarkers in non-processed exhaled breath condensate samples using reduced graphene oxide

In this work, we studied several important parameters regarding the standardization of a portable sensor of nitrite, a key biomarker of inflammation in the respiratory tract in untreated EBC samples. The storage of the EBC samples and electrical properties of both EBC samples and the sensor as main standardization parameters were investigated. The sensor performance was performed using differential pulse voltammetry (DPV) in a standard nitrite solution and untreated EBC samples. The storage effect was monitored by comparing sensor data of fresh and stored samples for one month at -80 °C. Results show, on average, a 20 percent reduction of peak current for stored solutions. The sensor's performance was compared with a previous EBC nitrite sensor and chemiluminescence method. The results demonstrate a good correlation between the present sensor and chemiluminescence for low nitrite concentrations in untreated EBC samples. The electrical behavior of the sensor and electrical variation between EBC samples were characterized using methods such as noise analysis, electrochemical impedance spectroscopy (EIS), electrical impedance (EI), and voltage shift. Data show that reduced graphene oxide (rGO) has lower electrical noise and a higher electron transfer rate regarding nitrite detection. Also, a voltage shift can be applied to calibrate the data based on the electrical variation between different EBC samples. This result makes it easy to calibrate the electrical difference between EBC samples and have a more reproducible portable chip design without using bulky EI instruments. This work helps detect nitrite in untreated and pure EBC samples and evaluates critical analytical EBC properties essential for developing portable and on-site point-of-care sensors.

A pilot study of total personal exposure to volatile organic compounds among Hispanic female domestic cleaners

Cleaners have an elevated risk for the development or exacerbation of asthma and other respiratory conditions, possibly due to exposure to cleaning products containing volatile organic compounds (VOCs) leading to inflammation and oxidative stress. This pilot study aimed to quantify total personal exposure to VOCs and to assess biomarkers of inflammation and pulmonary oxidative stress in 15 predominantly Hispanic women working as domestic cleaners in San Antonio, Texas, between November 2019 and July 2020. In partnership with a community organization, Domésticas Unidas, recruited women were invited to attend a training session where they were provided 3M 3500 passive organic vapor monitors (badges) and began a 72-hr sampling period during which they were instructed to wear one badge during the entire period ("AT," for All the Time), a second badge only while they were inside their home ("INS," for INSide), and a third badge only when they were outside their home ("OUT," for OUTside). At the end of the sampling period, women returned the badges and provided blood and exhaled breath condensate (EBC) samples. From the badges, 30 individual VOCs were measured and summed to inform total VOC (TVOC) concentrations, as well as concentrations of the following VOC groups: aromatic hydrocarbons, alkanes, halogenated hydrocarbons, and terpenes. From the blood and EBC samples, concentrations of serum C-reactive protein (CRP) and EBC 8-isoprostane (8-ISP) and pH were quantified. Data analyses included descriptive statistics. The 72-hr average of personal exposure to TVOC was 34.4 ppb and ranged from 9.2 to 219.5 ppb. The most prevalent class of VOC exposures for most women (66.7%) was terpenes, specifically d-limonene. Overall, most women also experienced higher TVOC concentrations while outside their home (86.7%) as compared to inside their home. Serum CRP concentrations ranged from 0.3 to 20.3 mg/dL; 8-ISP concentrations ranged from 9.5 to 44.1 pg/mL; and EBC pH ranged from 7.1 to 8.6. Overall, this pilot study demonstrated personal VOC exposure among Hispanic domestic cleaners, particularly to d-limonene, which may result from the use of scented cleaning products.

Exhaled Breath Condensate-A Non-Invasive Approach for Diagnostic Methods in Asthma

The pathophysiology of asthma has been intensively studied, but its underlying mechanisms such as airway inflammation, control of airway tone, and bronchial reactivity are still not completely explained. There is an urgent need to implement novel, non-invasive diagnostic tools that can help to investigate local airway inflammation and connect the molecular pathways with the broad spectrum of clinical manifestations of asthma. The new biomarkers of different asthma endotypes could be used to confirm diagnosis, predict asthma exacerbations, or evaluate treatment response. In this paper, we briefly describe the characteristics of exhaled breath condensate (EBC) that is considered to be an interesting source of biomarkers of lung disorders. We look at the composition of EBC, some aspects of the collection procedure, the proposed biomarkers for asthma, and its clinical implications. We also indicate the limitations of the method and potential strategies to standardize the procedure of EBC collection and analytical methods.

Electrochemical sensing: A prognostic tool in the fight against COVID-19

The COVID-19 pandemic has devastated the world, despite all efforts in infection control and treatment/vaccine development. Hospitals are currently overcrowded, with health statuses of patients often being hard to gauge. Therefore, methods for determining infection severity need to be developed so that high-risk patients can be prioritized, resources can be efficiently distributed, and fatalities can be prevented. Electrochemical prognostic biosensing of various biomarkers may hold promise in solving these problems as they are low-cost and provide timely results. Therefore, we have reviewed the literature and extracted the most promising biomarkers along with their most favourable electrochemical sensors. The biomarkers discussed in this paper are C-reactive protein (CRP), interleukins (ILs), tumour necrosis factor alpha (TNFα), interferons (IFNs), glutamate, breath pH, lymphocytes, platelets, neutrophils and D-dimer. Metabolic syndrome is also discussed as comorbidity for COVID-19 patients, as it increases infection severity and raises chances of becoming infected. Cannabinoids, especially cannabidiol (CBD), are discussed as a potential adjunct therapy for COVID-19 as their medicinal properties may be desirable in minimizing the neurodegenerative or severe inflammatory damage caused by severe COVID-19 infection. Currently, hospitals are struggling to provide adequate care; thus, point-of-care electrochemical sensor development needs to be prioritized to provide an approximate prognosis for hospital patients. During and following the immediate aftermath of the pandemic, electrochemical sensors can also be integrated into wearable and portable devices to help patients monitor recovery while returning to their daily lives. Beyond the COVID-19 pandemic, these sensors will also prove useful for monitoring inflammation-based diseases such as cancer and cardiovascular disease.

Ivacaftor-induced sweat chloride reductions correlate with increases in airway surface liquid pH in cystic fibrosis

BACKGROUND

Disruption of cystic fibrosis transmembrane conductance regulator (CFTR) anion channel function causes cystic fibrosis (CF), and lung disease produces most of the mortality. Loss of CFTR-mediated HCO3- secretion reduces the pH of airway surface liquid (ASL) in vitro and in neonatal humans and pigs in vivo. However, we previously found that, in older children and adults, ASL pH does not differ between CF and non-CF. Here, we tested whether the pH of CF ASL increases with time after birth. Finding that it did suggested that adaptations by CF airways increase ASL pH. This conjecture predicted that increasing CFTR activity in CF airways would further increase ASL pH and also that increasing CFTR activity would correlate with increases in ASL pH.

METHODS

To test for longitudinal changes, we measured ASL pH in newborns and then at 3-month intervals. We also studied people with CF (bearing G551D or R117H mutations), in whom we could acutely stimulate CFTR activity with ivacaftor. To gauge changes in CFTR activity, we measured changes in sweat Cl- concentration immediately before and 48 hours after starting ivacaftor.

RESULTS

Compared with that in the newborn period, ASL pH increased by 6 months of age. In people with CF bearing G551D or R117H mutations, ivacaftor did not change the average ASL pH; however reductions in sweat Cl- concentration correlated with elevations of ASL pH. Reductions in sweat Cl- concentration also correlated with improvements in pulmonary function.

CONCLUSIONS

Our results suggest that CFTR-independent mechanisms increase ASL pH in people with CF. We speculate that CF airway disease, which begins soon after birth, is responsible for the adaptation.

FUNDING

Vertex Inc., the NIH (P30DK089507, 1K08HL135433, HL091842, HL136813, K24HL102246), the Cystic Fibrosis Foundation (SINGH17A0 and SINGH15R0), and the Burroughs Wellcome Fund.

Mapping targetable inflammation and outcomes with cystic fibrosis biomarkers

Cystic fibrosis is characterized by an overly exuberant neutrophilic inflammatory response to pathogens and other stimuli that starts very early in disease. The overwhelming nature of this response is a primary cause of remodeling and destruction of the airways, suggesting that anti-inflammatory therapies could be beneficial in CF. However, finding therapies that can effectively reduce the inflammatory response without compromising host defenses remains elusive. New approaches towards mapping inflammatory targets promise to aid in developing novel therapeutic strategies and improve outcomes in individuals with CF.

Acidosis exacerbates in vivo IL-1-dependent inflammatory responses and neutrophil recruitment during pulmonary Pseudomonas aeruginosa infection

Acidic microenvironments commonly occur at sites of inflammation and bacterial infections. In the context of a Pseudomonas aeruginosa infection, we previously demonstrated that acidosis enhances the cellular proinflammatory interleukin (IL)-1β response in vitro. However, how pH alterations affect in vivo IL-1β responses and subsequent IL-1-driven inflammation during infection with P. aeruginosa is unclear. Here, we report that acidosis enhances in vivo IL-1β production and downstream IL-1 receptor-dependent responses during infection with P. aeruginosa in models of acute pneumonia and peritonitis. Importantly, we demonstrate that infection with P. aeruginosa within an acidic environment leads to enhanced production of a subset of proinflammatory cytokines, including chemokine (C-X-C) motif ligand 1, IL-6, and chemokine (C-C motif) ligand 2, and increased neutrophil recruitment. Furthermore, with the use of IL-1 receptor type 1-deficient mice, we identify the contribution of the IL-1 signaling pathway to the acidosis-enhanced inflammatory response and pathology. These data provide insights into the potential benefit of pH regulation during bacterial infections to control disease progression and immunopathology.

Smartphone-Based pH Sensor for Home Monitoring of Pulmonary Exacerbations in Cystic Fibrosis

Currently, Cystic Fibrosis (CF) patients lack the ability to track their lung health at home, relying instead on doctor checkups leading to delayed treatment and lung damage. By leveraging the ubiquity of the smartphone to lower costs and increase portability, a smartphone-based peripheral pH measurement device was designed to attach directly to the headphone port to harvest power and communicate with a smartphone application. This platform was tested using prepared pH buffers and sputum samples from CF patients. The system matches within ~0.03 pH of a benchtop pH meter while fully powering itself and communicating with a Samsung Galaxy S3 smartphone paired with either a glass or Iridium Oxide (IrOx) electrode. The IrOx electrodes were found to have 25% higher sensitivity than the glass probes at the expense of larger drift and matrix sensitivity that can be addressed with proper calibration. The smartphone-based platform has been demonstrated as a portable replacement for laboratory pH meters, and supports both highly robust glass probes and the sensitive and miniature IrOx electrodes with calibration. This tool can enable more frequent pH sputum tracking for CF patients to help detect the onset of pulmonary exacerbation to provide timely and appropriate treatment before serious damage occurs.

Luminescent rare-earth-based MOFs as optical sensors

This perspective article highlights the basics and applications of luminescence-based sensing of hazardous chemicals, pH, and temperature using rare-earth-based metal–organic frameworks.

How strong is the association between IPF and lung cancer? An answer from airway's DNA

Idiopathic pulmonary fibrosis is a chronic progressive disease of lung interstitium of unknown etiology with poor prognosis. In patients with IPF, the incidence of lung cancer is much higher than that in the general population. The identification of noninvasive biomarkers for early diagnosis of IPF is of great relevance in consideration of the management of these patients. Among the noninvasive omic markers, an increasing interest has been directed toward the study of genetic alterations of microsatellites (MAs) in exhaled breath condensate (EBC). The aim of this preliminary study was to investigate the MAs, located in chromosomal regions 8p21.3-q11.1 and 17q11.2-q21, that harbor tumor suppressor genes, in EBC and in the paired whole blood (WB) of IPF patients. Eleven IPF patients were compared with 10 healthy control subjects. All subjects underwent collection of the EBC and WB. The EBC was collected using a condenser. Four microsatellite markers (THRA1, D17S579, D17S250 and D8S137) were used for the analysis of MAs. The EBC-DNA and WB-DNA were amplified by PCR; PCR products were analyzed using the ABI Prism 310 DNA. Microsatellite alterations were found in 58.82 % of EBC-DNA and 12.50 % of WB-DNA in patients with IPF (p < 0.01). None of the healthy subjects exhibited MAs in the studied markers. Our findings suggest that these genetic alterations, studied in EBC, may play an important role in the complex genetic basis of IPF. Since these MAs are frequently detected in cancer, they might explain the higher relative risk of tumorigenesis in this disease.

IL-8 and pH Values in Exhaled Condensate after Antibiotics in Cystic Fibrosis Children

Interleukin (IL)-8 is a major factor in inflammatory response and the IL-8 levels in exhaled breath condensate (EBC) may be used as a marker of airway inflammation. Airway acidification is implicated in the pathophysiology of obstructive airway diseases and pH EBC values have been used as a marker of airway acidification. The aim of our study is to investigate whether IL-8 and pH levels in EBC of cystic fibrosis (CF) children with respiratory exacerbations change after antibiotic treatment. Lung function, IL-8 and pH EBC values were measured in fifteen CF children (mean age 11 years) with acute exacerbation before (T0) and after two weeks (T1) of antibiotic treatment. IL-8 and pH values were compared by paired t-test. A p<0.05 was considered significant. IL-8 EBC levels decreased after antibiotic treatment (TO 0.36±0.03pg/ml vs T1 0.28±0.03pg/ml; p=0.03) and pH values increased (TO 7.3610.09 vs T1 7.61±0.08; p=0.04). Results suggest possible application of EBC as a non-invasive tool to monitor efficacy of antibiotic treatment in CF patients.

The analysis of volatile organic compounds in exhaled breath and biomarkers in exhaled breath condensate in children - clinical tools or scientific toys?

Current monitoring strategies for respiratory diseases are mainly based on clinical features, lung function and imaging. As airway inflammation is the hallmark of many respiratory diseases in childhood, noninvasive methods to assess the presence and severity of airway inflammation might be helpful in both diagnosing and monitoring paediatric respiratory diseases. At present, the measurement of fractional exhaled nitric oxide is the only noninvasive method available to assess eosinophilic airway inflammation in clinical practice. We aimed to evaluate whether the analysis of volatile organic compounds (VOCs) in exhaled breath (EB) and biomarkers in exhaled breath condensate (EBC) is helpful in diagnosing and monitoring respiratory diseases in children. An extensive literature search was conducted in Medline, Embase and PubMed on the analysis and applications of VOCs in EB and EBC in children. We retrieved 1165 papers, of which nine contained original data on VOCs in EB and 84 on biomarkers in EBC. These were included in this review. We give an overview of the clinical applications in childhood and summarize the methodological issues. Several VOCs in EB and biomarkers in EBC have the potential to distinguish patients from healthy controls and to monitor treatment responses. Lack of standardization of collection methods and analysis techniques hampers the introduction in clinical practice. The measurement of metabolomic profiles may have important advantages over detecting single markers. There is a lack of longitudinal studies and external validation to reveal whether EB and EBC analysis have added value in the diagnostic process and follow-up of children with respiratory diseases. In conclusion, the use of VOCs in EB and biomarkers in EBC as markers of inflammatory airway diseases in children is still a research tool and not validated for clinical use.

The effects of lung recruitment maneuvers on exhaled breath condensate pH

Exhaled breath condensate (EBC) pH serves as a surrogate marker of airway lining fluid (ALF) pH and can be used to evaluate airway acidification (AA). AA is known to be present in acute respiratory distress syndrome (ARDS) and can be evaluated via continuous EBC pH measurement during mechanical ventilation. Lung recruitment maneuvers (LRMs) are utilized in the treatment of ARDS, however, their impact on EBC pH has never been explored. Here we described the acute effects of two commonly used LRMs on EBC pH. In a prospective, non-randomized, serial exposure study, 10 intubated pediatric subjects with acute respiratory distress syndrome sequentially underwent: a period of baseline ventilation, sustained inflation (SI) maneuver of 40 cm H2O for 40 s, open lung ventilation, staircase recruitment strategy (SRS) (which involves a systematic ramping of plateau pressures in 5 cm H2O increments, starting at 30 cm H2O), and PEEP titration. Maximum lung recruitment during the SRS is defined as a PaO2 + PaCO2 of  >400 mmHg. Following lung recruitment, PEEP titration was conducted from 20 cm H2O in 2 cm H2O decrements until a PaO2 + PaCO2 was  <380 and then increased by 2 cm H2O. EBC pH, arterial blood gases, lung mechanics, hemodynamics, and function residual capacity were obtained following each phase of the LRM and observational period. Seven out of 10 patients were able to reach maximum lung recruitment. Baseline EBC pH (6.38   ±   0.37) did not correlate with disease severity defined by PaO2/FiO2 ratio or oxygenation index (OI). Average EBC pH differed between phases and decreased after LRM (p = 0.001). EBC pH is affected by LRMs. EBC acidification following LRMs may represent a washout effect of opening acidic lung units and ventilating them or acute AA resulting from LRM.

Europium(III)-β-diketonate complex-containing nanohybrid luminescent pH detector

In this work, by loading an Eu(3+)-β-diketonate complex into LAPONITE®, we report an organic-inorganic hybrid pH detection system Eu(3+)(TTA)n@Lap that is valid under acid conditions, which can serve as highly robust, reliable, rapid responsive and sensitive fluorescent pH detector. In addition, this hybrid pH detector can be easily recovered and reused by simply treating with Et3N vapor.

Exhaled Breath Condensate: Technical and Diagnostic Aspects

Purpose. The aim of this study was to evaluate the 30-year progress of research on exhaled breath condensate in a disease-based approach. Methods. We searched PubMed/Medline, ScienceDirect, and Google Scholar using the following keywords: exhaled breath condensate (EBC), biomarkers, pH, asthma, gastroesophageal reflux (GERD), smoking, COPD, lung cancer, NSCLC, mechanical ventilation, cystic fibrosis, pulmonary arterial hypertension (PAH), idiopathic pulmonary fibrosis, interstitial lung diseases, obstructive sleep apnea (OSA), and drugs. Results. We found 12600 related articles in total in Google Scholar, 1807 in ScienceDirect, and 1081 in PubMed/Medline, published from 1980 to October 2014. 228 original investigation and review articles were eligible. Conclusions. There is rapidly increasing number of innovative articles, covering all the areas of modern respiratory medicine and expanding EBC potential clinical applications to other fields of internal medicine. However, the majority of published papers represent the results of small-scale studies and thus current knowledge must be further evaluated in large cohorts. In regard to the potential clinical use of EBC-analysis, several limitations must be pointed out, including poor reproducibility of biomarkers and absence of large surveys towards determination of reference-normal values. In conclusion, contemporary EBC-analysis is an intriguing achievement, but still in early stage when it comes to its application in clinical practice.

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.

Exhaled breath condensate pH does not discriminate asymptomatic gastroesophageal reflux or the response to lansoprazole treatment in children with poorly controlled asthma

BACKGROUND

Although exhaled breath condensate (EBC) pH has been identified as an "emerging" biomarker of interest for asthma clinical trials, the clinical determinants of EBC pH remain poorly understood. Other studies have associated acid reflux-induced respiratory symptoms, for example, cough, with transient acidification of EBC.

OBJECTIVE

We sought to determine the clinical and physiologic correlates of EBC acidification in a highly characterized sample of children with poorly controlled asthma. We hypothesized that (1) children with asymptomatic gastroesophageal reflux determined by 24-hour esophageal pH monitoring would have a lower EBC pH than children without gastroesophageal reflux, (2) treatment with lansoprazole would alter EBC pH in those children, and (3) EBC acidification would be associated with increased asthma symptoms, poorer asthma control and quality of life, and increased formation of breath nitrogen oxides (NOx).

METHODS

A total of 110 children, age range 6 to 17 years, with poor asthma control and esophageal pH data enrolled in the Study of Acid Reflux in Children with Asthma (NCT00442013) were included. Children submitted EBC samples for pH and NOx measurement at randomization and at study weeks 8, 16, and 24.

RESULTS

Serial EBC pH measurements failed to distinguish asymptomatic gastroesophageal reflux and was not associated with breath NOx formation. EBC pH also did not discriminate asthma characteristics such as medication and health care utilization, pulmonary function, and asthma control and quality of life both at baseline and across the study period.

CONCLUSION

Despite the relative ease of EBC collection, EBC pH as a biomarker does not provide useful information of children with asthma who were enrolled in asthma clinical trials.

Exhaled matrix metalloproteinase-9 (MMP-9) in different biological phenotypes of asthma

BACKGROUND AND OBJECTIVES

Airway remodeling is a main feature of asthma. Different biological phenotypes of severe asthma have been recently recognized by the ENFUMOSA study group and among these one is characterized by neutrophilic airway inflammation. Concentrations of MMP-9 in airways have been suggested as a marker to monitor airway remodeling in asthma.

OBJECTIVE

The aim of the present study was to explore airway remodeling in different biological phenotypes of asthma by measuring MMP-9 in EBC and correlating these with other variables.

METHODS

Sixty consecutive subjects with asthma and 20 healthy controls were enrolled in the study. Exhaled MMP-9, pH and NO levels and inflammatory cells in sputum were measured in all subjects enrolled.

RESULTS

We observed an increase of exhaled MMP-9 in asthmatic subjects compared to controls. Higher exhaled MMP-9 concentrations were described in severe asthmatics compared to mild to moderate especially in those with neutrophilic airway inflammation. We further found a correlation between exhaled MMP-9 and percentage of neutrophils in sputum, FEV1, exhaled NO and pH.

CONCLUSION

Our results seem to substantiate the feasibility of measuring exhaled MMP-9 in the breath of asthmatic patients. MMP-9 may be considered a proxy of the amount of the ongoing airway remodeling in asthma. MMP-9 has been shown to be differentially released in different phenotypes of asthma. The measure of exhaled MMP-9 could help to monitor the ongoing airway remodeling, recognize severe stages of asthma, and possibly help determine the appropriate choice of therapy.

Exhaled breath condensate--from an analytical point of view

Over the past three decades, the goal of many researchers is analysis of exhaled breath condensate (EBC) as noninvasively obtained sample. A total quality in laboratory diagnostic processes in EBC analysis was investigated: pre-analytical (formation, collection, storage of EBC), analytical (sensitivity of applied methods, standardization) and post-analytical (interpretation of results) phases. EBC analysis is still used as a research tool. Limitations referred to pre-analytical, analytical, and post-analytical phases of EBC analysis are numerous, e.g. low concentrations of EBC constituents, single-analyte methods lack in sensitivity, and multi-analyte has not been fully explored, and reference values are not established. When all, pre-analytical, analytical and post-analytical requirements are met, EBC biomarkers as well as biomarker patterns can be selected and EBC analysis can hopefully be used in clinical practice, in both, the diagnosis and in the longitudinal follow-up of patients, resulting in better outcome of disease.

Airway gas exchange and exhaled biomarkers

During inspiration and expiration, gases traverse the conducting airways as they are transported between the environment and the alveolar region of the lungs. The term "conducting" airways is used broadly as the airway tree is thought largely to provide a conduit for the respiratory gases, oxygen and carbon dioxide. However, despite a significantly smaller surface area, and thicker barrier separating the gas phase from the blood when compared to the alveolar region, the airway tree can participate in gas exchange under special conditions such as high water solubility, high chemical reactivity, or production of the gas within the airway wall tissue. While these conditions do not apply to the respiratory gases, other gases demonstrate substantial exchange of the airways and are of particular importance to the inflammatory response of the lungs, the medical-legal field, occupational health, metabolic disorders, or protection of the delicate alveolar membrane. Given the significant structural differences between the airways and the alveolar region, the physical determinants that control airway gas exchange are unique and require different models (both experimental and mathematical) to explore. Our improved physiological understanding of airway gas exchange combined with improved analytical methods to detect trace compounds in the exhaled breath provides future opportunities to develop new exhaled biomarkers that are characteristic of pulmonary and systemic conditions.

Recent advances in asthma biomarker research

Asthma is characterized by recurrent and reversible airflow obstruction, which is routinely monitored by history and physical examination, spirometry and home peak flow diaries. As airway inflammation is central to asthma pathogenesis, its monitoring should be part of patient management plans. Fractional exhaled nitric oxide level (FeNO) is the most extensively studied biomarker of airway inflammation, and FeNO references were higher in Chinese (Asians) than Whites. Published evidence was inconclusive as to whether FeNO is a useful management strategy for asthma. Other biomarkers include direct (histamine, methacholine) and indirect (adenosine, hypertonic saline) challenges of bronchial hyperresponsiveness (BHR), induced sputum and exhaled breath condensate (EBC). A management strategy that normalized sputum eosinophils among adult patients resulted in reductions of BHR and asthma exacerbations. However, subsequent adult and pediatric studies failed to replicate these benefits. Asthma phenotypes as defined by inflammatory cell populations in sputum were also not stable over a 12-month period. A recent meta-analysis concluded that induced sputum is not accurate enough to be applied in routine monitoring of childhood asthma. There is poor correlation between biomarkers that reflect different asthma dimensions: spirometry (airway caliber), BHR (airway reactivity) and FeNO or induced sputum (airway inflammation). Lastly, EBC is easily obtained noninvasively by cooling expired air. Many biomarkers ranging from acidity (pH), leukotrienes, aldehydes, cytokines to growth factors have been described. However, significant overlap between groups and technical difficulty in measuring low levels of inflammatory molecules are the major obstacles for EBC research. Metabolomics is an emerging analytical method for EBC biomarkers. In conclusion, both FeNO and induced sputum are useful asthma biomarkers. However, they will only form part of the clinical picture. Longitudinal studies with focused hypotheses and well-designed protocols are needed to establish the roles of these biomarkers in asthma management. The measurement of biomarkers in EBC remains a research tool.

Exhaled matrix metalloproteinase-9 in lung cancer

BACKGROUND

Matrix metalloproteinase-9 (MMP-9) has been recognized in several types of tumor development and progression, including lung cancer, for its role in the degradation and remodeling of lung tissue. Furthermore, increased MMP-9 has been commonly described in the serum and airways of non-small cell lung cancer (NSCLC) patients.

OBJECTIVE

The aim of this study was to investigate, for the first time, MMP-9 in the exhaled breath condensate (EBC) of NSCLC patients.

PARTICIPANTS

We enrolled 40 NSCLC patients and 40 controls affected by transudative pleural effusion.

MEASUREMENTS

MMP-9 concentrations were measured in the EBC, whole blood (WB), and pleural effusion (PE) of all the subjects under study using enzyme immunoassay (EIA) kits.

RESULTS

MMP-9 levels were found to be significantly higher in EBC, WB, and PE of NSCLC patients compared with controls. A positive correlation was observed between MMP-9 in EBC, cigarettes smoked, and stage of cancer.

CONCLUSION

Exhaled MMP-9 was elevated in NSCLC patients, especially during tumor progression, and could represent a suitable noninvasive marker in the diagnosis and monitoring of lung cancer.

Aging and airway inflammation

BACKGROUND

Since little is known of airways inflammation in the elderly, we have carried out a study to explore the presence of some inflammatory markers in the airways of healthy subjects of different ages using a non-invasive method which is particularly suitable for aged people.

OBJECTIVE

The aim of this work was to investigate whether parameters, including (1) pH, IL-8 and TNF-α in exhaled breath condensate (EBC), (2) exhaled nitric oxide levels (NO), and (3) inflammatory cell profile in induced sputum, are age-related.

MATERIALS AND METHODS

Thirty healthy adults (10 subjects below the age of 30 [A], 10 subjects between 30 and 60 years [B], and 10 subjects over 60 years of age [C]), were enrolled in the study. IL-8 and TNF-α levels were measured in breath condensate. Exhaled pH was measured after deaeration/decarbonation by means of a pH-meter. A rapid-response chemiluminescence NO analyzer was used to quantify NO. Induced sputum was collected, homogenized with dithiothreitol, and cytospins for differential cell were produced.

RESULTS

The levels of IL-8 and TNF-α in EBC, the levels of exhaled NO, and the percentage of neutrophils in induced sputum were significantly elevated in C and B compared with A; the EBC pH level was significantly reduced in C and B compared with A. The EBC levels of IL-8, TNF-α, pH, the level of exhaled NO, and the percentage of neutrophils correlated significantly with age.

CONCLUSION

This study has shown the presence of age-related airways inflammation in healthy subjects.

Novel end points for clinical trials in young children with cystic fibrosis

Cystic fibrosis (CF) lung disease commences early in the disease progression and is the most common cause of mortality. While new CF disease-modifying agents are currently undergoing clinical trial evaluation, the implementation of such trials in young children is limited by the lack of age-appropriate clinical trial end points. Advances in infant and preschool lung function testing, imaging of the chest and the development of biochemical biomarkers have led to increased possibility of quantifying mild lung disease in young children with CF and objectively monitoring disease progression over the course of an intervention. Despite this, further standardization and development of these techniques is required to provide robust objective measures for clinical trials in this age group.

Airway inflammation in cystic fibrosis: molecular mechanisms and clinical implications

Airway epithelial cells and immune cells participate in the inflammatory process responsible for much of the pathology found in the lung of patients with cystic fibrosis (CF). Intense bronchial neutrophilic inflammation and release of proteases and oxygen radicals perpetuate the vicious cycle and progressively damage the airways. In vitro studies suggest that CF transmembrane conductance regulator (CFTR)-deficient airway epithelial cells display signalling abnormalities and aberrant intracellular processes which lead to transcription of inflammatory mediators. Several transcription factors, especially nuclear factor-κB, are activated. In addition, the accumulation of abnormally processed CFTR in the endoplasmic reticulum results in unfolded protein responses that trigger 'cell stress' and apoptosis leading to dysregulation of the epithelial cells and innate immune function in the lung, resulting in exaggerated and ineffective airway inflammation. Measuring airway inflammation is crucial for initiating treatment and monitoring its effect. No inflammatory biomarker predictive for the clinical course of CF lung disease is currently known, although neutrophil elastase seems to correlate with lung function decline. CF animal models mimicking human lung disease may provide an important insight into the pathogenesis of lung inflammation in CF and identify new therapeutic targets.

Exhaled breath condensate in pediatric asthma: promising new advance or pouring cold water on a lot of hot air? a systematic review

BACKGROUND

Exhaled breath condensate (EBC) analysis is a simple non-invasive technique that allows repeated collection of breath samples with a minimum of inconvenience for the subject. These breath samples can potentially indicate lung disease activity and given the ease of collection, EBC is becoming a useful research tool in the study of respiratory diseases. It has the potential to be used in both population-based studies and in the context of pediatric asthma it may prove useful in diagnosis and monitoring.

METHODS

A systematic review was conducted to identify studies of EBC markers in childhood asthma.

RESULTS

Most of the studies were cross-sectional in design, and the results suggest that simple chemical entities such as hydrogen ions (as pH), hydrogen peroxide, and oxides of nitrogen are associated with pediatric allergic asthma and exacerbations. In addition, more complex molecules including leukotrienes, prostaglandins, and cytokines such as the interleukins IL-4 and IL-5 are also elevated in the breath of those with asthma.

CONCLUSION

EBC has the potential to aid diagnosis, and to evaluate the inflammatory status of asthmatic children. Future studies may be able to refine further how best to collect EBC samples, to interpret them, and the technique has the potential to allow repeated sampling which will allow studies of natural history, pathogenesis and response to treatment to be undertaken.

The role of exhaled nitric oxide and exhaled breath condensates in evaluating airway inflammation in asthma

BACKGROUND

Airway inflammation is central to the development and progression of asthma. Monitoring airway inflammation can be invasive and technically difficult, making its use limited in clinical practice. Several advances have been made in non-invasive techniques to monitor and measure inflammation from the airways.

OBJECTIVE

To examine the suitability of exhaled nitric oxide and exhaled breath condensates as diagnostic tools in asthma.

METHOD

The current literature regarding the use of exhaled nitric oxide and exhaled breath condensate to assess and manage asthma was reviewed.

CONCLUSION

Exhaled nitric oxide is a clinically useful marker of eosinophilic airway inflammation in asthma. Although showing promise, significant validation and investigation are required before exhaled breath condensate could be utilized in clinical practice.

Safety of an alkalinizing buffer designed for inhaled medications in humans

BACKGROUND

Airway acidification plays a role in disorders of the pulmonary tract. We hypothesized that the inhalation of alkalinized glycine buffer would measurably alkalinize the airways without compromising lung function or causing adverse events. We evaluated the safety of an inhaled alkaline glycine buffer in both healthy subjects and in subjects with stable obstructive airway disease.

METHODS

This work includes 2 open-label safety studies. The healthy controls were part of a phase 1 safety study of multiple inhalations of low-dose alkaline glycine buffer; nebulized saline was used as a comparator in 8 of the healthy controls. Subsequently, a phase 2 study in subjects with stable obstructive airway disease was completed using a single nebulized higher-dose strategy of the alkaline inhalation. We studied 20 non-smoking adults (10 healthy controls and 10 subjects with obstructive airway disease), both at baseline and after inhalation of alkaline buffer. We used spirometry and vital signs as markers of clinical safety. We used changes in fraction of exhaled nitric oxide (NO) and exhaled breath condensate (EBC) pH as surrogate markers of airway pH modification.

RESULTS

Alkaline glycine inhalation was tolerated by all subjects in both studies, with no adverse effects on spirometric parameters or vital signs. Airway alkalinization was confirmed by a median increase in EBC pH of 0.235 pH units (IQR 0.56-0.03, P = .03) in subjects after inhalation of the higher-dose alkaline buffer (2.5 mL of 100 mmol/L glycine).

CONCLUSIONS

Alkalinization of airway lining fluid is accomplished with inhalation of alkaline glycine buffer and causes no adverse effects on pulmonary function or vital signs.

Prediction of asthma exacerbations in children: results of a one-year prospective study

BACKGROUND

Underdiagnosis and low levels of asthma control are frequent occurring problems in patients with asthma.

OBJECTIVE

The study aim was to evaluate the ability of non-invasive inflammatory markers in exhaled breath to predict exacerbations of childhood asthma, and to assess the time course of changes in these exhaled markers before, during and after exacerbations.

METHODS

The design was a prospective one-year longitudinal study. Regular two-month visits at the outpatient clinic were performed. Forty children with asthma (aged 6-16 years) participated. The primary outcome measure was the occurrence of an exacerbation. Assessment was made of the presence and severity of pulmonary symptoms, use of medication, and measurements of forced expiratory volume in 1 s using home monitor. The following independent parameters were assessed during outpatient visits: (1) exhaled nitric oxide, (2) inflammatory markers in exhaled breath condensate: acidity, nitrite, hydrogen peroxide, interleukin-1α, -5, -13, interferon-γ, (3) lung function, (4) asthma control score.

RESULTS

Thirty-eight of 40 children completed the study. Sixteen children developed exacerbations, of which ten were moderate and six severe. Univariate Cox regression analysis revealed that condensate acidity, interleukin-5 and asthma control score were significant predictors of an asthma exacerbation (P < 0.05). In the multivariate Cox regression analysis, exacerbations were best predicted by the asthma control score and by the level of interleukin-5 in exhaled breath condensate (Wald scores of 7.19 and 4.44, P = 0.007 and P = 0.035 respectively). The predicted survival curve of this multivariate model showed a two times reduced risk on exacerbations in the category of children with the 10% most optimal values of IL-5 and asthma control score.

CONCLUSIONS AND CLINICAL RELEVANCE

Both exhaled breath condensate interleukin-5 level and asthma control score were significant predictors of asthma exacerbations. These findings open up the possibility of assessing the potential of such parameters to titrate asthma treatment in future studies.

Exhaled breath condensate pH in patients with cystic fibrosis

OBJECTIVE AND DESIGN

Exhaled breath condensate (EBC) pH has been proposed as a useful, non-invasive marker of airway inflammation in pulmonary diseases. In this study we tested whether cystic fibrosis (CF) is associated with acidification of EBC, when pH is assessed by the CO(2) gas standardization method.

METHODS

EBC was collected using two different devices (EcoScreen and R-Tube) in 46 stable CF patients during routine clinical visits and in 28 healthy controls.

RESULTS

Mean EBC pH in CF patients and in healthy controls was similar (EcoScreen: CF patients: 6.38 ± 0.03 versus controls: 6.39 ± 0.03, p = 0.699; R-tube: CF patients: 5.94 ± 0.04 versus controls: 6.02 ± 0.03, p = 0.159). Inflammatory cell counts in spontaneously expectorated sputum obtained in a subset of patients (n = 20) showed no correlation with pH values. EBC samples collected with the R-tube were more acidic than those collected with the EcoScreen device (p < 0.001).

CONCLUSIONS

Our data suggest that EBC pH does not discriminate between healthy controls and those with CF disease indicating that the clinical applicability of EBC pH measurements for assessing airway inflammation in CF is limited.

Reflux aspiration in children with neurodisability--a significant problem, but can we measure it?

Recurrent respiratory problems are common in children with severe neurodisability, and respiratory deterioration is a leading cause of premature death in this group. Although the etiology is multifactorial, recurrent pulmonary aspiration is thought to play a significant role. Gastroesophageal reflux is known to be common, as is oral-motor discoordination. Differentiating direct aspiration of food and saliva and gastric reflux aspiration is difficult and presents a challenge in managing patients and assessing their suitability for surgical antireflux procedures. This is particularly the case when children present with predominantly respiratory symptoms, where there may be direct aspiration, reflux aspiration, neither, or both. A clinical biomarker to identify and quantify reflux aspiration would therefore be useful in surgical assessment and may also be applicable as an outcome measure for clinical trials of antireflux surgery. In this review, we discuss the evidence base behind existing and potentially novel biomarkers of aspiration in bronchoalveolar lavage fluid. We highlight the limitations of the lipid-laden macrophage index, particularly with regard to its specificity and interrater/intrarater reliability. We discuss the laboratory methods available to measure promising new biomarkers (pepsin and bile acids) and highlight their potential advantages and disadvantages. Finally, to understand how aspiration causes clinical signs and symptoms in our patients, we need to study the effect of aspirated substances on the lung, and here we review the available in vivo and in vitro literature.

Comparison of two devices and two breathing patterns for exhaled breath condensate sampling

Introduction

Analysis of exhaled breath condensate (EBC) is a noninvasive method to access the epithelial lining fluid of the lungs. Due to standardization problems the method has not entered clinical practice. The aim of the study was to assess the comparability for two commercially available devices in healthy controls. In addition, we assessed different breathing patterns in healthy controls with protein markers to analyze the source of the EBC.

Methods

EBC was collected from ten subjects using the RTube and ECoScreen Turbo in a randomized crossover design, twice with every device - once in tidal breathing and once in hyperventilation. EBC conductivity, pH, surfactant protein A, Clara cell secretory protein and total protein were assessed. Bland-Altman plots were constructed to display the influence of different devices or breathing patterns and the intra-class correlation coefficient (ICC) was calculated. The volatile organic compound profile was measured using the electronic nose Cyranose 320. For the analysis of these data, the linear discriminant analysis, the Mahalanobis distances and the cross-validation values (CVV) were calculated.

Results

Neither the device nor the breathing pattern significantly altered EBC pH or conductivity. ICCs ranged from 0.61 to 0.92 demonstrating moderate to very good agreement. Protein measurements were greatly influenced by breathing pattern, the device used, and the way in which the results were reported. The electronic nose could distinguish between different breathing patterns and devices, resulting in Mahalanobis distances greater than 2 and CVVs ranging from 64% to 87%.

Conclusion

EBC pH and (to a lesser extent) EBC conductivity are stable parameters that are not influenced by either the device or the breathing patterns. Protein measurements remain uncertain due to problems of standardization. We conclude that the influence of the breathing maneuver translates into the necessity to keep the volume of ventilated air constant in further studies.

Calcium and magnesium in exhaled breath condensate of children with endogenous and exogenous airway acidification

BACKGROUND AND AIMS

Regulation of pH in the airways is of physiological importance. As acidification of the airways causes bronchoconstriction, the aim of the present study was to find out whether there is any difference in calcium and magnesium in exhaled breath condensate (EBC) of children with uncontrolled asthma (i.e., with endogenous acidification) and children with gastroesophageal reflux disease, GERD (i.e., with exogenous acidification).

MATERIAL AND METHODS

A total of 142 children were included in the study: children with uncontrolled asthma (N = 51), children with GERD (N = 61), and healthy controls (N = 30). In addition, according to the pH cut-off value children with asthma and GERD were divided into two subgroups, that is, patients with pH ≤ 6.93 (subgroup A) and patients with pH > 6.93 (subgroup B).

RESULTS

The mean EBC pH was significantly lower in children with asthma than in children with GERD (6.791 ± 0.374 vs. 7.002 ± 0.361, p = .006). Concentration [median and interquartile range-M (IQR)] of total magnesium, but not calcium, was lower in both asthmatic [(10 (10-40) μmol/L, p = .016)] and GERD children [(20 (10-40) μmol/L, p = .012)] in comparison with controls (47 ± 27 μmol/L). There was no statistically significant difference in EBC calcium and magnesium concentrations between asthmatic and GERD children. In asthmatic children a positive correlation was confirmed between forced expiratory volume in the first second (FEV1) and magnesium in EBC (r = 0.307; p = .030), and negative correlation was found between FEV1 and calcium/magnesium ratio (r = -0.290; p = .047). In addition, positive correlation was confirmed between fractional concentration of exhaled NO and calcium/magnesium ratio (r = 0.360; p = .018). In GERD patients a negative correlation (r = -0.404; p = .003) was found between magnesium and pH values. Concentration of calcium was higher in the GERD subgroup A children [(50 (30-90) μmol/L)] than in the subgroup B children [(30 (20-45) μmol/L, p = .031)]. In addition, concentration of magnesium was higher in the GERD subgroup A children [(30 (20-70) μmol/L)] than in the subgroup B children [(10 (10-20) μmol/L, p < .001)].

CONCLUSION

The present study indicates that decreased total magnesium concentration may be found in EBCs, irrespective of whether the acidification is the result of endogenous pathomechanisms or reflux-induced mechanisms. In children with GERD, EBC pH-metry should be performed after acute coughing episode. Future research is needed to investigate the mechanisms of onset and dynamics of these changes.

SCIENTIFIC SIGNIFICANCE

Lower concentration of magnesium may indicate its role in bronchoconstiction.

Neutrophilic airways inflammation in lung cancer: the role of exhaled LTB-4 and IL-8

BACKGROUND

Recent advances in lung cancer biology presuppose its inflammatory origin. In this regard, LTB-4 and IL-8 are recognized to play a crucial role in neutrophil recruitment into airways during lung cancer.Notwithstanding the intriguing hypothesis, the exact role of neutrophilic inflammation in tumour biology remains complex and not completely known.The aim of this study was to give our contribution in this field by investigating LTB-4 and IL-8 in the breath condensate of NSCLC patients and verifying their role in cancer development and progression.

METHOD

We enrolled 50 NSCLC patients and 35 controls. LTB-4 and IL-8 concentrations were measured in the breath condensate and the blood of all the subjects under study using EIA kits. Thirty NSCLC patients and ten controls underwent induced sputum collection and analysis.

RESULTS

LTB-4 and IL-8 resulted higher in breath condensate and the blood of NSCLC patients compared to controls. Significantly higher concentrations were found as the cancer stages progressed. A positive correlation was observed between exhaled IL-8 and LTB-4 and the percentage of neutrophils in the induced sputum.

CONCLUSION

The high concentrations of exhaled LTB-4 and IL-8 showed the presence of a neutrophilic inflammation in the airways of NSCLC patients and gave a further support to the inflammatory signalling in lung cancer. These exhaled proteins could represent a suitable non-invasive marker in the diagnosis and monitoring of lung cancer.

Exhaled breath condensate pH in lung transplant recipients with bronchiolitis obliterans syndrome

BACKGROUND

Assessment of exhaled breath condensate (EBC) pH is a promising method for investigating airway pathology. However, inaccurate measurement techniques may bias pH readings. In this longitudinal study, we tested whether development of bronchiolitis obliterans syndrome (BOS) in lung transplant recipients is associated with acidification of EBC.

METHODS

EBC was collected in 15 patients with BOS and 16 stable BOS-free patients during routine clinical visits. From nine BOS patients, samples were collected before and after the onset of BOS, as well. Twenty healthy nontransplant subjects served as controls. EBC pH was measured by the carbon dioxide gas standardization method.

RESULTS

EBC pH in patients with and without BOS and controls was similar (BOS group: 6.40±0.04, BOS-free group: 6.45±0.03; controls: 6.39±0.02; P>0.05). In patients who developed BOS during the follow-up, EBC pH before and after the onset of BOS was comparable (pre-BOS: 6.41±0.04 vs. post-BOS: 6.41±0.04; P>0.05). Coefficient of variation for repeated pH measurements in controls and subjects with and without BOS was 2.3%±0.3%, 2.0%±0.3%, and 1.7%±0.2%, respectively (P>0.05). Similarly, the limits of agreement for between-visit variability determined by the Bland-Altman test were comparable among the study groups.

CONCLUSIONS

These data suggest that assessment of EBC pH is of limited value for the diagnosis of BOS.

Evaluation of exhaled breath condensate pH as a biomarker for COPD

INTRODUCTION

We assessed the utility of EBC pH as a biomarker in COPD in a large cohort of well-characterised individuals with COPD and control subjects from the Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) study. We also determined short term reproducibility and the response of EBC to oral prednisolone.

METHODS

EBC was collected with R-Tubes(TM), using techniques for sampling and measurement that have been shown to be reproducible.

RESULTS

EBC pH was lower in COPD (n = 676, 7.29 ± SD 0.60) and in smoking controls (n = 31, 7.18 ± 0.85), compared with non-smoking controls (n = 50, 7.59 ± 0.44, p = 0.0008 and 0.0033 respectively), but was not different between COPD and smoking controls. There was no relationship between EBC pH and disease severity, as assessed by the percent predicted FEV(1), nor with airway inflammation as assessed by sputum leukocyte counts. Treatment with 20 mg.day-1 prednisolone for 4 weeks did not change EBC pH.

CONCLUSION

EBC pH is lower in COPD than in healthy control non-smokers, but does not differentiate COPD from smokers without COPD, relate to disease severity or to airway inflammation, and does not respond to corticosteroids. EBC pH therefore does not appear to be a useful biomarker in COPD.

Exhaled breath condensates in asthma: diagnostic and therapeutic implications

Exhaled breath condensate (EBC) collection and analysis offers a unique non-invasive method to sample the airway lining fluid. It enables classification and quantification of airway inflammation associated with various pulmonary diseases such as asthma. Over the last decade, innumerable efforts have been made to identify biomarkers in EBC for diagnosis and management of asthma. The aim of this review is to consolidate information available to date, summarize findings from studies and identify potential biomarkers which need further refinement through translational research prior to application in clinical practice.

Dyspnea perception in asthma: role of airways inflammation, age and emotional status

OBJECTIVES

Dyspnea perception in asthmatics differs between subjects. Poor perception is usually associated with increased risk of asthma attack/exacerbation. The advanced stage of the disease and the presence of eosinophilic airways inflammation have been recently recognized as being responsible for poor dyspnea perception. However, few studies are available on this topic.

DESIGN

The aim of this study was to analyse the influence of inflammatory pattern, age and affective status on dyspnea perception in asthmatic subjects.

SUBJECTS AND INTERVENTIONS

Seventy-one consecutive asthmatic patients were recruited and underwent induced sputum, exhaled NO measurement and breath condensate collection. Perception of dyspnea was evaluated as a BORG-VAS/FEV(1) slope before and after the broncho-reversibility test and correlated with the stage of asthma, inflammatory markers, age and depression scale.

RESULTS

Dyspnea perception decreases with the worsening of asthma, with the advance of age and of depression status. Furthermore, airways inflammation plays a key role in the decline of dyspnea perception as proved by the negative correlation observed between inflammatory cells in sputum, exhaled pH and NO and BORG-VAS/FEV(1) slope.

CONCLUSIONS

The results of our study suggested that airways inflammation, depression status, advance age and severity of asthma influence dyspnea perception and suggest a straight control to identify and better manage poor preceptor asthmatics.

Menopausal asthma: a new biological phenotype?

BACKGROUND

Female hormones play an important role in women's lung health, especially in asthma pathophysiology. Although a growing interest has recently been aroused in asthma related to short-term reproductive states, menopausal asthma has been little studied in the past. The aim of the present study was to explore airway inflammation in menopausal asthmatic women in a noninvasive manner.

METHODS

Forty consecutive women with menopausal asthma, 35 consecutive women with premenopausal asthma and 30 age-matched healthy controls were enrolled in the study. Urinary LTE-4, induced sputum inflammatory cells, and exhaled LTE-4, IL-6, pH, and NO levels were measured in all the subjects enrolled.

RESULTS

Women with menopausal asthma showed decreased estradiol concentrations, high sputum neutrophils, and exhaled IL-6. Women with premenopausal asthma presented instead an essentially eosinophilic inflammatory pattern. Higher urine and breath condensate LTE-4 concentrations were found in premenopausal and menopausal asthma compared to controls.

CONCLUSION

Our results substantiate the existence of a new biological phenotype of menopausal asthma that is mainly characterized by neutrophilic airways inflammation and shares several characteristics of the severe asthma phenotype.

Potential of anti-inflammatory treatment for cystic fibrosis lung disease

Cystic fibrosis (CF) is the most common life-shortening genetic disorder in Caucasians. With improved diagnosis and treatment, survival has steadily increased. Unfortunately, the overwhelming majority of patients still die from respiratory failure caused by structural damage resulting from airway obstruction, recurrent infection, and inflammation. Here, we discuss the role of inflammation and the development of anti-inflammatory therapies to treat CF lung disease. The inflammatory host response is the least addressed component of CF airway disease at this time. Current challenges in both preclinical and clinical investigation make the identification of suitable anti-inflammatory drugs more difficult. Despite this, many researchers are making significant progress toward this goal and the CF research community has reason to believe that new therapies will emerge from these efforts.

Assessment of exhaled breath condensate pH in exacerbations of asthma and chronic obstructive pulmonary disease: A longitudinal study

RATIONALE

Exhaled breath condensate pH has been proposed as a noninvasive marker of airway inflammation. However, due to standardization difficulties in pH measurement techniques, different pH readings were obtained in previous studies.

OBJECTIVES

In this longitudinal study we assessed condensate pH in patients with an exacerbation of asthma or chronic obstructive airway disease using the very precise carbon dioxide standardization method that negates the effect of this gas on condensate acidity.

METHODS

Condensate pH, fractional exhaled nitric oxide, lung function, and blood gases were measured in 20 nonsmoking patients with asthma and 21 smoking and 17 ex-smoking patients with chronic obstructive airway disease first at hospital admission due to an acute exacerbation of the disease and again at discharge after treatment. Condensate pH was also assessed in 18 smoking and 18 nonsmoking healthy control subjects.

MEASUREMENTS AND MAIN RESULTS

In patients with asthma, condensate pH was significantly decreased at the time of exacerbation compared with nonsmoking control subjects and increased with treatment. In patients with chronic obstructive airway disease, condensate pH remained unchanged during exacerbation, both in smokers and ex-smokers. Nevertheless, condensates collected from smokers were more acidic than those of ex-smokers. A similar difference was observed between smoker and nonsmoker healthy control subjects. No correlations were found between condensate pH and fractional exhaled nitric oxide or lung function variables measured either at admission or discharge.

CONCLUSIONS

Our data suggest that exacerbation of asthma, but not chronic obstructive airway disease, is associated with acidification of breath condensate.

Biomarkers in asthma and allergic rhinitis

A biological marker (biomarker) is a physical sign or laboratory measurement that can serve as an indicator of biological or pathophysiological processes or as a response to a therapeutic intervention. An applicable biomarker possesses the characteristics of clinical relevance (sensitivity and specificity for the disease) and is responsive to treatment effects, in combination with simplicity, reliability and repeatability of the sampling technique. Presently, there are several biomarkers for asthma and allergic rhinitis that can be obtained by non-invasive or semi-invasive airway sampling methods meeting at least some of these criteria. In clinical practice, such biomarkers can provide complementary information to conventional disease markers, including clinical signs, spirometry and PC(20)methacholine or histamine. Consequently, biomarkers can aid to establish the diagnosis, in staging and monitoring of the disease activity/progression or in predicting or monitoring of a treatment response. Especially in (young) children, reliable, non-invasive biomarkers would be valuable. Apart from diagnostic purposes, biomarkers can also be used as (surrogate) markers to predict a (novel) drug's efficacy in target populations. Therefore, biomarkers are increasingly applied in early drug development. When implementing biomarkers in clinical practice or trials of asthma and allergic rhinitis, it is important to consider the heterogeneous nature of the inflammatory response which should direct the selection of adequate biomarkers. Some biomarker sampling techniques await further development and/or validation, and should therefore be applied as a "back up" of established biomarkers or methods. In addition, some biomarkers or sampling techniques are less suitable for (very young) children. Hence, on a case by case basis, a decision needs to be made what biomarker is adequate for the target population or purpose pursued. Future development of more sophisticated sampling methods and quantification techniques, such as--omics and biomedical imaging, will enable detection of adequate biomarkers for both clinical and research applications.

Effects of a short-term rehabilitation program on airway inflammation in children with cystic fibrosis

BACKGROUND

Respiratory therapy in cystic fibrosis (CF) consists of airway clearance, infection control, and reduction of airway inflammation. It is well recognized that physical activity as well as daily chest physiotherapy, enhance airway clearance. We investigated the effects of pulmonary rehabilitation, including physical activity and chest physiotherapy, on airway inflammation in children with CF.

METHODS

Eighteen children with stable CF (six females), aged 8.2-16.2 years, participating in a 3-week multidisciplinary inpatient rehabilitation program were recruited. Assessment at the beginning and the end of the program included clinical score, pulmonary function test, exhaled breath condensate (EBC) and sputum analysis. Sputum supernatant and EBC were analyzed for interleukin (IL)-1b, 6, 8, 10, 12, tumor necrosis factor-alpha (TNF-alpha) and LTB4.

RESULTS

Median (IQR) symptom scores decreased from 19 [23] to 16 [21], P = 0.005. Vital capacity and FVC increased significantly (P < 0.05). However no difference was found for the total sputum cells and sputum as well as EBC cytokines between the two visits. Significant correlations were found for sputum IL-1 (+), IL-6 (-), and IL-8 (+) to total sputum cell count and neutrophils and for IL-8 to TNF-alpha.

CONCLUSIONS

We have shown that a short-term inpatient rehabilitation for children with stable CF with intensive physical activity mainly improve subjective clinical symptoms and measures of lung function such as VC and FVC but does not influence airflow obstruction and airway inflammation as assessed by sputum and EBC analysis.

Lactobacillus reuteri modulates cytokines production in exhaled breath condensate of children with atopic dermatitis

We measured the concentration of interferon-gamma and interleukin-4 in the exhaled breath condensate of children with atopic and nonallergic dermatitis receiving a probiotic supplementation (Lactobacillus reuteri ATCC 55730) or placebo for 8 weeks. We demonstrated that the levels of these cytokines increased and decreased respectively only in atopic subjects receiving active treatment. Our data suggest that the oral administration of a specific probiotic strain in patients with atopic dermatitis can modulate in vivo the cytokine pattern at a different site from intestine.

Lung function testing in preschool-aged children with cystic fibrosis in the clinical setting

In cystic fibrosis (CF) lung function testing is a means of monitoring progression of lung disease. The preschool years have often been referred to as the "silent years" due to the previous lack suitable measures of lung function testing in this age group. This review outlines the various techniques of lung function testing in preschool children with CF in the clinical setting. This includes measures requiring tidal breathing including the forced oscillation technique, the interrupter technique, plethysmography, and multiple breath washout, as well as spirometry that requires respiratory maneuvers. We describe the feasibility and variability of different lung function methods used in preschoolers and report measurements made during tidal breathing have greater feasibility, although greater variability compared to spirometry. We also report associations with lung function and markers of CF lung disease. In the preschool age group measurements made during tidal breathing may be more appropriate in the clinic setting than those that require a higher degree of cooperation and specific respiratory maneuvers.maneuvers.

Structural lung changes, lung function, and non-invasive inflammatory markers in cystic fibrosis

Cystic fibrosis (CF) lung disease is characterized by chronic airway inflammation and recurrent infections, resulting in (ir)reversible structural lung changes and a progressive decline in lung function. The objective of this study was to investigate the relationship between non-invasive inflammatory markers (IM) in exhaled breath condensate (EBC), lung function indices and structural lung changes, visualized by high resolution computed tomography (HRCT) scans in CF. In 34 CF patients, lung function indices (forced expiratory volume in 1 s, forced vital capacity [FVC], residual volume, and total lung capacity [TLC]) and non-invasive IM (exhaled nitric oxide, and condensate acidity, nitrate, nitrite, 8-isoprostane, hydrogen peroxide, interferon-gamma) were assessed. HRCT scans were scored in a standardized and validated way, a composite score and component scores were calculated. In general, the correlations between non-invasive IM and structural lung changes, and between IM and lung function were low (correlation coefficients <0.40). Patients with positive sputum Pseudomonas cultures had higher EBC nitrite levels and higher parenchymal HRCT subscores than patients with Pseudomonas-negative cultures (p < 0.05). Multiple linear regression models demonstrated that FVC was significantly predicted by hydrogen peroxide in EBC, and the scores of bronchiectasis and mosaic perfusion (Pearson correlation coefficient R = 0.78, p < 0.001). TLC was significantly predicted by 8-isoprostane, nitrate, hydrogen peroxide in EBC, and the mucous plugging subscore (R = 0.92, p < 0.01). Static and dynamic lung function indices in this CF group were predicted by the combination of non-invasive IM in EBC and structural lung changes on HRCT imaging. Future longitudinal studies should reveal whether non-invasive monitoring of airway inflammation in CF adds to better follow-up of patients.

Exhaled breath condensate pH and ammonia in cystic fibrosis and response to treatment of acute pulmonary exacerbations

Exhaled breath condensate (EBC) pH reflects the acid-base homeostasis of the airway lining fluid and is up to 3 log order lower in various inflammatory lung diseases including asthma, COPD, bronchiectasis, and cystic fibrosis (CF) than in normal controls. The aim of this study was to confirm this finding in CF and determine if there was a significant change in EBC pH after treatment of an acute pulmonary exacerbation. Ten subjects with CF and a pulmonary exacerbation, and 10 healthy age-matched control subjects were studied. EBC was collected at the onset of an acute pulmonary exacerbation and after treatment with intravenous antibiotics (median duration: 14 days (interquartile range, IQR): 12-14) when the exacerbation was considered resolved. The median age for CF patients was 15.9 years (IQR: 13-18.8), compared to 18 years (IQR: 15-24.8) for the control group, P = 0.242. All CF subjects had severe lung disease, median FEV(1) = 41.5% of predicted (IQR: 30.8-46.5%). Median EBC pH in CF subjects at the onset of a pulmonary exacerbation was 6.61 (IQR: 6.17-7.91) compared to median EBC pH of 8.14 (IQR: 7.45-9.08) in the control group, P < 0.02. Median EBC pH after resolution of an exacerbation was 7.02 (IQR: 5.8-8.64), not significantly different (P = 0.667) than during the acute exacerbation. EBC pH decreased in five subjects, increased in three subjects and there was no change in two subjects. There was no correlation between EBC pH and FEV(1) either before or after intravenous antibiotics. EBC ammonia, an important buffer of ASL, was also measured and similarly found to be lower than in normal controls. EBC pH is lower in CF than age-matched controls, and did not change consistently in response to treatment of an acute pulmonary exacerbation.