Small airways function and molecular markers in exhaled air in mild asthma

The Role of Exhaled Breath Condensate in Chronic Inflammatory and Neoplastic Diseases of the Respiratory Tract

Asthma and chronic obstructive pulmonary disease (COPD) are among the most common chronic respiratory diseases. Chronic inflammation of the airways leads to an increased production of inflammatory markers by the effector cells of the respiratory tract and lung tissue. These biomarkers allow the assessment of physiological and pathological processes and responses to therapeutic interventions. Lung cancer, which is characterized by high mortality, is one of the most frequently diagnosed cancers worldwide. Current screening methods and tissue biopsies have limitations that highlight the need for rapid diagnosis, patient differentiation, and effective management and monitoring. One promising non-invasive diagnostic method for respiratory diseases is the assessment of exhaled breath condensate (EBC). EBC contains a mixture of volatile and non-volatile biomarkers such as cytokines, leukotrienes, oxidative stress markers, and molecular biomarkers, providing significant information about inflammatory and neoplastic states in the lungs. This article summarizes the research on the application and development of EBC assessment in diagnosing and monitoring respiratory diseases, focusing on asthma, COPD, and lung cancer. The process of collecting condensate, potential issues, and selected groups of markers for detailed disease assessment in the future are discussed. Further research may contribute to the development of more precise and personalized diagnostic and treatment methods.

The Challenges and Opportunities for TiO2 Nanostructures in Gas Sensing

Chemiresistive gas sensors based on metal oxides have been widely applied in industrial monitoring, medical diagnosis, environmental pollutant detection, and food safety. To further enhance the gas sensing performance, researchers have worked to modify the structure and function of the material so that it can adapt to different gas types and environmental conditions. Among the numerous gas-sensitive materials, n-type TiO2 semiconductors are a focus of attention for their high stability, excellent biosafety, controllable carrier concentration, and low manufacturing cost. This Perspective first introduces the sensing mechanism of TiO2 nanostructures and composite TiO2-based nanomaterials and then analyzes the relationship between their gas-sensitive properties and their structure and composition, focusing also on technical issues such as doping, heterojunctions, and functional applications. The applications and challenges of TiO2-based nanostructured gas sensors in food safety, medical diagnosis, environmental detection, and other fields are also summarized in detail. Finally, in the context of their practical application challenges, future development technologies and new sensing concepts are explored, providing new ideas and directions for the development of multifunctional intelligent gas sensors in various application fields.

Small airways in asthma: From inflammation and pathophysiology to treatment response

Small airways are characterized as those with an inner diameter less than 2 mm and constitute a major site of pathology and inflammation in asthma disease. It is estimated that small airways dysfunction may occur before the emergence of noticeable symptoms, spirometric abnormalities and imaging findings, thus characterizing them as "the quiet or silent zone" of the lungs. Despite their importance, measuring and quantifying small airways dysfunction presents a considerable challenge due to their inaccessibility in usual functional measurements, primarily due to their size and peripheral localization. Several pulmonary function tests have been proposed for the assessment of the small airways, including impulse oscillometry, nitrogen washout, body plethysmography, as well as imaging methods. Nevertheless, none of these methods has been established as the definitive "gold standard," thus, a combination of them should be used for an effective assessment of the small airways. Widely used asthma treatments seem to also affect several parameters of the small airways. Emerging biologic treatments show promising results in reducing small airways inflammation and remodelling, providing evidence for potential alterations in the disease's progression and outcomes. These novel therapies have implications not only in the clinical aspects of asthma but also in its inflammatory and functional aspects.

Quantitative analysis of lung function and airway remodeling using ventilation/perfusion single photon emission tomography/computed tomography and HRCT in patients with chronic obstructive pulmonary disease and asthma

OBJECTIVE

To investigate the role of V/P SPECT/CT and HRCT quantitative parameters in evaluating COPD and asthma disease severity, airway obstructivity-grade, ventilation and perfusion distribution patterns, airway remodeling, and lung parenchymal changes.

METHOD

Fifty-three subjects who underwent V/P SPECT/CT, HRCT, and pulmonary function tests (PFTs) were included. Preserved lung ventilation (PLVF), perfusion function (PLPF), airway obstructivity-grade (OG), proportion of anatomical volume, ventilation and perfusion contribution of each lobe, and V/P distribution patterns were evaluated using V/P SPECT/CT. The quantitative parameters of HRCT included CT bronchial and CT pulmonary function parameters. In addition, the correlation and difference of V/P SPECT/CT-, HRCT-, and PFT-related parameters were compared.

RESULTS

There was a statistically significant difference between severe asthma and severe-very severe COPD in CT bronchial parameters, like WA, LA and AA, in the lung segment airways (P < 0.05). CT bronchial parameters, like as WT and WA, were statistically significant (p < 0.05) among asthma patients. The EI of severe-very severe COPD was different from that of the disease severity groups in asthma patients (P < 0.05). The airway obstructivity-grade, PLVF and PLPF differed significantly among the severe-very severe COPD and mild-moderate asthma patients (P < 0.05). And the PLPF was statistically significant among the disease severity groups in asthma and COPD (P < 0.05). OG and PLVF, PLPF, and PFT parameters were significantly correlated, with the FEV1 correlation being the most significant (r = - 0.901, r = 0.915, and r = 0.836, respectively; P < 0.01). There was a strong negative correlation between OG and PLVF (r = - 0.945) and OG and PLPF (r = - 0.853) and a strong positive correlation between PLPF and PLVF (r = 0.872). In addition, OG, PLVF, and PLPF were moderately to strongly correlated with CT lung function parameters (r = - 0.673 to - 0.839; P < 0.01), while lowly to moderately correlated with most CT bronchial parameters (r = - 0.366 to - 0.663, P < 0.01). There were three different V/P distribution patterns, including matched, mismatched, and reverse mismatched patterns. Last, the CT volume overestimated the contribution in the upper lobes and underestimated the lower lobes' contribution to overall function.

CONCLUSIONS

Quantitative assessment of ventilation and perfusion abnormalities and the degree of pulmonary functional loss by V/P SPECT/CT shows promise as an objective measure to assess the severity of disease and lung function to guide localized treatments. There are differences between HRCT parameters and SPECT/CT parameters among the disease severity groups in asthma and COPD, which may enhance, to some extent, the understanding of complex physiological mechanisms in asthma and COPD.

[Small airway: from definition to treatment]

The small airway, present since the origins of humanity and described barely a century ago, has recently been discovered as the anatomical site where inflammation begins in some obstructive lung diseases, such as asthma and Chronic Obstructive Pulmonary Disease (COPD), per se. Small airway dysfuction was identified in up to 91% of asthmatic patients and in a large proportion of COPD patients. In subjects without pathology, small airway represent 98.8% (approximately 4500 ml) of the total lung volume, contributing only between 10-25% of the total lung resistance; however, in subjects with obstruction, it can represent up to 90% of the total resistance. Despite this, its morphological and functional characteristics allow its dysfunction to remain undetected by conventional diagnostic methods, such as spirometry. Hence the importance of this review, which offers an overview of the tools available to assess small airway dysfunction and the possible therapies that act in this silent zone.

Association between exposure to a mixture of benzene, toluene, ethylbenzene, xylene, and styrene (BTEXS) and small airways function: A cross-sectional study

BACKGROUND

Lung is one of the primary target organs of benzene, toluene, ethylbenzene, xylene, and styrene (BTEXS). Small airways dysfunction (SAD) might be a sensitive indicator of early chronic respiratory disease. Here, we explored the relationships between exposure to BTEXS and small airways function, and identified the priority control pollutants in BTEXS mixtures.

METHODS

635 petrochemical workers were recruited. Standard spirometry testing was conducted by physicians. The cumulative exposure dose (CED) of BTEXS for each worker was estimated. The peak expiratory flow (PEF), forced expiratory flow between 25 and 75% of forced vital capacity (FEF25∼75%), and the expiratory flow rate found at 25%, 50%, and 75% of the remaining exhaled vital capacity (MEF25%, MEF50%, and MEF75%) were measured. SAD was also evaluated based on measured parameters. The associations between exposure to BTEXS individuals or mixtures and small airways function were evaluated using generalized linear regression models (GLMs) and quantile g-computation models (qgcomp). Meanwhile, the weights of each homolog in the association were estimated.

RESULTS

The median CED of BTEXS are 9.624, 19.306, 24.479, 28.210, and 46.781 mg/m³·years, respectively. A unit increase in ln-transformed styrene CED was associated with a decrease in FEF25∼75% and MEF50% based on GLMs. One quartile increased in BTEXS mixtures (ln-transformed) was significantly associated with a 0.325-standard deviation (SD) [95% confidence interval (CI): -0.464, -0.185] decline in FEF25∼75%, a 0.529-SD (95%CI: -0.691, -0.366) decline in MEF25%, a 0.176-SD (95%CI: -0.335, -0.017) decline in MEF75%, and increase in the risk of abnormal of SAD [risk ratios (95%CI): 1.520 (95%CI: 1.143, 2.020)]. Benzene and styrene were the major chemicals in BTEXS for predicting the overall risk of SAD.

CONCLUSION

Our novel findings demonstrate the significant association between exposure to BTEXS mixture and small airways function decline and the potential roles of key homologs (benzene and styrene) in SAD.

Challenges in Quantifying 8-OHdG and 8-Isoprostane in Exhaled Breath Condensate

Exhaled breath condensate (EBC) has attracted substantial interest in the last few years, enabling the assessment of airway inflammation with a non-invasive method. Concentrations of 8-Hydroxydesoxyguanosine (8-OHdG) and 8-isoprostane in EBC have been suggested as candidate biomarkers for lung diseases associated with inflammation and oxidative stress. EBC is a diluted biological matrix and consequently, requires highly sensitive chemical analytic methods (picomolar range) for biomarker quantification. We developed a new liquid chromatography coupled to tandem mass spectrometry method to quantify 8-OHdG and 8-isoprostane in EBC simultaneously. We applied this novel biomarker method in EBC obtained from 10 healthy subjects, 7 asthmatic subjects, and 9 subjects with chronic obstructive pulmonary disease. Both biomarkers were below the limit of detection (LOD) despite the good sensitivity of the chemical analytical method (LOD = 0.5 pg/mL for 8-OHdG; 1 pg/mL for 8-isoprostane). This lack of detection might result from factors affecting EBC collections. These findings are in line with methodological concerns already raised regarding the reliability of EBC collection for quantification of 8-OHdG and 8-isoprostane. Precaution is therefore needed when comparing literature results without considering methodological issues relative to EBC collection and analysis. Loss of analyte during EBC collection procedures still needs to be resolved before using these oxidative stress biomarkers in EBC.

Small Airway Dysfunction in Cough Variant Asthma: Prevalence, Clinical, and Pathophysiological Features

Introduction: Small airway dysfunction (SAD) commonly presents in patients with classic asthma, which is associated with airway inflammation, disease severity, and asthma control. However, the prevalence of SAD, its relationship with cough severity and airway inflammation, and its development after antiasthmatic treatment in patients with cough variant asthma (CVA) need to be clarified. This study aimed to investigate the prevalence of SAD and its relationship with clinical and pathophysiological characteristics in patients with CVA and the change in small airway function after antiasthmatic treatment.

Methods: We retrospectively analyzed 120 corticosteroid-naïve patients with CVA who had finished a standard questionnaire and relevant tests in a specialist cough clinic, such as cough visual analog scale (VAS), differential cells in induced sputum, fractional exhaled nitric oxide (FeNO) measurement, spirometry, and airway hyper-responsiveness. Information of 1-year follow-up was recorded in a part of patients who received complete cough relief after 2 months of treatment. SAD was defined as any two parameters of maximal mid-expiratory flow (MMEF)% pred, forced expiratory flow at 50% of forced vital capacity (FEF50%) pred, and forced expiratory flow at 75% of forced vital capacity (FEF75%) pred measuring <65%.

Results: SAD occurred in 73 (60.8%) patients with CVA before treatment. The patients with SAD showed a significantly longer cough duration (24.0 vs. 6.0, p = 0.031), a higher proportion of women (78.1 vs. 59.6%, p = 0.029), older mean age (41.9 vs. 35.4, p = 0.005), and significantly lower forced expiratory volume in 1 s (FEV₁%) pred, FEV₁/FVC, MMEF% pred, FEF50% pred, FEF75% pred, PEF% pred, and PD20 (all p < 0.01) as compared with patients without SAD. There were no significant differences in cough VAS, sputum eosinophils count, FeNO, and TIgE level between patients with SAD and those without SAD. Among 105 patients who completed 2 months of antiasthmatic treatment and repeatedly experienced spirometry measurement, 57 (54.3%) patients still had SAD, despite a significant improvement in cough VAS, sputum eosinophils, FeNO, FEF50% pred, and PEF% pred (all p < 0.01). As compared with patients without SAD, patients with SAD showed no significant differences in the relapse rate (50.0 vs. 41.9%, p = 0.483) and wheeze development rate (10.4 vs. 0%, p = 0.063) during the follow-up.

Conclusions: Small airway dysfunction occurred in over half of patients with CVA and persisted after short-term antiasthmatic treatment, which showed distinctive clinical and pathophysiological features.

"Poor Effort" Does Not Account for Reduced Forced Vital Capacity in Asthmatic Children

Purpose: Poor forced vital capacity (FVC) effort has been considered to be the main reason for FVC reduction by the ATS/ERS guideline; however, this has rarely been mentioned in previous studies. The present study aims to determine whether reduced FVC in asthmatic children is correlated to poor FVC effort. Methods: A total of 209 asthmatic children within 5-13 years old were included and divided into reduced FVC ("restricted," n = 66) and typical obstruction group ("obstructed," n = 143). Forced expiratory flows before and after bronchodilation were recorded in asthmatic children. The differences in clinical characteristics, spirometric results, FVC effort, and bronchodilator response were compared between two groups. Exhalation time (ET) was divided into effective ET (ETe) and plateau ET (ETp) by the start point of exhalation plateau on the time-volume curve. FVC effort was assessed by ET, ETp, and back extrapolated volume (EV)/FVC (%). Results: Asthmatic children in the restricted group had significantly higher slow vital capacity (SVC)/FVC (%), higher EV/FVC (%), shorter ET, shorter ETe, and longer ETp, when compared with those with obstructed. In the obstructed group, ET (r = 0.201, P = 0.016) and ETe (r = 0.496, P < 0.001) positively correlated with FVC, and ETp (r = -0.224, P = 0.007) negatively correlated with FVC. In the restricted group, FVC positively correlated with ETe (r = 0.350, P = 0.004) but not ET and ETp. FVC z-score significantly correlated with total IgE (n = 51, r = -0.349, P = 0.012) and with FEF_25-75% z-score (n = 66, r = 0.531, P < 0.001) in the restricted group. The further logistic regression revealed that the risk of restricted increased by 1.12 (95% CI, 1.04-1.22, P = 0.005) with every 1% increase in %ΔFVC. In subjects with restricted and bronchodilation tests, %ΔFVC was significantly associated with FeNO (n = 29, r = 0.386, P = 0.039), FEF_25-75% z-score (n = 29, r = -0.472, P = 0.010), and SVC/FVC (%) (n = 19, r = 0.477, P = 0.039) but not with EV/FVC (%), ET, ETe, or ETp (P > 0.05). Conclusion: These findings suggested that "poor FVC effort" does not account for the FVC reduction in asthmatic children. Short ET and high SVC/FVC (%) are characteristics of reduced FVC.

Correlation between fractional exhaled nitric oxide and Asthma Control Test score and spirometry parameters in on-treatment-asthmatics in Ho Chi Minh City

Background

Although fractional exhaled nitric oxide (FeNO) is a reliable and easily applied marker of airway inflammation in asthma, the relationship between FeNO and indicators of asthma control [Asthma Control Test (ACT) score] and/or severity (spirometry parameters) remains unclear. This study aims to determine possible correlations between FeNO and ACT score; and between FeNO and spirometry parameters.

Methods

A cross-sectional study with convenience sampling was conducted among ambulatory patients in the Asthma & COPD clinic at the University Medical Center, Ho Chi Minh City from March 2016 to March 2017. Using measurement of FeNO, the ACT questionnaire and a spirometry test, correlations were determined between FeNO and the ACT score and spirometry parameters.

Results

Four hundred and ten asthmatic patients (mean age 42 years; 65% female) were included and analyzed; their mean time since onset of asthma was 9.5 years. All patients were treated following step 2 to 4 of GINA guidelines. Mean (SD) FeNO was 29.5 (24.4) parts per billion (ppb) and mean (SD) ACT score was 20.5 (40). A significant difference in FeNO values was found among the three groups with different asthma control levels categorized according to the ACT score (P=0.001) but was not found among the three groups with different asthma treatment levels (P=0.425). FeNO was significantly inversely correlated with the ACT score (Spearman’s r =−0.224, P<0.001) and with spirometry parameters indicate airway obstruction such as predicted FEV1, FEV1/FVC, predicted PEF and predicted FEF25–75% with Spearman’s r were −0.187; −0.143; −0.091 and −0.195, respectively (all P<0.05), whereas no correlation between FeNO and FVC—an indicator of airway restriction—was found.

Conclusions

In these asthmatic patients in Vietnam, an inverse correlation was found between FeNO and the ACT score and between FeNO and spirometry indicators of airway obstruction. Therefore, FeNO may be a useful tool in asthma management.

Polychlorinated dibenzo-dioxins and polychlorinated dibenzo-furans exposure and altered lung function: The mediating role of oxidative stress

The lung has been reported to be one of the target organs of polychlorinated dibenzo-dioxins and polychlorinated dibenzo-furans (PCDD/Fs) in many toxicological studies. While the associations between PCDD/Fs exposure and lung function levels have not been investigated thoroughly. This study aimed to explore these associations and the potential mediating role of oxidative stress. In this study, 201 foundry workers and 222 non-exposed general residents were recruited from central China, and their lung function parameters were measured. Air and food samples were collected to determine the PCDD/Fs levels for individual PCDD/Fs exposure estimation. Serum PCDD/Fs levels were determined in a subgroup of individuals randomly selected from the study population to reflect the body burden. It was found that each 1-unit increase in ln-transformed concentration of PCDD/Fs exposure (fg TEQ/bw/day) was associated with a 0.47 L decrease in FVC and a 0.25 L decrease in FEV₁. Each 1-unit increase in ln-transformed concentration of serum PCDD/Fs (fg TEQ/g lipid) was associated with a 0.36 L decrease in FVC and a 0.24 L decrease in FEV₁. Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) was not only positively related to PCDD/Fs exposure, but also inversely associated with FVC and FEV₁ are FVC (β = -0.15, 95% CI: -0.22 to -0.08) and FEV₁ (β = -0.07, 95% CI: -0.13 to -0.02). Mediation analysis revealed that urinary 8-OHdG mediated 12.22% of the associations of external PCDD/Fs exposure with FVC levels, 28.61% and 27.87% of the associations of serum PCDD/Fs with FVC and FEV₁ levels respectively. Our findings suggested that PCDD/Fs exposure was associated with decreased lung function levels by a mechanism partly involving oxidatively generated damage to DNA.

Diagnostic value of FeNO and MMEF for predicting cough variant asthma in chronic cough patients with or without allergic rhinitis

OBJECTIVE

To evaluate the diagnostic value of fractional exhaled nitric oxide (FeNO) and maximum mid-expiratory flow (MMEF) for differentiating cough variant asthma (CVA) from chronic cough in patients with or without allergic rhinitis.

METHODS

In total, 328 patients with chronic cough who underwent spirometry and FeNO testing were consecutively included in the retrospective analysis. Patients were divided into the CVA (n = 125) or NCVA (n = 203) groups according to the diagnostic criteria of CVA. Receiver operating characteristic (ROC) curves were established to assess the diagnostic efficiency and optimal cutoff points of FeNO and MMEF for the prediction of CVA.

RESULTS

The optimal cutoff values of FeNO and MMEF to discriminate CVA from chronic cough were 24.5 ppb (AUC, 0.765; sensitivity, 69.60%; specificity 72.91%; PPV, 61.27%; NPV, 79.57%) and 66.2% (AUC, 0.771; sensitivity, 67.20%; specificity 78.33%; PPV, 65.63%; NPV, 79.50%). The optimal cutoff values of combining FeNO with MMEF to discriminate CVA from chronic cough were >22 ppb for FeNO and <62.6% for MMEF (AUC, 0.877). In patients with and without allergic rhinitis, the optimal cutoff point of FeNO to discriminate CVA from chronic cough was 24.5 ppb (AUC, 0.820) and 33.5 ppb (AUC, 0.707), respectively.

CONCLUSIONS

FeNO and MMEF might have greater value as negative parameters for differentiating CVA from chronic cough. Combining FeNO and MMEF provided a significantly better prediction than either alone. The diagnostic accuracy of FeNO for predicting CVA in chronic cough patients with allergic rhinitis was higher than in chronic cough patients without allergic rhinitis.

Improvement of asthma control after laser acupuncture and its impact on exhaled 8-isoprostane as an oxidative biomarker in chronic bronchial asthma

Traditional medicine may not control bronchial asthma. Many patients have uncontrolled symptoms and the underlying ongoing inflammation is persistent.

OBJECTIVE

to assess efficacy of laser acupuncture in improving asthma symptoms and underlying oxidative stress through monitoring exhaled 8-isoprostane.

METHOD

48 asthmatic (case group) received successive low level laser acupuncture sessions to stimulate acupoints for chronic asthma and 24 asthmatics received deactivated laser acupuncture sessions (control group). Asthma symptoms, asthma control questionnaire, concentration of 8-Isoprostane in exhaled breath condensate and airway resistance were assessed before and after laser acupuncture therapy.

RESULTS

After the completion of the course of laser acupuncture therapy, we observed significant improvement of asthma symptoms. Asthma control questionnaire improved from 9.7 ± 3.3 to 21.8 ± 3.6 (p 0.001). EBC 8-Isoprostane dropped from 14.7 ± 5.4 to 8.1 ± 5.0 (p 0.001). The airway resistance at R5 and R20 significantly decreased from 116.6 ± 25.8 & 124.5 ± 31.2 to 101.5 ± 25.6 &110.9 ± 29.9 respectively (p 0.001). Control patients who received sham acupuncture therapy did not show such improvement.

CONCLUSION

Laser acupuncture is an effective modality in treating bronchial asthma as evidenced by improved symptoms, airway resistance, and oxidative biomarkers.

Recent Advances in Inflammation and Treatment of Small Airways in Asthma

Small airways were historically considered to be almost irrelevant in the development and control of pulmonary chronic diseases but, as a matter of fact, in the past few years we have learned that they are not so "silent". Asthma is still a worldwide health issue due to the great share of patients being far from optimal management. Several studies have shown that the deeper lung inflammation plays a critical role in asthma pathogenesis, mostly in these not well-controlled subjects. Therefore, assessing the degree of small airways inflammation and impairment appears to be a pivotal step in the asthmatic patient's management. It is now possible to evaluate them through direct and indirect measurements, even if some obstacles still affect their clinical application. The success of any treatment obviously depends on several factors but reaching the deeper lung has become a priority and, for inhaled drugs, this is strictly connected to the molecule's size. The aim of the present review is to summarize the recent evidence concerning the small airway involvement in asthma, its physiopathological characteristics and how it can be evaluated in order to undertake a personalized pharmacological treatment and achieve a better disease control.

Asthma control in preschool children with small airway function as measured by IOS and fractional exhaled nitric oxide

OBJECTIVE

This study investigated the accuracy of impulse oscillometry (IOS) combined with fractional exhaled nitric oxide (FeNO) to assess asthma control among preschool children.

METHODS

A total of 79 preschool children(3-6 year old) with asthma and 25 healthy preschool children who visited a paediatrician were enrolled in this study. All of the children were tested for allergens, respiratory system resistance (at 5 and 20 Hz [R5, R20]), respiratory system reactance (at 5 Hz [X5]), the resonant frequency of reactance (Fres), and the area under the reactance curve (between 5 Hz and Fres (reactance area [AX]) using IOS and FeNO. A paediatric respiratory specialist who was unaware of the IOS and FeNO results assigned children with asthma to either the asthma-controlled group (n = 27) or the asthma-uncontrolled group (n = 52) based on the Global Initiative for Asthma (GINA) criteria. A healthy control group (n = 25) was also included. The relationships between the FeNO and IOS values as well as the asthma control of the three groups were analysed, and the areas under the curve (AUCs) were calculated for each measure.

RESULTS

(1) During the controlled group, means±standard deviations of AX, R5-20, R5, X5 and FeNO were 26.15 ± 7.534, 3.52 ± 1.311,9.97 ± 1.576,-3.85 ± 0.572,-3.85 ± 0.572. During the uncontrolled group, means±standard deviations of AX,R5-20,R5,X5 and FeNO were 38.34 ± 13.563,5.36 ± 1.545,11.41 ± 2.029,-5.07 ± 1.554,36.40 ± 21.07. Among preschool children, significant differences were observed between the controlled and uncontrolled group with regard to the small airway functional parameters (AX, R5-20, R5, and X5) and FeNO(P <0.05).(2) A receiver operating characteristic (ROC) analysis showed that the AUCs were 0.786 for FeNO alone, 0.751 for X5 alone, and 0.866 for X5 combined with FeNO (cut-off value: 27 ppb).

CONCLUSION

FeNO combined with the small airway function parameter X5 accurately assessed asthma control among preschool children.

Classifying oxidative stress by F2-isoprostane levels across human diseases: A meta-analysis

The notion that oxidative stress plays a role in virtually every human disease and environmental exposure has become ingrained in everyday knowledge. However, mounting evidence regarding the lack of specificity of biomarkers traditionally used as indicators of oxidative stress in human disease and exposures now necessitates re-evaluation. To prioritize these re-evaluations, published literature was comprehensively analyzed in a meta-analysis to quantitatively classify the levels of systemic oxidative damage across human disease and in response to environmental exposures.

In this meta-analysis, the F₂-isoprostane, 8-iso-PGF_2α, was specifically chosen as the representative marker of oxidative damage. To combine published values across measurement methods and specimens, the standardized mean differences (Hedges’ g) in 8-iso-PGF_2α levels between affected and control populations were calculated.

The meta-analysis resulted in a classification of oxidative damage levels as measured by 8-iso-PGF_2α across 50 human health outcomes and exposures from 242 distinct publications. Relatively small increases in 8-iso-PGF_2α levels (g<0.8) were found in the following conditions: hypertension (g=0.4), metabolic syndrome (g=0.5), asthma (g=0.4), and tobacco smoking (g=0.7). In contrast, large increases in 8-iso-PGF_2α levels were observed in pathologies of the kidney, e.g., chronic renal insufficiency (g=1.9), obstructive sleep apnoea (g=1.1), and pre-eclampsia (g=1.1), as well as respiratory tract disorders, e.g., cystic fibrosis (g=2.3).

In conclusion, we have established a quantitative classification for the level of 8-iso-PGF_2α generation in different human pathologies and exposures based on a comprehensive meta-analysis of published data. This analysis provides knowledge on the true involvement of oxidative damage across human health outcomes as well as utilizes past research to prioritize those conditions requiring further scrutiny on the mechanisms of biomarker generation.

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Oxidative damage is highly variable in human conditions as measured by F₂-isoprostanes.

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Respiratory tract and urogenital diseases have the highest F₂-isoprostanes.

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Cancer and cardiovascular diseases have surprisingly low F₂-isoprostanes.

Biomarkers in adult asthma: a systematic review of 8-isoprostane in exhaled breath condensate

OBJECTIVES

We aimed to assess the evidence for the use of 8-isoprostane in exhaled breath condensate (EBC) as a biomarker in adult asthma.

DESIGN

A systematic review and meta-analysis of EBC 8-isoprostane.

METHODS

We searched a number of online databases (including PubMed, Embase and Scopus) in January 2016. We included studies of adult non-smokers with EBC collection and asthma diagnosis conducted according to recognised guidelines. We aimed to pool data using random effects meta-analysis and assess heterogeneity using I ².

RESULTS

We included twenty studies, the findings from which were inconsistent. Seven studies (n = 329) reported 8-isoprostane levels in asthma to be significantly higher than that of control groups, whilst six studies (n = 403) did not. Only four studies were appropriate for inclusion in a random effects meta-analysis of mean difference. This found a statistically significant between-groups difference of 22 pg ml^-1. Confidence in the result is limited by the small number of studies and by substantial statistical heterogeneity (I ² = 94).

CONCLUSION

The clinical value of EBC 8-isoprostane as a quantitative assessment of oxidative stress in asthma remains unclear due to variability in results and methodological heterogeneity. It is essential to develop a robust and standardised methodology if the use of EBC 8-isoprostane in asthma is to be properly evaluated.

Association of Lung Inflammatory Cells with Small Airways Function and Exhaled Breath Markers in Smokers - Is There a Specific Role for Mast Cells?

Background

Smoking is associated with a mixed inflammatory infiltrate in the airways. We evaluated whether airway inflammation in smokers is related to lung function parameters and inflammatory markers in exhaled breath.

Methods

Thirty-seven smokers undergoing lung resection for primary lung cancer were assessed pre-operatively by lung function testing including single-breath-nitrogen washout test (sb-N2-test), measurement of fractional exhaled nitric oxide (FeNO) and pH/8-isoprostane in exhaled breath condensate (EBC). Lung tissue sections containing cancer-free large (LA) and small airways (SA) were stained for inflammatory cells. Mucosal (MC_T) respectively connective tissue mast cells (MC_TC) and interleukin-17A (IL-17A) expression by mast cells was analysed using a double-staining protocol.

Results

The median number of neutrophils, macrophages and mast cells infiltrating the lamina propria and adventitia of SA was higher than in LA. Both MCTC and MC_T were higher in the lamina propria of SA compared to LA (MC_TC: 49 vs. 27.4 cells/mm²; MC_T: 162.5 vs. 35.4 cells/mm²; P<0.005 for both instances). IL-17A expression was predominantly detected in MC_TC of LA. Significant correlations were found for the slope of phase III % pred. of the sb-N2-test (r_s= -0.39), for the FEV₁% pred. (r_s= 0.37) and for FEV₁/FVC ratio (r_s=0.38) with MC_T in SA (P<0.05 for all instances). 8-isoprostane concentration correlated with the mast cells in the SA (r_s=0.44), there was no correlation for pH or FeNO with cellular distribution in SA.

Conclusions

Neutrophils, macrophages and mast cells are more prominent in the SA indicating that these cells are involved in the development of small airway dysfunction in smokers. Among these cell types, the best correlation was found for mast cells with lung function parameters and inflammatory markers in exhaled breath. Furthermore, the observed predominant expression of IL-17A in mast cells warrants further investigation to elucidate their role in smoking-induced lung injury, despite the lack of correlation with lung function and exhaled breath parameters.

The role of the small airways in the pathophysiology of asthma and chronic obstructive pulmonary disease

Chronic respiratory diseases, such as asthma and chronic obstructive pulmonary disease (COPD), represent a major social and economic burden for worldwide health systems. During recent years, increasing attention has been directed to the role of small airways in respiratory diseases, and their exact contribution to the pathophysiology of asthma and COPD continues to be clarified. Indeed, it has been suggested that small airways play a distinct role in specific disease phenotypes. Besides providing information on small airways structure and diagnostic procedures, this review therefore aims to present updated and evidence-based findings on the role of small airways in the pathophysiology of asthma and COPD. Most of the available information derives from either pathological studies or review articles and there are few data on the natural history of small airways disease in the onset or progression of asthma and COPD. Comparisons between studies on the role of small airways are hard to draw because both asthma and COPD are highly heterogeneous conditions. Most studies have been performed in small population samples, and different techniques to characterize aspects of small airways function have been employed in order to assess inflammation and remodelling. Most methods of assessing small airways dysfunction have been largely confined to research purposes, but some data are encouraging, supporting the utilization of certain techniques into daily clinical practice, particularly for early-stage diseases, when subjects are often asymptomatic and routine pulmonary function tests may be within normal ranges. In this context further clinical trials and real-life feedback on large populations are desirable.

Biomarkers of inflammation in persons with chronic tetraplegia

In addition to lung volume restriction, individuals with chronic tetraplegia exhibit reduced airway caliber and bronchodilator responsiveness similar to persons with asthma. In asthma, airflow obstruction is closely linked to airway inflammation. Conversely, little is known regarding the airway inflammatory response in tetraplegia. To compare levels of biomarkers of inflammation in exhaled breath condensate (EBC) and serum in subjects with chronic tetraplegia, mild asthma, and able-bodied controls.Prospective, observational pilot study. Thirty-four subjects participated: tetraplegia (n = 12), asthma (n = 12), controls (n = 10). Biomarkers in EBC [8-isoprostane (8-IP), leukotriene B4 (LT-B4), prostaglandin E2 (PG-E2), tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6)] and serum (8-IP, LT-B4, TNF-α, IL-6) were determined using commercially available EIA kits (Cayman Chemical Company, Ann Arbor, MI). Separate, one-way ANOVA with Bonferroni's post-hoc analyses were performed to determine group differences in demographic and dependent variables [EBC and serum biomarkers, fractional exhaled nitric oxide (FeNO), pulmonary function parameters, and specific airway conductance (sGaw)]. The tetraplegia group had significantly elevated 8-IP levels in EBC compared to the asthma (68 ± 38 versus 21 ± 13 pg ml(-1); p < 0.001) and control groups (22 ± 13 pg ml(-1); p < 0.01), respectively. FeNO levels were significantly elevated in the asthma compared to the control group (26 ± 18 versus 11 ± 4 ppb; p < 0.05), and trended higher than levels in the tetraplegia group (15 ± 6; p = 0.08). Levels of serum biomarkers did not differ significantly among groups. Through analysis of EBC, levels of 8-IP were significantly elevated compared to levels found in individuals with mild asthma and healthy controls. Further studies are needed to extend upon these preliminary findings that suggest the presence of airway inflammation in subjects with chronic tetraplegia, and how this relates to pulmonary dysfunction in this population.

Usefulness of noninvasive methods for the study of bronchial inflammation in the control of patients with asthma

Bronchial asthma is one of the most prevalent respiratory conditions. Although it is defined as an inflammatory disease, the current guidelines for both diagnosis and follow-up of patients are based only on clinical and lung function parameters. Current research is focused on finding markers that can accurately predict future risk, and on assessing the ability of these markers to guide medical treatment and thus improve prognosis. The use of noninvasive methods to study airway inflammation is gaining increasing support. The study of eosinophils in induced sputum has proved useful for the diagnosis of asthma; however, its clinical implementation is complex. Some studies have shown that the measurement of exhaled nitric oxide (FeNO) may also be useful to establish disease phenotypes and improve control. Others have found that the measurement of pH and certain markers of oxidative stress, cytokines and prostanoids in exhaled breath condensate (EBC) may also be useful as well as the measurement of the temperature of exhaled breath and the analysis of volatile organic compounds (VOCs). In conclusion, since asthma is an inflammatory disease, it seems appropriate to try to control it through the study of airway inflammation using noninvasive methods. In this regard, the analysis of induced sputum cells has proved very useful, although the clinical implementation of this technique seems difficult. Other techniques such as temperature measurement, the analysis of FeNO, the analysis of the VOCs in exhaled breath, or the study of certain biomarkers in EBC require further study in order to determine their clinical applicability.

Biomarker discovery in asthma and COPD by proteomic approaches

Asthma and chronic obstructive pulmonary disease (COPD) are multifactorial respiratory diseases, characterized by reversible and irreversible airway obstruction, respectively. Even if the primary causes of these diseases remain unknown, inflammation is a central feature that leads to progressive and permanent pulmonary tissue damage (airway remodeling) up to the total loss of lung function. Therefore, the elucidation of the inflammation mechanisms and the characterization of the biological pathways, involved in asthma and COPD pathogenesis, are relevant in finding new possible diagnostic/prognostic biomarkers and for the validation of new drug targets. In this context, current advances in proteomic approaches, especially those based on MS, provide new tools to facilitate the discovery-driven studies of new biomarkers in respiratory diseases and improve the clinical reliability of the next generation of biomarkers for these diseases consisting of multiple phenotypes. This review will report an overview of the current proteomic methods applied to the discovery of candidate biomarkers for asthma and COPD, giving a special emphasis to emerging MS-based techniques.

Techniques of assessing small airways dysfunction

The small airways are defined as those less than 2 mm in diameter. They are a major site of pathology in many lung diseases, not least chronic obstructive pulmonary disease (COPD) and asthma. The small airways are frequently involved early in the course of these diseases, with significant pathology demonstrable often before the onset of symptoms or changes in spirometry and imaging. Despite their importance, they have proven relatively difficult to study. This is in part due to their relative inaccessibility to biopsy and their small size which makes their imaging difficult. Traditional lung function tests may only become abnormal once there is a significant burden of disease within them. This has led to the term 'the quiet zone' of the lung. In recent years, more specialised tests have been developed which may detect these changes earlier, perhaps offering the possibility of earlier diagnosis and intervention. These tests are now moving from the realms of clinical research laboratories into routine clinical practice and are increasingly useful in the diagnosis and monitoring of respiratory diseases. This article gives an overview of small airways physiology and some of the routine and more advanced tests of airway function.

Occupational asthma follow-up--which markers are elevated in exhaled breath condensate and plasma?

OBJECTIVES

To search for optimal markers in the exhaled breath condensate (EBC), plasma and urine that would reflect the activity/severity of occupational asthma (OA) after the withdrawal from the exposure to the allergen.

MATERIAL AND METHODS

Markers of oxidative stress: 8-iso-prostaglandin F2α (8-isoprostane, 8-ISO), malondialdehyde (MDA), 4-hydroxy-trans-2-nonenale (HNE), cysteinyl leukotrienes (LT) and LTB4 were determined using liquid chromatography and mass spectrometry in 43 subjects with immunological OA (49.3 ± 11.8 years), removed from the exposure to the sensitizing agent 10.5 ± 6.5 years ago; and in 20 healthy subjects (49.0 ± 14.9 years). EBC was harvested both before and after the methacholine challenge test. In parallel, identical markers were collected in plasma and urine. The results were analyzed together with forced expiratory volume in one second (FEV1), blood eosinophils, immunoglobulin E (IgE) and eosinophilic cationic protein (ECP) and statistically evaluated (Spearman rank correlation rS, two- or one-sample t tests and alternatively Kruskal Wallis or pair Wilcoxon tests).

RESULTS

Several parameters of lung functions were lower in the patients (FEV1% predicted, MEF25% and MEF50%, Rtot%, p < 0.001). Shorter time interval since the removal from the allergen exposure correlated with higher ECP (rS = 0.375) and lower FEV1%, MEF25% and MEF50% after methacholine challenge (rS = -0.404, -0.425 and -0.532, respectively). In the patients, IgE (p < 0.001) and ECP (p = 0.009) was increased compared to controls. In EBC, 8-ISO and cysteinyl LTs were elevated in the asthmatics initially and after the challenge. Initial 8-ISO in plasma correlated negatively with FEV1 (rS = -0.409) and with methacholine PD20 (rS = -0.474). 8-ISO in plasma after the challenge correlated with IgE (rS = 0.396).

CONCLUSIONS

The improvement in OA is very slow and objective impairments persist years after removal from the exposure. Cysteinyl LTs and 8-ISO in EBC and 8-ISO in plasma might enrich the spectrum of useful objective tests for the follow-up of OA.

Techniques for assessing small airways function: Possible applications in asthma and COPD

In recent years special interest has been expressed for the contribution of small airways in the pathophysiology, clinical manifestations and treatment of asthma and COPD. Small airways contribute little to the total respiratory resistance so that extensive damage of small airways may occur before the appearance of any symptoms, and this is the reason why they are characterized as the "silent zone" of airways. Furthermore, the peripheral localization of the small airways and their small diameter constitutes difficult their direct assessment. Thus, they are usually studied indirectly, taking advantage of the effects of their obstruction, such as premature closure, air trapping, heterogeneity of ventilation, and lung volume dependence of airflow limitation. Today, several heterogeneous methods for the assessment of small airways are available. These can be either functional (spirometry, plethysmography, resistance measurements, nitrogen washout, alveolar nitric oxide, frequency dependence of compliance, flow-volume curves breathing mixture of helium-oxygen) or imaging (mainly through high resolution computed tomography). The above-mentioned methods are summarized in Table 1. However, no method is currently considered as the "gold standard" and it seems that combinations of tests are needed. Furthermore, it is not clear whether the small airways are affected in all patients with asthma or COPD and their clinical significance remains under investigation. Well-designed future studies with large numbers of patients are expected to reveal which of the methods for assessing the small airways is the most accurate, reliable and reproducible, for which patients, and which can be used for the evaluation of the effects of treatment.

Alveolar nitric oxide and asthma control in mild untreated asthma

BACKGROUND

The role of the peripheral airways in asthma is increasingly being recognized as a potential target for the achievement of optimal control of the disease. We postulated that the inflammatory changes of the small airways are implicated in the lack of asthma control in mild asthma.

OBJECTIVE

To test this hypothesis, we measured the alveolar fraction of exhaled NO (CalvNO) in patients with mild asthma with different levels of control of symptoms.

METHODS

Seventy-eight patients with asthma (35 men, age, 37 ± 15 years; FEV1 percentage of predicted, 100% ± 9%) were studied. Asthma control was assessed by using the Asthma Control Test (ACT). Measurements of exhaled NO at multiple constant flows were performed.

RESULTS

Bronchial NO concentrations were 27.1 ± 20 nL/min, [corrected] and CalvNO levels were 5.7 ± 3.4 ppb. The ACT score was 20 ± 4.2. The level of asthma control was not associated with bronchial NO concentrations (rs = 0.16, P = .15). However, a significant correlation was found between the ACT score and CalvNO (rs = 0.25, P = .03). Moreover, CalvNO was significantly higher in patients with uncontrolled asthma than in patients with controlled/partially controlled asthma (6.7 ± 2.6 ppb vs 4.9 ± 2.6 nL/min, [corrected] respectively, P = .02). In the subgroup of patients with asthma who underwent extrafine inhaled corticosteroid treatment, the magnitude of the inhaled corticosteroid-induced improvement in asthma control positively correlated with baseline CalvNO at 1 month (rs = 0.39, P = .003) and at 3 months (rs = 0.49, P < .0001).

CONCLUSIONS

The alveolar component of exhaled NO is associated with the lack of asthma control in patients with mild, untreated asthma. This observation supports the notion that abnormalities of the peripheral airways are implicated in the mildest forms of asthma.

Application of metabolomics approaches to the study of respiratory diseases

Metabolomics is the global unbiased analysis of all the small-molecule metabolites within a biological system, under a given set of conditions. These methods offer the potential for a holistic approach to clinical medicine, as well as improving disease diagnosis and understanding of pathological mechanisms. Respiratory diseases including asthma and chronic obstructive pulmonary disorder are increasing globally, with the latter predicted to become the third leading cause of global mortality by 2020. The root causes for disease onset remain poorly understood and no cures are available. This review presents an overview of metabolomics followed by in-depth discussion of its application to the study of respiratory diseases, including the design of metabolomics experiments, choice of clinical material collected and potentially confounding experimental factors. Particular challenges in the field are presented and placed within the context of the future of the applications of metabolomics approaches to the study of respiratory diseases.

Assessing and accessing the small airways; implications for asthma management

Despite the wealth of experience in the management of asthma, the disease remains inadequately controlled in some patients, who face long-term respiratory impairment and disability. The disease has been characterised as an inflammatory condition affecting first the larger airways and eventually the smaller airways, but there is evidence that peripheral airway involvement defines a particular and more severe phenotype of asthma. For this reason, assessing functional and biological parameters reflective of small airways involvement is important prognostically. No assessment method is universally and directly representative of peripheral airway function, but the traditional spirometric tests, including vital capacity, residual volume and forced vital capacity, are somewhat correlated with this function; useful methods for further assessment include the single-breath nitrogen wash-out test, impulse oscillometry, nitrous oxide and exhaled breath concentrate measurements, as well as computed tomography to reflect air trapping and response to treatment. Formulation advancements have made for easier treatment access to the smaller airways, with the new extrafine formulations resulting in better asthma control compared with non-extrafine formulations.

Physiological measurement of the small airways

Noninvasive physiological measurements are reviewed that have been reported in the literature with the specific aim being to study the small airways in lung disease. This has mostly involved at-the-mouth noninvasive measurement of flow, pressure or inert gas concentration, with the intent of deriving one or more indices that are representative of small airway structure and function. While these measurements have remained relatively low-tech, the effort and sophistication increasingly reside with the interpretation of such indices. When aspiring to derive information at the mouth about structural and mechanical processes occurring several airway generations away in a complex cyclically changing cul-de-sac structure, conceptual or semi-quantitative lung models can be valuable. Two assumptions that are central to small airway structure-function measurement are that of an average airway change at a given peripheral lung generation and of a parallel heterogeneity in airway changes. While these are complementary pieces of information, they can affect certain small airways tests in confounding ways. We critically analyzed the various small airway tests under review, while contending that negative outcomes of these tests are probably a true reflection of the fact that no change occurred in the small airways. Utmost care has been taken to not favor one technique over another, given that most current small airways tests still have room for improvement in terms of rendering their content more specific to the small airways. One way to achieve this could consist of the coupling of signals collected at the mouth to spatial information gathered from imaging in the same patient.

Hyperoxidized peroxiredoxins in peripheral blood mononuclear cells of asthma patients is associated with asthma severity

AIMS

Oxidative stress is involved in the pathogenesis of asthma, and peroxiredoxins (PRDX) may be critical in controlling intracellular oxidative stress. The aim of this study was to evaluate expressions of PRDX and their hyperoxidized forms in asthmatic individuals.

MAIN METHODS

The levels of expression of PRDX1, PRDX2, PRDX3, and PRDX6 and their hyperoxidized forms (PRDX-SO(3)) were measured in PBMCs from asthma patients and control subjects. In addition, cells from these subjects were treated with hydrogen peroxide (H(2)O(2)) and their intracellular concentrations of reactive oxygen species (ROS) were measured.

KEY FINDINGS

The ratios of hyperoxidized to total PRDX (PRDX-SO(3/)PRDX) in PBMCs were significantly higher in asthma patients than in normal subjects and were correlated with disease severity, with the highest ratio seen in patients with severe asthma. Furthermore, H(2)O(2) treatment of PBMCs, particularly lymphocytes, increased intracellular ROS concentrations with greater and more persistent increases observed in cells from asthmatic than from control subjects.

SIGNIFICANCE

Hyperoxidation of PRDX may serve as a biomarker of asthma severity and may predict enhanced susceptibility to oxidative stress load in PBMCs of asthmatics.

Measures of asthma control

PURPOSE OF REVIEW

Over the past decade, the concept of asthma control as distinct from asthma severity has been clearly defined. Well controlled asthma is the goal of therapy in all asthma patients. This review is a comprehensive description of the tools currently available for a methodical assessment of different aspects of asthma control in clinical practice and research.

RECENT FINDINGS

Several questionnaires for assessing asthma control have been extensively validated in adults. In children, validation data are less extensive. Considerable overlap exists between asthma control measures and measures of asthma-specific quality of life. Asthma-specific quality-of-life questionnaires have been used as primary outcome measures in major clinical trials evaluating asthma therapy. Biomarkers that reflect eosinophilic inflammation of the airways are used as intermediate outcome measures to reflect the biological basis of asthma control. There is some controversy, however, over which biomarkers are best incorporated into therapeutic algorithms that attempt to achieve maximal asthma control while minimizing treatment intensity.

SUMMARY

In designing clinical studies to evaluate different asthma therapies, researchers will find this review to be a useful resource in terms of choosing the appropriate tool for assessing asthma control. This is also a valuable resource for a methodical assessment of response to asthma therapy in routine clinical care.

Utility of two-compartment models of exhaled nitric oxide in patients with asthma

Two-compartment models provide more precise information about the contribution of the different portions of the airways to exhaled nitric oxide (NO). Airway wall concentration of NO (Caw,NO) and maximum flux of NO in the airways (J'aw,NO) reflect the tissue production rate of NO and they can be modified by corticosteroids. The airway wall diffusing capacity of NO (Daw,NO) depends on diverse physical and anatomical determinants of the airways, such as gas exchange surface area. Daw,NO can be modified by structural and physiological changes that are characteristic of airway remodeling, which take place over the long term. The alveolar concentration of NO (Calv,NO) represents the degree of small airway inflammation. The persistence of high Calv,NO in patients treated with inhaled corticosteroids could reflect the incapacity of these drugs to reach distal locations due to the heterogeneity of the acinar ventilation. In this review, we evaluate the parameters provided by the compartmentalized analysis of exhaled NO that could be useful in characterizing asthma patients.

Small airway function, exhaled NO and airway hyper-responsiveness in paediatric asthma

BACKGROUND

Asthma is a chronic inflammatory airway disorder known to involve the peripheral airways. Current guidelines state that diagnosis and treatment should be guided by symptoms and spirometry. FEV(1) is, however, a poor marker of small airway function and correlates poorly with asthma control and airway inflammation.

AIMS

To assess the contribution of small airway dysfunction and inflammation in paediatric asthma. A secondary aim was to study the associations between small airway dysfunction, airway inflammation and airway hyper-responsiveness (AHR).

METHODS

Small airway function was measured as LCI, S(cond) and S(acin), evaluated with the SF(6) multiple breath inert gas washout (MBW) technique, in 47 asthmatic children and 74 healthy controls. Exhaled NO at multiple exhalation flow rates including 50 mL/s (FENO(50)) was assessed to calculate alveolar NO and bronchial NO flux (a surrogate for airway inflammation). AHR was evaluated with isocapnoic dry air hyperventilation challenge in the asthmatic children.

RESULTS

S(cond) was elevated in 31 (66%) and S(acin) in 18 (38%) of the asthmatic subjects. LCI was increased and FEV(1) decreased in 7 (15%) of the subjects with asthma. Individuals with AHR had higher S(cond) (p = 0.001) and FENO(50) (p < 0.0001) than those without AHR. The levels of FENO(50) and bronchial NO flux were elevated in asthmatic subjects compared with healthy controls. In asthma, S(cond) correlated with FENO(50) (r(s) = 0.42, p = 0.003) and alveolar NO (r(s) = 0.40, p = 0.011), and S(acin) correlated with alveolar NO (r(s) = 0.40, p = 0.015).

CONCLUSION

Dysfunction of small conducting airways is associated with airway inflammation and hyper-responsiveness in paediatric asthma.

Anti-inflammatory effects of pre-seasonal Th1-adjuvant vaccine to Parietaria judaica in asthmatics

Background:

The ultra-short course pre-seasonal allergy vaccine, containing appropriate allergoids with the adjuvant monophosphoryl lipid A (MPL), may be effective in treating allergic symptoms.

Objective:

To explore the timing of the immunological responses to the pre-seasonal allergy vaccine.

Methods:

Four subcutaneous injections of the active product (Pollinex Quattro) were administered to 20 Parietaria-sensitive intermittent asthmatics (M/F: 12/8; age: 48 ± 10 years; FEV₁% predicted: 108% ± 12%) during the 6 weeks prior to the start of the pollen season. Exhaled breath condensate (EBC) was collected immediately before the first and immediately after the last injections (t₁ and t₂), during the pollen season (t₃) and after (t₄) the pollen season. EBC was analyzed to determine the levels of pH and 8-isoprostane. Ten Parietaria-sensitive asthmatics served as the untreated control group at t₁ and t₂.

Results:

Measured pH levels were 7.64 ± 0.33 at t₁, 7.67 ± 0.23 at t₂, 7.72 ± 0.34 at t₃, and 7.82 ± 0.34 at t₄ (P = 0.049 vs baseline). 8-isoprostane levels were significantly lower than baseline at each visit (mean difference from baseline, for t₂: −0.77 pg, P = 0.031; for t₃: −0.92 pg, P = 0.010; for t₄: −0.70 pg, P = 0.048). In the control group, pH levels were 7.73 ± 0.26 at baseline and did not change after 6 weeks (7.79 ± 0.25, P = 0.33). Similarly, the concentrations of 8-isoprostane in the control group were not different from those of the study group at baseline (P = 0.86), and the levels remained unchanged after 6 weeks (P = 0.58).

Conclusion:

These findings show that the ultra-short course of vaccine adjuvated with MPL acutely reduces the degree of airway inflammation, as expressed by markers of oxidative stress, and suggest that this reduction is maintained during and after the pollen season.

The role of small airways in obstructive airway diseases

This review article is a summary of a seminar organised by the European Respiratory Society on "The role of small airways in obstructive airway diseases" which was held in October 2010 in Amsterdam, the Netherlands. The aims of the seminar were to identify important questions related to small airways involvement in asthma and chronic obstructive pulmonary disease (COPD), and to discuss future approaches based on current and evolving knowledge. Data obtained by pathological and physiological measurements in small airways and their relevance to clinical manifestations and therapeutics in asthma and COPD were reviewed. It was concluded that our knowledge on the roles of small airways in asthma and COPD is limited. Studies of large numbers of well-characterised subjects using multiple methods (genetic characterisation, cell biology and physiology, imaging) and integration of the data using mathematical models are suggested to be of interest. The availability of these techniques coupled with our ability to better target inhaled molecules to small airways provide a unique opportunity for a reappraisal of the relevance of small airways in chronic airway diseases.

Inflammatory markers in childhood asthma

The major characteristic of asthma is persistent airway inflammation that fails to resolve spontaneously. Dysregulation of pro- and anti-inflammatory mechanisms is responsible for the development of chronic inflammation. The inflammatory reaction is mediated by numerous cells and their mediators. Detection and quantification of airway inflammation in children are subject to many requirements, e.g., use of biologic samples obtained in a non-invasive way; use of standardized analytical methods to determine biomarkers that can identify inflammation processes (inflammation itself, oxidative stress, apoptosis and remodelling); determining the role of systemic inflammation; assessment of correlation of various biomarkers of inflammation with clinical parameters and their diagnostic efficacy; providing a tool(s) to monitor diseases, and to evaluate adequacy of therapy; and predicting the clinical course of inflammation and prognosis of asthma. Using standardized analyses, it is now possible to determine direct markers of local inflammation, i.e., fractional nitric oxide (marker of oxidative stress) in exhaled breath, pH (marker of acid stress) in breath condensate, and indirect markers in blood/serum, i.e., eosinophil granulocytes (indicating migration), eosinophil cationic protein (marker of activated eosinophil granulocytes) and C-reactive protein (marker of systemic inflammation). However, none of these biomarkers are specific for asthma. Further standardization of the known pulmonary biomarkers of local inflammation and identification of new ones will allow for longitudinal follow-up of inflammation in children with asthma.

Impact of cigarette smoking on maximal expiratory flows in a general population: the Takahata study

BACKGROUND

Maximal expiratory flows (MEFs) depend on the elastic recoil pressure in the alveoli, airway resistance and bronchial collapsibility. MEFs at lower levels of vital capacity [MEFs at x% FVC (MEF(x))] would indicate the patency of peripheral airways. In Japan, a ratio of MEF(50) to MEF(25) (MEF(50)/MEF(25)) greater than 4.0 is used as an index of injury to the small airways in subjects without airflow limitation. However, to date there have been no epidemiological investigations relating to this index. The aim of this study was to evaluate the impact of cigarette smoking on MEFs in a general population, and to assess the validity of using this index to evaluate injury to the small airways.

METHODS

Subjects aged 40 years or older (n=2,917), who had participated in a community-based annual health-check in Takahata, Japan, were enrolled in the study. MEF(75), MEF(50) and MEF(25) were measured in these subjects.

RESULTS

In smokers, as compared with never-smokers, the percentage predicted MEFs (%MEFs) decreased according to the aging of the population, except in the case of %MEF(25) in females. In males, but not in females, %MEFs decreased significantly with an increase in cigarette consumption. In both genders, MEF(50)/MEF(25) was slightly, but significantly, elevated with aging of the population. In addition, 36.5% of subjects who participated in this health-check had MEF(50)/MEF(25) values greater than 4.0. No difference in MEF(50)/MEF(25) was observed between smokers and never-smokers.

CONCLUSION

Cigarette smoking enhanced the age-related decline in MEFs. Since many healthy subjects aged 40 years or older have MEF(50)/MEF(25) values greater than 4.0, the use of this criterion may over-estimate the presence of small airway disease.

Actual control state of intermittent asthma classified on the basis of subjective symptoms

BACKGROUND

Many primary care physicians begin treatment of asthma patients on the basis of their subjective symptoms. We hypothesized that patients diagnosed as having intermittent asthma on the basis of subjective symptoms by a primary care physician may have their asthma severity underestimated.

METHODS

We investigated 293 patients who were in their 20s and diagnosed as having asthma. Two hundred and fifteen patients with intermittent asthma diagnosed on the basis of subjective symptoms were chosen. We evaluated their asthma severity using FEV(1) (% predicted), airway hyperresponsiveness to histamine dihydrochloride, and exhaled nitric oxide level as factors that determine asthma severity.

RESULTS

Among these patients, 27.8% were determined to have moderate or severe asthma by the pulmonary function test. History of childhood asthma was the only significant risk factor for a low pulmonary function. Among the patients, 60.9% showed moderate or severe airway hyperresponsiveness. History of childhood asthma was the only significant risk factor for the increase in airway hyperresponsiveness. Moreover, 53.8% showed a high exhaled nitric oxide level. History of childhood asthma was associated with an increased risk of a high eNO level as determined by univariate analysis, but no significant difference was observed in the comparison by multiple logistic regression analysis. The percentage of subjects classified into the mild group by all of the results of the three tests was only 20.6%.

CONCLUSION

We showed that asthma severity classified on the basis of only subjective symptoms may be underestimated in young adults. We showed that the diagnosis of mild intermittent asthma needs to be determined carefully.

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.

Forced expiratory flow between 25% and 75% of vital capacity and FEV1/forced vital capacity ratio in relation to clinical and physiological parameters in asthmatic children with normal FEV1 values

BACKGROUND

The assumption that the assessment of forced expiratory flow between 25% and 75% of vital capacity (FEF(25-75)) does not provide additional information in asthmatic children with normal FEV(1) percent predicted has not been adequately tested.

OBJECTIVE

We sought to determine whether the measurement of FEF(25-75) percent predicted offers advantages over FEV(1) percent predicted and FEV(1)/forced vital capacity (FVC) percent predicted for the evaluation of childhood asthma.

METHODS

This is a secondary analysis of data from the Pediatric Asthma Controller Trial and the Characterizing the Response to a Leukotriene Receptor Antagonist and Inhaled Corticosteroid trials. Pearson correlation coefficients, Pearson partial correlation coefficients, canonical correlations, and receiver operating characteristic (ROC) curves were constructed.

RESULTS

Among 437 children with normal FEV(1) percent predicted, FEF(25-75) percent predicted, and FEV(1)/FVC percent predicted were (1) positively correlated with log(2) methacholine PC(20), (2) positively correlated with morning and evening peak expiratory flow percent predicted, and (3) negatively correlated with log(10) fraction of exhaled nitric oxide and bronchodilator responsiveness. Pearson partial correlations and canonical correlations indicated that FEF(25-75) percent predicted was better correlated with bronchodilator responsiveness and log(2) methacholine PC(20) than were FEV(1) percent predicted or FEV(1)/FVC percent predicted. In the ROC curve analysis, FEF(25-75) at 65% of predicted value had a 90% sensitivity and a 67% specificity for detecting a 20% increase in FEV(1) after albuterol inhalation.

CONCLUSION

FEF(25-75) percent predicted was well correlated with bronchodilator responsiveness in asthmatic children with normal FEV(1). FEF(25-75) percent predicted should be evaluated in clinical studies of asthma in children and might be of use in predicting the presence of clinically relevant reversible airflow obstruction.

Effects of extra-fine inhaled beclomethasone/formoterol on both large and small airways in asthma

BACKGROUND

Airway inflammation in asthma involves both large and small airways, and the combination of inhaled corticosteroids (ICS) and long acting beta-2 agonists (LABA) is the mainstay of therapy. Available inhaled combinations differ in terms of drug delivery to the lung and the ability to reach small airways.

AIM

To evaluate whether treatment with an extra-fine inhaled combination provides additional effects vs a nonextra-fine combination on airway function.

METHODS

After a 1- to 4-week run-in period, patients with asthma were randomized to a double blind, double dummy, 12-week treatment with either extra-fine beclomethasone/formoterol (BDP/F) 400/24 microg daily or fluticasone propionate/salmeterol (FP/S) 500/100 microg daily. Methacholine (Mch) bronchoprovocation challenge and single breath nitrogen (sbN2) test were performed.

RESULTS

Thirty patients with asthma (15 men), mean age 43, mean forced expiratory volume in the first second (FEV(1)) 71.4% of predicted, were included. A significant increase (P < 0.01) versus baseline was observed in predose FEV(1) in both BDP/F and FP/S groups (0.37 +/- 0.13 l and 0.36 +/- 0.12 l, respectively). PD(20)FEV(1) Mch improved significantly from 90.42 (+/-30.08) microg to 432.41 (+/-122.71) microg in the BDP/F group (P = 0.01) but not in the FP/S group. A trend toward improvement vs baseline was observed for BDP/F in closing capacity (CC), whereas no differences were recorded in other sbN(2) test parameters.

CONCLUSION

The findings of this pilot study suggest that an extra-fine inhaled combination for the treatment of asthma has beneficial effects on both large and small airways function as expressed by Mch and sbN(2) tests.

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.

The role of oxidative stress in the pathogenesis of asthma

Oxidative stress plays a critical role in the pathogenesis of asthma. To effectively control oxidative stress in asthmatics, it is important to investigate the precise intracellular mechanism by which the development of immunity, rather than immune tolerance and progression of airway inflammation, is induced. In this article, we suggest that protein tyrosine phosphatases, as intracellular negative regulators, and intracellular antioxidant enzymes such as peroxiredoxins can be regulated by oxidative stress during intracellular signaling.

Patient perspectives in the management of asthma: improving patient outcomes through critical selection of treatment options

Asthma is a chronic inflammatory disorder of the airways that requires long-term treatment, the goal of which is to control clinical symptoms for extended periods with the least possible amount of drugs. International guidelines recommend the addition of an inhaled long-acting beta2-agonist (LABA) to a low- to medium-dose inhaled corticosteroid (ICS) when low doses of ICS fail to control asthma symptoms. The fixed combined administration of ICS/LABA improves patient compliance, reducing the risk of therapy discontinuation. The relative deposition pattern of the inhaled drug to the target site is the result of a complex interaction between the device used, the aerosol formulation and the patient's adherence to therapy. Different inhalation devices have been introduced in clinical practice over time. The new hydrofluoroalkane (HFA) solution aerosols allow for the particle size to be modified, thus leading to deeper penetration of the medication into the lung. The Modulite((R)) technology allows for the manipulation of inhaled HFA-based solution formulations, such as the fixed beclomethasone/formoterol combination, resulting in a uniform treatment of inflammation and bronchoconstriction. The success of any anti-asthmatic treatment depends on the choice of the correct device and the adherence to therapy.