Bronchial hyperresponsiveness

Evaluation of bronchial hyperresponsiveness in asthmatic paediatric patients using mannitol challenge test - Impacts of body mass index

BACKGROUND

Increasing epidemiological studies reported that overweight/obese asthma patients had more frequent and severe symptoms and exacerbations, indicating their asthma management may not be sufficient. Airway hyperresponsiveness (AHR), a significant feature of asthma, was found to link with the body mass index (BMI) with mixed findings using the "direct" methacholine challenge test. The objective was to examine the association between BMI and asthma control, as reflected by the "indirect" AHR with the mannitol challenge test in a paediatric asthmatic population.

METHODS

A total of 80 subjects with physician-diagnosed asthma, aged 6-18 years were enrolled in this cross-sectional study. Patients were first asked to complete the Asthma Control Test (ACT) questionnaire to self-evaluate their disease status. A mannitol challenge test was then performed to assess their AHR severity.

RESULTS

Seventy-six patients (96%) rated their asthma as well-controlled with an ACT score ≥ 20, but 42 patients (53%) were tested positive in the mannitol challenge test with mild and moderate AHR. While patients with mild AHR had comparable lung functions to those without AHR, patients with moderate AHR showed slightly but significantly lower FEV1 and FEV1/FVC values. Although no significant difference in the BMI values was noted for patients with different levels of AHR, the trend of increasing BMI with age was steeper for patients with moderate AHR.

CONCLUSION

A high prevalence of AHR (>50%) was found in asthmatic children who self-evaluated with good asthma control. No significant influence of the BMI on the AHR severity could be demonstrated in this population with the "indirect" mannitol challenge test. Since only a small number of overweight/obese subjects were recruited in the present study, further verification of the results with a larger sample size of obese subjects is required.

Cough-Variant Asthma: A Review of Clinical Characteristics, Diagnosis, and Pathophysiology

Chronic cough is among the most common symptoms prompting medical care. Cough-variant asthma (CVA) is an asthma subset where cough is the primary symptom, without wheezing, chest tightness, or dyspnea. It is an important cause of chronic cough, estimated to account for 25% to 42% of cases, but likely underdiagnosed due to delayed recognition and pitfalls of diagnostic testing. Early recognition and treatment can reduce morbidity and delay its progression to more typical asthma. This review details the clinical characteristics, diagnosis, pathophysiology, and treatment of CVA and contrasts it with classic asthma and other causes of chronic cough.

Stellate ganglia block reduces airway hyperresponsiveness with modulates the IKK/NF-κB/IL-4/IL-5/IL-13 pathway

BACKGROUND

Airway hyperresponsiveness (AHR) is characterized by excessive contraction of airway smooth muscle, leading to airflow limitation, increasing perioperative airway spasm and even triggering the defense of silent lungs, which can lead to delayed surgery. Stellate ganglion blockade (SGB) has gained attention for its immunomodulatory and anti-inflammatory effects; however, its impact on AHR and the underlying mechanisms remain unexplored. This study aims to evaluate whether SGB reduces AHR and if this effect is related to inflammation.

METHODS

The experimental groups included Control, OVA (ovalbumin-induced AHR), OVA + SGB2, OVA + SGB4, OVA + SGB5, OVA + SGB6, OVA + SGB8, OVA + 4PBA, Tm, and Tm + SGB6. Mice underwent varying numbers of SGB interventions over 17 days. On day 18, lung function tests were performed, followed by ELISA of IL-4, IL-5, and IL-13 levels in alveolar lavage fluid from the right lung, and finally, tissue from the right lung was extracted for transcriptome analysis, and tissue from the left lung (without lavage fluid) was stained with HE staining to assess histopathological changes.

RESULTS

Compared to the Control group, the OVA group exhibited increased overall respiratory resistance (Rrs), overall respiratory elasticity (Ers), central airway resistance (Rn), peripheral tissue elasticity (H), and tissue damage (G), alongside decreased overall respiratory compliance (Crs) (P < 0.05). SGB significantly improved lung function parameters, with the OVA + SGB6 group showing the most pronounced improvement (P < 0.05). The Tm group displayed elevated Rrs compared to Control (P < 0.05), while the OVA + 4PBA group demonstrated significant improvement in Rrs (P < 0.05). The Tm + SGB6 group also showed significant improvement in Rrs compared to the Tm group (P < 0.05). The expression of IRE1β-IKK/NF-κB genes was upregulated in the OVA group and downregulated in the OVA + SGB6 group. Furthermore, ER stress inhibitors reduced the expression of these key genes in OVA-induced AHR. Notably, the expression of ER stress-related genes was elevated in the OVA group, with a significant decrease in Agr2 (a promoter of ER stress IRE1β) observed in the OVA + SGB6 group compared to the OVA group (114 vs. 16).

CONCLUSION

SGB effectively reduced AHR while down-regulating the expression of key genes in the IKK/NF-κB/IL-4/IL-5/IL-13 signaling pathway, which may be related to IRE1β-mediated endoplasmic reticulum stress. However, further studies are needed to confirm the exact mechanism.

The Predictive Value of Baseline Spirometry, Age, and Gender for Airway Hyper-Responsiveness in Adults With Suspected Asthma

Background: Bronchial provocation test (BPT) plays a crucial role in diagnosing airway hyper-responsiveness (AHR) among patients with asthma-like symptoms. Given that BPT may induce severe bronchospasm, baseline spirometric parameters are expected to help predict a positive outcome, guiding the decision of referring a patient to BPT. Methods: Baseline spirometry and BPT conducted on suspected asthmatics between July 2011 and 2013 at Department of Pulmonary Medicine, Zhongshan Hospital, were retrospectively collected. Baseline characteristics from positive and negative BPT groups were compared. The predictive accuracy of single parameter for AHR was evaluated by plotting receiver operating characteristic curve, and a composite model was developed to improve the accuracy by the logistic regression. The relationships of FEV1/FVC, FEV1 %predicted, and forced expiratory flow at 50% of FVC exhaled (FEF50 %predicted) with the provocation dose causing a 20% fall in FEV1 (PD20-FEV1) were examined. Results: The positive BPT group exhibited reduced FEV1 %predicted, FEV1/FVC, and small airway function parameters compared with the negative group. Among these parameters, FEF50 %predicted, forced expiratory flow at 75% of FVC exhaled (FEF75 %predicted), and forced expiratory flow between 25% and 75% (FEF25-75 %predicted) demonstrated significant accuracy. Notably, females and younger subjects were more prone to a positive outcome. A predictive model that combined FEV1 %predicted (cutoff 98.65%, area under the curve 0.714, sensitivity 39.10%, specificity 88.10%), FEV1/FVC (cutoff 79.22%, area under the curve 0.690, sensitivity 32.80%, specificity 90.50%), and FEF50 %predicted (cutoff 74.45%, area under the curve 0.761, sensitivity 50.50%, specificity 84.60%) with age and gender was found to enhance the accuracy for a positive BPT (area under the curve 0.786, 95% CI 0.758-0.814, sensitivity 52.27%, specificity 86.14%). Moreover, FEV1/FVC, FEF50 %predicted, and FEF25-75 %predicted showed differences among groups with varying AHR levels. The significant correlations between these 3 parameters and PD20-FEV1 were exclusively demonstrated in the severe AHR group. Conclusions: This study revealed that FEV1 %predicted, FEV1/FVC, and FEF50 %predicted along with age and gender were predictors of AHR in subjects with suspected asthma. Their combination improved the predictive accuracy over using FEF50 %predicted alone, thus offering a complement for clinical decision-making regarding referrals to BPT.

The Link Between Dysbiosis, Inflammation, Oxidative Stress, and Asthma-The Role of Probiotics, Prebiotics, and Antioxidants

Background: Asthma (a chronic inflammatory disease of the airways) is characterized by a variable course, response to treatment, and prognosis. Its incidence has increased significantly in recent decades. Unfortunately, modern lifestyle and environmental factors contribute to the further increase in the incidence of this disease. Progressive industrialization and urbanization, widespread use of antibiotic therapy, excessive sterility and inappropriate, highly processed diets are some of the many risk factors that are relevant today. Over the years, a lot of evidence has been gathered showing the influence of microorganisms of the gut or airways on human health. Studies published in recent years indicate that dysbiosis (microbial imbalance) and oxidative stress (pro-oxidant-antioxidant imbalance) are important elements of the pathogenesis of this inflammatory disease. Scientists have attempted to counteract the effects of this process by using probiotics, prebiotics, and antioxidants. The use of probiotic microorganisms positively modulates the immune system by maintaining homeostasis between individual fractions of immune system cells. Moreover, recently conducted experiments have shown that probiotics have antioxidant, anti-inflammatory, and protective properties in oxidative stress (OS). The aim of this study is to present the current state of knowledge on the role of dysbiosis and OS in the pathogenesis of asthma. Conclusions: This review highlights the importance of using probiotics, prebiotics, and antioxidants as potential strategies to support the treatment and prevention of this disease.

LY333531 attenuates contraction of tumor necrosis factor-α-sensitized human airway smooth muscle cells

OBJECTIVE

Protein kinase C (PKC) has been implicated in the increased contraction of human airway smooth muscle cells (HASMCs) in asthma. Using the three-dimensional collagen gel contraction system, the study aimed to determine the effects of LY333531, a specific inhibitor of the PKC-β isoform, on the contraction of tumor necrosis factor (TNF)-α-sensitized HASMCs.

METHODS

Cultured HASMCs were divided into five groups: the control group received no treatment, and the cells in the TNF-α group were sensitized with 10 ng/mL TNF-α for 48 h, while TNF-α was administered to sensitize HASMCs in the presence of 0.1, 0.2, and 0.5 μM LY333531 for 48 h in the 0.1LY, 0.2LY, and 0.5LY groups, respectively. Following this, HASMCs contraction was stimulated with 1 mM acetylcholine (ACh) for up to 24 h in each group and assessed using a three-dimensional collagen gel contraction assay. Furthermore, western blot and immunofluorescence analysis were performed.

RESULTS

The collagen gel contraction assay revealed that TNF-α increased the protein expression of phosphorylated PKC-β2, CPI-17, and MLC while exacerbating ACh-induced HASMCs contraction. LY333531 significantly attenuated HASMCs contraction and downregulated the protein expression of both p-CPI-17 and p-MLC.

CONCLUSIONS

At least in part by regulating CPI-17 and MLC phosphorylation, LY333531 attenuates augmented contraction of TNF-α-sensitized HASMCs in a collagen gel contraction system.

Melatonin prevents histopathologies stem from cadmium chloride in pregnant mice lungs

Heavy metals may cause structural and functional changes in organs. Cadmium, taken into the body through oral and respiratory routes, can lead to lesions. Cadmium may lead to lesions by accumulating in organs. The lungs are significantly affected by cadmium. Melatonin, an antioxidant hormone with therapeutic effects, is secreted by the pineal gland. The aim of the study is to treat cadmium-induced lesions in the lungs of pregnant mice with Melatonin. Four groups were created with 24 pregnant mice, named Control, Cadmium Chloride, Melatonin, and Melatonin + Cadmium Chloride groups (n: 6) Cadmium Chloride (2 mg/kg/bw) and Melatonin (3 mg/kg/bw) were given orally through gavage during pregnancy (21 days) After routine histological procedures, the lung tissues were stained with Hematoxylin-Eosin and evaluated under a light and electron microscope. ANOVA tests were applied for one-way analysis of variance, and LSD tests were applied for pairwise comparisons (p < 0.05) The average lung weight decreased in the Cadmium Chloride group (p: 0.03) The average lung weight in the Cadmium Chloride + Melatonin group was found to be close to the control group (p: 0.06) Cadmium Chloride caused thickening of the lung alveolar wall, inflammatory cell infiltration, and fibrin deposition. Because the lesions were not observed in the Melatonin group, lesions may be prevented by melatonin. Additional studies may be useful to determine the protective effect of Melatonin at different doses of Cadmium Chloride.

Impact of the pulmonary ventilation function on the prognosis of suspected asthma patients: a retrospective observational study

OBJECTIVE

Asthma is a common chronic respiratory diseases, and the relationship between pulmonary ventilation function and the prognosis of patients with suspected asthma is not well understood. This study aims to explore the impact of pulmonary ventilation functions on the prognosis of patients with suspected asthma.

METHODS

This retrospective observational study included patients with suspected asthma who were diagnosed and treated at the Guangdong Provincial Hospital of Traditional Chinese Medicine between August 2015 and January 2020. The primary outcome of interest was improvement in asthma symptoms, as measured by bronchial provocation test (BPT) results within one year after diagnosis. The impact of pulmonary ventilation functions on prognosis was explored by multivariable logistic regression analysis.

RESULTS

Seventy-two patients were included in the study. Patients with normal (OR = 0.123, p = .004) or generally normal (OR = 0.075, p = .039) pulmonary ventilation function were more likely to achieve improvement in asthma symptoms compared with patients with mild obstruction. There were no significant differences between the improvement and non-improvement groups in baseline characteristics.

CONCLUSION

These results suggest that suspected asthma patients with normal or generally normal pulmonary ventilation function are more likely to achieve improvement in asthma symptoms within one year compared to patients with mild obstruction.

Airway hyperresponsiveness in asthma: The role of the epithelium

Airway hyperresponsiveness (AHR) is a key clinical feature of asthma. The presence of AHR in people with asthma provides the substrate for bronchoconstriction in response to numerous diverse stimuli, contributing to airflow limitation and symptoms including breathlessness, wheeze, and chest tightness. Dysfunctional airway smooth muscle significantly contributes to AHR and is displayed as increased sensitivity to direct pharmacologic bronchoconstrictor stimuli, such as inhaled histamine and methacholine (direct AHR), or to endogenous mediators released by activated airway cells such as mast cells (indirect AHR). Research in in vivo human models has shown that the disrupted airway epithelium plays an important role in driving inflammation that mediates indirect AHR in asthma through the release of cytokines such as thymic stromal lymphopoietin and IL-33. These cytokines upregulate type 2 cytokines promoting airway eosinophilia and induce the release of bronchoconstrictor mediators from mast cells such as histamine, prostaglandin D2, and cysteinyl leukotrienes. While bronchoconstriction is largely due to airway smooth muscle contraction, airway structural changes known as remodeling, likely mediated in part by epithelial-derived mediators, also lead to airflow obstruction and may enhance AHR. In this review, we outline the current knowledge of the role of the airway epithelium in AHR in asthma and its implications on the wider disease. Increased understanding of airway epithelial biology may contribute to better treatment options, particularly in precision medicine.

Exposure frequency, intensity, and duration: What we know about work-related asthma risks for healthcare workers from cleaning and disinfection

The objective of this review was to scope the current evidence base related to three exposure assessment concepts: frequency, intensity, and duration (latency) for cleaning and disinfection exposures in healthcare and subsequent work-related asthma risks. A search strategy was developed addressing intersections of four main concepts: (1) work-related asthma; (2) occupation (healthcare workers/nurses); (3) cleaning and disinfection; and (4) exposure. Three databases were searched: Embase, PubMed, and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) database. Data were extracted related to three main components of risk assessment: (1) exposure frequency, (2) exposure intensity, and (3) exposure duration. Latency data were analyzed using an exponential distribution fit, and extracted concentration data were compared to occupational exposure limits. The final number of included sources from which data were extracted was 133. Latency periods for occupational asthma were exponentially distributed, with a mean waiting time (1/λ) of 4.55 years. No extracted concentration data were above OELs except for some formaldehyde and glutaraldehyde concentrations. Data from included sources also indicated some evidence for a dose-response relationship regarding increased frequency yielding increased risk, but this relationship is unclear due to potential confounders (differences in role/task and associated exposure) and the healthy worker effect. Data priority needs to include linking concentration data to health outcomes, as most current literature does not include both types of measurements in a single study, leading to uncertainty in dose-response relationships.

The Role of Vitamins in the Pathogenesis of Asthma

Vitamins play a crucial role in the proper functioning of organisms. Disturbances of their levels, seen as deficiency or excess, enhance the development of various diseases, including those of the cardiovascular, immune, or respiratory systems. The present paper aims to summarize the role of vitamins in one of the most common diseases of the respiratory system, asthma. This narrative review describes the influence of vitamins on asthma and its main symptoms such as bronchial hyperreactivity, airway inflammation, oxidative stress, and airway remodeling, as well as the correlation between vitamin intake and levels and the risk of asthma in both pre- and postnatal life.

Does peak expiratory flow moderate trajectories of cognitive function among individuals with lung diseases? A longitudinal analysis of the National Health and Aging Trends Study

INTRODUCTION

Impaired cognitive function can co-exist in chronic respiratory diseases. However, it is not clear if peak expiratory flow (PEF) impacts changes in cognitive function. Our objective was to explore whether peak expiratory flow moderates trajectories of memory, visuospatial abilities, and executive function in individuals with chronic respiratory diseases.

METHODS

This was an analysis of individuals with lung diseases from the National Health and Aging Trends Study. Multivariable-adjusted generalized linear mixed models were used to estimate trajectories of immediate and delayed recall, and clock drawing over a 10-year follow-up. The interaction between PEF and time were plotted using sex-specific values for peak expiratory flow at 10th, 50th and 90th percentiles.

RESULTS

In females, interactions of time-by-PEF were found for both immediate (n = 489, t = 2.73, p<0.01) and delayed recall (n = 489, t = 3.38, p<0.01). Females in the 10th vs. 90th percentile of PEF declined in immediate recall at 0.14 vs. 0.065 words/year, and 0.17 vs. 0.032 words/year for delayed recall. Among males, recall declined linearly over 10 years (immediate recall: n = 296, t = -3.08, p < 0.01; delayed recall: n = 292, t = -2.46, p = 0.02), with no interaction with PEF. There were no time-by-PEF interactions nor declines over time in clock drawing scores in both sexes (females: n = 484, t = 0.25, p = 0.81; males: n = 291, t = -0.61, p = 0.55).

CONCLUSION

Females with the lowest PEF values experienced the greatest rates of decline in immediate and delayed recall over 10 years of follow-up, whereas males experienced similar declines in memory outcomes across all levels of PEF. Clock drawing scores remained stable over 10 years in both sexes.

Exercise in bushfire smoke for high performance athletes: A Position Statement from the Australian Institute of SportEndorsed by Australasian College of Sport and Exercise Physicians (ACSEP) and Sport Medicine Australia (SMA)

OBJECTIVES

The frequency of bushfires in Australia is increasing and it is expected bushfire smoke will become a more prevalent phenomenon impacting air quality. The objective of this position statement is to provide guidance to the sport sector regarding exercise in air affected by bushfire smoke.

DESIGN

This is position statement from the Australian Institute of Sport, based on a narrative review of the literature regarding bushfire smoke and its effects on health and exercise performance.

METHODS

A narrative review of scientific publications regarding the effects of bushfire smoke on health and exercise performance.

RESULTS

Bushfire smoke has negative impacts on health and performance. Athletes exercising at high intensity over a prolonged duration will increase their exposure to air pollutants. Athletes with a history of elevated airway responsiveness are likely to be at increased risk of an adverse response to bushfire smoke exposure.

CONCLUSIONS

Athletes, coaches, support staff and sport organisations should monitor air quality (PM2.5 concentration) and make appropriate adjustments to training duration and intensity.

Airway smooth muscle in contractility and remodeling of asthma: potential drug target mechanisms

INTRODUCTION

Asthma is characterized by enhanced airway contractility and remodeling where airway smooth muscle (ASM) plays a key role, modulated by inflammation. Understanding the mechanisms by which ASM contributes to these features of asthma is essential for the development of novel asthma therapies.

AREAS COVERED

Inflammation in asthma contributes to a multitude of changes within ASM including enhanced airway contractility, proliferation, and fibrosis. Altered intracellular calcium ([Ca²⁺]_i) regulation or Ca²⁺ sensitization contributes to airway hyperreactivity. Increased airway wall thickness from ASM proliferation and fibrosis contributes to structural changes seen with asthma.

EXPERT OPINION

ASM plays a significant role in multiple features of asthma. Increased ASM contractility contributes to hyperresponsiveness, while altered ASM proliferation and extracellular matrix production promote airway remodeling both influenced by inflammation of asthma and conversely even influencing the local inflammatory milieu. While standard therapies such as corticosteroids or biologics target inflammation, cytokines, or their receptors to alleviate asthma symptoms, these approaches do not address the underlying contribution of ASM to hyperresponsiveness and particularly remodeling. Therefore, novel therapies for asthma need to target abnormal contractility mechanisms in ASM and/or the contribution of ASM to remodeling, particularly in asthmatics resistant to current therapies.

Pyroptosis and respiratory diseases: A review of current knowledge

Pyroptosis is a relatively newly discovered programmed cell death accompanied by an inflammatory response. In the classical view, pyroptosis is mediated by caspases-1,-4,-5,-11 and executed by GSDMD, however, recently it was demonstrated that caspase-3 and-8 also participate in the process of pyroptosis, by cleaving GSDMD/E and GSDMD respectively. Different from autophagy and apoptosis, many pores are formed on the cell membrane during pyroptosis, which makes the cell membrane lose its integrity, eventually leading to the release of cytokines interleukin(IL)-1β and IL-18. When the body is infected with pathogens or exposed to some stimulations, pyroptosis could play an immune defense role. It is found that pyroptosis exists widely in infectious and inflammatory respiratory diseases such as acute lung injury, bronchial dysplasia, chronic obstructive pulmonary disease, and asthma. Excessive pyroptosis may accompany airway inflammation, tissue injury, and airway damage, and induce an inflammatory reaction, leading to more serious damage and poor prognosis of respiratory diseases. This review summarizes the relationship between pyroptosis and related respiratory diseases.

Cigarette Smoke Particle-Induced Lung Injury and Iron Homeostasis

It is proposed that the mechanistic basis for non-neoplastic lung injury with cigarette smoking is a disruption of iron homeostasis in cells after exposure to cigarette smoke particle (CSP). Following the complexation and sequestration of intracellular iron by CSP, the host response (eg, inflammation, mucus production, and fibrosis) attempts to reverse a functional metal deficiency. Clinical manifestations of this response can present as respiratory bronchiolitis, desquamative interstitial pneumonitis, pulmonary Langerhans’ cell histiocytosis, asthma, pulmonary hypertension, chronic bronchitis, and pulmonary fibrosis. If the response is unsuccessful, the functional deficiency of iron progresses to irreversible cell death evident in emphysema and bronchiectasis. The subsequent clinical and pathological presentation is a continuum of lung injuries, which overlap and coexist with one another. Designating these non-neoplastic lung injuries after smoking as distinct disease processes fails to recognize shared relationships to each other and ultimately to CSP, as well as the common mechanistic pathway (ie, disruption of iron homeostasis).

Baseline spirometry parameters as predictors of airway hyperreactivity in adults with suspected asthma

BACKGROUND

Methacholine challenge tests (MCTs) are used to diagnose airway hyperresponsiveness (AHR) in patients with suspected asthma where previous diagnostic testing has been inconclusive. The test is time consuming and usually requires referral to specialized centers. Simple methods to predict AHR could help determine which patients should be referred to MCTs, thus avoiding unnecessary testing. Here we investigated the potential use of baseline spirometry variables as surrogate markers for AHR in adults with suspected asthma.

METHODS

Baseline spirometry and MCTs performed between 2013 and 2019 in a large tertiary center were retrospectively evaluated. Receiver-operating characteristic curves for the maximal expiratory flow-volume curve indices (angle β, FEV1, FVC, FEV1/FVC, FEF_50%, FEF_25-75%) were constructed to assess their overall accuracy in predicting AHR and optimal cutoff values were identified.

RESULTS

A total of 2983 tests were analyzed in adults aged 18-40 years. In total, 14% of all MCTs were positive (PC20 ≤ 16 mg/ml). All baseline spirometry parameters were significantly lower in the positive group (p < 0.001). FEF_50% showed the best overall accuracy (AUC = 0.688) and proved to be useful as a negative predictor when applying FEF_50% ≥ 110% as a cutoff level.

CONCLUSIONS

This study highlights the role of FEF_50% in predicting AHR in patients with suspected asthma. A value of ≥ 110% for baseline FEF_50% could be used to exclude AHR and would lead to a substantial decrease in MCT referrals.

Novel formulations and drug delivery systems to administer biological solids

Recent advances in formulation sciences have expanded the previously limited design space for biological modalities, including peptide, protein, and vaccine products. At the same time, the discovery and application of new modalities, such as cellular therapies and gene therapies, have presented formidable challenges to formulation scientists. We explore these challenges and highlight the opportunities to overcome them through the development of novel formulations and drug delivery systems as biological solids. We review the current progress in both industry and academic laboratories, and we provide expert perspectives in those settings. Formulation scientists have made a tremendous effort to accommodate the needs of these novel delivery routes. These include stability-preserving formulations and dehydration processes as well as dosing regimes and dosage forms that improve patient compliance.

A systematic review and meta-analysis on the effectiveness of swimming on lung function and asthma control in children with asthma

BACKGROUND

Swimming has been considered the most appropriate activity for children with asthma for its lower asthmogenicity compared to land-based activities. However, the benefits of swimming have been hampered by reports of increased asthma risks, airway inflammation and bronchial hyper-responsiveness from exposure to chlorine by-products in swimming pools. Thus, the role of swimming for children with asthma remains unclear.

OBJECTIVES

To determine the effectiveness of swimming as an intervention on lung function and asthma control in children below the age of 18 years. Any adverse effects from swimming on asthma were also examined.

METHODS

Searches were performed across six databases systematically (PubMed, CINAHL, Embase, CENTRAL, Scopus, and PsycINFO). Randomized controlled trials (RCTs), quasi-experimental studies and interventional studies with at least one control/comparator group that were published in English were included. All eligible studies were screened with risk of bias examined by two independent reviewers. Meta-analyses were conducted using Review Manager 5.4 software while narrative syntheses were performed where meta-analysis was inappropriate and heterogeneity was present.

RESULTS

1710 records were retrieved from the search. A total of 9 studies with 387 participants were included in this review after screening. Swimming was found to have favourable effects on forced expiratory volume in one second (L) and forced vital capacity (%), but not for forced expiratory volume in one second (%) and peak expiratory flow (%). Narrative synthesis on asthma control and adverse effects were in favour of the swimming group.

CONCLUSION

Future studies that are adequately powered, involve swimming interventions of sufficient intensity, frequency and duration, examine cumulative exposures to chlorine by-products and take into account potential cofounders are warranted.

Longitudinal predictors of bronchial hyperresponsiveness and FEV1 decline in bakers

OBJECTIVE

To determine long-term predictors of bronchial hyperresponsiveness (BHR) and forced expiratory volume in one second (FEV₁) decline.

METHODS

A longitudinal study in 110 bakers in 4 industrial bakeries and 38 non-exposed workers was conducted at the workplace with a mean of 3.3 visits per subject over a period of 13 years and a mean duration of follow-up of 6 years in bakers and 8 years in non-exposed subjects. A respiratory health questionnaire was administered; occupational allergen skin prick tests, spirometry and a methacholine bronchial challenge test were performed at each visit. In each bakery, full-shift dust samples of the inhalable fraction were obtained in order to assess the exposure of each job assignment. The repeated measurements of BHR and FEV₁ were analyzed using mixed effects logistic and linear regression models in subjects seen at least twice.

RESULTS

BHR, respiratory symptoms and their simultaneous occurrence depended on the duration of exposure. FEV₁ significantly decreased with duration of exposure and BHR at a preceding visit. This result persisted when adjusting for the effect of BHR at the current visit. The measured exposure levels were not a significant predictor for any outcome. Occupational sensitization was only a predictor of a decline in FEV₁ when duration of exposure was not included.

CONCLUSION

In flour-exposed industrial bakers, length of exposure and smoking are long-term determinants of BHR and of the decrease in FEV₁. BHR at a preceding visit predicted lower FEV₁ even when accounting for the effect of BHR at the current visit.

The use of a direct bronchial challenge test in primary care to diagnose asthma

Many asthmatics in primary care have mild symptoms and lack airflow obstruction. If variable expiratory airflow limitation cannot be determined by spirometry or peak expiratory flow, despite a history of respiratory symptoms, a positive bronchial challenge test (BCT) can confirm the diagnosis of asthma. However, BCT is traditionally performed in secondary care. In this observational real-life study, we retrospectively analyze 5-year data of a primary care diagnostic center carrying out BCT by histamine provocation. In total, 998 primary care patients aged ≥16 years underwent BCT, without any adverse events reported. To explore diagnostic accuracy, we examine 584 patients with a high pretest probability of asthma. Fifty-seven percent of these patients have a positive BCT result and can be accurately diagnosed with asthma. Our real-life data show BCT is safe and feasible in a suitably equipped primary care diagnostic center. Furthermore, it could potentially reduce diagnostic referrals to secondary care.

Characterization of Persistent Uncontrolled Asthma Symptoms in Community Members Exposed to World Trade Center Dust and Fumes

The destruction of the World Trade Center (WTC) towers on the 11th of September, 2001 released a vast amount of aerosolized dust and smoke resulting in acute and chronic exposures to community members as well as responders. The WTC Environmental Health Center (WTC EHC) is a surveillance and treatment program for a diverse population of community members, including local residents and local workers with WTC dust exposure. Many of these patients have reported persistent lower respiratory symptoms (LRS) despite treatment for presumed asthma. Our goal was to identify conditions associated with persistent uncontrolled LRS despite standard asthma management. We recruited 60 patients who were uncontrolled at enrollment and, after a three-month run-in period on high-dose inhaled corticosteroid and long acting bronchodilator, reassessed their status as Uncontrolled or Controlled based on a score from the Asthma Control Test (ACT). Despite this treatment, only 11 participants (18%) gained Controlled status as defined by the ACT. We compared conditions associated with Uncontrolled and Controlled status. Those with Uncontrolled symptoms had higher rates of upper airway symptoms. Many patients had persistent bronchial hyper-reactivity (BHR) and upper airway hyper-reactivity as measured by paradoxical vocal fold movement (PVFM). We found a significant increasing trend in the percentage of Controlled with respect to the presence of BHR and PVFM. We were unable to identify significant differences in lung function or inflammatory markers in this small group. Our findings suggest persistent upper and lower airway hyper-reactivity that may respond to standard asthma treatment, whereas others with persistent LRS necessitate additional diagnostic evaluation, including a focus on the upper airway.

Predictive value of non-specific bronchial challenge testing for respiratory symptoms and lung function in aluminium smelter workers

OBJECTIVE

To assess the predictive value of bronchial hyper-responsiveness (BHR) for the subsequent development of respiratory symptoms, airflow limitation and decline in lung function among aluminium smelter workers.

METHODS

An inception cohort study of new employees at two Australian aluminium smelters was conducted. Participants completed a modified British Medical Research Council respiratory questionnaire, spirometry and a methacholine bronchial challenge test at baseline and at annual follow-up reviews. BHR was defined as PD₂₀ ≤4000 µg. Poisson and mixed effects models were fitted to respiratory symptoms and lung function (forced expiratory volume in 1 s (FEV₁) and FEV₁/forced vital capacity (FVC)).

RESULTS

Baseline interview and lung function testing were completed by 278 workers, who were followed for a median of 4 years. BHR at baseline, present in 82 workers, was not associated with incident wheeze risk ratio (RR)=1.07 (95% CI 0.74 to 1.55) and cough RR=0.78 (95% CI 0.45, 1.35), but there was some increased risk of chest tightness RR=1.40 (95% CI 0.99, 1.98) after adjustment for age, sex, smoking and atopy. BHR at baseline was associated with lower FEV₁ and FVC, although the rate of annual decline in FEV₁ or FVC was similar between those with or without BHR. The specificity of BHR was 77% for wheeze, 70% for cough and 77% for chest tightness, but the sensitivity was poor, at 33%, 24% and 39%, respectively.

CONCLUSION

Methacholine challenge testing at entry to employment was not sufficiently predictive of later adverse respiratory outcomes, and notwithstanding the study limitations is unlikely to be a useful pre-employment or preplacement screening test in the aluminium smelting industry.

Bronchial hyper-responsiveness: a technical update

Background

Bronchial hyper-responsiveness (BHR) is often regarded as a 'hallmark' of asthma, and bronchoprovocation testing is frequently performed to support a diagnosis of asthma. The European Respiratory Society (ERS) and American Thoracic Society (ATS) have recently updated their technical standards and guidelines for performing methacholine challenge testing (MCT), the most commonly performed clinical test of BHR.

Aims

To review the updated guidelines and discuss the various changes and their potential impact on clinicians.

Methods

We performed a systematic review of references identified using Medline and hand searches of identified articles.

Results

The new ERS and ATS guidelines recommend that MCT be performed using tidal breathing, not deep inspirations with breath holding, that results be reported as the PD20 (cumulative dose causing a 20% fall in forced expiratory volume in 1 s [FEV1]), rather than PC20 (concentration causing a 20% fall in FEV1), and that manufacturers of nebulizers and other delivery systems provide performance characteristics to allow calculation of PD20 values. Our preliminary survey found that the new guidelines are only slowly being adopted.

Conclusions

Clinicians should be aware that recommended BHR testing methods, particularly for MCT, have changed. As a result, they should anticipate that test outcomes will increasingly be reported in terms of PD20, which will facilitate longitudinal assessment of their patients. Compliance with the new guidelines will increase the sensitivity of MCT in mild and asymptomatic asthmatics.

Asthma in the Primary Care Setting

Asthma is one of the commonest respiratory diseases in the United States, affecting approximately 8% of adults. This article reviews the epidemiology, diagnosis, and treatment of asthma, with integration of recommendations from professional societies, with special attention to differential diagnosis. A framework for outpatient management of patients with asthma is presented, including indications for subspecialist referral. With integration of objective diagnostic information, systematic approach through modification of disease triggers and adjustment of controller medications, and patient empowerment to respond to varying symptoms using an asthma action plan, most individuals with asthma are successfully managed in the primary care setting.

Time to onset of improvements in Quality of Life from Temperature-controlled Laminar Airflow (TLA) in severe allergic asthma

BACKGROUND

Allergen avoidance is important in allergic asthma management. Nocturnal treatment with Temperature-controlled Laminar Airflow (TLA; Airsonett^®) has been shown to provide significant reduction of exposure to allergens in the breathing zone, leading to long-term reduction in airway inflammation and improvement in quality of life. Allergic asthma patients uncontrolled on GINA step 4 were found to benefit the most. A frequently asked question from clinicians and funders is related to time to onset (TTO) of improvements for patients using TLA.

METHODS

Asthma Quality of Life Questionnaire (AQLQ) scores were collected in a previous study. TTO of improvements in Quality of Life was analysed for difference (TLA-placebo) in Area-under-Curve using backwards deletion from 12, 9, 6, 3 down to 1 month for the AQLQ total score, the four individual domains and specifically the sleep question.

RESULTS

Patients with uncontrolled asthma on GINA step 4 (n = 87)) reported a statistically significant and clinically relevant (≥0.5 point) improvement in total AQLQ score (0.57; p = 0.009) after 3 months treatment for TLA over placebo. The shortest TTO was within 1 month for the environmental domain (0.68; p = 0.016) and the sleep question (0.771; p = 0.037). TTO for the emotional and symptom domains was 3 months (0.66; p = 0.020 and 0.64; p = 0.014 respectively) and for the activity domain 6 months (0.47; p = 0.036).

CONCLUSION

Nocturnal avoidance of allergens using TLA provided a statistically significant and clinically relevant improvement in total AQLQ score within 3 months in patients in the GINA 4 + ACT<18 group. Questions related to sleep quality may provide the first signal of response already within a month after commencing treatment.

Impact of allergen immunotherapy in allergic asthma

Although traditional pharmacological approaches improve outcomes in disease management for allergic asthma, these fail to modify the underlying immune responses. Allergen immunotherapy remains the only etiological therapy for the treatment of respiratory allergies for which clinical efficacy has been demonstrated through several well-controlled studies. In this review, we examine evidence from the past 5 years regarding the impact of allergen immunotherapy on allergic asthma to inform practitioners and stimulate further discussion and research.

Can the ceramic industry be a new and hazardous sector for work-related asthma?

BACKGROUND

Work-related asthma (WRA) constitutes a significant proportion of all asthma cases and continues to be reported from different industries. The aim of the study was to identify the occupations that can be related to WRA and diagnostic steps used in suspected WRA patients.

METHODS

We retrospectively reviewed the clinical records of WRA suspected patients who were referred to Ankara Occupational and Environmental Diseases Hospital, Turkey from January 2015 to January 2017. Detailed occupational history, the diagnostic steps such as pulmonary function testing (PFT), peak expiratory flow (PEF) monitoring and nonspecific bronchial provocation tests (NSBPT) were recorded.

RESULTS

Among 160 patients, 148 were male and 12 were female. Only 2 of them were diagnosed as work-exacerbated asthma (WEA). Diagnosis of asthma was based on using reversible airflow limitation 28.8% (n = 46) or NSBPT 31.9% (n = 51). Toxicological analysis showed that 28 patients had heavy metal poisoning, 9 patients had solvent poisoning, 4 patients had both. According to occupations, 32 of them were ceramic workers (20.0%) and 27 of them were metal workers (16.9%). Plastic workers (4 ± 2.8 years), cleaners (6.2 ± 5.7 years), metal workers (7.4 ± 5.4 years), painters (10 ± 5.2 years), ceramic workers (10.8 ± 5.9 years) had the shortest exposure durations for development of occupational asthma (OA). An analysis of variance showed that the effect of heavy metal and solvent poisoning on mean time for onset of OA was not significant.

CONCLUSIONS

The results demonstrate that besides the sectors known to cause WRA, ceramic and metal industries can be related to important exposures related to WRA. Medical surveillance of employees in this sector is important in early detection.

Roles of Bronchopulmonary C-fibers in airway Hyperresponsiveness and airway remodeling induced by house dust mite

Background

Asthma is characterized by chronic airway inflammation, airway hyperresponsiveness (AHR), and airway remodeling. While exposure of house dust mites (HDM) is a common cause of asthma, the pathogenesis of the HDM-induced asthma is not fully understood. Bronchopulmonary C-fibers (PCFs) contribute to the neurogenic inflammation, viral infection induced-persistent AHR, and ovalbumin induced collagen deposition largely via releasing neuropeptides, such as substance P (SP). However, PCF roles in the pathogenesis of the HDM-induced asthma remain unexplored. The goal of this study was to determine what role PCFs played in generating these characteristics.

Methods

We compared the following variables among the PCF-intact and -degenerated BALB/c mice with and without chronic HDM exposure (four groups): 1) AHR and pulmonary SP; 2) airway smooth muscle (ASM) mass; 3) pulmonary inflammatory cells; and 4) epithelium thickening and mucus secretion.

Results

We found that HDM evoked AHR associated with upregulation of pulmonary SP and inflammation, ASM mass increase, epithelium thickenings, and mucus hypersecretion. PCF degeneration decreased the HDM-induced changes in AHR, pulmonary SP and inflammation, and ASM mass, but failed to significantly affect the epithelium thickening and mucus hypersecretion.

Conclusion

Our data suggest an involvement of PCFs in the mechanisms by which HDM induces allergic asthma via airway inflammation, AHR, and airway remodeling.

Overweight in childhood and adolescence: Does it lead to airway hyperresponsiveness in adulthood?

BACKGROUND

Obesity is increasing worldwide among children and adolescents, and has been associated with an increased incidence of asthma. However, the mechanisms underlying this association are incompletely understood.

OBJECTIVE

In this cohort study we aimed to investigate whether being overweight in childhood and adolescence is associated with an increased risk of airway hyperresponsiveness (AHR), a hallmark of asthma, in early adulthood.

METHODS

Of 527 subjects from a random population sample of children and adolescents (7-17 years) examined at baseline, a total of 184 subjects completed the follow-up visit 20 years later and were included in the present analysis. Both visits included assessment of height and weight, case history and spirometry. At both visits, bronchial provocation tests were performed using either histamine (baseline) or methacholine (follow-up). In addition, fractional exhaled nitric oxide (FeNO) was measured at follow-up.

RESULTS

No significant difference in the prevalence of AHR at follow-up was found between subjects who were overweight or obese at baseline visit (n = 26) (pediatric definition, body mass index ≥ 85%percentile) and normal weight subjects (n = 158) (positive bronchial provocation tests: 15.4% vs. 22.2%, respectively, p = 0.35). Likewise, follow-up FeNO levels did not differ significantly between subjects who were lean and those who were overweight or obese at baseline (geometric mean (95% confidence interval [CI]) 15.1 (13.7, 16.6) parts per billion (ppb) versus 13.0 (10.6, 15.9) ppb, p = 0.23).

CONCLUSION

In children and adolescents, being obese or overweight seems not to be associated with an increased risk of AHR or increased FeNO levels in early adulthood.

Does the medical diagnosis of occupational asthma coincide with the legal diagnosis?

OBJECTIVE

The incidence of occupational asthma (OA) is increasing worldwide. In this study, we first aimed to document the rate of diagnosis of OA among patients who were referred to our clinic from the Social Security Institution and the factors that affected diagnosis; secondly, we aimed to assess the consistency of the medical and legal diagnoses.

METHODS

The study involved 132 consecutive patients who were referred to our clinic for the evaluation of OA between 2010 and 2015. Detailed workplace history, the tools used in the diagnosis such as peak expiratory flow (PEF) monitoring and bronchial provocation tests, and the final medical diagnosis were recorded from case files.

RESULTS

Asthma was diagnosed in 75% (n = 99) of the patients. Among them, 22.2% were diagnosed as having OA. The diagnosis was confirmed by serial PEF measurements, non-specific bronchial hyperreactivity assessment or both of the tests both at work and off-work periods. OA diagnosis was mostly established in active workers (72.7%). The legal diagnosis period was completed in 54.5% of these 22 patients, and 50% (n = 11) were officially diagnosed as having OA with a 91.6% concordance with medical diagnosis.

CONCLUSION

This study verifies the importance of diagnosing asthma correctly as a first step in the evaluation of OA. Diagnostic tests other than specific provocation tests could be preferential in patients who still work in the same field. We believe that cooperation with the patient's occupational physician and adequate recognition of the work environment will improve the consistency of legal and medical diagnoses.

Modeling long-term effects attributed to nitrogen dioxide (NO2) and sulfur dioxide (SO2) exposure on asthma morbidity in a nationwide cohort in Israel

Studies have provided extensive documentation that acutely elevated environmental exposures contribute to chronic health problems. However, only attention has been paid to the effects of modificate of exposure assessment methods in environmental health investigations, leading to uncertainty and gaps in our understanding of exposure- and dose-response relationships. The goal of the present study was to evaluate whether average or peak concentration exerts a greater influence on asthma outcome, and which of the exposure models may better explain various physiological responses generated by nitrogen dioxide (NO₂) or sulfur dioxide (SO₂) air pollutants. The effects of annual NO₂ and SO₂ exposures on asthma prevalence were determined in 137,040 17-year-old males in Israel, who underwent standard health examinations before induction to military service during 1999-2008. Three alternative models of cumulative exposure were used: arithmetic mean level (AM), average peak concentration (APC), and total number of air pollution exposure episodes (NEP). Air pollution data for NO₂ and SO₂ levels were linked to the residence of each subject and asthma prevalence was predicted using bivariate logistic regression. There was significant increased risk for asthma occurrence attributed to NO₂ exposure in all models with the highest correlations demonstrated using the APC model. Data suggested that exposure-response is better correlated with NO₂ peak concentration than with average exposure concentration in subjects with asthma. For SO₂, there was a weaker but still significant exposure response association in all models. These differences may be related to differences in physiological responses including effects on different regions of the airways following exposure to these pollutants. NO₂, which is poorly soluble in water, penetrates deep into the bronchial tree, producing asthmatic manifestations such as inflammation and increased mucus production as a result of high gaseous concentrations in the lung parenchyma. In contrast, SO₂, which is highly water soluble, exerts its effects rapidly in the upper airways, leading to similar limited correlations at all levels of exposure with fewer asthmatic manifestations observed. These data indicate that differing exposure assessment methods may be needed to capture specific disease consequences associated with these air pollutants.

Low-dose oral cadmium increases airway reactivity and lung neuronal gene expression in mice

Inhalation of cadmium (Cd) is associated with lung diseases, but less is known concerning pulmonary effects of Cd found in the diet. Cd has a decades-long half-life in humans and significant bioaccumulation occurs with chronic dietary intake. We exposed mice to low-dose CdCl2 (10 mg/L in drinking water) for 20 weeks, which increased lung Cd to a level similar to that of nonoccupationally exposed adult humans. Cd-treated mice had increased airway hyperresponsiveness to methacholine challenge, and gene expression array showed that Cd altered the abundance of 443 mRNA transcripts in mouse lung. In contrast to higher doses, low-dose Cd did not elicit increased metallothionein transcripts in lung. To identify pathways most affected by Cd, gene set enrichment of transcripts was analyzed. Results showed that major inducible targets of low-dose Cd were neuronal receptors represented by enriched olfactory, glutamatergic, cholinergic, and serotonergic gene sets. Olfactory receptors regulate chemosensory function and airway hypersensitivity, and these gene sets were the most enriched. Targeted metabolomics analysis showed that Cd treatment also increased metabolites in pathways of glutamatergic (glutamate), serotonergic (tryptophan), cholinergic (choline), and catecholaminergic (tyrosine) receptors in the lung tissue. Protein abundance measurements showed that the glutamate receptor GRIN2A was increased in mouse lung tissue. Together, these results show that in mice, oral low-dose Cd increased lung Cd to levels comparable to humans, increased airway hyperresponsiveness and disrupted neuronal pathways regulating bronchial tone. Therefore, dietary Cd may promote or worsen airway hyperresponsiveness in multiple lung diseases including asthma.

Asthma and bronchiectasis exacerbation

Bronchiectasis and asthma are common respiratory diseases worldwide. However, the influence of asthma on bronchiectasis remains unclear. The objective of this study is to analyse the effects of asthma on bronchiectasis exacerbation.Data from inpatients diagnosed with bronchiectasis with or without asthma at Shanghai Pulmonary Hospital (Shanghai, China) between January 2013 and December 2014 were retrospectively collected and analysed. 249 patients with only bronchiectasis and 214 patients with both bronchiectasis and asthma were included in the study. Follow-up records were used to evaluate the effect of asthma on bronchiectasis exacerbation.The variables found to be independently associated with bronchiectasis exacerbations were age (OR 1.07, 95% CI 1.03-1.11; p<0.001), duration of symptoms (OR 1.06, 95% CI 1.03-1.09; p<0.001), the presence of asthma (OR 2.6, 95% CI 1.15-5.88; p=0.021), forced expiratory volume in 1 s <50% predicted (OR 4.03, 95% CI 1.75-9.26; p=0.001), isolation of Pseudomonas aeruginosa in sputum (OR 2.41, 95% CI 1.00-5.79; p=0.05) and lung lesion extension to more than two lobes (OR 2.73, 95% CI 1.16-6.45; p=0.022).The existence of asthma was associated with an independent increase in risk of bronchiectasis exacerbation.