Airway Inflammation after Cessation of Exposure to Agents Causing Occupational Asthma

Long-term outcome of occupational asthma with different etiology

PURPOSE OF REVIEW

This review summarizes the recent literature on the long-term outcome of sensitizer-induced and irritant-induced occupational asthma.

RECENT FINDINGS

Recent studies of sensitizer-induced occupational asthma show that after the offending exposure has ceased, most patients report at least partial relief of symptoms. However, in the long term, the diagnosis may negatively impact their careers, incomes, and quality of life. The studies also offer new insights into diisocyanate-induced occupational asthma phenotypes and asthma remission rates. One third of these cases were in remission in long-term after reduction or cessation of exposure. The long-term prognosis of irritant-induced occupational asthma was demonstrated to be poorer than sensitizer-induced occupational asthma. Older age, low fractional exhaled nitric oxide levels and uncontrolled asthma at the time of diagnosis predicted uncontrolled asthma in the long term in patients with irritant and low-molecular-weight sensitizer induced occupational asthma.

SUMMARY

Recent studies provide further evidence of the long-term outcome of different occupational asthma phenotypes and the factors that affect them. These findings help us identify patients at risk of poor asthma outcomes, who need close monitoring and support. It should also be borne in mind that occupational asthma diagnosis may have wider-ranging negative impacts on patients' lives.

Impact of occupational asthma on health and employment status: a long-term follow-up study

OBJECTIVES

The aim of this study was to assess the predictors of a favourable prognosis of occupational asthma (OA) and the employment status of patients with OA at least 2 years after diagnosis.

METHODS

We collected data from 204 patients who had a diagnosis of OA confirmed by a positive specific inhalation challenge. We defined OA remission as meeting the following three criteria: no asthma symptoms, no antiasthma therapy for the last year and having normal lung function at the end of follow-up. A logistic regression analysis was performed to estimate the effects of the covariates.

RESULTS

At 10.6±7.8-year follow-up, 60 of 204 possible patients participated in the study, and among them 17 showed OA remission. When compared with the 43 patients with persistent OA, these patients exhibited at diagnosis younger age (p=0.0039), shorter duration of symptomatic exposure (p=0.0512), better lung function expressed by higher forced vital capacity (FVC%) predicted (p=0.0164), forced expiratory volume in 1 s (FEV₁) % predicted (p=0.0066) and FEV₁/FVC% (p=0.0132), and less bronchial hyper-responsiveness (p=0.0118). Nevertheless, in the multivariable model, no variables were significantly associated with OA remission. At follow-up, three individuals have retired; among the remaining 57 workers, 91.2% were still employed and 43.8% of them had continued working in the same factory after ceasing exposure to the causative agent.

CONCLUSIONS

This monocentric study did not identify a strong predictor of OA remission, but documented a high employment rate and a good job preservation over a long timeframe after diagnosis of OA mainly induced by low molecular weight agents.

Long-Term Outcome of Occupational Asthma From Irritants and Low-Molecular-Weight Sensitizers

BACKGROUND

The short-term asthma outcome of irritant-induced asthma (IIA) is poorer than that of low-molecular-weight (LMW) sensitizer-induced occupational asthma (OA).

OBJECTIVES

To evaluate the long-term asthma outcome of IIA and LMW-induced OA and to determine which baseline features are associated with a poor long-term outcome.

METHODS

This follow-up questionnaire study assessed 43 patients diagnosed with IIA and 43 patients with LMW-induced OA at the Finnish Institute of Occupational Health in 2004-2018. The baseline results were analyzed to detect features associated with uncontrolled asthma (Asthma Control Test [ACT] score of ≤19, or ≥2 exacerbations or ≥1 serious exacerbation within 1 year) at follow-up.

RESULTS

The median interval since OA diagnosis was 6.3 years (interquartile range [IQR]: 4.4-11.3 years). Uncontrolled asthma was more frequent with IIA than with LMW-induced OA (58% vs 40%, adjusted odds ratio [OR]: 3.60, 95% confidence interval [CI]: 1.20-10.81). Poor symptom control was the main factor for this difference (median [IQR] ACT score of 18 [15-22] vs 21 [18-23], P = .036, respectively). Among all participants, older age (OR: 1.08 per year, 95% CI: 1.02-1.15), a fractional exhaled nitric oxide (FeNO) value <20 ppb (OR: 5.08, 95% CI: 1.45-17.80), and uncontrolled asthma at baseline (OR: 3.94, 95% CI: 1.31-11.88) were associated with uncontrolled asthma at follow-up.

CONCLUSIONS

Long-term asthma control of IIA appears to be inferior to that of LMW-induced OA. Older age, a low FeNO value, and uncontrolled asthma at baseline might indicate a worse long-term outcome among those with IIA and LMW-induced OA.

Current unmet needs and potential solutions to uncontrolled asthma

Despite the availability of effective inhaled therapies, many patients with asthma have poor asthma control. Uncontrolled asthma presents a significant burden on the patient and society, and, for many, remains largely preventable. There are numerous reasons why a patient may remain uncontrolled despite access to therapies, including incorrect inhaler technique, poor adherence to treatment, oversight of triggers and suboptimal medical care. Shared decision-making, good patient-clinician communication, supported self-management, multidisciplinary patient education, new technology and risk stratification may all provide solutions to this major unmet need in asthma. Novel treatments such as biologics could benefit patients' lives, while the investigations into biomarkers, non-Type 2 asthma, treatable traits and disease modification give an exciting glimpse into the future of asthma care.

Which Therapy for Non-Type(T)2/T2-Low Asthma

Currently, the asthmatic population is divided into Type 2-high and non-Type 2/Type 2-low asthmatics, with 50% of patients belonging to one of the two groups. Differently from T2-high, T2-low asthma has not been clearly defined yet, and the T2-low patients are identified on the basis of the absence or non-predominant expression of T2-high biomarkers. The information about the molecular mechanisms underpinning T2-low asthma is scarce, but researchers have recognized as T2-low endotypes type 1 and type 3 immune response, and remodeling events occurring without inflammatory processes. In addition, the lack of agreed biomarkers reprents a challenge for the research of an effective therapy. The first-choice medication is represented by inhaled corticosteroids despite a low efficacy is reported for/in T2-low patients. However, macrolides and long-acting anti-muscarinic drugs have been recognized as efficacious. In recent years, clinical trials targeting biomarkers playing key roles in T3 and T1 immune pathways, alarmins, and molecules involved in neutrophil recruitment have provided conflicting results probably misleading (or biased) in patients' selection. However, further studies are warranted to achieve a precise characterization of T2-low asthma with the aim of defining a tailored therapy for each single asthmatic patient.

Long-Term Follow-Up of Cluster-Based Diisocyanate Asthma Phenotypes

BACKGROUND

Data on the outcome of occupational asthma (OA) are heterogeneous.

OBJECTIVE

To assess the impact of being part of a specific cluster at diagnosis on the long-term outcome of diisocyanate-induced OA.

METHODS

We collected data from 56 patients who had a diagnosis of OA confirmed by a positive specific inhalation challenge. Patients sensitized to toluene diisocyanate were allocated to cluster 1 or 2 based on a tree analysis, using the 3 variables relevant for cluster segregation identified in a previous study: age, body mass index, and forced expiratory volume in 1 second/forced vital capacity at diagnosis. Patients sensitized to methylene diisocyanate were allocated to cluster 3, as in previous study. We defined OA remission when a patient had met a total of 3 criteria: no asthma symptoms and no antiasthma therapy for the last year, as well as having normal lung function.

RESULTS

At follow-up, 16 patients showed OA remission. They exhibited better lung function, less bronchial hyperreactivity, as well as younger age at diagnosis. Twenty-eight patients were allocated to cluster 1, 10 to cluster 2, and 18 to cluster 3. The percentage of patients with OA remission was higher in cluster 2 (50% vs 25% in cluster 1 and 22.5% in cluster 3), although the difference was not statistically significant (P = .2789).

CONCLUSIONS

Age at diagnosis was a strong predictor of OA remission. The outcome of diisocyanate OA tended to be more favorable for patients with toluene diisocyanate OA allocated in cluster 2, but this finding needs to be validated by further data.

IL-33 blockade affects mediators of persistence and exacerbation in a model of chronic airway inflammation

BACKGROUND

Severe inflammatory airway diseases are associated with inflammation that does not resolve, leading to structural changes and an overall environment primed for exacerbations.

OBJECTIVE

We sought to identify and inhibit pathways that perpetuate this heightened inflammatory state because this could lead to therapies that allow for a more quiescent lung that is less predisposed to symptoms and exacerbations.

METHODS

Using prolonged exposure to house dust mite in mice, we developed a mouse model of persistent and exacerbating airway disease characterized by a mixed inflammatory phenotype.

RESULTS

We show that lung IL-33 drives inflammation and remodeling beyond the type 2 response classically associated with IL-33 signaling. IL-33 blockade with an IL-33 neutralizing antibody normalized established inflammation and improved remodeling of both the lung epithelium and lung parenchyma. Specifically, IL-33 blockade normalized persisting and exacerbating inflammatory end points, including eosinophilic, neutrophilic, and ST2⁺CD4⁺ T-cell infiltration. Importantly, we identified a key role for IL-33 in driving lung remodeling because anti-IL-33 also re-established the presence of ciliated cells over mucus-producing cells and decreased myofibroblast numbers, even in the context of continuous allergen exposure, resulting in improved lung function.

CONCLUSION

Overall, this study shows that increased IL-33 levels drive a self-perpetuating amplification loop that maintains the lung in a state of lasting inflammation and remodeled tissue primed for exacerbations. Thus IL-33 blockade might ameliorate symptoms and prevent exacerbations by quelling persistent inflammation and airway remodeling.

Asthma in Children and Adults-What Are the Differences and What Can They Tell us About Asthma?

Asthma varies considerably across the life course. Childhood asthma is known for its overall high prevalence with a male predominance prior to puberty, common remission, and rare mortality. Adult asthma is known for its female predominance, uncommon remission, and unusual mortality. Both childhood and adult asthma have variable presentations, which are described herein. Childhood asthma severity is associated with duration of asthma symptoms, medication use, lung function, low socioeconomic status, racial/ethnic minorities, and a neutrophilic phenotype. Adult asthma severity is associated with increased IgE, elevated FeNO, eosinophilia, obesity, smoking, and low socioeconomic status. Adult onset disease is associated with more respiratory symptoms and asthma medication use despite higher prebronchodilator FEV1/FVC. There is less quiescent disease in adult onset asthma and it appears to be less stable than childhood-onset disease with more relapses and less remissions.

Non-eosinophilic asthma: current perspectives

Although non-eosinophilic asthma (NEA) is not the best known and most prevalent asthma phenotype, its importance cannot be underestimated. NEA is characterized by airway inflammation with the absence of eosinophils, subsequent to activation of non-predominant type 2 immunologic pathways. This phenotype, which possibly includes several not well-defined subphenotypes, is defined by an eosinophil count <2% in sputum. NEA has been associated with environmental and/or host factors, such as smoking cigarettes, pollution, work-related agents, infections, and obesity. These risk factors, alone or in conjunction, can activate specific cellular and molecular pathways leading to non-type 2 inflammation. The most relevant clinical trait of NEA is its poor response to standard asthma treatments, especially to inhaled corticosteroids, leading to a higher severity of disease and to difficult-to-control asthma. Indeed, NEA constitutes about 50% of severe asthma cases. Since most current and forthcoming biologic therapies specifically target type 2 asthma phenotypes, such as uncontrolled severe eosinophilic or allergic asthma, there is a dramatic lack of effective treatments for uncontrolled non-type 2 asthma. Research efforts are now focusing on elucidating the phenotypes underlying the non-type 2 asthma, and several studies are being conducted with new drugs and biologics aiming to develop effective strategies for this type of asthma, and various immunologic pathways are being scrutinized to optimize efficacy and to abolish possible adverse effects.

The interplay between neuroendocrine activity and psychological stress-induced exacerbation of allergic asthma

Psychological stress is recognized as a key factor in the exacerbation of allergic asthma, whereby brain responses to stress act as immunomodulators for asthma. In particular, stress-induced enhanced type 2 T-helper (Th2)-type lung inflammation is strongly associated with asthma pathogenesis. Psychological stress leads to eosinophilic airway inflammation through activation of the hypothalamic-pituitary-adrenal pathway and autonomic nervous system. This is followed by the secretion of stress hormones into the blood, including glucocorticoids, epinephrine, and norepinephrine, which enhance Th2 and type 17 T-helper (Th17)-type asthma profiles in humans and rodents. Recent evidence has shown that a defect of the μ-opioid receptor in the brain along with a defect of the peripheral glucocorticoid receptor signaling completely disrupted stress-induced airway inflammation in mice. This suggests that the stress response facilitates events in the central nervous and endocrine systems, thus exacerbating asthma. In this review, we outline the recent findings on the interplay between stress and neuroendocrine activities followed by stress-induced enhanced Th2 and Th17 immune responses and attenuated regulatory T (Treg) cell responses that are closely linked with asthma exacerbation. We will place a special focus on our own data that has emphasized the continuity from central sensing of psychological stress to enhanced eosinophilic airway inflammation. The mechanism that modulates psychological stress-induced exacerbation of allergic asthma through neuroendocrine activities is thought to involve a series of consecutive pathological events from the brain to the lung, which implies there to be a "neuropsychiatry phenotype" in asthma.

Novel approaches to the management of noneosinophilic asthma

Noneosinophilic airway inflammation occurs in approximately 50% of patients with asthma. It is subdivided into neutrophilic or paucigranulocytic inflammation, although the proportion of each subtype is uncertain because of variable cut-off points used to define neutrophilia. This article reviews the evidence for noneosinophilic inflammation being a target for therapy in asthma and assesses clinical trials of licensed drugs, novel small molecules and biologics agents in noneosinophilic inflammation. Current symptoms, rate of exacerbations and decline in lung function are generally less in noneosinophilic asthma than eosinophilic asthma. Noneosinophilic inflammation is associated with corticosteroid insensitivity. Neutrophil activation in the airways and systemic inflammation is reported in neutrophilic asthma. Neutrophilia in asthma may be due to corticosteroids, associated chronic pulmonary infection, altered airway microbiome or delayed neutrophil apoptosis. The cause of poorly controlled noneosinophilic asthma may differ between patients and involve several mechanism including neutrophilic inflammation, T helper 2 (Th2)-low or other subtypes of airway inflammation or corticosteroid insensitivity as well as noninflammatory pathways such as airway hyperreactivity and remodelling. Smoking cessation in asthmatic smokers and removal from exposure to some occupational agents reduces neutrophilic inflammation. Preliminary studies of 'off-label' use of licensed drugs suggest that macrolides show efficacy in nonsmokers with noneosinophilic severe asthma and statins, low-dose theophylline and peroxisome proliferator-activated receptor gamma (PPARγ) agonists may benefit asthmatic smokers with noneosinophilic inflammation. Novel small molecules targeting neutrophilic inflammation, such as chemokine (CXC) receptor 2 (CXCR2) antagonists reduce neutrophils, but do not improve clinical outcomes in studies to date. Inhaled phosphodiesterase (PDE)4 inhibitors, dual PDE3 and PDE4 inhibitors, p38MAPK (mitogen-activated protein kinase) inhibitors, tyrosine kinase inhibitors and PI (phosphoinositide) 3kinase inhibitors are under development and these compounds may be of benefit in noneosinophilic inflammation. The results of clinical trials of biological agents targeting mediators associated with noneosinophilic inflammation, such as interleukin (IL)-17 and tumor necrosis factor (TNF)-α are disappointing. Greater understanding of the mechanisms of noneosinophilic inflammation in asthma should lead to improved therapies.

An official American Thoracic Society Workshop Report: presentations and discussion of the fifth Jack Pepys Workshop on Asthma in the Workplace. Comparisons between asthma in the workplace and non-work-related asthma

The fifth Jack Pepys Workshop on Asthma in the Workplace focused on the similarities and differences of work-related asthma (WRA) and non-work-related asthma (non-WRA). WRA includes occupational asthma (OA) and work-exacerbated asthma (WEA). There are few biological differences in the mechanisms of sensitization to environmental and occupational allergens. Non-WRA and OA, when due to high-molecular-weight agents, are both IgE mediated; it is uncertain whether OA due to low-molecular-weight agents is also IgE mediated. Risk factors for OA include female sex, a history of upper airway symptoms, and a history of bronchial hyperresponsiveness. Atopy is a risk factor for OA due to high-molecular-weight agents, and exposure to cleaning agents is a risk factor for both OA and non-WRA. WEA is important among workers with preexisting asthma and may overlap with irritant-induced asthma, a type of OA. Induced sputum cytology can confirm airway inflammation, but specific inhalation challenge is the reference standard diagnostic test. Inhalation challenges are relatively safe, with the most severe reactions occurring with low-molecular-weight agents. Indirect health care costs account for about 50% of total asthma costs. Workers with poor asthma control (WRA or non-WRA) are less likely to be employed. Income loss is a major contributor to the indirect costs of WRA. Overall, asthma outcomes probably are worse for adult-onset than for childhood-onset asthma but better for OA than adult-onset non-WRA. Important aspects of management of OA are rapid and proper confirmation of the diagnosis and reduction of exposure to sensitizers or irritants at work and home.

Persistence of asthma following allergen avoidance is associated with proTh2 myeloid dendritic cell activation

BACKGROUND

The natural history of asthma includes in some patients periods of disease remission, but the underlying mechanisms are unknown.

OBJECTIVES

We explored whether type 1 myeloid dendritic cell (mDC) dysfunction could be involved in the persistence of asthma, studying the controlled setting of occupational asthma after allergen avoidance.

METHODS

We recruited 32 patients with occupational asthma to flour or latex ascertained by specific inhalation challenge and who were no longer exposed to the causal allergen. Leukapheresis was performed in each patient to isolate and characterise blood type 1 mDCs, and their functionality was studied in coculture with allogeneic CD4(+) T cells from controls.

RESULTS

At follow-up, 11/32 patients (34%) were characterised by the absence of symptoms and non-specific bronchial hyper-responsiveness to histamine and were considered to be cured. When compared with cured patients, mDCs from patients with persistent disease increased the production of interleukin (IL) 5 and IL-13 by CD4(+) T cells, and upregulated programmed death ligand 2 (PD-L2) upon allergen pulsing. In addition, IL-5 and IL-13 responses could be reversed by exogenous IL-12, as well as by PD-L2 blockade.

CONCLUSIONS

This study indicates that pro-Th2 features of mDCs correlate with disease activity in asthma after cessation of exposure to the causal allergen. The findings also highlight that the Th2 programming by dendritic cells is flexible and partly mediated by PD-L2.

Patterns of suspected wheat-related allergy: a retrospective single-centre case note review in 156 patients

Background

Allergy to wheat can present clinically in different forms: Sensitization to ingested wheat via the gastrointestinal tract can cause traditional food allergy or in combination with exercise, Wheat-Dependent Exercise-Induced Anaphylaxis (WDEIA). Sensitization to inhaled wheat flour may lead to occupational rhinitis and/or asthma.

Methods

We retrospectively reviewed the case notes of 156 patients (age 0.7 – 73.3 years) with a case history of wheat allergy. The population was divided into three groups, 1: Wheat allergy elicited by ingestion, 2: By inhalation and 3: WDEIA. All patients were examined with detailed case history, specific IgE (sIgE), Skin Prick Test (SPT) and wheat challenge (nasal or oral ± exercise). Details of the case history were extracted from the patients´ case records.

Results

Group 1: Twenty one of 95 patients were challenge positive (15 children, 6 adults). All children had atopic dermatitis, and most (13/15) outgrew their wheat allergy. Most children (13/15) had other food allergies. Challenge positive patients showed significantly higher levels of sIgE to wheat and significantly more were SPT positive than challenge negative.

Group 2: Eleven out of 13 adults with occupational asthma or rhinitis were challenge positive. None outgrew their allergy. Seven had positive sIgE and 10 had positive SPT to wheat.

Group 3: Ten of 48 (adolescent/adults) were positive when challenged during exercise. Challenge positive patients showed significantly higher levels of sIgE to ω-5-gliadin. The natural course is presently unknown.

Conclusion

Wheat allergy can manifest in different disease entities, rendering a detailed case history and challenge mandatory. Patient age, occupation, concomitant allergies (food or inhalant) and atopic dermatitis are important factors for evaluation.

The use of a work-related asthma screening questionnaire in a primary care asthma program: an intervention trial

OBJECTIVES

The work-related asthma screening questionnaire (long-version) (WRASQ(L)) is a 14-item tool designed to increase the recognition of work-related asthma (WRA) in primary care. The purpose of this study was to assess whether the WRASQ(L) provided additional information about a patient's likelihood of WRA, beyond what was collected in standard care, and to assess the use of the WRASQ(L) in the primary care setting.

METHODS

This was an intervention study involving two Ontario primary care sites. Standard care for asthma patients in these sites involved completing the Asthma Care Map (ACM), a template for asthma management that includes seven WRA screening items. Participation in this study involved completing an electronic WRASQ(L) at each visit for participants and prompted care providers to record details related to WRA investigations. Ethics approval was obtained from an Institutional Review Board.

RESULTS

The study sample (N = 37) was predominantly female (73.0%), with a mean age of 46.3 years (SD, 10.9). The use of WRASQ(L) identified additional work-related symptoms in 38% and exposures in 60% of participants over and above those identified by the ACM. Two participants were newly suspected of WRA during the study period.

CONCLUSIONS

The WRASQ(L) provided added information about possible WRA over standard care. The use of the questionnaire's results by care providers was limited due to barriers encountered in incorporating the use of electronic version of the WRASQ(L) into clinical practice. Once validated and implemented in practice, the WRASQ(L) has the potential to increase the recognition of WRA.

Persistence of asthmatic response after ammonium persulfate-induced occupational asthma in mice

Introduction

Since persulfate salts are an important cause of occupational asthma (OA), we aimed to study the persistence of respiratory symptoms after a single exposure to ammonium persulfate (AP) in AP-sensitized mice.

Material and Methods

BALB/c mice received dermal applications of AP or dimethylsulfoxide (DMSO) on days 1 and 8. On day 15, they received a single nasal instillation of AP or saline. Airway hyperresponsiveness (AHR) was assessed using methacholine provocation, while pulmonary inflammation was evaluated in bronchoalveolar lavage (BAL), and total serum immunoglobulin E (IgE), IgG1 and IgG2a were measured in blood at 1, 4, 8, 24 hours and 4, 8, 15 days after the single exposure to the causal agent. Histological studies of lungs were assessed.

Results

AP-treated mice showed a sustained increase in AHR, lasting up to 4 days after the challenge. There was a significant increase in the percentage of neutrophils 8 hours after the challenge, which persisted for 24 hours in AP-treated mice. The extent of airway inflammation was also seen in the histological analysis of the lungs from challenged mice. Slight increases in total serum IgE 4 days after the challenge were found, while IgG gradually increased further 4 to 15 days after the AP challenge in AP-sensitized mice.

Conclusions

In AP-sensitized mice, an Ig-independent response is induced after AP challenge. AHR appears immediately, but airway neutrophil inflammation appears later. This response decreases in time; at early stages only respiratory and inflammatory responses decrease, but later on immunological response decreases as well.

Diisocyanate-induced asthma in Switzerland: long-term course and patients' self-assessment after a 12-year follow-up

BACKGROUND

Isocyanates are among the most common causes of occupational asthma (OA) in Switzerland. Patients with OA have been shown to have unfavourable medical, socioeconomic and psychological outcomes. We investigated long-term asthma and the socio-economic outcomes of diisocyanate-induced asthma (DIA) in Switzerland.

PATIENTS AND METHODS

We conducted an observational study on 49 patients with DIA and followed 35 of these patients over a mean exposure-free interval of 12 ± 0.5 (range 11.0-13.0) years. At the initial and follow-up examinations, we recorded data on respiratory symptoms and asthma medication; measured the lung function; and tested for bronchial hyperreactivity. We allowed the patients to assess their state of health and overall satisfaction using a visual analogue scale (VAS) at these visits.

RESULTS

The 35 patients whom we could follow had a median symptomatic exposure time of 12 months, interquartile range (IQR) 26 months and a median overall exposure time of 51 (IQR 104) months. Their subjective symptoms (p < 0.001) and the use of asthma medication (p = 0.002), particularly the use of inhaled corticosteroids (p < 0.001), decreased by nearly 50%. At the same time, the self-assessment of the patients' state of health and overall satisfaction increased considerably according to both symptomatology and income. In contrast, slight reductions in terms of FVC% predicted from 102% to 96% (p = 0.04), of FEV1% predicted from 91% to 87% (p = 0.06) and of the FEV1/FVC ratio of 3%; (p = 0.01) were observed while NSBHR positivity did not change significantly. In univariate as well as multivariate logistic analyses we showed significant associations between age, duration of exposure and FEV1/FVC ratio with persistent asthma symptoms and NSBHR.

CONCLUSIONS

We found that the patients' symptoms, the extent of their therapy and the decrease in their lung volumes during the follow-up period were similar to the findings in the literature. The same hold true for some prognostic factors, whereas the patients' self-assessment of their state of health and overall satisfaction improved considerably.

Severe adult-onset asthma: A distinct phenotype

BACKGROUND

Some patients with adult-onset asthma have severe disease, whereas others have mild transient disease. It is currently unknown whether patients with severe adult-onset asthma represent a distinct clinical phenotype.

OBJECTIVE

We sought to investigate whether disease severity in patients with adult-onset asthma is associated with specific phenotypic characteristics.

METHODS

One hundred seventy-six patients with adult-onset asthma were recruited from 1 academic and 3 nonacademic outpatient clinics. Severe refractory asthma was defined according to international Innovative Medicines Initiative criteria, and mild-to-moderate persistent asthma was defined according to Global Initiative for Asthma criteria. Patients were characterized with respect to clinical, functional, and inflammatory parameters. Unpaired t tests and χ(2) tests were used for group comparisons; both univariate and multivariate logistic regression were used to determine factors associated with disease severity.

RESULTS

Apart from the expected high symptom scores, poor quality of life, need for high-intensity treatment, low lung function, and high exacerbation rate, patients with severe adult-onset asthma were more often nonatopic (52% vs 34%, P = .02) and had more nasal symptoms and nasal polyposis (54% vs 27%, P ≤ .001), higher exhaled nitric oxide levels (38 vs 27 ppb, P = .02) and blood neutrophil counts (5.3 vs 4.0 10(9)/L, P ≤ .001) and sputum eosinophilia (11.8% vs 0.8%, P ≤ .001). Multiple logistic regression analysis showed that increased blood neutrophil (odds ratio, 10.9; P = .002) and sputum eosinophil (odds ratio, 1.5; P = .005) counts were independently associated with severe adult-onset disease.

CONCLUSION

The majority of patients with severe adult-onset asthma are nonatopic and have persistent eosinophilic airway inflammation. This suggests that severe adult-onset asthma has a distinct underlying mechanism compared with milder disease.

The effects of a multisite aerobic exercise intervention on asthma morbidity in sedentary adults with asthma: the Ex-asthma study randomised controlled trial protocol

OBJECTIVE

Aerobic exercise can improve cardiovascular fitness and does not seem to be detrimental to patients with asthma, though its role in changing asthma control and inflammatory profiles is unclear. The main hypothesis of the current randomised controlled trial is that aerobic exercise will be superior to usual care in improving asthma control. Key secondary outcomes are asthma quality of life and inflammatory profiles.

DESIGN

A total of 104 sedentary adults with physician-diagnosed asthma will be recruited. Eligible participants will undergo a series of baseline assessments including: the asthma control questionnaire; the asthma quality-of-life questionnaire and the inflammatory profile (assessed from both the blood and sputum samples). On completion of the assessments, participants will be randomised (1:1 allocation) to either 12-weeks of usual care or usual care plus aerobic exercise. Aerobic exercise will consist of three supervised training sessions per week. Each session will consist of taking a short-acting bronchodilator, 10 min of warm-up, 40 min of aerobic exercise (50-75% of heart rate reserve for weeks 1-4, then 70-85% for weeks 5-12) and a 10 min cool-down. Within 1 week of completion, participants will be reassessed (same battery as at baseline). Analyses will assess the difference between the two intervention arms on postintervention levels of asthma control, quality of life and inflammation, adjusting for age, baseline inhaled corticosteroid prescription, body weight change and pretreatment dependent variable level. Missing data will be handled using standard multiple imputation techniques.

ETHICS AND DISSEMINATION

The study has been approved by all relevant research ethics boards. Written consent will be obtained from all participants who will be able to withdraw at any time.

RESULTS

The result will be disseminated to three groups of stakeholder groups: (1) the scientific and professional community; (2) the research participants and (3) the general public.

REGISTRATION DETAILS CLINICALTRIALSGOV IDENTIFIER

NCT00953342.

Respiratory impairment and systemic inflammation in cedar asthmatics removed from exposure

BACKGROUND

Prior research has shown that removing occupational asthmatics from exposure does not routinely lead to significant improvements in respiratory impairment. These studies were of limited duration and factors determining recovery remain obscure. Our objective was to evaluate residual respiratory impairment and associated sputum and blood biomarkers in subjects with Western red cedar asthma after exposure cessation.

METHODS

Subjects previously diagnosed with cedar asthma, and removed from exposure to cedar dust for at least one year, were recruited. Subjects completed a questionnaire and spirometry. PC20 (methacholine concentration that produces 20% fall in FEV1 (forced expiratory volume at 1 second)) sputum cellularity and select Th1/Th2 (T helper cells 1 and 2) cytokine concentrations in peripheral blood were determined. The asthma impairment class was determined and multivariate analyses were performed to determine its relationship with sputum cell counts and serum cytokines.

RESULTS

40 non-smoking males (mean age 62) were examined at a mean interval of 25 years from cedar asthma diagnosis and 17 years from last cedar exposure. 40% were in impairment class 2/3. On average, the PC20 had increased by 2.0 mg/ml; the FEV1 decreased by 1.5 L, with greater decrease in those with greater impairment. Higher impairment was associated with serum interferon-gamma (mean = 1.3 pg/ml in class 2/3 versus 0.62 pg/ml in class 0/1, p = 0.04), mainly due to the FEV1 component (correlation with interferon-gamma = -0.46, p = 0.005).

CONCLUSION

Years after exposure cessation, patients with Western red cedar asthma have persistent airflow obstruction and respiratory impairment, associated with systemic inflammation.

RADS and its variants: asthma by another name

This article describes the different clinical variants of irritant-induced asthma, specifically focusing on high-dose irritant-induced asthma and irritant-induced work-exacerbated asthma, as well as reviews known causes, addresses the often adverse medical and socioeconomic outcomes of this complex condition, and considers issues of causation from an occupational and environmental medicine perspective.

Work-related asthma: a case-based approach to management

The management of work-related asthma has some differences from management of other asthma. Components of management include not only making as accurate a diagnosis as possible, identifying the causative agent or triggers at work, and managing the asthma with pharmacologic treatment as for other patients with asthma, but also advising on the appropriate work changes that may be needed, assisting the worker with appropriate compensation claims, and supporting protective measures for coworkers. This article discusses the approaches that may be taken for patients with different forms of work-related asthma.

Airway inflammatory responses following exposure to occupational agents

BACKGROUND

Airway inflammatory responses to specific inhalation challenges (SICs) with low-molecular-weight (LMW) and high-molecular-weight (HMW) agents have not been studied thoroughly. We assessed the changes in airway inflammatory cells following SIC in sensitized workers, and looked at the influence of various factors on the pattern of inflammatory responses to SIC.

METHODS

Induced sputum analysis was performed in workers sensitized to LMW (n = 41) or HMW agents (n = 41) after a control day and after a positive SIC. Cell counts were compared with lung function and various clinical parameters.

RESULTS

In the LMW group, eosinophils were increased following late asthmatic responses (median [interquartile range], 0.02 [0.04] × 10(6) cells/g vs 0.30 [0.80] × 10(6) cells/g and 1.0% [3.5] vs 8.9% [8.0], P < .05), as were neutrophil numbers (0.8 [1.3] × 10(6) cells/g vs 2.3 [5.4] × 10(6) cells/g, P = .04). In the HMW group, eosinophil percentages increased both after early (1.0% [2.2] vs 5.5% [14.5], P = .003) and dual asthmatic responses (4.5% [3.7] vs 15.0% [13.7], P = .02). In the LMW group, the increases in neutrophils were higher in current smokers than in ex-smokers or nonsmokers. The length of exposure to the agent, tobacco use, and baseline percentage of eosinophils were independent predictors of the change in eosinophils, whereas age and baseline neutrophil percentage were predictors of the change in neutrophils.

CONCLUSIONS

This study confirms that eosinophils and neutrophils are increased after SIC, whatever the causal agent. The type of agent is not predictive of the inflammatory response to SIC. Smoking is associated with a more neutrophilic response after SIC with an LMW agent.

May the reduction of exposure to specific sensitizers be an alternative to work cessation in occupational asthma? Results from a follow-up study

BACKGROUND

Few data are reported on the effects of a reduction of exposure to specific sensitizers in occupational asthma (OA). The objective of this study was to evaluate the clinical outcome of subjects with OA, comparing the effect of a reduction with that of the persistence or cessation of occupational exposure to the specific sensitizer.

SUBJECTS AND METHODS

Forty-one subjects with OA due to different sensitizers were diagnosed via a specific inhalation challenge. After a follow-up interval of 3.5 years, subjects were reexamined by clinical assessment, bronchial hyperresponsiveness (BH) and induced sputum.

RESULTS

At follow-up, subjects who had reduced occupational exposure (n = 22) showed a significant improvement in BH and a nonsignificant improvement in sputum eosinophilia (from 5.3 to 1.1%, n.s.), while subjects still exposed (n = 10) showed a significant decrease in FEV(1). Subjects who ceased work (n = 9) showed a trend of improvement in BH and sputum eosinophilia. Logistic analysis showed that the major determinant of improvement in BH at follow-up was the severity of BH at diagnosis, with a minimal contribution from the duration of exposure and treatment with inhaled corticosteroids during follow-up; reduction of work exposure did not enter into any model.

CONCLUSION

The reduction of occupational exposure could not be considered to be as effective as work cessation, which remained the best treatment for OA. However, it was not associated with a deterioration of FEV(1) as observed in subjects with persistent exposure.

Outcome of occupational asthma after removal from exposure: A follow-up study

BACKGROUND

Despite being removed from their workplace, the majority of workers with occupational asthma (OA) remain afflicted with asthma.

OBJECTIVES

To assess the time course of clinical, functional and inflammatory parameters in subjects with OA over a four-year period, and whether the airway inflammation observed at the time of the diagnosis predicts the outcome of OA.

METHODS

The present study was a four-year, prospective, longitudinal investigation of workers with OA. Spirometry, methacholine challenge and sputum induction were performed at two weeks, and followed up at six months, and one, two, three and four years after the performance of specific inhalation challenges.

RESULTS

A total of 24 subjects were enrolled. Overall, clinical and functional characteristics remained stable during the four-year follow-up period. Sputum eosinophil (Eos) counts&nbsp; decreased within two weeks after exposure. Two groups of subjects were identified according to low (less than 2%, Eos-) or high (2% or greater, Eos+) Eos counts after exposure to the offending agent. The Eos+ group decreased their dose of inhaled corticosteroids, had a trend toward an&nbsp;improvement of airway responsiveness as well as a stable forced expiratory volume in 1 s (FEV1), whereas the Eos- group showed a decrease in FEV1, without any improvement in their functional parameters. The Eos- group also had an increase in sputum neutrophils after exposure to the occupational agents as well as during the follow-up period.

CONCLUSION

There was a rapid decrease in eosinophilic inflammation after removal from exposure. Subjects with a noneosinophilic asthmatic reaction during specific inhalation challenge seemed to have a poorer prognosis than subjects with eosinophilic airway&nbsp; inflammation.

Association of bronchial reactivity to occupational agents with methacholine reactivity, sputum cells and immunoglobulin E-mediated reactivity

BACKGROUND

Bronchial responsiveness and IgE-mediated reactivity are associated with specific bronchial reactivity to allergens.

OBJECTIVE

Our aim was to examine whether airway inflammation also plays a role.

METHODS

Retrospective analysis of all subjects who underwent specific inhalation challenges in the investigation of occupational asthma (OA) since 2000. Responsiveness to methacholine (PC(20) ) and levels of eosinophils and neutrophils in induced sputum on the control day were associated with the presence of OA (positive-specific inhalation challenge). In a sample of subjects exposed to wheat flour, we also examined the role of specific IgE- mediated reactivity (skin reactivity, specific IgE).

RESULTS

PC(20) level was significantly more often normal in subjects with OA (35 of 129, 27% instances) by comparison with non-OA (15 of 189, 8% instances), but the positive predictive value of responsiveness to methacholine for OA was low (35%). Coupling information on the level of eosinophils to responsiveness to methacholine increased positive predictive values for OA from 39% to 69% depending on the thresholds used. The best balance of positive (69%) and negative (60%) predictive values was obtained in the case of normal PC(20) and eosinophils ≥3%. In a multivariate analysis carried out in 34 subjects exposed to wheat flour, responsiveness to methacholine, sputum eosinophils, skin weal size and levels of specific IgE were all significantly associated with OA to wheat flour.

CONCLUSION AND CLINICAL RELEVANCE

Information on the level of sputum eosinophils in addition to PC(20) provides a better association with OA vs. non-OA when PC(20) is normal. Levels of sputum eosinophils in addition to PC(20) and IgE-mediated reactivity increase the likelihood of OA due to wheat flour.

Risks of exposure to occupational asthmogens in atopic and nonatopic asthma: a case-control study in Taiwan

RATIONALE

Asthma is often work-related and can be classified as atopic or nonatopic on the basis of its pathogenesis. Few studies have reported an association between exposure to occupational asthmogens and asthma with and without atopy.

OBJECTIVES

We investigated, in adults with asthma, whether occupational exposure to asthmogens influenced the risk of having atopic or nonatopic asthma, and their level of lung function.

METHODS

We recruited 504 hospital-based adults with current asthma, 504 community-based control subjects, and 504 hospital-based control subjects in southern Taiwan. Asthma with atopy was defined as having asthma in combination with an increase in total IgE (≥100 U/ml) or a positive Phadiatop test (≥0.35 Pharmacia arbitrary unit/L) (Pharmacia ImmunoCAP; Pharmacia, Uppsala, Sweden). Occupational exposure to asthmogens was assessed with an asthma-specific job exposure matrix.

MEASUREMENTS AND MAIN RESULTS

We found a significant association between atopic asthma and exposure to high molecular weight asthmogens (adjusted odds ratio [AOR], 4.0; 95% confidence interval [CI], 1.8-8.9). Nonatopic asthma was significantly associated with exposure to low molecular weight asthmogens (AOR, 2.6; 95% CI, 1.6-4.3), including industrial cleaning agents and metal sensitizers. Agriculture was associated with both atopic and nonatopic asthma (AOR, 7.8; 95% CI, 2.8-21.8; and AOR, 4.1; 95% CI, 1.3-13.0, respectively). The ratio of FEV₁ to FVC in the high-risk group was significantly lower than in the no-risk group (P = 0.026) in currently employed patients with asthma.

CONCLUSIONS

In adults with asthma, occupational exposure to high and low molecular weight asthmogens appears to produce differential risks for atopic and nonatopic asthma.

Recent advances in the management of occupational asthma

Occupational asthma (OA) is the most common occupational lung disease in industrialized countries. This respiratory disorder remains poorly diagnosed and managed, and inadequately compensated for worldwide. The most appropriate treatment for OA remains early removal from exposure to ensure that the worker has no further exposure to the causal agent with preservation of income. However, various studies demonstrate that many workers with OA continue to remain exposed to the causative agent or suffer prolonged work disruption and discrimination, and may face unemployment. Despite removal from exposure, OA frequently turns into a chronic condition and requires intensive medical management, including appropriate pharmacotherapy and patient education and counseling. There are very few studies on allergen immunotherapy in OA. Subcutaneous immunotherapy with latex extract in healthcare workers and with wheat-flour extract in subjects with baker's asthma, at adequate doses, appears to be a useful treatment in reducing cutaneous and respiratory symptoms, but should be considered as a high-risk treatment due to the appearance of systemic reactions.

Occupational asthma: what can be done to prevent it?

Occupational asthma (OA) accounts for at least 10% of cases of adult asthma and presents as intermittent asthma occurring at the workplace and remitting on weekends and holidays, or persistent asthma, especially if the diagnosis and early intervention is delayed. OA is under-recognized, challenging and time-consuming to diagnose, difficult to confirm with currently available tests and complex in terms of legal implications of disability and impairment. Over 400 agents have been identified as causing OA with allergic triggers accounting for 80-90% of cases. Managing the worker with OA is demanding as it requires the most thorough evaluation with attention to detail to provide an accurate diagnosis and develop a thoughtful treatment recommendation. This frequently has to occur in the context of various competing entities including management, unions, insurance carriers and attorneys. The primary goal is excellent employee health through interventions that may allow the worker to continue in their occupation safely. Primary, secondary and tertiary prevention measures have been adopted for various types of OA with success. Novel approaches may become available and be beneficial to identify and treat OA early before severe, chronic, unremitting and irreversible changes occur.

Matrix metalloproteinases, IL-8 and glutathione in the prognosis of workers exposed to chlorine

BACKGROUND

Workers exposed to chlorine may be at risk of deterioration in FEV1.

METHODS

A prospective study of 72 workers examined over a 5.8 +/- 1.9 year period. A sample of induced sputum for cells and mediators was obtained in 69 subjects at baseline (Vb) and in 36 both at Vb and at follow-up (Vf).

RESULTS

Sixty-four workers (89%) experienced at least one accidental inhalation of chlorine in the interval. The mean decrease in FEV1 was 30 ml/year and thus was within normal limits. Among the analysed remodelling markers, the level of the MMP-9-TIMP-1 complex, but not of free MMP-9 and TIMP-1, significantly diminished from Vb to Vf. We found significant correlations between neutrophils, IL-8, MMP-9 and MMP9-TIMP-1 complex at Vb and Vf. While levels of total glutathione, IL-8, MMP9, TIMP-1 and MMP9-TIMP-1 complex were highly correlated with each other at Vb, this was inconstant at Vf. Levels of MMP9-TIMP1 complex and of TIMP1 at Vf were significantly lower in workers reporting chlorine puffs with mild acute respiratory symptoms between visits compared to those who had no, or asymptomatic inhalations (P = 0.03 and 0.02, respectively). The fall in FEV1 from Vb to Vf was significantly correlated with levels of glutathione at Vb. Cough between visits was associated with a decrease in FEV1 (P = 0.06).

CONCLUSION

Although no accelerated loss in FEV1 was documented in these workers exposed to chlorine, subjects with a greater fall in FEV1 were more likely to report cough and have higher levels of total glutathione at Vb.

Comparison of risk factors for the onset and maintenance of depression

BACKGROUND

Factors associated with depression are usually identified from cross-sectional studies.

AIMS

We explore the relative roles of onset and recovery in determining these associations.

METHOD

Hazard ratios for onset and recovery were estimated for 39 risk factors from a cohort study of 10,045 general practice attendees whose depression status was assessed at baseline, 6 and 12 months.

RESULTS

Risk factors have a stronger relative effect on the rate of onset than recovery. The strongest risk factors for both onset and maintenance of depression tend to be time-dependent. With the exception of female gender the strength of a risk factor's effect on onset is highly predictive of its impact on recovery.

CONCLUSIONS

Preventive measures will achieve a greater reduction in the prevalence of depression than measures designed to eliminate risk factors post onset. The strength of time-dependent risk factors suggests that it is more productive to focus on proximal rather than distal factors.

Airway remodeling in subjects with severe asthma with or without chronic persistent airflow obstruction

BACKGROUND

The patterns of airway remodeling and the biomarkers that distinguish different subtypes of severe asthma are unknown.

OBJECTIVES

We sought to characterize subjects with severe asthma with and without chronic persistent airflow obstruction with respect to airway wall remodeling (histopathologic and radiologic) and specific sputum biomarkers.

METHODS

Subjects with severe asthma with chronic persistent (n = 16) or intermittent (n = 18) obstruction were studied. Endobronchial biopsy specimens were analyzed for airway smooth muscle area, epithelial detachment, basement membrane thickness, and submucosal fibrosis. Levels of eosinophil cationic protein, myeloperoxidase, matrix metalloproteinase 9, tissue inhibitor of matrix metalloproteinase 1 (ELISA), and 27 cytokines (multiplex assay) and differential cell counts were measured in induced sputum. Airway thickness was measured by means of high-resolution computed tomographic scanning.

RESULTS

Chronic persistent obstruction was associated with earlier age of onset, longer disease duration, more inflammatory cells in the sputum, and greater smooth muscle area (15.65% +/- 2.69% [n = 10] vs 8.96% +/- 1.99% [n = 14], P = .0325). No differences between groups were found for any of the biomarker molecules measured in sputum individually. However, principal component analysis revealed that the dominant variables in the chronic persistent obstruction group were IL-12, IL-13, and IFN-gamma, whereas IL-9, IL-17, monocyte chemotactic protein 1, and RANTES were dominant in the other group. Airway imaging revealed no differences between groups.

CONCLUSION

Subjects with severe asthma with chronic persistent obstruction have increased airway smooth muscle with ongoing T(H)1 and T(H)2 inflammatory responses. Neither airway measurements on high-resolution computed tomographic scans nor sputum analysis seem able to identify such patients.

Long-term outcomes of acute irritant-induced asthma

RATIONALE

The long-term outcomes of acute irritant-induced asthma (IIA) are mostly unknown.

OBJECTIVES

To study the long-term outcomes of IIA.

METHODS

We reassessed 35 subjects who experienced IIA at a mean interval of 13.6 +/- 5.2 years.

MEASUREMENTS AND MAIN RESULTS

The causal agent was chlorine in 20 cases (57%). At diagnosis, the mean +/- SD FEV(1) was 74.5 +/- 19.5% predicted, and all subjects showed bronchial hyperresponsiveness. At reassessment, all subjects reported respiratory symptoms, and 24 (68%) were on inhaled steroids. There were no significant improvements in FEV(1) and FEV(1)/FVC values. Twenty-three subjects had a methacholine test, and only six subjects had normal levels of responsiveness. Of the remaining 12 subjects, six had improvement in FEV(1) after bronchodilator >or=10%. In samples of induced sputum obtained from 27 subjects, six had eosinophils >or=2%. Levels of inflammatory and remodeling mediators were higher than in control subjects but were no different from subjects with occupational asthma due to sensitization. Quality of life score was 4.4 +/- 1.5 on a 0 (worst) to 7 (best) scale. Twelve subjects had an abnormal depression score.

CONCLUSIONS

This study provides the first evidence of significant long-term impact of acute IIA on various outcomes.

[The diagnosis and management of occupational asthma]

INTRODUCTION

Occupational asthma (OA), with a latency period induced by multiple exposures, is characterized by immunological sensitization to the responsible agent, based on both an IgE mediated mechanisms and non specific bronchial hyper responsiveness.

DIAGNOSTIC METHODS

In the diagnosis of OA, the medical history is obviously the starting-point. Onset of respiratory symptoms at work and resolution on vacation are indications of the diagnosis. After analysis of several publications, this element appears to have the best level of proof (grade 2+) according to the criteria of evidence-based medicine. A visit of the workplace, with the cooperation of the industrial physician, is essential to characterize the nature of the exposure. Positive immunological tests (skin tests and/or specific IgE) associated with objective criteria of symptoms related to work (modification of PEFR, lung function and/or nonspecific bronchial hyper responsiveness) will confirm the aetiological diagnosis of OA. Specific bronchial provocation tests performed in the laboratory allow the identification of new agents involved in OA and are necessary when other investigations are discordant or unavailable. OA needs a stepwise approach including induced sputum eosinophilic counts and measurements of exhaled nitric oxide.

MANAGEMENT OF OA

OA requires removal from the workplace because persistence of exposure to respiratory sensitisers may lead to an increase and prolongation of asthma symptoms. However, removal from the workplace can have tremendous professional, financial and social consequences, and sometimes a compromise must be found with reduction of exposure by various methods combined with adequate treatment. The pharmacological treatment of patients with OA should be the same as for patients with non OA, the use of bronchodilators and corticoids depending on the severity of asthma. Concerning the medico-legal aspects, OA can be recognised as an occupational disease. In France OA is included in several tables of work-related diseases.

Work-related asthma in Montreal, Quebec: population attributable risk in a community-based study

BACKGROUND

Occupational exposures are an important cause of adult-onset asthma but the population attributable risk percentage (PAR%) has been less frequently studied.

OBJECTIVES

To examine the distribution and determinants of adult asthma in six centres across Canada using data gathered in a community-based study.

METHODS

Data were gathered in a community survey of 2959 adults using the European Community Respiratory Health Survey Protocol. A subsample of 498 subjects completed detailed health and occupational questionnaires, methacholine challenge tests and allergy skin tests. Asthma was defined in three ways: current wheeze, asthma symptoms and/or medication, and airway hyperresponsiveness. Occupational exposures were classified as sensitizers or irritants. Associations between asthma and occupational exposures were examined using logistic regression analysis. Model selection was based on the findings for current wheeze, and the same model was applied to the other definitions of asthma.

RESULTS

Fifty-six per cent of subjects reported ever having had occupational exposure to sensitizers, and 9.8% to irritants. Current wheeze was associated with exposure to irritants (PAR% 4.54%), and airway hyperresponsiveness was associated with exposure to sensitizers (PAR% 30.7%). Neither a history of childhood asthma, atopy, nor confining the analysis to adult-onset asthma affected these associations. Analysis of effect modification suggested two types of work-related asthma: one due to exposure to occupational sensitizers, and the other due to exposure to irritants.

CONCLUSIONS

Detailed assessment of past and current exposures is essential in the investigation of work-related asthma. Childhood asthma reactivated or aggravated by work exposures is not easy to distinguish from asthma induced by work, a misclassification that could lead to an underestimation of work-induced asthma. This should be taken into account in jurisdictions in which persons with work-aggravated asthma are not eligible for workers' compensation.

Diagnosis and management of work-related asthma: American College Of Chest Physicians Consensus Statement

BACKGROUND

A previous American College of Chest Physicians Consensus Statement on asthma in the workplace was published in 1995. The current Consensus Statement updates the previous one based on additional research that has been published since then, including findings relevant to preventive measures and work-exacerbated asthma (WEA).

METHODS

A panel of experts, including allergists, pulmonologists, and occupational medicine physicians, was convened to develop this Consensus Document on the diagnosis and management of work-related asthma (WRA), based in part on a systematic review, that was performed by the University of Alberta/Capital Health Evidence-Based Practice and was supplemented by additional published studies to 2007.

RESULTS

The Consensus Document defined WRA to include occupational asthma (ie, asthma induced by sensitizer or irritant work exposures) and WEA (ie, preexisting or concurrent asthma worsened by work factors). The Consensus Document focuses on the diagnosis and management of WRA (including diagnostic tests, and work and compensation issues), as well as preventive measures. WRA should be considered in all individuals with new-onset or worsening asthma, and a careful occupational history should be obtained. Diagnostic tests such as serial peak flow recordings, methacholine challenge tests, immunologic tests, and specific inhalation challenge tests (if available), can increase diagnostic certainty. Since the prognosis is better with early diagnosis and appropriate intervention, effective preventive measures for other workers with exposure should be addressed.

CONCLUSIONS

The substantial prevalence of WRA supports consideration of the diagnosis in all who present with new-onset or worsening asthma, followed by appropriate investigations and intervention including consideration of other exposed workers.

[Course of bronchial hyperresponsiveness in patients with occupational asthma caused by exposure to persulfate salts]

OBJECTIVE

Persulfate salts are among the most frequently implicated causes of occupational asthma. The aim of this study was to describe the course of bronchial hyperresponsiveness and immunologic test results in patients with occupational asthma due to persulfate salts.

PATIENTS AND METHODS

Ten patients with occupational asthma due to persulfate salts were studied. Diagnosis was based on specific bronchial challenge tests performed at least 3 years before enrollment. An exhaustive medical and work history was taken during interviews with all patients, and all underwent spirometry and nonspecific bronchial challenge testing. Total immunoglobulin E levels were determined and skin prick tests to several persulfate salts were performed.

RESULTS

At the time of evaluation, 7 patients had avoided workplace exposure to persulfate salts. The bronchial hyperresponsiveness of 3 of those 7 patients had improved significantly. No improvement was observed in patients who continued to be exposed. Specific skin prick tests became negative in 3 patients who were no longer exposed at the time of the follow-up evaluation. Most of the patients continued to report symptoms, although improvements were noted. One patient, however, reported worsening of symptoms in spite of avoidance of exposure.

CONCLUSIONS

Although asthma symptoms and bronchial hyperresponsiveness may persist for patients with occupational asthma due to persulfate salts, their condition seems to improve if they avoid exposure. This course does not seem to differ from that reported for other cases of occupational asthma.

Inflammation and functional outcome in diisocyanate-induced asthma after cessation of exposure

BACKGROUND

The clinical outcome of diisocyanate-induced asthma has been found to be poor despite cessation of exposure. Our aim was to study the outcome of diisocyanate-induced asthma after initiation of inhaled steroid treatment at a mean period of 7 months (range 2-60 months) after cessation of exposure by following up lung function and bronchial inflammation.

METHODS

Bronchoscopy was performed on 17 patients 2 days after a positive inhalation challenge test, after which budesonide 1600 mug a day was started. Bronchoscopy, spirometry, and histamine challenge tests were repeated at 6 months and on average 3 years. The results were also compared with those obtained from 15 healthy control subjects.

RESULTS

Nonspecific bronchial hyperreactivity diminished significantly (P = 0.006); however, forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) values decreased, with a median yearly reduction of FEV1 of 79 ml. The count of mast cells in bronchial mucosa decreased (P = 0.012) and that of macrophages increased (P = 0.001). Interleukin-4 level in mucosa was during the first year significantly higher than in controls but its level decreased in the follow-up. Interleukin-6, interleukin-15, and tumour necrosis factor alpha messenger-RNA levels were significantly higher in hyperreactive patients than in nonhyperreactive patients at the end of the follow-up.

CONCLUSION

Our results indicate that inflammation may persist in diisocyanate-induced asthma despite inhaled steroid medication. However, TH2-type inflammation diminished. Persistent nonspecific bronchial hyperreactivity was associated with proinflammatory acting cytokines produced mainly by macrophages. Considering the poor prognosis of the disease the findings could be utilized to develop the follow-up and treatment of diisocyanate-induced asthma.

Reproducibility of Nasal Lavage in the Context of the Inhalation Challenge Investigation of Occupational Rhinitis

Background

The nasal lavage (NAL) method is increasingly used to assess changes in upper airways inflammation in the investigation of occupational rhinitis (OR). A good reproducibility of the method is fundamental to accurately assess changes in markers of inflammation in nasal secretions before and after inhalation challenges. The main objective of this study was to assess the short-term reproducibility of cells and cellular markers of inflammation in NAL in the setting of specific inhalation challenge (SIC) investigating OR. An ancillary objective was to assess the reproducibility of NAL in the context of two different SIC methodologies.

Methods

Twenty-five subjects attended the laboratory for 2 separate days of NAL performed within the same week. On the first visit subjects underwent NAL before a SIC sham session and on the second visit before a SIC with the active agent. These prechallenge NAL measurements obtained on both days were used to analyze the reproducibility of the NAL method.

Results

The reproducibility for cell differential counts was satisfactory for neutrophils (intraclass correlation coefficient [ICC] = 0.68), for eosinophils (ICC = 0.95), for macrophages (ICC = 0.77), and for epithelial cells (ICC = 0.73). The reproducibility of total cell counting was poor (ICC = 0.12). The reproducibility of ECP concentrations was satisfactory (ICC = 0.67). Eosinophil counts were reproducible in the context of two different challenge methodologies.

Conclusion

The NAL method was shown to be sufficiently reproducible to be considered useful for the monitoring of upper airways inflammation during the investigation of OR by SIC.

How long do the systemic and ventilatory responses to toluene diisocyanate persist in dermally sensitized mice?

BACKGROUND

Years after removal from exposure, workers with occupational asthma still show respiratory symptoms and airway hyperresponsiveness on re-exposure to the offending agent.

OBJECTIVE

We investigated the persistence of the respiratory responsiveness to toluene diisocyanate (TDI) in a mouse model.

METHODS

BALB/C mice received dermal applications of TDI on days 1 and 8, and a single intranasal instillation of TDI on day 10, 15, 20, 25, 30, 40, 50, 60, or 90. After instillation, early (1 hour) changes in ventilatory function and methacholine responsiveness (22 hours) were assessed. Cell counts and macrophage inflammatory protein 2 were measured in bronchoalveolar lavage. Total serum IgE, IgG(1), and IgG(2a) were quantified. Lymphocyte subpopulations were assessed in auricular and cervical lymph nodes, and release of IL-4 and IFN-gamma by these lymph node cells was measured.

RESULTS

Toluene diisocyanate-treated mice showed immediate ventilatory changes, increased methacholine reactivity, and an influx of neutrophils and macrophage inflammatory protein 2 in bronchoalveolar lavage as long as 50 days after initial treatment. These mice also showed a relative increase in CD19(+) cells and a decrease in CD4(+) and CD8(+) cells in auricular lymph nodes. Increased release of IL-4 and IFN-gamma in auricular lymph node cells was observed only until 20 days after sensitization. Total serum IgE, IgG(1), and IgG(2a) remained significantly elevated in TDI-sensitized mice until 90 days after dermal sensitization.

CONCLUSION

Ventilatory and lung inflammatory responses decrease with increasing delay between sensitization and challenge, despite persistent humoral signs of sensitization.

Structural changes and airway remodelling in occupational asthma at a mean interval of 14 years after cessation of exposure

BACKGROUND

Occupational asthma (OA) may cause alterations of airways with inflammation and remodelling after cessation of exposure. Although the long-term clinical, functional and induced sputum sequelae have been examined in workers removed from exposure, the long-term pathological outcomes are unknown.

OBJECTIVE

We aimed to investigate whether airway inflammation and remodelling were present in bronchial biopsies of subjects with prior OA but without evidence of persisting asthma at a mean interval of 14 years after cessation of exposure.

METHODS

Ten clinically and functionally asymptomatic subjects with a prior diagnosis of OA were recruited and underwent bronchoscopy, bronchoalveolar lavage and bronchial biopsy. Comparisons were made with biopsies from normal control subjects. Epithelial detachment, epithelial metaplasia, mucous gland and airway smooth muscle (ASM) areas as well as the distance between the epithelium and ASM were measured by image analysis. The amount of collagen present was assessed by van Gieson staining. The numbers of TGF-beta1- and eosinophil cationic protein (ECP)-positive cells were evaluated by specific immunostaining.

RESULTS

Statistically significant increases were found in the numbers of TGF-beta1- and ECP-positive cells and in the amount of subepithelial fibrosis present in the biopsies of subjects with prior OA compared with control biopsies. The distance between the epithelium and ASM was significantly reduced in the OA group. Increases in epithelial metaplasia, ASM mass, mucous gland numbers, collagen deposition and eosinophilia in the OA group were not statistically significant. There was no evidence of ongoing inflammation in the group with prior OA as assessed by the number of T lymphocytes present.

CONCLUSION

Some aspects of airway inflammation and remodelling persist in subjects with prior OA long after cessation of exposure even in the absence of clinical, sputum and functional abnormalities. These findings are relevant to the assessment of long-term sequelae in subjects with OA when reviewed after cessation of exposure.

Characteristics and medical resource use of asthmatic subjects with and without work-related asthma

BACKGROUND

Asthma is work related when there is an association between symptoms and work. Occupational asthma (OA) is induced by the workplace, whereas work-exacerbated asthma (WEA) is triggered by the workplace but not induced by it.

OBJECTIVE

We sought to compare the clinical characteristics and the use of medical resources between subjects with work-related asthma (WRA) and asthmatic control subjects without WRA, as well as between subjects with OA and subjects with WEA.

METHODS

We performed a retrospective cohort study of the charts of subjects with WRA who were investigated between 2001 and 2004 in our centers. These subjects were matched according to sex, age, and FEV(1) to subjects with non-WRA investigated during the same period. All charts were linked to the information provided by the Régie de l'assurance maladie du Québec, including outpatient clinic visits and visits to the emergency department and hospitalizations during the year before and after the initial assessment in our centers.

RESULTS

Three hundred fifty-one subjects had WRA (WEA, 145; OA, 206), whereas 384 subjects were asthmatic control subjects without WRA. Subjects with WRA had more asthma exacerbations than subjects with non-WRA. The risk factor of experiencing a severe asthma exacerbation was no greater for OA than for WEA (odds ratio, 1.15; 95% CI, 0.75-1.75).

CONCLUSION

WRA is associated with a larger use of medical resources than non-WRA.

CLINICAL IMPLICATIONS

Improving the diagnosis and management of WRA is crucial for limiting the use of medical resources associated with this condition.

Outcomes in occupational asthma caused by reactive dye after long-term avoidance

BACKGROUND

Reactive dye (RD) is known to be a causative agent of occupational asthma (OA). However, to date, no report has been issued concerning the long-term outcomes of RD-induced OA.

OBJECTIVES

We sought to evaluate the long-term outcomes in cases of OA caused by RD.

METHODS

A total of 11 OA patients confirmed by RD bronchial challenge were enrolled in this study. First and second follow-up examinations were conducted at 4.3+/-2.3 and 13.7+/-2.3 years (means+/-SD) after the initial examinations, respectively. Skin prick test with RD and 11 common inhalant allergens, pulmonary function test, methacholine bronchial provocation testing, symptom and medication scores were determined at each visit. In addition, inflammatory cells in induced sputum were measured at the second follow-up examinations.

RESULTS

Reduced lung function at initial examinations did not recover at the first and second examinations despite cessation of exposure and proper pharmacological treatment. In addition, asthma severity (as determined by symptom and medication scores) and non-specific airway hyper-responsiveness to methacholine also did not improve. However, skin reactivity to RD almost disappeared at the second examinations. Interestingly, four of the six patients who showed negative skin responses to all 11 common inhalant allergens at initial examinations were found to be atopic at the second examinations. Moreover, in terms of airway inflammation, seven of the 11 patients showed eosinophilia in induced sputum (> or =3%) at the second examinations despite having been on high-dose inhaled corticosteroid medication.

CONCLUSION

The present study demonstrates that reduced lung function and asthmatic symptoms persist in RD-induced OA even after long-term exposure avoidance.