Clinical aspects of work-related asthma: past achievements, persistent challenges, and emerging triggers

Cardiovascular Disease Among Adults With Work-Related Asthma, 2012-2017

INTRODUCTION

Asthma is associated with an increased risk for cardiovascular disease, and adults with persistent, severe asthma have a significantly higher risk of cardiovascular disease than adults with intermittent or no asthma.

METHODS

The objective of this cross-sectional study was to assess the association between work-related asthma status and cardiovascular disease among ever-employed adults (aged 18-64 years) with current asthma using data from the 2012-2017 Behavioral Risk Factor Surveillance System Asthma Call-Back Survey from 37 states and the District of Columbia. Weighted prevalence ratios and 95% CIs, adjusted for age, sex, race/ethnicity, education, household income, smoking status, chronic obstructive pulmonary disease, diabetes, and BMI, were calculated. In addition, the associations of cardiovascular disease with adverse asthma outcomes and asthma control among adults with work-related asthma were examined. Analyses were conducted in 2021.

RESULTS

Among an estimated annualized 14.8 million ever-employed adults aged 18-64 years with current asthma, adults with work-related asthma (prevalence ratio=1.5; 95% CI=1.2, 1.8) and possible work-related asthma (prevalence ratio=1.2; 95% CI=1.0, 1.5) were significantly more likely to have cardiovascular disease than adults with non-work-related asthma. Among adults with work-related asthma, those with very poorly controlled asthma (prevalence ratio=1.8; 95% CI=1.3, 2.5) and an asthma-related emergency room visit (prevalence ratio=1.5; 95% CI=1.1, 2.0) were significantly more likely to have cardiovascular disease.

CONCLUSIONS

Adults with work-related asthma were more likely to have cardiovascular disease than those with non-work-related asthma. Primary prevention, early diagnosis, and implementation of optimal work-related asthma management are essential for workers' health. Cardiovascular disease should be considered where appropriate when diagnosing and recommending treatment and interventions for adults with work-related asthma.

Work-related asthma: A position paper from the Thoracic Society of Australia and New Zealand and the National Asthma Council Australia

Work-related asthma (WRA) is one of the most common occupational respiratory conditions, and includes asthma specifically caused by occupational exposures (OA) and asthma that is worsened by conditions at work (WEA). WRA should be considered in all adults with asthma, but especially those with new-onset or difficult to control asthma. Improvement in asthma symptoms when away from work is suggestive of WRA. Clinical history alone is insufficient to diagnose WRA; therefore, objective investigations are required to confirm the presence of asthma and the association of asthma with work activities. Management of WRA requires pharmacotherapy similar to that of non-WRA, however, also needs to take into account control of the causative workplace exposure. Ongoing exposure will likely lead to decline in lung function and worsening asthma control. WRA is a preventable condition but this does rely on increased awareness of WRA and thorough identification and control of all potential occupational respiratory hazards.

Phosphorylation of low density lipoprotein receptor-related protein 6 is involved in receptor for advanced glycation end product-mediated β-catenin stabilization in a toluene diisocyanate-induced asthma model

BACKGROUND

We have previously demonstrated that the receptor for advanced glycation end products (RAGE)/β-catenin axis plays a vital role in regulating airway inflammation and airway remodeling in a toluene diisocyanate (TDI)-induced murine asthma model. However, the exact mechanism of β-catenin activation remains unclear. Given that phosphorylation of the low-density lipoprotein receptor-related protein 6 (Lrp6) is a key step in mediating β-catenin stabilization in canonical wnt/β-catenin signaling, we explored the possible relationship between RAGE and Lrp6 in regulating β-catenin stabilization in TDI-induced asthma.

METHODS

In this study, a TDI-induced murine asthma model was generated, and mice were treated with a specific inhibitor of RAGE. In vitro, the human bronchial epithelial cell line 16HBE was treated with TDI-human serum albumin (TDI-HSA). RAGE overexpression or knockdown cells were also constructed and assessed.

RESULTS

The results showed that RAGE inhibition or RAGE knockdown decreased β-catenin nuclear accumulation and the expression of relevant β-catenin targeted genes (VEGF, MMP9, TGF-β1) in the TDI-induced murine asthma model and TDI-HSA-treated 16HBE cells, respectively. Silencing of RAGE reversed the TDI-induced increase in phospho-ERK1/2 (p-ERK) and phospho-Lrp6 (p-Lrp6) in 16HBE cells. Pretreatment with the extracellular signal-regulated kinase (ERK)1/2 inhibitor U0126 suppressed TDI-induced Lrp6 phosphorylation. Furthermore, knockdown of Lrp6 in 16HBE cells decreased β-catenin nuclear translocation and the expression of VEGF, MMP9, and TGF-β1.

CONCLUSION

These data suggested that the RAGE/ERK axis modulates Lrp6 phosphorylation, contributing to β-catenin stabilization in a TDI-induced murine model.

Asthma medication use among adults with current asthma by work-related asthma status, Asthma Call-back Survey, 29 states, 2012-2013

OBJECTIVE

Asthma severity is defined as the intensity of treatment required to achieve good control of asthma symptoms. Studies have shown that work-related asthma (WRA) can be associated with poorer asthma control and more severe symptoms than non-WRA. Associations between asthma medications and WRA status were assessed using data from the 2012-2013 Asthma Call-back Survey among ever-employed adults (≥18 years) with current asthma from 29 states.

METHODS

Persons with WRA had been told by a physician that their asthma was work-related. Persons with possible WRA had asthma caused or made worse by their current or previous job, but did not have physician-diagnosed WRA. Asthma medications were classified as controller (i.e., long-acting β-agonist, inhaled corticosteroid, oral corticosteroid, cromolyn/nedocromil, leukotriene pathway inhibitor, methylxanthine, anti-cholinergics) and rescue (i.e., short-acting β-agonist). Demographic and clinical characteristics were examined. Associations between asthma medications and WRA status were assessed using a multivariate logistic regression to calculate adjusted prevalence ratios (PRs).

RESULTS

Among an estimated 15 million ever-employed adults with current asthma, 14.7% had WRA and an additional 40.4% had possible WRA. Compared with adults with non-WRA, those with WRA were more likely to have taken anti-cholinergics (PR = 1.80), leukotriene pathway inhibitor (PR = 1.59), and methylxanthine (PR = 4.76), and those with possible WRA were more likely to have taken methylxanthine (PR = 2.85).

CONCLUSIONS

Results provide additional evidence of a higher proportion of severe asthma among adults with WRA compared to non-WRA. To achieve optimal asthma control, adults with WRA may require additional intervention, such as environmental controls or removal from the workplace exposure.

Occupational Allergies: A Brief Review

Occupational allergies are groups of work-related disorders that are accompanied by immunologic reaction to workplace allergens and include occupational asthma, rhinitis, hypersensitivity pneumonitis, dermatitis, and anaphylaxis. This mini review presents a brief analysis of the more important aspects of occupational allergic disorders.

Do chronic workplace irritant exposures cause asthma?

PURPOSE OF REVIEW

The present review summarizes the recent literature on the relation between chronic workplace irritant exposures and asthma, focusing on exposures of low to moderate levels. We discuss results from epidemiological surveys, potential biological mechanisms, and needs for further research. These aspects are largely illustrated by studies on exposure to cleaning products.

RECENT FINDINGS

Recent results from nine population-based and workplace-based epidemiological studies, mostly cross-sectional, found an increased risk of both new-onset and work-exacerbated asthma among participants exposed to moderate level of irritants and/or cleaning products.

SUMMARY

Evidence of a causal effect of chronic workplace irritant exposure in new-onset asthma remains limited, mainly because of a lack of longitudinal studies and the difficulty to evaluate irritant exposures. However, recent epidemiological studies strengthen the evidence of an effect of chronic exposure to irritants in work-related asthma. The underlying mechanism remains unknown but may be related to oxidative stress, neurogenic inflammation and dual irritant and adjuvant effects. However, disentangling chronic irritant effects from either acute irritant-induced asthma or immunological low molecular weight agent-induced asthma is difficult for some agents. Further research is needed to improve assessment of irritant exposures and identify biomarkers.