Then and Now Reactive Airways Dysfunction Syndrome

Progress in Occupational Asthma

Occupational asthma (OA) represents one of the major public health problems due to its high prevalence, important social and economic burden. The aim of this review is to summarize current data about clinical phenotypes, biomarkers, diagnosis and management of OA, a subtype of work-related asthma. Most studies have identified two phenotypes of OA. One is sensitizer-induced asthma, occuring after a latency period and caused by hypersensitivity to high- or low-molecular weight agents. The other is irritant-induced asthma, which can occur after one or more exposures to high concentrations of irritants without latency period. More than 400 agents causing OA have been identified and its list is growing fast. The best diagnostic approach for OA is a combination of clinical history and objective tests. An important tool is a specific inhalation challenge. Additional tests include assessments of bronchial hyperresponsiveness to methacholine/histamine in patients without airflow limitations, monitoring peak expiratory flow at- and off-work, sputum eosinophil count, exhaled nitric oxide measurement, skin prick tests with occupational allergens and serum specific IgE. Treatment of OA implies avoidance of exposure, pharmacotherapy and education. OA is a heterogeneous disease. Mechanisms of its different phenotypes, their diagnosis, role of new biomarkers and treatment require further investigation.

Sulfur dioxide exposure reduces the quantity of CD19+ cells and causes nasal epithelial injury in rats

Background

Reactive airway dysfunction syndrome (RADS), also called irritant-induced asthma, is a type of occupational asthma that can occur within a very short period of latency. The study sought to investigate the influence of sulfur dioxide (SO₂) exposure on CD19+ cells and nasal epithelial injury.

Methods

We investigated the effects of SO₂ on CD19 expression and morphological changes of nasal epithelia in rats. In the study, 20 rats were randomly divided into the SO₂ exposure group that were exposed to 600 ppm SO₂, 2 h/day for consecutive 7 days, and the control group that were exposed to filtered air).

Results

Inhalation of high concentration of SO₂significantly reduced CD19 expression at both the mRNA transcript and protein levels, and reduced the percentages of CD19⁺ cells and CD19⁺/CD23⁺ cells in the nasal septum. However, inhalation of high concentration of SO₂ did not affect immunoglobulin (Ig) G, IgA and IgE levels in the serum and nasal septum. More importantly, SO₂ exposure also caused mild structural changes of the nasal septum.

Conclusion

Our results reveal that inhalation of a high concentration of SO₂ reduces CD19 expression and causes structural change of the nasal septum in rats.