MedWire News: Exposing human bronchial epithelial cells to cigarette smoke extract induces a greater than threefold increase in allergen penetration across the respiratory epithelium, research shows.
The results suggest that "cigarette smoking damages the respiratory epithelial barrier and allows allergens to intrude more efficiently into the subepithelial tissues," according to Verena Niederberger (Medical University of Vienna, Austria) and colleagues in the journal Allergy.
Several epidemiological studies have suggested a positive association between smoking and allergy, although this link is still a matter of debate. Other studies, for example, have shown a negative association between active smoking and atopy.
In this study, Niederberger and colleagues investigated whether cigarette smoke directly impaired the barrier functions of the respiratory epithelium for allergens.
Researchers used a surrogate of the intact respiratory epithelium by culturing a human bronchial epithelial cell line. The cell monolayer was then exposed to standardized cigarette smoke extract and the effects of the allergen penetration were measured using birch, grass, and dust mite pollens, along with various histamine release experiments.
Exposing the cells to cigarette smoke extract resulted in the development of cellular gaps and a decrease in transepithelial resistance. When exposed to the smoke extract, there was a more than threefold increase of the three allergens across the epithelial cells.
Additionally, the increased subepithelial allergen concentrations resulted in an augmented release of inflammatory mediators from sensitized basophils, including the activation of various immune cells, such as mast cells, T cells and eosinophils.
As a result of reducing the barrier function of the respiratory epithelium for allergens, cigarette smoke appears to contribute to increased allergic inflammation and the exacerbation of allergic disease, report the researchers.
The findings help provide an explanation for observations that cigarette smoke promotes sensitization to allergens, allergen-induced allergic inflammation and boosting of immunoglobulin E (IgE) memory responses, they add.
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