Abstract
Although high-affinity immunoglobulin (Ig)E receptor (FcεRI) expression is upregulated in type 2 (T2)-high asthmatic airway epithelium, its functional role in airway epithelial dysfunction has not been elucidated. Here we report the upregulated expression of FcεRI and p-EGFR (Epidermal Growth Factor Receptor), associated with decreased expression of E-cadherin and claudin-18 in bronchial biopsies of severe T2-high asthmatics compared to mild allergic asthmatics and non-T2 asthmatics. Monomeric IgE (mIgE) decreased the expression of junction proteins, E-cadherin, claudin-18, and ZO-1, and increased alarmin messenger RNA and protein expression in cultured primary bronchial epithelial cells from T2-high asthmatics. Epithelial FcεRI ligation with mIgE decreased transepithelial electric resistance in air-liquid interface cultured epithelial cells. FcεRI ligation with mIgE or IgE- Dinitrophenyl or serum of high-level allergen-specific IgE activated EGFR and Akt via activation of Src family kinases, mediating alarmin expression, junctional protein loss, and increased epithelial permeability. Furthermore, tracheal instillation of mIgE in house dust mite-sensitized mice induced airway hyper-responsiveness, junction protein loss, epithelial cell shedding, and increased epithelial permeability. Thus, our results suggest that IgE-FcεRI cross-linking in the airway epithelium is a potential and unnoticed mechanism for impaired barrier function, increased mucosal permeability, and EGFR-mediated alarmin production in T2-high asthma.