Epidermal growth factor receptor signalling contributes to house dust mite-induced epithelial barrier dysfunction

Abstract

Impaired airway epithelial barrier function has emerged as a key factor in the pathogenesis of allergic asthma. We aimed to discern the involvement of the epidermal growth factor receptor (EGFR) in allergen-induced epithelial barrier impairment, as we previously observed that house dust mite (HDM) signals through EGFR.We investigated the junctional integrity of human bronchial epithelial cells using electric cellsubstrate impedance sensing and immunofluorescent staining.HDM induced a rapid, transient fall in epithelial resistance, concomitant with delocalisation of Ecadherin and zona occludens (ZO)-1, and proteolytic cleavage of the latter. EGFR inhibition by AG1478 reduced the HDM-triggered decrease in epithelial resistance and improved restoration of epithelial junctions. Similarly, AG1478 increased epithelial barrier recovery upon electroporation-induced injury, although it delayed the migration phase of the wound healing response. HDM-promoted redistribution of E-cadherin was mediated via EGFR-dependent activation of protease-activated receptor (PAR)-2, while the concomitant ZO-1 degradation was PAR-2/EGFR-independent. Importantly, the fibrogenic cytokine transforming growth factor (TGF)-b prolonged HDM-induced EGFR phosphorylation and inhibited ligand-induced EGFR internalisation/degradation, which resulted in sustained E-cadherin and ZO-1 redistribution.Thus, allergen-induced, PAR-2/EGFR-mediated signalling decreases epithelial resistance and promotes junction disassembly. The TGF-b-enhanced EGFR signalling may be an important contributor to barrier dysfunction and increased epithelial vulnerability in response to HDM.

Epithelial EGF receptor signaling mediates airway hyperreactivity and remodeling in a mouse model of chronic asthma

“…reduced HDM-triggered decreases in epithelial resistance and improved restoration of epithelial junctions (21). Similarly, EGFR inhibition increased epithelial barrier recovery upon electroporation-induced injury (21).…”

The effects of inhaled house dust mite on airway barrier function and sensitivity to inhaled methacholine in mice

“…This would not have been detected in our design, where the longest duration of observation was 2 h after a single instillation. However, in vitro, near maximal effects were observed after only 15-30 min of exposure (8,25). Moreover, a design with repeated exposure over several days would not have been feasible to address our hypothesis.…”

“…Further support was obtained in studies of direct exposure of cultured epithelial cells to HDM fecal pellets or extract. Wan and colleagues (25) observed a time-dependent decrease in barrier function, which peaked at ϳ2 h and was still present at 6 h, whereas Heijink et al (8) observed decreased transepithelial resistance at 15 min which had resolved by 60 min. The fact that we did not observe any in vivo effect of direct exposure to HDM on either barrier function or responsiveness to MCh after either 30 min or 2 h suggests that any such effect must be minor and would seem unlikely to play a significant role in severity of disease.…”

“…Furthermore, the fact that HDM exposure also failed to induce any change in airway sensitivity to MCh supports the conclusion that if there was in fact a subtle change in airway barrier function, this was small enough not to have altered responses to inhaled agonists. The HDM extract we studied has been shown to be proteolytically active and is the same extract that has induced transient impairment of barrier function in cultured human airway epithelial cells (8). It is possible that continued exposure to the proteolytic effects of HDM may result in impaired barrier function over time.…”

“…Application of house dust mite (HDM) fecal pellets to cultured epithelial cells results in decreased intraepithelial staining for the zona occludens-1 adhesion molecule and increased rate of transepithelial movement of mannitol (25). In a later study, HDM extract was shown to have similar effects on E-cadherin and Z0 -1 adhesion molecules, as well as produce impaired barrier function as assessed by transepithelial resistance in cultured human airway epithelial cells (8). As no sensitization had occurred in these models, these responses were independent of any preprogrammed immune response to the HDM.…”