Soluble E-Cadherin Contributes to Airway Inflammation in Severe Asthma.

ABSTRACT

Impaired airway epithelial barrier and decreased expression of E-cadherin are key features of severe asthma. As a gatekeeper of the mucosa, E-cadherin can be cleaved from the cell surface and released into the apical lumen as a soluble form (sE-cadherin).This study was aimed to investigate the role of sE-cadherin in severe asthma.Induced sputum was obtained from healthy subjects and patients with asthma. Two murine models of severe asthma were established using either TDI (toluene diisocyanate) or OVA (ovalbumin)/CFA (complete Freund's adjuvants). The role of sE-cadherin in severe asthma was evaluated by intraperitoneal injection of DECMA-1, a neutralizing antibody against sE-cadherin. Mice or THP-1-derived macrophages were treated with recombinant sE-cadherin to explore the pro-inflammatory mechanism of sE-cadherin.Severe asthma patients had a significantly higher sputum sE-cadherin level than the health subjects with mild to moderate asthma, which were positively correlated with sputum HMGB1 level and glucocorticoid dosage required for daily control. Allergen exposure markedly increased sE-cadherin level in the bronchoalveolar lavage fluid in mice. Treatment of DECMA-1 significantly attenuated allergen-induced airway inflammation and hyperresponsivenes in both models of severe asthma. While exposure to recombinant sE-cadherin dramatically up-regulated VEGF expression in THP-1-derived macrophages, and increased neutophlil and eosinophil infiltration into the airway as well as the release of VEGF and IL-6 in mice, both of which can be suppressed by pharmacological inhibition of ERK signaling.Taken together, our data indicated that sE-cadherin contributed to the airway inflammation of severe asthma in an ERK-depedent pathway.