Mast cell chymase impairs bronchial epithelium integrity by degrading cell junction molecules of epithelial cells

Abstract

Background: An increased degree of mast cell (MC) degranulation and damage to the epithelial lining are prominent features of bronchial asthma. In asthmatic airways, it seems likely that epithelial cells will be exposed to increased concentrations of proteases from MC, though their actions on the epithelium are still not very clear. Methods: Bronchial rings from human lung tissue or 16HBE cell monolayer were incubated with MC chymase in different doses or various inhibitors. The sections of paraffin-embedded tissue were haematoxylin-eosin stained and computerized by image analysis for epithelial damage-scale-evaluation; the cell viability, proliferation, adhesion and lactate dehydrogenase activity release were assayed; the expressions of gelatinases, cell junction molecules and structure proteins of 16HBE were examined. Results: Mast cell chymase was found to provoke profound changes in the morphology of bronchi epithelial layer. Following incubation with chymase, there was 40% reduction in the length of epithelium that was intact, with detachment of columnar epithelial cells and basal cells. Chymase reduced epithelial cell proliferation and induced cell detachment, which were associated with the changes in secretion and activation of matrix metalloproteinase-2/9. In intact epithelial cell layers, immunocytochemistry study revealed that chymase reduced the expressions of occludin, claudin-4, ZO-1, E-cadherin, focal adhesion kinase and cytokeratin. Overall data of this study indicated that MC chymase can influence tissue remodelling, disrupt epithelial cell junctions, inhibit wound healing and impair the barrier function of epithelium, resulting in dysfunction of airway wall and ECM remodelling in pathogenesis of asthma. Conclusion: Mast cell chymase plays a key role in inducing the damage to bronchial epithelium in asthma. K E Y W O R D S bronchial epithelium,

Exophilin-5 regulates allergic airway inflammation by controlling IL-33–mediated Th2 responses

“…Among epithelial cell-derived cytokines, IL-33 was the major cytokine rapidly released after Alternaria stimulation. Antigen inhalation also induces rapid release of endogenous chemical mediators such as proteases and tumor necrosis factor α by mast cells, which potentially damages epithelial cells in the lungs of antigen-sensitized individuals (22,23). In fact, after the third OVA aerosol challenge, although IL-33 levels in the lung homogenates were comparable between WT and Exph5-KO mice, rapid IL-33 release into the alveolar space was observed in Exph5-KO mice, but not in WT mice as mast cells where it regulates exocytosis (11,12), dendritic cells (DCs) (13), Th cells (7), and lung epithelial cells (14), all of which play essential roles in antigen-specific allergic immune responses in the lung, the roles of Rab27 in the net allergic immune responses in vivo are unknown.…”

Nasal epithelial barrier dysfunction increases sensitization and mast cell degranulation in the absence of allergic inflammation

“…We evaluated whether epithelial barrier disturbance could also have a direct effect on MCs. Since an ongoing allergic inflammation directly contributes to an impaired epithelial barrier, an in vivo model of passive sensitization was developed to study the effects of barrier dysfunction on MC degranulation irrespective of inflammation. Mice were passively sensitized with r Der p 2‐specific murine IgE and subsequently exposed intranasally to chitosan (or sham) followed by r Der p 2 (Figure A).…”

“…In a study using primary human bronchial epithelial cells, IL‐1β impaired the epithelial barrier . Another study using bronchial epithelial cells found that the MC mediator chymase plays an important role in impairing epithelial monolayers via the disruption of cell junctions . However, the direct contribution of a defective epithelial barrier to allergic sensitization and allergic inflammation remained unclear.…”

“…Finally, we evaluated whether increased allergen passage in already sensitized subjects can facilitate MC degranulation and thus enhance allergic disease. As allergic inflammation by itself affects barrier integrity, we designed a novel murine model with passive sensitization to r Der p 2 to circumvent the effect of allergic inflammation on the airway mucosal barrier. We here demonstrate that chitosan‐induced barrier dysfunction increases allergen passage and not only facilitates allergic sensitization but also allergen‐induced MC degranulation.…”

Utilization of metabolic energy in treatment of ocular surface disorders: polyphosphate as an energy source for corneal epithelial cell proliferation

“…Where indicated, the migration was inhibited by addition of human chymase (C8118; Sigma-Aldrich) at a concentration of 10 munits per ml as described. 22…”