The School of Pharmaceutical Engineering and Life Science, Changzhou University, Jiangsu, China.
The Faculty of Medicine, The University of Southampton, Southampton, UK.
Allergy. 2019 Jul;74(7):1266-1276. doi: 10.1111/all.13666. Epub 2018 Dec 9.
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.
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.
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.
Mast cell chymase plays a key role in inducing the damage to bronchial epithelium in asthma.
肥大细胞（MC）脱颗粒程度增加和上皮衬里损伤是支气管哮喘的突出特征。在哮喘气道中，上皮细胞似乎会暴露于来自 MC 的蛋白酶浓度增加，但它们对上皮细胞的作用仍不是很清楚。
用人肺组织的支气管环或 16HBE 细胞单层与不同剂量的 MC 糜蛋白酶或各种抑制剂孵育。对石蜡包埋组织切片进行苏木精-伊红染色，并通过图像分析进行上皮损伤评分评估；测定细胞活力、增殖、粘附和乳酸脱氢酶活性释放；检测 16HBE 的明胶酶、细胞连接分子和结构蛋白的表达。
发现肥大细胞糜蛋白酶可引起支气管上皮层形态发生深刻变化。孵育糜蛋白酶后，完整上皮的长度减少了 40%，柱状上皮细胞和基底细胞脱落。糜蛋白酶降低了上皮细胞的增殖并诱导细胞脱落，这与基质金属蛋白酶-2/9 的分泌和激活变化有关。在完整的上皮细胞层中，免疫细胞化学研究显示糜蛋白酶降低了紧密连接蛋白 occludin、claudin-4、ZO-1、E-钙黏蛋白、粘着斑激酶和细胞角蛋白的表达。本研究的综合数据表明，MC 糜蛋白酶可影响组织重塑，破坏上皮细胞连接，抑制伤口愈合，损害上皮屏障功能，导致气道壁功能障碍和 ECM 重塑在哮喘发病机制中起作用。
肥大细胞糜蛋白酶在诱导哮喘支气管上皮损伤中起关键作用。
