Ginzberg H H, Cherapanov V, Dong Q, Cantin A, McCulloch C A, Shannon P T, Downey G P
Department of Pediatrics, Division of Gastroenterology and Nutrition, The University of Toronto, Toronto, Ontario, Canada M5S 1A8.
Am J Physiol Gastrointest Liver Physiol. 2001 Sep;281(3):G705-17. doi: 10.1152/ajpgi.2001.281.3.G705.
Neutrophil-mediated injury to gut epithelium may lead to disruption of the epithelial barrier function with consequent organ dysfunction, but the mechanisms of this are incompletely characterized. Because the epithelial apical junctional complex, comprised of tight and adherens junctions, is responsible in part for this barrier function, we investigated the effects of neutrophil transmigration on these structures. Using a colonic epithelial cell line, we observed that neutrophils migrating across cell monolayers formed clusters that were associated with focal epithelial cell loss and the creation of circular defects within the monolayer. The loss of epithelial cells was partly attributable to neutrophil-derived proteases, likely elastase, because it was prevented by elastase inhibitors. Spatially delimited disruption of epithelial junctional complexes with focal loss of E-cadherin, beta-catenin, and zonula occludens 1 was observed adjacent to clusters of transmigrating neutrophils. During neutrophil transmigration, fragments of E-cadherin were released into the apical supernatant, and inhibitors of neutrophil elastase prevented this proteolytic degradation. Addition of purified leukocyte elastase also resulted in release of E-cadherin fragments, but only after opening of tight junctions. Taken together, these data demonstrate that neutrophil-derived proteases can mediate spatially delimited disruption of epithelial apical junctions during transmigration. These processes may contribute to epithelial loss and disruption of epithelial barrier function in inflammatory diseases.
中性粒细胞介导的肠道上皮损伤可能导致上皮屏障功能破坏，进而引发器官功能障碍，但其机制尚未完全明确。由于由紧密连接和黏附连接组成的上皮顶端连接复合体部分负责这种屏障功能，我们研究了中性粒细胞迁移对这些结构的影响。利用结肠上皮细胞系，我们观察到迁移穿过细胞单层的中性粒细胞形成簇，这些簇与局灶性上皮细胞丢失以及单层内圆形缺损的形成有关。上皮细胞的丢失部分归因于中性粒细胞衍生的蛋白酶，可能是弹性蛋白酶，因为弹性蛋白酶抑制剂可阻止这种情况发生。在迁移的中性粒细胞簇附近观察到上皮连接复合体的空间限定性破坏，伴有E-钙黏蛋白、β-连环蛋白和闭合蛋白1的局灶性丢失。在中性粒细胞迁移过程中，E-钙黏蛋白片段释放到顶端上清液中，中性粒细胞弹性蛋白酶抑制剂可阻止这种蛋白水解降解。添加纯化的白细胞弹性蛋白酶也导致E-钙黏蛋白片段的释放，但仅在紧密连接开放后。综上所述，这些数据表明中性粒细胞衍生的蛋白酶可在迁移过程中介导上皮顶端连接的空间限定性破坏。这些过程可能导致炎症性疾病中上皮细胞丢失和上皮屏障功能破坏。
