Intracellular signal transduction mechanisms of airway epithelial cells in allergic conditions

最近，人们认为上皮细胞在变应性鼻炎等变应性疾病中起重要作用。本研究试图阐明介质影响上皮细胞功能变化的细胞内信号转导机制。1.白三烯激活粘蛋白基因转录的机制白三烯D_4（Leukotriene D_4，LTD_4）可诱导气道粘液分泌。然而，LTD_4对粘蛋白基因表达的影响以前一无所知。主要采用报告基因检测法进行分析。我们发现NF-κB是LTD_4诱导MUC 2基因转录所必需的，并且是CysLT_1 R依赖的。以上结果提示LTD_4通过CysLT_1R、G蛋白、PKC、MEK、ERK和NF-κ B等信号通路上调MUC 2基因转录。2.凝血酶增加上皮细胞通透性的机制 ...更多信息 甚至显示增加内皮细胞单层的渗透性。因此，我们怀疑凝血酶影响气道通透性。在组织培养细胞插入物的微孔膜上建立Calu-3细胞单层。我们检查了局部应用凝血酶或凝血酶受体激活肽（TRAP）对以下方面的影响：（1）放射性标记甘露醇和白蛋白的跨上皮渗透性（管腔至血清转移），（2）电阻变化，和（3）通过荧光显微镜评估的肌动蛋白纤维含量。与未处理的对照培养物相比，用凝血酶或TRAP处理单层细胞24小时显著降低了电阻，增加了对甘露醇和白蛋白的渗透性。此外，这些处理增强了肌动蛋白应力纤维的外观，并且在细胞-细胞接触区域处可见小间隙。凝血酶似乎通过受体介导的气道上皮细胞肌动蛋白网络重组增加上皮通透性。这可能导致气道屏障功能受损。少

Recently, it is believed that epithelial cells play important roles in allergic conditions as in allergic rhinitis. We tried to elucidate the intracellular signal transduction mechanisms by which mediators have effects on functional changes in epithelial cells.1.Mechanism by which leukotrienes activate mucin gene transcriptionLeukotriene D_4 (LTD_4) has been shown to induce mucus secretion in the airway. However, nothing has previously been known about the effect of LTD_4 on mucin gene expression. Reporter gene assay was mainly used for analysis. We found that NF-κB is required for LTD_4-induced MUC2 gene transcription in a CysLT_1R-dependent manner. Taken together, our findings suggest that LTD_4 up-regulates MUC2 gene transcription via a signaling pathway involving CysLT_1R, G-protein, PKC, MEK, ERK and NF-κB.2.Mechanism by which thrombin increases permeability in epithelial cellsRecently, thrombin was reported to be increased in the airway of patients with asthma, and thrombin has b … More een shown to increase the permeability of endothelial cell monolayers. Therefore, we suspected that thrombin affects airway permeability. Calu-3 cell monolayers were established on microporous membranes of tissue culture cell inserts. We examined the effects of topically applied thrombin or thrombin receptor activating peptide (TRAP) on : (1) transepithelial permeability (luminal to serosal transfer) of radiolabeled mannitol and albumin, (2) changes in electrical resistance, and (3) actin fiber content as assessed by fluorescence microscopy. Compared with untreated control cultures, treatment of the monolayers for 24 h with thrombin or TRAP significantly decreased the electrical resistance and increased the permeability to mannitol and albumin. In addition, these treatments enhanced the appearance of actin stress fibers, and small gaps became visible at areas of cell-cell contact. Thrombin appears to increase epithelial permeability by receptor-mediated reorganization of the actin network in airway epithelial cells. This is likely to contribute to the impairment of the airway barrier function. Less