Zuckerman Jodi D, Lee Winston Y, DelGaudio John M, Moore Charles E, Nava Porfirio, Nusrat Asma, Parkos Charles A
Department of Otolaryngology-Head and Neck Surgery, Emory University School of Medicine, Atlanta, Georgia, USA.
Am J Rhinol. 2008 Nov-Dec;22(6):589-97. doi: 10.2500/ajr.2008.22.3235.
Many mucosal inflammatory conditions are associated with alterations in epithelial intercellular junctions and barrier function; however, little is known about the role of intercellular junctions in inflammatory diseases of the upper airways. In this study, we examined nasal polyps for altered intercellular junctions and protein expression.
Biopsy specimens of nasal polyps and normal tissue were obtained intraoperatively from 11 patients and 6 controls. Tissue was analyzed for expression of intercellular junctional proteins by immunofluorescence. In parallel, cultured human bronchial epithelial (HBE) cells were treated with tumor necrosis factor (TNF) alpha, interferon (IFN) gamma, and IL-13 to simulate inflammatory conditions followed by assessment for changes in junctional proteins by immunofluorescence and Western blot.
Of the intercellular junctional proteins analyzed, including proteins comprising tight and adherens junctions, the only alterations observed were in desmosomal proteins in nasal polyp epithelium compared with normal controls. Specifically, expression of desmosomal proteins DSG2 and DSG3 were significantly decreased in polyps versus controls (0.53 pixel/microm2 versus 1.09 pixel/microm2 [p = 0.009], and 0.29 pixel/microm2 versus 1.11 pixel/microm2 [p = 0.0078], respectively). In vitro experiments involving exposure of cultured HBE cells with inflammatory cytokines revealed that TNF-alpha treatment resulted in internalization and decreased expression of DSG2 by immunofluorescence and Western blotting. Treatment with IFN-gamma resulted in increased expression of DSG2 and evidence of protein cleavage by Western blot. IL-13 exposure resulted in down-regulation of DSG2 expression and evidence of protein cleavage.
These results indicate that nasal polyps express decreased levels of DSG2 and DSG3 components of desmosomal junctions. This is likely linked to the mucosal inflammatory response. Exposure of a respiratory cell line to Th1/Th2 cytokines results in similar expressional alterations in DSG2, suggesting protein internalization and cleavage. We speculate that weakened desmosomal junctions in nasal mucosa secondary to inflammatory cytokines may contribute to the formation of nasal polyposis.
许多黏膜炎症性疾病与上皮细胞间连接和屏障功能的改变有关；然而，关于细胞间连接在上呼吸道炎症性疾病中的作用知之甚少。在本研究中，我们检测了鼻息肉中细胞间连接和蛋白表达的改变。
术中从11例患者和6例对照者获取鼻息肉和正常组织的活检标本。通过免疫荧光分析组织中细胞间连接蛋白的表达。同时，用人肿瘤坏死因子（TNF）α、干扰素（IFN）γ和白细胞介素（IL）-13处理培养的人支气管上皮（HBE）细胞以模拟炎症状态，随后通过免疫荧光和蛋白质印迹法评估连接蛋白的变化。
在所分析的细胞间连接蛋白中，包括构成紧密连接和黏附连接的蛋白，与正常对照相比，在鼻息肉上皮中观察到的唯一改变是桥粒蛋白的改变。具体而言，与对照相比，息肉中桥粒蛋白DSG2和DSG3的表达显著降低（分别为0.53像素/微米²对1.09像素/微米² [p = 0.009]，以及0.29像素/微米²对1.11像素/微米² [p = 0.0078]）。涉及用炎性细胞因子处理培养的HBE细胞的体外实验显示，TNF-α处理导致DSG2通过免疫荧光和蛋白质印迹法发生内化并表达降低。IFN-γ处理导致DSG2表达增加且通过蛋白质印迹法有蛋白裂解的证据。IL-13处理导致DSG2表达下调且有蛋白裂解的证据。
这些结果表明鼻息肉中桥粒连接的DSG2和DSG3成分表达水平降低。这可能与黏膜炎症反应有关。将呼吸道细胞系暴露于Th1/Th2细胞因子会导致DSG2出现类似的表达改变，提示蛋白内化和裂解。我们推测炎性细胞因子继发的鼻黏膜桥粒连接减弱可能促成鼻息肉病的形成。
