Regulation of MUC1 mucin during airway inflammation

描述(申请人提供)：虽然呼吸道炎症是吸入性细菌的基本宿主防御机制，但过度和长期的炎症对宿主是有害的。在过去的几年里，关于呼吸道炎症是如何启动和维持的，积累了大量的知识。然而，人们对炎症消退的机制知之甚少。MUC1是一种跨膜粘蛋白样糖蛋白，表达于包括呼吸道在内的各种黏膜表面的上皮细胞表面。我们最近发现，在铜绿假单胞菌(PA)呼吸道感染过程中，MUC1表达缺陷的小鼠表现出增强的呼吸道炎症和细菌清除，这表明MUC1的抗炎作用以及MUC1水平在呼吸道细菌感染中的重要性。经细菌制品处理后的MUC1/MUC1的抗炎活性也在各种体外研究中得到证实。在呼吸道细菌感染过程中，MUC1/MUC1的水平如何被调节尚不清楚，但最近的证据表明，肿瘤坏死因子-(。在这一新的应用中，我们将确定MUC1/MUC1上调的机制，以控制呼吸道细菌感染时的炎症。利用肺上皮细胞系(A549细胞)和在气液界面完全分化的正常人支气管上皮细胞，我们发现中性粒细胞弹性蛋白酶(NE)通过转录机制刺激MUC1的产生。此外，多条间接证据表明，肿瘤坏死因子-1是去甲肾上腺素诱导MUC1转录途径的关键成分。我们假设，呼吸道炎症是由肺内MUC1/MUC1水平控制的，而MUC1/MUC1水平受肿瘤坏死因子-(。这项应用的具体目的是：(1)在体外用遗传学和免疫学方法表征NE诱导MUC1上调所涉及的信号通路；(2)使用各种基因工程小鼠证明，PA感染引起的呼吸道炎症由NE诱导的TNF-α激活控制，进而上调肺中MUC1的水平。这项拟议研究的成功完成将为我们目前对呼吸道炎症调节的理解提供重要的见解，并将为控制呼吸道细菌感染期间过度和长期的呼吸道炎症提供药理学策略。与公众相关：该项目的成功完成将有助于我们更好地了解呼吸道炎症，并为预防和治疗与细菌感染相关的过度呼吸道炎症制定药理学策略。

DESCRIPTION (provided by applicant): While airway inflammation is an essential host defense mechanism for inhaled bacteria, excessive and prolonged inflammation is detrimental to the host. Over the past several years, a great deal of knowledge has accrued about how airway inflammation is initiated and maintained. However, the mechanisms through which inflammation is resolved are poorly understood. MUC1 (MUC1 in human and Muc1 in nonhuman species) is a transmembrane mucin-like glycoprotein expressed on the surface of epithelial cells lining various mucosal surfaces, including the respiratory tract. We recently showed that mice deficient in Muc1 expression exhibited both enhanced airway inflammation and bacterial clearance during Pseudomonas aeruginosa (PA) airway infection, suggesting an anti-inflammatory role for Muc1 and the importance of Muc1 levels during airway bacterial infection. The anti-inflammatory activity of MUC1/Muc1 following treatment with bacterial products also was demonstrated in various in vitro studies. How the levels of MUC1/Muc1 are regulated during airway bacterial infection is unknown, but recent evidence indicates the involvement of TNF-(. In this renewal application, we will identify the mechanism by which MUC1/Muc1 is upregulated to control inflammation during airway bacterial infection. Using a lung epithelial cell line (A549 cells) as well as normal human bronchial epithelial cells fully differentiated at an air-liquid interface, we found that neutrophil elastase (NE) stimulated MUC1 production via a transcriptional mechanism. Furthermore, several lines of indirect evidence suggested that TNF-( was a critical component of the pathway by which NE induced MUC1 transcription. We hypothesize that airway inflammation is controlled by the levels of MUC1/Muc1 in the lung, which are regulated by TNF-(. The specific aims of this application are: (1) to characterize the signaling pathway involved in NE-induced MUC1 upregulation using both genetic and immunological methods in vitro and (2) to demonstrate, using various genetically engineered mice, that airway inflammation resulting from PA infection is controlled by NE-induced TNF-( activation, which in turn upregulates MUC1 levels in the lung. Successful accomplishment of the proposed studies will shed significant insights into our current understanding of the regulation of airway inflammation and will provide pharmacological strategies to control excessive and prolonged airway inflammation during airway bacterial infection. Relevance to public: Successful completion of this project will help us better understand airway inflammation and develop pharmacological strategies toward the prevention and treatment of excessive airway inflammation associated with bacterial infection.