Mechanism of anti-inflammatory role of MUC1 during airway bacterial infection

描述（申请人提供）：尽管炎症是肺部感染过程中必不可少的宿主防御机制，但及时解决炎症对于宿主预防炎症细胞失控导致的肺损伤至关重要。最近，我们发现MUC1是一种表达于气道上皮细胞顶端表面的膜系粘蛋白，能够通过抑制toll样受体（TLR）5信号传导来控制气道铜绿假单胞菌（Pa）感染末端的炎症。在这项更新申请中，我们建议阐明MUC1在Pa感染期间抑制TLR5的机制。我们假设在Pa感染过程中，MUC1通过与TLR5的直接相互作用抑制TLR5信号，而TLR5是通过激活EGFR介导的，我们提出以下目的来验证这一假设。在Aim 1中，我们将通过遗传学和免疫学方法检查培养上皮细胞中MUC1和TLR5之间分子相互作用的细节，确定MUC1在气道Pa感染期间的抗炎作用是否由于其与TLR5的直接相互作用。在Aim 2中，我们将使用遗传学和免疫学方法确定在培养细胞中，EGFR对MUC1的酪氨酸磷酸化是否调节MUC1与TLR5的相互作用，并将使用EGFR缺陷小鼠验证EGFR的这种作用。在最后的Aim 3中，将使用培养细胞和体内动物实时监测从Pa感染到MUC1炎症解决的完整事件序列。这些实验的成功完成将提供MUC1在气道Pa感染过程中抗炎作用相关的详细分子相互作用，并为控制慢性炎症性肺部疾病（如COPD和囊性纤维化）的过度和长期肺部炎症特征提供可能的治疗策略。

DESCRIPTION (provided by applicant): Although inflammation is an essential host defense mechanism during lung infection, its timely resolution is critical for the host to prevent lung injuries resulting from uncontrolled inflammatory cells. Recently we discovered that MUC1, one of the membrane-tethered mucins expressed on the apical surface of airway epithelial cells, has an ability to control inflammation at the end of airway Pseudomonas aeruginosa (Pa) infection by suppressing toll-like receptor (TLR)5 signaling. In this renewal application, we propose to elucidate the mechanism by which MUC1 suppresses TLR5 during Pa infection. We hypothesize that MUC1 suppresses TLR5 signaling during Pa infection by a direct interaction with TLR5 which is mediated through activation of EGFR and propose the following aims to test the hypothesis. In Aim 1, we will determine whether anti-inflammatory effect of MUC1 during airway Pa infection is due to its direct interaction with TLR5 by examining the details of molecular interactions between MUC1 and TLR5 in cultured epithelial cells using both genetic and immunological methods. In Aim 2, we will determine whether the interaction of MUC1 with TLR5 is regulated by tyrosine phosphorylation of MUC1 by EGFR in cultured cells using genetic as well as immunological methods and such role of EGFR will be verified using EGFR deficient mice. In the final Aim 3, the complete sequence of the events that take place from Pa infection to the resolution of inflammation by MUC1 will be monitored in real time using both cultured cells and in vivo animals. Successful completion of these experiments will provide the detailed molecular interactions associated with the anti-inflammatory role of MUC1 during airway Pa infection and should provide insights into possible therapeutic strategies to control excessive and prolonged lung inflammation characteristic of chronic inflammatory lung diseases such as COPD and cystic fibrosis. PUBLIC HEALTH RELEVANCE: Chronic lung inflammatory diseases such as COPD, asthma and cystic fibrosis develop as a result of failure to control lung inflammation in a timely manner. MUC1 is a new anti- inflammatory molecule that prevents excessive inflammation during airway infection. Understanding how MUC1 controls excessive lung inflammation will help us to better understand the pathophysiology of these lung diseases and may provide insights into possible therapeutic strategies to treat these inflammatory lung diseases.