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

描述(申请人提供)：虽然炎症是肺部感染过程中的一种重要的宿主防御机制，但它的及时消退对于宿主预防因炎症细胞失控而导致的肺损伤至关重要。最近我们发现，表达于呼吸道上皮细胞顶端的膜性粘蛋白MUC1通过抑制Toll样受体(TLR5)信号转导通路，具有抑制肺炎铜绿假单胞菌(PA)感染后炎症反应的能力。在这一更新应用中，我们建议阐明MUC1在PA感染过程中抑制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，并提出以下目的来验证这一假说。在目标1中，我们将通过遗传学和免疫学方法研究MUC1和TLR5在培养的上皮细胞中分子相互作用的细节，来确定MUC1在呼吸道PA感染过程中的抗炎作用是否源于它与TLR5的直接相互作用。在目标2中，我们将使用遗传学和免疫学方法来确定培养细胞中MUC1与TLR5的相互作用是否受EGFR对MUC1的酪氨酸磷酸化的调节，并将在EGFR缺陷的小鼠身上验证这种作用。在最终目标3中，将使用培养细胞和活体动物实时监测从PA感染到MUC1消退炎症所发生的事件的完整序列。这些实验的成功完成将提供与呼吸道PA感染期间MUC1抗炎作用相关的详细分子相互作用，并将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.