A New Pathway for Neutrophil-induced Airway Inflammation

描述（由申请人提供）：在某些情况下，多形核白细胞（PMN）募集到气道炎症部位可通过产生蛋白酶、活性氧、促炎细胞因子和趋化因子导致组织损伤。PMN被认为在急性肺部疾病和慢性阻塞性肺疾病中发挥作用，并有助于囊性纤维化的炎症和肺损伤。我们在此描述了PMN内流和气道损伤的新途径，可能代表某些肺部疾病的新治疗靶点。特别是，当胶原蛋白被化学或酶降解时，产生一种三肽PGP，它在体外对PMN具有趋化作用。在体内，气道暴露于PGP引起PMN的显著流入，但不是单核细胞。气道长期暴露于PGP会导致肺泡增大和右心室肥厚。采用电喷雾电离-液相色谱-质谱法（ESI-LC-MS/MS）检测内毒素（LPS）暴露动物气道中的PGP。此外，肽实质上有助于PMN流入炎症气道。PGP的趋化活性显然是由于与CXC趋化因子的受体结合基序的特殊结构相关性，如IL-8，包含该序列或类似物。我们设计了一种具有精氨酸-苏氨酸-精氨酸（RTR）序列的新型肽，它可以结合PGP并有效地阻断该肽的体外趋化活性和体内病理生理作用。由于PGP和趋化因子之间的共享结构，RTR也明显抑制CXC趋化因子的活性。因此，RTR代表了一种潜在的治疗药物，可以阻断炎症的趋化因子和PGP途径。这些结果导致了该应用程序的以下目标。1. 确定PGP是否结合CXC趋化因子受体(R)并激活CXCR偶联效应通路。2. 评估气道炎症期间产生的含PGP肽的谱，以及PGP是否在急性炎症期间向气道招募PMN。3. 确定pgp介导的肺泡增大和右心室肥厚是否需要PMN。4. 评估PGP与CXC趋化因子在持续lps介导的肺部疾病模型中的相对病理生理作用。5. 在lps介导的肺部疾病模型中，测试RTR作为PGP和CXC趋化因子途径的拮抗剂。

DESCRIPTION (provided by applicant): Under certain circumstances, polymorphonuclear leukocyte (PMN) recruitment to sites of airway inflammation can lead to tissue damage via the production of proteases, reactive oxygen species, proinflammatory cytokines and chemokines. PMN are thought to play a role in acute lung diseases as well as chronic obstructive pulmonary diseases and contribute to inflammation and lung damage in cystic fibrosis. We herein describe a novel pathway of PMN influx and damage to the airways that may represent a new therapeutic target for certain pulmonary diseases. In particular, when collagen is chemically or enzymatically degraded a tripeptide, PGP, is generated that is chemotactic for PMN in vitro. In vivo, airway exposure to PGP elicits a marked influx of PMN, but not monocytes. More chronic airway exposure to PGP causes alveolar enlargement and right ventricular hypertrophy. Using electrospray ionization-liquid chromatography- mass spectrometry (ESI-LC-MS/MS), PGP is detected in the airways of animals exposed to endotoxin (LPS). In addition, the peptide substantially contributes to PMN influx into inflamed airways. The chemotactic activity of PGP apparently results from an extraordinary structural relatedness to a receptor binding motif of CXC chemokines, like IL-8 that contain this sequence or a close analog. We have designed a novel peptide with the sequence arginine-threonine-arginine (RTR) that binds PGP and potently blocks the peptide's in vitro chemotactic activity and in vivo pathophysiologic effects. RTR also inhibits CXC chemokine activity apparently as a result of the shared structure between PGP and the chemokines. Thus, RTR represents a potential therapeutic agent that can block both the chemokine and PGP pathways of inflammation. These results have led to the following goals for this application. 1. Determine whether PGP binds CXC chemokine receptors (R) and activates CXCR coupled effector pathways. 2. Evaluate the spectrum of PGP-containing peptides that are produced during airway inflammation and whether PGP recruits PMN to the airways during acute inflammation. 3. Determine whether PMN are necessary for PGP-mediated alveolar enlargement and right ventricular hypertrophy. 4. Evaluate the relative pathophysiologic roles of PGP as compared to CXC chemokines in a model of persistent LPS-mediated pulmonary disease. 5. Test RTR as an antagonist of the PGP and CXC chemokine pathways in the LPS-mediated pulmonary disease model.