Therapeutics for Chronic Lung Diseases: Antagonists of PGP, Chemokines and CXCR

在这个建议中，我们描述了一个新的信号通路，PMN流入和气道损伤可能在慢性阻塞性肺疾病（COPD）的启动或辅助因子中发挥作用。具体地说，胶原蛋白的化学或酶分解释放出三肽、PGP和/或相关的含PGP的序列，这些序列在体外对PMN具有趋化作用。我们证明PGP进入气道会引起PMN的大量涌入，而不是单核细胞。值得注意的是，PGP的PMN趋化活性可能是由于其与CXC趋化因子（如IL-8）的受体结合域具有显著的结构相关性，这些趋化因子含有该胶原蛋白序列或类似物。长时间的气道暴露于这种肽导致肺泡增大和右心室肥厚，从而重现COPD的各个方面。此外，使用电喷雾电离-液相色谱-质谱（ESI-LC-MS/MS）， PGP在暴露于雾化LPS的动物气道中被发现，并显著促进PMN内流。通过在N和/或C端系统地将L与P的D异构体交换，我们将PGP从CXC受体(R)激动剂转化为部分激动剂，并最终转化为拮抗剂。（D-P）G（D-P）在体外可拮抗PGP和IL-8趋化活性。我们发现PGP存在于几乎所有COPD患者的支气管肺泡灌洗液（BALF）和/或痰液中，但不存在于对照组或哮喘患者。此外，COPD患者而非对照个体的痰中含有纯化胶原在体外生成PGP所需的所有酶机制。总的来说，这些发现使我们假设PGP代表了一种新的COPD生物标志物，可能有助于疾病的发生。因此，我们推测PGP是COPD的一个有吸引力的治疗靶点。这些假设将通过多学科，多方面的方法进行测试，以开发（D-P）G（D-P）作为一种新的治疗方法，可以同时抑制中性粒细胞炎症的IL- 8和PGP途径，因此可能对慢性阻塞性肺病的治疗有用。此外，我们将评估PGP作为COPD的新型生物标志物以及（D-P）G（D-P）作为治疗药物的潜在效用的预测因子。

In this proposal, we describe a new pathway signaling PMN influx and damage to the airways that may play a role as an initiator or cofactor for chronic obstructive pulmonary disease (COPD). Specifically, chemical or enzymatic breakdown of collagen releases a tripeptide, PGP, and/or a related PGP-containing sequence that is chemotactic for PMN in vitro. We demonstrate that introduction of PGP into the airways causes a robust influx of PMN, but not monocytes. Remarkably, the PMN chemotactic activity of PGP may be due to a marked structural relatedness to a receptor binding domain of CXC chemokines such as IL-8 which contain this collagen sequence or a close analog. Prolonged airway exposure to this peptide causes alveolar enlargement and right ventricular hypertrophy and thus recapitulates aspects of COPD. Furthermore, using electrospray ionization-liquid chromatography-mass spectrometry (ESI-LC-MS/MS), PGP is found in the airways of animals exposed to aerosolized LPS and markedly contributes to PMN influx. We have converted PGP from a CXC receptor (R) agonist to a partial agonist and finally an antagonist by systematically exchanging L with D isomers of P on the N and/or C termini. (D-P)G(D-P) antagonizes PGP as well as IL-8 chemotactic activity in vitro. We have found that PGP is present in bronchoalveolar lavage fluids (BALF) and/or sputum from virtually all COPD patients but not controls or asthmatics. Furthermore, sputum from COPD patients but not control individuals contains all the enzymatic machinery necessary for the ex vivo generation of PGP from purified collagen. Collectively, these findings lead us to hypothesize that PGP represents a novel biomarker for COPD that may contribute to disease. As a corollary, we theorize that PGP represents an attractive therapeutic target in COPD. These hypotheses will be tested via a multidisciplinary, multifaceted approach to develop (D-P)G(D-P) as a new therapeutic that will simultaneously inhibit both the IL- 8 and PGP pathways of neutrophilic inflammation and, consequently, may be useful in the management of COPD. In addition, we will evaluate PGP as a novel biomarker for COPD as well as a prognosticator of potential utility of (D-P)G(D-P) as a therapeutic agent.