Enhancing Neutrophil Responses to Counter MDR Gram Negative Bacterial Pneumonia

 描述(申请人提供)：本申请的主要目标是测试一种潜在的宿主导向疗法，以增强对广泛耐药(XDR)革兰氏阴性病原体肺炎克雷伯菌和铜绿假单胞菌的中性粒细胞的杀灭作用，这两种细菌在呼吸机相关肺炎(VAP)中很常见。XDR革兰氏阴性病原体的出现和有限的抗菌药选择对这些患者的管理提出了越来越大的挑战。增强宿主免疫反应以对抗感染可能为传统抗菌药提供一种新的辅助方法，特别是在免疫功能减弱或免疫抑制通常容易受到这些病原体影响的危重HOSS患者。我们发现了一种新的机制，即参与细胞-细胞和细胞-基质相互作用的多功能细胞外基质糖蛋白-1(TSP-1)，并在炎症过程中释放多种细胞，通过抑制中性粒细胞丝氨酸蛋白酶(NSP)的活性来抑制中性粒细胞的微生物杀伤。我们的初步数据表明，TSP-1可能提供了一种以前未被认识的内源性抑制机制，以对抗NSP并减少微生物杀伤库的成分。以前的报告发现，TSP-1的II型重复结构域中的区域与在Kazal丝氨酸蛋白酶抑制剂家族中发现的共识序列惊人地相似。我们最近发现了候选的小分子抑制剂，它们可能靶向TSP-1的III型重复区域内产生的一个主要空洞。这一应用的主要假设是，可能破坏TSP-1/中性粒细胞丝氨酸蛋白酶相互作用的小分子化合物可以增强对XDR肺炎克雷伯菌和铜绿假单胞菌的微生物杀灭，这两种主要的VAP病原体几乎没有治疗选择。R21是一个概念验证的“长凳”阶段，我们将使用小鼠模型在体外和体内检查小分子化合物是否增加中性粒细胞对XDR临床分离株的微生物杀灭作用。R33是翻译或“床边”阶段，我们将在这里检查基于TSP-1的小分子化合物是否会改善利用疑似VAP患者的中性粒细胞在体外对XDR病原体的杀灭作用。这种方法可以作为现有抗微生物疗法的新辅助疗法的基础，以减少肺部的细菌负荷。

 DESCRIPTION (provided by applicant): The main goal of this application is to test a potential host-directed therapeutic to enhance neutrophil microbial killing of extensively drug resistant (XDR) gram negative pathogens Klebsiella pneumoniae and Pseudomonas aeruginosa that are prevalent in ventilator-associated pneumonia (VAP). The emergence of XDR gram negative pathogens and the limited number of antimicrobial options present a rising challenge for the management of these patients. Enhancing the host immune response to fight infection may afford a novel, adjunct approach to conventional antimicrobials, particularly in critically ill hoss with waning immunity or immunosuppression that are often vulnerable to these pathogens. We have identified a novel mechanism by which thrombospondin-1 (TSP-1), a multifunctional extracellular matrix glycoprotein involved in cell-cell and cell-matrix interactions and released b a variety of cells during inflammation, restrains neutrophil microbial killing through inhibition o neutrophil serine protease (NSP) activity. Our preliminary data indicates that TSP-1 may provide a previously unrecognized, endogenous inhibitory mechanism to counter NSPs and curtail components of the microbial killing arsenal. Previous reports identified regions within the type II repeats domain of TSP-1 that show striking similarity to the consensus sequence found among the Kazal family of serine protease inhibitors. We have recently identified candidate small molecule inhibitors that may target a major cavity created within the type III repeats region of TSP-1. The major hypothesis of this application is that small molecule compounds that potentially disrupt TSP-1/neutrophil serine protease interaction can enhance microbial killing of XDR Klebsiella pneumoniae and Pseudomonas aeruginosa, which are two major VAP pathogens with few treatment options. The R21 is a proof-of-concept "bench" phase where we will examine whether small molecule compounds increase neutrophil microbial killing of XDR clinical isolates in vitro and in vivo using a mouse model. The R33 is the translational or "bedside" phase where we will examine whether TSP-1 based small molecule compounds will improve in vitro microbial killing of XDR pathogens utilizing neutrophils from suspected VAP patients. This approach may serve as the basis for a novel adjunct therapy to existing anti-microbial regimens that reduce bacterial burden in the lungs.