Enhancing Neutrophil Responses to Counter MDR Gram Negative Bacterial Pneumonia

 描述（由申请方提供）：本申请的主要目的是测试一种潜在的宿主导向治疗剂，以增强中性粒细胞对广泛耐药（XDR）革兰氏阴性病原体肺炎克雷伯菌和铜绿假单胞菌的杀灭，这些病原体在呼吸机相关性肺炎（VAP）中普遍存在。XDR革兰氏阴性病原体的出现和有限的抗菌药物选择对这些患者的管理提出了越来越大的挑战。增强宿主免疫应答以对抗感染可能为常规抗菌剂提供一种新的辅助方法，特别是在免疫力减弱或免疫抑制的重症患者中，这些患者通常易受这些病原体的影响。血小板反应蛋白-1（TSP-1）是一种多功能的细胞外基质糖蛋白，参与细胞-细胞和细胞-基质的相互作用，在炎症过程中释放B，通过抑制中性粒细胞丝氨酸蛋白酶（NSP）活性抑制中性粒细胞对微生物的杀伤。我们的初步数据表明，TSP-1可能提供了一个以前未被认识到的，内源性抑制机制，以对抗NSP和削减组件的微生物杀伤武器库。先前的报道确定了TSP-1的II型重复结构域内的区域，其与丝氨酸蛋白酶抑制剂的Kazal家族中发现的共有序列具有惊人的相似性。我们最近已经确定了候选的小分子抑制剂，可以针对TSP-1的III型重复区域内产生的主要空腔。本申请的主要假设是，可能破坏TSP-1/嗜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肺炎克雷伯氏菌和铜绿假单胞菌的微生物杀灭，这两种病原体是两种主要的VAP病原体，治疗选择很少。R21是一个概念验证的“实验室”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XDR临床分离株的嗜中性粒细胞微生物杀伤。R33是转化或“床边”阶段，其中我们将检查基于TSP-1的小分子化合物是否将利用来自疑似VAP患者的嗜中性粒细胞改善XDR病原体的体外微生物杀灭。这种方法可以作为一种新的辅助治疗的基础，现有的抗微生物方案，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.