HOST RESPONSE TO CYTOTOXIC PROTEINS

高死亡率与医院肺部感染有关， 到铜绿假单胞菌 由于目前的抗生素治疗与 这种感染的死亡率为50- 80%， 显然需要预防和治疗。空域灌输 PA 103，铜绿假单胞菌的细胞毒性菌株，重现肺损伤， 败血症见于许多医院获得性肺炎患者; 细菌的滴注引起肺上皮损伤，菌血症， 器官衰竭和实验动物死亡。 在过去的四年里， 我们两个实验室合作进行细菌遗传实验 以及动物生理学实验， 本发明合成了新的铜绿假单胞菌胞外产物， 由III型酶分泌并与外切酶S协调控制 分泌系统 我们之前的调查已经证明 肺损伤和空气PA 103扩散到循环中 与细菌产生胞外酶S有关。 两 由胞外酶产生和分泌的新型胞外产物 它们是一种新的细胞毒素ExoU和耶尔森氏菌的同源物PcrV。 鼠疫V抗原，其可影响宿主细胞因子的产生。 我们 假设这两种细菌产物是主要的毒力 铜绿假单胞菌的产物和针对这些产物的疗法 可以防止由于传播引起的局部和全身损伤 看到这种感染。 为了证明这一假设，我们将比较 这些新发现的细菌产物对铜绿假单胞菌的影响 内毒素对肺的单独和联合作用 损伤、肺部炎症和全身炎症反应。 我们 将利用同基因转座子PA 103菌株， 缺失ExoU基因、PcrV基因或这两种基因。 这2 重组蛋白也可用于实验，我们有 获得特异性内毒素拮抗剂和遗传缺陷小鼠 脂多糖结合蛋白，以确定这些影响 产品在动物体内抵抗内毒素的影响。 我们将 确定这两种细菌产物是否负责IL-10 如果IL-10的阻断改善了局部宿主 防御

High mortality rates are associated with nosocomial lung infections due to P.aeruginosa. As current antibiotic therapies are associated with a 50-80 percent mortality in this infection, improved methods for prevention and therapy clearly are needed. The airspace instillation of PA103, a cytotoxic strain of P.aeruginosa, recreates the lung injury and sepsis seen in many of the patients with nosocomial pneumonia; the instillation of the bacteria causes lung epithelial injury, bacteremia, organ failure and death of experimental animals. Over the last 4 years, our two laboratories have collaborated on bacterial genetic experiments and animal physiology experiments that have led to the discovery of novel P.aeruginosa extracellular products which are synthesized and secreted and coordinately controlled with exoenzyme S by a type III secretory system. Our previous investigations have documented that the lung injury and dissemination of the airspace PA103 to the circulation correlated with the production of exoenzyme S by the bacteria. Two of the novel extracellular products produced and secreted with exoenzyme S are ExoU, a novel cytotoxin, and PcrV, a homolog of the Yersinia pestis V antigen, which may affect host cytokine production. Our hypothesis is that these two bacterial products are the major virulence products of P.aeruginosa and therapies directed against these products would prevent the local and systemic injury due to the dissemination seen with this infection. To prove this hypothesis, we will compare the effects of these newly discovered bacterial products to P.aeruginosa endotoxin in terms of their individual and combined effects on lung injury, lung inflammation and the systemic inflammatory response. We will utilize isogenic transposon PA103 strains that are selectively missing the genes for ExoU, for PcrV or both of these genes. These 2 recombinant proteins are also available for experiments and we have obtained specific endotoxin antagonists and genetically deficient mice for lipopolysaccharide binding protein to determine the effects of these products in animals resistant to the effects of endotoxin. We will determine whether these two bacterial products are responsible for IL-10 production in vivo and if blockade of the IL-10 improves local host defense.