HOST RESPONSE TO CYTOTOXIC PROTEINS

高死亡率与医院内肺部感染有关 致铜绿假单胞菌。因为目前的抗生素疗法与 这种感染的死亡率为50%-80%，改进的治疗方法 显然，预防和治疗是必要的。空域的灌输 PA103是铜绿假单胞菌的一种细胞毒性菌株，它能重现肺损伤和 脓毒症见于许多院内肺炎患者； 细菌的滴注会导致肺上皮损伤，菌血症， 实验动物的器官衰竭和死亡。在过去的4年里， 我们两个实验室在细菌基因实验方面进行了合作 和动物生理学实验导致了对 新型铜绿假单胞菌胞外产物的合成和 AIII型胞外酶S的分泌和协同调控 分泌系统。我们之前的调查表明， 肺损伤及向循环扩散的PA103空域 与细菌产生胞外酶S相关。其中两个 胞外酶产生和分泌的新型胞外产物 S是一种新的细胞毒素ExoU和PcrV，是耶尔森氏菌的同源物 鼠疫V抗原，可能影响宿主细胞因子的产生。我们的 假设这两种细菌产物是主要的毒力 铜绿假单胞菌产品及针对这些产品的治疗 将防止因传播而造成的局部和全身伤害 看起来像是感染了。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 内毒素对肺的单独作用及联合作用 损伤、肺部炎症和全身炎症反应。我们 将利用同基因转座子PA103菌株，这些菌株选择性地 缺少ExoU、PcrV或这两个基因的基因。这两个 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基因缺陷小鼠 以确定脂多糖结合蛋白的作用 动物体内的产品能抵抗内毒素的影响。我们会 确定这两种细菌产物是否与IL-10有关 体内产生IL-10和阻断IL-10可改善局部宿主 防守。

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.