Pathogenic Mechanism for Lung Infection in Mucoid Pseudomonas

描述(由申请人提供)： Pi-Dennis E.Ohman，Ph.D.标题：粘液性铜绿假单胞菌肺部感染的致病机制许多VA患者容易受到机会致病菌铜绿假单胞菌的感染。这可能是肺气肿、慢性支气管炎、癌症和免疫抑制药物治疗的并发症。接触这种无处不在的细菌可导致医院感染，这是通过呼吸机、导管、腰椎穿刺术和普通外科手术常见的。铜绿假单胞菌对大多数抗生素具有高度耐受性或抗药性，因此很难控制这类感染，从而导致高死亡率。这项研究的目的是提高我们对保护性囊状多糖藻酸盐的生物合成的了解，藻酸盐是由铜绿假单胞菌产生的一种毒力因子。在慢性呼吸道感染(如COPD)期间，体内适应性突变可导致这种胞外多糖的过度生产，从而使临床分离株表现出粘液菌落形态。提高对铜绿假单胞菌致病机制的认识，将有助于加强对该菌引起的肺部疾病的防治。大多数用于生产藻酸盐的酶聚集在一个由12个基因组成的操纵子中。在这项研究中，我们将：(1)评估海藻酸盐的主要前体GDP-甘露糖酸盐形成过程中的酶反应，(2)表征海藻酸盐聚合和细胞膜转移的机理，(3)表征海藻酸盐乙酰化的机理，它具有抗吞噬和厚生物膜的特性，(4)与结构生物学家合作，确定海藻酸盐生物合成蛋白的结构，以更好地了解聚合-分泌复合体。这项研究的长期目标是了解藻酸盐生物合成所需的所有成分的功能，藻酸盐现在被认为是肺部感染过程中的一个关键毒力因子。所获得的信息可能对开发治疗铜绿假单胞菌感染的新治疗方法至关重要。这些研究结果也将有助于我们全面了解细菌的衣壳生物合成，这是细菌毒力的一个常见机制，以避免宿主免疫反应。 公共卫生相关性： 相关性Pi-Dennis E.Ohman，Ph.D.标题：粘液性铜绿假单胞菌肺部感染的致病机制铜绿假单胞菌感染是我们退伍军人中的一个重大问题。由于肺气肿、慢性支气管炎、慢性阻塞性肺疾病和其他疾病的并发症，许多VAMC患者容易发生铜绿假单胞菌机会性感染。呼吸机治疗期间的医院感染也很常见。铜绿假单胞菌在肺部感染过程中的一个关键毒力因素是产生一种名为藻酸盐的胶囊状多糖。更好地了解藻酸盐生物合成的复杂机制可能会导致新的治疗方法。这项工作对退伍军人管理局卫生系统也很重要，因为假单胞菌感染由于其天生的抗生素耐药性而很难治疗。

DESCRIPTION (provided by applicant): ABSTRACT PI - Dennis E. Ohman, Ph.D. Title: Pathogenic Mechanism for Lung Infection in Mucoid Pseudomonas Many VA patients are susceptible and succumb to infections with the opportunistic pathogen, Pseudomonas aeruginosa. This can occur as a complication of emphysema, chronic bronchitis, cancer and immunosuppressive drug therapy. Exposure to this ubiquitous bacterium can result in nosocomial infections, which is common via respiratory ventilators, catheters, lumbar punctures and general surgery. P. aeruginosa is highly tolerant or resistant to most antibiotics, making it difficult to control such infections, which leads to a high mortality rate. The goal of this research is to improve our understanding of the biosynthesis of a protective capsule-like polysaccharide called alginate, which is produced as a virulence factor by P. aeruginosa. During chronic respiratory infections (e.g., COPD), adaptive mutations in vivo can lead to the over production of this exopolysaccharide such that clinical isolates demonstrate a mucoid colony morphology. Improving our understanding of this pathogenic mechanism in P. aeruginosa will enhance the management of pulmonary disease caused by this bacterium. Most of the enzymes for the production of alginate are clustered in an operon of 12 genes. In this study, we will: (1) evaluate the enzyme reactions in the formation of the main precursor of alginate, GDP-Mannuronate, (2) characterize the mechanism of alginate polymerization and cytoplasmic membrane transfer, (3) characterize the mechanism of alginate acetylation, which confers anti-phagocytic and thick biofilm properties, and (4) in collaboration with a structural biologist, determine the structures of alginate biosynthetic proteins to better understand the polymerization-secretion complex. The long-term goal of this research is to understand the functions of all of the components required for the biosynthesis of alginate, which is now recognized as a critical virulence factor during pulmonary infection. The information gained could be vital for the development of new therapeutic approaches in the treatment of P. aeruginosa infections. The results of these studies will also contribute to our overall understanding of bacterial capsule biosynthesis, which is a common mechanism of bacterial virulence for avoiding the host immune response. PUBLIC HEALTH RELEVANCE: Relevance PI - Dennis E. Ohman, Ph.D. Title: Pathogenic Mechanism for Lung Infection in Mucoid Pseudomonas Infection with the bacterium Pseudomonas aeruginosa is a significant problem among our veterans. Many VAMC patients are susceptible to opportunistic infections with P. aeruginosa due to complications with emphysema, chronic bronchitis, COPD and other disorders. Nosocomial infection during treatment with respiratory ventilators is also common. A key virulence factor of P. aeruginosa during pulmonary infection is the production of a capsule-like exopolysaccharide called alginate. A better understanding of the complex mechanisms involved in alginate biosynthesis could lead to novel therapies. This work is also of importance to the VA health system because Pseudomonas infections are very difficult to treat due to its innate antibiotic resistance.