OXIDATIVE NEUTROPHIL MICROBICIDAL MECHANISMS

氧化性中性粒细胞杀菌机制

• 批准号: 3139099
• 负责人: HENRY ROSEN
• 金额: $ 14.34万
• 依托单位: SWEDISH MEDICAL CENTER, FIRST HILL
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-03-01 至 1993-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3139099
• 关键词: Escherichia coli; bacterial proteins; bactericidal immunity; cell free system; cellular respiration; chlorine; chronic granulomatous disease; cytochromes; electron transport; enzyme mechanism; enzyme structure; flavins; genetic strain; growth media; high performance liquid chromatography; human subject; hydrogen peroxide; immunotoxicity; microorganism growth; microorganism immunology; microorganism metabolism; myeloperoxidase; neutrophil; oxidation; oxidizing agents; quinones; radiotracer; reduction; succinate dehydrogenase

Long-term objectives are to characterize oxidative microbicidal mechanisms within human neutrophils (PMN) with a view towards developing rational therapeutic interventions for infected patients with defects in PMN number or function. Because of the great number and complexity of PMN microbicidal systems, the proposed studies will focus on microbicidal properties of a single PMN- derived enzyme, myeloperoxidase (MPO). Specific aims are to identify early MPO-induced biochemical changes in target organisms and to evaluate the metabolic consequences of these changes. The goal is to determine which biochemical changes correlate best, and are perhaps responsible for, loss of replicative ability (viability). Preliminary studies have indicated a decrease in E. coli respiration that correlates well with loss of viability (r=0.97), suggesting a relationship between damage to the microbial respiratory chain and microbicidal activity. In the sequence of respiratory electron transport, from nutrients through dehydrogenates, quinones, and terminal oxidase cytochromes to 02, the principal MPO-mediated lesions appear to be in the dehydrogenase group with other components of the chain left substantially intact. Continuing investigations will focus on damage to individual dehydrogenase components: iron-sulfur centers and flavin cofactors. Metabolic consequences of impaired electron transport such as loss of transmembrane pH and electrochemical gradients (proton motive force), loss of active transport, and extensive ATP hydrolysis will be determined. Finally, attempts will be made to rescue organisms from MPO-mediated toxicity by providing growth conditions that bypass the need for products of MPO-oxidized systems. Successful rescue would suggest that damage to the bypassed systems was indeed responsible for the loss of viability observed under usual growth conditions. A further aim is to use the knowledge of MPO-mediated biochemical changes to distinguish MPO from other antimicrobial activity within intact PMNs. PMN microbicidal activity will be compared with MPO-specific changes in microbial structures and correlations will be sought. Specificity for MPO of the PMN-mediated changes will be confirmed using PMNs deficient in MPO (hereditary MPO-deficiency) or in H202 production (chronic granulomatous disease). These studies should identify microbial structures whose modification by PMN results in lethal injury. They may also offer clues for the design of new antimicrobial agents and suggest reasons why certain organisms are able to evade PMN-mediated host defense systems.

长期目标是表征氧化杀微生物剂