OXIDATIVE NEUTROPHIL MICROBICIDAL MECHANISMS

长期目标是表征氧化杀微生物剂 人中性粒细胞（PMN）内的机制， 为感染患者制定合理的治疗干预措施 PMN数量或功能有缺陷。 因为伟大的 PMN杀微生物系统的数量和复杂性，建议 研究将集中在单个PMN的杀微生物特性上， 髓过氧化物酶（MPO）。 具体的目标是 鉴定靶生物中MPO诱导早期生化变化 并评估这些变化的代谢后果。 的 目标是确定哪些生化变化最相关， 可能是导致复制能力丧失的原因 （生存能力）。 初步研究表明，E。 大肠杆菌的呼吸与生存力的丧失密切相关 （r=0.97），表明微生物的损害与 呼吸链和杀微生物活性。 序列中 呼吸电子传递，从营养物质， 三羧酸，醌，和末端氧化酶细胞色素到02， MPO介导的主要病变似乎位于 脱氢酶基团与链的其他组分一起离开 基本上完好无损。 继续调查将集中在 对单个脱氢酶组分的损害：铁硫中心 和黄素辅因子。 受损电子的代谢后果 转运，如跨膜pH和电化学损失 梯度（质子动力），主动运输的损失，以及 将测定广泛的ATP水解。 最后，尝试 将通过以下方式将生物体从MPO介导的毒性中拯救出来 提供生长条件，绕过对产品的需要， MPO-氧化系统。 成功的营救意味着 对被绕过的系统确实负责的损失， 在正常生长条件下观察到的活力。 另一个目的 是利用MPO介导的生化变化的知识， 区分MPO与其他抗微生物活性， PMNs。 将比较PMN杀微生物活性与MPO特异性 将寻求微生物结构的变化和相关性。 将确认PMN介导的变化对MPO的特异性 使用MPO缺陷（遗传性MPO缺陷）或H2 O2缺陷的PMN 慢性肉芽肿病（chronic granulomatous disease） 这些研究应 鉴定微生物结构，其被PMN修饰导致 致命伤 它们也可能为新的设计提供线索。 抗菌剂，并提出为什么某些生物体 能够逃避PMN介导的宿主防御系统。

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.