RICKETTSIA RICKETTSII IN HUMAN ENDOTHELIAL CELLS

人内皮细胞中的立克次体

• 批准号: 3127211
• 负责人: DAVID J SILVERMAN
• 金额: $ 28.03万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 1980
• 资助国家: 美国
• 起止时间: 1980-12-01 至 1998-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3127211
• 关键词: Rickettsia; Rocky Mountain spotted fever; bacterial cytopathogenic effect; cytolysis; electron microscopy; free radical scavengers; host organism interaction; human tissue; hydrogen peroxide; leukocyte oxidative burst; oxidative stress; phagocytosis; superoxide dismutase; superoxides; tissue /cell culture; vascular endothelium; virulence

DESCRIPTION (Adapted from the Applicant's Abstract): Rocky Mountain spotted fever, caused by Rickettsia rickettsii, is an important infection in the United States owing to the extreme severity of untreated cases, the difficulty in establishing an early clinical or laboratory diagnosis, and the lack of an effective means of prevention. Transmitted by tick bite, the organisms are spread by the bloodstream throughout the body, entering and injuring endothelial cells of the microcirculation. The in vitro model of Rickettsia rickettsii endothelial cell interaction utilized in Dr. Silverman's laboratory has led during the current funding cycle to highly productive research with establishment of important new concepts of infectious disease pathogenesis. The proposed study will examine cultured human endothelial cells infected with the virulent Sheila Smith strain and the avirulent Iowa strain of R. rickettsii and the virulent Breinl and avirulent Madrid E strains of R. prowazekii. Current evidence from Dr. Silverman's laboratory strongly suggests that R. rickettsii induced endothelial cell injury is mediated by reactive oxygen species. Superoxide radical has been detected in large amounts in culture supernatants during internalization of rickettsiae into endothelial cells. The investigator postulates that injury is initiated as a result of aborted phagocytosis of the organism that results in an oxidative burst. The oxidative burst releases superoxide at the cell surface which is converted to toxic H202 by extracellular superoxide dismutase in the endothelial glycocalyx. H202 readily passes through the plasma membrane and is capable of directly causing peroxidation of membrane lipids, or it may react with additional superoxide to produce the even more toxic hydroxyl radical. Catalase and pyruvate are known scavengers of H202 and protect endothelial cells from hydrogen peroxide generated from superoxide. The hypothesis that R. rickettsii causes abortive phagocytosis leading to endothelial cell injury following pretreatment with these scavengers, measuring intracellular glutathione and comparing them to comparable experiments with the Iowa, Breinl and Madrid E strains.

描述（改编自申请人的摘要）：落基山 由立克次体引起的斑疹热是一种重要的 在美国的感染，由于极端严重的 未经治疗的病例，难以建立早期临床或 实验室诊断，缺乏有效的预防手段。 通过蜱叮咬传播，生物体通过血液传播 在整个身体，进入和损伤内皮细胞的 微循环 立克次体与内皮细胞相互作用的体外模型 在西尔弗曼博士的实验室中使用， 循环到高生产力的研究与建立重要的新的 传染病发病机制的概念。 拟定的研究将 检查培养的人内皮细胞感染的毒性 SheilaSmith株和R.Iowa无毒力株。立克次体和 强毒株Breinl和弱毒株马德里E。prowazekii。 西尔弗曼博士实验室目前的证据有力地表明， R.立克次体诱导的内皮细胞损伤是由反应性 氧物种。 超氧自由基已被大量检测到 在立克次体内化到 内皮细胞 研究者假设损伤是由 由于生物体的吞噬作用中止， 氧化爆发 氧化爆发在细胞中释放出超氧化物 通过细胞外超氧化物转化为有毒H2O2的表面 内皮糖萼中的歧化酶。 H2O2容易通过 能直接引起细胞膜的过氧化， 膜脂，或者它可以与额外的超氧化物反应， 毒性更大的羟基自由基 已知过氧化氢酶和丙酮酸 清除剂H2O2和保护内皮细胞免受过氧化氢 由超氧化物生成。 假设R.立克次氏体病因 吞噬作用失败导致内皮细胞损伤 用这些清除剂预处理，测量细胞内谷胱甘肽 并将其与爱荷华州、布雷内尔和 马德里E菌株。