Regulatory Oxygenases in Vasculopathic Rickettsioses

血管病性立克次体病中的调节性氧化酶

• 批准号: 7806372
• 负责人: Sanjeev K. Sahni
• 金额: $ 22.58万
• 依托单位: UNIVERSITY OF ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-05-15 至 2011-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7806372
• 关键词: Actins; Acute; Address; Adenoviruses; Adhesions; Adult Respiratory Distress Syndrome; Algeria; Antioxidants; Apoptosis; Arthropods; Bacteria; Bacterial Infections; Behavior; Bilirubin; Biological; Biological Models; Biological Process; Blood; Blood Vessels; Brill' s Disease; Burundi; C3H/HeN Mouse; Carbon Monoxide; Catabolism; Cell Adhesion Molecules; Cell Survival; Cells; Centers for Disease Control and Prevention (U.S.); Cessation of life; Characteristics; Chelating Agents; Cytolysis; Cytoplasm; Data; Defense Mechanisms; Dermacentor; Dinoprostone; Disease; Disease Outbreaks; Dominant-Negative Mutation; Edema; Endothelial Cells; Endothelium; Enzymes; Epidemic; Epoprostenol; Exhibits; Ferritin; Fever; Functional disorder; Generations; Growth; Heme; Homeostasis; Human; Immune response; In Vitro; Inbred C57BL Mice; Individual; Infection; Infiltration; Inflammation; Inflammatory; Inflammatory Response; Intercellular adhesion molecule 1; Intervention; Iowa; Iron; Isoenzymes; Kinetics; Knockout Mice; Knowledge; Laboratories; Leukocytes; Life; Lipopolysaccharides; Logistics; Lung; Mediating; Molecular; Mouse Strains; Movement; Mus; Organ; Organism; Oxidants; Oxidation-Reduction; Oxidative Stress; Oxygenases; Pathogenesis; Pathologic; Pattern; Phospholipase; Physiological; Pneumonia; Predisposition; Prostaglandin Production; Prostaglandin-Endoperoxide Synthase; Prostaglandins; Protein Biosynthesis; Protein Isoforms; Publishing; Pulmonary Edema; Reaction; Reactive Oxygen Species; Regulation; Research Personnel; Rhipicephalus sanguineus; Rickettsia; Rickettsia Infections; Rickettsia rickettsii; Rocky Mountain Spotted Fever; Role; Scourge; Severities; Signal Transduction; Small Interfering RNA; Spottings; Stimulus; Stress; System; Therapeutic; Ticks; Tissues; Tropism; Typhus; Vascular Diseases; Vascular Endothelial Cell; Vascular Endothelium; Vascular Permeabilities; Vascular System; Virulence; Virulent; base; cell motility; cellular imaging; design; disability; heme oxygenase-1; improved; in vivo; in vivo Model; inhibitor/antagonist; insight; interstitial; mouse model; mutant; new therapeutic target; novel strategies; obligate intracellular parasite; pathogen; programs; research study; response; transmission process; vector

DESCRIPTION (provided by applicant): Pathogenic Rickettsia species are etiologic agents of some of the most severe bacterial diseases known to mankind worldwide. Among them are Rocky Mountain spotted fever and epidemic typhus caused respectively by R. rickettsii and R. prowazekii. Rickettsiae are obligate intracellular parasites characterized by tropism for vascular endothelium of their mammalian hosts. Accruing evidence indicates an important role for reactive oxygen species (ROS) in endothelial dysfunction and rickettsial pathogenesis. As an upholder of physiological homeostasis, endothelium maintains vessel tone and vascular permeability and regulates inflammatory responses to a plethora of noxious stimuli. Our published and preliminary data further suggest that: 1. Infection of endothelial cells (EC) induces the expression of heme oxygenase (HO)-1, an enzyme responsible for the degradation of pro-oxidant heme into biologically active molecules (bilirubin, carbon monoxide, and ferritin) with diverse cytoprotective functions; 2. Increased expression of cyclooxygenase (Cox)-2 during infection with spotted fever group (SFG) rickettsiae results in enhanced prostaglandin (PG) secretion; and 3. There are significant differences in the abilities of SF and typhus group (TG) organisms to trigger ROS generation and activate anti-oxidant defense mechanisms, likely due to distinct differences in their intracytoplasmic behavior. These observations have led to the hypothesis that regulation of HO and Cox enzyme systems and interplay between HO and Cox signaling mechanisms in the vasculature are critical determinants of host cell survival, onset/degree of inflammation, and changes in vascular permeability, all of which are critical determinants of pathologic manifestations of rickettsioses. The proposed studies are focused on elucidating heretofore unknown regulatory mechanisms controlling redox homeostasis, acute inflammation, and vascular permeability using infection of cultured human EC (in vitro) and disseminated endothelial infection of susceptible mice strains (in vivo) with SFG (R. rickettsii, R. conorii and R. australis) and TG (R. prowazekii, R. typhi) as independent model systems. Employing Rickettsia strains with varying degree of virulence, cell imaging, isozyme-specific inhibitors/activators or dominant- negative mutants, siRNA-based knockdown, tissue-targeted over-expression, and knockout mice, we will address the following thematically and mechanistically interrelated specific aims: Aim 1 will (i). define similarities and/or potential differences in signaling mechanisms and functional consequences of infection-induced HO-1 using Sheila Smith (highly virulent), HLP (comparatively less pathogenic), and Iowa (avirulent) strains of R rickettsii, and (ii). investigate the regulation of Cox-2 and its role in the control of vascular permeability via production of PGs and rickettsial replication. Aim 2 will characterize the differential effects of SFG versus TG rickettsiae and representative strains with varying degree of virulence within individual species on endothelial HO-1 and Cox-2 and identify specific rickettsial mechanisms that regulate host cell responses. Aim 3 will determine the role of HO-1 in the host-protective adaptations and Cox-2 in the pathophysiology of in vivo SFG and TG rickettsioses. Together, these studies will dissect the physiological significance and potential differences in the contributions of vasoactive products of HO-1 and Cox-2 activities in the pathogenetic and virulence mechanisms of SFG and TG rickettsioses and provide useful insight to identify novel therapeutic targets for species-specific interventions in particular or vasculopathic rickettsial diseases in general.

描述（由申请人提供）：致病性立克次体属是全世界人类已知的一些最严重细菌性疾病的病原体。其中有落基山斑疹热和流行性斑疹伤寒，分别由R. rickettsii和R. prowazekii。立克次体是专性细胞内寄生虫，其特征是嗜性其哺乳动物宿主的血管内皮。越来越多的证据表明，活性氧（ROS）在内皮功能障碍和立克次体的发病机制中起着重要作用。作为生理稳态的维持者，内皮细胞维持血管张力和血管通透性，并调节对过多有害刺激的炎症反应。我们公布的和初步的数据进一步表明：1。感染内皮细胞（EC）诱导血红素加氧酶（HO）-1的表达，HO-1是一种负责将促氧化血红素降解成具有多种细胞保护功能的生物活性分子（胆红素、一氧化碳和铁蛋白）的酶; 2.在斑点热群（SFG）立克次体感染期间，环氧合酶（考克斯）-2的表达增加导致前列腺素（PG）分泌增加;和3. SF和斑疹伤寒组（TG）生物体触发ROS生成和激活抗氧化防御机制的能力存在显着差异，这可能是由于它们的胞质内行为存在明显差异。这些观察结果导致了这样的假设，即HO和考克斯酶系统的调节以及HO和考克斯信号传导机制之间的相互作用是宿主细胞存活、炎症发作/程度和血管通透性变化的关键决定因素，所有这些都是立克次体病病理表现的关键决定因素。所提出的研究集中于阐明迄今未知的调控机制，控制氧化还原稳态，急性炎症，和血管通透性，使用SFG感染培养的人EC（体外）和易感小鼠品系的播散性内皮感染（体内）。rickettsii，R. conorii和R. australis）和TG（R.普劳瓦泽基河typhi）作为独立的模型系统。利用具有不同毒力程度的立克次体菌株、细胞成像、同工酶特异性抑制剂/激活剂或显性阴性突变体、基于siRNA的敲除、组织靶向过表达和敲除小鼠，我们将解决以下主题和机制相关的具体目标：目标1将（i）。使用立克次氏体的Sheila Smith（高毒力）、HLP（相对较低致病性）和爱荷华州（无毒力）菌株，定义感染诱导的HO-1的信号传导机制和功能结果的相似性和/或潜在差异，和（ii）。研究考克斯-2的调节及其在通过产生PG和立克次体复制控制血管通透性中的作用。目的2将表征SFG与TG立克次体以及在个体物种内具有不同毒力程度的代表性菌株对内皮HO-1和考克斯-2的不同作用，并鉴定调节宿主细胞应答的特定立克次体机制。目的3将确定HO-1在宿主保护性适应中的作用和考克斯-2在体内SFG和TG立克次体病的病理生理学中的作用。总之，这些研究将剖析HO-1和考克斯-2活动的血管活性产物在SFG和TG立克次体病的发病机制和毒力机制中的作用的生理意义和潜在差异，并提供有用的见解，以确定新的治疗靶点，特别是针对特定物种的干预措施或血管病变性立克次体病。