Host Cell JAK-STAT Activation and Pathogenesis of Spotted Fever Rickettsioses

宿主细胞 JAK-STAT 激活和斑点热立克次体病的发病机制

• 批准号: 8524206
• 负责人: Sanjeev K. Sahni
• 金额: $ 38.25万
• 依托单位: UNIVERSITY OF TEXAS MED BR GALVESTON
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-20 至 2014-08-19
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8524206
• 关键词: Activated Natural Killer Cell; Adhesives; Adult Respiratory Distress Syndrome; Anti-Bacterial Agents; Antibodies; Antiviral Agents; Binding; Biological; Blood Vessels; Boutonneuse Fever; Cardiac Output; Case Fatality Rates; Cells; Cellular biology; Cerebral Edema; Conditioned Culture Media; DNA Binding; Data; Development; Disease; Encephalitis; Endothelial Cells; Endothelium; Fever; Functional disorder; Genes; Gram-Negative Bacteria; Growth; Host Defense; Host Defense Mechanism; Human; IFNAR1 gene; Immune response; In Vitro; Infection; Inflammatory; Interferons; Janus kinase; Knowledge; Lipopolysaccharides; Lung; Mediating; Methods; Microbe; Microscopy; Modeling; Molecular Genetics; Morbidity - disease rate; Mouse Strains; Mus; Natural Immunity; Nuclear Translocation; Pathogenesis; Patients; Pattern; Phenotype; Phosphorylation; Phylogenetic Analysis; Play; Proteins; Proteobacteria; Proteomics; Publishing; Pulmonary Edema; RNA Interference; Rickettsia; Rickettsia Infections; Rickettsia rickettsii; Rocky Mountain Spotted Fever; Role; STAT protein; STAT1 gene; STAT3 gene; Scourge; Second Messenger Systems; Severities; Signal Pathway; Signal Transduction; Spottings; TLR4 gene; Testing; Therapeutic; Tick-Borne Diseases; Tissues; Transcriptional Activation; Tropism; Vascular Endothelium; Vascular Permeabilities; Vasculitis; autocrine; base; cytokine; human IFITM1 protein; human disease; improved; in vivo; innovation; insight; microbial; mortality; mouse model; novel; novel therapeutics; paracrine; pathogen; pathogenic bacteria; receptor; response; second messenger; trait; vascular inflammation

DESCRIPTION (provided by applicant): Rickettsia rickettsii and R. conorii are Gram-negative, obligate intracellular a-proteobacteria known to cause Rocky Mountain spotted fever (RMSF) and Mediterranean SF in humans. A unique trait of pathogenic rickettsiae is the tropism for microvascular endothelium of the blood vessels, which results in disseminated endothelial infection, vascular inflammation, and compromised vascular permeability. Activation of otherwise quiescent endothelium in response to rickettsial invasion is characterized by acquisition of prothrombotic, procoagulant and proinflammatory phenotypes, manifesting as 'rickettsial vasculitis'. Although endothelial activation typically involves input from multiple upstream mechanisms, including Janus Kinase-Signal Transducer and Activator of Transcription (JAK-STAT) proteins, the potential contributions of this critically important signaling pathway, which is typically involved in antiviral host defense, in rickettsial interactios with the host cell are completely unknown. Published as well as preliminary in vitro and in vivo evidence from our recent findings suggests: i) early STAT3 and late STAT1 activation in human microvascular endothelial cells (ECs) infected with SF rickettsiae; ii) ability of 'conditioned medium' from infected cells to activate STAT1 in na¿ve ECs through IFN-b; iii) increased expression of Interferon-Stimulated Gene encoding protein of 15 kDa (ISG15) dependent on IFN-b and STAT1; and iv) anti-bacterial activities of IFN-b, STAT1 and ISG15 against rickettsiae. These novel findings are the basis of three independent albeit mechanistically overlapping specific aims. First, we will identify receptor-mediated and intracytoplasmic signaling mechanisms and consequences of JAK-STAT activation during infection of cultured human and murine ECs with spotted fever rickettsiae. Because ISG15 not only plays an important role in innate immunity, but can also bind to other cellular proteins and modulate their functions via ISGylation, the second aim will determine its role in host defense mechanisms against pathogenic rickettsiae. Specifically, we will identify and analyze the functions of ISGylated proteins in infected endothelium and determine whether cytokine-like activity of secreted ISG15 activates Natural Killer cell-mediated host defense. Finally, we will define the potential roles of IFN-b, STAT1, and ISG15 as critical determinants of host defense exploiting established as well as novel murine models of infection mimicking human disease and mice lacking IFNAR, STAT1, and ISG15 as the host. We will employ contemporary, cutting edge methods of cell biology, microscopy, molecular genetics, and proteomics to reveal unique insights into mechanisms underlying host defense vis-¿-vis pathogenesis. Since rickettsioses are now re-emerging globally, comprehensive understanding of the pathogen interactions with the target host cell will aid in the identification of innovative therapeutic strategies to alter te course of debilitating rickettsial infections in favor of the host.

性状（由申请方提供）：立克次体和立克次体。conorii是革兰氏阴性的、专性细胞内α-变形菌，已知引起人的落基山斑疹热（RMSF）和地中海SF。致病性立克次体的一个独特特征是对血管的微血管内皮的嗜性，这导致播散性内皮感染、血管炎症和受损的血管通透性。立克次体侵入后，原本静止的内皮细胞被激活，其特征是获得促血栓形成、促凝血和促炎表型，表现为“立克次体血管炎”。虽然内皮激活通常涉及来自多个上游机制的输入，包括Janus激酶-信号转导和转录激活因子（JAK-STAT）蛋白，但这种至关重要的信号传导途径（通常参与抗病毒宿主防御）在立克次体与宿主细胞相互作用中的潜在贡献是完全未知的。我们最近发现的已发表的以及初步的体外和体内证据表明：i）SF立克次体感染的人微血管内皮细胞（EC）中的早期STAT 3和晚期STAT 1激活; ii）来自感染细胞的“条件培养基”通过IFN-b激活幼稚EC中STAT 1的能力; iii）依赖于IFN-b和STAT 1的15 kDa干扰素刺激基因编码蛋白（ISG 15）的表达增加;和iv）IFN-b、STAT 1和ISG 15针对立克次体的抗菌活性。这些新的发现是三个独立的基础，虽然机械重叠的具体目标。首先，我们将确定受体介导的和胞浆内的信号转导机制和JAK-STAT激活的结果在培养的人类和小鼠EC感染斑点热立克次体。由于ISG 15不仅在先天免疫中发挥重要作用，而且还可以与其他细胞蛋白结合并通过ISGylation调节其功能，因此第二个目标将确定其在宿主防御致病性立克次体机制中的作用。具体来说，我们将鉴定和分析ISGylated蛋白在感染内皮中的功能，并确定分泌的ISG 15的类精氨酸活性是否激活自然杀伤细胞介导的宿主防御。最后，我们将确定IFN-b，STAT 1和ISG 15作为宿主防御的关键决定因素的潜在作用，利用建立的以及新的模仿人类疾病的感染小鼠模型和缺乏IFNAR，STAT 1和ISG 15的小鼠作为宿主。我们将采用当代，细胞生物学，显微镜，分子遗传学和蛋白质组学的尖端方法，揭示宿主防御维斯的独特见解。由于立克次体病现在重新出现在全球范围内，全面了解病原体与靶宿主细胞的相互作用将有助于确定创新的治疗策略，以改变立克次体感染的衰弱过程，有利于宿主。