Pathogenic Mechanisms of Vascular Dysfunction in Scrub Typhus

恙虫病血管功能障碍的致病机制

基本信息

批准号：
10204937
负责人：
LYNN SOONG
金额：
$ 39.5万
依托单位：
UNIVERSITY OF TEXAS MED BR GALVESTON
依托单位国家：
美国
项目类别：
财政年份：
2018
资助国家：
美国
起止时间：
2018-08-02 至 2024-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10204937
关键词：
Acute Address Angiopoietin-2 Animal Model Antibodies Asia Bacteria Bacterial Infections Biological Markers Blood Platelets Blood Vessels Bone Marrow Cell Culture Techniques Cessation of life Color Containment Data Disease Endothelial Cells Endothelium FDA approved Functional disorder Gene Proteins Goals HMGB1 gene Human IL8RB gene Immune Immune response Immunity In Vitro Infection Infection Control Institutes Intervention Kinetics Knockout Mice Knowledge Leukocytes Life Lung Mediating Modality Modeling Molecular Mus Neutrophil Activation Orientia tsutsugamushi Pathogenesis Pathogenicity Pathologic Pathway interactions Pattern Peroxidases Phagocytes Platelet Activation Populations at Risk Prognostic Marker Public Health Recombinants Regulation Regulatory Pathway Research Role Scrub Typhus Sepsis Signal Transduction System TNF gene Testing Therapeutic Thrombocytopenia Time Tissues Umbilical vein Vaccines Validation Vascular Diseases Work base cell injury cohesion cost effective cytokine ethyl pyruvate human disease improved infection risk innovation insight macrophage mortality mouse model neutrophil novel preclinical study preservation protective effect receptor response specific biomarkers synergism therapeutic target tool vascular injury

项目摘要

Scrub typhus is a life-threatening disease caused by Orientia tsutsugamushi, a LPS-negative bacterium that replicates preferentially in endothelial cells (EC) and phagocytes. While one million people are infected yearly, with about one-third of world population at risk of infection, effective strategies for infection control are lacking. Information on disease pathogenesis and immune dysregulation is limited. To address these challenges, we have developed mouse models that mimic certain key pathological features of human scrub typhus. We found that endogenous damage-associated molecular pattern (DAMP) molecules such as HMGB1 and myeloperoxidase (MPO) are key regulators responsible for molecular dysfunctions involving angiopoietin 2 (Ang2), Tie2, and CD41+ platelets. We also discovered the detrimental effect of sustained neutrophil activation in thrombocytopenia and vascular injury, and the potential of Ang2 and miR-200b as unique biomarkers for vascular dysfunction. The objective of this study is to define pathogenic mechanisms of vascular dysfunction and therapeutic modalities for severe scrub typhus by utilizing the EC-targeting model of O. tsutsugamushi infection. Our central hypothesis is that the infection-triggered release of DAMPs exacerbates O. tsutsugamushi-induced vascular damage by altering neutrophil/platelet activation; interventions aimed at preserving vascular integrity or phagocyte function help to elicit a balanced immunity against acute tissue damage and severe scrub typhus. This hypothesis will be tested in three cohesive Specific Aims. Aim 1 will examine the mechanisms of HMGB1- and TNF-mediated sensitization and exacerbation of human endothelium in Orientia infection. We will use human microvascular endothelial cells (HMEC) to test whether Orientia triggers the release of HMGB1, TNF, Ang2, and miR-200b and their target genes/proteins, and if therapeutics targeting these mechanisms mitigate EC injury. Aim 2 will examine mechanisms by which neutrophils and HMGB1 contribute to vascular and platelet dysfunction during infection in mice. We will set up lethal and sublethal infections in CXCR2-/- or MPO-/- mice at different infection stages. Likewise, the deletion of RAGE (a HMGB1 receptor, RAGE-/- mice) or anti-RAGE antibody will reveal specific roles of HMGB1/RAGE signaling in tissue-infiltrated leukocytes, platelet and vascular function. Aim 3 will test whether anti-Ang2 and statin-based therapeutics promote host survival via modulating vascular function and phagocyte activation in mice. Mice will be treated with anti-Ang2 antibody, recombinant Ang1, or statins (alone or in combination) before or during lethal and sublethal infection. We will examine bacterial dissemination, neutrophil/platelet activation, and the levels of Tie2 and signature cytokines/DAMPs. This mechanism-focused study capitalizes on the synergism among several research teams. Discovery of vascular-specific biomarkers, novel regulatory pathways, and their impact on immune responses to Orientia is timely, innovative and highly significant.

Scrub Typhus是由Orientia Tsutsugamushi引起的一种威胁生命的疾病，这是一种LPS阴性细菌在内皮细胞（EC）和吞噬细胞中优先复制。虽然每年有100万人被感染，但大约三分之一的世界人口处于感染风险中，缺乏有效的感染控制策略。疾病发病机理和免疫失调的信息受到限制。为了应对这些挑战，我们已经开发了模仿人类灌木斑疹伤寒的某些关键病理特征的小鼠模型。我们发现内源性损伤相关的分子模式（潮湿）分子，例如HMGB1和脊髓过氧化物酶（MPO）是负责分子功能障碍的关键调节剂，涉及Angiopietin 2 （ANG2），TIE2和CD41+血小板。我们还发现了持续中性粒细胞激活的有害作用在血小板减少症和血管损伤中，以及Ang2和miR-200b作为独特的生物标志物的潜力血管功能障碍。这项研究的目的是定义血管功能障碍的致病机制通过使用O. tsutsugamushi的EC靶向模型，对严重磨砂鼠伤寒的热模式感染。我们的中心假设是感染触发的潮湿释放加剧了O。 tsutsugamushi通过改变中性粒细胞/血小板激活而诱导的血管损伤；针对的干预措施保持血管完整性或吞噬细胞功能有助于引起对急性组织的平衡免疫史损坏和严重的磨砂鼠伤寒。该假设将以三个凝聚的特定目的进行检验。目标1意志检查HMGB1和TNF介导的敏感性的机制，并加剧了人类东方感染的内皮。我们将使用人类微血管内皮细胞（HMEC）测试是否东方触发HMGB1，TNF，ANG2和MIR-200B及其靶基因/蛋白的释放，以及针对这些机制的治疗剂可减轻EC损伤。 AIM 2将检查机制小鼠感染过程中嗜中性粒细胞和HMGB1在感染过程中导致血管和血小板功能障碍。我们将设置在不同感染阶段，CXCR2 - / - 或MPO - / - 小鼠中的致死性感染。同样，删除愤怒（HMGB1受体，愤怒 - / - 小鼠）或抗rage抗体将揭示HMGB1/RAGE的特定作用在组织浸润的白细胞，血小板和血管功能中的信号传导。 AIM 3将测试抗ANG2和基于他汀类药物的治疗通过调节血管功能和吞噬细胞激活来促进宿主存活老鼠。小鼠将用抗Ang2抗体，重组ANG1或他汀类药物（单独或组合）治疗致死性感染之前或期间。我们将检查传播细菌，中性粒细胞/血小板激活以及TIE2和特征细胞因子/潮湿的水平。这项以机制为中心的研究资本化关于几个研究团队的协同作用。发现血管特异性生物标志物，新型调节途径及其对东方免疫调查的影响是及时的，创新的，并且非常重要。