Dysregulated type-1 and Vascular Responses in Scrub typhus Pathogenesis

 描述(申请人提供)：斑疹伤寒是一种由东方体引起的危及生命的疾病，是一种内毒素阴性细菌，优先在内皮细胞(EC)和单核细胞中复制。每年约有100万人感染；约三分之一的世界人口面临感染风险。目前还没有针对这种感染的有效疫苗，关于该病发病机制的信息有限。为了应对这些挑战，我们开发了能够模拟人类斑疹伤寒病理特征的小鼠模型。我们发现，致命性感染与1型免疫反应过度有关，而2型免疫反应不足与多个器官的血管损伤有关。然而，潜在的机制还没有得到很好的定义。这项研究的目的是通过利用人感染最流行的钩端螺旋体Karp株(OTK)的EC靶向模型来检查这种调控失调的分子基础。我们的中心假设是1型偏斜的炎症反应和血管生成素(Ang)表达失调是致死性OTK感染的主要原因。目的1研究干扰素-的细胞来源和干扰素-相关反应在东方体感染过程中细菌清除和免疫发病机制中的双重作用。干扰素-及其相关趋化因子在感染的肝、肺和脾中的先天和适应性细胞来源将通过干扰素-报告小鼠以及RAG2、干扰素-或CXCR3表达缺陷的小鼠进行检测。在疾病的不同阶段接受抗干扰素-治疗的小鼠将有助于确定干扰素-在体内细菌清除和免疫发病机制中的功能。来自单细胞和分子水平的免疫学结果将与组织细菌负荷和病理评估的结果相结合。目的2验证细菌感染引起的内皮细胞激活/失调可通过干扰素-相关细胞因子/趋化因子改善的假说。在疾病的早期和晚期，致命感染的小鼠将单独或与血管内皮生长因子或抗干扰素-一起使用重组血管紧张素1进行治疗。在干扰素--/-或CXCR3-/-小鼠身上进行的类似治疗，以及以EC为重点的体外研究，将有助于剖析细胞因子和血管反应之间的复杂相互作用。这项以机制为重点的研究认可研究团队(每个团队都有独特的专业知识)之间的协同作用；它利用了UTMB最先进的ABSL3/BSL3设施。这项研究的长期目标是确定与东方体感染相关的致病机制，并利用这些信息设计控制策略。ONet的发现和最初功能障碍的性质将揭示免疫干预的关键窗口，以及S标志性免疫图谱对疾病预后的预测。这一及时的研究将对其他细胞内病原体具有广泛的意义。

 DESCRIPTION (provided by applicant): Scrub typhus is a life-threatening disease caused Orientia tsutsugamushi, a LPS-negative bacterium that replicates preferentially in endothelial cells (EC) and monocytes. Approximately one million people are infected every year; about one third of world population is at risk of infection. There is no effective vaccine for this infection information on disease pathogenesis is limited. To address these challenges, we have developed mouse models that can mimic pathological features of human scrub typhus. We found that lethal infection was linked to excessive type 1, but deficient type 2, immune responses, which correlated with vascular damage in multiple organs. However, the underlying mechanisms are poorly defined. The goal of this study is to examine the molecular basis of such dysregulation by utilizing the EC-targeting model of O. tsutsugamushi Karp strain (OtK) infection, the most prevalent strain for human infections. Our central hypothesis is that type 1-skewed inflammatory responses and dysregulated angiopoietin (Ang) expression are leading causes for lethal OtK infection. Aim 1 will examine the cellular sources of IFN- and dual functions of IFN--related responses in bacterial clearance versus immunopathogenesis during Orientia infection. The innate vs. adaptive cell sources of IFN- and its related CXCR3 chemokines in infected liver, lungs and spleen will be examined by using IFN- reporter mice, as well as mice deficient in RAG2, IFN- or CXCR3 expression. Mice receiving anti-IFN- treatment at different stages of disease will help define in vivo function of IFN- in bacterial clearance vs. immunopathogenesis. Immunological findings from the single-cell and molecular levels will be integrated with those from tissue bacterial load and pathology evaluations. Aim 2 will test the hypothesis that endothelial activation/dysregulation initiated by bacterial infectionis ameliorated by IFN--related cytokines/chemokines. Lethally infected mice will be treated with recombinant Ang 1, alone or together with vascular endothelial growth factor (VEGF) or anti-IFN-, at early and late stages of disease. Similar treatment in IFN--/- or CXCR3-/- mice, as well as EC-focused in vitro studies, will help dissect complex interplays between cytokines and vascular responses. This mechanism-focused study endorses synergy among research teams (each with unique expertise); it utilizes the state-of-art ABSL3/BSL3 facilities at UTMB. The long-term goal of this study is to define the pathogenic mechanisms associated with Orientia infection and to utilize this information for the design of control strategies. Discovery of the onet and nature of initial dysfunction will reveal the critical window for immune intervention, as well s for signature immune profiles for disease prognosis. This timely study will have a broad implication for other intracellular pathogens.