CNS Tuberculosis

描述(申请人提供)：世界卫生组织(WHO)宣布结核病(TB)进入全球紧急状态，据估计，今天世界人口的三分之一，即约20亿人，感染了潜伏性结核病。结核分枝杆菌(Mtb)感染最危险的形式是中枢神经系统(CNS)结核(CNSTB)。尽管CNSTB对公共卫生具有重要意义，但目前对CNSTB发病机制的了解非常有限，CNSTB患者的预后也是黯淡的。CNSTB主要影响儿童和免疫缺陷成人。我们已经建立了新的MHC II类缺陷或RAG免疫缺陷小鼠模型来研究Mtb在中枢神经系统的传播。我们推测，树突状细胞(DC)将结核分枝杆菌(MTB)运送到中枢神经系统，促进结核杆菌在CNSTB中的传播。在我们的初步数据中，我们已经表明，在7日龄免疫缺陷小鼠中，DC优先携带Mtb进入中枢神经系统。我们已经产生了表达绿色荧光蛋白(GFP)的新型重组Mtb菌株，并创造了表达OVA257-264和OVA323-339抗原表位的Mtb菌株。我们已经证明，这些新的结核分枝杆菌菌株可以在体内被追踪，并用于测试CNSTB的系统适应性免疫。我们的总体目标是确定结核分枝杆菌向中枢神经系统传播的机制。在目标1中，我们将确定树突状细胞在结核杆菌传播到中枢神经系统中的作用(目标1A)，并研究血脑屏障(BBB)调节结核杆菌感染的树突状细胞迁移的途径(目标1B)。在目标2中，我们将研究CNSTB的免疫调控。我们将利用我们对周围组织中分枝杆菌控制的知识，并确定哪些中枢神经系统和免疫细胞控制CNSTB中的分枝杆菌生长(目标2A)。利用已定义的转Ag85、OT-I或OT-II基因的小鼠系，以及表达这些表位的重组Mtb菌株，我们将剖析CNSTB(Aim 2B)中抗原特异性免疫反应的机制。在这些研究的结论中，我们将增加对CNSTB发病机制的了解，评估新的CNSTB体内模型，创造可用于追踪体内Mtb感染的新试剂，并阐明BBB在Mtb向CNS扩散中的作用。这些实验将填补我们在CNSTB发病机制方面的知识空白，并将导致改善治疗中枢神经系统分枝杆菌感染的策略。 公共卫生相关性：尽管有有效的短程化疗和卡介苗(BCG)疫苗可用，但结核杆菌夺走的生命仍然比任何其他单一感染源都多。近年来，发展中国家和工业化国家的结核病发病率均有所上升，耐药菌株普遍出现，并与人类免疫缺陷病毒(艾滋病毒)产生了致命的协同作用。1993年，世界卫生组织(WHO)宣布结核病(TB)为全球紧急状态，据估计，今天全球人口的三分之一，约20亿人感染了潜伏性结核病。中枢神经系统结核(CNSTB)是最危险的结核分支杆菌感染形式。诊断具有挑战性，而且这种疾病在临床上很难管理。即使经过严格的治疗，死亡率也很高，存活下来的人中约有27%会出现严重的神经损伤和残疾。尽管这种疾病很严重，但目前对CNSTB发病机制的认识仍然可以追溯到1933年发表的尸检数据。自20世纪50年代引入异烟肼以来，治疗进展甚微(临床胸科医学30(4)：745-754)。治疗方法仅限于30多年前开发的化疗，而对发病机制研究的缺乏使新疗法的开发搁置了数十年。随着耐药菌株的出现，迫切需要制定新的治疗干预和预防该疾病的战略。该项目将提供关于中枢神经系统结核病发病机制的新知识，并使制定预防和治疗策略来应对这种疾病。

DESCRIPTION (provided by applicant): The World Health Organization (WHO) declared a tuberculosis (TB) global emergency, and it is estimated that today 1/3 of the world population, or approximately 2 billion people, is infected with latent TB. The most dangerous form of Mycobacterium tuberculosis (Mtb) infection is central nervous system (CNS) tuberculosis (CNSTB). Despite its public health importance, current understanding about the pathogenesis of CNSTB is very limited, and prognosis for patients with CNSTB is bleak. CNSTB largely affects children and immunodeficient adults. We have established novel MHC class II- deficient or RAG immunodeficient mouse models to study Mtb dissemination in the CNS. We hypothesize that dendritic cells (DCs) deliver Mtb into the CNS and contribute to Mtb dissemination in CNSTB. In our preliminary data, we have shown that DCs preferentially carry Mtb into the CNS in 7-day-old immunodeficient mice. We have generated novel recombinant Mtb strains that express green fluorescent protein (GFP) and created Mtb strains that express OVA257-264 and OVA323-339 antigenic epitopes. We have shown that these novel Mtb strains can be tracked in vivo and utilized for testing systemic adaptive immunity in CNSTB. Our overall goal is to define the mechanisms of Mtb dissemination into the CNS. In Aim 1, we will determine the role of DCs in Mtb dissemination into the CNS (Aim 1A) and investigate the means by which the blood- brain barrier (BBB) regulates Mtb-infected DC migration (Aim 1B). In Aim 2, we will study immunological control of CNSTB. We will take advantage of our knowledge of mycobacterial control in peripheral tissues and define which CNS and immune cells control mycobacterial growth in CNSTB (Aim 2A). Using defined mouse lines transgenic for Ag85, OT-I, or OT-II, as well as recombinant Mtb strains expressing these epitopes, we will dissect the mechanism of antigen-specific immune response in CNSTB (Aim 2B). At the conclusion of these studies, we will have increased our knowledge of CNSTB pathogenesis, evaluated new in vivo models of CNSTB, created novel reagents that can be used to track Mtb infections in vivo, and elucidated the role of the BBB in Mtb dissemination into the CNS. These experiments will fill the gap in our knowledge regarding the pathogenesis of CNSTB and will lead to improved strategies for treating mycobacterial infections of the CNS. PUBLIC HEALTH RELEVANCE: Despite the availability of effective short-course chemotherapy and the Bacille Calmette- Guerin (BCG) vaccine, the tubercle bacillus continues to claim more lives than any other single infectious agent. Recent years have demonstrated an increased incidence of tuberculosis in both developing and industrialized countries, the widespread emergence of drug-resistant strains and a deadly synergy with the human immunodeficiency virus (HIV). IN 1993, the World Health Organization (WHO) declared a tuberculosis (TB) global emergency and it is estimated that today 1/3, approximately 2 billion people, of the global population is infected with latent TB. CNS tuberculosis (CNSTB) is the most dangerous form of Mtb infection. The diagnosis is challenging, and the disease is clinically hard to manage. Mortality, even with rigorous treatment, is high, and of those who survive ~27% develop severe neurological damage and disability. Despite the severity of this disease, current understanding about the pathogenesis of CNSTB is still dated back to necropsy data published in 1933. Treatment has advanced little since the introduction of isoniazid in the 1950s (Clin Chest Med 30(4): 745-754). Therapeutic approaches are limited to chemotherapy developed over 30 years ago, and the lack of progress in research on pathogenesis has put the development of new treatments on hold for decades. With drug-resistant strains emerging there is an urgent need for development of new strategies for therapeutic intervention and prevention of this disease. This project will provide new knowledge regarding pathogenesis of CNS tuberculosis and enable the development of preventive and therapeutic strategies to cope with this disease.