Preclinical modeling to study Tuberculous Meningitis

结核性脑膜炎是一种严重威胁生命的疾病，影响脆弱人群，包括 艾滋病毒感染者和幼儿。早期诊断是具有挑战性的，即使是在 延长抗菌治疗时间(≥为12个月)。尽管几种关键的抗菌药限制了中枢 神经系统(CNS)渗透和免疫病理学是神经损伤的主要驱动因素， 肺结核仍被用作治疗范例，利用结核病的临床前模型的努力有限 优化脑膜炎治疗。 我们已经建立了一种结核脑膜炎的兔模型，该模型复制了结核脑膜炎的关键神经病理特征 人类疾病。此外，我们还开发了几种新的、临床可翻译的正电子发射 断层扫描(PET)示踪剂用于全面、无偏和非侵入性的病理生理测量 活体动物的过程。这些药物包括用于脑部炎症的124I-DPA-713、11C-利福平、76BrBedaquiline 和18F-利奈唑胺测定抗菌药物对中枢神经系统的渗透率，苯并噻嗪类似物直接 检测结核分枝杆菌和18F-白蛋白/11C-维拉帕米研究血脑屏障 通透性/药物外排转运体活性。鉴于利福平在治疗骨肉瘤中的重要性 我们使用动态11C-利福平PET在兔体内进行了详细的药代动力学(PK)研究 和人类(Tucker等人SCI Transl Med 2018)。我们证明了利福平的渗透性(在 曲线)进入感染的脑部病变是有限的，在空间上是不同的，并且在两个 开始治疗数周(32%至11%)。重要的是，脑脊液中的利福平浓度 与感染的脑部病变的相关性不好。人类首例11C-利福平PET在肺结核脑膜炎中的应用 患者是安全的，耐受性良好，表现出类似的有限和不同种类的利福平渗透。 我们将在兔模型中利用这些新的成像工具来提供对结核病的机械性见解 脑膜炎和优化治疗的关键信息：a)衡量新型结核病药物的渗透率，包括 那些积极抗击耐多药结核病的人，对感染的脑部病变以及对 脑脊液和脑组织水平不一致的相关性；b)比较利奈唑胺和大剂量利福平 方案，并阐明血脑屏障通透性和外流转运体在中枢神经系统药物暴露中的作用；c) 进行纵向多模式成像以同时可视化肿瘤内的细菌负荷， 活体动物结核病治疗期间炎症和抗菌药物暴露的相关性 脑内炎症反应和抗菌药物暴露与治疗结果的关系。这些 用目前需要切除组织的技术进行评估是不可行的。这项建议符合 影响一种破坏性疾病的结核病药物开发和治疗优化方面的重要差距 弱势群体。

Tuberculous (TB) meningitis is a serious, life-threatening disease affecting vulnerable populations including HIV-infected individuals and young children. Early diagnosis is challenging and outcomes are poor even with prolonged antimicrobial treatment (≥12 months). Although several key antimicrobials have limited central nervous system (CNS) penetration and immunopathology is the major driver of neurological damage, pulmonary TB is still used as the treatment paradigm, with limited efforts to utilize preclinical models of TB meningitis to optimize treatment. We have developed a rabbit model of TB meningitis that replicates key neuropathological features of human disease. Additionally, we have developed several novel, clinically translatable positron emission tomography (PET) tracers to perform holistic, unbiased and noninvasive measurements of pathophysiological processes in live animals. These include 124I-DPA-713 for cerebral inflammation, 11C-rifampin, 76Br-bedaquiline and 18F-linezolid to measure antimicrobial penetration into the CNS, benzothiazinone (BTZ) analogs to directly detect Mycobacterium tuberculosis and 18F-albumin / 11C-verapamil to study blood-brain barrier (BBB) permeability / drug efflux transporter activity respectively. Given the importance of rifampin for the treatment of TB meningitis, we performed detailed pharmacokinetic (PK) studies using dynamic 11C-rifampin PET in rabbits and humans (Tucker et al. Sci Transl Med 2018). We demonstrate that rifampin penetration (area under the curve) into infected-brain lesions is limited, spatially heterogeneous and substantially decreases within two weeks of starting treatment (32% to 11%). Importantly, rifampin concentrations in cerebrospinal fluid (CSF) do not correlate well with those in infected-brain lesions. First-in-human 11C-rifampin PET in a TB meningitis patient was safe, well tolerated and demonstrated similar limited and heterogeneous rifampin penetration. We will utilize these novel imaging tools in the rabbit model to provide mechanistic insights into TB meningitis and key information to optimize treatments: a) measure the penetration of novel TB drugs, including those active against multi-drug resistant TB, into infected-brain lesions as well as provide insights into the relevance of discordant CSF and brain tissue levels; b) compare linezolid and high-dose rifampin based regimens and elucidate the role of BBB permeability and efflux transporters in drug exposures in the CNS; c) perform longitudinal multi-modality imaging to simultaneously visualize intralesional bacterial burden, inflammation and antimicrobial exposure during TB treatments in live animals to correlate the effect of intracerebral inflammatory responses and antimicrobial exposures with the treatment outcome. These assessments are not feasible with current technologies that require resected tissues. This proposal fulfills an important gap in TB drug development and treatment optimization for a devastating disease affecting vulnerable populations.