Preclinical modeling to study Tuberculous Meningitis

结核性脑膜炎是一种严重的、威胁生命的疾病，影响脆弱人群， 艾滋病毒感染者和幼儿。早期诊断是具有挑战性的，即使有 长期抗菌治疗（≥12个月）。尽管几种关键的抗菌剂具有有限的中心作用， 神经系统（CNS）渗透和免疫病理学是神经损伤的主要驱动力， 肺结核仍被用作治疗范例，在利用结核病临床前模型方面所做的努力有限 脑膜炎以优化治疗。 我们已经建立了一个结核性脑膜炎的兔模型，该模型复制了结核性脑膜炎的关键神经病理学特征。 人类疾病此外，我们还开发了几种新的，临床上可翻译的正电子发射 断层扫描（PET）示踪剂进行整体，公正和非侵入性的测量病理生理 活的动物中的过程。这些药物包括用于脑炎症的124 I-DPA-713、11 C-利福平、76 Br-贝达喹啉 和18F-利奈唑胺来测量抗菌剂对CNS的渗透，苯并噻嗪酮（BTZ）类似物直接 检测结核分枝杆菌和18 F-白蛋白/11 C-维拉帕米，研究血脑屏障（BBB） 渗透性/药物外排转运蛋白活性。鉴于利福平对治疗 结核性脑膜炎，我们进行了详细的药代动力学（PK）研究，使用动态11 C-利福平PET在兔 和人类（Tucker et al. Sci Transl Med 2018）。我们证明，利福平渗透（面积下的 曲线）进入感染的脑病变是有限的，空间异质性和实质上减少两个 开始治疗的周数（32%至11%）。重要的是，脑脊液（CSF）中利福平浓度 与感染性脑损伤的相关性不高。结核性脑膜炎中首次人体11 C-利福平PET 患者安全，耐受性良好，并表现出相似的有限和异质性利福平渗透。 我们将在兔子模型中利用这些新的成像工具来提供对结核病的机制见解 脑膜炎和优化治疗的关键信息：a）测量新型结核病药物的渗透率，包括 那些积极对抗多药耐药结核病，进入感染的大脑病变，以及提供深入了解 CSF和脑组织水平不一致的相关性; B）比较基于利奈唑胺和高剂量利福平的 方案，并阐明BBB渗透性和外排转运蛋白在CNS中药物暴露中的作用; c） 进行纵向多模态成像以同时可视化病灶内细菌负荷， 在活体动物中TB治疗期间的炎症和抗微生物剂暴露， 脑内炎症反应和抗菌剂暴露与治疗结果。这些 用需要切除组织的现有技术进行评估是不可行的。这一提议实现了一个 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.