How do drugs enter and leave the central nervous system?

药物如何进入和离开组织对于它们在治疗疾病中的有效性至关重要。最有效的低毒性治疗方法如果不能达到其目标是没有用的，如果毒性形式迅速从体内清除，则可以安全使用高毒性药物。在这个项目中，我们的目标是了解药物如何进入和离开中枢神经系统（CNS）。几乎所有分子进出CNS的运动都受到血脑屏障的严格调节，血脑屏障限制了血管系统和大脑之间的运动。此外，脉络丛在脑室中产生脑脊液（CSF），蛛网膜绒毛清除CSF。这种调节在限制表现出神经毒性的化合物进入方面是至关重要的，但也是通过中枢神经系统对疾病进行药理学操作的重要障碍。此外，毒性和药物疗效必须平衡，通过抗微生物剂通常具有显著毒性的感染性脑膜炎的治疗来体现。然而，尽管它的重要性，大多数药物如何进入和离开中枢神经系统是未知的。在这个项目中，我们将调查如何抗菌剂进入和离开中枢神经系统在脑膜炎的治疗。这将告知这种药物的使用和潜在的改进，但也将增加我们对药物进出CNS的更广泛机制的了解。我们将重点关注的CNS感染形式是隐球菌脑膜炎（约翰斯顿和吉布森，2016; http：//goo.gl/bJaQco）。隐球菌脑膜炎（CM）的治疗受到疾病晚期表现和诊断的阻碍。最好的治疗方法是阿替西霉素B（Amp B）的脂质体制剂，但其毒性和成本使其在大多数低收入和中等收入国家中无法使用，这些国家的疾病负担最大。来自Hope实验室的最新研究表明，AmpB具有长的半衰期，并且较短的治疗过程不会在治疗上较差，但毒性可能较小（Lestner等人，2017（http：//goo.gl/hR8kLU）; AMBITON：cm临床试验; Molefi等人，2015年）。此外，约翰斯顿实验室已经在斑马鱼中产生了独特的体内实验模型，用于研究治疗性化合物进入和离开CNS（Lestner等人，2017;货车Leeuwen等人，2017年，筹备中）。因此，我们将研究AmpB CNS进入和退出的机制，以确定改善AmpB治疗的机会，增加治疗剂量而不增加毒性。该项目将有三个部分：1。斑马鱼有一个很好的保存血脑屏障和流体交换结构与人类。我们最近开发了一种新的血脑屏障和脉络丛的体内模型，使我们能够在很长一段时间内直接对这两种结构进行成像。我们将使用荧光标记的AmpB注射到血流中，并实时成像其在整个身体中的动态。我们将能够量化本地化和药物动力学，以开发CNS 2中AmpB动力学的潜在模型。我们将使用啮齿动物和兔宿主隐球菌脑膜炎的成熟实验模型，通过对CNS不同区域的脑样本和不同时间点进行质谱分析，以确认斑马鱼中的发现，来测试我们的AmpB动力学模型。3.与我们的非学术合作伙伴吉利德，我们将研究潜在的修改脂质体的AmpB配方和我们的机制研究如何可能影响治疗使用AmpB。

How drugs enter and leave tissues is critical to their usefulness in treating disease. The most effective, low toxicity treatment is no use if it cannot reach its target, and a highly toxic drug can be used safely if its toxic form is rapidly removed from the body. In this project, we aim to understand how drugs can enter and leave the central nervous system (CNS).The movement of almost all molecules in and out of the CNS is tightly regulated by the blood brain barrier, which restricts movement between the vascular system and the brain. In addition, there is the choroid plexus that produces cerebral spinal fluid (CSF) in the brain ventricles and the arachnoid villi that remove CSF. This regulation is critical in limiting entry of compounds that exhibit neuro toxicity but is also a significant barrier to pharmacological manipulation of disease via the central nervous system. Furthermore, toxicity and drug efficacy must be balanced, epitomised by the treatment of infective meningitis where antimicrobials often have significant toxicity. However, despite its importance, how most drugs enter and leave the central nervous system is unknown.In this project, we will investigate how an antimicrobial enters and the leaves the CNS during the treatment of meningitis. This will inform the use, and potentially the refinement, of this drug but will also increase our knowledge of the wider mechanisms of drug movement in and out of the CNS. The form of CNS infection we will focus on is cryptococcal meningitis (Johnston and Gibson, 2016; http://goo.gl/bJaQco).Treating cryptococcal meningitis (CM) is hindered by late presentation and diagnosis late in disease. The best available therapy is a liposomal formulation of amphotericin B (AmpB) but its toxicity and cost make it prohibitive for use in most low and middle income countries, where there is the largest burden of disease. Recent work from the Hope laboratory has shown that AmpB has a long half-life, and that a shorter course of treatment would not be therapeutically inferior but may be less toxic (Lestner et al., 2017 (http://goo.gl/hR8kLU) ; AMBITON:cm clinical trial; Molefi et al., 2015). Furthermore, the Johnston lab has generated a unique in vivo experimental model in zebrafish for studying the entry and exit of therapeutic compounds into the CNS (Lestner et al., 2017; van Leeuwen et al., 2017, in preparation). Therefore, we will study the mechanism of AmpB CNS entry and exit to identify opportunities for improving AmpB treatment, increasing therapeutic dose without increasing toxicity. The project will have 3 parts: 1. Zebrafish have a well conserved blood brain barrier and fluid exchange structures with humans. We have recently developed a new in vivo model of the blood brain barrier and choroid plexus that enables us to directly image both structures over a long period of time. We will use fluorescently labelled AmpB injected into the blood stream and live image its dynamics throughout the body. We will be able to quantify localisation and drug dynamics to develop potential models for AmpB dynamics in the CNS 2. We will test our models for AmpB dynamics using well-established experimental models of cryptococcal meningitis in rodent and leporine hosts by performing mass spectrometry on brain samples of the different areas of the CNS and at different time points to confirm findings in zebrafish. 3. With our non-academic partner Gilead, we will investigate potential modifications to the liposomal AmpB formulation and how our mechanistic studies might impact therapy using AmpB.