How do drugs enter and leave the central nervous system?

药物进入和离开组织的方式对它们治疗疾病的有效性至关重要。如果不能达到目标，最有效、低毒的治疗是没有用的，而如果剧毒药物的有毒形式被迅速从体内清除，则可以安全地使用。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)。几乎所有进出中枢神经系统的分子都受到血脑屏障的严格调控，血脑屏障限制了血管系统和大脑之间的运动。此外，在脑室还有脉络丛产生脑脊液，蛛网膜绒毛清除脑脊液。这一规定在限制表现出神经毒性的化合物进入方面至关重要，但也是通过中枢神经系统对疾病进行药理操作的重要障碍。此外，毒性和药效必须得到平衡，以治疗感染性脑膜炎为代表，在这种情况下，抗菌剂往往具有显著的毒性。然而，尽管它很重要，但大多数药物是如何进入和离开中枢神经系统的尚不清楚。在这个项目中，我们将调查在脑膜炎治疗过程中，抗菌药是如何进入和离开中枢神经系统的。这将为该药物的使用和潜在的改进提供信息，但也将增加我们对药物进出中枢神经系统的更广泛机制的了解。我们将关注的中枢神经系统感染的形式是隐球菌性脑膜炎(Johnston和Gibson，2016；http://goo.gl/bJaQco).Treating隐球菌性脑膜炎(CM)由于疾病的后期表现和诊断而受到阻碍。现有的最好的治疗方法是两性霉素B(AmpB)的脂质体配方，但其毒性和成本使其无法在疾病负担最大的大多数低收入和中等收入国家使用。霍普实验室最近的研究表明，AmpB有很长的半衰期，较短的疗程不会在治疗上逊色，但可能毒性较小(Lestner等人，2017年(http://goo.gl/hR8kLU)；AMBITON：CM临床试验；Molefi等人，2015年)。此外，约翰斯顿实验室在斑马鱼身上建立了一种独特的体内实验模型，用于研究治疗化合物进入和离开中枢神经系统的过程(Lestner等人，2017年；van Leeuwen等人，正在准备中)。因此，我们将研究AmpB中枢神经系统的进入和退出机制，以寻找改进AmpB治疗的机会，在不增加毒性的情况下增加治疗剂量。该项目将分为三个部分：1。斑马鱼具有保存完好的血脑屏障和与人类的液体交换结构。我们最近开发了一种新的血脑屏障和脉络丛体内模型，使我们能够在很长一段时间内直接成像这两种结构。我们将使用荧光标记的AmpB注射到血流中，并实时成像其在全身的动态。我们将能够量化定位和药物动力学，以开发在CNS 2中AmpB动力学的潜在模型。我们将使用啮齿动物和Leporine宿主中已建立的隐球菌脑膜炎实验模型，通过对CNS不同区域和不同时间点的大脑样本进行质谱分析，以确认在斑马鱼中的发现，来测试我们的AmpB动力学模型。3.与我们的非学术合作伙伴Gilead一起，我们将调查对脂质体AmpB配方的潜在修改，以及我们的机制研究可能如何影响使用AmpB的治疗。

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.