Targeted Delivery of Anthrax Inhibitors

描述（由申请人提供）：该项目的总体目标是开发一种靶向递送炭疽毒素抑制剂的系统。目前被批准用于炭疽暴露后治疗的抗生素治疗对毒血症无效，毒血症是由含有保护性抗原（PA）和致死或水肿因子（LF或EF）的炭疽毒素引起的。一些研究小组开发了毒素酶活性的小分子抑制剂，可以阻断细胞内的毒素。然而，膜透性差、血液清除率快、这些化合物的工作浓度相对较高是目前尚未解决的严重问题。为了克服这些问题，我们建议将抑制剂封装到靶向脂质体中，通过炭疽受体（ANTXR）在细胞内递送。为了测试这种方法，我们将在脂质体中配制一种小分子LF抑制剂（IC50 ~ 1¿M），并修饰LFn， LFn是具有pa结合活性的LF的无毒片段。我们最近报道了lfn脂质体通过pa依赖的antxr介导的内吞作用迅速内化，为靶向细胞内药物递送提供了新的机会。在项目的这一部分中，我们将确定lfn -脂质体是否向表达ANTXR的细胞提供治疗相关剂量的特定小分子LF抑制剂，并在毒血症小鼠模型中验证lfn -脂质体的保护作用。以下具体目标旨在测试我们方法的可行性：验证LFn-脂质体在体内的靶向性。具体目标2。优化lfn脂质体对LF抑制剂的有效递送。具体目标#3。目的：探讨lfn靶向脂质体在毒血症小鼠模型中的作用。完成这些具体目标将确定LFn-脂质体用于给药的可行性。在II期，我们将开发结合LF和EF抑制剂的lfn -脂质体，在炭疽感染的动物模型中验证这些脂质体，并进行IND申请所需的临床前步骤。

DESCRIPTION (provided by applicant): The overall goal of this project is to develop a system for targeted delivery of anthrax toxin inhibitors. Antibiotic treatment currently approved as a post-exposure anthrax therapy is not effective against toxemia, which is induced by anthrax toxins comprising protective antigen (PA) and lethal or edema factors (LF or EF). Several groups develop small molecule inhibitors of toxin enzymatic activity that block toxins inside the cell. However poor membrane permeability, rapid blood clearance, and relatively high working concentrations of these compounds are serious problems that have not been solved so far. To overcome these problems, we propose to encapsulate inhibitors into targeted liposomes for intracellular delivery via anthrax receptors (ANTXR). To test this approach, we will formulate a small-molecule LF inhibitor (IC50 ~ 1 ¿M) into liposome decorated with LFn, a non-toxic fragment of LF with the PA-binding activity. We have recently reported that LFn-liposomes are rapidly internalized via PA-dependent ANTXR-mediated endocytosis, providing new opportunities for targeted intracellular drug delivery. In this part of the project we will establish if LFn-liposomes deliver therapeutically relevant doses of a specific small-molecule LF inhibitor to ANTXR expressing cells and validate protective effect of LFn-liposomes in a toxemia mouse model. The following specific aims are designed to test feasibility of our approach: Specific aim #1. To validate targeting of LFn- liposomes in vivo. Specific aim #2. To optimize LFn-liposomes for efficient delivery of LF inhibitor. Specific aim #3. To establish efficiency of LFn-targeted liposomes in a toxemia mouse model. Accomplishing these specific aims will establish feasibility of using LFn- liposomes for drug delivery. In Phase II we will develop LFn-liposomes with combination of LF and EF inhibitors, validate these liposomes in animal models of anthrax infection, and pre-clinical steps required for IND filing.