Biodegradable Nanoparticles for Targeted Antibiotic Delivery

描述(由申请人提供)：人类感染细胞内的沙眼衣原体和肺炎衣原体是一个巨大的卫生保健问题。这些病原体的感染与几种慢性病的产生和/或恶化有关，其中一些衣原体感染已被证明对抗生素治疗无效。治疗效果的缺乏是由于在某些情况下感染衣原体的代谢率减弱，再加上此类药物正常输送到衣原体驻留在宿主细胞细胞质中的包涵体所能达到的适度细胞内浓度。本文概述的研究的主要治疗目标是开发一种方法，通过这种方法，抗生素或其他治疗剂可以以有效浓度的靶向方式输送到细胞内的衣原体包裹体，而不会对宿主细胞或受感染的组织产生毒性。我们的初步研究表明，衣原体感染引起宿主细胞叶酸受体(FAR)表达增加，叶酸偶联纳米粒可能提供一种新的高效的细胞内给药途径。支持这项研究的工作假设是，感染沙眼衣原体或肺炎衣原体的宿主细胞可以通过纳米颗粒介导的靶向传递有效浓度的抗生素来清除活跃或持续感染的有机体，这些抗生素已知对活跃的衣原体感染有效。我们进一步假设，纳米颗粒促进的传递将需要更少的治疗材料，这可能会显著降低医疗成本。为了实现这一目标，将实现三个具体目标。在第一个目标中，我们将确定相关的人类沙眼衣原体感染宿主细胞在培养中和在沙眼衣原体感染的小鼠模型中叶酸受体表达的时程，并确定叶酸受体在宿主细胞和细胞质包涵膜之间的定位。在第二个目标中，我们将确定在体外感染后的哪个时间点，这些纳米颗粒是最有效的，以及通过纳米颗粒将抗生素输送到受感染的细胞是否有效清除沙眼衣原体感染。此外，利用荧光显微镜，我们将研究纳米颗粒在感染和未感染细胞中的细胞内转运，以了解纳米颗粒靶向包裹体的机制。目的三，利用体内成像、分子遗传学和定量分析方法，我们确定远靶向将纳米抗生素输送到衣原体感染的小鼠是否清除了体内的滑膜感染。如果成功，这项研究的结果将建议一种新的基于纳米技术的治疗方案，用于有效治疗一个重要的医疗保健问题。 公共卫生相关性：衣原体与几种慢性疾病有关，包括炎性关节炎、导致异位妊娠的输卵管闭塞和宫颈癌(沙眼衣原体)；肺炎衣原体与动脉粥样硬化、炎性关节炎和颞动脉炎等密切相关。这项拟议的研究预计将对人类健康产生积极影响，因为它有望导致开发一种治疗持续性衣原体感染的有效方法。

DESCRIPTION (provided by applicant): Human infections by the intracellular bacterial pathogens Chlamydia trachomatis and C pneumoniae present an enormous health care problem. Infections by these pathogens have been associated with engendering and/or exacerbating several chronic diseases, and some of these Chlamydial infections have proved to be refractory to antibiotic therapy. The lack of therapeutic efficacy results from the attenuated metabolic rate of infecting chlamydiae under some circumstances, in combination with the modest intracellular concentrations achievable by normal delivery of such drugs to the inclusions within which chlamydiae reside in the host cell cytoplasm. The major therapeutic goal of the studies outlined here is to develop a means by which antibiotics or other therapeutic agents can be delivered in a targeted manner to the intracellular Chlamydial inclusion at effective concentrations, without toxicity to the host cell or infected tissue. Our initial studies indicate that Chlamydial infection elicits increased expression of host cell folic acid receptors (FAR), and that folic acid-conjugated nanoparticles may provide a novel and highly effective means of intracellular delivery of therapeutic agents to Chlamydia- infected cells. The working hypothesis underlying the studies proposed is that host cells infected with either C trachomatis or C pneumoniae can be cleared of actively- or persistently-infecting organisms via nanoparticle-mediated targeted delivery of effective concentrations of antibiotics known to work against active Chlamydial infections. We further hypothesize that nanoparticle-facilitated delivery will require reduced amounts of therapeutic materials, which could engender significant health care cost reductions. To pursue that end, three Specific Aims will be addressed. In Aim One, we will define the time-course of expression of folate receptors following C trachomatis infection of a relevant panel of human host cells in culture and in a mouse model of C trachomatis infection, and define the localization of folic acid receptors between the host cell and cytoplasmic inclusion membranes. In Aim Two, we will determine at what time point post-in vitro infection delivery of those nanoparticles is most effective, and whether delivery of antibiotics to infected cells by nanoparticles is effective in clearing C trachomatis infection. In addition, using fluorescence microscopy, we will study the intracellular trafficking of nanoparticles in infected and uninfected cells to understand the mechanism of nanoparticle targeting to inclusions. In Aim Three, using in vivo imaging, molecular genetics, and quantitative analytical methods, we determine if FAR targeted delivery of nanoparticle antibiotics to Chlamydia-infected mice clears synovial infection in vivo. If successful, results of this research will suggest a novel nanotechnology-based therapeutic regimen for effective treatment of an important health care problem. PUBLIC HEALTH RELEVANCE: Chlamydiae are associated with several chronic diseases, including inflammatory arthritis, tubal occlusion leading to ectopic pregnancy, and cervical cancer (C trachomatis); C pneumoniae has been compellingly associated with atherosclerosis, inflammatory arthritis, and temporal arteritis, among several others. The proposed research is expected to positively affect human health, because, it is expected to lead to the development of an effective approach for the treatment of persistent Chlamydial infections.