Immunochemotherapy in Visceral Leishmaniasis

描述(申请人提供)：这项研究的目标是提高内脏利什曼病(VL)患者的治疗效果。在VL中，寄生虫以组织巨噬细胞为靶点，灭活并复制。除非给予巨噬细胞激活宿主免疫机制或化疗，否则复制不会停止，寄生虫也不会被杀死。因此，优化治疗的一个合理途径是将激活的宿主机制与化疗相结合。该项目的目标是了解宿主机制如何与化疗一起作用，以扩大和加速药物的初始反应，并产生持久的治疗后效果，以防止复发。VL是免疫化疗及其测试的理想候选者，因为在这种感染中：(A)没有疫苗，使药物治疗成为临床治疗的主要手段，(B)可用的化疗并不是最理想的，(C)对激活或灭活耐药性的机制的实验理解是坚实的，并准备好建立在此基础上，(D)可以在体内模型中确定候选宿主机制，以及(E)在已建立的内脏感染中，对这些机制的实验调整既可行又具有治疗作用。尽管如此，我们对VL靶向的特定宿主机制以及如何最好地制定和应用免疫化疗的病因学理解存在差距。我们提出的杜氏利什曼原虫(LD)感染模型将填补这些空白，为未来的化疗干预奠定基础。为了实现特定的目标，研究计划测试体内的反应、既定感染的影响和相关组织焦点中的假设，其中寄生的巨噬细胞、涌入的单核细胞和T细胞以及上调和下调免疫炎症机制都与药物交叉。目的1：确定宿主Th1机制如何将化疗转化为利什曼杀毒。目的1检测控制装配组织肉芽肿内药物反应的机制：潜在的治疗性趋化因子对单个核细胞的募集，GM-CSF诱导的单核细胞内流和肉芽肿重塑，以及改变被包围的、寄生的巨噬细胞的药物药理学的影响。目的2：在一种驱动发病机制和限制化疗的反调节失活机制中，表征并禁用近端和远端靶点。目的2检测该机制的远端效应产物(IL-6、TGF-2、IL-27)，它们位于以IL-10为基础的失活细胞因子网络中，然后由TLR(TLR2)和MAPK(ERK1/2)信号转导途径启动。目的3：分析化疗如何激活宿主免疫机制。目的3检验一种新的相反的想法，即药物治疗本身触发可识别的、相关的和可利用的宿主防御机制，以确保总体疗效。目的3‘S计划在药物治疗时测试对巨噬细胞机制的直接影响，然后将重点放在治疗后阶段，即化疗诱导的、IL-12和诱导型一氧化氮合酶/光子非依赖性机制出现时，协调持续组织感染的静止和长期无复发状态。

DESCRIPTION (provided by applicant): The goal of this research is to improve the efficacy of treatment in patients with visceral leishmaniasis (VL). In VL, parasites target, deactivate and replicate within tissue macrophages. Replication does not cease nor are parasites killed unless macrophage-activating host immune mechanisms supervene or chemotherapy is given. A logical route to optimizing treatment, then, is combining activated host mechanisms with chemotherapy. This project's objective is to understand how host mechanisms act with chemotherapy to amplify and accelerate the initial response to drug and produce long-lasting post-treatment effects to prevent relapse. VL is an ideal candidate for immunochemotherapy and its testing, since in this infection: (a) there is no vaccine, making drug therapy the mainstay of clinical management, (b) available chemotherapy is not optimal, (c) experimental understanding of mechanisms which activate or deactivate resistance is solid and ready to be built upon, (d) candidate host mechanisms can be identified in an in vivo model, and (e) experimental adjustment of these mechanisms is both feasible and therapeutic in established visceral infection. Nonetheless, gaps exist in our pathogenetic understanding of specific host mechanisms to target in VL and in how to best formulate and apply immunochemotherapy. Our proposed work in a model of Leishmania donovani (Ld) infection will fill in these gaps, laying the groundwork for future interventions to employ with chemotherapy. To accomplish the Specific Aims, the Research Plan tests responses in vivo, effects in established infection and hypotheses in the relevant tissue focus where parasitized macrophages, influxing monocytes and T cells, and up- and downregulating immunoinflammatory mechanisms all intersect with drug. Aim 1: Determine how host Th1 mechanisms transform chemotherapy to leishmanicidal. Aim 1 tests mechanisms which govern responses to drug within the assembled tissue granuloma: mononuclear cell recruitment by potentially therapeutic chemokines, GM-CSF-induced blood monocyte influx and granuloma remodeling, and effects which alter drug pharmacology in encircled, parasitized macrophages. Aim 2: Characterize and then disable both proximal and distal targets in a counter regulatory, deactivating mechanism which drives pathogenesis and limits chemotherapy. Aim 2 tests the mechanism's distal effector products (IL-6, TGF-2, IL-27) which reside in an IL-10-based network of deactivating cytokines and then its more proximal initiation by TLR (TLR2) and MAPK (ERK1/2) signal transduction. Aim 3: Analyze how chemo- therapy activates host immune mechanisms. Aim 3 examines the novel converse idea that drug therapy itself triggers identifiable, relevant and exploitable host defense mechanisms to ensure overall efficacy. Aim 3's plan tests direct effects on macrophage mechanisms at the time of drug therapy, and then focuses on the post-treatment period, when a chemotherapy-induced, IL-12- and iNOS/phox-independent mechanism emerges to orchestrate quiescence of persistent tissue infection and the long-term, relapse-free state.