Characterization of CCR5-like Molecules in Leishmania

描述（由申请方提供）：利什曼原虫感染可在人体内引起广谱利什曼酶。虽然众所周知，宿主和寄生虫衍生的因素有助于疾病的结果，我们的知识，他们的分子相互作用仍然相对有限。本申请的长期目标是确定宿主对L易感性的潜在机制。亚马逊河（La）感染。与La感染相关的皮肤利什曼病的一个标志是对寄生虫的细胞免疫的严重缺陷。Th 1细胞因子和炎性CC-趋化因子的产生不足与小鼠La感染的疾病进展相关。我们的抗体和配体为基础的研究表明，病变和培养的La和L。mexicana寄生虫可以表达CCR 5样分子。这些发现导致了利什曼原虫寄生虫表达一种或多种模拟和干扰宿主CCR 5系统的分子的假设，从而促进寄生虫归巢至其靶细胞和/或原位调节趋化因子应答。这一假设将在两个特定目标中同时进行检验。目的1是确认CCR 5样分子在不同种/株利什曼原虫中的表达，并研究其表达在宿主-寄生虫相互作用中的生物学相关性。我们的努力将主要放在使用鼠和人CCR 5配体以及不与CCR 5结合的配体进行功能研究（Ca++流入、趋化性和配体结合/内化测定）上。目的2是表征寄生虫来源的CCR 5编码基因，并确定这些蛋白质的性质。编码CCR 5样分子的基因将用于与其哺乳动物或病毒对应物进行序列比较。将产生表达LaCCR 5和对利什曼原虫CCR 5样蛋白特异性的抗体的稳定细胞系，用于在功能测定中重新评价。 这项拟议的研究是新颖的和高度重要的，因为，虽然存在可靠的证据，宿主细胞因子/趋化因子及其受体的分子模拟的许多病原体，包括DNA病毒，弓形虫，曼氏血吸虫，这种模拟尚未确定锥虫。事实上，试剂已经到位，与PI在免疫学和分子生物学方面的经验相联系，确保了这项探索性资助的可行性。如果被证明是正确的，这项研究将首次证明利什曼原虫中存在功能性CCR 5同源物。这一应用将极大地扩展我们目前对利什曼原虫生物学的理解，并为进一步深入研究宿主-寄生虫相互作用奠定基础。

DESCRIPTION (provided by applicant): Leishmania infection can cause a broad spectrum of leishmaniases in humans. Although it is well known that host- and parasite-derived factors contribute to disease outcome, our knowledge about their molecular interactions is still relatively limited. The long-term goal of this application is to define the mechanism(s) underlying the host susceptibility to L. amazonensis (La) infection. A hallmark of cutaneous leishmaniasis associated with La infection is the profound deficiency in cellular immunity to the parasite. An insufficient production of Th1 cytokines and inflammatory CC-chemokines is correlated with disease progression in murine La infection. Our antibody- and ligand-based studies have revealed that lesional and cultured La and L. mexicana parasites can express CCR5-like molecules. These findings have led to the hypothesis that Leishmania parasites express one or more molecules that mimic and interfere with the host CCR5 system, thus promoting homing of parasites to their target cells and/or modulating chemokine responses in situ. This hypothesis will be tested concurrently in two Specific Aims. Aim 1 is to confirm the expression of CCR5-like molecules in different species/strains of Leishmania and to examine the biological relevance of their expression in host-parasite interaction. Our efforts will mostly be placed on conducting functional studies (Ca++ influx, chemotaxis and ligand binding/internalization assays) using murine and human CCR5 ligands, as well as ligands that do not bind to CCR5. Aim 2 is to characterize the gene encoding parasite-derived CCR5 and define the nature of these proteins. The gene encoding CCR5-like molecules will be used for sequence comparison with their mammalian or viral counterparts. Stable cell lines expressing LaCCR5 and antibodies specific to leishmanial CCR5-like proteins will be generated for re-evaluation in functional assays. This proposed study is novel and highly significant because, while solid evidence exists for molecular mimicry of host cytokines/chemokines and their receptors by many pathogens, including DNA viruses, Toxoplasma gondii, and Schistosoma mansoni, such mimicry has not been identified for trypanosomatids. The fact that reagents are in place, linked with the PI's experience in immunology and molecular biology, ensures the feasibility of this exploratory grant. If proven correct, this study would, for the first time, demonstrate the presence of a functional CCR5 homologue(s) in Leishmania parasites. This application would greatly extend our current understanding of Leishmania biology and lay the foundation for additional in-depth investigations of host-parasite interactions.