TARGETED DELIVERY OF CYSTEINE PROTEINASE INHIBITORS TO LEISHMANIA

利什曼酶是一组形态相似的鞭毛虫 通过沙蝇媒介传播，存活在沙蝇的吞噬细胞内 脊椎动物寄主并引发一系列不同严重程度的疾病。 利什曼病更令人畏惧的是其极端的组织发病率，其频繁的 并发症，以及治疗的不便和不适，而是 比它的致命率更高。治疗寄生虫的主要药物是 经常需要住院治疗的五价锑化合物 给药，并因毒性而出现并发症。的确有 因此，迫切需要针对这些疾病的替代药物疗法 感染。 该项目提出了两个相互支持的目标，旨在产生一个 利什曼病的新化疗。利什曼原虫的无鞭毛体 驻留在巨噬细胞内，是一种酸性的、具有水解性的 溶酶体隔室。该隔间可通过 宿主细胞的内吞网络。这项提议的第一个目标是 利用某些内细胞性受体的巨噬细胞特异性 在这些吞噬细胞上，以便于选择性地输送和浓缩 巨噬细胞内的活性化合物。因为巨噬细胞是已知的 一种清除血液中毒品的作用，应该能够增强 这种行为是通过将药物与甘露糖/岩藻糖的配体络合而实现的 受体，这是一种巨噬细胞特异性凝集素。这样做的效率 策略将通过与报告分子偶联的配体进行评估，例如 生物素或二硝基苯酚。向寄生性液泡的输送将 用免疫电子显微镜检查。 该项目的第二个目标涉及开发一个已演示的 利什曼原虫无鞭毛体半胱氨酸蛋白酶的选择性 如图所示为某些多肽底物，这些底物抵抗 巨噬细胞溶酶体中的组织蛋白。利用分离的吞噬小体，我们 已经表明寄生虫的酶表现出明显不同的裂解 部位识别，并可被肽酮抑制，从而阻断 寄生虫的生长。我们打算继续进行这些研究，以制定 寄生虫特异性半胱氨酸蛋白酶抑制剂。这些抑制剂将是 与第一个目标中确定的巨噬细胞特异性配体复合， 生产一种抗利什曼的化合物，该化合物将在 优先于巨噬细胞。

The leishmaniases are a group of morphologically-similar flagellates that are transmitted by sandfly vector, survive within the phagocytes of the vertebrate host and induce a spectrum of diseases of varying severity. Leishmaniasis is more feared for its extreme tissue morbidity, its frequent complications, and the inconvience and discomfort of its treatment, rather than its levels of fatality. The mainline drugs against the parasite are pentavalent antimonial compounds that often require hospitalization during administration, and have complications due to toxicity. There is therefore, an urgent need for alternative drug therapies for these infections. This Project proposes two mutually-supportive goals designed to produce a new chemotherapy for leishmaniasis. The amastigote form of Leishmania resides within the macrophage, in an acidic, hydrolytically-active lysosomal compartment. This compartment may be accessed through the endocytic network of the host cell. The first goal of this proposal is to exploit the macrophage-specific nature of some of the endocytic receptors on these phagocytes to facilitate selective delivery and concentration of active compounds within the macrophage. As the macrophage is known to play a role in clearance of drugs from the blood, one should be able to enhance this behavior by complexing the drugs with ligands for the mannose/fucose receptor, which is a macrophage-specific lectin. The efficiency of this strategy will be evaluated with ligands coupled to reporter molecules such as biotin or dinitrophenol. Delivery to the parasitophorous vacuole will be examined by immunoelectron microscopy. The second goal of the Project involves the exploitation of a demonstrated selectivity that the cysteine proteinases of the Leishmania amastigote have shown for certain peptidic substrates that are resistant to hydrolysis by the cathepsins of the macrophage's lysosome. Using isolated phagosomes, we have shown that the parasite enzymes exhibit a markedly different cleavage site recognition, and can be inhibited by peptidoketones, which block parasite growth. We intend to pursue these studies in the development of parasite-specific cysteine proteinase inhibitors. These inhibitors will be complexed with macrophage-specific ligands, identified in the first goal, to produce an antileishmanial compound that will be delivered preferentially to macrophages.