DEVELOPMENTAL BIOLOGY OF LEISHMANIA PROMASTIGOTES

利什曼原虫前鞭毛体的发育生物学

• 批准号: 6098895
• 负责人: David Sacks
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6098895
• 关键词: Leishmania; Psychodidae; arthropod genetics; communicable disease transmission; digestion; disease vectors; flow cytometry; glycolipids; hamsters; host organism interaction; laboratory mouse; leishmaniasis; life cycle; molecular cloning; polymerase chain reaction; receptor expression; transfection

During the natural transmission of Leishmania, sand flies inoculate low numbers of metacyclic promastigotes, along with saliva, into the skin of the mammalian host. It was previously shown that saliva can enhance the infectivity of Leishmania. Most individuals who live in endemic areas, however, are exposed to saliva from uninfected flies before the bite that transmits infection. We have attempted to establish a model of cutaneous leishmaniasis in the mouse that mimics these natural conditions of infection: low number of metacyclic promastigotes (103), inoculation into the ear dermis, and co-inoculation with salivary lysates from a natural vector, P. papatasi, into naive mice or to mice pre-exposed to saliva. Our studies reveal a dramatic exacerbating effect of saliva on lesion development in the dermal site. The dermal lesions appeared earlier, progressed to a larger size, were more destructive, and contained greater numbers of parasites. Disease exacerbation was associated with the ability of saliva to elicit an early increase (6 hr.) in the frequency of cells producing type 2 cytokines in the epidermis. Furthermore, the exacerbating effect was not seen in IL-4 knockout. The ability of saliva to exacerbate dermal lesions was completely abrogated in mice that had been previously injected with salivary gland lysates. These mice made anti-saliva antibodies that were shown to neutralize the ability of saliva to enhance infection and to elicit type 2 responses in the epidermis. These results introduce the notion that the exposure history of individuals to vector saliva will influence the outcome of infection with Leishmania. There are few reports of successful transmission to experimental animals by bite, and virtually none have explored the host inflammatory and immune response to sand fly initiated infections. A reproducible murine ear model based on the transmission of L. major by bite was established. The model was used to investigate the effect of host presensitization to sand fly saliva via exposure to uninfected sand fly bites on the course of infection. The number of dermal lesions produced was greater, and the progression of lesions, measured by diameter and thickness, was significantly faster in naive mice. Preliminary analyses of the early response in the dermis to the bites of infected flies revealed a dramatic increase in the number of epidermal cells producing type 2 cytokines, especially IL-5, in BALB/c. This response was eliminated in mice pre-exposed to sand fly bites, further supporting a role for these cytokines in the exacerbation of disease by saliva. Despite the importance of L. tropica as the cause of a widely distributed, highly endemic form of cutaneous leishmaniasis in the Old World, no vector studies involving L. tropica have been reported. A laboratory colony of Phlebotomus sergenti, which is the natural vector of L. tropica transmission, was successfully established, and used to reveal a high degree of specificity in vectorial capacity for L. tropica sp. vs. other Leishmania strains. This finding has important epidemiologic considerations.

在利什曼原虫自然传播过程中，沙子 苍蝇接种少量的后循环前鞭毛体，以及 唾液进入哺乳动物宿主的皮肤。以前是 研究表明，唾液可以增强利什曼原虫的传染性。最多 然而，生活在流行地区的人会接触到 在传播感染的叮咬之前未受感染的苍蝇的唾液。 我们试图建立皮肤利什曼病模型 在模仿这些自然感染条件的小鼠中：低 后循环前鞭毛体数量 (103)，接种到耳朵中 真皮，并与天然唾液裂解物共同接种 载体 P. papatasi，进入幼稚小鼠或预先暴露于 唾液。我们的研究揭示了唾液对 真皮部位的病变发展。真皮病变出现 更早，发展到更大的尺寸，更具破坏性，并且 含有较多数量的寄生虫。疾病恶化是 与唾液引起早期增加的能力有关（6小时） 细胞中产生 2 型细胞因子的频率 表皮。此外，在 IL-4 敲除。唾液加剧真皮病变的能力 在之前注射过的小鼠中被完全消除 与唾液腺裂解物。这些小鼠产生了抗唾液抗体 已被证明可以中和唾液增强的能力 感染并引起表皮2型反应。这些 结果引入了这样一个概念：个人的暴露史 媒介唾液会影响感染的结果 利什曼原虫。很少有关于成功传输的报告 实验动物被咬，几乎没有人探索过 宿主对白蛉的炎症和免疫反应启动 感染。基于可重复的小鼠耳模型 已确定主要利斯特氏菌通过叮咬传播。该模型是 用于研究宿主预敏化对白蛉的影响 通过在感染过程中暴露于未感染的白蛉叮咬而产生唾液 感染。产生的真皮损伤数量较多，并且 通过直径和厚度测量病变的进展情况 在幼鼠中明显更快。早期的初步分析 真皮对受感染苍蝇叮咬的反应揭示了 产生 2 型的表皮细胞数量急剧增加 BALB/c 中的细胞因子，尤其是 IL-5。这个回应是 在预先暴露于沙蝇叮咬的小鼠中被消除，进一步支持 这些细胞因子在唾液引起的疾病恶化中发挥作用。 尽管热带乳杆菌作为广泛感染的原因具有重要意义， 皮肤利什曼病的分布、高度流行形式 旧世界，没有涉及热带乳杆菌的媒介研究 报道称。塞氏白蛉 (Phlebotomus sergenti) 的一个实验室群体，它是 热带乳杆菌传播的自然载体，已成功 建立并用于揭示高度的特异性 L. tropica sp 的矢量容量。与其他利什曼原虫菌株相比。 这一发现具有重要的流行病学考虑。