Cryptococcal Chitin Synthase 3 and Host Immune Responses

项目总结/摘要 新型隐球菌感染是艾滋病患者发病和死亡的重要原因， 是器官移植受者中第三常见的侵袭性真菌感染。据估计， 每年有100万隐球菌脑膜炎病例，导致约20万人死亡。因为宿主免疫 反应对于控制隐球菌病至关重要，我的长期目标是描述宿主：真菌 影响C的相互作用。新生儿发病机制或清除率。之间的主要接口之一 真菌和宿主是真菌细胞壁。隐球菌的细胞壁是不寻常的，因为几丁质是 主要脱乙酰化成壳聚糖。壳聚糖缺陷型C.发现新形虫无毒 并迅速从鼠肺中清除。此外，用壳聚糖缺陷型C.新生 缺乏三个几丁质脱乙酰酶（cda 1 Δ2Δ3Δ）的小鼠， 用毒性野生型对应物攻击。除了几丁质脱乙酰基酶之外，以前还显示 几丁质合成酶3（Chs 3）也是几丁质脱乙酰酶介导的壳聚糖形成所必需的。小鼠 接种 chs3Δ 在先前显示的在36小时内诱导cda 1 Δ2Δ3Δ die保护的剂量下， 真菌有机体的安装。死亡是剂量依赖性的，因为给予较低剂量的小鼠没有死亡。 死亡率不依赖于活真菌，因为小鼠接种了热灭活的 chs3Δ 死亡率与 用活的chs 3 Δ接种小鼠，表明死亡的快速发生是宿主介导的，可能是由 过度的免疫反应总之，这些研究使我们假设Chs 3在 抑制隐球菌诱导的宿主炎症反应。在本申请中，我们旨在定义 宿主内触发对chs 3 Δ的异常免疫应答并鉴定细胞免疫应答的机制。 来自chs 3 Δ的引起这种非保护性促炎反应的组分。在此提出的工作 应用程序将对基础科学知识产生重大的整体影响，这将为其他领域提供见解。 病原微生物和生物学领域，以及潜在地推进我们对一个重要的 隐球菌病患者的管理问题。这种K22方法将为我提供机会， 不仅了解驱动宿主反应的途径和驱动免疫应答的隐球菌成分， 免疫反应，而且保护性和非保护性先天宿主反应之间的分歧。的 Wormley，Doering和Lodge实验室，以及知识和 获得的经验使我有能力和机会成为一名独立的研究人员， 追求成功的事业研究主机：病原体相互作用。这项工作将为今后的工作奠定基础。 RO 1应用以及研究宿主的职业生涯：影响真菌发病机制的真菌相互作用 或许可。

PROJECT SUMMARY/ABSTRACT Cryptococcus neoformans infections are a significant cause of morbidity and mortality among AIDS patients and the third most common invasive fungal infection in organ transplant recipients. There are an estimated quarter million cases of cryptococcal meningitis each year resulting in ~200,000 deaths. Because host immune responses are so vital to the control of cryptococcosis, my long-term goal is to delineate the host: fungal interactions that impact C. neoformans pathogenesis or clearance. One of the main interfaces between the fungus and the host is the fungal cell wall. The cell wall in Cryptococcus is unusual in that the chitin is predominantly deacetylated to chitosan. Chitosan deficient strains of C. neoformans were found to be avirulent and were rapidly cleared from the murine lung. Moreover, infection with a chitosan deficient C. neoformans lacking three chitin deacetylases (cda1Δ2Δ3Δ) was found to confer protective immunity to a subsequent challenge with a virulent wild type counterpart. In addition to the chitin deacetylases, it was previously shown that chitin synthase 3 (Chs3) is also essential for chitin deacetylase mediated formation of chitosan. Mice inoculated with chs3Δ at a dose previously shown to induce protection with cda1Δ2Δ3Δ die within 36 hours after installation of the fungal organism. Death is dose dependent as mice given a lower dose did not succumb. Mortality was not dependent on viable fungi as mice inoculated with heat-killed chs3Δ died at the same rate as mice inoculated with live chs3Δ, suggesting that the rapid onset of death was host mediated likely caused by an over exuberant immune response. Altogether, these studies lead us to hypothesize that Chs3 plays a critical role in dampening cryptococcal induced host inflammatory responses. In this application we aim to define the mechanism(s) within the host that trigger the aberrant immune response to chs3Δ and identify the cellular component(s) from chs3Δ that elicit this non-protective pro-inflammatory response. The work proposed in this application will have significant overall impact on basic science knowledge, which will provide insights into other pathogenic microbes and areas of biology, as well as potentially advance our understanding of a significant problem in the management of cryptococcal patients. This K22 approach will provide me with opportunities to not only understand the pathways that drive the host response and the cryptococcal components that drive the immune response, but also the bifurcation between protective and non-protective innate host responses. The mentorship received in Drs. Wormley, Doering, and Lodge laboratories, as well as the knowledge and experiences gained has afforded me the skills and opportunities to become an independent researcher and to pursue a successful career studying host: pathogen interactions. This work will provide the foundation for future RO1 applications as well as a career investigating the host: fungal interactions that impact fungal pathogenesis or clearance.