Impact of Candida Oxylipins on Host Immunity and Fungal Biology

描述（由申请人提供）：机会性真菌病原体白色念珠菌产生免疫调节性氧化脂素，与宿主类二十烷（前列腺素和白三烯）发生功能性交叉反应，是先天和适应性免疫反应的有效调节剂。此外，念珠菌可以在宿主脂肪酸前体存在的情况下产生真正的宿主二十烷酸。尽管宿主和酵母都可以产生类似的信号分子，但氧脂素在宿主-病原体相互作用中的作用尚未得到充分表征，真菌氧脂素生物合成酶也尚未被确定。缺乏这些知识是一个重要的问题，因为它限制了针对致病真菌中这些途径的新治疗策略的发展，其中大多数产生氧化脂素。本研究的长期目标是表征念珠菌在宿主体内的持久性和免疫调节机制。本提案的目的是确定真菌氧化脂素和宿主类二十烷酸在影响念珠菌生物学和宿主免疫中的作用。我们的中心假设是，真菌和宿主产生的氧化脂素在调节真菌的微生物学和宿主-病原体相互作用中至关重要，有利于慢性感染或持久性。该研究的基本原理是确定宿主和真菌氧化脂素在宿主-微生物相互作用中的作用，将提供有关念珠菌影响免疫机制的关键信息，并促进开发用于治疗和控制真菌感染的新型药理干预措施。第一个特定的目标将是利用分子方法-过表达和靶向诱变-识别和表征与氧化脂素产生和发病有关的念珠菌基因。突变体将使用体外分析来检查形态发生和生物膜形成以及假丝酵母菌病的体内模型。第二个具体目标将是确定真菌和宿主氧脂素对念珠菌生物学（形态发生和生物膜形成）和抗真菌药物敏感性的影响。第三个具体目标将是确定真菌和宿主氧脂素对宿主-病原体相互作用的下游影响，包括体内和与树突状细胞（dc）的相互作用。体内分析将涉及在全身和粘膜感染模型中使用前列腺素抑制剂和环氧化酶敲除小鼠（负责前列腺素产生的宿主酶）。DC分析将包括研究氧脂素在体外和体内DC疫苗接种过程中对DC成熟和激活的影响。我们对这一研究领域的贡献有望是对氧化脂素如何产生及其在念珠菌发病机制和生物学中的作用的详细了解。这一贡献是重要的，因为它有望为开发专门针对这些免疫调节真菌生物活性脂类产生的生物合成途径的药理学策略提供所需的知识，并提供有关氧化脂类和二十烷类在宿主-病原体相互作用中的作用的信息。这项工作的结果将对治疗念珠菌相关疾病的公共卫生产生积极影响，因为氧化脂素途径有望提供新的治疗靶点。这些研究将对了解所有致病真菌微生物的毒力策略具有重要意义，其中大多数产生氧化脂素。更重要的是，用类二十烷类抑制剂靶向真菌氧脂素途径是一种可用于调节感染过程的新策略。这些药物有可能干扰真菌和宿主，阻止真菌的形态发生、氧脂素的产生和生存能力，并影响免疫反应。

DESCRIPTION (provided by applicant): The opportunistic fungal pathogen Candida albicans produces immunomodulatory oxylipins that cross- react functionally with host eicosanoids (prostaglandins and leukotrienes), which are potent regulators of innate and adaptive immune responses. In addition, Candida can produce authentic host eicosanoids in the presence of host fatty acid precursors. Despite the fact that both the host and yeast can produce similar signaling molecules, the role of oxylipins in host-pathogen interactions has not been fully characterized nor have the fungal oxylipin biosynthetic enzymes been identified. Lack of such knowledge is an important problem, because it limits development of novel therapeutic strategies that target these pathways in pathogenic fungi, most of which produce oxylipins. The long term goal of this research is to characterize mechanisms of Candida persistence and immunomodulation in the host. The objective of this proposal is to determine the role of fungal oxylipins and host eicosanoids in influencing Candida biology and host immunity. Our central hypothesis is that production of oxylipins by both fungi and host are crucial in modulating the microbiology of the fungus and the host-pathogen interaction in favor of chronic infection or persistence. The rationale for the proposed research is that determining the role of host and fungal oxylipins in host-microbe interactions will provide key information about the mechanisms by which Candida influences immunity and facilitate development of novel pharmacological interventions for treatment and control of fungal infection. The first specific aim will be to identify and characterize Candida genes involved in oxylipin production and pathogenesis using molecular methods-both overexpression and targeted mutagenesis. Mutants will be analyzed using in vitro assays to examine morphogenesis and biofilm formation and in vivo models of candidiasis. The second specific aim will be to determine the effects of the effects of fungal and host oxylipins on Candida biology (morphogenesis and biofilm formation) and susceptibility to antifungal drugs. The third specific aim will be to determine the downstream effects of fungal and host oxylipins on host-pathogen interactions, both in vivo and with dendritic cells (DCs). In vivo analysis will involve the use of prostaglandin inhibitors and cyclooxygenase knockout mice (host enzyme responsible for prostaglandin production) during systemic and mucosal infection models. DC analysis will involve studying the effects of oxylipins on maturation and activation of DCs in vitro and during DC vaccination in vivo. Our contribution to this area of research is expected to be a detailed understanding of how oxylipins are produced and their roles in Candida pathogenesis and biology. This contribution is significant because it is expected to provide the knowledge needed to develop pharmacologic strategies that specifically target the biosynthetic pathways involved in production of these immunomodulatory fungal bioactive lipids and provide information regarding the role of oxylipins and eicosanoids during host-pathogen interactions. PUBLIC HEALTH RELEVANCE Results from this work will have a positive impact on public health in terms of treating Candida-associated diseases, as oxylipin pathways are expected to provide novel therapeutic targets. These studies will have important implications for understanding virulence strategies of all pathogenic fungal microbes, most of which produce oxylipins. More importantly, targeting fungal oxylipin pathways with eicosanoid inhibitors is a novel strategy that can be used to modulate the course of an infection. These drugs have the potential to interfere with both the fungus and the host, preventing fungal morphogenesis, oxylipin production, and viability, and also influencing immune responses.