Transcriptional regulation of A. fumigatus virulence

描述(由申请人提供)：侵袭性曲霉病是免疫功能低下的宿主中最可怕的疾病之一，其发病率正在稳步上升。尽管有新的治疗方法，但这种疾病的死亡率超过50%。侵袭性曲霉病发病机制中的关键步骤是烟曲霉菌与肺上皮细胞的相互作用。 吸入后，烟曲霉分生孢子附着并被排列在肺泡内的上皮细胞吞噬。在敏感宿主中，这些分生孢子萌发形成菌丝，菌丝离开肺上皮细胞，侵入更深的组织。在之前的项目期间，我们确定了烟曲霉菌的关键转录调控因子，这些转录调控因子在体外与宿主细胞的相互作用以及在免疫抑制小鼠侵袭性疾病期间的毒力。利用转录图谱，我们发现了这些转录的潜在靶基因 监管者。我们的初步数据表明，这些靶基因编码了新发现的毒力因子，这些毒力因子在烟曲霉与肺上皮细胞和天然免疫系统的致病相互作用中起重要作用。这项建议中描述的实验将识别和表征两种新发现的烟曲霉菌表面分子及其宿主细胞受体。第一种是烟曲霉菌半乳糖氨基半乳糖半乳糖半乳糖第二组真菌细胞表面分子由三个烟曲霉菌蛋白组成，它们可能作为真菌配体，介导该微生物与肺上皮细胞的致病相互作用。我们将通过以下方式研究这两种表面分子：(1)确定GAG和候选真菌配体在体外宿主细胞相互作用中的作用；(2)阐明它们影响侵袭性肺曲霉菌病小鼠模型毒力的机制；以及(3)鉴定它们的同源宿主细胞受体。此外，我们将确定GAG是否以及如何影响真菌配体的功能和表面表达，以及真菌配体是否反过来影响GAG和β-葡聚糖的表面暴露。利用这一研究机构，我们的最终目标是开发新的治疗策略 以阻止烟曲霉菌的黏附和入侵。改进侵袭性曲霉病的治疗势在必行，因为免疫功能低下的患者群体不断扩大，他们面临着这种严重且危及生命的疾病的高风险。

DESCRIPTION (provided by applicant): Invasive aspergillosis is one of the most feared diseases in the immunocompromised host, and its incidence is steadily increasing. Despite new therapies, the mortality of this disease is greater than 50%. A critical step in the pathogenesis o invasive aspergillosis is the interaction of Aspergillus fumigatus with pulmonary epithelial cells. After being inhaled, A. fumigatus conidia adhere to and are endocytosed by the epithelial cells that line the alveoli. In susceptible hosts, these conidia then germinate to form hyphae, which exit the pulmonary epithelial cells and invade the deeper tissues. During the previous project period, we identified key transcriptional regulators of A. fumigatus that govern both its interactions with host cells in vitro and virulence during invasive disease in immunosuppressed mice. Using transcriptional profiling, we uncovered potential target genes of these transcriptional regulators. Our preliminary data indicate that these target genes encode newly identified virulence factors that are important for the pathogenic interactions of A. fumigatus with pulmonary epithelial cells and the innate immune system. The experiments described in this proposal will identify and characterize two types of newly discovered A. fumigatus surface molecules and their host cell receptors. The first is A. fumigatus galactosaminogalactan (GAG), which is a novel pathogen-associated molecular pattern (PAMP) that likely plays important roles in both adherence to host constituents and modulation of the inflammatory response. The second set of fungal cell surface molecules consists of three A. fumigatus proteins that likely function as fungal ligands which mediate the pathogenic interactions of this organism with pulmonary epithelial cells. We will investigate both types of surface molecules by: (1) determining the roles of GAG and the candidate fungal ligands in host cell interactions in vitro; (2) elucidating the mechanisms by which they influence virulence in mouse models of invasive pulmonary aspergillosis; and (3) identifying their cognate host cell receptors. Furthermore, we will determine if and how GAG influences the function and surface expression of the fungal ligands, and whether the fungal ligands in turn influence the surface exposure of GAG and ¿-glucan. Utilizing this body of research, our ultimate goal is to develop new therapeutic strategies to block A. fumigatus adherence and invasion. It is imperative to improve therapy for invasive aspergillosis because of the expanding population of immunocompromised patients who at high risk for this serious and life-threatening disease.