Genetic Determinants of Aspergillus host-pathogen interactions

我们工作的长期目标是通过以下方式减少与曲霉感染相关的发病率和死亡率 改善宿主-病原体相互作用的结果。摘要烟曲霉是空气传播的主要真菌病原菌。 并导致一系列临床症状，其严重程度取决于宿主的免疫状态。 免疫功能严重受损的宿主可发生侵袭性肺曲霉菌病和播散性感染 而且通常与高达90%的死亡率有关。在免疫活性宿主中，烟曲霉菌定植 可导致慢性肺曲霉菌病(CPA)，这是一种最近被诊断为 每年影响160多万人的标准。许多注册会计师患者都有潜在的 呼吸道疾病，如哮喘或囊性纤维化，因肺炎病毒的存在而进一步加重 真菌。尽管多种病原体相关分子模式(PAMP)驱动宿主识别和 反应是已知的，发现了可以作为治疗靶点的新的真菌分子途径 增强或掩蔽PAMP展示和/或生物合成可证明是调节宿主有用治疗靶点 对改善结果的反应。为了解决这个问题，我们利用了炎症体的激活，这是一种多蛋白 检测病原体以引发炎症反应的细胞内复合体，作为揭示 曲霉菌突变体具有激活宿主反应的能力改变。我们已经完成了初步筛选 应用烟曲霉菌测定巨噬细胞分化的人单核细胞系IL-1β的分泌 最近在我们实验室建立了蛋白激酶干扰文库。在筛选出的118个蛋白激酶中断突变中， 我们鉴定了7种显著增加(n=2)或减少(n=5)的烟曲霉菌蛋白激酶。 干扰时依赖炎症体的IL-1β的分泌。令人惊讶的是，这两种蛋白激酶的破坏 诱导IL-1β释放增加的突变体编码磷酸中继感受器组氨酸激酶(phkA和fhk3)， 蛋白激酶的一个亚类，直接感知环境和细胞内的变化，随后 激活压力反应信号。由PhkA和Fhk3控制的分子通路是未知的，因为两者 HKS在很大程度上没有特征。尽管HK信号的一个主要结果是应激反应的激活 上调转录因子活性以响应环境刺激的途径，下游 所有烟曲霉HKS的转录效应物仍未被描述。我们的工作将描述烟曲霉菌 依赖组氨酸激酶(HK)的寄主反应机制(目标1)和鉴定烟曲霉菌转录 炎性小体激活的调节剂(目标2)。通过完成建议的目标，我们将划定 曲霉菌诱导宿主反应的真菌分子途径。这项工作对今后的工作至关重要。 开发新的治疗方法，以激活对侵袭性感染的保护 或减轻慢性感染期间有害的宿主反应。

The long-term goal of our work is to reduce the morbidity and mortality associated with Aspergillus infections by improving outcomes of host-pathogen interactions. Aspergillus fumigatus is the major airborne fungal pathogen and is responsible for a range of clinical syndromes, the severity of which is dependent on host immune status. Invasive pulmonary aspergillosis and disseminated infections can occur in severely immunocompromised hosts and are often associated with mortality rates of up to 90%. In immune competent hosts, A. fumigatus colonization can lead to chronic pulmonary aspergillosis (CPA), a clinical manifestation with recently defined diagnostic criteria that impacts upwards of 1.6 million individuals per year. Many individuals with CPA have underlying respiratory conditions, such as asthma or cystic fibrosis, that are further exacerbated by the presence of the fungus. Although multiple Pathogen-Associated Molecular Patterns (PAMPs) driving host recognition and response are known, uncovering novel fungal molecular pathways that could serve as therapeutic targets to enhance or mask PAMP display and/or biosynthesis could prove useful therapeutic targets to modulate host response for improved outcomes. To address this, we utilized activation of the inflammasome, a multiprotein intracellular complex that detects pathogenic organisms to initiate inflammatory responses, as a tool to uncover Aspergillus mutants with altered abilities to activate host response. We have completed a preliminary screen to measure IL-1β secretion from a macrophage differentiated human monocyte cell line employing an A. fumigatus protein kinase disruption library recently generated in our lab. Of 118 protein kinase disruption mutants screened, we identified seven A. fumigatus protein kinases that either significantly increased (n=2) or decreased (n=5) inflammasome-dependent IL-1β secretion upon disruption. Strikingly, both of the protein kinase disruption mutants that induced increased IL-1β release encode phospho-relay sensor histidine kinases (phkA and fhk3), a sub-class of protein kinases that directly sense environmental and intracellular changes and subsequently activate stress response signaling. The molecular pathways controlled by PhkA and Fhk3 are unknown, as both HKs are largely uncharacterized. Although a major consequence of HK signaling is activation of stress responses pathways that upregulate transcription factor activity to respond to environmental stimuli, the downstream transcriptional effectors for all A. fumigatus HKs remain undescribed. Our work will delineate A. fumigatus histidine kinase (HK)-dependent mechanisms of host response (Aim 1) and identify A. fumigatus transcriptional regulators of inflammasome activation (Aim 2). Through completion of the proposed Aims, we will delineate fungal molecular pathways mediating Aspergillus-induced host response. This work is essential for future development of novel therapeutic approaches targeted towards activating protection against invasive infections or mitigating harmful host-response during chronic infections.