Table_3_Aspergillus fumigatus Challenged by Human Dendritic Cells: Metabolic and Regulatory Pathway Responses Testify a Tight Battle.XLSX

Dendritic cells (DCs) are antigen presenting cells which serve as a passage between the innate and the acquired immunity. Aspergillosis is a major lethal condition in immunocompromised patients caused by the adaptable saprophytic fungus Aspergillus fumigatus. The healthy human immune system is capable to ward off A. fumigatus infections however immune-deficient patients are highly vulnerable to invasive aspergillosis. A. fumigatus can persist during infection due to its ability to survive the immune response of human DCs. Therefore, the study of the metabolism specific to the context of infection may allow us to gain insight into the adaptation strategies of both the pathogen and the immune cells. We established a metabolic model of A. fumigatus central metabolism during infection of DCs and calculated the metabolic pathway (elementary modes; EMs). Transcriptome data were used to identify pathways activated when A. fumigatus is challenged with DCs. In particular, amino acid metabolic pathways, alternative carbon metabolic pathways and stress regulating enzymes were found to be active. Metabolic flux modeling identified further active enzymes such as alcohol dehydrogenase, inositol oxygenase and GTP cyclohydrolase participating in different stress responses in A. fumigatus. These were further validated by qRT-PCR from RNA extracted under these different conditions. For DCs, we outlined the activation of metabolic pathways in response to the confrontation with A. fumigatus. We found the fatty acid metabolism plays a crucial role, along with other metabolic changes. The gene expression data and their analysis illuminate additional regulatory pathways activated in the DCs apart from interleukin regulation. In particular, Toll-like receptor signaling, NOD-like receptor signaling and RIG-I-like receptor signaling were active pathways. Moreover, we identified subnetworks and several novel key regulators such as UBC, EGFR, and CUL3 of DCs to be activated in response to A. fumigatus. In conclusion, we analyze the metabolic and regulatory responses of A. fumigatus and DCs when confronted with each other.

树突状细胞（dendritic cells, DCs）是一类抗原呈递细胞，作为连接固有免疫与适应性免疫的桥梁。曲霉病是由适应性腐生真菌烟曲霉（Aspergillus fumigatus）引发的、免疫功能低下患者的主要致死性疾病。健康人体免疫系统可抵御烟曲霉感染，但免疫缺陷患者极易罹患侵袭性曲霉病。烟曲霉可在感染过程中持续定植，这源于其能够在人体DCs的免疫应答中存活的能力。因此，针对感染特定情境下的代谢研究，有助于深入解析病原体与免疫细胞的适应策略。我们构建了烟曲霉感染DCs过程中的中心代谢模型，并计算得到其代谢通路（初等模式，elementary modes, EMs）。利用转录组数据，我们鉴定了烟曲霉受到DCs刺激时激活的通路。研究发现，氨基酸代谢通路、替代碳源代谢通路以及应激调节酶均处于激活状态。代谢流建模进一步鉴定出乙醇脱氢酶、肌醇加氧酶与GTP环水解酶等参与烟曲霉不同应激反应的活性酶类。上述结果通过在对应培养条件下提取RNA进行定量实时逆转录聚合酶链反应（qRT-PCR）得到了验证。针对DCs，我们分析了其与烟曲霉相互作用时激活的代谢通路。研究发现，脂肪酸代谢发挥关键调控作用，同时伴随其他代谢层面的改变。基因表达数据及其分析揭示了除白细胞介素调控之外，DCs中还存在其他激活的信号通路。具体而言，Toll样受体信号通路、NOD样受体信号通路与RIG-I样受体信号通路均处于激活状态。此外，我们鉴定出DCs中响应烟曲霉感染而激活的子网与多个新型关键调控因子，如UBC、EGFR及CUL3。综上，本研究解析了烟曲霉与DCs相互作用时二者的代谢与调控应答反应。