Interactions of pDCs with Aspergilus

描述（由申请人提供）：烟曲霉是侵袭性霉菌感染的最常见原因。即使在治疗和早期诊断方面取得了进展，死亡率仍然很高。浆细胞样树突状细胞（pDC）包含功能上不同的DC谱系，其在用病毒刺激时主要通过依赖于病毒核酸的感测的机制快速产生大量的I型干扰素（IFN）。pDC通过分泌细胞因子和通过引发T细胞将先天免疫与获得性免疫联系起来。pDC和真菌之间的相互作用尚未得到很好的表征。该应用建立在令人信服的初步数据基础上，这些数据表明：1）人pDC通过涉及A.烟曲霉诱导的pDC死亡; 2）用A. pDC的耗竭使小鼠对A. fumigatus菌丝的肺和静脉内攻击高度敏感。烟曲霉通过一种机制，似乎是由于，至少部分是由于一个失调的免疫反应;和4）肺部感染与A。烟曲霉导致pDC流入肺。我们推测pDC通过介导直接抗真菌活性和调节先天性和适应性免疫应答在宿主防御侵袭性曲霉病中发挥重要作用。为了解决这一假设，我们将定义pDC在防御A.烟曲霉，使用在体外和在 体内模型在目的1中，我们将探索我们观察到的pDC与A.烟曲霉在体外导致真菌识别、抗真菌活性和细胞因子释放。将探索pDC识别分生孢子和菌丝真菌形态型所需的受体。探讨了A.烟曲霉将被阐明。将使用完整pDC和pDC裂解物来表征pDC如何介导抗真菌活性。最后，研究了pDC对A.将对烟曲霉菌进行调查。在目标2中，我们将通过阐明pDC在宿主防御曲霉病中具有非冗余作用的机制来继续我们的证明。将在侵袭性曲霉病的鼠模型中确定pDC消耗对死亡率、真菌负荷、免疫细胞募集、病理学和细胞因子应答的影响。将通过共消耗pDC和特异性白细胞亚群以及用敲除小鼠来检查pDC介导的保护所需的免疫系统的臂。最后，我们将使用流式细胞术和显微镜来确定pDC是否与分生孢子和菌丝在体内相关。在资助期间完成这些研究将导致真菌发病机制，真菌免疫学和pDC生物学的重大概念进展。此外，所获得的知识可能导致预防和治疗侵袭性真菌病的新策略。

DESCRIPTION (provided by applicant): Aspergillus fumigatus is the most common cause of invasive mold infections. Even with advances in therapy and early diagnostics, mortality rates remain high. Plasmacytoid dendritic cells (pDCs) comprise a functionally distinct lineage of DCs that rapidly produce copious amounts of type I interferons (IFNs) upon stimulation with viruses, predominantly via mechanisms dependent on sensing of viral nucleic acids. pDCs link innate to adaptive immunity by secreting cytokines and by priming T cells. The interplay between pDCs and fungi has not been well characterized. The application builds upon compelling preliminary data demonstrating that: 1) human pDCs directly inhibit fungal growth via a mechanism that involves A. fumigatus-induced pDC death; 2) following stimulation with A. fumigatus hyphae, pDCs release cytokines, including type I IFNs; 3) depletion of pDCs renders mice hypersusceptible to pulmonary and intravenous challenge with A. fumigatus by a mechanism that appears to be due, at least in part, to a dysregulated immune response; and 4) pulmonary infection with A. fumigatus results in pDC influx into the lungs. We hypothesize that pDCs play a major role in host defenses against invasive aspergillosis by mediating direct antifungal activity and by modulating the innate and adaptive immune response. To address this hypothesis, we will define the contribution of pDCs in the defense against A. fumigatus using both in vitro and in vivo models. In Aim 1, we will explore the mechanistic basis of our observations that incubation of pDCs with A. fumigatus in vitro results in fungal recognition, antifungal activity and cytokine release. The receptors required for pDC recognition of the conidial and hyphal fungal morphotypes will be explored. The mechanism of pDC death induced by A. fumigatus will be elucidated. How pDCs mediate antifungal activity will be characterized using both intact pDCs and pDC lysates. Finally, the cytokine and chemokine response of pDCs to A. fumigatus will be investigated. In aim 2, we will follow up our demonstration that pDCs have a non- redundant role in host defenses against aspergillosis by illuminating the mechanisms by which this occurs. The effect of pDC depletion on mortality, fungal burden, immune cell recruitment, pathology and cytokine response will be determined in murine models of invasive aspergillosis. The arms of the immune system required for pDC-mediated protection will be examined by co-depleting pDCs and specific leukocyte subsets and with knockout mice. Lastly, we will determine whether pDCs associate with conidia and hyphae in vivo using flow cytometry and microscopy. Completion of these studies over the funding period will result in major conceptual advances in fungal pathogenesis, fungal immunology and pDC biology. Moreover, the knowledge gained may lead to novel strategies to prevent and treat invasive mycoses.