Interactions of pDCs with Aspergilus

描述（由申请人提供）：烟曲霉是侵入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进展，死亡率仍然很高。浆细胞样树突状细胞（pDCs）包括一个功能独特的树突状细胞谱系，它们在病毒刺激下迅速产生大量的I型干扰素（ifn），主要通过依赖于病毒核酸感知的机制。pDCs通过分泌细胞因子和启动T细胞将先天免疫与适应性免疫联系起来。pDCs与真菌之间的相互作用尚未得到很好的表征。该应用程序建立在令人信服的初步数据基础上，这些数据表明：1)人类pDC通过一种涉及烟曲霉诱导pDC死亡的机制直接抑制真菌生长；2)烟曲霉菌丝刺激后，pDCs释放包括I型ifn在内的细胞因子；3) pDCs的消耗使小鼠对烟曲霉肺和静脉攻击易感，其机制似乎是由于，至少部分是由于免疫反应失调；4)肺部感染烟曲霉导致pDC流入肺部。我们假设pDCs通过介导直接抗真菌活性和调节先天和适应性免疫反应，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pDCs在体外和体内对烟曲霉的防御中的贡献

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.