Regulation of antifungal immunity by monocyte-derived dendritic cells

 描述(由申请人提供)：越来越清楚的是，真菌病原体对人类健康构成重大负担，但目前可用的化疗方法在防止侵袭性真菌生长导致的死亡方面往往无效。有人提出，抗真菌药物和基于免疫的干预措施的结合可能是显著改善目前与侵袭性真菌感染相关的可怕结果的关键。在……里面 为了实现基于免疫的治疗干预的承诺，需要更好地了解宿主对真菌的相关保护机制。烟曲霉是一种霉菌病原体，也是侵袭性曲霉病(IA)的最常见原因，IA是一种严重的感染，发生在免疫功能受损的患者中。虽然多种免疫细胞可以帮助提供对IA的保护，但管理免疫细胞合作最终根除分生孢子和预防IA的机制尚不清楚。利用选择性细胞耗竭策略，我们最近的研究表明，除了中性粒细胞外，CCR2炎性单核细胞(CCR2 Mo)及其衍生的单核细胞来源的树突状细胞(Mo-DC)也是预防IA所必需的。我们的研究表明，CCR2、Mo和Mo-DC对于：1)直接根除真菌孢子；2)建立保护性炎症肺环境；3)充分激活中性粒细胞抗真菌活性是必不可少的。在初步研究中，我们发现在中性粒细胞耗竭的动物中，IA的发展与这些细胞中Mo-DC分化减少和杀分生孢子活性降低有关。这项研究的中心假设是中性粒细胞和CCR2Mo功能是相互依赖的，不断地交叉调节彼此的抗真菌活性。因此，我们的目标是询问CCR2、Mo和中性粒细胞的交叉调节机制，并表征它们在抗真菌免疫中的总体贡献。我们的第一个目标是确定CCR2钼衍生细胞如何调节中性粒细胞抗真菌效应功能。为了确定中性粒细胞杀分生孢子活性的相关上游调节因子，我们对中性粒细胞在CCR2、Mo和Mo-DC存在或不存在的情况下对肺部Af感染做出反应的中性粒细胞进行了无偏转录组分析。我们的分析表明，Af感染在抗真菌中性粒细胞中诱导了强烈的I型干扰素特征，而去除CCR2 Mo会削弱这一反应。在目标1中，我们将确定CCR2、Mo和Mo-DC如何控制干扰素的产生，髓系细胞固有的干扰素信号在激活分生孢子效应功能中的作用，并确定干扰素诱导的GTP酶是否是中性粒细胞分生孢子诱导功能的必要效应者。在目标2中，我们将确定中性粒细胞如何控制Mo-DC分化及其抗真菌效应功能。我们将阐明特定的中性粒细胞衍生因子在 钼树突状细胞的分化和中性粒细胞固有的固有受体缺陷在获得中性粒细胞调节途径中的作用。综上所述，这些研究将为调节天然细胞合作的机制提供新的和重要的见解，这些机制对于抗真菌免疫的发展至关重要。

 DESCRIPTION (provided by applicant): It is becoming increasingly clear that fungal pathogens pose a significant burden to human health yet currently available chemotherapies are often ineffective in preventing mortality from invasive fungal growth. It has been proposed that the combination of antifungal medications and immune-based interventions may be the key to significantly improve the dire outcomes currently associated with invasive fungal infections. In order to fulfill the promise of immune-based therapeutic interventions, a better understanding of relevant mechanisms of host protection against fungi is needed. Aspergillus fumigatus is a mold fungal pathogen and the most common cause of invasive aspergillosis (IA), a serious infection that develops in patients with compromised immune function. Although a variety of immune cells can help confer protection against IA, the mechanisms that govern immune cell cooperation culminating in the eradication of conidia and IA prevention are unclear. Using selective cell depletion strategies our recent studies have shown that, in addition to neutrophils, CCR2+ inflammatory monocytes (CCR2+Mo) and their derivative monocyte-derived dendritic cells (Mo-DCs) are required for the prevention of IA. Our studies indicate that CCR2+Mo and Mo-DCs are essential for: 1) direct fungal spore eradication; 2) establishment of a protective inflammatory lung milieu; 3) the full activation of neutrophil antifungal activities. In preliminary studies we lso find that IA development in neutrophil-depleted animals is associated with diminished Mo-DC differentiation and lower conidiacidal activity in these cells. The central hypothesis of the studis proposed in this application is that neutrophil and CCR2+Mo functions are interdependent, continuously cross-regulating each other's antifungal activities. Our goal is thus to interrogate the mechanisms of CCR2+Mo and neutrophil cross-regulation and characterize their overall contributions to anti-fungal immunity. Our first aim is to determine how CCR2+Mo derived cells regulate neutrophil anti-fungal effector functions. In order to identify relevant upstream regulators of neutrophil conidiacidal activity we thus performed an unbiased transcriptome analysis of neutrophils that responded to a pulmonary Af infection in the presence or absence of CCR2+Mo and Mo-DCs. Our analysis revealed that Af infection induces a strong type I IFN signature profile in antifungal neutrophils and that removal of CCR2+Mo impairs this response. In aim 1 we will thus define how CCR2+Mo and Mo-DCs control IFN production, the role of myeloid cell intrinsic IFN signaling in the activation of conidiacidal effector functions and determine whether IFN-inducible GTPases are essential effectors of neutrophil conidiacidal function. In aim 2 we will determine how neutrophils control Mo-DC differentiation and their antifungal effector functions. We will elucidate the role of specific neutrophil-derived factors in the differentiation of Mo-DCs and the role of neutrophil-intrinsic innate receptor deficiencies in the acquisition of neutrophil regulatory pathways. Taken together, these studies will provide novel and significant insights into the mechanisms that mediate innate cell cooperation essential for the development of antifungal immunity.