Pulmonary defense against aspergillus fumigatus

描述(申请人提供)：由霉菌烟曲霉菌引起的侵袭性肺曲霉菌病已经成为最严重的侵袭性真菌感染之一，不仅在不断扩大的免疫抑制患者群体中，而且在被认为不是经典免疫损害的个人中也是如此。针对烟曲霉菌的先天免疫涉及肺泡巨噬细胞的最初一波炎症反应，随后是中性粒细胞的寻找和摧毁任务。我们之前已经证明，β-葡聚糖受体Dectin-1在体外介导了肺泡巨噬细胞(AM)对烟曲霉的炎症反应(Steele等人。PLOS病理1：E42,2005年12月)，自从上一次对这一建议的审查(2009年2月)以来，我们现在已经报告了Dectin-1基因缺陷的小鼠显示出对烟曲霉菌肺部感染的固有易感性(Werner等人)。J免疫182：4938-4946,2009年4月)。最近一个有趣的发现是，观察到“天生的IL-17”是对烟曲霉产生抵抗力的中心成分：(1)Dectin-1 KO小鼠在烟曲霉攻击后不久就出现肺IL-17产生缺陷，(2)注射IL-17中和抗体的WT小鼠对烟曲霉感染变得易感。我们现在通过细胞内细胞因子染色显示，在烟曲霉菌攻击后，肺内IL-17的主要细胞来源出奇地不是淋巴来源，而是髓系CD11b+和CD11c+细胞群，它们以Dectin-1依赖的方式产生IL-17。在其他数据中，我们发现，在暴露于烟曲霉菌的Dectin-1 KO小鼠的肺中，诱导Th17细胞所必需的IL-6和TGF-β在较低水平上没有产生，这表明其他机制/介质对Dectin-1依赖的IL-17的产生起作用。反过来，新的数据表明，在烟曲霉菌攻击后，Dectin-1 KO小鼠Th17/IL-17诱导细胞因子IL-21和Th17/IL-17维持细胞因子IL-23的产生减少，趋化因子CXCL12/SDF-1和CCL2/MCP-1也是如此。这些结果表明，Dectin-1可能通过产生IL-17相关的诱导细胞因子或产生IL-17产生的细胞向肺部募集所必需的趋化因子来控制暴露于烟曲霉菌后肺中的IL-17水平。最后，Th17/IL-17相关细胞因子IL-22被发现高度依赖于Dectin-1在肺部的表达。因此，我们假设IL-17介导的对烟曲霉菌的最佳防御依赖于β-葡聚糖受体Dectin-1。为了验证我们的假设：(1)确定烟曲霉菌暴露后肺组织中依赖Dectin-1的IL-17的细胞来源；(2)确定烟曲霉菌暴露后依赖Dectin-1的细胞特异性产生IL-17的机制(S)；(3)确定与IL-17诱导(IL-21/IL-23)、募集(SDF-1/MCP-1)和信号(IL-22)途径相关的介质是否调节宿主对烟曲霉菌的防御。 公共卫生相关性：我们的数据表明，Dectin-1β-葡聚糖受体对侵袭性肺曲霉菌病的病原体烟曲霉的免疫至关重要，因为它控制着一条可能最终需要清除肺部烟曲霉菌的“天生IL-17”途径。这项建议的研究将进一步表征天然IL-17的细胞来源，依赖Dectin-1的细胞群体的产生机制，以及IL-17家族成员是否可以调节宿主对烟曲霉菌的防御。

DESCRIPTION (provided by applicant): Invasive pulmonary aspergillosis caused by the mold Aspergillus fumigatus has emerged as one of the most severe invasive fungal infections, not only in an expanding population of immunosuppressed patients, but also in individuals who are not considered classically immunocompromised. Innate immunity against A. fumigatus involves an initial wave of inflammatory reaction by alveolar macrophages followed by the seek-and- destroy mission of neutrophils. We have previously shown that the beta-glucan receptor Dectin-1 mediates alveolar macrophage (AM) inflammatory responses to A. fumigatus in vitro (Steele et al. PLoS Pathog 1:e42 Dec. 2005) and since the last review of this proposal (February 2009), we have now reported that mice deficient in Dectin-1 display an inherent susceptibility to A. fumigatus lung infection (Werner et al. J Immunol 182: 4938-4946, April 2009). A recent, intriguing finding was the observation that "innate IL-17" was a central component of resistance to A. fumigatus: (1) Dectin-1 KO mice had a defect in lung IL-17 production shortly after A. fumigatus challenge and (2) WT mice administered IL-17 neutralizing antibodies became susceptible to A. fumigatus infection. We now show by intracellular cytokine staining that the predominant cellular sources of IL-17 in the lungs after A. fumigatus challenge are surprisingly not lymphoid in origin, but rather myeloid CD11b+ and CD11c+ cell populations, which produce IL-17 in a Dectin-1 dependent manner. In other data, we show that IL-6 and TGF-¿, which are essential for the induction of Th17 cells, are not produced at lower levels in the lungs of Dectin-1 KO mice exposed to A. fumigatus, suggesting that other mechanisms/mediators are responsible for Dectin-1 dependent IL-17 production. In turn, new data indicate that production of the Th17/IL- 17 induction cytokine IL-21 and the Th17/IL-17 maintenance cytokine IL-23 are attenuated in Dectin-1 KO mice after A. fumigatus challenge, as are the chemokines CXCL12/SDF-1 and CCL2/MCP-1. These results suggest that Dectin-1 may control IL-17 levels in the lungs after A. fumigatus exposure via production of IL-17- associated induction cytokines or production of chemokines essential for the recruitment of IL-17-producing cells to the lungs. Finally, the Th17/IL-17 associated cytokine IL-22 was found to be highly dependent in Dectin-1 for its expression in the lungs. Therefore, we hypothesize that optimal IL-17-mediated defense against A. fumigatus is dependent on the beta glucan receptor Dectin-1. The following Specific Aims will test our hypothesis: (1) To identify the Dectin-1 dependent cellular source of IL-17 in the lungs after A. fumigatus exposure, (2) To identify the mechanism(s) responsible for Dectin-1 dependent, cell-specific production of IL-17 after A. fumigatus lung exposure and (3) To determine whether mediators associated with IL-17 induction (IL-21/IL-23), recruitment (SDF-1/MCP-1) and signaling (IL-22) pathways modulate lung host defense against A. fumigatus. PUBLIC HEALTH RELEVANCE: Our data indicate that the Dectin-1 beta-glucan receptor is essential for immunity against Aspergillus fumigatus, the etiological agent of invasive pulmonary aspergillosis, by controlling an "innate IL-17" pathway that may be ultimately required for clearance of A. fumigatus from the lungs. Studies in this proposal will further characterize the cellular source of innate IL-17, the Dectin-1 dependent mechanisms for the generation of this cell population and whether IL-17 family members can modulate host defense against A. fumigatus.