A critical role for macrophage ferroptosis in promoting fungal invasion in lung transplant recipients

项目总结/摘要 本申请的重点是移植物损伤诱导的铁超载在调节异常中的作用。 肺巨噬细胞（巨噬细胞）和促进侵袭性曲霉病。烟曲霉（Af）是一种 无处不在的霉菌，释放空气中的孢子（分生孢子），影响全球近2000万人。一合 三名肺移植受者（LTR）患有与肺吸虫相关的肺病。而肺 移植可以挽救成千上万人的生命，移植后的生存往往受到限制， Af感染。为了更好地了解移植（宿主）-Af（病原体）关系，我们开发了一种小鼠 Af感染的原位气管移植（OTT）模型。我们已经证明，移植排斥介导的 微出血增加组织铁水平并决定Af侵袭。然而， 免疫、铁超载和感染之间的关系仍然知之甚少。M型糖尿病是抵抗 AF和也是恢复组织铁稳态的核心。重要的是，我们的初步结果表明， 微囊介导的铁超负荷：（i）深刻地影响mfs杀死Af分生孢子的能力，通过微囊介导的铁超负荷。 溶酶体酸化缺陷;（ii）先天性免疫反应向促炎性细胞分化 导致高水平的组织损伤性活性氧（ROS）;和（iii）铁促进心肌梗死 铁性下垂铁凋亡是一种新认识到的调节性细胞死亡的形式，由铁的产生引起 毒性脂质ROS。亚铁下垂症最初是在癌症中被发现的，但现在已知它会导致阿尔茨海默氏症， 帕金森病，缺血再灌注损伤，动脉粥样硬化，急性肾损伤及急性肾损伤后的反应 出血然而，如果存在病原体，铁凋亡在降低宿主对病原体的防御中的作用仍然存在 未知拟议的研究旨在解决这些问题的Af入侵。中央 假设移植微血管介导的铁过载诱导MF铁凋亡和极化 转化为不受限制的促炎表型，促进Af侵袭。具体目标1利用体外和 在体内实验中，研究了铁凋亡是由M极化状态决定的概念， 导致移植瘤不能减轻Af感染，并研究了降铁剂的作用 和抗铁蛋白药物以减少真菌侵袭。特定目标2使用最先进的组学技术来定义 铁诱导的Af蛋白酶，并测试了真菌蛋白酶抑制可以减轻铁凋亡的概念， 改善气管移植模型的结果。具体目标3研究肺泡上皮细胞分离的能力 与非肺移植物相比，来自人LTR的Af分生孢子被杀死，并且与细菌杀死Af分生孢子的能力相关 分生孢子具有M-偏振态和铁凋亡。这一目标将提供一个直接 铁过载诱导铁凋亡和促炎表型的假设的可翻译性， 促进真菌入侵。成功完成这些研究将有助于发现一个基本的 新的生物学，并为真菌感染的治疗提供新的靶点。

PROJECT SUMMARY/ ABSTRACT This application focuses on the contribution of transplant hemorrhage-induced iron overload in the dysregulation of pulmonary macrophages (mɸs) and the promotion of invasive aspergillosis. Aspergillus fumigatus (Af) is a ubiquitous mold that releases airborne spores (conidia) and affects nearly 20 million people worldwide. One-in- three lung transplant recipients (LTRs) suffers from Aspergillus-related pulmonary disease. While lung transplantation can be a life-saving treatment for thousands of people, survival post-transplant is often limited by Af infection. To better understand the transplant (host)-Af (pathogen) relationship, we developed a murine orthotopic tracheal transplant (OTT) model of Af infection. We have shown that transplant rejection-mediated microhemorrhage increases tissue iron levels and determines Af invasion. However, the exact interaction between immunity, iron overload and infection are still poorly understood. Mɸs are the first line of defense against Af and are also central to restoring tissue iron homeostasis. Importantly, our preliminary results indicate that microhemorrhage-mediated iron overload: (i) profoundly impacts the ability of mfs to kill Af conidia through a defect in lysosomal acidification; (ii) the innate immune response is polarized toward a pro-inflammatory mɸs state that results in high levels of tissue damaging reactive oxygen species (ROS); and (iii) iron promotes mɸ ferroptosis. Ferroptosis is a newly recognized form of regulated cell death that results from the production of iron toxic lipid ROS. Ferroptosis was first recognized in cancer but is now known to contribute to Alzheimer’s and Parkinson’s disease, ischemia reperfusion injury, atherosclerosis, acute kidney injury and the response to acute hemorrhage. However, the role of ferroptosis in lowering the host’s defense against pathogens, if any, remains unknown. The proposed studies are designed to address these questions in terms of Af invasion. The central hypothesis is that transplant microhemorrhage-mediated iron overload induces mf ferroptosis and polarization into an unrestrained pro-inflammatory phenotype that promotes Af invasion. Specific aim 1 utilizes in vitro and in vivo experiments to investigate the concept that ferroptosis is dictated by mɸs polarization state and contributes to the inability of transplant mɸs to mitigate Af infection and studies the role of iron lowering agents and anti-ferroptotic drugs to decrease fungal invasion. Specific aim 2 uses state-of-art omics techniques to define iron induced Af proteases and tests the concept that fungal protease inhibition can mitigate ferroptosis and improve outcomes in the tracheal transplant model. Specific aim 3 studies the ability of alveolar mɸs isolated from human LTRs compared to non-lung transplants to kill Af conidia and correlates the ability of mɸs to kill conidia with mɸs-polarization state and ferroptosis, using mass cytometry. This aim will provide a direct translatability of the hypothesis that iron overload induces ferroptosis and a pro-inflammatory phenotype that promotes fungal invasion. Successful completion of these studies will allow for the discovery of a fundamental new biology and provide novel targets for the treatment of fungal infections.