Regulation of ferroptosis in type-2 immune responses

2型免疫反应可促进炎症(例如在哮喘中)或促进宿主防御和修复(例如在感染蠕虫寄生虫期间)。2型免疫通常与组织损伤有关，例如由蠕虫幼虫或蛋白酶变应原引起。铁下垂是一种程序性氧化性细胞死亡，与组织损伤(如肾脏或脑)有关，但对其在2型免疫环境中的参与和调节知之甚少。2型免疫反应是组织修复的工具，这表明必须严格控制铁下垂，以防止2型免疫环境中的过度损害。目前的项目旨在确定2型免疫(过敏性呼吸道炎症和蠕虫感染)小鼠模型中铁下垂标志物的特征，并确定在这些环境中铁下垂的调节机制。我们将重点关注巨噬细胞和上皮细胞的铁下垂，它们是启动2型免疫反应、参与炎症、免疫调节和组织修复的关键细胞。在我们之前的工作中，我们已经发现了蠕虫蛋白(HPB谷氨酸脱氢酶(GDH)和HPB铁蛋白)，它们可以调节与脂质过氧化有关的脂氧合酶的表达和/或活性。这些蠕虫酶的主要活性是谷氨酸代谢和铁结合(铁蛋白)。作为脂氧合酶产物，谷氨酸和铁促进铁下垂，我们的目的是研究HPB GDH和HPB铁蛋白是否以及如何抑制人和小鼠巨噬细胞以及人呼吸道上皮细胞的铁下垂。除了研究蠕虫蛋白对铁下垂的调节外，我们还发现了在2型免疫反应中可能调节铁下垂的宿主因素：转谷氨酰胺酶-2(TG2)可能是铁下垂的正调控因子，载脂蛋白E(ApoE)可能预防巨噬细胞和上皮细胞的铁下垂。为了研究TG2的作用，我们将利用免疫细胞中缺乏TG2的小鼠的巨噬细胞，或者使用药物抑制剂CRISPR/Cas9或siRNA来靶向人类细胞中的TG2。铁下垂标志物将在条件性TG2缺陷小鼠中进行评估，以研究免疫细胞来源的TG2在肠道蠕虫感染或过敏性呼吸道炎症期间铁下垂中的参与。我们以前的工作表明，ApoE在鼻息肉和哮喘患者的鼻黏膜上皮和巨噬细胞中下调。因此，我们的目标是研究患者细胞中低水平的载脂蛋白E是否导致铁眼性细胞死亡的易感性增加，并确定载脂蛋白E保护细胞免受脂质过氧化和铁下垂的机制。该项目将提供对2型免疫中铁下垂调节的见解，与2型驱动的病理可能相关，并询问蠕虫蛋白作为治疗铁下垂的方案，在炎症性和退行性疾病中具有潜在的治疗应用。

Type-2 immune responses can drive inflammation (e.g. in asthma) or promote host defense and repair (e.g. during infection with worm parasites (helminths)). Type-2 immunity is typically associated with tissue damage, caused e.g. by helminth larvae or protease allergens. Ferroptosis, a form of programmed oxidative cell death, is involved in tissue injury (e.g. in the kidney or brain), but its involvement and regulation in type-2 immune contexts are poorly understood. Type-2 immune responses are instrumental for tissue repair, suggesting that ferroptosis has to be tightly regulated in order to prevent excessive damage in type-2 immune settings. The current project aims at characterizing ferroptosis markers in mouse models of type-2 immunity (allergic airway inflammation and helminth infection) and to define mechanisms of ferroptosis regulation in these settings. We will focus on ferroptosis in macrophages and epithelial cells as key cells involved in the initiation of type-2 immune responses and in inflammation, immune regulation and tissue repair. In our previous work, we have identified helminth proteins (Hpb glutamate dehydrogenase (GDH) and Hpb Ferritin), which can regulate the expression and/ or activity of lipoxygenases implicated in lipid peroxidation. The main activities of these helminth enzymes are glutamate metabolism (GDH) and iron binding (Ferritin). As lipoxygenase products, glutamate and iron promote ferroptosis, we aim to study whether and how Hpb GDH and Hpb Ferritin can suppress ferroptosis in human and murine macrophages as well as in human airway epithelial cells. In addition to studying ferroptosis regulation by helminth proteins, we have identified host factors that may regulate ferroptosis in type-2 immune responses: While the enzyme transglutaminase-2 (TG2) may act as a positive regulator of ferroptosis, apolipoprotein E (ApoE) may prevent macrophage and epithelial cell ferroptosis. To study the role of TG2, we will make use of macrophages from mice lacking TG2 in immune cells or of pharmacological inhibitors, CRISPR/Cas9 or siRNA to target TG2 in human cells. Ferroptosis markers will be assessed in mice with a conditional TG2 deficiency, to study the involvement of immune cell-derived TG2 in ferroptosis during intestinal helminth infection or allergic airway inflammation. Our previous work has shown that ApoE is downregulated in the nasal epithelium and in macrophages of patients suffering from nasal polyps and asthma. Thus, we aim to study whether low ApoE levels in patient cells result in increased susceptibility to ferroptotic cell death and to define the mechanisms by which ApoE may protect cells against lipid peroxidation and ferroptosis. The project will provide insights into ferroptosis regulation in type-2 immunity with potential relevance for type-2 driven pathologies and interrogate helminth proteins as regimens against ferroptosis with potential therapeutic application in inflammatory and degenerative diseases.