Regulation of ferroptosis in type-2 immune responses

2型免疫反应可引起炎症（例如在哮喘中）或促进宿主防御和修复（例如在寄生虫（蠕虫）感染期间）。2型免疫通常与组织损伤有关，如由蠕虫幼虫或蛋白酶过敏原引起。铁凋亡是程序性氧化细胞死亡的一种形式，与组织损伤（如肾或脑）有关，但其在2型免疫环境中的参与和调节尚不清楚。2型免疫反应有助于组织修复，这表明铁下垂必须受到严格调节，以防止2型免疫环境中的过度损伤。目前的项目旨在表征2型免疫小鼠模型（过敏性气道炎症和蠕虫感染）中的铁下垂标志物，并确定这些环境中铁下垂调节的机制。我们将重点关注巨噬细胞和上皮细胞中的铁凋亡，它们是参与2型免疫反应启动、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，我们已经确定了蠕虫蛋白（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（GDH）和铁结合（铁蛋白）。作为脂氧合酶的产物，谷氨酸和铁促进铁凋亡，我们旨在研究Hpb GDH和Hpb铁蛋白是否以及如何抑制人、鼠巨噬细胞和人气道上皮细胞的铁凋亡。除了研究蠕虫蛋白对铁下垂的调节外，我们还发现了在2型免疫应答中可能调节铁下垂的宿主因子：转谷氨酰胺酶-2 （TG2）可能是铁下垂的正调节因子，载脂蛋白E （ApoE）可能阻止巨噬细胞和上皮细胞铁下垂。为了研究TG2的作用，我们将利用免疫细胞中缺乏TG2的小鼠巨噬细胞或药理抑制剂、CRISPR/Cas9或siRNA靶向人细胞中的TG2。将在条件TG2缺乏的小鼠中评估铁下垂标志物，以研究免疫细胞来源的TG2在肠蠕虫感染或过敏性气道炎症期间参与铁下垂。我们之前的工作表明，ApoE在鼻息肉和哮喘患者的鼻上皮和巨噬细胞中下调。因此，我们的目的是研究患者细胞中低ApoE水平是否导致对铁沉细胞死亡的易感性增加，并确定ApoE可能保护细胞免受脂质过氧化和铁沉的机制。该项目将深入了解铁下垂在2型免疫中的调节，与2型驱动的病理有潜在的相关性，并研究寄生虫蛋白作为抗铁下垂的方案，在炎症和退行性疾病中有潜在的治疗应用。

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.