Role and mechanism of action of glutamate dehydrogenase in helminth-driven regulation of eicosanoids and type 2 immunity

全世界有超过5亿人患有过敏性哮喘或鼻息肉等慢性炎症性气道疾病。不幸的是，这些患者中有很大一部分患有治疗抵抗性疾病。在这种情况下，蠕虫寄生虫可以产生抑制过敏性炎症的分子是很有趣的。在拟议的项目中，我们的目标是机械地表征蠕虫寄生虫的免疫调节作用和分子，最终目的是利用这种治疗气道炎症的潜力。到目前为止，我们可以证明肠道寄生虫多回Heligmosomoides polygyrus bakeri（“HpbE”）的幼虫提取物诱导巨噬细胞表型，能够抑制过敏性炎症。特别是，我们可以证明HpbE改变巨噬细胞的脂质介质代谢，从而诱导一个由调节/抗炎介质如前列腺素E2 （PGE2）主导的谱。此外，缺乏环氧化酶2 （COX2）的巨噬细胞不再能够抑制过敏性免疫反应。此外，我们可以确定负责HpbE免疫调节作用的第一个分子和机制。在继续的提案中，我们现在的目标是验证我们的主要候选蛋白（Hpb谷氨酸脱氢酶，GDH）的免疫调节作用并阐明其作用机制。在提交时，我们正在优化Hpb GDH的表达和纯化，以保证其高质量和高数量的重组生产。我们还提出了一种抗hpbgdh的单克隆抗体。有了这些工具，我们的目标是研究来自寄生虫的GDH是否以及如何被洗刷到宿主免疫细胞，以及这是否导致脂质介质和谷氨酰胺代谢的转变。Hpb GDH的功效及其作用机制将在过敏和蠕虫（Hpb）感染的小鼠模型以及人类巨噬细胞中进行评估。通过转录（RNAseq）分析，我们首次获得了表观遗传机制（组蛋白修饰）在总提取物（HpbE）免疫调节作用中的作用。通过进行表观遗传分析（ChIPseq）和阻断潜在的机制靶点（如hdac），我们现在的目标是研究组蛋白修饰如何通过HpbE和Hpb GDH调节巨噬细胞的脂质介质代谢和效应功能。总之，我们的工作将有助于更好地理解过敏性炎症背景下先天免疫反应的调节，并可能促进转化为新的治疗方法。

More than 500 million people worldwide are affected by chronic inflammatory airway diseases such as allergic asthma or nasal polyps. Unfortunately, a significant part of these patients suffers from therapy resistant disease. In this context, it is intriguing that worm parasites can produce molecules, which suppress allergic inflammation. In the proposed project, we aim to mechanistically characterize immuneregulatory effects and molecules from a worm parasite with the ultimate aim to harness this potential for the therapy of airway inflammation. So far, we could show that a larval extract of the intestinal parasite Heligmosomoides polygyrus bakeri (“HpbE”) induces a macrophage phenotype that is able to suppress allergic inflammation. In particular, we could show that HpbE modifies the lipid mediator metabolism of macrophages to induce a profile, which is dominated by regulatory/ anti-inflammatory mediators such as prostaglandin E2 (PGE2). Moreover, macrophages, which lack the enzyme cyclooxygenase 2 (COX2), were no longer able to suppress allergic immune responses. Furthermore, we could identify first molecules and mechanisms that are responsible for the immuneregulatory actions of HpbE. In the continuation proposal, we now aim to validate the immuneregulatory effects of our major candidate protein (Hpb glutamate dehydrogenase, GDH) and to elucidate its mechanism of action. At the time of submission, we are optimizing the expression and purification of Hpb GDH to allow for its recombinant production in good quality and quantity. We have also raised a monoclonal antibody against Hpb GDH. With these tools in hand, we aim to study if and how GDH from the parasite is shuffled to host immune cells and if this results in a shift in the lipid mediator- and glutamine- metabolism. The efficacy of Hpb GDH and its mechanism(s) of action will then be assessed in mouse models of allergy and helminth (Hpb) infection as well as in human macrophages.Through transcriptional (RNAseq) profiling, we have obtained first hints to a role for epigenetic mechanisms (histone modifications) in the immuneregulatory effects of the total extract (HpbE). By performing epigenetic analyses (ChIPseq) and by blocking potential mechanistic targets (e.g. HDACs), we now aim to investigate how histone modifications may contribute to the modulation of the lipid mediator metabolism and effector functions of macrophages by HpbE and Hpb GDH. In summary, our work will contribute to a better understanding of the regulation of innate immune responses in the context of allergic inflammation and may foster the translation into novel therapies.