Gene expression profile of Macrophages Following Helminth Enzyme Exposure Targeting Prostaglandin Synthesis

The molecular mechanisms by which worm parasites evade host immunity are incompletely understood. In a mouse model of chronic intestinal helminth infection, we identify helminthic glutamate dehydrogenase (heGDH) as an essential factor for parasite chronicity by using antibody mediated neutralization or treatment with exogenous recombinant heGDH. Macrophages efficiently internalize heGDH and represent a major target of the enzyme in vivo. Combining RNA-seq, ChIP-seq, targeted lipidomics and inhibitor studies, we identify prostaglandin E2 (PGE2) as a major immune regulatory mechanism of heGDH. The induction of PGE2 and further immune regulatory factors (IL-12 family cytokines, IDO1) by heGDH depended on the p300-mediated acetylation of histones. While the enzyme's catalytic activity was dispensable for key immune regulatory functions, an N-terminal handle-like structure distinct from mammalian GDHs may confer interaction of heGDH with its targets (CD64, GPNMB), identified via proteomics. Thus, helminths employ a ubiquitous metabolic enzyme to epigenetically target macrophages and establish chronicity. Overall design: RNA-Seq of human monocyte derived macrophages treated with helminthic glutamate dehydrogenase (heGDH) or LPS

蠕虫寄生虫逃避宿主免疫的分子机制目前尚未完全阐明。本研究在慢性肠道蠕虫感染小鼠模型中，通过抗体介导的中和实验以及外源性重组蠕虫谷氨酸脱氢酶（helminthic glutamate dehydrogenase, heGDH）处理，证实heGDH是寄生虫维持慢性感染的关键因子。巨噬细胞可高效摄取heGDH，是该酶在体内的主要作用靶点。通过整合RNA测序（RNA-seq）、染色质免疫沉淀测序（ChIP-seq）、靶向脂质组学以及抑制剂实验，我们证实前列腺素E2（prostaglandin E2, PGE2）是heGDH发挥免疫调控作用的核心机制。heGDH诱导PGE2及其他免疫调控因子（白细胞介素12家族细胞因子、吲哚胺2,3-双加氧酶1, IDO1）的表达，这一过程依赖于p300介导的组蛋白乙酰化修饰。尽管该酶的催化活性对其核心免疫调控功能并非必需，但相较于哺乳动物谷氨酸脱氢酶（GDHs），heGDH特有的N端柄状结构可介导其与靶点（分化簇64, CD64、跨膜糖蛋白非转移性黑色素瘤蛋白B, GPNMB）的结合，上述靶点通过蛋白质组学筛选得到。综上，蠕虫可通过一种广泛存在的代谢酶，以表观遗传调控方式靶向巨噬细胞，从而建立慢性感染。实验整体设计：对经heGDH或脂多糖（lipopolysaccharide, LPS）处理的人单核细胞源性巨噬细胞进行RNA测序（RNA-seq）。