Metabolic regulation of inflammatory processes: HIF-1alpha and IDO as anti-infectious effector molecules in professional phagocytes

组织炎症是微生物感染的标志，其特征在于由于增强的细胞浸润和血管阻塞导致的局部氧水平降低。转录因子缺氧诱导因子（HIF）-1α介导基因表达的基本变化，如糖酵解途径的代谢开关或诱导血管生成，以允许细胞适应减少的氧气供应。此外，HIF-1α具有直接的抗微生物功能，导致防御素、蛋白酶和一氧化氮（NO）的产生。除了稳定HIF-1α蛋白外，缺氧还增强了具有抗微生物和免疫抑制效应器功能的色氨酸降解血红素酶吲哚胺2，3-双加氧酶-1（IDO）的酶活性。本研究旨在探讨HIF-1 α和IDO在树突状细胞（DC）和巨噬细胞介导的炎症过程中的作用及其相互关系。为此，我们使用CD 11 cCre或CCL 17 Cre小鼠产生了两种突变小鼠系，能够有效地对DC中的HIF-1α进行细胞类型特异性消融。我们已经证明，在低氧培养条件下，DC成熟增强，而IL-12 p70的产生以HIF-1α非依赖性方式受损。与此相反，在DC中发现缺氧诱导的CD 73和趋化因子受体CXCR 4和CCR 7的上调是HIF-1α依赖的。这些改变对体外和体内DC的趋化因子依赖性迁移的影响将受到未来的研究。我们还产生了ES细胞系，其允许使用Cre/loxP重组系统进行IDO的细胞类型特异性过表达。在该突变的种系传递后，我们将能够在CCL 17 + DC或巨噬细胞中组成型诱导IDO。HIF-1α缺陷型、IDO缺陷型（项目4）或IDO过表达小鼠将在不同感染模型中进行攻毒，采用单核细胞增生李斯特菌、金黄色葡萄球菌、肺炎衣原体和MCMV进行全身或局部感染。通过这种方式，我们希望确定HIF-1α和IDO对微生物防御和免疫调节的贡献。

Tissue inflammation is a hallmark of microbial infections and is characterized by a local reduction in oxygen levels due to enhanced cellular infiltration and vascular obstruction. The transcription factor Hypoxia-inducible factor (HIF)-1α mediates essential changes in gene expression, like the metabolic switch to the glycolytic pathway or induction of angiogenesis, to permit cellular adaptation to reduced oxygen supply. In addition, HIF-1α has direct anti-microbial functions, leading to the production of defensins, proteases and nitric oxide (NO). Besides stabilization of the HIF-1α protein, hypoxia also enhances the enzymatic activity of the tryptophan-degrading heme enzyme indoleamine 2,3-dioxygenase-1 (IDO), which has both anti-microbial and immunosuppressive effector functions. In contrast, HIF-1α may inhibit IDO activity through induction of NO. In this project, we want to study the functional importance and interplay of HIF-1α and IDO during inflammatory processes mediated by dendritic cells (DC) and macrophages. To this end, we have generated two mutant mouse lines with efficient cell-type specific ablation of HIF-1α in DC, using either CD11cCre or CCL17Cre mice. We have shown that DC maturation is enhanced under hypoxic culture conditions, whereas IL-12p70 production is impaired in a HIF-1α-independent manner. In contrast, hypoxia-induced upregulation of CD73 and chemokine receptors CXCR4 and CCR7 were found to be HIF-1α-dependent in DC. The effect of these alterations on chemokine-dependent migration of DC in vitro and in vivo will be subject to future investigation. We also generated ES cell lines, which allow for cell-type specific overexpression of IDO, using the Cre/loxP recombination system. Upon germline transmission of this mutation, we will be able to constitutively induce IDO in either CCL17+ DC or macrophages. HIF-1α-deficient-, IDO-deficient- (Project 4), or IDO-overexpressing mice will be challenged in different infection models, using systemic or local infection with Listeria monocytogenes, Staphylococcus aureus, Chlamydia pneumoniae and MCMV. In this way, we want to determine the contribution of HIF-1α and IDO to microbial defense and immune regulation.