Biological actions of endogenous Kynurenine-derived electrophiles

犬尿氨酸途径主要通过以下作用分解代谢超过95%的所有色氨酸： 肝细胞中的色氨酸2，3-双加氧酶2（TDO 2）和骨髓中的吲哚胺2，3-双加氧酶1（IDO 1） 白细胞树突状细胞（DC）中继发于IDO 1上调的犬尿氨酸合成增加强烈地抑制了IDO 1的表达。 与通过促进抗炎信号传导产生致耐受性表型相关，调节性T细胞 （Treg）极化和免疫耐受，由免疫细胞引起的减弱的炎症反应， 反复暴露于TLR配体。然而，虽然这一途径的病理生理相关性很好- 尽管犬尿氨酸的免疫调节作用已经建立，但犬尿氨酸的免疫调节作用背后的机制仍然不清楚。使用 通过代谢组学方法，我们发现继发于外源性 补充或慢性炎症与新的信号活性的形成有关。 犬尿氨酸衍生的亲电体。这种介质，有效地抑制TLR 4依赖性NF-κB信号在原发性肝癌中的表达。 巨噬细胞和减弱炎症反应的内毒素攻击的小鼠。此外，小说 犬尿氨酸衍生的亲电体以比其犬尿氨酸高50倍的效力参与AhR信号传导 前体，表明在DC和T细胞中的潜在促耐受性作用。专门设计的最先进的 LC-MS/MS分析将能够在其他犬尿氨酸的情况下定量这种新型衍生物。 活化和非活化髓系白细胞中的途径代谢物以及阐明摄取和 出口机制。犬尿氨酸衍生的亲电体在生理pH下是带电荷的氨基酸，因此在生理pH下是带电荷的氨基酸。 将合成细胞可渗透的烷基酯化类似物以进一步确定其信号传导机制， 在不存在活性细胞转运和潜在的限速作用的情况下的治疗潜力 通过存在于细胞外环境中的其它氨基酸的竞争。来源于途径特异性的原代细胞 基因敲除动物和新的生物正交标记策略将被利用来定义机制基础 犬尿氨酸衍生的亲电体的抗炎作用，无论是在特定的调节， 信号通路及其对炎症引起的能量代谢变化的影响。最后，潜力 将建立犬尿氨酸衍生的亲电体促进致耐受性应答的体外T细胞模型。 细胞极化和内毒素抗性和耐受性的体内模型。该研究计划将揭示具体 犬尿氨酸途径的免疫调节作用，并可能导致相关的发展 用于失调的免疫应答如慢性炎症、自身免疫 疾病、癌症和同种异体移植排斥。

The kynurenine pathway catabolizes over 95% of all tryptophan primarily through the actions of tryptophan 2,3-dioxygenase 2 (TDO2) in hepatocytes and indoleamine 2,3-dioxygenese 1 (IDO1) in myeloid leukocytes. Increased kynurenine synthesis in dendritic cells (DC) secondary to IDO1 upregulation is strongly linked with the generation of a tolerogenic phenotype by promoting anti-inflammatory signaling, regulatory T cell (Treg) polarization and immune tolerance, an attenuated inflammatory response instigated by immune cells that are repeatedly exposed to TLR ligands. However, while the pathophysiologic relevance of this pathway is well- established, the mechanism behind the immunomodulatory effects of kynurenine remain poorly defined. Using metabolomic approaches, we found that systemic increases in kynurenine secondary to either exogenous supplementation or chronic inflammation are associated with the formation of a novel signaling-active kynurenine-derived electrophile. This mediator, potently inhibits TLR4-dependent NF-κB signaling in primary macrophages and attenuates inflammatory responses in endotoxin-challenged mice. In addition, the novel kynurenine-derived electrophile engages AhR signaling with 50-fold higher potency than its kynurenine precursor, suggesting a potential pro-tolerogenic role in DC and T-cells. Specifically designed state-of-the-art LC-MS/MS assays will enable the quantification of this novel derivative in the context of other kynurenine pathway metabolites in activated and non-activated myeloid leukocytes as well as the elucidation of uptake and export mechanisms. The kynurenine-derived electrophile is a charged amino acid at physiological pH, thus a cell-permeable alkyl-esterified analogue will be synthesized to further define its signaling mechanisms and therapeutic potential in the absence of the rate-limiting effects of active cellular transport and potential competition by other amino acids present in the extracellular milieu. Primary cells derived from pathway-specific knock-out animals and novel bio-orthogonal labeling strategies will be harnessed to define the mechanistic basis of the anti-inflammatory actions of the kynurenine-derived electrophile both in terms of the modulation of specific signaling pathways and its effects on inflammation-elicited changes in energy metabolism. Finally, the potential of the kynurenine-derived electrophile to promote tolerogenic responses will be established assessing in vitro T cell polarization and in vivo models of endotoxin resistance and tolerance. This Research Plan will reveal specific immunomodulatory actions of the kynurenine pathway and may potentially lead to the development of related pharmacological interventions for dysregulated immune responses such as chronic inflammation, autoimmune diseases, cancer, and allograft rejection.