Biological actions of endogenous Kynurenine-derived electrophiles

犬尿氨酸途径主要通过以下作用分解超过95%的色氨酸： 肝细胞中的色氨酸2，3-双加氧酶2(TDO2)和髓系细胞中的吲哚胺2，3-双加氧酶1(IDO1) 白细胞。IDO1上调继发于树突状细胞(DC)的犬尿氨酸合成增加 通过促进抗炎信号、调节性T细胞与耐受性表型的产生有关 (Treg)极化和免疫耐受，一种由免疫细胞激发的减弱的炎症反应 反复暴露于TLR配体。然而，尽管这一途径的病理生理学相关性很好- 尽管已经确定，犬尿氨酸免疫调节作用背后的机制仍不清楚。vbl.使用 代谢组学方法，我们发现全身犬尿氨酸的增加继发于外源性 补充剂或慢性炎症与一种新的信号活性的形成有关 犬尿氨酸衍生电泳体。这种介体，有效地抑制依赖于TLR4的原发灶中的NF-κB信号。 并减轻内毒素攻击小鼠的炎症反应。此外，这部小说 犬尿氨酸衍生的电泳体参与AhR信号转导，其效力是犬尿氨酸的50倍 前体，提示在DC和T细胞中具有潜在的促耐受作用。特别设计的最先进的 LC-MS/MS分析将使这种新的衍生物能够在其他犬尿氨酸的背景下进行定量 活化和非活化髓系白细胞的途径代谢物以及摄取和 出口机制。犬尿氨酸衍生的电泳液在生理pH下是带电的氨基酸，因此 将合成细胞渗透性的烷基酯化类似物，以进一步确定其信号转导机制和 在没有主动细胞转运和潜能的限速效应的情况下的治疗潜力 细胞外环境中存在的其他氨基酸的竞争。来源于特定途径的原代细胞 将利用基因敲除动物和新的生物正交标记策略来确定机制基础 犬尿氨酸衍生的电泳体的抗炎作用 信号通路及其在炎症引起的能量代谢变化中的作用。最后，潜在的 将建立犬尿氨酸衍生电泳体促进耐受性反应的体外T 细胞极化和体内内毒素耐受和耐受模型。这项研究计划将揭示具体的 犬尿氨酸途径的免疫调节作用并可能导致相关疾病的发生 对慢性炎症、自身免疫等免疫反应失调的药物干预 疾病、癌症和同种异体移植排斥反应。

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.