College of Food Science and Technology, South China University of Technology, Guangzhou, China.
Guangdong Wei-Wei Biotechnology Co., Ltd, Guangzhou, China.
Crit Rev Food Sci Nutr. 2022;62(31):8793-8811. doi: 10.1080/10408398.2021.1934813. Epub 2021 Jun 4.
Tryptophan (TRP), as an essential amino acid, plays crucial roles in maintaining immune homeostasis due to its complex metabolism pathway, including the microbial metabolism, 5-hydroxytryptamine and kynurenine pathways (KP). Metabolites from these pathways can act antioxidant and endogenous ligand of aryl hydrocarbon receptor (including microbiota metabolites: indole, indole aldehyde, indole acetic acid, indole acrylic acid, indole lactate, indole pyruvate acid, indole propionic acid, skatole, tryptamine, and indoxyl sulfate; and KP metabolites: kynurenine, kynurenic acid, 3-hydroxyanthranilic acid, xanthurenic acid, and cinnabarinic acid) for regulating immune response. In immune-related diseases, the production of pro-inflammatory cytokine activates indoleamine-2,3-dioxygenase, a rate-limiting enzyme of KP, leading to abnormal TRP metabolism in vivo. Many recent studies found that TRP metabolism could be regulated by diet, and the diet regulation on TRP metabolism could therapy related diseases. Accordingly, this review provides a critical overview of the relationships among diet, TRP metabolism and immunity with the aim to seek a treatment opportunity for immune-related diseases.
色氨酸（TRP）作为一种必需氨基酸，由于其复杂的代谢途径，包括微生物代谢、5-羟色胺和犬尿氨酸途径（KP），在维持免疫稳态方面发挥着关键作用。这些途径的代谢物可以作为抗氧化剂和芳烃受体的内源性配体（包括微生物代谢物：吲哚、吲哚醛、吲哚乙酸、吲哚丙烯酸、吲哚乳酸、吲哚丙酮酸、吲哚丙酸、粪臭素、色胺和吲哚硫酸；和 KP 代谢物：犬尿氨酸、犬尿氨酸酸、3-羟基邻氨基苯甲酸、黄尿酸和肉桂酸），从而调节免疫反应。在免疫相关疾病中，促炎细胞因子的产生会激活 KP 的限速酶——犬尿氨酸 2,3-双加氧酶，导致体内 TRP 代谢异常。许多最近的研究发现，TRP 代谢可以通过饮食来调节，而 TRP 代谢的饮食调节可以治疗相关疾病。因此，本综述批判性地概述了饮食、TRP 代谢和免疫之间的关系，以期为免疫相关疾病寻求治疗机会。
