Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China; University of Chinese Academy of Sciences, Beijing, China.
State Key Laboratory of Agricultural Microbiology, College of Fisheries, Huazhong Agricultural University, Wuhan, China.
Fish Shellfish Immunol. 2019 Jun;89:301-308. doi: 10.1016/j.fsi.2019.04.005. Epub 2019 Apr 6.
Indoleamine 2,3-dioxygenase (IDO) is a kind of dioxygenase that can catalyze the degradation of levo-tryptophan (L-Trp) and plays key roles in immune tolerance. In this study, the IDO gene was cloned and functionally characterized from grass carp (gcIDO). The results showed that gcIDO overexpressed in GCO cells could catalyze the degradation of L-Trp through the L-Trp - kynurenine pathway, and this activity could be promoted by δ-aminolevulinic acid (ALA) while inhibited by levo-1-methyl tryptophan (L-1MT). Moreover, gcIDO was constitutively expressed in various tissues, and its expression could be significantly up-regulated by LPS and Poly (I:C) in peripheral blood leukocytes (PBLs). Furthermore, recombinant TGF-β1 of grass carp could up-regulate the expression of IDO, TGF-β1, CD25, and Foxp3 in PBLs, indicating that the TGF-β1/IDO pathway is present in fish. In the soybean meal induced enteritis (SBMIE) model, the expression of gcIDO in the intestine was up-regulated significantly, demonstrating that gcIDO may play an immunoregulatory role in SBMIE. Taken together, these data suggest that the IDO plays multiple roles in the immunity of fish.
色氨酸 2,3-双加氧酶（IDO）是一种能够催化左旋色氨酸（L-Trp）降解的双加氧酶，在免疫耐受中发挥关键作用。本研究从草鱼（gcIDO）中克隆并功能表征了 IDO 基因。结果表明，在 GCO 细胞中过表达的 gcIDO 可以通过 L-Trp-犬尿氨酸途径催化 L-Trp 的降解，这种活性可以被δ-氨基酮戊酸（ALA）促进，而被 L-1-甲基色氨酸（L-1MT）抑制。此外，gcIDO 在各种组织中均有组成性表达，其在外周血白细胞（PBLs）中的表达可被 LPS 和 Poly（I:C）显著上调。此外，草鱼重组 TGF-β1 可上调 PBLs 中 IDO、TGF-β1、CD25 和 Foxp3 的表达，表明鱼类存在 TGF-β1/IDO 通路。在大豆蛋白诱导的肠炎（SBMIE）模型中，肠道中 gcIDO 的表达显著上调，表明 gcIDO 可能在 SBMIE 中发挥免疫调节作用。总之，这些数据表明 IDO 在鱼类免疫中发挥多种作用。
