吲哚胺2,3-双加氧酶与树突状细胞

吲哚胺2,3-双加氧酶(IDO)是降解必需氨基酸色氨酸的限速酶,广泛表达于各种组织和细胞,在感染或炎症期间其表达量明显增高.而树突状细胞(DC)是专职的抗原提呈细胞,IDO在其内的表达可影响DC的表型和功能,进而抑制T细胞的免疫反应.研究IDO和DC的关系对深入理解IDO在免疫系统中的作用以及开发新的免疫调节策略都具有重要意义.     

吲哚胺2,3双加氧酶(IDO)的免疫调节作用

吲哚胺 2 ,3双加氧酶 (indoleamine 2 ,3 dioxygenase ,IDO )是肝脏以外唯一可催化色氨酸沿犬尿酸途径分解代谢的限速酶 ,在哺乳动物的组织与细胞 ,尤其是淋巴组织和胎盘中广泛表达。它通过降解局部组织中的色氨酸 ,在诱发宿主免疫防御、抑制T细胞免疫和抗肿瘤免疫、诱导母胎免疫耐受和移植物免疫耐受中均发挥重要的代谢性免疫调节作用。     

吲哚胺2,3-双加氧酶1在胃癌中的研究进展

胃癌 (Gastric Cancer,GC) 是全球第五大最常见的恶性肿瘤,也是第四大癌症死亡相关原因。胃癌异质性明显,肿瘤微环境复杂,免疫检查点抑制剂虽然在晚期胃癌中展现出一定抗肿瘤疗效,但获益人群仍在少数。吲哚胺2,3-双加氧酶 1 (Indoleamine 2,3-Dioxygenase 1,IDO1) 是色氨酸沿犬尿氨酸途径代谢中的关键酶,对肿瘤免疫逃逸起到了关键作用。目前已有多项研究表明IDO1在胃癌发生发展及幽门螺杆菌感染和EB病毒感染中发挥重要作用,所以靶向IDO1有望成为胃癌免疫治疗的新策略。本文就IDO1作用机制、IDO1在胃癌及相关疾病中的研究进展及IDO1抑制剂在胃癌中的应用前景进行综述。     

人外周血单个核细胞和肿瘤细胞中吲哚胺2,3双加氧酶mRNA水平的实时定量RT-PCR分析

目的 定量分析HIV-1感染者及高危人群外周血单个核细胞(PBMC)和人源肿瘤细胞在Toll样受体(TLR)配体刺激前后吲哚胺2,3双加氧酶(indoleamine 2,3-dioxygenase,IDO)的表达水平.方法 建立人IDO mRNA的TaqMan探针实时荧光定量RT-PCR检测方法;检测HIV-1阳性个体和高危人群PBMC中IDO mRNA水平;检测TLR4、TLR7/8、TLR9配体刺激前后人黏膜(T84、Caco2、Hela)和白细胞(THP-1、MT-4)来源肿瘤细胞中IDO mRNA的水平.结果 HIV-1阳性个体PBMC中IDO mRNA水平较高危人群高(103.42拷贝IDO mRNA/106拷贝GAPDH mRNA);但也有部分高危人群个体的PBMC含有较高水平的IDO mRNA;肿瘤细胞在TLR配体刺激后IDO mRNA的水平可以显著升高,因细胞系和TLR配体种类不同而异.结论 本研究表明IDO可能在我国HIV-1感染者体内病毒免疫逃逸和肿瘤发生中起作用,值得深入研究.     

吲哚胺2,3-双加氧酶参与乳腺癌患者免疫耐受的研究

目的:研究吲哚胺2,3-双加氧酶(Indoleamine2,3-dioxygenase,IDO)在乳腺癌组织和引流淋巴结中的表达及调节性T细胞在相应组织内的分布,探讨IDO在乳腺癌免疫耐受中的作用机制.方法:收集26例乳腺癌患者的癌组织、癌旁正常乳腺、引流淋巴结和10例乳腺良性病变组织,用RT-PCR法检测IDO mRNA表达,用免疫组织化学法检测IDO和Foxp3蛋白表达.结果:乳腺癌引流淋巴结中IDO mRNA表达水平及IDO表达阳性指数[(19.59±7.65)%]高于原发乳腺癌组织[IDO表达阳性指数(13.16±7.82)%](P<0.05),乳腺癌组织中IDO mRNA表达水平及IDO表达阳性指数高于乳腺良性病变组织[IDO表达阳性指数(3.24±1.30)%]和癌旁正常乳腺组织[IDO阳性细胞指数(2.70±1.53)%](P均<0.05).乳腺癌组织中IDO表达水平与肿瘤临床分期和淋巴结转移相关(P<0.05).乳腺癌引流淋巴结中Foxp3阳性细胞指数[(6.13±2.31)%]高于乳腺原发癌[(3.50±1.04)%],乳腺癌组织中Foxp3阳性细胞指数高于乳腺良性病变[(0.71±0.42)%]和癌旁正常乳腺组织[(0.55±0.34)%](P均<0.05).乳腺癌和引流淋巴结中IDO的表达水平与Treg细胞的分布间均正性相关(r~2=0.449,r~2=0.454,P均<0.05).结论:IDO在乳腺癌细胞中表达增高,并伴随乳腺癌和引流淋巴结中Treg细胞比例升高,提示IDO表达增高有可能通过募集Treg细胞参与肿瘤和引流淋巴结内的免疫耐受.     

IL-6上调绒毛及蜕膜组织吲哚胺2,3-双加氧酶(IDO)的表达

目的 探讨早孕绒毛和蜕膜组织中的白细胞介素6(IL-6)对吲哚胺2,3-双加氧酶(IDO)表达的调节作用.方法 收集早孕6～9周行人工流产妇女的绒毛及蜕膜组织,采用Western blot法检测绒毛、蜕膜组织IL-6与IDO蛋白的表达情况;在绒毛、蜕膜组织中,加入(10、50、100) ng/mL IL-6分别培养48...     

吲哚胺2,3二加氧酶与自身免疫性疾病

自身免疫性疾病的发病机制主要在于机体自身耐受的破坏，机体产生自身抗体和（或）自身反应性淋巴细胞，导致疾病的发生。最近很多研究表明，吲哚胺2，3-二加氧酶（indoleamine 2，3-dioxygenase，IDO）催化的色氨酸代谢与自身免疫耐受机制有关，表达IDO的细胞能够抑制T细胞免疫应答，在自身免疫性疾病的发病机制中起重要作用。因而研究IDO介导色氨酸代谢途径可以为阐明自身免疫疾病的发病机制和治疗自身免疫性疾病提供一种全新的观念。     

SOCS3和吲哚胺2,3-双加氧酶(IDO)在早孕绒毛和蜕膜组织中的表达呈负相关

目的探讨人早孕时细胞因子信号传送阻抑物3(SOCS3)及吲哚胺2,3-双加氧酶(IDO)在母胎界面的表达及其相关性。方法用Western blot法检测正常妊娠绒毛、蜕膜组织中SOCS3及IDO的表达。结果正常妊娠绒毛及蜕膜组织中均有IDO及SOCS3蛋白的表达,SOCS3与IDO表达呈高度负相关。SOCS3在绒毛和蜕膜组织中的表达无差异,而IDO在蜕膜组织中表达较高。结论在正常生理妊娠状态下,母胎界面中SOCS3参与调节IDO的表达,在妊娠免疫耐受的调节中起重要作用。     

GITRL对Kupffer细胞内脂多糖诱导的吲哚胺2,3双加氧酶的作用研究

目的:研究糖皮质激素诱导的TNF受体配体(GITRL)对Kupffer细胞(KCs)内脂多糖(LPS)诱导的吲哚胺2,3双加氧酶(IDO)的影响。方法:分离小鼠KCs后分为5组:Control组,只加培养基;LPS组,加入LPS(10μg/ml);LPS+Control siRNA组,转染Control siRNA后同LPS组;LPS+GITRLsiRNA组,转染GITRLsiRNA后同LPS组;LPS+Dex组,地塞米松(100μmol/L)处理后同LPS组。处理24小时后,分别采用免疫细胞化学染色、蛋白免疫印记和ELISA法检测KCs的GITRL、IDO表达及肿瘤坏死因子(TNF)-α分泌。结果:和Control组比较,LPS刺激后KCs上GITRL的表达明显上调(P<0.05),而沉默GITRL基因或者使用地塞米松能减弱其升高(P<0.05)。LPS可以诱导IDO和TNF-α在KCs上的高表达,然而GITRL基因沉默可以抑制其诱导的IDO和TNF-α的表达(P<0.05),同样地塞米松预处理也能够减弱其诱导的IDO和TNF-α的表达(P<0.05)。结论:GITRL介导了KCs内LPS诱导的IDO,地塞米松可通过下调GITRL的表达以降低LPS诱导的IDO。     

内皮源性吲哚胺2,3-双加氧酶抑制周细胞迁移及收缩蛋白表达

 目的: 探讨内皮源性吲哚胺2,3-双加氧酶(IDO)对周细胞迁移及收缩蛋白表达的影响。方法: 体外培养人肺动脉内皮细胞(HPAECs)及大鼠脑微血管周细胞。建立过表达IDO的HPAECs模型(IDO-HPAECs)。实验分为3组:对照组,以HPAECs条件培养基干预周细胞;处理组,以IDO-HPAECs条件培养基干预周细胞;抑制组,以含1-甲基色氨酸(1-mT)的IDO-HPAECs条件培养基干预周细胞。测定共培养体系一氧化氮(NO)、色氨酸及犬尿氨酸浓度。观察周细胞活性、迁移及收缩蛋白表达情况。结果: IDO-HPAECs条件培养基干预周细胞6～48 h对其活性无显著影响。处理组的周细胞迁移能力显著低于对照组(P < 0.01),抑制组显著高于处理组(P < 0.01)。共培养体系的NO浓度在各组间差异无统计学意义(P > 0.05)。处理组的色氨酸浓度显著低于对照组(P < 0.01),而抑制组显著高于处理组(P < 0.01)。处理组的犬尿氨酸浓度显著高于对照组(P < 0.01),而抑制组显著低于处理组(P < 0.01)。处理组的α-平滑肌肌动蛋白与结蛋白表达水平显著低于对照组(P < 0.01),抑制组显著高于处理组(P < 0.01)。结论: 内皮源性IDO抑制周细胞迁移及收缩蛋白表达,可能参与机体微血管功能调控。     

Indoleamine 2,3-dioxygenase regulates T cell activity through Vav1/Rac pathway

The immunoregulatory enzyme indoleamine 2,3-dioxygenase (IDO) suppresses T-cell responses and promotes immune tolerance in tumor resistance. A previous study determined that IDO inhibits Vav1 mRNA expression and the activation of Vav1 and its downstream targets in T cells in the guanine exchange factor (GEF)-independent pathway. The current study aims to determine whether IDO induces T-cell immunosuppression through Vav1/Rac signaling pathway, which is a GEF-dependent pathway. The correlation between Vav1 mRNA expressions in T cells of tumor infiltrating lymphocytes and the levels of IDO expression in lung cancer tissues from lung cancer patients was detected. HEK293 cells were stably transfected with human IDO (HEK293-IDO). T cells were isolated from human blood. HEK293-IDO cells were co-incubated with T cells in the presence or absence of an anti-CD3 antibody to activate T cell receptor (TCR) and/or 1-methyl-l-tryptophan (1-MT) to inhibit IDO activity. The early signaling proteins in T-cytoskeleton regulation through Vav1/Rac pathway of T cell were determined. A significant and negative correlation was observed between IDO and Vav1 expression in the tumor microenvironment. IDO, which was produced by HEK293-IDO cells, significantly inhibited the expression of Vav1, which resulted in defective F-actin reorganization. Thus, TCR signaling initiation was damaged. The effects on T-cells induced by the co-culture of HEK293-IDO cells with T cells were attenuated by 1-MT. Results indicate that the inhibitory effects of IDO on T cell immune responses may occur through the down-regulation of Vav1 protein expression and the suppression of Vav1/Rac cascade. These studies provide insight into the mechanisms of immune escape induced by IDO.     

Vav1蛋白与T细胞功能

Vav1表达于人体所有血细胞相对分子质量为95000的蛋白,其在T细胞抗原受体（TCR）激活后发生迅速的酪氨酸磷酸化后活化,作为鸟苷酸交换因子（GEF）发挥重要作用。Vav1主要参与T细胞信号传导途径,传导信号激活钙流（[Ca^2＋]流）、细胞外信号调节激酶（ERK）以及转录因子NF—κB。Vav1蛋白在T细胞生长发育、成熟T细胞激活、细胞因子合成及细胞骨架活动中发挥重要作用。     

Essential role for Vav1 in activation,but not development,of gammadelta T cells

Vav1 is a guanine nucleotide exchange factor essential in the development and function of alphabeta lineage T cells. Here we report that in contrast to profound effects on pre-TCR- or alphabeta TCR-dependent events in thymocyte development, Vav1 deficiency has no detectable effect on the development of gammadelta T cells. Strikingly, however, these gammadelta T cells are markedly deficient in signaling through the gammadelta TCR, as evidenced by a lack of proliferation and cytokine production in response to stimulation with anti-gammadelta TCR antibodies. We propose that Vav1 has a unique and non-redundant role in the initiation of signaling downstream of the gammadelta TCR in lymphocytes.     

Human type 1 and type 2 conventional dendritic cells express indoleamine 2,3-dioxygenase 1 with functional effects on T cell priming

Dendritic cells (DCs) are key regulators of the immune system that shape T cell responses. Regulation of T cell induction by DCs may occur via the intracellular enzyme indoleamine 2,3-dioxygenase 1 (IDO), which catalyzes conversion of the essential amino acid tryptophan into kynurenine. Here, we examined the role of IDO in human peripheral blood plasmacytoid DCs (pDCs), and type 1 and type 2 conventional DCs (cDC1s and cDC2s). Our data demonstrate that under homeostatic conditions, IDO is selectively expressed by cDC1s. IFN-γ or TLR ligation further increases IDO expression in cDC1s and induces modest expression of the enzyme in cDC2s, but not pDCs. IDO expressed by conventional DCs is functionally active as measured by kynurenine production. Furthermore, IDO activity in TLR-stimulated cDC1s and cDC2s inhibits T cell proliferation in settings were DC-T cell cell-cell contact does not play a role. Selective inhibition of IDO1 with epacadostat, an inhibitor currently tested in clinical trials, rescued T cell proliferation without affecting DC maturation status or their ability to cross-present soluble antigen. Our findings provide new insights into the functional specialization of human blood DC subsets and suggest a possible synergistic enhancement of therapeutic efficacy by combining DC-based cancer vaccines with IDO inhibition.     

The proto-oncogene Vav product is constitutively tyrosine-phosphorylated in normal human immature T cells

The proto-oncogene Vav product is markedly tyrosine-phosphorylated after the recruitment of various receptors of cells of hematopoietic origin, including mature T cells. Recent studies on Vav-deficient mice have clearly implicated the product of the proto-oncogene Vav in intrathymic T cell development. Vav tyrosine phosphorylation is probably crucial to connect early tyrosine kinase(s) to downstream molecular events leading to cell division and maturation that occur in the thymus. We investigated the tyrosine phosphorylation of Vav in human thymocytes. Immunoblotting experiments demonstrate that, as in mature T cells, tyrosine phosphorylation of Vav is induced following thymocyte stimulation through the T cell receptor. The main observation, however, is that an important fraction of cellular Vav is constitutively tyrosine-phosphorylated in freshly isolated cells. This phenomenon takes place apparently both in the CD4⁺CD8⁺ and the more mature CD4⁺CD8^? and CD4^?CD8⁺ thymocyte cell subsets. Co-immunoprecipitation experiments showed, moreover, that a small amount of Vav is engaged in the multimolecular complex that includes elements of the T cell receptor and the T cell specific ZAP-70 tyrosine kinase. Altogether, these data suggest that a critical pathway for T cell development in the human thymus likely involves the permanent activation of Vav in vivo.     

Induction of indoleamine 2,3-dioxygenase in vivo by IFN-con1.

Indoleamine 2,3-dioxygenase (IDO) activity as determined by increases in serum kynurenine was measured in a group of hepatitis C patients treated with consensus interferon (IFN-con1). Kynurenine levels increased significantly within 2 days of initiation of treatment but returned to normal values by week 4 after treatment. Although IDO is normally induced by IFN-gamma, no such IFN was detected by ELISA or biologic assays. Thus, consensus IFN induces low levels of IDO in vivo without an IFN-gamma intermediate.     

骨髓间质干细胞吲哚胺2，3-双加氧酶活性对T淋巴细胞的影响(英文)

目的: 探讨骨髓间质干细胞（MSCs）吲哚胺2，3-双加氧酶（IDO）活性对抑制T淋巴细胞应答反应的影响。方法: 从人骨髓中分离培养间质干细胞,通过其形态特点、表面标志及多向分化能力检测进行鉴定。以浓度为2×105 U/L的 IFN-γ对分离的MSCs诱导18 h，检测MSCs上IDO mRNA和IDO蛋白表达。将经过IFN-γ 2×105 U/L诱导的MSCs预先接种在培养板中，再建立混合淋巴细胞培养(MLR)体系，利用MTT法检测T淋巴细胞增殖率，并用反相高效液相色谱法检测IDO活性。结果: IFN-γ能诱导MSCs上IDO mRNA和IDO蛋白的表达；MSCs的IDO活性抑制MLR体系中T淋巴细胞增殖率。结论： 经IFN-γ刺激后的MSCs在体外可抑制异体T淋巴细胞的免疫应答，IDO活性参与了这种免疫抑制作用的发挥。