CD4+CD25+调节性T细胞、IL-2与免疫耐受

近年来,越来越多的研究表明CD4+CD25+调节性T细胞在免疫耐受的过程中起着非常重要的作用。IL-2作为一种T细胞生长因子调控着调节性T细胞诱导免疫耐受的过程。IL-2维持着中枢及外周的调节性T细胞的活性,但是对胸腺调节性T细胞的发育是非必要的。同时,IL-2信号影响着调节性T细胞的功能并维持着其的竞争适应性。因此,CD4+CD25+调节性T细胞通过与IL-2之间形成的免疫网络调控着免疫耐受的过程,从而影响着机体的免疫平衡。     

调节性T细胞的分化及其影响因素

调节性T细胞是近年发现的一种具有免疫抑制活性的CD4+T细胞亚群,它们可以在胸腺中被选择分化,也可以在外周淋巴组织内由转化生长因子-β等细胞因子诱导分化。本文就调节性T细胞分化过程的关键信号通路及影响因素进行综述。调控调节性T细胞的分化过程能够影响其在体内的数目,可通过对其数量的干预,为自身免疫性疾病、免疫监视、排斥反应及变态反应等相关疾病提供可能的治疗靶点。     

调节性T细胞及其调节机制

免疫系统中许多细胞相互作用以保护机体免受各种病原体造成的伤害,同时机体又发展了多种机制调控免疫系统以预防对自身抗原的免疫应答或对病原体的过度应答。除了抗原刺激免疫活性细胞激活和分化的内在稳态调节机制外,调节性T细胞所介导的外源性机制在免疫调节中发挥着举足轻重的作用。目前发现的调节性T细胞主要包括CD4+CD25+调节性T细胞、Tr1调节性T细胞、Th3调节性T细胞、CD8+调节性T细胞、NK T细胞、TCRγδ+T细胞、DN T细胞。本文介绍这些调节性T细胞的表型和作用机制的研究进展。     

1型调节性T细胞的表型和功能

1型调节性T细胞(Tr1)在免疫耐受的诱导和维持过程中发挥重要作用。Tr1细胞通常在免疫耐受的环境中由外来抗原诱导产生,通过产生高水平的IL-10而发挥免疫抑制作用。而CD4 CD25 调节性T细胞(Tregs)可在胸腺中天然产生也可在外周被抗原诱导产生,通过细胞接触发挥抑制作用。现对Tr1细胞的表型、功能及其抑制作用机制等方面的研究进展进行综述。     

白细胞介素-2联合环磷酰胺对乳腺癌荷瘤小鼠调节性T细胞的影响

目的：调节性T细胞（Regulatory T cells,Treg）被认为能够抑制抗肿瘤免疫反应,从而促进肿瘤生长。环磷酰胺（Cyclophosphamide,CTX）是个常规化疗药物,现在更多的注意力集中在其小剂量应用时可以删除Treg。了解小剂量环磷酰胺联合白细胞介素-2（Interleukin-2,IL-2）对4T1Balb/c乳腺癌荷瘤小鼠调节性T细胞的影响及其抗肿瘤效果。方法：通过皮下接种4T1乳腺癌细胞建立乳腺癌Balb/c荷瘤小鼠模型;20只荷瘤小鼠随机分为IL-2＋NS组、PBS＋CTX组、IL-2＋CTX组及PBS＋NS组,在种瘤第10天开始对荷瘤小鼠分别经腹腔按方案给药。在种瘤后第16天人道处死小鼠,采用流式细胞术检测小鼠脾脏中CD4＋CD25＋调节性T细胞数量,应用ELISA法检测血清干扰素-γ浓度,电子称称量肿瘤重量。结果：与对照组相比,在应用IL-2后,荷瘤小鼠脾脏CD4＋CD25＋/CD4＋比值增加,在应用IL-2的同时使用小剂量CTX可减少CD4＋CD25＋/CD4＋的比值;单次及联合用药均可提高血清INF-γ浓度;联合用药可减少肿瘤重量。结论：小剂量CTX可以减少由使用IL-2所增加的Treg数量,促进抗肿瘤免疫,提高IL-2的抗瘤效果,从而抑制肿瘤生长。该研究可能为乳腺癌的临床治疗提供一种有效的方法。     

双歧杆菌完整肽聚糖对食物过敏小鼠调节性T细胞影响的研究

目的以食物过敏小鼠为动物模型,通过灌喂双歧杆菌完整肽聚糖(Whole Peptidoglycan,WPG),观察其对调节性T细胞的作用。方法 4～6周龄SPF级无鸡蛋喂养BALB/c雌鼠随机分为3组,每组8只。取其中2组建立食物过敏模型,分别为OVA致敏阳性对照组、OVA激发后灌喂双歧杆菌WPG治疗组和生理盐水对照组。采用ELISA法检测各组血清中OVA特异性IgE、IL-10和TGF-β1水平;流式细胞术分析脾脏单个核细胞悬液中CD4+CD25+调节性T细胞的数量变化。结果 OVA组IL-10、TGF-β1水平显著高于对照组(P分别0.05和0.01);WPG组血清IL-10和TGF-β1水平显著低于OVA组(P0.05)。OVA组脾CD4+CD25+T淋巴细胞的百分比低于对照组(P0.05),WPG组与OVA组相比有升高趋势,差异有统计学意义(P0.05);OVA组脾Foxp3+CD4+CD25+调节性T细胞的百分比显著低于对照组(P0.01),WPG组与OVA组相比有升高趋势,差异有统计学意义(P0.01)。结论双歧杆菌WPG可以增加食物过敏小鼠CD4+CD25+调节性T细胞数量,刺激细胞因子IL-10和TGF-β分泌。     

调节性T细胞在动脉粥样硬化发病中的作用

CD4^＋CD25^＋调节性T细胞（CD4^＋CD25^＋Treg）是一个具有独特免疫调节功能的T细胞亚群,它不仅抑制自身免疫性疾病的发生,而且可能参与诱导移植耐受以及肿瘤免疫调节,在维持机体内环境稳态中起重要作用。本文综述了CD4^＋CD25^＋调节性T细胞的特点和调节机制,以及在动脉粥样硬化发生发展中的可能作用。最新研究提示其可能是机体内源性有效的抑制动脉粥样硬化的因子。这些研究成果为理解动脉粥样硬化的免疫病理机制提供了新的观点,并可能为应用调节性T细胞作为靶点,寻找治疗动脉粥样硬化的免疫调节制剂提供新的策略。     

调节性T细胞抑制作用机制的研究进展

调节性T细胞(Treg)对维持机体免疫动态平衡具有重要作用。不仅诱导产生自身免疫耐受,防止自身免疫疾病的发生,而且能够限制免疫防御中T、B细胞过度活化,避免造成组织损伤。最近研究发现,Treg可能导致效应性免疫细胞失活,降低机体对肿瘤和病原的免疫应答。尽管Treg可能通过调节免疫细胞活化、增值和分化及效应等多环节产生抑制作用,但其抑制机制仍未清楚。本文对近几年国外研究Treg可能的抑制作用机制的进展作一综述。     

消化道肿瘤患者外周血调节性T细胞的变化及其意义

目的:通过测定外周血CD4+CD25+Foxp3+调节性T(Treg)细胞比例,探讨其与消化道肿瘤发生、发展的关系.方法:采用流式细胞术(FCM)检测156例消化道恶性肿瘤患者(消化道恶性肿瘤组)与50名健康体检者(对照组)的外周血中CD4+CD25+Foxp3+Treg细胞的水平,并进行比较分析.结果:消化道肿瘤患者CD4+CD25+Foxp3+Treg比例明显高于对照组(P<0.01),且随疾病进展恶性肿瘤患者外周血CD4+CD25+Foxp3+Treg细胞的比例升高.结论:CD4+CD25+Foxp3+Treg在消化道肿瘤患者外周血中比例升高,提示其可能是癌症患者细胞免疫功能削弱的机制之一,与消化道肿瘤的发生和发展密切相关.     

Treg细胞在慢性乙肝患者外周血中的表达及其对DC细胞的抑制作用

目的:检测慢性乙型肝炎患者外周血中Treg细胞的比例,探讨其对DC细胞的免疫抑制作用。方法:检测CHB患者和正常对照组外周血CD4+,CD25+,Treg及DC表面因子CD80和HLA-DR的表达;在DC培养不同时间内加入不同比例CHB Treg细胞,观察DC对淋巴细胞增殖的影响以及细胞因子IL-10及TGF-β的表达变化。结果:CHB患者外周血Treg细胞比例高于对照组,差异有统计学意义(P0.05);CHB患者DC细胞表面分子CD80和HLA-DR表达均低于对照组,差异有统计学意义(P0.05);经Treg细胞处理后,DC细胞刺激淋巴细胞的增殖能力下降,淋巴细胞增殖的抑制率显著升高(P0.05);随Treg细胞增加,IL-10及TGF-β水平升高,差异有统计学意义(P0.05)。结论:CHB患者外周血中Treg细胞的增加可能通过诱导IL-10和TGF-β的表达来抑制DC细胞的免疫功能。     

调节性T细胞与自身免疫性疾病

自身免疫性疾病是由于机体正常免疫耐受功能受损导致免疫系统对自身组织结构和功能的破坏,并出现一定临床表现的一类疾病.调节性T细胞作为一类具有负向免疫调节功能的淋巴细胞亚群在免疫自稳和免疫耐受中起关键作用,既能抑制不恰当的免疫反应,又能限制免疫应答的范围、程度及作用时间,对效应性T细胞的增殖及免疫活性的发挥产生抑制,因此在许多自身免疫性疾病的发病中扮演重要角色.近年来的研究表明调节性T细胞可以通过细胞接触、分泌细胞因子、基因调控等多种途径发挥作用,在不同的疾病,不同的内环境因素作用下可以表现出不同的特点,转录因子Foxp3作为调节性T细胞的特异性标志是其分化成熟及功能维持的根本.     

CD4+CD25+调节性T细胞

调节性T细胞(regulatory T cells,Treg)是机体维持自身耐受的重要组成部分。CD4^ CD25^ Treg细胞来源于胸腺,其主要功能是抑制自身反应性T细胞,并且其作用是通过直接的Treg-T效应细胞之间的相互接触方式来实现的。CD4^ CD25^ Treg细胞可分泌多种抑制性细胞因子,但与其抑制功能关系并不明确,目前有证据表明GITR和Foxp3与CD4^ CD25^ Treg细胞的抑制功能有关,并且Foxp3已作为CD4^ CD25^ Treg细胞的特异性标志。通过IL-10、TGF-β等抑制性细胞因子、imDC以及转基因技术可以产生具有免疫抑制功能的调节性T细胞。调节性T细胞在免疫相关性疾病、肿瘤免疫和抗感染免疫等方面具有重要意义。     

Lymph Node Stromal Cells Generate Antigen-Specific Regulatory T Cells and Control Autoreactive T and B Cell Responses

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Dendritic Cells and Regulatory T Cells in Atherosclerosis

Although macrophages and other immune system cells, especially T cells, have been shown to play disease-promoting roles in atherosclerosis, less is known about the role of antigen presenting cells. Functional, immune stimulating dendritic cells (DCs) have recently been detected in aortic intima, the site of origin of atherosclerosis. We had compared DCs with macrophages in mice with experimental atherosclerosis, to clearly define cell types by developmental and functional criteria. This review summarizes recent advances in studies of DCs in humans and in mouse models of atherosclerosis, as well as providing a simple strategy to measure regulatory T (Treg) cells in the mouse aorta.     

CD4+CD25+调节性T细胞的外周维持

CD4 CD25 调节性T细胞作为一种抑制性T细胞功能亚群,在维持机体的免疫自稳和免疫耐受方面发挥了关键作用。该作用的发挥与其外周细胞库的维持密切相关。新近的研究显示CD4 CD25 调节性T细胞主要通过两种机制来维持其外周细胞库,一些功能分子参与其中。     

喘可治注射液对小鼠体外CD4+CD25+T细胞的影响

利用荧光抗体标记和流式细胞术检测喘可治对刀豆蛋白A(ConA)诱导的T细胞CD69和CD25表达的影响,研究喘可治是否具有促进CD4 CD25 调节性T细胞升高的作用.结果发现喘可治对ConA诱导的T细胞活化标志分子CD69的表达具有抑制作用,但对CD25的表达具有促进作用.说明喘可治对T细胞活化具有抑制作用,CD25表达的上调并不是由活化引起的,而很可能是CD4 CD25 Tr水平升高的标志.     

Epicubenol and Ferruginol induce DC from human monocytes and differentiate IL-10-producing regulatory T cells in vitro

Epicubenol and 19-hydroxyferruginol (Ferruginol) are sesquiterpenes isolated from the black heartwood of Cryptomeria japonica. Dendritic cells (DC) are specialized antigen-presenting cells that monitor the antigenic environment and activate na?ve T cells. The role of DC is not only to sense danger but also to tolerize the immune system to antigens encountered in the absence of maturation/inflammatory stimuli. In this study, we attempted to investigate the effects of Epicubenol and Ferruginol on the phenotypic and functional maturation of human monocytes-derived DC in vitro. Human monocytes were cultured with GM-CSF and IL-4 for 6 days under standard conditions, followed by another 2 days with Epicubenol or Ferruginol. The expression levels of CD1a, CD83, and HLA-DR as expressed by mean fluorescence intensity (MFI) on Epicubenol-primed DC or Ferruginol-primed DC were enhanced. Allogeneic Epicubenol-primed DC or Ferruginol-primed DC co-cultured with na?ve T cells at 1:5 ratio, secreted IL-10 and TGF-beta, but little IL-4. Moreover, T cells that develop in co-culture of Epicubenol-primed DC or Ferruginol-primed DC and na?ve T cells at 1:5 ratio suppressed the proliferation of autologous T cells at Treg cells: Ttarget cells and this suppression of proliferation was inhibited by anti-IL-10 mAb. The expression of FoxP3 mRNA on T cells that develop in co-culture of Epicubenol-primed DC or Ferruginol-primed DC and na?ve T cells was lower. From these results, Epicubenol and Ferruginol may induce IL-10-producing Treg 1 cells from na?ve T cells by modulating DC function. It seems that Epicubenol and Ferruginol appear to be a target for tolerance after transplantation and in autoimmune diseases.     

Synthetic TGF-β Signaling Agonist-Treated Dendritic Cells Induce Tolerogenicity and Antirheumatic Effects

The newly synthesized compound TGF-β signaling agonist (T74) is a small molecule associated with the TGF-β receptor signaling pathway. Tolerogenic dendritic cells (tDCs) have been used to examine immunosuppressive and anti-inflammatory effects in multiple autoimmune disease models. The aim of this study was to investigate whether treatment of DCs with T74 has an antirheumatic effect in a mouse model of collagen-induced arthritis (CIA). Bone marrow-derived cells were obtained from DBA/1J mice and differentiated into DCs. T74-treated DCs (T74-DCs) were generated by treating bone marrow-derived DCs with LPS, type II collagen, and T74. T74-DCs expressed lower levels of surface molecules and inflammatory cytokines associated with antigen presentation and T cell stimulation. The ability of T74-DCs to differentiate effector T cells was lower than that of T74-untreated DCs (NT-DCs), but T74-DCs increased the regulatory T (Treg) cell differentiation in vitro. DBA/1J mice received two subcutaneous (s.c.) injections of type II collagen to establish CIA. Mice then received two s.c. injections of T74-DCs or NT-DCs. Joint inflammation was ameliorated in the paws of T74-DC-treated mice. Additionally, Treg populations in T74-DC-treated mice were higher than in NT-DC-treated or PBS-treated CIA mice. Taken together, these results demonstrate that T74 induces tolerance in DCs, and that T74-mediated DCs exert antirheumatic effects via induction of Tregs.     

Immunologic Memory in Pregnancy: Focusing on Memory Regulatory T Cells

A successful pregnancy requires the maternal immune system to tolerate an allogeneic fetus. The incidence of preeclampsia and other complications related to impaired fetal tolerance is lower during the second pregnancy than during the first pregnancy. At the same time, compared with normal pregnant women in the previous pregnancy, patients with pregnancy complications in the previous pregnancy also have an increased risk of the disease when they become pregnant again. This difference may be related to the immunological memory of pregnancy. Regulatory T cells (Tregs) are immunosuppressive CD4⁺ T cells that play a predominant role in maintaining immune tolerance. In addition, Tregs possess immunological memory properties, including fetal or paternal-specific memory Tregs and Tregs expressing memory cell makers, forming an immunoregulatory memory against fetal antigens. In this review, we provide an overview of the characteristics of memory Tregs in pregnancy, evidence regarding the existence of memory Tregs in human pregnancy, as well as in mouse models. We also discuss the mechanism of memory Tregs induction, maintenance, and action. In addition, we described their changes during the first pregnancy, second pregnancy, postpartum, and pathological pregnancy in order to provide new targets for the diagnosis and treatment of pregnancy related diseases.     

调节性 T 细胞发育的一个关键转录因子 Foxp3

调节性 T 细胞是目前免疫学领域研究的热点,对于维持机体免疫耐受和免疫应答稳态具有非常重要的作用 . 对其发育和功能机制的深入认识,不但有助于了解错综复杂的免疫系统理论,而且在自身免疫性疾病、肿瘤和艾滋病的治疗以及移植耐受的诱导等方面具有广泛的应用前景 . 最近的研究发现,转录因子 Foxp3 对于调节性 T 细胞的发育具有重要的作用,是调节性 T 细胞发育的一个关键转录因子 .