CD4+CD25+ T cells in skin lesions of patients with cutaneous leishmaniasis exhibit phenotypic and functional characteristics of natural regulatory T cells

Endogenous regulatory T (Treg) cells are involved in the control of infections, including Leishmania infection in mice. Leishmania viannia braziliensis is the main etiologic agent of cutaneous leishmaniasis (CL) in Brazil, and it is also responsible for the more severe mucocutaneous form. Here, we investigated the possible involvement of Treg cells in the control of the immune response in human skin lesions caused by L. viannia braziliensis infection. We show that functional Treg cells can be found in skin lesions of patients with CL. These cells express phenotypic markers of Treg cells--such as CD25, cytotoxic T lymphocyte-associated antigen 4, Foxp3, and glucocorticoid-induced tumor necrosis factor receptor--and are able to produce large amounts of interleukin-10 and transforming growth factor- beta . Furthermore, CD4+CD25+ T cells derived from the skin lesions of 4 of 6 patients with CL significantly suppressed in vitro the phytohemagglutinin-induced proliferative T cell responses of allogeneic peripheral-blood mononuclear cells (PBMCs) from healthy control subjects at a ratio of 1 Treg cell to 10 allogeneic PBMCs. These findings suggest that functional Treg cells accumulate at sites of Leishmania infection in humans and possibly contribute to the local control of effector T cell functions.     

CD4+CD25+调节性T细胞与支气管哮喘

支气管哮喘是一种常见的慢性呼吸道疾病,其免疫发病机制尚不十分清楚。CD4 CD25 调节性T细胞是一种特殊的调节性T细胞,参与自身免疫调节,维持自身免疫耐受。本文就CD4 CD25 调节性T细胞的特性及与支气管哮喘的发病机制、治疗、预后的研究进展做一综述。     

Precommitment of CD4+CD8+ thymocytes to either CD4 or CD8 lineages.

CD4+ and CD8+ mature T cells arise from CD4+CD8+ precursors in the thymus. During this process, cells expressing T-cell receptors (TCRs) reactive with self major histocompatibility complex (MHC) class I or II molecules are positively selected to the CD8 or CD4 lineage, respectively. It is controversial whether lineage commitment of CD4+CD8+ thymocytes is controlled directly by TCR specificity for MHC (instructional model) or, alternatively, by processes that operate independently of TCR specificity (stochastic model). We show here that CD4+CD8+ thymocytes bearing a MHC class I-restricted transgenic TCR can be subject to two alternative developmental fates. One population of CD4+CD8+ cells is positively selected by MHC class I molecules to the CD8 lineage as expected, whereas the other CD4+CD8+ population rearranges endogenous TCR genes and is positively selected by MHC class II molecules to the CD4 lineage. Blocking TCR-MHC class II interactions in vivo does not interfere with the generation of CD4+CD8+ cells expressing endogenous TCRs but does prevent their subsequent maturation to CD4+ cells. These data support a version of the stochastic model in which CD4+CD8+ thymocytes are precommitted to the CD4 or CD8 lineage independently of TCR specificity for MHC and prior to positive selection.     

CD4+CD25+调节性T细胞及其与移植物抗宿主病和移植物抗白血病的关系

CD4 CD25 调节性T细胞(Treg细胞)是CD4 T细胞的一个亚群,在维持机体自身免疫耐受,诱导移植耐受等方面发挥重要作用。移植物抗宿主病(GVHD)是异基因造血干细胞移植最严重的并发症之一。在动物骨髓移植模型中证实Treg细胞可以促进移植物植入,减少GVHD的发生率和严重度,但并没有消除移植物抗白血病(GVL)的作用。在人体有关Treg细胞对GVHD的影响因研究者分析Treg细胞采用的表型不同,其结论存在不一致性。本文就新近Treg细胞生物学特性,Treg细胞与GVHD和GVL的关系的研究进展进行综述。     

CD4+CD25+调节性T细胞——免疫治疗新策略

1995年日本学者Sakaguchi等[1]首次证实外周血中CD4+T细胞中5%～10%的CD4+CD25+T细胞具有免疫抑制功能,它们能预防和阻止自身免疫病的发生发展,这群细胞被定义为CD4+CD25+调节性T细胞(regulatory T cells,Treg).近十多年对Treg在自身免疫病发病中的作用及机制进行了深入研究,发现免疫病治疗后Treg治疗免疫病具有广阔应用前景.     

CD4+ CD25+ 调节性T细胞与自身免疫性甲状腺疾病

CD4+ CD25+ 调节性T细胞为新近发现的一群功能成熟的T细胞亚群.其特征性表达叉头盒蛋白3(Foxp3)分子,专职免疫无能和免疫抑制,在维持外周免疫耐受,防止自身免疫性疾病发病中起着极为关键的作用.CD4+ CD25+ 调节性T细胞在自身免疫性甲状腺疾病(AITD)发病中的作用引起了人们的关注.动物实验发现CD4+ CD25+ 调节性T细胞存在与否决定了实验动物是否发生实验性自身免疫性甲状腺炎(EAT)和Graves病.人体研究发现CD4+ CD25+ 调节性T细胞数目和功能异常与人AITD发生密切相关.这些研究结果提示,CD4+ CD25+ 调节性T细胞可能在AITD发病中起重要作用.     

CD4+CD25+ regulatory T cells control CD8+ T-cell effector differentiation by modulating IL-2 homeostasis

CD4(+)CD25(+) regulatory T cells (Treg) play a crucial role in the regulation of immune responses. Although many mechanisms of Treg suppression in vitro have been described, the mechanisms by which Treg modulate CD8(+) T cell differentiation and effector function in vivo are more poorly defined. It has been proposed, in many instances, that modulation of cytokine homeostasis could be an important mechanism by which Treg regulate adaptive immunity; however, direct experimental evidence is sparse. Here we demonstrate that CD4(+)CD25(+) Treg, by critically regulating IL-2 homeostasis, modulate CD8(+) T-cell effector differentiation. Expansion and effector differentiation of CD8(+) T cells is promoted by autocrine IL-2 but, by competing for IL-2, Treg limit CD8(+) effector differentiation. Furthermore, a regulatory loop exists between Treg and CD8(+) effector T cells, where IL-2 produced during CD8(+) T-cell effector differentiation promotes Treg expansion.     

调节性T细胞与移植物抗宿主病相关性的研究进展

异基因造血干细胞移植(allo-HSCT)已被广泛应用于治疗多种遗传性疾病、恶性或非恶性血液系统疾病,然而移植物抗宿主病(GVHD)仍然是导致allo-HSCT后死亡的最重要的并发症之一。目前应用多种免疫抑制剂防治GVHD已达到一定的治疗疗效,但却大大增加了感染和复发的几率。利用免疫系统内在的调节机制调节异基因免疫应答,控制GVHD的发生,同时保留抗感染及抗肿瘤免疫已成为目前移植耐受研究的焦点。调节性T细胞可通过“主动”的方式抑制免疫系统对自身和外来抗原的应答,在维持机体免疫耐受和免疫应答稳态方面具有非常重要的作用。CD4 CD2 …     

De novo generation of antigen-specific CD4+CD25+ regulatory T cells from human CD4+CD25- cells

Antigen-specificity is a hallmark of adaptive T cell-mediated immune responses. CD4+CD25+FOXP3+ regulatory T cells (T(R)) also require activation through the T cell receptor for function. Although these cells require antigen-specific activation, they are generally able to suppress bystander T cell responses once activated. This raises the possibility that antigen-specific T(R) may be useful therapeutically by localizing generalized suppressive activity to tissues expressing select target antigens. Here, we demonstrate that T(R) specific for particular peptide-MHC complexes can be generated from human CD4+CD25- T cells in vitro and isolated by using HLA class II tetramers. Influenza hemagglutinin epitopes were used to generate hemagglutinin-specific T(R), which required cognate antigen for activation but which subsequently suppressed noncognate bystander T cell responses as well. These findings have implications for the generation of therapeutic regulatory T cells in disease, and also suggest an important mechanism by which T cells may be regulated at the site of inflammation.     

CD4+CD25+调节性T细胞及其分子标记物与支气管哮喘

CD4+CD25+调节性T细胞是一类以免疫抑制和免疫无能为特征的淋巴细胞群,FOXP3是CD4+CD25+调节性T细胞一个特征性的分子标志物,并且对CD4+CD25+调节性T细胞的发育、外周表达和功能维持有着关键性的作用.近年来,多项研究显示CD4+CD25+调节性T细胞参与并影响了支气管哮喘的发生、发展过程,对调节性T细胞或其相关基因的干预也许会成为支气管哮喘治疗的新方向.     

CD4+CD25+ T细胞在溃疡性结肠炎中的表达及其临床意义

目的 研究溃疡性结肠炎(UC)患者外周血CD 4CD 25调节性T细胞比例的变化,探讨其在UC病理机制中的意义.方法 选择UC患者33例,对照组20例.用流式细胞仪检测外周血CD 4CD 25T细胞阳性率.用RT-PCR检测外周单个核细胞(PBMC)中Foxp3 mRNA的表达.用酶联免疫吸附试验检测血清中IL-10和TGF-β的浓度.结果 UC患者CD 4CD 25T细胞占CD 4T细胞的比例明显低于对照组(P＜0.01),并且与疾病的活动指数及血沉水平均呈显著负相关(R值分别为-0.660和-0.572,P值均＜0.01).UC患者Foxp3 mRNA的表达也明显低于对照组(P＜0.01).两组患者血清IL-10和TGF-β的浓度比较无明显差异(P＞0.05).结论 UC患者外周血CD 4CD 25 调节性T细胞明显降低,与疾病活动性相关,提示这类细胞可能在UC的病理机制中发挥作用.Foxp3表达降低可能是导致CD 4CD 25 T细胞发育障碍的重要因素.     

Stability of human rapamycin-expanded CD4+CD25+ T regulatory cells

Background

The clinical use of ex vivo-expanded T-regulatory cells for the treatment of T-cell-mediated diseases has gained increasing momentum. However, the recent demonstration that FOXP3⁺ T-regulatory cells may contain interleukin-17–producing cells and that they can convert into effector cells once transferred in vivo raises significant doubts about their safety. We previously showed that rapamycin permits the ex vivo expansion of FOXP3⁺ T-regulatory cells while impairing the proliferation of non-T-regulatory cells. Here we investigated the Th17-cell content and the in vivo stability of rapamycin-expanded T-regulatory cells as pertinent aspects of cell-based therapy.

Design and Methods

T-regulatory-enriched cells were isolated from healthy volunteers and were expanded ex vivo with rapamycin with a pre-clinical applicable protocol. T-regulatory cells cultured with and without rapamycin were compared for their regulatory activity, content of pro-inflammatory cells and stability.

Results

We found that CD4⁺CCR6⁺CD161⁺ T cells (i.e., precursor/committed Th17 cells) contaminate the T-regulatory cells cultured ex vivo in the absence of rapamycin. In addition, Th17 cells do not expand when rapamycin-treated T-regulatory cells are exposed to a “Th17-favorable” environment. Rapamycin-expanded T-regulatory cells maintain their in vitro regulatory phenotype even after in vivo transfer into immunodeficient NOD-SCID mice despite being exposed to the irradiation-induced pro-inflammatory environment. Importantly, no additional rapamycin treatment, either in vitro or in vivo, is required to keep their phenotype fixed.

Conclusions

These data demonstrate that rapamycin secures ex vivo-expanded human T-regulatory cells and provide additional justification for their clinical use in future cell therapy-based trials.     

CD4+CD25+ regulatory T cells inhibit immune-mediated transgene rejection

Like cellular transplantation, gene therapy is often limited by immune rejection of the newly expressed antigen. In a model of gene transfer in muscle, delivery of the influenza hemagglutinin (HA) membrane protein by adeno-associated virus (AAV) is impaired by a strong immune response that leads to a rapid rejection of the transduced fibers. We show here that injection of HA-specific CD4+CD25+ T cells from T-cell receptor (TCR)-transgenic animals, concomitant with gene transfer, down-regulates the anti-HA cytotoxic and B-lymphocyte responses and enables persistent HA expression in muscle. This demonstrates for the first time that adoptive transfer of antigen-specific CD4+CD25+ regulatory T cells can be used to induce sustained transgene engraftment in solid tissues.     

Therapeutic vaccination using CD4+CD25+ antigen-specific regulatory T cells

Autoimmune disease results from the dysregulation of basic tolerogenic processes designed to control self/non-self-discrimination. Approaches to treat autoimmunity have focused historically on potent immunosuppressives that block the activation and expansion of antigen-specific T cells before they differentiate into pathogenic T cell responses. These therapies are very efficient in reducing clonal expansion and altering early signaling pathways. However, once the pathogenic responses are established (i.e., autoimmunity), the interventions are less effective on activated and differentiated T cell subsets (including memory T cells) or acting in the presence of an inflammatory milieu to abort immune responses at the target tissue and systemically. Moreover, the current immunotherapies require continuous use because they do not redirect the immune system to a state of tolerance. The continuous treatment leads to long-term toxicities and can profoundly suppress protective immune responses targeted at viruses, bacteria, and other pathogens. Over the past decade, there have been tremendous advances in our understanding of the basic processes that control immune tolerance. Among the most exciting has been the identification of a professional regulatory T cell subset that has shown enormous potential in suppressing pathologic immune responses in autoimmune diseases, transplantation, and graft vs. host disease. In this review, we summarize current efforts to induce and maintain tolerance in the autoimmune diabetes setting by using therapeutic vaccination with CD4(+)CD25(+) regulatory T cells. Emphasis will be placed on approaches to exploit regulatory T cells either directly or through the use of anti-CD3 immunotherapy.