Development and function of naturally occurring CD4+CD25+ regulatory T cells

The immune system has evolved numerous mechanisms of peripheral T cell immunoregulation, including a network of regulatory T (Treg) cells, to modulate and down-regulate immune responses at various times and locations and in various inflammatory circumstances. Amongst these, naturally occurring CD4(+)CD25(+) Treg cells (nTreg) represent a major lymphocyte population engaged in the dominant control of self-reactive T responses and maintaining tolerance in several models of autoimmunity. CD4(+)CD25(+) Treg cells differentiate in the normal thymus as a functionally distinct subpopulation of T cells bearing a broad T cell receptor repertoire, endowing these cells with the capacity to recognize a wide range of self and nonself antigen specificities. The generation of CD4(+)CD25(+) Treg cells in the immune system is genetically controlled, influenced by antigen recognition, and various signals, in particular, cytokines such as interleukin-2 and transforming growth factor-beta1, control their activation, expansion, and suppressive effector activity. Functional abrogation of these cells in vivo or genetic defects that affect their development or function unequivocally promote the development of autoimmune and other inflammatory diseases in animals and humans. Recent progress has shed light on our understanding of the cellular and molecular basis of CD4(+)CD25(+) Treg cell-mediated immune regulation. This article discusses the relative contribution of CD4(+)CD25(+) nTreg cells in the induction of immunologic self-tolerance and provides a comprehensive overview of recent finding regarding the functional properties and effector mechanism of these cells, as revealed from various in vitro and in vivo models.     

TCRalphabeta repertoire diversity of human naturally occurring CD4+CD25+ regulatory T cells

We examined the alphabeta T cell receptor (TCR) repertoire of naturally occurring CD4+CD25+ regulatory T (Treg) cells isolated from healthy human blood. Three-color FACS analysis demonstrated that the usage of variable region segments of TCRbeta chains by CD4+CD25+ cells did not differ from those of CD4+CD25- cells. Complementarity-determining region 3 (CDR3) size distribution analyses demonstrated that the repertoire diversity of CDR3beta was almost identical between CD4+CD25+ and CD4+CD25- T cell subsets, and that there was no skewing of the CDR3beta repertoire of CD4+CD25+ T cells. In contrast, in vitro activated CD4+CD25+ T cells by cytomegalovirus-derived antigens showed a skewed CDR3 size distribution pattern. These findings support the hypothesis that naturally occurring CD4+CD25+ T cell subset in humans is 1argely composed of a T cell lineage positively selected in the thymus as a consequence of the interaction between self-peptides and TCRs and not derived from recent activation by a limited array of antigens.     

Overlap between molecular markers expressed by naturally occurring CD4+CD25+ regulatory T cells and antigen specific CD4+CD25+ and CD8+CD28- T suppressor cells

Alloantigen specific CD8+CD28- T suppressor (TS) cells differ from naturally occurring CD4+CD25+ T-regulatory (natural TR) cells not only by their phenotype but also by their mechanism of action. Natural TR have been extensively studied, leading to the identification of characteristic "molecular markers" such as Forkhead box P3 (FOXP3), glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR) and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4). We have investigated the expression of these genes in alloantigen specific TS and CD4+CD25+ T regulatory (TR) cells and found that they are expressed at levels similar to those observed in natural TR. Furthermore, similar to natural CD4+CD25+ TR, antigen-specific CD8+CD28-CD62L+ TS cells have more suppressive capacity than CD8+CD28-CD62L- TS cells. In spite of these similarities, natural TR are not antigen-specific and inhibit other T cells by T cell-to-T cell interaction, whereas TS are antigen-specific and exert their inhibitory function by interacting with antigen-presenting cells and render them tolerogenic to other T cells. The molecular characterization of TS cells may contribute to a better understanding of mechanisms involved in inhibition of immune responses in autoimmunity, transplantation, and chronic viral infection.     

桥本氏甲状腺炎患者Th17与调节性T细胞免疫失衡的研究

目的 检测桥本氏甲状腺炎(HT)患者甲状腺组织及外周静脉血中Th17细胞和调节性T 细胞(Treg)细胞相关细胞因子的表达水平,分析Th17/Treg免疫平衡在HT发病机制中的作用.方法 采用逆转录-聚合酶链反应(RT-PCR)法,检测10例HT甲功正常组、10例HT甲低组和10例正常甲状腺组织(对照组)中IL-17A...     

IL-2抑制小鼠CD4~+ CD62L~+ T细胞分化为Th17细胞

目的研究IL-2对小鼠脾脏CD4+CD62L+T细胞在体外向Th17细胞分化的作用。方法免疫磁珠法分选C57BL/6小鼠脾脏CD4+CD62L+T细胞,于抗体包被的培养板中培养3 d,实验分为对照组和IL-2处理组。对照组为经典Th17诱导分化培养基,IL-2处理组在对照组基础上于培养体系中添加IL-2。CFSE染色检测细胞增殖,Annexin V-PI法检测细胞凋亡,ELISA检测培养上清中IL-17A的浓度,荧光定量PCR检测Rorγt mRNA的表达,流式细胞术检测CD4~+IL-17~+Th17的生成比例以及Rorγt的表达。结果磁珠分选的小鼠脾脏CD4+CD62L+nave T细胞纯度高于95%。与对照组相比,IL-2处理组细胞数目明显增多,增殖能力明显增强(P0.05),细胞凋亡比例降低(P0.05);IL-2处理组培养上清中IL-17A的浓度明显降低(P0.05),且CD4+IL-17+细胞比例下降,其特异性转录因子Rorγt的表达水平也显著降低(P0.05)。结论 IL-2在CD4+CD62L+T细胞分化为Th17的过程中,能够促进T细胞的增殖并且抑制Th17的分化。     

强直性脊柱炎患者Th17细胞与CD4+CD25+FoxP3+调节性T细胞的变化及意义

目的 探讨强直性脊柱炎( ankylosing spondylitis,AS)患者Th17和CD4+ CD25+ FoxP3+调节性T细胞比例及相关细胞因子水平的变化及意义.方法 强直性脊柱炎患者40例,正常同年龄对照37例.采用流式细胞术检测外周血Th17与调节性T细胞的比例,双抗体夹心酶联免疫吸附法( ELISA)检测血清IL-6、IL-23、IL-17和TGF-β水平.结果 AS组患者外周血Th17细胞比例明显高于对照组[(1.02±0.34)％vs(0.68:±0.29)％,P＜0.05],CD+ CD25+ FoxP3+细胞比例明显低于对照组[(3.77±0.81)％ vs (4.69±1.23)％,P＜0.05].AS患者血清中IL-6、IL-23、IL-17水平明显高于对照组[ (6.15±2.71) ng/L vs(3.31±1.65) ng/L; (9.44±3.12) ng/ml vs (5.82±2.61) ng/ml;( 10.53±4.97) ng/L vs (6.78±3、26) ng/L,P均＜0.01];差异有统计学意义.与对照组相比,AS组TGF-β水平有下降的趋势[(4,76±2.15) ng/ml vs(5.16±2.02) ng/ml,P＞0.05],但差异无统计学意义.AS患者血清各细胞因子含量与临床及实验室指标无相关性.结论 强直性脊柱炎患者Th17与CD4+CD35+FoxP3+调节性T细胞比例失衡,血清IL-6、IL-23、IL-17和TGF-β水平变化,这些原因可能参与强直性脊柱炎免疫发病过程.     

类风湿关节炎患者Th17细胞与调节性T细胞失衡的研究

目的观察类风湿性关节炎（RA）患者外周血Th17细胞与CD4^＋CD25^＋FoxP3^＋调节性T细胞（Treg）平衡状态与疾病的关系,分析Th17／Treg细胞免疫失衡在RA发病机制中的作用。方法采用流式细胞仪四色荧光抗体标记法分别对47例RA患者和39名健康志愿者（HVs）进行CD3、CD8、IL-17与CD4、CD25、F0xP3标记,测定Th17与调节性T细胞的比例变化及相关细胞因子IL-6、IL-23和IL-17水平。结果RA组患者外周血中,CD3^＋CD8^＋IL-17^＋T细胞占CD3^＋T淋巴细胞的百分比为（1．12±0．38）％,明显高于对照组（0．68±0．29）％（t=1．83,P〈0．05）;CD4’CD25’FoxP3^＋细胞占CD4^＋T淋巴细胞的百分比为（2．74±0．71）％,明显低于对照组（4．69±1．23）％（t=-2．94,P〈0．05）。相关细胞因子测定结果：IL-6水平在RA组为（13．5±3．7）ng／L,正常人为（4．6±0．9）ng／L（t=6．24,P〈0．01）;IL-23水平在RA组为（71±19）ng／L,正常人为（25±6）ng／L（t=14．37,P〈0．01）;IL-17水平在RA组为（122±33）ng／L,正常人为（37±9）ng／L（t=19．01,P〈0．01）;RA患者血清IL-6、IL-23和IL-17水平均明显升高。结论RA患者外周血Th17与CD4^＋CD25^＋FoxP3^＋调节性T细胞数量的异常可能是RA发病的重要因素,IL-6和IL-23的升高是引起这些改变的可能原因。     

Naturally Occurring Self-Reactive CD4^＋CD25^＋ Regulatory T Cells： Universal Immune Code

Naturally occurring thymus-arisen CD4^＋CD25^＋ regulatory T （Treg） cells are considered to play a central role in self-tolerance. Precise signals that promote the development of Treg cells remain elusive, but considerable evidence suggests that costimulatory molecules, cytokines, the nature of the TCR and the niche or the context in which the T cell encounters antigen in the thymus play important roles. Analysis of TCR from Treg cells has demonstrated that a large proportion of this population has a higher avidity to self-antigen in comparison with TCR from CD4^＋CD25^＋ cells and that peripheral antigen is required for their development, maintenance, or expansion. Treg cells have been shown to undergo expansion in the periphery, likely regulated by the presence of self-antigen. Many studies have shown that the involvement of Treg cells in the tolerance induction is antigen-specific, even with MHC-mismatched, in transplantation/graft versus host disease （GVHD）, autoimmunity, cancer, and pregnancy. Theses studies concluded a vital role for self-reactive Treg cells in maintenance of the body integrity. Based on those studies, we hypothesize that self-reactive Treg cells are shared among all healthy individuals and recognize same self-antigens and their TCR encodes for few dominant antigens of each organ which defines the healthy self. These dominant self antigens can be regarded as ＂universal immune code＂. Cellular ＆ Molecular Immunology.     

CD4+CD25+ naturally occurring regulatory T cells and not lymphopenia play a role in the pathogenesis of iodide-induced autoimmune thyroiditis in NOD-H2h4 mice

NOD-H2(h4) mice, which express I-A(k) on the NOD background, spontaneously develop autoimmune thyroiditis, a model of Hashimoto thyroiditis in humans, by adding iodide in the drinking water. Parental NOD mice have previously been shown to have intrinsic numerical abnormalities in peripheral lymphocytes and lymphocyte subpopulations such as CD4(+)CD25(+) naturally occurring regulatory T cells (Treg). Therefore we first investigated whether the similar abnormalities exist in NOD-H2(h4) mice. We observed that, compared with other non-autoimmune disease prone BALB/c and C57BL/6 mice, NOD-H2(h4) mice have lower numbers of splenocytes, CD3(+)T, CD4(+)T and CD8(+)T cells but the ratios of Treg to CD4(+)T cells were comparable. Increasing the numbers of peripheral lymphocytes by Complete Freund's Adjuvant immunization or splenocyte transfer did not affect development of thyroiditis, indicating that lymphopenia does not play a critical role in the pathogenesis of thyroiditis. We next examined the significance of Treg by depleting this lymphocyte subset with anti-CD25 antibody. Treg depletion, performed 4days before the administration of NaI water for 8 weeks, significantly exacerbated thyroiditis (p<0.01). Anti-thyroglobulin antibody titers also increased by Treg depletion (p<0.01) without changing the IgG2b to IgG1 ratios. In addition, expression levels of mRNA for IFN-gamma and IL-4 were enhanced in parallel. However, T(4) levels were similar between antibody-treated and untreated groups. Additional anti-CD25 administration at 3 weekly intervals did not influence these results. These data, together with previous studies on other mouse models of inducible thyroiditis and Graves' disease, indicate the role played by Treg in keeping anti-thyroid autoimmune reaction in check in experimental autoimmune thyroid diseases.     

固有CD4+CD25+调节性T细胞与其在移植耐受上的进展

固有CD4 CD25 调节性T细胞(naturally occurringCD4 CD25 regulatory T cells,nTreg)是在胸腺发育的功能成熟的T细胞亚群,可通过下调效应性免疫细胞的功能和增殖来抑制或控制机体免疫应答的程度,并维持机体自身免疫耐受。近年来的研究发现,nTreg对外源性抗原(如移植物同种抗原)也能产生特异性的免疫耐受。该文将就近年来nTreg在细胞标记、作用机制及其在移植耐受方面的研究进展进行综述。     

Role of the T cell receptor alpha chain in the development and phenotype of naturally arising CD4+CD25+ T cells

The T cell receptor alpha chain repertoire and the possible influence of the alpha chain on the development and phenotype of naturally arising mouse CD4+CD25+ T cells have not been extensively analysed. We used all available Valpha-specific monoclonal antibodies and a sensitive multiplex genomic DNA PCR assay to study the Valpha repertoire of CD4+CD25+ T cells in normal mice. To address whether CD4+CD25+ T cells express two TCR alpha chains, we have carried out four-colour flow cytometry using combinations of the available anti-Valpha reagents in mice where one allele of the TCRA locus had been inactivated. Results indicate that the Valpha repertoire of CD4+CD25+ T cells is as diverse as their CD25- partners. In addition, CD4+CD25+ T cells develop normally in Tcralpha+/- mice and we show for the first time that despite expressing only one TCRalpha chain, they retain their characteristic CD4(low), CD3(low), TCRbeta(low), CD5(high), CD45RB(low) and cytoplasmic CD152(high) phenotype.     

支气管哮喘患者外周血Th17、CD4~+CD25~+Treg细胞表达特征

目的:探讨外周血Th17和CD4+CD25+调节性T细胞(Treg)在支气管哮喘患者中的表达特征。方法:41例慢性持续期哮喘患者,分为间歇-轻度组(n=23)和中重度组(n=18),行肺功能检查和哮喘控制问卷(ACQ)调查,20例正常人作为对照。通过流式细胞术检测外周血Th17和CD4+CD25+Treg细胞的比例。ELISA检测血浆以及植物血凝素刺激24小时后外周血单个核细胞(PBMC)上清液中的IL-17、IL-10、TGF-β水平。结果:中重度哮喘组外周血Th17细胞比例及血浆IL-17水平高于间歇-轻度哮喘和正常人组,而外周血CD4+CD25+Foxp3+Treg细胞比例及血浆IL-10、TGF-β水平则降低。中重度哮喘组PBMC上清液中IL-17水平增高。哮喘患者FEV1(%预计值)与Th17细胞及血浆IL-17表达成负相关,与CD4+CD25+Treg表达成正相关。ACQ平均得分与Th17细胞和血浆IL-17表达成正相关,与外周血CD4+CD25+Treg表达成负相关。结论:中重度哮喘中外周血Th17细胞应答增强,而CD4+CD25+Treg细胞缺乏,哮喘的严重程度及症状控制与外周血Th17/Treg免疫应答失衡密切相关。     

Chemokines,chemokine receptors and CD4+CD25+ regulatory T cells

The fields of regulatory T (Treg) cells and chemokines/chemokine receptors have progressed rapidly in the last few years. Treg cells, especially CD4⁺CD25⁺ Treg cells, play a critical role in maintaining self-tolerance and immune homeostasis. Chemokines and chemokine receptors are crucial for lymphoid development, homing and immunological regulation. This review will discuss the biological effects of chemokines and chemokine receptors on regulating the migration and development of CD4⁺CD25⁺ Treg cells, and the potential clinical implications of these findings when considering chemokine receptors as therapeutic targets.     

CD4+CD25+免疫调节性T细胞对CD4+T细胞介导的移植物抗宿主病预防作用的研究

目的研究CD4+CD25+免疫调节性T(Treg)细胞在小鼠骨髓移植后,对移植物抗宿主病的预防作用及其作用机制.方法用C3H(H-2k)小鼠骨髓作为供体,提取C3H(H-2k)小鼠CD4+T及CD4+CD25+T细胞,C3H×B6(H-2k/b)F1小鼠为骨髓移植的受者.在受者接受致死量全身放射后,输注供者去除T细胞的骨髓(ATBM),使其造血功能重建(ATBM组).于不同的实验组给予CD4+(CD4组)T细胞,CD4+CD25+T(CD25组)或二者同时输注(CD4/CD25组).观察各组小鼠移植物抗宿主病(GVHD)的发生率.结果所有10只ATBM组小鼠至骨髓移植后60天仍全部存活,无GVHD发生;所有10只CD4组小鼠在骨髓移植10天内全部死于GVHD(P＜0.01);所有5只CD25组小鼠于骨髓移植后60天仍全部存活,无明显GVHD发生(P＞0.05);同样,所有6只CD4/CD25组小鼠至骨髓移植后仍全部存活,无明显GVHD发生(P＞0.05).结论在同种异基因小鼠的骨髓移植模型中,CD4+CD25+T不诱导GVHD的发生,并有预防CD4+T细胞介导的GVHD发生的作用.     

Characterization of CD4+CD25+ natural regulatory T cells in the inflammatory infiltrate of human chronic periodontitis

Periodontitis is an infectious disease, where putative periodontopathogens trigger chronic inflammatory and immune responses against periodontal structures, in which an unbalanced host response is also determinant to the disease outcome. It is reasonable to assume that patient susceptibility to periodontal tissue destruction could be determined by the balance between the response against periodontopathogens and regulatory mechanisms of these events mediated by suppressive T cells. In the present study, we identified and characterized natural regulatory T cells (Tregs) in the inflammatory infiltrate of human chronic periodontitis (CP) with emphasis on phenotypic analyses that were carried out to address the participation of Tregs in CP. Results showed that patients with CP presented increased frequency of T lymphocytes and CD4+CD25+ T cells in the inflammatory infiltrate of gingival tissues. These cells exhibited the phenotypic markers of Tregs such as forkhead box p3 (Foxp3), CTLA-4, glucocorticoid-inducible TNFR, CD103, and CD45RO and seemed to be attracted to the inflammation site by the chemokines CCL17 and CCL22, as their expression and its receptor CCR4 were increased in CP patients. Moreover, besides the increased detection of Foxp3 mRNA, diseased tissues presented high expression of the regulatory cytokines IL-10 and TGF-beta. In addition, the inflammatory infiltrate in CP biopsies was composed of CD25+Foxp3+ and CD25+TGF-beta+ cells, thus corroborating the hypothesis of the involvement of Tregs in the pathogenesis of CP. Finally, these results indicate that Tregs are found in the chronic lesions and must be involved in the modulation of local immune response in CP patients.