Toll-like receptors and immune regulation: their direct and indirect modulation on regulatory CD4+ CD25+ T cells

Regulatory CD4(+) CD25(+) T (Treg) cells with the ability to suppress host immune responses against self- or non-self antigens play important roles in the processes of autoimmunity, transplant rejection, infectious diseases and cancers. The proper regulation of CD4(+) CD25(+) Treg cells is thus critical for optimal immune responses. Toll-like receptor (TLR)-mediated recognition of specific structures of invading pathogens initiates innate as well as adaptive immune responses via antigen-presenting cells (APCs). Interestingly, new evidence suggests that TLR signalling may directly or indirectly regulate the immunosuppressive function of CD4(+) CD25(+) Treg cells in immune responses. TLR signalling may shift the balance between CD4(+) T-helper cells and Treg cells, and subsequently influence the outcome of the immune response. This immunomodulation pathway may therefore have potential applications in the treatment of graft rejection, autoimmune diseases, infection diseases and cancers.     

CD4+CD25+调节性T细胞在自身免疫病中作用的研究进展

CD4 CD25 调节性T细胞具有独特的免疫抑制功能,通过细胞接触和细胞因子机制抑制自身反应性T细胞的活化与增殖,在自身免疫病中发挥着重要作用。通过研究CD4 CD25 调节性T细胞在自身免疫病中的作用,将会揭示这类疾病的发病机制,从而为治疗自身免疫病提供一个新途径。     

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.     

Induction and maintenance of self tolerance: the role of CD4+CD25+ regulatory T cells

The immune system responds vigorously to invading pathogens (non-self, foreign), while remaining unresponsive (tolerant) to the body's own components and circulating constituents (self). This indifference to self components is a result of finely orchestrated events of thymic negative selection (central tolerance) of developing T cells that are autoaggressive combined with those operative in the periphery (peripheral tolerance) to control the activity of potentially autoreactive T cells that escaped thymic tolerance. Recently, autoimmune regulator expressed in the thymus has been identified as a critical mediator of central tolerance towards tissue-specific antigens. In the periphery, a variety of regulatory T cells are involved in effecting tolerance. There is immense interest and excitement about the newly identified subset of CD4(+)CD25(+) T cells. This is a unique subset of CD4(+) T cells that bear CD25 (IL-2Ralpha chain) on the cell surface in the na?ve state and express FoxP3 as a unique marker. These cells suppress the activity of autoreactive effector T cells primarily via cell-cell contact. The deficiency and/or altered function of CD4(+)CD25(+) T cells is associated with autoimmunity. Mice deficient in FoxP3 (scurfy mice) bear an autoimmune phenotype, and human males with mutations in the corresponding gene express the phenotype of wide-spread autoimmunity, the immune dysregulation, polyendocrinopathy and enteropathy, and X-linked syndrome. In vitro expansion of antigen-specific CD4(+)CD25(+) T cells and their adoptive transfer into patients suffering from autoimmunity is emerging as a promising new therapeutic approach for these debilitating disorders.     

Regulatory CD4+CD25+ T-cells are Controlled by Multiple Pathways at Multiple Levels

CD4⁺CD25⁺ regulatory T-cells (Treg cells) are an important subset of T-cells that functions to negatively control immune responses to self or non-self antigens. Depletion of CD4⁺CD25⁺ Treg cells leads to the occurrence of lymphoproliferative autoimmune diseases in animals and humans. Therefore, CD4⁺CD25⁺ Treg cells must be tightly regulated in the physiologic situation. In this article, we try to summarize the regulating pathways of the development, survival, and function of CD4⁺CD25⁺ Treg cells at multiple levels and multiple pathways, including the dendritic cells, costimulatory signals, cytokines, as well as intracellular signals.     

天然CD4+CD25+Treg细胞的研究进展

天然CD4+ CD25+ Treg细胞在针对自身抗原和外来抗原的免疫应答中起关键控制作用,其缺乏或功能性的缺陷将导致多重病理性的失调.本文就近年在其产生、作用机制以及与免疫耐受的诱导关系等方面的研究进展进行了综述.     

Increase of circulating CD4+CD25+ T cells in myasthenia gravis patients with stability and thymectomy

BACKGROUND: CD4(+)CD25(+) regulatory T cells are key controllers of peripheral immunological self-tolerance and suppress various autoimmune diseases in animal models, but few studies have been done to define their roles in myasthenia gravis (MG) so far. OBJECTIVE: To investigate frequencies and dynamic changes of blood CD4(+)CD25(+) T cells from MG patients. METHODS: The peripheral blood CD4(+)CD25(+) T cells of 29 MG patients and 23 healthy controls were detected by three-color flow cytometry. RESULTS: Myasthenic patients with symptomatically uncontrollable disease showed slightly lower percentages of CD4(+)CD25(+) T cells (mean = 3.79 +/- 1.40%; P = 0.12), whereas MG patients with clinically stable disease had significantly increased CD4(+)CD25(+) T cells (mean = 8.45 +/- 1.96%, P = 0.0001), as compared with healthy controls (mean = 4.53 +/- 0.96%). In addition, thymectomized MG patients had significantly higher percentages of CD4(+)CD25(+) T cells (mean = 8.44 +/- 2.39%), as compared with both non-thymectomized MG patients (mean = 5.88 +/- 2.89%, P = 0.038) and healthy controls (P = 0.003). CONCLUSIONS: Our observations indicate that increased percentages of CD4(+)CD25(+) T cells in MG patients may be related to disease stability and that thymectomy in patients with MG resulted in augmented CD4(+)CD25(+) T cells.     

CD4+CD25+ T regulatory cells inhibit cytotoxic activity of T CD8+ and NK lymphocytes in the direct cell-to-cell interaction

There are reports suggesting an influence of CD4(+)CD25(+) T regulatory cells (Treg) on cytotoxic lymphocytes. The aim of the study was to evaluate such an influence. Cytotoxic activity was examined in the cultures of peripheral blood mononuclear cells (PBMC) as well as in the cultures of separate T CD8(+) or NK cells mixed with Treg and other subpopulations of PBMC. We found that the production of IFNgamma, perforin and cytotoxic activity of T CD8(+) or NK cells were decreased in the presence of Treg, however, the percentage of conjugates formed by cytotoxic cells with target cells during cytotoxic reaction was decreased only in the cultures of T CD8(+) cells. Inhibition of the cytotoxic reactions in the presence of Treg cells was found to be associated with the generation of conglomerates formed by CD4(+)CD25(+) and the cytotoxic cells, as observed under the fluorescence microscope. Treg produced IL10 when mixed with the cytotoxic lymphocytes, however, an addition of anti-IL10 mAb into the cultures did not affect the results. It is concluded that Treg were able to inhibit both T CD8+ and NK lymphocyte cytotoxic activities in a direct cell-to-cell interaction. Treg decreased the number of T CD8+ cells attached to the target cells, while the mechanism underlying a decrease in NK cytotoxicity remained unclear.     

Age-related changes in the occurrence and characteristics of thymic CD4(+) CD25(+) T cells in mice

Natural regulatory CD4(+) CD25(+) T cells play an important role in preventing autoimmunity by maintaining self-tolerance. They express CD25 constitutively and are produced in the thymus as a functionally mature T-cell population. Changes in the potential of these cells to regulate the activity of conventional effector lymphocytes may contribute to an increased susceptibility to infection, cancer and age-associated autoimmune diseases. In this study we demonstrated that the thymi of aged mice are populated by a higher percentage of CD4(+) CD25(+) thymocytes than in young animals. The expression of several surface markers (CD69, CD5, CD28, CTLA-4, CD122, FOXP3), usually used to characterize the phenotype of CD4(+) CD25(+) T regulatory cells, was compared between young and aged mice. We also examined the ability of sorted thymus-deriving regulatory T cells of young and aged BALB/c mice to inhibit the proliferation of lymph node lymphocytes activated in vitro. Natural regulatory T cells isolated from the thymi of young mice suppress the proliferation of responder lymph node cells. We demonstrated that thymus-deriving CD4(+) CD25(+) T cells of old mice maintain their potential to suppress the proliferation of activated responder lymphocytes of young mice. However, their potential to inhibit the proliferation of old responder T cells is abrogated. Differences in the occurrence and activity of CD4(+) CD25(+) thymocytes between young and old animals are discussed in relation to the expression of these surface markers.     

肺炎支原体感染患儿外周血CD4+CD25+调节性T细胞的变化及其临床意义

探讨肺炎支原体(MP)感染患儿外周血CD4+ CD25+调节性T细胞(Treg)频率变化及其意义.选取32例肺炎支原体感染患儿,其中肺炎支原体肺炎18例,肺炎支原体肺炎合并肺外症状14例;26名健康儿童,分离其外周血单个核细胞,以CD4、CD25单克隆抗体标记细胞后,用流式细胞仪(FACS)检测Treg细胞频率.FAC...     

Circulating CD4+CD25+ T Regulatory Cells Are Not Altered in Multiple Sclerosis and Unaffected by Disease-Modulating Drugs

Experimental animal models for autoimmunity have demonstrated the existence and crucial role of CD4(+)CD25(+) T regulatory (Tr) cells in suppressing autoreactive T cells and promoting peripheral tolerance. Recent in vitro functional studies showed that Tr cells are enriched in the CD25(high) cell population among CD4(+) T cells, and that they totally inhibit proliferation and cytokine secretion by CD4(+) T cells. It is not yet known if circulating Tr cells are involved in multiple sclerosis (MS). This study was done firstly to determine whether alterations of the CD4 (+) CD25(high) T cells occur in MS, examining their frequencies. As it was reported that the suppressive activity of CD4(+)CD25(+) Tr cells is mainly through cell surface contact pathway, we secondly analyzed the expression of the functionally important cell surface molecules of CD4(+)CD25(high) Tr cells. Two- or three-colour flow cytometry was used to identify and quantify CD4(+)CD25(+) Tr cells and CD4(+)CD25(high) Tr cells among blood CD4(+) T cells in MS patients without treatment vs. patients treated with either interferon-beta (IFN-beta) or glatiramer acetate (GA) or IFN-beta + GA in combination vs. healthy controls (HC). Expression of functionally important surface molecules CD45RO, CD69, CD95, HLA-DR, and intracellular CTLA-4 and IL-10 production by CD4(+)CD25(high) Tr cells were investigated. CD4(+)CD25(+) T cells constituted around 6% of CD4(+)T cells in all MS patient groups, and 7% in HC. There were also no changes in the proportions of CD4(+)CD25(+) Tr cells and CD4(+)CD25(high) Tr cells in a longitudinal follow-up of MS patients before and during IFN-beta treatment. Frequencies of circulating CD4(+)CD25(high)Tr cells among CD4(+) T cells were also similar and their surface or intracellular molecular expression did not vary in MS patients, irrespective of treatment, compared to HC. This study suggests that levels of circulating CD4(+)CD25(+) Tr cells and CD4(+)CD25(high) Tr cells are not altered in MS, and are unaffected by substances currently used to modulate the disease.     

CD4+CD25+调节性T细胞对B细胞免疫应答的抑制作用

CD4 CD25 调节性T细胞(CD4 CD25 Treg细胞)主要来源于胸腺,在体内外抑制CD4 或CD8 T细胞的活化及增殖,是维持自身免疫耐受的重要机制之一。近来研究发现该调节性T细胞除了能够抑制T细胞的免疫应答外,还能够抑制B细胞免疫应答,包括抑制B细胞活化和抗体生成,从而抑制主要由抗体介导的自身免疫性疾病的发生。     

IL-10 is involved in the suppression of experimental autoimmune encephalomyelitis by CD25+CD4+ regulatory T cells

CD25(+)CD4(+) regulatory T cells inhibit the activation of autoreactive T cells in vitro and in vivo, and suppress organ-specific autoimmune diseases. The mechanism of CD25(+)CD4(+) T cells in the regulation of experimental autoimmune encephalomyelitis (EAE) is poorly understood. To assess the role of CD25(+)CD4(+) T cells in EAE, SJL mice were immunized with myelin proteolipid protein (PLP)(139-151) to develop EAE and were treated with anti-CD25 mAb. Treatment with anti-CD25 antibody following immunization resulted in a significant enhancement of EAE disease severity and mortality. There was increased inflammation in the central nervous system (CNS) of anti-CD25 mAb-treated mice. Anti-CD25 antibody treatment caused a decrease in the percentage of CD25(+)CD4(+) T cells in blood, peripheral lymph node (LN) and spleen associated with increased production of IFN-gamma and a decrease in IL-10 production by LN cells stimulated with PLP(130-151) in vitro. In addition, transfer of CD25(+)CD4(+) regulatory T cells from naive SJL mice decreased the severity of active EAE. In vitro, anti-CD3-stimulated CD25(+)CD4(+) T cells from naive SJL mice secreted IL-10 and IL-10 soluble receptor (sR) partially reversed the in vitro suppressive activity of CD25(+)CD4(+) T cells. CD25(+)CD4(+) T cells from IL-10-deficient mice were unable to suppress active EAE. These findings demonstrate that CD25(+)CD4(+) T cells suppress pathogenic autoreactive T cells in actively induced EAE and suggest they may play an important natural regulatory function in controlling CNS autoimmune disease through a mechanism that involves IL-10.     

Phenotypic characterization of regulatory CD4+CD25+ T cells in rats

CD25 has become widely used as a marker for a subset of regulatory CD4(+) T cells present in the thymus and periphery of mice, rats and humans. However, CD25 is also expressed on conventionally activated T cells that are not regulatory and not all peripheral regulatory T cells express CD25. The identification of a stable and unique marker for regulatory T cells would therefore be valuable. This study provides a detailed account of the phenotype of CD4(+)CD25(+) regulatory T cells in rats. In the thymus, CD4(+)CD8(-)CD25(+) cells were found to have a more mature phenotype than the corresponding CD4(+)CD8(-)CD25(-) cells with respect to expression of Thy1 (CD90), CD53 and CD44, suggesting that CD25 expression, and perhaps commitment to regulatory function, might be a late event in thymocyte development. CD4(+)CD25(+) cells in both the thymus and periphery were found to have enriched and heterogeneous expression of activation markers such as OX40 (CD134) and OX48 (an antibody determined in this study to be specific for CD86). CD4(+)CD25(+) T cells were also found to have enriched expression of CD80, at both the mRNA and protein level. However, functional studies in vitro and in vivo showed that neither OX40 or CD86 were useful markers for the further subdivision of regulatory T cells. Our studies indicate that, at present, CD25 remains the most useful marker to enrich for regulatory CD4(+) T cells in rats and no further subdivision of the regulatory component of CD4(+)CD25(-)CD45RC(low) T cells has yet been achieved.     

CD4+CD25+调节性T细胞及血小板参数在重症肺炎患者中表达的意义

目的 探讨CD4+ CD25+调节性T细胞及血小板参数在重症肺炎患者中表达的意义.方法 收集2013年5月至2015年10月我院诊断为肺炎的患者,共计80例,进一步分为重症肺炎组28例和肺炎组52例.对照组为同期健康体检者,共50例.对比重症肺炎组、肺炎组和对照组入院时CD4+ CD25+调节性T细胞及血小板参数水平,并且分析重症肺炎组死亡患者与存活患者入院时CD4+ CD25+调节性T细胞及血小板参数水平.结果 ①重症肺炎组、肺炎组和对照组入院时CD4+ CD25+调节性T细胞水平、MPV及PLT结果比较有差异(P＜0.05);重症肺炎组、肺炎组和对照组入院时PDW、PCT结果比较无差异(P＞0.05).②重症肺炎组死亡患者与存活患者入院时CD4+ CD25+调节性T细胞水平、MPV及PLT结果比较有差异(P＜0.05);重症肺炎组死亡患者与存活患者入院时PDW、PCT结果比较无差异(P＞0.05).结论 CD4+ CD25+调节性T细胞、MPV及PLT可作为反应肺炎严重程度的敏感指标,并且可作为评价重症肺炎患者预后的客观指标.     

晚期肺癌患者血CD4+CD25+调节T细胞水平的变化

为探讨晚期肺癌患者CD 4CD 25去调节T细胞水平的变化及其与其它T细胞亚群和NK细胞的相互关系,对86例肺癌组患者和64名对照组测定和比较CD 4CD 25调节T细胞、T细胞亚群(CD 3、CD 4、CD 8、CD 8CD 28)和NK细胞的水平,探讨其临床意义.CD 4CD 25细胞和T细胞亚群均用流式细胞仪检测.结果表明,晚期肺癌患者血CD 4CD 25细胞明显高于对照组(18.4%±6.2%vs7.1%±0.4%,P<0.01),CD 4细胞、CD 8CD 28细胞和NK细胞明显低于对照组(32.4%±8.7%vs44.9%±8.4%,P<0.01;7.4%±3.5%vs16.5%±2.7%,P<0.01;10.2%±4.1%vs18.5%±7.2%,P<0.01),CD 8细胞明显高于对照组(36.7%±7.5%vs31.8%±5.1%,P<0.01).CD 4CD 25细胞与CD 8CD 28细胞、NK细胞呈明显负相关.表明CD 4CD 25细胞增多是晚期肺癌患者免疫功能紊乱的一个证据.     

CD4+CD25+ T regulatory cells inhibit cytotoxic activity of CTL and NK cells in humans-impact of immunosenescence

We hypothesized that advanced age and medical conditions had an impact on the accumulation of CD4+CD25+ T regulatory cells (Treg), which in turn could deteriorate cytotoxic activity of CD8+ T and NK cells. Volunteers were divided according to the Senieur Protocol into healthy young and elderly and non-healthy young and elderly subjects. The numbers of Treg cells in peripheral blood, their influence on CD8+ T and NK cells and production of IL2 as well as apoptosis intensity of Treg cells were measured. The number of Treg cells was higher in both elderly groups than in respective young ones. Compared to healthy subjects, those with medical conditions were revealed to have higher numbers of Treg cells. In addition, the highest accumulation of Treg cells in non-healthy elderly could be a result of their resistance to undergo apoptosis. The frequency of Treg cells correlated inversely with the activity of autologous cytotoxic cells in PBMC and production of IL2 by autologous CD4+CD25- Th cells. Thus, these parameters were the most highly decreased in non-healthy subjects, notably in the elderly. However, these parameters improved in the cultures of pure sorted cells. The only subset capable of decreasing them to the levels noted in PBMC when added back was Treg cells, which proved the link between the number of Treg cells, cytotoxic activity and production of IL2. Concluding, we found that Treg accumulated as a result of ageing and/or medical conditions were capable of decreasing cytotoxic activity of CD8+ T and NK cells and production of IL2.     

CD4+CD25+调节性T细胞的发育与胸腺CD4-CD25+细胞关联性的探讨

目的:探讨CD4 CD25 调节性T细胞(CD4 CD25 regulatoryTcells,CD4 CD25 Tr)的发育及其与胸腺CD4-CD25 细胞的关系。方法:以流式细胞术检测小鼠从出生至发育成熟过程中,胸腺、脾脏、淋巴结和外周血中CD4 CD25 Tr比例变化,以及胸腺CD4-CD25 细胞比例变化;通过磁激活细胞分选(MACS)从小鼠淋巴结纯化CD4 CD25 T和CD4 CD25-T细胞,经CFDA-SE标记,以多种刺激形式诱导增殖。结果:小鼠出生1d到10周的发育过程中,胸腺CD4 CD25 Tr比例一直比较恒定,但在脾脏、淋巴结和外周血,随鼠龄增加而不断升高,从1d龄到1周时升高最迅速,其后的升高速度逐渐减慢,10周龄时达平台期。胸腺中CD4-CD25 细胞在出生1d的小鼠比例非常高,1d龄到1周龄期间迅速下降,10周龄时达平台期。ConA不能诱导CD4 CD25 Tr和CD4 CD25-T细胞增殖,但CD4 CD25 Tr出现一过性细胞增大;佛波醇酯加离子霉素能诱导CD4 CD25 Tr和CD4 CD25-T细胞增殖;包被的抗CD3抗体加可溶性抗CD28抗体能刺激CD4 CD25-T细胞增殖,但CD4 CD25 Tr不增殖,加入高浓度IL-2,CD4 CD25-T细胞增殖更强,CD4 CD25 Tr出现增殖。结论:胸腺CD4-CD25 细胞很有可能是CD4 CD25 Tr的前体。     

The different effects of indirubin on effector and CD4+CD25+ regulatory T cells in mice: potential implication for the treatment of autoimmune diseases

CD4(+)CD25(+) regulatory T (Treg) cells play an essential role in the induction and maintenance of peripheral self-tolerance. Indirubin, a traditional Chinese medicine, was clinically used in the treatment of chronic myelocytic leukemia as well as some autoimmune diseases, including Alzheimer's disease, diabetes, and so on. The effects of indirubin on CD4(+)CD25(+)Treg cells, which play a critical role in controlling autoimmunity, have not been addressed. In the present study, we observed the cell levels, phenotypes, and immunoregulatory function of CD4(+)CD25(+)Treg cells in indirubin-treated mice. Treatment with indirubin significantly enhanced the ratios of CD4(+)CD25(+)Treg cells or CD4(+)CD25(+)Foxp3(+)Treg cells to CD4(+)T cells in peripheral blood, lymph nodes, and spleens (P < 0.01 compared with control mice). CD4(+)CD25(+)Foxp3(+)Treg cells to CD4 single positive cells in the thymi of indirubin-treated mice were significantly higher than those in control mice. Furthermore, splenic CD4(+)CD25(+)Treg cells in indirubin-treated mice showed immunosuppressive ability on the immune response of T effector cells to alloantigens or mitogen as efficiently as the control CD4(+)CD25(+)Treg cells in vitro. The present studies indicate that CD4(+)CD25(+)Treg cells are more resistant to indirubin than effector T cells in vivo. The selectively enhanced CD4(+)CD25(+)Treg cell levels by indirubin made host to be more favorable for immune tolerance induction, which opened one possibility for indirubin to treat autoimmune diseases.