Inverse correlation between CD4+ regulatory T-cell population and autoantibody levels in paediatric patients with systemic lupus erythematosus

CD4(+) CD25(+) regulatory T cells (Tregs) are critical in maintaining self-tolerance and preventing organ-specific autoimmunity. Their role in paediatric systemic lupus erythematosus (SLE), an autoimmune disease characterized by inappropriate regulation of hyperactivated B and T cells, has not been clearly defined. Using flow cytometry to determine cell populations and real-time polymerase chain reaction to assay mRNA expression for FOXP3, CTLA-4, and GITR, we characterized CD4(+) CD25(+) T cells in paediatric SLE patients and healthy subjects. The frequency of CD4(+) CD25(+) Tregs was significantly decreased in patients with active SLE compared with patients with inactive SLE and with controls (7.27% +/- 2.50%, 9.59% +/- 2.80% and 9.78% +/- 2.11%, respectively; P = 0.027 and P < 0.001, respectively), and was inversely correlated with disease activity, as assessed with the Systemic Lupus Erythematosus Disease Activity Index 2000 scores (r = -0.59, P = 0.001) and serum anti-double-stranded DNA levels (r = -0.65, P < 0.001). Our preliminary investigations found elevated surface expression of GITR in CD4(+) CD25(+) T cells, elevated mRNA expression of CTLA-4 in CD4(+) T cells and higher amounts of mRNA expression for FOXP3 in CD4(+) cells in patients with active SLE compared with patients with inactive disease and controls. We demonstrated reduced CD4(+) CD25(+) Treg levels were inversely correlated with disease activity, indicating a defective Treg population in paediatric SLE patients. The differences in the expression of FOXP3, CTLA-4 and GITR imply the possible role of CD4(+) Tregs in the pathogenesis of SLE.     

Effects of interleukin 4 on CD25+CD4+ regulatory T cell function

CD25+CD4+ regulatory T cells (Tregs) contribute to the maintenance of peripheral tolerance against self and non-self. The modulatory effects of cytokines, such as interleukin 4 (IL-4) on the function of Tregs have not been explored in detail. We here report that IL-4 prevents spontaneous apoptosis and the decline of foxp3 mRNA which were found to occur during culture of isolated Tregs. Tregs exposed to IL-4 were more potent in suppressing the proliferation of na?ve CD4+ T cells and they better inhibited IFN-gamma production by CD4+ T cells as compared to Tregs cultured in medium. IL-4 also enhanced membrane IL-2Ralpha (CD25) expression on Tregs above the levels observed on freshly isolated cells. IL-4-mediated effects on Treg function persisted in Tregs from Stat6-/- mice, pointing to a Stat6-independent intracellular transduction pathway. In conclusion, our data suggest that the anti-inflammatory function of IL-4 could partly be mediated by effects on Tregs function.     

Deficient SOCS3 expression in CD4+CD25+FoxP3+ regulatory T cells and SOCS3-mediated suppression of Treg function

Naturally occurring CD4+CD25+FoxP3+ regulatory T cells (Treg) suppress T helper (Th) cell-mediated immune responses. The cytokines IL-2 and IL-6 are known to influence Treg function. However, their relative effects on Th cells versus Treg are not well understood. Stimulation with IL-2, and to a lesser extent, IL-6, enhanced Treg proliferation, FoxP3 and CTLA4 maintenance, and suppressive function. In contrast, when IL-2 or IL-6 were added to Treg/Th cell cocultures, suppression was inhibited. The molecule SOCS3 negatively regulates responses to IL-2 and IL-6. Interestingly, unlike Th cells, Treg were found to be deficient in SOCS3 protein expression. The significance of this finding lies in the need for Treg to rapidly respond to these cytokines to prevent unwarranted immune responses to self-antigens. Overexpression of SOCS3 in Treg decreased their proliferation, FoxP3 and CTLA-4 expression and suppressive function. Thus, up-regulation of SOCS3 expression may be a useful therapeutic approach in diseases where inhibition of Treg is desirable.     

Phenotypic and functional characteristics of CD4+ CD39+ FOXP3+ and CD4+ CD39+ FOXP3neg T-cell subsets in cancer patients

Human CD4(+) CD39(+) regulatory T (Treg) cells hydrolyze exogenous adenosine triphosphate (ATP) and participate in immunosuppressive adenosine production. They contain two T-cell subsets whose role in mediating suppression is not understood. Frequencies of both CD4(+) CD39(+) subsets were evaluated in peripheral blood lymphocytes of 57 cancer patients and in tumor infiltrating lymphocytes (TILs) of 6 patients. CD4(+) CD39(+) and CD4(+) CD39(neg) T cells isolated using immunobeads and cell sorting were cultured under various conditions. Their conversion into CD39(+) FOXP3(+) CD25(+) or CD39(+) FOX(neg) CD25(neg) cells was monitored by multiparameter flow cytometry. Hydrolysis of exogenous ATP was measured in luminescence assays. Two CD4(+) CD39(+) cell subsets differing in expression of CD25, FOXP3, CTLA-4, CD121a, PD-1, latency associated peptide (LAP), glycoprotein A repetitions predominant (GARP), and the cytokine profile accumulated with equal frequencies in the blood and tumor tissues of cancer patients. The frequency of both subsets was significantly increased in cancer. CD39 expression levels correlated with the subsets' ability to hydrolyze ATP. Conventional CD4(+) CD39(neg) T cells incubated with IL-2 + TGF-β expanded to generate CD4(+) CD39(+) FOXP3(+) Treg cells, while CD4(+) CD39(+) FOXP3(neg) CD25(neg) subset cells stimulated via the TCR and IL-2 converted to FOXP3(+) CTLA4(+) CD25(+) TGF-β-expressing Treg cells. Among CD4(+) CD39(+) Treg cells, the CD4(+) CD39(+) FOXP3(neg) CD25(neg) subset serves as a reservoir of cells able to convert to Treg cells upon activation by environmental signals.     

Natural Tregs, CD4+CD25+ inhibitory hybridomas, and their cell contact dependent suppression

The natural CD4+CD25+ T regulatory (Treg) lymphocyte has emerged as a critical cell for controlling immune responses to self, foreign proteins, and pathogens. Identified initially by the constitutive expression of CD4 and CD25, natural Tregs suppress a variety of immune cells and responses, including CD4+CD25− proliferation and IL-2 production, and CD8 cell proliferation, IFNγ production and CTL activity. Although natural Tregs require activation with specific antigen to attain their suppressive phenotype, once activated they execute inhibition in an antigen specific as well as non-specific (bystander) fashion. Treg suppression depends on IL-2, CD25, and cell:cell contact. The use of live cell imaging in vivo and in vitro to visualize the dynamic cell:cell interactions involving natural Tregs as well as the CD4+CD25+ Treg inhibitory hybridoma RD6 has refined the mechanistic models of contact dependent Treg suppression.     

Pertussis toxin as an adjuvant suppresses the number and function of CD4+CD25+ T regulatory cells

We observed a remarkable reduction in the frequency and immunosuppressive activity of splenic CD4+CD25+ T cells in C57BL/6 mice with MOG33-55-induced experimental autoimmune encephalomyelitis (EAE). Our study revealed that pertussis toxin (PTx), one component of the immunogen used to induce murine EAE, was responsible for down-regulating splenic CD4+CD25+ cells. Treatment of normal BALB/c mice with PTx in vivo reduced the frequency, suppressive activity and FoxP3 expression by splenic CD4+CD25+ T cells. However, PTx treatment did not alter the expression of characteristic phenotypic markers (CD45RB, CD103, GITR and CTLA-4) and did not increase the expression of CD44 and CD69 by the residual splenic and lymph node CD4+CD25+ T cells. This property of PTx was attributable to its ADP-ribosyltransferase activity. PTx did not inhibit suppressive activity of purified CD4+CD25+ T regulatory (Treg) cells in vitro, but did so in vivo, presumably due to an indirect effect. Although the exact molecular target of PTx that reduces Treg activity remains to be defined, our data suggests that alteration of both distribution and function of splenic immunocytes should play a role. This study concludes that an underlying cause for the immunological adjuvanticity of PTx is down-regulation of Treg cell number and function.     

Combined CD4+ Donor Lymphocyte Infusion and Low-Dose Recombinant IL-2 Expand FOXP3+ Regulatory T Cells following Allogeneic Hematopoietic Stem Cell Transplantation

CD4⁺CD25⁺FOXP3⁺ regulatory T cells (Treg) successfully control graft-versus-host-disease (GVHD) in animal models. In humans, incomplete reconstitution of Treg after allogeneic hematopoietic stem cell transplantation (HSCT) has been associated with chronic GVHD (cGVHD). Recent studies have demonstrated that interleukin (IL)-2 infusions expand Treg in vivo. However, the effectiveness of this therapy depends on the number of cells capable of responding to IL-2. We examined the effect of low-dose IL-2 infusions on Treg populations after HSCT in patients who also received infusions of donor CD4⁺ lymphocytes. Utilizing FOXP3 as a Treg marker, we found that patients who received CD4+DLI concomitantly with IL-2 had greater expansion of Treg compared to patients who received IL-2 (P = .03) or CD4⁺DLI alone (P = .001). FOXP3 expression correlated with absolute CD4⁺CD25⁺ cell counts. Moreover, expanded CD4⁺CD25⁺ T cells displayed normal suppressive function and treatment with CD4⁺DLI and IL-2 was not associated with GVHD. This study suggests that administration of low-dose IL-2 combined with adoptive CD4⁺ cellular therapy may provide a mechanism to expand Treg in vivo.     

慢性乙肝患者外周血CD4CD25FOXP3 Tregs及HBV抗原特异性CTLs的检测和分析

目的: 检测慢性乙肝(CHB)患者外周血中CD4⁺CD25⁺FOXP3⁺调节性T淋巴细胞(Treg细胞)和乙肝病毒(HBV)特异性细胞毒性T淋巴细胞(CTLs)的表达及意义。方法: 收集28例CHB患者和15例健康人外周血单个核细胞标本,运用流式细胞仪对Treg细胞亚群进行定量分析,同时采用酶联免疫斑点法检测HBV抗原特异性CTLs,并结合丙氨酸氨基转移酶(ALT)和 HBV DNA的临床情况进行分析。结果: CHB组CD4⁺CD25⁺FOXP3⁺ Treg细胞的频率显著高于健康对照组 (3.14%±0.97% vs 1.95%±0.68%,P＜0.05);HBV抗原特异性CTL斑点计数为阳性(19.28±3.85)。CHB组Treg的频率与乙肝病毒载量呈正相关(r=0.831, P＜0.01),与HBV特异性CTL斑点计数值呈负相关(r＝-0.540,P＜0.01)。结论: CHB患者外周血CD4⁺CD25⁺FOXP3^＋Treg细胞表达升高并与病毒载量相关,而与HBV反应的CTLs数量呈负相关,提示Treg细胞可通过抑制细胞免疫反应影响病毒清除。     

卵巢癌细胞培养上清诱导CD4+CD25-T细胞分化为CD4+CD25+调节性T细胞

目的研究卵巢癌细胞培养上清液是否能诱导外周血CD4^＋CD25^- T细胞转变为CD4^＋CD25^＋调节性T细胞。方法将外周血CD4^＋CD25^- T细胞分离后，对照组用CD3和CD28单抗活化，实验组在对照基础上加用卵巢癌细胞株SKOV3培养上清，72h后分离各组的CD25^＋和CD25^-T细胞，溴化脱氧尿嘧啶掺入标记法测定增殖能力及对静息的自体同源CD4^＋CD25^- T细胞的增殖抑制能力，流式细胞仪测定细胞糖皮质激素诱发型TNF受体（glucocorticoid-induced TNFR,GITR）与CTLA-4分子的表达，RT-PCR检测细胞卿mRNA的表达。结果与对照组相反，实验组的CD4^＋CD25^＋T细胞具有免疫抑制功能，自身增殖能力下降，GITR和CTLA-4分子的表达和CD4^＋CD25^＋调节性T细胞相似，并被诱导表达转录因子Foxp3 mRNA。结论卵巢癌细胞分泌的可溶性物质能诱导外周血CD4^＋CD25^-T细胞转化为CD4^＋CD25^＋调节性T细胞。     

Compromised CD4+ CD25(high) regulatory T-cell function in patients with relapsing-remitting multiple sclerosis is correlated with a reduced frequency of FOXP3-positive cells and reduced FOXP3 expression at the single-cell level

CD4+ CD25(high) regulatory T cells (Tregs) of patients with relapsing-remitting (RR) multiple sclerosis (MS), in contrast to those of patients with secondary progressive (SP) MS, show a reduced suppressive function. In this study, we analysed forkhead box P3 (FOXP3) at the single-cell level in MS patients and controls (healthy individuals and patients with other neurological diseases) by means of intracellular flow cytometry. Our data revealed a reduced number of peripheral blood CD4+ CD25(high) FOXP3+ T cells and lower FOXP3 protein expression per cell in RR-MS patients than in SP-MS patients and control individuals, which was correlated with the suppressive capacity of Tregs in these patients. Interestingly, interferon (IFN)-beta-treated RR-MS patients showed restored numbers of FOXP3+ Tregs. Furthermore, a higher percentage of CD4+ CD25(high) FOXP3+ Tregs in RR-MS patients, as compared with controls and SP-MS patients, expressed CD103 and CD49d, adhesion molecules involved in T-cell recruitment towards inflamed tissues. This was consistent with a significantly increased number of CD27+ CD25(high) CD4+ T cells in the cerebrospinal fluid (CSF), as compared with peripheral blood, in RR-MS patients. Taken together, these data show aberrant FOXP3 expression at the single-cell level correlated with Treg dysfunction in RR-MS patients. Our results also suggest that Tregs accumulate in the CSF of RR-MS patients, in an attempt to down-regulate local inflammation in the central nervous system.     

Costimulatory effects of IL-1 on the expansion/differentiation of CD4+CD25+Foxp3+ and CD4+CD25+Foxp3- T cells

CD4+CD25+forkhead box p3 (Foxp3)+ regulatory T cells (Treg) control peripheral tolerance. Although Treg are anergic when stimulated through the TCR, mature bone marrow-derived, but not splenic, dendritic cells (DC) can induce their proliferation after TCR stimulation in the absence of IL-2. One possibility is that the DC produce proinflammatory cytokines such as IL-1 or IL-6 that function as growth factors for Treg. We have analyzed the costimulatory effects of IL-1 on the expansion of Foxp3+ Treg in vitro. When CD4+CD25+ T cells were cultured in the presence of splenic DC and IL-1, marked expansion of the Foxp3+ T cells was observed. The effects of IL-1 were mediated on CD4+CD25+Foxp3(-) T cells present in the starting population rather than on the DC or on the CD4+CD25+Foxp3+ T cells. In contrast, stimulation of CD4+CD25+ T cells with plate-bound anti-CD3 and IL-1 in the absence of DC resulted in the outgrowth of a CD4+CD25+Foxp3(-) T cell population composed of NKT cells and non-NKT, IL-17-producing cells. Foxp3+ Treg purified from mice expressing the reporter gene enhanced GFP in the Foxp3 locus failed to proliferate when costimulated with IL-1. These findings have important implications for the design of protocols for the expansion of CD4+CD25+ T cells for cellular biotherapy.     

CD4-mediated functional activation of human CD4+CD25+ regulatory T cells

Naturally occurring CD4(+)CD25(+)FoxP3(+) regulatory T cells (CD25(+) Tregs) constitute a specialized population of T cells that is essential for the maintenance of peripheral self-tolerance. The immune regulatory function of CD25(+) Tregs depends upon their activation. We found that anti-CD4 antibodies activate the suppressive function of human CD25(+) Tregs in a dose-dependent manner. We demonstrate that CD4-activated CD25(+) Tregs suppress the proliferation of CD4(+) and CD8(+) T cells, their IL-2 and IFN-gamma production as well as the capacity of CD8(+) T cells to re-express CD25. By contrast, anti-CD4 stimulation did not induce suppressive activity in conventional CD4(+) T cells. These results identify CD4 as a trigger for the suppressive function of CD25(+) Tregs and suggest a possible CD4-mediated exploitation of these cells.     

CD4(+) regulatory T cells in autoimmunity and allergy

Regulatory T cells (also referred to as suppressor T cells) are important components of the homeostasis of the immune system, as impaired regulatory T cell activity can cause autoimmune diseases and atopy. It is now clear that the phrase 'regulatory T cells' encompasses more than one cell type. For instance, CD4(+)CD25(+) regulatory T cells have received attention due to their immunosuppressive properties in vitro and in vivo, but in several instances it has been shown that CD4(+)CD25(-) T cell populations also contain potent regulatory activity. Recent progress in the field of regulatory T cells includes the discovery of the role of two tumor necrosis factor receptor (TNFR) family members (GITR and TRANCE-R/RANK) in Treg biology, the improved understanding of the role of co-stimulatory molecules and cytokines IL-10 and IL-2 in the induction and function of Tregs, and the generation of CD25(+) and CD25(-) regulatory T cells in vivo through high-avidity T cell receptor interactions.     

CD4~+CD25~+Foxp3~+调节性T细胞与LSCC发病的相关研究

为研究调节性T细胞在喉鳞状细胞癌(laryngeal squamous cell carcinoma,LSCC)、发展中的变化及其参与疾病进展的作用机制,收集2010～2011年上海市五官科医院收治的50例LSCC患者的肿瘤组织和外周血,应用流式细胞术检测CD4+CD25+Foxp3+Treg细胞及趋化因子受体CCR6的表达变化,Real-time PCR法检测转录因子Foxp3以及细胞因子mRNA的表达量。结果发现:LSCC患者外周血中CD4+CD25+Foxp3+Treg的百分比较正常人显著增加,并与临床分期相关;CD4+CD25+CCR6+Treg Foxp3的表达,以及肿瘤组织Foxp3mRNA的表达皆明显高于对照组,且与临床分期、淋巴结转移相关。同时发现,LSCC患者外周血中TGF-β和IL-10mRNA的检出水平分别高于对照组,但IFN-γ、IL-2、IL-12mRNA的水平低于对照组。提示此类Foxp3+Treg属于一类诱导性T抑制细胞(Foxp3+iTreg),可通过产生IL-10和TGF-β抑制LSCC患者的细胞免疫功能。Foxp3的检测可能对判断LSCC的预后有一定价值。     

Flow cytometry-based methods for studying signaling in human CD4+CD25+FOXP3+ T regulatory cells

T regulatory (Treg) cells have a fundamental role in the establishment and maintenance of peripheral tolerance. It is well established that Treg cells have a phenotype and function that is distinct from conventional T effector cells, although how these two T cell subsets differ in terms of molecular signaling cascades remains largely unknown. Analysis of signaling events in Treg cells using classical biochemistry has been hampered due to difficulties in isolating homogeneous populations and limited cell numbers. In order to overcome these challenges, we defined the optimal conditions for culture, in vitro expansion, and stimulation of human CD4(+)CD25(+) Treg and T effector cells to study intracellular signaling events by flow cytometry. In order to avoid the pitfalls associated with cell isolation based on CD25 expression, we developed methodology to analyze subpopulations of FOXP3 positive and negative cells from ex vivo CD4(+) T cells. In addition to examination of ex vivo cells, we optimized expansion conditions for analysis of signaling in Treg and T effector cell lines. Using these methods, we found that human FOXP3(+) Treg cells displayed a greater capacity to phosphorylate the extracellular regulated kinase (ERK) compared to T effector cells, upon TCR-mediated activation. In contrast, FOXP3(+) Treg cells showed a significantly diminished capacity to phosphorylate AKT. This methodology provides a foundation for future investigation into the molecular events that regulate the phenotype and function of Treg cells, and may ultimately lead to the identification of Treg-cell specific therapeutic targets.     

In vivo depletion of CD4+CD25+ regulatory T cells in cats

To establish a characterized model of regulatory T cell (Treg) depletion in the cat we assessed the kinetics of depletion and rebound in peripheral and central lymphoid compartments after treatment with anti-CD25 antibody as determined by cell surface markers and FOXP3 mRNA expression. An 82% decrease in circulating CD4+CD25+ Tregs was observed by day 11 after treatment. CD4+CD25+ cells were also reduced in the thymus (69%), secondary lymphoid tissues (66%), and gut (67%). Although CD4+CD25+ cells rebound by day 35 post-treatment, FOXP3 levels remain depressed suggesting anti-CD25 antibody treatment has a sustainable diminutive effect on the Treg population. To determine whether CD25+ Treg depletion strategies also deplete activated CD25+ effector cells, cats were immunized with feline immunodeficiency virus (FIV) p24-GST recombinant protein, allowing them to develop a measurable memory response, prior to depletion with anti-CD25 antibody. Anti-FIV p24-GST effector cell activity in peripheral blood after depletion was sustained as determined by antigen-specific T cell proliferation and humoral responses against FIV p24-GST with an ELISA for antigen-specific feline IgG. Furthermore, development of an anti-mouse response in Treg-depleted cats was similar to control levels indicating the retained capacity to respond to a novel antigen. We conclude that despite alterations in CD25+ cell levels during depletion, the feline immune system remains functional. We demonstrate here a model for the study of disease pathogenesis in the context of reduced numbers of immunosuppressive CD4+CD25+ Tregs throughout the feline immune system.