Transient expression of FOXP3 in human activated nonregulatory CD4+ T cells

Foxp3 plays a key role in CD4+ CD25+ T(reg) cell function in mice and represents a specific marker for these cells. Despite the strong association between FOXP3 expression and regulatory function in fresh human T cells, little is known about the dynamics of endogenous FOXP3 expression and its relation to the suppressive function in activated human T cells. Here, we addressed the dynamics of FOXP3 expression during human CD4+ T cell activation by plate-bound anti-CD3 Ab as well as the relationship between its expression and regulatory function at the single-cell level. Our data show that FOXP3 is expressed in a high percentage of activated T cells after in vitro stimulation of human CD4+ CD25- cells. FOXP3 expression is strongly associated with hyporesponsiveness of activated T cells, but is not directly correlated with their suppressive capabilities, as we demonstrate that it is also expressed in activated nonsuppressive T cells. However, in this nonsuppressive T cell population, FOXP3 expression is transient, while it is stably expressed in activated T cells that do display suppressive function, and in natural CD4+ CD25++ T(reg) cells. These data indicate that expression of endogenous FOXP3, in humans, is not sufficient to induce regulatory T cell activity or to identify T(reg) cells.     

The role of CD4CD25 T cells in autoantibody production in murine lupus

Systemic lupus erythematosus (SLE) is a chronic, systemic autoimmune disease characterized by the loss of tolerance to self-antigen. Because it is currently not known if regulatory T (T(reg)) cells are involved in the pathogenesis, we determined the frequency of CD4(+)CD25(+) T cells and assayed the related gene expression levels in CD4(+)CD25(+) T cells isolated from both lupus mice (NZB/NZW F(1)) and normal control mice (DBA2/NZW F(1)). The results showed that the frequency of CD4(+)CD25(+) T cells in lupus mice was lower than that of normal mice. Except for the high expression level of interleukin (IL)-10 mRNA, CD4(+)CD25(+) T cells from lupus mice expressed normal forkhead box P3 (Foxp3) and transforming growth factor (TGF)-beta mRNA, and exerted suppressive functions. Furthermore, we depleted CD25(+) T(reg) cells of non-autoimmune mice with anti-CD25 antibody and broke their tolerance with apoptotic cell-pulsed dendritic cells for the follow-up of autoantibody levels. The mice in the CD25(+) cell-depleted group had higher titres of anti-double-strand/single-strand DNA antibodies than those of the isotype control antibody-treated group. These findings indicated that CD4(+)CD25(+) T cells might be involved in the regulatory mechanism of autoantibody production.     

糖皮质激素对哮喘小鼠CD4~+T细胞中miRNA-155表达调控的研究

目的:探讨糖皮质激素对哮喘小鼠CD4~+ T细胞中微小RNA-155(miRNA-155)表达调控的影响。方法:使用糖皮质激素对卵清蛋白诱导的小鼠哮喘模型进行治疗,观察糖皮质激素对哮喘小鼠肺组织病理学、肺组织及CD4~+ T细胞中miRNA-155表达和支气管肺泡灌洗液(BALF)中细胞因子含量的影响。结果:RT-qPCR结果显示,哮喘小鼠肺组织和脾脏CD4~+ T细胞中miRNA-155表达显著升高,随着接触过敏原时间的增加,CD4~+ T细胞中miRNA-155水平显著升高(P0.01)。HE和PAS染色显示,与对照组相比,模型小鼠肺组织中炎性细胞浸润显著增加,给予糖皮质激素治疗后可明显减轻支气管周围和血管周围炎症,减少增生杯状细胞的黏液分泌。糖皮质激素治疗后哮喘小鼠肺组织中的miRNA-155水平显著降低,CD4~+ T细胞中的miRNA-155水平显著下调。糖皮质激素治疗可抑制哮喘小鼠的脾脏中CD4~+ CD8~-细胞比例的增加,减少哮喘小鼠肺组织中CD4~+ T细胞的聚集。糖皮质激素治疗后BALF中白细胞介素4(IL-4)、IL-5和IL-13水平下降,干扰素γ水平显著增加。结论:糖皮质激素可抑制哮喘小鼠肺组织中CD4~+ T细胞的聚集,并可降低肺组织和脾脏中CD4~+ T细胞的miRNA-155的表达。     

Thymic production of human FOXP3(+) regulatory T cells is stable but does not correlate with peripheral FOXP3 expression

In humans functionally mature FOXP3⁺ regulatory T (Treg) cells can be found already in the fetus, but the kinetics of their maturation is still unknown. Here, we show that from birth to until 10 years of age the thymic production of FOXP3⁺ Treg cells is very stable and correlates with T-lymphopoiesis in general. The level of FOXP3 expression in the blood was also very stable, even when children and adults were compared, but there was no correlation between thymic and peripheral FOXP3 levels. Analysis of the cell cycle-associated marker Ki67 showed that a substantial fraction of peripheral FOXP3⁺ cells is dividing. This characteristic was obtained in the periphery, since it was not observed in thymic CD4⁺ FOXP3⁺ cells. These data suggest that the thymic output of human Treg cells is intrinsically stable, while in the periphery the increased rate of proliferation severs the connection between production and homeostatic maintenance of the FOXP3⁺ Treg cell population.     

CD4+ CD25+ FOXP3+ regulatory T cells from human thymus and cord blood suppress antigen-specific T cell responses

Activation of self-reactive T cells in healthy adults is prevented by the presence of autoantigen-specific CD4+CD25+ regulatory T cells (CD25+ Treg). To explore the functional development of autoantigen-reactive CD25+ Treg in humans we investigated if thymic CD25+ Treg from children aged 2 months to 11 years and cord blood CD25+ Treg are able to suppress proliferation and cytokine production induced by specific antigens. While CD4+CD25- thymocytes proliferated in response to myelin oligodendrocyte glycoprotein (MOG), tetanus toxoid and beta-lactoglobulin, suppression of proliferation was not detected after the addition of thymic CD25+ Treg. However, CD25+ Treg inhibited interferon (IFN)-gamma production induced by MOG, which indicates that MOG-reactive CD25+ Treg are present in the thymus. In contrast, cord blood CD25+ Treg suppressed both proliferation and cytokine production induced by MOG. Both cord blood and thymic CD25+ Treg expressed FOXP3 mRNA. However, FOXP3 expression was lower in cord blood than in thymic CD25+ T cells. Further characterization of cord blood CD25+ T cells revealed that FOXP3 was highly expressed by CD25+CD45RA+ cells while CD25+CD45RA- cells contained twofold less FOXP3, which may explain the lower expression level of FOXP3 in cord blood CD25+ T cells compared to thymic CD25+ T cells. In conclusion, our data demonstrate that low numbers of MOG-reactive functional CD25+ Treg are present in normal thymus, but that the suppressive ability of the cells is broader in cord blood. This suggests that the CD25+ Treg may be further matured in the periphery after being exported from the thymus.     

Regulatory T cells in a spectrum of HPV-induced cervical lesions: cervicitis, cervical intraepithelial neoplasia and squamous cell carcinoma

PROBLEM: Thriving of tumors amidst rich immune infiltrates is an unexplained paradox. METHOD OF STUDY: Immune markers on lymphocytic infiltrates in HPV-positive cervicitis, cervical intraepithelial neoplasia III (CIN III), squamous cell carcinoma (SCC) and normal cervices were characterized immunohistochemically. Regulatory T cells were enumerated and phenotypically characterized using antibodies to FOXP3. RESULTS: SCCs had higher numbers of CD4 and CD8 cells; infiltrates expressed more CD25, TGFbeta, and IL10 but had significantly lower IL2 compared with cervicitis and CIN III. Expression of CD25 and IL2 correlated well in cervicitis and CIN III but not in SCC. FOXP3 expression was also higher and ratios of CD4/FOXP3 and CD8/FOXP3 were lower in SCC. A fraction of cervicitis, CIN I, CIN II and CIN III had natural (n) regulatory T cells (Tregs); their lesional distribution was predominantly intraepithelial in cervicitis, while in CIN they were also present in the stroma. The proportion of FOXP3(+) CD25(+); FOXP3(+) CD25(-) and TGFbeta(+) CD25(+) in invasive tumors was 17; 19 and 22 respectively. CONCLUSION: Cervical tumors are marked by the presence of an immunoregulatory environment, and harbor equal proportions of 'inactive' n Tregs; activated n Tregs; and Tregs operating via TGFbeta. nTregs in cervicitis and CIN may be a potential marker of persistence.     

The role of CD4+ T-cell subsets in determining transplantation rejection or tolerance

Summary: Peripheral tolerance to allogeneic organ grafts can be induced in rodents by treating with non-depleting CD4 and CD8 monoclonal antibodies. This tolerance is maintained by CD4⁺ T cells with a potent capacity to induce tolerance in further cohorts of T cells (i.e. infectious tolerance). We have cloned CD4⁺ T-cell subsets against the male transplantation antigen in vitro and find, in contrast to Th1 or Th2 clones that elicit rejection, that there is a distinct population of CD4⁺ T cells that suppress rejection by adoptive transfer (here called T reg ). In order to identify molecular markers associated with tolerance and gain insights into the mechanisms of action of T reg cells, we carried out serial analysis of gene expression. We identified genes overexpressed in T reg compared to Th1 and Th2 cultures and found that some of these correlated in vivo with CD4-induced transplantation tolerance rather than rejection. The genes overexpressed in T reg cultures and within tolerated skin grafts were primarily expressed by mast cells (e.g. tryptophan hydroxylase and FcεR1α), suggesting that regulatory cell activity and this form of tolerance may be associated with a localised but non-destructive form of Th2-like activation and a recruitment of mast cells.     

Suppression of the immune system by oral glucocorticoid therapy in bronchial asthma

The effect of systemic glucocorticoid therapy on immune parameters was studied in patients with bronchial asthma. Patients were divided into two groups: 1) those receiving oral glucocorticoid; 2) control patients who did not receive systemic glucocorticoid treatment. The glucocorticoid dose varied between 5 and 70 mg per day. Patients had been taking oral therapy for at least 1 year. Glucocorticoid treatment was associated with an increased frequency of respiratory tract infections. Therefore, we need to define immune parameters which may predict an increased risk of infections. In this study, we analyzed several surface markers on lymphocytes and monocytes by flow cytometry. A significant reduction of the ratio of peripheral blood CD4⁺ to CD8⁺ T cells was associated with the administration of oral glucocorticoids. Furthermore, the expression of the HLA-DR molecule on monocytes was reduced in patients with systemic glucocorticoid therapy compared to control patients. Moreover, the capacity to elaborate cytokines by peripheral blood mononuclear cells upon stimulation was greatly reduced after exposure to glucocorticoids in vivo and in vitro. In addition, the humoral immune response was affected, because reduced IgG, IgM, and IgA levels were observed in patients receiving oral glucocorticoids. These results indicate that systemic glucocorticoid treatment in patients with bronchial asthma is associated with cellular and humoral immunosuppression which results in an increased risk of bacterial and viral infections.     

High-altitude climate therapy reduces local airway inflammation and modulates lymphocyte activation

High-altitude climate therapy is a well-established therapeutic option, which improves clinical symptoms in asthma. However, little is known about the underlying immunological mechanisms. The study investigates the influence of high-altitude climate therapy on airway inflammation and cellular components of specific and unspecific immune response. Exhaled NO significantly decreased within 3 weeks of therapy in patients with allergic and intrinsic, moderate and severe asthma. Interleukin-10 (IL-10)-secreting peripheral blood mononuclear cells (PBMC) increased within 3 weeks of therapy in six of 11 patients, whereas transforming growth factor-beta(1)-secreting PBMC remained stable. Furthermore, monocyte activation, assessed by CD80 expression significantly decreased during therapy. The frequency of CRTH2-expressing T cells decreased, while regulatory T cells (T(reg)) remained stable. FOXP3 and GATA-3 mRNA expression in CD4(+) T cells did not change, while interferon-gamma and IL-13 mRNA expression decreased in eight of 10 patients. The current data demonstrate that high-altitude climate therapy reduces local airway inflammation. Furthermore, monocytes switch towards a tolerogenic phenotype under high-altitude climate therapy. The T(reg)/Th2 ratio increases; however, because of the absence of antigens/allergens, no de novo differentiation of Th2 nor T(reg) cells is observed. The high-altitude climate therapy therefore may form the immunological basis for the endogenous control of allergen-driven diseases.     

Transient regulatory T-cells: a state attained by all activated human T-cells

CD4(+)CD25(+)FOXP3(+) regulatory T-cells (T(regs)) form an important arm of the immune system responsible for suppressing untoward immune responses. T(regs) can be thymically derived or peripherally induced, even from CD4(+)CD25(-)FOXP3(-) T-cells. FOXP3 expression and in vitro suppressive activity are considered unique hallmarks of this dedicated and stable lineage of regulatory cells. Here we show that virtually all human CD4(+)CD25(-)FOXP3(-) T-cells and CD8(+)CD25(-)FOXP3(-) T-cells attain a transient FOXP3(+)CD25(+) state during activation. In this state of activation, these cells possess the classic phenotype of T(regs), in that they express similar markers and inhibit in vitro proliferation of autologous CD4(+)CD25(-) T-cells. This state is characterized by suppressed IFN-gamma production and robust TNF-alpha and IL-10 production. Interestingly, the great majority of the activated cells eventually downregulate FOXP3 expression, with a concomitant drop in suppressive ability. Our results show that, in humans, FOXP3 expression and T(reg) functionality are not exclusive features of a stable or unique lineage of T-cells but may also be a transient state attained by almost all T-cells. These results warrant caution in interpreting human studies using FOXP3 and suppressive activity as readouts and suggest that attempts to induce "T(regs)" may paradoxically result in induction of effector T-cells, unless stability is confirmed.     

The levels of CD4+CD25+ regulatory T cells in paediatric patients with allergic rhinitis and bronchial asthma

Our purpose was to determine whether numbers of CD4(+)CD25(+) T [T regulatory (T(reg))] cells and mRNA expression of functional molecules of T(reg) are related to airway allergy and disease severity in 51 paediatric patients with allergic rhinitis or bronchial asthma and 47 healthy controls. Surface markers were evaluated with flow cytometry, and mRNA was determined with real-time polymerase chain reaction. Children with allergic disease had fewer CD4(+)CD25(+) T cells (8 x 49% +/- 2 x 41% versus 9 x 58% +/- 2 x 43%, P<0 x 05) and CD4(+)CD25(hi) T cells (1 x 32% +/- 0 x 68% versus 1 x 70% +/- 0 x 68%, P<0 x 01) than control subjects. Numbers of CD4(+)CD25(+) and CD4(+)CD25(hi) T lymphocytes were higher in children with persistent allergic rhinitis and/or moderate-severe bronchial asthma than in those with respective milder disease. The number of T(reg) cells was correlated positively with total immunoglobulin E level. The mRNA expression of forkhead box P3 (FoxP3) was increased in moderate-severe versus mild asthma (2 x 93 +/- 0 x 38 versus 1 x 60 +/- 0 x 31, P< 0 x 01). Patients with moderate-severe bronchial asthma also had increased mRNA expression of interleukin (IL)-10 compared with patients with mild asthma (15 x 24 +/- 4 x 07 versus 3 x 77 +/- 2 x 18, P<0 x 01). The suppressive function of T(reg) cells from patients with more severe asthma was competent in vitro. On average, decreased numbers of T(reg) cells in children with allergic airway disease might represent a defect of the T(reg) population. With increased expression of FoxP3 and IL-10 in T(reg) from patients with relatively severe allergic disease, adaptive and functional T(reg) might be generated in response to aggravated atopy and disease severity.     

分离培养人外周血CD4+CD25-T细胞及其生物学特性研究

目的:分离培养人外周血CD4 CD25-T细胞,并鉴定其生物学特性。方法:设对照组(A组)、LPS组(B组)、LPS 抗TGF-β1mAb组(D),用Percoll不连续密度梯度离心与免疫磁珠法,分离培养健康人外周血CD4 CD25-T细胞。用光镜及电镜观察其形态特征,台盼蓝试验检测其活力,流式细胞术(FCM)鉴定其纯度。体外培养4h、3d及5d后,用FCM检测CD4 CD25 T细胞的阳性率,ELISA法检测培养上清中TGF-β1的浓度,RT-PCR法检测细胞中叉状头/翼状螺旋转录因子(FOXP3)mRNA的表达。结果:(1)光镜下观察分离的CD4 CD25-T细胞主要为小体积细胞,电镜下观察细胞核呈圆形,染色质致密。体外抗人CD3/CD28mAb刺激培养的CD4 CD25-T细胞体积逐渐增大,胞质较丰富,电镜下观察细胞核呈椭圆形或肾型,染色质较稀疏。(2)FCM检测CD4 CD25-T细胞纯度达91.5%～96%。台盼蓝试验检测分离前后活细胞数无统计学意义(P>0.05)。(3)FCM检测表明,B5d组为CD4 CD25 T细胞的阳性率为(55.99±1.42)%与A5d组相比较有统计学意义(P<0.01);D5d组CD4 CD25 T细胞的阳性率为(1.99±0.83)%与A5d组的阳性率(1.29±0.04)%相比较无统计学意义。(4)ELISA测定表明,培养液中TGF-β1的浓度,B3d组为(1.60±0.09)μg/L、B5d组为(1.83±0.14)μg/L,分别与A3d组为(0.35±0.04)μg/L、A5d组为(0.33±0.08)μg/L相比较,均有统计学意义(P<0.01);而D3d、D5d组与A3d、A5d组相比较均无统计学意义。(5)RT-PCR检测表明,FOXP3mRNA的表达:以β-actin的A值作为内参照,B3d组为(0.84±0.07)、B5d组为(1.85±0.24)分别与A3d组(0.05±0.02)、A5d组(0.04±0.02)相比较,均有统计学意义(P<0.01);而D组与A组的各个组间相比较均无统计学意义。(6)LPS诱导的人外周血中CD4 CD25-T细胞培养液上清中TGF-β1的水平与该细胞中FOXP3mRNA的表达呈显著的正相关(r=0.812,P<0.01)。结论:用Percoll不连续密度梯度离心与免疫磁珠法体外分离培养的人外周血CD4 CD25-T细胞的活力及纯度较理想;LPS诱导的CD4 CD25-T细胞中FOXP3mRNA的表达,可能与TGF-β1有关。