Relative Resistance of Human CD4+ Memory T Cells to Suppression by CD4+CD25+ Regulatory T Cells

Successful expansion of functional CD4⁺CD25⁺ regulatory T cells (T_reg) ex vivo under good manufacturing practice conditions has made T_reg‐cell therapy in clinical transplant tolerance induction a feasible possibility. In animals, T_reg cells home to both transplanted tissues and local lymph nodes and are optimally suppressive if active at both sites. Therefore, they have the opportunity to suppress both naïve and memory CD4⁺CD25^? T cells (Tresp). Clinical transplantation commonly involves depleting therapy at induction (e.g. anti‐CD25), which favors homeostatic expansion of memory T cells. Animal models suggest that T_reg cells are less suppressive on memory, compared with naïve Tresp that mediate allograft rejection. As a result, in the context of human T_reg‐cell therapy, it is important to define the effectiveness of T_reg cells in regulating naïve and memory Tresp. Therefore, we compared suppression of peripheral blood naïve and memory Tresp by fresh and ex vivo expanded T_reg cells using proliferation, cytokine production and activation marker expression (CD154) as readouts. With all readouts, naïve human Tresp were more suppressible by approximately 30% than their memory counterparts. This suggests that T_reg cells may be more efficacious if administered before or at the time of transplantation and that depleting therapy should be avoided in clinical trials of T_reg cells.     

Expression of CD39 by Human Peripheral Blood CD4+CD25+ T Cells Denotes a Regulatory Memory Phenotype

We have shown that CD39 and CD73 are coexpressed on the surface of murine CD4⁺Foxp3⁺ regulatory T cells (Treg) and generate extracellular adenosine, contributing to Treg immunosuppressive activity. We now describe that CD39, independently of CD73, is expressed by a subset of blood‐derived human CD4⁺CD25⁺CD127lo Treg, defined by robust expression of Foxp3. A further distinct population of CD4⁺CD39⁺ T lymphocytes can be identified, which do not express CD25 and FoxP3 and exhibit the memory effector cellular phenotype. Differential expression of CD25 and CD39 on circulating CD4⁺ T cells distinguishes between Treg and pathogenic cellular populations that secrete proinflammatory cytokines such as IFNγ and IL‐17. These latter cell populations are increased, with a concomitant decrease in the CD4⁺CD25⁺CD39⁺ Tregs, in the peripheral blood of patients with renal allograft rejection. We conclude that the ectonucleotidase CD39 is a useful and dynamic lymphocytes surface marker that can be used to identify different peripheral blood T cell‐populations to allow tracking of these in health and disease, as in renal allograft rejection.     

CD4+CD25+调节性T细胞在维持小鼠肝脏移植自发性免疫耐受状态中的作用

目的 探讨CD4+CD25+调节性T细胞在维持小鼠肝脏移植免疫耐受状态中的作用.方法 进行小鼠原位肝脏移植,诱导出移植免疫耐受后,向受体注射抗CD25抗体(PC61)以去除CD4+CD25+T细胞,检测受体内CD4+CD25+T细胞数量及叉状头/翅膀状螺旋转录因子(Foxp3)的表达以确定CD4+CD25+T细胞完全被清除,同时观察受体生存时间.结果 与同种同系小鼠肝脏移植结果 相似,同种异系肝脏移植小鼠的生存时间亦均超过70 d.移植免疫耐受诱导后,PC61不同注射方案均能完全去除受体小鼠肝脏、脾脏及血液中的CD4+CD25+T细胞,且移植肝脏中Foxp3 mRNA的表达也明显降低,表明完全去除了CD4+CD25+调节性T细胞,但肝脏移植动物生存时间并未受到影响.结论 CD4+CD25+调节性T细胞对于小鼠肝脏移植自发性免疫耐受的维持并非必需.     

Presence of Functional Mouse Regulatory CD4+CD25+T Cells in Xenogeneic Neonatal Porcine Thymus-Grafted Athymic Mice

Xenotransplantation with porcine thymus is emerging as a possible means to reconstitute host cellular immunity and to induce immune tolerance in rodents and large animals. However, the presence of regulatory T cells (Treg cells) in this model needs to be determined. We herein demonstrated that efficient repopulation of mouse CD4+CD25+Treg cells was achieved in Balb/c nude mice by grafting neonatal porcine thymic tissue (NP THY). Mouse CD4+CD25+T cells expressed normal levels of Foxp3 in NP THY-grafted nude mice. Furthermore, these CD4+CD25+Treg cells showed significant inhibitory effects on the cell proliferation or interleukin-2 products of syngeneic T cells to alloantigens, Con A or a peptide antigen, although the potent immunosuppressive function might be lower than CD4+CD25+Treg cells in Balb/c mice. CD4+CD25+T cells in NP THY-grafted nude mice showed significantly stronger inhibition on the response to donor porcine antigens of CD4+CD25(-)T cells than CD4+CD25+Treg cells in Balb/c mice. Both CD4+CD25+Treg cells in NP THY-grafted nude and Balb/c mice prevented the development of autoimmune disease mediated by syngeneic CD4+CD25(-)T cells in a similar efficient way in the secondary recipients. These findings provide evidence for the potential involvement of CD4+CD25+Treg cells in keeping self-tolerance and transplant tolerance in this xeno-thymus transplantation model.     

胃癌患者手术前后CD4+CD25+调节性T细胞的变化

目的 研究胃癌患者手术前、后调节性T细胞(Treg)及FoxP3表达的变化.方法 采用流式细胞术检测20例胃癌患者术前及其中15例接受了手术者术后1周(简称术后)以及15例因胃部不适接受胃镜检查的自愿者(正常对照组)外周血中Treg数量的变化,用RT-PCR法检测Treg的特异性分子标志物FoxP3的转录水平,同时用免疫组织化学法检测胃癌组织中FoxP3蛋白的表达情况.结果 胃癌患者术前外周血中CD4+T细胞中的CD4+ CD25+比例明显高于正常对照组[(19.39±5.58)%比(9.91±3.23)%,P＜0.01],而术后CD4+ CD25+比例较术前明显下降[(13.50±5.93)%比(19.39±5.58)%,P＜0.05].胃癌患者术前外周血中FoxP3转录水平明显高于正常对照组(0.86±0.03比0.64±0.02,P＜0.01),而术后较术前明显下降(0.73±0.04比0.86±0.03,P＜0.05),提示FoxP3转录水平与Treg变化一致.胃癌患者外周血中CD4+T细胞在单个核细胞中的比例与正常对照组相比明显下降(P＜0.01),而手术前、后变化不明显.20例胃癌患者中13例胃癌癌细胞的细胞浆中有不同程度的FoxP3蛋白表达(强阳性2例,中阳性6例,弱阳性5例),7例胃癌患者的胃癌细胞中不表达.结论 Treg可能通过免疫抑制作用在胃癌的发生、发展中发挥作用,肿瘤组织本身可能是引起Treg变化的重要始动因素.     

Following Anti-CD25 Treatment, A Functional CD4+CD25+ Regulatory T-Cell Pool Is Present in Renal Transplant Recipients

Daclizumab, a humanized antibody directed against the alpha-chain of the interleukin-2 receptor (CD25), has shown efficacy in the prevention of acute rejection following organ transplantation. However, anti-CD25 therapy can be expected to affect not only alloreactive effector T cells, but also CD4(+)CD25(+) regulatory T (Treg) cells that are shown to play an important role in the induction of transplantation tolerance. Therefore, the size and function of the Treg pool in human renal allograft recipients after single-dose daclizumab administration was investigated in this study. Approximately 8 weeks after administration, daclizumab was cleared from the circulation and the Treg population then present appeared not different from that observed before transplantation. Functional analysis revealed that the Treg possessed a normal capacity to suppress mixed lymphocyte reactions in vitro. These data indicate that after daclizumab therapy a Treg population, normal in number and function, is present in the peripheral blood of renal transplant recipients.     

反复自然流产患者外周血CD4~+CD25~+调节性T细胞的检测

目的:探讨CD4+CD25+调节性T细胞(Tr)在反复自然流产发病机制中的作用。方法:应用流式细胞术检测29例原因不明的反复自然流产妇女(URSA组)和20例正常妊娠妇女(正常对照组)外周血中CD4+CD25+Tr的比例。结果:URSA组外周血中CD4+CD25brightTr百分率[(1.98±0.96)%]显著低于正常对照组[(3.21±1.25)%,P<0.05],而2组间CD4+CD25+总百分率、CD4+CD25dim细胞百分率以及CD4+CD25bright/CD4+比值均无显著性差异(P均>0.05)。结论:URSA的发生可能与患者CD4+CD25brightTr比例下降有关,CD4+CD25brightTr在母胎免疫耐受中发挥重要作用。     

The Jak Inhibitor CP‐690,550 Preserves the Function of CD4+CD25brightFoxP3+ Regulatory T Cells and Inhibits Effector T Cells

The Jak inhibitor CP‐690,550 inhibits alloreactivity and is currently being investigated for prevention of allograft rejection after transplantation. In this study, we examined the effect of CP‐690,550 on IL‐2‐mediated Jak/STAT5 phosphorylation by CD4⁺CD25^brightFoxP3⁺CD127^?/low T cells (Treg) and CD4⁺CD25^neg effector T cells (Teff) in kidney transplant (KTx) patients. Phosphospecific flow cytometry was used to study the effect of CP‐690,550 on IL‐2‐induced intracellular STAT5‐phosphorylation. IL‐2‐induced phosphorylation of STAT5 (P‐STAT5) in both Treg and Teff, which was significantly higher for CD4⁺CD25^bright Treg (increased by 71%, mean) than for CD4⁺CD25^neg Teff (increased by 42%). In the presence of 100 ng/mL CP‐690,550, a clinically relevant exposure, IL‐2‐induced P‐STAT5 was partially inhibited in CD4⁺CD25^brightTreg (% inhibition; 51%), while almost completely blocked in Teff (%inhibition; 84%, p = 0.03). The IC₅₀ was 2–3 times higher for Treg (104 ng/mL) than for Teff (40 ng/mL, p = 0.02). In the presence of CP‐690,550, Treg exhibited additional suppressive activities on the alloactivated proliferation of Teff (56%, mean). In addition, CD4⁺CD25^bright Treg from KTx‐patients receiving CP‐690,550 vigorously suppressed the proliferation of Teff (87%, mean). Our findings show that CP‐690,550 effectively inhibits Teff function but preserves the suppressive activity of CD4⁺CD25^bright regulatory T cells.     

免疫磁珠两步法分离大鼠脾脏CD4+CD25+调节性T细胞

目的探索利用磁性细胞分离(MACS)系统高效、快速地分离大鼠脾脏CD4+CD25+调节性T细胞.方法采用免疫磁珠两步法分离大鼠脾脏内的CD4+CD25+调节性T细胞, 首先采用"鸡尾酒"抗体和抗IgG磁珠阴性分选CD4+ T细胞,再用抗CD25-PE抗体和抗PE磁珠阳性分选获得CD4+CD25+T 细胞.分离后的细胞经流式细胞仪检测分离纯度; 台盼蓝染色检测细胞存活率; 体外增殖实验检测其对CD4+CD25-T细胞的免疫抑制作用.结果阴性分选获得的CD4+T细胞纯度为(83.6±2.5)%(79%～87%), 阳性分选后获得的CD4+CD25+T细胞纯度为(90.2±1.8)%(86%～93%), 细胞存活率为(92.8±3.4)%(92%～95%), 体外增殖实验表明,CD4+CD25+T细胞能明显抑制CD4+CD25-T 细胞的增殖(P＜0.01). 结论采用MACS系统阴性加阳性分选可以高效、快速地获得理想纯度和有免疫抑制功能的大鼠CD4+CD25+调节性T细胞.     

Serum 25-Hydroxyvitamin D Level Is Not Related to Regulatory T Cells or Kidney Function in Renal Transplant Recipients

Background

Vitamin D and regulatory T cells (Tregs) are both involved in promoting peripheral tolerance and limiting chronic inflammatory diseases. Renal transplant recipients (RTRs) are likely to have low vitamin D levels, which may influence their immune status.

CD4+ CD25bright+ Regulatory T Cells Can Mediate Donor Nonreactivity in Long-Term Immunosuppressed Kidney Allograft Patients

CD4+ CD25bright+ FoxP3+ T cells are potent regulators of T-cell reactivity, but their possible involvement in donor-specific nonresponsiveness after clinical kidney transplantation remains to be elucidated. We assessed the proliferative donor-reactivity in 33 kidney allograft recipients who were maintained on a combination of proliferation inhibitors (mycophenolate mofetil (MMF) or Azathioprine (Aza)) and prednisone, long (> 5 years) after transplantation. Of the 33 patients, 8 still exhibited donor-reactivity, whereas 25 were classified as donor nonreactive patients. Within these 25 donor nonreactive patients, we assessed the involvement of CD4+ CD25bright+ regulatory T cells both by depleting them from the responder population as well as by reconstituting them to the CD25(-/dim) effector population. The absence of proliferation in these 25 patients, was abolished in 7 (28%) recipients upon depletion of the CD4+ CD25bright+ T cells. Reconstitution of these cells suppressed the donor-reactivity in a dose-dependent manner. Adding-back CD4+ CD25bright+ T cells inhibited the anti-third party response in all recipients, indicating that functional CD4+ CD25bright+ T cells circulate despite more then 5 years of immunosuppressive treatment. Altogether, we conclude that in long-term immunosuppressed kidney allograft patients functional regulatory CD4+ CD25bright+ T cells circulate but that these cells mediate donor non reactivity only in a subset of patients.     

CD154+ Graft Antigen-Specific CD4+ T Cells are Sufficient for Chronic Rejection of Minor Antigen Incompatible Heart Grafts

We used a defined model system to address the role of minor histocompatibility antigen-specific CD4+ T cells in chronic rejection. The coronary arteries of vascularized heart grafts expressing the model antigen ovalbumin developed intimal hyperplasia in normal recipients and those lacking CD8+ T cells but not in those lacking CD4+ T cells. Furthermore, purified ovalbumin-specific CD4+ T cells from T-cell antigen receptor transgenic mice caused intimal hyperplasia in ovalbumin-expressing heart grafts in lymphocyte-deficient mice. The graft antigen-specific CD4+ T cells only caused intimal hyperplasia when expressing CD154 and were found in the intima of the affected coronary arteries along with CD40+ cells, CD11c+ dendritic cells and CD11b+, Gr-1+ monocytes. These results show that minor histocompatibility antigen-specific CD4+ T cells are required to cause the classical vascular changes of chronic rejection. They are capable of doing so without contributions from other lymphocytes, and may cause intimal hyperplasia by using CD154 to stimulate other non-lymphoid cells in the intima.     

Donor Apoptotic Lymphocyte Transfusion-Induced Liver Allograft Tolerance by Up-Regulation of CD4CD25 Regulatory T Cells in Peripheral Blood

Uptake of apoptotic cells by antigen-presenting cells (APC) may be involved in tolerance maintenance with an immunoregulatory role. The aim of this study was to evaluate the consequences of preoperative transfusion of donor apoptotic lymphocytes on survival of orthotopic liver transplantations (OLT). OLT was performed between Lewis (donor) and Brown Norway (BN recipient) inbred rats using a double-cuff technique. Apoptotic splenic lymphocytes induced by ultraviolet-C (UVC) irradiation were infused intravenously at 7 days before OLT. Changes in regulatory T cells in blood were determined using flow cytometry. UVC irradiated lymphocytes were sensitive and effective, as evidenced by increased peripheral blood CD4⁺CD25⁺ T cells compared with recipients that received infusion of untreated donor lymphocytes or a control. Apoptotic lymphocyte transfusion prolonged hepatic allograft survival, with significantly lower histological stages of inflammation and cellular infiltration than in untreated allografts. Our results demonstrated that donor apoptotic cells promoted allograft acceptance and up-regulated CD4⁺CD25⁺ regulatory T cells (Treg) in blood.     

Variation of CD4+CD25+Foxp3+ Regulatory T Cells and Th17 Cells in the Peripheral Blood of Human Liver Allograft Patients With Long-term Survival

Background

Monitoring of peripheral blood (PB) lymphocyte subpopulation counts may be useful to underlie immune status after liver transplantation (LT). We aimed at exploring the variation of regulatory cells and Th17 in the PB of liver allograft patients with long-term survival.

Regulatory CD25+ T cells in human kidney transplant recipients

Recent evidence suggests that a population of professional regulatory cells, which limit immune responsiveness, exist in rodents and healthy human subjects. However, their role in disease states remains unclear. A proportion of renal transplant recipients do not demonstrate in vitro reactivity toward their mismatched donor-derived HLA-DR antigens; it was therefore hypothesized that this may be due to such regulatory cells. A cohort of 23 renal transplant recipients was studied at a single institution. In patients with no history of acute rejection, 6 (40%) of 15 demonstrated regulation toward the mismatched HLA-DR allopeptides by CD25(+) cells. By contrast, only one (12.5%) in eight of those with a history of acute rejection demonstrated regulation. Interestingly, if the patient assays were stratified according to initial in vitro immune responsiveness toward the mismatched allopeptides, 8 (47.1%) of 17 of patient assays with low allopeptide responsiveness (alloreactive T cell frequencies less than 60/million) demonstrated regulation of indirect pathway alloresponses by CD25(+) cells, whereas 0 of 8 with higher responses (frequencies greater than 60/million) demonstrated no such regulation (P < 0.05 by chi(2) test). The regulatory cells are present in the circulation as early as 3 mo after transplantation and persist for a number of years, despite conventional immunosuppression. Furthermore, induction treatment with anti-IL-2R mAb did not prevent the development of these regulatory CD25(+) cells. Data from two patients suggest that these cells may also play a role in preventing epitope shifting, implicated in the ongoing immune activation contributing to chronic rejection, and that loss of regulation in a given patient may precede an episode of rejection.     

Allergic Conjunctivitis Renders CD4+ T Cells Resistant to T Regulatory Cells and Exacerbates Corneal Allograft Rejection

Allergic diseases rob corneal allografts of immune privilege and increase immune rejection. Corneal allograft rejection in BALB/c allergic hosts was analyzed using a short ragweed (SWR) pollen model of allergic conjunctivitis. Allergic conjunctivitis did not induce exaggerated T‐cell responses to donor C57BL/6 (B6) alloantigens or stimulate cytotoxic T lymphocyte (CTL) responses. Allergic conjunctivitis did affect T regulatory cells (Tregs) that support graft survival. Exogenous IL‐4, but not IL‐5 or IL‐13, prevented Treg suppression of CD4⁺ effector T cells isolated from naïve mice. However, mice with allergic conjunctivitis developed Tregs that suppressed CD4⁺ effector T‐cell proliferation. In addition, IL‐4 did not inhibit Treg suppression of IL‐4Rα^?/? CD4⁺ T‐cell responses, suggesting that IL‐4 rendered effector T cells resistant to Tregs. SRW‐sensitized IL‐4Rα^?/? mice displayed the same 50% graft survival as nonallergic WT mice, that was significantly less than the 100% rejection that occurred in allergic WT hosts, supporting the role of IL‐4 in the abrogation of immune privilege. Moreover, exacerbation of corneal allograft rejection in allergic mice was reversed by administering anti‐IL‐4 antibody. Thus, allergy‐induced exacerbation of corneal graft rejection is due to the production of IL‐4, which renders effector T cells resistant to Treg suppression of alloimmune responses.     

Influence of Immunosuppressive Drugs on the Development of CD4CD25 Foxp3 T Cells in Liver Transplant Recipients

Introduction

Many studies suggest that CD4⁺CD25^high T regulatory cells (Tregs) have a crucial role in downregulating the immune response to alloantigens. In this study, we investigated the possible influence of immunosuppressive therapy, including rapamycin and calcineurin inhibitors (CNIs; tacrolimus), on level of Tregs in liver allograft recipients.

Materials and Methods

We assessed 47 liver transplant recipients with stable liver function for ≥2 years, dividing them into 2 groups: Patients receiving rapamycin (n = 15), and those receiving tacrolimus (n=32). Thirty-eight, age-matched healthy subjects were used as normal controls. We examined the expression of CD4, CD25, and Foxp3 in peripheral blood T cells. Flow cytometry was performed with a FACSCalibur instrument with data analysis using Cell Quest software.

Results

Rapamycin significantly increased the prevalence of Tregs, including the percentage of CD4⁺CD25^high T cells in total lymphocytes and among total CD4⁺ T cells, compared with the healthy subjects and the CNI group. The prevalence of Tregs in the CNIs group was significantly lower than that of controls. Foxp3 was expressed in >95% of CD4⁺CD25^highT cells, whereas it was in <20% of CD4⁺CD25^low T cells and not expressed among CD4⁺CD25⁻ T cells.

Conclusions

Immunosuppressive therapy (rapamycin or CNIs) may have a different roles in tolerance induction among liver transplant recipients. Namely, rapamycin promoted the induction of a profile consistent with alloantigen tolerance; CNIs hampered this progression.     

早期肝癌术后患者调节性T细胞数量及功能变化

目的通过分析早期肝癌患者肝癌切除手术前、后外周血中CD4+CD25+FOXP3+调节性T细胞(Treg)数量及功能的变化,从免疫抑制角度探讨手术对肝癌患者免疫功能的影响。方法采集肝癌患者(病例组,15例)手术治疗前、后及正常人群(对照组,5例)外周血,提取淋巴细胞,行细胞外(CD4、CD25)及细胞内(FOXP3)染色,应用流式细胞仪分析Treg的数量及功能。结果 病例组CD4+CD25+T细胞和CD25+FOXP3+T细胞在术前外周血中所占比例均明显高于正常对照组〔(12.43±2.57)%比(5.56±1.02)%,(5.14±1.4)%比(2.18±0.83)%,P<0.05〕,病例组以上两种细胞在术后1周﹝(10.56±2.13)%,(4.28±1.08)%﹞较术前均有所下降,但差异无统计学意义(P>0.05),而术后2周〔(7.30±0.89)%,(3.43±0.83)%〕较术前下降明显(P<0.05)。病例组CD8+T细胞和CD4+CD25-T细胞在术前外周血中所占比例明显低于正常对照组〔(23.42±1.80)%比(29.22±2.26)%,(36.14±1.12)%比(43.69±2.78)%,P<0.05〕,病例组以上两种细胞在术后2周〔(27.15±1.71)%,(40.30±2.00)%〕较术前均明显升高(P<0.05)。对Treg与AFP进行相关性分析发现二者具有低度相关关系(r=0.48,P<0.05)。结论肝癌切除术能够在一定程度上改善肝癌患者的免疫功能,且Treg在肝癌的诊治及预后的判断中,可能具有一定辅助意义。