Relationship between regulatory and type 1 T cells in dogs with oral malignant melanoma

Recent data suggest a decreased prevalence of IFN‐γ‐producing T lymphocytes (Type 1 T cells) in tumor‐bearing hosts. Moreover, it has been reported that Treg have a strong impact on the activation and proliferation of CD4 (+) and CD8 (+) lymphocytes; however, no previous reports have described the relationship between Treg and the progression of tumor, or Type 1 T cell populations in dogs with malignant tumor. In this study, the percentage of Treg, Th1, and Tc1 in the peripheral blood of dogs with oral malignant melanoma and healthy dogs was measured and compared. Although the percentages of Th1 and Tc1 in dogs with oral malignant melanoma were less than those in healthy dogs (Th1: P < 0.01, Tc1: P < 0.05), the percentage of Treg was increased (P < 0.01). A significant inverse correlation between the percentage of Tc1 and the clinical tumor stage (P < 0.01), and a significant correlation between that of Treg and the clinical tumor stage (P < 0.001) was found. Moreover, there was a significant inverse correlation between the percentages of Treg and Th1 (P < 0.05) or Tc1 (P < 0.001). In conclusion, the percentage of Treg increases with the tumor stage in the peripheral blood of dogs with oral malignant melanoma. In dogs, Treg appears to suppress Type 1 immunity, which may be responsible for anti‐tumor responses.     

Rap1A regulates generation of T regulatory cells via LFA-1-dependent and LFA-1-independent mechanisms

The small GTPase Rap1A has a critical role in regulating cell-matrix and cell-cell adhesion. In T lymphocytes, Rap1A mediates LFA-1 activation and LFA-1-mediated adhesion. LFA-1 reduces the threshold of TCR signals for low affinity ligands. Previously, we determined that mice expressing constitutively active Rap1A on T cells have increased frequency of CD103⁺ T regulatory cells (Treg). We hypothesized that Rap1A-GTP might affect the differentiation of Treg by regulating LFA-1 activation. Using Foxp3-GFP-KI, LFA-1-KO and Rap1A-GTP-Tg mice we determined that Rap1A has an active role in the development of thymic Treg but LFA-1 is not mandatory for this function. Rap1A is also involved in the generation of peripheral Treg and this effect is mediated via LFA-1-dependent and LFA-1-independent mechanisms. Identification of the signaling pathways via which Rap1-GTP contributes to the differentiation of Treg will provide new insights to the function of Rap1A and to designing targeted approaches for generation of Treg for therapeutic applications.     

Optimal number of regulatory T cells

The adaptive immune system of a vertebrate may attack its own body, causing autoimmune diseases. Regulatory T cells suppress the activity of the autoreactive effector T cells, but they also interrupt normal immune reactions against foreign antigens. In this paper, we discuss the optimal number of regulatory T cells that should be produced. We make the assumptions that some self-reactive immature T cells may fail to interact with their target antigens during the limited training period and later become effector T cells causing autoimmunity, and that regulatory T cells exist that recognize self-antigens. When a regulatory T cell is stimulated by its target self-antigen on an antigen-presenting cell (APC), it stays there and suppresses the activation of other naive T cells on the same APC. Analysis of the benefit and the harm of having regulatory T cells suggests that the optimal number of regulatory T cells depends on the number of self-antigens, the severity of the autoimmunity, the abundance of pathogenic foreign antigens, and the spatial distribution of self-antigens in the body. For multiple types of self-antigen, we discuss the optimal number of regulatory T cells when the self-antigens are localized in different parts of the body and when they are co-localized. We also examine the separate regulation of the abundances of regulatory T cells for different self-antigens, comparing it with the situation in which they are constrained to be equal.     

人类免疫缺陷病毒1型同性恋感染者与健康人群Th17/Treg平衡状况的比较研究

通过探讨人类免疫缺陷病毒1型(HIV-1)同性恋感染者外周血中辅助性T细胞17(Th17)与CD4+CD25hiFoxp3+调节性T细胞(Treg)比例及Th17/Treg平衡状态与疾病进展的关系,初步阐明Th17/Treg失衡在HIV发病机制中的作用和意义。选取54例未经抗病毒治疗的HIV感染者,另有32名健康志愿者作为正常对照。分离外周血单核细胞后,利用流式细胞技术检测Th17和Treg水平。结果表明,在HIV感染者外周血中Th17比例明显低于正常对照组(0.68±0.35vs1.42±0.86,P<0.001),Treg比例明显高于正常对照(6.15±2.12vs4.50±0.76,P<0.001),导致HIV感染者中Th17/Treg比例较正常对照显著降低(0.12±0.07vs0.31±0.17,P<0.001)。研究还发现,Th17/CD4比例与CD4+T细胞计数正相关(r=0.371,P<0.05),与病毒载量不相关;Treg/CD4比例与CD4+T细胞计数负相关,与病毒载量正相关(r=-0.402,P<0.05;r=0.447,P<0.001)。此外,Th17/Treg比例与CD4+T细胞计数正相关,与病毒载量负相关(r=0.525,P<0.001;r=-0.318,P<0.05)。结果提示,HIV感染中存在Th17/Treg失衡现象,与疾病进程密切相关,可能在HIV进展中具有重要作用。     

哮喘患者外周血Treg和Th1/Th2的变化及其与哮喘病情的关系

目的：探讨哮喘患者外周血调节性T细胞（Treg）以及辅助性T细胞（Th1/Th2）的比例的变化,探讨其在哮喘的临床治疗中的作用。方法：80例哮喘患者（哮喘组）按临床表现分为急性发作期组（54例）和缓解期组（26例）,同时选择50例健康体检者。应用流式细胞仪检测上述各组外周血CD4＋CD25＋Foxp3＋Treg、CD4＋IFN-γ＋Th1和CD4＋IL-4＋Th2细胞水平,并进行统计学分析。结果：哮喘组CD4＋CD25＋Foxp3＋Treg水平亦明显低于正常对照组（P〈0.05。其中急性发作期组Treg水平明显低于缓解期组和正常对照组（P〈0.05）。而哮喘组Th1/Th2比值显著低于对照组（P〈0.05）,且在哮喘急性发作组中Th1/Th2比值显著低于缓解期组和正常对照组（P〈0.05）。结论：提示Treg和Th在哮喘的发生和发展中起着重要的作用。     

Treatment of diabetes in NOD mice by gene transfer of Ig-fusion proteins into B cells: role of T regulatory cells

We previously reported that retrovirally mediated gene expression of Ig fusion proteins leads to specific immunologic tolerance and successful treatment of autoimmune conditions. Thus, a single dose of GAD65-IgG- or (Pro) Insulin-IgG-transduced B cells delays the onset and decreases the incidence of diabetes in young (7-12 weeks old) NOD female mice. Herein, we tested the role of regulatory T cells by in vivo treatment with anti-CD25 before B-cell gene therapy or by in vitro ablation of CD25+ cells from tolerized hosts in an adoptive transfer model. Our results demonstrate that anti-CD25 treatment, like cyclophosphamide, partially blocks the efficacy of gene therapy for tolerance. Moreover, B-cell therapy is effective at preventing diabetes transfer by female T cells (from older diabetic mice) into intact male recipients with normal islets, but failed to do so in NOD-scid recipients. This is due in part to homeostatic proliferation but also to the absence of CD25+ T cells in the latter hosts. Tolerance induced in younger NOD females can be stably transferred to NOD-scid recipients. However, physical removal of CD25+ cells abrogates the transfer of tolerance. Therefore, we conclude that CD4+, CD25+ regulatory T cells are required for the induction as well as maintenance of tolerance in this gene therapy model. The phenotype of these induced regulatory T cells is under investigation.     

FoxP3+ regulatory T cells are not important for rotavirus clearance or the early antibody response to rotavirus

Regulatory T cells produce TGF-β that contributes to IgA induction by intestinal commensal bacteria but their importance in IgA responses to pathogens has not been determined. Immunity against the enteropathogen, rotavirus, is dependent on intestinal IgA, but whether FoxP3⁺ regulatory T cells contribute to this IgA is unknown. Infection with rotavirus increased the numbers of intestinal FoxP3⁺ regulatory T cells. Depletion of FoxP3⁺ regulatory T cells altered leukocyte activation but did not significantly alter rotavirus clearance or specific antibody levels. These data suggest FoxP3⁺ regulatory T cells are not critical for the early antibody response to rotavirus infection.     

Activated T cells complicate the identification of regulatory T cells in rheumatoid arthritis

Most cell surface markers for CD4⁺CD25⁺ regulatory T cells (Tregs) are also expressed by activated non-regulatory T cells. Recently, CD127 down-regulation was found to identify functional Tregs in healthy individuals, but there are no data from patients with inflammatory conditions. We examined peripheral blood mononuclear cells (PBMC) from rheumatoid arthritis patients with active inflammation and from healthy controls, and found that CD4⁺ T cells contained an equal proportion of CD25⁺CD127⁻/low cells in both groups. In patients, not all these cells expressed intracellular FOXP3. Upon activation by anti-CD3/anti-CD28, PBMC rapidly down-regulated CD127, while FOXP3 up-regulation was transitory and occurred in fewer cells. The activated cells were not anergic to restimulation and had no suppressive effects. The distinct kinetics indicate that the FOXP3⁻CD127⁻/low cells in rheumatoid arthritis patients most likely represent activated non-regulatory T cells. This complicates the use of CD127 for identification of Tregs in inflammatory diseases.     

Possible involvement of regulatory T cells in tumor onset and progression in primary breast cancer

Background  The FOXP3 mRNA expression and the other regulatory T cell-related molecules were investigated and compared with clinicopathological parameters in human primary breast cancer. Method  This study included 136 breast cancer patients operated in our department from 2003 to 2006. Total RNA was extracted from frozen normal breast and breast cancer tissues, and the expression of FOXP3, IL-10, TGFβ1 and CCL22 mRNA was evaluated using quantitative real-time RT-PCR. Result   FOXP3, IL-10, TGFβ1 and CCL22 mRNA expressions were significantly higher in cancer tissue than in normal tissue, not only at pT1, 2, and 3 stages but also at the DCIS stage. There were positive correlations between FOXP3 and IL-10, FOXP3 and TGFβ1, as well as FOXP3 and CCL22 mRNA expressions, respectively. FOXP3 and IL-10 mRNA expressions were significantly upregulated in PgR-negative or HER2-positive tumors. Conclusion  These results suggest that regulatory T cells are involved in tumor onset and progression in human primary breast cancer, possibly contributing to poor prognosis of patients with breast cancer.     

Paclitaxel may inhibit autoimmune diseases by sparing or increasing the number of CD4(+) CD25(+) regulatory T cells

Paclitaxel, a representative of taxanes, exhibits cytotoxic effects against a broad range of tumors. Strikingly, an emerging body of data suggests that paclitaxel also exerts effects on immune system by stimulating anti-tumor and anti-autoimmunity effects, supporting the idea that paclitaxel suppresses tumor through several mechanisms and not solely through inhibiting cell division. Based on the accumulating data, we hypothesized that paclitaxel may inhibit autoimmune diseases by sparing or actively increasing the number of CD4(+) CD25(+) Treg cells. The hypothesis, if proved to be correct, will significantly improve our understanding of the tumor immunity, autoimmunity and its related pathological effects. It will influence our choice on immunosuppressive drugs for cancer patients with autoimmune diseases. It will also impact the immunotherapy for tumors.     

Preferential migration of regulatory T cells mediated by gliomasecreted chemokines can be blocked with chemotherapy

Despite the immunogenicity of glioblastoma multiforme (GBM), immune-mediated eradication of these tumors remains deficient. Regulatory T cells (Tregs) in the blood and within the tumor microenvironment of GBM patients are known to contribute to their dismal immune responses. Here, we determined which chemokine secreted by gliomas can preferentially induce Treg recruitment and migration. In the malignant human glioma cell lines D-54, U-87, U-251, and LN-229, the chemokines CCL22 and CCL2 were detected by intracellular cytokine analysis. Furthermore, tumor cells from eight patients with GBM had a similar chemokine expression profile. However, only CCL2 was detected by enzyme-linked immunosorbent assay, indicating that CCL2 may be the principal chemokine for Treg migration in GBM patients. Interestingly, the Tregs from GBM patients had significantly higher expression levels of the CCL2 receptor CCR4 than did Tregs from healthy controls. Glioma supernatants and the recombinant human chemokines CCL2 and CCL22 induced Treg migration and were blocked by antibodies to the chemokine receptors. Production of CCL2 by glioma cells could also be mitigated by the chemotherapeutic agents temozolomide and carmustine [3-bis (2-chloroethyl)-1-nitrosourea]. Our results indicate that gliomas augment immunosuppression by selective chemokine-mediated recruitment of Tregs into the tumor microenvironment and that modulating this interaction with chemotherapy could facilitate the development of novel immunotherapeutics to malignant gliomas. Justin T. Jordan and Wei Sun are contributed equally to this work. An erratum to this article can be found at     

Immune responses to p53 in patients with cancer:enrichment in tetramer+ p53 peptide-specific T cells and regulatory T cells at tumor sites

Objective: A majority of human cancers, including head and neck cancer (HNC), overexpress p53. Although T cells specific for wild-type (wt) sequence p53 peptides are detectable in the peripheral blood of patients with HNC, it is unknown whether such T cells accumulate in tumor-involved tissues. Also, the localization of regulatory T cells (Treg) to tumor sites in HNC has not been investigated to date. Methods: Tumor infiltrating lymphocytes (TIL), tumor-involved or non-involved lymph node lymphocytes (LNL) and peripheral blood mononuclear cells (PBMC) were obtained from 24 HLA-A2.1+ patients with HNC. Using tetramers and four-color flow cytometry, the frequency of Treg and CD3+CD8+ T cells specific for wt p53 epitopes as well as their functional attributes were determined. Results: The CD3+CD8+ tetramer+ cell frequency was significantly higher (P<0.001) in TIL than autologous PBMC as was the percentage of CD4+CD25+ T cells (P<0.003). TIL were enriched in FOXp3+, GITR+ and CTLA-4+ Treg. CD8+ TIL had low expression and produced little IFN- after ex vivo stimulation relative to autologous PBMC or PBMC from NC. Conclusions: Anti-wt p53 epitope-specific T cells and Treg preferentially localize to tumor sites in patients with HNC. However, despite enrichment in tumor peptide-specific T cells, the effector cell population (CD3+CD8+) in TIL or PBMC was unresponsive to activation in the tumor microenvironment enriched in Treg.     

Advantage of having regulatory T cells requires localized suppression of immune reactions

The immune system of vertebrates may attack its own body and cause autoimmunity diseases. To prevent autoimmunity, regulatory T cells suppress the activity of the autoreactive effector T cells, but they also interrupt normal immune reactions against foreign antigens. In this paper, we discuss the advantage of having some regulatory T cells by considering the host's ability of coping with foreign antigens and the harm of autoimmunity. Assumptions are as follows: the immature T cells reactive to abundant self-antigens are eliminated, those reactive to rare self-antigen will become regulatory T cells, and those that fail to interact with the antigens to which they are reactive will become effector T cells. Some self-reactive immature T cells may fail to interact with their own target antigens during the limited training period, and will later become effector T cells, causing autoimmunity. Analysis suggests that, having some regulatory T cells can never be advantageous to the host, if activated regulatory T cells suppress effector T cells at any location of the body (global suppression). In contrast, producing some regulatory T cells can be beneficial, if the body is composed of many compartments and regulatory T cells suppress the immune reactions only within the same compartment (localized suppression). This requires regulatory T cells to stop circulating once they are activated by their own target self-antigens.     

1型调节性T细胞的表型和功能

1型调节性T细胞(Tr1)在免疫耐受的诱导和维持过程中发挥重要作用。Tr1细胞通常在免疫耐受的环境中由外来抗原诱导产生,通过产生高水平的IL-10而发挥免疫抑制作用。而CD4 CD25 调节性T细胞(Tregs)可在胸腺中天然产生也可在外周被抗原诱导产生,通过细胞接触发挥抑制作用。现对Tr1细胞的表型、功能及其抑制作用机制等方面的研究进展进行综述。     

Effect of regulatory T cells and adherent cells on the expansion of HBcAg-specific CD8 T cells in patients with chronic hepatitis B virus infection

Patients with chronic HBV infection show poor immune response to HBV-specific CD8⁺ T cells. Several studies demonstrate that regulatory T cells (Treg) and dendritic cells (DC) are important to maintain peripheral immune tolerance. In this study, we investigated the effects of CD4⁺CD25⁺Treg and/or the adherent cells (AC) on the proliferation of HBc18-27-specific CD8⁺ T cells (c18-27-CD8Ts) in response to in vitro stimulation. The frequency of c18-27-CD8Ts in four different mixed leukocyte reactions (MLRs) were analyzed using an HLA-A2-HBc18-27 tetramer. The data indicated that the median percentage of c18-27-CD8Ts in four different MLRs were significant difference in patients with chronic HBV infection. Our results showed that Treg and/or AC might suppress the frequency of HBc18-27-specific CD8⁺ T cell proliferation in response to in vitro stimulation in chronic HBV patients, and AC might be more effective than Treg.