Age-associated parallel increase of Foxp3CD4 regulatory and CD44CD4 memory T cells in SJL/J mice

Effector/memory T cells (Tem) are required to maintain successful immunity, while regulatory T cells (Treg) are required to prevent excessive/uncontrolled inflammation and/or autoimmunity. Although both Tem and Treg cells are increased during aging, the relationship between the increased proportion of Foxp3⁺ Treg cells and CD44⁺ Tem cells with aging is not clearly understood. We found in this report that Foxp3⁺ Treg cells are increased in parallel with CD44⁺ Tem cells in SJL/J mice with aging, and that all Foxp3⁺ Treg cells are of CD44⁺ Tem phenotype, suggesting that the increased Foxp3⁺ Treg cells originated from the expanded pool of CD44⁺ Tem cells with aging. Our in vitro kinetic studies further suggested that Foxp3⁺ Treg cells are converted through the CD44⁺ stage. Furthermore, we observed that although the balance between Foxp3⁺ Treg and CD44⁺Foxp3⁻ Tem cells remained with aging, the aged mice have higher ratios of both Tem and Treg cells vs. naïve T cells resulting in the “shrunken” naïve T cell pools. Our results suggest that an age-associated imbalance of T cell repertoire is a mechanism that contributes to spontaneous occurrence of Hodgkin’s-like lymphoma in aged SJL/J mice.     

Regulatory T cells (CD4CD25FoxP3) expansion in systemic sclerosis correlates with disease activity and severity

Background

The role and function of T regulatory (Treg) cells have not been fully investigated in patients with systemic sclerosis (SSc).

Methods

Ten patients with SSc donated 20 ml of peripheral blood. Activity (Valentini) and severity (Medsger) scores for SSc were calculated for all patients. Healthy volunteers (controls) were matched to each patient by gender and age. CD4⁺ cells were separated using the MACS system. The numbers of Treg cells were estimated by flow cytometry after staining for CD4, CD25, and FoxP3 and calculated as patient-to-control ratio separately for each experiment. Correlations with activity and severity indices of the disease were performed. Twenty-four-hour production of TGF-β and IL-10 by activated CD4⁺ cells was measured by ELISA in culture supernatants.

Results

The numbers of Treg cells, expressed as patient-to-control ratio, correlated significantly with both activity and severity indices (r = 0.71, p = 0.034 and r = 0.67, p = 0.044, respectively). ELISA-measured production of TGF-β and IL-10 by CD4⁺ cells was similar in patients and controls.

Conclusions

Increased numbers of Treg cells are present in patients with SSc, correlating with activity and severity of the disease. This expansion of Treg cells was not accompanied, however, by heightened TGF-β or IL-10 production. Further studies to elaborate the causes and functional significance of Treg cell expansion in SSc are needed.     

老年COPD疾病进展与机体调节性T 细胞的关系分析

目的:探讨老年慢性阻塞性肺疾病(COPD)患者疾病进展与机体调节性T细胞(Treg)的关系。方法:选取我院收治的65例COPD患者(COPD组)以及同期在我院行体检的健康人群45例(正常对照组),将COPD患者分为急性期组41例及稳定期组24例,采用肺功能仪检测肺功能,采用酶联免疫吸附法检测血清γ-干扰素(IFN-γ)、白介素4(IL-4)、IL-17水平,采用流式细胞仪检测外周血CD4+CD25+Treg细胞比例。结果:与正常对照组比较,COPD患者的FEV1、FVC、PEF、FEV1/FVC、6MWT、血清IL-4水平、外周血CD4~+CD25~+Treg细胞比例均明显下降,血清IFN-γ、IL-17及Th1/Th2均显著升高。急性期COPD患者的CD4~+CD25~+Treg细胞比例较正常对照组显著升高,而正常对照组患者的CD4~+CD25~+Treg细胞比例较稳定组COPD患者显著升高,组间比较均有明显差异(P0.05)。结论:老年CODP患者体内存在免疫功能失调,调节性T细胞可能参与了老年COPD疾病的发病以及急性加重过程,导致患者出现肺功能改变。     

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.     

Early activation does not translate into effector differentiation of peripheral CD8T cells during the acute phase of Kawasaki disease

Early diagnosis of acute Kawasaki disease (KD), lying in the spectrum between infectious and autoimmune diseases, can be difficult. To clarify the role of peripheral CD8T cells in KD, we examined their activation, proliferation, maturation, and effector function by four-color flow cytometry. Compared to healthy/febrile controls, acute KD patients showed striking increase in early activation marker CD69⁺CD8T cells and maturation subsets, but HLA-DR⁺CD8T cells representing late activation did not increase. Although Ki67⁺CD8T cells reflecting ongoing cell division increased in acute KD and febrile controls, absolute numbers of CD8T cells and maturation subsets decreased in acute KD versus healthy controls. Effector cells were lower in acute than in convalescent KD. Perforin⁺CD8T cells, denoting cytolytic activity, were lower in KD patients versus febrile controls. CD69⁺CD8T cells increase in acute KD but effector differentiation is absent. CD69⁺CD8T cells could be a marker to determine disease progression, treatment response, and convalescence in acute KD.     

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.     

Small numbers of residual tumor cells at the site of primary inoculation are critical for anti-tumor immunity following challenge at a secondary location

Luciferase-transduced B16 murine melanoma cells (luc-B16) inoculated in ear skin do not form tumors but prevent tumor formation by luc-B16 cells injected into the footpad. To determine the requirements for such immunity, we followed the fate of luc-B16 cells following ear injection. Surprisingly, small numbers of viable luc-B16 cells were detected in tumor-free mouse skin for up to 60 days post-inoculation. After 1 week, the number of Foxp3⁺CD4⁺CD25⁺ T cells (along with foxp3 mRNA expression) increased rapidly in the injected ear skin. Residual tumor cells in ears were reduced in mice treated with anti-CD25 mAb and in CD4-deficient mice, but increased in CD8-deficient mice. Strikingly, the loss of luc-B16 cells in the ear skin, either spontaneously or following amputation of the injected ear, resulted in significantly enhanced tumor formation by parental and luciferase-expressing B16 cells after footpad injection. These studies suggest that small numbers of tumor cells (possibly regulated by CD4⁺CD25⁺ regulatory T cells expressing Foxp3) are required for effective host anti-tumor responses at alternate inoculation sites.     

Mathematical modeling of allergy and specific immunotherapy: Th1-Th2-Treg interactions

Regulatory T cells (Treg) have recently been identified as playing a central role in the immune response to allergens and during allergen-specific immunotherapy. We have extended our previous mathematical model describing the nonlinear dynamics of Th1-Th2 regulation by including Treg cells and their major cytokines. We hypothesize that immunotherapy mainly acts on the T cell level and that the decisive process can be regarded as a dynamical phenomenon. The model consists of nonlinear differential equations which describe the proliferation and mutual suppression of different T cell subsets. The old version of the model was based upon the Th1-Th2 paradigm and is successful in describing the “Th1-Th2 switch” which was considered to be the decisive event during specific immunotherapy. In recent years, however, the Th1-Th2 paradigm has been questioned and therefore, we have investigated a modified model in order to account for the influence of a regulatory T cell type. We examined the extended model by means of numerical simulations and analytical methods. As the modified model is more complex, we had to develop new methods to portray its characteristics. The concept of stable manifolds of fixed points of a stroboscobic map turned out to be especially important. We found that when including regulatory T cells, our model can describe the events in allergen-specific immunotherapy more accurately. Our results suggest that the decisive effect of immunotherapy, the increased proliferation of Treg and suppression of Th2 cells, crucially depends on the administration of high dose injections in short intervals right before the maintenance phase sets in. Empirical protocols could therefore be improved by optimizing this step of therapy.     

Dendritic cells reduce number and function of CD4+CD25+ cells in cytokine-induced killer cells derived from patients with pancreatic carcinoma

Aim and background: CD4⁺CD25⁺ cells are described as professional regulatory/suppressor T cells that are crucial for the prevention of spontaneous autoimmune diseases. They play an important role in maintaining a balanced peripheral immune system. On the other hand, it has been suggested that regulatory T cells (Treg) suppress antitumor immune responses after tumor-specific vaccinations. Therefore, we determined the percentage of regulatory T cells in cytokine-induced killer (CIK) cells, an effector cell population with high impact for adoptive immunotherapeutic strategies. Results: CIK cells showed strong induction of CD4⁺CD25⁺ cells with high secretion of interleukin 10 (IL-10) after unspecific stimulation of the TCR complex and stimulation with interleukin 2. Depletion of CD25⁺ cells led to an increase in cytotoxic activity and a reduction of IL-10 release. A more pronounced reversal of suppression could be induced by coculture of CIK cells with dendritic cells (DCs). After coculture of CIK cells with DCs, the number of CD4⁺CD25⁺ cells as well as the IL-10 concentration in the supernatant decreased, and the cytotoxic activity against pancreatic carcinoma cells increased. This was shown for cells from healthy donors as well as for cells from patients with pancreatic carcinoma. Conclusion: Our established effector cells possess some regulatory features induced by unspecific TCR-activation that could be prevented by coculture with DCs. CIK cells have desirable properties for immunotherapeutical approaches, especially after coculture with DCs, which could be used additionally for induction of a specific immune response.     

供体来源ImDex联合抗原特异性Treg保护大鼠肝脏移植物的研究

目的:探讨供体来源低剂量未成熟树突状细胞外来体(immature dendritic cells exosome,im Dex)联合供体抗原特异型调节性T细胞(regulatory t cells,Tregs)对于肝脏移植物的保护作用。方法:以BN-Lewis大鼠为供受体,建立大鼠原位肝移植模型。利用超高速梯度离心法获得im Dex,采用流式细胞术鉴定该im Dex的表型。不同剂量im Dex用于本移植模型,生存分析探究其对肝脏移植物的保护作用及该作用与剂量的相关关系。利用磁珠分选技术获得Treg,混合淋巴细胞培养获得供体抗原特异性Treg,将不同性质的Treg用于移植受体,验证抗原特异性Treg保护肝脏移植物。进一步探究两者联合使用的效果,应用免疫荧光、流式细胞术研究Treg在移植受体中的分布。结果:超高速梯度离心法分选出的im Dex具有im DC表型,其保护肝脏移植物的最佳作用剂量为20μg,Treg发挥保护移植物作用具有抗原特异性。两者联合应用组生存时间长于对照组(P0.05)。病理显示,输注的Treg分布于受体移植物。结论:Im Dex联合抗原特异性Treg可以有效保护大鼠肝脏移植物。     

Th17/Treg 细胞在银屑病的发病机制研究进展

Th17细胞和Treg细胞是CD4+T细胞在不同细胞因子环境中分化出的新亚群,发挥不同的生物学效应,使机体的免疫系统处于平衡状态.Th17/Treg细胞失衡可引起一系列自身免疫性疾病.银屑病是与遗传、免疫异常有关的皮肤炎症性疾病,其发病机制尚不清楚.越来越多的研究发现,Th17细胞增多和Treg细胞减少及其分泌的细胞因子在银屑病的发病中有着重要作用.本文围绕这一机制综述了近年来有关Th17细胞、Treg细胞在银屑病发病机制中作用的研究,帮助我们更深入地了解银屑病的发病机制并为今后临床诊断和治疗提供依据.     

Tolerance and immunity in a mathematical model of T-cell mediated suppression

Regulatory CD4+CD25+ T cells play a major role in natural tolerance to body components and therefore are relevant to understand the self-non-self discrimination by the immune system. The most pressing theoretical question, regarding the fact that these regulatory cells perform their function through linked recognition of the APCs, is how this "non-specific" mechanism permits a proper balance between tolerance and immunity that is compatible with an effective self-non-self discrimination. To tackle this issue, we develop a numerical simulation, which extends a previous mathematical model of T-cell-mediated suppression to include the thymic generation and the peripheral dynamics of many T cell clones. This simulation can mimic the capacity of the immune system to establish natural tolerance to self-antigens and reliably mount immune responses to foreign antigens. Natural tolerance is based on ubiquitous and constitutive self-antigens, which select and sustain clones of specific regulatory cells. Immune responses to foreign antigens are only achieved if they displace the self-antigens from the APCs, leading to a loss of the regulatory cells, and/or if the foreign antigen introduction entails a sharp increase in the total number of APCs. Meaningful behavior is obtained even if differentiation of regulatory cells in the thymus is antigen non-specific, but requires that a minimum number of new T cells enter the periphery per unit of time, and that the repertoire is selected so that anti-self-affinities are within a proper interval. We conclude that positive selection is required to generate a sufficiently high frequency of self-antigen specific regulatory cells that reliably mediate natural tolerance. Negative selection is required to avoid the emergence at the periphery of very high affinity anti-self-regulatory cells that will make the tolerant state so robust that it could no be broken by the introduction of a foreign antigen. This result highlights the importance of repertoire selection in dominant tolerance proposing a novel role for the processes of positive and negative selection within this framework.     

Rapamycin in combination with donor-specific CD4CD25Treg cells amplified in vitro might be realize the immune tolerance in clinical organ transplantation

It is an urgent need to induce and keep the donor-specific immune tolerance without affecting the function of normal immune defense and immune surveillance in clinical organ transplantation. Large number of studies showed that both the establishment of donor-recipient chimerism and the application of antibodies or drugs could obtain the donor-specific immune tolerance in animal transplantation model. However, the former as treatment of clinical practice has a poor feasibility, the latter has a very low success rate in clinical organ transplantation. There is a group of naturally occurring CD4⁺CD25⁺ regulatory T cells (Tregs) that mediate immune tolerance by suppressing alloreactive T cells in vivo. These cells are unable to curb the occurrence of allograft rejection owing their low content. And donor-specific Tregs amplified in vitro alone can not induce donor-specific immune tolerance for recipient. Rapamycin (RPM) as a proliferation signal inhibitor, studies have shown it can effectively inhibit allograft rejection and maybe contribute to induction of immune tolerance. But there exist still many dose-dependent adverse reactions which could prevent the establishment of immune tolerance and reduce the life quality of recipients in the clinical application of RPM. Therefore, we speculate a small amount of RPM combined with donor-specific Tregs amplified in vitro may be not only induce the achievement of donor-specific tolerance, but also reduce or eliminate the side effects of RPM in clinical organ transplantation.     

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。