The development of IL-17/IFN-γ-double producing CTLs from Tc17 cells is driven by epigenetic suppression of Socs3 gene promoter

The plasticity of T lymphocytes induced by epigenetic modifications of gene promoters may play a pivotal role in controlling their effector functions, which are sometimes causally associated with immune disorders. IL -17-producing T cells, which induce type 17 immune responses, are newly identified pathogenic effector cells. The type 1 signature cytokine IFN-γ strongly inhibits their differentiation, indicating a mutually exclusive relationship between type 17- and type 1-immune responses. However, many reports indicate the presence of a unique IL-17/IFN-γ-double producing T-cell subset in various inflammatory settings, although the mechanisms responsible for their development and their precise functions remain unclear. Here, we demonstrate that IL-12 permits the conversion of mouse IL-17-producing CD8(+) T (Tc17) cells to IL-17/IFN-γ-double producing CD8(+) T (Tc17/IFN-γ) cells, and that this conversion is due to repressive epigenetic modifications of Socs3 gene promoters. Moreover, we show that SOCS3 strongly regulates the capability of Tc17 cells to produce IL-17, in addition to regulating the expression of the type 17-master regulator RORγt. These findings elucidate the mechanisms underlying the conversion of Tc17 cells into Tc17/IFN-γ cells. As these cells are known to have potent antitumor activities, manipulation of these conversion mechanisms for therapeutic tumor immunity may be possible.     

IL-17/IFN-γ double producing CD8+ T (Tc17/IFN-γ) cells: a novel cytotoxic T-cell subset converted from Tc17 cells by IL-12

It has been reported that IFN-γ-producing CD8(+) T (Tc1) cells express cytotoxic molecules such as perforin and granzyme B to exhibit higher cytotoxicity against tumor cells compared with Tc2 cells. However, the critical role of IL-17-producing CD8(+) T (Tc17)-cell subsets in tumor immunity remains unclear. Tc17 cells differentiated from naive CD8(+) T cells did not possess cytotoxic molecules and exhibited no strong cytotoxicity. However, when Tc17 effector cells were further cultured with IL-12, they converted into IFN-γ-producing Tc17 cells, which mainly consisted of IL-17/IFN-γ double-producing cells (Tc17/IFN-γ). IL-12-converted Tc17 cells also acquired cytotoxic function in addition to IFN-γ producibility. Moreover, they showed strong anti-tumor activity both in vitro and in vivo as well as Tc1 cells. Among four distinct subsets in IL-12-converted Tc17 cell populations, the isolated Tc17/IFN-γ cells exhibited cytotoxicity as well as IFN-γ-producing Tc1-like cells. Thus, we first indicate direct evidence that Tc17/IFN-γ cells, which were plastically converted from non-cytotoxic Tc17 cells by IL-12, exhibited strong anti-tumor activity as well as Tc17 cell-derived Tc1-like cells.     

Human immunodeficiency virus-1 infection protects against a Tc1-to-Tc2 shift in CD8(+) T cells

Despite the reports of dysfunction of the lytic abilities of CD8(+) T cells during human immunodeficiency virus-1 (HIV-1) disease progression, the effects of infection on the noncytolytic functions of CD8(+) T cells have not been well characterized to date. We examined the effect of HIV-1 infection on the cytokine and chemokine responses of peripheral blood-derived CD8(+) T cells in an in vitro system. Activation of HIV-1-infected CD8(+) T cells with phytohemagglutinin resulted in a 4- to 8-fold increase in the production of macrophage inflammatory protein (MIP)-1α, MIP-1β, regulated on activation normal T-cell expressed and secreted, and interleukin (IL)-16. Treatment of activated HIV-1-infected CD8(+) T cells with anti-CD3 monoclonal (M) antibody (Ab) and IL-15 induced strong production of interferon-γ (IFN-γ). Treatment of cells with anti-IL-12 MAb and IL-4 to induce a Tc1-to-Tc2 shift resulted in no change in viral production levels or IFN-γ production within the HIV-1-infected CD8(+) T cell population. Initiation of a Tc2-to-Tc1 shift resulted in a 6-fold increase in HIV-1 replication and 2- to 3-fold higher levels of IFN-γ, demonstrating that infection can protect against a Tc1-to-Tc2 shift in CD8(+) T cells.     

Expansion of regulatory CD8+ CD25+ T cells after neonatal alloimmunization

Transplantation tolerance induced by neonatal injection of semi-allogeneic spleen cells is associated with a pathological syndrome caused by T helper type 2 (Th2) differentiation of donor-specific CD4(+) T lymphocytes. We have shown previously that this Th2-biased response is inhibited by host CD8(+) T cells. Herein, we demonstrate that upon neonatal immunization with (A/J × BALB/c)F(1) spleen cells, BALB/c mice expand a population of CD8(+) T cells expressing both CD25 and forkhead box P3 (FoxP3) markers. In this setting, CD8(+) CD25(+) T cells predominantly produce interferon (IFN)-γ and interleukin (IL)-10 and are efficient in controlling IL-4, IL-5 and IL-13 production by donor-specific CD4(+) T cells in vitro. CD8(+) FoxP3(-) T cells are single producers of IFN-γ or IL-10, whereas CD8(+) FoxP3(+) T cells are double producers of IFN-γ and IL-10. We further demonstrate that IFN-γ and IL-10 are two major cytokines produced by CD8(+) T cells involved in the in vivo regulation of Th2-type pathology. In this setting, we conclude that neonatal alloimmunization induces the expansion of several regulatory CD8(+) T cells which may control Th2 activities via IFN-γ and IL-10.     

新生儿、儿童及成人外周血CD4~+和CD8~+T细胞分泌IFN-γ及IL-4变化的研究

本研究应用相应的荧光标记的抗体 ,从单细胞水平检测了正常无家族过敏史的 17例新生儿、 18例儿童及 10例成人外周血CD4+ 、CD8+ 细胞分泌IFN γ、IL 4的变化 ,结果显示产生IFN γ的CD4+ (Th1)和CD8+ (Tc1)细胞、产生IL 4的CD4+ (Th2 )细胞及同时产生IFN γ/IL 4的CD4+ (Th0 )细胞 ,随着年龄的增长而明显增高 (P <0 0 5 ) ,Th1/Th2比值也明显升高 (P <0 0 5 )。表明从新生儿期至成人Th1、Tc1、Th2、Th0有一个正常生理性增加过程 ,其中Th1、Tc1变化更为显著 ,可能与抗原暴露接触有关。     

ST2 deletion enhances innate and acquired immunity to murine mammary carcinoma

ST2 is a member of the IL-1 receptor family and IL-33 was recently identified as its natural ligand. The IL-33/ST2 pathway regulates Th1/Th2 immune responses in autoimmune and inflammatory conditions, but the role of ST2 signaling in tumor growth and metastasis has not been investigated. We aimed to investigate whether ST2 gene deletion affects tumor appearance, growth, and metastasis, and antitumor immunity in an experimental metastatic breast cancer model. Deletion of ST2 in BALB/c mice bearing mammary carcinoma attenuated tumor growth and metastasis, which was accompanied by increased serum levels of IL-17, IFN-γ, and TNF-α and decreased IL-4. Tumor-bearing ST2-/- mice had significantly higher percentages of activated CD27high CD11bhigh NK cells, CD69+ and KLRG- NK cells and higher cytotoxic activity of splenocytes, NK cells, and CD8+ T cells in vitro. A significantly higher number of NK cells expressing IFN-γ were found in ST2-/- mice compared with WT recipients. In vivo depletion of CD8+ or NK cells revealed a key role for NK cells in enhanced antitumor immunity in ST2-/- mice. We report for the first time that suppressed breast cancer progression and metastasis in mice lacking ST2 corresponds mainly with enhanced cytotoxic activity of NK cells, and increased systemic Th1/Th17 cytokines.     

Early Th1/Th2 cell polarization in the absence of IL-4 and IL-12: T cell receptor signaling regulates the response to cytokines in CD4 and CD8 T cells.

Differentiation of developing T cells into the type 1 (IFN-gamma-producing) or type 2 (IL-4-producing) subsets is a central theme of immune regulation. The balance of IL-4 and IL-12 present during T cell activation has been considered the major influence on type 1 versus type 2 development. Here we show that CD4 T cells can become biased towards type 1 or type 2 phenotypes during their initial activation in the absence of IL-4 or IL-12. This type of regulation is dependent on the balance of MAPkinase, protein kinase C, and calcineurin signaling after TCR engagement. Later maturation of Th1 or Th2 effectors is dependent on IL-12 or IL-4. However Tc1 CD8 effector development is independent of IL-12, and Tc2 cell generation requires both appropriate TCR signals and IL-4 early in effector development. Using an altered peptide ligand to stimulate TCR transgenic T cells, we show that altered signaling regulates the numbers of CD8 cells capable of developing into Tc2 effectors, and also their responsiveness to IL-4. Together, the results support a two-stage model of differentiation in which intermediate cells biased towards the type 1 or type 2 pathways after activation, are subsequently matured in response to IL-12 or IL-4, respectively.     

Monocytes differentiated with GM-CSF and IL-15 initiate Th17 and Th1 responses that are contact-dependent and mediated by IL-15

Distinct types of DCs are generated from monocytes using GM-CSF with IL-4 (IL4-DC) or IL-15 (IL15-DC). IL15-DCs are potent inducers of antigen-specific CD8(+) T cells, display a phenotype similar to CD14(+) cells commonly described in chronically inflamed tissues, and produce high levels of IL-1β and IL-15 in response to TLR4 stimulation. As these cytokines promote Th17 responses, which are also associated with inflammatory diseases, I hypothesized that TLR-primed IL15-DCs favor Th17 activation over IL4-DCs. Compared with IL4-DCs, IL15-DCs stimulated with TLR agonists secreted significantly higher concentrations of the Th17-promoting factors, IL-1β, IL-6, IL-23, and CCL20, and lower levels of the Th1 cytokine, IL-12. In addition, IL15-DCs and not IL4-DCs up-regulated IL-15 on the cell surface in response to TLR agonists. IL15-DCs primed with TLR3 or TLR4 agonists triggered Th17 (IL-17, IL-22, and/or IFN-γ) and Th1 (IFN-γ) responses, whereas IL4-DCs primed with the same TLR agonists activated Th1 (IFN-γ) responses. Secretion of IL-17 and IFN-γ required contact with TLR-primed IL15-DC, and IFN-γ production was mediated by membrane-bound IL-15. These findings identify key differences in monocyte-derived DCs, which impact adaptive immunity, and provide primary evidence that IL-15 promotes Th17 and Th1 responses by skewing monocytes into IL15-DC.     

IL-21 Is Increased in Peripheral Blood of Emphysema Mice and Promotes Th1/Tc1 Cell Generation In Vitro

Interleukin-21 (IL-21) has been reported to be involved in many Th1-associated diseases. However, the alteration and immune regulation of IL-21 in emphysema remains unknown. In this study, we tested the levels of IFN-γ and IL-21 and the frequencies of Th1 and Tc1 in peripheral blood from cigarette smoke (CS)-exposed mice and air-exposed mice and explored the effect of IL-21 on generation of Th1 and Tc1 cells in vitro. It was found that the levels of IFN-γ and IL-21 and the frequencies of Th1, Tc1, CD4⁺ IL-21⁺, CD4⁺ IL-21R⁺, and CD8⁺ IL-21R⁺ T cells were much higher in CS-exposed mice. Moreover, the levels of IL-21 were correlated positively with Th1 cells and with Tc1 cells. Finally, the in vitro experiments showed that IL-21 could promote Th1/Tc1 cell generation in CS-exposed mice. These results indirectly provide evidence that IL-21 produced by CD4⁺ T cells could promote Th1/Tc1 response, leading to systemic inflammation in emphysema.     

Type 1 CD8^＋ T Cells are Superior to Type 2 CD8^＋ T Cells in Tumor Immunotherapy due to Their Efficient Cytotoxicity, Prolonged Survival and Type 1 Immune Modulation

CD8^＋ cytotoxic T （Tc） cells play a crucial role in host immune responses to cancer, and in this context, adoptive CD8^＋ Tc cell therapy has been studied in numerous animal tumor models. Its antitumor efficacy is, to a large extent, determined by the ability of Tc cells to survive and infiltrate tumors. In clinical trials, such in vitro-activated T cells often die within hours to days, and this greatly limits their therapeutic efficacy. CD8^＋ Tc cells fall into two subpopulations based upon their differential cytokine secretion. In this study, we in vitro generated that ovalbumin （OVA）-pulsed dendritic cell （DCovA）-activated CD8^＋ type 1 Tc （Tcl） cells secreting IFN-T, and CD8^＋ type 2 Tc （Tc2） cells secreting IL-4, IL-5 and IL-10, which were derived from OVA-specific T cell receptor （TCR） transgenic OT I mice. We then systemically investigated the in vitro and in vivo effector function and survival of Tcl and Tc2 cells, and then assessed their survival kinetics after adoptively transferred into C57BL/6 mice, respectively. We demonstrated that, when compared to CD8^＋ Tc2, Tcl cells were significantly more effective in perforin-mediated cytotoxicity to tumor cells, had a significantly higher capacity for in vivo survival after the adoptive T cell transfer, and had a significantly stronger therapeutic effect on eradication of well-established tumors expressing OVA in animal models. In addition, CD8^＋ Tcl and Tc2 cells skewed the phenotype of CD4^＋ T cells toward Thl and Th2 type, respectively. Therefore, the information regarding the differential effector function, survival and immune modulation of CD8^＋ Tcl and Tc2 cells may provide useful information when preparing in vitro DC-activated CD8^＋ T cells for adoptive T cell therapy of cancer.     

Role of antigen-presenting cells in the polarized development of helper T cell subsets: evidence for differential cytokine production by Th0 cells in response to antigen presentation by B cells and macrophages

Immune challenges can elicit polarized responses skewed towards the development of T helper type 1 (Th1) or Th2 T cell subsets. To determine if distinct antigen-presenting cells (APC) populations might selectively influence Th subset development, we studied the role of two key APC populations, B cells and macrophages, in the differentiation of effector Th populations from naive precursor Th in vitro. Antigen (Ag)-specific, naive CD4⁺ T cells were enriched from a mouse strain, AND, bearing a transgenic α/β T cell receptor (TCR) encoding reactivity with pigeon cytochrome c peptide 88-104. Peptide Ag was used throughout these studies so that differences in the uptake and processing by the two APC populations would not influence the results. Both APC populations, activated B cells and bone marrow-derived macrophages, supported the development of effector Th having the capacity to secrete high levels of cytokines when restimulated. Regardless of APC population present during effector development, exogenous interferon-γ (IFN-γ) and interleukin-4 (IL-4) had dominant effects on Th subset development. Thus, with both APC populations, effector Th generated in the presence of IFN-γ acquired a Th1-type cytokine profile, Th generated with IL-4 acquired a Th2-type cytokine profile, and Th generated without IFN-γ or IL-4 acquired a Th0-type cytokine profile. B cells and macrophages also had equivalent APC function in the restimulation of Th1 and Th2-like effectors, since only minor differences in cytokine production were noted for these effector populations when restimulated with the two APC populations. However, in 8 of 19 experiments, the Th0-like effector population generated in the presence of IL-2 differentially responded to restimulation with B cells and macrophages, secreting significantly more IFN-γ when restimulated with B cells, and significantly more IL-4 when restimulated with macrophages. We also found that Th effector populations recultured in IFN-γ or IL-4 assumed a more Th1 or Th2-like phenotype, respectively, regardless of their initial cytokine profile. We conclude that through a subtle capacity to skew cytokine production by a Th0 subset, different APC may selectively influence Th subset development under conditions of prolonged or chronic stimulation in an autocrine fashion.     

Diversion of CD4+ T cell development from regulatory T helper to effector T helper cells alters the contact hypersensitivity response

Cutaneous sensitization to reactive haptens and subsequent challenge results in a T cell-mediated response, contact hypersensitivity (CHS). Recent results from this laboratory have indicated that hapten sensitization induces two populations of reactive T cells: CD8⁺ T cells producing interferon (IFN)-γ which mediate the response and CD4⁺ T cells producing interleukin (IL)-4 and IL-10 which negatively regulate the magnitude and duration of the response. Since CD4⁺ T cell development to either IFN-γ- (Th1) or IL-4/IL-10- (Th2)-producing cells is dependent upon the cytokine environment during antigen priming, we hypothesized that CD4⁺ T cell induction in a Th1-promoting environment would not only alter the CD4⁺ T cell cytokine-producing phenotype but also the course of the CHS response. Administration of the Th1-promoting cytokine IL-12 during hapten sensitization resulted in a CHS response of greater magnitude following challenge and extended the duration of the response. In hapten-sensitized mice depleted of CD8⁺ T cells, treatment with IL-12 induced effector CD4⁺ T cells. Histological examination of challenged ear tissue from these mice indicated minimal edema and an acute mononuclear cell infiltration more typical of classical delayed-type hypersensitivity than CHS. Hapten-primed CD4⁺ T cells from IL-12 treated, sensitized mice produced IFN-γ, but not IL-4 in response to T cell receptor-mediated stimulation. Use of neutralizing anti-IFN-γ antibody indicated that IL-12 not only directly promoted Th1 development but also indirectly inhibited Th2 development through stimulation of IFN-γ production at the time of hapten sensitization. Overall, these results demonstrate that diversion of CD4⁺ T cell development to Th1 effector cells rather than to Th2 cells alters the efferent nature of CHS and removes a primary regulatory mechanism of the immune response.     

Production of IFN-γ by CD4(+) T cells in response to malaria antigens is IL-2 dependent

T-cell immune responses are critical for protection of the host and for disease pathogenesis during infection with Plasmodium species. We examined the regulation of CD4(+) T-cell cytokine responses during infection with Plasmodium berghei ANKA (PbA). CD4(+) T cells from PbA-infected mice produced IFN-γ, IL-4 and IL-10 in response to TCR stimulation at levels higher than those from uninfected mice. This altered cytokine response was dependent on parasitemia. To examine the specificity of the response, mice were adoptively transferred with CD4(+) T cells from OT-II TCR transgenic mice and were infected with PbA expressing OVA. Unexpectedly, CD4(+) T cells from the OT-II-transferred wild-type PbA-infected mice showed high levels of IFN-γ production after stimulation with OVA and the cells producing IFN-γ were not OT-II but were host CD4(+) T cells. Further investigation revealed that host CD4(+) T cells produced IFN-γ in response to IL-2 produced by activated OT-II cells. This IFN-γ response was completely inhibited by anti-CD25 mAbs, and this effect was not due to the block of the survival signals provided by IL-2. Furthermore, IFN-γ production by CD4(+) T cells in response to PbA antigens was dependent on IL-2. These findings suggest the importance of IL-2 levels during infection with malaria parasites and indicate that CD4(+) T cells can produce IFN-γ without TCR engagement via a bystander mechanism in response to IL-2 produced by other activated CD4(+) T cells.     

Viral dsRNA-activated human dendritic cells produce IL-27, which selectively promotes cytotoxicity in naive CD8+ T cells

Viral recognition programs DCs to express Signal 3 molecules that promote the differentiation of effector CD8(+) T cells. Besides IL-12, another DC-derived IL-12 family member, IL-27, has been reported to contribute herein, but its specific role is not well understood. Here, we show that whereas IL-12 potently induces inflammatory cytokines (i.e., IFN-γ and TNF-α, but not IL-2), IL-27 excels in inducing proliferation and a cytotoxic profile (GrB, cytotoxicity of target cells) in human na?ve CD8(+) T cells. Compared with bacterial cell-wall peptidoglycan, viral dsRNA-mimic poly (I:C) is superior in priming human BDCA1(+) peripheral blood DCs to produce IL-12 and IL-27, which promote inflammatory cytokines and a cytotoxic profile in differentiating CD8(+) T cells, respectively. These data support the concept that viral dsRNA-activated human DCs produce IL-27 to act as a specialized procytotoxic, antiviral cytokine in the development of effector CD8(+) T cells.     

The role of IL-12 in the maintenance of an established Th1 immune response in experimental leishmaniasis

IL-12 initiates the development of cell-mediated immunity by promoting the differentiation of naive T cells into the Th1 phenotype, and is essential in the development of a Th1 immune response to the intracellular protozoan parasite, Leishmania major. The present study investigated whether IL-12 is also required for the maintenance and effector function of an established Th1 immune response in L. major -infected mice. While neutralization of IL-12 com promised the ability of a leishmanial antigen-reactive Th1 cell clone to produce IFN-γ in vitro, lymphnode cells taken from 2-week L. major -infected mice were able to secrete IFN-γ in an IL-12-independent manner. However, when a short-term T cell line was established in vitro from lymph node cells, the production of IFN-γ again became IL-12 dependent. These results suggest that other factors may compensate for IL-12 in vivo in promoting IFN-γ production during L. major infection. To directly assess if IL-12 was required in vivo for resistance to L. major, we studied the effect of IL-12 neutralization on both a primary and secondary L. major infection in C3H mice. L. major infection in C3H mice is characterized by the development of a small lesion that heals by 8 weeks, and these animals are resistant to reinfection. As previously reported, administration of anti-IL-12 monoclonal antibody (mAb) during a primary infection led to severe disease. However, mice that had healed from a primary infection with L. major and were treated with anti-IL-12 mAb were as resistant as control animals. These findings suggest that once Th1 cells have developed, their effector function in vivo is independent of IL-12, and that this independence is not due to an intrinsic property of the T cell, but to the microenvironment created by the infection.     

IL-17作为分子佐剂增强HIV DNA疫苗细胞免疫应答的研究

目的 为了进一步增强HIV DNA疫苗的免疫反应,本研究将IL-17作为HIV DNA疫苗的分子佐剂免疫小鼠,旨在探讨IL-17对HIVDNA疫苗诱导体液和细胞免疫应答的影响.方法 将小鼠IL-17构建到真核表达载体,与HW-1膜蛋白DNA疫苗pGX-Env联合免疫BALB/c小鼠;分别在第0、2周进行免疫,在第4周检测T淋巴细胞增殖指数、抗-Env IgG、细胞因子表达水平和体内细胞毒性T淋巴细胞杀伤作用(CTL)等免疫学指标.结果 IL-17能够增强HIV DNA疫苗的特定免疫反应.与单注射疫苗组相比,IL-17作为佐剂组的T细胞增殖、抗体水平和CD4~+T细胞分泌IFN-γ、IL-4和IL-17的表达均无明显增强,但对CD8~+T细胞分泌IFN-γ的表达和体内CTL的效果影响明显(P<0.05).结论 IL-17作为分子佐剂不足以影响Th细胞分化,然而却能够增强特异性CD8~+T细胞中IFN-γ的表达,尤其是增强体内CTL反应.此结果为增强艾滋病DNA疫苗CD8~+T细胞活性和用于艾滋病的治疗提供了一个新的思路.     

Human Th1 responses driven by IL-12 are associated with enhanced expression of CD40 ligand

IL- 12 is the prominent inducer of Th1 responses in humans and in the mouse. CD40 ligand (CD40L) plays important roles in regulation of immune responses, including T cell-dependent activation of B cells and cytokine production by monocytes and dendritic cells. The present study examined the influences of IL-12 on the CD40L expression of activated human CD4⁺ T cells. IL-12 enhanced CD40L expression on CD4⁺ T cells stimulated with immobilized anti-CD3 in the complete absence of accessory cells, whereas IL-4 and IL-10 decreased it. Exogenous interferon-gamma (IFN-γ) did not increase CD40L expression on immobilized anti-CD3 stimulated CD4⁺ T cells at any time up to 168 h of culture. The IL-12-induced enhancement of CD40L expression on anti-CD3 activated CD4⁺ T cells was not influenced in the presence of a metalloproteinase inhibitor KB8301, which up-regulated CD40L expression by preventing the processing of membrane-bound CD40L, or B cells, which down-regulated CD40L expression by receptor-mediated endocytosis. These results indicate that IL-12 enhances the CD40L expression of activated CD4⁺ T cells independently of the IFN-γ production. The data thus suggest that Th1 responses induced by IL-12 might play an important role in the regulation of humoral immune responses through up-regulated CD40L expression.