Lineage and signal strength determine the inhibitory effect of transforming growth factor beta1 (TGF-beta1) on human antigen-specific Th1 and Th2 memory cells

TGF-beta1 is a pleotrophic cytokine playing an important role in immune regulation. The impact of TGF-beta1 on immune function is determined by the cell type and the microenvironment. CD4+ T cells exemplify this, by responding to TGF-beta1 in heterogeneous ways based on their level of maturation and state of differentiation. TGF-beta1 leads to suppression of proliferation and cytokine production of naive T cells and influences the outcome of T cell differentiation. In mice, the response of memory T cells to TGF-beta1 is determined by the lineage of the cells. TGF-beta1 causes decreased proliferation of Th1 cells but has little effect on the proliferation of Th2 cells. Here we examined the effect of TGF-beta1 on human Th1 and Th2 memory T cells and show that proliferation of Th1 clones are inhibited by TGF-beta1, whereas Th2 cells are not. Furthermore the sensitivity of individual Th1 clones to TGF-beta1 is linked to the level of activation achieved in culture, but these differences cannot be explained by T cell receptor (TCR) affinity alone. Together this demonstrates that the human T cell response to TGF-beta1 is determined by the environment in which an immune response takes place and the previous immune experience of the cells involved.     

Th2/Th3 cytokine genotypes are associated with pregnancy loss

Cytokines are critical immunoregulatory molecules, responsible for determining the nature of an immune response. It has been proposed that Th2/Th3 immune reactions support normal pregnancy, while Th1 immunity is considered detrimental to the fetus. Since cytokine production is partly under genetic control, it is possible that women suffering from a high incidence of abortions are genetically predisposed to mount a type of immune response inappropriate for pregnancy maintenance. This study investigated the frequencies of cytokine gene polymorphisms in abortion-prone women and women with successful pregnancies. We investigated the role of Th1/Th2/Th3 cytokine gene polymorphisms, such as TGF-beta1 codon 10 (TGFbetac10; C to T), TGF-beta1 codon 25 (TGFbetac25; G to C), TNFalpha promoter-308 (G to A), IL-6 promoter-174 (G to C), IL-10 promoter-1082 (G to A), IL-10 promoter-819 (C to T), IL-10 promoter-592 (C to A), and IFNgamma intron 1 +874 (A to T) in abortion-prone female patients. Our results support the importance of Th2/Th3 immune responses in pregnancy loss, and suggest that an individual's immunogenetic profile indicative of imbalances in Th2/Th3 cytokines is associated with pregnancy loss. Our results suggest that abortive events are determined by genetic factors, reflected in the female patient's immunogenetic profile.     

抗原特异性Th17细胞的分化与调节

目的: 探讨影响抗原特异性Th17细胞分化和调节的因素.方法: T细胞受体转基因小鼠(DO11.10)CD4 T细胞, 与同背景正常小鼠的脾细胞混合, 经OVA多肽刺激后, 在不同的Th17极化的培养条件下, 观察Th17细胞及细胞因子的产生. 结果: 单纯OVA抗原刺激主要诱导特异性Th1型反应, 在TGF-β和IL-6存在的条件下, 主要诱导Th17反应; 当加入IL-23之后, 促进了Th17细胞的分化.阻断了IFN-γ和IL-4之后, Th17细胞的百分率明显增加.LPS可以促进Th1型细胞因子的产生, 但对抗原特异性Th17细胞的分化没有明显的促进作用.结论: 抗原特异性Th17细胞是与Th1、 Th2相对独立的细胞亚群, TGF-β、 IL-6和 IL-23可诱导或促进Th17的分化, 而Th1和Th2细胞因子抑制其分化.     

Autoreactive T cell clones isolated from normal and autoimmune-susceptible mice exhibit lymphokine secretory and functional properties of both Th1 and Th2 cells

Recent studies have suggested the existence of two mutually exclusive subpopulations of T helper (Th) cells in the murine immune system, called Th1 which produces interleukin (IL)-2 and interferon (IFN)-gamma but not IL-4 and Th2 which secretes IL-4 and IL-5 but not IL-2. Also, functionally, Th1 cells generally activate the macrophages and mediate delayed-type hypersensitivity whereas Th2 cells provide help efficiently to B cells. In the present study, we investigated the lymphokine secretory properties of two well-characterized autoreactive (self-Ia reactive) T cell clones isolated from normal DBA/2 mice and autoimmune-susceptible MRL-lpr/lpr mice. It was observed that both the autoreactive T cell clones, following activation, produced IL-2, IL-4, and IFN-gamma. They induced hyper-Ia expression and cell proliferation in syngeneic B cells as well as activated the macrophages to exhibit tumoristatic properties. Both clones could also induce T-T network interaction in which syngeneic naive CD4+ T cells responded directly to stimulation with autoreactive T cell clones. The T-T interaction was demonstrable in 1-month-old MRL-lpr/lpr mice prior to the onset of the autoimmune disease but not in 6-month-old mice having lymphadenopathy and autoimmune disease. Unlike Th1 and Th2 cells which upon antigenic stimulation respond to exogenous IL-2 and IL-4, the autoreactive T cell clones responded only to IL-2 but not to IL-4. Our data suggest the existence of a unique subset of immunoregulatory CD4+ Th cells having the lymphokine secretory and functional properties of both the murine Th1 and Th2 subsets.     

Transforming growth factor-beta1, a strong costimulator of rat T-cell activation promoting a shift towards a Th2-like cytokine profile

TGF-beta is a known regulator of hematopoietic cells. In this study we suggest a major role of adherent spleen cells (adh-splc), to convert an inhibitory effect of TGF-beta1 on T-cell activation into a stimulatory effect. We show that interaction of TGF-beta1 with adh-splc induces a costimulatory effect on T-cell proliferation. This costimulatory signal requires the adh-splc to be in physical contact with the T-cells. Presence of adh-splc results in a shift towards a Th2-like response with a cytokine profile of increased IL-10 and decreased IFN-gamma. In the adh-splc population the increase of IL-10 is most pronounced at start of activation, whereas in the T-lymphocyte population, IL-10 increases at the end of culture. The suppression of the IFN-gamma production by TGF-beta1 is shown to be an important mechanism by which TGF-beta enhances proliferation of Th2 lymphocytes.     

Cytokine expression pattern in benign prostatic hyperplasia infiltrating T cells and impact of lymphocytic infiltration on cytokine mRNA profile in prostatic tissue

The aim of the study is to characterize the type of immune response in benign prostatic hyperplasia (BPH) tissue. BPH tissue-derived T cells (n = 10) were isolated, activated (PMA + ionomycin), and analyzed for intracellular reactivity with anti-IFN-gamma and IL-2, -4, -5, -6, -10, and -13, as well as TNF-alpha and -beta by four-color flow cytometry. Lymphokine release was tested using Th1/Th2 cytokine bead arrays. The amount of IFN-gamma and IL-2, -4, -13, and TGF-beta mRNA expressed in normal prostate (n = 5) was compared with that in BPH tissue separated into segments with normal histology (n = 5), BPH histology with (n = 10) and without (n = 10) lymphocytic infiltration, and BPH nodules (n = 10). Expression of lymphokine receptors was analyzed by immunohistology, flow cytometry, and RT-PCR. We found that 28 +/- 18% of BPH T helper cells were IFN-gamma(+)/IL-4(-) Th1 cells, 10 +/- 2% were IFN-gamma(-)/IL-4(+) Th2, and 12 +/- 6% were IFN-gamma(+)/IL-4(+) Th0 cells. In relation, cytotoxic and double-negative BPH T lymphocytes showed a slight decrease in Th1 and Th0 in favor of Th2. In double-positive BPH T lymphocytes, the trend toward Th2 (35 +/- 15%) was significant (Th1: 12 +/- 7%; Th0: 5 +/- 4%). Lymphokine release upon stimulation was found in the case of IL-2, IL-5, IFN-gamma, and TNF-alpha > 4 microg; of IL-4 > 2 microg; and of IL-10 > 1 microg/ml. Expression of lymphokine mRNA in tissue was increased (2- to 10-fold) in infiltrated BPH specimens with and without BPH histology. The infiltrated BPH specimens with normal histology differed from those with BPH histology, most evident by the significant decrease in IFN-gamma and the increase in TGF-beta mRNA expression. Infiltrated BPH specimens with BPH histology expressed significantly more IFN-gamma (5-fold), IL-2 (10-fold), and IL-13 (2.8-fold) when compared with noninfiltrated BPH specimens. BPH nodules, however, showed the highest level of expression of IL-4 and IL-13, with only intermediate levels of IFN-gamma and very low levels of IL-2 mRNA. Immune response in histologically less transformed BPH specimens is primarily of type 1, whereas in chronically infiltrated nodular BPH and especially within BPH nodules, it is predominantly of type 0 or type 2.     

Adjuvant effect of zinc oxide on Th2 but not Th1 immune responses in mice

Background and aim: We investigated the effect of zinc oxide (ZnO) on Th1 and Th2 immune responses in mice.

Material and methods: Mice were intraperitoneally administered with ovalbumin (OVA) with or without varying doses of ZnO (day 0). On day 21, anti-OVA IgG, IgG2a, IgG1, and IgE antibodies in sera, OVA-specific proliferative responses of spleen cells, and production of Th1 cytokines including IFN-γ as well as Th2 cytokines such as IL-4 and IL-5 were measured.

Results: The results showed that administration of OVA with ZnO was followed by greater increases in anti-OVA IgG and the antigen-specific splenocyte proliferation compared to that of OVA alone. The production of anti-OVA IgG1 and IgE and secretion of IL-4 and IL-5 were markedly enhanced by ZnO. The enhancing effect of ZnO on these Th2 responses was as strong as aluminium hydroxide (Alum) that was widely used as an adjuvant. In contrast, treatment with OVA plus ZnO failed to affect production of anti-OVA IgG2a as well as IFN-γ. It was also observed that ZnO had a stimulating effect on the secretion of the proinflammatory cytokine IL-17 from a new lineage of effector Th cells.

Conclusion: These results suggest that ZnO appears to have an adjuvant effect on the immune system, especially Th2 but not Th1 immune responses.     

Induction of global anergy rather than inhibitory Th2 lymphokines mediates posttrauma T cell immunodepression

Depressed mitogen-induced IL-2 and IFN-gamma responses after severe mechanical or thermal injury are postulated to result from an expansion of Th2 lymphocytes with concomitant excessive production of IL-4 and/or IL-10. Here, we simultaneously assessed proliferation and Th1 (IFN-gamma) versus Th2 (IL-10, IL-4) lymphokine production in trauma patients' isolated T cells stimulated in a costimulation sufficient, antigen presenting cell independent system (anti CD3 + anti-CD4). T cells with depressed proliferation and IL-2 production simultaneously lost IL-4, IL-10, and IFN-gamma protein and mRNA responses. Exogenous IL-12 addition did not restore IFNgamma responses, but exogenous IL-2 partially restored IL-4, IFN-gamma, and IL-10 production. Although initially partially restored by exogenous IL-2 or stimulation with PMA + ionomycin, patient T cells with persisting anergy progressively lost even these lymphokine and proliferative responses. Development of global T cell anergy was not a result of lost T cell viability or protein synthesis, since it corresponded to predominance of anergic T cells with upregulated expression of CD11b, but downregulated CD28 and CD3 expression. Thus, the subset of posttrauma patients whose isolated T cells become unresponsive experienced progressively worsening global anergy, mediated not by an increased production of Th2 lymphokines, but possibly by T cell incapacity to be activated through TCR triggering or Ca(2+) mobilization.     

TGF-beta1 down-regulates Th2 development and results in decreased IL-4-induced STAT6 activation and GATA-3 expression

TGF-beta plays an important role in immune regulation in vivo and affects T cell differentiation in vitro. Here we describe how TGF-beta modulates Th2 development in vitro and investigate its mechanisms of action. TGF-beta down-regulated Th2 development of naive CD4+ Mel-14high T cells derived from the DO11.10 ovalbumin-specific TCR-transgenic mouse, and this was observed both in cultures driven with anti-CD3 and anti-CD28 and with splenic APC and antigen. TGF-beta down-regulated GATA-3 expression in developing Th2 and these cells showed a diminished IL-4-induced STAT6 activation. We found, however, that naive cells driven in Th2 conditions with TGF-beta did not show a significantly decreased STAT6 activation, suggesting that TGF-beta inhibits Th2 development via a STAT6-independent mechanism.     

The effect of TGF-beta1 on immune responses of naïve versus memory CD4+ Th1/Th2 T cells

The role of TGF-beta1 in the regulation of T cell responses has been perplexing, possibly because it is dependent on the type of T cell being regulated and its cytokine microenvironment. In the present study, we demonstrate that TGF-beta1 has a profound inhibitory effect on naive CD4+ T cell undergoing differentiation under defined neutral, Th1 and Th2 priming conditions. In addition, we show that if CD4+ T cells are primed in the presence of TGF-beta1, they exhibit reduced secondary anti-CD3/anti-CD28-induced and antigen-specific immune responses (even when TGF-beta is absent during the secondary response), which is not due to reduced expression of co-stimulatory molecules or to inadequate IL-2 production. Finally, with respect to the effect of TGF-beta on fully differentiated antigen-specific memory CD4+ T cells, we demonstrate that while antigen-specific activation and cytokine secretion by memory Th1 T cells is inhibited by TGF-beta1, such inhibition is associated with partial down-regulation of IL-12 receptor beta2 chain expression. In contrast, memory Th2 T cells are not subject to TGF-beta1 -mediated suppression. In summary, these studies reveal that TGF-beta1 is a powerful negative regulator of the primary immune response of CD4+ T cells, but only Th1 T cells are subject to such regulation after the memory stage of T cell differentiation has been reached. Thus, these studies define the potential regulatory role of TGF-beta1 in Th1 and Th2 T cell-mediated autoimmunity.     

Effect of sinomenine on collagen-induced arthritis in mice

The present study was designed to investigate the effect of sinomenine (SIN), an alkaloid extracted from sinomenium acutum on collagen-induced arthritis (CIA) in mice. For this investigation, mice were s.c. immunized with type II collagen (CII) emulsified with complete Freund's adjuvant (day 0). Varying doses of SIN were orally administered daily commencing on day 0 daily over a period of 55 days. The severity of arthritis was evaluated according to clinical score, the effect of SIN on immune responses were determined by measurement of proliferative responses of spleen cells, antibody levels in serum and cytokine assays. Anti-CII IgG2a and IFN-gamma were measured as indicators of Th1 immune responses and anti-CII IgG1, IgE and IL-5 as those of Th2 responses. IL-10 and TGF-beta were measured as indicators of T cell regulator responses. The results showed that treatment with SIN was followed by decreases in the incidence and severity of CIA, anti-CII IgG and the antigen-specific splenocyte proliferation. Production of all isotypes of antibodies including anti-CII IgG2a, IgG1 and IgE as well as secretion of cytokines such as IFN-gamma and IL-5 were suppressed by SIN. In addition, SIN enhanced the secretion of TGF-beta while it had no obvious effect on production of IL-10. These results suggest that the anti-arthritic effect of SIN may be related to the suppression of both Th1 and Th2 immune responses. TGF-beta may at least in part contribute to the suppression of Th1 as well as Th2 immune responses.     

A Mixed Th1/Th2 Cell Cytokine Response Predominates in Systemic Onset Juvenile Rheumatoid Arthritis: Immunoregulatory IL-10 Function

The immune response identified by the induction of Th1/Th2 cells plays a critical role in the pathogenesis of various inflammatory and immune disorders. We have determined that in children with systemic onset juvenile rheumatoid arthritis (JRA), peripheral blood mononuclear cells (PBMC) constitutively and after stimulation with various antigensin vitroinduce a higher secretion of interleukin-4 (IL-4) and IL-10 with a characteristic deficiency of IL-2 and interferon-γ (IFN-γ). This cytokine pattern is a representative of a mixed Th1/Th2 cell response in JRA. The CD3/CD28 costimulatory molecule was found to be a potent inducer of IL-4 and IL-10 secretion. PBMC-derived augmented IL-10 secretion was inhibited by exogenous Th1 cell type recombinant cytokines (IL-2, IL-12, and IFN-γ). Although IL-10 inhibits PBMC-induced proinflammatory IL-1α and tumor necrosis factor-α secretion, it had no major effect on IL-6 production. The finding of a distinctly enhanced mixed Th1/Th2 cell response cytokine (IL-4 and IL-10) pattern in JRA provides a framework for developing strategies for immunologic intervention in this rheumatic disorder in children.     

Revisiting the Th1/Th2 Paradigm

The identification of subsets of CD4⁺ helper cells producing distinct pattern of cytokines has provided a valuable framework for understanding how different effector populations of immune cells can be recruited in vivo during infection. In the view of most investigators, Th1 and Th2 cells produce factors that serve as their own autocrine factors and cytokines exerting suppressive activities on each other's development and activity. This concept intuitively explains the natural tendency of immune responses to become progressively polarized. However, several experimental observations appear difficult to rationalize with a simple, 'symmetrical' Th1/Th2 paradigm including those that Th1 cells do not produce their own growth factor; that both Th1 and Th2 cells can promote inflammatory responses; that interleukin-10 (IL-10) inhibits inflammatory responses in a Th1/Th2-independent fashion; that IL-10 promotes the development of Th1-type effector cells; and that IL-12 can amplify pre-established Th2 responses. The purpose of the present analysis is to provide a revised model for better understanding how cytokines regulate immune responses in vivo .     

Regulation of cytokine production by human Th0 cells following stimulation with peptide analogues: differential expression of TGF-beta in activation and anergy.

The different biological activities of T-cell-derived cytokines and their level of production influences the qualitative nature of immune responses and, in certain forms of T-cell tolerance, the lack of antigen responsiveness is associated with the production of transforming growth factor-beta (TGF-beta) and interleukin-4 (IL-4). In this study we have investigated the effects of T-cell receptor (TCR) ligation with peptide analogues and the native peptide, in the presence and absence of costimulation, on cytokine production by human T-helper type 0 (Th0) cells reactive with influenza virus haemagglutinin (HA) peptide (HA306-318) and restricted by HLA-DRB1*0101. We observed that resting Th0 cells constitutively produced TGF-beta, but when stimulated with peptide and antigen-presenting cells (APC) under conditions that induce clonal expansion, TGF-beta secretion was abrogated. Furthermore, exposure of the T cells to the wild-type HA peptide under conditions that induce T-cell anergy resulted in the secretion of TGF-beta, and subsequent antigenic rechallenge was unable to override this signal and down-regulate TGF-beta production. Stimulation with altered TCR ligands that failed to induce proliferation also resulted in marked production of TGF-beta, although in many instances the levels were less than those observed in the total absence of antigen, suggesting that partial signalling has occurred. Although in general, there was a direct positive correlation between proliferation and the production of IL-2, IL-4 and interferon-gamma (IFN-gamma) following stimulation with certain analogues, the production of selected cytokines was dissociated.