地塞米松对哮喘小鼠CD4+CD25+调节性T细胞及IL-4、IL-10水平的影响

目的 探讨地塞米松对哮喘小鼠CD4+ CD25+调节性T细胞及IL-4、IL-10水平的影响.方法 30只雄性BALB/c小鼠随机分为三组:正常对照组、哮喘组和地塞米松组.利用卵清白蛋白腹腔注射和雾化吸入制备哮喘模型;通过流式细胞仪检测各组小鼠脾脏单个核细胞CD4+ CD25+调节性T细胞占CD4+T细胞的百分比;使用免疫组织化学方法分析各组IL-4在小鼠肺组织中的表达情况;用酶联免疫吸附试验检测各组小鼠血清IL-10的水平.结果 哮喘组脾脏单个核细胞CD4+CD25+调节性T细胞百分比及IL-10的表达水平较正常对照组和地塞米松组降低(P＜0.05),哮喘组IL-4水平较正常对照组和地塞米松组增高(P＜0.05).结论 地塞米松的抗炎作用可能通过上调CD4+ CD25+调节性T细胞、调节性T细胞亚群失衡的途径来实现.     

CD4+CD25+ T cells regulate colonic localization of CD4 T cells reactive to a microbial antigen

BACKGROUND: In patients with inflammatory bowel diseases, T-cell activation driven by microflora has been implicated as a mechanism causing clonal expansion and infiltration of CD4+ T cells in colonic lamina propria (LP). We explored a regulatory mechanism preventing infiltration of CD4+ T cells specific to a microbe-associated antigen in the gut. METHODS: SCID mice were reconstituted with CD4+ T cells specific to ovalbumin (OVA) and were orally administered with Escherichia coli engineered to produce OVA. RESULTS: OVA-specific CD4+ T cells (KJ1-26+) were recruited to colonic LP in an Ag-dependent manner, which was inhibited by adoptive transfer of naturally occurring CD4+CD25+ T (Treg) cells. KJ1-26+ T cells and Treg cells are localized preferentially to the colonic follicles that contain dendritic cells. In mice given Treg cells, LP CD4+ T cells showed a decrease in proliferative and interferon gamma response and an increase in transforming growth factor beta1 response to OVA stimulation. Treg cells inhibited both antigenic activation of effector CD4+ T cells and class II/CD80/CD86 up-regulation of dendritic cells. CONCLUSION:: Treg cells suppress recruitment of CD4+ T cells specific to a microbe-associated antigen to LP, which was associated with colocalization of effector CD4+ T cells and Treg cells in colonic follicles.     

CD4+ CD25+ Treg cells inhibit human memory gammadelta T cells to produce IFN-gamma in response to M tuberculosis antigen ESAT-6

T cells play an important role in innate immunity against infections; however, the regulation of these cells remains largely unknown. In the present study, we show that ESAT-6, an antigen of Mycobacterium tuberculosis, induces IFN- secretion by human T cells. In addition, ESAT-6 also induces the activation and proliferation of T cells. Phenotypic analysis indicates that IFN-–producing T cells are mainly effector memory cells with the surface phenotype of CD45RA^–CD62L^–CCR7^–. These results were further confirmed by the fact that naive T cells from cord blood did not produce IFN- in response to ESAT-6. Further studies indicated that stimulation with ESAT-6 directly induced purified T cells to produce IFN-, independent of both antigen-presenting cells and CD4⁺ T cells. Unexpectedly, depletion of CD4⁺ T cells markedly enhanced IFN- production by T cells, indicating that CD4⁺ T cells regulate the response of T cells. Importantly, CD4⁺CD25⁺ T regulatory (Treg) cells but not CD4⁺CD25^– T cells significantly inhibited IFN- production by T cells. Taken together, these data demonstrate for the first time that Treg cells can play an important role in the regulation of immune responses of antigen-specific human memory T cells.     

HIV-1-specific IFN-gamma/IL-2-secreting CD8 T cells support CD4-independent proliferation of HIV-1-specific CD8 T cells

Functional and phenotypic characterization of virus-specific CD8 T cells against cytomegalovirus, Epstein-Barr virus, influenza (flu), and HIV-1 were performed on the basis of the ability of CD8 T cells to secrete IFN-gamma and IL-2, to proliferate, and to express CD45RA and CCR7. Two functional distinct populations of CD8 T cells were identified: (i) dual IFN-gamma/IL-2-secreting cells and (ii) single IFN-gamma-secreting cells. Virus-specific IFN-gamma/IL-2-secreting CD8 T cells were CD45RA-CCR7-, whereas single IFN-gamma CD8 T cells were either CD45RA-CCR7- or CD45RA+CCR7-. The proportion of virus-specific IFN-gamma/IL-2-secreting CD8 T cells correlated with that of proliferating CD8 T cells, and the loss of HIV-1-specific IL-2-secreting CD8 T cells was associated with that of HIV-1-specific CD8 T cell proliferation. Substantial proliferation of virus-specific CD8 T cells (including HIV-1-specific CD8 T cells) was also observed in CD4 T cell-depleted populations or after stimulation with MHC class I tetramer-peptide complexes. IL-2 was the factor responsible for the CD4-independent CD8 T cell proliferation. These results indicate that IFN-gamma/IL-2-secreting CD8 T cells may promote antigen-specific proliferation of CD8 T cells even in the absence of helper CD4 T cells.     

Frequencies of circulating IL-17-producing CD4+CD161+ T cells and CD4+CD161+ T cells correlate with disease activity in rheumatoid arthritis

Abstract

Objective. Rheumatoid arthritis (RA) is a common autoimmune disease that is primarily driven by effector T cells, particularly Th17 cells, which are mainly contained within CD4+CD161+ T cells. Thus, we aimed to explore whether the frequencies of circulating IL-17-producing CD4+CD161+ T cells and CD4+CD161+ T cells were correlated with RA disease activity.

Methods. The surface phenotype and cytokine production of blood were analyzed by flow cytometry in 52 RA patients and 17 healthy controls. The disease activity was evaluated by the 28-joint disease activity score.

Results. The frequencies of circulating IL-17-producing CD4+CD161+ T cells and CD4+CD161+ T cells were increased in RA patients, and they were elevated in patients with active disease status compared to patients with low disease status. Furthermore, their frequencies were positively correlated with disease activity parameters. Receiver operating characteristic curve analysis revealed that IL-17-producing CD4+CD161+ T cell levels were able to distinguish disease activity with 60.7 % sensitivity and 87.5 % specificity, while CD4+CD161+ T cell levels showed 92.9 % sensitivity and 66.7 % specificity.

Conclusion. These results support the hypothesis that Th17 cells are involved in the pathogenesis of RA and suggest that circulating CD4+CD161+ T cells are a potential biomarker of RA disease activity.     

Phosphoantigen-activated V gamma 2V delta 2 T cells antagonize IL-2-induced CD4+CD25+Foxp3+ T regulatory cells in mycobacterial infection

Although Foxp3(+) T regulatory cells (Tregs) are well documented for their ability to suppress various immune cells, T-cell subsets capable of counteracting Tregs have not been demonstrated. Here, we assessed phosphoantigen-activated Vgamma2Vdelta2 T cells for the ability to interplay with Tregs in the context of mycobacterial infection. A short-term IL-2 treatment regimen induced marked expansion of CD4(+)CD25(+)Foxp3(+) T cells and subsequent suppression of mycobacterium-driven increases in numbers of Vgamma2Vdelta2 T cells. Surprisingly, activation of Vgamma2Vdelta2 T cells by adding phosphoantigen Picostim to the IL-2 treatment regimen down-regulated IL-2-induced expansion of CD4(+)CD25(+)Foxp3(+) T cells. Consistently, in vitro activation of Vgamma2Vdelta2 T cells by phosphoantigen plus IL-2 down-regulated IL-2-induced expansion of CD4(+)CD25(+)Foxp3(+) T cells. Interestingly, anti-IFN-gamma-neutralizing antibody, not anti-TGF-beta or anti-IL-4, reduced the ability of activated Vgamma2Vdelta2 T cells to down-regulate Tregs, suggesting that autocrine IFN-gamma and its network contributed to Vgamma2Vdelta2 T cells' antagonizing effects. Furthermore, activation of Vgamma2Vdelta2 T cells by Picostim plus IL-2 treatment appeared to reverse Treg-driven suppression of immune responses of phosphoantigen-specific IFNgamma(+) or perforin(+) Vgamma2Vdelta2 T cells and PPD-specific IFNgamma(+)alphabeta T cells. Thus, phos-phoantigen activation of Vgamma2Vdelta2 T cells antagonizes IL-2-induced expansion of Tregs and subsequent suppression of Ag-specific antimicrobial T-cell responses in mycobacterial infection.     

CD4+CD25+ regulatory T cells control CD8+ T-cell effector differentiation by modulating IL-2 homeostasis

CD4(+)CD25(+) regulatory T cells (Treg) play a crucial role in the regulation of immune responses. Although many mechanisms of Treg suppression in vitro have been described, the mechanisms by which Treg modulate CD8(+) T cell differentiation and effector function in vivo are more poorly defined. It has been proposed, in many instances, that modulation of cytokine homeostasis could be an important mechanism by which Treg regulate adaptive immunity; however, direct experimental evidence is sparse. Here we demonstrate that CD4(+)CD25(+) Treg, by critically regulating IL-2 homeostasis, modulate CD8(+) T-cell effector differentiation. Expansion and effector differentiation of CD8(+) T cells is promoted by autocrine IL-2 but, by competing for IL-2, Treg limit CD8(+) effector differentiation. Furthermore, a regulatory loop exists between Treg and CD8(+) effector T cells, where IL-2 produced during CD8(+) T-cell effector differentiation promotes Treg expansion.     

CD8+ T cells control the TH phenotype of MBP-reactive CD4+ T cells in EAE mice

Trimolecular interactions between the T cell antigen receptor and MHC/peptide complexes, together with costimulatory molecules and cytokines, control the initial activation of naive T cells and determine whether the helper precursor cell differentiates into either T helper (TH)1 or TH2 effector cells. We now present evidence that regulatory CD8(+) T cells provide another level of control of TH phenotype during further evolution of immune responses. These regulatory CD8(+) T cells are induced by antigen-triggered CD4(+) TH1 cells during T cell vaccination and, in vitro, distinguish mature TH1 from TH2 cells in a T cell antigen receptor Vbeta-specific and Qa-1-restricted manner. In vivo, protection from experimental autoimmune encephalomyelitis (EAE) induced by T cell vaccination depends on CD8(+) T cells, and myelin basic protein-reactive TH1 Vbeta8(+) clones, but not TH2 Vbeta8(+) clones, used as vaccine T cells, protect animals from subsequent induction of EAE. Moreover, in vivo depletion of CD8(+) T cells during the first episode of EAE results in skewing of the TH phenotype toward TH1 upon secondary myelin basic protein stimulation. These data provide evidence that CD8(+) T cells control autoimmune responses, in part, by regulating the TH phenotype of self-reactive CD4(+) T cells.     

Humoral immune response in IL-12 and IFN-gamma deficient mice after infection with Cryptosporidium parvum

Infection with Cryptosporidium spp. causes diarrhoeal disease and has become an important medical and veterinary problem especially in the immunocompromised host. The importance of the adaptive immune response, with CD4+ T-lymphocytes being the major players, has been clearly demonstrated. The requirement of IL-12 and IFN-gamma identifies this response as a Th1-dominated reaction. IFN-gamma is also important in the early phase of the host-parasite interaction. We analysed the outcome of infection in IL-12p40 (IL-12KO) and IFN-gamma (GKO) deficient C57BL/6 mice after primary and secondary challenge with the parasite and, for the first time, we demonstrate the resulting Ig response in sera and vaginal lavages. Although showing differences in the extent and the time course both strains of mice were able to clear infection and developed an almost complete resistance to re-infection. While GKO mice mounted prolonged parasite-specific IgG and IgA responses after primary infection, in IL-12KO mice IgG and IgA titres dropped over time. Re-challenge of mice 5 weeks after primary infection led to a booster effect in Ig response despite the absence of oocyst shedding. The data from infection and re-challenge experiments suggest that in IL-12- or IFN-gamma-deficient mice the development of resistance involves other protective immune responses.     

IL-2 and IFN-gamma, but not IL-4 secretion by peripheral blood mononuclear cells (PBMC) are related to CD4+ T cells and clinical status in Brazilian HIV-1-infected subjects.

It has been reported that production of IL-2 and IFN-gamma, known as T-helper type 1 cytokines, by peripheral mononuclear cells (PBMC) decreases with progression of HIV infection. In contrast, IL-4 and IL-10 production, Th2 cytokine profile, increases with HIV disease progression. PBMC were evaluated from 55 HIV-infected subjects from Divis?o de Imunologia, Hospital das Clínicas, Faculdade de Medicina da Universidade de S?o Paulo, to "in vitro" cytokines production after 24 hours of stimulation with PHA. Low levels of IL-4 production in both HIV-infected patients and normal subjects, were detected. The patients with CD4+ T cell counts < 200 showed a significant decrease of IL-2 and IFN-gamma production compared to controls. Patients with higher counts of CD4+ T cells (either between 200-500 or > 500 cells/mm3) also showed decreased production of IL-2 that was not statistically significant. There was a correlation between IL-2 and IFN-gamma release with CD4+ T cells counts. HIV-1-infected individuals with CD4+ T cells > 500 cells/mm3 showed increased levels of IL-2 and IFN-gamma, than individuals with CD4+ T cells < 500 cells/mm3. In conclusion, we observed a decline of IL-2 and IFN-gamma production at advanced HIV disease. IL-4 production was not affected during HIV infection. Taken together, these findings suggest that the cytokine profile might be influenced by the HIV infection rather than the cause of disease progression.     

Murine liver antigen presenting cells control suppressor activity of CD4+CD25+ regulatory T cells

CD4(+)CD25(+) regulatory T cells (Treg) are important mediators of peripheral immune tolerance; however, whether Treg participate also in hepatic immune tolerance is not clear. Therefore, we tested the potential of Treg to suppress stimulation of CD4(+) T cells by liver sinusoidal endothelial cells (LSEC), Kupffer cells (KC), or hepatocytes. In the absence of Treg, all 3 types of liver cells could stimulate CD4(+) T cell proliferation; in the presence of Treg, however, CD4(+) T cell proliferation was suppressed. Interaction with KC even stimulated the expansion of the Treg population; LSEC or hepatocytes, in contrast, could not induce proliferation of Treg. Because liver inflammation can be induced by infection, we tested the potential of liver cells to modify Treg suppressor activity in the presence of microbial signals. In the presence of immune-stimulatory CpG-oligonucleotides, LSEC, KC, and hepatocytes could indeed overcome Treg-mediated suppression; in the presence of lipopolysaccharide (LPS), however, only KC and hepatocytes, but not LSEC, could overcome Treg suppressor activity. Hepatocytes from mice with deficient toll-like receptor-4 signaling failed to abrogate Treg suppression in response to LPS, indicating that overcoming Treg suppressor activity was indeed a response of the liver cell and not of the Treg. In conclusion, Treg can suppress CD4(+) T cell stimulation by liver cells. However, in response to microbial signals, the liver cells can overcome the suppressive activity of Treg. Thus, liver cells may facilitate the transition from hepatic immune tolerance to hepatic inflammation by controlling Treg suppressor activity.     

CD4+CD25+ T cells in skin lesions of patients with cutaneous leishmaniasis exhibit phenotypic and functional characteristics of natural regulatory T cells

Endogenous regulatory T (Treg) cells are involved in the control of infections, including Leishmania infection in mice. Leishmania viannia braziliensis is the main etiologic agent of cutaneous leishmaniasis (CL) in Brazil, and it is also responsible for the more severe mucocutaneous form. Here, we investigated the possible involvement of Treg cells in the control of the immune response in human skin lesions caused by L. viannia braziliensis infection. We show that functional Treg cells can be found in skin lesions of patients with CL. These cells express phenotypic markers of Treg cells--such as CD25, cytotoxic T lymphocyte-associated antigen 4, Foxp3, and glucocorticoid-induced tumor necrosis factor receptor--and are able to produce large amounts of interleukin-10 and transforming growth factor- beta . Furthermore, CD4+CD25+ T cells derived from the skin lesions of 4 of 6 patients with CL significantly suppressed in vitro the phytohemagglutinin-induced proliferative T cell responses of allogeneic peripheral-blood mononuclear cells (PBMCs) from healthy control subjects at a ratio of 1 Treg cell to 10 allogeneic PBMCs. These findings suggest that functional Treg cells accumulate at sites of Leishmania infection in humans and possibly contribute to the local control of effector T cell functions.     

Preferential loss of IL-2-secreting CD4+ T helper cells in chronic HCV infection

Hepatitis C virus (HCV) becomes persistent in the majority of infected individuals. In doing so, the virus evades host adaptive immune responses, although the mechanisms responsible in this evasion are not clear. Several groups have demonstrated weak or absent HCV-specific CD4+ T cell responses during chronic HCV infection using proliferation assays and, more recently, class II tetramers. However, the functional status of HCV-specific CD4+ T cells in resolved and persistent infection is poorly understood. Using interferon gamma (IFN-gamma) and interleukin 2 (IL-2) enzyme-linked immunospot assays, we analyzed cytokine secretion patterns in chronically infected patients and compared them with those with resolved infection. In the spontaneous resolver group, strong IL-2 secretion in relation to IFN-gamma secretion was observed. However, in the persistently infected group, a consistent and significant loss of IL-2-secreting cells, compared with IFN-gamma-secreting cells, was identified. In vitro addition of IL-2 had a substantial effect in restoring CD4+ T cell activity. In conclusion, failure of IL-2 secretion, as opposed to physical deletion or complete functional unresponsiveness, appears to be an important determinant of the status of CD4+ T cell populations in chronic HCV infection. Loss of IL-2 secretory capacity may lead to disruption of IFN-gamma and proliferative function in vivo-a status that characterizes the cellular immune response in both CD4+ and CD8+ compartments in chronic disease.     

调节性T细胞在不同品系小鼠心脏移植后的变化及意义

目的探讨不同品系小鼠颈部心脏移植后调节性T细胞的变化及意义。方法建立小鼠颈部心脏异位移植模型,实验分2组,受体小鼠均为C57BL／6,供体分别为BALB／c和C57BL／6小鼠。比较两组供心存活时间、排斥反应程度,流式细胞仪测定CD4＋CD25＋调节性T细胞（Tregs）及CD3＋CD8＋T细胞水平。结果术后第7天,异基因组Tregs水平明显低于同基因组（P〈0．05）,而CD8＋T细胞却明显高于同基因组（P〈0．05）。结论Tregs水平高低与心脏移植后免疫耐受的发生、发展密切相关,可作为心脏移植后免疫耐受的监测指标,对移植物的预后估计和急性排斥反应的早期诊断具有重要的临床意义。     

Impaired up-regulation of CD25 on CD4+ T cells in IFN-gamma knockout mice is associated with progression of myocarditis to heart failure

Inflammation has been recognized increasingly as a critical pathologic component of a number of heart diseases. A mouse model of autoimmune myocarditis was developed to study the role of immune mediators in the development of cardiac dysfunction. We have found previously that IFN-gamma deficiency promotes inflammation in murine myocarditis. It has been unclear, however, how IFN-gamma deficiency in myocarditis affects cardiac function and what underlying immune mechanisms are responsible for these effects. In this work, we show that IFN-gamma knockout (KO) mice have more pronounced systolic and diastolic dysfunction and greater frequency of progression to dilated cardiomyopathy and heart failure compared with WT mice. Cardiac dysfunction in the KO mice is associated with the expansion of activated (CD44(high)) CD3+ T cells due to reduced apoptosis of CD4+, but not CD8+, T cells. CD4+ T cells in the KO mice show impaired up-regulation of CD25 upon activation, resulting in the expansion of CD4+CD44+CD25- T cells and their infiltration into the heart. CD4+CD25- T cells are less apoptosis-prone compared with the CD25+ population, and their infiltration into the heart is associated with greater severity of myocarditis. We conclude that IFN-gamma deficiency in autoimmune myocarditis is associated with preferential expansion of CD4+CD44+CD25- T cells resulting in increased cardiac inflammation. An exaggerated inflammatory response in IFN-gamma KO mice causes cardiac dysfunction, leading to dilated cardiomyopathy and heart failure.