不同树突状细胞亚型在支气管哮喘中的作用

树突状细胞(DCs)是目前已知功能最强的抗原递呈细胞,也是唯一能将抗原递呈给naiveT细胞、激发初次免疫应答的抗原递呈细胞,其在机体固有免疫以及适应性免疫中均发挥着重要的作用.支气管哮喘(简称哮喘)是一种常见的气道慢性炎症性疾病,存在Th1/Th2细胞亚群数量与功能失衡.近年来,研究显示,通过释放一系列的趋化因子以及细胞因子,DCs能活化naive T细胞并影响其极化,参与哮喘的发生发展.然而,不同DCs的亚型诱导naive T细胞极化的方向不尽相同,在决定机体对抗原是免疫耐受还是免疫反应发挥着不同作用.本文就DCs不同亚型在哮喘中的作用作一综述.     

慢性乙型肝炎患者CD11c+髓样树突状细胞数量和功能的变化

BV形成免疫耐受是其持续感染的主要原因.树突状细胞(DC)作为体内最强的抗原递呈细胞,在诱导HBV特异性细胞毒T淋巴细胞反应中起重要作用[1].其中外周血DCs前体CD11c+髓样树突状细胞(mDC)主要发挥抗原提呈功能,促进Th1细胞极化和细胞免疫的发生[2].     

颗粒化日本血吸虫M_r22600抗原对小鼠树突状细胞和CD4~+CD25~+调节性T细胞的作用

目的研究颗粒化日本血吸虫Mr22600抗原对小鼠树突状细胞(DCs)功能的影响及诱导CD4+CD25+调节性T细胞的作用。方法体外实验:分别用Sepharose 4B偶联rSj22.6/26GST抗原与可溶性rSj22.6/26GST抗原负载DCs,流式检测DCs表型变化,混合淋巴细胞增殖实验检测DCs功能。将不同抗原负载的DCs,与CD4+T细胞共培养,流式检测观察对CD4+CD25+Foxp3+T细胞数量的影响。体内试验:将42只BALB/c小鼠随机分6组(每组6～8只),A组免疫Sepharose4B偶联rSj22.6/26GST抗原,B组免疫福氏佐剂乳化rSj22.6/26GST抗原,C组免疫rSj22.6/26GST抗原,同时设Sepharose4B对照组(D组),福氏佐剂对照组(E组)和PBS对照组(F组),各组均为皮下多点免疫50μg抗原,隔2周加强免疫,共免疫2次。末次免疫后2周处死,无菌取腹股沟淋巴结,制备细胞悬液,流式检测DCs占淋巴结细胞的比例;同时取脾脏,制备成脾脏单个核细胞,流式检测各免疫组CD4+CD25+Foxp3+T细胞占脾细胞的比例。用免疫磁珠分选各免疫组CD4+CD25+T细胞,与CD4+CD25-T细胞共培养,氚标记胸腺嘧啶核苷(3H-TdR)掺入法检测细胞增殖情况。结果体外实验结果显示,DCs经可溶性抗原刺激后表面分子CD40、CD80、CD86表达率分别为(43.5±6.2)%、(37.7±0.1)%和(71.4±1.4)%,经Sepharose4B偶联抗原刺激后表达率分别为(31.2±5.4)%、(32.0±1.6)%和(63.8±1.0)%,与可溶性抗原相比,Sepharose4B偶联rSj22.6/26GST抗原不能有效刺激DCs成熟。Sepharose4B偶联rSj22.6/26GST抗原负载DCs可诱导CD4+CD25+调节性T细胞扩增。体内实验结果显示,Sepharose4B偶联rSj22.6/26GST抗原免疫小鼠可诱导CD4+CD25+调节性T细胞数量增加,且与可溶性抗原组(cpm值为3558±147)相比,Sepharose4B偶联rSj22.6/26GST抗原组(cpm值为1420±335)来源的CD4+CD25+调节性T细胞的抑制能力更强。结论 Sepharose4B偶联rSj22.6/26GST抗原与可溶性抗原相比,更易诱导CD4+CD25+调节性T细胞,诱导的CD4+CD25+调节性T细胞具有更强的抑制功能,且这一作用可能与不同性状抗原干预DCs的功能状态有关。     

IGRP与1型糖尿病的关系

1型糖尿病是由T细胞介导的自身免疫性疾病.许多研究表明,抗原特异性的CD4~+和CD8~+T细胞在1型糖尿病的发病过程中起重要作用.胰岛细胞特异性葡萄糖-6-磷酸酶催化亚基相关蛋白(IGRP)作为1型糖尿病的主要自身抗原之一,是葡萄糖-6-磷酸酶蛋白家族中的一员,在人和非肥胖糖尿病鼠胰腺中均有表达.它在胰岛β细胞的代谢过程中起重要作用,但是确切机制仍不清楚.IGRP的研究将有助于探索1型糖尿病诊断和治疗的新方法.     

胰岛β细胞自身免疫的分子机制

根据美国糖尿病学会(ADA，1997)和世界卫生组织(WHO，1999)糖尿病分型诊断的新建议，1型糖尿病可分为免疫介导性和特发性两种亚型。遗传易感因素[如人白细胞抗原(HLA)-DQ／DR、胰岛素基因的可变串联重复序列(INS-VNTR)和细胞毒性T淋巴细胞抗原(CTLA)-4等]与环境因素(如病毒感染、饮食成分及化学毒素等)相互作用，致使免疫调节失衡[如辅助性T细胞(Th)1功能亢进，Th2功能减弱等]，胰岛β细胞的免疫耐受性丧失而遭受免疫攻击，发生自身免疫性糖尿病。换言之，免疫介导性1型糖尿病系由自身免疫选择性破坏胰岛β细胞，引起胰岛素分泌缺乏所致。     

辅助性T细胞免疫与桥本甲状腺炎

桥本甲状腺炎(HT)是一种自身免疫性疾病,其免疫发病机制与T细胞亚群中的CD4+ CD25+调节性T细胞、辅助性T细胞(Th) 17、滤泡辅助性T细胞有重要关系.CD4+ CD25+调节性T细胞可抑制Th1介导的自身免疫和炎性反应,其减少势必使Thl过量产生细胞因子(包括白细胞介素-1β、干扰素-γ、肿瘤坏死因子-α),这些细胞因子激发了甲状腺细胞的凋亡,从而促使HT的发生.Th17与调节性T细胞相拮抗,其在早期HT患者中高表达.滤泡辅助性T细胞是淋巴组织中最重要的效应性T细胞亚群之一,其过量表达会引起HT的发生.对调节性T细胞、Th17、滤泡辅助性T细胞进行研究,有助于进一步认识HT的免疫发病机制.     

树突状细胞与1型糖尿病

树突状细胞(DC)是体内最主要的抗原提呈细胞。对DC在1型糖尿病发病机制中的作用有促进和预防两种不同看法。当前研究认为,DC是一种生物特性及功能多样性细胞。在1型糖尿病发病过程中,不同类型DC、不同生理状态的DC以及DC所处微环境的不同,将影响其表达双信号的能力和诱导辅助性T细胞(Th细胞)分化的方向。进而对免疫耐受和免疫平衡的调节发挥不同作用。本文就此作一综述。     

1型糖尿病免疫学研究进展

1型糖尿病是一种器官特异性自身免疫性疾病.其发病机制复杂,在遗传、环境、免疫等诸多因素的共同作用下,自身抗原免疫耐受丧失,免疫调节失衡,导致针对胰岛β细胞的自身免疫性破坏,导致糖尿病的发生.但其具体病因目前尚不明确,再生基因家族、胰-十二指肠同源盒因子1、嗜铬粒蛋白A、辅助性T细胞(Th)17及胰岛稳态蛋白等均参与1型糖尿病发病的不同环节,同时这些新的免疫学因子的发现,为1型糖尿病的诊断及治疗提供了新的靶点.     

T 淋巴细胞与 1 型糖尿病

CD4+、CD8+T淋巴细胞在1型糖尿病(DM)发病中起重要作用.近年研究发现,T淋巴细胞在胰岛自身抗原刺激下发生增殖,该细胞在浸润胰岛过程中需要粘附分子参与,CD4+T淋巴细胞通过分泌细胞因子参与1型DM的发病过程,CD8+T淋巴细胞在1型DM发病早期有重要作用,且与CD4+T淋巴细胞有协同作用.     

调节性T细胞在1型糖尿病和胰岛移植中的作用

调节性T细胞是一种免疫抑制性细胞,在维持免疫耐受中起重要作用.研究相继发现了多种调节性T细胞的表面标记和调节性T细胞的作用机制.调节性T细胞的数量和(或)功能缺陷与1型糖尿病的发生、发展密切相关.输注调节性T细胞可以预防和治疗1型糖尿病,延长移植胰岛的存活时间和改善移植物功能.目前,关于调节性T细胞治疗的临床试验研究已经开展,如果后续实验能证实调节性T细胞体内输注治疗的安全性及有效性,调节性T细胞免疫治疗将成为治疗1型糖尿病和预防胰岛移植后免疫排斥的有效方法.     

Prospects for dendritic cell vaccination against fungal infections in hematopoietic transplantation

Dendritic cells (DCs) are uniquely able to initiate and control the immune response to fungi. DCs function at three levels in the manipulation of the immune response to these pathogens. First, they mount an immediate or innate response to them, for example, by producing inflammatory mediators upon capture and phagocytosis; second, through these preceding innate functions, they decode the fungus-associated information and translate it in qualitatively different Th responses, and third, they are key in containing and dampening inflammatory responses by tolerization through the induction of regulatory T cells (Treg). DCs sense fungi in a morphotype-specific manner, through the engagement of distinct recognition receptors ultimately affecting cytokine production and costimulation. Both myeloid and plasmacytoid murine and human DCs phagocytose fungi and undergo functional maturation in response to them. However, their activation program for cytokine production was different, being IL-12 mainly produced by myeloid DCs and IL-12, IL-10 and IFN-alpha mainly produced by plasmacytoid DCs. This resulted in a distinct ability for T cell priming, being Th1, Th2, and Treg differently activated by the different DC subsets. The ability of fungus-pulsed DCs to prime for Th1 and Th2 cell activation upon adoptive transfer in vivo correlated with the occurrence of resistance and susceptibility to the infections, respectively. Antifungal protective immunity was also induced upon adoptive transfer of DCs transfected with fungal RNA. The efficacy was restricted to DCs transfected with RNA from yeasts or conidia but not with RNA from fungal hyphae. The effect was fungus-specific, as no cross-protection was observed upon adoptive transfer of DCs pulsed with either fungal species. The infusion of fungus-pulsed or RNA-transfected DCs accelerated the recovery of functional antifungal Th1 responses in mice with allogeneic hematopoietic stem cell transplantation (HSCT) and affected the outcome of the infections. As the ability of phagocytose fungi was defective in peripheral DCs from patients with HSCT, soon after the transplant, our findings suggest that the adoptive transfer of DCs may restore immunocompetence in HSCT by contributing to the educational program of T cells. Thus, the remarkable functional plasticity of DCs in response to fungi can be exploited for the deliberate targeting of cells and pathways of cell-mediated immunity in response to fungal vaccines.     

HBcAg-pulsed dendritic cell vaccine induces Th1 polarization and production of hepatitis B virus-specific cytotoxic T lymphocytes

Aim:  Dendritic cells (DCs) pulsed with HBsAg efficiently reverse the immune tolerance to hepatitis B virus (HBV) and induce HBV-specific cytotoxic T lymphocyte (CTL) responses in transgenic mice and healthy volunteers. However, it is not clear whether HBV core antigen (HBcAg)-pulsed DCs can effectively induce CD4⁺ helper T cells polarization into Th1, which contribute to the induction and maintenance of HBV-specific CD8⁺ T cells in chronic hepatitis B (CHB) patients. To address this issue, we conducted this study and investigated whether HBcAg-pulsed DCs could polarize Th1 cells and induce an HBcAg-specific CTL response.
Methods:  HBcAg-pulsed DCs were generated from 21 CHB patients. The capacity of the HBcAg-pulsed DC vaccine to stimulate CD4⁺ and CD8⁺ T cells to produce IFN-γ and IL-4 was estimated by intercellular cytokine staining, and the HBcAg-pulsed DCs derived from 10 humam leucocyte antigen (HLA)-A2⁺ CHB patients were tested for the induction of HBV-specific CTLs from autologous T cells by pentamer staining. The cytotoxicity of these CTLs was evaluated in vitro by flow cytometry.
Results:  The HBcAg-pulsed DCs derived from CHB patients exhibited a stronger capacity to stimulate autologous CD4⁺ and CD8⁺ T cells to release IFN-γ rather than IL-4, which could induce HBV core 18-27 specific CTLs, suggesting a specific cytotoxicity against T2 cells that had been loaded with the HBV core 18-27 peptide in vitro .
Conclusion:  HBcAg-pulsed DC vaccine derived from CHB patients efficiently induced autologous T cell polarization to Th1 and generation of HBV core 18-27 specific CTLs.     

The cross-regulatory relationship between human dendritic and regulatory T cells and its role in type 1 diabetes mellitus

Dendritic cells (DCs) and T regulatory (Treg) cells play a crucial role in maintaining the tolerance needed to prevent the onset of autoimmunity that leads to the development of type 1 diabetes mellitus (T1DM). Various experimental studies have shown that human DC subsets are involved in the induction of anergy in T cells and in the differentiation of conventional CD4(+) and CD8(+) lymphocytes into the respective subtypes of Treg cells. Treg cells, in turn, have been shown to modulate the function of DCs to exhibit tolerogenic properties. To evaluate whether T1DM development is related to abnormalities in DCs and Treg cells, many attempts have been made to characterize these cell types in diabetic individuals and in subjects at risk of developing the disease. This review aims to supply an update on the progress made in these aspects of T1DM research.     

Osteopontin functionally activates dendritic cells and induces their differentiation toward a Th1-polarizing phenotype

Osteopontin (OPN) has been shown to have T helper 1 (Th1) cytokine functions in cell-mediated immunity. Deficiency of OPN is linked to a reduced Th1 immune response in autoimmunity, infectious disease, and delayed-type allergy. Dendritic cells (DCs) are central for the induction of T-cell-mediated immunity, when initially flexible DCs are instructed by priming signals and tissue-derived factors to adopt Th1, Th2, or regulatory T-cell-inducing phenotypes. Although OPN influences the cytokine secretion of T cells and macrophages, its effects on DC polarization remain an important missing link in the understanding of OPN functions in Th1 immunity. Here we demonstrate that OPN promotes the emigration of human DCs from the epidermis and functionally activates myeloid-type DCs, augmenting their expression of HLA-DR, costimulatory, and adhesion molecules. OPN induces their Th1-promoting tumor necrosis factor alpha (TNF-alpha) and interleukin-12 (IL-12) secretion, and enhances their allostimulatory capacity. In mixed lymphocyte reactions (MLRs), OPN stimulates IL-12 secretion by DCs, inducing elevated interferon-gamma (IFN-gamma) production by T cells. Naive Th cells stimulated by OPN-activated DCs show a Th1-polarized cytokine production. Our findings identify OPN as an important tissue-derived factor that DCs encounter when traveling from peripheral sites of activation to secondary lymphatic organs, which induces DC maturation toward a Th1-promoting phenotype.     

树突状细胞诱导抗曲霉菌的Th免疫及皮质类固醇对其影响的研究

目的　研究树突状细胞 (DC)在抗曲霉菌免疫中的作用以及皮质类固醇如何在DC水平影响机体的抗曲霉菌免疫。方法　通过体外培养小鼠骨髓DC ,用麦氏比浊法检测DC对灭活曲霉菌孢子的吞噬量。酶联免疫吸附测定 (ELISA)检测DC以及脾脏T细胞分泌的细胞因子。结果　小鼠骨髓DC能高效吞噬加热灭活的曲霉菌孢子 ,皮质类固醇氢化可的松 (HC)抑制DC吞噬曲霉菌孢子的能力。DC受曲霉菌孢子刺激时分泌白细胞介素 12 (IL 12 )和干扰素γ(IFN γ) ,而不分泌白细胞介素 10 (IL 10 ) ,HC明显抑制DC分泌IL 12和IFN γ ,但不影响IL 10的分泌。给小鼠接种经灭活曲霉菌孢子冲击的DC后 ,其脾脏T细胞在体外受灭活曲霉菌孢子再刺激时分泌IFN γ ,而给小鼠接种经灭活曲霉菌孢子和HC联合冲击的DC后 ,其脾脏T细胞受灭活曲霉菌孢子再刺激时分泌IFN γ明显减少 ,IL 10却增加。结论　DC可能是抗曲霉菌免疫的效应细胞 ,并起始抗曲霉菌的Th1型免疫 ,HC抑制DC的这些功能 ,并使曲霉菌免疫偏向Th2型。经灭活曲霉菌孢子冲击的DC可能对增强免疫受损宿主抗曲霉菌免疫有作用。     

Enhancement of CTLs induced by DCs loaded with ubiquitinated hepatitis B virus core antigen

AIM: To investigate whether hepatitis B virus (HBV) could induce a hepatitis B virus core antigen (HBcAg)-specific cytotoxic T lymphocyte (CTL) response in vitro by dendritic cells (DCs) transduced with lentiviral vector-encoding ubiquitinated hepatitis B virus core antigen (LV-Ub-HBcAg).METHODS: Recombinant LV-Ub-HBcAg were transfected into highly susceptible 293 T cells to obtain high virus titres. Bone marrow-derived DCs isolated from BALB/c mice were cultured with recombinant granulocyte-macrophage colony-stimulating factor and recombinant interleukin (IL)-4. LV-Ub-HBcAg, lentiviral vector-encoding hepatitis B virus core antigen (LV-HBcAg), lentiviral vector (LV) or lipopolysaccharide were added to induce DC maturation, and the DC phenotypes were analyzed by flow cytometry. The level of IL-12 in the supernatant was detected by enzyme-linked immunosorbent assay (ELISA). T lymphocytes were proliferated using Cell Counting Kit-8. DCs were cultured and induced to mature using different LVs, and co-cultured with allogeneic T cells to detect the secretion levels of IL-2, IL-4, IL-10 and interferon-γ in the supernatants of T cells by ELISA. Intracellular cytokines of proliferative T cells were analyzed by flow cytometry, and specific CTL activity was measured by a lactate dehydrogenase release assay.RESULTS: LV-Ub-HBcAg-induced DCs secreted more IL-12 and upregulated the expression of CD80, CD86 and major histocompatibility class II. DCs sensitised by different LVs effectively promoted cytokine secretion; the levels of IL-2 and interferon-γ induced by LV-Ub-HBcAg were higher than those induced by LV-HBcAg. Compared with LV-HBcAg-transduced DCs, LV-Ub-HBcAg-transduced DCs more efficiently stimulated the proliferation of T lymphocytes and generated HBcAg-specific cytotoxic T lymphocytes.CONCLUSION: LV-Ub-HBcAg effectively induced DC maturation. The mature DCs efficiently induced T cell polarisation to Th1 and generated HBcAg-specific CTLs.     

华支睾吸虫成虫抗原和排泄分泌产物对T细胞的作用研究

目的观察华支睾吸虫成虫抗原(Crude antigen,CA)、排泄/分泌产物(excretory-secretory products,ESPs)对T细胞的作用。方法体外分离小鼠骨髓细胞诱导分化为未成熟骨髓树突状细胞(immature DC,iDC);磁珠分选仪分选小鼠脾脏细胞的初始CD4+T细胞;流式细胞术检测DC、CD4+T细胞的纯度;抗原刺激DC细胞,实验分为PBS阴性对照组,LPS阳性对照组,CA和ESPs刺激组;负载抗原后的DC细胞与分选的CD4+T细胞共培养72h;Real time-PCR检测T-bet、GATA3mRNA的相对表达量;ELISA检测细胞培养上清中IFN-γ、IL-4细胞因子的表达量。结果与PBS组相比,ESPs刺激组Tbet、GATA3mRNA表达水平升高(P0.05),而CA刺激组T-bet、GATA3 mRNA表达水平差异不显著;与PBS组相比,ESPs刺激组细胞因子IFN-γ、IL-4的含量均升高(P0.05),CA刺激组仅IFN-γ的分泌增高(P0.05),IL-4无明显变化。结论 CA可能诱导宿主产生Th1型免疫应答,ESPs可能诱导宿主产生Th1型、Th2型免疫应答。     

Alternatively activated dendritic cells regulate CD4+ T-cell polarization in vitro and in vivo

Interleukin-4 is a cytokine widely known for its role in CD4(+) T cell polarization and its ability to alternatively activate macrophage populations. In contrast, the impact of IL-4 on the activation and function of dendritic cells (DCs) is poorly understood. We report here that DCs respond to IL-4 both in vitro and in vivo by expression of multiple alternative activation markers with a different expression pattern to that of macrophages. We further demonstrate a central role for DC IL-4Rα expression in the optimal induction of IFNγ responses in vivo in both Th1 and Th2 settings, through a feedback loop in which IL-4 promotes DC secretion of IL-12. Finally, we reveal a central role for RELMα during T-cell priming, establishing that its expression by DCs is critical for optimal IL-10 and IL-13 promotion in vitro and in vivo. Together, these data highlight the significant impact that IL-4 and RELMα can have on DC activation and function in the context of either bacterial or helminth pathogens.     

Dll4 in the DCs isolated from OVA-sensitized mice is involved in Th17 differentiation inhibition by 1,25-dihydroxyvitamin D3 in vitro

Introduction: T helper 17 cell (Th17) cells play an important role in neutrophilic asthma, and 1,25(OH)2D3 has been reported to modulate the proliferation and differentiation of T cells. In this study, we examined the effects of 1,25(OH)2D3 on the dendritic cell (DC)-mediated regulation of Th17differentiation from OVA-sensitized mice. Methods: DCs were isolated from ovalbumin-sensitized mouse spleens. Lipopolysaccharide (LPS) was administered to stimulate the DCs for 24?h, and dexamethasone or 1,25(OH)2D3 was applied simultaneously. The expression of Notch ligand delta-like ligand 4 (Dll4) in the DCs was detected in each group. All the groups of treated DCs were co-cultured with T cells, and Dll4 was inhibited in these groups. After 24?h, Th17 and Treg cell differentiation and the IL-17A levels were measured. Results: Dll4 expression was increased in LPS-treated DCs compared with the control group (p?=?0.05), resulting in increased Th17 cell differentiation (p?=?0.002). Treatment with 1,25(OH)2D3 inhibited the Dll4 expression(p?=?0.04) and decreased Th17 cell differentiation (p?=?0.001) in DCs that was induced by LPS. Directly inhibiting Dll4 reduced Th17 cell differentiation, and Th17 cell differentiation was not further inhibited by 1,25(OH)2D3 once Dll4 was blocked. Conclusions: These result suggest that Dll4 in the DCs isolated from OVA-sensitized mice is involved in Th17 differentiation inhibition by 1,25(OH)2D3.