联合阻断共刺激信号对移植免疫耐受的影响

目的:探讨联合阻断共刺激信号对移植免疫耐受的影响.方法:采用野生型BALB/c小鼠作为供体,采用野生型B6小鼠作为受体进行腹部异位小鼠心脏移植.受体接受单独或联合使用抗CD40L抗体(MRl)和抗B7抗体的治疗,以阻断CD28-B7和CD40-CD40L(ligand,配体)共刺激信号.以心脏完全停跳作为排斥反应终结时间,并开腹确认心脏是否停跳.心脏移植后60日对移植物进行HE染色.为确定移植免疫耐受是否具有供体抗原特异性,对接受联合阻断共刺激信号治疗而长期存活的受体实施了第二部分来源(供体来源)及第三部分来源 (C3H来源)的皮肤移植.结果:联合阻断共刺激信号使移植心脏长期存活(>150日),而且组织病理学检查未见慢性排斥反应发生.供体来源的皮肤长期存活(>50日),而第三部分来源的皮肤则很快被排斥.结论:联合阻断共刺激信号CD28-B7与CD40-CD40L可诱导出不伴有慢性排斥反应的供体抗原特异性的移植免疫耐受.     

体外LPS刺激及CD40的配基化对sCD40基因修饰DCs TLR4-MD2表达及IL-12分泌的影响

目的： 研究体外LPS刺激及CD40的配基化对可溶性CD40（sCD40）基因修饰树突状细胞TLR4-MD2表达及IL-12分泌的影响,为有效利用树突状细胞诱导特异性移植免疫耐受提供实验依据。方法: 脂质体法将质粒pEGFP-N1/sCD40及空质粒pEGFP-N1转染DC2.4细胞株;应用LPS及抗CD40单抗刺激6 h,流式细胞仪检测DC表面TLR4-MD2的表达,RT-PCR法检测DC 的TLR4 mRNA 表达水平,并用ELISA法检测细胞因子IL-12p70的分泌。结果: LPS刺激下调DC表面TLR4-MD2的表达,同时给予CD40配基化可引起TLR4-MD2的表达显著增高;CD40配基化对DC TLR4mRNA 水平表达无影响，但可部分地增高LPS引起的TLR4mRNA 表达降低;此外,CD40的配基化可显著诱导LPS刺激后IL-12分泌增加。sCD40基因修饰DC可拮抗以上作用。结论: 体外LPS及抗CD40单抗刺激下,sCD40基因修饰树突状细胞可显著下调其表面TLR4-MD2的表达,IL-12p70分泌减少，可能与阻断胞浆内的TLR4-MD2的转运过程有关。     

CD40单克隆抗体的制备、筛选及功能鉴定

CD40是肿瘤坏死因子受体超家族成员之一,属于Ⅰ型跨膜糖蛋白,其自然配体是CD40L。CD40-CD40L信号通路在许多重要的生理和病理过程中都起到关键的调节作用。基于其在激活免疫应答中的重要作用,在肿瘤免疫治疗中,具有激活CD40-CD40L信号的CD40激动剂抗体可用于提高抗肿瘤免疫应答;在移植排斥和炎症反应中,CD40-CD40L信号也起重要作用,阻断CD40信号通路是目前治疗风湿性关节炎、肠炎、系统性红斑狼疮、多发性硬化和糖尿病的一个重要靶点。制备CD40阻断性抗体或激动剂抗体不仅可用于检测CD40分子表达,还可以开发用于炎症性疾病或肿瘤治疗的免疫疗法。本研究表达CD40胞外段蛋白,通过免疫制备14株CD40单克隆抗体,筛选发现全部可作为western blotting检测CD40蛋白表达的抗体,9株CD40抗体可作为一抗用于流式细胞术检测人CD40表达,1株CD40抗体能阻断人CD40L和CD40相互作用。有意义的是,8株CD40抗体能激活人CD40分子信号通路,另外有10株能激活小鼠脾脏细胞CD40下游基因的表达,7株能上调小鼠脾脏B细胞表面共刺激分子CD86的表达。本研究制备一系列CD40抗体,可用于CD40检测、CD40信号的阻断或激活。     

OX40在免疫耐受中的调节作用

T细胞的激活不仅需要T细胞受体与靶细胞表面的抗原肽-主要组织相容性复合物特异性结合产生的第一信号,还需要共刺激分子传导的第二信号.OX40就是共刺激分子之一,其与配体OX40L的相互作用对维持T细胞活化后的进一步扩增、存活、分化为效应细胞及记忆性T细胞具有重要作用.阻断这一信号通路对增强免疫耐受,治疗移植排斥反应具有重要价值.近年来OX40在免疫耐受中对不同类型T细胞的调节作用及其在器官移植及移植物抗宿主病中应用的研究备受瞩目.     

microRNA-27a对树突状细胞表型及功能的影响

目的:研究microRNA-27a(miR-27a)对脂多糖(Lipopolysaccharide,LPS)刺激的小鼠树突状细胞(Dendritic cell,DC)的成熟和细胞因子分泌的影响。方法:小鼠骨髓来源的未成熟树突状细胞(immature dendritic cell,im DC)转染miR-27a的模拟物(miR-27a mimics)后,用LPS刺激24 h,采用流式细胞仪检测其表面共刺激分子CD80、CD86及MHCⅡ表达,ELISA方法检测其上清中的IL-12p70及IL-10蛋白水平,RT-PCR方法检测其细胞内IL-12p40及IL-10 mRNA水平,混合淋巴细胞反应(MLR)检测其刺激T细胞增殖能力。结果:与未处理的im DC比较,LPS刺激24 h后的DC表面的共刺激分子CD80、CD86及MHCⅡ表达均显著增高(均P0.001);LPS刺激24 h后,与对照组比较,转染miR-27a mimics细胞的共刺激分子CD80、CD86及MHCⅡ表达均显著降低(均P0.001),且显著抑制IL-12分泌(P0.01)、促进IL-10分泌(P0.05),并显著减弱LPS刺激的DC促CD4+T细胞增殖的能力(P0.01)。结论:miR-27a影响小鼠树突状细胞的成熟以及细胞因子的分泌。     

TLR2激动剂Pam3CK逆转IL-10转染小鼠髓样树突状细胞免疫功能的研究

目的:观察TLR2激活剂Pam3CK对IL-10转染小鼠髓样树突状细胞免疫功能影响。方法:转染IL-10至小鼠髓样树突状细胞(mDC),TLR2配体Pam3CK刺激48小时,利用流式细胞仪检测DC表面标志MHCⅡ、CD80、CD86及FasL等分子的表达;ELISA检测细胞产生IL-6、TNF-α。结果:IL-10抑制mDC表达CD80、CD86、MHCⅡ类分子,降低其分泌IL-6、TNF-α,促进其表达FasL,而TLR2激动剂刺激增加了IL-10转染DC表达MHC-Ⅱ类分子及CD80、CD86,促进其产生IL-6及TNF-α,抑制了FasL表达。结论:TLR2激动剂可逆转IL-10诱发的DC免疫应答低下。     

IL-10基因修饰的大鼠树突状细胞表型分析及生物学特性的研究

目的研究IL-10基因修饰后的大鼠树突状细胞(DC)的表型及其生物学特性。方法以含IL-10基因的重组腺病毒载体体外转染大鼠骨髓来源的DC,Western blot测定转染后各组DC中IL-10蛋白的表达,流式细胞仪检测各组DC表面抗原CD83、CD86分子的表达情况,混合淋巴细胞反应法测定各组DC刺激同种异体T细胞增殖的能力。结果 IL-10基因修饰组DC可检测到IL-10高表达,表面抗原CD83、CD86低表达,其刺激T淋巴细胞增殖水平较其他各组低。结论 IL-10基因修饰的DC可有效的表达有功能的IL-10,为研究IL-10修饰的DC诱导同种异体移植免疫耐受奠定了基础。     

CD40-CD40L共刺激途径在体液免疫和细胞免疫中的作用

CD40与CD40配体(CD40L)是体内炎症和免疫反应系统的一对共同刺激分子,参与机体的体液免疫和细胞免疫反应.CD40-CD40L共刺激途径能促进T细胞活化并放大T淋巴细胞依赖的免疫应答,是产生记忆性CD8+T细胞的基础,能够促进CD8+T细胞的扩增和多能性,在CD4+T细胞分化的过程中起重要作用,介导更强的抗肿瘤效应和杀伤靶细胞的能力.CD40-CD40L共刺激途径参与T淋巴细胞依赖的B淋巴细胞应答过程、生发中心的形成、长期记忆性R细胞的产生、抗体的产生及抗体类别转换,并可诱导和扩增CD4+ CD25+ Treg细胞.CD40-CD40L共刺激途径在多种疾病的发生、发展中起作用,有广阔的临床应用前景.     

IL-17A 协同GM-CSF 和LPS 促进骨髓细胞衍生树突状细胞的分化和成熟研究

目的:探讨IL鄄17A 对小鼠骨髓细胞衍生树突状细胞分化和成熟的影响。方法:分离小鼠骨髓细胞,加入含GM-CSF(20 ng/ ml)RPMI1640 完全培基培养8 d,诱导小鼠骨髓单个核细胞向DC 分化,加入LPS(1 滋g/ ml)继续培养36 h,进一步诱导DC 成熟,同时在骨髓细胞衍生诱导DC 分化及成熟的不同阶段加入不同浓度的rmIL-17A(10、100 ng/ ml),采用流式细胞术检测DC 表面共刺激分子的表达,ELISA 方法检测DC 培养上清中IL-12p40 和IL-10 水平。结果:rmIL-17A 可促进GM-CSF 诱导骨髓细胞衍生DC 表面共刺激分子CD40、CD80、CD86 和MHC域的表达,且具有剂量依赖性,其中以高浓度rmIL-17A刺激组的CD40 及MHC域表达增加最显著;在LPS 诱导DC 成熟阶段加入rmIL-17A,骨髓细胞衍生DC 共刺激分子CD40、CD80、CD86 和MHC域的表达均明显增加,并且随着rmIL-17A 浓度的增加,CD86 和MHC域的表达水平也随之增高;同时与未加rmIL鄄17A 的对照组相比,低浓度rmIL-17A 组LPS 刺激骨髓细胞衍生DC 分泌IL-12p40 和IL鄄10 水平均显著增加(P <0.001),高浓度rmIL-17A 组IL-12p40 水平显著增高(P<0.001),但IL-10 水平没有变化。结论:IL-17A 可促进GM-CSF 诱导的骨髓细胞衍生DC 前体细胞表型发展,并能协同LPS 诱导骨髓衍生DC 的分化和成熟。     

体外DCs在抗CD45RB抗体诱导免疫耐受中的作用机制

目的:探讨树突状细胞(dendritic cells,DCs)在抗CD45RB抗体诱导的免疫耐受中所发挥的作用,从而阐明抗CD45RB抗体诱导免疫耐受的机制。方法:采用DCs的常规诱导方法(rmGM-CSF、IL-4和LPS),在诱导过程中加入不同剂量的抗CD45RB抗体,成熟后利用流式细胞仪检测细胞表型、周期和吞噬能力,ELISA法检测IL-12分泌量,混合淋巴细胞培养检测DCs对T细胞增殖能力的影响。结果:DCs经抗CD45RB抗体处理后,CD11C和CD83表达升高,CD86表达下降,自身增殖和吞噬能力增强,但分泌IL-12和刺激T细胞增殖的能力明显下降。结论:耐受性树突状细胞(tolerogenic dendritic cells,tDCs)能显著抑制T细胞的增殖,它的产生是抗CD45RB抗体诱导免疫耐受的主要机制之一。     

CD40 ligation and phagocytosis differently affect the differentiation of monocytes into dendritic cells

That monocytes can differentiate into macrophages or dendritic cells (DCs) makes them an essential link between innate and adaptive immunity. However, little is known about how interactions with pathogens or T cells influence monocyte engagement toward DCs. We approached this point in cultures where granulocyte macrophage-colony stimulating factor (GM-CSF) and interleukin (IL)-4 induced monocytes to differentiate into immature DCs. Activating monocytes with soluble CD40 ligand (CD40L) led to accelerated differentiation toward mature CD83(+) DCs with up-regulated human leukocyte antigen-DR, costimulatory molecules and CD116 (GM-CSF receptor), and down-regulation of molecules involved in antigen capture. Monocytes primed by phagocytosis of antibody-opsonized, killed Escherichia coli differentiated into DCs with an immature phenotype, whereas Zymosan priming yielded active DCs with an intermediate phenotype. Accordingly, DCs obtained from cultures with CD40L or after Zymosan priming had a decreased capacity to endocytose dextran, but only DCs cultured with CD40L had increased capacity to stimulate allogeneic T cells. DCs obtained after E. coli or Zymosan priming of monocytes produced high levels of proinflammatory tumor necrosis factor alpha and IL-6 as well as of regulatory IL-10, but they produced IL-12p70 only after secondary CD40 ligation. Thus, CD40 ligation on monocytes accelerates the maturation of DCs in the presence of GM-CSF/IL-4, whereas phagocytosis of different microorganisms does not alter and even facilitates their potential to differentiate into immature or active DCs, the maturation of which can be completed upon CD40 ligation. In vivo, such differences may correspond to DCs with different trafficking and T helper cell-stimulating capacities that could differently affect induction of adaptive immune responses to infections.     

腺病毒介导的CD40Ig基因治疗诱导异基因大鼠心脏移植物的长期存活

目的:通过腺病毒介导的CD40Ig基因治疗,阻断受体体内CD40/CD154共刺激途径,诱导异基因大鼠之间的心脏移植耐受,并探讨相关机制。在将异基因DA大鼠的心脏移植给受体LEW大鼠后,即经门静脉输注携带CD40Ig基因的腺病毒(AdCD40Ig,5×109 pfu)。观察、记录心脏移植物的存活时间。ELISA检测受体大鼠体内CD40Ig蛋白的表达。通过MLR,IL-2逆转实验及Th1/Th2型细胞因子表达的检测,研究耐受的机制。结果:与未处理对照组相比,携带绿色荧光蛋白基因的腺病毒(AdEGFP)给予组,移植物的存活时间未见明显延长;AdCD40Ig腺病毒给予组,异基因大鼠心脏移植物平均存活时间延长至(142.8±26.8)天。ELISA检测表明,CD40Ig蛋白在受体体内表达时间较长,但随时间的推移表达水平逐渐下降。Th1和Th2型细胞因子的检测结果显示,耐受大鼠体内未发现这两类细胞因子偏移的现象。MLR证明耐受大鼠对供体抗原表现为特异性低应答。IL-2逆转实验表明,该耐受形成的早期与克隆无能有关。结论:经.AdCD40Ig腺病毒基因治疗的受体大鼠可以产生特异性的移植耐受,使异基因大鼠心脏移植物长期存活。     

Generation of functionally mature dendritic cells from elutriated monocytes using polyinosinic : polycytidylic acid and soluble CD40 ligand for clinical application

Despite the increasing use of dendritic cell (DC) vaccination in clinical trials, optimal conditions for the generation of functionally mature DCs remain to be established. The current standard DC maturation protocol for clinical trials has been used as an inflammatory cytokine cocktail [tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-6 and prostaglandin E(2)], but this cocktail induced insufficient maturation of DCs derived from elutriated monocytes when cultured in X-VIVO 15. The aim of this study was to define effective combinations of stimulators for generating functionally mature DCs from elutriated monocytes under current good manufacturing practice conditions. We compared the functional capacity of DCs in response to all possible pairwise combinations of four different classes of stimuli: TNF-alpha, peptidoglycan, polyinosinic : polycytidylic acid [poly(I:C)] and soluble CD40 ligand (CD40L). Maturation status of DCs stimulated with combination of four stimuli was similar to that of the cytokine cocktail as assessed by the cell surface phenotype. However, only the combination of poly(I:C) + CD40L induced complete functional activation of the whole DC population, assessing IL-12p70 production, allostimulatory activity, migratory response to CCL19 and T helper 1-polarizing capacity. Thus, the protocol based on the combination of poly(I:C) and CD40L is more effective for the induction of clinical-grade DCs from elutriated monocytes than the standard cytokine cocktail.     

Distinct regulation of CD40-mediated interleukin-6 and interleukin-12 productions via mitogen-activated protein kinase and nuclear factor kappaB-inducing kinase in mature dendritic cells

The role of mitogen-activated protein kinase (MAPK) and nuclear factor kappaB (NF-kappaB) pathways, especially NF-kappaB-inducing kinase (NIK)-mediated alternative pathway, in CD40-mediated interleukin (IL)-6 and IL-12 productions by immature or mature dendritic cells (DCs) was investigated. Murine myeloid DCs were matured by treatment with lipopolysaccharide. CD40 ligation induced modest or vigorous cytokine productions in immature or mature DCs, respectively. After CD40 ligation, p38 MAPK was significantly activated in either immature or mature DCs. SB203580, a p38 MAPK inhibitor, markedly decreased CD40-mediated IL-6 and IL-12 productions in immature DCs. In mature DCs, SB203580 significantly decreased CD40-mediated IL-6 but not IL-12 production. On the other hand, CD40 ligation induced vigorous activation of the NF-kappaB alternative pathway including p100 phosphorylation and subsequent nuclear translocations of p52, a processed form of p100, and RelB in mature but not immature DCs. The CD40-mediated phosphorylation of p100 was completely abolished in NIK-mutated mature DCs. The NIK mutation markedly reduced CD40-mediated IL-12 but not IL-6 production by mature DCs. Taken together, we concluded that IL-6 and IL-12 productions in response to CD40 ligation were controlled by p38 MAPK and NIK mediated alternative pathway, respectively, in mature DCs.     

Engagement of human monocyte-derived dendritic cells into interleukin (IL)-12 producers by IL-1beta + interferon (IFN)-gamma

Dendritic cells (DCs) are potent antigen-presenting cells and can induce tumour- or pathogen-specific T cell responses. For adoptive immunotherapy purposes, immature DCs can be generated from adherent monocytes using granulocyte macrophage colony stimulating factor (GM-CSF) and interleukin (IL)-4, and further maturation is usually achieved by incubation with tumour necrosis factor (TNF)-alpha. However, TNF-alpha-stimulated DCs produce low levels of IL-12. In this study, we compared the effects of TNF-alpha, interferon (IFN)-gamma, IL-1beta or IFN-gamma + IL-1beta on the phenotypic and functional maturation of DCs. Our results show that IFN-gamma, but not IL-1beta, augmented the surface expression of CD80, CD83 and CD86 molecules without inducing IL-12 production from DCs. However, IL-1beta, but not IFN-gamma, induced IL-12 p40 production by DCs without enhancing phenotypic maturation. When combined, IFN-gamma + IL-1beta treatment profoundly up-regulated the expression of CD80, CD83, CD86 and major histocompatibility complex (MHC) class II antigens. Furthermore, IFN-gamma + IL-1beta-treated DCs produced larger amounts of IL-12 and induced stronger T cell proliferation and IFN-gamma secretion in primary allogeneic mixed lymphocyte reaction (MLR) than did TNF-alpha-treated DCs. Our results show that IFN-gamma + IL-1beta induced human monocyte-derived DCs to differentiate into Th1-prone mature DCs.     

Plasmodium falciparum-free merozoites and infected RBCs distinctly affect soluble CD40 ligand-mediated maturation of immature monocyte-derived dendritic cells

Free plasmodium merozoites released from the parasitized hepatocytes and erythrocytes represent a transitory, extracellular stage in its mammalian host. In this study, we compared the effect of Plasmodium falciparum-free merozoites with infected RBCs (iRBCs) on the maturation of human monocyte-derived dendritic cells (DCs) in vitro. Phagocytosed-free merozoites prevented soluble CD40 ligand (sCD40L)-induced, phenotypic maturation of DCs and secretion of IL-12p70 but enhanced IL-10 production and primed, naive CD4+ cells to produce a high level of IL-10 compared with IFN-gamma. Free merozoites augmented sCD40L-induced ERK1/2 activation, and inhibition of ERK1/2 with its inhibitor PD98059 markedly abrogated IL-10 production and rescued IL-12 production. Therefore, the molecular mechanisms by which free merozoites antagonized sCD40L-induced DC maturation appeared to involve the activation of the ERK pathway. In contrast, phagocytosed iRBCs by itself induced DCs to semi-maturation, responded to CD40 signaling by maturing and secreting increased levels of TNF-alpha, IL-6, and also IL-12p70, and led to a pronounced, proinflammatory response by the allogenic CD4+ T cells. iRBCs regulate CD40-induced p38MAPK. Studies using inhibitors selective for p38MAPK (SB203580) showed that p38MAPK played an essential role in the maturation and function of DCs. Our results reveal the ability of free merozoites and iRBCs to distinctly alter the sCD40L-induced DC functioning by regulating the activation of the MAPK pathway that can inactivate or exacerbate immune responses to promote their survival and the development of parasite-specific pathologies.     

肿瘤抗原联合CD40L致敏树突状细胞诱导CTLs杀伤K562细胞的实验研究

目的：以健康人外周血单核细胞为前体细胞，体外诱导为树突状细胞（DCs），负载K562细胞冻融抗原，并联合CD40L诱导产生特异性细胞毒性T淋巴细胞（CTLs）对K562细胞的杀伤作用。方法:密度梯度离心法、贴壁法分离健康人外周血单核细胞，应用rhGM-CSF、rhIL-4、rhTNF-α等细胞因子诱导扩增，培养DCs，用K562细胞冻融抗原联合rhsCD40L致敏DCs。实验分4组：K562细胞冻融抗原致敏DCs为实验组A，联合CD40L致敏DCs为实验组B，未致敏DCs为对照组A，单核细胞+异体淋巴细胞组为对照组B，观察CTLs对K562细胞的杀伤效应。结果:培养出具有典型特征的DCs，表达CD40最高达96%、CD86达97%、CD80为77%、CD1a为 69%，体外能诱导强烈的同种异体混合淋巴细胞增殖反应。在效靶比为 20∶1 时，实验组A对K562细胞的杀伤率为71.3%，实验组B为86.9%，对照组A为37.6%，对照组B为21.1%。实验组均显示高水平杀伤率，与对照组比较差异显著（P＜0.05），实验组B加CD40L杀伤率高于实验组A（P＜0.05） 。结论：K562细胞冻融抗原冲击致敏DCs能有效诱导T细胞特异性抗白血病作用，联合CD40L能增强其CTL的杀伤作用。     

Antigen-specific and nonspecific determinants of cytokine production during topical sensitization of mice to chemical allergens

BACKGROUND: Topical exposure to chemical allergens such as trimellitic anhydride or 1-chloro-2,4-dinitrochlorobenzene results in the accumulation of dendritic cells (DCs) and subsequent rapid up-regulation of CD4 T-cell proliferation and cytokine secretion within draining lymph nodes. OBJECTIVE: We investigated the contribution of antigen-specific and CD40 ligand (CD40L)-mediated signals to chemical allergen-induced CD4 T-cell growth and cytokine production. METHODS: DCs enriched from lymph nodes of allergen-challenged animals by metrizamide centrifugation were used to stimulate cytokine and proliferative responses by magnetic immunobead-sorted CD4 T cells primed in vivo with the same or unrelated allergen. Cultures of DCs and T cells were supplemented with antibodies that block IL-12 and CD40L activity. RESULTS: Proliferation of CD4 T cells was stimulated by DCs primed with the same but not unrelated antigen, whereas IFN-gamma, IL-12, and IL-10 secretion were provoked equally well by DCs primed with either hapten. Blockade of CD40L engagement abrogated production of IFN-gamma (80%) and IL-12 (95%) under antigen-nonspecific stimulatory conditions. In contrast, IL-10 secretion was enhanced after CD40L blockade under both antigen-specific and nonspecific conditions. Primary CD4 T cells activated by mitogen were also influenced by DCs in the same way. CONCLUSION: These results show that during the development of chemical sensitization emerging CD4 T-cell growth and cytokine production are regulated by independent mechanisms requiring antigen presentation and CD40 signaling, respectively.