Antigen presentation by murine dendritic cells is nuclear factor-kappa B dependent both in vitro and in vivo

Antigen presentation is a key rate‐limiting step in the immune response. Dendritic cells (DCs) have been reported to be the most potent antigen‐presenting cells for naïve T cells, but little is known about the biochemical pathways that regulate this function. We here demonstrate that mature murine DC can be infected with adenovirus at high efficiency (>95%) and that an adenovirus transferring the endogenous inhibitor IκBα blocks nuclear factor‐kappa B (NF‐κB) function in murine DC. This result indicates that antigen presentation in the mixed leucocyte reaction is NF‐κB dependent, confirming data with human DC in vitro. However, the importance of this finding depends on verifying that this is true also in vivo. Using delayed type hypersensitivity with allogeneic cells, we show that NF‐κB inhibition had a marked immunosuppressive effect in vivo. These results thus establish NF‐κB as an effective target for blocking DC antigen presentation and hence inhibiting T‐cell‐dependent immune responses. This finding has potential implications for the development of therapeutic agents for use in various pathological conditions of the immune system, including allergy and autoimmunity, and also in transplantation.     

Efficacy of peripheral tolerance induced by dendritic cells is dependent on route of delivery

Previous studies have demonstrated that the route of delivery of dendritic cells (DC) is an important variable in eliciting anti-tumor immunity. In contrast, little is known about different routes of DC administration to influence peripheral tolerance in autoimmune diseases. Here we compared therapeutic effect of splenic IFN-gamma-modified-DC (IFN-gamma-DC) in actively induced experimental allergic encephalomyelitis (EAE) by different routes of DC delivery. Following subcutaneous (s.c.) injection, IFN-gamma-DC effectively suppressed clinical signs of EAE, whereas intravenous (i.v.) injection did not inhibit clinical signs of EAE. Compared to s.c. injection, i.v. injection of IFN-gamma-DC failed to mediate T cell responses, but stimulated anti-MBP antibody production and upregulated pro-inflammatory IL-1beta, IFN-gamma and TNF-alpha as well as RANTES expression which may contribute to the accumulation of inflammatory cells within the central nervous system. These results suggest that the administration route of DC should be considered as an important factor for DC-based immunotherapy in autoimmune diseases.     

Role of B70/B7-2 in CD4+ T-cell immune responses induced by dendritic cells.

Dendritic cells (DC) are potent antigen-presenting cells (APC). However, the molecular basis underlying this activity remains incompletely understood. To address this question, we generated murine monoclonal antibodies (mAb) against human peripheral blood-derived DC. One such antibody, designated IT209, stained differentiated DC and adherent monocytes, but failed to stain freshly isolated peripheral blood mononuclear cells (PBMC). The antigen recognized by IT209 was identified as B70 (B7-2; also recently identified as CD86). Using this mAb we studied the role of B70 in CD4+ T-cell activation by DC in vitro. IT209 partly inhibited the proliferative response of CD4+ T cells to allogeneic DC and to recall antigens, such as tetanus toxoid (TT) and purified protein derivative (PPD) of tuberculin, presented by autologous DC. More importantly, the mAb had a potent inhibitory effect on the primary response of CD4+ T cells to autologous DC pulsed with human immunodeficiency virus (HIV) gp160 or keyhole limpet haemocyanin (KLH). Adherent monocytes, despite their expression of B70, failed to induce T-cell responses to these antigens. IT209-mediated inhibition of CD4+ T-cell responses was equivalent to that produced by anti-CD25 mAb, whereas an anti-CD80 mAb was only marginally inhibitory and did not augment the effect of IT209. These findings indicate that the B70 antigen plays an important role in DC-dependent CD4+ T-cell activation, particularly in the induction of primary CD4+ T-cell responses to soluble antigens. However, since activated monocytes, despite their expression of B70, failed to prime naive T cells to these antigens, our results suggest that additional molecules contribute to the functions of DC in CD4+ T-cell activation.     

共刺激分子B7-2与HPV16L1联合基因免疫小鼠的免疫应答

目的：研究共刺激分子B7-2和HPV16L1重组质粒免疫小鼠的体液免疫反应。方法：用pcDNA-L1和PLXDmB7-2质粒共同肌注免疫C57BL/6小鼠，ELISA方法检测其血清抗体，红细胞凝集抑制实验和HPV16病毒样颗粒结合抑制实验检测其抗体中和活性。结论：HPV16L1和B7-2基因联合免疫小鼠的血清抗体滴度增高。结论：共刺激分子B7-2联合免疫可以增加目的抗原的抗体产生，可能是HPV16有效防治性疫苗研制更有希望的策略。     

To B or not to B: B cells and the Th2-type immune response to helminths

Similar T helper (Th)2-type immune responses are generated against different helminth parasites, but the mechanisms that initiate Th2 immunity, and the specific immune components that mediate protection against these parasites, can vary greatly. B cells are increasingly recognized as important during the Th2-type immune response to helminths, and B cell activation might be a target for effective vaccine development. Antibody production is a function of B cells during helminth infection and understanding how polyclonal and antigen-specific antibodies contribute should provide important insights into how protective immunity develops. In addition, B cells might also contribute to the host response against helminths through antibody-independent functions including, antigen presentation, as well as regulatory and effector activity. In this review, we examine the role of B cells during Th2-type immune response to these multicellular parasites.     

Recessive tolerance to preproinsulin 2 reduces but does not abolish type 1 diabetes

Although autoimmune diseases can be initiated by immunization with a single antigen, it is not clear whether a single self antigen is essential for the initiation and, perhaps, the perpetuation of spontaneous autoimmunity. Some studies have suggested that insulin may represent an essential autoantigen in type 1 diabetes. Here we show that unlike tolerance to glutamic acid decarboxylase, tolerance to transgenically overexpressed preproinsulin 2 substantially reduced the onset and severity of type 1 diabetes in nonobese diabetic mice. However, some mice still developed type 1 diabetes, suggesting that insulin is a key, but not absolutely essential, autoantigen. The results are consistent with the idea that the human IDDM2 locus controls susceptibility to type 1 diabetes by regulating intrathymic preproinsulin expression.     

术前输注供者CD80~(low)/CD86~(low)树突状细胞,延长小鼠同种异体移植心脏存活

目的 :应用B7- 1和B7- 2反义寡核苷酸 (ASB7- 1/ASB7- 2oligo)抑制CD80 (B7- 1)、CD86 (B7- 2 )在供体小鼠骨髓树突状细胞 (DC)上的表达 ,观察这类DC对同种异体小鼠心脏移植存活时间的影响并探讨其机理。方法 :小鼠B7- 1和B7- 2反义寡核苷酸在lipofectamine协助下分别转染供体鼠C5 7BL/10J(B10 )小鼠骨髓DC ,流式细胞仪检测其CD80 /CD86的表达 ,证实为CD80 low/CD86 low。将各组DC经尾静脉输注到受体小鼠C3H/HeJ(C3H)体内 ,1周后进行心脏移植术 ,观察存活时间 ;体外实验观察各组DC对同种异体T细胞的激活作用 ,包括混合淋巴细胞反应、细胞毒性效应、及IL - 2的产生。结果 :ASB7- 1和ASB7- 2分别显著抑制DC表达CD80 /CD86 ;转输这些CD80 low/CD86 lowDC可使小鼠心脏移植物存活时间显著延长 ,分别为 (18.6± 0 .89)d和 (2 3.6 7± 10 .73)d ,与转输成熟骨髓DC(IL - 4DC)组和生理盐水注射组(6 .2 2± 0 .97)d、(11.17± 1.72 )d比较 ,均有显著差异 (P <0 0 1) ;CD80 low或CD86 lowDC对异体T细胞激活作用较弱 ,表现为T细胞增殖能力、IL - 2产生及细胞毒杀伤均明显低。结论 :应用反义寡聚核苷酸转染供者DC ,降低其CD80或CD86的表达 ,可以抑制供者特异性的免疫应答 ,延长移植物存活时间。     

Mucin-1 is expressed on dendritic cells, both in vitro and in vivo

Dendritic cells (DCs) are the best professional antigen-presenting cells to stimulate cytotoxic as well as T helper cells and are therefore appropriate candidates for establishing immunotherapy. The concept of our vaccination program is to introduce the tumor-associated antigen mucin-1 (MUC1) into DCs. Analysis of immature and mature DCs--before transducing the antigen MUC1--already demonstrated expression of MUC1 on in vitro monocyte-derived DCs upon maturation. Different culture methods as well as maturation cocktails showed similar results concerning the upregulation of MUC1 expression. Furthermore, we studied the expression of MUC1 on DCs in vivo. No MUC1 expression was found on blood DCs, or on thymic or tonsil DCs. On the other hand, synovial fluid from patients with arthritis contained DCs that were found to express MUC1. This study shows for the first time that the tumor-associated antigen MUC1 is expressed on in vivo DCs. We further show that MUC1 is also expressed on in vitro cultured bone marrow-derived DCs of human MUC1 transgenic mice, supporting the relevance of this mouse model to the human situation. The observation that MUC1 is present on in vivo DCs suggests a functional role, but this physiological function remains to be elucidated.     

术前输注供者CD80low/CD86low树突状细胞，延长小鼠同种异体移植心脏存活

目的:应用B7-1和B7-2反义寡核苷酸(ASB7-1/ASB7-2oligo)抑制CD80(B7-1)、CD86(B7-2)在供体小鼠骨髓树突状细胞(DC)上的表达,观察这类DC对同种异体小鼠心脏移植存活时间的影响并探讨其机理。方法:小鼠B7-1和B7-2反义寡核苷酸在lipofectamine协助下分别转染供体鼠C57BL/10J(B10)小鼠骨髓DC,流式细胞仪检测其CD80/CD86的表达,证实为CD80^low/CD86^low。将各组DC经尾静脉输注到受体小鼠C3H/HeJ(C3H)体内,1周后进行心脏移植术,观察存活时间;体外实验观察各组DC对同种异体T细胞的激活作用,包括混合淋巴细胞反应、细胞毒性效应、及IL-2的产生。结果:ASB7-1和ASB7-2分别显著抑制DC表达CD80/CD86;转输这些CD80^low/CD86^lowDC可使小鼠心脏移植物存活时间显著延长,分别为(18.6±0.89)d和(23.67±10.73)d,与转输成熟骨髓DC(IL-4DC)组和生理盐水注射组(6.22±0.97)d、(11.17±1.72)d比较,均有显著差异(P<0.01);CD80^low或CD86^lowDC对异体T细胞激活作用较弱,表现为T细胞增殖能力、IL-2产生及细胞毒杀伤均明显低。结论:应用反义寡聚核苷酸转染供者DC,降低其CD80或CD86的表达,可以抑制供者特异性的免疫应答,延长移植物存活时间。     

Antigen-specific regression of established tumors induced by active immunization with irradiated IL-12- but not B7-1-transfected tumor cells

Transfection of modestly immunogenic tumors to express B7 family co- stimulator molecules results in their rejection by syngeneic mice, suggesting a possible clinical application in cancer patients. Immunization of naive mice with irradiated B7-1-transfected P1.HTR cells is sufficient to induce specific cytolytic T lymphocytes (CTL) and to protect against tumor challenge. However, patients to be treated will have an existing tumor burden; thus, preclinical models should examine therapeutic efficacy in an established tumor setting. Contrary to expectations, immunization of mice with irradiated B7-1-transfected P1.HTR cells had no impact on the growth of pre-established control- transfected tumors. Mice bearing control-transfected P1.HTR tumors successfully rejected living B7-1 transfectants on the contralateral flank, demonstrating the ability of tumor-bearing mice to respond to B7 co-stimulation. Inasmuch as IL-12 is another important factor for CTL maturation, P1.HTR transfectants expressing B7-1 and/or IL-12 were then constructed. Remarkably, regression of pre-established tumors was achieved following immunization with irradiated IL-12 transfectants, even without co-expression of B7-1. Rejection required a shared antigen with the tumor used for immunization, could not be reproduced with rIL- 12 alone, depended on host T lymphocytes and correlated with a high IFN- gamma-producing T cell phenotype. In addition, IL-12-facilitated tumor rejection required co-operation with a CTLA-4 ligand provided by the host, and correlated with up-regulation of B7-1 and B7-2 on host antigen-presenting cells. Thus, active immunization in the established tumor setting is benefitted greatly by the provision of IL-12, which may recruit participation of sufficient B7 co-stimulation from the host that it need not be provided exogenously.      

B7/BB-1 is a leucocyte differentiation antigen on human dendritic cells induced by activation.

Activation of a primary T-lymphocyte response requires additional signals apart from interaction of the T-cell receptor (TcR)/CD3 complex with major histocompatibility complex (MHC) antigens on the antigen-presenting cell. The CD28 antigen on T lymphocytes provides an important co-stimulatory signal to T lymphocytes and we therefore searched for the presence of its ligand, the B7/BB-1 antigen, on blood and tonsil dendritic cells (DC). Blood DC, prepared from peripheral blood mononuclear cells with a minimal period of in vitro culture, did not stain with the monoclonal antibody BB-1 using flow cytometry analysis. In contrast, tonsil DC stained weakly for B7/BB-1 compared to positive control cell lines. Polymerase chain reaction (PCR) was used to amplify a 605 base pair (bp) fragment from human B7/BB-1 mRNA and demonstrated significant amounts of B7/BB-1 mRNA in tonsil DC but no specific product was obtained from blood DC, confirming the surface-staining results. Weak expression of B7/BB-1 antigen was detected by immunofluorescence analysis following culture of blood DC with either interferon-gamma (IFN-gamma) or granulocyte-macrophage colony-stimulating factor (GM-CSF). These data support the concept that blood DC give rise to tissue and/or lymphoid DC, which acquire co-stimulatory ligands as a result of activation and/or differentiation.     

Autologous dendritic cells or cells expressing both B7-1 and MUC1 can rescue tumor-specific cytotoxic T lymphocytes from MUC1-mediated apoptotic cell death

We attempted to induce MUC1-specific cytotoxic T lymphocytes (CTLs) by mixed-lymphocyte tumor cell culture (MLTC) using two allogeneic MUC1-positive cancer cell lines, T-47D and MCF7. The induced CTLs exhibited MUC1-specific cytotoxicity 16 days after the initial stimulation. However, these CTLs underwent apoptotic death within 16 days. To examine whether the B7-1 molecule is required for the expansion of the responder cells, a B7-1(+)/MUC1(-) cell line was transfected with MUC1 cDNA, and the resulting transfectant was employed as a stimulator in an autologous MLTC. The CTLs exhibited MUC1 specificity but also continued to propagate. In parallel, autologous dendritic cells (DCs) were added to an MLTC containing peripheral blood lymphocytes (PBLs) and the allogeneic MUC1-positive stimulators. The CTLs demonstrated MUC1 specificity and their number increased. This suggests that the B7-1 molecule is required for rescuing CTLs from MUC1-mediated apoptotic death, but not for the induction of MUC1-specific responsiveness. This strategy to obtain the CTLs efficiently may be useful for adoptive immunotherapy against cancer.     

B7-2表达质粒对HBV DNA疫苗诱导的特异性免疫应答的影响

目的：探讨B7－2分子是否能够增强乙型肝炎病毒（HBV）DNA疫苗诱导的特异性免疫应答。方法：将B7－2表达质粒与HBV DNA疫苗共接种于小鼠腓肠肌内，检测细胞毒性T淋巴细胞（CTL）活性，迟发性超敏反应（DTH）及抗－HBs滴度。结果：B7－2表达质粒与HBV DNA疫苗共接种组的DTH反应和CTL活性，明显强于单独接种HBV DNA疫苗组（P＜0．01）。两组的抗－HBs滴度差异无显著性（P＞0．05）。结论：B7－2表达质粒与HBV DNA疫苗共接种可显著增强抗－HBV特异性细胞免疫应答（CMI）。     

可溶性小鼠BTLA对树突状细胞表面B7-1和B7-2表达的影响

目的研究可溶性小鼠B/T淋巴细胞弱化因子（murine B and T lymphocyte attenuator ，mBTLA）-人IgG1 Fc融合蛋白（mBTLA-hIg）对树突状细胞表面共刺激分子表达的影响。方法克隆mBT／A基因，构建mBTLA胞外功能区和人IgG1Fc融合基因的真核表达载体（pmBTLA-hIg），并采用脂质体转染法，将pmBTLA-hIg质粒转染小鼠树突状细胞系（DC2．4）。采用RT-PCR、ELISA和Westem blot分别检测pmBTLA-hIg质粒转染DC中mBTLA基因mBNA的表达及细胞培养上清中mBTLA-hIg融合蛋白的表达；采用流式细胞术检测pmBTLA-hIg质粒转染对DC2．4表面共刺激分子B7-1（CD80）和B7-2（CD86）表达的影响。结果成功克隆了小鼠BT／A基因，并构建了真核表达载体；mBTLA-hIg融合基因转染的DC高表达mBTLA-hIg融合蛋白，并可结合到DC表面。表达可溶性mBTLA-hIg融合蛋白的DC2．4表面B7．1的表达上调，B7-2的表达下调，而且这种改变可被兔抗GST-mBTLA血清阻断。结论可溶性mBTLA-hIg融合蛋白对DC细胞表面研分子的表达具有调节作用，可能是BTLA反向信号作用于DC的结果。     

Heterodimerization of TLR2 with TLR1 or TLR6 expands the ligand spectrum but does not lead to differential signaling

TLR are primary triggers of the innate immune system by recognizing various microorganisms through conserved pathogen-associated molecular patterns. TLR2 is the receptor for a functional recognition of bacterial lipopeptides (LP) and is up-regulated during various disorders such as chronic obstructive pulmonary disease and sepsis. This receptor is unique in its ability to form heteromers with TLR1 or TLR6 to mediate intracellular signaling. According to the fatty acid pattern as well as the assembling of the polypeptide tail, LP can signal through TLR2 in a TLR1- or TLR6-dependent manner. There are also di- and triacylated LP, which stimulate TLR1-deficient cells and TLR6-deficient cells. In this study, we investigated whether heterodimerization evolutionarily developed to broaden the ligand spectrum or to induce different immune responses. We analyzed the signal transduction pathways activated through the different TLR2 dimers using the three LP, palmitic acid (Pam)octanoic acid (Oct)(2)C-(VPGVG)(4)VPGKG, fibroblast-stimulating LP-1, and Pam(2)C-SK(4). Dominant-negative forms of signaling molecules, immunoblotting of MAPK, as well as microarray analysis indicate that all dimers use the same signaling cascade, leading to an identical pattern of gene activation. We conclude that heterodimerization of TLR2 with TLR1 or TLR6 evolutionarily developed to expand the ligand spectrum to enable the innate immune system to recognize the numerous, different structures of LP present in various pathogens. Thus, although mycoplasma and Gram-positive and Gram-negative bacteria may activate different TLR2 dimers, the development of different signal pathways in response to different LP does not seem to be of vital significance for the innate defense system.     

Tim-1 is induced on germinal centre B cells through B-cell receptor signalling but is not essential for the germinal centre response

T‐cell immunoglobulin mucin‐1 (Tim‐1) has been proposed to be an important T‐cell immunoregulatory molecule since its expression on activated T cells was discovered. To study the role of Tim‐1 on T cells in vitro and in vivo we generated both Tim‐1‐deficient mice and several lines of Tim‐1 transgenic mice with Tim‐1 expression on either T cells, or B and T cells. We demonstrate that neither deficiency nor over‐expression of Tim‐1 on B and T cells results in modulation of their proliferation in vitro. More surprisingly, T helper type 2 cells generated either from Tim‐1‐deficient mice or Tim‐1 transgenic mice did not show enhancement of interleukin‐4 (IL‐4), IL‐5 and IL‐10 production. Furthermore, using a Schistosoma mansoni egg challenge as a potent T helper type 2 response inducer we also show that Tim‐1 is not essential for T‐ and B‐cell responses in vivo. However, we observe induction of Tim‐1 on B cells following B‐cell receptor (BCR), but not Toll‐like receptor 4 stimulation in vitro. We show that the induction of Tim‐1 on B cells following BCR stimulation is phosphoinositide‐3 kinase and nuclear factor‐κB pathway dependent. More importantly, we conclude that Tim‐1 is predominantly expressed on germinal centre B cells in vivo although the percentage of germinal centre B cells in wild‐type and Tim‐1‐deficient mice is comparable. Identification of Tim‐1 as a marker for germinal centre B cells will contribute to the interpretation and future analysis of the effects of the anti‐Tim‐1 antibodies in vivo.     

Association of B7-1 co-stimulation with the development of graft arterial disease. Studies using mice lacking B7-1, B7-2, or B7-1/B7-2

To investigate the roles of B7-1 and/or B7-2 co-stimulatory molecule in the development of graft arterial disease (GAD), major histocompatibility complex (MHC) class II-mismatched allograft hearts were transplanted into wild-type, B7-1(-/-), B7-2(-/-), or B7-1/B7-2(-/-) recipient mice. Grafts were explanted at 4 or 8 weeks and used for histological and immunohistochemical analyses, RNase protection assay, and flow cytometry of graft infiltrating cells. Grafts in wild-type recipients showed macrophage, recipient MHC class II, and B7 molecule co-localization by immunohistochemistry to GAD lesions. Flow cytometry revealed that CD11b(+) and MHC class II(+) graft infiltrating cells expressed B7-1 more than B7-2, whereas B7-2 expression was predominant in CD11b(-) cells at 4 and 8 weeks. GAD was significantly attenuated in the allografts in B7-1(-/-) and B7-1/B7-2(-/-) but not in B7-2(-/-) recipients compared to wild-type hosts. Interferon-gamma mRNA levels were comparable in all graft combinations, whereas interleukin-4 mRNA levels decreased in grafts in B7-2 deficient hosts, but did not correlate with GAD attenuation. The findings indicate distinct roles for B7-1 and B7-2 co-stimulatory molecules in the development of GAD, potentially because of differential expression of B7-1 and B7-2 molecules on distinct stimulator and/or effector cell populations.     

Allergen-specific immune deviation from a TH2 to a TH1 response induced by dendritic cells and collagen type I.

BACKGROUND: Atopy and IgE production are associated with enhanced allergen-specific T(H)2 responses. Therefore a causative treatment may result from the deviation of this T(H)2-dominated immune response toward a T(H)1 response. OBJECTIVE: This study was carried out to analyze whether dendritic cells, the most potent antigen-presenting cells that are also known to induce antigen-specific T(H)1 responses, are suitable for therapy of atopic diseases by shifting the allergen-specific T(H)2 response toward a T(H)1 response. METHODS: Monocyte-derived dendritic cells were used to present allergens in vitro to autologous CD4(+) T cells of allergic persons. Because collagen type I activates dendritic cells and enhances the secretion of IL-12, we performed allergen presentation assays also in the presence of collagen type I. RESULTS: After stimulation with allergen-pulsed dendritic cells the production of IFN-gamma as well as that of IL-4 and IL-5 by CD4(+) T cells was enhanced. In the presence of collagen type I, however, a significant shift toward a T(H)1 response with increased production of IFN-gamma and a decreased production of IL-5 could be observed. When T cells were stimulated directly with anti-CD3 and anti-CD28 in the absence of antigen-presenting cells, it was demonstrated that collagen type I also exerted a direct effect on T cells, increasing their IFN-gamma production. CONCLUSION: These data indicate that collagen type I influences dendritic cells as well as T cells in a way that a shift in cytokine production results in a T(H)1 response even in already-sensitized atopic individuals.     

Delta-like 1 is necessary for the generation of marginal zone B cells but not T cells in vivo

Notch receptors and their ligands contribute to many developmental systems, but it is not apparent how they function after birth, as their null mutants develop severe defects during embryogenesis. Here we used the Cre-loxP system to delete the Delta-like 1 gene (Dll1) after birth and demonstrated the complete disappearance of splenic marginal zone B cells in Dll1-null mice. In contrast, T cell development was unaffected. These results demonstrated that Dll1 was dispensable as a ligand for Notch1 at the branch point of T cell-B cell development but was essential for the generation of marginal zone B cells. Thus, Notch signaling is essential for lymphocyte development in vivo, but there is a redundancy of Notch-Notch ligand signaling that can drive T cell development within the thymus.