树突细胞与哮喘Th1/Th2失衡

特应性哮喘患者以Th2免疫反应为主,导致气道炎症,Th1／Th2失衡是特庆性哮喘重要的免疫病理机制,树突细胞（DCs）中肺部主要抗原递呈细胞,不但可以介志对吸入抗原初始的免疫反应,活化辅助性T细胞,而且在可以决定T细胞的分化方向,维持哮喘Th2免疫反应和Th1／Th2失衡机制中发挥重要作用而日益受到重视。本文就近年来对特应性哮喘免疫病理机制中DCs对Th1／Th2失衡影响认识作一综述。     

Circulating interferon-gamma- and interleukin-4-secreting cells in recurrent spontaneous abortions.

PROBLEM: Are recurrent spontaneous abortions (RSAs) associated with deviation of circulating cytokine-secreting cells? METHOD OF STUDY: Interferon (IFN)-γ- and interleukin (IL)-4-secreting cells were identified by enzyme-linked immunospot (ELISPOT) in blood from 34 women with RSA. Samples were taken before pregnancy and/or pregnancy weeks 7–10, 17–20, and after terminated pregnancy. Eleven healthy primigravidae and 10 nonpregnant women served as controls. RESULTS: No significant difference in numbers of IFN-γ- and IL-4-secreting cells was noted within the RSA group when abortions and successful pregnancies were compared in samples taken before pregnancy. The number of IFN-γ- as well as IL-4-secreting cells in pregnancy weeks 17–20 in the RSA group was significantly higher compared with before pregnancy, pregnancy weeks 7–10, and after pregnancy. In samples from non-pregnant women, the number of IFN-γ- and IL-4-secreting cells was significantly higher in the RSA group compared with controls. CONCLUSIONS: Our results do not indicate a systemic shift in the general balance between T helper 1- and T helper 2-type cytokine pattern. A local shift at the fetomaternal interface seems more probable.     

Neonatal dendritic cells are intrinsically biased against Th-1 immune responses

Dendritic cells (DCs) were derived from human peripheral blood monocytes or cord blood monocytes cultured in the presence of IL-4 and GM-CSF. Adult and cord DCs were observed to have comparable immature phenotypes. However, the increase in surface expression of HLA-DR and CD86 after addition of LPS was significantly attenuated in cord DCs, with CD25 and CD83 expression also markedly reduced. Cord DCs were also unable to produce IL-12p70, failed to down-regulate expression of the chemokine receptor CCR5 and induced lower levels of IFN-gamma production from allogeneic naive CD4+ T cells than their adult counterparts. In contrast, the kinetics of the production of TNF-alpha and IL-10 in response to LPS stimulation was comparable to adult DCs. The reduced ability of cord DCs to attain a fully mature adult phenotype, and to activate naive CD4+ T cells to produce IFN-gamma, suggests that they are intrinsically preprogrammed against the generation of Th-1 immune responses.     

Differential CD4(+) T-cell memory responses induced by two subsets of human monocyte-derived dendritic cells

Dendritic cells (DC) are powerful inducers of primary T-cell responses, but their role in secondary responses has not been extensively analysed. Here, we address the role of two DC subsets derived from human CD16(+) (16(+) mDC) or CD16(-) (16(-) mDC) monocytes on the reactivation of memory responses. CD4(+) CD45RA(-) memory T cells were obtained from adult blood donors, and central (T(CM)) and effector (T(EM)) memory T cells were isolated by fluorescence-activated cell sorting with anti-CCR7 antibodies. The 16(+) mDC and 16(-) mDC were cocultured with autologous lymphocytes, either unpulsed or loaded with purified protein derivatives of Mycobacterium tuberculosis (PPD) or tetanus toxoid (TT), and were analysed for up to 8 days. Over a range of doses, 16(+) mDC drove stronger T-cell proliferative responses against both antigens. Overall, antigen-specific memory cells tended to acquire a phenotype of T(EM) at later time-points in the culture, whereas cells that had completed fewer cycles of division were similar to T(CM). The 16(+) mDC induced higher rates of proliferation on both T(CM) and T(EM) lymphocytes than 16(-) mDC. This phenomenon was not related to the ability of both DC to induce CD25 expression on T cells, to lower secretion of interleukin-2, or to raise production of interleukin-10 during T-cell/16(-) mDC cocultures. The induction of T(CM) effector capacity in terms of interferon-gamma production was faster and more pronounced with 16(+) mDC, whereas both DC had similar abilities with T(EM). In conclusion, these data might reveal new potentials in vaccination protocols with 16(+) mDC aimed at inducing strong responses on central memory T cells.     

树突细胞与支气管哮喘

作为抗原呈递细胞,树突细胞是识别抗原并将其呈递给免疫系统细胞的主要细胞。呼吸道树突细胞在气道黏膜下捕捉抗原,游走至引流淋巴结,将抗原呈递给初始T淋巴细胞。本义通过文献复习,综述了树突细胞的分布,免疫学特性及其生物学功能。并阐述近年来对哮喘病人及哮喘动物模型树突细胞的研究结果。目前认为树突细胞是诱导和维持嗜酸性细胞气道炎症的基础,这一认识为支气管哮喘的预防和治疗提供了新的思路。     

Prognostic values of serum IP-10 and IL-17 in patients with pulmonary tuberculosis

Objective: To identify patients at high risk of relapse after anti-tuberculosis (TB) therapy or with poor long-term outcomes. Methods: Fifty-one patients with pulmonary TB: 7 were classified as high association with both cavitations on initial chest radiography and positive sputum smear/cultures after two months of anti-TB treatment (HA group); 19 medium association (MA, one risk alone); and 25 low association (LA, neither risk). Serum interferon (IFN)-γ-inducible protein 10 (IP-10), interleukin-17 (IL-17), and C-reactive protein levels were investigated. Results: There was a trend towards higher serum IP-10 levels (p = 0.042) for HA patients throughout the 6-month treatment period. Month-2 IP-10 levels were higher in the HA than in the MA/LA group (656.2 ± 234.4 vs. 307.6 ± 258.5 pg/ml, adjusted p = 0.005). Receiver operating characteristic curves showed that the risk of relapse was well-captured by month-2 IP-10 levels at a cut-off value of 431 pg/ml (AUC=0.857, 95% CI 0.75–0.97, p = 0.003). Month-2 serum IL-17 levels were lower in non-survivors than survivors (15.7 ± 2.9 pg/ml vs. 24.6 ± 8.2 pg/ml, p = 0.001). Multivariate analysis demonstrated that a month-2 serum IL-17 level of ≤ 17 pg/ml (p = 0.026) was independently associated with all-cause mortality. Conclusions: Serum IP-10 and IL-17 levels after 2 months of anti-TB treatment may be biomarkers for estimating risk of both cavitation and delayed sputum conversion, and for predicting long-term mortality, respectively.     

Circulating dendritic cells and interferon-alpha production in patients with tuberculosis: correlation with clinical outcome and treatment response

Dendritic cells (DC) have been characterized recently as having an important role in the initiation and control of immunological response to Mycobacterium tuberculosis infection. Blood DC have been subdivided into myeloid (mDC) and plasmacytoid (pDC) subsets, on the basis of differences in phenotype markers and function. Little is known about the enumeration and functional evaluation of circulating DC in patients with tuberculosis and their correlation with clinical outcome during the course of anti-tuberculous treatment. We assessed circulating mDC and pDC counts measured by a newly developed single-platform flow cytometric assay based on TruCOUNT, as well as the production of interferon (IFN)-alpha after in vitro stimulation by herpes simplex virus (HSV-1) in 24 patients with active tuberculosis (TB) and 37 healthy donors. Absolute numbers of both DC subsets were decreased significantly in patients with active TB compared to controls. Similarly, the production of IFN-alpha was highly impaired. In 13 patients these parameters were assessed longitudinally, before and after the specific anti-microbial treatment. Most interestingly, in all nine patients with successful anti-tuberculous therapy there was a significant and marked increase of pDC counts and IFN-alpha production. In contrast, no significant longitudinal variations in DC counts and IFN-alpha production were observed in four patients with lack of response to specific treatment. In conclusion, active TB is associated with a defect in blood DC numbers and IFN-alpha production that is restored after bacterial clearance and clinical improvement, as a result of effective anti-tuberculous treatment.     

结核病患者外周血树突状细胞及其亚群的变化

目的:分析不同结核病患者外周血树突状细胞(DCs)及其亚群的变化,并进行免疫机制探讨。方法:就诊于我院2008-11/2009-08的结核病患者32例(实验组),同期在我院进行健康体检者11例(对照组),采用流式细胞术(FCM)检测了结核病患者(包括19例初治患者和13例复治患者,以及痰涂片结果不同的19例肺结核患者)和对照组中外周血中DCs及其亚群的变化。结果:实验组DC1亚群的比率和DCs的总数分别为(0.28±0.13)%和(0.42±0.19)%,明显低于对照组的DC1亚群的比率和DCs的总数(0.47±0.23)%和(0.65±0.22)%(P0.01)。痰涂片阳性患者外周血中DC1亚群的比率和DCs的总数分别为(0.16±0.04)%和(0.24±0.06)%,明显低于痰涂片阴性患者DC1亚群的比率和DCs的总数(0.28±0.14)%和(0.43±0.12)%(P0.05)。初治患者与复治患者外周血中DCs的总数及其亚群的比率无统计学意义(P0.05)。结论:DCs可作为结核病传染源初筛和抗结核疗效观察的参考指标,反映不同结核病患者的免疫状态。     

Dendritic cells exposed in vitro to TGF-beta1 ameliorate experimental autoimmune myasthenia gravis

Experimental autoimmune myasthenia gravis (EAMG) is an animal model for human myasthenia gravis (MG), characterized by an autoaggressive T-cell-dependent antibody-mediated immune response directed against the acetylcholine receptor (AChR) of the neuromuscular junction. Dendritic cells (DC) are unique antigen-presenting cells which control T- and B-cell functions and induce immunity or tolerance. Here, we demonstrate that DC exposed to TGF-beta1 in vitro mediate protection against EAMG. Freshly prepared DC from spleen of healthy rats were exposed to TGF-beta1 in vitro for 48 h, and administered subcutaneously to Lewis rats (2 x 10(6)DC/rat) on day 5 post immunization with AChR in Freund's complete adjuvant. Control EAMG rats were injected in parallel with untreated DC (naive DC) or PBS. Lewis rats receiving TGF-beta1-exposed DC developed very mild symptoms of EAMG without loss of body weight compared with control EAMG rats receiving naive DC or PBS. This effect of TGF-beta1-exposed DC was associated with augmented spontaneous and AChR-induced proliferation, IFN-gamma and NO production, and decreased levels of anti-AChR antibody-secreting cells. Autologous DC exposed in vitro to TGF-beta1 could represent a new opportunity for DC-based immunotherapy of antibody-mediated autoimmune diseases.     

CTLA4-Ig基因修饰的树突状细胞体外对Th1/Th2平衡的影响

目的:探讨细胞毒性T淋巴细胞相关抗原4免疫球蛋白(CTLA4 Ig)基因修饰的树突状细胞(CTLA4 Ig-DCs)体外对Th1/Th2平衡的影响。方法:通过腺病毒载体将目的基因(CTLA4 Ig)转染至小鼠骨髓来源的树突状细胞(DC)。采用流式细胞术(FCM)检测DC表面分子和胞内CTLA4 Ig的表达;采用混合淋巴细胞反应检测DC刺激同种异体T细胞的能力,ELISA法检测DC抗原提呈反应中Th1和Th2类细胞因子IFN-γ和IL-4分泌水平。结果:CTLA4 Ig基因成功转染至DC,转染率约为80%,制备的CTLA4 Ig-DCs稳定表达CTLA4Ig,表面分子CD86呈现低表达;CTLA4 Ig-DCs可有效抑制T细胞增殖,降低抗原提呈反应上清中IFN-γ和IL-4的分泌,并增加IFN-γ/IL-4比值。结论:通过腺病毒将CTLA4 Ig转染DC并且高效表达,可有效降低DC表面CD86分子,抑制同种异体T细胞反应,并能影响体外Th1/Th2水平。     

Cultures derived from peripheral blood CD34+ progenitor cells of head and neck cancer patients and from cord blood are functionally different

Patients with head and neck squamous cell carcinoma (HNSCC) have profound immune defects mediated, in part, by an increased number of immune suppressive CD34⁺ progenitor cells in their peripheral blood and tumor. One means of overcoming this immune suppression is to stimulate the CD34⁺ cells to differentiate into more mature, nonsuppressive progeny such as dendritic cells or monocytes. This study determined that CD34⁺ cells from the peripheral blood of HNSCC patients have the same potential to differentiate into dendritic cells as do human umbilical cord blood CD34⁺ cells following 12–16 days of culture with a cytokine cocktail. When compared functionally, the cultures that developed from CD34⁺ cells of cord blood were able to induce an allostimulatory response in naive T-cells, while the cultures that developed from patient CD34⁺ cells lacked allostimulatory ability. Both cultures expressed class II MHC (HLA-DR), but the proportion of cells expressing the costimulatory molecules CD80 and CD86 was significantly less in cultures that developed from HNSCC-patient CD34⁺ cells. Therefore, although the CD34⁺ cells from the peripheral blood of HNSCC patients can differentiate into dendritic cells, their allostimulatory capabilities are impaired, raising the question of their potential effectiveness in stimulating antitumor immune responses.     

树突状细胞的生物学特性及临床应用

1 引言肿瘤的免疫治疗是目前肿瘤临床治疗的重要趋势，其中主动免疫的方法之一是通过注射抗原提呈细胞刺激淋巴细胞产生抗肿瘤效应。树突状细胞(Dendritic Cell, DC)被认为是最佳的抗原提呈细胞。树突状细胞在非淋巴组织内吞噬抗原物质，与MHC抗原结合，将抗原信息表达于细胞表面，通过血液或淋巴液迁徒至淋巴组织，激活初始淋巴细胞，产生免疫反应[1]。另一方面树突状细胞又具有免疫耐受功能，可用于控制免疫损伤反应。近些年，从骨髓或外周血体外诱导生成一定数量的树突状细胞供生物学研究乃至临床应用已成为现实[2，3]。树突状细胞生…     

Dendritic cells infected with adenovirus expressing the thyrotrophin receptor induce Graves' hyperthyroidism in BALB/c mice

Dendritic cells (DCs) are the most potent antigen-presenting cells and a prerequisite for the initiation of primary immune response. This study was performed to investigate the contribution of DCs to the initiation of Graves' hyperthyroidism, an organ-specific autoimmune disease in which the thyrotrophin receptor (TSHR) is the major autoantigen. DCs were prepared from bone marrow precursor cells of BALB/c mice by culturing with granulocyte macrophage-colony stimulating factor and interleukin-4. Subcutaneous injections of DCs infected with recombinant adenovirus expressing the TSHR (but not beta-galactosidase) in syngeneic female mice induced Graves'-like hyperthyroidism (8 and 35% of mice after two and three injections, respectively) characterized by stimulating TSHR antibodies, elevated serum thyroxine levels and diffuse hyperplasitc goiter. TSHR antibodies determined by ELISA were of both IgG1 (Th2-type) and IgG2a (Th1-type) subclasses, and splenocytes from immunized mice secreted interferon-gamma (a Th1 cytokine), not interleukin-4 (a Th2 cytokine), in response to TSHR antigen. Surprisingly, IFN-gamma secretion, and induction of antibodies and disease were almost completely suppressed by co-administration of alum/pertussis toxin, a Th2-dominant adjuvant, whereas polyriboinosinic polyribocytidylic acid, a Th1-inducer, enhanced splenocyte secretion of IFN-gamma without changing disease incidence. These observations demonstrate that DCs efficiently present the TSHR to naive T cells to induce TSHR antibodies and Graves'-like hyperthyroidism in mice. In addition, our results challenge the previous concept of Th2 dominance in Graves' hyperthyroidism and provide support for the role of Th1 immune response in disease pathogenesis.     

Kinetics and expression patterns of chemokine receptors in human CD4+ T lymphocytes primed by myeloid or plasmacytoid dendritic cells

We investigated the kinetics of expression of 12 chemoattractant receptors as a function of cell division following priming of human naive CD4+ T cells by different populations of dendritic cells (DC) and under conditions favoring Th1 or Th2 differentiation. Two chemokine receptors, CXCR3 and CXCR5, were rapidly up-regulated following T cell activation by either monocyte-derived DC, myeloid DC (mDC) or plasmacytoid DC (pDC). While CXCR5 expression was transient, expression of CXCR3 at advanced cell divisions was dependent on differentiation, being expressed at high levels on Th1 cells. Several other receptors (CCR2, CCR3, CCR4, CCR5, CXCR6 and CRTh2) were acquired progressively as a function of cell division and in a fashion that was influenced by polarizing cytokines. The Th2-associated chemoattractant receptors CRTh2 and CCR3 were up-regulated with slower kinetics compared to the Th1-associated receptors CXCR3 and CXCR6, consistent with a different kinetics and efficiency of polarization. Moreover, CCR4 and CXCR6 were preferentially induced in T cells activated by mDC and pDC, respectively. Finally, CXCR5 and CCR7 were also rapidly and transiently up-regulated in memory T cells following TCR stimulation. These results indicate a complex chemokine receptor regulation dependent on both T cell activation and differentiation state. In addition, they reveal the existence of DC-specific cues for the regulation of T cell migratory capacity.     

Dose-dependent synergy of Th1-stimulating cytokines on bacille Calmette-Guérin-induced interferon-gamma production by human mononuclear cells

Successful bacille Calmette-Guérin (BCG) immunotherapy of bladder cancer depends on the proper induction of a T helper-type 1 (Th1) immune response. In this study we investigated the possible involvement of Th1-stimulating cytokines in BCG-induced interferon (IFN)-gamma production as well as their potential roles in enhancing BCG-induced IFN-gamma from human peripheral blood mononuclear cells (PBMCs). BCG efficiently induced IFN-gamma production by PBMCs in a dose-dependent manner. Neutralization of endogenous cytokines interleukin (IL)-2, IL-12 and IFN-alpha reduced BCG-induced IFN-gamma by 38%, 67% and 49%, respectively. Although single recombinant (r) IL-2, rIL-12 and rIFN-alpha induced no or a marginal amount of IFN-gamma, a combination of any two or three cytokines increased IFN-gamma production. When BCG (a subsaturated dose) was combined with mono, dual or triple cytokines, a synergy on IFN-gamma production was observed. Such a synergy was readily achievable even when minimal or low doses of cytokines were used. No saturation of IFN-gamma production was observed even when a subsaturated BCG dose was combined with very high doses of cytokines. A robust IFN-gamma production was also observed when a minimal BCG dose was combined with minimal doses of triple cytokines. In addition, we demonstrated that IL-2- and IFN-alpha-expressing rBCGs were superior to wild-type BCG for PBMC IFN-gamma induction and that combination of both rBCGs showed a synergy in IFN-gamma production. Taken together, these results suggest that combination of BCG with certain exogenous or endogenous (expressed by rBCGs) Th1-stimulating cytokines is a rational candidate for further study in bladder cancer treatment.     

树突状细胞疫苗与泌尿系统肿瘤的生物治疗

肿瘤生物治疗的基本策略之一是激活肿瘤抗原特异性的细胞毒T细胞,诱导抗肿瘤免疫反应,这一过程必须要有抗原提呈细胞的参与.树突状细胞的抗原提呈功能极强,它能激活幼稚T细胞分化增殖,并建立初级免疫反应.近年来研究应用多种形式的抗原(肿瘤细胞裂解物、肿瘤蛋白、RNA等)负载树突状细胞,再将经过修饰的树突状细胞回输入动物模型或人体内,取得了较好的效果.本文综述了近年树突状细胞的研究进展及其在泌尿系统肿瘤的中研究和应用情况.     

Dendritic cells respond to influenza virus through TLR7- and PKR-independent pathways

Natural interferon-producing cells (IPC) secrete type I IFN (IFN-alpha and -beta) in response to influenza virus. This process is independent of viral replication and is mediated by Toll-like receptor 7 (TLR7), which recognizes single-stranded RNA (ssRNA). DC also express TLR7 but its function in DC response to influenza virus is unknown. To address this, we compared the DC and IPC responses to influenza virus and ssRNA oligoribonucleotides (ORN) that activate TLR7. When stimulated by ORN in vitro and in vivo, DC matured and produced inflammatory cytokines but not IFN-alpha. DC did secrete IFN-alpha in response to influenza virus. However, this response was independent of TLR7 signaling and required viral replication but not dsRNA-activated protein kinase (PKR). We conclude that DC and IPC are hard-wired to secrete IFN-alpha via different pathways, reflecting their complementary but distinct roles in anti-viral immunity.     

Beyond macrophages: the diversity of mononuclear cells in tuberculosis

Mycobacterium tuberculosis, the bacterium that causes tuberculosis (TB), is an intracellular pathogen of mononuclear phagocytes. Although M. tuberculosis has traditionally been thought to survive and replicate in macrophages, recent work in our laboratory and others has revealed that M. tuberculosis infects multiple subsets of mononuclear phagocytes in vivo and in vitro. In experimental animals, M. tuberculosis infects no fewer than five distinct cell subsets in the lungs, including resident alveolar macrophages and 4 types of cells that recruited to the lungs in response to inflammatory signals: neutrophils, monocytes, interstitial macrophages, and dendritic cells. A characteristic of the adaptive immune response in TB is that it is delayed for several weeks following infection, and we have determined that this delay is due to prolonged residence of the bacteria in lung phagocytes prior to acquisition of the bacteria by dendritic cells. Among the mechanisms used by M. tuberculosis to delay acquisition by dendritic cells is to inhibit apoptosis of alveolar macrophages and neutrophils, which sequester the bacteria and prevent their acquisition by dendritic cells in the early stages of infection. We hypothesize that each infected cell subset makes a distinct contribution to the overall biology of M. tuberculosis and allows the bacteria to evade elimination by T-cell responses and to avoid rapid killing by antimycobacterial drugs.