树突状细胞在抗感染免疫研究中的最新进展

树突状细胞(Dendritic cell,DC)是体内功能最强的抗原提呈细胞,也是介导机体固有免疫应答和适应性免疫应答的桥梁,其作用也越来越受到科研工作者的关注,而树突状细胞体外培养技术的发展成熟,为设计和发展DC依赖性疫苗提供了科学依据,也为感染性和肿瘤性疾病的预防和治疗展示了很好的应用前景。因此,对树突状细胞抗感染免疫方面研究的最新进展做一综述。     

SOCS1基因修饰树突状细胞在肿瘤治疗中的研究进展

树突状细胞是功能最强的抗原提呈细胞,是启动、调节及维持免疫应答的核心环节,以树突状细胞为基础的肿瘤疫苗被认为是最具潜能的肿瘤免疫治疗手段。细胞因子信号通路抑制因子1（suppressor ofcytokine signaling1,SOCS1）是细胞因子信号通路抑制因子（suppressor of cytokine signaling,SOCS）家族的重要成员,广泛参与树突状细胞的发生、成熟和活化,具有负调控树突状细胞功能的重要作用。SOCS1沉默的树突状细胞能够促进自身成熟并增强其诱导的T细胞的抗肿瘤活性。现就国内外关于树突状细胞功能研究及基因修饰的肿瘤疫苗临床试验作一综述,以期对未来的研究有所帮助。     

大鼠骨髓来源未成熟与成熟树突状细胞的对比研究

目的:对比培养大鼠骨髓来源的未成熟树突状细胞与成熟树突状细胞,并从形态学、表型及功能检测等多方面进行对比研究,为后续的实验做出基础研究。方法:大鼠脱臼法处死后取两侧胫骨、股骨,PBS冲洗骨髓腔收集骨髓细胞,经GM-CSF和IL-4刺激培养六天后,对比研究经LPS刺激组与未经LPS刺激培养组细胞状况。结果:①成熟树突状细胞悬浮生长,集落分散,扫描电镜下见其突起数目明显多于未成熟树突状细胞。②成熟树突状细胞高表达表面标记分子CD80、CD86、MHCⅡ,而未成熟树突状细胞均低表达。③成熟树突状细胞培养基上清中IL-12水平高,而未成熟树突状细胞培养基上清中IL-12水平低。④成熟树突状细胞具有强的刺激T细胞增殖能力,而未成熟树突状细胞基本不具有诱导T细胞增殖能力。结论:未成熟状态的树突状细胞具备致耐受原性,可抑制T细胞的应答,而成熟状态的树突状细胞由于获得了免疫刺激潜能从而会对炎性刺激做出反应。     

肝癌免疫逃逸机制的研究进展

肿瘤免疫逃逸在肝癌发生发展中起着重要作用。树突状细胞和免疫细胞的不成熟或功能低下将导致机体免疫功能被抑制而促进肝癌的发生发展。多种细胞因子如IL-10、TGF-β、VEGF等会抑制机体免疫功能使肝癌生长增殖或直接促进肿瘤的发生发展。肝癌细胞分泌Fas L及其表面Fas的表达减少会诱导免疫细胞凋亡或避免T细胞等免疫细胞的杀伤作用从而逃避机体免疫作用。因此,本文将从免疫细胞、肿瘤细胞本身以及两者间的相互作用三个方面阐述肝癌免疫逃逸的分子机制。     

肿瘤来源的抑制性细胞因子影响树突状细胞的微观流变特性并导致免疫应答恶化

现已证明,在肿瘤发生过程中,司职抗原呈递的树突状细胞的功能存在缺陷和紊乱,从而导致了免疫系统的显著受抑和肿瘤的免疫逃逸.为了探索肿瘤的免疫逃逸机制,利用生物物理学和微观流变学的方法研究了肿瘤来源因素对树突状细胞(dendriticcells,DCs)分化过程的影响.发现来源于肿瘤微环境的细胞因子等成分,导致DCs的渗透脆性增加、细胞膜脂流动性显著下降,而且细胞的转录水平和能量状态也明显改变,导致DCs的抗原摄取能力和活化幼稚T细胞的能力显著下降.所以,DCs的微观流变特性的改变也许是肿瘤免疫逃逸机制的一个方面.     

脂肪酸转运蛋白2(Fatp2)与肿瘤免疫抑制

正多形核髓系抑制细胞(polymorphonuclear myeloid derived suppressor cells,PMN-MDSC)是一种在病理状态下被激活的中性粒细胞;尽管其与中性粒细胞起源相同;但这类细胞的功能,却是抑制肿瘤免疫、促进肿瘤生长与转移,与肿瘤预后不良及治疗效果不佳相关。近年来研究揭示,"脂类积累"(lipid accumulation)现象,存在于癌症组织巨噬细胞、树突状细胞和髓系抑制细胞(myeloid     

透明质酸孵育树突状细胞对荷瘤小鼠免疫功能的影响

目的：研究透明质酸对小鼠骨髓来源树突状细胞功能的影响以及回输后荷黑色素瘤小鼠脾淋巴细胞增殖、活化和细胞因子 的变化,进而探讨透明质酸诱导的树突状细胞增强荷瘤小鼠免疫功能的机制。方法：体外细胞因子联合诱导培养小鼠骨髓细胞获 得树突状细胞（DCs）,免疫磁珠分选纯化获得CD11c+树突状细胞,经不同浓度透明质酸（HA）刺激后,采用酶联免疫吸附法 （ELISA）检测培养上清液中细胞因子IL-12p70 含量。建立小鼠皮下B16 黑色素瘤模型,肿瘤局部皮下回输HA 孵育DC后检测 肿瘤大小,应用ConA 检测脾淋巴细胞增殖情况,应用MTT 法检测脾淋巴细胞杀伤活性,ELISA 法检测脾淋巴细胞分泌的 TNF-alpha和IFN-r的表达,以单纯DC回输、生理盐水注射以及正常小鼠（无瘤）组作为对照。结果：在10～100 ug/mL 范围内,HA 以剂量依赖的方式上调DCs 分泌IL-12p70。HA 孵育DC处理组肿瘤生长明显受到抑制;淋巴细胞增殖反应、杀伤活性和细胞因 子TNF-alpha和IFN-r的表达明显高于单纯DC 组和生理盐水组(P < 0.05)。结论：透明质酸可促进小鼠骨髓DC 的成熟;透明质酸孵 育的DC 通过增强荷瘤小鼠的抗肿瘤免疫功能而抑制肿瘤的生长。     

Toll样受体信号转导对树突状细胞活化的影响

树突状细胞（dendriticcells,DCs）是目前已知功能最强的抗原提呈细胞（antigenpresentingcell,APC）,是介导固有免疫和适应性免疫的桥梁,在机体抗感染、抗肿瘤等方面发挥重要作用。Toll样受体（toll．1ikereceptor,TLRs）是一类重要的模式识别受体（paRemrecognitionreceptors,PRRs）,可识别入侵的病原体相关分子模式（pathogen-associatedmoleculepatterns,PAMPs）,通过招募接头蛋白、活化蛋白激酶和激活转录因子进行信号传导,从而引起效应细胞的活化和促炎因子的释放。不同亚型的DCs分布有不同的TLRs,多种TLRs可识别外来入侵的病原体成分,发挥重要的免疫学作用：诱导DCs分化成熟,摄取递呈抗原,促进DCs分泌多种细胞因子发挥作用。在炎症、病毒感染、自身免疫性疾病和肿瘤等疾病状态下,DCs表面TLRs的表达上调或下调,并且存在功能障碍,可影响DCs的分化成熟,导致其功能低下,这与疾病的发生和发展密切相关。本文综述了TLRs及其信号通路对树突状细胞的活化及功能的影响。     

喉癌组织中血管内皮生长因子、CD1a阳性树突状细胞表达及相关性的研究

目的:观察喉癌病人癌组织内CDla~ 树突状细胞(dendritic cells,DC)的分布、形态学特征以及血管内皮生长因子(vascular endothelial growth factor,VEGF)的表达情况,同时探讨喉癌组织CDla~ DC分布与VEGF表达的关系。方法:采用抗VEGF、抗CDla抗体进行免疫组化染色和透射电镜等方法研究了42例喉癌组织。结果:喉癌组织CDla~ 树突状细胞树突状细胞形态不规则,表面有许多不规则树状突起。大部分散在分布于癌巢内,与肿瘤细胞有密切接触,少量分布于癌巢之间的间质和癌周组织。喉癌组织内CDla~ DC密度与喉癌临床期次呈明显的负相关,而VEGF的表达与喉癌临床期次呈明显的正相关。喉癌组织中VEGF表达明显升高的病例,其CDla~ DC密度显著降低。结论:癌巢内树突状细胞为不成熟状态的DC,与肿瘤细胞密切接触而捕获肿瘤抗原。喉癌组织中VEGF表达与DC含量呈负相关。     

应用Toll样受体激动剂促进DC成熟的研究

树突状细胞(dendritic cell,DC)是目前被广泛认可的抗原提呈功能最强的专职抗原提呈细胞(antigen presenting cell,APC),成熟DC具有很强的诱导初始T细胞活化、激活免疫应答的功能,是固有免疫中巨噬细胞和适应性免疫中B细胞功能的100~1 000倍。树突状细胞–细胞因子诱导的杀伤细胞(dendritic cells-cytokine induced killer cell,DC-CIK)联合放化疗治疗多种恶性肿瘤,对抑制肿瘤进展和转移、降低肿瘤负荷、提高患者生活质量及延长患者生存时间都有一定的意义,但目前临床应用的DC其成熟度与疗效所需的成熟度仍有差距,这可能是限制DC-CIK疗效的原因之一。该研究将贴壁法获得的DC用多聚次黄嘌呤胞嘧啶核苷酸[polyinosinic-polycytidylic acid,Poly(I?C)]和传统刺激DC成熟的物质肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)刺激DC成熟,第8 d用流式细胞术检测成熟DC的表型,发现与TNF-α相比,Poly(I?C)能够更有效地促进DC成熟。同时,该研究还比较了Poly(I?C)协同腺病毒对DC成熟的影响,通过流式细胞术或ELISA检测成熟DC的表型CD80、CD83、CD86、人类白细胞抗原-DR(human leukocyte antigen DR,HLA-DR)以及白介素-12(interleukin-12,IL-12)的分泌,发现腺病毒并不能协同Poly(I?C)刺激DC的成熟。最后,探讨了不同成熟度的DC对初始T淋巴细胞活化程度的影响。结果表明,成熟度较高的DC可更好地诱导初始T淋巴细胞的活化,并且大量分泌TNF-α和γ干扰素(inteferon-γ,IFN-γ)。     

Interactions of tumor cells with dendritic cells: balancing immunity and tolerance

Dendritic cells (DCs) are antigen-presenting cells specialized to initiate and maintain immunity and tolerance. DCs initiate immune responses in a manner that depends on signals they receive from pathogens, surrounding cells and their products. Most tumors are infiltrated by DCs. Thus, interactions between DCs and dying tumor cells may determine the balance between immunity and tolerance to tumor cells. In addition, DCs also display non-immunologic effects on tumors and the tumor microenvironment. Therefore, improved understanding of the cross talk between tumor cells and DCs may suggest new approaches to improve cancer therapy.     

Differential effects of dengue virus on infected and bystander dendritic cells

Dendritic cells (DCs) play a central role as major targets of dengue virus (DV) infections and initiators of antiviral immune responses. Previous observations showed that DCs are activated by infection, presumably acquiring the capacity to promote cell-mediated immunity. However, separate evaluations of the maturation profiles of infected and uninfected bystander cells show that infection impairs the ability of DCs to upregulate cell surface expression of costimulatory, maturation, and major histocompatibility complex molecules, resulting in reduced T-cell stimulatory capacity. Infected DCs failed to respond to tumor necrosis factor alpha as an additional maturation stimulus and were apoptotic. Interleukin 10 (IL-10) was detected in supernatants from cultures of DV-infected DCs and cocultures of DCs and T cells. Taken together, these results constitute an immune evasion strategy used by DV that directly impairs antigen-presenting cell function by maturation blockade and induction of apoptosis.     

Tracking the 'general': tagging skin-derived dendritic cells

Dendritic cells (DCs) are the sentinels of the immune system; their migration, maturation and mobilization are fundamental to immunity and tolerance. The recent tracking of DCs from the skin to lymph node (LN) and their enumeration using a Cre/loxP system demonstrate the recruitment of a higher than expected number of DCs to the draining LN after cutaneous administration of DNA-coated gold particles. The longevity of the migrated DCs was also longer than previously reported.     

Tolerogenic dendritic cells and the quest for transplant tolerance

In recent years, there has been a shift from the perception of dendritic cells (DCs) solely as inducers of immune reactivity to the view that these cells are crucial regulators of immunity, which includes their ability to induce and maintain tolerance. Advances in our understanding of the phenotypical and functional plasticity of DCs, and in our ability to manipulate their development and maturation in vitro and in vivo, has provided a basis for the therapeutic harnessing of their inherent tolerogenicity. In this Review, we integrate the available information on the role of DCs in the induction of tolerance, with a focus on transplantation.     

Purified Dendritic Cell-Tumor Fusion Hybrids Supplemented with Non-Adherent Dendritic Cells Fraction Are Superior Activators of Antitumor Immunity

Background

Strong evidence supports the DC-tumor fusion hybrid vaccination strategy, but the best fusion product components to use remains controversial. Fusion products contain DC-tumor fusion hybrids, unfused DCs and unfused tumor cells. Various fractions have been used in previous studies, including purified hybrids, the adherent cell fraction or the whole fusion mixture. The extent to which the hybrids themselves or other components are responsible for antitumor immunity or which components should be used to maximize the antitumor immunity remains unknown.

Methods

Patient-derived breast tumor cells and DCs were electro-fused and purified. The antitumor immune responses induced by the purified hybrids and the other components were compared.

Results

Except for DC-tumor hybrids, the non-adherent cell fraction containing mainly unfused DCs also contributed a lot in antitumor immunity. Purified hybrids supplemented with the non-adherent cell population elicited the most powerful antitumor immune response. After irradiation and electro-fusion, tumor cells underwent necrosis, and the unfused DCs phagocytosed the necrotic tumor cells or tumor debris, which resulted in significant DC maturation. This may be the immunogenicity mechanism of the non-adherent unfused DCs fraction.

Conclusions

The non-adherent cell fraction (containing mainly unfused DCs) from total DC/tumor fusion products had enhanced immunogenicity that resulted from apoptotic/necrotic tumor cell phagocytosis and increased DC maturation. Purified fusion hybrids supplemented with the non-adherent cell population enhanced the antitumor immune responses, avoiding unnecessary use of the tumor cell fraction, which has many drawbacks. Purified hybrids supplemented with the non-adherent cell fraction may represent a better approach to the DC-tumor fusion hybrid vaccination strategy.     

Skewing effect of sulprostone on dendritic cell maturation compared with dinoprostone

Background

Dendritic cells (DCs) are the most efficient antigen-presenting cells and act at the center of the immune system owing to their ability to control both immune tolerance and immunity. In cancer immunotherapy, DCs play a key role in the regulation of the immune response against tumors and can be generated ex vivo with different cytokine cocktails. Methods. We evaluated the feasibility of dinoprostone (PGE₂) replacement with the molecular analog sulprostone, in our good manufacturing practice (GMP) protocol for the generation of DC-based cancer vaccine. We characterized the phenotype and the function of DCs matured in the presence of sulprostone as a potential substitute of dinoprostone in the pro-inflammatory maturation cocktail consisting of tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β) and IL-6. Results. We found that sulprostone invariably reduces the recovery, but does not significantly modify the viability and the purity of DCs. The presence of sulprostone in the maturation cocktail increases the adhesion of single cells and of clusters of DCs to the flask, making them more similar to their immature counterpart in terms of adhesion and spreading proprieties. Moreover, we observed that sulprostone impairs the expression of co-stimulatory molecules and the spontaneous as well as the directed migration capacity of DCs.

IL-10-conditioned dendritic cells, decommissioned for recruitment of adaptive immunity, elicit innate inflammatory gene products in response to danger signals

Dendritic cells (DCs) are the professional APCs of the immune system, enabling T cells to perceive and respond appropriately to potentially dangerous microbes, while also being able to maintain T cell tolerance toward self. In part, such tolerance can be determined by IL-10 released from certain types of regulatory T cells. IL-10 has previously been shown to render DCs unable to activate T cells and it has been assumed that this process represents a general block in maturation. Using serial analysis of gene expression, we show that IL-10 pretreatment of murine bone marrow-derived DCs alone causes significant changes in gene expression. Furthermore, these cells retain the ability to respond to Toll-like receptor agonists, but in a manner skewed toward the selective induction of mediators known to enhance local inflammation and innate immunity, among which we highlight a novel CXCR2 ligand, DC inflammatory protein-1. These data suggest that, while the presence of a protolerogenic and purportedly anti-inflammatory agent such as IL-10 precludes DCs from acquiring their potential as initiators of adaptive immunity, their ability to act as initiators of innate immunity in response to Toll-like receptor signaling is enhanced.