Immune checkpoints and the regulation of tolerogenicity in dendritic cells: Implications for autoimmunity and immunotherapy

The immune system is responsible for defending the host from a large variety of potential pathogens, while simultaneously avoiding immune reactivity towards self-components. Self-tolerance has to be tightly maintained throughout several central and peripheral processes; immune checkpoints are imperative for regulating the immunity/tolerance balance. Dendritic cells (DCs) are specialized cells that capture antigens, and either activate or inhibit antigen-specific T cells. Therefore, they play a key role at inducing and maintaining immune tolerance. DCs that suppress the immune response have been called tolerogenic dendritic cells (tolDCs). Given their potential as a therapy to prevent transplant rejection and autoimmune damage, several strategies are under development to generate tolDCs, in order to avoid activation and expansion of self-reactive T cells. In this article, we summarize the current knowledge relative to the main features of tolDCs, their mechanisms of action and their therapeutic use for autoimmune diseases. Based on the literature reviewed, autologous antigen-specific tolDCs might constitute a promising strategy to suppress autoreactive T cells and reduce detrimental inflammatory processes.     

Wnt信号分子在大鼠中枢神经系统的表达及其共存

目的:通过研究Wnt信号分子在大鼠中枢神经系统(CNS)的表达及分布,以探讨Wnt信号分子在CNS早期发育的可能调控机制,以及Wnt信号分子之间的功能联系.方法:应用免疫组织化学及双标记技术,观察了Wnt信号分子β-catenin、糖原合成酶激酶3β(Gsk-3β)、大肠腺瘤样息肉基因(APC)等关键调控分子在成年大鼠CNS的表达分布、细胞定位及共存关系.结果:免疫组织化学显色显示Gsk-3β阳性细胞多为具有突起的神经元样细胞,其主要分布区域包括新皮层、背内侧丘脑、海马、小脑浦肯野细胞及脑干多个核团.β-catenin与APC在分布模式上与Gsk-3β高度一致.双标记实验显示β-catenin与APC除神经元外,在部分星形胶质细胞也存在表达,而Gsk-3β则主要显示神经元定位.部分β-catenin阳性细胞,特别是室下层及海马区阳性细胞还呈现与神经前体细胞标记物巢蛋白的共存.结论:Wnt信号分子在CNS存在着密切相关的功能联系,同时在不同细胞及组织区域可能还具有其特有的生物效应,与神经前体细胞和神经胶质细胞增殖分化密切相关,对其相关信号机制有待深入研究.     

以PCR-RFLP分析检测髓系白血病人APC基因的杂合性缺失

采用PCR-RFLP分析检测了APC抑癌基因在7例MDS,36例ANLL和15例正常人对照中的杂合性缺失(loss of heterozygosity,LOH),并讨论其与髓系表型特异性、临床表现以及预后的相关性。PCR-RFLP的分析结果发现,在58例标本中有35例(60.3％)为杂合子个体,能提供缺失信息,其中包括9例正常人,22例ANLL和4例MDS。正常组未见1例发生LOH(0/9),MDS组1例RAEB阳性(1/4),而ANLL中LOH阳性的有4例(4/22),其中3例为M_(2a)(3/6),1例为M_(4a)(1/1)。统计学证实M_(2a)的阳性率与正常组有显著性差异(P=0.044)。LOH阳性及阴性AML病人的临床资料比较,前者的共同点有:①中老年人偏多;②外周血WBC数较高,但浸润现象不明显;③对化疗较敏感。结论是APC基因的异常可能是发生于髓系恶性疾病中粒系异常克隆的一个独立分子事件,代表着一部分具有特殊临床表现及预后的病人群体。     

巢式MS-PCR法检测恶性血液病细胞株APC基因启动子甲基化状态

本研究旨在应用巢式甲基化特异性PCR（nMS—PCR）法检测10种恶性血液系统肿瘤细胞株APC基因启动子的甲基化状态,并探究其在肿瘤发生发展中的作用,同时筛选出APC基因启动子高甲基化的肿瘤细胞株,将其作为研究基因甲基化与表达关系的细胞模型。采用nMS—PCR扩增亚硫酸盐修饰后的10种肿瘤细胞株基因组DNA,检测其APC基因启动予区CpG岛的甲基化状态。结果表明,CA46、U266、Molt4、K562、HL-60、CEM、AKR、U937、Raji细胞的APC基因启动子区均未甲基化,而Jurkat细胞的APC基因启动子区出现甲基化。结论：用nMS—PCR可以准确地检测出恶性血液病细胞株APC基因的甲基化状态,该方法操作简便,可用于检测各种肿瘤细胞基因的甲基化状态。     

粪便中p53与APC突变检测在大肠癌诊断中的意义

目的探讨在大肠癌患者粪便中检测p53、APC基因突变的可行性及其应用前景和意义。方法从36例大肠癌患者、10例大肠腺瘤患者以及30例正常对照者的粪便中分别提取DNA,应用PCR-SSCP法检测粪便中p53、APC基因突变情况。结果36例大肠癌患者粪便中p53及/或APC基因突变检出率为77.78%(19/36),二者突变率分别为52.78%(19/36)和36.11%(13/36);10例大肠腺瘤中p53基因突变检出率为0%,APC为20%;30例正常对照粪便中p53、APC基因突变检出率均为0%。p53的突变随大肠癌分化程度的降低而增高(P<0.05);APC基因突变与大肠癌组织学类型无关(P>0.05)。结论联合检测粪便中p53与APC突变在大肠癌诊断和筛查中有潜在的应用价值。     

散发性结直肠癌APC、K-ras、p53、MMR基因突变检测

目的探讨结直肠癌中APC、K-ras、p53、MMR基因突变模式。方法应用酚/氯仿法提取48例结直肠癌组织及其相应正常黏膜组织的DNA,用聚合酶链反应（PCR）、单链构象多态性分析（SSCP）和DNA测序等方法检测APC基因第l5外显子突变密集区（mutation cluster region,MCR）区段、K-ras、p53和MMR基因的突变。结果hMLH1未发生突变,APC、K-ras、p53基因和hMSH2的突变率分别为37.5%（18/48）、43.8%（21/48）、35.4%（17/48）和4.2%（2/48）。APC、K-ras、p53或hMSH2基因突变率高达91.7%（44/48）。APC、K-ras,p53基因均发生突变的发生率为4.2%（2/48）。结论结直肠癌的发生、发展并不完全遵循由正常结直肠黏膜上皮细胞向腺瘤和侵袭性癌转化的过程,可能存在其他结直肠癌发病机制。     

Establishment of shared antigen reactive cytotoxic T lymphocyte using co-stimulatory molecule introduced autologous cancer cells

Cytotoxic T lymphocytes (CTLs) play an essential role in immunological responses for tumor rejection. In the past decade, many tumor-associated antigens (TAAs) have been identified predominantly in melanomas. Several clinical trials based on such antigenic peptides with or without adjuvants brought about partially favorable results, suggesting that identification of more immunogenic TAAs is needed. We show here the successful establishment of human leukocyte antigen (HLA)-A24-restricted CTL (TcLHK2 line1) from a pleural effusion of lung cancer patient, using B7.1 (CD80) transduced autologous lung cancer cells as an antigen-presenting cell (APC). TcLHK2 line1 recognized autologous lung adenocarcinoma cell line LHK2 in an HLA-A24-restricted fashion. Moreover, this CTL line also recognized allogeneic HLA-A24-positive lung adenocarcinoma cell line, gastric carcinoma cell line and melanoma cell line. These data raise the possibility that co-stimulatory molecule B7.1 (CD80) plays important role to overcome the immunological tolerance. Furthermore, TcLHK2 line1 is a useful tool for the identification of widely expressed shared antigens restricted by HLA-A24. Further analysis of this CTL and autologous cancer cell line will bring about novel TAAs.     

Endoscopic diagnosis and treatment of inlet patch: Justification,techniques, and results

Esophageal gastric inlet patches (EGIPs) comprise an island of heterotopic gastric columnar epithelium in the cervical esophagus with a reported prevalence of up to 10%. Usually the diagnosis is made by chance in the course of an upper gastrointestinal endoscopy. After histopathologic examination EGIPs can be classified as oxyntic (mucosal glands contain parietal cells), mucoid type (mucosa is composed solely of glands with mucous cells), or mixed type (presence of both: glands with parietal cells and glands of mucous cells). Despite their overall low incidence of clinically relevant conditions, EGIPs seem to be a significant entity. Few individuals with EGIPs report symptoms of globus sensations, dysphagia, hoarseness, or chronic cough that are often misinterpreted as an atypical manifestation of gastroesophageal reflux disease. It is known that these symptoms significantly compromise the patients' quality of life. Therefore, therapy should be initiated. However, proton pump inhibitors' response seems to be poor in these patients. We were able to show that an interventional ablative endoscopic therapy by argon plasma coagulation can be a safe and effective procedure. However, further researches are required to better understand the clinical significance of EGIPs and their association to symptoms.     

Wnt通路成员APC、β-catenin、c-myc及黏附分子E-cadherin与大肠癌的关系

大肠癌是我国十分常见的恶性肿瘤,其发病率占全部胃肠肿瘤的第一至第二位。随着我国人民生活水平的提高及生活方式、饮食、环境因素的变化,我国大肠癌的发病率已呈明显上升的趋势。大肠癌的发生、发展机理至今尚未十分清楚,“正常结直肠上皮—畸变性腺窝灶—腺瘤性息肉—腺瘤恶变—侵袭性癌”病理转变是一个多阶段、多基因参与的过程,涉及到癌基因的激活和抑癌基因的失活。近年来,分子生物学研究发现,Wnt通路中各癌基因、抑癌基因及细胞黏附分子异常与大肠癌的发生、发展密切相关。一、Wnt通路、黏附分子的组成及与肿瘤的关系Wnt基因编码…