The role of cytotoxic CD161-expressing CD4+ T-cells in host defense during chronic inflammatory diseases of the gut.

这项拟议项目的目的是阐明肠道中表达CD161的CD4+T细胞是否有助于宿主抵御细菌感染，以及这些细胞与导致或维持炎症性肠病(IBD)的病理之间是否存在联系。为此，在最初的一系列实验中，计划对这些细胞的TCR谱系、转录程序和组织内的定位进行详细的表征。初步实验已经显示，肠道中相当大比例的CD161+CD4+T细胞在激活时表达细胞毒效应分子颗粒酶B。因此，这个项目的核心部分将是分析CD161+CD4+T细胞是否除了颗粒酶B之外还表达其他细胞毒效应分子，如穿孔素，以及它们是否有能力直接杀死受细菌感染的靶细胞。过去，不同小组的科学研究将肠道细菌与IBD联系起来。例如，研究表明，在患有两种主要IBD形式之一的克罗恩病的患者中，细菌DNA存在于该病特有的肉芽肿中，该疾病与具有侵袭性表型的肠道细菌的存在有关。有趣的是，Klenermann教授团队之前的实验显示，与健康对照组相比，从IBD患者分离的CD161+CD4+T细胞表达更高水平的抑制性受体，也显示出颗粒酶B的表达缺陷。为了弄清肠道中的CD161+CD4+T细胞与IBD的发生或维持之间是否存在联系，将测试IBD的严重程度是否与这些细胞的存在和功能相关。为此，计划从不同疾病阶段的患者中分离CD161+CD4+T细胞，并测定它们的数量、抑制性受体的表达和细胞毒能力。

The aim of the proposed project is to elucidate whether the CD161-expressing CD4+ T-cells from the gut can contribute to host defence against bacterial infections and if there is a connection between these cells and the pathology leading to or maintaining inflammatory bowel diseases (IBD). To that end, in an initial set of experiments it is planned to make a detailed characterization of these cells in terms of their TCR repertoire, their transcriptional program and their localization within the tissue.Preliminary experiments already revealed that a notable percentage of the CD161+CD4+ T-cells in the gut expresses the cytotoxic effector molecule Granzyme B upon activation. Hence, a central part is this project will be to analyse whether the CD161+CD4+ T-cells express other cytotoxic effector molecules like Perforin in addition to Granzyme B and whether they have the capacity to kill bacterially infected target cells directly.Scientific studies from different groups have linked gut bacteria to IBD in the past. For instance, it was shown that in patients suffering form Crohn’s disease, one of the two major forms of IBD, bacterial DNA is present in the granulomas characteristic for the disease and that the disease is associated with the presence of gut bacteria with an invasive phenotype. Interestingly, previous experiments from Professor Klenermans group revealed that CD161+CD4+ T-cells isolated from IBD patients expressed higher levels of inhibitory receptors and also displayed a defect in Granzyme B expression compared to healthy controls. In order to unravel if there is a connection between the CD161+CD4+ T-cells in the gut and the development or maintenance of IBD, it will be tested whether the severity of IBD correlated with the presence and functionality of these cells. To that end it is planned to isolate the CD161+CD4+ T-cells from patients in different stages of disease and determine their numbers, expression of inhibitory receptors and cytotoxic capacities.