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

该项目的目的是阐明来自肠道的表达CD161的CD4+ T细胞是否有助于宿主防御细菌感染，以及这些细胞与导致或维持炎症性肠病（IBD）的病理学之间是否存在联系。为此，在最初的一组实验中，计划对这些细胞的TCR库、转录程序和在组织中的定位进行详细的表征。初步实验已经揭示，肠道中相当大比例的CD 161 + CD 4 + T细胞在活化后表达细胞毒性效应分子颗粒酶B。因此，该项目的核心部分是分析除了颗粒酶B之外，CD161+CD4+ T细胞是否表达其他细胞毒性效应分子，如穿孔素，以及它们是否具有直接杀死细菌感染的靶细胞的能力。过去，不同小组的科学研究将肠道细菌与IBD联系起来。例如，已经表明，在患有克罗恩病（IBD的两种主要形式之一）的患者中，细菌DNA存在于该疾病特有的肉芽肿中，并且该疾病与具有侵袭性表型的肠道细菌的存在相关。有趣的是，Klenermans教授小组先前的实验显示，与健康对照相比，从IBD患者中分离的CD 161 + CD 4 + T细胞表达更高水平的抑制性受体，并且还显示出颗粒酶B表达的缺陷。为了阐明肠道中的CD161+CD4+ T细胞与IBD的发展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CD 161 + CD 4 + T细胞，并确定其数量、抑制性受体的表达和细胞毒性能力。

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.