Modulation of intestinal inflammation in colitis by manipulating dendritic cells

描述(申请人提供)：炎症性肠病(IBD)是一种慢性复发性炎症状态，其发病因素包括患者的遗传背景、肠道共生或致病菌的影响，以及先天和适应性免疫反应的异常激活。树突状细胞(DC)似乎在调节先天免疫反应和获得性免疫反应中发挥作用。来自肠板的DC使用模式识别受体识别细菌成分并对其做出反应，如Toll样受体(TLRs)。TLR检测到一系列不同的保守微生物成分，因此，它们可以共同检测到大多数微生物。TLRs被微生物的特定成分激活，如：FMLP、内毒素、PG-PS、脂磷脂酸和某些宿主分子。一旦树突状细胞上的TLRs识别细菌成分，树突状细胞就充当抗原提呈细胞(APC)，这是T细胞激活的关键介质。已有研究表明，炎症性肠病(IBD)中T细胞对凋亡的抵抗导致T细胞的不适当积聚和慢性粘膜炎症的持续存在。FasL和肿瘤坏死因子相关的凋亡诱导配体(TRAIL)属于肿瘤坏死因子超家族的一个亚群，它通过与含有死亡结构域的受体结合来诱导细胞凋亡。凋亡诱导配体如FasL和TRAIL被发现在细胞调控中发挥重要作用。FasL是一种II型跨膜蛋白，属于肿瘤坏死因子家族，表达于活化的脾细胞和胸腺细胞，与其参与T细胞介导的反应一致。最近的研究表明，TRAIL还可以诱导多种组织细胞和白细胞的凋亡。这一建议的中心假设是，通过树突状细胞上FASL和TRAIL的表达，诱导活化的CD4T细胞凋亡，将对慢性IBD期间发生的特征性炎症具有治疗作用。本研究的具体目的是：1)体外检测T细胞与DC的相互作用；2)体外检测FASL和TRAIL的表达对DC活性CD4T细胞凋亡的影响；3)确定结肠炎时DCs中FASL和TRAIL的表达对活性CD4T细胞凋亡的影响。这些研究将有助于我们了解结肠炎发生的免疫机制，以及未来使用体外产生的DC作为恢复肠道免疫的治疗工具的可能性。

DESCRIPTION (provided by applicant): Inflammatory bowel diseases (IBD) are chronic relapsing inflammatory conditions; the factors involved in their pathogenesis include the genetic background of patients, the effect of commensal or pathogenic bacteria in the gut, and abnormal activation of innate and adaptive immune responses. Dendritic cells (DCs) appear to play a role in modulating both the innate and adaptive immune response. DCs from the lamina propia of the intestines recognize and respond to bacterial components using pattern recognition receptors, such as Toll-like receptors (TLRs). TLRs sense a distinct repertoire of conserved microbial components, so that collectively, they can detect most microbes. TLRs are activated by specific components of microbes, such as: FMLP, LPS, PG-PS, lipoteicoic acid and certain host molecules. Once TLRs on DCs recognize bacterial components, DCs act as antigen presenting cells (APC), which are critical mediators of T cell activation. Previous studies have shown that T-cell resistance against apoptosis contributes to inappropriate T-cell accumulation and the perpetuation of chronic mucosal inflammation in inflammatory bowel diseases (IBDs). FasL and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) belong to a subgroup of the TNF superfamily which induces apoptosis by binding to their death domain containing receptors. Apoptosis-inducing ligands such as FasL and TRAIL have been found to play an important role in cell regulation. FasL is a type II transmembrane protein that belongs to the tumor necrosis factor family and is expressed in activated splenocytes and thymocytes, consistent with its involvement in T-cell-mediated responses. Recent data indicate that TRAIL may also induce apoptosis in various tissue cells and leukocytes. The central hypothesis of this proposal is that inducing the apoptosis of active CD4 T cells, mediated by the expression of FASL and TRAIL on DCs, will have a therapeutic effect against the characteristic inflammation that occurs during chronic IBD. The specific aims of this proposal are to1) examine in vitro the interaction of T cells with DCs as an APC 2) to examine in vitro the effect of the apoptosis of active CD4 T-cells mediated by the expression of FASL and TRAIL on DCs 3) determine the effect of the apoptosis of active CD4 T-cells mediated by the expression of FASL and TRAIL in DCs during colitis. These studies will contribute to our understanding of the immune mechanisms that occur in colitis and to the possibility of using ex vivo-generated DCs as therapeutic tools for restoring intestinal immunity in the future.