The role of tumor progression locus 2 (TPL2) in the pathogenesis of Clostridium difficile infection (CDI)

项目摘要/摘要 艰难梭菌感染(CDI)是医疗机构感染性腹泻的最常见原因，约有 根据美国疾病控制与预防中心2015年的报告，美国每年有453.000例病例和29,000人死亡。严重的CDI的持续上升已经 由于超强毒力菌株的出现，世界各地都观察到了这种病毒。CDI的症状从腹泻到 肠道炎症/损伤和死亡。症状主要由两种外毒素TcdA和TcdB引起， 哪些糖基化Rho GTP酶，包括RhoA，rac1和CDc42，导致细胞内 细胞骨架和紧密连接。这两种毒素共享相似的结构域结构，包括N-末端 葡萄糖转移酶结构域(GT)，自催化半胱氨酸蛋白酶结构域(CPD)，易位 结构域(TMD)和C末端受体结合域(RBD)。只有GT在以下情况下释放到胞浆中 它的CPD能自动分解毒素。CDI的病程以最初的肠道炎症为特征 随后发生全身炎症反应的过程。然而，TcdA/TcdB诱导的机制 这种疾病的标志是一种强有力的炎症反应，目前尚不清楚。 我们的长期目标是了解艰难梭菌毒素和 利用这些知识设计更好的干预措施，以降低CDI的发生率和严重性。 本研究旨在阐明Tpl2在CDI发病机制中的作用。我们假设 TPL2消融将下调TcdA/TcdB诱导的MAPK激活，导致肿瘤坏死因子-α/IL-6降低 生产，从而减少毒素引起的肠道炎症、组织损伤和死亡率。 为了验证我们的假设，我们将追求两个具体目标。在目标1中，我们将评估Tpl2在 用小鼠模型研究CDI的发病机制。在目标2中，我们将研究Tpl2在信号转导中的作用 TcdA/TcdB诱导骨髓巨噬细胞产生肿瘤坏死因子-α和白介素6的途径

Project Summary/Abstract C. difficile infection (CDI) is the most common cause of infectious diarrhea in healthcare settings with about 453.000 cases and 29,000 deaths yearly in US per CDC report in 2015. A continual rise in severe CDI has been observed worldwide due to the emergence of hypervirulent strains. CDI symptoms range from diarrhea to intestinal inflammation/lesion and death. Symptoms are mainly caused by two exotoxins TcdA and TcdB, which glucosylate Rho GTPases, including RhoA, Rac1 and CDC42 within cells, leading to disruption of cytoskeleton and tight junctions. Both toxins share similar domain structures, including the N-terminal glucosyltransferase domain (GT), the autocatalytic cysteine proteinase domain (CPD), the translocation domain (TMD), and the C-terminal receptor binding domain (RBD). Only the GT is released into cytosol after auto-cleavage of the toxin by its CPD. The course of CDI is characterized by an initial intestinal inflammatory process followed by a systemic inflammatory response. However, the mechanism by which TcdA/TcdB induce a potent inflammatory response, the hallmark of the disease, is unclear. Our long-term goal is to understand the mechanisms mediating intestinal inflammation by C. difficile toxins and to utilize this knowledge for designing better interventions to reduce the incidence and severity of CDI. The objective of this study is to elucidate the role of TPL2 in the pathogenesis of CDI. We hypothesize that TPL2 ablation will down regulate TcdA/TcdB-induced activation of MAPK, leading to reduced TNF-α / IL-6 production, thus reducing toxin-caused intestinal inflammation, tissue injury and mortality. To test our hypothesis, two specific aims will be pursued. In aim 1, we will evaluate the role of TPL2 in the pathogenesis of CDI using mouse models. In aim 2, we will investigate the role of TPL2 in the signaling pathway mediating TcdA/TcdB-induced production of TNF-α and IL-6 by bone marrow-derived macrophages.