Role of STAT3 in the pathogenesis of Inflammatory Bowel Disease

描述(申请人提供)：炎症性肠病(IBD)是一种特发性结肠和小肠疾病。IBD的主要类型是克罗恩病(CD)和溃疡性结肠炎(UC)。据估计，美国有140万人患有IBD。IBD会导致严重的腹泻、腹痛，并增加患结直肠癌的风险。重要的是，目前还没有治愈IBD的方法。信号转导和转录激活因子(Stat)3已被证明在IBD小鼠模型中起致病作用。IBD患者体内激活的STAT3水平升高与肠道炎症程度直接相关。STAT3有两种亚型(？/p92和？/p83)。只表达STAT3的小鼠对细菌内毒素的攻击具有高反应性，并且对失血性休克诱导的心、肺和肝脏中的实质细胞的凋亡具有抵抗力，这表明STAT3可以减弱由STAT3介导的炎症和抗凋亡反应。我们之前开发了一种有效的小分子STAT3抑制剂(C188-9)，它对STAT3与STAT3具有选择性。在初步研究中，我们证明C188-9几乎完全预防葡聚糖硫酸钠(DSS)诱导的小鼠结肠炎。在目前的方案中，我们将使用C188-9和转基因STAT3？小鼠来询问STAT3？在IBD发病机制中的作用这一假说，并建立通过选择性药物靶向STAT3？治疗IBD的原则证明。我们制定了两个密切关注的目标来检验这一假设。具体目标1：确定C188-9能否治疗IBD，C188-9是一种选择性靶向STAT3的STAT3小分子抑制剂。我们将确定C188-9在由DSS(模拟UC)诱导的慢性IBD-IBD和由2，4，6-三硝基苯磺酸(TNBS)(模拟CD)诱导的IBD两种临床前模型中是否有益。检查的终点包括死亡率、体重减轻、直肠出血、大便稠度、结肠长度和便秘程度。 结肠炎(由组织病理学检查确定)。我们还将研究C188-9抑制IBD发病的机制是否通过减少免疫细胞产生的促炎细胞因子和趋化因子和/或通过增加致病的CD4+T细胞的凋亡来实现。特异性目的2：探讨STAT3在IBD发病机制中的作用。我们将在DSS和TNBS诱导的结肠炎中对转基因STAT3基因缺陷小鼠和它们的小鼠WT对照进行比较，比较疾病表现的严重性、细胞因子和趋化因子水平以及T细胞凋亡，如目标1所述。这一建议将支持这样的假设，即STAT3，特别是STAT3，参与IBD的发病机制，并且以STAT3为靶点，使用对STAT3具有选择性的小分子抑制剂是治疗IBD的一种新的有效的方法。

DESCRIPTION (provided by applicant): Inflammatory bowel disease (IBD) is an idiopathic disease of the colon and small intestine. The major types of IBD are Crohn's disease (CD) and ulcerative colitis (UC). An estimated 1.4 million persons in the United States suffer from IBD. IBD causes severe diarrhea, abdominal pain and increases the risk of colorectal cancer. Importantly, there is no cure for IBD. Signal transducer and activator of transcription (Stat) 3 ha been shown to play a pathogenic role in mice models of IBD. Increased levels of activated Stat3 directly correlated with the degree of intestinal inflammation in humans with IBD. There are two isoforms of Stat3 (¿/p92 and ¿/p83). Mice expressing only Stat3¿ are hyper-responsive to bacterial LPS challenge and are resistant to hemorrhagic shock-induced apoptosis of parenchymal cells within the heart, lung, and liver suggesting that Stat3¿ attenuates inflammatory and anti-apoptotic responses mediated by Stat3¿. We previously developed a potent, small-molecule Stat3 inhibitor (C188-9) that is selective for Stat3¿ vs. Stat3¿. In preliminary studies, we demonstrated that C188-9 almost completely prevents dextran sodium sulphate (DSS)-induced colitis in mice. In the current proposal, we will use C188-9 and transgenic Stat3¿ mice to interrogate the hypothesis that Stat3¿ contributes to the pathogenesis of IBD and to establish proof-of-principle that IBD can be treated using selective pharmacological targeting of Stat3¿. We have formulated 2 tightly focused aims to examine this hypothesis. Specific aim 1: To determine if IBD can be treated with C188-9, a small-molecule inhibitor of Stat3 that selectively targets Stat3¿. We will determine if C188-9 is of benefit in 2 preclinical models of chronic IBD-IBD induced by DSS, which mimics UC, and IBD induced by 2, 4, 6-trinitrobenzene sulfonic acid (TNBS), which mimics CD. Endpoints that will be examined include mortality rate, weight loss, rectal bleeding, stool consistency, colon length and extent of colonic inflammation (as determined by histopathological assessment). We will also examine if the mechanism by which C188-9 inhibits the pathogenesis of IBD is through decreasing the production of proinflammatory cytokines and chemokines by immunocytes and/or through increased apoptosis of pathogenic CD4+T-cells. Specific aim 2: To determine the contribution of Stat3¿ to the pathogenesis of IBD. We will subject transgenic Stat3¿ knock-in/Stat¿-deficient mice and their littermate WT controls to DSS- and TNBS-induced colitis and compare the severity of disease manifestations, levels of cytokines and chemokines and T-cell apoptosis as outlined in Aim 1. This proposal will provide support for the hypothesis that Stat3, particularly Stat3¿, contributes to the pathogenesis of IBD and that targeting Stat3 with a small molecule inhibitor that is selective for Stat3¿ is a novel and effective approach to IBD treatment.