The role of Axin2+ stem cells in ulcer healing during colitis.

Axin2 干细胞在结肠炎溃疡愈合中的作用。

• 批准号: 9138122
• 负责人: Terrence A. Barrett
• 金额: --
• 依托单位: VA MEDICAL CENTER - LEXINGTON, KY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-10-01 至 2020-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9138122
• 关键词: AXIN2 gene; Area; Biochemical; Cell Proliferation; Cells; Clinical Markers; Colitis; Colon; Colon Carcinoma; Data; Disease; Elements; Epithelial; Epithelial Cells; Event; Excision; Exhibits; Failure; Flare; Gene Expression; Gene Targeting; General Population; Generations; Goals; Granulation Tissue; Hospitalization; Human; Impairment; In Vitro; Incidence; Inflammatory Bowel Diseases; Intestines; Island; Lasers; Mediating; Medical; Messenger RNA; Microscopy; Molecular; Molecular Profiling; Mucous Membrane; Mus; Natural regeneration; Operative Surgical Procedures; Oral; Patients; Play; Population; Prevalence; Recovery; Refractory; Reporter; Risk; Role; Signal Transduction; Stem cells; Steroid therapy; Steroids; Structure; Surface; Symptoms; Ulcer; Ulcerative Colitis; Veterans; WNT Signaling Pathway; Work; beta catenin; cell type; clinical remission; design; disability; healing; improved; insight; monolayer; mouse model; novel; prevent; prospective; public health relevance; repaired; self-renewal; stem cell population; therapeutic target

 DESCRIPTION (provided by applicant): A major cause of colon removal surgery in veterans with inflammatory bowel disease (IBD) is a failure of medically-induced mucosal healing. Mucosal healing is a reliable clinical marker of recovery after IBD therapy as it is associated with durable clinical remission. Despite the importance of mucosal repair, we continue to have a poor understanding of many of the cellular and molecular elements that mediate ulcer healing. The current proposal focuses on the role of colonic (epithelial) stem cells (CSC) in ulcer healing during colitis. Wnt/β-catenin signaling in stem cells promotes cell proliferation as well as self-renewal, both essential functions needed for ulcer healing and restitution of the mucosal barrier. A central tenant of this proposal is the hypothesis that Wnt/β-catenin signaling plays an integral role in mucosal repair in IBD and that steroids delay ulcer healing my impairing Wnt/β-catenin signaling. In mucosal ulceration, as seen in IBD, there is replacement of surface mucosa with granulation tissue that is re-epithelialized with new crypt structures. We suspect that active Wnt signaling is required for several steps through this sequence of events from stage 1) generation of an intestinal epithelial cell (IEC) monolayer, to stage 2) formation of epithelial invaginations, to stage 3) formation of crypt islands on ulcer surfaces and finally stage 4) regeneration of mature crypts (Fig 3). Biochemical data from our lab indicate Wnt/β-catenin signaling is increased during ulcer healing in colitis in mice and IBD patients. In studies to interrogate the role of Wnt signaling in ulcer healing, we discovered that IEC expressing mRNA for the Wnt target gene Axin2 expand in ulcer margins, on ulcer surfaces, and within newly-formed crypt structures in the middle of ulcers. Studies using a novel Axin2 reporter mouse model indicate that Axin2+ IEC are pluripotent and capable of growing colonoid structures in vitro from a single cell. Together the preliminary data suggest that Axin2+ IEC represent a novel ISC population that forms new crypt structures during ulcer healing. In Aim 1, Axin2lacZ/+ and Axin2 CreERT2/+; R26RmTmG/+ mice will be used to study ulcer-associated Axin2+ IEC localization and gene expression profiles of this new stem cell population, as well as perform lineage tracing during ulcer healing in DSS colitis. In Aim 2 we will examine ulcer healing in mice treated with steroids. New studies will utilize Axin2-specific expression of stabilized β-catenin to examine its role in ulcer healin during steroid therapy. Aim 3 studies will interrogate the role of Axin2+ IEC in human IBD and will analyze the mechanisms by which steroids impair ulcer healing. The goal of these studies will be to determine if untreated UC patients exhibit increased Axin2 expression, Wnt signaling and stem cell gene expression in areas of ulcer healing (Aim 3A) and determine whether steroid therapy reduces levels of Axin2 expression and stem cell activation in areas of delayed ulcer healing in a prospective trial of UC patients treated with steroids for a colitis flare (Aim 3B). Together the studies proposed will provide valuable insights into the molecular mechanisms that govern ulcer healing in colitis. The goal is to determine areas where therapeutic targets can be designed to safely accelerate ulcer healing and reverse the negative impact of steroids on mucosal repair in colitis.

 描述（由申请人提供）： 炎症性肠病（IBD）退伍军人中结肠切除手术的主要原因是医学诱发的粘膜愈合的失败。粘膜愈合是IBD治疗后恢复的可靠临床标志，因为它与持久的临床缓解有关。尽管粘膜修复的重要性很重要，但我们仍然对许多介导溃疡愈合的细胞和分子元素的了解仍然很糟糕。当前的提案着重于结肠（上皮）干细胞（CSC）在结肠炎期间溃疡愈合中的作用。干细胞中的Wnt/β-catenin信号传导促进了细胞的增殖和自我更新，这是溃疡愈合所需的基本功能和粘膜屏障的限制。该提议的核心租户是假设Wnt/β-catenin信号传导在IBD的粘膜修复中起着不可或缺的作用，并且类固醇延迟溃疡治愈我的Wnt/β-catenin信号传导。如IBD所示，粘膜溃疡是用新的隐窝结构重新上皮化的肉芽组织替代表面粘膜。我们怀疑，从第1阶段的事件开始，需要几个步骤进行主动Wnt信号传导，从第1阶段）产生肠上皮细胞（IEC）单层（IEC）单层，再到第2阶段）形成上皮invaginations的形成，再到第3阶段，再到阶段3）在溃疡表面上形成加密岛上的加密岛，并在溃疡表面上的形成，并最终在4）阶段4）成熟的crypters（图3）。来自我们实验室的生化数据表明，在小鼠和IBD患者的结肠炎溃疡愈合过程中，Wnt/β-catenin信号传导增加。在询问Wnt信号在溃疡愈合中的作用的研究中，我们发现IEC表达了Wnt靶基因AXIN2在溃疡边缘，溃疡表面以及溃疡中部新形成的隐窝结构中扩展的IEC。在AIM 1，AXIN2LACZ/+和AXIN2 CREERT2/+中使用新型AXIN2报道器小鼠模型进行研究； R26RMTMG/+小鼠将用于研究这种新的干细胞种群的溃疡相关AXIN2+ IEC定位和基因表达谱，并在DSS结肠炎中进行溃疡愈合期间进行谱系追踪。在AIM 2中，我们将检查用类固醇治疗的小鼠中的溃疡愈合。新的研究将利用稳定的β-catenin的AXIN2特异性表达来检查其在类固醇治疗过程中的作用。 AIM 3研究将询问AXIN2+ IEC在人IBD中的作用，并将分析类固醇损害溃疡愈合的机制。这些研究的目的是确定未经治疗的UC患者在溃疡愈​​合区域中是否表现出增加的AXIN2表达，Wnt信号传导和干细胞基因表达（AIM 3A），并确定立体疗法是否会在UC患者的前瞻性试验中降低延迟溃疡愈合的区域的AXIN2表达水平和干细胞的干细胞激活。控制结肠炎的溃疡愈合的机制。目的是确定可以设计热目标以安全加速溃疡愈合并扭转类固醇对结肠炎粘膜修复的负面影响的区域。