MYOFIBROBLAST REGULATION OF THE STEM CELL NICHE IN SHORT BOWEL SYNDROME

 描述(申请人提供)：克罗恩病、缺血、创伤或放射性肠炎等疾病手术切除后功能性小肠表面积的丧失可能会导致短肠综合征(SBS)，这是美国发病率、死亡率和医疗费用的重要原因。短肠综合征患者经常依赖肠外营养来满足他们的营养需求。肠切除后，剩余的小肠上皮会产生适应性反应，增加绒毛高度、隐窝深度，并增强营养和电解质的吸收。然而，人类的适应性反应是不可预测的，即使对残留小肠长度进行了准确的评估，也可能需要长达两年的时间来确定哪些患者将脱离肠外营养。这种临床变异性的机制基础尚不清楚。我们的应用寻求探索新的再生治疗方法，以增强小肠功能表面积，使用来自PI的大量SBS患者的患者活检。我们的方法将把我们对短肠综合征的临床前模型和干细胞利基中的肌成纤维细胞信号的观察转化为对具有治疗潜力的人类SBS的研究。我们已经证明，肌成纤维细胞蛋白表吗啡(EPIM)调节小鼠的隐窝分裂、肠道上皮细胞增殖和肌成纤维细胞的分泌功能。与Epim-/-肌成纤维细胞共培养进一步促进WT小鼠隐窝的肠样生长和表面积。我们的首要目标是增强增殖性上皮反应和增加小肠表面积，作为SBS的治疗策略。我们的主要假设是，调节肌成纤维细胞Epim及其靶点将促进人类小肠生长，为SBS提供一种新的再生治疗方法。目标1将通过从PI的大量SBS患者队列中建立干细胞/肠样和肌成纤维细胞培养来直接转化我们的小鼠研究。我们将解决与Epim缺陷的肌成纤维细胞共培养增加人类肠样生长的假设。我们将确定体外培养的肠样细胞的生长和增殖能力是否可以预测其适应和脱离肠外营养的能力。目标2将解决两个假设。1.通过改变BMP、HH和Wnt信号通路，Epim基因缺失可调节MF与隐窝上皮细胞的相互作用，从而促进隐窝干细胞的增殖和肠样生长。2.EPIM在调节MF的分泌方面表现出上下文特异性的抑制和促进胞吐的作用。我们的研究意义重大，因为我们将把我们的发现从临床前研究直接转化为人类研究，即EPIM缺失对干细胞利基中MF功能的影响。我们将扩大我们独特的来自SBS患者的小肠隐窝干细胞/肠样培养的临床收集，并为未来可能高通量筛选促进SBS干细胞和隐窝细胞增殖的治疗药物创造一个全国性的资源。Epim和受Epim缺失调控的可溶性因子的分泌是促进肠干/隐窝上皮细胞增殖、导致适应的潜在治疗靶点。。

 DESCRIPTION (provided by applicant): Loss of functional small bowel surface area following surgical resection for disorders including Crohn's disease, ischemia, trauma, or radiation enteritis may result in short bowel syndrome (SBS), an important cause of morbidity, mortality and health care costs in the U.S. SBS patients are frequently dependent on parenteral nutrition to meet their nutritional requirements. Following intestinal resection, the remaining small bowel epithelium mounts an adaptive response that increases villus height, crypt depth and enhances nutrient and electrolyte absorption. However, the adaptive response in humans is unpredictable and it may require up to two years to determine which patients will wean off parenteral nutrition, even with an accurate assessment of remnant small bowel length. The mechanistic basis for this clinical variability is unknown. Our application seeks to explore new regenerative, therapeutic approaches to enhance small bowel functional surface area, using patient biopsies from the PI's large SBS patient population. Our approach will translate observations from our preclinical models of short bowel syndrome and myofibroblast signaling in the stem cell niche into studies in human SBS that have therapeutic potential. We have shown that a myofibroblast protein, epimorphin (Epim) regulates crypt fission, gut epithelial proliferation and myofibroblast secretory function in mice. Co-culture with Epim-/- myofibroblasts further enhances WT mouse crypt enteroid growth and surface area. Our overarching goals are to enhance the proliferative epithelial response and increase small bowel surface area as a therapeutic strategy for SBS. Our overarching hypothesis is that modulating myofibroblast Epim and its targets will enhance human small bowel growth providing a novel regenerative therapeutic approach to SBS. Aim 1 will directly translate our mouse studies by establishing stem cell/enteroid and myofibroblast cultures from the PI's large cohort of SBS patients. We will address the hypothesis that co- culture with Epim-deficient myofibroblasts increases the growth of human enteroids. We will determine whether growth and proliferative capacity of enteroids in vitro can predict the ability t adapt and wean from parenteral nutrition. Aim 2 will address two hypotheses. 1. MF-crypt epithelial interactions are modulated by Epim deletion to increase crypt stem cell proliferation and enteroid growth via altered Bmp, Hh, and Wnt signaling pathways. 2. Epim demonstrates context-specific inhibitory vs. pro-exocytotic roles in regulating MF secretion. Our studies are significant because we will directly translate our findings from preclinical studies to human studies of Epim deletion's effects on MF function in the stem cell niche. We will expand our unique clinical collection of small bowel crypt stem/enteroid cultures from SBS patients, and generate a national resource for potential future high throughput screening of therapeutic agents that enhance stem and crypt cell proliferation in SBS. Epim and the secretion of soluble factors that are modulated by Epim deletion represent potential novel therapeutic targets to promote intestinal stem/crypt epithelial proliferation, leading to adaptation. .