Mechanisms of Neurotensin in Intestinal Inflammation

描述（由申请人提供）：炎症性肠病（IBD）是一种具有显著发病率和死亡率的临床实体，其病理生理学尚不完全清楚。越来越多的证据表明，神经肽是结肠炎症发病机制的主要参与者。我们发现神经肽神经紧张素（NT）在结肠炎急性期起促炎介质的作用。我们的初步证据还表明，NT缺乏小鼠肠道炎症反应减少，为该肽在肠道炎症中的重要性提供了直接证据。然而，NT也通过激活EGF受体（EGFR）和磷酸化抗凋亡信号分子Akt来促进炎症修复阶段的愈合。因此，我们对这一修订更新应用的目的1的假设是NT通过减少细胞凋亡和增加细胞增殖参与结肠炎的愈合阶段。因此，Aim 1将研究NT-NT受体1 （NTR1）诱导的akt和egfr相关的抗凋亡和增殖反应在分离的结肠炎和实验性结肠炎模型中的信号机制。我们还发现结肠炎期间肠系膜脂肪库中NT和NTR1的表达增加，并在小鼠前脂肪细胞中发现NT和NTR1的表达，这些细胞因子的释放和增殖增加对NT有反应。这些发现首次将结肠炎期间肠系膜脂肪nt - ntr1依赖性炎症变化联系起来，可能对IBD具有重要意义，因为IBD患者手术期间肠道脂肪包裹是常见的发现。因此，aim 2将通过比较肠系膜脂肪中NT和NTR1表达与ibd相关模型中粘膜和脂肪组织炎症程度的关系，研究急慢性实验性结肠炎中结肠黏膜和肠系膜库之间NT介导的串音。在分离的前脂肪细胞中进行的实验将检验NT刺激促炎细胞因子和脂肪因子释放、改变粘附分子表达和刺激巨噬细胞向这些细胞迁移的机制。目的1和目的2的实验还将比较NT缺乏型和野生型小鼠脂肪库的结肠炎和炎症变化。aim 3的研究将确定nt诱导的前脂肪细胞IGF-1R磷酸化的信号转导途径，并研究NT-NTR1相互作用导致细胞增殖和迁移的机制。我们的研究结果将为NT及其受体在结肠炎症中的作用以及在IBD和实验性结肠炎动物模型中观察到的肠系膜脂肪组织的激活和炎症中的扩展作用提供重要的见解。本项目将研究神经肽神经紧张素参与肠道炎症和炎症性肠病发病的病理生理机制。这个项目的一部分还研究了这种神经肽如何影响结肠炎症改变后邻近脂肪组织炎症的发展。

DESCRIPTION (provided by applicant): The pathophysiology of Inflammatory Bowel Disease (IBD), a clinical entity with significant morbidity and mortality, is not completely understood. Emerging evidence indicates that neuropeptides are major participants in the pathogenesis of colonic inflammation. We showed that the neuropeptide neurotensin (NT) acts as a proinflammatory mediator in the acute phase of colitis. Our preliminary evidence also indicates that NT deficient mice have reduced intestinal inflammatory responses, providing direct evidence for the importance of this peptide in intestinal inflammation. However, NT also promotes healing during the repair phase of inflammation by activating the EGF receptor (EGFR) and phosphorylating the anti-apoptotic signaling molecule Akt. Thus, our hypothesis for aim 1 of this revised renewal application is that NT participates in the healing phase of colitis by reducing apoptosis and increasing cell proliferation. Aim 1 therefore will examine the signaling mechanisms involved in NT-NT receptor 1 (NTR1)-induced Akt-and EGFR-related anti-apoptotic and proliferative responses in isolated colonocytes and models of experimental colitis. We also found increased NT and NTR1 expression in the mesenteric fat depots during colitis and identified expression of NT and NTR1 in mouse preadipocytes that respond to NT be release of cytokines and increased proliferation. These findings link for the first time NT-NTR1-dependent inflammatory changes in mesenteric fat during colitis and may be of major importance in IBD where fat wrapping of the bowel is a common finding during surgery of IBD patients. Thus, in aim 2 will examine the NT-mediated cross talk between the colonic mucosa and mesenteric depots in acute and chronic experimental colitis by comparing NT and NTR1 expression in mesenteric fat to the degree of mucosal and adipose tissue inflammation in IBD-related models. Experiments in isolated preadipocytes will examine the mechanisms by which NT stimulates release of proinflammatory cytokines and adipokines, alters expression of adhesion molecules, and stimulates macrophage migration to these cells. Experiments in aim 1 and 2 will also compare colitis and inflammatory changes in fat depots between NT deficient and wild type mice. Studies in aim 3 will determine the signal transduction pathways involved in NT-induced IGF-1R phosphorylation in preadipocytes and examine the mechanisms by which NT-NTR1 interactions lead to cell proliferation and migration. Our results will provide important insights on the role of NT and its receptor in colonic inflammation and its expanded role in activation and inflammation of mesenteric adipose tissue observed in IBD and animal models of experimental colitis. PUBLIC HEALTH REVELVANCE This project will examine the pathophysiologic mechanisms by which the neuropeptide neurotensin participates in the pathogenesis of intestinal inflammation and Inflammatory Bowel Disease. Part of this project also examines how this neuropeptide influences development of inflammation in the adjacent fat tissue following colonic inflammatory changes.