Extracellular Matrix in Inflammatory Bowel Disease

溃疡性结肠炎(UC)的组织损伤主要是上皮细胞及其基底膜的溃烂。相反，克罗恩病(CD)的特点是纤维性胶原在固有层、粘膜肌层、粘膜下层、固有肌层和浆膜中过度沉积。因此，在这两种形式的炎症性肠病(IBD)中，组织重塑以及间质的破坏和恢复都是导致解剖破坏和重大临床后果的连续和动态的过程。由于粘膜T淋巴细胞被包裹在被称为细胞外基质(ECM)的蛋白质、糖蛋白和蛋白多糖组成的复杂和高度组织化的网络中，我们认为IBD的慢性化、恶化和复发是多因素的，涉及一个混合的致病T细胞对组织损伤和纤维化产生不利影响的过程，反之亦然。我们已发表的和初步的结果表明，整合素介导的与ECM的黏附是产生免疫反应的中心事件。因此，我们推测ECM的黏附和辅助功能也是调控IBD的关键机制。我们报道，在效应/记忆T细胞中，由胶原启动的信号转导通路与由纤维连接蛋白启动的不同。此外，调节细胞骨架重组的小GTP酶的Rho家族成员在黏附于纤维连接蛋白的T细胞中被激活，而在T细胞与胶原结合时被激活的Rho家族成员不同，波形蛋白(T细胞中间细丝的关键成分)头部区域上的丝氨酸磷酸化模式也类似地不同。我们还证明了由对照患者的人肠成纤维细胞(HIF)合成的三维天然ECM在T细胞中启动了不同于克罗恩病患者HIF分泌的天然基质的信号转导级联。当我们将(I)CD来源的天然ECM模拟纯化的胶原启动的转导级联与(Ii)胶原在慢性炎症的CD粘膜和固有层中过度沉积的观察结果相结合时，我们提出了以下中心假设：在IBD的ECM的持续重塑过程中，UC和CD是一个截然不同的修复过程，部分整合素与粘膜T细胞的结合调节并潜在地破坏其信号和功能，从而导致炎症过程的慢性化和复发。这一假说将通过两个特定的目的来验证：目的1.分子：定义由交替的ECM受体参与的信号通路，这些受体调节LPT细胞骨架重排，特别是Rho家族的小GTP酶。目的2.生化：评估移行性LPT中不同整合素分子的连接所调节的特异性蛋白丝氨酸激酶和靶蛋白，尤其是波形蛋白。

Tissue damage in Ulcerative colitis (UC) is predominantly ulceration of the epithelium and its underlying basement membrane. In contrast, Crohn’s disease (CD) is characterized by excessive deposition of fibrillar collagen in the lamina propria, muscularis mucosa, submucosa, muscularis propria, and serosa. Thus, in both forms of inflammatory bowel disease (IBD) tissue remodeling and the destruction and restitution of the interstitium are continual and dynamic processes that contribute to anatomical destruction and major clinical consequences. In that mucosal T lymphocytes are enmeshed in the complex and highly organized network of proteins, glycoproteins, and proteoglycans known as the extracellular matrix (ECM), we propose that the chronicity, exacerbation, and recurrence of IBD are multifactorial, involving a process by which the intermingled pathogenic T cells adversely affects tissue injury and fibrosis, and vice versa. Our published and preliminary results show that integrin-mediated adhesion to the ECM is a central event in the generation of an immune response. Therefore, we postulate that ECM adhesion and accessory function is also a pivotal mechanism that modulates IBD. We report that the signal transduction pathway initiated by collagen in an effector/memory T cell is different from that initiated by fibronectin. In addition, the Rho family member of small GTPases, which regulate cytoskeletal reorganization, activated in a T cell adherent to fibronectin differs from that activated when the T cell is bound to collagen, and that the pattern of serine phosphorylation on the head domain of vimentin (the key component of the intermediate filament in T cells) is similarly distinct. We also demonstrate that a three dimensional, native ECM synthesized by human intestinal fibroblasts (HIF) from a control patient initiates a signal transduction cascade in T cells different from that initiated by a native matrix secreted by HIF from patients with Crohn’s disease. When we couple the observation that (i) CD-derived native ECM mimics the transduction cascade initiated by purified collagen to (ii) the excessive deposition of collagen in the chronically inflamed CD mucosa and lamina propria, we propose the following central hypothesis: During the continuous remodeling of the ECM in IBD, a repair process quite distinct between UC and CD, engagement of select integrins on mucosal T cells modulates and potentially disrupts their signaling and function, thus contributing to chronicity and recurrence of the inflammatory process. This hypothesis will be tested by two specific aims: Aim 1. Molecular: Define the signaling pathways engaged by alternate ECM receptors that regulate LPT cytoskeletal rearrangement with a particular focus on the Rho family of small GTPases. Aim 2. Biochemical: Evaluate the specific protein serine kinases and target proteins modulated by the ligation of distinct integrin molecules in the migratory LPT, with a particular focus on vimentin.