Mechanisms of Adenosine Protection

描述（由申请人提供）：炎症伴随着组织代谢的实质性变化。炎症的主要代谢特征之一是缺氧，其最近被认为显著影响炎症性疾病的结果。在疾病过程的早期，这种"炎性缺氧"在很大程度上是由于需要氧的炎性细胞类型，特别是嗜中性粒细胞的募集。近年来，我们一直专注于确定炎症缺氧启动的靶点和分子途径。这些研究的结果已经定义了一系列新的信号传导机制，其中缺氧（体外和体内）驱动细胞外核苷酸的代谢，产生大量的细胞外腺苷。该途径的核心是鉴定缺氧诱导因子（HIF）作为Ado代谢所必需的酶（特别是CD73）的重要调节剂，从而鉴定HIF调节的Ado产生作为内源性抗炎途径。正在进行的研究表明，Ado通过Cullin的主动去内酰化来调节HIF，Cullin是一种对泛素连接酶的募集至关重要的蛋白质家族。基于这些初步研究，我们假设在炎症反应早期产生的Ado通过对粘膜HIF稳定的直接作用作为前馈抗炎机制发挥作用。三个具体目标是针对测试这一假设：在具体目标1中，我们将定义中性粒细胞和上皮细胞在炎症部位对Ado生成的贡献。具体目标2将扩展初步数据，以阐明ESTA介导的Cullin-2去neddylation的机制。特异性目的3将探讨Ado对HIF介导的保护作用。该提案的总体目标是确定炎症缺氧期间粘膜内HIF和Ado的新代谢信号。 公共卫生相关性：该提案旨在了解代谢在粘膜炎症中的作用，例如在炎症性肠病（IBD）中观察到的作用。本文提出的研究结果将大大解决炎症领域的一些未回答的问题，包括：哪些细胞类型对与炎症相关的代谢变化贡献最大？这些代谢变化对组织是保护性的还是有害的？这些代谢变化是否可以作为治疗获益的靶点？这些问题的答案，通过实验提出这里将提供一个重要的基础，其中整合新的治疗方法粘膜炎症。

DESCRIPTION (provided by applicant): Inflammation is accompanied by a substantial shift in tissue metabolism. One of the major metabolic signatures of inflammation is hypoxia, which is recently appreciated to significantly influence inflammatory disease outcome. Early in the disease process, such "inflammatory hypoxia" results, in large extent, from the recruitment of oxygen demanding inflammatory cell types, particularly neutrophils. In recent years, we have focused on defining targets and molecular pathways set into motion by inflammatory hypoxia. Results from these studies have defined a series of novel signaling mechanisms in which hypoxia (both in vitro and in vivo) drives the metabolism of extracellular nucleotides toward the generation of large amounts of extracellular adenosine. Central to this pathway was the identification of hypoxia-inducible factor (HIF) as an important regulator of the enzymes necessary for Ado metabolism (esp. CD73), thus identifying HIF-regulated Ado production as an endogenous anti-inflammatory pathway. Ongoing studies have revealed that Ado regulates HIF through the active deneddylation of Cullins, a family of proteins critical for the recruitment of ubiquitin ligases. Based on these preliminary studies, we hypothesize that Ado generated early in the inflammatory response functions as a feed-forward anti- inflammatory mechanism through direct actions on mucosal HIF stabilization. Three specific aims are directed at testing this hypothesis: In Specific Aim 1, we will define the contribution of neutrophils and epithelia to Ado generation at sites of inflammation. Specific Aim 2 will extend preliminary data to elucidate mechanisms of Ado-mediated Cullin-2 de-neddylation. Specific Aim 3 will Probe the role of Ado to HIF-mediated protection. The overall aim of this proposal is to identify novel metabolic signaling by HIF and Ado within the mucosa during inflammatory hypoxia. PUBLIC HEALTH RELEVANCE: This proposal aims at understanding the role of metabolism in mucosal inflammation such as that observed in inflammatory bowel disease (IBD). Results from the studies proposed here will go far to resolve a number of unanswered questions in the field of inflammation, including: What cell types contribute most significantly to the metabolic changes associated with inflammation? Are these metabolic changes protective or detrimental to the tissue? Can these metabolic changes be targeted for therapeutic benefit? Answers to these questions through experiments proposed here will provide an important foundation for which to integrate novel therapeutic approaches for mucosal inflammation.