A20 Mediated Regulation of Colitis and Spondyloarthritis

描述（由申请人提供）：最近的研究表明，炎症性肠病（IBD）是由正常宿主免疫细胞对微生物分子的反应被破坏引起的，微生物分子可以引发肠道炎症。树突状细胞是一种特殊的免疫细胞，对微生物高度敏感，可以有效地激活炎症细胞。由于dc可能频繁或强直性地感知肠道中微生物的存在，它们引起炎症的倾向可能取决于它们对与微生物接触的细胞内调节或“解释”。因此，调节由微生物触发的信号的细胞内蛋白可能是显性炎症反应的核心。A20是一种能有效限制微生物感知途径信号的酶，包括toll样受体（TLR）、NOD和TNF信号。因此，我们的中心假设是，在dc中特异性表达A20可以保持免疫稳态并预防IBD和IBD相关关节炎。为了验证我们的中心假设，我们产生了一种新的小鼠品系，A20FL/FL CD11c-Cre小鼠，其中A20特异性地从dc中删除。显著的;我们对这些小鼠的初步数据表明，这些小鼠自发发展为结肠炎、血清阴性关节炎和脊柱炎，这是人类IBD的一种典型综合征。我们现在建议使用这些A20FL/FL CD11-cre小鼠来确定将dc中A20表达与这些刺激性表型联系起来的细胞和分子机制。具体来说，我们将确定肠道微生物和T细胞是否参与了A20缺陷dc引起结肠炎和关节炎的病理生理过程（目的1）。由于A20可能限制dc细胞内信号，包括MyD88依赖性TLR信号，我们将使用复合A20FL/FL MyD88FL/FL CD11c-Cre小鼠来确定dc中哪些A20调节信号是MyD88依赖性的，哪些信号是MyD88非依赖性的。对这些小鼠的研究将揭示细胞内DC信号和DC产物调节T细胞活化、结肠炎和血清阴性关节炎（Aim 2）。A20是一种泛素修饰酶，调节信号蛋白的泛素化，也与A20 Binding Inhibitor of NFkB-1或ABIN-1结合。为了确定A20和ABIN-1协同限制dc中信号的分子机制，我们还生成了dc中特异性缺乏ABIN-1的小鼠。我们现在将使用这些小鼠来研究ABIN-1如何与A20合作限制dc中的信号传导并预防结肠炎和关节炎（Aim 3）。

DESCRIPTION (provided by applicant): Recent studies suggest that inflammatory bowel disease (IBD) results from the disruption of normal host immune cells responses to microbial molecules that can trigger inflammation in the intestine. Dendritic cells (DCs) are specialized immune cells that are highly sensitive to microbes and can potently activate inflammatory cells. As DCs may frequently or tonically sense the presence of microbes in the intestine, their propensity to cause inflammation may be dependent on their intracellular regulation or "interpretation" of encounters with microbes. Hence, intracellular proteins that regulate signals triggered by microbes may be central to the commitment to overt inflammatory responses. A20 is an enzyme that potently restricts signals from microbial sensing pathways, including Toll-like receptor (TLR), NOD and TNF signals. Thus, our central hypothesis is that A20 expression specifically in DCs preserves immune homeostasis and prevents IBD and IBD-associated arthritis. To test our central hypothesis, we have generated a novel strain of mice, A20FL/FL CD11c-Cre mice, in which A20 is deleted specifically from DCs. Remarkably; our preliminary data with these mice suggest that these mice spontaneously develop colitis, sero-negative arthritis and spondyloarthritis, a stereotypical syndrome in human IBD. We now propose to use these A20FL/FL CD11-cre mice to determine the cellular and molecular mechanisms linking A20 expression in DCs to these provocative phenotypes. Specifically, we will determine whether luminal microbes and T cells are involved in the pathophysiologies by which A20 deficient DCs cause colitis and arthritis (Aim 1). As A20 may restrict intracellular signals in DCs, including MyD88 dependent TLR signals, we will use compound A20FL/FL MyD88FL/FL CD11c-Cre mice to determine which A20 regulated signals in DCs are MyD88-dependent and which signals are MyD88-independent. Studies with these mice will unveil which intracellular DC signals and DC products regulate T cell activation, colitis, and sero-negative arthritis (Aim 2). A20 is a ubiquitn modifying enzyme that regulates ubiquitination of signaling proteins and also binds to A20 Binding Inhibitor of NFkB-1, or ABIN-1. To define the molecular mechanisms by which A20 and ABIN-1 may collaborate to restrict signals in DCs, we have also generated mice lacking ABIN-1 specifically in DCs. We will now use these mice to study how ABIN-1 collaborates with A20 to restrict signaling in DCs and prevent colitis and arthritis (Aim 3). PUBLIC HEALTH RELEVANCE: This project focuses on a novel anti-inflammatory protein called A20 and how it regulates dendritic cells, colitis, and colitis associated arthritis. Dendritc cells and Toll-like receptors are central to the pathogenesis of inflammatory bowel diseases. In addition, recent human genetic studies have revealed that SNPs of the human A20 gene are associated with Crohn's disease. Therefore, understandings how A20 regulates dendritic cells and prevents colitis and colitis associated arthritis will significantly enhance the development of therapies for inflammatory bowel diseases and have major benefits for public health.