Inhibition of Microflora-Induced Colitis by NF-kB

描述(由申请人提供)：本提案的目的是确定核因子-kappaB亚单位p50和p65抑制下肠道炎症的细胞和分子机制。P50的抑制功能可能与控制结肠内的炎症特别相关，因为我们的实验室已经表明，缺乏p50(p50-/-)的小鼠对肝螺杆菌诱导的结肠炎敏感，并且这种敏感性在既缺乏p50又是p65(p50-/-p65+/-)杂合子的小鼠中显著加剧。这些小鼠由于先天免疫系统固有的缺陷而对结肠炎的发展敏感。这一缺陷可能反映出无法控制His诱导的抗原提呈细胞(APC)内炎症基因的表达，因为His感染导致p50-/-和p50-/-p65+/巨噬细胞中关键炎症细胞因子IL-12p40和IP-10的水平高于WT巨噬细胞。这项建议的目的是：1)确定先天免疫系统细胞内的p50和p65在抑制肝炎性反应中的作用机制。使用我们实验室创造的一种新的小鼠品系(p50-/-p65+/-rag-2-/-)，我们将评估先天免疫系统中需要p50/p65活性以促进调节性T细胞的抑制功能的可能性。2)探讨p50和p65抑制肝炎性基因表达的机制。我们将使用分子技术比较内源性IL-12p40和IP-10启动子在WT、p50-/-和p50-/-p65+/-巨噬细胞中的功能。3)确定p50和p65是否可以防止伤害宿主的过度侵袭性免疫反应，或者p50和p65是否可以防止导致细菌负担增加的免疫缺陷。我们将比较p50-/-p65+/-rag-2-/-小鼠和p50-/-p65+/-rag-2-/-小鼠的细菌负荷，并确定向p50-/-p65+/-rag-2-/-小鼠引入功能性天然免疫细胞是否可以预防肝炎病毒引起的炎症。综上所述，我们相信这些研究将导致对炎症性肠病分子发病机制的深入了解，从而可能导致新的治疗策略。

DESCRIPTION (provided by applicant): The purpose of this proposal is to define the cellular and molecular mechanisms by which the NF-kappaB subunits p50 and p65 inhibit inflammation within the lower bowel. The inhibitory functions of p50 may be especially relevant to the control of inflammation within the colon, as our laboratory has shown that mice lacking p50 (p50-/-) are sensitive to colitis induced by Helicobacter hepaticus, and this sensitivity is significantly exacerbated in mice that both lack p50 and are heterozygous for p65 (p50-/-p65+/-). These mice are sensitized to the development of colitis by a defect intrinsic to the innate immune system. This defect may reflect an inability to control H. hepaticus-induced inflammatory gene expression within antigen presenting cells (APCs), as H. hepaticus infection induces higher levels of the critical inflammatory cytokines IL-12p40 and IP-10 in p50-/- and p50-/-p65+/- macrophages than in WT macrophages. The goals of this proposal are: 1) To determine the mechanism by which p50 and p65 within cells of the innate immune system contribute to inhibiting the inflammatory response to H. hepaticus. Using a novel mouse strain created in our laboratory (p50-/-p65+/-RAG-2-/-), we will evaluate the possibility that p50/p65 activity is required within the innate immune system to facilitate the inhibitory function of regulatory T cells. 2) To determine the mechanisms by which p50 and p65 inhibit H. hepaticus induced inflammatory gene expression. We will use molecular techniques to compare the function of endogenous IL-12p40 and IP-10 promoters in WT, p50-/-, and p50-/-p65+/- macrophages. 3) To determine whether p50 and p65 prevent an overaggressive immune response that injures the host, or alternatively, whether p50 and p65 prevent an immune deficiency that leads to increased bacterial burden. We will compare bacterial burden in RAG-2-/- and p50-/-p65+/-RAG-2-/- mice, and determine whether introduction of functional innate immune cells into p50-/-p65+/-RAG-2-/- mice can prevent H. hepaticus-induced inflammation. Taken together, we believe that these studies will lead to insights regarding the molecular pathogenesis of inflammatory bowel disease that could lead to novel therapeutic strategies.