Activation of inflammatory cells by flagellin

描述(申请人提供)：先天免疫反应的激活 由细菌介导，由一组分子共同调节 称为调制素。这些与表面相关的分子是由广泛的 微生物单核细胞、巨噬细胞、中性粒细胞和上皮细胞阵列 通过产生促炎细胞因子来对调制素作出反应。产品的生产 细胞因子对于保护性的先天免疫和获得性免疫反应是必不可少的。 然而，细胞因子的过度产生也与 与重症肺炎患者败血症反应相关的病理事件 细菌感染。我们和其他人已经证明了来自一种 革兰氏阴性菌种数可诱生促炎细胞因子 由单核细胞和肠道上皮细胞产生。我们证明了这一点 鞭毛的主要结构蛋白鞭毛蛋白是 是诱导细胞因子合成所必需的。鞭毛蛋白信号是 由Toll样受体(TLR)蛋白TLR5介导，但可由 另一个TLR，TLR4。鉴于鞭毛蛋白作为一种 参与宿主防御的细胞的激活剂，我们建议如下 具体目标：1.确定所需的组成部分和途径 用于依赖TLR5的鞭毛蛋白信号转导。GG2EE是一种巨噬细胞 来源于内毒素低反应的C3H/HeJ小鼠。就像来自 这种小鼠品系GG2EE细胞表达TLR4的缺陷形式，因此 对内毒素的反应很差。相反，GG2EE细胞表达野生型形式的 TLR5，从而产生响应鞭毛蛋白的TNFa。然而，这些细胞确实 不会因鞭毛蛋白而产生一氧化氮。我们将确定TLR 鞭毛蛋白信号的要求和信号组件 细胞因子和一氧化氮的合成。2.确定通过什么机制 鞭毛蛋白诱导随后的鞭毛蛋白耐受状态。对以下方面的响应 鞭毛蛋白可以受到多种因素的影响，包括鞭毛蛋白本身。 暴露于鞭毛蛋白的细胞对二次刺激不敏感 鞭毛蛋白。这种缺乏响应性与戏剧性的 IRAK激酶活性下降。伊拉克活动的减少并不是因为 IRAK蛋白水平的下降。其他调查人员已经 证实单核细胞暴露于内毒素也会导致内毒素状态 反应迟钝。内毒素耐受细胞也表现出非常低的水平 鞭毛蛋白响应性。然而，鞭毛蛋白耐受细胞是完全 对内毒素有反应。我们将确定鞭毛蛋白这种作用的机制 因为它对宿主的反应具有重要影响 鞭毛蛋白。此外，拟议的研究还应提供以下方面的见解 调节TLR信号并允许宿主的复杂模式的因素 细胞反应。

DESCRIPTION (provided by applicant): Activation of the innate immune response by bacteria is mediated by a group of molecules that have collectively been termed modulins. These surface-associated molecules are produced by a broad array of microbial Monocytes, macrophages, neutrophils and epithelial cells respond to modulins by producing proinflammatory cytokines. The production of cytokines is essential for protective innate and adaptive immune responses. However, excessive production of cytokines has also been implicated in the pathologic events associated with the septic response in patients with severe bacterial infections. We and others have demonstrated that flagella from a number of gram-negative bacterial species induce proinflammatory cytokine production by monocytes and intestinal epithelial cells. We demonstrated that the major structural protein of the flagella, flagellin, is the component required for the induction of cytokine synthesis. Flagellin signaling is mediated by a toll-like receptor (TLR) protein, TLR5, but can be modulated by another TLR, TLR4. In view of the extraordinary potency of flagellin as an activator of cells that are involved in host defense, we propose the following specific aims: 1. To determine the components and pathways that are required for TLR5-dependent flagellin signal transduction. GG2EE is a macrophage cell line derived from the LPS-hyporesponsive C3H/HeJ mouse. Like the cells from this mouse strain, GG2EE cells express a defective form of TLR4 and thus respond poorly to LPS. In contrast, GG2EE cells express a wild-type form of TLR5 and thus produce TNFa in response to flagellin. However, these cells do not produce nitric oxide in response to flagellin. We will determine the TLR requirements and signaling components for flagellin signaling leading to cytokine and nitric oxide synthesis. 2. To determine the mechanism by which flagellin induces a subsequent state of flagellin tolerance. Responsiveness to flagellin can be influenced by several factors including flagellin itself. Cells that are exposed to flagellin become insensitive to secondary stimulation by flagellin. This lack of responsiveness is associated with a dramatic decrease in IRAK kinase activity. This decrease in IRAK activity is not due to a decrease in the level of the IRAK protein. Other investigators have established that exposure of monocytes to LPS also results in a state of LPS non-responsiveness. LPS tolerant cells also exhibit a very low level of flagellin responsiveness. However, flagellin tolerant cells are fully responsive to LPS. We will determine the mechanism for this effect of flagellin since it has important implications with regard to the host response to flagellin. Furthermore, the proposed studies should also provide insights into the factors that regulate TLR signaling and allow for complex patterns of host cell response.