Molecular Mechanisms of LPS Preconditioning In Stroke

描述(申请人提供)：脑缺血是美国发病率和死亡率的主要原因之一，许多缺血病例是心血管手术后的继发性病例。用TOL样受体激动剂LPS预适应或预适应可诱导对缺血损伤的保护性反应，称为缺血耐受。这一竞争性更新应用试图阐明定义内毒素预适应诱导的缺血耐受的分子事件。我们先前的研究揭示了一个新的基因组指纹，它暗示I型干扰素(IFN)是内毒素诱导的缺血损伤耐受的主要效应因子。我们发现，内毒素预适应需要干扰素转录因子IRF3，我们最近的初步工作表明，也可能需要干扰素转录因子IRF7。此外，我们还发现，干扰素基因组指纹延伸到另外两种预适应刺激诱导的脑缺血保护：TLR9配体、未甲基化的CpG ODN和低剂量缺血，从而扩大了其重要性。一种新的干扰素指纹在神经保护中的出现支持了一种新的预适应工作模式，其中Toll样受体是其核心特征。阐明干扰素反应的功能可能有助于深入了解TLR诱导的卒中预防治疗的机制，并导致开发一种新的TLR诱导的急性神经保护途径，从而绕过预先预适应的需要。这些发现使我们假设，内毒素预适应通过IRF3/IRF7驱动的一组核心基因的表达来诱导神经保护，从而导致互补的神经保护途径。目的1.阐明转录因子IRF3和IRF7在TLR诱导的神经保护中的作用。目的2.确定干扰素指纹在脑缺血损伤中提供神经保护作用的机制。目的3.检测卒中急性期直接激活IRF3/7是否具有脑缺血保护作用。

DESCRIPTION (provided by applicant): Brain ischemia is one of the leading causes of morbidity and mortality in the United States, and many cases of ischemia are secondary to cardiovascular surgery. Pretreatment or preconditioning with a Tol-like Receptor agonist, LPS, induces a protective response to ischemic injury referred to as ischemic tolerance. This competitive renewal application seeks to elucidate the molecular events that define ischemic tolerance induced by LPS preconditioning. Our previous research revealed a novel genomic fingerprint that implicates type I interferons (IFNs) as primary effectors of LPS induced tolerance to ischemic injury. We discovered that the IFN transcription factor, IRF3 is required for LPS preconditioning and our recent preliminary work suggests that the IFN transcription factor, IRF7 may also be required. In addition we have found that the IFN genomic fingerprint extends to ischemic protection of the brain induced by two other preconditioning stimuli: a TLR9 ligand, unmethylated CpG ODNs and low dose ischemia thus broadening its importance. The appearance of a novel IFN fingerprint in neuroprotection supports a new working model of preconditioning in which Toll-like receptors are the central feature. Elucidation of the function of the IFN response may provide insight into the mechanism of TLR induced prophylactic treatment for stroke and lead to the development of a new TLR induced pathway of acute neuroprotection that by-passes the need for prior preconditioning. These findings have led us to hypothesize that LPS preconditioning induces neuroprotection through IRF3/IRF7 driven expression of a core set of genes that result in complimentary pathways of neuroprotection. We shall test the precepts of this model and its therapeutic potential in three aims: Aim 1. Elucidate the function of transcription factors IRF3 and IRF7 in TLR-induced neuroprotection. Aim 2. To determine the mechanism by which the IFN fingerprint confers neuroprotection in response to ischemic injury. Aim 3. Test whether direct activation of IRF3/7 in the acute setting of stroke leads to ischemic neuroprotection.