IL1 and hypoxic-ischemic insults

描述（由申请人提供）：脑缺血（即中风）引起的脑损伤是一个主要的公共卫生问题。多达50%的中风引起的脑损伤发生在损伤的主要焦点之外，组织破坏的过程持续数小时至数天。现在很明显，炎症因子有助于这种延迟的病理生理学。具体来说，研究表明，细胞因子，白细胞介素1 β（IL-1 β），上调后，实验和临床中风，而其他研究牵连它在损伤的进展。然而，IL-1 β促进神经元细胞死亡的细胞和分子途径尚未确定。这主要是由于缺乏合适的体外模型来评估这些机制。因此，我们开发了一个可靠的和可重复的体外模型系统，利用混合的神经元/星形胶质细胞皮质细胞培养。在该模型中，通过外源性添加IL-1 β和通过剥夺细胞的氧诱导的神经元损伤来模拟IL-1 β的内源性产生。我们发现，预处理-但不是同时或后处理-与这种细胞因子显着增强神经元细胞死亡诱导的剥夺混合小鼠皮层细胞培养物的氧气。IL-1 β的作用是浓度依赖性的，并且可以被重组IL-1受体拮抗剂完全抑制，表明通过I型IL-1受体（IL 1 R1）的信号传导参与。此外，我们发现这种IL-1 β介导的缺氧神经元损伤的增强可以通过代谢型谷氨酸受体1（但不是mGluR 5）的药理学拮抗作用完全阻止。这与不受mGluR 1受体拮抗作用影响的纯缺氧神经元损伤形成鲜明对比。最后，我们发现IL-1 β诱导的损伤的增强依赖于星形胶质细胞中IL 1 R1的表达，而神经元中信号的丢失则没有影响。因此，本五年研究计划的目标是：1）确定IL-1 β信号与mGluR 1信号在功能上协同作用以增强缺氧神经元损伤的分子机制; 2）确定负责介导IL-1 β增强效应的星形胶质细胞因子;以及3）评估去除IL-1 β信号传导是否可以有效地预防/改善由直接海马注射NMDA和/或大脑中动脉闭塞引起的海马损伤。这些事件的定义的改善可能导致新的治疗策略的发展，旨在减轻中风后神经元破坏的进展。

DESCRIPTION (provided by applicant): Injury to the brain caused by cerebral ischemia (i.e. stroke) is a major public health concern. As much as 50% of the brain damage incurred by stroke occurs outside of the primary focus of damage with the process of tissue destruction continuing for hours to days. It is now apparent that inflammatory factors contribute to this delayed pathophysiology. Specifically, studies demonstrate that the cytokine, interleukin 1beta (IL-1beta), is upregulated following experimental and clinical stroke while additional studies implicate it in the progression of injury. However, the cellular and molecular pathway(s) by which IL-1beta contributes to neuronal cell death have yet to be identified. This is largely due to the lack of suitable in vitro models in which to assess these mechanisms. Therefore, we developed a reliable and reproducible in vitro model system utilizing mixed neuronal/astrocyte cortical cell cultures. In this model, endogenous production of IL-1beta is simulated by exogenous addition of IL-1beta and neuronal injury induced by depriving cells of oxygen. We found that pre-treatment - but not concurrent or post-treatment - with this cytokine dramatically potentiated neuronal cell death induced by depriving mixed murine cortical cell cultures of oxygen. The effect of IL-1beta was concentration-dependent and could be completely inhibited by the recombinant IL-1 receptor antagonist, indicating that signaling through the IL-1 receptor type I (IL1R1) was involved. Further, we found this IL-1beta -mediated enhancement of hypoxic-neuronal injury can be completely prevented by pharmacological antagonism of metabotropic glutamate receptor 1 (but not mGluR5). This is in stark contrast to a pure hypoxic neuronal injury which is unaffected by mGluR1 receptor antagonism. Finally, we found that the enhancement of injury induced by IL-1beta was dependent on astrocytic expression of IL1R1 whereas loss of signaling in neurons had no effect. Thus, the objectives of this five year research plan are to 1) determine the molecular mechanism(s) by which IL1beta signaling functionally synergizes with mGluR1 signaling to enhance hypoxic neuronal injury; 2) to determine the astrocytic factor or factors responsible for mediating the IL-1beta enhancing effect; and 3) to assess whether removal of IL-1beta signaling can effectively prevent/ameliorate hippocampal injury in vivo induced by direct hippocampal injection of NMDA and/or middle cerebral artery occlusion. Improved definition of these events could lead to the development of new therapeutic strategies designed to attenuate the progression of neuronal destruction following stroke.