Microglia adenine nucleotides and hypoxia

描述（由申请人提供）：低氧脑损伤后小胶质细胞过度激活，它们向中枢神经系统释放神经毒性炎症介质，导致炎症和损伤。因此，调节小胶质细胞活性对于减少或预防中风、心肺疾病和呼吸障碍引起的脑损伤后的神经元损伤具有重要意义。细胞外腺嘌呤核苷酸是小胶质细胞炎症能力的重要调节剂，在脑损伤后大量存在。虽然已经做了很多工作来阐明ATP刺激小胶质炎症因子的机制，但它们对小胶质炎症介质产生的互补抑制作用知之甚少。指导这一建议的基本假设是，细胞外腺嘌呤核苷酸通过与嘌呤能受体信号转导途径相互作用来减少小胶质细胞的激活，从而在大脑中发挥神经保护作用。我们将研究腺嘌呤核苷酸介导的神经保护在小胶质细胞培养中的分子机制，使用两种小胶质细胞激活模型：细菌脂多糖（LPS）或缺氧。研究人员提出了四个特定的目标来测试嘌呤能受体影响神经毒性/炎症介质的小胶质细胞产生的机制，重点是嘌呤能受体MAP激酶途径和转录因子激活谱。嘌呤能受体的激活降低了小胶质细胞对几种小胶质激活剂的活性，表明嘌呤能受体与不同刺激的信号通路相互作用。然而，嘌呤能受体的激活在某些情况下会引起有害的影响，这意味着某些嘌呤能受体的治疗性调节可能会导致不同的影响，这取决于预先存在的小胶质细胞激活状态。这项工作的结果将有助于确定新的药物靶点，这些靶点可能被用于治疗控制小胶质细胞对几种刺激（包括缺氧）的激活。

DESCRIPTION (provided by applicant): Microglial cell hyperactivation following hypoxic brain injury, and their release of neurotoxic inflammatory mediators into the CNS contributes to inflammation and damage. Hence, modulation of microglial cell activity is of great interest to decrease or prevent neuronal damage following brain injury from stroke, heart or lung disease and breathing disorders. Extracellular adenine nucleotides are important modulators of microglial cell inflammatory capacity, and they are abundant following brain injury. Although much work has been done elucidating the mechanisms involved in ATP stimulation of microglial inflammatory cytokines, little is known about their complementary inhibitory effects on microglial inflammatory mediator production. The fundamental hypothesis guiding this proposal is that extracellular adenine nucleotides exert neuroprotective effects in the brain by interacting with purinergic receptor signal transduction pathways to decrease microglial cell activation. We will investigate the molecular mechanisms underlying adenine nucleotide mediated neuroprotection in microglial cell cultures using two models of microglial activation: bacterial lipopolysaccharide (LPS) or hypoxia. Four specific aims are proposed to test mechanisms by which purinergic receptors influence microglial production of neurotoxic/inflammatory mediators, focusing on purinergic receptor MAP kinase pathways and transcription factor activation profiles. Purinergic receptor activation decreases microglial cell activity in response to several microglial activators, suggesting that purinergic receptors interact with signaling pathways common to different stimuli. However, purinergic receptor activation can cause deleterious effects in some situations, implying that therapeutic modulation of certain purinergic receptors may result in different effects depending upon the pre-existing microglial activation status. Results of this work will aid in the identification of new pharmacologic targets that may be exploited therapeutically to control microglial activation in response to several stimuli including hypoxia.