Purines and the Health of Retinal Ganglion Cells

描述（申请人提供）：青光眼是世界范围内致盲的主要原因，其特点是视神经头星形胶质细胞和视网膜神经节细胞发生一系列病理改变，最终导致视力丧失。虽然细胞损伤的最大危险因素是眼压升高，但促炎细胞因子也有助于慢性疾病。然而，将生理压力与细胞因子反应联系起来的机制尚不清楚。这一建议是基于一种新的假设，即细胞外ATP将机械应变与青光眼中增强的细胞因子反应联系起来。特别是，视神经星形胶质细胞通过pannexin通道机械敏感释放ATP，可自刺激邻近的P2X7受体，在分子水平上上调细胞因子表达，并通过炎性体和经典释放途径激活细胞因子释放。通过体内IOP升高模型和体外细胞拉伸模型，我们将展示应变和炎症之间的联系机制，并确定干预点。目的1将证实细胞因子IL-1和IL-6在慢性和急性青光眼模型中的作用。将确定细胞因子激活的时间过程，并评估老年动物中促炎信号的相对贡献。pannexin和P2X7通道的作用将在敲除小鼠的分子水平和通道阻滞剂的药理学水平上进行探索；拮抗剂减少炎性体激活的能力可能会确定新的治疗方法。在Aim 2中，我们将在视神经头星形胶质细胞中确认机械应变、ATP和细胞因子之间的联系机制，同时确定炎症小体产物IL-1对视网膜神经节细胞健康的影响。总之，本研究将证明嘌呤能信号将IOP升高与星形胶质细胞炎症反应增强和视网膜神经节细胞病理联系起来。这种新方法将在确定可能的新干预目标的同时，在机制水平上推进我们对疾病的理解。

DESCRIPTION (provided by applicant): Glaucoma is a major cause of blindness worldwide and is characterized by a series of pathological changes to optic nerve head astrocytes and retinal ganglion cells that eventually lead to vision loss. While the biggest risk factor for cell injury is elevated intraocular pressure (IOP), proinflammatory cytokines also contribute to the chronic disease. The mechanisms connecting physical strain to the cytokine response are unclear, however. This proposal is based upon the novel hypothesis that extracellular ATP links mechanical strain to the enhanced cytokine response in glaucoma. In particular, the mechanosensitive release of ATP through pannexin channels on optic nerve astrocytes can autostimulate adjacent P2X7 receptors, upregulating cytokine expression on a molecular level and activating cytokine release through both the inflammasome and classic release pathways. Using in vivo models of elevated IOP and in vitro models of cell stretch, we will demonstrate the mechanisms linking strain and inflammation and identify points of intervention. Aim 1 will confirm the involvement of cytokines IL-1� and IL-6 in models of chronic and acute glaucoma. The time course of cytokine activation will be determined and the relative contribution of proinflammatory signals in older animals will be assessed. The contribution of pannexin and P2X7 channels will be explored on a molecular level with knockout mice, and on a pharmacological level with channel blockers; the ability of antagonists to reduce inflammasome activation may identify new treatments. In Aim 2, the mechanisms connecting mechanical strain, ATP and cytokines will be confirmed in optic nerve head astrocytes while the effects of inflammasome product IL-1� on retinal ganglion cell health will be determined. In summary, this proposal will demonstrate that purinergic signaling links elevated IOP with the enhanced inflammatory response in astrocytes and pathology in retinal ganglion cells. This novel approach will advance our understanding of the disease on a mechanistic level while identifying possible new targets for intervention.