Uncoupling caspase 8-mediated-apotosis from caspase 8-mediated-inflammation in glaucoma.

将青光眼中 caspase 8 介导的细胞凋亡与 caspase 8 介导的炎症解偶联。

• 批准号: 9919567
• 负责人: MEREDITH GREGORY-KSANDER
• 金额: $ 24.63万
• 依托单位: SCHEPENS EYE RESEARCH INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-05-01 至 2022-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9919567
• 关键词: Anti-Inflammatory Agents; Apoptosis; Apoptotic; Axon; BAX gene; Blindness; CASP3 gene; CASP8 gene; CCL2 gene; CD95 Antigens; CRISPR/Cas technology; Cell Death; Cells; Cessation of life; Chronic; Chronic Disease; Cleaved cell; Complex; Data; Development; Etanercept; Event; Experimental Models; Glaucoma; Goals; Grant; Induction of Apoptosis; Inflammation; Inflammation Mediators; Inflammatory; Interleukin-1 beta; Interleukin-6; Laboratories; Ligand Binding; Link; Literature; Mediating; Microglia; Microspheres; Minocycline; Modeling; Molecular; Mus; Mutant Strains Mice; Optic Disk; Optic Nerve; Pathway interactions; Pharmaceutical Preparations; Play; Point Mutation; Publishing; Research; Retina; Retinal Ganglion Cells; Role; Signal Pathway; Signal Transduction; Site; Testing; Tumor Necrosis Factor Ligand Superfamily Member 6; Work; axon injury; axonal degeneration; chemokine; cytokine; human model; mouse model; neuronal cell body; neuroprotection; neurotoxic; novel strategies; prevent; retinal apoptosis

One important unanswered question in glaucoma is whether apoptosis of retinal ganglion cells (RGCs) and axon degeneration are two separate events mediated by molecularly distinct pathways, or whether they are linked and triggered through a common pathway. Answering this question is critical to developing effective neuroprotective therapies that protect both axons and RGC somas. In support of the idea there are two distinct pathways that mediate axon degeneration and RGC apoptosis, it was demonstrated that deletion of the pro- apoptotic BAX gene blocked apoptosis of RGCs in a mouse model of glaucoma, but did not prevent axon degeneration. There is accumulating evidence that axon degeneration is triggered by axon damage in the optic nerve head, which precedes RGC apoptosis and is linked to microglial activation and neurotoxic inflammation. Therefore, it is possible that blocking inflammation could prevent axon degeneration and subsequent death of RGCs, leaving open the possibility that there is a shared pathway linking axon degeneration and RGC apoptosis. In support of the idea that inflammation may be the shared pathway that links axon degeneration and RGC apoptosis, our laboratory demonstrated previously that blocking the Fas/Fas ligand (FasL) signaling pathway prevents axon degeneration and RGC apoptosis in both inducible and chronic mouse models of glaucoma and this protection coincided with an inhibition of microglia activation and induction of inflammatory mediators. However, since Fas triggers apoptotic and inflammatory pathways, the question remains as to whether blocking inflammation alone would prevent axon degeneration and subsequent RGC apoptosis. The challenge to resolving this issue is the inability to uncouple Fas-mediated inflammation from Fas-mediated apoptosis. However, Fas signaling requires activation of caspase-8 for both apoptosis and inflammation and recent studies examining the molecular mechanism of caspase-8 activation discovered an additional auto- cleavage step that is required for the induction of caspase-8-mediated apoptosis but not required for induction of caspase-8 mediated inflammation. Using this information, a mutant mouse was created (Casp8DA/DA) in which a point mutation in the auto-cleavage site blocked caspase-8-mediated apoptosis, but did not block caspase-8-mediated inflammation. We will use these mice to definitively determine how caspase-8-mediated inflammation and/or apoptosis triggers axon degeneration and RGC apoptosis in glaucoma. We hypothesize that elevated IOP triggers caspase-8-mediated inflammation that acts as a common pathway triggering axon degeneration and RGC apoptosis. This hypothesis will be tested in two aims: (1) Determine whether caspase- 8-mediated apoptosis contributes to axon degeneration and death of RGCs in a microbead-induced mouse model of glaucoma and (2) Demonstrate that Fas-mediated activation of microglia mediates neurotoxic inflammation, axon degeneration, and death of RGCs in the microbead-induced mouse model of glaucoma.

青光眼中一个重要的未解决问题是视网膜神经节细胞（RGC）和 轴突变性是通过分子不同途径介导的两个单独的事件，或者它们是否是 通过公共途径链接并触发。回答这个问题对于发展有效至关重要 保护轴突和RGC SOMAS的神经保护疗法。为了支持这个想法，有两个不同的 介导轴突变性和RGC凋亡的途径，证明了预删除 凋亡Bax基因阻断了小鼠青光眼模型中RGC的凋亡，但并不能阻止轴突 退化。有积极的证据表明轴突变性是由视神经轴损伤触发的 神经头，先于RGC凋亡，与小胶质细胞激活和神经毒性炎症有关。 因此，阻塞炎症可能会防止轴突变性和随后的死亡 RGC，打开了有链接轴突变性和RGC的共享途径的可能性 凋亡。支持炎症可能是连接轴突变性的共同途径的想法 和RGC凋亡，我们的实验室先前证明了阻断FAS/FAS配体（FASL）信号传导 途径可防止诱导和慢性小鼠模型的轴突变性和RGC凋亡 青光眼和这种保护与抑制小胶质细胞活化和诱导炎症相吻合 调解人。但是，由于FAS会触发凋亡和炎症途径，因此仍然存在问题 单独阻断炎症是否会防止轴突变性和随后的RGC凋亡。这 解决此问题的挑战是无法与FAS介导的FAS介导的炎症无关 凋亡。然而，FAS信号传导需要激活caspase-8用于凋亡和炎症，并且 最近检查caspase-8激活分子机制的研究发现了另一种自动 诱导caspase-8介导的细胞凋亡所必需的裂解步骤，但不需要诱导 caspase-8介导的炎症。使用此信息，创建了一个突变鼠标（CASP8DA/DA） 自动切换位点的点突变阻塞了caspase-8介导的凋亡，但没有阻止 caspase-8介导的炎症。我们将使用这些小鼠明确确定caspase-8介导的 炎症和/或凋亡触发青光眼中的轴突变性和RGC凋亡。我们假设 升高的IOP触发了caspase-8介导的炎症，该炎症是触发轴突的常见途径 变性和RGC凋亡。该假设将以两个目的进行检验：（1）确定caspase-是否是否 8介导的凋亡有助于Microbead诱导的小鼠中RGC的轴突变性和死亡 青光眼的模型和（2）表明，FAS介导的小胶质细胞的激活介导神经毒性 RGC在微片引起的青光眼小鼠模型中的炎症，轴突变性和死亡。