Ceramide-mediated mitochondrial damage in diabetic retinopathy investigated by novel microfluidic O2 sensing and bio-mimetic electrochemistry

尽管最近在治疗方法上取得了成功，但糖尿病视网膜病变（DR）仍然是一个严重的问题。 导致视力逐渐丧失和失明的主要原因。概念和技术突破 确定治疗这种并发症的新靶点和策略至关重要。我们认为 最近糖尿病患者线粒体功能障碍的证据提供了这样的突破 视网膜病变与来自大型临床试验的数据相结合，表明 脂质异常和DR进展之间的关联，以及神经酰胺 影响线粒体功能 线粒体在细胞代谢中起着基石作用， 线粒体功能可导致病理。事实上，线粒体损伤先于 DR组织病理学异常。 最近的研究表明，神经酰胺和 线粒体功能线粒体已被证明含有许多鞘脂，包括 鞘磷脂和神经酰胺，以及鞘脂途径的酶。神经酰胺诱导 在复合物III水平限制呼吸链功能，以及琥珀酸 已经证明蓄积是局部缺血/再灌注和中风的致病因素， 导致组织损伤。 除了对呼吸酶的影响外，神经酰胺还被证明有助于 线粒体外膜通透性通过S1 P和十六烯醛的产生 和BAX/巴克的激活，或直接通过形成蛋白质可渗透的神经酰胺 线粒体外膜中的通道。这些渠道被证明发挥了关键作用， 通过细胞色素c释放到细胞质中诱导细胞凋亡。我们有 以前证明酸性鞘磷脂酶的激活是一个重要的早期事件， 糖尿病视网膜病变的发病机制。在本提案中，我们将检验总体假设 ASM激活后线粒体神经酰胺水平增加导致a） 细胞色素c释放和细胞凋亡与线粒体呼吸链的B）限制 在糖尿病的REC和RPE细胞中发挥作用。作为传统的极谱或荧光 淬火（海马）方法不利于对有限数量的可用 视网膜组织和细胞，我们正在开发一种新的微流体方法， 线粒体研究。我们将利用这种新的方法来评估ASM的作用 糖尿病视网膜线粒体损伤中的激活和神经酰胺产生。

Despite recent success in treatment approaches, diabetic retinopathy (DR) remains a leading cause of progressive vision loss and blindness. Conceptual and technical breakthroughs to identify novel targets and strategies to cure this complication are paramount. We believe that such a breakthrough is offered by recent evidence of mitochondrial dysfunction in diabetic retinopathy in combination with the data from large clinical trials demonstrating a strong association between lipid abnormalities and DR progression, and the discovery that ceramide affects mitochondrial function. Mitochondria play cornerstone role in cellular metabolism and even slight modification of mitochondrial function can lead to pathology. Indeed, mitochondrial damage precedes histopathological abnormalities in DR. Recent studies demonstrate that there is an intricate connection between ceramide and mitochondrial function. Mitochondria have been shown to contain many sphingolipids including sphingomyelin and ceramide, as well as enzymes of sphingolipid pathway. Ceramide-induced restriction of respiratory chain function at the level of complex III, as well as succinate accumulation has been shown to be a causative factor in ischemia/reperfusion and stroke- induced tissue damage. In addition to effects on respiratory enzymes, ceramides were shown to contribute to mitochondrial outer membrane permeability either through S1P and hexadecenal production and activation of BAX/BAK, or directly through the formation of protein-permeable ceramide channels in mitochondrial outer membranes. These channels are shown to play a key role in the induction of apoptosis through the release of cytochrome c into the cytoplasm. We have previously demonstrated that activation of acid sphingomyelinase is an important early event in the pathogenesis of diabetic retinopathy. In this proposal we will test the overall hypothesis that increased levels of mitochondrial ceramide upon ASM activation leads to a) cytochrome c release and apoptosis and b) restriction on mitochondrial respiratory chain function in REC and RPE cells in diabetes. As traditional polarographic or fluorescence quenching (Seahorse) methods are not conducive for studies on limited amounts of available retinal tissue and cells, we are developing a novel microfluidic method for functional mitochondrial studies. We will utilize this novel methodology to assess the role of ASM activation and ceramide production in mitochondrial damage in diabetic retina.