Targeting NAD metabolism to ameliorate bacterial endophthalmitis

项目摘要 细菌性眼内炎是眼球穿通伤后常见的一种威胁视力的并发症。 还有眼科手术。尽管有积极的抗生素和手术干预，但眼内炎往往会导致 部分或完全失明。我们研究的长期目标一直是研究肺炎的病理生物学。 眼内炎和确定潜在的治疗靶点。在我们最近的研究中(PMID：34095879)， 利用转录组学和非靶向代谢组学，我们确定了几条与能量有关的关键途径 金黄色葡萄球菌(SA)眼内炎期间代谢受扰。在这些途径中，我们 发现细菌感染会迅速耗尽小鼠体内的烟酰胺腺嘌呤二核苷酸(NAD)池 视网膜。NAD不仅对线粒体的氧化还原反应至关重要，而且对NAD的代谢产物也是至关重要的 途径也是各种酶(如PAPS、sirtuins和CD38)的底物，以维持细胞 动态平衡。因此，NAD代谢的失调已成为发病机制中的一个促成因素。 几种疾病的症状。然而，它在眼部感染中的作用还没有被研究。在这里，我们建议NAD 耗竭导致生物能量学崩溃，导致受体相互作用的蛋白激酶-3激活。 (RIPK3)介导视网膜细胞死亡。作为支持，我们的初步数据显示，NAD合成通过 SA感染中抢救途径、CD38NADase活性升高及RIPK3/MLKL信号的激活 视网膜和培养的细胞。使用小鼠遗传工具、基因治疗和药理学的组合 干预措施，我们将确定NAD耗尽和恢复救助途径的机制(目标1)， 阐明CD38NADase活性和RIPK3在调节视网膜细胞死亡中的相互作用(目标2)，以及 检验补充NAD前体是否可作为辅助治疗的假说 细菌性眼内炎(目标3)。总而言之，对NAD失调和NAD的机械论见解 这项建议中制定的补充治疗战略可能在该领域产生重大影响，不仅是 关于眼部感染，但也包括其他系统性传染病。

Project Summary Bacterial endophthalmitis is a vision-threatening complication commonly occurring post penetrating eye injuries and ocular surgeries. Despite aggressive antibiotics and surgical interventions, endophthalmitis often results in partial or complete vision loss. The long-term goal of our research has been to study the pathobiology of endophthalmitis and identify potential therapeutic targets for treatment. In our recent study (PMID: 34095879), using transcriptomics and untargeted metabolomics, we identified several key pathways related to energy metabolism being perturbed during Staphylococcus aureus (SA) endophthalmitis. Among these pathways, we found that bacterial infection rapidly depletes the nicotinamide adenine dinucleotide (NAD+) pool in the mouse retina. NAD+ is not only crucial for oxidation-reduction reactions in the mitochondria, but metabolites of the NAD+ pathway also serve as substrates for various enzymes (e.g., PARPs, sirtuins, and CD38) to maintain cellular homeostasis. Thus, dysregulation in NAD+ metabolism has emerged as a contributing factor in the pathogenesis of several diseases. However, its role has not been investigated in ocular infections. Here, we propose that NAD+ depletion causes bioenergetics collapse, leading to the activation of receptor-interacting protein kinase-3 (RIPK3) mediated retinal cell death. In support, our preliminary data show disruption of the NAD+ synthesis via salvage pathway, increased activity of CD38 NADase, and the activation of RIPK3/MLKL signaling in SA-infected retina and cultured cells. Using a combination of mouse genetic tools, gene therapy, and pharmacological interventions, we will determine mechanisms of NAD+ depletion and restoration of salvage pathway (Aim 1), elucidate the crosstalk between CD38 NADase activity and RIPK3 in regulating retinal cell death (Aim 2), and test the hypothesis whether supplementation of NAD+ precursors can be used as an adjunct therapy to treat bacterial endophthalmitis (Aim 3). Collectively, the mechanistic insights on NAD+ dysregulation and NAD+ supplementation treatment strategies developed in this proposal could have a major impact in the field, not only with regards to ocular infections but other systemic infectious diseases as well.