Targeting NAD metabolism to ameliorate bacterial endophthalmitis

项目摘要 细菌性眼内炎是眼穿透伤后常见的威胁视力的并发症 和眼部手术尽管积极的抗生素和手术干预，眼内炎往往导致 部分或完全视力丧失。我们研究的长期目标是研究 眼内炎和识别潜在的治疗靶点。在我们最近的研究（PMID：34095879）中， 利用转录组学和非靶向代谢组学，我们确定了几个与能量相关的关键途径， 金黄色葡萄球菌（SA）眼内炎期间代谢受到干扰。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+）库 视网膜。NAD+不仅对线粒体中的氧化还原反应至关重要， 途径还充当各种酶的底物（例如，PARP、沉默调节蛋白和CD 38）来维持细胞内的 体内平衡因此，NAD+代谢失调已成为发病机制中的一个促成因素 几种疾病。然而，其在眼部感染中的作用尚未研究。在这里，我们建议NAD+ 消耗引起生物能量学崩溃，导致受体相互作用蛋白激酶-3的激活 （RIPK 3）介导的视网膜细胞死亡。作为支持，我们的初步数据显示，NAD+合成的中断， SA感染者中CD 38 NAD酶活性增加和RIPK 3/MLKL信号转导激活， 视网膜和培养细胞。使用小鼠遗传工具、基因治疗和药理学的组合， 干预，我们将确定NAD+耗竭和补救途径恢复的机制（目标1）， 阐明CD 38 NAD酶活性和RIPK 3在调节视网膜细胞死亡中的相互作用（Aim 2），和 检验补充NAD+前体是否可用作治疗糖尿病的辅助疗法的假设。 细菌性眼内炎（目的3）。总的来说，关于NAD+调节异常和NAD+ 本提案中制定的补充治疗战略可能在该领域产生重大影响， 除了眼部感染，还有其他全身性感染性疾病。

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.