Understanding metabolic mechanisms underlying retinopathy of prematurity

项目总结/摘要 早产儿出生时肺部发育不全，因此有必要提供 补充氧气以防止死亡。然而，提供的补充氧气是 对发育中的视网膜有害并导致早产儿视网膜病。在子宫内，视网膜血液 血管通过感知缺氧而萌发并从高氧浓度迁移到低氧浓度。 与人类ROP相似，高氧导致小鼠模型中第1阶段血管生长停滞 OIR，随后导致视网膜局部缺氧，并导致新生血管形成， 缺氧稳定缺氧诱导因子（HIF），其导致OIR的分泌。 血管生成生长因子如VEGF。这些生长因子的梯度驱动尖端细胞迁移 和柄细胞增殖。越来越多的证据表明，生长因子 然而，生物合成代谢物也是正常发育所必需的。 血管实验室和其他研究小组的最新发现表明，谷氨酰胺是一种 视网膜内皮细胞增殖所需的重要代谢物。除了谷氨酰胺外， 内皮细胞还具有增强的糖酵解、戊糖磷酸途径和脂肪酸 增殖期间的利用通量。谷氨酰胺仅由Mu氏细胞产生， 视网膜。正常情况下，Müller细胞通过同化氨废物产生谷氨酰胺。我们 最近证明高氧会降低进入三羧酸的糖酵解通量 在视网膜Mu ller细胞中的TCA循环（TCA），因此导致谷氨酰胺的利用增加 通过Mueller细胞和饥饿的视网膜内皮细胞的生长前体。防止血液 OIR第1阶段的血管生长停滞可能会对OIR第2阶段提供保护。我们将 使用OIR抗性和OIR敏感小鼠品系来评估 OIR的第1阶段。已发表的数据和我们的初步数据指向高级脂肪酸 OIR抗性小鼠品系中的代谢通量。我们假设高甘油三酯 水平可以减轻或减少血管增生缺陷完全，通过产生乙酰- 当进入TCA的糖酵解碳减少时，CoA或琥珀酰CoA通过脂肪酸氧化。 这可以另外降低Mu氏细胞对谷氨酰胺的利用，从而节省谷氨酰胺用于 视网膜中的其他细胞。此外，在易感小鼠的饮食中补充 替代脂肪酸作为非氮回补底物可保护敏感菌株 了解OIR抵抗者和OIR抵抗者之间的这些基本代谢差异， OIR敏感菌株将阐明OIR中保护作用的代谢途径 耐药小鼠品系，并可能导致可转化的治疗。

PROJECT SUMMARY/ABSTRACT Premature infants are born with underdeveloped lungs, making it necessary to provide them oxygen supplementation to prevent mortality. However, the supplemental oxygen provided is deleterious to the developing retina and leads to retinopathy of prematurity. In utero, retinal blood vessels sprout and migrate from high oxygen to low oxygen concentrations by sensing hypoxia. Like in human ROP, hyperoxia leads to blood vessel growth arrest in phase 1 in the mouse model of OIR, which subsequently leads to local hypoxia in the retina and causes neovascularization in phase 2 of OIR. Hypoxia stabilizes hypoxia inducible factor (HIF) which leads to the secretion of angiogenic growth factors like VEGF. Gradient of these growth factors drive tip cell migration and stalk cell proliferation. There is a growing body of evidence suggesting that growth factors are guiding cues; however, biosynthetic metabolites are also necessary for normal development of blood vessels. Recent findings from lab and other groups demonstrate that glutamine is an important metabolite needed for retinal endothelial cell proliferation. In addition to glutamine, endothelial cells also have enhanced glycolytic, pentose phosphate pathway and fatty acid utilization fluxes during proliferation. Glutamine is solely produced by the Müller cells in the retina. Müller cells in normal conditions produce glutamine by assimilating ammonium waste. We have recently demonstrated that hyperoxia decreases glycolytic flux entry into tricarboxylic acid cycle (TCA) in the retinal Müller cells, consequently leading to increased utilization of glutamine by Müller cells and starving retinal endothelial cells of their growth precursor. Preventing blood vessel growth arrest in the phase 1 of OIR may provide protection against phase 2 of OIR. We will use OIR resistant and OIR susceptible mice strains to evaluate biosynthetic metabolic pathways in the phase 1 of OIR. Published data and our preliminary data points towards higher fatty acid metabolism flux in the OIR resistant mouse strains. We hypothesize that the higher triglyceride levels may mitigate or diminish blood vessel proliferation defect completely, by producing acetyl- CoA or succinyl-CoA via fatty acid oxidation when glycolytic carbon entry into TCA is decreased. This can additionally lower glutamine utilization by the Müller cells thereby sparing glutamine for other cell types in the retina. Additionally, supplementing diets of the susceptible mouse with alternative fatty acids as non-nitrogenous anaplerotic substrates may protect susceptible strain against OIR. Understanding these basic metabolic differences between an OIR resistant and an OIR susceptible strain will shed light on the metabolic pathways underlying protection in the OIR resistant mouse strain and may lead to translatable treatment.