Inhibition of reactive oxygen species by Lovastatin downregulates vascular endothelial growth factor expression and ameliorates blood-retinal barrier breakdown in db/db mice: role of NADPH oxidase 4.
Inhibition of reactive oxygen species by Lovastatin downregulates vascular endothelial growth factor expression and ameliorates blood-retinal barrier breakdown in db/db mice: role of NADPH oxidase 4.
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作者：
Li J;Wang JJ;Yu Q;Chen K;Mahadev K;Zhang SX
氧化应激是糖尿病视网膜病变的重要致病因素。我们之前的研究表明洛伐他汀可以减轻db/db小鼠血视网膜屏障（BRB）的破坏。本研究的目的是确定洛伐他汀对糖尿病视网膜病变有益作用的机制。NADPH氧化酶（Nox） 4、血管内皮生长因子（VEGF）、缺氧诱导因子(HIF)-1α的表达；产生活性氧（ROS）；在培养的视网膜毛细血管内皮细胞（RCECs）和洛伐他汀治疗的db/db小鼠中测量视网膜血管通透性。在db/db小鼠视网膜中，Nox4和VEGF的表达显著升高，洛伐他汀治疗后则降低。在培养的RCECs中，缺氧和高糖上调Nox4 mRNA和蛋白表达、ROS生成和VEGF水平。这些变化可通过洛伐他汀或NADPH氧化酶抑制剂二苯二氯铵预处理而消除。Nox4的过表达增加了RCECs中ROS生成、HIF-1α和VEGF表达的基础水平。相反，使用表达显性阴性Nox4的腺病毒阻断Nox4活性，可消除缺氧和高糖诱导的ROS产生和VEGF表达。此外，抑制Nox4可减弱缺氧诱导的HIF-1α上调和高糖诱导的STAT3磷酸化。最后，在db/db小鼠中，腺病毒递送的Nox4小干扰RNA消耗Nox4可显著降低视网膜NADPH氧化酶活性和VEGF表达，并降低视网膜血管的通透性。Nox4的激活在高糖和低氧介导的VEGF表达和糖尿病诱导的BRB分解中起重要作用。抑制Nox4，至少在一定程度上有助于洛伐他汀对糖尿病视网膜病变的保护作用。
Oxidative stress is a key pathogenic factor in diabetic retinopathy. We previously showed that lovastatin mitigates blood-retinal barrier (BRB) breakdown in db/db mice. The purpose of this study is to determine the mechanisms underlying the salutary effects of lovastatin in diabetic retinopathy. Expression of NADPH oxidase (Nox) 4, vascular endothelial growth factor (VEGF), and hypoxia-inducible factor (HIF)-1α; production of reactive oxygen species (ROS); and retinal vascular permeability were measured in cultured retinal capillary endothelial cells (RCECs) and in db/db mice treated with lovastatin. Expressions of Nox4 and VEGF were significantly increased in retinas of db/db mice and reduced by lovastatin treatment. In cultured RCECs, hypoxia and high glucose upregulated mRNA and protein expression of Nox4, ROS generation, and VEGF level. These changes were abrogated by pretreatment with lovastatin or NADPH oxidase inhibitor diphenyleneiodonium chloride. Overexpression of Nox4 increased basal level of ROS generation, HIF-1α, and VEGF expression in RCECs. In contrast, blockade of Nox4 activity using adenovirus-expressing dominant-negative Nox4 abolished hypoxia- and high-glucose–induced ROS production and VEGF expression. Moreover, inhibition of Nox4 attenuated hypoxia-induced upregulation of HIF-1α and high-glucose–elicited phosphorylation of STAT3. Finally, depletion of Nox4 by adenovirus-delivered Nox4 small interfering RNA significantly decreased retinal NADPH oxidase activity and VEGF expression and reduced retinal vascular premeability in db/db mice. Activation of Nox4 plays an important role in high-glucose– and hypoxia-mediated VEGF expression and diabetes-induced BRB breakdown. Inhibition of Nox4, at least in part, contributes to the protective effects of lovastatin in diabetic retinopathy.