Department of Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
Mol Cell Biochem. 2021 May;476(5):2099-2109. doi: 10.1007/s11010-021-04071-y. Epub 2021 Jan 30.
NADPH oxidase (NOX) is a main producers of reactive oxygen species (ROS) that may contribute to the early pathogenesis of diabetic retinopathy (DR). ROS has harmful effects on endogenous neuro-survival factors brain-derived neurotrophic factor (BDNF) and sirtuin 1 (SIRT1) are necessary for the growth and survival of the retina. The role of NOX isoforms NOX4 in triggering ROS in DR is not clear. Here we determine the protective effects of a plant-derived NOX inhibitor apocynin (APO) on NOX4-induced ROS production which may contribute to the depletion of survival factors BDNF/SIRT1 or cell death in the diabetic retinas. Human retinal Müller glial cells (MGCs) were treated with hypoxia mimetic agent cobalt chloride (CoCl) in the absence or presence of APO. Molecular analysis demonstrates that NOX4 is upregulated in CoCl-treated MGCs and in the diabetic retinas. Increased NOX4 was accompanied by the downregulation of BDNF/SIRT1 expression or in the activation of apoptotic marker caspase-3. Whereas, APO treatment downregulates NOX4 and subsequently upregulates BDNF/SIRT1 or alleviate caspase-3 expression. Accordingly, in the diabetic retina we found a positive correlation in NOX4 vs ROS (p = 0.025; R = 0.488) and caspase-3 vs ROS (p = 0.04; R = 0.428); whereas a negative correlation in BDNF vs ROS (p = 0.009; R = 0.596) and SIRT1 vs ROS (p = 0.0003; R = 0.817) respectively. Taken together, NOX4-derived ROS could be a main contributor in downregulating BDNF/SIRT1 expression or in the activation of caspase-3. Whereas, APO treatment may minimize the deleterious effects occurring due to hyperglycemia and/or diabetic mimic hypoxic condition in early pathogenesis of DR.
烟酰胺腺嘌呤二核苷酸磷酸氧化酶（NOX）是活性氧（ROS）的主要产生者，可能有助于糖尿病性视网膜病变（DR）的早期发病机制。ROS 对内源性神经存活因子脑源性神经营养因子（BDNF）和 SIRT1 有有害影响，视网膜的生长和存活都需要它们。NOX 同工型 NOX4 在 DR 中触发 ROS 的作用尚不清楚。在这里，我们确定了一种植物源性 NOX 抑制剂 apocynin（APO）对 NOX4 诱导的 ROS 产生的保护作用，这可能导致存活因子 BDNF/SIRT1 的耗竭或糖尿病视网膜细胞死亡。在缺氧模拟剂氯化钴（CoCl）存在或不存在 APO 的情况下，用缺氧模拟剂氯化钴（CoCl）处理人视网膜 Müller 胶质细胞（MGC）。分子分析表明，NOX4 在 CoCl 处理的 MGC 中和糖尿病视网膜中上调。NOX4 的增加伴随着 BDNF/SIRT1 表达的下调或凋亡标记物 caspase-3 的激活。然而，APO 处理下调 NOX4，随后上调 BDNF/SIRT1 或减轻 caspase-3 表达。因此，在糖尿病视网膜中，我们发现 NOX4 与 ROS 之间存在正相关（p=0.025；R=0.488），caspase-3 与 ROS 之间存在正相关（p=0.04；R=0.428）；而 BDNF 与 ROS 之间存在负相关（p=0.009；R=0.596），SIRT1 与 ROS 之间存在负相关（p=0.0003；R=0.817）。总之，NOX4 衍生的 ROS 可能是下调 BDNF/SIRT1 表达或激活 caspase-3 的主要原因。然而，APO 治疗可能会最小化由于高血糖和/或糖尿病模拟缺氧条件引起的有害作用，从而在 DR 的早期发病机制中发生。
