Department of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan; Graduate Institute of Medical Sciences, Taipei Medical University, Taipei, Taiwan.
Graduate Institute of Medical Sciences, Taipei Medical University, Taipei, Taiwan.
Redox Biol. 2023 Aug;64:102786. doi: 10.1016/j.redox.2023.102786. Epub 2023 Jun 15.
Diabetic retinopathy (DR) is a major cause of blindness in adult, and the accumulation of advanced glycation end products (AGEs) is a major pathologic event in DR. Methylglyoxal (MGO), a highly reactive dicarbonyl compound, is a precursor of AGEs. Although the therapeutic potential of metformin for retinopathy disorders has recently been elucidated, possibly through AMPK activation, it remains unknown how metformin directly affects the MGO-induced stress response in retinal pigment epithelial cells. Therefore, in this study, we compared the effects of metformin and the AMPK activator A769662 on MGO-induced DR in mice, as well as evaluated cytotoxicity, mitochondrial dynamic changes and dysfunction in ARPE-19 cells. We found MGO can induce mitochondrial ROS production and mitochondrial membrane potential loss, but reduce cytosolic ROS level in ARPE-19 cells. Although these effects of MGO can be reversed by both metformin and A769662, we demonstrated that reduction of mitochondrial ROS production rather than restoration of cytosolic ROS level contributes to cell protective effects of metformin and A769662. Moreover, MGO inhibits AMPK activity, reduces LC3II accumulation, and suppresses protein and gene expressions of MFN1, PGC-1α and TFAM, leading to mitochondrial fission, inhibition of mitochondrial biogenesis and autophagy. In contrast, these events of MGO were reversed by metformin in an AMPK-dependent manner as evidenced by the effects of compound C and AMPK silencing. In addition, we observed an AMPK-dependent upregulation of glyoxalase 1, a ubiquitous cellular enzyme that participates in the detoxification of MGO. In intravitreal drug-treated mice, we found that AMPK activators can reverse the MGO-induced cotton wool spots, macular edema and retinal damage. Functional, histological and optical coherence tomography analysis support the protective actions of both agents against MGO-elicited retinal damage. Metformin and A769662 via AMPK activation exert a strong protection against MGO-induced retinal pigment epithelial cell death and retinopathy. Therefore, metformin and AMPK activator can be therapeutic agents for DR.
糖尿病性视网膜病变（DR）是成年人失明的主要原因，而晚期糖基化终产物（AGEs）的积累是 DR 的主要病理事件。甲基乙二醛（MGO）是一种高度反应性的二羰基化合物，是 AGEs 的前体。尽管二甲双胍治疗视网膜病变的治疗潜力最近已经阐明，可能是通过 AMPK 激活，但仍不清楚二甲双胍如何直接影响视网膜色素上皮细胞中 MGO 诱导的应激反应。因此，在这项研究中，我们比较了二甲双胍和 AMPK 激活剂 A769662 对小鼠 MGO 诱导的 DR 的影响，并评估了细胞毒性、ARPE-19 细胞中线粒体动态变化和功能障碍。我们发现 MGO 可以诱导线粒体 ROS 产生和线粒体膜电位丧失，但降低 ARPE-19 细胞中的细胞质 ROS 水平。虽然 MGO 的这些作用可以被二甲双胍和 A769662 逆转，但我们证明，减少线粒体 ROS 产生而不是恢复细胞质 ROS 水平有助于二甲双胍和 A769662 的细胞保护作用。此外，MGO 抑制 AMPK 活性，减少 LC3II 积累，并抑制 MFN1、PGC-1α 和 TFAM 的蛋白和基因表达，导致线粒体分裂、线粒体生物发生和自噬抑制。相反，这些 MGO 事件通过 AMPK 依赖性方式被二甲双胍逆转，这一点可以从化合物 C 和 AMPK 沉默的作用中得到证明。此外，我们观察到一种 AMPK 依赖性的上调，即普遍存在于细胞中的糖氧酶 1，它参与 MGO 的解毒。在玻璃体内药物治疗的小鼠中，我们发现 AMPK 激活剂可以逆转 MGO 诱导的棉絮斑、黄斑水肿和视网膜损伤。功能、组织学和光学相干断层扫描分析支持这两种药物对抗 MGO 诱导的视网膜损伤的保护作用。通过 AMPK 激活，二甲双胍和 A769662 对 MGO 诱导的视网膜色素上皮细胞死亡和糖尿病有很强的保护作用。因此，二甲双胍和 AMPK 激活剂可以作为 DR 的治疗药物。
