Abstract

Diabetic retinopathy is one of the major diabetic complications and remains the most common cause of adult blindness among patients with diabetes mellitus. Polygonatum sibiricum polysaccharides (PSP) are a group important component of Polygonatum sibiricum (PS) with anti-diabetic activity. However, the effect and underlying mechanism of PSP on diabetic retinopathy remains unclear. We used high glucose (HG)-stimulated ARPE-19 cells to establish in vitro diabetic retinopathy model. Methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay was performed to evaluate cell viability of ARPE-19 cells. The changes in the ROS production, malondialdehyde (MDA) content, and activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) were detected to indicate oxidative stress. The secretion levels of tumor necrosis factor-alpha (TNF-α) and interleukin-8 (IL-8) were detected by ELISA. The protein levels of TNF-α, IL-8, bcl-2, bax, nuclear Nrf2, and anti-hemeoxygenase-1 (HO-1) were detected by western blot analysis. Our results showed that HG treatment caused a significant reduction in cell viability of ARPE-19 cells. PSP treatment improved the reduced cell viability of ARPE-19 cells. PSP also attenuated HG-induced oxidative stress with decreased ROS production and MDA content, as well as increased the activities of SOD and GPx. In addition, HG significantly increased bax expression and caspase-3 activity, and decreased bcl-2 expression. However, these changes were mitigated by PSP treatment. Furthermore, PSP markedly induced the activation of Nrf2/HO-1 pathway in HG-induced ARPE-19 cells. Knockdown of Nrf2 reversed the protective effects of PSP on HG-induced ARPE-19 cells. Taken together, these findings indicated that PSP protects ARPE-19 cells from HG-induced oxidative stress, inflammation, and cell apoptosis through regulation of Nrf2/HO-1 signaling pathway.

摘要

糖尿病视网膜病变是糖尿病的主要并发症之一，并且仍然是糖尿病患者成人失明的最常见原因。黄精多糖（PSP）是黄精（PS）的一组重要成分，具有抗糖尿病活性。然而，PSP对糖尿病视网膜病变的影响和潜在机制仍不清楚。我们使用高糖 (HG) 刺激的 ARPE-19 细胞建立体外糖尿病视网膜病变模型。进行甲基噻唑基二苯基-溴化四唑(MTT)测定以评估ARPE-19细胞的细胞活力。ROS产生、丙二醛（MDA）含量、超氧化物歧化酶（ SOD）和谷胱甘肽过氧化物酶活性的变化(GPx) 被检测到表明氧化应激。ELISA法检测肿瘤坏死因子-α（TNF-α）和白细胞介素-8（IL-8）的分泌水平。通过蛋白质印迹分析检测 TNF-α、IL-8、bcl-2、bax、核 Nrf2 和抗血氧合酶-1 (HO-1) 的蛋白质水平。我们的结果表明，HG 处理导致 ARPE-19 细胞的细胞活力显着降低。PSP 处理改善了 ARPE-19 细胞降低的细胞活力。PSP 还通过降低 ROS 产生和 MDA 含量以及增加 SOD 和 GPx 的活性来减弱 HG 诱导的氧化应激。此外，HG显着增加bax表达和caspase-3活性，并降低bcl-2表达。然而，这些变化通过 PSP 处理得到缓解。此外，PSP显着诱导了HG诱导的ARPE-19细胞中Nrf2/HO-1通路的激活。敲除 Nrf2 可逆转 PSP 对 HG 诱导的 ARPE-19 细胞的保护作用。总之，这些发现表明 PSP 通过调节 Nrf2/HO-1 信号通路保护 ARPE-19 细胞免受 HG 诱导的氧化应激、炎症和细胞凋亡。