Department of Neurology, The Fifth Affiliated Hospital of Guangzhou Medical University, 621#Harbour Road, Whampoa District, Guangzhou, 510700, China.
Mol Biol Rep. 2020 Apr;47(4):3233-3240. doi: 10.1007/s11033-020-05324-7. Epub 2020 Feb 24.
Inflammation plays an important role in ischemia-reperfusion injury. Through its antioxidative effects, uric acid can reduce cell injury. However, its mechanism is unknown. This study investigated the protective mechanism of uric acid in cells during ischemia-reperfusion. We divided hippocampal neurons into six groups: the control, OGD, OGD/R, OGD/R + HMGB1 siRNA, OGD/R + uric acid, and OGD/R + uric acid + HMGB1 groups. The MTT assay was used to evaluate cell viability, while apoptosis was detected by flow cytometry. The expression of HMGB1, TLR4, NF-κB-p65 and phosphorylated NF-κB-p65 was detected by Western blotting. The levels of IL-6, IL-1β and TNF-α in the culture medium were determined by ELISA. The results indicated increased cell viability and decreased apoptosis in the presence of HMGB1 siRNA and uric acid but the opposite findings in the presence of HMGB1 protein after OGD/R. Uric acid and HMGB1 siRNA inhibited HMGB1 acetylation to prevent its transport from the nucleus to the cytoplasm. The expression of HMGB1 downstream proteins (TLR4, NF-κB-p65 and phosphorylated NF-κB-p65) and the levels of inflammatory factors in the presence of HMGB1 siRNA and uric acid was lower than those in the presence of HMGB1 protein after OGD or OGD/R. These data indicated that uric acid may prevent cell injury mainly by inhibiting HMGB1 acetylation to regulate TLR4/NF-κB pathways and reduce the levels of inflammatory factors.
炎症在缺血再灌注损伤中起重要作用。尿酸通过其抗氧化作用可以减轻细胞损伤。然而，其机制尚不清楚。本研究探讨了尿酸在缺血再灌注过程中对细胞的保护机制。我们将海马神经元分为六组：对照组、OGD 组、OGD/R 组、OGD/R+HMGB1 siRNA 组、OGD/R+尿酸组和 OGD/R+尿酸+HMGB1 组。MTT 法检测细胞活力，流式细胞术检测细胞凋亡。Western blot 检测 HMGB1、TLR4、NF-κB-p65 和磷酸化 NF-κB-p65 的表达。ELISA 法检测培养基中 IL-6、IL-1β 和 TNF-α 的水平。结果表明，HMGB1 siRNA 和尿酸存在时，细胞活力增加，凋亡减少，而 OGD/R 后 HMGB1 蛋白存在时则相反。尿酸和 HMGB1 siRNA 抑制 HMGB1 乙酰化，防止其从细胞核向细胞质转运。HMGB1 siRNA 和尿酸存在时，HMGB1 下游蛋白（TLR4、NF-κB-p65 和磷酸化 NF-κB-p65）的表达和炎症因子的水平低于 OGD 或 OGD/R 后 HMGB1 蛋白存在时。这些数据表明，尿酸可能主要通过抑制 HMGB1 乙酰化来调节 TLR4/NF-κB 通路，降低炎症因子水平，从而防止细胞损伤。
