He Wei, Yuan Kaiming, Ji Bin, Han Yuan, Li Jun
Department of Anesthesiology and Perioperative Medicine, Critical Care and Pain Medicine, The Second Affiliated Hospital & Yuying Children Hospital of Wenzhou Medical University, Wenzhou 325027, China.
Ann Transl Med. 2020 Feb;8(4):88. doi: 10.21037/atm.2019.12.147.
Activated microglia induced by amyloid-beta (Aβ) release proinflammatory cytokines that can induce neurotoxicity. High-mobility group box 1 protein (HMGB1) and HMGB1-mediated inflammatory responses have been attributed with memory impairment in patients with Alzheimer's disease (AD). There is accumulating evidence to suggest curcumin is a potent anti-inflammatory polyphenol. However, whether curcumin could effectively inhibit inflammation through the suppression of HMGB1 production or HMGB1-mediated inflammatory responses in Aβ-activated microglia is still unclear.
Primary microglia were prepared from the cerebral cortices of one- to three-day-old Sprague Dawley rats. The microglia were cultured and treated with Aβ 50 µM for 24 h to prove a toxic effect. Curcumin 10 µM was administrated 1 h before Aβ treatment. The levels of HMGB1, interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) in the culture medium were analyzed by ELISA. Western blotting was conducted to assess the expression level of toll-like receptor 4 (TLR4) and the receptor for advanced glycation end products (RAGE). In addition, PC12 cells were treated with conditioned medium from microglia treated with Aβ or Aβ and curcumin, and cell viability was subsequently assessed by MTT.
Curcumin was found to significantly inhibit HMGB1 expression and release in Aβ-stimulated microglia. Pretreatment with curcumin reduced TLR4 and RAGE expression. Proinflammatory cytokines such as IL-1β and TNF-α were also remarkably reduced by curcumin. In addition, curcumin protected neurons from indirect toxicity mediated by Aβ-treated microglia.
Curcumin effectively inhibits Aβ-induced neuroinflammation in microglia, partly by suppressing the expression of HMGB1, TLR4, and RAGE.
由β-淀粉样蛋白（Aβ）诱导激活的小胶质细胞会释放促炎细胞因子，进而诱发神经毒性。高迁移率族蛋白B1（HMGB1）以及HMGB1介导的炎症反应被认为与阿尔茨海默病（AD）患者的记忆障碍有关。越来越多的证据表明姜黄素是一种有效的抗炎多酚。然而，姜黄素是否能通过抑制Aβ激活的小胶质细胞中HMGB1的产生或HMGB1介导的炎症反应来有效抑制炎症，目前仍不清楚。
从1至3日龄的Sprague Dawley大鼠的大脑皮层制备原代小胶质细胞。培养小胶质细胞并用50μM的Aβ处理24小时以证明其毒性作用。在Aβ处理前1小时给予10μM姜黄素。通过酶联免疫吸附测定（ELISA）分析培养基中HMGB1、白细胞介素-1β（IL-1β）和肿瘤坏死因子-α（TNF-α）的水平。进行蛋白质免疫印迹法以评估Toll样受体4（TLR4）和晚期糖基化终产物受体（RAGE）的表达水平。此外，用Aβ或Aβ与姜黄素处理的小胶质细胞的条件培养基处理PC12细胞，随后通过噻唑蓝（MTT）法评估细胞活力。
发现姜黄素可显著抑制Aβ刺激的小胶质细胞中HMGB1的表达和释放。姜黄素预处理降低了TLR4和RAGE的表达。姜黄素还显著降低了IL-1β和TNF-α等促炎细胞因子的水平。此外，姜黄素保护神经元免受Aβ处理的小胶质细胞介导的间接毒性。
姜黄素可有效抑制Aβ诱导的小胶质细胞神经炎症，部分原因是通过抑制HMGB1、TLR4和RAGE的表达。
