Chuang Dennis Y, Simonyi Agnes, Cui Jiankun, Lubahn Dennis B, Gu Zezong, Sun Grace Y
Interdisciplinary Neuroscience Program, University of Missouri, Columbia, MO, USA.
Center for Translational Neuroscience, University of Missouri, Columbia, MO, USA.
Neuromolecular Med. 2016 Sep;18(3):415-25. doi: 10.1007/s12017-016-8419-5. Epub 2016 Jun 23.
Microglia play a significant role in the generation and propagation of oxidative/nitrosative stress, and are the basis of neuroinflammatory responses in the central nervous system. Upon stimulation by endotoxins such as lipopolysaccharides (LPS), these cells release pro-inflammatory factors which can exert harmful effects on surrounding neurons, leading to secondary neuronal damage and cell death. Our previous studies demonstrated the effects of botanical polyphenols to mitigate inflammatory responses induced by LPS, and highlighted an important role for cytosolic phospholipase A2 (cPLA2) upstream of the pro-inflammatory pathways (Chuang et al. in J Neuroinflammation 12(1):199, 2015. doi: 10.1186/s12974-015-0419-0 ). In this study, we investigate the action of botanical compounds and assess whether suppression of cPLA2 in microglia is involved in the neurotoxic effects on neurons. Differentiated SH-SY5Y neuroblastoma cells were used to test the neurotoxicity of conditioned medium from stimulated microglial cells, and WST-1 assay was used to assess for the cell viability of SH-SY5Y cells. Botanicals such as quercetin and honokiol (but not cyanidin-3-O-glucoside, 3CG) were effective in inhibiting LPS-induced nitric oxide (NO) production and phosphorylation of cPLA2. Conditioned medium from BV-2 cells stimulated with LPS or IFNγ caused neurotoxicity to SH-SY5Y cells. Decrease in cell viability could be ameliorated by pharmacological inhibitors for cPLA2 as well as by down-regulating cPLA2 with siRNA. Botanicals effective in inhibition of LPS-induced NO and cPLA2 phosphorylation were also effective in ameliorating microglial-induced neurotoxicity. Results demonstrated cytotoxic factors from activated microglial cells to cause damaging effects to neurons and potential use of botanical polyphenols to ameliorate the neurotoxic effects.
小胶质细胞在氧化/亚硝化应激的产生和传播中起重要作用，是中枢神经系统神经炎症反应的基础。在受到脂多糖（LPS）等内毒素刺激后，这些细胞会释放促炎因子，对周围神经元产生有害影响，导致继发性神经元损伤和细胞死亡。我们之前的研究证明了植物多酚减轻LPS诱导的炎症反应的作用，并强调了促炎途径上游的胞质磷脂酶A2（cPLA2）的重要作用（Chuang等人，《神经炎症杂志》12(1):199，2015年。doi:10.1186/s12974-015-0419-0）。在本研究中，我们研究了植物化合物的作用，并评估小胶质细胞中cPLA2的抑制是否与对神经元的神经毒性作用有关。使用分化的SH-SY5Y神经母细胞瘤细胞来测试受刺激的小胶质细胞条件培养基的神经毒性，并使用WST-1测定法评估SH-SY5Y细胞的细胞活力。槲皮素和厚朴酚（但不是花青素-3-O-葡萄糖苷，3CG）等植物化合物可有效抑制LPS诱导的一氧化氮（NO）产生和cPLA2的磷酸化。用LPS或IFNγ刺激的BV-2细胞的条件培养基对SH-SY5Y细胞具有神经毒性。cPLA2的药理抑制剂以及用siRNA下调cPLA2可以改善细胞活力的降低。有效抑制LPS诱导的NO和cPLA2磷酸化的植物化合物也能有效改善小胶质细胞诱导的神经毒性。结果表明，活化的小胶质细胞产生的细胞毒性因子会对神经元造成损害，植物多酚可能具有改善神经毒性作用的潜力。
