School of Pharmacy, Shanghai Jiao Tong University, Shanghai, P.R. China.
J Alzheimers Dis. 2014;38(1):133-44. doi: 10.3233/JAD-130818.
Microglia and astrocytes in the brain play an important role in the development and progression of Alzheimer's disease (AD). Serum amyloid A (SAA) is a major acute-phase protein produced locally in the brain and colocalizes with senile plaques in AD patients. We investigated whether SAA plays a role in the development of AD. The viability of cultured primary microglia and astrocytes was measured by MTT; cell cycle and apoptosis analysis was also conducted. Cultured microglia and astrocytes were stimulated with 1 μM SAA for different periods of time (2, 4, 6, 12 h) or treated with 1 μM SAA with or without 15 min pretreatment of MAPK or PI3K inhibitors. Total RNA was extracted for qPCR analysis. SAA induced morphological changes of primary microglia but not astrocytes. Interestingly, SAA increased the viability of microglia by inhibiting their apoptosis and reduced the viability of astrocytes by inducing G1 cell cycle arresting. SAA treatment increased the mRNA levels of IL-6, TNF-α, IL12p40, IL23p19, and IL-10, with higher potency in microglia than in astrocytes. However, SAA induced more iNOS mRNA in astrocytes than in microglia. SAA induced these cytokines and iNOS expression by activating the PI3K pathway in both glial cells, but selectively activated the JNK pathway in microglia and the NF-κB pathway in astrocytes. These results suggest that SAA can stimulate a different reactive phenotype in microglia and astrocytes, and SAA regulates cell viability differently in these two glial cells in part through the PI3K pathway.
脑内的小胶质细胞和星形胶质细胞在阿尔茨海默病（AD）的发生和进展中发挥重要作用。血清淀粉样蛋白 A（SAA）是大脑局部产生的主要急性期蛋白，与 AD 患者的老年斑共定位。我们研究了 SAA 是否在 AD 的发生中发挥作用。通过 MTT 测量培养的原代小胶质细胞和星形胶质细胞的活力；还进行了细胞周期和凋亡分析。用 1μM SAA 刺激培养的小胶质细胞和星形胶质细胞不同时间（2、4、6、12 h）或用 1μM SAA 处理，同时用 MAPK 或 PI3K 抑制剂预处理 15 分钟。提取总 RNA 进行 qPCR 分析。SAA 诱导原代小胶质细胞形态发生变化，但不诱导星形胶质细胞。有趣的是，SAA 通过抑制细胞凋亡增加小胶质细胞活力，通过诱导 G1 细胞周期停滞降低星形胶质细胞活力。SAA 处理增加了 IL-6、TNF-α、IL12p40、IL23p19 和 IL-10 的 mRNA 水平，在小胶质细胞中的效力高于星形胶质细胞。然而，SAA 在星形胶质细胞中诱导的 iNOS mRNA 多于小胶质细胞。SAA 通过激活两种神经胶质细胞中的 PI3K 通路诱导这些细胞因子和 iNOS 表达，但在小胶质细胞中选择性地激活 JNK 通路，在星形胶质细胞中激活 NF-κB 通路。这些结果表明，SAA 可以刺激小胶质细胞和星形胶质细胞产生不同的反应表型，并且 SAA 通过部分通过 PI3K 通路以不同的方式调节这两种神经胶质细胞的细胞活力。
