Abstract: Objective To investigate the secretion of lysosomal Pro-cathepsin L and its contribution to neuronal apoptosis upon lipopolysaccharide (LPS) stimulation. Methods The effect on the release of Pro-cathepsin L in BV-2 cells upon LPS stimulation was determined by Western blotting. Dopaminergic cell line PC-12 cells were cultured with conditioned medium collected from BV-2 cells upon LPS stimulation, then the activated Caspase-3 expression in PC-12 cells was determined by Western blotting. After combination with Cathepsin L inhibitor (iCL) and LPS, the activated Caspase-3 expression in PC-12 cells was observed. Results The secretion of Pro-cathepsin L was increased significantly at 1 and 3 h upon LPS stimulation in BV-2 cells (P = 0.015, 0.021). Expression of activated Caspase-3 in PC-12 cells co-cultured with conditioned medium collected from BV-2 cells upon LPS stimulation at 1 and 3 h was increased (P = 0.000, for all). However, pretreatment with iCL in BV-2 cells could partially reverse Caspase-3 activation (P = 0.005, 0.001). Conclusion Inflammation increases secretion of Pro-cathepsin L in microglia, which can induce the Caspase-3 activation of neurons, which may participate in the pathogenesis of neurodegenerative diseases.

Key words: Lipopolysaccharides, Microglia, Lysosomes, Cathepsins, Apoptosis, Cells, cultured

摘要： 目的 观察脂多糖刺激对小胶质细胞系BV-2（BV-2细胞）分泌Pro-cathepsin L 和神经元凋亡的影响。方法 通过脂多糖刺激BV-2 细胞产生炎性反应建立炎性细胞模型，Western blotting 法分别观察脂多糖刺激前后BV-2 细胞条件培养液中Pro-cathepsin L 表达水平，以及经Cathepsin L 抑制剂预处理前后多巴胺能神经元细胞系PC-12（PC-12 细胞）活化Caspase-3 表达变化。结果 脂多糖刺激BV-2 细胞1 和3 h 后，Pro-cathepsin L 表达水平显著增加，与刺激前比较差异均有统计学意义（P = 0.015，0.021）。与BV-2 细胞共培养并经脂多糖刺激1 和3 h 后，PC-12 细胞活化Caspase-3 表达水平升高，且显著高于刺激前水平（均P = 0.000）；经Cathepsin L 抑制剂预处理及脂多糖刺激1 和3 h 后，PC-12 细胞活化Caspase-3 表达水平下降，且显著低于单纯脂多糖刺激组（P = 0.005，0.001）。结论 小胶质细胞在炎性反应条件下可向细胞外释放Pro-cathepsin L，促进神经元表达活化型Caspase-3，在神经变性疾病发生发展中发挥重要作用。

关键词: 脂多糖类, 小神经胶质细胞, 溶酶体, 组织蛋白酶类, 细胞凋亡, 细胞, 培养的