Intra- versus extracellular effects of microglia-derived cysteine proteases in a conditioned medium transfer model
Intra- versus extracellular effects of microglia-derived cysteine proteases in a conditioned medium transfer model
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DOI：
10.1111/j.1471-4159.2009.06283.x
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发表时间：
2009-09-01
影响因子：
4.7
通讯作者：
Luebbert, Hermann
中科院分区：
文献类型：
--
作者：
Wendt, Wiebke;Schulten, Roxane;Luebbert, Hermann
激活的小胶质细胞释放炎症介质，对神经元存活和信号传导显示有益或有害的影响。在本研究中，我们证明，暴露于脂多糖导致增加的溶酶体半胱氨酸蛋白酶，组织蛋白酶B，K，S和X，在培养上清液中的小胶质细胞系BV-2。此外，我们观察到的细胞质组分中的组织蛋白酶的上调与脂多糖的刺激。这些细胞的条件培养基对神经母细胞瘤细胞系Neuro 2a有毒性。膜渗透性和膜不渗透性半胱氨酸蛋白酶抑制剂的实验表明，在这种介质转移模型中，阻断细胞外组织蛋白酶对小胶质细胞介导的神经元死亡没有影响。然而，细胞内组织蛋白酶似乎触发神经毒性因子的释放。在脂多糖刺激的BV-2细胞中，细胞内组织蛋白酶的抑制显著减少了小胶质细胞活化，其特征在于不同促炎细胞因子的表达减少，从而降低了培养基的神经毒性作用。半胱氨酸蛋白酶在活化的小胶质细胞中的这种迄今未知的细胞内作用可能将慢性神经炎症与神经变性联系起来。
Activated microglia release inflammatory mediators that display either beneficial or harmful effects on neuronal survival and signaling. In the present study we demonstrate that exposure to lipopolysaccharide leads to an increase in the lysosomal cysteine proteases, cathepsin B, K, S, and X, in culture supernatants of the microglia cell line BV-2. In addition, we observed an up-regulation of cathepsins in the cytoplasmic fraction in response to stimulation with lipopolysaccharide. Conditioned medium from these cells was toxic to the neuroblastoma cell line Neuro2a. Experiments with membrane-permeable and membrane-impermeable cysteine protease inhibitors suggested that blocking extracellular cathepsins had no effect on microglia-mediated neuron death in this medium transfer model. However, intracellular cathepsins seem to trigger the release of neurotoxic factors. In lipopolysaccharide-stimulated BV-2 cells, inhibition of intracellular cathepsins significantly diminished microglial activation characterized by reduced expression of different proinflammatory cytokines, thereby reducing the neurotoxic effects of the medium. This hitherto unknown intracellular effect of cysteine proteases in activated microglia might connect chronic neuroinflammation with neurodegeneration.