摘要
在中枢神经系统中,小胶质细胞和星形胶质细胞对神经元的发育、功能维持及细胞存活具有重要的作用。但在炎症反应过程中,星形胶质细胞增生的作用及其对神经元的影响目前并不十分清楚。因此,本研究对不同种类的细胞进行培养,给予细菌脂多糖（lipopolysaccharide,LPS）刺激,观察各种细胞的反应。结果显示,星形胶质细胞可以减轻炎症反应的神经元毒性,提示星形胶质细胞增生主要具有神经保护作用。如果去掉上清液中由星形胶质细胞分泌的胶质细胞源性神经营养因子（glial cell line-derived neurotrophic factor,GDNF）,这种神经保护作用显著降低。为了研究星形胶质细胞的免疫功能,本研究培养了高浓度的星形胶质细胞,并发现LPS不能诱导肿瘤坏死因子（tumor necrosis factor,TNF）-α及诱导型一氧化氮合酶（inducible nitric oxide synthase,iN OS）/一氧化氮（nitric oxide,NO）（iN OS/NO）释放。但如果在培养的高浓度星形胶质细胞中增加0.5%～1%的小胶质细胞,则可以诱导TNF-α及iN OS/NO的释放。这提示小胶质细胞和星形胶质细胞间的相互作用对于LPS诱导星形胶质细胞释放前炎症因子及GDNF是必须的。我们还发现,小胶质细胞释放的TNF-α可以通过旁分泌作用调节星形胶质细胞的神经保护功能。综上所述,本研究结果提示星形胶质细胞可能不会直接被LPS激活,而是通过与小胶质细胞相互作用被激活,释放神经营养因子,减少因炎症反应激活的小胶质细胞释放的毒性物质对神经元的损害作用。
Microglia and astroglia play critical roles in the development, function, and survival of neurons in the CNS. However, under inflammatory conditions the role of astrogliosis in the inflammatory process and its effects on neurons remains unclear. Here, we used several types of cell cultures treated with the bacterial inflammogen LPS to address these questions. We found that the presence of astroglia reduced inflammation-driven neurotoxicity, suggesting that astrogliosis is principally neuroprotective. Neutralization of supernatant glial cell line-derived neurotrophic factor（GDNF） released from astroglia significantly reduced this neuroprotective effect during inflammation. To determine the immunological role of astroglia, we optimized a highly-enriched astroglial culture protocol and demonstrated that LPS failed to induce the synthesis and release of TNF-α and iN OS/NO. Instead we found significant enhancement of TNF-α and iN OS expression in highly-enriched astroglial cultures required the presence of 0.5-1% microglia, respectively. Thus suggesting that microglial-astroglial interactions are required for LPS to induce the expression of pro-inflammatory factors and GDNF from astroglia. Specifically, we found that microglia-derived TNF-α plays a pivotal role as a paracrine signal to regulate the neuroprotective functions of astrogliosis. Taken together, these findings suggest that astroglia may not possess the ability to directly recognize the innate immune stimuli LPS, but rather depend on crosstalk with microglia to elicit release of neurotrophic factors as a counterbalance to support neuronal survival from the collateral damage generated by activated microglia during neuroinflammation.
出处
《神经损伤与功能重建》
2015年第1期50-50,共1页
Neural Injury and Functional Reconstruction
