Neuroimmunology Group, Netherlands Institute for Neuroscience, An Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands.
Glia. 2013 Nov;61(11):1848-61. doi: 10.1002/glia.22562. Epub 2013 Sep 6.
Little is known about the functional phenotype of microglia in normal appearing white matter (NAWM) of multiple sclerosis (MS), although it may hold valuable clues about mechanisms for lesion development. Therefore, we studied microglia from NAWM obtained post-mortem from controls (n = 25) and MS patients (n = 21) for their phenotype ex vivo and their immune responsiveness in vitro, using a microglia isolation method that omits culture and adherence. By flow cytometry, microglia in MS NAWM displayed elevated CD45 levels and increased size and granularity but were distinct from autologous choroid plexus macrophages by absent or low expression of additional markers, in particular CD206. Flow cytometric analysis of microglia from NAWM of three controls and four MS patients showed alterations in levels of Fc-gamma receptors in MS. In primary microglia from a bigger sample of subjects, analysis of Fc-gamma receptors by quantitative PCR indicated a significant increase in mRNA levels of the inhibitory CD32b isoform in MS NAWM. Despite their changed activation status, microglia from MS NAWM were unresponsive to lipopolysaccharide in vitro. Notably, culture with dexamethasone led to an impaired induction of the inflammation-limiting cytokine CCL18 in microglia from MS NAWM compared with those from control NAWM. Together, these data demonstrate that microglia in MS NAWM are in an alerted state, but display features of immunosuppression. Thus, the activation status of microglia in NAWM of MS patients likely reflects a response to ongoing neuroinflammation, which coincides with upregulation of immunoregulatory molecules to prevent full activation and damage to the vulnerable milieu.
关于多发性硬化症（MS）正常外观白质（NAWM）中微胶质细胞的功能表型知之甚少，尽管它可能为病变发展的机制提供有价值的线索。因此，我们研究了死后取自对照者（n=25）和 MS 患者（n=21）的 NAWM 中的微胶质细胞，以研究其表型，并在体外研究其免疫反应性，使用一种避免培养和黏附的微胶质细胞分离方法。通过流式细胞术，MS NAWM 中的微胶质细胞显示出 CD45 水平升高、体积增大和颗粒度增加，但通过缺乏或低表达其他标记物（特别是 CD206），与自体脉络丛巨噬细胞明显不同。对三名对照者和四名 MS 患者的 NAWM 中微胶质细胞的流式细胞术分析显示，MS 中 Fc-γ受体的水平发生改变。在更大样本量的受试者的原代微胶质细胞中，通过定量 PCR 分析 Fc-γ受体表明，MS NAWM 中抑制性 CD32b 同工型的 mRNA 水平显著增加。尽管其激活状态发生变化，但 MS NAWM 中的微胶质细胞对 LPS 在体外无反应。值得注意的是，与对照者的 NAWM 中的微胶质细胞相比，在 MS NAWM 中培养用地塞米松导致炎症限制细胞因子 CCL18 的诱导受损。这些数据表明，MS NAWM 中的微胶质细胞处于警戒状态，但表现出免疫抑制的特征。因此，MS 患者 NAWM 中微胶质细胞的激活状态可能反映了对持续神经炎症的反应，这与免疫调节分子的上调相吻合，以防止完全激活和对脆弱环境的损害。
