Department of Neurology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany; Department of Neurology, Medical Faculty, University Duisburg-Essen, Essen, Germany.
Department of Neurology, Medical Faculty, University Duisburg-Essen, Essen, Germany.
Neurosci Lett. 2018 Jan 1;662:136-141. doi: 10.1016/j.neulet.2017.10.023. Epub 2017 Oct 16.
Lysophosphatidic acid (LPA) is a pleiotropic signaling lipid that acts as ligand for at least six specific G-protein coupled receptors. Schwann cells (SC) are known to mainly express the LPA receptor subtype. An emerging body of evidence has linked LPA with injury-induced peripheral nerve demyelination as well as neuropathic pain. However, the molecular mechanisms underlying its demyelinating effect have not been conclusively elucidated. We aimed to decipher the demyelinating effect in vitro as well as in vivo by studying markers of SC differentiation and dedifferentiation: Myelinated dorsal root ganglia (DRG) cultures were treated either with LPA, LPA plus AM095 (LPA antagonist) or vehicle. Myelin content was subsequently investigated by Sudan Black staining and immunocytochemistry. In vivo, we performed sciatic nerve crush in C57BL/6 mice treated with AM095 at 10mg/kg. In DRG cultures, LPA caused a significant reduction of myelin as demonstrated by both Sudan Black staining and immunocytochemical analysis of myelin basic protein. Demyelination was paralleled by an upregulation of TNF-alpha as well as downregulation of Sox10, a marker for SC differentiation. LPA mediated effects were largely blocked by the addition of the LPA receptor antagonist AM095. In the in vivo model, AM095 treatment prior to crush injury increased Sox10 expression in SCs in the distal nerve stump while reducing the number of cells expressing the SC dedifferentiation marker Sox2. Additionally, TNF-alpha immunofluorescence was reduced in CD11b-positive cells. These data indicate that LPA may be a critical factor that shifts SCs towards a post-injury phenotype and contributes to the onset of Wallerian degeneration.
溶血磷脂酸（LPA）是一种具有多种功能的信号脂质，作为至少六种特定 G 蛋白偶联受体的配体。雪旺细胞（SCs）主要表达 LPA 受体亚型。越来越多的证据表明，LPA 与损伤诱导的周围神经脱髓鞘以及神经病理性疼痛有关。然而，其脱髓鞘作用的分子机制尚未得到明确阐述。我们旨在通过研究雪旺细胞分化和去分化的标记物，体外和体内破译脱髓鞘效应：用 LPA、LPA 加 AM095（LPA 拮抗剂）或载体处理有髓背根神经节（DRG）培养物。随后通过苏丹黑染色和免疫细胞化学法研究髓鞘含量。在体内，我们在 C57BL/6 小鼠中进行坐骨神经挤压，并用 10mg/kg 的 AM095 进行治疗。在 DRG 培养物中，LPA 导致髓鞘明显减少，苏丹黑染色和髓鞘碱性蛋白的免疫细胞化学分析均证实了这一点。脱髓鞘与 TNF-α的上调以及 Sox10 的下调平行，Sox10 是雪旺细胞分化的标志物。LPA 介导的作用被添加 LPA 受体拮抗剂 AM095 大大阻断。在体内模型中，挤压损伤前用 AM095 处理可增加远端神经残端 SC 中的 Sox10 表达，同时减少表达 SC 去分化标志物 Sox2 的细胞数量。此外，CD11b 阳性细胞中的 TNF-α免疫荧光减少。这些数据表明，LPA 可能是一种关键因素，可使 SC 向损伤后表型转变，并有助于 Wallerian 变性的发生。
