IL-1β对脓毒症新生幼鼠胼胝体内少突胶质细胞前体细胞分化成熟的影响

目的:探讨IL-1β对少突胶质细胞前体细胞(OPCs)分化成熟及轴突髓鞘化的影响。方法:将出生1 d的SD幼鼠96只随机分为2组:对照组和脂多糖(LPS)组各48只。LPS组给予腹腔注射1mg/kg LPS,对照组腹腔注射等体积PBS。根据注射后时间分为3 h、24 h、3 d、7 d、14 d、28 d 6个亚组,应用双标免疫组化及Western blotting的方法观察3 h、24 h、3 d、7 d时IL-1β及IL-1受体1(IL-1R1)的表达和14 d、28 d时髓鞘碱性蛋白(MBP)的表达。进行原代OPCs培养将其分为对照组、IL-1β组、IL-1β+IL-1受体拮抗剂(IL-1Ra)组及IL-1Ra组。将其诱导分化3 d后利用免疫荧光及Western blotting比较4组间MBP的表达。结果:与对照组相比,LPS注射后3 h、24h、3 d、7 d幼鼠胼胝体小胶质细胞表达IL-1β明显增加,其受体在OPCs表达增加。LPS注射后14 d、28 d,MBP在胼胝体的表达下降。细胞实验显示原代OPCs培养诱导分化3 d后IL-1β可以抑制MBP的表达,并且可以被IL-1Ra逆转。IL-1β可抑制磷酸化ERK的表达,ERK过表达可逆转IL-1β对MBP的抑制作用。结论:在脓毒症新生幼鼠胼胝体内IL-1β有可能通过抑制ERK通路来抑制OPCs成熟,从而导致脑白质轴突低髓鞘化。

Effects of microglia-derived IL-1β on differentiation of OPCs in corpus callosum of septic neonatal rats

AIM: To explore whether IL-1β inhibits the oligodendrocyte precursor cell (OPCs) differentiation and affects axonal myelination. METHODS: One-day-old SD rats were randomly divided into control group and LPS group (48 rats in each group). The rats in LPS group were intraperitoneally injected with 1 mg/kg LPS. The rats in control group were injected with an equal volume of PBS. The rats in each group were further divided into 3 h, 24 h, 3 d, 7 d, 14 d and 28 d subgroups after injection. The expression of IL-1β and IL-1R₁ in the rat corpus callosum at 3 h, 24 h, 3 d, 7 d was determined by double immunofluorescence and Western blotting. The myelin basic protein(MBP) expression in the rat corpus callosum at 14 d, 28 d after injection was also measured. In vitro, primary OPCs culture was performed and divided into control group, 30 μg/L IL-1β group, 30 μg/L IL-1β+IL-1Ra group and 30 μg/L IL-1Ra group. The expression of MBP in the OPCs induced differentiation for 3 d was observed by double immunofluorescence and Western blotting. RESULTS: The expression of IL-1β and IL-1R₁ in the rat corpus callosum at 3 h, 24 h, 3 d, 7 d after LPS injection was obviously increased and the expression of MBP in the rat corpus callosum at 14 d, 28 d in LPS group was obviously decreased compared with control group in vivo. The level of MBP was significantly decreased after IL-1β treatment for 3 d in vitro. However, IL-1Ra (IL-1R inhibitor) reversed the down-regulation of MBP expression. IL-1β inhibited the expression of p-ERK, ERK over-expression reversed the down-regulation of MBP expression compared with IL-1β group. CONCLUSION: IL-1β inhibits the differentiation of OPCs, which may be involved in ERK pathways, thus leading to axonal hypomyelination in the corpus callosum of septic neonatal rats.