背景:已经证明,在神经毒性和神经退行性条件下,反应性星形胶质细胞可以极化为促炎A1表型或抗炎A2表型。已经表明小胶质细胞通过释放促炎和抗炎介质在星形胶质细胞表型极化中起关键作用。在这项研究中,我们研究了三甲基锡(TMT)损伤是否可以诱导小鼠齿状回的星形胶质细胞极化,以及蛋白激酶Cδ(PKCδ)是否在TMT诱导的星形胶质细胞表型极化中起作用。
方法:雄性C57BL/6N小鼠接受TMT(2.6mg/kg,i.p.),评估海马中A1和A2表型标记的mRNA表达的时间变化。此外,在齿状回中检查了C3,S100A10,Iba-1和p-PKCδ蛋白表达的时空变化。Rottlerin(5mg/kg,在TMT治疗后3-5天,以12小时的间隔进行i.p.×5),以及A1和A2转录物的表达,p-PKCδ,在TMT治疗后6天评估Iba-1、C3、S100A10和C1q。
结果:TMT处理显著增加A1和A2表型标记的mRNA表达,A1标记的表达增加比A2标记的表达更长。代表性的A1表型标记的免疫反应性,C3和A2表型标记,S100A10在TMT损伤齿状回后6天达到峰值。虽然C3在整个齿状回中均匀表达,S100A10在hilus和内分子层中高表达。此外,TMT损伤诱导小胶质细胞p-PKCδ表达。用rottlerin治疗,PKCδ抑制剂,Iba-1和C3表达减少,但不影响S100A10的表达,表明PKCδ抑制减弱小胶质细胞活化和A1星形胶质细胞表型极化。始终如一,rottlerin显著降低C1q和肿瘤坏死因子-α(TNFα)的表达,已被认为是由活化的小胶质细胞释放并诱导A1星形胶质细胞极化。
结论:我们证明了TMT损伤小鼠齿状回后星形胶质细胞极化的时间和空间分布。一起来看,我们的结果表明,PKCδ通过促进小胶质细胞活化并因此增加TMT损伤后促炎介质的表达,在诱导A1星形胶质细胞极化中起作用.
BACKGROUND: It has been demonstrated that reactive astrocytes can be polarized into pro-inflammatory A1 phenotype or anti-inflammatory A2 phenotype under neurotoxic and neurodegenerative conditions. Microglia have been suggested to play a critical role in astrocyte phenotype polarization by releasing pro- and anti-inflammatory mediators. In this study, we examined whether trimethyltin (TMT) insult can induce astrocyte polarization in the dentate gyrus of mice, and whether protein kinase Cδ (PKCδ) plays a role in TMT-induced astrocyte phenotype polarization.
METHODS: Male C57BL/6 N mice received TMT (2.6 mg/kg, i.p.), and temporal changes in the mRNA expression of A1 and A2 phenotype markers were evaluated in the hippocampus. In addition, temporal and spatial changes in the protein expression of C3, S100A10, Iba-1, and p-PKCδ were examined in the dentate gyrus. Rottlerin (5 mg/kg, i.p. × 5 at 12-h intervals) was administered 3-5 days after TMT treatment, and the expression of A1 and A2 transcripts, p-PKCδ, Iba-1, C3, S100A10, and C1q was evaluated 6 days after TMT treatment.
RESULTS: TMT treatment significantly increased the mRNA expression of A1 and A2 phenotype markers, and the increased expression of A1 markers remained longer than that of A2 markers. The immunoreactivity of the representative A1 phenotype marker, C3 and A2 phenotype marker, S100A10 peaked 6 days after TMT insult in the dentate gyrus. While C3 was expressed evenly throughout the dentate gyrus, S100A10 was highly expressed in the hilus and inner molecular layer. In addition, TMT insult induced microglial p-PKCδ expression. Treatment with rottlerin, a PKCδ inhibitor, decreased Iba-1 and C3 expression, but did not affect S100A10 expression, suggesting that PKCδ inhibition attenuates microglial activation and A1 astrocyte phenotype polarization. Consistently, rottlerin significantly reduced the expression of C1q and tumor necrosis factor-α (TNFα), which has been suggested to be released by activated microglia and induce A1 astrocyte polarization.
CONCLUSIONS: We demonstrated the temporal and spatial profiles of astrocyte polarization after TMT insult in the dentate gyrus of mice. Taken together, our results suggest that PKCδ plays a role in inducing A1 astrocyte polarization by promoting microglial activation and consequently increasing the expression of pro-inflammatory mediators after TMT insult.