M2型巨噬细胞衍生外泌体促进小胶质细胞M2型极化

M2 macrophage-derived exosomes promote microglia M2-type polarization

背景:目前对于M2型巨噬细胞衍生外泌体的研究多集中于促进伤口愈合及成骨细胞的增殖和分化,而很少有研究关注其对小胶质细胞表型的调控作用。目的:探讨M2型巨噬细胞衍生外泌体对于小胶质细胞的表型调控作用及分子机制。方法:①提取骨髓原代巨噬细胞,用50 ng/m L白细胞介素4刺激巨噬细胞24 h促进巨噬细胞M2型极化,流式细胞术和细胞免疫荧光鉴定M2型巨噬细胞标志物CD206;②提取和鉴定M2型巨噬细胞衍生外泌体;③将小胶质细胞BV2随机分为3组:对照组、脂多糖组、治疗组,对照组不做处理,脂多糖组加入500 ng/m L脂多糖干预24 h,治疗组同时加入500 ng/m L脂多糖和25μg/m L M2型巨噬细胞衍生外泌体干预24 h,ELISA检测培养上清中肿瘤坏死因子α和白细胞介素10的分泌量,q RT-PCR检测细胞中诱导型一氧化氮合酶、精氨酸酶1、白细胞介素1β和白细胞介素10的m RNA表达,Western blot检测诱导型一氧化氮合酶、精氨酸酶1的蛋白表达以及核因子κB信号通路相关蛋白表达。结果与结论:①ELISA结果显示,与对照组相比,脂多糖组肿瘤坏死因子α分泌明显增多;与脂多糖组相比,治疗组肿瘤坏死因子α的分泌减少而白细胞介素10的分泌增多;②q RT-PCR结果显示,与对照组相比,脂多糖组白细胞介素1β、诱导型一氧化氮合酶m RNA表达升高;与脂多糖组相比,治疗组白细胞介素1β、诱导型一氧化氮合酶m RNA表达降低,白细胞介素10、精氨酸酶1 m RNA表达升高;③Western blot结果显示,与对照组相比,脂多糖组诱导型一氧化氮合酶蛋白表达升高;与脂多糖组相比,治疗组诱导型一氧化氮合酶蛋白表达降低,而精氨酸酶1蛋白表达升高;(4)与对照组相比,脂多糖组核因子κB信号通路中P65、p-IκB-α蛋白表达降低;与脂多糖组相比,治疗组P65、p-IκB-α蛋白表达升高。结果表明:M2型巨噬细胞衍生外泌体可以显著抑制脂多糖诱导小胶质细胞的炎症反应,促进抗炎因子白细胞介素10的表达,抑制促炎因子肿瘤坏死因子α、白细胞介素1β的表达,促进小胶质细胞表型由M1型向M2型极化,其机制可能与M2型巨噬细胞衍生外泌体抑制核因子κB信号通路激活有关。

BACKGROUND:Much of the current research on M2 macrophage-derived exosomes focuses on their effects on wound healing and osteoblast proliferation and differentiation,while few studies have focused on their role in regulating microglia phenotype.OBJECTIVE:To discuss the role and molecular mechanisms of M2 macrophage-derived exosomes in the phenotypic regulation of microglia.MERHODS:(1)Bone marrow primary macrophages were extracted and then stimulated with 50 ng/mL interleukin 4 for 24 hours to promote macrophage M2-type polarization.Flow cytometry and cellular immunofluorescence were used to identify the M2-type macrophage marker CD206.(2)M2 macrophage-derived exosomes were extracted and identified.(3)Microglia BV2 were randomly divided into three groups:control group,lipopolysaccharide group,and treatment group.No treatment was done in the control group.500 ng/mL lipopolysaccharide was added to the intervention for 24 hours in the lipopolysaccharide group.500 ng/mL lipopolysaccharide and 25μg/mL M2 macrophage-derived exosomes were added simultaneously to the treatment group for 24 hours.ELISA was performed to detect the secretion of tumor necrosis factorαand interleukin 10 in the culture supernatant.qRT-PCR was performed to detect the mRNA expression of inducible nitric oxide synthase,arginase 1,interleukin 1β,and interleukin 10 in the cells.Western blot assay was performed to detect the protein expression of inducible nitric oxide synthase,arginase 1,and nuclear factor-κB signaling pathway related protein expression.RESULTS AND CONCLUSION:(1)ELISA results showed that the secretion of tumor necrosis factorαwas significantly increased in the lipopolysaccharide group compared with the control group.The secretion of tumor necrosis factorαwas reduced and the secretion of interleukin 10 was increased in the treatment group compared with the lipopolysaccharide group.(2)The qRT-PCR results showed that compared with the control group,the mRNA expression of interleukin 1βand inducible nitric oxide synthase increased in the lipopolysaccharide group.Compared with the lipopolysaccharide group,the mRNA expression of interleukin 1βand inducible nitric oxide synthase decreased,and the mRNA expression of interleukin 10 and arginase 1 increased in the treatment group.(3)Western blot assay results showed that the expression of inducible nitric oxide synthase protein was increased in the lipopolysaccharide group compared with the control group.The expression of inducible nitric oxide synthase protein was decreased and the expression of arginase 1 protein was elevated in the treatment group compared with the lipopolysaccharide group.(4)Compared with the control group,the expression of p65 and p-IκB-αproteins in the nuclear factor-κB signaling pathway was reduced in the lipopolysaccharide group,whereas the expression of p65 and p-IκB-αproteins was elevated in the treatment group compared with the lipopolysaccharide group.The results showed that M2-type macrophage-derived exosomes could significantly inhibit lipopolysaccharide-induced inflammatory responses in microglia,enhance the expression of the anti-inflammatory factor interleukin 10,suppress the expression of the pro-inflammatory factors tumor necrosis factorαand interleukin 1β,and promote microglial cell phenotypes polarized from the M1-type to the M2-type.The mechanism may be related to the inhibition of nuclear factor-κB signaling pathway activation by M2-type macrophage-derived exosomes.