消肿止痛合剂通过抑制TLR4/MyD88/NF-κB信号通路诱导小鼠小胶质细胞的M2极化

Xiaozhong-Zhitong mixture induces M2 polarization of mouse microglia by inhibiting TLR4/MyD88/NF-κB signaling pathway

目的:观察消肿止痛合剂(Xiaozhong-Zhitong mixture,XZZT)对小鼠小胶质细胞(BV2细胞)M2极化和Toll样受体4(Toll-like receptor 4,TLR4)/髓样分化因子88(myeloid differentiation factor 88,MyD88)/核因子κB(nuclear factor-κB,NF-κB)信号通路的影响。方法:将BV2细胞分为空白组、模型组[脂多糖(lipopolysaccharide,LPS)+缺氧]、TAK-242(TLR4抑制剂)组(LPS+缺氧+TAK-242)、XZZT组(LPS+缺氧+XZZT)和TAK-242+XZZT组(LPS+缺氧+TAK-242+XZZT)共5组。流式细胞术检测BV2细胞的早期凋亡及细胞周期;免疫荧光染色检测M1型标志物诱导型一氧化氮合酶(inducible nitric oxide synthase,iNOS)和M2型标志物CD206的阳性表达;Western blot检测TLR4/MyD88/NF-κB信号通路相关蛋白TLR4、MyD88、NF-κB p65、磷酸化p65(phosphorylated p65,p-p65)、磷酸化转化生长因子β活化激酶1(phosphorylated transforming growth factor-β-activated kinase 1,p-TAK1)和磷酸化NF-κB抑制蛋白激酶α/β(phosphorylated IκB kinaseα/β,p-IKKα/β)水平;RT-qPCR检测白细胞介素1β(interleukin-1β,IL-1β)、IL-10、肿瘤坏死因子α(tumor necrosis factor-α,TNF-α)、TLR4、MyD88和NF-κB p65的mRNA表达水平。结果:与模型组相比,XZZT组中BV2细胞早期凋亡率显著降低(P<0.01),生长周期阻滞于S期的细胞比例显著升高(P<0.01),TLR4、MyD88、NF-κB p65、p-IKKα/β、p-p65和p-TAK1蛋白水平显著降低(P<0.05或P<0.01),IL-1β、TNF-α、TLR4、MyD88和NF-κB p65的mRNA表达水平显著降低(P<0.05或P<0.01),IL-10的mRNA表达水平显著升高(P<0.05)。与TAK-242组相比,TAK-242+XZZT组iNOS平均阳性面积百分率显著降低,CD206平均阳性面积百分率显著升高(P<0.01)。结论:XZZT具有诱导小鼠小胶质细胞M2极化的作用,其机制可能与抑制TLR4/MyD88/NF-κB信号通路有关。

AIM:To investigate the effects of Xiaozhong-Zhitong mixture(XZZT)on M2 polarization and Toll-like receptor 4(TLR4)/myeloid differentiation factor 88(MyD88)/nuclear factor-κB(NF-κB)signaling pathway in mouse microglia(BV2 cells).METHODS:The BV2 cells were divided into 5 groups:blank group,model group[lipopolysaccharide(LPS)+hypoxia],TAK-242(resatorvid,a TLR4 inhibitor)group(LPS+hypoxia+TAK-242),XZZT group(LPS+hypoxia+XZZT),and TAK-242+XZZT group(LPS+hypoxia+TAK-242+XZZT).Flow cytometry was used to detect early apoptosis and cell cycle of BV2 cells,and immunofluorescence staining was employed to detect the positive expression of M1-type marker inducible nitric oxide synthase(iNOS)and M2-type marker CD206.Western blot was utilized to detect the expression of TLR4/MyD88/NF-κB signaling pathway-related proteins,including TLR4,MyD88,NF-κB p65,phosphorylated p65(p-p65),phosphorylated transforming growth factor-β-activated kinase 1(p-TAK1),and phosphorylated IκB kinaseα/β(p-IKKα/β).RT-qPCR was used to detect the mRNA expression of interleukin-1β(IL-1β),IL-10,tumor necrosis factor-α(TNF-α),TLR4,MyD88,and NF-κB p65.RESULTS:Compared with model group,the rate of early apoptosis was significantly decreased in XZZT group(P<0.01),the percentage of cells arrested in the S phase was significantly increased(P<0.01),and the protein levels of TLR4,MyD88,NF-κB p65,p-IKKα/β,p-p65,and p-TAK1 were significantly decreased(P<0.05 or P<0.01).Additionally,IL-1β,TNF-α,TLR4,MyD88 and NF-κB p65 mRNA expression levels were significantly decreased(P<0.05 or P<0.01),while IL-10 mRNA expression was significantly increased(P<0.05).Compared with TAK-242 group,the average percentage of iNOS positive area was significantly decreased,while CD206 was significantly increased in TAK-242+XZZT group(P<0.01).CONCLUSION:The XZZT has the effect of inducing M2 polarization of mouse microglia,and the mechanism may be linked to the inhibition of TLR4/MyD88/NF-κB signaling pathway.