红霉素抑制PI3K/Akt通路增加Nrf2蛋白表达减轻烟草烟雾暴露下单核细胞炎性反应的效果研究

Erythromycin inhibits the PI3K/Akt pathway and increases the expression of Nrf2 protein to reduce the inflammatory response of monocytes exposed to cigarette smoke

目的研究红霉素通过抑制PI3K/Akt通路增加Nrf2蛋白表达从而减轻烟草烟雾暴露下单核细胞炎性反应的效果。方法以人单核细胞株(U937)为研究对象,采用烟草烟雾提取物(CSE)制造细胞氧化应激模型,分为空白对照(NC)组、CSE组(CSE刺激细胞)、红霉素组(红霉素预孵育+CSE刺激细胞)、抑制剂组(PI3K通路抑制剂LY294002预孵育+CSE刺激细胞)等4组。根据转染Nrf2-siRNA干扰细胞中Nrf2蛋白的表达,分为siRNA NC对照组、siRNA NC+CSE组、NC+CSE+红霉素组、Nrf2-siRNA组、Nrf2-siRNA+CSE组、Nrf2-siRNA+CSE+红霉素组等6组。采用逆转录-聚合酶链式反应(RT-PCR)检测各组细胞中Akt mRNA、Nrf2 mRNA的表达。采用Western blotting检测各组细胞内Akt、PAkt、Nrf2、核因子(NF)-κB p65蛋白的水平。结果与空白对照组比较,CSE组白细胞介素-8(IL-8)水平明显升高,PAkt及NF-κB p65蛋白的表达水平上升,Nrf2蛋白及Nrf2 mRNA的表达水平下降。红霉素组和抑制剂组IL-8水平较CSE组下降,PAkt及NF-κB p65蛋白的表达水平下降,Nrf2蛋白及Nrf2 mRNA的表达水平有所升高。不同细胞氧化应激模型组Akt mRNA水平比较差异无统计学意义(P>0.05)。Nrf2-siRNA组Nrf2的表达水平较siRNA NC组明显降低,但与Nrf2-siRNA+CSE组、Nrf2-siRNA+CSE+红霉素组比较无明显差异;siRNA NC-CSE组Nrf2表达水平下降,而NC-CSE+红霉素组表达水平上升;siRNA NC-CSE组及Nrf2-siRNA+CSE组NF-κB p65及PAkt表达水平上升,但siRNA NC-CSE+红霉素组、NC-CSE+红霉素组表达水平下降。Nrf2-siRNA组与siRNA NC组NF-κB p65及PAkt表达水平无明显差异。不同干扰组间Akt蛋白的表达水平无明显差异。结论红霉素可通过抑制PI3K/Akt通路增加Nrf2蛋白的表达减轻烟草烟雾暴露下单核细胞的炎性反应。

Objective To study the effect of erythromycin on reducing the inflammatory response of monocytes exposed to cigarette smoke by inhibiting the phosphatidylin-ositol-3-kinase(PI3K)/Akt pathway and increasing the expression of nuclear factor-erythroid 2-related factor 2(Nrf2)protein.Methods Taking human monocyte cell line(U937)as the research object,the cell oxidative stress model was made by using cigarette smoke extract(CSE),the cells were divided into four groups:the normal control(NC)group,the CSE group(CSE stimulated cells),the erythromycin group(erythromycin pre-incubation+CSE stimulated cells),and the inhibitor group(PI3K pathway inhibitor LY294002 pre-incubated+CSE stimulated cells).According to the expression of Nrf2 protein in cells transfected with Nrf2-siRNA interference,the cells were divided into the siRNA NC group,the siRNA NC+CSE group,the NC+CSE+erythromycin group,the Nrf2-siRNA group,the Nrf2-siRNA+CSE group,the Nrf2-siRNA+CSE+erythromycin group.The expressions of Akt mRNA and Nrf2 mRNA in the cells of each group were detected by reverse transcription-polymerase chainreaction(RT-PCR).The levels of Akt,phosphorylated-Akt(PAkt),Nrf2,nuclear factor kappa-B(NF-κB)p65 protein in each group were detected by Western blotting.Results Compared with the blank control group,the interleukin-8(IL-8)level in the CSE group was significantly increased,the expression levels of PAkt and NF-κB p65 proteins were increased,and the expression levels of Nrf2 protein and Nrf2 mRNA were decreased.Compared with the CSE group,the IL-8 level in the erythromycin group and the inhibitor group decreased,the expression levels of PAkt and NF-κB p65 protein decreased,and the expression levels of Nrf2 protein and Nrf2 mRNA increased.There was no significant difference in Akt mRNA levels in different cell oxidative stress model groups(P>0.05).The expression level of Nrf2 in Nrf2-siRNA group was significantly lower than that in siRNA NC group,but there was no significant difference compared with Nrf2-siRNA+CSE group and Nrf2-siRNA+CSE+erythromycin group.The expression level of Nrf2 decreased in the siRNA NC-CSE group,but increased in the NC-CSE+erythromycin group.The expression levels of NF-κB p65 and PAkt increased in siRNA NC-CSE group and Nrf2-siRNA+CSE group,but decreased in siRNA NC-CSE+erythromycin group and NC-CSE+erythromycin group.There was no significant difference in the expression levels of NF-κB p65 and PAkt between Nrf2-siRNA group and siRNA NC group.There was no significant difference in the expression level of Akt protein among different interference groups.Conclusion Erythromycin can reduce the inflammatory response of monocytes exposed to cigarette smoke by inhibiting the PI3K/Akt pathway and increasing the expression of Nrf2 protein.