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目的观察高脂状态下肺泡Ⅱ型上皮细胞(Alveolar typeⅡepithelial cells,ATⅡ)株A549细胞的脂质蓄积,并探讨炎症对高脂状态下A549细胞脂质蓄积的影响及可能的作用机制。方法将A549细胞分为4组:对照组(不加药物)、高脂组(100μg/ml LDL)、炎症组(300 ng/ml LPS)、联合处理组(100μg/ml LDL+300 ng/ml LPS),处理24 h后,油红O染色观察各组细胞内脂质蓄积情况;Real-time PCR检测固醇调节元件结蛋白2(Sterol regulatory elememnt binding proteins 2,SREBP2)、HMGCoA(3-Hydroxy-3-methlglutary 1 coezyme A)还原酶和低密度脂蛋白受体(Low-density lipoprotein receptor,LDLr)基因mRNA转录水平;Western blot法检测SREBP2、LDLr和三磷酸腺酐结合盒转运体A1(ATP-binding cassette sub-family A member 1,ABCA1)蛋白表达水平。结果联合处理组细胞内脂质蓄积较对照组、高脂组及炎症组严重;与对照组相比,高脂组的SREBP2、HMGCoA还原酶、LDLr基因mRNA转录水平反馈性下调(0.54±0.09)、(0.51±0.06)及(0.34±0.06)倍(P<0.05);联合处理组各基因mRNA转录水平下调程度低于高脂组;SREBP2及LDLr蛋白表达水平的变化趋势与基因转录水平基本一致;与对照组相比,高脂组ABCA1蛋白的表达反馈性上调(2.78±0.38)倍(P<0.01);联合处理组ABCA1蛋白表达上调无高脂组明显。结论炎症可加重高脂状态下肺泡Ⅱ型上皮细胞内的脂质蓄积,其机制可能与炎症干扰SREBP2-LDLr/HMGCoA还原酶通路介导的细胞内脂质稳态有关。
Objective To observe the lipid accumulation of A549 cells in alveolar type Ⅱepithelial cells (AT Ⅱ) in hyperlipidemic rats and to explore the possible mechanism of inflammation on the lipid accumulation of A549 cells in hyperlipidemic state. Methods A549 cells were divided into 4 groups: control group (without drug), high fat group (100μg / ml LDL), inflammation group (300μg / ml LPS) LPS) for 24 h. Oil accumulation was observed by oil red O staining. Sterol regulatory elememnt binding protein 2 (SREBP2), HMGCoA (3-Hydroxy 3-methlglutary 1 coezyme A) mRNA and LDLr mRNA were detected by Western blot. Western blot was used to detect the transcriptional level of SREBP2, LDLr and triadrine-binding cassette transporter A1 (ATP -binding cassette sub-family A member 1, ABCA1) protein expression level. Results Compared with the control group, the lipid accumulation of intracellular lipid in the combined treatment group was more severe than that in the control group, hyperlipidemia group and inflammatory group. Compared with the control group, the transcriptional level of SREBP2, HMGCoA reductase and LDLr mRNA in the hyperlipidemia group was down-regulated (0.54 ± 0.09) , (0.51 ± 0.06) and (0.34 ± 0.06) -folds respectively (P <0.05). The mRNA transcription levels of all the genes in the combined treatment group were lower than those in the high-fat diet group. The changes of SREBP2 and LDLr protein expression levels were basically consistent with those of the gene transcription ; Compared with the control group, the expression of ABCA1 protein in hyperlipidemia group was up-regulated (2.78 ± 0.38) times (P <0.01); ABCA1 protein expression in the combination group was significantly higher than that in the hyperlipidemia group. Conclusions Inflammation can increase the lipid accumulation in alveolar type Ⅱ epithelial cells under hyperlipidemia, and its mechanism may be related to the interference of inflammation in the intracellular lipid homeostasis mediated by SREBP2-LDLr / HMGCoA reductase pathway.