SMS沉默对HepG2细胞炎症和CD14表达的影响

The effects of SMS interference vector on inflammation and expression of CD14 in HepG2 cell

肝细胞的炎性损伤与全身性炎症引起的多器官功能障碍的发生相关,LPS可致全身性炎症,在炎症发生过程中,CD14是LPS的膜受体,可通过激活NF-κB诱导炎症相关因子的表达,CD14主要分布于细胞膜脂筏部位,脂筏是由鞘磷脂(SM)和胆固醇相互锚定,并与相关蛋白质组成的一种微空间结构,因此降低SM的合成,会降低SM在脂筏部位的含量,进而改变脂筏结构及CD14在脂筏部位的分布,最终影响炎症的发生。本研究利用干扰载体pSUPER-SMS沉默HepG2细胞鞘磷脂合酶(SMS)的表达,并检测SM在脂筏部位的含量及CD14和TNF-ɑ的表达,结果显示SMS1和SMS2的mRNA水平表达和酶活都有显著下降(P<0.001,n=3),SM在脂筏部位含量和CD14的表达均有显著降低(P<0.001,n=3),导致LPS所致HepG2细胞TNF-ɑmRNA水平的表达下降。可见SMS可通过改变CD14在脂筏部位的含量,最终影响和炎症发生相关分子TNF-ɑ的表达。

The inflammatory injury of the liver is closely related to multiple organ dysfunction that commonly caused by systemic inflammatory response. Meanwhile,the membrace protein CD14 also has a role in the singal pathway of inflammation that is located in the lipid rafts. Lipid rafts is a certain type of microdomains that is composed by the anchored sphingmyolin（SM） and cholesterol and realated protein, Therefore, the interference vector pSUPER-SMS could be used to knock down expression of SMS, and thus might affect the content of SM,the structure and the distribution of CD14 in lipid rafts. In this study,the pSUPER-SMS was employed to knock down the expression of SMS in HepG2 cells. It was observed that the expression of SMS1 and SMS2 decreased significantly in mRNA levels,with the downregulation of the SMS enzyme activity（P〈0. 001 ,n=3）. The content of SM in lipids raft and the expression of CD14 also showed an obvious decreasing （P〈0. 001, n = 3）. Moreover, the expression of TNF-α was down-regulated in mRNA levels in HepG2 cell that had been pre-treated by LPS. Therefore,the SMS could alter the distribution of CD14 in lipid rafts,and affect the expression of TNF-α that is associated with the occurrence of inflammation.