Apolipoprotein M Exerts Anti-oxidative Stress By Upregulating DHCR24 Via SR-B1

Objective:Apolipoprotein M?apoM?is one of the components of high-density lipoprotein?HDL?,and previous studies showed that apoM may inhibit TNF-?-induced IL-1?and MCP-1 expression through DHCR24 pathway.The aim of this study was to investigate whether apoM exerts anti-inflammatory effects through the DHCR24 pathway.Approach:?1?The EA.hy926 cells were transfected with negative control lentivirus and lentivirus carrying apoM gene.The total RNA and total cellular protein were obtained from stable cell lines,and detecting the expression of apoM in the cells were infected with negative control lentivirus(apoM^TgNcell)and lentivirus carrying apoM gene(apoM^Tgcell).?2?The virus-transfected apoM^TgNcells and apoM^Tgcells were subcultured and spreaded into two six-well plates?ie,control and experimental groups?at a density of 6×10⁶ cells/ml,and the control group and the experimental group were treated with PBS and 10 ng/ml TNF-?for 3 h and 6 h respectively after the cells were completely adherent.Then total RNA was extracted to detect mRNA expression levels of SR-B1,DHCR24,IL-1?and MCP-1.?3?The virus-transfected apoM^TgNcells and apoM^Tgcells were subcultured and spreaded uniformly into four six-well plates at a density of 6×10⁶ cells/ml?ie,control groups A and B and experimental groups C and D?.After the cells were completely adherent,control group A,experimental group C and control group B,and experimental group D were treated with absolute ethanol and 10 uM BLT-1?SR-B1 inhibitor?for 12 hours.And then 10 ng/ml TNF-?was added to all the control and experimental groups for6 h.Total RNA was extracted to detect mRNA expression levels of DHCR24,IL-1?,and MCP-1.Results:?1?The expression of apoM mRNA and protein in apoM^Tgcells was significantly higher than that of apoM^TgNgN cells.?2?The expression of SR-B1 and DHCR24 mRNA in apoM^Tgcells was significantly higher than that of apoM^TgNcells under physiological or inflammatory stimuli conditions.The mRNA expression levels of IL-1?and MCP-1 in apoM^Tgcells and apoM^TgNcells were not statistically significant under physiological condition.Under stimulation of inflammation,the mRNA expression of IL-1?and MCP-1 in apoM^Tgcells was significantly lower than that of apoM^TgNcells.?3?The expression level of DHCR24 mRNA in apoM^Tgcells was significantly higher than that in apoM^TgNcells under physiological condition.However the expression of DHCR24 mRNA was significantly decreased in apoM^Tgcells treated with BLT-1 for 12 hours,and the mRNA expression levels of IL-1?and MCP-1 were not statistically significant.Conclusions:ApoM increases the mRNA expression of SR-B1 and DHCR24,and upregulate the expression of DHCR24 through SR-B1 receptor.However,it does not inhibit the expression of IL-1?and MCP-1 induced by TNF-?.In other words,apoM may exert anti-inflammatory effect through other pathways.