Vaspin Promotes Macrophage ABCA1 Expression And Cholesterol Efflux Through The NF-?B Pathway In THP-1 Macrophages

Objective: It had been reported that vaspin(a visceral adipose tissue-derived serine protease inhibitor) possessed the characteristic of atheroprotection, but the mechanism was still not fully understood. This study was aimed to investigate whether vaspin up-regulates ATP-binding cassette transporter A1(ABCA1) through NF-?B pathway in THP-1 macrophages.Methods: Human THP-1 monocytes were treated to form foam cells. Then ABCA1 expression was examined after treated with vaspin at different concentrations or incubated with vaspin(100 ng/ml) for different time(0, 6, 12, 24, 48h). Liquid scintillator was used to determine cholesterol efflux detetion. Oil red O staining was used evaluate the cellular lipid droplets. High performance liquid chromatography was performed to evaluate the intracellular total cholesterol, free cholesterol and cholesterol ester content. Western blot was used to determine the level of ABCA1 protein.The ABCA1 mRNA level was examined by RT-PCR. THP-1 macrophages transfected with miR-33 a mimic or anti-mi R-33 a, respectly, and then incubated with LPS for 24 hours, then treated with vaspin for another 24 hours, the levels of ABCA1, miR-33 a and SREBP mRNA were determined.THP-1 macrophage-derived foam cells were pretreated with PDTC(50?M) for 24 hours, and the cells were then incubated with LPS for another 24 hours with or without pretreatement of vaspin, to examine the protein level of NF-?B and ABCA1, the mRNA level of ABCA1 and miR-33 a and the cholesterol efflux detetion.Results: vaspin evidently up-regulated ABCA1 mRNA and protein levels in a time- and dose- dependent manner in THP-1 derived foam cells. Then we investigate the effect of vaspin on miR-33 a, SREBP-2 and NF-?B,the results showed that with vaspin treated, the expression of miR-33 a, SREBP-2 were decreased and the activation of NF-?B was inhibited, also the ABCA1 mRNA and protien expression were increased.Conclusions: Our study provides novel insights into the protective effect of vaspin on enhancing cholesterol efflux via up regulating ABCA1 expression, which is mediated by inhibiting NF-?B signaling pathway and miR-33 expression.