ABSTRACT
Objective::To clarify the inhibitory effect of essential oil from Alpinia zerumbet rhizome (EOFAZ) on oxidized low-density lipoprotein (ox-LDL)-induced transformation of macrophage into foam cell and explore its possible mechanism. Method::THP-1 monocyte was incubated with 100 μg·L-1 phorbol myristate acetate (PMA) to grow into macrophage, experiment was divided into 4 groups as follows, control group, model group (80 mg·L-1 ox-LDL), EOFAZ at low dose (80 mg·L-1 ox-LDL+ 4 μg·L-1 EOFAZ)and EOFAZ at high dose (80 g·L-1 ox-LDL+ 20 μg·L-1 EOFAZ). Mathye thiazolye telrazliurn (MTT) method was employed to examine the influence of EOFAZ on macrophage viability. Western blot was used to analyze the expression level of cluster of differentiation 36(CD36) and ATP-binding cassette transporter A1(ABCA1) protein in macrophage. Enzyme-linked immunosorbent assay (ELISA) was used to detect cholesteryl ester contents in macrophage. Oil red O staining was applied to determine the accumulation of lipids in macrophage. Result::EOFAZ showed non-toxic effect on macrophage. Compared to control group, macrophage in model group displayed higher level of cholesteryl ester and lipid droplet(P<0.01), as well as significant increasing of CD36 expression (P<0.01), but no effect on ABCA1 expression. EOFAZ notably reduced the contents of lipids and cholesteryl ester(P<0.01), down-regulated expression of CD36 and up-regulated expression of ABCA1 in macrophage in comparison with the model group(P<0.01), indicating that EOFAZ inhibited transformation of macrophage into foam cell. Conclusion::EOFAZ could inhibit ox-LDL-induced transformation of macrophage into foam cell, the underlying mechanism may involves its ability to increase CD36 expression and decrease ABCA1 expression in macrophage.
ABSTRACT
Objective: To explore the effect of astragalus polysaccharide (APS) on oxidized low-density lipoprotein (ox-LDL)-induced lipid metabolism of macrophages and its underlying mechanism. Methods: The small interfering RNA (siRNA) targeting ATP binding cassette transporter A1 (ABCA1) was transfected into RAW 264.7 macrophages. Then the cells were stimulated with various concentrations of APS (20 mg/L, 60 mg/L and 150 mg/L), followed by the incubation with 50 mg/L ox-LDL for 24 h. qRT-PCR and Western blot were used to investigate the expression of ABCA1 mRNA and protein. Oil red O was used to analyze the level of foam cells. Lipid accumulation level was assessed by high performance liquid chromatography. [3H]-cholesterol was used to evaluate cholesterol efflux. Results: APS dose-dependently inhibited ox-LDL-induced formation of macrophage-derived foam cell compared with those in control group (P<0.05). HPLC analysis confirmed that APS attenuated lipid accumulation in a dose-dependent manner based on the decrease in ratio of cholesterol ester (CE)/total cholesterol (TC), concomitant with up-regulation of cholesterol efflux (P<0.05), indicating that APS might inhibit lipid deposition in macrophage by enhancing reverse cholesterol transport. Further more, APS dose-dependently increased ABCA1 mRNA and protein levels (P<0.05). When silencing ABCA1 expression with its specific siRNA, APS-inhibited lipid accumulation was significantly up-regulated, accompanied with the down-regulation of cholesterol efflux (P<0.05). Conclusion: APS may regulate lipid metabolism of macrophages by ABCA1-mediated progress of reverse cholesterol transport. Therefore, this study provides a potential target for the treatment of cardiovascular diseases triggered by vulnerable plaque.