Inhibitory effects of blocking voltage-dependent potassium channel 1.3 on human monocyte-derived macrophage differentiation into foam cells / 北京大学学报(医学版)

ABSTRACT

Objective: To investigate the expression of voltage-dependent potassium channel 1.3(Kv1.3) mRNA and protein during human monocyte-derived macrophage differentiation into foam cells and its function in foam cell formation. Methods: Human peripheral blood monocytes were isolated from healthy male volunteers by density gradient centrifugation and then by adherent method. The obtained monocytes were cultured for 5 days to differentiate into macrophages. Based on establishment of the human macrophage-derived foam cell model, the expression of Kv1.3 channel was investigated by immunocytochemical staining, reverse transcription-polymerase chain raction (RT-PCR) and Western blot. Furthermore, the effects of rMargatoxin, a Kv 1.3 channel-specific inhibitor, on cholesterol metabolism in macrophages incepting oxidized low density lipoprotein (OxLDL) were studied. Results: After the macrophages co-incubated with 30 mg/L OxLDL at 37 ℃ for 60 hours, the cellular volume obviously enlarged and many red lipid granules were deposited in cytoplasm. The total amount of cholesterol (TC),free cholesterol ( FC ) and cholesterol ester ( CE ) in cells markedly increased and the ratio of CE/TC rose from ( 14.4±6.8) % to (57.9±3.5) % (n=7,P＜0.05). However, the expression of Kv1.3 channel had no significant change. r Margatoxin (0.1 nmol/L and 10 nmol/L) markedly reduced the contents of TC, FC and CE in macrophages and the ratios of CE/TC decreased to (42.8±11.6) % and (22.6±8.0)% , respectively (n=7, P＜0.05). Meanwhile, the red lipid granules deposited in the cytoplasm of macrophages also decreased. Conclusion: These data clearly show that the expression of Ky1.3 channel does not change obviously during human monocyte-derived macrophage differentiation into foam cells and the blocking of it would prevent foam cell formation.