Studies Of Mast Cells Inhibiting HDL₃-induced Cholesterol Efflux From THP-1macrophage-derived Foam Cells

OBJECTIVE: Mast cells (MCs) are better known for their actions in inflammationallergic reactions. Traditionally interest has centered around the role of MCs in inflammation or allergic disease such as hypersusceptibility, dermatitis, asthma, arthritis. Having understood the atherosclerosis, researchers discover that MCs might be associated with the pathogenesis of atherosclerosis. In human atherosclerotic lesions, degranulated mast cells are found to be present in the close vicinity of cholesterol-loaded macrophage-derived foam cells. In the present study, we investigate whether the MCs caninhibit HDL3 -induced cholesterol efflux from THP-1 macrophage-derived foam cells and its possible reasons.METHODS: MCs, isolated from peritoneal cavities of rats, were stimulated todegranulate with Compound 48/80. The degree of MCs degranulation was determined by measuring the histamine release percentage using luminescence spectrometer. The morphology characters of MCs was detected by microscope, after toluidine blue staining. LDTI were extracted by acetone and purified by reverse-phase HPLC. Tryptase activities in supernatant of MCs were assayed by reacting with substrate BAPNA.After THP-1 macrophage-derived foam cells were incubated in the absence or presence of mast cells supernatant ,leech-derived tryptase inhibitor(LDTI) and HDL3 in 20 hours, the intracellular lipid droplets was observed with oil red O staining, the level of intracellular cholesterol and cholesterol efflux were determined by high performance liquid chromatography (HPLC ) ,and FJ-2107P type liquid scintillater, luminescence spectrometer, respectively. The mRNA expression of ABCA1 was examined by RT-PCR. HDL3 that was treaded with supernatant of mast cells was analyzed by 15% SDS-PAGE under nonreducing conditions and agarose gel electrophoresis.