ABSTRACT
Objective To evaluate the effect of lipopolysaccharide (LPS) on the expression of ATP-binding cassette transporter A1 (ABCA1) in alveolar macrophage cells of rats.Methods The alveolar macrophage cells of rats NR8383 were seeded in 6-well plates at a density of 1 × 106 cells/ml (2 ml/well) and randomly divided into 6 groups:control group (group C,n =24),0.2 μg/L LPS group (group L0.2,n =12),2.0 μg/L LPS group (group L2.0,n =12),20.0 μg/L LPS group (group L20.0,n =60),200.0 pg/L LPS group (group L200.0,n =12),and 20.0 μg/L LPS + ABCA1 siRNA group (group L20.0 + siRNA,n =12).The cells were routinely cultured in group C.LPS with the final concentrations of 0.2,2.0,20.0 and 200.0μg/L was added to the culture medium in L0.2,L2.0,L20.0 and I200.0 groups,respectively.In group L20.0 + siRNA,siRNA 50 nmol/L was added to the culture medium and 12 h later LPS 20.0 μg/L was added.In group C,6 wells were chosen for determination of ABCA1 mRNA and protein expression.At 24 h of incubation with LPS 0.2,2.0 and 200.0 μg/L,or at 2,6,12 and 24 h of incubation with LPS 20.0 μg/L,6 wells were chosen and the cell suspension was obtained for measurement of ABCA1 mRNA expression (by real-time fluorescent quantitative PCR),and ABCA1 expression (by flow cytometry).At 12 h of incubation with 20.0 μg/L LPS or with 20.0 μg/L LPS + 50 nmol/L siRNA,6 wells were chosen and the cell suspension was obtained for measurement of TLR4 mRNA expression (by real-time fluorescent quantitative PCR) and TLR4 expression (by flow cytometry).Results Compared with group C,the expression of ABCA1 mRNA and protein was significantly down-regulated in L0.2,L2.0,L20.0 and L200.0 groups,and the expression of ABCA1 mRNA and protein was up-regulated in L20.0 and L20.0 + siRNA groups.In L20.0 group,the expression of ABCA1 mRNA and protein was gradually down-regulated with the prolonging time of incubation with LPS.Compared with group L20.0,the expression of TLR4 mRNA and protein was significantly up-regulated in group L20.0 + siRNA.Conclusion LPS can down-regulate the expression of ABCA1 in alveolar macrophage cells of rats,however,ABCA1 can inhibit the synthesis of TLR4.