Effects Of LPS On Expression Of PCSK9and LDLR In THP-1Derived Macrophages

ObjectiveIn our study, we investigated the effect of lipopolysaccharide on expression ofPCSK9and LDLR in THP-1derived macrophages, tried to find the variation andregularity of PCSK9and LDLR at the cellular level, and in order to understandwhether PCSK9mediates lipopolysaccharide play a role in the development ofatherosclerosis.MethodsHuman THP-1cells were differentiated into macrophages by160nmol/L PMAtreated. Macrophages were incubated with different concentrations of LPS (0,0.1,1,10,100μg/ml) for different times (0,3,6,12,24h). RT-PCR was coducted to detectPCSK9and LDLR mRNA level. Western blot was conducted to detect PCSK9andLDLR protein level. The PCSK9siRNA were designed and synthesized, thentransfected80nmol/L PCSK9siRNA into THP-1derived macrophages by positiveion liposome Lipofectamine2000. Western blot was conducted to detect LDLRprotein level. Intracellular lipid accumulation was observed by Oil Red O staining.ResultsIn THP-1derived macrophages, LPS increased PCSK9mRNA and proteinexpression. PCSK9was up-regulated with increasing concentration of LPS, while100μg/ml LPS increased significantly. But with increasing concentration of LPS, theexpression of THP-1derived macrophages LDLR protein gradually reduced. ByRT-PCR detected, an early decreased in LDLR mRNA levels (at3and6h), but atlater time points (at12and24h) the expression of LDLR mRNA gradually increased and by24h the expression of LDLR mRNA was slightly more than controls.Transfected PCSK9siRNA into THP-1derived macrophages, compared with LPSalone treated group, and the expression of LDLR protein increased for PCSK9siRNAtreated group and PCSK9siRNA+LPS treated group. The expression of LDLRprotein increased siginificantly for PCSK9siRNA treated group. Oil Red O stainingsuggested that intracellular lipid content for PCSK9siRNA treated group wasincreased siginificantly.Conclusions1. LPS up-regulated the expression of PCSK9mRNA and protein in THP-1derived macrophages; LPS down-regulated the expression of LDLR protein in THP-1derived macrophages, while the expression of LDLR mRNA was variable.2. LPS down-regulated the expression of LDLR via PCSK9in THP-1derivedmacrophages, and effects on lipid phagocytosis.