Abstract:Aim To investigate whether the protein expression of ATP-binding cassette transporter A1 (ABCA1) and the accumulation of lipid could be regulated by the activity of semicarbazide-sensitive amine oxidase (SSAO) in vascular smooth muscle cells (VSMC) derived foam cells treated with lipopolysaccharide(LPS). Methods Vascular smooth muscle cells derived foam cells were exposed to different concentration of LPS along or together with SSAO inhibitor semicarbazide (SEM) for 6 hours. The activity of SSAO and the cellular lipid accumulation were determined by high-performance liquid chromatography analysis. The concentration of glucose in the samples was determined in a glucose oxidase-peroxidase method. Fluorospectrophotometer was used to determine the intracellular or medium H2O2 levels. Cholesterol efflux was determined by FJ-2107P type liquid scintillator. Western blot was used to determine the protein levels of ABCA1. Results The activity of SSAO, glucose consumption, H2O2 production were increased after treated with LPS and these changes can be reversed by SEM completely. The cellular lipid accumulation was increased, while the cellular cholesterol efflux and the protein expression of ABCA1 were decreased in vascular smooth muscle cells derived foam cells but these changes can be reversed by SEM partly. Conclusion LPS can down-regulate the protein expression of ABCA1 and promote the cellular lipid accumulation by up-regulating the activity of SSAO partly in vascular smooth muscle cells derived foam cells.

Abstract:Aim To explore the change of nitric oxide in human umbilical vein endothelial cells induced by different dose of formaldehyde and the mechanisms of the nitric oxide change.Methods Human umbilical vein endothelial cells(hUVECs-12) were cultured in dulbeccos minimum essential medium(DMEM) containing 10% fetal bovine serum.At 80% confluence,cells were washed with D-Hanks fluid and cultured in DMEM containing 1% fetal bovine serum for 24 h.Cells were incubated in the presence or absence(control) of formaldehyde.In order to test the dose-effect of formaldehyde-induced endothelial cells change of nitric oxide,the cells were treated with formaldehyde at the dose of 0.0 μmol/L and 5,10,20,40,80 μmol/L for 24 h respectively.To explore the injuring mechanism of formaldehyde on endothelial cells,hydrogen peroxide(100 μmol/L),a potent free radical,was selected as a positive control;Vitamin C(100 mg/L),an anti-oxidant medicine,was selected as a protective group.After 24 h,the transudation content of lactate dehydregenase was observed by colorimetry reaction,the level of malondialdehyde in supernatant-conditioned media of cells was measured by thiobituric acid reaction(TBA) method,the level of nitric oxide in the culture medium was observed to evaluate the influence feature of formaldehyde by nitrate reductase method,the nitric oxide synthase activity was measured by biochemical method,the protein and mRNA level of inducible nitric oxide synthase and endothelial nitric oxide synthas were examined by immunohistochemistry and RT-PCR approach respectively to elucidate the injuring mechanism.Results Formaldehyde conspicuously inhibited the activity of Endothelial nitric oxide synthas,expression of endothelial nitric oxide synthas protein and endothelial nitric oxide synthas mRNA.Formaldehyde induced the activity of inducible nitric oxide synthase,expression of inducible nitric oxide synthase protein and inducible nitric oxide synthase mRNA,and increased the production of nitric oxide,malondialdehyde and the transudation content of lactate dehydrogenase on Human umbilical vein endothelial cells in dose-dependent manner;Vitamin C inhibited the activity of inducible nitric oxide synthase,expression of inducible nitric oxide synthase protein and inducible nitric oxide synthase mRNA,and increased the activity of endothelial nitric oxide synthas.Conclusion Formaldehyde can conspicuously cause change of nitric oxide on human umbilical vein endothelial cells when the concentration is between 5 and 80 μmol/L.This change is related to reducing the activity and expression of endothelial nitric oxide synthas,and increasing the activity and expression of inducible nitric oxide synthase.