Perivascular Adipose Tissue In Role Of Nicotine Induced Endothelial Cell Lesion

Cigarette smoking is one of the most important risk factors in the development of atherosclerosis.Atherosclerotic disease remains the major cause of death worldwide.Smoking promotes the incidence rate and mortality of atherosclerosis increased 2-6 times.Nicotine is known to be a key active component of cigarette smoke and contributes to vascular dysfunction.Previous research focused on smoking induced vascular endothelial cells(VECs)damage directly.However,there is little research on the relationship between perivascular adipose tissue(PVAT)and VECs.It is still unclear whether dysfunctional PVAT leads to VEC injury.In recent years,with the deepening of the adipose tissue cell research,and the rapid increased incidence of cardiovascular disease,PVAT has becoming the focus,since there is no anatomical barrier between PVAT and adventitia.We research the correlation between PVAT and vascular endothelial cells from nuclear factor-kappa B(NF-?B)pathway and cell apoptosis using nicotine stimulates VECs,PVAT and the co-culture cells in vitro cell culture.To make sure that nicotine could promote the apoptosis of VECs and PVAT could regulate the apoptosis of VECs,while analysis the mechanism.We used a co-culture system of human umbilical vein endothelial cells(HUVECs)and adipocytes to investigate whether nicotine-induced PVAT malfunction could injure HUVECs via the nuclear factor-kappa B(NF-?B)pathway.To make sure that nicotine could promote the injury of VECs,and the related mechanism.Clear the role of PVAT in vascular endothelial injury and atherosclerosis disease.We used 10-6 mol�L-1,10-7 mol�L-1 and 10-8 mol�L-1 nicotine to induce dysfunctional HUVECs and adipocytes.Cell apoptosis was detected by Annexin V-FITC.In addition,we used a novel model to co-culture HUVECs and adipocytes in vitro by the transwell co-culture system.Using 10-6 mol�L-1 nicotine to stimulate the co-culture system,cell apoptosis was detected by the same method.Genes and proteins involved in the nuclear factor kappa B(NF-?B)signaling pathway were detected by qRT-PCR and western blot analysis,respectively.We also investigated the nuclear translocation of NF-?B p65 using immunofluorescence staining.Our results showed that nicotine dose-dependently induces the apoptosis of HUVECs and adipocytes and is associated with the activation of NF-?B signal pathway.The apoptosis of HUVECs induced by 10-6 mol�L-1 nicotine increased significantly compare with the control group(P < 0.01).By contrast,adipocytes were more sensitive with nicotine,the apoptosis of adipocytes under different concentrations increased more than the control group(P < 0.05).And in both gene and protein levels,the expression of IKK? and NF-?B p65 of HUVECs and adipocytes after the treatment of nicotine increased significantly compared with the control groups(P < 0.01;P < 0.01).Meanwhile through the co-culture system,adipocytes promoted the expression of IKK? and NF-?B p65,as well as the translocation of NF-?B p65,and they accelerated the degradation of IkB?,resulting in increased apoptosis of HUVECs compared with that of the single cultured system.In addition,the apoptosis of HUVECs and adipocytes were decreased under PDTC,the inhibitor NF-?B signal pathway(P<0.05).A certain concentration of nicotine could activate the NF-?B pathway,promoting the phosphorylation of the NF-?B,lead to the excessive apoptosis or necrosis of endothelial cells and mature adipose cells.And the adipocytes treated with nicotine might be able to further activate the NF-?B signaling pathway in endothelial cells.Thereby the toxic damage of nicotine in endothelial cells could be increased.Ultimately,the adipocytes treated with nicotine induced the change of the structure and function of the endothelial cells,accelerating the development of atherosclerosis disease.