Effects Of Oxidized Low Density Lipoprotein Expression On(Pro)renin Receptors In Human Aortic Smooth Muscle Cells

The pathologic basic of coronary heart disease, cerebro-vascular disease andperipheral arterial disease is atherosclerosis (AS), and research on this topic has beenpopular for more than a decades. This process is mainly characterized by continuousaccumulation of lipid and fibers in the arterial wall, leading to chronic inflammatorycondition of the arterial wall and finally resulting in rupture or acute thrombosis inemergency and acute condition. Moreover, endothelial dysfunction is a majoraetiological factor for AS. In addition to this, proliferation and migration of smoothmuscle cells play a key role in the AS. The researchers accepted that oxidized LDL(ox-LDL) has an important feature in development and progress in AS, resulting inunstable plaque. It is mainly acting through the endothelial injury, leading to foam cellformation, regulating the proliferation of smooth muscle cells, adhesion and aggregationof platelets.Hypertension is another major risk factor for AS and participating in multilevel inthe development and progress of AS, resulting in the functional impairment in the targetorgans. Renin Angiotensin Aldosterone System (RAS) plays a key role in the vasculitisand disease progression. Prorenin receptor [(P)RR] is one of the newly discoveredcomponents of the renin-angiotensin-aldosterone system, has been received a widespread attention in cardiovascular and renal disease in recent years. This receptors bindwith renin and (pro)renin, triggering AngII independent step in RAS system, activatingintracellular signaling pathway, resulting expression of fibrosis gene and eventually leadto target organ damage e.g. hypertension, cardiac fibrosis and arteriosclerosis of kidney(glomerulosclerosis), etc.Preliminary experimental results of our groups identified that (P)RR expression inthe human umbilical vein endothelial cells (HUVECs), can cause endothelialdysfunction and expression of inflammatory cytokines. The mechanisms mentionedabove involve in the disease development and progress in AS. Ox-LDL stimulation can induce abnormal proliferation of smooth muscle cells and migration under thesubintimal layer, which play a major role in the AS. Previous research proved that(P)RR expression in vascular smooth muscle cells and ERK1/2phosphorylation canenhance the excessive proliferation of smooth muscle cells. Therefore, this may berelated to the (P)RR stimulation in AS. But there is no report about the impact of (P)RRexpression of ox-LDL in vascular smooth muscle cells currently.Objectives: This study is to assess the existence of in-vitro (P)RR expression inhuman aortic smooth muscle cells (HASMCs) and effects on (P)RR mRNA and proteinexpression after ox-LDL stimulationMethods:1. In-vitro culture of HASMCs.2. Assessing the existence of (P)RR expression in HASMCs by immunofluorescencetechnique.3.100μg/ml ox-LDL stimulated HASMCs in different time,1,2,4,6,12and24hsub-groups; normal control group was cultured with complete medium for24hours.Real-time quantitative PCR and western blot method was used to detect theexpression of (P)RR in order to determine the ox-LDL stimulation time and toobserve the effect of ox-LDL on the expression of (P)RR in HASMCs.4. HASMCs were stimulated with ox-LDL in different concentration,25,50,100,150,200and300μg/ml sub-groups; normal control group was cultured with completemedium for6hours. Real-time quantitative PCR and western blot method was usedto detect the expression of (P)RR in HASMCs.Results：1.(P)RR was expressed in HASMCs.2.100μg/ml ox-LDL significantly upregulated (P)RR mRNA and protein expression,beginning at2hours after incubation, peaking at6hours and moderately decreasingthereafter but maintaining a level still above that of control.3. Different concentrations of ox-LDL stimulated HASMCs, compared with control,the expression of (P)RR were markedly increased and reached the peak in the groupof50μg/ml, and following the extension of treatment, the effect was not so obvious.Conclusions:1.(P)RR was expressed in HASMCs.2. Ox-LDL upregulate (P)RR mRNA and protein expression in HASMCs in a time dependent order.3. Different concentrations of ox-LDL upregulate (P)RR mRNA and proteinexpression in HASMCs in a concentration dependent order.4. Ox-LDL upregulate the expression of in HASMCs, and this may involve in thedevelopment and progress of AS.