Effects Of Chemerin And Its Receptor On Proliferation Of Vascular Smooth Muscle Cells In Metabolic Hypertensive Rats

Objective:To investigate the vascular remodeling of thoracic aorta in metabolic hypertensive rat model and to observe the change of chemerin and its receptor expression in vascular smooth muscle cells following vascular remodeling. Subsidiarily, we determine the effects of human recombinant human chemerin protein on proliferation, phenotype and cell cycle in human aortic smooth muscle cells, and to explore the potential role of chemerin and its receptor on vascular remodeling following hypertension.Methods:1After adaptive feeding for one week,16male Wistar rats, age of8weeks, were randomly divided into two groups. The experimental group (n=8) was fed with high-fat, high-salt, and high-sugar diet for26weeks, where as the control group (n=8) was fed with normal basal diet. Body weight, blood pressure, blood glucose, and lipid profile were measured and recorded at week0,4,8,20, and26. At the end of the study (week26), all the animals were sacrificed and the thoracic aortas were quickly obtained. Vascular media thickness, media thickness/lumen diameter ratio, chemerin, and chemerin receptor (CMKLR1) expression were determined with immunohistochemistry. Chemerin and CMKLR1mRNA expression were quantified with qRT-PCR.2Cultured human aortic smooth muscle cells (HA-VSMCs) were exposed with different chemerin concentrations (0.1,1,10,100ug/L). Cell proliferation was determined by MTT assay at each time point (0,12,24,48h). Moreover, HA-VSMCs were exposed with chemerin (100ug/L) and the protein expression of a-SMA, cyclin D1,and cyclin A were examined by western-blot at each time point (0,6,12,24,48h).Results:1After4weeks of high-salt-fat and high-sugar diet, body weight, blood pressure, blood glucose, serum total cholesterol as well as triglycerides in experimental group were significantly higher than the control group while serum high-density lipoprotein levels were significantly lower (all p<0.05). There was no significant difference between the two groups in serum low-density lipoprotein levels (p>0.05). After26weeks, vascular wall thickness, media thickness/lumen diameter ratio, chemerin, and CMKLR1expression in experimental group were significantly higher than those of the control group (p<0.05).2Chemerin stimulated the proliferation of HA-VSMCs in a concentration-and time-dependent manner. When exposed to chemerin (100ug/L), α-SMA protein expression decreased gradually (p<0.05) while cyclin D1protein gradually increased (p<0.05), and cyclin D1protein expression was most obvious at24h. In contrast, cyclin A protein expression did not change significantly.Conclusion:1In metabolic hypertensive rat model, chemerin and its receptor CMKLR1expression were found remarkably higher in the media layer of thoracic aorta.2Human recombinant chemerin protein could promote HA-VSMCs proliferation as well as its phenotypic changes and involved in cell cycle process.