Mechanism Of CD163/TWEAK In The Development Of Atherosclerosis

Objective:Previous studies have shown that CD163 positive macrophages have anti atherosclerotic effect,but the mechanism of its action is not clear.Our study will explore the role and possible mechanism of CD163/TWEAK pathway in the formation of atherosclerosis in mice.Methods:In vivo,The APOE^-/-and wild type（C57/BL6）mice at 8¹0 weeks old were divided into four groups（10 mices in each group）:APOE^-/-fed with normal or western diet groups(APOE^-/-+ND,APOE^-/-+WD),wild type fed with normal or western diet groups（WT+ND,WT+WD）.At the 16th week,plasma lipids level were measured and the aortic lesion area were detected by oil red O staining.The protein levels of CD163 and TWEAK in aortas of each group were detected by Western blot,and the expression and distribution of CD163 and TWEAK in atherosclerotic plaques were identified by immunohistochemistry.In vitro,mouse peritoneal macrophages with Recombinant mouse CD163 protein were used to detect the expression level of TWEAK to investigate whether CD163 is involved in the regulation of TWEAK expression.Results:（1）Compared with WT+ND and WT+WD mice,the cholesterol,triglyceride and LDL levels of APOE^-/-+ND and APOE^-/-+WD mice were significantly higher（P<0.001）,and the HDL level decreased significantly（P<0.001）,but there were no significant difference between the APOE^-/-+ND group and the APOE^-/-+WD group.（2）Aortic oil red O staining showed that both the ratio of aortic lesion area/aortic area,or the ratio of aortic arch plaque area/aortic arch area,were significantly increased in the APOE^-/-mice group（p<0.0001）.（3）The CD163 and TWEAK expression levels in APOE^-/-mice aortas were significantly higher than that in WT mice（P<0.05）.（4）CD163 positive macrophages were located in the plaques where removed from the lipid core,while TWEAK were seen in all parts of atherosclerotic plaques.（5）After separating peritoneal macrophages and extracting protein,the Western blot experiment was performed.The results showed that the extracted peritoneal macrophages did not express CD163,indicating that the macrophage was M1 macrophage,which was consistent with the results of laser confocal scanning microscope.We added exogenous recombinant CD163 protein（0.5ug/ml）into the cells,and the protein expression level of TEWAK decreased significantly（p<0.05）.Conclusion:In the microenvironment of atherosclerosis,the protein level of CD163 and its ligand TWEAK increases significantly,and the CD163 positive macrophages were located in the relatively stable area of plaques where far from the lipid core,while TWEAK was decreased in mouse peritoneal macrophages with Recombinant mouse CD163 protein.Our study suggests that CD163 plays an anti-atherosclerotic role by decreasing the TWEAK expression level.