Dynamic Alteration Of Peripheral Blood Natural Regulatory T Cells And Lipid And The Expression Of TNF-α In Aortas And Myocardium During The Progression Of Atherosclerosis

Objective:Through animal experiment on dynamic alteration of peripheral blood natural regulatory T cells and lipid and the expression of TNF-α in aortas and myocardium during the progression of atherosclerosis,this study reveal the functions of natural regulatory T cells and lipid and TNF-α in the the progression of atherosclerosis.We study from the following four main pionts:1.The establishment of atherosclerotic model and observation of the formation of atherosclerotic plaque.2.Dynamic alteration of the expression of TNF-αin aortas and myocardium during the progress of atherosclerosis.3.Dynamic alteration of peripheral blood natural regulatory T cells during the progress of atherosclerosis.4.Dynamic alteration of lipid during the progress of atherosclerosis.Methods:48 male SD rats(body weight 100±10g) were randomly divided into two groups,namely healthy control group(C group), atherosclerosis group(A group). Each group has 24 rats. Rats of A group can be established by treating rats with celiac injection of vitamin D3 accompanied by high sucrose-high fat diet to establish atherosclerosis models in this experiment.C group received standard diet.Randomly drawing eight rats in each group were general anesthetized by 20% urethane intraperitoneal injection of 0.5ml/100 g and killed by abdominal aorta bloodletting method on weeks 0,12 and 24 and collected theheart and the aortic roots for experiment specimens.Aortic roots were observed with HE staining for pathological changes.The intimal thickness and inner diameter ratios were calculated by the Image-Pro Plus image analysis system.The expression of TNF-α in the rat aortic roots and myocardium was detected by immunohistochemical assay.The frequencies of CD4+CD25+Foxp3+regulatory T cells in peripheral blood were measured by fluorescence-activated cell sorter(FACS)in each group.Serum lipids of rats were detected by enzymatic colorimetric method.Result:1.There is no plaque in the rats’ aortic roots in Group C at each time point and in Group A at 0 week.There is fibrous plague(i.e.,the early stage of plague)in the rats’ aortic roots in Group A at 12 weeks.There is atheromatous plague(i.e.,the late stage of plague)in the rats’ aortic roots in Group A at 24 weeks.The IT/ID ratios of aortic roots in Group A at12、24 weeks were higher than those in Group A at 0 week and the same-age rats in Group C(P<0.05).The IT/ID ratios of aortic roots in Group A at 24 weeks were a little higher than those in Group A at 12 weeks.There was no statistically significant difference between Group A at 12 weeks and 24 weeks. 2.The expression of TNF-α protein in the rats’ myocardium and aortic roots in Group A at 12 、24 weeks were higher than those in Group A at 0 week and the same-age rats in Group C( P<0.05).There was no statistically significant difference in the expression of TNF-α protein in the rats’ myocardium and aortic roots between Group A at 12 weeks and 24 weeks. 3.Peripheral frequency of CD4+CD25+ Foxp3+ regulatory T cell was decreased in Group A at 12 weeks compared with those in Group A at 0 week 、 24 weeks and the same-age rats in Group C( P<0.05).There was no statistically significant difference in Peripheral frequency of CD4+CD25+ Foxp3+ regulatory T cell between Group A at 0 week and 24 weeks. 4.Serum lipid contents in Group A:The serum levels of TC、TG and HDL in A group at 12、24 weeks were obviously higher than the A group at 0 week(P<0.05).The serum levels of LDL hadan increasing tendency in the three time points.The serum levels of LDL in A group at 24 weeks were obviously higher than the A group at 0、12 weeks(P<0.05).Conclusion:1.It is an effective method for establishing a rat model of atherosclerosis by Celiac injection of vitamin D3 accompanied by high sucrose-high fat diet.Early and late atherosclerotic lesions mainly show a change in the composition of the plaque, but not in intimal hyperplasia. 2.There was no significant difference in the expression of TNF-α and IT/ID ratios between early and late atherosclerotic lesions.This suggests that the pace of progress in the late stage of plague is slower than the early stage. 3.In the early stage of atherosclerosis,peripheral frequency of nTreg was decreased,whereas the expression of TNF-α protein in aortas and myocardium was increased,suggesting an increasing inflammatory response.In the late stage of atherosclerosis,peripheral frequency of nTreg was increased,suggesting an important negative feedback mechanism that results in the attenuation of prolonged or excessive immune responses.The formation of this negative feedback mechanism may have been associated with the regulation of TNF-α. 4.With the development of the AS lesions,blood lipid levels had an increasing tendency. This suggests a close relations between elevated blood lipid and aggravating AS.