Role Of Fibrocytes In The Formation Of Atherosclerosis Induced By High Fat Diet

Background With the improvement of living standard and the popularity of western lifestyle in developing countries, atherosclerosis will be the most deadly reason of causing cardiovascular and cerebrovascular diseases. Therefore, the causes and mechanism of the formation of atherosclerosis were researched, which has clinical value and significance for prevention and treatment of atherosclerosis. The study found that myofibroblasts produce excess collagen and other extracellular matrix components in the formation of atherosclerosis plaque, and collagen and other extracellular matrix components deposition in formation of fibrous cap is considered to be important component in the formation of atherosclerosis plaques and fibrous cap. Recent studies have shown that fibrocytes is an important source of myofibroblasts, which participate in the formation of atherosclerosis. However, the role of fibrocytes in atherosclerosis had been researched rarely. The purpose of this study was to explore role of fibrocytes in formation of atherosclerosis plaque from fibrocytes way, and to help to offer new strategy and thought for prevention and treatment of atherosclerosis. Fibrocytes derived from bone marrow, has a variety of functions and quickly differentiate into myofibroblasts in damaged tissue. Then myofibroblasts product a large number of extracellular matrix, secret angiogenic factors, proinflammatory cytokines, MMPs, growth factor, fibrogenetic factors and other factors, which play an important role in cell migration and proliferation, angiogenesis and tissue remodeling. It has attracted more and more attention. Fibrocytes have been proved to play important roles in various diseases. Recent studies have found that fibrocytes are involved in the formation of atherosclerosis, but the definite role of fibrocytes in the pathogenesis of atherosclerosis is still unclear. Methods Two kinds of high fat diet (A: 78.8% basic feed,12% lard,3.5% cholesterol,0.2% propylthiouracil,5% sugar,0.5% sodium cholate; B:60% basic feed,10% lard,10% yolk powder, white sugar 20%) method were used to feed SD rat to establish model of atherosclerosis. Automatic biochemical analyzer was used to monitor blood lipid (TC, TG, HDL-C and LDL-C level) regularly and HE staining was used to explore abdominal aortic plaque formation in rat model of atherosclerosis. Immunohistochemical method was used to determine the existence of fibrocytes (CD34+, CD45+, Col I+). Enzyme-linked immunosorbent assay (ELISA) was used to observe expression level of Chemotaxis cytokine ligand-12 (CXCL12) and chemotaxis cytokine receptor-4 (CXCR4) in atherosclerosis plaques to estimate its role in fibrocyte migration. Immuno-histochemistry and reverse transcriptase polymerase chain reaction(RT-PCR) were used to analyze role of fibrocyte differentiation into a-smooth muscle actin (a-SMA+) myofibroblast. RT-PCR and Western blotting were used to analyze expression levels of mRNA and protein of extracellular matrix (Col 1), angiogenesis factor (PDGF-A), matrix metalloproteinases (MMP-2), growth factor (TGF-β) and chemokine (MCP-1) to explore role of fibrocyte in the formation of atherosclerosis. Results (1) Two kinds of high fat diet (with VD3) feed in different period have successfully caused atherosclerosis in rats. (2) The positive reaction of CD45+, CD34+ and Col I+ in aorta have been found in rats in both normal model and atherosclerosis model, and the positive reaction is higher in atherosclerosis model rats than in normal model rats. (3) The positive reaction of α-SMA+ myofibroblasts and the expression level of α-SMA+ mRNA in aorta were found to be higher in atherosclerosis model rats than in normal model rats. (4) CXCL12 and CXCR4 in serum in both normal and atherosclerosis rat has been detected by ELISA. (5) Atherosclerosis rat produced higher expression of mRNA and protein of Col I+, PDGF-A, MMP-2, TGF-β and MCP-1 compared with those in normal rat aorta. Conlcusions These findings suggest that two kind of high fat diet (with vitamin D3) were used to feed rats which is ideal way to establish atherosclerosis model, and that the migration, differentiation (differentiate to myofibroblasts) and secretion(Col I, PDGF-A, MMP-2, TGF-β and MCP-1) of fibrocytes may play an important role in the formation of atherosclerosis, which help to offer new strategy and thought for prevention and treatment of atherosclerosis.