Experimental Study On Relation Between Tenascin-C And Stability Of Atherosclerotic Lesion

Experimental Study on Relation Between Tenascin-C and Stability of Atherosclerotic LesionAbstractAcute coronary syndromes mainly result from rupture of a vulnerable coronary atherosclerotic plaque and formation of thrombus. The characteristics of a vulnerable plaque include a large lipid core, an abundance of inflammatory cells and mediators and a thin overlying fibrous cap. It is very important for the structure and intensity of the fibrous cap, as well as the activity of abundant monocyte-macrophages involving in inflammation to effect the stability of plaque. The resistance to rupture depend greatly on fibrous cap's content of fibrillar interstitial collagen. The factors decreasing synthesis and / or increasing breakdown of collagen in the fibrous cap may contribute to weakening of the cap, increasing its vulnerability to rupture. The matrix metalloproteinases (MMPs) may play the main role in digestion of extracellular matrix in the fibrous cap.Tenascin-C is a large extracellular oligomeric matrix glycoprotein. The tenascin-C subunits have a multidomain structure that include epidermal growth factor-, fibronectin type III- and fibrinogen-like repeats. The multidomain structure of the tenascin-C subunit gives rise to the multifunctional properties of tenascin-C. It implicated in cell proliferation, differentiation and migration. Although the distribution of tenascin-C is restricted in adult tissue, there are locally restricted increases in tenascin-C expression during organgenesis, inflammation, tumors as well as healing wounds. In this work, we studied the pattern of tenascin-C expression in rat atherosclerotic lesion. In addition, we investigated the expression of the tenascin-C in cultured rat vascular smooth muscle cells and peritoneal macrophages. Moreover, the effects of tenascin-C on activity of macrophages, the expression and activity of MMP-2, MMP-9 were observed.Methods: (1). The rat atherosclerotic model was established by given a high-Cholesterol diet and injected vitamin D3 in peritoneal. (2). By immunocytochemicalstaining and RT-PCR analysis, the expression of tenascin-C in atherosclerotic lesion and the relationships between the levels of tenascin-C mRNA and aortic atherosclerotic lesion area and tissue cholesterol content were invested. (3). In vitro, the rat vascular smooth muscle cells and peritoneal macrophages were harvested and cultured. Furthermore, the effects of expression of tenascin-C on stimulating factors (such as oxLDL) in these cells were observed. (4). By Western bloU Zymography and Northern blot analysis, we also invested the effects of tenascin-C and fibronectin on activity of peritoneal macrophages, the expression levels and activity of MMP-2, MMP-9 in peritoneal macrophages.Main results: (1). The Wistar rats were given a high-Cholesterol diet and peritoneal injection vitamin D3 for 30 or 90 days (D30 and D90 group). We found the levels of serum total cholesterol (TC), triglyceride (TG), LDL-C and the contents of cholesterol in aortic tissue in these two groups were significantly higher than those in control group (PO.01), and those in D90 group were higher than D30 group. The pathologic observation of aortic atherosclerotic lesion showed that the percentages of atherosclerotic lesion area in aortic intima of D30 and D90 groups were significantly higher than that in control group (2.4?.6%, 4.8?.4% vs 0, PO.001). There were intima thickening and a lot of foam cells infiltration in aortic atherosclerotic lesion. (2). By immunocytochemical staining and RT-PCR analysis, the expression of tenascin-C in protein and mRNA levels was not detected in normal artery, it was strongly expression in aortic atherosclerotic lesion. Spatially, tenascin-C was concentrated in tunica media. In linear correlation analysis, tenascin-C mRNA level in atherosclerotic lesion was closely correlation with plaque area and contents of cholesterol in aortic tissue, respectively(r=0.84, 0.79). (3). oxLDL caused a dose dependent progressive increase in steady-state levels of MMP-9 protei...