Effects Of Celastrol On The Atherosclerotic Plaque Formation And Stability In ApoE^-/- Mice

Objective Celastrol (also known as tripterine) is the pentacyclic triterpene monomer, one of the active components extracted from T. wilfordii or other members of the celastraceae (bittersweet) family in China. Recently, celastrol has shown promise as an anti-inflammatory compound in animal models of arthritis, lupus, amyotrophic lateralsclerosis, Parkinson disease, Huntington disease and Alzheimer's disease. It also has anti-inflammatory, anti-oxidative, antiproliferative and induced apoptosis effects against numerous cell lines such as vascular endothelial cells, macrophages and cancer cells. Several molecular mechanisms have been identified for these effects, including gene expression modulation likely mediated through inhibition of NF-κB via TAK1 and IκBαkinase, proteasome inhibition, topoisomerase II inhibition, and heat shock response activation. Nonetheless, direct targets remain elusive.Atherosclerosis is a chronic vascular disease in which inflammation and oxidative stress are commonly implicated as major factors. Early stages of plaque development involve endothelial activation induced by inflammatory cytokines, oxidized low-density lipoprotein (ox-LDL) and/or changes in endothelial shear stress. Chronic inflammation appears to play an important role in the initiation and progression of atherosclerosis.In this study, we investigated the effects of celastrol on the formation and the plaque stability of atherosclerosis in the ApoE gene knockout (ApoE^-/-) mice, and ApoE- /-mice were fed with weatern food (21% fat and 0.21% cholesterol) for 8 weeks and given celastrol by intraperitoneal injection at dose of 2mg. kg-1.d-1 in the last 4 weeks.Methods 8-week old male ApoE^-/-mice were divided randomly into celastrol group (CeT group) and DMSO control group (DMSO group) (n=6 in each group). 8-week old male C57BL/6J mice (C57 group) is normal control (n=6).CeT group were given celastrol. DMSO group and C57 group were only given equivalent amount of dimethyl sulfoxide (DMSO). Plasma lipids were determined by biochemical methods.HE staining of root aorta was used to observe the histomorphological change and measure the area of atherosclerotic plaque.SABC immunohistochemistry analysis was performed to detect the expressions of C-reactive protein(CRP), CD40L, tissue factor(TF), CD68 and smooth muscle cellα-actin in the aortic atherosclerotic lesions in ApoE^-/-mice.The contents of collagen in the aortic atherosclerotic lesions were detected with Picrosirius Red staining.Results Serum TC and LDL-C levels in DMSO group were significantly higer than that in C57 group (P<0.05), while Serum HDL-C level in DMSO group was significantly lower than that in C57 group (P<0.05). Serum TG, HDL-C, and LDL-C levels in CeT group were lower than that in DMSO group (P<0.05). The area of atherosclerotic plaque in CeT group was smaller than that in DMSO group (P<0.05), and the ratio of plaque area/aorta cross section area in CeT group was also less than that inDMSO group (P <0.05). The expression of CRP in the aortic wall and TF, CD40L and CD68 in the atherosclerotic plaque were significantly lower in CeT group compared with DMSO group (P<0.05), while the expression ofα-actin in the atherosclerotic plaque didn't differ significantly both CeT group and DMSO group (P>0.05).The contents of collagen in the atherosclerotic plaque was significantly higher in CeT group compared with DMSO group (P<0.05).Conclusions Celastrol can not only inhibit the development of atherosclerosis but also promote the stability of atherosc1erotic plaque in ApoE^-/-mice probably by inhibiting inflammation, reducing the TF and CD40L production and infiltrating number of macrophages, increasing the amount of collagen in atherosclerotic lesions in ApoE^-/- mice. These observations may provide novel insight into a potential anti-inflammatory and antiatherosclerotic pathway of celastrol.