The Role Of High Mobility Group Box B1 In Atherosclerosis And The Effects Of Simvastatin On HMGB1 And Atherosclerosis

Atherosclerosis (AS) is a chronic inflammatory disease. High mobility group box 1 (HMGB1), as an important inflammatory mediator, contributes to the progression of AS. And receptor for advanced glycation end products (RAGE), as a important receptor for HMGB1, also contributes to the development of atherosclerosis. Recent studies suggested that High mobility group box 1 (HMGB1) neutralization or blockade of receptor for advanced glycation end products (RAGE) by soluble RAGE (sRAGE) in apoE deficient mice suppressed atherosclerosis. In addition, it’s approved that statin inhibit lesion RAGE and increase serum sRAGE in type 2 diabetes. However, it remains whether statin suppresses the HMGB1-RAGE axis via mevalonate pathway. So, high fat diet induced AS in apoE deficient mice were used in this study; and there were three groups:control group, simvastatin group and simvastatin+mevalonic acid (SM) group. Obvious atherosclerotic plaques were found in control group. Simvastatin significantly suppressed early atherosclerosis, vascular HMGB1、RAGE and HMGB1-RAGE axis downstream targeting molecules. In addition, simvastatin increased serum sRAGE level. And serum level of sRAGE was negatively correlated with aortic root lesion area. And in SM group, there were completely reverse results compared with simvastatin group. In summary, we demonstrated that simvastatin suppressed vascular HMGB1-RAGE axis and atherosclerosis in apoE-/- mice. Furthermore, we observed that HMGB1 induced activation of HMGB1-RAGE axis in HUVECs, including HMGB1, RAGE and VCAM1 up-regulation. Pre-treatment of simvastatin or anti-RAGE antibody inhibited the effects of HMGB1 on HUVECs. There were no differences. This further proved that simvastatin may suppress activation of HMGB1-RAGE.In conclusion, we proposed that simvastatin suppressed activation of HMGB1-RAGE axis and atherosclerosis in apoE-/- mice via the mevalonate pathway; and the roles of inhibited atherosclerosis by simvastatin may relate to the suppression of HMGB1-RAGE axis in endothelial cell. It needs further studies.Part oneThe role of high mobility group box B1 in atherosclerosis of apoE-/- mice and the effects of simvastatin on HMGBl and atherosclerosisObjective:To demonstrate the effects of simvastatin on HMGB1-RAGE axis and atherosclerosis in apoE-/- mice.Methods:18 male apoE-/- mice, age 5 weeks, were offered high fat diet. At age 8 weeks, mice were randomized to three groups:control group (vehicle), simvastatin (50mg/kg/day) group and simvastatin (50mg/kg/day)+ mevalonic acid (30mg/kg/day) group (SM). All mice were killed at age 11 weeks. Aortic root plaque staining by oil red 0, expression of vascular of inflammatory molecules (HMGB1、RAGE、VCAM1, MCP1 and TF) examination using western blot and serum levels of HMGB1 and RAGE tested by ELISA were performed. In addition, en face of aortic arch examination by SEM and determination of macrophages in lesions using IF were also does.Results:Compared with controls, simvastatin obviously decreased atherosclerotic lesion area and inhibited the expression of vascular HMGB1, RAGE, VCAM1, MCP1 and TF in apoE-/- mice. And, an increase of sRAGE level in serum was observed in simvastatin-treated apoE-/- mice versus controls. And serum sRAGE levels was negatively correlated with serum HMGB1 levels and aortic sinus atherosclerotic lesion area. The serum HMGB1 level was trended to reduced by simvastatin, although the results did not achieve statistical significance. In addition, simvastatin also significantly reduced the number of inflammatory cell adhesion on en face of aortic arch and number of macrophages in lesions. But in SM group, there were completely reverse results compared with simvastatin group, and was similar to control group.Conclusion:simvastatin suppressed HMGB1-RAGE axis and atherosclerosis in apoE-/- mice via the mevalonate pathway. Part twoHMGB1-induced activation of HMGB1-RAGE axis in HUVECs and the effects of simvastatin on HMGB1-induced HUVECObjective:To elucidate the effects of simvastatin on activity of HMGB1-RAGE axis in HMGB1-induced HUVECs.Methods:HUVECs were separated to 5 groups:control group, HMGB1 (100ng/ml) group, anti-RAGE antibody (4ug/ml)+HMGB1 (100ng/ml) group, anti-RAGE antibody (12ug/ml)+HMGB1 (100ng/ml) group and simvastatin(10-5M)+HMGB1 (100ng/ml) Group. After 24 hours treatment, protein was extracted from HUVECs and western-blot was performed to detect the expression of VCAM1, HMGB1 and RAGE. Results:Compared with controls, HMGB1 obviously increased the expression of VCAM1, HMGB1 and RAGE protein in HUVEC; In contrast, simvastatin significantly suppressed the expression of VCAM1, HMGB1 and RAGE induced by HMGB1; and it is similar to the effects of anti-RAGE antibody.Conclusion:RAGE plays a key role during simvastatin-inhibited the activity of HMGB1-RAGE axis induced by HMGB1 in HUVECs.