Role Of P38 Mitogen-Activated Protein Kinaes In Oxidative Stress Response To Vascular Adventitial Injury And Study Of Medication Intervention

【Background and Objective】The pathogenesy of atherosclerosis is very complex.Resently,most people believed that it's a vascular response to mechanical injury,the beginning of AS.Inflammation,migration and proliferation of smooth muscle cells(SMCs),and fibrohyperplasy after vascular injury result in the formation of neointima and vascular remodeling.The p38 mitogen-activated protein kinase(MAPK) pathway has been shown to play an important role in this procedure.The phosphorylation of p38 MAPK was induced by celluar stress,including reactive oxygen species(ROS) and reactive nitrogen species(RNS).ROS act as "second messengers",activating p38 MAPK,regulating the expression of monocyte chemotactic factor,such as VCAM-1,ICAM-1 and MCP-1,and activating the intracellular growth program.Rescent studies suggest that adventitial imflammtion involves in the development of AS. The proliferation and migration of adventitial fibroblast to intima prior to others after sever coronary injury.Both collar and endotoxin infiltrated silk around adventitia could induce intimal hyperplasia.Atherectomy,angioplasty and balloon injury could damage the whole layers of blood vessel and lead to restenosis.However,the mechanism of formation of neointima is unknown.In the present study,we try to prove that,adventitial injury involves in the formation of intimal hyperplasia;the increased production of ROS and sustained activation of p38 MAPK induced by adventitial injury maybe the possible cause of intimal hyperplasia lesion.Atorvastatin and Tongxinluo could suppress the activation of p38 induced by ROS, and inhibit the vascular lesion.【Methods】1.Male New Zealand White rabbit,divied into two groups randomly,one were fed with normal diet(n=6) and another with high fat diet for 4weeks before surgery(n=12). Digestion and blunt dissection injury was performed in the left or right carotid artery adventitia,and sham operations were performed in the opposing artery.After that,they maintained on a normal diet for 2 weeks and a high fat/cholestrol diet for 4 weeks or 12 weeks respectively until the end of the study.To analysis vascular lesion morphology, paraffin sections were stained with Hematoxylin and Eosin and cryotomy sections with Oil Red O.2.A total of 72 male hypercholesterolemic New Zealand White rabbit were divied into three groups,control(n=24),atorvastatin(n=24) and tongxinluo(n=24).They were used for a time course analysis of ROS production by CM-H2DCFDA(6-chloromethyl-2', 7'-dichlorodihydrofluorescein diacetate,acetyl ester),p38 MAPK activation by Western blotting and immunhistochemical staining.Immunolocalization of phosphor-p38 were also performed in these groups.【Results】1.Two weeks after adventitial injury,intimal hyperplasia without lipidoses displayed in injured carotid artery of normal diet groups,while the opposing artry was negative.The NI/medium were 0.28±0.06 vs 0,P＜0.05.TC and LDL-C elevated after 4 weeks of a high fat/cholesterol diet,P＜0.05.Intimal hyperplasia lesion could be observed in adventitial injured carotid arteries of hypercholesterolemic rabbits at 4 weeks,and classical atherosclerotic plaque with lipidoses at 12 weeks.The NI/medium were 1.56±0.14 vs 0.05±0.02(P＜0.05) and 2.02±0.18 vs 0.10±0.05(P＜0.05),respectively.2.The ROS production and p38 MAPK activation was noted at 1 day aider adventitial injury and remained elevated for at least 28 days.The expression of NF kappa B and VCAM-1,the downsteam of p38,were increased sequencely.Long-term treatment(4 weeks) with HMG-CoA reducase inhibitor atorvastain reduced the vascular response to adventitial injury in hypercholesterolemic rabbit.We got similar result with Tongxl.Both groups reduced TC and LDL-C compared with control,that is 14.31±2.23 vs 23.48±2.90 vs 41.50±5.47(P＜0.05),and 7.90±1.63 vs 13.68±5.90 vs 19.64±2.71(P＜0.05), respectively.The NI/medium of these groups were 0.41±0.06 vs 0.49±0.08 vs 1.56±0.14 (P＜0.05).【Conclusions】1.Adventitial injury involves in the formation of intimal hyperplasia;2.The increased production of ROS and sustained activation of p38 MAPK plays an important role in the formation of neointima induced by adventitial injury;3.Inhibit the activation of p38 induced by ROS,could be one of the mechanisms in atorvastatin and Tongxl's antiatherogenic effects.