| Objective: AS is a complex chronic disease and the major cause of cerebrovascular disease.Cerebrovascular disease is one of the most common fatal and disabled diseases in the society of today.But so far,the pathogenesis of AS is not yet clear.In recent years,we tend to consider that AS is a chronic inflammatory disease.Its main pathological three processes include intimal thickening,accumulation of foam cells and sedimentation of lipid and fibrous tissue.In the initial stage,a large number of cholesterol-rich macrophages(ie,foam cells)are deposited beneath the vascular endothelium(induced by injury or infection,etc.)in the lesion.Under the light microscope,a pronounced "lipid profile" appears on the inner wall of the blood vessel.Subsequently,a large number of lipid droplets and smooth muscle cells continue to accumulate at the lesion site,and a lipid-rich "necrotic center" and "fiber caps" are formed at the lesion site.As the lesion deepens,the blood vessel cavity begins to ulcerate and bleed.In the late stage of AS,the plaque is huge and unstable and it is easy to form thrombus after the plaque rupture which endangers life.Autophagy is a process in which protein and organelle degradation is mediated by lysosome.Autophagy can be found in both physiological and pathological process,which can resist environmental changes on cell damage and induce cell active death at the same time.During autophagy,parts of the cytoplasm are sequestered into characteristic double-membrane vesicles,autophagosomes,which subsequently fuse with late endosomes or lysosomes,forming the autolysosome.Exposure of the inner compartment to lysosomal hydrolases causes degradation of the cytoplasmic cargo and the resulting degradation products are then released into the cytosol for recycling As a results,qutophagy has a dual nature in the formation process of AS.What's more,the PI3K/Akt/m TOR signaling pathway is the classic pathway of autophagy.In recent years,with the in-depth study of mi RNAs,people have found that mi RNAs play an important role in the process of formation and development in AS.The latest research indicates that mi R-155 defects can inhibit the occurrence of AS.This experiment aimed to explore the effect of mi R-155 on carotid atherosclerotic plaques by changing the level of mi R-155 expression in Apo E-/-mice.By the way,we furtherly clarified whether mi R-155 can mediate PI3K/Akt/m TOR autophagy pathway.Materials and methods: 40 SPF 8 weeks old male Apo E-/-mice were randomly divided into control group(treated with high fat diet treatment),positive control group(treated with right carotid artery cannulation + high fat diet + tail intravenous injection of NS),mi R-155 up-regulated group,(treated with right carotid artery cannulation + high fat diet + tail intravenous injection of mi R-155-LV)and mi R-155 down-regulated group(ctreated with right carotid artery cannulation + high fat diet + tail intravenous injection of mi R-155-RNAi-LV).The mice were killed after 8 weeks.Then we detected plasma total cholesterol(TC),glycerin three greases(TG),low density lipoprotein cholesterol(LDL)level from femoral artery blood of mice,made pathological sections of the right carotid artery by HE staining method to observe growth condition of carotid artery plaques and detected protein expression levels of LC3-II and PI3K/Akt/m TOR signal pathway in right carotid plaque areas by Western blotting method.Results:(1)Analysis of blood lipid: after 8 weeks high-fat diet,the levels of TC,TG and LDL in plasma of each group were higher than the normal values,but there was no statistically significant difference in TC,TG and LDL levels among all groups(P >0.05).(2)Results of pathological section stained with HE: we failed to observed carotid artery plaque formation and thickening of arterial wall in the control group;We found that compared with the control group,the carotid arterial wall was thickened and the arterial lumen was narrowed in the positive control group;further compared with the positive control group,we found that up-regulation of mi R-155 increased the development of plaques and the stenosis of the lumen in the right carotid artery.However,after the mi R-155 level was down-regulated,only local plaques were formed and lumen stenosis was significantly reduced in the right carotid artery than the positive group.(3)Western blotting results: Compared with the control group,the expression level of each protein in the PI3K/Akt/m TOR signaling pathway was significantly increased in the positive control group(P < 0.05),while LC3-II protein expression was decreased(P<0.05).Compared with the positive group,up-regulation of mi R-155 increased PI3K/Akt/m TOR signaling protein expression(P<0.05)and inhibited LC3-II protein levels(P<0.05).However,PI3K/Akt/m TOR pathway protein expression was significantly decreased(P<0.05)and LC3-II protein was increased(P<0.05)in mi R-155 down-regulation group.Conclusion: Targeting down-regulation of mi R-155 expression in Apo E-/-mice can protect carotid arteries by inhibiting the PI3K/Akt/m TOR signaling pathway,activating autophagy and reduced carotid atherosclerotic plaque formation. |
PDF Full Text Request