| Atherosclerosis is a chronic inflammatory vascular disease and is the most common manifestation of cardiovascular disease.Inflammation-driven monocyte/macrophage infiltration and the formation of lipid-rich macrophage foam cells within the vessel wall are key stages in the development of atherosclerosis.Infiltration of monocytes/macrophages into the endothelium involves migration,adhesion and invasion.Specifically,endothelial cells undergo inflammatory activation to secrete various cytokines that recruit monocytes from the circulation and induce them to adhere to the endothelium.Once adherent to the endothelium,monocytes penetrate the arterial wall and take on the properties of macrophages,which are highly expressed in scavenging receptors and phagocytic lipoprotein particles transformed into foam cells.In short,monocyte/macrophage infiltration of the vessel wall is the initial process of atherosclerosis formation and targeted inhibition of macrophage infiltration is a potential strategy for the treatment of atherosclerosis.Both hyperlipidaemia and inflammation can trigger atherosclerosis.Although current strategies to reduce atherosclerosis can slow the progression of atherosclerosis,such as the administration of platelet aggregation inhibitors and statins,inflammation is not resolved and the risk of cardiovascular development remains.Thus,new approaches that can effectively reduce inflammation and hyperlipidaemia offer promising therapeutic targets for atherosclerosis.It has been reported that EQST has significant hypolipidemic and antibacterial activity.We hypothesized that EQST could inhibit the development of atherosclerosis in HFD-fed mice through both modulation of lipid metabolism and inhibition of inflammation.We explored the effects of EQST on atherosclerosis in mice by constructing a mouse model of atherosclerosis and a macrophage inflammation model.The main points of this essay are as follows:In Chapter 1,we introduce the current status of cardiovascular disease research,the formation of atherosclerosis,the relationship between macrophages and atherosclerosis,atherosclerosis and inflammation and related inflammatory signalling pathways,the progress of EQST research in atherosclerosis-related areas,and clarify the research background and research ideas of this thesis.In the second chapter,the effect of EQST on atherosclerosis formation in mice induced by high-fat diet was studied at animal level.Firstly,a high-fat diet-induced atherosclerosis model in mice was constructed,and it was found by oil red O,HE,MASSON,and immunohistochemical staining that after EQST treatment,ibramycin could reduce the number of atherosclerotic plaques and increase the stability of plaques compared with the control and positive drug groups,thus inhibiting the formation of atherosclerosis in mice.In Chapter 3 we explored the effect of EQST on the ability of macrophages to form foam cells and its mechanisms.Firstly,we examined the lipoprotein uptake and foam cell formation ability of mouse-derived macrophages and Raw264.7 cell line and found that EQST could attenuate the ability of macrophages to form foam cells.In order to clarify the effect of EQST on foam cell formation ability and its possible mechanism,we examined lipoprotein uptake related proteins and m RNA expression by Western blot and RT-PCR In order to clarify the effect of EQST on foam cell formation ability and its possible mechanism,the expression of lipoprotein uptake related proteins and m RNAs were detected by Western blot and RT-PCR.In conclusion,EQST inhibited the ability of macrophages to form foam cells by suppressing lipoprotein uptake.In Chapter 4 we explored the effect of EQST on the atherosclerotic inflammatory response.We first investigated the effect of EQST on the proatherosclerotic microenvironment in atherosclerotic plaques by immunohistochemical analysis of inflammatory cytokines and monocyte recruitment factors（including MMP2 and VCAM1）associated with the progression of atherosclerosis in the aorta of Apo E-/-mice.HFD significantly enhanced the protein expression of MMP2 and VCAM1 in the aorta of Apo E-/-mice.However,high doses of EQST significantly reduced the protein expression of MMP2 and VCAM1 in the aorta of HFD-fed Apo E mice.These results suggest that EQST can improve the proatherogenic microenvironment of atherosclerosis.We next investigated the effect of EQST on macrophage migration.We stimulated macrophages with LPS,which promotes macrophage migration,and we found that the addition of EQST significantly inhibited macrophage migration and down-regulated the expression levels of migration-associated proteins.In parallel,we investigated the effect of EQST on the expression of atherogenic cytokines induced by LPS and ox LDL in Raw264.7 cells.We found that EQST down-regulated the expression levels of inflammatory factors in macrophages by examining the expression levels of inflammatory factors IL-6,IL-1βand TNF-αin each group of cells when EQST was treated or not treated.In Chapter 5,based on the results of the previous section,we targeted the STAT3protein as a candidate molecular target for eumycin.To verify this result,in this chapter we first investigated the interactions between eumycin and STAT3 protein through molecular docking,followed by the identification of the binding ability of eumycin to STAT3 protein using cellular thermal shift analysis（CETSA）,and finally further investigated whether eumycin has any effect on the structure of STAT3 protein through circular dichroism.In summary,this thesis found that:（1）EQST can improve the extent of atherosclerosis induced by high-fat diet and enhance plaque stability in mice;（2）EQST can inhibit lipoprotein uptake and thus diminish the ability of macrophages to form foam cells,as well as down-regulate lipoprotein uptake-related protein and m RNA expression levels;（3）EQST can improve the proatherosclerotic microenvironment of atherosclerosis and reduce the levels of inflammatory factors in macrophages;（4）there is an interaction between eblockomycin and STAT3 protein,and STAT3 may be a key component of eblockomycin treatment of atherosclerosis.（3）EQST can improve the pro-atherogenic microenvironment of atherosclerosis and reduce the level of inflammatory factors in macrophages;（4）there is an interaction between EQST and STAT3 protein,and STAT3 may be a potential target protein for EQST in the treatment of atherosclerosis. |
