The Role And Mechanism Of YKL-40 In Regulating The Biological Behavior Of Vascular Smooth Muscle Cells In Carotid Atherosclerotic Plaque

Objective Carotid atherosclerotic plaque rupture is an important cause of stroke,and previous studies found that YKL-40 expression was significantly increased in carotid plaque.This article will explore the role and potential mechanism of the inflammatory factor YKL-40 in atherosclerotic plaque progression and plaque stability,and provide new ideas for the study of the mechanism of atherosclerotic plaque development and plaque stability.To find new targets for the prevention and treatment of cardiovascular and cerebrovascular diseases.Methods The research design includes four parts:clinical sample experiment,cell experiment,mechanism study,and animal disease model experiment.In clinical specimen detection,we used Real Time Quantitative Polymerase Chain Reaction(RT-q PCR),Western blot detection,pathology detection and other experimental methods for 34 cases of advanced carotid artery plaque samples to clarify the correlation between plaque stability and the expression level of YKL-40,and clarify the location of YKL-40 in the plaque.Then through in vitro cell experiments,using apoptosis detection technology Td T-mediated d UTP Nick-End Labeling(TUNEL),oil red staining,proliferation detection technology5-Ethynyl-2'-deoxyuridine(EDU),Cell Counting Kit-8(CCK-8),migration experiment,molecular biology technology(RT-q PCR,Western blot),etc.to clarify the effect of YKL-40 on the biological function of human aortic smooth muscle cells(HASMC);Adenovirus transfection technology was used to overexpress YKL-40 in HASMC to detect the proliferation,migration and phenotypic changes of HASMC.Further analyze the potential mechanism of YKL-40 regulating vascular smooth muscle cells(VSMC)through RNA sequencing and bioinformatics analysis technology,then use molecular biology technology to verify.Finally,by using Low Density Lipoprotein Receptor Knockout Mice(LDLr^-/-)to construct a mouse model of carotid unstable plaque injected with YKL-40,and analyze the plaque stability by immunohistochemistry and other techniques,verify the function of YKL-40 in atherosclerosis and plaque stability.Results Part I.(1)The RNA level of YKL-40 is related to the stability of atherosclerotic plaques,and the expression level of YKL-40 is higher in unstable plaques.(2)The expression of YKL-40 is co-localized with VSMC in the plaque.(3)The RNA level of YKL-40 is positively correlated with Matrix Metalloproteinase-9(MMP-9)and Interleuk-1?(IL-1?),and negatively correlated with Smooth muscle 22?(SM22?)and Myosin Heavy Chain(MYH11).Part II.(1)Exogenous YKL-40 has no effect on the apoptosis and foam cell formation of VSMC;(2)Exogenous YKL-40 promotes the proliferation and migration of VSMC:(3)Exogenous YKL-40 Up-regulating the secretion of MMP-9 has no effect on the phenotypic transition of VSMC;(4)Overexpression of YKL 40 promotes the proliferation and migration of VSMC;(5)Overexpression of YKL 40 up-regulates the secretion of MMP-9,which has an effect on VSMC The phenotypic conversion has no effect.Part III.(1)RNA sequencing after overexpression of YKL-40,the main differential gene enrichment pathways include Mitogen-activated protein kinase(MAPK)and P53;(2)The phosphorylation level of P38 increased significantly after overexpression of YKL-40.Part IV.(1)After YKL-40 intervention,the mouse aortic root plaque area is larger,and AS progresses is faster;(2)After YKL-40 intervention,the mouse carotid plaque fiber cap becomes thinner and the necrotic core increases Larger,less collagen fibers,less VSMC in fibrous cap,and increased plaque instability.(3)After YKL-40 intervention,there was no significant effect on the proliferation and apoptosis of VSMC in the plaque;(4)After YKL-40 intervention,the expression of MMP-9 in the plaque increased significantly.Conclusion YKL-40 expression was significantly elevated in unstable carotid plaques and colocalized with VSMC.YKL-40 may activate MAPK pathway by promoting P38phosphorylation,regulate the proliferation and migration function of VSMC,and up-regulate the expression level of MMP-9.YKL-40 promoted the thinning of the fibrous cap and the decrease of collagen fiber content in AS plaques,which may be related to the upregulation of MMP-9.