The Effect And Mechanism Of CHI3L1 On The Stability Of Atherosclerosis Plaque Via Impaired Macrophage Efferocytosis

ObjectiveCardiovascular disease,especially stroke,has become the primary disease that threatens the health of Chinese residents.The rupture of unstable plaque of carotid artery stenosis is an important cause of stroke.The stability of the atherosclerotic plaque is the result of the dynamic equilibrium between the necrotic core and the fibrous cap within the plaque.Efferocytosis is the physiological process of phagocyte cells(macrophages,dendritic cells,etc.)to eliminate programmed death cells.The efficiency of macrophage efferocytosis in atherosclerotic plaques directly affects the size of the plaque necrosis core.The deficiency of efferocytosis results in a reduction in the stability of the atherosclerotic plaque.CHI3L1 is a molecular marker that is highly correlated with ischemic stroke and is also associated with atherosclerosis.However,whether CHI3L1 affects the stability of atherosclerotic plaque and its potential biological mechanism has not been reported yet.Understanding the impact of CHI3L1 on the stability of atherosclerotic plaque will help early diagnosis and early treatment of high-risk stroke patients.Therefore,the main purpose of this research is to clarify the impact of CHI3L1 on atherosclerotic plaque stability and to explore its specific biological mechanism.MethodsWe figure out the the effect of CHI3L1 in atherosclerosis plaque stability by analyze the plaque samples form volunteers.Meanwhile,primary human and mouse macrophages were extracted to study the effect of CHI3L1 on macrophages in vitro.Subsequently,CHI3L1 and its neutralizing antibody were injected to the mouse model of unstable carotid artery plaque in order to clarify the effect of CHI3L1 on the function of macrophage and the stability of plaque.Besides,the target genes of CHI3L1 were screened by proteomics and bioinformatics techniques,then western blot and QPCR were used to study their specific molecular mechanisms in atherosclerosis plaque.ResultsIn this study,tissue sections and RNA were used to detect CHI3L1 expression in unstable atherosclerotic plaques,which were mainly located near the necrosis core of plaque.It was demonstrated by flow cytometry and confocal laser scanning microscope that CHI3L1 could inhibit the macrophage efferocytosis in mouse bone marrow macrophages and human peripheral blood macrophages.In the model of unstable carotid atherosclerotic plaque,the mice injected with CHI3L1 showed deficiency of efferocytosis and less stable plaque compared with the control group,while this effect could restore by CHI3L1 neutralize antibody.Through the analysis of clinical samples and proteomics techniques,the target gene MFGE8 of CHI3L1,which was the bridge molecular of efferocytosis,was screened out and verified in vivo and in vitro.MFGE8 could rescue the deficiency of efferocytosis inhibited by CHI3L1,which comfirm that CHI3L1 suppress efferocytosis by reduction of MFGE8.Conclusionwe comfirmed CHI3L1 could reduce the stability of atherosclerosis plaque via impaired efferocytosis in vitro and in vivo.We figure out this effect is mediated by decreased MFGE8 expression and verifIed both in vitro and in mouse model.