Geniposide Ameliorates Atherosclerosis By Regulating Macrophage Polarization Via Perivascular Adipocyte-derived CXCL14

Background and aim:Atherosclerosis is a chronic and progressive inflammatory disease.Adipokines derived from perivascular adipose tissue(PVAT)can affect the initiation and development of AS via endocrine function.CXCL14 is a novel brown adipokine that can induce browning in white adipose tissue through promoting M2 macrophage polarization.However,the role of CXCL14 in AS remains unclear.Traditional Chinese Medicine believes that the theory of deficiency,phlegm,blood stasis and heat-toxin can be used as the basis of evidence-based prescription for the treatment of AS in modern Chinese medicine.Gardenia jasminoides Ellis is known as a heat-clearing and detoxifying herb.The role and potential mechanism of geniposide(GP),the main component of Gardenia jasminoides Ellis,in AS have not been fully elucidated.The present study wished to clarify whether GP improved the progression of AS by promoting M2 macrophage polarization in plaque via CXCL14 derived from PVAT.Methods:The ApoE-/-mice were fed with western diet(WD)to replicate the mouse model of AS,and CXCL14 expression was knocked down in vivo by lentivirus particles packaging CXCL14-shRNA,and the effects of geniposide and CXCL14 on AS in mice were observed in vivo.3T3-L1 mouse preadipocytes were induced and differentiated into mature adipocytes,and the effect of geniposide on the expression of UCP1 and CXCL14 in adipocytes was observed in vitro.LPS and IFN-y were used to induce the polarization of RAW264.7 macrophages to M1,and IL-4 was used to induce the polarization of RAW264.7 macrophages to M2.The effects of conditioned medium and CXCL14 mouse recombinant protein on the polarization of 3T3-L1 adipocytes were observed.Results:1.Geniposide reduced AS plaque size and increased plaque stability.Compared with the model group,geniposide significantly reduced the plaque area and increased the fibrous cap area.2.Geniposide inhibited M1 polarization and promoted M2 polarization of macrophages in plaques.Compared with the model group,geniposide significantly reduced the expression of M1 polarization-related genes such as iNOS,IL-6,IL-1β and TNFα,and increased the expression of M2 polarization-related genes such as Argl,IL-4,IL-10 and TGF-β.3.Geniposide enhanced the expression of UCP1 and CXCL14 in PVAT.Compared with the model group,geniposide markedly increased the expression levels of UCP1 and CXCL14 in PVAT,and the expression level of CXCL14 was negatively correlated with plaque size.4.CXCL14 knockdown blunted the effects of geniposide on AS plaque and macrophage polarization.The results of qPCR and WB showed that the expression of CXCL14 in the PVAT was significantly inhibited by CXCL14-shRNA,and the effects of geniposide on improving AS plaque and regulating macrophage polarization were blocked after silencing CXCL14 expression.5.Conditioned medium from 3T3-L1 adipocytes after geniposide treatment and mouse CXCL14 recombinant protein decreased the proportion of M1 type in RAW264.7 macrophages and increased the proportion of M2 type.Compared with the control group,geniposide treatment significantly increased the expression of UCP1 and CXCL14 in 3T3-L1 adipocytes.RAW264.7 macrophages were treated with conditioned medium from 3T3-L1 adipocytes and mouse recombinant CXCL14 protein,the results showed that both of them significantly inhibited Ml polarization and promoted M2 polarization.Conclusion:Our study has shown that geniposide ameliorates AS by promoting M2 polarization and inhibiting M1 polarization of plaque macrophages through increasing the expression of CXCL14 derived from PVAT.