Soluble Epoxide Hydrolase Deletion Attenuated Nicotine-induced Arterial Stiffness

Background and Objective:Arterial stiffness is a potential risk factor for cardiovascular diseases and is closely related to smoking.Epoxyeicosatrienoic acids（EETs）,which was hydrolyzed by soluble epoxide hydrolase（s EH）,have beneficial effects against cardiovascular dysfunction.Previous studies have found that EETs can inhibit vascular remodeling.However,whether s EH knockout affects nicotine-induced arterial stiffness has not been reported.Therefore,this study aims to explore whether s EH knockout could prevent nicotine-induced arterial stiffness and its underlying mechanism.Methods:In the present study,Male Ephx2（the gene encodes the s EH enzyme）knockout（Ephx2-/-）mice and wild-type（WT）littermate mice were infused with or without nicotine（5 mg/kg per day）,combined with or without nicotinamide（NAM,SIRT1 inhibitor,10 mg/kg/day）,for four weeks.Aortic pulse-wave velocity（PWV）was measured using a Vevo 2100 Imaging System.Morphological and immunohistochemical analysis was performed by Masson’s Trichrome staining,Verhoeff’s Van Gieson（EVG）staining and IHC staining.The EETs levels and SIRT1activity were measured by ELISA.The YAP activity was assayed by immunofluorescent staining.In-vitro study,movas were pretreated with or without EETs（10μM）for 2 hours,followed by nicotine（1μM）accompanied with or without Selisistat（EX-527,10μM）treatment for 24 hours.The expression of p-YAP,MMP2,and SIRT1 were measured by Western Blot.The YAP activity was assayed by immunofluorescent staining.Results:Nicotine treatment increased s EH expression and activity in the aortas of WT mice.Nicotine infusion significantly induced vascular extracellular matrix（ECM）remodeling,enhanced arterial stiffness,and decreased SIRT1 expression in WT mice but not in Ephx2^-/-mice without NAM treatment.However,the protective effects were gone in Ephx2^-/-mice with NAM treatment.In addition,SIRT1 inhibition blocked the depressive role of Ephx2 knock out in nicotine induced YAP activation and dephosphorylation.In vitro studies,11,12-EET treatment attenuated nicotine-induced MMP2 activation and SIRT1 depression,which was blocked by NAM treatment.Also,SIRT1 inhibition blocked the depressive role of 11,12-EET in nicotine induced YAP activation and dephosphorylation.Conclusion:Ephx2 knockout SIRT1-dependent attenuated nicotine-induced arterial stiffness and extracellular matrix remodeling by limiting the loss of SIRT1 and inhibiting YAP nuclear localization,which was mediated by increased EETs production.