Effect Of Aldehyde Dehydrogenase 2 On The Development Of Abdominal Aortic Aneurysm And Its Mechanism

BackgroundAbdominal aortic aneurysm(AAA)is afatal disease,with a rupture mortality exceeding 80%.The prevalence of aneurysms is still rising,but the mechanism remains unclear.Now the main treatment mainly relieson surgery without effective internal interventions.Recent studies have found that the phenotype transformation of vascular smooth muscle cells(VSMC)is one of the important pathological mechanisms of AAA.The loss of functional VSMC is the main cause of AAA.However,the regulating factors and potetntialtheputical targets need to be further explored.We previously found that individuals carrying ALDH2 inactivating point mutation had a decreased risk of-developing AAA compared with wild type people.Herein,we further investigated the mechanism of ALDH2 on AAA,and explored the underlying mechanisms.Objectives1.To investigate whether ALDH2 affects the formation of AAA in ApoE’/_mice2.To explore the molecular mechanism of ALDH2’s influence on the development of abdominal aortic aneurysm3.To study potential interventions that affect aneurysm developmentMethodsIn vivo study1.Establish AAA model in mice:AngⅡ(1.44 mg/kg per day)was dissolved in NS and infused using osmotic pumpsfor 28days in mice2.ALDH2 interventions:Simultaneous intraperitoneal injection of ALDH2-specific inhibitors(Daidzin,75 mg/kg per day),specifically reduce the activity of ALDH2 and study its effect on AAA,Mice were divided into groups as follows:DMSO sham;Daidzin sham;ANGII+DMSO;ANGII+Daidzin3.Establishing myocardin(Myocd)to interfere with mouse abdominal aortic aneurysm model(1)The AAV2 carrying Myocd-shRNA or empty vector was injected into the tail vein to construct a Myocd interference or control mouse model.The Myocd expression in the vascular tissue of mice was detected by Western blotting;(2)A mouse abdominal aortic aneurysm model was constructed according to the above methods,using ApoE-/-mice and double-knocked mice DKO,Mice were divided into groups as follows:ApoE-/-+NC,ApoE-/-+shRNA,DKO+shRNA;4.Abdominal aorta diameter was evaluated with echocardiography;5.VG staining was used to detect changes of vascular elastic fibers;6.HE staining to observe the morphological changes of mouse vessels;7.RT-PCR and western blot were performed to determine the expression of vascular smooth muscle cell markers and myocardin;8.Immunohistochemical method was used to detect vascular smooth muscle cell marker such as a-SMA,SM22a;In vitro study1.Human primary smooth muscle cells are stimulated with ANGII,Simultaneous administration of Daidzin Cells were divided into groups as follows:NS+DMSO,AGNII+DMSO,ANGII+Daidzin;2.Primary cells extracted from abdominal aorta of WT mouse are stimulated with ANGII,simultaneous administration of miR-31-5p Mimics,Cells were divided into groups as follows:DMSO+Mimic,Daidzin+Mimic,DMSO+Mimic nc,Daidzin+Mimic nc;3.Primary cells extracted from abdominal aorta of WT and KO mouse are stimulated with ANGII,Controls were given NS;4.RT-PCR andwestern blot were performed to detemine the expression of VSMC markers and myocardin;Results1.Inhibition of ALDH2 can reduce the incidence of abdominal aortic aneurysm;2.Inhibition of acetaldehyde dehydrogenase 2 activity maintains contractile function of smooth muscle cells by increasing the expression level of myocardin;3.Aldehyde dehydrogenase 2 can affect the expression of myocardin by miR-31-5p and affect the phenotypic switch and AAA of smooth muscle cellsConclusionsALDH2 plays an important role in the occurrence and development of AAA.Inhibition of ALDH2 activity regulates vascular smooth muscle cell phenotype switch by inhibiting miR-31-5pincreasing expression of myocardin,ALDH2 inhibitor reduces synthetic phenotype of VSMC after ANGII stimulation and maintains vascular contractibility and integrity,and ultimately reduces the occurrence and development of AAA.