Endoplasmic Reticulum Stress-induced Endothelial Dysfunction Promotes Neointima Formation after Arteriovenous Grafts in Mice on High-fat Diet

Objective Endothelial dysfunction is one candidate for triggering neointima formation after arteriovenous grafts(AVGs),but the factors mediating this process are unclear.The purpose of this study was to investigate the role of endoplasmic reticulum stress(ERS)-induced endothelial dysfunction in neointima formation following AVGs in high-fat diet(HFD)mice.Methods CCAAT-enhancer-binding protein-homologous protein(CHOP)knockout(KO)mice were created.Mice were fed with HFD to produce HFD model.AVGs model were applied in the groups of WT ND,WT HFD,and CHOP KO HFD.Human umbilical vein endothelial cells(HUVECs)were cultured with oxidized low density lipoprotein(ox-LDL)(40 mg/L)for the indicated time lengths(0,6,12,24 h).ERS inhibitor tauroursodeoxycholic acid(TUDCA)was used to block ERS.Immunohistochemical staining was used to observe the changes of ICAM1.Changes of ERS were detected by real-time RT-PCR.Protein expression levels and ERS activation were detected by Western blotting.Endothellial cell function was determined by endothelial permeability assay and transendothelial migration assay.Results HFD increased neointima formation in AVGs associated with endothelial dysfunction.At the same time,ERS was increased in endothelial cells(ECs)after AVGs in mice consuming the HFD.In vitro,ox-LDL was found to stimulate ERS,increase the permeability of the EC monolayer,and cause endothelial dysfunction.Blocking ERS with TUDCA or CHOP siRNA reversed the EC dysfunction caused by ox-LDL.In vivo,knockout of CHOP(CHOP KO)protected the function of ECs and decreased neointima formation after AVGs in HFD mice.Conclusion Inhibiting ERS in ECs could improve the function of AVGs.

Carbon Monoxide Releasing Molecule Accelerates Reendothelialization after Carotid Artery Balloon Injury in Rat

Objective This study was aimed to investigate the effects of carbon monoxide releasing molecule （CORM-2）, a novel carbon monoxide carrier, on the reendothelialization of carotid artery in rat endothelial denudation model. Methods Male rats subjected to carotid artery balloon injury were treated with CORM-2, inactive CORM-2 （iCORM-2） or dimethyl sulfoxide （DMSO）. The reendothelialization capacity was evaluated by Evans Blue dye and the immunostaining with anti-CD31 antibody. The number of circulating endothelial progenitor cells （EPCs） was detected by flow cytometry. The proliferation, migration, and adhesion of human umbilical vein endothelial cells （HUVECs） were assessed by using [3H]thymidine, Boyden chamber and human fibronectin respectively. The expressions of protein were detected by using western blot analysis. Results CORM-2 remarkably accelerated the re-endothelialization 5 d later and inhibited neointima formation 28 d later. In addition, the number of peripheral EPCs significantly increased in CORM-2-treated rats than that in iCORM-2 or DMSO-treated rats after 5 d later. In vitro experiments, CORM-2 significantly enhanced the proliferation, migration and adhesion of HUVECs. The levels of Akt, eNOS phosphorylation, and NO generation in HUVECs were also much higher in CORM-2 treated group. Blocking of PI3K/Akt/eNOS signaling pathway markedly suppressed the enhanced migration and adhesion of HUVECs induced by CORM-2. Conclusion CORM-2 could promote endothelial repair, and inhibit neointima formation after carotid artery balloon injury, which might be associated with the function changes of HUVECs regulated by PI3K/Akt/eNOS pathway.