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Purpose: The role of endoplasmic reticulum (ER) stress in cardiovascular disease is now recognized. Tauroursodeoxycholic acid (TUDCA) is known to have cardiovascular protective effects by decreasing ER stress. This study aimed to assess the ability of TUDCA to decrease ER stress, inhibit dedifferentiation of vascular smooth muscle cells (VSMCs), and reduce in-stent restenosis., Methods: The effect of TUDCA on dedifferentiation of VSMCs and ER stress was investigated in vitro using wound-healing assays, MTT assays, and western blotting. For in vivo studies, 18 rabbits were fed an atherogenic diet to induce atheroma formation. Bare metal stents (BMS), BMS+TUDCA or Firebird stents were implanted in the left common carotid artery. Rabbits were euthanized after 28 days and processed for scanning electron microscope (SEM), histological examination (HE), and immunohistochemistry., Results: In vitro TUDCA (10-1000 μmol/L) treatment significantly inhibited platelet-derived growth factor (PDGF)-BB-induced proliferation and migration in VSMCs in a concentration-dependent manner and decreased ER stress markers (IRE1, XBP1, KLF4, and GRP78). In vivo, we confirmed no significant difference in neointimal coverage on three stents surfaces; neointimal was significantly lower with BMS+TUDCA (1.6 ± 0.2 mm 2 ) compared with Firebird (1.90 ± 0.1 mm 2 ) and BMS (2.3 ± 0.1 mm 2 ). Percent stenosis was lowest for BMS+TUDCA, then Firebird, and was significantly higher with BMS (28 ± 4%, 35 ± 7%, 40 ± 1%; respectively; P < 0.001). TUDCA treatment decreased ER stress in the BMS+TUDCA group compared with BMS., Conclusions: TUDCA inhibited dedifferentiation of VSMCs by decreasing ER stress and reduced in-stent restenosis, possibly through downregulation of the IRE1/XBP1 signaling pathway.

Abstract Background Phenotypic switching of vascular smooth muscle cells (VSMCs) plays a key role in atherosclerosis. We aimed to investigate whether Homocysteine-responsive endoplasmic reticulum protein (Herp) was involved in VSMC phenotypic switching and affected atheroprogression. Methods To assess the role of Herp in homocysteine (Hcy)-associated atherosclerosis, Herp−/− and LDLR−/− double knockout mice were generated and fed with a high methionine diet (HMD) to induce Hyperhomocysteinemia (HHcy). Atherosclerotic lesions, cholesterol homeostasis, endoplasmic reticulum (ER) stress activation, and the phenotype of VSMCs were assessed in vivo. We used siRNAs to knockdown Herp in cultured VSMCs to further validate our findings in vitro. Results HMD significantly activated the activating transcription factor 6 (ATF6)/Herp arm of ER stress in LDLR −/− mice, and induced the phenotypic switch of VSMCs, with the loss of contractile proteins (SMA and calponin) and an increase of OPN protein. Herp−/−/LDLR−/− mice developed reduced atherosclerotic lesions in the aortic sinus and the whole aorta when compared with LDLR−/− mice. However, Herp deficiency had no effect on diet-induced HHcy and hyperlipidemia. Inhibition of VSMC phenotypic switching, decreased proliferation and collagen accumulation were observed in Herp−/−/LDLR−/− mice when compared with LDLR−/− mice. In vitro experiments demonstrated that Hcy caused VSMC phenotypic switching, promoted cell proliferation and migration; this was reversed by Herp depletion. We achieved similar results via inhibition of ER stress using 4-phenylbutyric-acid (4-PBA) in Hcy-treated VSMCs. Conclusion Herp deficiency inhibits the phenotypic switch of VSMCs and the development of atherosclerosis, thus providing novel insights into the role of Herp in atherogenesis. Highlights • HMD-induced HHcy could independently cause atherosclerosis through activating ER stress related ATF6/Herp pathway. • Herp deficiency mitigates HHcy-induced atherosclerosis in LDLR −/− mice; • Herp knockdown suppresses the phenotypic switch, cell proliferation and migration of VSMCs; • Herp deficiency protects against HHcy-related atherosclerosis by inhibiting the phenotypic switch of VSMCs. [ABSTRACT FROM AUTHOR]

Background Angiotensin II (Ang II)-induced damage to endothelial cells (ECs) plays a crucial role in the pathogenesis of atherosclerosis. This study aimed to investigate the role of microRNA-384 (miR-384) in endothelial cell apoptosis. Methods The expression of five various miRNAs in Ang II-treated human umbilical vein endothelial cells (HUVECs) were detected by qPCR. The Ang II-induced apoptosis of HUVECs was determined by flow cytometry, TUNEL staining and western blot. Endoplasmic reticulum (ER) stress markers were detected by western blot analysis. The target gene of miR-384 was determined by bioinformatics analyses. qPCR, western blotting and immunofluorescence were performed to determine the expression level of homocysteine inducible ER protein with ubiquitin like domain 1 (Herpud1). Results miR-384 expression level was significantly decreased in Ang II-treated HUVECs. Ang II-induced HUVEC apoptosis was accompanied by the occurrence of ER stress. A decreased rate of HUVEC apoptosis and a decreased rate of ER stress were observed following restoration of miR-384 expression. Herpud1 expression level was increased in HUVECs treated with Ang II, and miR-384 mimics effectively inhibited Herpud1 expression. Mechanistically, miR-384 directly targets the 3′-untranslated region of Herpud1. Furthermore, effects of miR-384 on HUVECs apoptosis and ER stress were at least partly reversed by knockdown of Herpud1 expression. Conclusion The results of the present study collectively indicated that miR-384 expression level was downregulated in Ang II-treated HUVECs and miR-384 overexpression protected HUVECs against Ang II-induced apoptosis by negatively regulating Herpud1. These findings point towards new strategies by which apoptosis of ECs can be suppressed. [ABSTRACT FROM AUTHOR]