Autophagy is a cellular catabolic process responsible for removing the injured proteins and organelles via lysosome-dependent pathway, and it plays an important role in maintaining cellular homeostasis. Recent studies have shown that autophagy is activated and implicated in the pathogenesis of atherosclerosis. Autophagy can be triggered by oxidative lipids, cytokines and advanced glycation end products, and exerts protective or detrimental functions in the progression of atherosclerosis. However, the precise role and mechanisms of autophagy in different stages of atherosclerosis are still not fully clarified. This review highlights recent findings regarding autophagy response in vascular cells and its potential contribution to atherogenesis. Additionally, the relationship of autophagy with endoplasmic reticulum stress and whether autophagy could be a new therapeutic target for atherosclerosis are also discussed.

Pigment epithelium-derived factor (PEDF) is a multifunctional protein with anti-inflammatory, antioxidant and antithrombotic properties and plays a protective role against atherosclerosis (AS). The purpose of the present study is to explore the effects of oxidized low density lipoprotein (ox-LDL) on the expression of PEDF in cultured human umbilical vein endothelial cells (HUVECs). HUVECs were cultured and incubated with ox-LDL at different concentrations (6.25, 12.5, 25, 50, 100 and 150 mg/L) for 24 h. Apoptosis of endothelial cells were assayed by morphological staining and flow cytometry. The intracellular reactive oxygen species (ROS) levels were measured by flow cytometry. Cell viability was assayed by MTT assay. PEDF protein and mRNA expressions in HUVECs were analyzed by Western blot and quantitative real-time PCR, respectively. The results showed that ox-LDL significantly induced apoptosis, reduced cell viability, increased intracellular ROS levels and decreased the PEDF expression in HUVECs in a concentration-dependent manner. Ox-LDL at 50 mg/L obviously decreased the PEDF protein expression compared with control group (P < 0.05), whereas 25 mg/L ox-LDL already markedly reduced the PEDF mRNA expression (P < 0.05). In conclusion, the results suggest that ox-LDL down-regulates the PEDF expression through an increased ox-LDL-induced intracellular production of ROS.
Apoptosis ; Cells, Cultured ; Down-Regulation ; Eye Proteins ; metabolism ; Human Umbilical Vein Endothelial Cells ; cytology ; drug effects ; Humans ; Lipoproteins, LDL ; pharmacology ; Nerve Growth Factors ; metabolism ; Reactive Oxygen Species ; metabolism ; Serpins ; metabolism

The present study was to investigate whether endoplasmic reticulum stress (ERS) was involved in oxidized low density lipoprotein (ox-LDL)-induced scavenger receptor A1 (SR-A1) upregulation in macrophages. RAW264.7 cells were pretreated with 20 mmol/L of 4-phenylbutyric acid (PBA) for 30 min and then treated with ox-LDL (50 mg/L) for 12 h or stimulated with 2 mg/L tunicamycin (TM) or 2 μmol/L thapsigagin (TG) for 4 h. In addition, RAW264.7 cells were incubated with 0.5, 1 and 2 mg/L TM for 4 h or treated with 2 mg/L TM for 1, 2 and 4 h, respectively. The intracellular total cholesterol (TC) content was measured using a tissue/cell total cholesterol assay kit. The protein and mRNA expressions of SR-A1 and glucose-regulated protein 78 (GRP78) were analyzed by Western blot and real-time PCR, respectively. Dil-ox-LDL uptake was detected using a microplate reader. The results showed that ox-LDL-induced cholesterol accumulation in macrophages was attenuated by PBA, an ERS inhibitor. Ox-LDL caused significant SR-A1 upregulation with concomitant activation of ERS as assessed by upregulation of GRP78, whereas PBA significantly inhibited the ox-LDL-induced SR-A1 upregulation (P < 0.05) and slightly decreased GRP78 expression by 39.3% (P = 0.057). TM, an ERS inducer, upregulated SR-A1 protein expression and ox-LDL uptake in dose- and time-dependent manner, but had no significant effect on SR-A1 mRNA level. However, the TM- or TG-induced SR-A1 upregulation and ox-LDL uptake were significantly mitigated by PBA. These data indicate that ERS plays a critical role in ox-LDL-induced SR-A1 upregulation, which in turn enhances the foam cell formation by uptaking more ox-LDL.
Animals ; Cell Line ; Cholesterol ; metabolism ; Endoplasmic Reticulum Stress ; Heat-Shock Proteins ; metabolism ; Lipoproteins, LDL ; pharmacology ; Macrophages ; drug effects ; metabolism ; Mice ; Scavenger Receptors, Class A ; metabolism ; Up-Regulation

High-density lipoprotein (HDL) is composed of apolipoproteins, lipids and functional proteins. HDL protects against atherosclerosis (AS) by reverse cholesterol transport (RCT). HDL inhibits the lipid oxidation, inflammation and restores endothelial function. During systemic inflammation or metabolic disorders, HDL can be modified abnormally and converted to a dysfunctional type, which results in the loss of anti-inflammatory factors including apolipoprotein A-I (apoA-I), paraoxonase (PON) and platelet activating factor acetylhydrolase (PAF-AH), and gains of pro-inflammatory factors such as serum amyloid A (SAA), triglyceride (TG) and oxidative lipid. Therefore, understanding the changes in compositions and biological functions of dysfunctional HDL might help to comprehend its pathogenic mechanism.

For a long time, hydrogen (H) has been considered as a physiological inert gas. However, recent studies have demonstrated that molecular H exerts significant therapeutic effects on various disease models due to its antioxidative, anti-inflammatory and anti-apoptotic capabilities, which have also been well confirmed in many clinical trials. Cardiovascular and cerebrovascular diseases (CCVDs) are the leading cause of death in the world, constituting a serious threat to human life and public health. In this paper, we reviewed the latest research progress of the biomedical effects of H in CCVDs and its possible molecular mechanisms, in the hope of providing new clues for the treatment of some CCVDs.

The purpose of this study was to investigate whether activating transcription factor 6 (ATF6), a sensor to endoplasmic reticulum stress (ERS), would mediate advanced glycated albumin (AGE-alb)-induced macrophage apoptosis and to elucidate the possible molecular mechanisms. RAW264.7 macrophages were cultured in vitro and treated with AGE-alb (2, 4 and 6 g/L), normal control albumin or tunicamycin (TM, 4 mg/L) for 24 h. ATF6 small interfering RNA (siRNA) was transfected to RAW264.7 cells by Lipofectamine 2000. Cell viability and apoptosis were determined by MTT method and Annexin V-FITC/propidium iodide apoptosis detection kit, respectively. The activities of lactate dehydrogenase (LDH) in medium and caspase-3 in cells were measured by corresponding detection kits. ATF6 nuclear translocation was detected by Western blot and immunofluorescence cytochemistry. Protein and mRNA levels of C/EBP homologous protein (CHOP, a key-signaling component of ERS-induced apoptosis) were detected by Western blot and real-time fluorescence quantitative PCR, respectively. The results showed that similar to TM, AGE-alb increased the expression of CHOP at both the protein and mRNA levels in a concentration dependent manner. ATF6, as a factor that positively regulates CHOP expression, was activated by AGE-alb in a concentration dependent manner. siRNA-mediated knockdown of ATF6 significantly inhibited AGE-alb-induced macrophage injury, as indicated by the increased cell viability and the decreased LDH release, apoptosis and caspase-3 activation. Additionally, ATF6 siRNA attenuated AGE-alb-induced CHOP upregulation at both the protein and mRNA levels. These results suggest that ATF6 and its downstream molecule CHOP are involved in AGE-alb-induced macrophage apoptosis.