[Research progress of celastrol on the prevention and treatment of metabolic associated fatty liver disease].

Metabolic associated fatty liver disease (MAFLD) is a liver disease with hepatocyte steatosis caused by metabolic disorders, which is closely related to obesity, diabetes, metabolic dysfunction, and other factors. Its pathological process changes from simple steatosis, liver inflammation to non-alcoholic steatohepatitis (NASH), and then leads to liver fibrosis, cirrhosis, and liver cancer. At present, no specific therapeutics are available for treatment of MAFLD targeting its etiology. Celastrol is the main active component of the traditional Chinese medicine Celastrus orbiculatus Thunb. In recent years, it has been found that celastrol shows important medicinal value in regulating lipid metabolism, reducing fat and weight, and protecting liver, and then ameliorates MAFLD. This article reviews the related research progress of celastrol in the prevention and treatment of MAFLD, so as to provide a reference for the comprehensive development and utilization of celastrol.

[Oxidized phospholipids and atherosclerosis].

Phospholipids are important components of biomembrane and lipoproteins. Phospholipids can be oxidized by free radicals/nonradicals and enzymes to form oxidized phospholipids (OxPLs), which can lead to further generation of oxidation products with different biological activities. Clinical evidence shows that OxPLs are constantly generated and transformed during the pathogenesis of atherosclerosis and accumulated at the lesion sites. OxPLs are highly heterogeneous mixtures that can influence the progress of atherosclerosis through a variety of related receptors or signaling pathways. This review summarizes the process of phospholipid oxidation, the related products, the interaction of OxPLs with endothelial cells, monocytes/macrophages, smooth muscle cells, platelets and lipoproteins involved in the pathological process of atherosclerosis, and the progress of the researches using OxPLs as a target to inhibit atherosclerosis in recent years.

Roles and mechanisms of phospholipid transfer protein in the development of Alzheimer's disease.

Phospholipid transfer protein (PLTP) is a complex glycosylated protein that mediates the transfer of phospholipids, unesterified cholesterol, diacylglycerides, specific apolipoproteins, and tocopherols between different classes of lipoproteins as well as between lipoproteins and cells. Many studies have associated PLTP with a variety of lipid metabolic diseases. However, recent studies have indicated that PLTP is highly expressed in the brain of vertebrate and may be related to many central nervous system diseases, such as Alzheimer's disease. Here, we review the data and report the role and mechanisms PLTP in Alzheimer's disease.

[Different types of molecular hydrogen donors and their pharmacokinetics in vivo].

Molecular hydrogen (H2) has been shown to have diverse biomedical effects. As a small molecular gas, hydrogen can be diffused to the target without hindrance. A variety of related hydrogen products used in medical research and public health have been developed. There are various methods of administration of H2, mainly including inhaling hydrogen gas, drinking hydrogen water, injecting hydrogen-saline, orally taking solid-state H2 sustained-release agents, and stimulating intestinal microbiomes to produce hydrogen. Pharmacokinetics of H2 in vivo vary with methods of administration and thus influence its biomedical effects. This review summarizes the types of H2 donors and their pharmacokinetics in vivo.

[Research advances on preventive and therapeutic effects of hydrogen on cardiovascular and cerebrovascular diseases and underlying mechanisms].

For a long time, hydrogen (H2) has been considered as a physiological inert gas. However, recent studies have demonstrated that molecular H2 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 H2 in CCVDs and its possible molecular mechanisms, in the hope of providing new clues for the treatment of some CCVDs.

[The relationship of autophagy with endoplasmic reticulum stress and its role in pathogenesis, prevention and therapy of atherosclerosis].

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.

[Changes in biological functions of high-density lipoprotein after abnormal modification].

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.

[Activating transcription factor 6-C/EBP homologous protein pathway mediates advanced glycated albumin-induced macrophage apoptosis].

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.

Ethanol extract of propolis protects macrophages from oxidized low density lipoprotein-induced apoptosis by inhibiting CD36 expression and endoplasmic reticulum stress-C/EBP homologous protein pathway.

BACKGROUND: Ethanol extract of propolis (EEP), rich in flavones, has been known for various biological activities including antioxidant, antiinflammatory and antibiotic activities. Our previous studies have shown that EEP protects endothelial cells from oxidized low-density lipoprotein (ox-LDL)-induced apoptosis and inhibits atherosclerotic lesion development. In this present study, we explored the protective effect of EEP on ox-LDL-induced cytotoxicity in macrophages and specifically the endoplasmic reticulum (ER) stress-C/EBP homologous protein (CHOP) pathway-mediated apoptosis. METHODS: EEP was prepared and the total flavonoids content of EEP was determined by the colorimetric method of Chinese Standard (GB/T 20574-2006). The effects of EEP on lipid accumulation, cytotoxicity and apoptosis in RAW264.7 cells induced by ox-LDL or tunicamycin (TM, an ER stress inducer) were assayed using oil red O staining, MTT assay, flow cytometric analysis and so on. Immunofluorescence, Western blot and real time-PCR analysis were then used to further investigate the molecular mechanisms by which EEP protects macrophages from ox-LDL-induced apoptosis. 4-phenylbutyric acid (PBA), an ER stress inhibitor, was used as a positive control. RESULTS: EEP (7.5, 15 and 30 mg/L) not only attenuated ox-LDL-induced lipid accumulation in RAW264.7 macrophages in a dose-dependent manner but also inhibited the decreased cell viability and the increased lactate dehydrogenase (LDH) leakage, caspase-3 activation and apoptosis induced by ox-LDL or tunicamycin (TM, a classical ER stress inducer), which were similar to 4-phenylbutyric acid (PBA, an inhibitor of ER stress) treatment. In addition, like PBA, EEP significantly suppressed the ox-LDL- or TM-induced activation of ER stress signaling pathway including the phosphorylation of double-stranded RNA-activated protein kinase-like ER kinase (PERK) and eukaryotic translation initiation factor 2α (eIF2α) as well as upregulation of glucose regulated protein 78 (GRP78) and the pro-apoptotic protein CHOP. Furthermore, EEP significantly suppressed ox-LDL intake by macrophages and the upregulation of CD36 induced by ox-LDL. CONCLUSION: These data indicate that EEP may protect macrophages from ox-LDL-induced apoptosis and the mechanism at least partially involves its ability to suppress the CD36-mediated ox-LDL intake and subsequent activation of ER stress-CHOP signalling pathway.

Cardioprotective Effect of Hydrogen-rich Saline on Isoproterenol-induced Myocardial Infarction in Rats.

BACKGROUND: Infusion with hydrogen gas-saturated saline has recently been reported to exert antioxidant and anti-inflammatory activity that may protect against organ damage induced by oxidative stress. Therefore because oxidative stress plays a significant role in the pathophysiology of myocardial infarction (MI), the aim of our study was to investigate whether hydrogen-rich saline has cardioprotective effects against isoproterenol-induced MI in rats. METHODS: An acute MI model was induced in male Wistar rats by subcutaneous injection of isoproterenol. Different doses of hydrogen-rich saline (5, 7.5, and 10 mL/kg body weight i.p.) or Vitamin C (250 mg/kg body weight i.g.) were administered to the rats. Oxidative stress indices including levels of myocardial marker enzymes, inflammatory cytokines, membrane-bound myocardial enzymes and histopathological changes were measured. RESULTS: Compared with those in isoproterenol-MI group, hydrogen-rich saline decreased malondialdehyde and 8-hydroxy-desoxyguanosine concentrations, enhanced superoxide dismutase and Na(+)-K(+)-ATPase activity, lowered Ca(2+)-ATPase activity and decreased interleukin-6 and tumour necrosis factor-α levels in the serum and/or cardiac tissue of rats. Hydrogen-rich saline pretreatment also diminished infarct size, improved left heart function, and ameliorated pathological changes of the left heart. CONCLUSION: From these results, hydrogen-rich saline exerts cardiovascular protective effects against isoproterenol-induced MI at least in part via interactions which evoke antioxidant and anti-inflammatory activities.

[Endoplasmic reticulum stress mediates oxidized low density lipoprotein-induced scavenger receptor A1 upregulation in macrophages].

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.

[Ox-LDL down-regulates expression of pigment epithelium-derived factor in human umbilical vein endothelial cells].

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.

[Inhibitory effect of quercetin preconditioning on tunicamycin-induced apoptosis in macrophages and its mechanism].

The purposes of the present study were to investigate the inhibitory effect of quercetin (QUE) preconditioning on endoplasmic reticulum stress (ERS) inducer tunicamycin (TM)-induced apoptosis in RAW264.7 macrophages and the underlying molecular mechanisms. RAW264.7 cells were pretreated with different concentrations (20, 40, and 80 µmol/L) of QUE for 30 min and then treated with TM (5 mg/L) for 12 h. Cell viability and apoptosis were determined using MTT assay and Annexin V-FITC apoptosis detection kit, respectively. The nuclear translocation of activating transcription factor 6 (ATF6) in cells was detected by immunofluorescence analysis and Western blot. Protein and mRNA expressions of C/EBP homologous protein (CHOP) and Bcl-2 were examined by Western blot and real-time PCR, respectively. The results showed that TM reduced cell viability and induced apoptosis in RAW264.7 macrophages. The cytotoxic effects of TM were significantly inhibited by QUE pretreatment at the concentrations of 40 and 80 µmol/L. Interestingly, we found that QUE also significantly suppressed the TM-induced translocation of ATF6, an ERS sensor, from the cytoplasm to the nucleus. In addition, exposure of RAW264.7 macrophages to TM resulted in a significant increase of the expression of CHOP, a transcription factor regulated by ATF6 under conditions of ERS, as well as a decrease of Bcl-2 at transcript and protein levels. QUE blocked these effects in a dose-dependent manner. These data indicate that QUE can protect RAW264.7 cells from TM-induced apoptosis and that the mechanism at least partially involves its ability to inhibit the ATF6-CHOP signaling pathway.

Inhalation of 4% and 67% hydrogen ameliorates oxidative stress, inflammation, apoptosis, and necroptosis in a rat model of glycerol-induced acute kidney injury.

Acute kidney injury (AKI) is the major complication of rhabdomyolysis (RM) clinically, which is usually mimicked by glycerol injection in basic research. Oxidative stress, inflammatory response and apoptosis are recognized to play important roles in development of this disease. Recently, numerous studies have reported the therapeutic effects of molecular hydrogen (H2) on oxidative stress and inflammation-related diseases. Here, the effects of H2 against glycerol-induced AKI and the underlying mechanisms were explored in rats. Low (4%) and high (67%) concentrations of H2 were prepared using a self-made device to investigate the dose-response. After 72 hours of glycerol injection (8 mL/kg), we found that glycerol triggered oxidative stress, inflammatory reactions, and apoptotic events. These caused subsequent renal damage, evidenced by a significant reduction of antioxidases and up-regulation of the relevant damaged biomarkers. H2 inhalation reversed the above alterations and exerted renoprotective effects. Interestingly, for RM/AKI-related factors, no consistent dose-response benefits of H2 were observed. However, higher concentration of H2 inhalation improved histological and morphological changes better. This study suggests that H2 is a potential alternative therapy to prevent or minimize RM induced AKI possibly via its antioxidant, anti-inflammatory, anti-apoptotic and anti-necroptotic properties.

In vivo microelectrode monitoring of real-time hydrogen concentration in different tissues of rats after inhaling hydrogen gas.

Medical effects of hydrogen have been reported in many studies. Due to difficulties in measuring hydrogen concentration in vivo after intake and high explosive risks of hydrogen, studies about dose-response relationships and tissue concentrations of hydrogen are few. Here, for the first time, we monitored real-time hydrogen concentrations in different tissues in rats including brain, liver, spleen, kidney, thigh muscle, inguinal white adipose tissue, and gonadal white adipose tissue after inhaling different concentrations of hydrogen (4%, 42%, and 67%) using an electrochemical sensor. Hydrogen concentrations in the same tissue showed a dose-dependent response. The equilibrium concentration values were highest in the brain and lowest in the thigh muscle. The saturation and desaturation curves changed more slowly in the thigh muscle and white adipose tissues than in other tissues. These results provide fundamental information for the selection of hydrogen dose applications in basic research and clinical trials. The experiments were approved by the Laboratory Animal Ethics Committee of Shandong First Medical University & Shandong Academy of Medical Sciences (No. 2020-1028) on March 18, 2020.

Protective effects of hydrogen-rich saline on monocrotaline-induced pulmonary hypertension in a rat model.

BACKGROUND: Hydrogen-rich saline has been reported to have antioxidant and anti-inflammatory effects and effectively protect against organ damage. Oxidative stress and inflammation contribute to the pathogenesis and/or development of pulmonary hypertension. In this study, we investigated the effects of hydrogen-rich saline on the prevention of pulmonary hypertension induced by monocrotaline in a rat model. METHODS: In male Sprague-Dawley rats, pulmonary hypertension was induced by subcutaneous administration of monocrotaline at a concentration of 6 mg/100 g body weight. Hydrogen-rich saline (5 ml/kg) or saline was administered intraperitoneally once daily for 2 or 3 weeks. Severity of pulmonary hypertension was assessed by hemodynamic index and histologic analysis. Malondialdehyde and 8-hydroxy-desoxyguanosine level, and superoxide dismutase activity were measured in the lung tissue and serum. Levels of pro-inflammatory cytokines (tumor necrosis factor-α, interleukin-6) in serum were determined with enzyme-linked immunosorbent assay. RESULTS: Hydrogen-rich saline treatment improved hemodynamics and reversed right ventricular hypertrophy. It also decreased malondialdehyde and 8-hydroxy-desoxyguanosine levels, and increased superoxide dismutase activity in the lung tissue and serum, accompanied by a decrease in pro-inflammatory cytokines. CONCLUSIONS: These results suggest that hydrogen-rich saline ameliorates the progression of pulmonary hypertension induced by monocrotaline in rats, which may be associated with its antioxidant and anti-inflammatory effects.

[Differential time attachment: optimization of the adherent time to obtain mouse bone marrow-derived endothelial progenitor cells].

The different biological functions were studied in mouse bone marrow-derived endothelial progenitor cells isolated by differential time attachment to obtain the optimal adherent time in this study. Density gradient centrifugation-isolated bone marrow mononuclear cells were seeded on the fibronectin-coated dish. The 1-day cultured unattached cells were seeded on the second dish for 2 more days. Then unattached cells in the second dish were seeded on the third dish. The cells on 3 dishes were defined as 1-day adherent cells, 3-day adherent cells and 3-day unattached cells, respectively. After 20-day culture, the biological functions, such as the percentage of biomarkers, the ability of adhesion, and the ability of forming tubes in vitro were analyzed. The results showed that the percentages of positive CD34, FLK-1, and CD34/FLK-1 expressions in 1-day attached cells were significantly increased compared to those in the 3-day adherent or unattached cells (P < 0.01), which showed the strongest adhesion ability. The expression of eNOS in 1- or 3-day adherent cells was significantly higher than that in 3-day unattached cells (P < 0.01). The expression of VEGF in 3-day adherent cells was significantly higher than that in 1-day adherent cells or 3-day unattached cells (P < 0.01). These results suggest the biological functions of 1-day adherent cells are significantly stronger than that of 3-day adherent or unattached cells. VEGF expression in 3-day adherent cells is higher than that in 1-day adherent cells or 3-day unattached cells. The expression of eNOS in 1-day adherent cells or 3-day adherent cells is higher than that in 3-day unattached cells. The optimal adherent time to obtain mouse bone marrow-derived endothelial progenitor cells is 1-3 d.

[Oxidative stress of platelet and atherosclerosis].

Most platelet-derived oxidants are produced through NAD (P) H-oxidase enzyme system. There are antioxidants such as superoxide dismutase and reduced glutathione in platelet. Oxidative stress alters platelet functions via regulation of platelet aggregation phase, impact on platelet nitric oxide and alpha II bbeta3 integrin, and imbalance between reduced and oxidized glutathione in platelet. Activated platelet by oxidative stress can influence blood vessel endothelium cell function, and worsen atherosclerosis through CD40 ligand. LDL is modified to oxidized LDL by platelets which can trigger foam cell formation. Some drugs with therapeutic intervention to reduce oxidative stress of platelet will be of use for atherosclerosis treatment.

[The progress of nuclear medicine and magnetic resonance molecular imaging of atherosclerotic vulnerable plaques].

The major goal of atherosclerotic molecular imaging is to target specific plaque-associated molecules with molecular probe that provide sensitive and specific imaging contrast and acquire molecular imaging. This method will greatly improve detection and characterization of atherosclerotic lesions, especially plaque components. The plaque components are highly associated with plaque rupture and vulnerability to rupture as well as the consequences followed plaque rupture. Thus, the knowledge about plaque composition will have tremendous clinical utility in terms of the treatment and prognosis judgment of patients with atherosclerosis.