Hydrogen sulfide attenuates endothelial cell senescence via inhibiting over-phosphorylation of protein kinase B

AIM To explore the effect of hydrogen sulfide on the senescence of human umbilical vein endothelial cells (HUVECs) induced by hydrogen peroxide (H₂O₂) and the possibly involved mechanism. METHODS Senescence model was established by treating HUVECs with H₂O₂ at 60 μmol/L for 1 h and then cultured for 24 h. The several parameters were detected to demonstrate the effect of hydrogen sulfide on senescence by Western blot. RESULTS In the cells treated with H₂O₂, a larger proportion of cells were stained with β-galactosidase (SA-β-Gal), and the protein expression of plasminogen activator inhibitor 1 (PAI-1) was dramatically increased (P<0.05). The less SA-β-Gal positive cells and decreased protein of PAI-1 were detected when the cells were pretreated with 100 μmol/L sodium hydrosulfide (NaHS). Furthermore, NaHS treatment inhibited the phosphorylation of protein kinase B (PKB/Akt). Meanwhile, LY294002, the specific inhibitor of Akt, was also able to reverse the cellular senescence induced by H₂O₂ in HUVECs. CONCLUSION Exogenous hydrogen sulfide prevents HUVECs against H₂O₂-induced senescence partially via the inhibition of Akt over-phosphorylation.     

Roles of protein phosphatase 4 in down-regulation of eNOS Ser633 phosphorylation induced by palmitic acid in human umbilical vein endotheli?al cells

AIMTo investigate the roles of protein phosphatase 4 (PP4) in down-regulation of endothelial nitric oxide synthase (eNOS) Ser633 phosphorylation induced by palmitic acid (PA). METHODSHuman umbilical vein endothelial cells (HUVECs) were treated with PA at 25 μmol/L, 50 μmol/L, 100 μmol/L and 200μmol/L for 36 h, or treated with PA at 100 μmol/L for 12 h, 24 h, 36 h and 48 h. Protein phosphatase 2A (PP2A) family inhibitor fostriecin (FST, 20 nmol/L) or okadaic acid (OA, 5 nmol/L) was selected to pretreat the HUVECs for 30 min. Protein phosphatase 4 catalytic subunit (PP4c) siRNA or protein phosphatase 2A catalytic subunit (PP2Ac) siRNA was transfected into the HUVECs. The protein expression levels of of eNOS, PP4c and PP2Ac, as well as the level of eNOS Ser633 phosphorylation, were detected by Western blot. The intracellular nitric oxide (NO) content was measured by DAF-FM DA. RESULTS(1) Compared with control group, the levels of eNOS Ser633 phosphorylation were decreased in PA groups in which the HUVECs were treated with 25 μmol/L, 50 μmol/L, 100 μmol/L and 200 μmol/L PA for 36 h (P<0.05) and 100 μmol/L PA for 24 h, 36 h and 48 h (P<0.05). No significant difference in the level of total eNOS protein expression among all the groups was observed. (2) Compared with control group, both FST and OA pretreatment reversed the reduction of eNOS Ser633 phosphorylation (P<0.05) and the decrease in intracellular NO content (P<0.05) induced by PA. No significant difference in the level of total eNOS protein expression among all the groups was observed. (3) Compared with si-Control group, the PP4c protein expression was significantly reduced (P<0.05), while the level of eNOS Ser633 phosphorylation was significantly increased in si-PP4c group (P<0.05). Although the levels of PP2Ac protein expression declined significantly (P<0.05), the level of eNOS Ser633 phosphorylation remained unchanged in si-PP2Ac group. No significant differencein the level of total eNOS protein expression among all the groups was found. CONCLUSION PA significantly reduces the level of eNOS Ser633 phosphorylation and the content of NO in the HUVECs, which may be due to PA inducing the activation of the PP2A family member PP4 rather than PP2A.     

AHV-PI attenuates endothelial cell injury induced by LPS

AIM:To investigate the effect of platelet inhibitor from Agkistrodon halys venom (AHV-PI) on lipopolysaccharide (LPS) induced human umbilical vein endothelial cells (HUVECs) injury in vitro, and to explore its mechanism. METHODS:Cultured HUVECs were induced inflammatory injury by LPS (1 mg/L). The experiment was divided into blank control group, LPS group, AHV-PI group and AHV-PI+LPS group. The viability of HUVECs was measured by MTT assay. The morphological changes of HUVECs were observed under inverted microscope. The optimum concentration of AHV-PI at 5 mg/L was selected. Flow cytometry was used to detect apoptosis of HUVECs. Immunohistochemical method was used to observe the expression of tissue type plasminogen activator (t-PA) and plasminogen activator indhibitor-1 (PAI-1) of HUVECs. ELISA was used to detect the concentrations of intercellular adhesion molecule-1 (ICAM-1) and tissue factor (TF) in the supernatant. The activation and translocation of NF-κB subunit p65 were observed by immunofluorescence staining. RESULTS:The HUVECs were spindle shaped, the ratio of length to width was increased, the cells were fibroblast-like, and granular substance appeared in the cytoplasm in LPS group. The viability and morphological changes of HUVECs were not significantly affected as treated with AHV-PI at concentration of 0~5 mg/L, but the viability of HUVECs induced by LPS was inhibited and the morphological changes were alleviated. Compared with the blank control group, the levels of TF and ICAM-1 in the supernatant increased, and the expression of t-PA and PAI-1 in the HUVECs was decreased in LPS group. Compared with the LPS group, the contents of TF and ICAM-1 in the supernatant were significantly decreased, the expression of t-PA and PAI-1 in the HUVECs was increased and the expression of nucleus NF-κB p65 was decreased in AHV-PI+LPS group (P<0.05). CONCLUSION:AHV-PI reduces HUVECs damage. The protective mechanism is related to the inhibition of cytokine secretion and NF-κB activation.     

Hydrogen sulfide attenuates human umbilical vein endothelial cell senescence via modulation of Sirt1/eNOS pathway

AIM: To explore the role of Sirt1/eNOS signalling pathway in the protective effect of hydrogen sulphide (H₂S) against endothelial cell senescence induced by high glucose.METHODS: High glucose (33 mmol/L) was applied to induce senescence in primary human umbilical vein endothelial cells (HUVECs). The cell viability, the proportion of senescence-associated β-galactosidase (SA-β-Gal) positive cells and the plasminogen activator inhibitor 1 (PAI-1) expression were detected to assess the senescence model. Mean while, Sirt1 siRNA was used to examine the effect of Sirt1 on eNOS expression and the senescence-related parameters.RESULTS: Treatment of HUVECs with high glucose decreased the cell viability slowly with a larger proportion of the cells stained with SA-β-Gal, and the protein expression of PAI-1 was dramatically increased. The increased cell viability, reduced SA-β-Gal positive cells and decreased protein expression of PAI-1 were detected after sodium hydrosulfide (NaHS, 100 μmol/L) treatment. Furthermore, NaHS treatment upregulated the protein expression of Sirt1 and eNOS, and eventually increased the production of nitric oxide (NO).CONCLUSION: Exogenous H₂S modulates Sirt1/eNOS/NO pathway to prevent HUVECs against high glucose-induced senescence.     

Effects of folic acid and vitamin B12 on human umbilical vein endothelial cells against homocysteine-induced apoptosis

AIM: To investigate the effect of folic acid and vitamin B₁₂ on homocysteine (Hcy)-induced apoptosis of human umbilical vein endothelial cells (HUVECs) through mammalian sterile 20-like kinase 1 (MST1). ME-THODS: HUVECs were cultured in the absence (control group), or presence of 100 μmol/L Hcy alone (Hcy group) or 100 μmol/L Hcy plus 30 μmol/L folic acid and vitamin B₁₂ (intervention group) for 72 h. The effect of Hcy on the apoptosis of HUVECs was analyzed by flow cytometry. The transfection efficiency of DNA methyltransferase 1 (DNMT1)-overexpressing adenovirus was observed under fluorescence inverted microscope. The mRNA and the protein levels of DNMT1 and MST1 were determined by RT-qPCR and Western blot. The DNA methylation level of MST1 promoter was detected by methylation-specific PCR. RESULTS: Compared with control group, the apoptotic rate (P<0.01) and the expression of MST1 at mRNA (P<0.01) and protein (P<0.05) levels in the HUVECs were significantly increased, while the mRNA levels of DNMT1 was decreased in Hcy group (P<0.01). In addition, folic acid and vitamin B₁₂ treatment significantly inhibited Hcy-mediated apoptosis of HUVECs (P<0.01), increase in MST1 mRNA level (P<0.01) and decrease in DNMT1 mRNA level (P<0.01). Meantime, the mRNA level of MST1 was positively correlated with the apoptotic rate of the HUVECs (r=0.943 9, P<0.001). The expression of DNMT1 at mRNA and protein levels was significantly increased after the transfection of DNMT1-overexpressing adenovirus into HUVECs (P<0.01), and a large amount of green fluorescent protein expression was observed. Meanwhile, the DNA methylation level of MST1 promoter was increased (P<0.01), while the protein level of MST1 was decreased (P<0.01).CONCLUSION: Up-regulation of MST1 promotes Hcy-induced apoptosis of HUVECs, while folic acid and vitamin B₁₂ exert an anti-apoptosis effect, which might be regulated by hypermethylation of MST1 promoter region.     

Role of SIRT1/eNOS/NO signaling pathway in protective effect of ginsenoside Rb1 against replicative senescence of endothelial cells

AIM: To explore the effect of ginsenoside Rb1 on replicative senescence of endothelial cells and the role of SIRT1/eNOS/NO signaling pathway in this process. METHODS: The replicative senescence model of primary human umbilical vein endothelial cells (HUVECs) was established. The morphological change of the cells, the proportion of senescence-associated β-galactosidase (SA-β-Gal) positive cells and the plasminogen activator inhibitor 1 (PAI-1) expression were detected to assess the senescence model. The expression of eNOS and PAI-1 at mRNA and protein levels in the aging cells was determined by real-time PCR and Western blot before and after silencing of SIRT1 was performed. The NO concentration in the cell culture supernatant was measured by nitrate reductase assay. RESULTS: HUVECs with cumulative population-doubling level (CPDL) at 16 were chosen as the replicative senescence model in this research. Ginsenoside Rb1 at 80 μmol/L significantly reduced the expression of PAI-1 at mRNA and protein levels. Furthermore, ginsenoside Rb1 increased the expression of SIRT1 and eNOS at mRNA and protein levels, and increased the NO content. SIRT1 silencing inhibited the expression of eNOS at mRNA and protein levels and reduced NO generation, leading to an increase in the expression of PAI-1 at mRNA and protein levels. Upon intervention of ginsenoside Rb1, the eNOS and PAI-1 expression and the level of NO were not reversed. CONCLUSION: Ginsenoside Rb1 modulates SIRT1/eNOS/NO signaling pathway to prevent the replicative senescence of HUVECs.     

Hydrogen sulfide ameliorates high glucose-induced endothelial cell senescence by suppressing oxidative stress

AIM：To explore the effect of hydrogen sulfide on the senescence of human umbilical vein endothelial cells (HUVECs) induced by high glucose. METHODS：Senescence model was established by treating HUVECs with 33 mmol/L glucose for 48 h. The parameters were detected to demonstrate the effect of hydrogen sulfide on senescence and the mechanism involved was also investigated. RESULTS：In the cells treated with high glucose, the proliferation was attenuated with a higher number of senescence-associated β-galactosidase (SA-β-Gal) positive cells, and plasminogen activator inhibitor 1 (PAI-1) protein expression, malondialdehyde (MDA) production and NF-κB p65 activity were increased significantly, but the expression of superoxide dismutase 1 (SOD1) was decreased. However, the cell number and SOD1 expression were increased, and the number of SA-β-Gal positive cells, PAI-1 protein expression, MDA production and the activity of NF-κB p65 were decreased after sodium hydrosulfide (100 and 200 μmol/L) treatment.CONCLUSION：Exo-genous hydrogen sulfide prevents HUVECs against high glucose-induced senescence by suppressing oxidative stress and NF-κB p65 activity.     

Effects of high hydrostatic pressure on ADMA metabolism in human vascular endothelial cells and the role of RAS

AIM:To observe the effects of high hydrostatic pressure on asymmetric NG, NG-dimethyl-L-arginine (ADMA) metabolism of human vascular endothelial cells (HUVECs), and the role of renin-angiotensin system (RAS). METHODS:Cultured HUVECs of 3-6th passage were exposed to atmosphere (0 mmHg, APC), 120 mmHg (MPC), 180 mmHg (HPC). There were three groups in each pressure condition, one as control, the other two were interfered with captopril （Cap, 10 μmol/L or 100 μmol/L） or irbesartan （Irb, 10 μmol/L or 100 μmol/L） respectively. Cell proliferation was quantified by determining hexosaminidase activity at 12 h. Concentration of ADMA in conditioned medium was measured by high performance liquid chromatography (HPLC) at 12 h. RESULTS:Compared with APC group, ADMA concentration increased prominently in MPC and HPC (4.69±0.37 and 4.48±0.39 vs 0.75±0.05，P<0.01), but no difference was found between MPC and HPC group. ADMA concentration was not influenced by Cap and Irb in APC, but obviously reduced in MPC and HPC in a dose-dependent manner. CONCLUSION:ADMA is upregulated by high hydrostatic pressure and RAS is involved.     

Puerarin pretreatment protects human umbilical vein endothelial cells against hypoxia/reoxygenation injury via increasing protein expression of endothelial nitric oxide synthase

AIM: To investigate the protective effects of puerarin (PUE) pretreatment on hypoxia/reoxygenation (H/R) injury in human umbilical vein endothelial cells (HUVECs), as well as its possible mechanism and the signal transduction pathways involved. METHODS: HUVECs were randomly divided into normal control group, H/R group, PUE pretreatment group and PUE+H/R group (1.0×10^-3 mol/L, PUE pretreated the cells for 24 h before H/R). The protein expression of endothelial nitric oxide synthase (eNOS) was measured by Western blot. The activity of constitutive NOS (cNOS) was determined via chemical colorimetric methods. Apoptosis of HUVECs was detected by TUNEL assay. In addition, the cells were treated with ERK inhibitor U0126 (1.0×10^-5 mol/L) or PKB/Akt inhibitor LY294002 (5.0×10^-5 mol/L) for 1 h before PUE pretreatment, and then H/R was performed.RESULTS: Compared with control group, H/R decreased the protein expression of eNOS (P<0.05), and PUE pretreatment up-regulated it (P<0.05). This effect of PUE was inhibited by U0126 or LY294002 (P<0.05). Compared with control group, the activity of cNOS decreased in H/R group (P<0.05), while it increased after PUE pretreatment (P<0.05). Compared with control group, the apoptotic index significantly increased in H/R group (P<0.01). PUE pretreatment reduced the apoptotic index (P<0.01). CONCLUSION: H/R decreases the protein expression and enzyme activity of eNOS in HUVECs, and induces apoptosis of HUVECs. PUE pretreatment up-regulates the protein expression and enzyme activity of eNOS, and reduces the apoptosis of HUVECs with H/R injury. The protective effect of PUE might be through increasing eNOS protein expression via ERK1/2 and PKB/Akt signaling pathways.     

Effects of oxidative modification of lipoproteins on blood coagulation and fibrinolysis

AIM: To study the effects of oxidative modification lipoproteins on blood coagulation and fibrino-lysis in vitro. METHODS: Normal human plasma VLDL, LDL and HDL, which were isolated by density gradient ultracentrifugation method, were oxidatively modified by Cu²⁺ and HOCl method. N-VLDL, Ox-VLDL, N-LDL, Ox-LDL, N-HDL, Ox-HDL were added to the reaction system which consisted of mixed fresh normal plasma respectively, prothrombin time (PT), activated partial thrombplastin time (APTT), plasminogen activator inhibitor 1 (PAI-1), tissue plasminogen activator (t-PA) and platelet aggregation were measured according to the direction of the kits. RESULTS: The relative electrophoretic mobility (REM), absorbance at 234nm and TBARS of oxidized VLDL, LDL and HDL mediated by HOCl or Cu²⁺ were significantly higher than that of the control group (P<0.01). N-VLDL, N-LDL and N-HDL had no effect on PT, APTT, t-PA, PAI-1 and platelet aggregation. The PT and APTT of Ox-VLDL, Ox-LDL and Ox-HDL were significantly shorter than that of the control group (P<0.05 and P<0.01). The platelet aggregation of Ox-VLDL, Ox-LDL and Ox-HDL were significantly stronger than that of the control group (P<0.01). The Ox-VLDL and Ox-LDL were higher in t-PA and lower in PAI-1 than that of the control group (P<0.05 and P<0.01), but the Ox-HDL had no influences on t-PA and PAI-1 activity. CONCLUSIONS: N-VLDL, N-LDL and N-HDL have no effects on blood coagulation and fibrinolysis in vitro. Ox-VLDL, Ox-LDL and Ox-HDL enhance blood coagulation and thrombosis. Ox-VLDL and Ox-LDL enhance t-PA activity and decreased PAI-1 activity, but Ox-HDL does not affect the fibrinolysis activity.     

Effects of miR-30c on viability and migratory ability of HUVECs by targeting PAI-1

AIM: To investigate the effect of microRNA (miR)-30c on the viability and migratory ability of human umbilical vein endothelial cells (HUVECs) by targeting plasminogen activator inhibitor-1 (PAI-1).METHODS: The HUVECs were transfected with miR-30c mimic and inhibitor or negative control (NC), and then the expression levels of miR-30c, PAI-1 mRNA and protein were detected by RT-qPCR and Western blot. The viability and migratory ability of HUVECs were measured by CCK-8 assay and wound healing test. After bioinformatic analysis, the assessment of miR-30c binding to PAI-1 3'-UTR was carried out using a luciferase reporter gene assay. RESULTS: miR-30c directly down-regulated PAI-1 levels by binding to the 3' UTR seed sequence of PAI-1 mRNA. Furthermore, transfection of a miR-30c mimic down-regulated the expression of PAI-1 at mRNA and protein levels, leading to enhanced migratory ability and viability of the HUVECs. However, transfection of a miR-30c inhibitor up-regulated the expression of PAI-1 at mRNA and protein le-vels, leading to decreased migratory ability and viability. CONCLUSION: Regulation of miR-30c level changes the migratory ability and viability of HUVECs by affecting the PAI-1 expression, indicating the involvement of miR-30c in modulating endothelial function.     

Limb ischemic preconditioning protects human umbilical vein endothelial cells from oxidative stress induced by H2O2

AIM: To investigate the effects of the sera from the rats after limb ischemic preconditioning (LIPC) on human umbilical vein endothelial cells (HUVECs) injured by hydrogen peroxide (H₂O₂). METHODS: The HUVECs were divided into 5 groups: the cells in control group were cultured without any intervention; the cells in model group (M) were damaged by 1 mmol/L H₂O₂ for 2 h; the cells in early preconditioning serum (EPS) group, delayed preconditioning serum (DPS) group or sham limb ischemic preconditioning serum (SPS) group were treated with the corresponding serum at 5% for 12 h, respectively, and then treaed with H₂O₂ for 2 h. The viability of the HUVECs was analyzed by flow cytometry. The lactate dehydrogenase (LDH) in the culture media was detected. The cell adhesion molecules in the HUVECs were detected by real-time PCR. The mRNA and protein expression of heme oxygenase-1 (HO-1) was also determined. RESULTS: The viability of HUVECs incubated with 1 mmol/L H₂O₂ for 2 h significantly decreased compared with the control cells, which was accompanied with the augmentations of LDH in the medium and the cell adhesion molecules in cells, such as vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1). Preincubation with EPS and DPS derived from the rats subjected LIPC attenuated these injuries. Furthermore, pretreatment with EPS and DPS increased the expression of HO-1 at mRNA and protein levels. CONCLUSION: LIPC protects the HUVECs from H₂O₂-induced injury.     

Effects of advanced glycation end products on protein and mRNA expression of macrophage inflammatory protein-1α in cultured human umbilical vein endothelial cells

AIM: To investigate the effects of advanced glycation end products (AGEs) on protein and mRNA expression of macrophage inflammatory protein-1α (MIP-1α) in cultured human umbilical vein endothelial cells(HUVECs). METHODS: HUVECs were cultured with AGEs at different concentrations for 24 h and at a concentration of 400 mg/L for different time.The levels of mRNA and protein expression of MIP-1α in cultured HUVEC were detected by in situ hybridization and Western blot, respectively. RESULTS: In situ hybridization showed that after exposure of HUVECs to AGEs at different concentrations (100 mg/L, 200 mg/L, 400 mg/L) for 24 h, the average integrated optical density values (18.76±3.17, 26.58±1.61, 34.23±2.25) of MIP-1α mRNA expression in HUVECs were higher than that in control group (13.83±1.24, P0.05). After exposure of HUVECs to AGEs at a concentration of 400 mg/L for 12 h, 24 h and 36 h, the average integrated optical density values of MIP-1α mRNA expression in HUVECs were 22.67±1.46, 34.23±2.25 and 42.28±3.14, higher than that in 0 h group (12.56±1.24, P0.05). Western Blot showed that exposure of HUVECs to AGEs at different concentrations(100 mg/L, 200 mg/L, 400 mg/L) for 24 h resulted in a 1.34-fold, 1.87-fold and 2.46-fold increase in the expression of MIP-1α protein in HUVECs compared with BSA control group (P<0.05). Meanwhile, exposure of HUVECs to AGEs at a concentration of 400 mg/L for 12 h, 24 h and 36 h resulted in a 1.82-fold, 2.71-fold and 3.34-fold increase in MIP-1α protein expression in HUVECs compared with 0 h group (P<0.05). CONCLUSION:These data suggest that AGEs could induce a high expression of MIP-1αmRNA and protein in cultured HUVECs in a dose-dependent and time-dependent manner.     

Effects of simvastatin on cigarette smoke extract-induced sEPCR and EPCR expression in human umbilical vein endothelial cells

AIM: To investigate the effects of simvastatin on cigarette smoke extract (CSE)-induced expression levels of soluble endothelial cell protein C receptor (sEPCR) and membrane-associated endothelial cell protein C receptor (mEPCR ) in human umbilical vein endothelial cells (HUVECs). METHODS: Cultured HUVECs at passage 4 to 6 were randomly divided into control group, 5% CSE group, simvastatin groups and simvastatin+CSE groups. In simvastatin groups, HUVECs were incubated with simvastatin at the concentrations of 50, 100 and 200 μmol/L for 24 h. In simvastatin+CSE groups, the cells were treated with simvastatin at the concentrations of 50, 100 and 200 μmol/L for 2 h, and then exposed to CSE for 24 h. The protein level of sEPCR in the culture supernatants was measured by ELISA. The cells were collected for determining the mRNA expression of mEPCR by real-time PCR. RESULTS: Compared with control group, the protein level of sEPCR was significantly increased, and the mRNA expression of mEPCR was significantly decreased in 5% CSE group (both P<0.05). The protein levels of sEPCR were significantly increased, and the mRNA expression of mEPCR was significantly decreased in 100 μmol/L and 200 μmol/L simvastatin groups. However, the protein levels of sEPCR were lower, and the mRNA expression of mEPCR was significantly higher in 100 μmol/L and 200 μmol/L simvastatin groups than those in 5% CSE group. Compared with 5% CSE group, the protein levels of sEPCR in simvastatin+CSE groups were significantly decreased, but higher than those in control group and simvastatin group with corresponding concentration. On the contrary, the mRNA expression of mEPCR in simvastatin+CSE groups was significantly increased, but lower than that in control group and simvastatin group with corresponding concentration (all P<0.05). CONCLUSION: Simvastatin obviously increases the mRNA expression of mEPCR, decreases the protein level of sEPCR, and attenuates the CSE-induced endothelial injury in vitro .     

2,3,5,4’-Tetrahydroxystilbene-2-O-β-D-glucoside protects against LPC-induced endothelial cell injury

AIM: To observe the protective effect of 2,3,5,4’-tetrahydroxystilbene-2-O-β-D-glucoside (TSG) on lysophosphatidylcholine (LPC)-induced vascular endothelial cell injury. METHODS: The 3rd and 4th generations of human umbilical vein endothelial cells (HUVECs) were cultured in vitro and propagated. The cells were randomly divided into 3 groups: control group, model group (LPC) and experimental group (TSG+LPC). The cells in control group were not treated with any reagent. To establish endothelial cell injury model, LPC was administered to HUVECs at concentration of 10 mg/L and incubated with the cells for 24 h. In TSG+LPC group, TSG was administered to HUVECs at concentrations of 10.0, 1.0 and 0.1 μmol/L 1 h before administration of LPC, and then the cells were incubated for 24 h. The cell viability, the content of asymmetric dimethyl arginine (ADMA) and NO, and apoptotic rate were detected. RESULTS: Compared with control group, ADMA content in the cell culture supernatants and apoptotic rate of the HUVECs in LPC group were significantly increased, while the NO content and cell viability were notably decreased. Compared with LPC group, ADMA content and apoptotic rate in TSG+LPC group was significantly decreased, while the NO content and cell viability were notably increased. CONCLUSION: TSG may protect LPC-injured vascular endothelial cells by attenuating the expression of ADMA and enhancing the production of NO, thus inhibiting apoptosis and increasing cell survival rate.     

Inhibition of HMGB1 expression and release by nicotine in RAW264.7 cells

AIM: To investigate that nicotine inhibits HMGB1 expression and release in RAW264.7 cells.METHODS: (1) RAW264.7 cells were cultured in 6 wells plate, treated with 250 μg/L LPS and 1 μmol/L or 10 μmol/L nicotine, in which the cells treated with or without 250 μg/L LPS were regarded as nicotine 1 group (N1), nicotine 2 group (N2), LPS group (LPS) and control group (C), respectively. HMGB1 protein in the cell culture media and in cell nuclear was examined by Western blotting and the cellular HMGB1 mRNA level was detected by RT-PCR. (2) Transfected with antisense RNA or sense RNA of α7 subunit-containing nicotinic receptor (α7nAChR), RAW264.7 cells were treated with 250 μg/L LPS and 10 μmol/L nicotine, HMGB1 protein in the culture media was also tested by Western blotting.RESULTS: (1) HMGB1 mRNA level in C group was low (1 659.20±121.05) and no significant statistical difference among groups of N1, N2 and LPS was observed (P>0.05). (2) Higher HMGB1 accumulation in the cell culture media was detected in LPS group (445.34±28.52) than that in C group. Compared to LPS group, both N1 and N2 groups distinctly attenuated HMGB1 accumulation in culture media (P<0.05). (3) Nuclear HMGB1 accumulation was lower in LPS group than that in C group, and two different nicotine concentrations markedly increased the nuclear HMGB1 accumulation compared to LPS group (P<0.05). (4) No significant difference of HMGB1 levels in culture media between antisense RNA group and LPS group was observed (P>0.05). In sense RNA group, however, HMGB1 level was observably reduced compared to antisense group (P<0.05).CONCLUSION: The present results suggest that nicotine dramatically inhibits RAW264.7 cell nuclear HMGB1 translocation and extracellular release, and this effect relies on α7nAch receptor expression.     

Effects of oxidized HDL on the levels of MCP-1, ICAM-1 and free calcium in cultured human umbilical venous endothelial cells

AIM:To study the effects of oxidized high-density lipoprotein (oxHDL) on the expression of monocyte chemoattractant protein-1(MCP-1) and intercellular adhesion molecule-1(ICAM-1) and intracellular free calcium concentration ([Ca²⁺]i) level in cultured human umbilical venous endothelial cells(HUVECs). METHODS:The MCP-1 protein content in the medium of conditioned HUVEC was measured by ELISA, and the ICAM-1 on HUVECs was detected by indirect immunofluorescence, and [Ca²⁺]i was determined by Fluo-3/AM, the injury of cells was observed by scanning electron microscopy (SEM).RESULTS:oxHDL could induce the expression of MCP-1 and ICAM-1 in HUVECs. In oxHDL group (HUVECs were incubated with 100 mg protein/L oxHDL for 24 h), the levels of MCP-1, ICAM-1 and [Ca²⁺]i increased by 160%, 60% and 70% respectively compared with the control group (P＜0.01). When HUVECs were incubated with 300 mg protein/L oxHDL for 24 h, cells were injured obviously. CONCLUSION:By inducing the expression of ICAM-1 and MCP-1 in endothelial cells, oxHDL may promote monocyte-endothelium adhesion and monocyte migration to intima, it may promote atherosclerosis as oxidized low-density lipoprotein (oxLDL).