Effect of Chinese propolis on PC-PLC activity and TLR4 expression in LPS-treated vascular endothelial cells

AIM: To investigate the effect of Chinese propolis on the activity of phosphatidylcholine-specific phospholipase C (PC-PLC) and the expression of Toll-like receptor 4 (TLR4) in LPS-treated vascular endothelial cells (VECs). METHODS: Confluent VECs were stimulated with LPS at the concentration of 100 μg/L in the presence of 0.5% fetal bovine serum. The cells were treated with Chinese propolis at the concentration of 12.5 mg/L for 12 h and 24 h. The viability of VECs and the level of nitric oxide (NO) were detected by sulforhodamine B (SRB) assay and chemical method, respectively. The activity of PC-PLC was measured using L-α-phosphatidylcholine as substrate. The protein levels of TLR4, nuclear factor-κB p65 (NF-κB p65) and p53 were determined by Western blotting. The level of intracellular reactive oxygen species (ROS) was examined using a fluorescent probe, 2,7-dichlorodihydrofluorescin (DCHF). For the measurement of mitochondrial membrane potential, the fluorescent dye JC-1 was used. RESULTS: Treatment with Chinese propolis for 24 h had no effect on the viability of VECs. However, the levels of NO and ROS were significantly decreased by Chinese propolis. PC-PLC activity and NF-κB p65 expression were significantly depressed by Chinese propolis treated for 12 h, and the expression of TLR4 and p53 were dramatically decreased by Chinese propolis treated for 12 and 24 h. No effect of Chinese propolis on mitochondrial membrane potential was observed. CONCLUSION: Chinese propolis depresses the activity of PC-PLC and the expression of TLR4, and then inhibits the downstream signal molecules such as NF-κB p65, p53, ROS and NO in VECs.     

Involvement of TLR4/NLRP3 inflammasome in contrast medium-induced inflammation and injury in renal tubular epithelial cells

AIM: To investigate whether Toll-like receptor 4 (TLR4) and Nod-like receptor protein 3 (NLRP3) inflammasome were involved in contrast medium (CM)-induced inflammation and injury in renal tubular epithelial cells. METHODS: Iopromide was used to injure NRK-52E cells in the study. The cell viability was measured by CCK-8 assay. The protein levels of TLR4, NLRP3, apoptosis-associated speckle-like protein (ASC), caspase-1 and cleaved caspase-3 were determined by Western blot. The releases of interleukin (IL)-1β and IL-18 were detected by ELISA. The apoptotic rate was evaluated by Hoechst staining, and mitochondrial membrane potential (MMP) was analyzed by JC-1 staining. siRNA was transfected into the NRK-52E cells to silence NLRP3 expression. RESULTS: CM decreased the viability of NRK-52E cells (P<0.05). CM also elevated the protein levels of cleaved caspase-3, TLR4, NLRP3, IL-1β and IL-18 (P<0.05). Silencing NLRP3 attenuated CM-induced releases of inflammatory cytokines. Moreover, treatment with TLR4 inhibitor TAK-242 or knockdown of NLRP3 by siRNA transfection both attenuated cell apoptosis and loss of MMP caused by CM. CONCLUSION: TLR4/NLRP3 inflammasome takes part in the pathogenesis of CM-induced acute kidney injury, and mediates CM-induced injury and inflammation in renal tubular epithelial cells.     

Xiaozhong-Zhitong mixture attenuates hypoxic damage of vascular endothelial cells in rats via VEGF-Dll4/Notch signaling pathway

AIM: To study the effect of Xiaozhong (detumescence)-Zhitong (analgesia) mixture on the function of vascular endothelial cells of rat skin flaps and the expression of VEGF-Dll4/Notch signaling pathway-related proteins. METHODS: Vascular endothelial cells of rat skin flaps were isolated and cultured. The cells were divided into control group, hypoxia group, hypoxia+detumescence analgesia group, hypoxia+detumescence analgesia+axitinib (VEGF receptor inhibitor) group, and hypoxia+detumescence analgesia+MK-0752 (Notch signaling pathway blocker) group. The serum levels of VEGF were measured by ELISA. The number of dead and living cells at 1 d, 2 d and 3 d after hypoxia was determined by cell calcein-AM and PI double staining. The protein expression levels of VEGF-A, Notch and Dll4 in the cells at 24 h and 48 h were detected by Western blot. RESULTS: Compared with control group, the content of VEGF was increased significantly after 24 h and 48 h, and the protein expression of VEGF-A, Notch and Dll4 was increased significantly (P<0.05). Compared with hypoxia group, the content of VEGF was increased significantly after the intervention of Xiaozhong-Zhitong mixture, the death rate was decreased significantly, and the protein expression of VEGF-A, Notch and Dll4 was increased significantly (P<0.05). Compared with Xiaozhong-Zhitong mixture group, the protective effect of Xiaozhong-Zhitong mixture on hypoxia-induced vascular endothelial cell injury was weakened by VEGF receptor inhibitor, the cell mortality was significantly increased, the content of VEGF was decreased, and the protein expression of VEGF-A, Notch and Dll4 was decreased (P<0.05). After intervention with Notch signaling pathway blocker, the cell viability remained unchanged, the expression level of VEGF-A was increased, and the increased Notch and Dll4 protein expression was effectively resisted (P<0.01). CONCLUSION: Xiaozhong-Zhitong mixture improves the function of vascular endothelial cells of rat skin flaps, and its mechanism may be related to the influence of the signal transduction pathway of VEGF-Dll4/Notch.     

Ethanol extract of propolis protects vascular endothelial cells from oxidized low-density lipoprotein-induced apoptosis by inhibiting C/EBP homologous protein expression

AIM: To investigate the inhibitory effect of ethanol extract of propolis (EEP) on oxidized low-density lipoprotein (ox-LDL)-induced vascular endothelial cell apoptosis and the underlying molecular mechanisms.METHODS: Human umbilical vein endothelial cells (HUVECs) were pretreated with EEP (7.5, 15 and 30 mg/L) or 4-phenylbutyric acid (PBA, 4 mmol/L) for 1 h and then treated with ox-LDL (100 mg/L) or tunicamycin (TM, 4 mg/L) for 24 h. The cell viability and apoptosis were determined by MTT assay and Annexin V-FITC/PI double staining, respectively. The activities of lactic dehydrogenase (LDH) in the medium and caspase-3 in the HUVECs were measured. The protein and mRNA levels of C/EBP homologous protein (CHOP), a proapoptotic molecule under endoplasmic reticulum stress (ERS), and its downstream Bcl-2 were examined by Western blot and real-time PCR, respectively.RESULTS: Like PBA (an ERS inhibitor), EEP protected HUVECs from ox-LDL-induced injury in a dose-dependent manner, as assessed by the increased cell viability and the decreased LDH release, apoptotic rate and caspase-3 activation. The decrease in cell viabi-lity and the increases in LDH release, apoptotic rate and caspase-3 activation induced by TM, an ERS inducer, were also attenuated by EEP. Moreover, EEP suppressed ox-LDL-induced CHOP upregulation and Bcl-2 downregulation, and this effect was similar to that of PBA. Similarly, EEP significantly suppressed TM-induced CHOP upregulation both at the protein and mRNA levels.CONCLUSION: EEP may protect HUVECs from ox-LDL-induced apoptosis, and the mechanism is at least partially involved in suppressing CHOP-mediated ERS-associated apoptotic pathway.     

Effect of protein kinase C signal pathway on resistin expression in 3T3-L1 adipocytes

AIM：To investigate the effect of protein kinase C on resistin expression in 3T3-L1 adipocytes.METHODS：The differentiated 3T3-L1 adipocytes were incubated with 50 nmol/L phorbol 12-myristate 13-acetate (PMA) or 5 μmol/L Ro-31-8220 for 24 h.Expression of resistin mRNA was detected by RT-PCR and expression of resistin protein was detected by Western blotting.RESULTS：Compared with control,PMA increased the expression of resistin mRNA and protein in 3T3-L1 adipocytes significantly (P<0.01),while Ro-31-8220 decreased the expression of resistin mRNA and protein in 3T3-L1 adipocytes obviously (P<0.01).CONCLUSION：Protein kinase C signal pathway may regulate resistin expression in 3T3-L1 adipocytes.     

Role of PI3K/Akt/eNOS signaling pathway in inhibitory effects of puerarin on ox-LDL-induced TF expression in vascular endothelial cells

AIM:To explore the role of phosphatidylinositiol 3-kinase/protein kinase B/endothelial nitric oxide synthase (PI3K/Akt/eNOS) signaling pathways in the inhibitory effects of puerarin on oxidized low-density lipoprotein (ox-LDL)-induced tissue factor (TF) expression in vascular endothelial cells.METHODS:The mRNA expression of TF was detected by real-time fluorescent quantitative PCR.The protein levels of TF and Akt was determined by Western blot.The content of the nitric oxide (NO) was measured by nitrate reduction method.RESULTS:Compared with control group,incubating endothelial cells with ox-LDL significantly induced TF expression at mRNA and protein levels and the dephosphorylation of Akt protein,and decreased NO production.Incubation of the endothelial cells with puerarin for 1 h and then treatment of the cells with ox-LDL decreased the TF expression at mRNA and protein levels,increased Akt protein phosphorylation and intracellular NO content.Co-incubation of the endothelial cells with PI3K inhibitor LY294002 and puerarin for 1 h and then treatment of the cells with ox-LDL augmented the TF expression at mRNA and protein levels and the Akt protein dephosphorylation,and decreased NO production.Co-incubation of the endothelial cells with eNOS inhibitor N^G-nitro-L-arginine methyl ester (L-NAME) and puerarin significantly decreased the inhibitory effect of puerarin on ox-LDL-induced TF expression at mRNA and protein levels in the endothelial cells,and reduced Akt protein phosphorylation and NO production.CONCLUSION:Puerarin inhibits ox-LDL-induced TF expression at mRNA and protein levels in the human umbilical vein endothelial cells via activation of PI3K/Akt/eNOS signaling pathway.     

Protective effect of paeoniflorin on nerve cells in APP/PS1 mice and its mechanism

AIM: To investigate the therapeutic and preventive effects of paeoniflorin (PF) on APP/PS1 mice, and to explore the possible mechanism. METHODS: Fifteen male 5-month-old APP/PS1 non-dominant mice were chosen as normal control group, 15 male 5-month-old APP/PS1 double transgenic mice were used as model group, and 15 male 5-month-old APP/PS1 double transgenic mice treated with 5 mg/kg PF by intraperitoneal injection were allocated in administation group. The learning and memory ability of the mice in each group was detected by Morris water maze. The apoptosis was assessed by TUNEL fluorescence staining. The protein expression of PI3K, Akt, p-PI3K, p-Akt, caspase-3, caspase-9, Bcl-2 and Bax in cerebral cortex and hippocampus was detected by Western Blot. The protein expression levels and distribution of caspase-3 and caspase-9 were detected by immunohistochemistry. RESULTS: (1) Compared with normal control group, the learning and memory ability declined in APP/PS1 model group. Compared with APP/PS1 model group, PF obviously improve the ability of learning and memory in mice. (2) Compared with normal control group, the apoptosis of nerve cells in APP/PS1 model group significantly increased and distributed in wider areas, while that in PF group was reduced (P<0.05). (3) Compared with APP/PS1 model group, PF could significantly lower pro-apoptotic factors, caspase-3, caspase-9 and Bax (P<0.05), and increase the expression of anti-apoptotic factors, p-PI3K, p-Akt and Bcl-2 (P<0.05). CONCLUSION: PF can up-regulate the expression of Bcl-2 and down-regulate the expression levels of caspase-9, caspase-3 and Bax via the activation of PI3K/Akt pathway, thereby inhibiting the nerve cell apoptosis and protecting the nerve cells, so as to treat neurodegenerative diseases.     

Effect of Tripterygium wilfordii multiglucoside on intestinal flora and immune function in IgA nephropathy rats based on C1GALT1/Cosmc pathway

AIM To investigate the effects of Triptergium wilfordii multiglucoside （TWM） on intestinal flora and immune function in IgA nephropathy （IgAN） rats based on core 1 β1,3-galactosyltransferase （C1GALT1） and its chaperone protein Cosmc （C1GALT1/Cosmc pathway）. METHODS The rat model of IgAN was established, and the animals were randomly divided into model group （IgAN group）, dexamethasone （Dex） group and TWM group. Normal rats served as normal control （NC） group. The levels of serum creatinine （SCr） and blood urea nitrogen （BUN）, 24-hour urinary total protein （24 h UTP） and the number of urinary red blood cells were measured by automatic biochemical analyzer. The levels of serum IgA1, and plasma tumor necrosis factor-α （TNF-α）, B-cell activating factor （Baff） and interleukin-17 （IL-17） were detected by ELISA. The level of galactose-deficient IgA1 （Gd-IgA1） was detected by Vicia villosa lectin affinity ELISA. The intestinal colony was cultured in selective bacterial medium. The ratio of CD4⁺ CD25⁺ regulatory T cells （Treg） to CD4⁺ T cells （Treg proportion） in peripheral blood mononuclear cells （PBMC） was detected by flow cytometry.Western blot was used to determine the protein expression of C1GALT1 and Cosmc in intestinal mucosa. RESULTS Compared with NC group, 24 h UTP, the number of urinary red blood cells, SCr, BUN, serum IgA1 and Gd-IgA1, the numbers of Enterobacteriaceae, Enterococcus and Bacteroides, and the levels of TNF-α, Baff and IL-17 in plasma in IgAN group were significantly increased （P<0.05）, while the numbers of Bifidobacteria and Lactobacilli, the Treg proportion in PBMC, and the protein expression levels of C1GALT1 and Cosmc in intestinal mucosa were significantly decreased （P<0.05）. Compared with IgAN group, 24 h UTP, the number of urinary red blood cells, SCr, BUN, serum IgA1 and Gd-IgA1, the numbers of Enterobacteriaceae, Enterococcus and Bacteroides, and the levels of TNF-α, Baff and IL-17 in plasma in Dex group and TWM group were significantly reduced （P<0.05）, and those in TWM group were lower than those in Dex group （P<0.05）. Moreover, the numbers of Bifidobacteria and Lactobacilli, the Treg proportion in PBMC, and the protein expression levels of C1GALT1 and Cosmc in intestinal mucosa were significantly elevated （P<0.05）, and those in TWM group were higher than those in Dex group （P<0.05）. CONCLUSION TWM reduces the abnormal glycosylation level of IgA in IgAN rats by promoting the activation of C1GALT1/Cosmc pathway, and attenuates the intestinal flora disorder and immune dysfunction in IgAN rats, thus exerting the therapeutic effect.     

Effects of Danshensu on TGF-β1/Smads signaling pathways in rats with pulmonary fibrosis

AIM: To study the preventive and curative roles of Danshensu (DA) in bleomycin (BLM)-induced pulmonary fibrosis in rats. METHODS: Pulmonary fibrosis was induced in SD rats by intratracheal instillation of BLM. The rats were intraperitoneally injected with dexamethasone (1 mg·kg-1·d-1, DXM group), DA (15 mg·kg-1·d-1, DA group), or physiological saline (2 mL·d-1, BLM group). Normal controls (NC group) received physiological saline both intratracheally and intraperitoneally. At the 28th day after modeling, the histological changes of the lungs were evaluated by hematoxylin-eosin (HE) and Masson’s trichrome staining. The protein levels of α-smooth muscle actin (α-SMA) in the lung tissues were detected by the method of immunohistochemistry. The mRNA expression of transforming growth factor beta 1 (TGF-β1), Smad3 and Smad7 was assessed by real-time fluorescence quantitative PCR. RESULTS: Compared with BLM group, the degree of inflammation and fibrosis of the lung in DA group was obviously reduced, and so was the expression of α-SMA in the lung tissues. The mRNA expression of TGF-β1 and Smad3 in the lung tissues of the rats decreased and the mRNA expression of Smad7 increased. CONCLUSION: DA alleviates BLM-induced pulmonary fibrosis in rats in the early stage by inhibiting the expression of TGF-β1/Smad3 and stimulating the expression of Smad7 in the lung tissues.     

Inhibitory effects of right cervical sympathetic trunk transection on inflammatory response after acute myocardial infarction in rats and its influence on HMGB1/TLR4/NF-κB signaling pathway

AIM: To observe the effects of transection of right cervical sympathetic trunk (TCST) on inflammatory response and expression of high mobility group box 1 (HMGB1) and TLR4/NF-κB signaling pathway in the rats after acute myocardial infarction (AMI). METHODS: AMI model was established by ligation of left anterior descending coronary artery in SD rats, then the model rats were randomly divided into MI group and MI+TCST group. MI+TCST model was performed by transection of right cervical sympathetic trunk after left anterior descending coronary artery ligation. The rats in MI group and MI+TCST group were divided into 1, 3, 7, 14 and 28 d subgroups, and another sham operation group threading without ligation, with 8 rats in above each group. After modeling for 4 weeks, the cardiac function was measured by echocardiography. All rats were killed to harvest the hearts for mesuring cardiac hypertrophy index. The myocardial tissue close to infarction was observed with HE staining. The relative mRNA expression levels of HMGB1, tumor necrosis factor α(TNF-α) and interleukin (IL)-6 at different time points were detected by real-time PCR. The protein expression of HMGB1 and TLR4 at different time points after AMI was determined by Western blot. The effect of transection of right cervical sympathetic trunk on the expressions of HMGB1 and TLR4/NF-κB signaling pathway was also analyzed.RESULTS: Compared with the MI group, left ventricular ejection fraction (LVEF) and left ventricular shorterning fraction (LVFS) were significantly higher (P<0.05), left ventricular end-diastole dimension (LVEDd), left ventricular end-systole dimension (LVESd) and cardiac hypertrophy index were significantly lower (P<0.05), and the mRNA levels of HMGB1, TNF-α and IL-6 decreased significantly in MI+TCST group (P<0.05). Western blot results revealed that the protein expression level of HMGB1 increased in the infarct border zone at 3 d, and reached its peak at 7 d, then gradually decreased, and at 28 d after MI in MI group was still significantly higher than that in sham group (P<0.05). The protein expression of TLR4 was consistent with that of HMGB1. Transection of right cervical sympathetic trunk reduced protein expression of HMGB1 and TLR4/NF-κB signaling pathway-related proteins (P<0.05).CONCLUSION: Transection of right cervical sympathetic trunk improves ventricular remodeling and maintaining cardiac function. The mechanism may be related to inhibiting HMGB1/TLR4/NF-κB signaling pathway to reduce inflammatory response.