Pro-apoptotic role of NF-κB pathway inhibition in lipopolysaccharide stimulated polymorphonuclear neutrophils

Objective To investigate the role of nuclear factor kappa B (NF-κB) pathway inhibition in lipopolysaccharide (LPS)-stimulated apoptosis of polymorphonuclear neutrophils (PMNs).Methods Rats with acute lung injury induced by LPS intratracheal instillation and cultured human venous PMNs were studied. Pyrrolidine dithiocarbamate (PDTC) and gliotoxin were used as NF-κB inhibitors. Additionally, to explore the role of extracellularly regulated protein kinase as an upstream signal in NF-κB pathway on regulating LPS-stimulated PMN apoptosis, PD098059, the specific inhibitor of extracellularly regulated protein kinase, was also applied. The lung injury was determined by protein content and PMN numbers in bronchoalveolar lavage fluid. PMN apoptosis was measured by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) end labeling and DNA fragmentation. IκBα degradation was analyzed by Western blot. NF-κB DNA binding activity was detected by an electrophoretic mobility shift assay.Results (1) The increase of protein content and PMN numbers in bronchoalveolar lavage fluid induced by LPS (100μg per rat) intratracheal instillation were alleviated by PDTC (50, 100, or 200mg/kg, i. p. ) in a dose-dependent manner. (2) PMNs apoptosis in vivo or in vitro was delayed by LPS, and accelerated by PDTC, gliotoxin or PD098059 pretreatment. (3) IκBα degradation and increased NF-KB DNA binding activity mediated by LPS were inhibited by PDTC, gliotoxin or PD098059 pretreatment.Conclusion Inhibition of either NF-κB itself or the upstream signals in NF-κB pathway such as extracellularly regulated protein kinases has therapeutic effect on LPS-induced acute lung injury, in which the dysregulation of PMN apoptosis plays an important role.     

Epstein-Barr virus encoded latent membrane protein 1 induces TRAF1 expression to promote anti-apoptosis activity via NF-κB signaling pathway in nasopharyngeal carcinoma

Objectives To identify whether Epstein-Barr virus (EBV) encoded latent membrane protein 1(LMP1) can induce tumor necrosis factor receptor-associated factor 1 (TRAF1) expression and promote its anti-apoptosis activity via the NF-KB signaling pathway, and assess that LMP1 suppresses apoptosis in nasopharyngeal carcinoma (NPC).Methods A stable transfected cell line HNE2-LMP1 was established by introducing LMP1 cDNA into HNE2 cells. Transactivation of TRAF1 was determined by luciferase reporter assay, while expression of TRAF1 mRNA was detected by RT-PCR and expression of TRAF1 protein and caspase 3 by Western blot analysis. Apoptosis activity was observed through fluorescence staining.Results LMP1 induced TRAF1 expression in NPC cells and caused a decrease in apoptosis. This induction could be blocked by antisense LMPI. Moreover, LMPl-mediated induction of a TRAF1 promoter-driven reporter gene was significantly impaired when the KB site KB1 or KB5 was disrupted,whereas mutation of κB3 had only a minor effect on LMP1 dependent up-regulation of the reporter gene.Conclusion LMP1 induces TRAF1 expression and promotes its anti-apoptosis activity via the NF-κB signaling pathway, which may be one of the mechanisms that LMP1 uses to suppress apoptosis in NPC cells.     

Low doses of ethanolic extract of Boldo （Peumus boldus） can ameliorate toxicity generated by cisplatin in normal liver cells of mice in vivo and in WRL-68 cells in vitro,but not in cancer cells in vivo or in vitro

OBJECTIVE： Use of cisplatin, a conventional anticancer drug, is restricted because it generates strong hepatotoxicity by accumulating in liver. Therefore its anticancer potential can only be fully exploited if its own toxicity is considerably reduced. Towards this goal, ethanolic extract of the plant, Boldo （Peumus boldus）, known for its antihepatotoxic effects, was used simultaneously with cisplatin, to test its ability to reduce cisplatin＇s cytotoxicity without affecting its anticancer potential. METHODS： The cytotoxicity of Boldo extract （BE） and cisplatin, administered alone and in combination, was determined in three cancer cell lines （A549, HeLa, and HepG2） and in normal liver cells （WRL-68）. Drug-DNA interaction, DNA damage, cell cycle, apoptosis, reactive oxygen species （ROS） and mitochondrial membrane potential （MMP, Aψ） were also studied. Hepatotoxicity and antioxidant activity levels were determined by alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase and glutathione assays in mice. The cytotoxicity of related proteins was tested by Western blotting. RESULTS： Co-administration of BE and cisplatin increased viability of normal cells, but had no effect on the viability of cancer cells. Boldo protected liver from damage and normalized different antioxidant enzyme levels in vivo and also reduced ROS and re-polarized MMP in vitro. Bax and cytochrome c translocation was reduced with caspase 3 down-regulation. Further, a drug- DNA interaction study revealed that BE reduced cisplatin＇s DNA-binding capacity, resulting in a reduction in DNA damage. CONCLUSION： Results indicated that a low dose of BE could be used beneficially in combination with cisplatin to reduce its toxicity without hampering cisplatin＇s anticancer effect. These findings siqnify a potential future use of BE in cancer therapy.     

LMP1 activates NF- κB via degradation of IκBα in nasopharyngeal carcinoma cells

Objective To elucidate the mechanisms by which Epstein- Barr virus- encoded latent membran e protein 1 activates NF- κB in nasopharyngeal carcinoma cells. Methods A tetracycline- regulated LMP1- expressing nasopharyngeal carcinoma cell line, T et- on- LMP1- HNE2, was used as the cell model. The kinetics of the expression of proteins, including LMP1, IκBα and IκBβ, was analyzed by Western blotting . The subcellular localization of NF- κB (p65) was detected by indirect immuno fluorescence assay. The NF- κB transactivity was studied by transient transfec tion and reporter gene assay. Results IκBα was phosphorylated and degraded after the inducible expression of LMP1, a lthough the total protein levels remained stable. The steady- state level of to tal IκBβ protein may have resulted from the initiation of an autoregulation lo op after the activation of NF- κB. No change in the IκBβ level was detected . NF- κB (p65) was translocated from the cytoplasm to the nucleus following de gradation of IκBα. After the introduction of the dominant- negative mutant of IκBα (Del 71) into Tet- on- LMP1- HNE2 cells, both nuclear translocation and transactivation of NF- κB induced by LMP1 was significantly inhibited. Conclusions The results indicated that in nasopharyngeal carcinoma cells, LMP1 activated NF - κB via phosphorylation and degradation of IκBα, but not IκBβ. The do minant- negative mutant of IκBα (Del 71) could completely inhibit both the nuc lear translocation and transactivation of NF- κB induced by LMP1.     

Metformin inhibits nuclear factor-κB activation and inflammatory cytokines expression induced by high glucose via adenosine monophosphate-activated protein kinase activation in rat glomerular mesangial cells in vitro

Background The renoprotective mechanisms of adenosine monophosphate （AMP）-activated protein kinase （AMPK） agonist-metformin have not been stated clearly.We hypothesized that metformin may ameliorate inflammation via AMPK interaction with critical inflammatory cytokines The aim of this study was to observe the effects of metformin on expression of nuclear factor-κB （NF-κB）,monocyte chemoattractant protein-1 （MCP-1）,intercellular adhesion molecule-1 （ICAM-1） and transforming growth factor-beta 1 （TGF-β1） induced by high glucose （HG） in cultured rat glomerular mesangial cells （MCs）.Methods MCs were cultured in the medium with normal concentration glucose （group NG,5.6 mmol/L）,high concentration glucose （group HG,25 mmol/L） and different concentrations of metformin （group M1,M2,M3）.After 48-hour exposure,the supernatants and MCs were collected.The expression of NF-κB,MCP-1,ICAM-1,and TGF-β1 mRNA was analyzed by real time polymerase chain reaction.Westem blotting was used to detect the expression of AMPK,phospho-Thr-172 AMPK （p-AMPK）,NF-κB p65,MCP-1,ICAM-1,and TGF-β1 protein.Results After stimulated by HG,the expression of NF-κB,MCP-1,ICAM-1,TGF-β1 mRNA and protein of MCs in group HG increased significantly compared with group NG （P ＜0.05）.Both genes and protein expression of NF-κB,MCP-1,ICAM-1,TGF-β1 of MCs induced by high glucose were markedly reduced after metformin treatment in a dose-dependent manner （P ＜0.05）.The expression of p-AMPK increased with the rising of metformin concentration,presenting the opposite trend,while the level of total-AMPK protein was unchanged with exposure to HG or metformin.Conlusion Metformin can suppress the expression of NF-κB,MCP-1,ICAM-1 and TGF-β1 of glomerular MCs induced by high glucose via AMPK activation,which may partlv contribute to its reno-protection.     

Fuzheng Yiliu Granule (扶正抑瘤颗粒) inhibits the growth of hepatocellular cancer by regulating immune function and inducing apoptosis in vivo and in vitro

Objective  

To study the inhibitory effect of Fuzheng Yiliu Granule (扶正抑瘤颗粒, FYG) on hepatocellular cancer (HCC) and investigate the mechanism mediating its bioactivity.     

Effects of High Concentration Glucose on the Expression of NF-κB, Bax and Cytochrome C and Apoptosis of Islet Cells in Mice

The roles of NF-kappaB （NF-κB） expression, Bax activity and cytochrome C （Cyt C） release, apoptosis of islet cells induced by high concentration glucose were explored in vitro. Pancreatic islet cells, which were isolated from Kunming mice, were cultured with different concentrations of glucose in DMEM, and divided into the following groups： G1, G2, G3, G4, G5, and G6 groups, corresponding to the glucose concentrations of 5.6, 7.8, 11.1, 16.7, 22.5, and 27.6 mmol/L, respectively. After culture for 120 h, insulin secretion was evaluated by radioimmunoassay, and the NF-rd3 expression was detected by immunocytochemistry. Bax activity and Cyt C release were measured by immunofluorescence, and apoptosis was examined by Hoechst33342 assay. The results showed that in GI, G2 and G3 groups, insulin secretion was enhanced with the increase of glucose concentration, and the NF-κB expression was also increased （P〈0.05）, but Bax activity, Cyt C release and apoptosis rate showed no significant difference among them. However, in G4, G5, and G6 groups, apoptosis rate of islet cells, NF-rd3 expression, Bax activity, and Cyt C release were all significantly increased, and insulin secretion was impaired as compared with G1, G2, and G3 groups （P〈0.05）. It was concluded that the exposure of islet cells to high glucose could induce islet cells apoptosis as well as impaired insulin secretion. The NF-κB signaling pathway and mitochondria pathway in islet cells might play some roles in the progressive loss of islet cells in diabetes. The inhibition of the NF-κB expression could be an effective strategy for protecting pancreatic islet cells.     

Atorvastatin attenuates involvement of RhoA/Rho-kinase pathway and NF-κB activation in hypoxic pulmonary hypertensive rats

Background Hypoxic pulmonary hypertension （HPH） contributes to the pathogenesis of cardiopulmonary diseases.Several lines of evidence indicate that the Rho A/Rho-kinase pathway play an important role in the progress of pulmonary hypertension.Stains have been shown exert numerous biological effects that are independent of their cholesterollowering property.We hypothesized that the Rho A/Rho-kinase pathway is involved in the pathogenesis of HPH,and that atorvastatin would attenuate involvement of the Rho A/Rho-kinase pathway in a HPH rat model.Methods Thirty-two Wistar rats were randomly divided into four groups：control group,hypoxic group,atovastatin group,and normal saline group.The control group was kept in a normoxia environment.The other groups were exposed to hypoxia for three weeks.Atovastatin was administered daily via a gastric gavage in the atovastatin group.We measured the mean pulmonary arterial pressure （mPAP）,the ratio of the right ventricular weight to the sum of the weights of the left heart ventricle and septum （RV/（LV＋S））,arteriole wall thickness/vascular external diameter （WT％）,vascular area/total vascular area （WA％）,expression of RhoA and phos-MYPT-1 protein in lung tissue,and NF-κB activation in pulmonary vascular smooth muscle cells.Results Compared with the control group,mPAP,RV/（LV＋S）,WT％,WA％,NF-κB activation,expression of RhoA,and phos-MYPT-1 were increased in the hypoxic and normal saline groups （P ＜0.05）.Compared with the hypoxic group,mPAP,RV/（LV＋S）,WT％,WA％,NF-κB activation,expression of RhoA,and phos-MYPT-1 were decreased in the atovastatin group （P ＜0.05）.Correlations between phos-MPTY-1 and mPAP,WA％,WT％,and NF-κB activation were all positive.Conclusions The Rho NRho-kinase pathway plays an important role in the development of HPH.Atorvastatin reversed HPH by inhibiting the activity of Rho A/Rho-kinase and NF-κB.     

Resolvin-D1 inhibits interleukin-8 and hydrogen peroxide production induced by cigarette smoke extract in 16HBE cells via attenuating NF-κB activation

Background Cigarette smoke induced airway inflammation plays a role in pathogenesis of airway inflammation.Resolvin-D1 derived from omega-3 polyunsaturated fatty acids is an endogenous anti-inflammatory and proresolving lipid mediator.Resolvin-D1 ameliorated inflammatory responses in lung injury,asthma,peritonitis and atherosclerosis.We investigated whether resolvin-D1 suppressed the productions of chemokines and oxidative stress induced by cigarette smoke extract （CSE） in vitro and its possible mechanism.Methods We examined the proinfiammatory chemokine interleukin-8 and hydrogen peroxide （H2O2）productions induced by CSE in 16 human bronchial epithelial （16HBE）cells after resolvin-D1 treatment and their mechanisms.16HBE cells were treated with resolvin-D1 at up to 10 nmol/L,for 30 minutes before CSE up to 16％ （v/v） exposure.Release of interlukin-8 proteins was assessed by enzyme linked immunosort assay （ELISA） and its mRNA level by RT-PCR.We evaluated extracellular H2O2 expression in the supematant.Phosphorylation of NF-KB/p65 and degradation of Ⅰ-KB in 16HBE cells were determined by Westem blotting analysis and NF-KB DNA binding activity by electrophoretic mobility shift assay （EMSA）.Results 16HBE cells treated with 8％ CSE showed significantly higher interlukin-8 production.Resolvin-D1 pretreatment inhibited CSE induced intedukin-8 production （mRNA and protein） in a dose and time dependent manner.Extracellular H2O2 level decreased after resolvin-D1 treatment.Resolvin-D1 attenuated CSE triggered Ⅰ-KB degradation and NF-KB/p65 activation dose dependently and inhibited NF-KB DNA binding activity.Conclusion Resolvin-D1 inhibits CSE induced interlukin-8 and H2O2 production in 16HBE cells by modulating NF-KB activation and has therapeutic potential for pulmonary inflammation.