Increased expression and activity of MMP-9 in C-reactive protein- induced human THP-1 mononuclear cells is related to activation of nuclear factor kappa-B

The relation between the expression and activity of MMP-9 in C-reactive protein （CRP）-induced human THP-1 mononuclear cells and the activation of nuclear factor kappa-B （NF-κB） was studied to investigate the possible role of CRP in plaque destabilization. Human THP-1 cells were incubated in the presence of CRP at 0 （control group）, 25, 50 and 100 μg/mL （CRP groups） for 24 h. In PDTC （a specific NF-κB inhibitor） group, the cells were pre-treated with PDTC at 10 μmol/L and then with 100 μg/mL CRP. The conditioned media （CM） and human THP-1 cells in different groups were harvested. MMP-9 expression in CM and human THP-1 cells was measured by ELISA and Western blotting. MMP-9 activity was assessed by fluorogenic substrates. The expression of NF-κB inhibitor α （IκB-α） and NF-κB p65 was detected by Western blotting and ELISA respectively. The results showed that CRP increased the expression and activity of MMP-9 in a dose-dependent manner in the human THP-1 cells. Western blotting revealed that IiB-α expression was decreased in the cells with the concentrations of CRP and ELISA demonstrated that NF-κB p65 expression in the CRP-induced cells was increased. After pre-treatment of the cells with PDTC at 10 μmol/L, the decrease in IκB-α expression and the increase in NF-κB p65 expression in the CRP-induced cells were inhibited, and the expression and activity of MMP-9 were lowered too. It is concluded that increased expression and activity of MMP-9 in CRP-induced human THP-1 cells may be associated with activation of NF-κB. Down-regulation of the expression and activity of MMP-9 may be a new treatment alternative for plaque stabilization by inhibiting the NF-κB activation.     

Shp-2／NF-κB Pathway Mediates the Inhibition of Lipoxin A4 onIL-1β-induced Synthesis of IL-6 in Glomerular Mesangial Cells

Objective: To examine whether lipoxin A4 (LXA4) has an antagonistic effect on IL-1β-induced synthesis of IL-6 in glomerular mesangial cells, and to explore the molecular mechanisms of signal pathway in LXA4 actions. Methods: The glomerular mesangial cells of rat were cultured and treated with IL-1β with or without preincubation with LXA4 at different concentrations. The amount of IL-6 in the supernatant of cells was analyzed by enzymelinked immunosorbent assay(ELISA). The expressions of mRNA of IL-6 were determined by RT-PCR. The expressions of Src homology 2( SH2 ) containing protein-tyrosine phosphatase 2(Shp-2) were assessed by immunoprecipitation and immunoblotting. Activities of DNA-binding of nuclear factor-kappa B(NF-κB) were measured by electrophoretic mobility shift assay(EMSA). Results:IL-1β- snulated secretion of protein and expression of mRNA of IL-6 in mesangial cells were inhibited by LXA4 in a dose-dependent manner. LXA4 antagonizes the phosphorylation of Shp-2 and activities of NF-κB induced by IL-1β Conclusion: LXA4 antagonists IL-1β-induced synthesis of IL-6 in glomerular mesangial cellsthrough the mechanism of Shp-2/NF-κB pathway-dependent signal transduction.     

Relationship between Carbachol Hyperstimulation-induced Pancreatic Intracelluar Trypsinogen and NF-κB Activation in Rats in vitro

The relationship between intracelluar trypsinogen activation and NF-κB activation in rat pancreatic acinar cells induced by M3 cholinergic receptor agonist （carbachol） hyperstimulation was studied. Rat pancreatic acinar cells were isolated, cultured and treated with carbachol, the active protease inhibitor （pefabloc） and NF-κB inhibitor （PDTC） in vitro. Intracelluar trypsin activity was measured by using a fluorogenic substrate. The activity of NF-κB was monitored by using electrophoretic mobility shift assay. The results showed that after pretreatment with 2 mmol/L pefabloc, the activities of trypsin and NF-κB in pancreatic acinar cells treated with high concertrations of carbachol （10^-3 mol/L） in vitro was significantly decreased as compared with control group （P〈0.01 ）. The addition of 10^-2 mol/L PDTC resulted in a significant decrease of NF-κB activities in pancreatic acinar cells after treated with high concertrations of carbachol （10^-3 mol/L） in vitro, but the intracelluar trypsinogen activity was not obviously inhibited （P〉0.05）. It was concluded that intracelluar trypsinogen activation is likely involved in the regulation of high concertrations of carbachol-induced NF-κB activation in pancreatic acinar cells in vitro. NF-κB activation is likely not necessary for high concertrations of carbachol-induced trypsinogen activation in pancreatic acinar cells in vitro.     

Activation of NF-κB in bronchial epithelial cells from children with asthma

Objectives To determine whether nuclear factor-κB (NF-κB) is activated in epithelial cells from children with asthma and to understand the role of NF-κB in airway inflammation in asthma. Methods Bronchial mucosa specimens were obtained from 9 children with asthma and 6 control subjects. NF-κB expression in epithelial cells were detected by immunohistochemical examination, and NF-κB-DNA binding was measured by electrophoretic mobility shift assay (EMSA). Results Nuclear expression of NF-κB in epithelial cells was observed in the 9 asthmatic children. NF-κB-DNA binding was found in 4 asthmatic children (EMSA was performed in 6 asthmatic children). In contrast, both nuclear expression and NF-κB-DNA binding were absent in the 6 control subjects. Conclusion These results indicated that NF-κB is activated in epithelial cells from asthmatic children and the NF-κB activation may be the basis for the increased expression of many inflammatory genes and for airway inflammation in asthma.     

Inhibition of NF-κB by mutant IκBα enhances TNF-α-induced apoptosis in HL-60 cells by controlling bcl-xL expression

Backgound The aim of this study was to explore whether the inhibition of nuclear factor-κB (NF-κB)activation by mutant IκBα (S32,36→A) can enhance TNF-α-induced apoptosis of leukemia cells and to investigate the possible mechanism. Methods The mutant IκBα gene was transfected into HL-60 cells by liposome-mediated techniques. G418 resistant clones stably expressing mutant IκBα were obtained by the limiting dilution method. TNF-α-induced NF-κB activation was measured by electrophoretic mobility shift assay (EMSA). The expression of bcl-xL was detected by RT-PCR and Western blot after 4 hours exposure of parental HL-60 and transfected HL-60 cells to a variety of concentrations of TNF-α. The percentage of apoptotic leukemia cells was evaluated by flow cytometry (FCM). Results Mutant IκBα protein was confirmed to exist by Western blot. The results of EMSA showed that NF-κB activation by TNF-α in HL-60 cells was induced in a dose-dependent manner, but was almost completely inhibited by mutant IκBα repressor in transfected cells. The levels of bcl-xL mRNA and protein in HL-60 cells increased after exposure to TNF-α, but changed very little in transfected HL-60 cells. The inhibition of NF-κB activation by mutant IκBα enhanced TNF-α-induced apoptosis. Thecytotoxic effects of TNF-α were amplified in a time- and dose-dependent manner. Conclusions NF-κB activation plays an important role in the resistance to TNF-α-induced apoptosis. The inhibition of NF-κB by mutant IκBα could provide a new approach that may enhance the antileukemia effects of TNF-α or even of other cytotoxic agents.     

Activation of NF-κB and its regulation on IL-6 expression during LPS-induced liver injury

Objective： To explore the kinetics of the activation of nuclear factor-kappa B （NF-κB） and its regulation of interleukin-6 （IL-6） expression during LPS induced liver injury. Methods： Kunming mice were randomly divided into 4 groups in order to observe the does effect relationship at 3h： normal saline solution （control） group, low （1 mg/kg）, middle （5 mg/kg）, and high （10 mg/kg） LPS-induced groups; 6 groups in order to observe the time-effect relationship of 5 mg/kg LPS injection： normal saline solution （control） group, 0.5, 1, 3, 5 and 8 h groups ; pyrrolidine dithiocarbamate （PDTC） intervened groups （3 h）： normal saline solution （control） group, 5 mg/kg LPS, 200 mg/kg PDTC, and 200 mg/kg PDTC＋5 mg/kg LPS groups. NF-κB activities of Kupffer cells were determined with electrophoretic mobility shift assay （EMSA） and expression levels of IL-6 were measured with enzyme-linked immunosorbent assay （ELISA）. Results： Does-effect of NF-κB activities in Kupffer cells after LPS injection 3 h： NF-κB activation could be detected in 1 mg/kg LPS group, reached the highest level in 5 mg/kg LPS group, and persisted in 10 mg/kg LPS group; time-course after 5 mg/kg LPS injection： the DNA-binding activity was observable at 0.5 h after LPS injection, increased significantly at 3 h, and persisted for at least 8 h; in addition, antioxidant PDTC could inhibit the activation of NF-κB significantly. The kinetics of IL-6 level in liver tissues during LPS-induced liver injury were that IL-6 level after 3 h of injection increased first and then reduced; the same trend was observed in the time-course on IL-6 level after LPS injection; PDTC could significantly inhibit the release of IL-6. Correlation analyses revealed that IL-6 level was significantly and positively correlated with the activation of NF-κB. Conclusion ： NF-κB in Kupffer cells can be activitied during LPS-induced liver injury to some extent, and NF-κB may have some regulation on the expression of IL-6.     

Ursolic Acid Inhibits T-Cell Activation through Modulating Nuclear Factor-κB Signaling

<正>Objective:To investigate the effects of ursolic acid(UA) on T-cell proliferation and activation,as well as to examine its effect on nuclear factor-κB(NF-κB) signaling pathway in T cells.Methods:T-cells isolated from BALB/c mice were incubated with UA at concentrations ranging from 5-30μmol/L in the presence of phorbol 12-myristate 13-acetate(PMA) or PMA plus ionomycin.The proliferation of T cells was measured by the MTT assay.The expressions of CD69,CD25,and CD71 on T-cell surface were analyzed using flow cytometry. The level of interleukin-2(IL-2) in the culture supernatant of activated T cells was quantified by enzyme-linked immunosorbent assay(ELISA).The level of phosphorylated IκB-α(p-lκB-α) in total protein and p65,a subunit of NF-κB,nuclear translocation were measured by Western blot analysis.Results:UA in a dose-dependent manner significantly decreased the proliferation and inhibited the surface expressions of CD69,CD25,and CD71 in murine T lymphocytes upon in vitro activation(P0.01).Significant reduction of IL-2 production was found in activated T cells treated with UA(P0.01).The PMA-induced increase in p-lκB-αprotein was inhibited,and nuclear translocation of p65 from the cytoplasm was blocked by UA.Conclusion:UA is a potent inhibitor for T cell activation and proliferation;these effects are associated with the inhibition of NF-κB signaling pathway.     

Triptolide-induced apoptosis by inactivating nuclear factor-kappa B apoptotic pathway in multiple myeloma <Emphasis Type="Italic">in vitro</Emphasis>

The effect of triptolide on proliferation and apoptosis of human multiple myeloma RPMI-8226 cells in vitro,as well as the roles of nuclear factor-kappa B(NF-κB) and IκBα was investigated.The effect of tritptolide on the growth of RPMI-8226 cells was studied by MTT assay.Apoptosis was detected by Hoechest 33258 staining and Annexin V/PI double staining assay.The expression of NF-κB and IκBα was observed by Western blot and confocal microscopy.The results showed that triptolide inactivated NF-κB apoptotic pathway in human multiple myeloma RPMI-8226 cells.Triptolide at nM range induced proliferation inhibition in a dose-and time-dependent manner and apoptosis in a dose-dependent fashion in RPMI-8226 cells.Besides,we observed the inhibition of NF-κB /p65 in the nuclear fraction was correlated with the increase in the protein expression of IκBα in the cytosol.These results suggested that triptolide might exhibit its strong anti-tumor effects via inactivation of NF-κB/p65 and IκBα.     

Change and significance of nuclear factor-κB in adriamycin induced cardiomyopathy in rats

Background This study aimed at investigating the change and significance of nuclear factor-κB (NF-κB) in eardiomyopathy induced by adriamyein (ADR) in rats. Methods Sixty male Wistar rats were randomly divided into three groups: control, ADR and ADR pyrrolidine dithiocarbamate (PDTC) groups. After 30-day experiment, myocardial histopathological observation was performed. Location and distribution of NF-κB p50 was examined by immunohistochemical assay. Expression of NF-κB p50 protein was examined by immunoboh assay. Electrophoretic Mobility Shift Assay examined activity of NF-κB; Myocardium p53 gene expression was examined by RT-PCR analysis. Results The myocardial lesions of rats were less pronounced in ADR PDTC group than in ADR group. Compared with control group, there were many myocardium nucleuses, which expressed NF-κB p50 and distribute under epicardium. Expression of NF-κB p50 protein in nucleus increased significantly in ADR group. The NF-κB binding activity increased significantly in ADR group. Myocardium expressions of p53 mRNA increased in ADR group. Conclusions The NF-κB binding activity increased significantly in cardiomyopathy induced by ADR in rats. Moreover, NF-κB plays an important role in causing degeneration of myocardial tissue and regulating expression of related-apoptosis genes.     

The Role of IκBα in TNF-α-induced Apoptosis in Hepatic Stellate Cell Line HSC-T6

To investigate the role of NF-κB in TNF-α induced apoptosis in HSC-T6, a mutant IκBα was transfected into HSC-T6 cells by lipofectin transfection technique and its transient effect was examined 48 h after the transfection. The activation of NF-κB was detected by immune fluorescence cytochemistry and Western blotting with anti-p65 antibody. The apoptosis and the rate of inhibition by TNF-α in both transfected and untransfected HSC-T6 cells were measured respectively by FAC-Scan side scatter analysis and MTF methods. Our results showed that TNF-α could activate NF-κB in untransfected cells but not in transfected HSC-T6 cells. The percentage of apoptosis in transfected cells were significantly higher than that in the untransfected ones （P〈0.01） and it was also true of the inhibition rate （P〈0.01）. It is concluded that the resistance of HSC-T6 towards apoptosis induced by TNF-α can be mediated by NF-κB activation. The inhibition of NF-κB activation by mutant IκBα can attenuate the resistance of HSC-T6 cells and increase its sensitivity to TNF-α.     

Activation of nuclear factor κB and induction of inducible nitric oxide synthase by lipid-associated membrane proteins isolated from Mycoplasma penetrans

Background This study was designed to investigate the potential pathogenicity of Mycoplasma penetrans (M. penetrans) and its molecular mechanisms responsible for the induction of iNOS gene expression in mouse macrophages stimulated by lipid-associated membrane proteins (LAMPs) prepared from M. penetrans. Methods Mouse macrophages were stimulated with M. penetrans LAMPs to assay the production of nitric oxide (NO). The expression of inducible nitric oxide synthase (iNOS) was detected by RT-PCR and Western blotting. The activity of nuclear factor KB (NF-κB) and the effects of pyrrolidine dithiocarbamate (PDTC), an inhibitor of NF-κB, on the production of nitric oxide and the expression of iNOS were also assessed in mouse macrophages treated with M. penetrans LAMPs by indirect immunofluorescence and Western blotting. Results M. penetrans LAMPs stimulated mouse macrophages to produce nitric oxide in a dose- and time-dependent manner. The mRNA and protein levels of iNOS were also upregulated in response to LAMP stimulation and inhibited by PDTC treatment. M. penetrans LAMPs were found to trigger NF-κB activation, a possible mechanism for the induction of iNOS expression. Conclusion This study demonstrated that M. penetrans may be an important etiological factor of certain diseases due to the ability of M. penetrans LAMPs to stimulate the expression of iNOS, which is probably mediated through the activation of NF-κB.     

The role of NF-κB in hepatocellular carcinoma cell

Objective To evaluate the role of nuclear factor-kappaB (NF-κB) and IκBα in hepatocellular cacinoma (HCC) SMMC7721 cells, the consequence of NF-κB inhibition in SMMC7721 cells transfected with mutated IκBα (mIκBα) plasmid and the effect of stable inhibition of NF-κB activity in combination with Doxorubicin.Methods Western blot was used to determine the expression of NF-κB and IκBα in SMMC7721 cells and normal liver cells. Nuclear protein was used to evaluate the binding of the 32P-labeled tandem κB sequence using electrophoretic mobility shift assay and the expression of NF-κB using Western blot between SMMC7721 cells transfected with mIκBα plasmid (SMMC7721-MT) and control cells. Furthermore, cell viability was plotted between SMMC7721-MT and control cells. The binding of κB sequence and cell viability between SMMC7721-MT and control cells at different concentrations of Doxorubicin were also investigated.Results Western blot analysis for nuclear extract showed more P50 (NF-κB1) and P65 (RelA) expression in SMMC7721 cells compared with normal liver cells. The expression of cytosolic IκBα protein in SMMC7721 cells was less than that in normal cells. SMMC7721-MT cells inhibited NF-κB nuclear translocation at 0, 24, 48 and 96 hours. Furthermore, NF-κB cannot be detected in the nuclear protein of SMMC7721-MT cells by Western blot. By calculating cell viability, the proliferation of SMMC7721-MT cells was shown to be suppressed more significantly than that of control cells. NF-κB in untransfected cells was activated by Doxorubicin in a dose-dependent manner, but that in SMMC7721-MT cells was not induced at low concentrations of Doxorubicin. Compared with untransfected cells, the viability of SMMC7721-MT cells was significantly suppressed at the same concentration of Doxorubicin (P&lt;0.01）.Conclusions The present study demonstrates that upregulation of NF-κB and downregulation of inhibitory kappaB (IκBα) in SMMC7721 cells are related with the growth of hepatocellular cacinoma cells. Stable expression of mIκBα in SMMC7721-MT cells can inhibit NF-κB nuclear translocation and suppress cell growth. Furthermore, stable inhibition of NF-κB activity in combination with Doxorubicin can significantly inhibit cell proliferation in SMMC7721-MT cells. Thus, modulation of NF-κB may represent an improvement in the efficacy of HCC therapies and be worthy of further research and investigation.     

The Role of NF-kB and I-kB in Intimal Proliferation Following Balloon Catheter-induced Injury in the Rat Carotid Artery

The aim of our study was to gain insight into the molecular and cellular mechanisms of post-angioplasty restenosis using balloon catheter-induced injury model in the rat carotid artery. SD rats were subjected balloon catheterization at one side carotid artery as study group and another side as control group. Six rats were killed on the 6 h, and 3rd, 7th, 14th, 28th day after balloon-induced injury respectively. The intimal thickness and the expression of NF-κB and I-κB were detected by HE-staining, gel electrophoretic mobility shift assay （EMSA） and Western-blot methods. The results showed that： （1） The thickening of intima was observed on the 3rd day after balloon-induced injury, and it became more significant on the 7th, 14th and 28th day. The area ratio of intima/media was increased significantly （P〈0.05）; （2） The expression of NF-κB was not detectable in the control group, however, in study group, the expression of NF-κB was detected on the 6th h after balloon-induced injury, reached the peak on the 14th day, and on 28th day, strong expression of NF-κB was observed; （3） The expression of I-κB protein was reduced after balloon-induced injury, and there were significant differences between the study group and the control group （P〈0.05）. It was concluded that the alteration of NF-κB/I-κB system might play an important role in aberrant proliferation within the intima and vascular remodeling following vascular injury. To block NF-κB activation and its role in arterial restenosis initiation may potentially provide a novel therapeutic tool for the treatment and prevention of arterial restenosis.     

Interleukin-13 inhibits cytokines synthesis by blocking nuclear factor-κB and c-Jun N-terminal kinase in human mesangial cells

Objective： Monocytes/macrophages, proinflammatory cytokines and chemokines are important in the pathogenesis of glomerulonephritis. Interleukin （IL） -13 has been shown to exert potent anti-inflammatory properties. This study was designed to investigate the effect of IL-13 on the expression of proinflammatory cytokines, chemokines and profibrogenic cytokines and the involved molecular mechanism in cultured human mesangial cells （HMCs）. Methods： The expressions of proinflammatory cytokines, chemokines and profibrogenic cytokines were determined by ribonuclease protection assay （RPA）. Activity of nuclear factor-kappa B （NF-κB） and activa- tor protein-1 （AP-1） was examined by electrophoretic mobility shift assay （EMSA）. NF-κB subunit p65 nuclear transportation and c-Jun N-terminal kinase （JNK） activity were assayed by immunoblot. Results： Recombinant IL-13 inhibited tumor necrosis factor-α （TNF-u）, IL-1α, IL-1β, monocyte chemoattractant protein-1 （MCP-1）, IL-8, and transforming growth factor-β1 （TGF-β1） mRNA expressions in a dose-dependent manner. Lipopoly- sacchorides （LPS） dramatically increased NF-κB DNA binding activity of HMCs, which was inhibited by IL-13 in a dose-dependent manner. LPS-activated NF-κB contained p50 and p65 dimers, but not c-Rel subunit. IL-13 blocked LPS-induced NF-κB subunit p65. LPS stimulated JNK/AP-1 activation, which was inhibited by IL-13 in a dose-dependent manner. Conclusion： IL-13 inhibits proinflammatory cytokines, chemokines, and profibrogenic cytokines synthesis by blocking NF-κB and JNK/AP-1 activation. These observations point to the importance of IL-13 in the modulation of inflammatory processes in the renal glomerulus.