Blockage Of NF-κB Activation Research Articles

Dauricine negatively regulates lipopolysaccharide- or cecal ligation and puncture-induced inflammatory response via NF-κB inactivation

Acute lung injury (ALI) is a challenging clinical problem worldwide characterized by severe pulmonary inflammation. Dauricine, extracted from the root of traditional Chinese medicine Menispermum dauricum DC, is employed as anti-inflammatory herbs. In this study, we explored the inhibitory effects of dauricine on lipopolysaccharide (LPS)-induced inflammation in macrophages and LPS- or cecal ligation and puncture (CLP)-induced ALI in C57BL/6 mice. Our in vitro study identified that pretreatment of dauricine dose-dependently inhibited pro-inflammatory cytokines including nitric oxide (NO), interleukin-1β (IL1β), IL6, tumor necrosis factor-α (TNFα), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX2) in LPS-stimulated macrophages. Moreover, dauricine could suppress LPS-mediated nuclear translocation and transcriptional activity of nuclear factor-kappaB (NF-κB) by suppressing the phosphorylation of NF-κB inhibitors (IκB). In vivo studies, administration of dauricine, especially high-dose dauricine, potently improved the survival rate, reduced the production of pro-inflammatory cytokines in serum, and ameliorated ALI induced by LPS or CLP via blockage of NF-κB activation. Collectively, the present study discovers a new biological effect of dauricine in prevention of inflammation, indicating that dauricine can be served as a potential therapeutic agent to treat inflammatory diseases.

H19 induced by oxidative stress confers temozolomide resistance in human glioma cells via activating NF-κB signaling.

BackgroundRecent findings around long noncoding RNAs (lncRNAs) have opened novel areas of research around their prospective use in overcoming chemoresistance. Herein, we aimed to investigate the role of lncRNA H19 in temozolomide (TMZ) resistance of human glioma cells and the possible mechanisms.MethodsShort-/long-term oxidative stress was induced, and TMZ-resistant glioma cells (U251TMZ and LN229TMZ) were established. Small interfering RNA (siRNA) and overexpression plasmids were used to modulate the expression of H19 and/or luciferase the reporters. The MTT assay and immunoblotting of cleaved caspase-3, cyclin D1, XIAP and Bcl-2 were conducted to evaluate TMZ sensitivity. Luciferase reporter and quantitative real-time PCR (qRT-PCR) assays were used to verify the activation of NF-κB pathways by H19.ResultsKnockdown of H19 in U251TMZ and LN229TMZ cells decreased half maximal inhibitory concentration (IC50) values for TMZ and increased cell apoptosis, and H19 overexpression in U251 and LN229 cells led to the opposite effects, indicating that the H19 confers TMZ resistance to glioma cells. Furthermore, knockdown of H19 decreased the NF-κB signaling, which was revealed by repressed reporter activity and declined expression of its downstream targets in TMZ-resistant glioma cells. In contrast, H19 overexpression in U251 and LN229 cells resulted in an increase in NF-κB activation. Blockage of NF-κB activation by its inhibitor abolished TMZ resistance caused by H19 overexpression. Addition of H2O2 to induce oxidative stress largely reversed TMZ sensitivity caused by H19 knockdown.ConclusionH19 confers TMZ resistance through activating NF-κB signaling and may represent a novel therapeutic target for TMZ-resistant gliomas.

Activation of α7nAChR Promotes Diabetic Wound Healing by Suppressing AGE-Induced TNF-α Production.

Diabetes frequently presents accumulation of advanced glycation end products (AGEs), which might induce excessive TNF-α production from macrophages to cause impaired wound healing. Recent studies have shown that activation of α7 nicotinic acetylcholine receptor (α7nAChR) on macrophages efficiently suppressed TNF-α synthesis. The aim of this study was to investigate the accumulation of AGEs in the wounds and determine whether PNU282987, an α7nAChR agonist, can improve wound repair by inhibiting AGE-mediated TNF-α production in a streptozotocin (STZ)-induced diabetic mouse model. Animals were assigned into four groups: wounded control group, wounded diabetic group, wounded diabetic group treated intraperitoneally with PNU282987, or wounded diabetic group treated intraperitoneally with vehicle. Compared with the non-diabetic control mice, the diabetic mice exhibited delayed wound healing that was characterized by elevated accumulation of AGEs, increased TNF-α level and macrophage infiltration, and decreased fibroblast number and collagen deposition at the late stage of repair. Besides, macrophages of diabetic wounds showed expression of α7nAChR. During late repair, PNU282987 treatment of diabetic mice significantly reduced the level of TNF-α, accelerated wound healing, and elevated fibroblast number and collagen deposition. To investigate the cellular mechanism of these observations, RAW 264.7 cells, a macrophage cell line, were incubated with AGEs in the presence or absence of PNU282987. TNF-α production from AGE-stimulated macrophages was significantly decreased by PNU282987 in a dose-dependent manner. Furthermore, PNU282987 significantly inhibited AGE-induced nuclear factor-κB (NF-κB) activation and receptor for AGE (RAGE) expression. These results strongly suggest that activating α7nAChR can promote diabetic wound healing by suppressing AGE-induced TNF-α production, which may be closely associated with the blockage of NF-κB activation in macrophages.

Anti-inflammatory effects of Dendrobium nobile derived phenanthrenes in LPS-stimulated murine macrophages.

Dendrobium nobile belongs to the Orchidaceae family and is one of the medicinal herbs used in traditional Chinese medicine as a therapeutic agent for gastrointestinal and cardiovascular diseases. In this study, we separated three phenanthrenes (ephemeranthol A (EA), 1,5,7-trimethoxyphenanthren-2-ol (TP), dehydroorchinol (DO)) from D. nobile, and compared their anti-inflammatory activities. TP is a new phenanthrene compound and its structure was determined from (1)H, (13)C NMR and HR-ESI-MS data. To analyze the anti-inflammatory activities of the phenanthrenes, Raw 264.7 cells were used, since they are immature-macrophages and easily matured by LPS stimulation. EA and DO showed anti-inflammatory activities in the activated Raw 264.7 cells. That is, we showed that EA is a potent inhibitor of the production of nitric oxide and pro-inflammatory cytokines. The inhibitory activities of phenanthrenes were found to be caused by blockage of NF-κB activation and the phosphorylation of MAP kinases in the macrophages. These results are expected to serve as a guide for future studies on the ability of phenanthrenes to inhibit acute and chronic inflammatory diseases.

Inhibition of allergic airway inflammation through the blockage of NF-κB activation by ellagic acid in an ovalbumin-induced mouse asthma model.

Allergic asthma is a complex inflammatory disease characterized by airway hyperresponsiveness, eosinophilic inflammation and the hypersecretion of mucus by goblet cells. Ellagic acid (EA), a natural polyphenolic compound present as ellagitannins in fruits and fruit juices, has been reported to show potent anti-inflammatory properties in various diseases. We aimed to investigate the effects of EA in an ovalbumin (OVA)-induced mouse asthma model and to explore its potential mechanism of action. Our results showed that EA resulted in a significant reduction in lung eosinophilia, increased Th2 cytokines in bronchoalveolar lavage fluid and increased OVA-induced specific IgE in serum samples. Moreover, histological examination showed that EA markedly inhibited lung eosinophilic inflammation and goblet cell hyperplasia. In addition, EA attenuated the development of airway hyperresponsiveness and blocked NF-κB activation. These results demonstrate that EA shows obvious anti-inflammatory effects in OVA-induced asthma in a mouse model, possibly through inhibiting NF-κB activation. Therefore it may be a potential therapeutic agent for the treatment of allergic asthma.

Regulation of apoptosis and inflammatory responses by insulin-like growth factor binding protein 3 in fibroblast-like synoviocytes and experimental animal models of rheumatoid arthritis.

Insulin-like growth factor binding protein 3 (IGFBP-3) is known to interfere with the NF-κB signaling pathway, and it effectively promotes apoptosis in tumor cells by a variety of mechanisms. NF-κB activation and apoptosis resistance of fibroblast-like synoviocytes (FLS) play pivotal roles in rheumatoid arthritis (RA). This study was undertaken to evaluate whether IGFBP-3 has antiarthritic effects. To deliver IGFBP-3, we used an adenovirus containing IGFBP-3 complementary DNA (AdIGFBP-3) or IGFBP-3 mutant that is devoid of IGF binding affinity but retains IGFBP-3 receptor binding ability (AdmtIGFBP-3). The regulatory roles of IGFBP-3 in inflammation and bone destruction were investigated in mice with collagen-induced arthritis (CIA). IGFBP-3 levels were significantly higher in patients with RA than in those with osteoarthritis (OA) and were notably higher in patients with active RA. AdIGFBP-3 suppressed NF-κB activation, chemokine production, and matrix metalloproteinase secretion induced by tumor necrosis factor α (TNFα) in RA FLS. AdIGFBP-3 sensitized RA FLS to TNFα-induced apoptosis in vitro and also significantly increased apoptosis in an in vivo model of Matrigel implants engrafted into immunodeficient mice. AdIGFBP-3-injected mice with CIA had attenuated arthritis severity and reduced radiologic and pathologic abnormalities. Moreover, AdIGFBP-3 down-regulated local and systemic levels of NF-κB-targeted proinflammatory cytokines. Of note, RA FLS and mice with CIA treated with AdmtIGFBP-3 exhibited similar effects as those treated with AdIGFBP-3. Our results suggest that both the inflammatory response and bone destruction are reduced with blockage of NF-κB activation and induction of apoptosis in RA FLS by IGFBP-3. Therefore, IGFBP-3 may have therapeutic potential in RA.

The Proteasome Inhibitor Bortezomib Sensitizes AML with Myelomonocytic Differentiation to TRAIL Mediated Apoptosis

Acute myeloid leukemia (AML) is an aggressive stem cell malignancy that is difficult to treat. There are limitations to the current treatment regimes especially after disease relapse, and therefore new therapeutic agents are urgently required which can overcome drug resistance whilst avoiding unnecessary toxicity. Among newer targeted agents, both tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) and proteasome inhibitors show particular promise. In this report we show that a combination of the proteasome inhibitor bortezomib and TRAIL is effective against AML cell lines, in particular, AML cell lines displaying myelomonocytic/monocytic phenotype (M4/M5 AML based on FAB classification), which account for 20-30% of AML cases. We show that the underlying mechanism of sensitization is at least in part due to bortezomib mediated downregulation of c-FLIP and XIAP, which is likely to be regulated by NF-κB. Blockage of NF-κB activation with BMS-345541 equally sensitized myelomonocytic AML cell lines and primary AML blasts to TRAIL.

Tetradecanoyl phorbol acetate induces expression of Toll-like receptor 2 in U937 cells: involvement of PKC, ERK, and NF-κB

Toll-like receptors (TLRs) have been identified recently as crucial signaling receptors mediating the innate immune recognition. Though induction of TLR2 or TLR4 by 12- O-tetradecanoyl phorbol 13-acetate (TPA) in leukemia cells has been reported, however, the mechanism by which TPA up-regulates TLR2 or TLR4 remains poorly understood. In this study, we investigated the effect of TPA on induction of TLR2 in U937 cells. TPA markedly induced TLR2 mRNA and protein expressions. TLR2 expression in response to TPA was attenuated by pretreatments with GF109203X and Go6976 (inhibitors of protein kinase C (PKC)) and PD98059 (an inhibitor of extracellular signal-regulated kinases (ERKs)), but not SB203580 (an inhibitor of p38s) and SP600125 (an inhibitor of c-Jun N-terminal kinases), suggesting involvement of PKC and ERKs in this response. Moreover, TPA-induced PKC activation was linked to generation of reactive oxygen species, which were dispensable for TLR2 expression in U937 cells. Pretreatments with GF109203X blocked TPA-induced phosphorylation of ERKs, suggesting activation of ERKs by PKC. In addition, TPA induced nuclear factor-κB (NF-κB) activation, which was shown by increased nuclear translocation of p65 NF-κB and degradation of IκB-α, a NF-κB inhibitory protein. Importantly, TPA-induced TLR2 expression was inhibited by blockage of NF-κB activation using NF-κB inhibitors, including MG132 and BAY11-7085. Specifically, TPA-induced nuclear translocation of NF-κB was effectively attenuated by GF109203X and PD98059, suggesting PKC and ERK regulation of NF-κB nuclear localization in response to TPA. Together, these results suggest that TPA-induced TLR2 expression in U937 cells may be at least in part mediated through activation of PKC and ERKs as well as NF-κB transcription factor, and that cross-talk between PKC or ERKs and NF-κB may exist.

Up-regulation of human β-defensin 2 by interleukin-1β in A549 cells: involvement of PI3K, PKC, p38 MAPK, JNK, and NF-κB

Induction of human β-defensin 2 (HBD-2) by interleukin-1β (IL-1β) in epithelial cells has been reported. However, the mechanism by which IL-1β up-regulates HBD-2 remains poorly understood. In this study, we investigated the effect of IL-1β on induction of HBD-2 in A549 cells. IL-1β markedly increased HBD-2 mRNA expression in concentration- and time-dependent manners. HBD-2 mRNA expression in response to IL-1β was attenuated by pretreatment of GF109203X, Go6976, and staurosporine [inhibitors of protein kinase C (PKC)], SB203580 [an inhibitor of p38 mitogen-activated protein kinase (MAPK)], SP600125 [an inhibitor of c-Jun N-terminal kinase (JNK)], and LY294002 [an inhibitor of phosphatidylinositol-3-kinase (PI3K)], but not PD98059 [an inhibitor of extracellular signal-regulated kinase (ERK)], suggesting involvement of PKC, p38 MAPK, JNK, and PI3K in this response. Interestingly, IL-1β induced nuclear factor-κB (NF-κB) activation in A549 cells, which was shown by increased nuclear translocation of p65 NF-κB and degradation of IκB-α. Importantly, IL-1β-induced HBD-2 mRNA expression was inhibited by blockage of NF-κB activation using NF-κB inhibitors, including pyrrolidine dithiocarbamate and MG132. Specifically, IL-1β-induced nuclear translocation of NF-κB was in part attenuated by LY294002, but not by GF109203X, SB203580, and SP600125, suggesting PI3K-dependent nuclear translocation of NF-κB in response to IL-1β. Together, these results suggest that IL-1β induces HBD-2 mRNA expression in A549 cells, and the induction seems to be at least in part mediated through activation of NF-κB transcription factor as well as activation of signaling proteins of PKC, p38 MAPK, JNK, and PI3K, but not ERK.

Activation of NF-κB Is Essential for Hepatocyte Growth Factor-Mediated Proliferation and Tubulogenesis

Hepatocyte growth factor (HGF) and its receptor, Met, regulate a number of biological functions in epithelial and nonepithelial cells, such as survival, motility, proliferation, and tubular morphogenesis. The transcription factor NF-kappaB is activated in response to a wide variety of stimuli, including growth factors, and is involved in biological responses in part overlapping with those triggered by HGF. In this work we used the liver-derived MLP29 cell line to study the possible involvement of NF-kappaB in HGF/Met signaling. HGF stimulates NF-kappaB DNA binding and transcriptional activation via the canonical IkappaB phosphorylation-degradation cycle and via the extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinase cascades. Phosphatidylinositol 3-kinase is not involved in Met-mediated NF-kappaB activation. Blockage of NF-kappaB activation in MLP29 cells by forced expression of the NF-kappaB super-repressor IkappaB(alpha)2A does not interfere with HGF-induced scatter but inhibits proliferation and tubulogenesis. Surprisingly, in the same cells NF-kappaB appears to be dispensable for the antiapoptotic function of HGF.

Inhibition of nuclear factor-κB activation improves the survival of rats with taurocholate pancreatitis

BackgroundDeath in the early stages of severe acute pancreatitis is frequently the result of multiple organ dysfunction, but its mechanism is not clear.AimsTo investigate the state of nuclear factor-κB (NF-κB)...