Nuclear Protein-1 Research Articles

Control of Cell Migration and Inflammatory Mediators Production by CORM-2 in Osteoarthritic Synoviocytes

BackgroundOsteoarthritis (OA) is the most widespread degenerative joint disease. Inflamed synovial cells contribute to the release of inflammatory and catabolic mediators during OA leading to destruction of articular tissues. We have shown previously that CO-releasing molecules exert anti-inflammatory effects in animal models and OA chondrocytes. We have studied the ability of CORM-2 to modify the migration of human OA synoviocytes and the production of chemokines and other mediators sustaining inflammatory and catabolic processes in the OA joint.Methodology/Principal FindingsOA synoviocytes were stimulated with interleukin(IL)-1β in the absence or presence of CORM-2. Migration assay was performed using transwell chambers. Gene expression was analyzed by quantitative PCR and protein expression by Western Blot and ELISA. CORM-2 reduced the proliferation and migration of OA synoviocytes, the expression of IL-8, CCL2, CCL20, matrix metalloproteinase(MMP)-1 and MMP-3, and the production of oxidative stress. We found that CORM-2 reduced the phosphorylation of extracellular signal-regulated kinase1/2, c-Jun N-terminal kinase1/2 and to a lesser extent p38. Our results also showed that CORM-2 significantly decreased the activation of nuclear factor-κB and activator protein-1 regulating the transcription of chemokines and MMPs in OA synoviocytes.Conclusion/SignificanceA number of synoviocyte functions relevant in OA synovitis and articular degradation can be down-regulated by CORM-2. These results support the interest of this class of agents for the development of novel therapeutic strategies in inflammatory and degenerative conditions.

Vibrio vulnificus IlpA induces MAPK-mediated cytokine production via TLR1/2 activation in THP-1 cells, a human monocytic cell line

Vibrio vulnificus is a pathogenic bacterium causing primary septicemia, which is followed by a classical septic shock pathway including an overwhelming inflammatory cytokine response. V. vulnificus IlpA is a potent immunogenic lipoprotein that triggers cytokine production in human monocytes by activating the toll-like receptor 2 (TLR2). In this study, we further defined the IlpA signaling pathways involved in cytokine production in the human monocytic cell line, THP-1. TLR2 was involved in cytokine production by complexing with TLR1, but not with TLR6. MyD88 was necessary for IlpA-induced cytokine expression through TLR1/TLR2. Three mitogen activated protein kinases (MAPK), p38, ERK1/2, and JNK, were activated in THP-1 cells stimulated with recombinant IlpA (rIlpA). Selective inhibition of each MAPK resulted in significant decrease of rIlpA-induced cytokine production. Especially, functional TLR2 was necessary for IlpA-induced activation of p38 and JNK. IlpA augmented the DNA-binding activity of nuclear factor-kappaB (NF-κB) and activator protein-1 (AP-1) transcriptional factors to their recognition sites in THP-1 cells. These results suggest that serial activation of TLR1/TLR2, MyD88, the three MAPKs, and NF-κB/AP-1 comprises the signaling pathway responsible for proinflammatory cytokine production by V. vulnificus IlpA.

8042 POSTER Nuclear Y-box Binding Protein-1 Expression, a Predictive Marker of Prognosis, Is Correlated With Activated Signal Transducer and Activator of Transcription-3 Expression and Survival in Cervical Squamous-cell Carcinoma

8042 POSTER Nuclear Y-box Binding Protein-1 Expression, a Predictive Marker of Prognosis, Is Correlated With Activated Signal Transducer and Activator of Transcription-3 Expression and Survival in Cervical Squamous-cell Carcinoma

Comparative Evaluation of Two Structurally Related Flavonoids, Isoliquiritigenin and Liquiritigenin, for Their Oral Infection Therapeutic Potential

Isoliquiritigenin (1) and liquiritigenin (2) are structurally related flavonoids found in a variety of plants. The purpose of this study was to perform a comparative analysis of biological properties of these compounds in regard to their therapeutic potential for oral infections. Compound 1 demonstrated significant antibacterial activity against three major periodontopathogens, Porphyromonas gingivalis, Fusobacterium nucleatum, and Prevotella intermedia. In contrast, 2 exerted less pronounced effects on the above bacterial species. Neither compound was effective against cariogenic bacteria (Streptococcus mutans and Streptococcus sobrinus). Furthermore, 1 exhibited a stronger inhibitory activity than 2 toward P. gingivalis collagenase and human matrix metalloproteinase 9. Finally, the capacity of 1 to attenuate the inflammatory response of macrophages induced by Aggregatibacter actinomycetemcomitans lipopolysaccharide (LPS) was much higher when compared to 2. The activation of transcriptional factors nuclear factor-κB (NF-κB) p65 and activator protein-1 (AP-1) associated with the LPS-induced inflammatory response in macrophages was inhibited strongly by 1, but less affected by 2.

Inhibition of chronic pancreatitis and pancreatic intraepithelial neoplasia (PanIN) by capsaicin in LSL-KrasG12D/Pdx1-Cre mice

Capsaicin is a major biologically active ingredient of chili peppers. Extensive studies indicate that capsaicin is a cancer-suppressing agent via blocking the activities of several signal transduction pathways including nuclear factor-kappaB, activator protein-1 and signal transducer and activator of transcription 3. However, there is little study on the effect of capsaicin on pancreatic carcinogenesis. In the present study, the effect of capsaicin on pancreatitis and pancreatic intraepithelial neoplasia (PanIN) was determined in a mutant Kras-driven and caerulein-induced pancreatitis-associated carcinogenesis in LSL-Kras(G12D)/Pdx1-Cre mice. Forty-five LSL-Kras(G12D)/Pdx1-Cre mice and 10 wild-type mice were subjected to one dose of caerulein (250 μg/kg body wt, intraperitoneally) at age 4 weeks to induce and synchronize the development of chronic pancreatitis and PanIN lesions. One week after caerulein induction, animals were randomly distributed into three groups and fed with either AIN-76A diet, AIN-76A diet containing 10 p.p.m. capsaicin or 20 p.p.m. capsaicin for a total of 8 weeks. The results showed that capsaicin significantly reduced the severity of chronic pancreatitis, as determined by evaluating the loss of acini, inflammatory cell infiltration and stromal fibrosis. PanIN formation was frequently observed in the LSL-Kras(G12D)/Pdx1-Cre mice. The progression of PanIN-1 to high-grade PanIN-2 and -3 were significantly inhibited by capsaicin. Further immunochemical studies revealed that treatment with 10 and 20 p.p.m. capsaicin significantly reduced proliferating cell nuclear antigen-labeled cell proliferation and suppressed phosphorylation of extracellular signal-regulated kinase (ERK) and c-Jun as well blocked Hedgehog/GLI pathway activation. These results indicate that capsaicin could be a promising agent for the chemoprevention of pancreatic carcinogenesis, possibly via inhibiting pancreatitis and mutant Kras-led ERK activation.

Role of decursin in TNF-α-stimulated migration, invasion, and matrix metalloproteinase-9 induction in vascular smooth muscle cells

Decursin, isolated from the roots of danggui (Angelicae gigas), has been showed many physiological effects. However, the effects of decursin on cardiovascular diseases such as atherosclerosis were not elucidated. Treatment with a low concentration of decursin (10–20 μM) showed a significant decrease in invasion and migration by matrigel invasion assay and wound-healing analysis in tumor necrosis factor-α (TNF-α)-treated vascular smooth muscle cells (VSMC). MTT assay, however, showed no effect on cell viability. Addition of decursin in TNF-α-induced VSMC in zymograhic and immunoblot experiments showed strong inhibition of both matrix metallopeptidase-9 (MMP-9) expression and activation of TNF-α-induced transcriptional MMP-9 promoter, which was mediated by suppression of nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) binding activities. These results demonstrate that decursin suppresses invasion and migration by inhibition of MMP-9 expression via reducing the binding activities of NF-κB and AP-1 in TNF-α-treated VSMC.

Endometrial Epithelial Cell Responses to Coinfecting Viral and Bacterial Pathogens in the Genital Tract Can Activate the HIV-1 LTR in an NFκB-and AP-1–Dependent Manner

Sexually transmitted infections (STIs) are associated with increased human immunodeficiency virus type 1 (HIV-1) susceptibility and viral shedding in the genital tract, but the mechanisms underlying this association are poorly understood. Direct activation of HIV long terminal repeats (LTRs), a proxy measure for HIV-1 replication, was measured after treatment of 1G5 T cells with Toll-like receptor (TLR) ligands, herpes simplex virus type 1 or 2 (HSV-1/2), or Neisseria gonorrhoeae. For indirect activation, 1G5 T cells were incubated with supernatants from female primary genital epithelial cells (GECs) previously exposed to these agents. Proinflammatory cytokines and chemokines were measured in GEC supernatants. Proinflammatory pathways were blocked to determine the mechanisms of direct and indirect HIV-LTR activation. HSV-1/2, N. gonorrhoeae, and TLR ligands FimH (TLR-4), flagellin (TLR-5), and Poly (I:C) (TLR-3) directly induced HIV-LTR activation in 1G5 T cells. Supernatants collected from GECs incubated with these agents indirectly induced HIV-LTR activation. Production of tumor necrosis factor α, interleukin 6, interleukin 8, and monocyte chemoattractant protein-1 was elevated in GECs exposed to copathogens. Inhibition of nuclear factor κB and activator protein-1 (AP-1) signaling pathways in 1G5 T cells abrogated both direct and indirect HIV-LTR activation. STIs may increase HIV-1 replication in the female genital tract via proinflammatory signaling pathways directly and indirectly via their effects on GECs. This increased HIV-1 replication may enhance sexual and vertical HIV transmission.

Inhibition of Egr-1 by siRNA in prostate carcinoma cell lines is associated with decreased expression of AP-1 and NF-κB

Previous studies suggest that the effects of Egr-1 on tumorigenesis are critically dependent on the levels of Egr-1 and the cellular context. For this reason, we examined the effects of blocking the Egr-1 activity by a short interfering RNA (siRNA) against Egr-1 on the expression of nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) signaling in the PC-3 and LNCaP prostate carcinoma cell lines. We observed that the reduction in expression of Egr-1 in PC-3 and LNCaP cells by effects of the siRNA vector resulted in lower cell viability and increased apoptosis at 24 and 120 h after transfection. This reduced cell viability correlated well with a reduced activity of the NF-κB and AP-1 factors. We analyzed the expression and activity of these factors and found that p65 and IκB but not p50 were reduced in the siRNA-treated cells. Similarly, we found that c-Fos but not c-Jun was reduced in the siRNA treated cells. These effects were translated to reduced transcriptional activity of NF-κB over cellular inhibitor of apoptosis (cIAP) and p21 genes, as assayed by RT-PCR and of AP-1 over a luciferase reporter activated by AP-1 response elements. Egr-1 was also found to interact directly with p65 and IκB members of the NF-κB family, thereby was able to regulate directly their activity by post-transcriptional effects. These results suggest that Egr-1 may promote prostate cancer development by modulating the activity of factors NF-κB and AP-1, which are involved in cell proliferation and apoptosis.

Modulation of Pancreatic Cancer Chemoresistance by Inhibition of TAK1

TGF-β-activated kinase-1 (TAK1), a mitogen-activated protein kinase kinase kinase, functions in the activation of nuclear factor κB (NF-κB) and activator protein-1, which can suppress proapoptotic signaling pathways and thus promote resistance to chemotherapeutic drugs. However, it is not known if inhibition of TAK1 is effective in reducing chemoresistance to therapeutic drugs against pancreatic cancer. NF-κB activity was measured by luciferase reporter assay in human pancreatic cancer cell lines AsPc-1, PANC-1, and MDAPanc-28, in which TAK1 expression was silenced by small hairpin RNA. TAK1 kinase activity was targeted in AsPc-1, PANC-1, MDAPanc-28, and Colo357FG cells with exposure to increasing doses of a selective small-molecule inhibitor, LYTAK1, for 24 hours. To test the effect of LYTAK1 in combination with chemotherapeutic agents, AsPc-1, PANC-1, MDAPanc-28 cells, and control cells were treated with increasing doses of oxaliplatin, SN-38, or gemcitabine in combination with LYTAK1. In vivo activity of oral LYTAK1 was evaluated in an orthotopic nude mouse model (n = 40, 5 per group) with luciferase-expressing AsPc-1 pancreatic cancer cells. The results of in vitro proliferation were analyzed for statistical significance of differences by nonlinear regression analysis; differences in mouse survival were determined using a log-rank test. All statistical tests were two-sided. AsPc-1 and MDAPanc-28 TAK1 knockdown cells had a statistically significantly lower NF-κB activity than did their respective control cell lines (relative luciferase activity: AsPc-1, mean = 0.18, 95% confidence interval [CI] = 0.10 to 0.27; control, mean = 3.06, 95% CI = 2.31 to 3.80; MDAPanc-28, mean = 0.30, 95% CI = 0.13 to 0.46; control, mean = 4.53, 95% CI = 3.43 to 5.63; both P < .001). TAK1 inhibitor LYTAK1 had potent in vitro cytotoxic activity in AsPc-1, PANC-1, MDAPanc-28, and Colo357FG cells, with IC(50) between 5 and 40 nM. LYTAK1 also potentiated the cytotoxicity of chemotherapeutic agents oxaliplatin, SN-38, and gemcitabine in AsPc-1, PANC-1, and MDAPanc-28 cells compared with control cells (P < .001). In nude mice, oral administration of LYTAK1 plus gemcitabine statistically significantly reduced tumor burden (gemcitabine vs gemcitabine plus LYTAK1, P = .03) and prolonged survival duration (median survival: gemcitabine, 82 days vs gemcitabine plus LYTAK1, 122 days; hazard ratio = 0.334, 95% CI = 0.027 to 0.826, P = .029). The results of this study suggest that genetic silencing or inhibition of TAK1 kinase activity in vivo is a potential therapeutic approach to reversal of the intrinsic chemoresistance of pancreatic cancer.

Copper chelation by tetrathiomolybdate inhibits lipopolysaccharide-induced inflammatory responses in vivo

Redox-active transition metal ions, such as iron and copper, may play an important role in vascular inflammation, which is an etiologic factor in atherosclerotic vascular diseases. In this study, we investigated whether tetrathiomolybdate (TTM), a highly specific copper chelator, can act as an anti-inflammatory agent, preventing lipopolysaccharide (LPS)-induced inflammatory responses in vivo. Female C57BL/6N mice were daily gavaged with TTM (30 mg/kg body wt) or vehicle control. After 3 wk, animals were injected intraperitoneally with 50 μg LPS or saline buffer and killed 3 h later. Treatment with TTM reduced serum ceruloplasmin activity by 43%, a surrogate marker of bioavailable copper, in the absence of detectable hepatotoxicity. The concentrations of both copper and molybdenum increased in various tissues, whereas the copper-to-molybdenum ratio decreased, consistent with reduced copper bioavailability. TTM treatment did not have a significant effect on superoxide dismutase activity in heart and liver. Furthermore, TTM significantly inhibited LPS-induced inflammatory gene transcription in aorta and heart, including vascular and intercellular adhesion molecule-1 (VCAM-1 and ICAM-1, respectively), monocyte chemotactic protein-1 (MCP-1), interleukin-6, and tumor necrosis factor (TNF)-α (ANOVA, P < 0.05); consistently, protein levels of VCAM-1, ICAM-1, and MCP-1 in heart were also significantly lower in TTM-treated animals. Similar inhibitory effects of TTM were observed on activation of nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) in heart and lungs. Finally, TTM significantly inhibited LPS-induced increases of serum levels of soluble ICAM-1, MCP-1, and TNF-α (ANOVA, P < 0.05). These data indicate that copper chelation with TTM inhibits LPS-induced inflammatory responses in aorta and other tissues of mice, most likely by inhibiting activation of the redox-sensitive transcription factors, NF-κB and AP-1. Therefore, copper appears to play an important role in vascular inflammation, and TTM may have value as an anti-inflammatory or anti-atherogenic agent.

Albumin overload activates intrarenal renin–angiotensin system through protein kinase C and NADPH oxidase-dependent pathway

Inappropriate activation of the intrarenal renin-angiotensin system (RAS) plays an important role in the pathogenesis of hypertension and renal injury. However, the underlying mechanisms remain elusive. Proteinuria has been shown to elicit the renal activation of RAS. The present study was performed to test the intracellular signal pathway involved in albumin-triggered activation of RAS. NRK52E cells, a rat renal proximal tubular cell line, were incubated with increased levels of albumin. The rat model of protein overload was established in female Wistar-Kyoto rats that were subjected to unilateral nephrectomy followed by daily intraperitoneal injection of BSA at various doses (0.5, 1.0, and 5.0 g/kg) or combination with intragastric administration of apocynin (100 mg/kg per day), an inhibitor of NADPH oxidase. Exposure of the cells to high levels of albumin activated the RAS through the endocytic receptors megalin and cubilin. High levels of albumin triggered the production of intracellular reactive oxygen species by a protein kinase C (PKC)-NADPH oxidase-dependent pathway and this, in turn, led to activation of nuclear factor-κB (NF-κB) and activation protein-1 (AP-1). Inhibition of PKC or NADPH oxidase abolished albumin-induced activation of RAS. In a protein overload rat model, activation of RAS in renal proximal tubular cells was significantly increased, coincident with activation of PKC, NADPH oxidase, NF-κB, and AP-1. Chronic inhibition of NADPH oxidase by apocynin largely ameliorated intrarenal activation of RAS. Exposure of renal tubular epithelial cells with high levels of albumin triggers activation of RAS via a PKC-NADPH oxidase-dependent pathway.

Luteolin, a Novel Natural Inhibitor of Tumor Progression Locus 2 Serine/Threonine Kinase, Inhibits Tumor Necrosis Factor-α-Induced Cyclooxygenase-2 Expression in JB6 Mouse Epidermis Cells

Targeting tumor necrosis factor (TNF)-α-mediated signal pathways may be a promising strategy for developing chemopreventive agents, because TNF-α-mediated cyclooxygenase (COX)-2 expression plays a key role in inflammation and carcinogenesis. Luteolin [2-(3,4-dihydroxyphenyl)-5,7-dihydroxy-4-chromenone] exerts anticarcinogenic effects, although little is known about the underlying molecular mechanisms and specific targets of this compound. In the present study, we found that luteolin inhibited TNF-α-induced COX-2 expression by down-regulating the transactivation of nuclear factor-κB and activator protein-1. Furthermore, luteolin inhibited TNF-α-induced phosphorylation of mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase 1/ERK/p90(RSK), mitogen-activated protein kinase kinase 4/c-Jun N-terminal kinase/c-Jun, and Akt/p70(S6K). However, it had no effect on the phosphorylation of p38. These effects of luteolin on TNF-α-mediated signaling pathways and COX-2 expression are similar to those achieved by blocking tumor progression locus 2 serine/threonine kinase (TPL2) using pharmacologic inhibitors and small interfering RNAs. Luteolin inhibited TPL2 activity in vitro and in TPL2 immunoprecipitation kinase assays by binding directly in an ATP-competitive manner. Overall, these results indicate that luteolin exerts potent chemopreventive activities, which primarily target TPL2.

The effect of nano-silver on the activation of nasal polyp epithelial cells by Alternaria, Der P1 and staphylococcal enterotoxin B

Nano-silver is used for its anti-bacterial, anti-viral and anti-fungal properties. The aim of this study was to investigate the potential clinical efficacy of nano-silver for its anti-inflammatory effect on respiratory epithelial cell inflammation. Primary nasal polyp epithelial cells (NPECs) were exposed to Alternaria alternata, Der P1, and staphylococcal enterotoxin B for 48h with or without various concentration of nano-silver, then the supernatants were collected. Cell cytotoxicities were measured using a CellTiter-96® aqueous cell proliferation assay kit. The interleukin (IL)-6, IL-8 and granulocyte-macrophage colony stimulating factor were measured to evaluate the inflammatory effects on the epithelial cells. Nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) were analyzed using western blot and ELISA method. Cell survival was found to be significantly decreased at nano-silver concentrations exceeding 10ppm. Alternaria, Der P1 and SEB activated NPECs with increased cytokine production. Alternaria induced NPECs not inhibited by nano-silver. However, Der P1 and SEB induced cytokine production was significantly affected by concentrations over 1ppm. Alternaria, Der P1 and SEB enhanced nuclear NF-κB expression and nano-silver inhibited NF-κB expression in SEB and Der P1 treated group. Although nano-silver is cytotoxic at higher concentrations, at safe concentrations it can inhibit the activation of NPECs. This finding suggests a novel pharmacological rationale for the treatment of airway inflammation and/or immunological disease.

TSPO-specific ligand Vinpocetine exerts a neuroprotective effect by suppressing microglial inflammation

Vinpocetine has long been used for cerebrovascular disorders and cognitive impairment. Based on the evidence that the translocator protein (TSPO, 18kDa) was expressed in activated microglia, while Vinpocetine was able to bind TSPO, we explored the role of Vinpocetine on microglia treated with lipopolysaccharide (LPS) and oxygen-glucose deprivation (OGD) in vitro. Our results show that both LPS and OGD induced the up-regulation of TSPO expression on BV-2 microglia by RT-PCR, western blot and immunocytochemistry. Vinpocetine inhibited the production of nitrite oxide and inflammatory factors such as interleukin-1β (IL-1β), IL-6 and tumour necrosis factor-α (TNF-α) in BV-2 microglia, in which cells were treated with LPS or exposed to OGD, regardless of the time Vinpocetine was added. Next, we measured cell death-related molecules Akt, Junk and p38 as well as inflammation-related molecules nuclear factor-κB (NF-κB) and activator protein-1 (AP-1). Vinpocetine did not change cell death-related molecules, but inhibited the expression of NF-κB and AP-1 in LPS-stimulated microglia, indicating that Vinpocetine has an anti-inflammatory effect by partly targeting NF-κB/AP-1. Next, conditioned medium from Vinpocetine-treated microglia protected from primary neurons. As compared with in vitro, the administration of Vinpocetine in hypoxic mice also inhibited inflammatory molecules, indicating that Vinpocetine as a unique anti-inflammatory agent may be beneficial for the treatment of neuroinflammatory diseases.

Chitosan oligosaccharides suppress LPS-induced IL-8 expression in human umbilical vein endothelial cells through blockade of p38 and Akt protein kinases

To investigate whether and how COS inhibited IL-8 production in LPS-induced human umbilical vein endothelial cells (HUVECs). RT-PCR, enzyme-linked immunosorbent assays (ELISA) and Western blotting were used to study IL-8 expression and related signaling pathway. Wound healing migration assays and monocytic cell adhesion analysis were used to explore the chemotactic and adhesive activities of HUVECs. COS 50-200 μg/mL exerted a significant inhibitory effect on LPS 100 ng/mL-induced IL-8 expression in HUVECs at both the transcriptional and translational levels. In addition, COS 50-200 μg/mL inhibited LPS-induced HUVEC migration and U937 monocyte adhesion to HUVECs in a concentration-dependent manner. Signal transduction studies suggest that COS blocked LPS-induced activation of nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) as well as phosphorylation of p38 mitogen-activated protein kinase (MAPK) and phosphokinase Akt. Further, the over-expression of LPS-induced IL-8 mRNA in HUVECs was suppressed by a p38 MAPK inhibitor (SB203580, 25 μmol/L) or a phosphatidylinositol 3-kinase (PI3K) inhibitor (LY294002, 50 μmol/L). COS inhibited LPS-induced IL-8 expression in HUVECs through the blockade of the p38 MAPK and PI3K/Akt signaling pathways.

Chitosan oligosaccharides inhibit LPS-induced over-expression of IL-6 and TNF-α in RAW264.7 macrophage cells through blockade of mitogen-activated protein kinase (MAPK) and PI3K/Akt signaling pathways

Chitosan oligomers show various biological activities. However, its molecular mechanisms remain unknown in LPS-stimulated macrophages. Here, we explored the inhibitive effects of chitosan oligomers on LPS-induced IL-6/TNF-α production in macrophages. The results indicated chitosan oligomers pretreatment effectively inhibited LPS-induced over-expression of both inflammatory cytokines. Signal transduction studies show chitosan oligomers may repress not only the phosphorylation of p38, ERK1/2, JNK, phosphatidylinositol 3-kinase (PI3K) and Akt, but also the activation of nuclear factor-κB (NF-κB) and activator protein-1 (AP-1). Furthermore, both the activation of NF-κB/AP-1 and the subsequent IL-6/TNF-α over-expression in LPS-induced macrophages are inhibited by specific p38 inhibitor (SB203580), ERK1/2 inhibitor (PD98059), JNK inhibitor (SP600125) and PI3K inhibitor (LY294002). In conclusion, our investigation suggests chitosan oligomers inhibited the elevated expression of IL-6/TNF-α in LPS-induced macrophages, regulated by MAPKs and PI3K/Akt pathways dependent on NF-κB/AP-1 activation.

Basic and Translational Understandings of Microbial Recognition by Toll-Like Receptors in the Intestine

Microbial recognition by multicellular organisms is initially accomplished by a group of pattern recognition receptors which are specialized to recognize microbe-associated molecular patterns (MAMPs) such as lipopolysaccharide, bacterial lipoprotein, CpG DNA motif, double strand RNA and flagellin. Toll-like receptors (TLRs) are the representative pattern recognition receptors, and microbial recognition by TLRs elicits innate and inflammatory responses. Ten TLR family members have been presently identified in human genome, and numerous studies discovered that intracellular responses from MAMPs-TLR engagements are mediated by a participation of at least 4 immediate adaptor molecules such as myeloid differentiation primary response gene-88 (MyD88), MyD88 adaptor-like (Mal) (also known as Toll/IL-1 receptor domain-containing adaptor protein [TIRAP]), Toll/IL-1 receptor domain-containing adaptor-inducing interferon-β (TRIF) and TRIF-related adaptor molecule (TRAM) leading to activate transcription factors including nuclear factor κB, activator protein-1 and interferon-regulatory factors. Given that large amounts of commensal microbiota constantly reside in the intestinal lumen, enteric microbial recognition by TLRs at the intestinal epithelium provides a critical impact on regulating intestinal homeostasis. Indeed, aberrant TLR4 and TLR5 activations are etiologically associated with the development and progress of intestinal inflammatory diseases including inflammatory bowel disease and necrotizing enterocolitis. In this review article, we present the molecular mechanism by which TLRs elicit intracellular signal transduction, and summarize the physiological relevance of TLRs related to the gastrointestinal tract.

Morus bombycis Koidzumi extract suppresses collagen-induced arthritis by inhibiting the activation of nuclear factor-κB and activator protein-1 in mice

Morus bombycis Koidzumi is widely distributed in Asia. In Korea, it has been used in traditional medicine because of its apparent anti-inflammatory, antioxidant, and hepatoprotective properties. Although the extract of Morus bombycis Koidzumi (MB) has long since been used as a traditional anti-inflammatory medicine in Korea, its effect on arthritis remains unknown. We aimed to investigate the anti-arthritis activity of MB and the mechanism underlying it. The anti-arthritis activity of MB was assessed by using mouse models of type II collagen-induced arthritis (CIA). The clinical arthritis index and histopathological changes were evaluated in mice. Reverse transcriptase-polymerase chain reaction (RT-PCR), electrophoretic mobility shift assay (EMSA), and other biologic approaches were used for measuring the effect of MB on arthritis and understanding the underlying mechanism. MB significantly decreased the clinical arthritis index in CIA mice; this was confirmed by examining histological changes in joints. Infiltration of immune cells, synovial hyperplasia, cartilage destruction, and bone erosion in the hind paw were largely suppressed by MB. The mRNA levels of matrix metalloproteinase (MMP)-1/MMP-3, inflammatory cytokines (tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6), and chemokines (macrophage inflammatory protein (MIP)-1, monocyte chemoattractant protein (MCP)-1, RANTES) were significantly suppressed by MB in a dose-dependent manner. The number of osteoclasts in the hind tibia was also significantly decreased. With regard to the mechanism, MB suppressed the activation of nuclear factor (NF)-κB and activator protein (AP)-1 in CIA mice. MB produced an anti-arthritis effect in CIA mice by inhibiting the production of critical inflammatory mediators and osteoclasts through the downregulation of NF-κB and AP-1.

Role of Angiotensin II Type 1 Receptor in Angiotensin II-Induced Cytokine Production in Macrophages

This study was aimed to investigate the regulatory effects of angiotensin II (Ang II) on the expression of Ang II type 1 (AT1) receptor and to characterize the mechanism underlying AT1 receptor promotion of inflammatory cytokines and reactive oxygen species (ROS). The RAW 264.7 cells were stimulated with various concentrations of Ang II for different times. The mRNA and protein expressions of AT1 receptor in the cells were determined by reverse transcriptase-polymerase chain reaction and Western blot analysis, respectively. The macrophages secretion of proinflammatory cytokines tumor necrosis factor-α, interleukin-1β (IL-1β), IL-6, and anti-inflammatory cytokine IL-10 and generation of ROS (by flow cytometry) were also examined. Nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) activities were determined by electrophoretic mobility shift assay. Ang II resulted in an upregulation of AT1 receptor expression in dose- and time-dependent manners in macrophages. Ang II not only induced the production of tumor necrosis factor-α, IL-1β, IL-6, and IL-10 but also increased the release of ROS. Further, both NF-κB and AP-1 were activated after stimulation with Ang II. However, these events were all abolished by preincubation with ZD7155, a selective competitive antagonist for the AT1 receptor. These results suggest that the AT1 receptor plays an important role in Ang II-induced cytokines production and ROS release via NF-κB and AP-1 pathways in macrophages.

Inhibitory effect of esculetin on migration, invasion and matrix metalloproteinase-9 expression in TNF-α-induced vascular smooth muscle cells

Esculetin, a potent non-competitive inhibitor of lipoxygenase, has been shown to inhibit vascular smooth muscle cell (VSMC) proliferation. However, the effect of esculetin on the matrix metalloproteinase-9 (MMP-9) regulation responsible for cell migration and invasion has not been previously investigated. The results of the present study showed the esculetin (12.5-25 µg/ml) induced the inhibition of migration and invasion in tumor necrosis factor-α (TNF-α)-treated VSMC, as demonstrated by a matrigel invasion assay and wound healing analysis. However, esculetin did not affect cell viability in TNF-α-treated VSMC under 0-25 µg/ml concentration conditions. In addition, both zymographic and immunoblot experiments showed that esculetin suppressed the TNF-α-induced expression of MMP-9 in VSMC in a dose-dependent manner. Furthermore, the treatment of cells with esculetin decreased the activity of the TNF-α-induced MMP-9 promoter, which was driven by a luciferase reporter. Finally, esculetin reduced the binding activities of nuclear factor-κB (NF-κB) and activator protein-1 (AP-1), which are cis-elements present in the promoter of the MMP-9 gene, in TNF-α-treated VSMC. Taken together, these results demonstrated that esculetin decreased the migration and invasion of cells by suppressing MMP-9 expression, which subsequently reduced the binding activities of NF-κB and AP-1 in TNF-α-treated VSMC. These novel findings provide basic information for effective therapeutic treatment with esculetin for atherosclerotic disease.