The NF-kappaB pathway

Toll-like receptor triggering in cord blood mesenchymal stem cells

Recently, the antagonizing effect on the differentiation of mesenchymal stem cells (MSCs) by toll-like receptor (TLR) ligands, was described. Our study shows that on more primitive cord blood derived MSCs, the expression of TLRs and ligand-induced triggering differs from that of bone marrow derived MSCs. At the RNA level, cord blood MSCs (unrestricted somatic stem cells; USSCs) express low levels of TLR1,3,5,9 and high levels of TLR4 and TLR6. At the protein level expression of TLR5 and very low expression of TLR4 was observed. NF-κB translocation studies revealed that both TLR4 and TLR5 are functional, although signalling kinetics induced by the individual ligands differed. Stimulation of USSCs with either lipopolysaccharide (LPS) or flagellin resulted in a marked increase of interleukin (IL)-6 and/or IL-8 production although levels differed significantly between both stimuli. Interestingly, tumour necrosis factor (TNF)-α was undetectable after TLR stimulation, which appeared to be due to an inactivated TNF-α promoter in USSCs. Moreover, osteoblastic differentiation was enhanced after triggering USSCs with LPS and flagellin. In summary, TLR4 and 5 signalling in USSCs is slow and results in the up-regulation of a restricted number of pro-inflammatory cytokines and enhanced osteoblastic differentiation. Apparently, the outcome of TLR signalling depends on the cell type that expresses them.

NF-κB knockdown can modulate amphetamine-mediated feeding response

This study determined if transcription factor NF-κB is involved in the effect of amphetamine (AMPH)-mediated feeding response. Moreover, possible roles of hypothalamic neuropeptide Y (NPY) and proopiomelanocortin (POMC) were also investigated. AMPH was administered daily to rats for four days. Changes in NF-κB, NPY and POMC expression were assessed and compared. The NPY gene was down-regulated with maximal response on Day 2 during AMPH treatment, which was consistent with the response to feeding behavior. In contrast, NF-κB and POMC genes were up-regulated, and their expression was increased by about 200% and 450%, respectively, with maximal response on Day 2. Moreover, NF-κB DNA binding ability and expression were increased similar to that of POMC. To examine further if NF-κB was involved, intracerebroventricular infusion of NF-κB antisense oligonucleotide was performed 1 h before the daily AMPH dosing in freely moving rats. Results showed that NF-κB knockdown could modify AMPH anorexia as well as NPY and POMC expression. The present findings prove that cerebral NF-κB participates in AMPH-mediated appetite suppression, possibly by modulating NPY and POMC expression. These results may aid in therapeutic research on AMPH and AMPH-like anti-obesity drugs.

Expression of NF-κB p65 phosphorylated at serine-536 in rectal cancer with or without preoperative radiotherapy

BACKGROUND

In the present study, we investigated NF-κB p65 phosphorylated at Serine-536 (phosphor-Ser536-p65) in rectal cancer and its relationship to preoperative radiotherapy (RT), clinicopathological variables and biological factors.

PATIENTS AND METHODS

Expression of phosphor-Ser536-p65 was examined by using immunohistochemistry in 141 primary rectal cancers, 149 normal mucosa specimens and 48 metastases in the lymph nodes, from rectal cancer patients who participated in a Swedish clinical trial of preoperative RT.

RESULTS

The expression of phosphor-Ser536-p65 in the cytoplasm increased from normal mucosa to primary tumour (p<0.0001, for both the group that did and the group that did not received RT). The expression did not further increase from primary tumour to metastasis in either group (p>0.05). Expression of phosphor-Ser536-p65 was positively related to, or tended to be related to, the expression of tumour endothelium marker 1 (TEM1, p=0.02), FXYD-3 (p=0.001), phosphatase of regenerating liver (PRL, p=0.02), p73 (p=0.048) and meningioma associated protein (MAC30, p=0.05) in the group that received RT but there were no such relationships in the group that did not received RT (p>0.05). The expression of phosphor-Ser536-p65 was not related to clinicopathological factors including survival (p>0.05).

CONCLUSIONS

The increased expression of phosphor-Ser536-p65 may be involved in rectal cancer development. After RT, phosphor-Ser536-p65 seems to be positively related to the biological factors, which associated with more malignant features of tumours. However, phosphor-Ser536-p65 was not directly related to the response of RT based on recurrence and survival.

Consequences of alteration in leucine zipper sequence of melittin in its neutralization of lipopolysaccharide-induced proinflammatory response in macrophage cells and interaction with lipopolysaccharide

The bee venom antimicrobial peptide, melittin, besides showing versatile activity against microorganisms also neutralizes lipopolysaccharide (LPS)-induced proinflammatory responses in macrophage cells. However, how the amino acid sequence of melittin contributes in its anti-inflammatory properties is mostly unknown. To determine the importance of the leucine zipper sequence of melittin in its neutralization of LPS-induced inflammatory responses in macrophages and interaction with LPS, anti-inflammatory properties of melittin and its three analogues and their interactions with LPS were studied in detail. Two of these analogues, namely melittin Mut-1 (MM-1) and melittin Mut-2 (MM-2), possess leucine to alanine substitutions in the single and double heptadic leucine residue(s) of melittin, respectively, whereas the third analogue is a scrambled peptide (Mel-SCR) that contains the amino acid composition of melittin with minor rearrangement in its leucine zipper sequence. Although MM-1 partly inhibited the production of proinflammatory cytokines in RAW 264.7 and rat primary macrophage cells in the presence of LPS, MM-2 and Mel-SCR were negligibly active. A progressive decrease in interaction of melittin with LPS, aggregation in LPS, and dissociation of LPS aggregates with alteration in the leucine zipper sequence of melittin was observed. Furthermore, with alteration in the leucine zipper sequence of melittin, these analogues failed to exhibit cellular responses associated with neutralization of LPS-induced inflammatory responses in macrophage cells by melittin. The data indicated a probable important role of the leucine zipper sequence of melittin in neutralizing LPS-induced proinflammatory responses in macrophage cells as well as in its interaction with LPS.

Hypoxia induces cysteine-rich 61, vascular endothelial growth factor, and interleukin-8 expressions in human nasal polyp fibroblasts: An implication of neutrophils in the pathogenesis of nasal polyposis

BACKGROUND

The purpose of this article was to elucidate the roles of neutrophils and angiogenesis factors in the pathogenesis of nasal polyposis. The effect of hypoxia on the expressions of angiogenesis factors as cysteine-rich 61 (Cyr61) and vascular endothelial growth factor (VEGF) and neutrophil chemoattractant as interleukin (IL)-8 in nasal polyp fibroblasts (NPFs), and the role of nuclear factor kappa B (NF-kappaB) in this reaction were investigated. The action of Cyr61 on the synthesis of VEGF and IL-8 in NPFs was also examined.

METHODS

Primary cultures of NPFs were established from nasal polyps (NPs). Productions of Cyr61, VEGF, and IL-8 by NPFs under hypoxia were detected by Western blot (Cyr61 and VEGF) or enzyme-linked immunosorbent assay (ELISA; IL-8). Immunohistochemical staining was used to examine the relation between fibroblastic expression of Cyr61 and neovascularization/neutrophil infiltration in NPs.

RESULTS

Western blot showed that the hypoxia inducer CoCl(2) stimulated Cyr61 synthesis in NPFs in a time-dependent manner, reaching a peak at 24 hours. Bay-117082 (a specific NF-kappaB inhibitor) attenuated the levels of Cyr61 stimulated by hypoxia. Cyr61 induced IL-8 secretion and VEGF synthesis by NPFs, as evidenced by Western blot and ELISA analysis. Bay-117082 abolished hypoxia-stimulated IL-8 and VEGF synthesis, whereas Cyr61 restored the stimulative effect of hypoxia readily. Immunohistochemical staining revealed the presence of Cyr61 and IL-8 in NPFs. Neutrophils and capillaries aggregating around these NPFs were frequently found.

CONCLUSION

Under hypoxia, NPFs contribute to NP propagation by expressing Cyr61, which subsequently stimulates VEGF and IL-8 production, leading to angiogenesis and activating neutrophil infiltration in NPs.

Ginsenoside Rg5 ameliorates lung inflammation in mice by inhibiting the binding of LPS to toll-like receptor-4 on macrophages

Heating and steaming processes have been applied to various natural medicines for either enhancing or altering their pharmacological activities, and the chemical compositions of the active components. While ginsenoside Rb1, which is the major constituent of raw ginseng, has been studied extensively for its anti-inflammatory effect, the biological activity of ginsenoside Rg5, a major constituent of steamed ginseng, remains to be explored. Here, we isolated Rg5 and examined anti-inflammatory effect in lipopolysaccharide (LPS)-stimulated macrophages and on LPS-induced lung inflammation. Rg5 inhibited the expression of proinflammatory cytokines, IL-1β and TNF-α, as well as inflammatory enzymes, COX-2 and iNOS in LPS-stimulated alveolar macrophages. Rg5 also reduced LPS-induced phosphorylation of IL-1 receptor-associated kinases (IRAK)-1 and IKK-β, as well as the degradation of IRAK-1 and IRAK-4. Rg5 inhibited the phosphorylation of NF-κB as well as the translocation of p65 into the nucleus. When macrophages were treated with Alexa Fluor 594-conjugated LPS in the presence of Rg5, the fluorescence intensity of LPS observed outside the cell membrane was lower than that in LPS-stimulated alveolar macrophages alone. Rg5, inhibited the levels of protein and neutrophils in bronchoalveolar lavage fluid of LPS-stimulated mice, as well as pro-inflammatory cytokines, TNF-α and IL-1β. Rg5 also inhibited iNOS and COX expressions, and NF-κB activation in LPS-stimulated lung inflammation of mice. The inhibitory effect of Rg5 (10 mg/kg) was comparable to that of dexamethasone (5 mg/kg). Based on these findings, Rg5 can ameliorate lung inflammation possibly by inhibiting the binding of LPS to toll-like receptor (TLR)-4 on macrophages.

Cytokines in dermatology - a basic overview

Cytokines are non-immunoglobulin proteins and glycoproteins produced by a wide variety of cells, in response to any immune stimulus. Cytokines are signaling molecules that send downstream signals to various cells through a number of signal transduction pathways and act further by binding to specific membrane receptors (cytokine receptors) on the cell surface. They are emergency molecules, which are released transiently. Cytokines play an important role in cellular communication. They regulate immunity, inflammation, cell activation, cell migration, cell proliferation, apoptosis, and hematopoiesis. However, when released persistently they can produce chronic disease

Nuclear factor κB subunits RelB and cRel negatively regulate Toll-like receptor 3-mediated β-interferon production via induction of transcriptional repressor protein YY1

The induction of β-interferon (IFN-β) is a key anti-viral response to infection by RNA viruses. Virus-induced expression of IFN-β requires the co-operative action of the transcription factors IRF-3/7, NF-κB, and ATF-2/c-Jun on the IFN-β promoter leading to the orderly recruitment of chromatin remodeling complexes. Although viruses strongly activate NF-κB and promote its binding to the IFN-β promoter, recent studies have indicated that NF-κB is not essential for virus-induced expression of IFN-β. Herein, we examined the role of NF-κB in regulating IFN-β expression in response to the viral-sensing Toll-like receptor 3 (TLR3). Intriguingly pharmacological inhibition of the NF-κB pathway augments late phase expression of IFN-β expression in response to TLR3 stimulation. We show that the negative effect of NF-κB on IFN-β expression is dependent on the induction of the transcriptional repressor protein YinYang1. We demonstrate that the TLR3 ligand polyriboinosinic:polyribocytidylic acid (poly(I:C)) induces expression and nuclear translocation of YinYang1 where it interacts with the IFN-β promoter and inhibits the binding of IRF7 to the latter. Evidence is also presented showing that the NF-κB subunits c-Rel and RelB are the likely key drivers of these negative effects on IFN-β expression. These findings thus highlight for the first time a novel self-regulatory mechanism that is employed by TLR3 to limit the level and duration of IFN-β expression.

Critical roles of cold shock domain protein A as an endogenous angiogenesis inhibitor in skeletal muscle

Angiogenesis is regulated by the local balance between angiogenic stimulators and inhibitors and is maintained by muscle-derived angiogenic factors in ischemic tissues.

AIMS

Our objectives were to investigate the effect of cold shock domain protein A (CSDA) as an endogenous angiogenesis inhibitor and to develop a novel strategy of therapeutic angiogenesis by blocking CSDA expression.

RESULTS

In human skeletal muscle cells, CSDA was upregulated during hypoxia when cells were damaged and apoptosis was induced. CSDA expression could repress the activity of hypoxia inducible factor-1α and nuclear factor κB, because CSDA can competitively bind the hypoxia response element and the nuclear factor κB-binding element. As a result, vascular endothelial growth factor-A, interleukin-6, and interleukin-8 secretions from skeletal muscle cells were decreased. Further, CSDA depletion increased the secretion level of these angiogenic factors. In a hindlimb ischemia model, transfer of short-hairpin RNA targeting CSDA ameliorated ischemia without direct transfer of angiogenic factors. In this ischemic tissue, vascular endothelial growth factor-A, interleukin-6, and CXCL2 protein levels were increased.

INNOVATION AND CONCLUSION

CSDA appears to play a critical role as an endogenous angiogenesis inhibitor in skeletal muscle, and RNA interference targeting of CSDA is a promising gene therapy strategy for treating peripheral arterial disease.

Knocking down the transcript of NF-kappaB modulates the reciprocal regulation of endogenous antioxidants and feeding behavior in phenylpropanolamine-treated rats

It has been reported that oxidative stress, antioxidants, and neuropeptide Y (NPY) are involved in regulating the feeding behavior of phenylpropanolamine (PPA), a sympathomimetic drug. This study explored whether transcription factor NF-κB is involved in this effect. Rats were treated daily with PPA for 4 days. Changes in hypothalamic NF-κB, NPY, superoxide dismutase (SOD), and glutathione peroxidase (GPx) levels during PPA treatment were assessed and compared. Results showed that NF-κB, SOD, and GPx increased, with a maximal response on Day 2, while the food intake and NPY decreased with the biggest reduction on Day 2 during PPA treatment. To further determine whether NF-κB was involved, intracerebroventricular infusion of antisense oligonucleotide was performed at 1 h before daily PPA in free-moving rats. Cerebral NF-κB knockdown could modify PPA anorexia and the expressions of NPY, SOD, and GPx. It is suggested that hypothalamic NF-κB participates in the reciprocal regulation of NPY and antioxidants, which mediated the appetite-suppressing effect of PPA. Results may further the understanding of the molecular mechanisms of PPA.

Breast cancer stem cells, cytokine networks, and the tumor microenvironment

Many tumors, including breast cancer, are maintained by a subpopulation of cells that display stem cell properties, mediate metastasis, and contribute to treatment resistance. These cancer stem cells (CSCs) are regulated by complex interactions with the components of the tumor microenvironment - including mesenchymal stem cells, adipocytes, tumor associated fibroblasts, endothelial cells, and immune cells - through networks of cytokines and growth factors. Since these components have a direct influence on CSC properties, they represent attractive targets for therapeutic development.

Soy protein prevents renal damage in a fructose-induced model of metabolic syndrome via inhibition of NF-kB in male rats

The study determines the effect of soy protein on inflammatory status and expression of nuclear factor-kappa B (NF-κB P(65)) and receptor for advanced glycation end products (RAGE) in a metabolic syndrome (MS) model. MS was induced in adult male rats by feeding them a high fructose diet (60 g/100 g diet). The rats were randomised into six groups by feeding one of the following semi-synthetic diets for 60 days: corn starch (60%) and casein (20%; CCD), fructose (60%) and casein (20%; FCD), fructose (60%) and soy protein (20%; FSD) or corn starch (60%) and soy protein (20%; CSD). The expression of NF-κB P(65), transforming growth factor-β1 (TGF-β1) and RAGE, histochemical localization of α-smooth muscle actin (α-SMA), tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) assays, collagen deposition and ultrastructural analysis were performed. FCD rats displayed inflammatory changes and increased expression of growth factors and nuclear factors. FSD rats showed reduction in inflammation, fibrogenesis, collagen deposition, NF-κB activation and mitigated the ultrastructural changes. Soy protein prevents inflammation and early nephropathic changes in the MS model secondary to the attenuation of NF-κB activation.

Regulation of cancer stem cells by cytokine networks: attacking cancer's inflammatory roots

There is substantial evidence that many human cancers are driven by a subpopulation of cells that display stem cell properties. These cancer stem cells (CSC) may also contribute to metastasis and treatment resistance. Furthermore, just as normal stem cells are regulated by their microenvironment, or niche, CSCs interact with and in turn are regulated by cells in the tumor microenvironment. These interactions involve inflammatory cytokines, such as interleukin (IL)-1, IL-6, and IL-8, which in turn activate Stat3/NF-κB pathways in both tumor and stromal cells. Activation of these pathways stimulates further cytokine production, generating positive feedback loops that in turn drive CSC self-renewal. These cytokine loops and the pathways they regulate resemble those activated during chronic inflammation and wound healing, and may contribute to the known link between inflammation and cancer. Inhibitors of these cytokines and their receptors have been developed as anti-inflammatory agents. By blocking signals from the tumor microenvironment, these agents have the potential to target CSCs. Future clinical trials using these compounds will be needed to determine whether targeting the CSC population has clinical benefit.

Antioxidant and anti-inflammatory effect of polysaccharides from Lobophora variegata on zymosan-induced arthritis in rats

This study analyzes the action of sulfated polysaccharides, fucans, from algae Lobophora variegata on zymosan-induced arthritis in rats. Groups of fucans, obtained after acetone fractionation (0.3-2.0 volumes), were denominated F0.3, F0.5, F0.8, F1, F1.5, and F2. The results that F1 contained a high yield in relation to other fractionated fucans. Chemical and structure analysis of F1 was performed by nuclear magnetic resonance (NMR) and infrared (IR) spectroscopies. The in vitro antioxidant activities of the fraction F1 were also observed. Thus, 2 mg/mL of F1 inhibited the phosphomolybdate in the total antioxidant activity assay. The EC(50) values were 0.3 mg/mL and 0.12 mg/mL for superoxide and hydroxyl radicals, respectively. Fucan F1 (25, 50, and 75 mg/kg by body weight), diclofenac sodium (10 mg/kg), and L-NAME (25 mg/kg) were administered intraperitoneally (i.p.) in rats, according to body weight of different groups of animals (n=6). After 6 h, analyses of cell influx and nitrite levels were conducted. Then after 96 h, analysis of edema and concentration of serum TNF-α was carried out along with histopathological analysis. F1 at 25, 50, and 75 mg/kg i.p. by body weight reduced cell influx in 52.1-96.7% and nitric oxide level in 27.2-39% compared with the control group. The reduction of edema and serum TNF-α was observed at 50 mg/kg i.p. (p<0.001). These results suggest that this heterofucan from the brown algae L. variegata has potential anti-inflammatory activity in acute zymosan-induced arthritis in rats and that antioxidant activity promotes modulation in the cellular redox state.

The role of tumor necrosis factor-α and TNF-α receptors in cerebral arteries following cerebral ischemia in rat

Background

Tumour necrosis factor-α (TNF-α) is a pleiotropic pro-inflammatory cytokine, which is rapidly upregulated in the brain after injury. TNF-α acts by binding to its receptors, TNF-R1 (p55) and TNF-R2 (p75), on the cell surface. The aim of this study was first to investigate if there is altered expression of TNF-α and TNF-α receptors in cerebral artery walls following global or focal ischemia, and after organ culture. Secondly, we asked if the expression was regulated via activation of the MEK-ERK1/2 pathway.

Methods

The hypothesis was tested in vivo after subarachnoid hemorrhage (SAH) and middle cerebral artery occlusion (MCAO), and in vitro by organ culture of isolated cerebral arteries. The localization and amount of TNF-α, TNF-α receptor 1 and 2 proteins were analysed by immunohistochemistry and western blot after 24 and 48 h of organ culture and at 48 h following SAH or MCAO. In addition, cerebral arteries were incubated for 24 or 48 h in the absence or presence of a B-Raf inhibitor (SB386023-b), a MEK- inhibitor (U0126) or an NF-κB inhibitor (IMD-0354), and protein expression evaluated.

Results

Immunohistochemistry revealed enhanced expression of TNF-α, TNF-R1 and TNF-R2 in the walls of cerebral arteries at 48 h after MCAO and SAH compared with control. Co-localization studies showed that TNF-α, TNF-R1 and TNF-R2 were primarily localized to the cell membrane and the cytoplasm of the smooth muscle cells (SMC). There was, in addition, some expression of TNF-R2 in the endothelial cells. Immunohistochemistry and western blot analysis showed that these proteins were upregulated after 24 and 48 h in culture, and this upregulation reached an apparent maximum at 48 h of organ culture. Treatment with U0126 significantly reduced the enhanced SMC expression of TNF-α, TNF-R1 and TNF-R2 immunoreactivities after 24 and 48 h of organ culture. The Raf and NF-κB inhibitors significantly reduced organ culture induced TNF-α expression while they had minor effects on the TNF-α receptors.

Conclusion

The present study shows that cerebral ischemia and organ culture induce expression of TNF-α and its receptors in the walls of cerebral arteries and that upregulation is transcriptionally regulated via the MEK/ERK pathway.

Binding force measurement of NF-κB-ODNs interaction: an AFM based decoy and drug testing tool

Interaction between transcription factors and DNA are essential for regulating gene transcription. The Nuclear factor-κB (NF-κB) is a ubiquitous transcription factor involved in cell signalling and its failure is a principal cause of several autoimmune and auto-inflammatory disorders. In this paper we have developed an atomic force microscopy (AFM) method to quantitatively characterise the interaction force between NF-κB and DNA or LNA (locked nucleic acid) double strand molecules containing the NF responsive elements (RE). This process allows the simple testing and selection of LNA based decoy molecules to be used in NF-κB modulation decoy strategies. Furthermore the proposed methodology is also suitable for testing drug efficacy on the modulation of NF-κB binding to its nucleic acid target sequence. A biological AFM based sensor is therefore considered appropriate for characterising transcription factors and selecting molecules to modulate their activity.

Kalopanaxsaponin A ameliorates experimental colitis in mice by inhibiting IRAK-1 activation in the NF-κB and MAPK pathways

BACKGROUND AND PURPOSE

Kalopanaxsaponin A, a triterpenoid saponin isolated from Kalopanax pictus (family Araliaceae), potently inhibited nuclear factor-kappa B (NF-κB) activation in lipopolysaccharide (LPS)-stimulated peritoneal macrophages during a screening programme for anti-colitis agents from natural products. Its anti-inflammatory mechanism remains unknown. Therefore, we investigated its anti-inflammatory effects in lipopolysaccharide (LPS)- or peptidoglycan-stimulated murine peritoneal macrophages and trinitrobenzene sulphonic acid (TNBS)-induced colitic mice.

EXPERIMENTAL APPROACH

Peritoneal macrophages from male ICR mice were stimulated with LPS or peptidoglycan in vitro and treated with kalopanaxsaponin A. Colitis was induced in vivo by intrarectal administration of TNBS in male ICR mice. Mice were treated daily with kalopanaxsaponin A, sulphasalazine or phosphate-buffered saline. Inflammatory markers, cytokines, enzymes and transcription factors were measured by ELISA, immunoblot, flow cytometry and immunofluorescent confocal microscopy.

KEY RESULTS

Kalopanaxsaponin A potently inhibited the expression of the pro-inflammatory cytokines, interleukin (IL)-1β, tumour necrosis factor (TNF)-α and IL-6, induced by LPS, but not that induced by TNF-α, in peritoneal macrophages. However, it potently increased the expression of the anti-inflammatory cytokine IL-10. Kalopanaxsaponin A inhibited activation of the IL-1 receptor-associated kinase (IRAK)-1, inhibitor of κB kinase-β, NF-κB and mitogen-activated protein kinases (extracellular signal-regulated kinase, c-Jun NH(2) -terminal kinase, p-38), but LPS/Toll-like receptor-4 interaction and IRAK-4 activation were not affected. Oral administration of kalopanaxsaponin A (10 and 20 mg·kg(-1) ) improved the clinical parameters and histology in vivo. Kalopanaxsaponin A inhibited NF-κB and mitogen-activated protein kinase activation induced by TNBS by suppressing IRAK-1 activation.

CONCLUSIONS AND IMPLICATIONS

Kalopanaxsaponin A may improve inflammatory diseases, such as colitis, by inhibiting IRAK-1 activation.

The human NADPH oxidase: primary and secondary defects impairing the respiratory burst function and the microbicidal ability of phagocytes

Phagocytes, such as granulocytes and monocytes/macrophages, contain a membrane-associated NADPH oxidase that produces superoxide leading to other reactive oxygen species with microbicidal, tumoricidal and inflammatory activities. Primary defects in oxidase activity in chronic granulomatous disease (CGD) lead to severe, life-threatening infections that demonstrate the importance of the oxygen-dependent microbicidal system in host defence. Other immunological disturbances may secondarily affect the NADPH oxidase system, impair the microbicidal activity of phagocytes and predispose the host to recurrent infections. This article reviews the primary defects of the human NADPH oxidase leading to classical CGD, and more recently discovered immunological defects secondarily affecting phagocyte respiratory burst function and resulting in primary immunodeficiencies with varied phenotypes, including susceptibilities to pyogenic or mycobacterial infections.

Transcriptional control of maladaptive and protective responses in alcoholics: a role of the NF-κB system

Alcohol dependence and associated cognitive impairment appear to result from maladaptive neuroplasticity in response to chronic alcohol consumption, neuroinflammation and neurodegeneration. The inherent stability of behavioral alterations associated with the addicted state suggests that transcriptional and epigenetic mechanisms are operative. NF-κB transcription factors are regulators of synaptic plasticity and inflammation, and responsive to a variety of stimuli including alcohol. These factors are abundant in the brain where they have diverse functions that depend on the composition of the NF-κB complex and cellular context. In neuron cell bodies, NF-κB is constitutively active, and involved in neuronal injury and neuroprotection. However, at the synapse, NF-κB is present in a latent form and upon activation is transported to the cell nucleus. In glia, NF-κB is inducible and regulates inflammatory processes that exacerbate alcohol-induced neurodegeneration. Animal studies demonstrate that acute alcohol exposure transiently activates NF-κB, which induces neuroinflammatory responses and neurodegeneration. Postmortem studies of brains of human alcoholics suggest that repeated cycles of alcohol consumption and withdrawal cause adaptive changes in the NF-κB system that may permit the system to better tolerate excessive stimulation. This type of tolerance, ensuring a low degree of responsiveness to applied stimuli, apparently differs from that in the immune system, and may represent a compensatory response that protects brain cells against alcohol neurotoxicity. This view is supported by findings showing preferential downregulation of pro-apoptotic gene expression in the affected brain areas in human alcoholics. Although further verification is needed, we speculate that NF-κB-driven neuroinflammation and disruption to neuroplasticity play a significant role in regulating alcohol dependence and cognitive impairment.

Suppression of mast-cell-mediated allergic inflammation by Lindera obtusiloba

Allergic disease is a consequence of exposure to normally innocuous substances that elicit the activation of mast cells. Mast-cell-mediated allergic response is involved in many diseases such as anaphylaxis, allergic rhinitis, asthma and atopic dermatitis. The discovery of drugs for the treatment of allergic disease is an important subject in human health. In this study, we investigated the effect of Lindera obtusiloba water extract (LOWE) on the mast-cell-mediated allergic inflammation and possible mechanism of action using in vitro and in vivo models. LOWE reduced histamine release from various types of mast cells activated by immunoglobulin E (IgE) or phorbol 12-myristate 13-acetate and calcium ionophore A23187 (PMACI). The inhibitory effect of LOWE on histamine release was mediated by calcium signal. LOWE decreased the PMACI-stimulated gene expression of proinflammatory cytokines such as tumor necrosis factor-α and interleukin-6 in human mast cells. The inhibitory effect of LOWE on the proinflammatory cytokines was nuclear factor (NF)-κB dependent. In addition, LOWE suppressed compound 48/80-induced systemic allergic reaction and serum histamine release in mice and IgE-mediated local allergic reactions. Our results indicate that LOWE inhibits mast-cell-derived allergic inflammation and involvement of calcium, histamine, proinflammatory cytokines and NF-κB in these effects.

Mechanisms involved in regulation of osteoclastic differentiation by mechanical stress-loaded osteoblasts

Mechanical stress is known to be important for regulation of bone turnover, though the detailed mechanisms are not fully understood. In the present study, we examined the effect of mechanical stress on osteoblasts using a novel compression model. Mouse osteoblastic MC3T3-E1 cells were embedded in three-dimensional (3D) gels and cultured with continuous compressive force (0-10.0 g/cm(2)) for 48 h, and the conditioned medium were collected. RAW264.7 cells were then incubated with the conditioned medium for various times in the presence of receptor activator of nuclear factor-κB ligand (RANKL). Conditioned medium was found to inhibit the differentiation of RAW264.7 cells into osteoclasts induced by RANKL via down-regulation of the expression of tumor necrosis factor receptor-associated factor 6 (TRAF6), phosphorylation of IκBα, and nuclear translocation of p50 and p65. Interestingly, the conditioned medium also had a high level of binding activity to RANKL and blocked the binding of RANK to RANKL. Furthermore, the binding activity of conditioned medium to RANKL was reduced when the 3D gel was supplemented with KN-93, an inhibitor of non-canonical Wnt/Ca(2+) pathway. In addition, expression level of osteoprotegerin (OPG) mRNA was increased in time- and force-dependent manners, and remarkably suppressed by KN-93. These results indicate that osteoblastic cells subjected to mechanical stress produce OPG, which binds to RANKL. Furthermore, this binding activity strongly inhibited osteoclastogenesis through suppression of TRAF6 and the nuclear factor-kappa B (NF-κB) signaling pathway, suggesting that enhancement of OPG expression induced by mechanical stress is dependent on non-canonical Wnt/Ca(2+) pathway.

1,2,3,6-tetra-O-galloyl-beta-D-allopyranose gallotannin isolated, from Euphorbia jolkini, attenuates LPS-induced nitric oxide production in macrophages

Nitric oxide (NO) is a pleiotropic regulator, critical to numerous biological processes, including vasodilatation and macrophage-mediated immunity. Macrophages express inducible NO synthase (iNOS) and produce NO after lipopolysaccharide (LPS) stimulation. Gallotannins are water-soluble polyphenols with wide-ranging biological activities. Various chemical structures of gallotannins occurring in medicinal and food plants that are used worldwide showed several remarkable biological and pharmacological activities. In the present study, we examined the inhibitory effects of gallotannin 1,2,3,6-tetra-O-galloyl-beta-D-allopyranose (GT24) isolated from Euphorbia jolkini on the LPS-induced NO production and underlying mechanisms of action. GT24 dose-dependently decreased LPS-induced NO production and iNOS expression in J774A.1 macrophages. In addition, GT24 inhibited LPS-induced activation of nuclear factor (NF)-kappaB as indicated by inhibition of degradation of I-kappaBalpha, nuclear translocation of NF-kappaB, and NF-kappaB dependent gene reporter assay. Our results suggest that GT24 possesses an inhibitory effect on the LPS-induced inflammatory reaction.

Lancemaside A inhibits lipopolysaccharide-induced inflammation by targeting LPS/TLR4 complex

In our previous study, lancemaside A isolated from Codonopsis lanceolata (family Campanulaceae) ameliorated colitis in mice. In this study, the anti-inflammatory effects of lancemaside A was investigated in lipopolysaccharide (LPS)-stimulated mice and their peritoneal macrophage cells. Lancemaside A suppressed the production of pro-inflammatory cytokines, TNF-α and IL-1β, in vitro and in vivo. Lancemaside A also down-regulated inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), as well as the inflammatory mediators, nitric oxide (NO), and PGE(2). Lancemaside A also inhibited the expression of IL-1 receptor-associated kinase-4 (IRAK-4), the phosphorylation of IKK-β and IκB-α, the nuclear translocation of NF-κB and the activation of mitogen-activated protein kinases in LPS-stimulated peritoneal macrophages. Furthermore, lancemaisde A inhibited the interaction between LPS and TLR4, as well as IRAK-4 expression in peritoneal macrophages. Based on these findings, lancemaside A expressed anti-inflammatory effects by regulating both the binding of LPS to TLR4 on macrophages.

Chronic inflammation and hepatocellular carcinoma

Hepatocellular carcinoma (HCC) invariably develops within a setting of chronic inflammation caused by either hepatotropic viruses, toxins, metabolic liver disease or autoimmunity. Mechanisms that link these two processes are not completely understood, but transcription factors of the NF-κB family and signal transducer and activator of transcription 3 (STAT3), cytokines such as IL-6 and IL-1α and ligands of the epidermal growth factor receptor (EGFR) family are clearly pivotal players. HCC may have its origins in either hepatocytes or hepatic progenitor cells (HPCs), and HCCs, like other solid tumours appear to be sustained by a minority population of cancer stem cells.

Cactin targets the MHC class III protein IkappaB-like (IkappaBL) and inhibits NF-kappaB and interferon-regulatory factor signaling pathways

Toll-like receptors (TLRs) act as primary sensors of the immune system by recognizing specific microbial motifs and inducing proinflammatory genes that facilitate innate and adaptive immunity. TLRs regulate gene expression by activating transcription factors, such as NF-κB and interferon-regulatory factors. Dysregulation of these pathways can lead to inflammatory diseases, and thus they are subject to stringent control by negative regulators of innate immune signaling. Cactin (Cactus interactor) was initially discovered as a novel interactor of Drosophila Cactus, a regulator of Drosophila Toll signaling. We now describe the first functional characterization of the human ortholog of Cactin (hCactin) and show that it acts as a negative regulator of TLRs. Overexpression of hCactin suppresses TLR-induced activation of NF-κB and interferon-regulatory factor transcription factors and induction of TLR-responsive genes, whereas knockdown of endogenous hCactin augments TLR induction of these responses. hCactin also interacts with IκB-like protein and targets other proteins that are encoded by genes in the MHC Class III region of chromosome 6. We demonstrate that hCactin localizes to the nucleus, and this nuclear localization is critical for manifesting its inhibitory effects on TLR signaling. This study thus defines hCactin as a novel negative regulator of TLR signaling and reveals its capacity to target MHC Class III genes at the molecular and functional level.

Soyasaponin I attenuates TNBS-Induced colitis in mice by inhibiting NF-κB pathway

Soybean, which contains soyasaponins and isoflavones as representative constituents, exhibits anti-inflammatory and antioxidant effects. To understand the anti-inflammatory effects of soyasaponins, we isolated soyasaponin I, a major constituent of soybean, and investigated the inhibitory effects on inflammatory markers in LPS-stimulated mouse peritoneal macrophages and 3,4,5-trinitrobenzenosulfonic acid (TNBS)-induced colitic mice. Soyasaponin I, which exhibited lipid peroxidation-inhibitory effects in vitro, inhibited the production of proinflammatory cytokines (TNF-α and IL-1β), inflammatory mediators (NO and PGE2), and inflammatory enzymes (COX-2 and iNOS) in LPS-stimulated peritoneal macrophages. Soyasaponin I also suppressed the phosphorylation of IκB-α and the nuclear translocation of NF-κB. However, these soyasaponins barely inhibited mitogen-activated protein kinases. Oral administration of soyasaponin I (10 and 20 mg/kg) to TNBS-treated colitic mice significantly reduced inflammatory markers, colon length, myeloperoxidase, lipid peroxide (malondialdehyde and 4-hydroxy-2-nonenal), proinflammatory cytokines and NF-κB activation in the colon, as well as increased glutathione content, superoxide dismutase, and catalase activity. Based on these findings, soyasaponin I may attenuate colitis by inhibiting the NF-κB pathway.

An extract of Phellinus linteus grown on germinated brown rice inhibits inflammation markers in RAW264.7 macrophages by suppressing inflammatory cytokines, chemokines, and mediators and up-regulating antioxidant activity

The immunomodulatory activity of an organic extract of Phellinus linteus grown on slightly germinated brown rice (PBR) was previously demonstrated. Here, we investigated the possible anti-inflammatory activity of the PBR extract by analyzing its effect on the expression of macrophage-derived cytokines, chemokines, and mediator genes that participate in immune and inflammatory responses and diseases. The extract profoundly inhibited the induction of cytokines and chemokines, including tumor necrosis factor-α, chemokine (C-X-C motif) ligand-10, granulocyte-macrophage colony-stimulating factor, and interleukin-6, in lipopolysaccharide (LPS)-stimulated RAW264.7 mouse macrophage cells. It also greatly inhibited LPS-stimulated production of nitric oxide (NO) and prostaglandin E(2) in RAW264.7 cells by suppressing the expression of inducible NO synthase and cyclooxygenase-2. PBR extract inhibited NO production with a twofold lower half-maximal inhibitory concentration value than P. linteus extract. To elucidate the underlying mechanism of action, we examined the effect of the PBR extract on the LPS-induced phosphorylation of mitogen-activated protein kinases (MAPKs) in RAW264.7 cells. PBR extract greatly inhibited extracellular signal-regulated kinase and c-Jun N-terminal kinase phosphorylation and slightly inhibited p38 MAPK phosphorylation. It also significantly increased intracellular glutathione peroxidase activity and heme oxygenase-1 protein expression. Thus, the PBR extract has anti-inflammatory activity in LPS-stimulated RAW264.7 cells by virtue of its ability to suppress the production of inflammatory cytokines and chemokines via inhibition of MAPK activation and up-regulation of antioxidant activities.

A-kinase-interacting protein 1 (AKIP1) acts as a molecular determinant of PKA in NF-kappaB signaling

The cAMP-dependent protein kinase (PKA) signaling pathway plays a crucial role in the pathogenesis of many NF-kappaB-related diseases. However, there have been controversial reports with regard to the PKA actions in the regulation of NF-kappaB activity. In this study, we have demonstrated the effect of PKA on NF-kappaB activity in view of AKIP1 action; and in 293 and HeLa cells, where the endogenous AKIP1 expression is minimal, PKA-activating agents inhibited the NF-kappaB-dependent reporter gene expression, blocked the interaction of PKAc and p65 subunit of NF-kappaB, and attenuated PKA-dependent phosphorylation of p65 on Ser-276. This inhibitory function of PKAc in NF-kappaB signaling was reversed by overexpression of AKIP1 in 293 cells. In the breast cancer cell line, MDA-MB231 cells and MCF7 cells, where the endogenous AKIP1 is abundant, the PKA signal was found to be synergized with NF-kappaB activation; PKA-activating agents enhanced NF-kappaB-dependent transcriptional activity and the interaction between p65 and PKAc and augmented the phosphorylation of p65 on Ser-276. After RNAi knockdown of AKIP1 in these breast cancer cells, we observed that PKA-activating agents antagonized NF-kappaB-dependent activation. Meanwhile, PKA inhibitor suppressed NF-kappaB-induced breast cancer cell proliferation and multiple NF-kappaB-dependent anti-apoptotic gene expression. It is likely that expression of AKIP1 determines the relationship between these two signal transduction pathways. These findings explained controversial results from various independent groups regarding the action of PKA signaling on the NF-kappaB activation cascade and suggested a possible therapeutic potential of PKA inhibitor in developing anti-cancer strategies.

Computational modeling with forward and reverse engineering links signaling network and genomic regulatory responses: NF-kappaB signaling-induced gene expression responses in inflammation

Background

Signal transduction is the major mechanism through which cells transmit external stimuli to evoke intracellular biochemical responses. Diverse cellular stimuli create a wide variety of transcription factor activities through signal transduction pathways, resulting in different gene expression patterns. Understanding the relationship between external stimuli and the corresponding cellular responses, as well as the subsequent effects on downstream genes, is a major challenge in systems biology. Thus, a systematic approach is needed to integrate experimental data and theoretical hypotheses to identify the physiological consequences of environmental stimuli.

Results

We proposed a systematic approach that combines forward and reverse engineering to link the signal transduction cascade with the gene responses. To demonstrate the feasibility of our strategy, we focused on linking the NF-κB signaling pathway with the inflammatory gene regulatory responses because NF-κB has long been recognized to play a crucial role in inflammation. We first utilized forward engineering (Hybrid Functional Petri Nets) to construct the NF-κB signaling pathway and reverse engineering (Network Components Analysis) to build a gene regulatory network (GRN). Then, we demonstrated that the corresponding IKK profiles can be identified in the GRN and are consistent with the experimental validation of the IKK kinase assay. We found that the time-lapse gene expression of several cytokines and chemokines (TNF-α, IL-1, IL-6, CXCL1, CXCL2 and CCL3) is concordant with the NF-κB activity profile, and these genes have stronger influence strength within the GRN. Such regulatory effects have highlighted the crucial roles of NF-κB signaling in the acute inflammatory response and enhance our understanding of the systemic inflammatory response syndrome.

Conclusion

We successfully identified and distinguished the corresponding signaling profiles among three microarray datasets with different stimuli strengths. In our model, the crucial genes of the NF-κB regulatory network were also identified to reflect the biological consequences of inflammation. With the experimental validation, our strategy is thus an effective solution to decipher cross-talk effects when attempting to integrate new kinetic parameters from other signal transduction pathways. The strategy also provides new insight for systems biology modeling to link any signal transduction pathways with the responses of downstream genes of interest.

Inhibitor of growth-4 promotes IkappaB promoter activation to suppress NF-kappaB signaling and innate immunity

Ing4 is a member of the inhibitor of growth (ING) family of chromatin-modifying proteins. Biochemical experiments indicate that Ing4 is a subunit of the HB01-JADE-hEAF6 histone acetyltransferase complex responsible for most nucleosomal histone H4 acetylation in eukaryotes, and transfection studies suggest that Ing4 may regulate a wide variety of cellular processes, including DNA repair, apoptosis, cell-cycle regulation, metastasis, angiogenesis, and tumor suppression. However, in vivo evidence for a physiological role for Ing4 in cell-growth regulation is lacking. We have generated Ing4-deficient mice to explore the role of Ing4 in development, tumorigenesis, and in NF-kappaB signaling. Ing4-null mice develop normally and are viable. Although mice deficient for Ing4 fail to form spontaneous tumors, they are hypersensitive to LPS treatment and display elevated cytokine responses. Macrophages isolated from Ing4-null mice have increased levels of nuclear p65/RelA protein, resulting in increased RelA binding to NF-kappaB target promoters and up-regulation of cytokine gene expression. However, increased promoter occupancy by RelA in LPS-stimulated, Ing4-null cells does not always correlate with increased NF-kappaB target-gene expression, as RelA activation of a subset of cytokine promoters also requires Ing4 for proper histone H4 acetylation. Furthermore, activation of the IkappaB alpha promoter by RelA is also Ing4-dependent, and LPS-stimulated, Ing4-null cells have reduced levels of IkappaB alpha promoter H4 acetylation and IkappaB gene expression. Thus, Ing4 negatively regulates the cytokine-mediated inflammatory response in mice by facilitating NF-kappaB activation of IkappaB promoters, thereby suppressing nuclear RelA levels and the activation of select NF-kappaB target cytokines.

Inhibition of IkappaB kinase-beta protects dopamine neurons against lipopolysaccharide-induced neurotoxicity

Parkinson's disease (PD) is a progressive neurological disorder characterized by a selective loss of dopamine (DA) neurons in the substantia nigra (SN). Although current therapy can control symptoms of this disorder, there is no effective therapy available to halt its progression. Recently, neuroinflammation has been recognized as an important contributor to the pathogenesis of PD, and nuclear factor-kappaB (NF-kappaB) plays a key role in regulating neuroinflammation. Hence, the modulation of NF-kappaB pathway may have therapeutic potential for PD. Activation of NF-kappaB depends on the phosphorylation of its inhibitor, IkappaB, by the specific IkappaB kinase (IKK) subunit IKK-beta. Compound A (7-[2-(cyclopropylmethoxy)-6-hydroxyphenyl]-5-[(3S)-3-piperidinyl]-1, 4-dihydro-2H-pyrido[2,3-d][1,3]oxazin-2-one hydrochloride), a potent and selective inhibitor of IKK-beta, has recently been reported to provide cardioprotection through specific suppression of NF-kappaB signaling. The present study, for the first time, elucidates neuroprotective effects of compound A. Daily subcutaneous injection of compound A (1 mg/kg) for 7 days inhibited the activation of microglia induced by nigral stereotaxic injection of lipopolysaccharide (LPS) and significantly attenuated LPS-induced loss of DA neurons in the SN. In vitro mechanistic studies revealed that neuroprotective effects of compound A were mediated by 1) suppressing the activity of microglial NADPH oxidase and decreasing the production of reactive oxygen species, and 2) inhibiting NF-kappaB-mediated gene transcription of various proinflammatory mediators in microglia via IKK-beta suppression. These findings indicate that compound A afforded potent neuroprotection against LPS-induced neurodegeneration through selective inhibition of NF-kappaB activation and may be of potential benefit in the treatment of PD.

An inhibitor kappaB homologue from bay scallop Argopecten irradians

IkappaB is an important member of NF-kappaB pathway in the innate immune system. In the present study, the full-length cDNA sequence encoding IkappaB protein (designated AiIkappaB) was isolated from bay scallop Argopecten irradians. The complete sequence of AiIkappaB cDNA containing a 5' untranslated region (UTR) of 237 bp, a 3' UTR of 1023 bp with a poly (A) tail, and an open reading frame (ORF) of 1086 bp encoding a polypeptide of 361 amino acids with the predicted molecular weight of 39.9 kDa and theoretical isoelectric point of 4.7. Six ankyrin repeats which were necessary for specific binding to NF-kappaB and two potential phosphorylation sites responsible for IkappaB degradation were identified in the N-terminus of AiIkappaB. No PEST domain but a phosphorylation site motif (S(357)DSD(360)) was present at the C-terminus of AiIkappaB. Predicted three-dimensional structure of AiIkappaB shared high similarity with mammalian IkappaBalpha. Similarity and phylogenetic analysis revealed that AiIkappaB was clustered into IkappaBs from invertebrate. All these typical characteristics indicated that the AiIkappaB should be classified into IkappaB family proteins. Quantitative real-time RT-PCR was employed to assess the mRNA expression of AiIkappaB in various tissues and its temporal expression in haemocytes of scallops challenged with Listonella anguillarum. The mRNA transcript of AiIkappaB could be detected in all the examined tissues with highest expression level in hepatopancreas. Bacteria infection inhibited the transcription level of AiIkappaB. The results suggested the involvement of AiIkappaB in responses against bacterial infection and further highlighted its functional importance in the immune system of A. irradians.

Characterisation of expression patterns and functional role of Cactin in early zebrafish development

The immune system of teleost zebrafish (Danio rerio) shows high similarity to mammalian counterparts sharing many innate immune components including Toll-Like Receptors (TLRs), cytokines, chemokines and complement molecules. As in mammals, zebrafish also contains the transcription factor NF-kappaB that plays dualist roles in innate immunity and early development. Indeed NF-kappaB members are expressed in different temporal patterns during the early stages of zebrafish embryogenesis indicating that each molecule is involved in specific developmental events. In the present study we employ zebrafish as a model to characterise the expression pattern and role of a novel NF-kappaB regulator, termed Cactin, in early development. Cactin was first characterised in Drosophila as a new member of the Rel pathway that could affect the generation of dorsal-ventral polarity. To explore the potential developmental role of Cactin in zebrafish, we initially investigated its expression pattern and functional role during early embryonic developmental stages. We detect Cactin expression at all stages of early development and knockdown of Cactin by specific morpholino antisense oligonucleotides causes developmental abnormalities manifested by an overall dysmorphic cellular organisation. These results indicate that Cactin has been highly conserved during evolution and plays a key role in early embryonic development.

Structural basis for targeting of human RNA helicase DDX3 by poxvirus protein K7

Poxviruses are DNA viruses that express numerous proteins to subvert the host immune response. Vaccinia virus protein K7 adopts a Bcl-2 fold and displays structural and functional similarities to Toll-like receptor antagonist A52. Both proteins interact with IRAK2 and TRAF6 and suppress TLR-dependent NF-kappaB activation. However, unlike A52, K7 also forms a complex with RNA helicase DDX3 and antagonizes interferon-beta promoter induction. We have narrowed the K7 binding site to an N-terminal peptide motif of DDX3 ahead of its core RNA-helicase domains. The crystal structure of full-length K7 in complex with the DDX3 peptide reveals a thumblike projection of tandem phenalyalanine residues of DDX3 into a deep hydrophobic cleft. Mutagenesis of these phenylalanines abolishes the effects of DDX3 on interferon-beta promoter induction. The structure of K7-DDX3 reveals a novel binding mode by a viral Bcl-2 protein that antagonizes a key pathway in innate immunity.

The anti-inflammatory effects of the tellurium redox modulating compound, AS101, are associated with regulation of NFkappaB signaling pathway and nitric oxide induction in macrophages

BACKGROUND

LPS-activated macrophages produce mediators which are involved in inflammation and tissue injury, and especially those associated with endotoxic shock. The non toxic tellurium compound ammonium tri-chloro(dioxoethylene-O,O'-)tellurate, AS101, has been recently shown to exert profound anti-inflammatory properties in animal models, associated with its Te(IV) redox chemistry. This study explores the anti-inflammatory properties of AS101 with respect to modulation of inflammatory cytokines production and regulation of iNOS transcription and expression in activated macrophages via targeting the NFkB complex.

RESULTS

AS101 decreased production of IL-6 and in parallel down-regulated LPS-induced iNOS expression and NO secretion by macrophages. AS101 reduced IkB phosphorylation and degradation, and reduced NFkB nuclear translocalization, albeit these effects were exerted at different kinetics. Chromatin immunoprecipitation assays showed that AS101 treatment attenuated p50-subunit ability to bind DNA at the NFkB consensus site in the iNOS promotor following LPS induction.

CONCLUSIONS

Besides AS101, the investigation of therapeutic activities of other tellurium(IV) compounds is scarce in the literature, although tellurium is the fourth most abundant trace element in the human body. Since IKK and NFkB may be regulated by thiol modifications, we may thus envisage, inview of our integrated results, that Te(IV) compounds, may have important roles in thiol redox biological activity in the human body and represent a new class of anti-inflammatory compounds.

The effect of intracellular delivery of catalase and antisense oligonucleotides to NF-kappaB using albumin microcapsules in the endotoxic shock model

Microencapsulated (MC) catalase has been shown to inhibit H(2)O(2) and tumor necrosis factor (TNF) in vitro after endotoxin stimulation. It is the purpose of this study to determine whether MC catalase improves pro-inflammatory cytokine inhibition and mortality in an endotoxic shock model in vivo. We also examined whether MC catalase and antisense oligonucleotides (ASO) to nuclear factor kappaB (NF-kappaB) together improved survival by inhibiting pro-inflammatory cytokines using different mechanisms.

METHODS

Albumin microcapsules containing catalase and ASO to NF-kappaB were prepared 2-7 microm in size by using a Büchi spray dryer. Progressively increasing doses of MC catalase, MC ASO to NF-kappaB, and the combination were given to rats before the administration of Escherichia coli endotoxin. Results demonstrated 60% survival in rats given 15 mg/kg MC catalase, 70% survival with 20 mg/kg MC ASO NF-kappaB, and 80% survival with the combination. TNF was inhibited by 53% in the MC catalase group 4 h after endotoxin administration, 43% in the ASO NF-kappaB group, and 78% in the combination group compared to controls. In conclusion, this study demonstrates the effectiveness of MC intracellular delivery of the naturally occurring antioxidant catalase in improving animal survival. The addition of ASO to NF-kappaB improved both cytokine inhibition and animal survival in endotoxic shock.

Combination of linkage mapping and microarray-expression analysis identifies NF-kappaB signaling defect as a cause of autosomal-recessive mental retardation

Autosomal-recessive inheritance accounts for nearly 25% of nonsyndromic mental retardation (MR), but the extreme heterogeneity of such conditions markedly hampers gene identification. Combining autozygosity mapping and RNA expression profiling in a consanguineous Tunisian family of three MR children with mild microcephaly and white-matter abnormalities identified the TRAPPC9 gene, which encodes a NF-kappaB-inducing kinase (NIK) and IkappaB kinase complex beta (IKK-beta) binding protein, as a likely candidate. Sequencing analysis revealed a nonsense variant (c.1708C>T [p.R570X]) within exon 9 of this gene that is responsible for an undetectable level of TRAPPC9 protein in patient skin fibroblasts. Moreover, TNF-alpha stimulation assays showed a defect in IkBalpha degradation, suggesting impaired NF-kappaB signaling in patient cells. This study provides evidence of an NF-kappaB signaling defect in isolated MR.

The role of NF-kappaB in hypoxia-induced gene expression

Hypoxia is a common physiologic and pathophysiologic stimulus that activates the expression of genes through oxygen-sensitive transcription factors including the hypoxia-inducible factor (HIF) and nuclear factor-kappaB (NF-kappaB). Hypoxia-dependent gene expression can have important physiologic or pathophysiologic consequences for an organism, depending upon the cause of the hypoxic insult. Consequently, this pathway represents an attractive therapeutic target in a number of disease states. While the mechanism linking hypoxia to the activation of HIF has been extensively studied, our understanding of how hypoxia activates NF-kappaB is limited. Recent studies have demonstrated that similar oxygen-sensing mechanisms are employed in conferring oxygen sensitivity to both HIF and NF-kappaB-dependent gene expression. Furthermore, there is an extensive degree of cross-talk occurring between NF-kappaB and HIF. Investigations into mechanisms of hypoxic activation of HIF and NF-kappaB and how these signaling pathways interact will uncover new therapeutic modalities in a diverse range of disease states where hypoxia is a feature of the microenvironment including cancer, vascular disease, and chronic inflammation.

TNFalpha activation of PKCdelta, mediated by NFkappaB and ER stress, cross-talks with the insulin signaling cascade

TNFalpha plays key roles in the regulation of inflammation, cell death, and proliferation and its signaling cascade cross-talks with the insulin signaling cascade. PKCdelta, a novel PKC isoform, is known to participate in proximal TNFalpha signaling events. However, it has remained unclear whether PKCdelta plays a role in distal TNFalpha signaling events. Here we demonstrate that PKCdelta is activated by TNFalpha in a delayed fashion that is temporally associated with JNK activation. To investigate the signaling pathways activating PKCdelta and JNK, we used pharmacological and genetic inhibitors of NFkappaB. We found that inhibition of NFkappaB attenuated PKCdelta and JNK activations. Further analysis revealed that ER stress contributes to TNFalpha-stimulated PKCdelta and JNK activations. To investigate the role of PKCdelta in TNFalpha action, we used 29-mer shRNAs to silence PKCdelta expression. A reduction of ~90% in PKCdelta protein levels reduced TNFalpha-stimulated stress kinase activation, including JNK. Further, PKCdelta was necessary for thapsigargin-stimulated JNK activation. Because thapsigargin is a potent inducer of ER stress, we determined whether PKCdelta was necessary for induction of the UPR. Indeed, a reduction in PKCdelta protein levels reduced thapsigargin-stimulated CHOP induction, a hallmark of the UPR, but not BiP/GRP78 induction, suggesting that PKCdelta does not globally regulate the UPR. Next, the role of PKCdelta in TNFalpha mediated cross-talk with the insulin signaling pathway was investigated in cells expressing human IRS-1 and a 29-mer shRNA to silence PKCdelta expression. We found that a reduction in PKCdelta protein levels reversed the TNFalpha-mediated reduction in insulin-stimulated IRS-1 Tyr phosphorylation, Akt activation, and glycogen synthesis. In addition, TNFalpha-stimulated IRS protein Ser/Thr phosphorylation and degradation were blocked. Our results indicate that: 1) NFkappaB and ER stress contribute in part to PKCdelta activation; 2) PKCdelta plays a key role in the propagation of the TNFalpha signal; and 3) PKCdelta contributes to TNFalpha-induced inhibition of insulin signaling events.

Astrocytes in the damaged brain: molecular and cellular insights into their reactive response and healing potential

Long considered merely a trophic and mechanical support to neurons, astrocytes have progressively taken the center stage as their ability to react to acute and chronic neurodegenerative situations became increasingly clear. Reactive astrogliosis starts when trigger molecules produced at the injury site drive astrocytes to leave their quiescent state and become activated. Distinctive morphological and biochemical features characterize this process (cell hypertrophy, upregulation of intermediate filaments, and increased cell proliferation). Moreover, reactive astrocytes migrate towards the injured area to constitute the glial scar, and release factors mediating the tissue inflammatory response and remodeling after lesion. A novel view of astrogliosis derives from the finding that subsets of reactive astrocytes can recapitulate stem cell/progenitor features after damage, fostering the concept of astroglia as a promising target for reparative therapies. But which biochemical/signaling pathways modulate astrogliosis with respect to both the time after injury and the type of damage? Are reactive astrocytes overall beneficial or detrimental for neuroprotection and tissue regeneration? This debate has been animating this research field for several years now, and an integrated view on the results obtained and the possible future perspectives is needed. With this Commentary article we have attempted to answer the above-mentioned questions by reviewing the current knowledge on the molecular mechanisms controlling and sustaining the reaction of astroglia to injury and its stem cell-like properties. Moreover, the cellular/molecular mechanisms supporting the detrimental or beneficial features of astrogliosis have been scrutinized to gain insights on possible pharmacological approaches to enhance astrocyte neuroprotective activities.