NF-kappa B subunit-specific regulation of the interleukin-8 promoter

Lipopolysaccharide responsiveness in vocal fold fibroblasts

Background

Vocal fold fibroblast’s (VFF) strategic location in the lamina propria and their ability to respond to external stimuli by producing inflammatory molecules suggest their possible direct involvement in innate immunity. Toll-like receptors (TLRs) are an essential signaling component to this response, as they allow for recognition of various microorganisms, leading to subsequent induction of pro-inflammatory genes. The objective of this study was to elucidate the role of VFF in the host immune response and subsequent influence on inflammatory cytokine secretion.

Methods

VFF derived from polyp, scar, and normal tissue were treated with 5 μg/ml lipopolysaccharide (LPS). TLR1 through 9, CD14, and MD-2 were measured during stable conditions by polymerase chain reaction (PCR). Expression of TLR4 and IL-1R type-1 genes were quantified after 24 hrs LPS stimulation by reverse transcription-PCR. LPS responsiveness was determined by NF-κB nuclear translocation as measured by subunit p65 expression in nucleus with immunocytochemistry. Downstream effects were confirmed with immunoassay measuring IL-8 concentrations in supernatant after 8 hrs.

Results

All VFFs constitutively expressed TLR1 to 6, TLR9, CD14, and MD-2 mRNA. Polyp VFF exhibited significantly higher TLR4 transcript levels (p < 0.001) in comparison to scar and normal VFF. LPS stimulated scar and polyp VFF exhibited increased levels of p65 in the nucleus (p < 0.01) and secreted greater IL-8 protein (p < 0.0001) compared to normal VFF.

Conclusion

VFF constitutively express genes for the receptors essential to the host immune response. Scar and polyp VFF produced greater LPS responsiveness resulting in over-activated inflammatory patterns. These findings support VFF role in the pathogenesis of inflammatory vocal fold disorders and suggests their presence in the wound bed could lead to chronic inflammation.

Coronavirus-induced ER stress response and its involvement in regulation of coronavirus-host interactions

Coronavirus replication is structurally and functionally associated with the endoplasmic reticulum (ER), a major site of protein synthesis, folding, modification and sorting in the eukaryotic cells. Disturbance of ER homeostasis may occur under various physiological or pathological conditions. In response to the ER stress, signaling pathways of the unfolded protein response (UPR) are activated. UPR is mediated by three ER transmembrane sensors, namely the PKR-like ER protein kinase (PERK), the inositol-requiring protein 1 (IRE1) and the activating transcriptional factor 6 (ATF6). UPR facilitates adaptation to ER stress by reversible translation attenuation, enhancement of ER protein folding capacity and activation of ER-associated degradation (ERAD). In cells under prolonged and irremediable ER stress, UPR can also trigger apoptotic cell death. Accumulating evidence has shown that coronavirus infection causes ER stress and induces UPR in the infected cells. UPR is closely associated with a number of major signaling pathways, including autophagy, apoptosis, the mitogen-activated protein (MAP) kinase pathways, innate immunity and pro-inflammatory response. Therefore, studies on the UPR are pivotal in elucidating the complicated issue of coronavirus-host interaction. In this paper, we present the up-to-date knowledge on coronavirus-induced UPR and discuss its potential involvement in regulation of innate immunity and apoptosis.

The response of porcine monocyte derived macrophages and dendritic cells to Salmonella Typhimurium and lipopolysaccharide

Background

Following infection and initial multiplication in the gut lumen, Salmonella Typhimurium crosses the intestinal epithelial barrier and comes into contact with cells of the host immune system. Mononuclear phagocytes which comprise macrophages and dendritic cells (DC) are of key importance for the outcome of Salmonella infection. Although macrophages and DC may differentiate from a common precursor, their capacities to process and present antigen differ significantly. In this study, we therefore compared the response of porcine macrophages and DC differentiated from peripheral blood monocytes to S. Typhimurium and one of the most potent bacterial pathogen associated molecular patterns, bacterial lipopolysaccharide. To avoid any bias, the expression was determined by protein LC-MS/MS and verified at the level of transcription by quantitative RT-PCR.

Results

Within 4 days of culture, peripheral blood monocytes differentiated into two populations with distinct morphology and expression of MHC II. Mass spectrometry identified 446 proteins in macrophages and 672 in DC. Out of these, 433 proteins were inducible in macrophages either after infection with S. Typhimurium or LPS exposure and 144 proteins were inducible in DC. The expression of the 46 most inducible proteins was verified at the level of transcription and the differential expression was confirmed in 22 of them. Out of these, 16 genes were induced in both cell types, 3 genes (VCAM1, HMOX1 and Serglycin) were significantly induced in macrophages only and OLDLR1 and CDC42 were induced exclusively in DC. Thirteen out of 22 up-regulated genes contained the NF-kappaB binding site in their promoters and could be considered as either part of the NF-kappaB feedback loop (IkappaBalpha and ISG15) or as NF-kappaB targets (IL1beta, IL1alpha, AMCF2, IL8, SOD2, CD14, CD48, OPN, OLDLR1, HMOX1 and VCAM1).

Conclusions

The difference in the response of monocyte derived macrophages and DC was quantitative rather than qualitative. Despite the similarity of the responses, compared to DC, the macrophages responded in a more pro-inflammatory fashion.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-014-0244-1) contains supplementary material, which is available to authorized users.

Neurotensin, a Novel Messenger to Cross-Link Inflammation and Tumor Invasion via Epithelial-Mesenchymal Transition Pathway

Multiple cytokines and growth factors are critical for the prognosis of cancer which has been regarded as a worldwide health problem. Recently, neuropeptides, soluble factors regulating a series of functions in the central nervous system, have also been demonstrated to stimulate the proliferation and migration of tumor cells. Among these signaling peptides, the role of neurotensin (NTS) on malignancy procession has become a hot topic. The effects of NTS on tumor growth and its antiapoptosis role have already been identified. Subsequently, studies demonstrated the impact of NTS on the migration and invasion, but the molecular mechanisms involved are still unclear at present. Recently, some reports indicated that NTS could induce expression and secretion of interleukin-8 (IL-8) to promote local imflammatory response which might participate in epithelial-mesenchymal transition (EMT)-related tumor migration. In present review, we highlight the process of tumor EMT induced by NTS through stimulating IL-8 and the significance of NTS/IL-8 pathway in clinical application prospect.

Epithelial growth factor receptor-activated nuclear factor κB signaling and its role in epithelial growth factor receptor-associated tumors

Dysregulated epithelial growth factor receptor (EGFR) signaling is directly associated with a number of cancers, such as brain, lung, and breast cancer. The downstream signaling pathways activated by EGFR have been extensively studied, such as PI3K/AKT pathway, MAPK (mitogen-activated protein kinase) pathway, and STAT (signal transducer and activator of transcription) pathway. There are growing numbers of evidence suggesting that EGFR activates nuclear factor κB (NF-κB), which is a key transcription factor controlling a variety of cellular functions. However, relatively less is known about the signal transduction mechanism that links EGFR to NF-κB activation. Here, we discuss recent progress in EGFR-induced NF-κB pathways, including the identification of CARMA3-Bcl10-MALT1 complex and protein kinase C[Latin Small Letter Open E] as 2 essential signaling components linking EGFR to the activation of IκBα kinase. In addition, we discuss the multifunctional roles of NF-κB in EGFR-associated tumors, including proliferation, tumor invasiveness, metabolism, tumor-promoting microenvironment, and EGFR tyrosine kinase inhibitor resistance.

NF-κB repressing factor downregulates basal expression and mycobacterium tuberculosis induced IP-10 and IL-8 synthesis via interference with NF-κB in monocytes

Background

Our previous study showed NF-κB repressing factor (NKRF) downregulates IP-10 and IL-8 synthesis in the peripheral blood mononuclear cells and alveolar macrophages of TB patients with high bacterial loads. However, the mechanism underlying the repressive effect of NKRF is not fully understood.

Results

The levels of IP-10, IL-8 and NKRF were significantly up-regulated in THP-1 cells treated with heated mycobacterium tuberculosis (H. TB). NKRF inhibited NF-κB-mediated IP-10 and IL-8 synthesis and release induced by H. TB. The repressive effect of NKRF is mediated via interference with NF-κB (p65) binding and RNA polymerase II recruitment to promoter sites of IP-10 and IL-8.

Conclusions

We have elucidated that direct contact with MTb induces IP-10, IL-8 and a concomitant increase in NKRF in THP-1 cells. The up-regulated NKRF serves as an endogenous repressor for IP-10 and IL-8 synthesis to hinder host from robust response to MTb infection.

Nuclear factor κB-dependent regulation of angiogenesis, and metastasis in an in vivo model of thyroid cancer is associated with secreted interleukin-8

CONTEXT

Development of novel strategies in the treatment of advanced thyroid cancer are needed. Our laboratory has previously identified a role for nuclear factor κB (NF-κB) signaling in human thyroid cancer cell growth, survival, and invasion.

OBJECTIVE

Our goal was to establish the role of NF-κB signaling on thyroid cancer growth and metastases in vivo and to begin to dissect mechanisms regulating this effect.

SETTING AND DESIGN

We examined tumor formation of five thyroid cancer cell lines in an in vivo model of thyroid cancer and observed tumor establishment in two of the cell lines (8505C and BCPAP).

RESULTS

Inhibition of NF-κB signaling by overexpression of a dominant-negative IκBα (mIκBα) significantly inhibited thyroid tumor growth in tumors derived from both cell lines. Further studies in an experimental metastasis model demonstrated that NF-κB inhibition impaired growth of tumor metastasis and prolonged mouse survival. Proliferation (mitotic index) was decreased in 8505C tumors, but not in BCPAP tumors, while in vitro angiogenesis and in vivo tumor vascularity were significantly inhibited by mIkBα only in the BCPAP cells. Cytokine antibody array analysis demonstrated that IL-8 secretion was blocked by mIκBα expression. Interestingly, basal NF-κB activity and IL-8 levels were significantly higher in the two tumorigenic cell lines compared with the nontumorigenic lines. Furthermore, IL-8 transcript levels were elevated in high-risk human tumors, suggesting that NF-κB and IL-8 are associated with more aggressive tumor behavior.

CONCLUSIONS

These studies suggest that NF-κB signaling is a key regulator of angiogenesis and growth of primary and metastatic thyroid cancer, and that IL-8 may be an important downstream mediator of NF-κB signaling in advanced thyroid cancer growth and progression.

Coronavirus infection, ER stress, apoptosis and innate immunity

The replication of coronavirus, a family of important animal and human pathogens, is closely associated with the cellular membrane compartments, especially the endoplasmic reticulum (ER). Coronavirus infection of cultured cells was previously shown to cause ER stress and induce the unfolded protein response (UPR), a process that aims to restore the ER homeostasis by global translation shutdown and increasing the ER folding capacity. However, under prolonged ER stress, UPR can also induce apoptotic cell death. Accumulating evidence from recent studies has shown that induction of ER stress and UPR may constitute a major aspect of coronavirus–host interaction. Activation of the three branches of UPR modulates a wide variety of signaling pathways, such as mitogen-activated protein (MAP) kinase activation, autophagy, apoptosis, and innate immune response. ER stress and UPR activation may therefore contribute significantly to the viral replication and pathogenesis during coronavirus infection. In this review, we summarize the current knowledge on coronavirus-induced ER stress and UPR activation, with emphasis on their cross-talking to apoptotic signaling.

Drug-induced nephrotoxicity: clinical impact and preclinical in vitro models

The kidney is a major target for drug-induced toxicity. Drug-induced nephrotoxicity remains a major problem in the clinical setting, where the use of nephrotoxic drugs is often unavoidable. This leads frequently to acute kidney injury, and current problems are discussed. One strategy to avoid such problems would be the development of drugs with decreased nephrotoxic potential. However, the prediction of nephrotoxicity during preclinical drug development is difficult and nephrotoxicity is typically detected only late. Also, the nephrotoxic potential of newly approved drugs is often underestimated. Regulatory approved or validated in vitro models for the prediction of nephrotoxicity are currently not available. Here, we will review current approaches on the development of such models. This includes a discussion of three-dimensional and microfluidic models and recently developed stem cell based approaches. Most in vitro models have been tested with a limited number of compounds and are of unclear predictivity. However, some studies have tested larger numbers of compounds and the predictivity of the respective in vitro model had been determined. The results showed that high predictivity can be obtained by using primary or stem cell derived human renal cells in combination with appropriate end points.

Regulation of Mcl-1 by constitutive activation of NF-κB contributes to cell viability in human esophageal squamous cell carcinoma cells

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is one of the most lethal malignancies with a 5-year survival rate less than 15%. Understanding of the molecular mechanisms involved in the pathogenesis of ESCC becomes critical to develop more effective treatments.

METHODS

Mcl-1 expression was measured by reverse transcription (RT)-PCR and Western blotting. Human Mcl-1 promoter activity was evaluated by reporter gene assay. The interactions between DNA and transcription factors were confirmed by electrophoretic mobility shift assay (EMSA) in vitro and by chromatin immunoprecipitation (ChIP) assay in cells.

RESULTS

Four human ESCC cell lines, TE-1, Eca109, KYSE150 and KYSE510, are revealed increased levels of Mcl-1 mRNA and protein compare with HaCaT, an immortal non-tumorigenic cell line. Results of reporter gene assays demonstrate that human Mcl-1 promoter activity is decreased by mutation of kappaB binding site, specific NF-kappaB inhibitor Bay11-7082 or dominant inhibitory molecule DNMIkappaBalpha in TE-1 and KYSE150 cell lines. Mcl-1 protein level is also attenuated by Bay11-7082 treatment or co-transfection of DNMIkappaBalpha in TE-1 and KYSE150 cells. EMSA results indicate that NF-kappaB subunits p50 and p65 bind to human Mcl-1-kappaB probe in vitro. ChIP assay further confirm p50 and p65 directly bind to human Mcl-1 promoter in intact cells, by which regulates Mcl-1 expression and contributes to the viability of TE-1 cells.

CONCLUSIONS

Our data provided evidence that one of the mechanisms of Mcl-1 expression in human ESCC is regulated by the activation of NF-kappaB signaling. The newly identified mechanism might provide a scientific basis for developing effective approaches to treatment human ESCC.

Fold change of nuclear NF-κB determines TNF-induced transcription in single cells

In response to tumor necrosis factor (TNF), NF-κB enters the nucleus and promotes inflammatory and stress-responsive gene transcription. Because NF-κB deregulation is associated with disease, one might expect strict control of NF-κB localization. However, nuclear NF-κB levels exhibit considerable cell-to-cell variability, even in unstimulated cells. To resolve this paradox and determine how transcription-inducing signals are encoded, we quantified single-cell NF-κB translocation dynamics and transcription in the same cells. We show that TNF-induced transcription correlates best with fold change in nuclear NF-κB, not absolute nuclear NF-κB abundance. Using computational modeling, we find that an incoherent feedforward loop, from competition for binding to κB motifs, could provide memory of the preligand state necessary for fold-change detection. Experimentally, we observed three gene-specific transcriptional patterns that our model recapitulates by modulating competition strength alone. Fold-change detection buffers against stochastic variation in signaling molecules and explains how cells tolerate variability in NF-κB abundance and localization.

α-catenin acts as a tumour suppressor in E-cadherin-negative basal-like breast cancer by inhibiting NF-κB signalling

Basal-like breast cancer is a highly aggressive tumour subtype associated with poor prognosis. Aberrant activation of NF-κB signalling is frequently found in triple-negative basal-like breast cancer cells, but the cause of this activation has remained elusive.Here we report that α-catenin functions as a tumour suppressor in E-cadherin-negative basal-like breast cancer cells by inhibiting NF-κB signalling. Mechanistically, α-catenin interacts with the IκBα protein, and stabilizes IκBα by inhibiting its ubiquitylation and its association with the proteasome. This stabilization in turn prevents nuclear localization of RelA and p50, leading to decreased expression of TNF-α, IL-8 and RelB. In human breast cancer, CTNNA1 expression is specifically downregulated in the basal-like subtype, correlates with clinical outcome and inversely correlates with TNF and RELB expression. Taken together, these results uncover a previously undescribed mechanism by which the NF-κB pathway is activated in E-cadherin-negative basal-like breast cancer.

Quantitative analysis of bortezomib-induced IL-8 gene expression in ovarian cancer cells

Interleukin-8 (IL-8), originally discovered as the neutrophil chemoattractant and inducer of leukocyte-mediated inflammation, contributes to cancer progression through its induction of tumor cell proliferation, survival, and migration. IL-8 expression is increased in many types of advanced cancers, including ovarian cancer, and correlates with poor prognosis. Bortezomib (BZ) is the first FDA-approved proteasome inhibitor that has shown remarkable antitumor activity in multiple myeloma and other hematological malignancies. In solid tumors, including ovarian carcinoma, BZ has been less effective as a single agent; however, the mechanisms remain unknown. We have recently shown that in ovarian cancer cells, BZ greatly increases IL-8 expression, while expression of other NFκB-regulated cytokines, IL-6 and TNF, is unchanged. In this chapter, we describe a protocol that uses real-time qRT-PCR to quantitatively analyze mRNA levels of IL-8 and IL-6 in BZ-treated ovarian cancer cells. The protocol can be easily modified and used for analysis of other cytokines in different cell types.

Regulation of c-Fos gene expression by NF-κB: a p65 homodimer binding site in mouse embryonic fibroblasts but not human HEK293 cells

The immediate early gene c-Fos is reported to be regulated by Elk-1 and cAMP response element-binding protein (CREB), but whether nuclear factor (NF)-κB is also required for controlling c-Fos expression is unclear. In this study, we determined how NF-κB’s coordination with Elk/serum response factor (SRF) regulates c-fos transcription. We report that PMA strongly induced c-Fos expression, but tumor necrosis factor (TNF)-α did not. In mouse embryonic fibroblasts, the PMA induction of c-Fos was suppressed by a deficiency in IKKα, IKKβ, IKKγ, or p65. By contrast, in human embryonic kidney 293 cells, PMA induced c-Fos independently of p65. In accordance with these results, we identified an NF-κB binding site in the mouse but not human c-fos promoter. Under PMA stimulation, IKKα/β mediated p65 phosphorylation and the binding of the p65 homodimer to the NF-κB site in the mouse c-fos promoter. Furthermore, our studies demonstrated independent but coordinated functions of the IKKα/β-p65 and extracellular signal-regulated kinase (ERK)-Elk-1 pathways in the PMA induction of c-Fos. Collectively, these results reveal the distinct requirement of NF-κB for mouse and human c-fos regulation. Binding of the p65 homodimer to the κB site was indispensable for mouse c-fos expression, whereas the κB binding site was not present in the human c-fos promoter. Because of an inability to evoke sufficient ERK activation and Elk-1 phosphorylation, TNF-α induces c-Fos more weakly than PMA does in both mouse and human cells.

Modulation of NF-κB and Nrf2 control of inflammatory responses in FHs 74 Int cell line is tocopherol isoform-specific

The present study investigates the relative ability of α-, γ-, and δ-tocopherol (Toc) to modulate cell signaling events that are associated with inflammatory responses in fetal-derived intestinal (FHs 74 Int) cells. Secretion of the proinflammatory cytokine IL-8 in FHs 74 Int cells was stimulated in the following order: α-Toc<γ-Toc<δ-Toc. A similar proinflammatory response was observed when inflammation was induced in FHs 74 Int cells. Modulation of IL-8 expression by Toc corresponded to an isoform-specific modulation of NF-κB and nuclear factor-erythroid 2-related factor 2 (Nrf2) cell signaling pathways involved in expression of proinflammatory cytokines and antioxidant enzymes, respectively. δ-Toc and, to a lesser extent, γ-Toc activated NF-κB and Nrf2 signaling, as indicated by the greater nuclear translocation of transcription factors. Activation of NF-κB signaling by γ- and δ-Toc was accompanied by upregulation of NF-κB target genes, such as IL-8 and prostaglandin-endoperoxide synthase 2, with and without a prior IFNγ-PMA challenge. Nevertheless, γ- and δ-Toc, particularly δ-Toc, concurrently downregulated glutamate-cysteine ligase, a Nrf2 target gene that encodes for glutathione biosynthesis. This observation was substantiated by confirmation that γ- and δ-Toc were effective at decreasing glutamate-cysteine ligase protein expression and cellular glutathione content. Downregulation of glutathione content in fetal intestinal cells corresponded to induction of apoptosis-mediated cytotoxicity. In conclusion, γ- and δ-Toc are biologically active isoforms of vitamin E and show superior bioactivity to α-Toc in modulating cell signaling events that contribute to a proinflammatory response in fetal-derived intestinal cells.

Cytoprotective signaling and gene expression in endothelial cells and macrophages-lessons for atherosclerosis

Atherosclerosis is a chronic inflammatory disease of the medium and large arteries driven in large part by the accumulation of oxidized low-density lipoproteins and other debris at sites rendered susceptible because of the geometry of the arterial tree. As lesions develop, they acquire a pathologic microcirculation that perpetuates lesion progression, both by providing a means for further monocyte and T-lymphocyte recruitment into the arterial wall and by the physical and chemical stresses caused by micro-hemorrhage. This review summarizes work performed in our department investigating the roles of signaling pathways, alone and in combination, that lead to specific programs of gene expression in the atherosclerotic environment. Focusing particularly on cytoprotective responses that might be enhanced therapeutically, the work has encompassed the anti-inflammatory effects of arterial laminar shear stress, mechanisms of induction of membrane inhibitors that prevent complement-mediated injury, homeostatic macrophage responses to hemorrhage, and the transcriptional mechanisms that control the stability, survival, and quiescence of endothelial monolayers. Lastly, while the field has been dominated by investigation into the mechanisms of DNA transcription, we consider the importance of parallel post-transcriptional regulatory mechanisms for fine-tuning functional gene expression repertoires.

Coregulation and modulation of NFκB-related genes in celiac disease: uncovered aspects of gut mucosal inflammation

It is known that the NFκB route is constitutively upregulated in celiac disease (CD), an immune-mediated disorder of the gut caused by intolerance to ingested gluten. Our aim was to scrutinize the expression patterns of several of the most biologically relevant components of the NFκB route in intestinal biopsies from active and treated patients and after in vitro gliadin challenge, and to assess normalization of the expression using an inhibitor of the MALT1 paracaspase. The expression of 93 NFκB genes was measured by RT-PCR in a set of uncultured active and treated CD and control biopsies, and in cultured biopsy series challenged with gliadin, the NFκB modulator, both compounds and none. Methylation of eight genes involved in NFκB signaling was analyzed by conventional pyrosequencing. Groups were compared and Pearson's correlation matrixes were constructed to check for coexpression and co-methylation. Our results confirm the upregulation of the NFκB pathway and show that constitutively altered genes usually belong to the core of the pathway and have central roles, whereas genes overexpressed only in active CD are more peripheral. Additionally, this is the first work to detect methylation level changes in celiac intestinal mucosa. Coexpression is very common in controls, whereas gliadin challenge and especially chronic inflammation present in untreated CD result in the disruption of the regulatory equilibrium. In contrast, co-methylation occurs more often in active CD. Importantly, NFκB modulation partially restores coregulation, opening the door to future therapeutic possibilities and targets.

Proteasome inhibition by bortezomib increases IL-8 expression in androgen-independent prostate cancer cells: the role of IKKα

Expression of the proinflammatory and proangiogenic chemokine IL-8, which is regulated at the transcriptional level by NF-κB, is constitutively increased in androgen-independent metastatic prostate cancer and correlates with poor prognosis. Inhibition of NF-κB-dependent transcription was used as an anticancer strategy for the development of the first clinically approved 26S proteasome inhibitor, bortezomib (BZ). Even though BZ has shown remarkable antitumor activity in hematological malignancies, it has been less effective in prostate cancer and other solid tumors; however, the mechanisms have not been fully understood. In this article, we report that proteasome inhibition by BZ unexpectedly increases IL-8 expression in androgen-independent prostate cancer PC3 and DU145 cells, whereas expression of other NF-κB-regulated genes is inhibited or unchanged. The BZ-increased IL-8 expression is associated with increased in vitro p65 NF-κB DNA binding activity and p65 recruitment to the endogenous IL-8 promoter. In addition, proteasome inhibition induces a nuclear accumulation of IκB kinase (IKK)α, and inhibition of IKKα enzymatic activity significantly attenuates the BZ-induced p65 recruitment to IL-8 promoter and IL-8 expression, demonstrating that the induced IL-8 expression is mediated, at least partly, by IKKα. Together, these data provide the first evidence, to our knowledge, for the gene-specific increase of IL-8 expression by proteasome inhibition in prostate cancer cells and suggest that targeting both IKKα and the proteasome may increase BZ effectiveness in treatment of androgen-independent prostate cancer.

A quantitative study of the cell-type specific modulation of c-Rel by hydrogen peroxide and TNF-α

Hydrogen peroxide (H₂O₂) at moderate steady-state concentrations synergizes with TNF-α, leading to increased nuclear levels of NF-κB p65 subunit and to a cell-type specific up-regulation of a limited number of NF-κB-dependent genes. Here, we address how H₂O₂ achieves this molecular specificity. HeLa and MCF-7 cells were exposed to steady-state H₂O₂ and/or TNF-α and levels of c-Rel, p65, IκB-α, IκB-β and IκB-ε were determined. For an extracellular concentration of 25 µM H₂O₂, the intracellular H₂O₂ concentration is 3.7 µM and 12.5 µM for respectively HeLa and MCF-7 cells. The higher cytosolic H₂O₂ concentration present in MCF-7 cells may be a contributing factor for the higher activation of NF-κB caused by H₂O₂ in this cell line, when compared to HeLa cells. In both cells lines, H₂O₂ precludes the recovery of TNF-α-dependent IκB-α degradation, which may explain the observed synergism between H₂O₂ and TNF-α concerning p65 nuclear translocation. In MCF-7 cells, H₂O₂, in the presence of TNF-α, tripled the induction of c-Rel triggered either by TNF-α or H₂O₂. Conversely, in HeLa cells, H₂O₂ had a small antagonistic effect on TNF-α-induced c-Rel nuclear levels, concomitantly with a 50 % induction of IκB-ε, the preferential inhibitor protein of c-Rel dimers. The 6-fold higher c-Rel/IκB-ε ratio found in MCF-7 cells when compared with HeLa cells, may be a contributing factor for the cell-type dependent modulation of c-Rel by H₂O₂.

Our results suggest that H₂O₂ might have an important cell-type specific role in the regulation of c-Rel-dependent processes, e.g. cancer or wound healing.

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Selective modulation of individual NF-κB-dependent genes expression by H₂O₂.

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In MCF-7 cells H₂O₂ tripled the TNF-α 4-fold induction of c-Rel nuclear levels.

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In HeLa cells, H₂O₂ had an antagonistic effect on TNF-α induced c-Rel translocation.

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c-Rel dimers bind chiefly to IκB-α/IκB-ε in MCF-7 cells and to IκB-ε in HeLa cells.

Therapeutic effects of saireito (chai-ling-tang), a traditional Japanese herbal medicine, on lymphedema caused by radiotherapy: a case series study

Despite the development of radiotherapy machines and technologies, a proportion of patients suffer from radiation-induced lymphedema. Saireito (SRT) is a traditional Japanese herbal medicine that has been used for treating edema and inflammation in conditions such as nephritic disease. This study investigated the effect of SRT on lymphedema caused by radiotherapy. Four patients were treated with SRT at a dose of 9 g/day. The severity of lymphedema was evaluated using the Common Terminology Criteria for Adverse Events version 4 and Numerical Rating Scale before and after SRT treatment. After the treatment with SRT, 2 of 4 patients (50%) showed apparent improvement in lymphedema. One of the cases had difficulty in wearing the custom-made thermoplastic cast, but after SRT administration, he could wear the mask easily. One case decided to stop taking SRT 3 days after initiation because cough and fever appeared. In conclusion, it is important to control the side effects of radiotherapy, which leads to improved tumor control rates. Prospective randomized studies are necessary to confirm the findings of this case series study.

Ethanol extract of Adiantum capillus-veneris L. suppresses the production of inflammatory mediators by inhibiting NF-κB activation

ETHNOPHARMACOLOGICAL RELEVANCE

Adiantum capillus-veneris L. is a wildly distributed plant species and has been extensively used in south of China as traditional folk medicine for the treatment of inflammatory diseases.

AIM OF THE STUDY

To investigate the anti-inflammatory effect of ethanolic extracts of Adiantum capillus-veneris L. and the involvement of NF-κB signaling in the regulation of inflammation.

MATERIALS AND METHODS

The plant ethanolic extracts were initially tested against lipopolysaccharide (LPS)-induced prostaglandin E2 (PGE2) production in RAW264.7 mouse macrophages, and interleukin 6 (IL-6) and tumor necrosis factor (TNF) production in human U937 monocytes. The effect of the plant extracts on the transcription factor nuclear factor kappa B (NF-κB) pathway was evaluated in TNF-α stimulated HepG2 cells by luciferase gene reporter assay and Western blotting at the transcriptional and translational levels. Subsequently, the inhibition of NF-κB downstream gene expression (IL-8 and ICAM-1) by the plant extracts was assessed via quantitative real time polymerase chain reaction (qPCR). Lastly, the anti-inflammatory activities of the plant extracts in vivo were evaluated by testing spleen index and NF-κB related protein expression in LPS-stimulated CD1 mice.

RESULTS

The plant ethanolic extracts effectively suppressed PGE2, IL-6 and TNF release with an IC50 less than 50 μg/ml. Moreover, luciferase expression could be specifically blocked in HepG2 cells, not in HEK293 cells, showing that the plant extracts displayed a cell-specific pattern on NF-κB gene transcription. The assayed biological activity also depended on the order of adding TNF-α and the plant extracts because the plant extracts could only block the NF-κB activation if added earlier but were unable to stop the signal when added after TNF-α. However, the plant extracts did not exert any effect on ubiquitination which regulates several steps in the NF-κB pathway. Additionally, the plant extracts down-regulated phosphorylation of IKKα/β at S176/180, p38 at T180/Y182 and p65 at S536, but not p65 at S276. This was confirmed by their ability to selectively abrogate the induction of IL-8 transcription, whereas the ICAM-1 gene, which is not transcribed selectively by an NF-κB complex containing a form of p65 phosphorylated on Ser536, did not change. Finally, the plant extracts at 200 μg/mg could normalize the LPS-induced elevation of spleen index as well as NF-κB and p38 activations in CD1 mice.

CONCLUSION

The present studies presents the potential utilization of this plant extracts, as a natural resources for the development of an anti-inflammatory medicine.

Constitutive and tumor necrosis factor-α-induced activation of nuclear factor-κB in adenomyosis and its inhibition by andrographolide

OBJECTIVE

To investigate the action of nuclear factor (NF)-κB in adenomyosis and evaluate the potential therapeutic effect of andrographolide on tumor necrosis factor (TNF)-α-induced expression of NF-κB-mediated genes cyclooxygease-2 (COX-2), vascular endothelial growth factor (VEGF), and tissue factor (TF) in adenomyotic stromal cells.

DESIGN

Laboratory study using human tissues.

SETTING

Academic hospital.

PATIENT(S)

Twenty-nine patients (cases) with histologically confirmed adenomyosis and 14 (controls) without adenomyosis or endometriosis.

INTERVENTION(S)

Endometrial stromal cells derived from tissue samples harvested from both cases and controls were subjected to electrophoretic mobility shift assay, and gene and protein expression analyses.

MAIN OUTCOME MEASURE(S)

The NF-κB DNA-binding activity and protein levels of NF-κB subunits p50 and p65 and the messenger RNA (mRNA) and protein levels of NF-κB-mediated genes COX-2, VEGF, and TF in cases and controls, and their changes after stimulation with TNF-α and treatment with andrographolide.

RESULT(S)

The constitutive NF-κB DNA-binding activity and protein expression levels of p50 and p65, and mRNA and protein levels of COX-2, VEGF, and TF in cases were significantly higher than that of controls. The binding activity level correlated positively with dysmenorrhea severity in cases. The TNF-α stimulation further increased the binding activity, and the mRNA and protein levels of COX-2, VEGF, and TF, but treatment with andrographolide significantly reduced them.

CONCLUSION(S)

NF-κB may be a pivotal transcription factor involved in the development of adenomyosis. Targeting NF-κB with inhibitors, like andrographolide, may hold promises of treating adenomyosis.

The serine phosphatase SerB of Porphyromonas gingivalis suppresses IL-8 production by dephosphorylation of NF-κB RelA/p65

Porphyromonas gingivalis is a major pathogen in severe and chronic manifestations of periodontal disease, which is one of the most common infections of humans. A central feature of P. gingivalis pathogenicity is dysregulation of innate immunity at the gingival epithelial interface, including suppression of IL-8 production by epithelial cells. NF-κB is a transcriptional regulator that controls important aspects of innate immune responses, and NF-κB RelA/p65 homodimers regulate transcription of IL8. Phosphorylation of the NF-κB p65 subunit protein on the serine 536 residue affects nuclear translocation and transcription of target genes. Here we show that SerB, a haloacid dehalogenase (HAD) family serine phosphatase secreted by P. gingivalis, is produced intracellularly and can specifically dephosphorylate S536 of p65 in gingival epithelial cells. A P. gingivalis mutant lacking SerB was impaired in dephosphorylation of p65 S536, and ectopically expressed SerB bound to p65 and co-localized with p65 in the cytoplasm. Ectopic expression of SerB also resulted in dephosphorylation of p65 with reduced nuclear translocation in TNF-α-stimulated epithelial cells. In contrast, the p105/50 subunit of NF-κB was unaffected by SerB. Co-expression of a constitutively active p65 mutant (S536D) relieved inhibition of nuclear translocation. Both the activity of the IL8 promoter and production of IL-8 were diminished by SerB. Deletion and truncation mutants of SerB lacking the HAD-family enzyme motifs of SerB were unable to dephosphorylate p65, inhibit nuclear translocation or abrogate IL8 transcription. Specific dephosphorylation of NF-κB p65 S536 by SerB, and consequent inhibition of nuclear translocation, provides the molecular basis for a bacterial strategy to manipulate host inflammatory pathways and repress innate immunity at mucosal surfaces.

Periodontal diseases are one of the most common infections of humans, and are characterized by gingival inflammation and destruction of the hard and soft tissues that support the tooth, eventually causing tooth loss. Porphyromonas gingivalis is a major pathogen in periodontal diseases and a key pathogenic attribute of this organism is the ability to disrupt host innate immunity. Infection of gingival epithelial cells by P. gingivalis suppresses production of the neutrophil chemokine IL-8. This inhibitory process is associated with the P. gingivalis serine phosphatase, SerB. In this study we show that SerB has a potent and specific ability to inhibit activation the NF-κB transcription factor which regulates IL-8 production. Mechanistically, SerB binds to and dephosphorylates the p65 subunit of NF-κB which prevents nuclear translocation and subsequent transcription of the IL8 gene. Targeting the NF-κB p65 subunit allows P. gingivalis to dampen IL-8 dependent inflammatory responses, facilitate survival and potentially to establish a favorable niche for the entire periodontal microbial community.

NF-κB is activated in response to temozolomide in an AKT-dependent manner and confers protection against the growth suppressive effect of the drug

Background

Most DNA-damaging chemotherapeutic agents activate the transcription factor nuclear factor κB (NF-κB). However, NF-κB activation can either protect from or contribute to the growth suppressive effects of the agent. We previously showed that the DNA-methylating drug temozolomide (TMZ) activates AKT, a positive modulator of NF-κB, in a mismatch repair (MMR) system-dependent manner. Here we investigated whether NF-κB is activated by TMZ and whether AKT is involved in this molecular event. We also evaluated the functional consequence of inhibiting NF-κB on tumor cell response to TMZ.

Methods

AKT phosphorylation, NF-κB transcriptional activity, IκB-α degradation, NF-κB2/p52 generation, and RelA and NF-κB2/p52 nuclear translocation were investigated in TMZ-treated MMR-deficient (HCT116, 293TLα^-) and/or MMR-proficient (HCT116/3-6, 293TLα⁺, M10) cells. AKT involvement in TMZ-induced activation of NF-κB was addressed in HCT116/3-6 and M10 cells transiently transfected with AKT1-targeting siRNA or using the isogenic MMR-proficient cell lines pUSE2 and KD12, expressing wild type or kinase-dead mutant AKT1. The effects of inhibiting NF-κB on sensitivity to TMZ were investigated in HCT116/3-6 and M10 cells using the NF-κB inhibitor NEMO-binding domain (NBD) peptide or an anti-RelA siRNA.

Results

TMZ enhanced NF-κB transcriptional activity, activated AKT, induced IκB-α degradation and RelA nuclear translocation in HCT116/3-6 and M10 but not in HCT116 cells. In M10 cells, TMZ promoted NF-κB2/p52 generation and nuclear translocation and enhanced the secretion of IL-8 and MCP-1. TMZ induced RelA nuclear translocation also in 293TLα⁺ but not in 293TLα^- cells. AKT1 silencing inhibited TMZ-induced IκB-α degradation and NF-κB2/p52 generation. Up-regulation of NF-κB transcriptional activity and nuclear translocation of RelA and NF-κB2/p52 in response to TMZ were impaired in KD12 cells. RelA silencing in HCT116/3-6 and M10 cells increased TMZ-induced growth suppression. In M10 cells NBD peptide reduced basal NF-κB activity, abrogated TMZ-induced up-regulation of NF-κB activity and increased sensitivity to TMZ. In HCT116/3-6 cells, the combined treatment with NBD peptide and TMZ produced additive growth inhibitory effects.

Conclusion

NF-κB is activated in response to TMZ in a MMR- and AKT-dependent manner and confers protection against drug-induced cell growth inhibition. Our findings suggest that a clinical benefit could be obtained by combining TMZ with NF-κB inhibitors.

Copper(II) oxide nanoparticles penetrate into HepG2 cells, exert cytotoxicity via oxidative stress and induce pro-inflammatory response

The potential toxic effects of two types of copper(II) oxide (CuO) nanoparticles (NPs) with different specific surface areas, different shapes (rod or spheric), different sizes as raw materials and similar hydrodynamic diameter in suspension were studied on human hepatocarcinoma HepG2 cells. Both CuO NPs were shown to be able to enter into HepG2 cells and induce cellular toxicity by generating reactive oxygen species. CuO NPs increased the abundance of several transcripts coding for pro-inflammatory interleukins and chemokines. Transcriptomic data, siRNA knockdown and DNA binding activities suggested that Nrf2, NF-κB and AP-1 were implicated in the response of HepG2 cells to CuO NPs. CuO NP incubation also induced activation of MAPK pathways, ERKs and JNK/SAPK, playing a major role in the activation of AP-1. In addition, cytotoxicity, inflammatory and antioxidative responses and activation of intracellular transduction pathways induced by rod-shaped CuO NPs were more important than spherical CuO NPs. Measurement of Cu(2+) released in cell culture medium suggested that Cu(2+) cations released from CuO NPs were involved only to a small extent in the toxicity induced by these NPs on HepG2 cells.

Cigarette smoke and its component acrolein augment IL-8/CXCL8 mRNA stability via p38 MAPK/MK2 signaling in human pulmonary cells

Interleukin-8 (IL-8/CXCL8) is an important neutrophil chemoattractant known to be elevated in the airways of cigarette smokers and in patients with chronic obstructive pulmonary disease (COPD). We examined the acute effect of aqueous cigarette smoke extract (CSE) on IL-8 expression in primary human pulmonary cells, in particular in normal human bronchial smooth muscle cells (HBSMCs). IL-8 mRNA levels increased upon CSE exposure in a concentration- and time-dependent manner, and such an effect was accompanied by IL-8 secretion. CSE-evoked elevation of IL-8 mRNA was mimicked by its component acrolein. Both CSE and acrolein induced p38 mitogen-activated protein kinase (MAPK) phosphorylation, accompanied by the phosphorylation of MAPK-activated kinase 2 (MK2), a known downstream substrate of the p38 MAPK, both in HBSMCs and in human airway epithelial cells. Furthermore, pharmacological inhibition of p38 MAPK or MK2 strongly accelerated the decay of IL-8 mRNA levels upon stimulation with CSE or acrolein and subsequent blockade of mRNA neosynthesis with actinomycin D in pulmonary structural cells (HBSMCs and airways epithelial cells) as well as in human alveolar macrophages. Conversely, pharmacological inhibition of ERK1/2 signaling inhibited CSE-induced steady-state levels of IL-8 mRNA without affecting mRNA stability, thus suggesting inhibition at the transcriptional level. In sum, p38 MAPK/MK2 signaling is an important posttranscriptional mechanism underlying upregulation of IL-8 mRNA levels elicited by CSE and acrolein. Given the pivotal role of IL-8 in neutrophil chemotaxis and activation, our results shed light on the mechanisms through which cigarette smoke can initiate inflammation in the lung.

Lactobacilli differently regulate expression and secretion of CXCL8 in urothelial cells

Modulation of the immune response is an established feature of certain lactobacilli. CXCL8 is an inflammatory chemokine released by the urinary tract mucosa after contact with uropathogenic Escherichia coli during urinary tract infection and is crucial for proper infiltration of immune cells. Nevertheless, persistently high levels of CXCL8 are associated with pathogenicity and malignancy. In this study, we tested twelve Lactobacillus strains for their ability to influence CXCL8 release from urothelial cells. We evaluated how strains from different Lactobacillus species could regulate CXCL8 in human 5637 urothelial cells, either resting cells or cells concomitantly challenged with heat-killed E. coli. A majority of the tested species altered CXCL8 release from the urothelial cells after 24 hours of stimulation. Most species increased CXCL8 release, whereas a few lactobacilli efficiently suppressed CXCL8 secretion from E. coli-challenged cells. While strong CXCL8 modulators such as Lactobacillus reuteri and Lactobacillus delbrueckii were unable to degrade CXCL8 in the extracellular environment, effects on IL8 transcription were evident for selected lactobacilli. Although IL8 transcription was affected by lactobacilli, the influence on mRNA transcript did not correlate to the impact on CXCL8 release. Phylogenetic analysis based on a 16S rRNA dendrogram of the tested lactobacilli and their effect on CXCL8 revealed some linkage to specific Lactobacillus groups. Testing the immunomodulatory nature of lactobacilli can prove important when selecting new probiotic microbes. Moreover, we believe that phylogenetic and phenotypic similarities could be used to analyse the traits governing such modulation.

Human pituitary tumor-transforming gene 1 overexpression reinforces oncogene-induced senescence through CXCR2/p21 signaling in breast cancer cells

Introduction

hPTTG1 (human pituitary tumor-transforming gene 1) is an oncogene overexpressed in breast cancer and several other types of cancer. Increased hPTTG1 expression has been shown to be associated with poor patient outcomes in breast cancer. Although hPTTG1 overexpression plays important roles in promoting the proliferation, invasion, and metastasis of cancer cells, it also has been suggested to induce cellular senescence. Deciphering the mechanism by which hPTTG1 overexpression induces these contradictory actions in breast cancer cells is critical to our understanding of the role of hPTTG1 in breast cancer development.

Methods

MCF-10A and MCF-7 cells were used to identify the mechanism of hPTTG1-induced senescence. The interplay between hPTTG1 overexpression and chemokine C-X-C motif receptor 2 (CXCR2)/p21-dependent senescence in tumor growth and metastasis of MCF-7 cells was investigated by orthotopic transplantation of severe combined immunodeficiency (SCID) mice. Additionally, human invasive ductal carcinoma (IDC) tissue arrays were used to confirm the hPTTG1/CXCR2/p21 axis established in vitro.

Results

In this study, we investigated the mechanism of hPTTG1-induced senescence as well as its role in breast cancer progression and metastasis. Herein, we showed that hPTTG1 overexpression reinforced senescence through the CXCR2/p21 signaling. Furthermore, hPTTG1 overexpression activated NF-κB signaling to transactivate the expression of interleukin (IL)-8 and growth-regulated oncogene alpha (GROα) to execute CXCR2 signaling in MCF-7 cells. When CXCR2 expression was knocked down in hPTTG1-overexpressing MCF-7 cells, hPTTG1-induced senescence was abrogated by alleviating CXCR2-induced p21 expression. In a mouse model, CXCR2-mediated senescence limited hPTTG1-induced tumor growth and metastasis. Moreover, CXCR2 knockdown in hPTTG1-overexpressing MCF-7 tumors dramatically accelerated tumor growth and metastasis. Our in vitro and in vivo results demonstrated that hPTTG1 overexpression reinforces senescence through CXCR2 signaling, and the evasion of CXCR2/p21-dependent senescence was critical to hPTTG1 exerting its oncogenic potential. Interestingly, although CXCR2-dependent senescence restrained hPTTG1-induced tumor progression, when MCF-7 cells and hPTTG1-overexpressing MCF-7 cells were co-transplanted into the mammary fat pads of SCID mice, hPTTG1-overexpressing senescent cells created a metastasis-promoting microenvironment that promoted lung metastasis of the MCF-7 cells. Immunohistochemical analysis of human breast tumor samples also confirmed the importance of the hPTTG1/CXCR2 axis in promoting breast cancer metastasis.

Conclusions

Our findings provide novel molecular insights into hPTTG1-induced senescence and identify a novel mechanism by which hPTTG1 promotes metastasis by regulating the senescence-associated microenvironment.

Abacavir alters the transcription of inflammatory cytokines in virologically suppressed, HIV-infected women

BACKGROUND

Abacavir (ABC) may be associated with a small, increased risk of myocardial infarction in HIV-infected adults, possibly related to cytokine-mediated inflammation.

METHODS

To evaluate the induction of inflammatory cytokine transcription by ABC, we used samples from women randomized to receive zidovudine/lamivudine/ABC (Trizivir) or lopinavir/ritonavir and zidovudine/lamividine (Kaletra/Combivir) from the third trimester through six-months postpartum for the prevention of mother-to-child transmission (PMTCT). Women were matched by CD4 count and baseline HIV RNA. All women attained viral suppression (<50 copies/ml) by the time of sampling.

RESULTS

Four cytokines showed a difference in expression between the treatment arms, all in a proinflammatory direction for the ABC arm: CD40LG 1.82-fold, (p=.027); IL-8 3.16-fold (p=.020); LTA 2.82-fold, (p=.008); and CCL5 -1.67-fold, (p=.035). At 12-months postpartum, 6-months after antiretroviral discontinuation, cytokine expression was similar by treatment arm.

CONCLUSIONS

We conclude that ABC may upregulate proinflammatory cytokines at the transcriptional level in this population.

Substances released from probiotic Lactobacillus rhamnosus GR-1 potentiate NF-κB activity in Escherichia coli-stimulated urinary bladder cells

Lactobacillus rhamnosus GR-1 is a probiotic bacterium used to maintain urogenital health. The putative mechanism for its probiotic effect is by modulating the host immunity. Urinary tract infections (UTI) are often caused by uropathogenic Escherichia coli that frequently evade or suppress immune responses in the bladder and can target pathways, including nuclear factor-kappaB (NF-κB). We evaluated the role of L. rhamnosus GR-1 on NF-κB activation in E. coli-stimulated bladder cells. Viable L. rhamnosus GR-1 was found to potentiate NF-κB activity in E. coli-stimulated T24 bladder cells, whereas heat-killed lactobacilli demonstrated a marginal increase in NF-κB activity. Surface components released by trypsin- or LiCl treatment, or the resultant heat-killed shaved lactobacilli, had no effect on NF-κB activity. Isolation of released products from L. rhamnosus GR-1 demonstrated that the induction of NF-κB activity was owing to released product(s) with a relatively large native size. Several putative immunomodulatory proteins were identified, namely GroEL, elongation factor Tu and NLP/P60. GroEL and elongation factor Tu have previously been shown to elicit immune responses from human cells. Isolating and using immune-augmenting substances produced by lactobacilli is a novel strategy for the prevention or treatment of UTI caused by immune-evading E. coli.

Inflammasome-mediated IL-1β production in humans with cystic fibrosis

BACKGROUND

Inflammation and infection are major determinants of disease severity and consequently, the quality of life and outcome for patients with cystic fibrosis (CF). Interleukin-1 beta (IL-1β) is a key inflammatory mediator. Secretion of biologically active IL-1β involves inflammasome-mediated processing. Little is known about the contribution of IL-1β and the inflammasomes in CF inflammatory disease. This study examines inflammasome-mediated IL-1β production in CF bronchial epithelial cell lines and human patients with CF.

RESULTS

Bronchial epithelial cell lines were found to produce negligible amounts of basal or stimulated IL-1β compared to hematopoeitic cells and they did not significantly upregulate caspase-1 activity upon inflammasome stimulation. In contrast, peripheral blood mononuclear cells (PBMCs) from both CF and healthy control subjects produced large amounts of IL-1β and strongly upregulated caspase-1 activity upon inflammasome stimulation. PBMCs from CF patients and controls displayed similar levels of caspase-1 activation and IL-1β production when stimulated with inflammasome activators. This IL-1β production was dependent on NF-κB activity and could be enhanced by priming with LPS. Finally, chemical inhibition of CFTR activity in control PBMCs and THP-1 cells did not significantly alter IL-1β or IL-8 production in response to P. aeruginosa.

CONCLUSION

Hematopoeitic cells appear to be the predominant source of inflammasome-induced pro-inflammatory IL-1β in CF. PBMCs derived from CF subjects display preserved inflammasome activation and IL-1β secretion in response to the major CF pathogen Pseudomonas aeruginosa. However, our data do not support the hypothesis that increased IL-1β production in CF subjects is due to an intrinsic increase in NF-κB activity through loss of CFTR function.

Paraoxonases-2 and -3 Are Important Defense Enzymes against Pseudomonas aeruginosa Virulence Factors due to Their Anti-Oxidative and Anti-Inflammatory Properties

The pathogen Pseudomonas aeruginosa causes serious damage in immunocompromised patients by secretion of various virulence factors, among them the quorum sensing N-(3-oxododecanoyl)-L-homoserine lactone (3OC12) and the redox-active pyocyanin (PCN). Paraoxonase-2 (PON2) may protect against P. aeruginosa infections, as it efficiently inactivates 3OC12 and diminishes PCN-induced oxidative stress. This defense could be circumvented because 3OC12 mediates intracellular Ca(2+)-rise in host cells, which causes rapid inactivation and degradation of PON2. Importantly, we recently found that the PON2 paralogue PON3 prevents mitochondrial radical formation. Here we investigated its role as additional potential defense mechanism against P. aeruginosa infections. Our studies demonstrate that PON3 diminished PCN-induced oxidative stress. Moreover, it showed clear anti-inflammatory potential by protecting against NF-κB activation and IL-8 release. The latter similarly applied to PON2. Furthermore, we observed a Ca(2+)-mediated inactivation and degradation of PON3, again in accordance with previous findings for PON2. Our results suggest that the anti-oxidative and anti-inflammatory functions of PON2 and PON3 are an important part of our innate defense system against P. aeruginosa infections. Furthermore, we conclude that P. aeruginosa circumvents PON3 protection by the same pathway as for PON2. This may help identifying underlying mechanisms in order to sustain the protection afforded by these enzymes.

Resistance exercise increases NF-κB activity in human skeletal muscle

Intense resistance exercise causes a significant inflammatory response. NF-κB has been identified as a prospective key transcription factor mediating the postexercise inflammatory response. The purpose of this study was to determine whether a single bout of intense resistance exercise regulates NF-κB signaling in human skeletal muscle. Muscle biopsy samples were obtained from the vastus lateralis of five recreationally active, but not strength-trained, males (21.9 ± 1.3 yr) prior to, and at 2 and 4 h following, a single bout of intense resistance exercise. A further five subjects (4 males, 1 female) (23 ± 0.89 yr) were recruited as a nonexercise control group to examine the effect of the muscle biopsy protocol on key markers of skeletal muscle inflammation. Protein levels of IκBα and phosphorylated NF-κB (p65), as well as the mRNA expression of inflammatory myokines monocyte chemoattractant protein 1 (MCP-1), IL-6, and IL-8 were measured. Additionally, NF-κB (p65) DNA binding to the promoter regions of MCP-1, IL-6, and IL-8 was investigated. IκBα protein levels decreased, while p-NF-κB (p65) protein levels increased 2 h postexercise and returned to near-baseline levels by 4-h postexercise. Immunohistochemical data verified these findings, illustrating an increase in p-NF-κB (p65) protein levels, and nuclear localization at 2 h postexercise. Furthermore, NF-κB DNA binding to MCP-1, IL-6, and IL-8 promoter regions increased significantly 2 h postexercise as did mRNA levels of these myokines. No significant change was observed in the nonexercise control group. These novel data provide evidence that intense resistance exercise transiently activates NF-κB signaling in human skeletal muscle during the first few hours postexercise. These findings implicate NF-κB in the transcriptional control of myokines known to be central to the postexercise inflammatory response.

Involvement of metabotropic glutamate receptor 5, AKT/PI3K signaling and NF-κB pathway in methamphetamine-mediated increase in IL-6 and IL-8 expression in astrocytes

Methamphetamine (MA) is one of the commonly used illicit drugs and the central nervous system toxicity of MA is well documented. The mechanisms contributing to this toxicity have not been fully elucidated. In this study, we investigated the effect of MA on the expression levels of the proinflammatory cytokines/chemokines, IL-6 and IL-8 in an astrocytic cell line. The IL-6 and IL-8 RNA levels were found to increase by 4.6 ± 0.2 fold and 3.5 ± 0.2 fold, respectively, after exposure to MA for three days. Exposure of astrocytes to MA for 24 hours also caused increased expression of IL-6 and IL-8 at the level of both RNA and protein. The potential involvement of the nuclear factor-Kappa B (NF-κB) pathway was explored as one of the possible mechanism(s) responsible for the increased induction of IL-6 and IL-8 by MA. The MA-mediated increases in IL-6 and IL-8 were significantly abrogated by SC514. We also found that exposure of astrocytes to MA results in activation of NF-κB through the phosphorylation of IκB-α, followed by translocation of active NF-κB from the cytoplasm to the nucleus. In addition, treatment of cells with a specific inhibitor of metabotropic glutamate receptor-5 (mGluR5) revealed that MA-mediated expression levels of IL-6 and IL-8 were abrogated by this treatment by 42.6 ± 5.8% and 65.5 ± 3.5%, respectively. Also, LY294002, an inhibitor of the Akt/PI3K pathway, abrogated the MA-mediated induction of IL-6 and IL-8 by 77.9 ± 6.6% and 81.4 ± 2.6%, respectively. Thus, our study demonstrates the involvement of an NF-κB-mediated signaling mechanism in the induction of IL-6 and IL-8 by MA. Furthermore, we showed that blockade of mGluR5 can protect astrocytes from MA-mediated increases of proinflammatory cytokines/chemokines suggesting mGluR5 as a potential therapeutic target in treating MA-mediated neurotoxicity.

The myxobacterial compounds spirangien a and spirangien M522 are potent inhibitors of IL-8 expression

Elevated expression of interleukin-8 (IL-8) has been implicated in inflammatory diseases, in tumor growth, and in angiogenesis. The aim of this study was to identify natural or synthetic compounds that suppress IL-8 production in response to interleukin-1 (IL-1), the natural inflammatory stimulus of the IL-8 gene. We therefore developed an IL-1-inducible cell-based screening assay by stable integration of an IL-8 reporter gene into HeLa S3 cells. The screening of heterogeneous compound libraries revealed several compounds that displayed an inhibitory effect on the reporter gene expression. Following hit validation, we focused on the most efficient compound, spirangien A, and its chemical derivate spirangien M522. Detailed analysis shows that both compounds are potent inhibitors of the endogenous IL-8 gene transcription. Furthermore, both compounds decelerate the phosphorylation and degradation of IκBα, the key regulator of the IL-1-stimulated NF-κB signaling pathway. Our study has identified the two spirangiens A and M522 as potent inhibitors of IL-1/NF-κB-mediated IL-8 gene expression.

BMP type II receptor deficiency confers resistance to growth inhibition by TGF-β in pulmonary artery smooth muscle cells: role of proinflammatory cytokines

Mutations in the bone morphogenetic protein (BMP) type II receptor (BMPR-II) underlie most cases of heritable pulmonary arterial hypertension (HPAH) and a significant proportion of sporadic cases. Pulmonary artery smooth muscle cells (PASMCs) from patients with pulmonary arterial hypertension (PAH) not only exhibit attenuated growth suppression by BMPs, but an abnormal mitogenic response to transforming growth factor (TGF)-β1. We sought to define the mechanism underlying this loss of the antiproliferative effects of TGF-β1 in BMPR-II-deficient PASMCs. The effect of TGF-β1 on PASMC proliferation was characterized in three different models of BMPR-II dysfunction: 1) HPAH PASMCs, 2) Bmpr2(+/-) mouse PASMCs, and 3) control human PASMCs transfected with BMPR-II small interfering RNA. BMPR-II reduction consistently conferred insensitivity to growth inhibition by TGF-β1. This was not associated with altered canonical TGF-β1/Smad signaling but was associated with a secreted factor. Microarray analysis revealed that the transcriptional responses to TGF-β1 differed between control and HPAH PASMCs, particularly regarding genes associated with interleukins and inflammation. HPAH PASMCs exhibited enhanced IL-6 and IL-8 induction by TGF-β1, an effect reversed by NF-κB inhibition. Moreover, neutralizing antibodies to IL-6 or IL-8 restored the antiproliferative effect of TGF-β1 in HPAH PASMCs. This study establishes that BMPR-II deficiency leads to failed growth suppression by TGF-β1 in PASMCs. This effect is Smad-independent but is associated with inappropriately altered NF-κB signaling and enhanced induction of IL-6 and IL-8 expression. Our study provides a rationale to test anti-interleukin therapies as an intervention to neutralize this inappropriate response and restore the antiproliferative response to TGF-β1.

Carotenoid exposure of Caco-2 intestinal epithelial cells did not affect selected inflammatory markers but altered their proteomic response

Carotenoid consumption has been linked to a number of beneficial health effects, including the reduction of chronic diseases such as cancer and cardiovascular complications. However, no data are available on their action on the intestinal epithelium, being exposed to the highest concentrations of carotenoids in the human body, and where they could act preventively on intestinal inflammatory diseases such as Crohn's disease and ulcerative colitis. The objective of the present study was to investigate whether lycopene and β-carotene in micelles (M), at concentrations that could be reached via the diet (10-25 μg/ml) could aid in the reduction of TNF-α plus IL-1β-induced inflammation of Caco-2 human epithelial cells. The impact on biomarkers of inflammation, including IL-8, NO and cyclo-oxygenase-2 (through PGE-2α), and the NF-κB and mitogen-activated protein kinase (MAPK) pathways of intracellular signalling cascades were evaluated compared with controls (empty M). Furthermore, proteomic analyses were conducted from total cellular protein extracts. The results revealed that isolated carotenoids had no statistical significant anti-inflammatory effect on the biomarkers observed, or on the regulation of NF-κB and MAPK. Nevertheless, analyses of the proteome suggested that fifteen proteins were significantly (P < 0·05, expression ratio >1·3) differentially regulated following β-carotene exposure, participating mostly in metabolic activities including antioxidant mechanisms, such as glutathione S-transferase A1. Only one protein was differentially regulated by lycopene (profilin-1). To our knowledge, this is the first attempt to investigate pathways involved in the action of carotenoids on the intestinal epithelium.

Differential effects of selenium and knock-down of glutathione peroxidases on TNFα and flagellin inflammatory responses in gut epithelial cells

Selenium (Se) is essential for human health. Despite evidence that Se intake affects inflammatory responses, the mechanisms by which Se and the selenoproteins modulate inflammatory signalling, especially in the gut, are not yet defined. The aim of this work was to assess effects of altered Se supply and knock-down of individual selenoproteins on NF-κB activation in gut epithelial cells. Caco-2 cells were stably transfected with gene constructs expressing luciferase linked either to three upstream NF-κB response elements and a TATA box or only a TATA box. TNFα and flagellin activated NF-κB-dependent luciferase activity and increased IL-8 expression. Se depletion decreased expression of glutathione peroxidase1 (GPX1) and selenoproteins H and W and increased TNFα-stimulated luciferase activity, endogenous IL-8 expression and reactive oxygen species (ROS) production. These effects were not mimicked by independent knock-down of either GPX1, selenoprotein H or W; indeed, GPX1 knock-down lowered TNFα-induced NF-κB activation and did not affect ROS levels. GPX4 knock-down decreased NF-κB activation by flagellin but not by TNFα. We hypothesise that Se depletion alters the pattern of expression of multiple selenoproteins that in turn increases ROS and modulates NF-κB activation in epithelial cells, but that the effect of GPX1 knock-down is ROS-independent.

Flice inhibitory protein is associated with the survival of neonatal neutrophils

Neonatal polymorphonuclear leukocytes (PMN) exhibit delayed apoptosis both constitutively and under inflammatory conditions, and evidence has linked PMN longevity to the presence of antiapoptotic proteins. Activation of the survival-associated transcription factor, nuclear factor kappa B (NF-κB), promotes the synthesis of several antiapoptotic proteins including Flice inhibitory protein (FLIP). Neonatal and adult PMN were compared in this study to test the hypothesis that FLIP modulates age-related apoptosis. Expression of the short isoform, FLIP-S, was prominent at baseline and persisted during spontaneous apoptosis in neonatal PMN, whereas basal expression was lower and decreased under the same conditions in adult PMN. Stable FLIP-S expression in neonatal PMN was associated with a relative resistance to apoptosis in response to the protein synthesis inhibitor, cycloheximide (CHX), or the NF-κB inhibitor, gliotoxin. In contrast, similar treatment of adult PMN promoted greater overall apoptosis accompanied by FLIP degradation. Nuclear levels of phosphorylated p65, a critical NF-κB dimer, were relatively robust in neonatal PMN under basal conditions or after stimulation with TNF-α, a cytokine that induces FLIP. In conclusion, persistent FLIP-S expression is involved in the longevity of neonatal PMN, and our data suggest a contribution of NF-κB signaling and related survival mechanisms.

Nuclear factor-κB: a key regulator in health and disease of lungs

Rel/NF-κB transcription factors play a key role in modulating the response of immunoregulatory genes including cytokines and chemokines, cell adhesion molecules, acute phase proteins, and anti-microbial peptides. Furthermore, an array of genes important for angiogenesis, tumor invasion and metastasis is also regulated by nuclear factor-κB (NF-κB). Close association of NF-κB with inflammation and tumorigenesis makes it an attractive target for basic research as well as for pharmaceutical industries. Studies involving various animal and cellular models have revealed the importance of NF-κB in pathobiology of lung diseases. This review (a) describes structures, activities, and regulation of NF-κB family members; (b) provides information which implicates NF-κB in pathogenesis of pulmonary inflammation and cancer; and (c) discusses information about available synthetic and natural compounds which target NF-κB or specific components of NF-κB signal transduction pathway and which may provide the foundation for development of effective therapy for lung inflammation and bronchogenic carcinomas.

Differential effects of Radix Paeoniae Rubra (Chishao) on cytokine and chemokine expression inducible by mycobacteria

Background

Upon initial infection with mycobacteria, macrophages secrete multiple cytokines and chemokines, including interleukin-6 (IL-6), IL-8 and tumor necrosis factor-α (TNF-α), to mediate host immune responses against the pathogen. Mycobacteria also induce the production of IL-10 via PKR activation in primary human monocytes and macrophages. As an anti-inflammatory cytokine, over-expression of IL-10 may contribute to mycobacterial evasion of the host immunity. Radix Paeoniae Rubra (RPR, Chishao), a Chinese medicinal herb with potentials of anti-inflammatory, hepatoprotective and neuroprotective effects, is used to treat tuberculosis. This study investigates the immunoregulatory effects of RPR on primary human blood macrophages (PBMac) during mycobacterial infection.

Methods

The interaction of Bacillus Calmette-Guerin (BCG) with PBMac was used as an experimental model. A series of procedures involving solvent extraction and fractionation were used to isolate bioactive constituents in RPR. RPR-EA-S1, a fraction with potent immunoregulatory effects was obtained with a bioactivity guided fractionation scheme. PBMac were treated with crude RPR extracts or RPR-EA-S1 before BCG stimulation. The expression levels of IL-6, IL-8, IL-10 and TNF-α were measured by qPCR and ELISA. Western blotting was used to determine the effects of RPR-EA-S1 on signaling kinases and transcriptional factors in the BCG-activated PBMac.

Results

In BCG-stimulated macrophages, crude RPR extracts and fraction RPR-EA-S1 specifically inhibited IL-10 production while enhanced IL-8 expression at both mRNA and protein levels without affecting the expressions of IL-6 and TNF-α. Inhibition of BCG-induced IL-10 expression by RPR-EA-S1 occurred in a dose- and time-dependent manner. RPR-EA-S1 did not affect the phosphorylation of cellular protein kinases including MAPK, Akt and GSK3β. Instead, it suppressed the degradation of IκBα in the cytoplasm and inhibited the translocation of transcription factor NF-κB1 p50 to the nucleus.

Conclusion

RPR crude extracts and its fraction RPR-EA-S1 inhibited anti-inflammatory cytokine IL-10 and enhanced pro-inflammatory chemokine IL-8 expression in BCG-activated PBMac. The inhibitory effects of RPR-EA-S1 on IL-10 expression in BCG-activated PBMac may be due to the reduced nuclear translocation of NF-κB1 p50.

Evaluation of SV40-transformed synovial fibroblasts in the study of rheumatoid arthritis pathogenesis

The SV40 T antigen has been used to generate immortalized cells from rheumatoid arthritis (RA) synovial fibroblasts (RASFs) that are commonly used in lieu of primary RASFs. In the current study, we investigated the effect of stimulation by tissue necrosis factor alpha (TNF-α) and interleukin 17 (IL-17) on primary and immortalized RASFs in order to gauge the appropriateness of the use of immortalized RASFs, the MH7A cell line, in the study of RA pathogenesis. Changes in the levels of secretion and expression of 8 proteins associated with RA upon stimulation were assessed by multiplex immunoassay. IL-17 stimulation had a minimal impact on protein secretion and expression for primary and immortalized cells. Basic fibroblast growth factor (FGF-2) was not detectable for the primary cells but was detectable for the immortalized cells. In contrast, monocyte chemoattractant protein 1 (MCP-1) was detectable for primary cells but was undetectable for immortalized cells. In general, protein expression and secretion by cells stimulated with TNF-α were significantly increased. For primary cells, several proteins were below the limit of detection for unstimulated cells and cells stimulated with IL-17, while levels for TNF-α-stimulated cells were within the detectable range. For the same proteins, expression was observed for immortalized cells, regardless of stimulation, suggestive of constitutive activation of the NF-κB signaling pathway. The current study therefore provides strong evidence that immortalized and primary RASFs differ in regard to protein expression and secretion and therefore may not be appropriate for use in the study of RA pathogenesis.

Novel roles for hypoxia and prostaglandin E2 in the regulation of IL-8 during endometrial repair

The endometrium has a remarkable capacity for efficient repair; however, factors involved remain undefined. Premenstrual progesterone withdrawal leads to increased prostaglandin (PG) production and local hypoxia. Here we determined human endometrial expression of interleukin-8 (IL-8) and the roles of PGE(2) and hypoxia in its regulation. Endometrial biopsy specimens (n = 51) were collected. Endometrial cells and explants were exposed to 100 nmol/L of PGE(2) or 0.5% O(2). The endometrial IL-8 concentration peaked during menstruation (P < 0.001) and had a significant proangiogenic effect. IL-8 was increased by PGE(2) and hypoxia in secretory but not proliferative explants, which suggests that exposure to progesterone is essential. In vitro progesterone withdrawal induced significant IL-8 up-regulation in proliferative explants primed with progestins, but only in the presence of hypoxia. Epithelial cells treated simultaneously with PGE(2) and hypoxia demonstrated synergistic increases in IL-8. Inhibition of HIF-1 by short hairpin RNA abolished hypoxic IL-8 induction, and inhibition of NF-κB by an adenoviral dominant negative inhibitor decreased PGE(2)-induced IL-8 expression (P > 0.05). Increased menstrual IL-8 is consistent with a role in repair. Progesterone withdrawal, hypoxia, and PGE(2) regulate endometrial IL-8 by acting via HIF-1 and NF-κB. Hence, progesterone withdrawal may activate two distinct pathways to initiate endometrial repair.

Lingual antimicrobial peptide and IL-8 expression are oppositely regulated by the antagonistic effects of NF-κB p65 and C/EBPβ in mammary epithelial cells

Pathogen contact induces quickly in Mammary Epithelial Cells (MEC) the expression of the proinflammatory cytokine IL-8 and delayed that of the bactericidal β-defensin LAP. Both genes encoding these factors feature on their proximal promoter a composite NF-κB/CEBP binding site. We compare here in MEC the role of NF-κB and C/EBP factors in regulating basal and pathogen-induced expression of both genes from cattle. Abrogating NF-κB binding to that site by introduction of a single point mutation blocks promoter activity of both genes in reporter gene assays. Chromatin accessibility PCR and Chromatin immunoprecipitation reveal that the chromatin of the resting LAP promoter is tightly packed and NF-κB p50 homodimer binding prevails. Infection results in chromatin decompaction accompanied by predominant recruitment of NF-κB p65 for promoter activation. Overexpression of transcription factors confirms a stimulatory role of NF-κB p65 but also a repressive function of C/EBPβ for LAP promoter activity. These factors reverse roles to control IL-8 expression. NF-κB p65 homodimers already reside on the resting IL-8 promoter and induction recruits NF-κB p50. Overexpression of both NF-κB factors represses the promoter in MEC, but not in HEK293 cells. Inhibitors of NF-κB activation and nuclear recruitment both tremendously increase basal and pathogen stimulated IL-8 mRNA concentrations in MEC. Mutation of the C/EBP-binding site blocks and overexpression of C/EBPβ stimulates IL-8-promoter activity. Thus, the pathogen-induced fast activation of diverse transcription factors acting through a common promoter binding site is gene specifically differentiated into opposite functional significance for swiftly (IL-8) or slowly (LAP) induced genes in MEC.

Inhibitors of p38 and ERK1/2 MAPkinase and hydrogen sulphide block constitutive and IL-1β-induced IL-6 and IL-8 expression in the human chondrocyte cell line C-28/I2

Mitogen-activated protein kinases (MAPKs) play a central role in inflammatory processes, and their blockage represents pharmacological approaches in the treatment of autoimmune diseases like rheumatoid arthritis (RA). Alternatively, H(2)S has long been used in sulphur bath therapy for patients suffering from different types of rheumatic disorders, but reports about the beneficial effects of this form of therapy are controversial, rare and of poor scientific quality. The human chondrocyte cell line C-28/I2 was treated with two different MAPK inhibitors (SB203580 and U0126) or with various concentrations of the H(2)S donor Natrium hydrogen sulphide (NaHS). Thereafter, the secretion of IL-6 and IL-8 was quantified by enzyme-linked immunosorbent assays (ELISAs). The impact of NaHS on the regulation of p38 and ERK1/2 MAPK was confirmed by Western blot experiments. Furthermore, IL-6 and IL-8 expression was quantified by real-time polymerase chain reaction (RT-PCR) and ELISAs from cells which were exposed to SB203580, U0126 and NaHS and stimulated by IL-1β. The C-28/I2 cells constitutively expressed large quantities of IL-6 and IL-8. The data provided prove that in these cells, constitutive as well as IL-1β-induced IL-6 and IL-8 expression was partially and transiently blocked by the treatment of cells with both MAPK inhibitors and NaHS. Presented data seem to be important in evaluating the beneficial functions of MAPK inhibitors and H(2)S in immune-pathophysiological processes.

When NRF2 talks, who's listening?

Activation of the KEAP1-NRF2 signaling pathway is an adaptive response to environmental and endogenous stresses and serves to render animals resistant to chemical carcinogenesis and other forms of toxicity, whereas disruption of the pathway exacerbates these outcomes. This pathway, which can be activated by sulfhydryl-reactive, small-molecule pharmacologic agents, regulates the inducible expression of an extended battery of cytoprotective genes, often by direct binding of the transcription factor to antioxidant response elements in the promoter regions of target genes. However, it is becoming evident that some of the protective effects may be mediated indirectly through cross talk with additional pathways affecting cell survival and other aspects of cell fate. These interactions provide a multi-tiered, integrated response to chemical stresses. This review highlights recent observations on the molecular interactions and their functional consequences between NRF2 and the arylhydrocarbon receptor (AhR), NF-κB, p53, and Notch1 signaling pathways.

Gene-specific repression of proinflammatory cytokines in stimulated human macrophages by nuclear IκBα

We have previously shown that increased nuclear accumulation of IkappaBalpha inhibits NF-kappaB activity and induces apoptosis in human leukocytes. In this study, we wanted to explore the possibility that the nucleocytoplasmic distribution of IkappaBalpha can be used as a therapeutic target for the regulation of NF-kappaB-dependent cytokine synthesis. Treatment of LPS-stimulated human U937 macrophages with an inhibitor of chromosome region maintenance 1-dependent nuclear export, leptomycin B, resulted in the increased nuclear accumulation of IkappaBalpha and inhibition of NF-kappaB DNA binding activity, caused by the nuclear IkappaBalpha-p65 NF-kappaB interaction. Surprisingly, however, whereas mRNA expression and cellular release of TNF-alpha, the beta form of pro-IL-1 (IL-1beta), and IL-6 were inhibited by the leptomycin B-induced nuclear IkappaBalpha, IL-8 mRNA expression and cellular release were not significantly affected. Analysis of in vivo recruitment of p65 NF-kappaB to NF-kappaB-regulated promoters by chromatin immunoprecipitation in U937 cells and human PBMCs indicated that although the p65 recruitment to TNF-alpha, IL-1beta, and IL-6 promoters was inhibited by the nuclear IkappaBalpha, p65 recruitment to IL-8 promoter was not repressed. Chromatin immunoprecipitation analyses using IkappaBalpha and S536 phosphospecific p65 NF-kappaB Abs demonstrated that although the newly synthesized IkappaBalpha induced by postinduction repression is recruited to TNF-alpha, IL-1beta, and IL-6 promoters but not to the IL-8 promoter, S536-phosphorylated p65 is recruited to IL-8 promoter, but not to TNF-alpha, IL-1beta, or IL-6 promoters. Together, these data indicate that the inhibition of NF-kappaB-dependent transcription by nuclear IkappaBalpha in LPS-stimulated macrophages is gene specific and depends on the S536 phosphorylation status of the recruited p65 NF-kappaB.