Kappa B-type enhancers are involved in lipopolysaccharide-mediated transcriptional activation of the tumor necrosis factor alpha gene in primary macrophages

Thalidomide inhibits lipopolysaccharide-induced tumor necrosis factor-α production via down-regulation of MyD88 expression

The effect of thalidomide on lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF)-α production was studied by using RAW 264.7 murine macrophage-like cells. Thalidomide significantly inhibited LPS-induced TNF-α production. Thalidomide prevented the activation of nuclear factor (NF)-KB by down-regulating phosphorylation of inhibitory KB factor (IKB), and IKB kinase (IKK)-α and IKK-β Moreover, thalidomide inhibited LPS-induced phosphorylation of AKT, p38 and stress-activated protein kinase (SAPK)/JNK. The expression of myeloid differentiation factor 88 (MyD88) protein and mRNA was markedly reduced in thalidomide-treated RAW 264.7 cells but there was no significant alteration in the expression of interleukin-1 receptor-associated kinase (IRAK) 1 and TNF receptor-associated factor (TRAF) 6 in the cells. Thalidomide did not affect the cell surface expression of Toll-like receptor (TLR) 4 and CD14, suggesting the impairment of intracellular LPS signalling in thalidomide-treated RAW 264.7 cells. Thalidomide significantly inhibited the TNF-α production in response to palmitoyl-Cys(RS)-2,3-di(palmitoyloxy) propyl)-Ala-Gly-OH (Pam3Cys) as a MyD88-dependent TLR2 ligand. Therefore, it is suggested that thalidomide might impair LPS signalling via down-regulation of MyD88 protein and mRNA and inhibit LPS-induced TNF-α production. The putative mechanism of thalidomide-induced MyD88 down-regulation is discussed.

HCMV IL-10 suppresses cytokine expression in monocytes through inhibition of nuclear factor-kappaB

Modulation of host immune responses is a common strategy for promoting virus persistence and avoiding clearance. Human cytomegalovirus (HCMV) is known to encode numerous immunomodulatory genes, including a homolog of the cytokine human interleukin-10 (hIL-10). While having limited sequence homology to hIL-10, cytomegalovirus IL-10 (cmvIL-10) shares many functional characteristics with the human cytokine and acts as a potent suppressor of the inflammatory immune response. The mechanism by which hIL-10 inhibits inflammatory cytokines involves a transcriptional block via inhibition of nuclear factor-kappaB (NF-kappaB) activity. To determine whether cmvIL-10 employs the same mechanism to inhibit cytokine production, the effect of cmvIL-10 on NF-kappaB signaling in monocytes was investigated. The results demonstrate that cmvIL-10 does inhibit NF-kappaB activation, as evidenced by reduced degradation of the NF-kappaB inhibitor IkappaB-alpha, and decreased transcription of the NF-kappaB-responsive genes tumor necrosis factor-alpha (TNF-alpha) and IL-1beta. These studies confirm that cmvIL-10 mediates cytokine suppression by blocking NF-kappaB transcriptional activity in human monocytes.

BCL11B enhances TCR/CD28-triggered NF-kappaB activation through up-regulation of Cot kinase gene expression in T-lymphocytes

BCL11B is a transcriptional regulator with an important role in T-cell development and leukaemogenesis. We demonstrated recently that BCL11B controls expression from the IL (interleukin)-2 promoter through direct binding to the US1 (upstream site 1). In the present study, we provide evidence that BCL11B also participates in the activation of IL-2 gene expression by enhancing NF-kappaB (nuclear factor kappaB) activity in the context of TCR (T-cell receptor)/CD28-triggered T-cell activation. Enhanced NF-kappaB activation is not a consequence of BCL11B binding to the NF-kappaB response elements or association with the NF-kappaB-DNA complexes, but rather the result of higher translocation of NF-kappaB to the nucleus caused by enhanced degradation of IkappaB (inhibitor of NF-kappaB). The enhanced IkappaB degradation in cells with increased levels of BCL11B was specific for T-cells activated through the TCR, but not for cells activated through TNFalpha (tumour necrosis factor alpha) or UV light, and was caused by increased activity of IkappaB kinase, as indicated by its increase in phosphorylation. As BCL11B is a transcription factor, we investigated whether the expression of genes upstream of IkappaB kinase in the TCR/CD28 signalling pathway was affected by increased BCL11B expression, and found that Cot (cancer Osaka thyroid oncogene) kinase mRNA levels were elevated. Cot kinase is known to promote enhanced IkappaB kinase activity, which results in the phosphorylation and degradation of IkappaB and activation of NF-kappaB. The implied involvement of Cot kinase in BCL11B-mediated NF-kappaB activation in response to TCR activation is supported by the fact that a Cot kinase dominant-negative mutant or Cot kinase siRNA (small interfering RNA) knockdown blocked BCL11B-mediated NF-kappaB activation. In support of our observations, in the present study we report that BCL11B enhances the expression of several other NF-kappaB target genes, in addition to IL-2. In addition, we provide evidence that BCL11B associates with intron 2 of the Cot kinase gene to regulate its expression.

In Vitro Effects of the Reduced Form of Coenzyme Q(10) on Secretion Levels of TNF-alpha and Chemokines in Response to LPS in the Human Monocytic Cell Line THP-1

Ubiquinol-10 (QH₂), the reduced form of Coenzyme Q₁₀ (CoQ₁₀) serves as a potent antioxidant of lipid membranes. Because many antioxidants reveal potent anti-inflammatory effects, the influence of QH₂ on lipopolysaccharide (LPS)-induced pro-inflammatory cytokines and chemokines were determined in the human monocytic cell line THP-1. Stimulation of cells with LPS resulted in a distinct release of Tumour necrosis factor-alpha (TNF-α), Macrophage inflammatory protein-1 alpha (MIP-1α), Regulated upon activation, normal T cell expressed and secreted (RANTES) and Monocyte chemotattractant protein-1 (MCP-1). The LPS-induced responses were significantly decreased by pre-incubation of cells with QH₂ to 60.27 ± 9.3% (p = 0.0009), 48.13 ± 6.93% (p = 0.0007) and 74.36 ± 7.25% (p = 0.008) for TNF-α, MIP-1α and RANTES, respectively. In conclusion, our results indicate anti-inflammatory effects of the reduced form of CoQ₁₀ on various proinflammatory cytokines and chemokines in vitro.

Tolerance induced via TLR2 and TLR4 in human dendritic cells: role of IRAK-1

Background

While dendritic cells (DCs) can induce tolerance in T cells, little is known about tolerance induction in DCs themselves. We have analysed tolerance induced in human in-vitro generated DCs by repeated stimulation with ligands for TLR4 and TLR2.

Results

DCs stimulated with the TLR4 ligand LPS did show a rapid and pronounced expression of TNF mRNA and protein. When DCs were pre-cultured for 2 days with 5 ng LPS/ml then the subsequent response to stimulation with a high dose of LPS (500 ng/ml) was strongly reduced for both TNF mRNA and protein. At the promoter level there was a reduced transactivation by the -1173 bp TNF promoter and by a construct with a tetrameric NF-κB motif. Within the signalling cascade leading to NF-κB activation we found an ablation of the IRAK-1 adaptor protein in LPS-tolerant DCs. Pre-culture of DCs with the TLR2 ligand Pam3Cys also led to tolerance with respect to TNF gene expression and IRAK-1 protein was ablated in such tolerant cells as well, while IRAK-4 protein levels were unchanged.

Conclusion

These data show that TLR-ligands can render DCs tolerant with respect to TNF gene expression by a mechanism that likely involves blockade of signal transduction at the level of IRAK-1.

UVB and proinflammatory cytokines synergistically activate TNF-alpha production in keratinocytes through enhanced gene transcription

UVB irradiation potently induces cytokines in the skin, including IL-1alpha and tumor necrosis factor-alpha (TNF-alpha). The mechanism for TNF-alpha induction in UVB-irradiated keratinocytes is not clear. In this study, we explored the effects of UVB and cytokines, alone or in combination in human keratinocytes. Keratinocytes were sham- or UVB-irradiated with 30 mJ cm(-2), and then incubated in the absence or presence of IFN-alpha2b, TNF-alpha, or IL-1alpha. UVB and IL-1alpha treatment synergistically enhanced TNF-alpha secretion and mRNA levels in human keratinocytes, similar to the findings reported previously in human fibroblasts. Exogenous recombinant TNF-alpha up-regulates its own mRNA level. However, addition of IFN-alpha2b did not show any additive effect on TNF-alpha mRNA induction. To understand the regulation of TNF-alpha mRNA by UVB, with or without IL-1alpha, we examined the transcription rate and half-life of TNF-alpha mRNA. Treatment of keratinocytes with IL-1alpha or UVB alone increased TNF-alpha gene transcription 4- to 5-fold over sham treatment, and TNF-alpha gene transcription increased 11-fold in cells treated with UVB plus IL-1alpha over sham. UVB with IL-1alpha did not enhance the half-life of TNF-alpha mRNA over that seen with UVB alone. In conclusion, TNF-alpha expression in primary keratinocytes is upregulated transcriptionally by UVB and IL-1alpha.

Echinacea-induced macrophage activation

Public interest in Echinacea is growing rapidly. Unfortunately, there is little scientific evidence to support claims of efficacy of this widely used botanical, and little information about potential mechanism of action. This study examines the ability of Echinacea to upregulate macrophage function and begins to elucidate the mechanism of Echinacea-induced macrophage activation. Murine peritoneal macrophages were cultured with E. purpurea extracts enriched for plant polysaccharide (EP). ELISA was used to measure cytokine production. MAPKs were blocked using specific inhibitors, and Western blotting used to identify phosphorylated proteins involved in signal transduction. To examine in vivo efficacy, EP was administered orally and Listeria monocytogenes given i.v. Mice were sacrificed three days post-infection to determine bacterial load in the spleen. We demonstrate that an endotoxin-free EP extract activates the innate immune response, stimulating production of IL-6, TNF, IL-12, and NO from macrophages in vitro. Along with evidence of enhanced macrophage function, we found that oral EP reduces bacterial burden during infection by Listeria monocytogenes, demonstrating its efficacy in vivo. EP initiates a signaling cascade within macrophages through both TLR4-dependent and -independent mechanisms, involving ERK, p38 and JNK, and ultimately the activation of NF-kappaB.

Chromatin profiling across the human tumour necrosis factor gene locus reveals a complex, cell type-specific landscape with novel regulatory elements

The TNF locus on chromosome 6p21 encodes a family of proteins with key roles in the immune response whose dysregulation leads to severe disease. Transcriptional regulation is important, with cell type and stimulus-specific enhancer complexes involving the proximal TNF promoter. We show how quantitative chromatin profiling across a 34 kb region spanning the TNF locus has allowed us to identify a number of novel DNase hypersensitive sites and characterize more distant regulatory elements. We demonstrate DNase hypersensitive sites corresponding to the lymphotoxin alpha (LTA) and tumour necrosis factor (TNF) promoter regions, a CpG island in exon 4 of lymphotoxin beta (LTB), the 3′ end of nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor-like 1 (NFKBIL1) and 3.4 kb upstream of LTA. These sites co-localize to highly conserved DNA sequences and show evidence of cell type specificity when lymphoblastoid, Jurkat, U937, HeLa and HEK293T cell lines are analysed using Southern blotting. For Jurkat T cells, we define histone modifications across the locus. Peaks of acetylated histone H3 and H4, together with tri-methyl K4 of histone H3, correspond to hypersensitive sites, notably in exon 4 of LTB. We provide evidence of a functional role for an intergenic DNase I hypersensitive site distal to LTA in Jurkat cells based on reporter gene analysis, with evidence of recruitment of upstream stimulatory factors (USF) transcription factors.

Insights into the regulation of TNF-alpha production in human mononuclear cells: the effects of non-specific phosphodiesterase inhibition

OBJECTIVE

The objective of this study was to determine the effect of nonspecific phosphodiesterase inhibition on transcription factor activation and tumor necrosis factor-alpha (TNF-alpha) production in lipopolysaccharide (LPS)-stimulated human mononuclear cells.

INTRODUCTION

The production of TNF-alpha following LPS stimulation is one of the key steps in bacterial sepsis and inflammation. The mechanism by which phosphodiesterase inhibition alters TNF-alpha production in the presence of LPS remains unclear.

METHODS

Human mononuclear cells were stimulated with LPS (1 microg/mL), in the presence and absence of Pentoxifylline (PTX; 20 mM), a nonspecific phosphodiesterase inhibitor. Western blotting of phosphorylated cytoplasmic I-kBalpha, nuclear factor-kB p65 (NF-kB), and nuclear cAMP-response element binding protein (CREB) was performed. DNA binding of NF-kB and CREB was verified by electrophoretic mobility shift assay. TNF-a levels were determined in the supernatant of stimulated cells in the presence and absence Protein kinase A inhibition by an enzyme-linked immunosorbent assay (ELISA).

RESULTS

PTX was demonstrated to significantly reduce cytoplasmic I-kBalpha phosphorylation, nuclear p65 phosphorylation, and the DNA binding activity of NF-kB. In contrast, PTX markedly enhanced the phosphorylation and DNA binding activity of CREB. Cells concomitantly treated with PTX and LPS secreted similar levels of TNF-a in the presence and absence Protein kinase A inhibition.

DISCUSSION

The increased level of cAMP that results from phosphodiesterase inhibition affects cytoplasmic and nuclear events, resulting in the attenuation of NF-kB and the activation of CREB transcriptional DNA binding through pathways that are partially Protein kinase A-independent.

CONCLUSION

PTX-mediated phosphodiesterase inhibition occurs partially through a Protein kinase A-independent pathway and may serve as a useful tool in the attenuation of LPS-induced inflammation.

Understanding NF-kappaB signaling via mathematical modeling

Mammalian inflammatory signaling, for which NF-kappaB is a principal transcription factor, is an exquisite example of how cellular signaling pathways can be regulated to produce different yet specific responses to different inflammatory insults. Mathematical models, tightly linked to experiment, have been instrumental in unraveling the forms of regulation in NF-kappaB signaling and their underlying molecular mechanisms. Our initial model of the IkappaB-NF-kappaB signaling module highlighted the role of negative feedback in the control of NF-kappaB temporal dynamics and gene expression. Subsequent studies sparked by this work have helped to characterize additional feedback loops, the input-output behavior of the module, crosstalk between multiple NF-kappaB-activating pathways, and NF-kappaB oscillations. We anticipate that computational techniques will enable further progress in the NF-kappaB field, and the signal transduction field in general, and we discuss potential upcoming developments.

S-adenosylmethionine inhibits lipopolysaccharide-induced gene expression via modulation of histone methylation

We previously showed that S-adenosylmethionine (SAMe) and its metabolite methylthioadenosine (MTA) blocked lipopolysaccharide (LPS)-induced tumor necrosis factor alpha (TNFalpha) expression in RAW (murine macrophage cell line) and Kupffer cells at the transcriptional level without affecting nuclear factor kappa B nuclear binding. However, the exact molecular mechanism or mechanisms of the inhibitory effect were unclear. While SAMe is a methyl donor, MTA is an inhibitor of methylation. SAMe can convert to MTA spontaneously, so the effect of exogenous SAMe may be mediated by MTA. The aim of our current work is to examine whether the mechanism of SAMe and MTA's inhibitory effect on proinflammatory mediators might involve modulation of histone methylation. In RAW cells, we found that LPS induced TNFalpha expression by both transcriptional and posttranscriptional mechanisms. SAMe and MTA treatment inhibited the LPS-induced increase in gene transcription. Using the chromatin immunoprecipitation assay, we found that LPS increased the binding of trimethylated histone 3 lysine 4 (H3K4) to the TNFalpha promoter, and this was completely blocked by either SAMe or MTA pretreatment. Similar effects were observed with LPS-mediated induction of inducible nitric oxide synthase (iNOS). LPS increased the binding of histone methyltransferases Set1 and myeloid/lymphoid leukemia to these promoters, which was unaffected by SAMe or MTA. The effects of MTA in RAW cells were confirmed in vivo in LPS-treated mice. Exogenous SAMe is unstable and converts spontaneously to MTA, which is stable and cell-permeant. Treatment with SAMe doubled intracellular MTA and S-adenosylhomocysteine (SAH) levels. SAH also inhibited H3K4 binding to TNFalpha and iNOS promoters.

CONCLUSION

The mechanism of SAMe's pharmacologic inhibitory effect on proinflammatory mediators is mainly mediated by MTA and SAH at the level of histone methylation.

Role of STAT3 in glucocorticoid-induced expression of the human IL-10 gene

In the present report we have determined the molecular mechanisms, which govern the expression of the human IL-10 gene when induced by the glucocorticoid Methyl-Prednisolone (MP). Treatment of cells with MP at 10(-6) M will readily induce IL-10 in CD19+ primary B cells and in a human B cell line. Analysis of the IL-10 promoter showed a robust 18-fold induction and demonstrated that a potential GRE motif was not required, while mutation of the -120 STAT-motif strongly reduced MP-induced trans-activation. A strong induction was also seen with a trimeric STAT-motif and over-expression of dominant-negative STAT3 could block MP induction of IL-10 mRNA. Finally, MP treatment induced binding of STAT3 to the promoter as shown by gelshift, supershift and by chromatin-immunoprecipitation. These data show that glucocorticoid-induced expression of the IL-10 gene is mediated by the transcription factor STAT3.

Uncovering a macrophage transcriptional program by integrating evidence from motif scanning and expression dynamics

Macrophages are versatile immune cells that can detect a variety of pathogen-associated molecular patterns through their Toll-like receptors (TLRs). In response to microbial challenge, the TLR-stimulated macrophage undergoes an activation program controlled by a dynamically inducible transcriptional regulatory network. Mapping a complex mammalian transcriptional network poses significant challenges and requires the integration of multiple experimental data types. In this work, we inferred a transcriptional network underlying TLR-stimulated murine macrophage activation. Microarray-based expression profiling and transcription factor binding site motif scanning were used to infer a network of associations between transcription factor genes and clusters of co-expressed target genes. The time-lagged correlation was used to analyze temporal expression data in order to identify potential causal influences in the network. A novel statistical test was developed to assess the significance of the time-lagged correlation. Several associations in the resulting inferred network were validated using targeted ChIP-on-chip experiments. The network incorporates known regulators and gives insight into the transcriptional control of macrophage activation. Our analysis identified a novel regulator (TGIF1) that may have a role in macrophage activation.

Macrophages play a vital role in host defense against infection by recognizing pathogens through pattern recognition receptors, such as the Toll-like receptors (TLRs), and mounting an immune response. Stimulation of TLRs initiates a complex transcriptional program in which induced transcription factor genes dynamically regulate downstream genes. Microarray-based transcriptional profiling has proved useful for mapping such transcriptional programs in simpler model organisms; however, mammalian systems present difficulties such as post-translational regulation of transcription factors, combinatorial gene regulation, and a paucity of available gene-knockout expression data. Additional evidence sources, such as DNA sequence-based identification of transcription factor binding sites, are needed. In this work, we computationally inferred a transcriptional network for TLR-stimulated murine macrophages. Our approach combined sequence scanning with time-course expression data in a probabilistic framework. Expression data were analyzed using the time-lagged correlation. A novel, unbiased method was developed to assess the significance of the time-lagged correlation. The inferred network of associations between transcription factor genes and co-expressed gene clusters was validated with targeted ChIP-on-chip experiments, and yielded insights into the macrophage activation program, including a potential novel regulator. Our general approach could be used to analyze other complex mammalian systems for which time-course expression data are available.

Protective effect of baicalin against lipopolysaccharide/D-galactosamine-induced liver injury in mice by up-regulation of heme oxygenase-1

Baicalin, a traditional anti-inflammatory drug, has been found to protect against liver injury in several experimental animal hepatitis models; however, the mechanisms underlying the hepatoprotective properties of baicalin are poorly understood. In the present study,we investigated the effects of baicalin on the acute liver injury in mice induced by Lipopolysaccharide/D-galactosamine (LPS/D-GalN). Baicalin (50, 150, and 300 mg/kg) was pretreated intraperitoneally (i.p.) at 2, 24, and 48 h respectively before LPS/D-GalN injected in mice. The mortality, hepatic tissue histology, hepatic tissue Tumor necrosis factor-alpha (TNF-alpha) and myeloperoxidase (MPO), plasma levels of TNF-alpha and alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were analyzed. Besides, western blotting analyses of nuclear factor kappa B (NF-kappaB) translocation and Heme oxygenase-1(HO-1) protein expression, as well as HO-1 activity were determined. The results showed that baicalin protected against LPS/D-GalN-induced liver injury, including dose-dependent alleviation of mortality and hepatic pathological damage, decrease of ALT/AST release and the rise of MPO. Baicalin reduced nuclear translocation of NF-kappa B, TNF-alpha mRNA and protein levels in hepatic tissues and plasma levels of TNF-alpha induced by LPS/D-GalN. Moreover, baicalin dose-dependently increased HO-1 protein expression and activity. Further, inhibition of HO-1 activity significantly reversed the protective effect of baicalin against LPS/D-GalN-induced liver injury. These results suggest that baicalin can effectively prevent LPS/D-GalN-induced liver injury by inhibition of NF-kappa B activity to reduce TNF-alpha production and the underlying mechanism may be related to up-regulation of HO-1 protein and activity.

poly(I:C) and LPS induce distinct IRF3 and NF-kappaB signaling during type-I IFN and TNF responses in human macrophages

Macrophages play major roles in the onset of immune responses and inflammation by inducing a variety of cytokines such as TNF and IFN-beta. The pathogen-associated molecular pattern, polyinosinic-polycytidylic acid [poly(I:C)], and LPS were used to study type-I IFN and TNF responses in human macrophages. Additionally, activation of the key signaling pathways, IFN-regulatory factor 3 (IRF3) and NF-kappaB, were studied. We found that TNF production occurred rapidly after LPS stimulation. LPS induced a strong IFN-beta mRNA response within a short time-frame, which subsided at 8 h. The IFN-stimulated genes (ISGs), ISG56 and IFN-inducible protein 10, were strongly induced by LPS. These responses were associated with NF-kappaB and IRF3 activation, as shown by IRF3 dimerization and by nuclear translocation assays. poly(I:C), on the other hand, induced a strong and long-lasting (>12 h) IFN-beta mRNA and protein response, particularly when transfected, whereas only a protracted TNF response was observed when poly(I:C) was transfected. However, these responses were induced in the absence of detectable IRF3 and NF-kappaB signaling. Thus, in human macrophages, poly(I:C) treatment induces a distinct cytokine response when compared with murine macrophages. Additionally, a robust IFN-beta response can be induced in the absence of detectable IRF3 activation.

High-mobility group box proteins modulate tumor necrosis factor-alpha expression in osteoclastogenesis via a novel deoxyribonucleic acid sequence

We have previously shown that mice lacking the TSH receptor (TSHR) exhibit osteoporosis due to enhanced osteoclast formation. The fact that this enhancement is not observed in double-null mice of TSHR and TNFalpha suggests that TNFalpha overexpression in osteoclast progenitors (macrophages) may be involved. It is unknown how TNFalpha expression is regulated in osteoclastogenesis. Here, we describe a receptor activator for nuclear factor-kappaB ligand (RANKL)-responsive sequence (CCG AGA CAG AGG TGT AGG GCC), spanning from -157 to -137 bp of the 5'-flanking region of the TNFalpha gene, which functions as a cis-acting regulatory element. We further show how RANKL treatment stimulates the high-mobility group box proteins (HMGB) HMGB1 and HMGB2 to bind the RANKL-responsive sequence and up-regulates TNFalpha transcription. Exogenous HMGB elicits the expression of cytokines, including TNFalpha, as well as osteoclast formation. Conversely, TSH inhibits the expression of HMGB and TNFalpha and the formation of osteoclasts. These results suggest that HMGB play a pivotal role in osteoclastogenesis. We also show a direct correlation between the expression of HMGB and TNFalpha and osteoclast formation in TSHR-null mice and TNFalpha-null mice. Taken together, we conclude that HMGB and TNFalpha play critical roles in the regulation of osteoclastogenesis and the remodeling of bone.

Cloning and characterization of an IKK homologue from pearl oyster, Pinctada fucata

IkappaB kinase (IKK) play central roles in cell signaling by regulating nuclear factor-kappaB (NF-kappaB) activation, which is involved in inflammatory response, proliferation, development and bone homeostasis. We report here for the first time that an IKK homologue was cloned and functionally characterized in pearl oyster, Pinctada fucata. The full-length cDNA consists of 2546bp with an ORF encoding a 737 amino acids protein. The putative pearl oyster IKK protein (Pf-IKK) possesses the characteristic organization of the mammalian IKK proteins, namely an amino-terminal kinase domain followed by a leucine zipper region and a carboxylterminal helix-loop-helix motif. Real-time PCR (RT-PCR) analysis indicated that Pf-IKK was ubiquitously expressed in pearl oyster. We also found that lipopolysaccharides (LPS) transiently stimulates IkappaBalpha degradation, but not expression levels of Pf-IKK. When transfected into NIH3T3 cells, Pf-IKK activated the expression of NF-kappaB-controlled reporter gene and induced NF-kappaB translocation, whereas the activation was greatly deduced by pyrrolidine dithiocarbamate (PDTC). We also found that overexpression of Pf-IKK increased the alkaline phosphatase (ALP) activity significantly. Based on the results and the homology to the vertebrate NF-kappaB cascade, these studies help to highlight a potentially important regulatory pathway to the study of the related functions in mollusks.

Functions of coenzyme Q10 in inflammation and gene expression

Clinical studies demonstrated the efficacy of Coenzyme Q10 (CoQ10) as an adjuvant therapeutic in cardiovascular diseases, mitochondrial myopathies and neurodegenerative diseases. More recently, expression profiling revealed that Coenzyme Q10 (CoQ10) influences the expression of several hundred genes. To unravel the functional connections of these genes, we performed a text mining approach using the Genomatix BiblioSphere. We identified signalling pathways of G-protein coupled receptors, JAK/STAT, and Integrin which contain a number of CoQ10 sensitive genes. Further analysis suggested that IL5, thrombin, vitronectin, vitronectin receptor, and C-reactive protein are regulated by CoQ10 via the transcription factor NFkappaB1. To test this hypothesis, we studied the effect of CoQ10 on the NFkappaB1-dependent pro-inflammatory cytokine TNF-alpha. As a model, we utilized the murine macrophage cell lines RAW264.7 transfected with human apolipoprotein E3 (apoE3, control) or pro-inflammatory apoE4. In the presence of 2.5 microM or 75 microM CoQ10 the LPS-induced TNF-alpha response was significantly reduced to 73.3 +/- 2.8% and 74.7 +/- 8.9% in apoE3 or apoE4 cells, respectively. Therefore, the in silico analysis as well as the cell culture experiments suggested that CoQ10 exerts anti-inflammatory properties via NFkappaB1-dependent gene expression.

Endogenous morphine/nitric oxide-coupled regulation of cellular physiology and gene expression: implications for cancer biology

Cancer is a simplistic, yet complicated, process that promotes uncontrolled growth. In this regard, this unconstrained proliferation may represent primitive phenomena whereby cellular regulation is suspended or compromised. Given the new empirical evidence for a morphinergic presence and its profound modulatory actions on several cellular processes it is not an overstatement to hypothesize that morphine may represent a key chemical messenger in the process of modulating proliferation of diverse cells. This has been recently demonstrated by the finding of a novel opiate-alkaloid selective receptor subtype in human multilineage progenitor cells (MLPC). Adding to the significance of morphinergic signaling are the findings of its presence in plant, invertebrate and vertebrate cells, which also have been shown to synthesize this messenger as well. Interestingly, we and others have shown that some cancerous tissues contain morphine. Furthermore, in medullary histolytic reticulosis, which is exemplified by cells having hyperactivity, the mu3 (mu3) opiate select receptor was not present. Thus, it would appear that morphinergic signaling has inserted itself in many processes taking a long time to evolve, including those regulating the proliferation of cells across diverse phyla.

Small molecules in stem cell self-renewal and differentiation

The use of stem cells in regenerative medicine is a promising approach to the treatment of disease and injury. Natural and synthetic small molecules have been shown to be useful chemical tools for controlling and manipulating the fates of cells. Small molecules can target signaling transduction pathways (for example, tyrosine kinase receptors) and affect DNA replication, cell differentiation, tumor metastasis and apoptosis. Stem cells share many properties with cancer cells and these similarities can provide insights to control and direct cell behavior; small molecules are already standard chemotherapeutics in the treatment of cancer. Libraries of small molecules have been examined for anticancer behavior (especially apoptosis), and, more recently, for stem cell self-renewal and differentiation capabilities in potential approaches to regenerative medicine. Differentiation therapy for cancer is based on the idea that cancer cells are undifferentiated embryonic-like cells and proposes to promote the differentiation and hence block cell proliferation. For example, retinoids have a role in stem cell differentiation to several lineages and have also been used to promote differentiation of acute promyeloic leukemic cells. Small molecules are also important tools for understanding mechanistic and developmental processes. Strategies for generating functional small molecule libraries have been outlined previously. In this review, we will look at several small molecules that have been described in the recent literature as effectors of stem cell self-renewal or differentiation as associated with the Wnt, Hedgehog or NF-kappaB pathways.

Degradation of nuclear factor kappa B during foot-and-mouth disease virus infection

We have previously shown that the leader proteinase (L(pro)) of foot-and-mouth disease virus (FMDV) interferes with the innate immune response by blocking the translation of interferon (IFN) protein and by reducing the immediate-early induction of beta IFN mRNA and IFN-stimulated genes. Here, we report that L(pro) regulates the activity of nuclear factor kappaB (NF-kappaB). Analysis of NF-kappaB-dependent reporter gene expression in BHK-21 cells demonstrated that infection with wild-type (WT) virus has an inhibitory effect compared to infection with a genetically engineered mutant lacking the leader coding region. The expression of endogenous NF-kappaB-dependent genes tumor necrosis factor alpha and RANTES is also reduced in WT virus-infected primary porcine cells. This inhibitory effect is neither the result of a decrease in the level of the mRNA of p65/RelA, a subunit of NF-kappaB, nor a block on the nuclear translocation of p65/RelA, but instead appears to be a consequence of the degradation of accumulated p65/RelA. Viral L(pro) is localized to the nucleus of infected cells, and there is a correlation between the translocation of L(pro) and the decrease in the amount of nuclear p65/RelA. By using a recombinant cardiovirus expressing L(pro), we demonstrate that the disappearance of p65/RelA takes place in the absence of any other FMDV product. The observation that L(pro) disrupts the integrity of NF-kappaB suggests a global mechanism by which FMDV antagonizes the cellular innate immune and inflammatory responses to viral infection.

The inner gel component of Aloe vera suppresses bacterial-induced pro-inflammatory cytokines from human immune cells

The present study was carried out to examine the anti-inflammatory activity of the inner leaf gel component of Aloe barbadensis Miller. A simple in vitro assay was designed to determine the effect of the inner gel on bacterial-induced pro-inflammatory cytokine production, namely TNF-alpha and IL-1 beta, from peripheral blood leukocytes stimulated with Shigella flexneri or LPS. This report describes the suppression of both cytokines with a freeze-dried inner gel powder and a commercial health drink from the same source. Comparison was made with a human monocytic cell-line (THP-1 cells) and a similar trend in responses was demonstrated.

Virulizin, a novel immunotherapy agent, stimulates TNFalpha expression in monocytes/macrophages in vitro and in vivo

Virulizin, a novel biological response modifier, has demonstrated broad antitumor efficacy in a variety of human tumor xenograft models including melanoma, pancreatic cancer, breast cancer, ovarian cancer and prostate cancer. Previous studies have demonstrated a significant role of macrophages and NK cells in the antitumor mechanism of Virulizin. Increased activity and expansion of macrophages and NK cells has been observed in mice treated with Virulizin. In the present study, the effects of Virulizin on TNFalpha expression were investigated in vitro and in vivo. CD-1 nude mice were treated with Virulizin daily for 5 days. Quantitative RT-PCR demonstrated that the level of TNFalpha mRNA increased in peritoneal macrophages isolated from Virulizin-treated mice as compared to the control group. An increase in TNFalpha protein expression was also observed, as assessed by flow cytometric analysis. Increased levels of TNFalpha mRNA were seen in human tumor xenografts following treatment of tumor-bearing mice with Virulizin. In the presence of LPS, Virulizin also stimulated TNFalpha protein secretion and mRNA expression in human monocytic U937 cells and mouse macrophage RAW264.7 cells in vitro in a time- and dose-dependent manner. U937 cells treated with Virulizin showed a significantly enhanced cytotoxicity that was eliminated upon neutralization of TNFalpha. Virulizin also induced the phosphorylation of IkappaB, suggesting that induction of TNFalpha expression by Virulizin is mediated by activation of NFkappaB. The results indicate that Virulizin-induced TNFalpha expression contributes to modulation of immune responses and antitumor activities.

Calyculin A stimulates the expression of TNF-alpha mRNA via phosphorylation of Akt in mouse osteoblastic MC3T3-E1 cells

Intracellular phosphatase activity has been recognized to play a central role in signal transduction. In the present study, we investigated the effects of calyculin A, an inhibitor of protein phosphatases, on the expression of TNF-alpha mRNA and the possible signaling pathways in mouse osteoblastic MC3T3-E1 cells. The result of semiquantitative RT-PCR showed that calyculin A increased the expression of TNF-alpha mRNA in MC3T3-E1 cells. Pre-treatment of LY294002 and Wortmannin, inhibitors of PI3K, inhibited the calyculin A-stimulated TNF-alpha mRNA expression. Western blot result disclosed that calyculin A increased the phosphorylation status of Akt at Ser473. However, U0126 and SB203580, specific inhibitor of MEK1/2 and p38MAPK, respectively, had no effect on calyculin A-stimulated expression of TNF-alpha mRNA. BAY11-7085 and CAPE, inhibitors of NF-kappaB activity, did not alter the calyculin A-stimulated TNF-alpha mRNA expression. Indirect immunofluorescent study confirmed that NF-kappaB was not translocated to the nucleus by calyculin A treatment. Our present results suggest that inhibition of phosphatase activity by calyculin A stimulate the phosphorylation of Akt at Ser473 by PI3K/Akt signaling pathway, resulting in the expression TNF-alpha mRNA.

Post-induction, Stimulus-specific Regulation of Tumor Necrosis Factor mRNA Expression

The tumor necrosis factor (TNF) gene is activated by multiple extracellular signals in a stimulus- and cell type-specific fashion. Based on the presence of kappaB-like DNA motifs in the region upstream of the TNF gene, some have proposed a direct role for NF-kappaB in lipopolysaccharide (LPS)-induced TNF gene transcription in cells of the monocyte/macrophage lineage. However, we have previously demonstrated a general and critical role for a minimal TNF promoter region bearing only one of the kappaB-like motifs, kappa3, which is bound by nuclear factor of activated T cell proteins in lymphocytes and fibroblasts in response to multiple stimuli and Ets proteins in LPS-stimulated macrophages. Here, in an effort to resolve these contrasting findings, we used a combination of site-directed mutagenesis of the TNF promoter, quantitative DNase I footprinting, and analysis of endogenous TNF mRNA production in response to multiple stimuli under conditions that inhibit NF-kappaB activation (using the proteasome inhibitor lactacystin and using cells lacking either functional NF-kappaB essential modulator, which is the IkappaB kinase regulatory subunit, or the Nemo gene itself). We find that TNF mRNA production in response to ionophore is NF-kappaB-independent, but inhibition of NF-kappaB activation attenuates virus- and LPS-induced TNF mRNA levels after initial induction. We conclude that induction of TNF gene transcription by virus or LPS does not depend upon NF-kappaB binding to the proximal promoter; rather, a stimulus-specific post-induction mechanism involving NF-kappaB, yet to be characterized, is involved in the maintenance of maximal TNF mRNA levels.

Regulation of NF-kappaB-dependent gene expression by the POU domain transcription factor Oct-1

Maintenance of the cells of the vessel wall in a quiescent state is an important aspect of normal vascular physiology. Transcriptional repressors are widely believed to regulate this process, yet the exact factors involved and the mechanism of repression are not known. Here, we report that the POU domain transcription factor Oct-1 represses the expression of E-selectin and vascular cell adhesion molecule (VCAM-1), two cytokine-inducible, NF-kappaB-dependent endothelial-leukocyte adhesion molecules that participate in the leukocyte recruitment phase of the inflammatory response. Co-transfection and microinjection studies demonstrate that Oct-1 blocks tumor necrosis factor alpha-stimulated E-selectin and VCAM-1 expression. Gene expression arrays indicate that control of tumor necrosis factor alpha-induced, NF-kappaB-dependent gene expression by Oct-1 is promoter-specific. A DNA-binding mutant of Oct-1 represses NF-kappaB-dependent reporter gene expression. Biochemically, Oct-1 interacts with p65, suggesting that Oct-1 is involved in the regulation of NF-kappaB transactivation function. NF-kappaB-dependent gene expression is more pronounced in Oct-1-deficient than in wild-type murine embryonic fibroblasts, and reintroduction of human Oct-1 abolishes these differences. Finally, the cytokine interleukin-6 induces Oct-1 gene expression, providing a biologically relevant means by which NF-kappaB-dependent gene expression can be selectively reverted by Oct-1 to quiescent levels.

Generation of inhibitory NFkappaB complexes and phosphorylated cAMP response element-binding protein correlates with the anti-inflammatory activity of complement protein C1q in human monocytes

The interaction of C1q with specific cells of the immune system induces activities, such as enhancement of phagocytosis in monocytes and stimulation of superoxide production in neutrophils. In contrast to some other monocyte activators, C1q itself does not induce pro-inflammatory cytokine production, but rather inhibits the lipopolysaccharide (LPS)-stimulated induction of certain pro-inflammatory cytokines and induces expression of interleukin-10. To investigate the molecular mechanism by which C1q exerts this effect on gene expression, the influence of C1q on the activation of transcription factors of the NFkappaB family and cAMP response element-binding protein (CREB) was assessed. C1q treatment increased kappaB binding activity in freshly isolated human monocytes in a time-dependent fashion as assessed by electrophoretic mobility shift assays. In antibody supershift experiments, anti-p50 antibody supershifted the C1q-induced NFkappaB complex, whereas anti-p65 antibody had little effect, suggesting that C1q induced the translocation of NFkappaB p50p50 homodimers. This is in contrast to the dominant induction of p65 containing complexes in parallel monocyte cultures stimulated with LPS. C1q treatment also induced cAMP response element (CRE)-binding activity as demonstrated by electrophoretic mobility shift assay, increased phosphorylation of CREB, and induction of CRE driven gene expression. In contrast, CREB activation was not detected in LPS-treated monocytes. These results suggest that C1q may modulate the cytokine profile expressed in response to inflammatory stimuli (e.g. LPS), by triggering inhibitory and/or competing signals. Because C1q and other defense collagens have been shown to enhance clearance of apoptotic cells, this regulatory pathway may be beneficial in avoiding autoimmunity and/or resolving inflammation.

MnTBAP, a synthetic metalloporphyrin, inhibits production of tumor necrosis factor-α in lipopolysaccharide-stimulated RAW 264.7 macrophages cells via inhibiting oxidative stress-mediating p38 and SAPK/JNK signaling

Antioxidants are able to inhibit inflammatory gene expression in response to lipopolysaccharide via down-regulating generation of intracellular reactive oxygen species (ROS) as second messengers. The effect of manganese (III) tetrakis (4-benzoic acid) porphyrin (MnTBAP), a synthetic metalloporphyrin with antioxidant activity, on tumor necrosis factor (TNF)-alpha production in lipopolysaccharide-stimulated RAW 264.7 macrophage cells was examined. MnTBAP prevented the generation of intracellular ROS in lipopolysaccharide-stimulated RAW 264.7 cells and further inhibited lipopolysaccharide-induced TNF-alpha production. MnTBAP exclusively prevented the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and stress-activated protein kinase (SAPK/JNK) whereas it did not affect the phosphorylation and activation of nuclear factor-kappaB and extracellular signal regulated kinase 1/2. MnTBAP was suggested to inhibit lipopolysaccharide-induced TNF-alpha production by the prevention of intracellular ROS generation and subsequent inactivation of p38 MAPK and SAPK/JNK.

Increased myeloid cell responses to M-CSF and RANKL cause bone loss and inflammation in SH3BP2 "cherubism" mice

While studies of the adaptor SH3BP2 have implicated a role in receptor-mediated signaling in mast cells and lymphocytes, they have failed to identify its function or explain why SH3BP2 missense mutations cause bone loss and inflammation in patients with cherubism. We demonstrate that Sh3bp2 "cherubism" mice exhibit trabecular bone loss, TNF-alpha-dependent systemic inflammation, and cortical bone erosion. The mutant phenotype is lymphocyte independent and can be transferred to mice carrying wild-type Sh3bp2 alleles through mutant fetal liver cells. Mutant myeloid cells show increased responses to M-CSF and RANKL stimulation, and, through mechanisms of increased ERK 1/2 and SYK phosphorylation/activation, they form macrophages that express high levels of TNF-alpha and osteoclasts that are unusually large. M-CSF and RANKL stimulation of myeloid cells that overexpress wild-type SH3BP2 results in similar large osteoclasts. This indicates that the mutant phenotype reflects gain of SH3BP2 function and suggests that SH3BP2 is a critical regulator of myeloid cell responses to M-CSF and RANKL stimulation.

Effects of Coenzyme Q10 on TNF-alpha secretion in human and murine monocytic cell lines

Studies in humans and cell culture as well as bioinformatics suggested that Coenzyme Q(10) (CoQ10) functions as an anti-inflammatory molecule. Here we studied the influence of CoQ10 (Kaneka Q10) on secretion of the pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) by using the human and murine monocytic cell lines THP-1 and RAW264.7 expressing human apolipoprotein E3 (apoE3) or pro-inflammatory apoE4. Incubation of cells with physiological (0.1-10 microM) and supra-physiological (> 10 to < 100 microM) concentrations of CoQ10 led to an intracellular accumulation of its reduced form without any cytotoxic effects. Stimulation of cell models with lipopolysaccharide (LPS) resulted in a substantially release of TNF-alpha. When THP-1 cells were pre-incubated with 10 microM CoQ10, the LPS-induced TNF-alpha release was significantly decreased to 72 +/- 32%. This effect is similar to those obtained by 10 microM N-Acetyl-Cysteine, a well known reference antioxidant. In RAW264.7-apoE3 and -apoE4 cells, significant reductions of LPS-induced TNF-alpha secretion to 73.3 +/- 2.8% and 74.7 +/- 8.9% were found with 2.5 microM and 75 microM CoQ10, respectively. In conclusion, CoQ10 has moderate anti-inflammatory effects in two monocytic cell lines which could be mediated by its antioxidant activity.

Pleiotropic functions of TNF-alpha determine distinct IKKbeta-dependent hepatocellular fates in response to LPS

TNF-alpha influences morbidity and mortality during the course of endotoxemia. However, the complex pleiotropic functions of TNF-alpha remain poorly understood. We evaluated how hepatic induction of NF-kappaB and TNF-alpha influence survival and hepatocellular death in a lethal murine model of endotoxic shock. Using dominant-negative viral vectors to inhibit the IKK complex, we demonstrate through this study that the liver is a major source of TNF-alpha during the course of lethal endotoxemia and that IKKbeta (but not IKKalpha) is predominantly responsible for activating NF-kappaB and TNF-alpha in the liver after LPS administration. Using TNF-alpha knockout mice and hepatic-specific inhibition of IKKbeta, we demonstrate that the status of TNF-alpha and NF-kappaB balances necrotic and apoptotic fates of hepatocytes in the setting of endotoxemia. In the presence of TNF-alpha, inhibiting hepatic IKKbeta resulted in increased survival, reduced serum proinflammatory cytokines, and reduced hepatocyte necrosis in response to a lethal dose of endotoxin. In contrast, inhibiting hepatic IKKbeta in TNF-alpha knockout mice resulted in decreased survival and increased caspase 3-mediated hepatocyte apoptosis after endotoxin challenge, despite a reduced proinflammatory cytokine response. In the presence of TNF-alpha, NF-kappaB-dependent hepatocellular necrosis predominated, while in the absence of TNF-alpha, NF-kappaB primarily influenced apoptotic fate of hepatocytes. Changes in JNK phosphorylation after LPS challenge were also dynamically affected by both IKKbeta and TNF-alpha; however, this pathway could not solely explain the differential outcomes in hepatocellular fates. In conclusion, our studies demonstrate that induction of NF-kappaB and TNF-alpha balances protective (antiapoptotic) and detrimental (proinflammatory) pathways to determine hepatocellular fates during endotoxemia.

Tristetraprolin (TTP)-14-3-3 complex formation protects TTP from dephosphorylation by protein phosphatase 2a and stabilizes tumor necrosis factor-alpha mRNA

Tumor necrosis factor (TNF)-alpha is a major cytokine produced by alveolar macrophages in response to pathogen-associated molecular patterns such as lipopolysaccharide. TNF-alpha secretion is regulated at both transcriptional and post-transcriptional levels. Post-transcriptional regulation occurs by modulation of TNF-alpha mRNA stability via the binding of tristetraprolin (TTP) to the adenosine/uridine-rich elements found in the 3'-untranslated region of the TNF-alpha transcript. Phosphorylation plays important roles in modulating mRNA stability, because activation of p38 MAPK by lipopolysaccharide stabilizes TNF-alpha mRNA. We hypothesized that the protein phosphatase 2A (PP2A) regulates this signaling pathway. Our results show that inhibition of PP2A by okadaic acid or small interference RNA significantly enhanced the stability of TNF-alpha mRNA. This result was associated with increased phosphorylation of p38 MAPK and MAPK-activated kinase 2 (MK-2). PP2A inhibition increased TTP phosphorylation and enhanced complex formation with chaperone protein 14-3-3. TTP physically interacted with PP2A in transfected mammalian cells. A functional consequence of TTP-14-3-3 complex formation appeared to be protection of TTP from dephosphorylation by inhibition of the binding of PP2A to phosphorylated TTP. Mutation of the MK-2 phosphorylation sites of TTP did not influence TNF-alpha adenosine/uridine-rich element binding and did not alter the increased TNF-alpha 3'-untranslated region-dependent luciferase activity induced by PP2A-small interference RNA silencing. Our data indicate that, although phosphorylation stabilizes TNF-alpha mRNA, PP2A regulates the mRNA stability by modulating the phosphorylation state of members of the p38/MK-2/TTP pathway.

Current insights into the regulation of programmed cell death by NF-kappaB

The nuclear factor-kappaB (NF-kappaB) transcription factors have emerged as major regulators of programmed cell death (PCD) whether via apoptosis or necrosis. In this context, NF-kappaB's activity has important ramifications for normal tissue development, homoeostasis and the physiological functions of various cell systems including the immune, hepatic, epidermal and nervous systems. However, improper regulation of PCD by NF-kappaB can have severe pathologic consequences, ranging from neurodegeneration to cancer, where its activity often precludes effective therapy. Although NF-kappaB generally protects cells by inducing the expression genes encoding antiapoptotic and antioxidizing proteins, its role in apoptosis and necrosis can vary markedly in different cell contexts, and NF-kappaB can sensitize cells to death-inducing stimuli in some instances. This article describes our current knowledge of the role of NF-kappaB in apoptosis and necrosis, and focuses on the many advances since we last reviewed this rapidly evolving topic in Oncogene 3 years ago. There has been substantial progress in understanding NF-kappaB's mode of action in apoptosis and necrosis and the mechanisms that regulate its anti- vs proapoptotic activities. These recent developments shed new light on the role of NF-kappaB in many disease conditions including tumor development, tumor progression and anticancer treatment.

Modulation of cytokine secretion by pentacyclic triterpenes from olive pomace oil in human mononuclear cells

Olive pomace oil, also known as "orujo" olive oil, is a blend of refined-pomace oil and virgin olive oil, fit for human consumption. Maslinic acid, oleanolic acid, erythrodiol, and uvaol are pentacyclic triterpenes, found in the non-glyceride fraction of orujo oil, which have previously been reported to have anti-inflammatory properties. In the present work, we investigated the effect of these minor components on pro-inflammatory cytokine production by human peripheral blood mononuclear cells in six different samples. Uvaol, erythrodiol, and oleanolic acid significantly decreased IL-1beta and IL-6 production in a dose-dependent manner. All three compounds significantly reduced TNF-alpha production at 100microM; however, at 10microM, uvaol and oleanolic acid enhanced the generation of TNF-alpha. In contrast, maslinic acid did not significantly alter the concentration of those cytokines, with the exception of a slight inhibitory effect at 100microM. All four triterpenes inhibited production of I-309, at 50microM and 100microM. However, uvaol enhanced I-309 production at 10microM. The triterpenic dialcohols had a similar effect on MIG production. In conclusion, this study demonstrates that pentacyclic triterpenes in orujo oil exhibit pro- and anti-inflammatory properties depending on chemical structure and dose, and may be useful in modulating the immune response.

-238 G>A polymorphism of tumor necrosis factor alpha gene (TNFA) is associated with alcoholic liver cirrhosis in alcoholic Spanish men

BACKGROUND

The tumor necrosis factor alpha gene (TNFA) has been recently associated to alcoholic steatohepatitis. We have analyzed the distribution of genotypes and alleles of two polymorphisms at positions -238 and -308 in the promoter region of the TNFA gene in a Spanish male population of alcoholics with and without alcoholic liver cirrhosis.

METHODS

149 male alcoholics (84 without alcoholic liver disease, and 65 with alcoholic liver cirrhosis) and 90 control subjects were included. Genotyping was done by polymerase chain reaction and digestion with restriction enzymes.

RESULTS

No significant differences in the distribution of genotypes and alleles of the -308 TNFA gene polymorphism were observed between alcoholics and non-alcoholics, or between alcoholics with liver cirrhosis and those without liver disease. However, we found an association between the -238 TNFA polymorphism and alcoholic liver cirrhosis; the frequency of the heterozygous genotype being significantly higher in alcoholics with cirrhosis than in those without liver damage.

CONCLUSION

The -238 TNFA-A allele is associated with a higher risk to develop alcoholic liver cirrhosis. This polymorphism could be considered as a genetic factors that confer predisposition to suffer liver cirrhosis in the alcoholic population of Castile and León.

Nuclear factor-kappab (NF-kappaB): an unsuspected major culprit in the pathogenesis of endometriosis that is still at large?

Endometriosis, defined as the ectopic presence of endometrial glandular and stromal cells outside the uterine cavity, is a common benign gynecological disorder with an enigmatic pathogenesis. Many genes and gene products have been reported to be altered in endometriosis, yet some of them may not be major culprits but merely unwitting accomplices or even innocent bystanders. Therefore, the identification and apprehension of major culprits in the pathogenesis of endometriosis are crucial to the understanding of the pathogenesis and would help to develop better therapeutics for endometriosis. Although so far NF-kappaB only has left few traces of incriminating fingerprints, several lines of investigation suggest that NF-kappaB, a pivotal pro-inflammatory transcription factor, could promote and maintain endometriosis. Various inflammatory agents, growth factors, and oxidative stress activate NF-kappaB. NF-kappaB proteins themselves and proteins regulated by them have been linked to cellular transformation, proliferation, apoptosis, angiogenesis, and invasion. Interestingly, all existing and nearly all investigational medications for endometriosis appear to act through suppression of NF-kappaB activation. In endometriotic cells, NF-kappaB appears to be constitutively activated, and suppression of NF-kappaB activity by NF-kappaB inhibitors or proteasome inhibitors suppresses proliferation in vitro. Viewing NF-kappaB as a major culprit, an autoregulatory loop model can be postulated, which is consistent with existing data and, more importantly, can explain several puzzling phenomena that are otherwise difficult to interpret based on prevailing theories. This view has immediate and important implications for novel ways to treat endometriosis. Further research is warranted to precisely delineate the roles of NF-kappaB in the pathogenesis of endometriosis and to indict and convict its aiders and abettors.

Rhinovirus replication in human macrophages induces NF-kappaB-dependent tumor necrosis factor alpha production

Rhinoviruses (RV) are the major cause of acute exacerbations of asthma and chronic obstructive pulmonary disease (COPD). Rhinoviruses have been shown to activate macrophages, but rhinovirus replication in macrophages has not been reported. Tumor necrosis factor alpha (TNF-alpha) is implicated in the pathogenesis of acute exacerbations, but its cellular source and mechanisms of induction by virus infection are unclear. We hypothesized that rhinovirus replication in human macrophages causes activation and nuclear translocation of NF-kappaB, leading to TNF-alpha production. Using macrophages derived from the human monocytic cell line THP-1 and from primary human monocytes, we demonstrated that rhinovirus replication was productive in THP-1 macrophages, leading to release of infectious virus into supernatants, but was limited in monocyte-derived macrophages, likely due to type I interferon production, which was robust in monocyte-derived but deficient in THP-1-derived macrophages. Similar to bronchial epithelial cells, only small numbers of cells supported complete virus replication. We demonstrated RV-induced activation of NF-kappaB and colocalization of p65/NF-kappaB nuclear translocation with virus replication in both macrophage types. The infection induced TNF-alpha release in a time- and dose-dependent, RV serotype- and receptor-independent manner and was largely (THP-1 derived) or completely (monocyte derived) dependent upon virus replication. Finally, we established the requirement for NF-kappaB but not p38 mitogen-activated protein kinase in induction of TNF-alpha. These data suggest RV infection of macrophages may be an important source of proinflammatory cytokines implicated in the pathogenesis of exacerbations of asthma and COPD. They also confirm inhibition of NF-kappaB as a promising target for development of new therapeutic intervention strategies.

Captopril suppresses inflammation in endotoxin-induced uveitis in rats

Captopril is an inhibitor of angiotensin-converting enzyme (ACE) that is largely used in the treatment of cardiovascular diseases. Several previous studies have demonstrated that captopril exhibits a wide variety of biological activities, including an anti-inflammatory action, on which we focused our attention. The aim of the present study was to investigate the efficacy of captopril on endotoxin induced uveitis (EIU) in rats. We investigated its effect upon cellular infiltration and protein leakage, as well as on the concentration of tumor necrosis factor-alpha (TNF-alpha), nitric oxide (NO), prostaglandin E2 (PGE2), monocyte chemoattractant protein-1 (MCP-1) in the anterior chamber. In addition, we checked its effect on activation of nuclear factor kappa B (NF-kappaB) in iris and ciliary body (ICB) cells in vivo. EIU was induced in male Lewis rats by a footpad injection of lipopolysaccharide (LPS). One hour after the LPS inoculation, either 1mg/kg, 10mg/kg or 100mg/kg captopril were injected intravenously. 24h later, the aqueous humor was collected from both eyes, and the number of infiltrating cells and protein concentration in the aqueous humor were determined. Levels of TNF-alpha, PGE2, NO and MCP-1 were determined by enzyme-linked immunosorbent assay. On some eyes, after enucleation, immunohistochemical staining with a monoclonal antibody against activated NF-kappaB was performed. Captopril treatment significantly decreased the inflammatory cells infiltration, the level of protein, concentrations of TNF-alpha, PGE2, NO and MCP-1 in the aqueous humor. The number of activated NF-kappaB-positive cells was lower in ICB of the rats treated with captopril 3h after the LPS injection. The present results indicate that captopril suppresses the inflammation in EIU by inhibiting the NF-kappaB-dependent pathway and the subsequent production of pro-inflammatory mediators.

Ca2+- and protein kinase C-dependent signaling pathway for nuclear factor-kappaB activation, inducible nitric-oxide synthase expression, and tumor necrosis factor-alpha production in lipopolysaccharide-stimulated rat peritoneal macrophages

Lipopolysaccharide (LPS)-activated macrophages are pivotal in innate immunity. With LPS treatment, extracellular signals are transduced into macrophages via Toll-like receptor 4 and induce inflammatory mediator production by activating signaling pathways, including the nuclear factor-kappaB (NF-kappaB) pathway and the mitogen-activated protein kinase (MAPK) pathway. However, the mechanisms by which the intracellular free Ca2+ concentration ([Ca2+]i) increases and protein kinase C (PKC) is activated remain unclear. Therefore, we investigated the signaling pathway for Ca2+- and PKC-dependent NF-kappaB activation, inducible nitric-oxide synthase expression, and tumor necrosis factor-alpha (TNF-alpha) production in LPS-stimulated rat peritoneal macrophages. The results demonstrated that the LPS-induced transient [Ca2+]i increase is due to Ca2+ release and influx. Extracellular and intracellular Ca2+ chelators inhibited phosphorylation of PKCalpha and PKCbeta. A PKCbeta-specific and a general PKC inhibitor blunted phosphorylation of serine in mitogen-activated/extracellular signal-regulated kinase kinase kinase (MEKK) 1. Moreover, a MEKK inhibitor reduced activation of inhibitorykappaB kinase and NF-kappaB. Upstream of the [Ca2+]i increase, a protein-tyrosine kinase inhibitor reduced phosphorylation of phospholipase C (PLC) gamma. Furthermore, a PLC inhibitor eliminated the transient [Ca2+]i increase and decreased the amount of activated PKC. Therefore, these results revealed the following roles of Ca2+ and PKC in the signaling pathway for NF-kappaB activation in LPS-stimulated macrophages. After LPS treatment, protein-tyrosine kinase mediates PLCgamma1/2 phosphorylation, which is followed by a [Ca2+]i increase. Several PKCs are activated, and PKCbeta regulates phosphorylation of serine in MEKK1. Moreover, MEKKs regulate inhibitory kappaB kinase activation. Sequentially, NF-kappaB is activated, and inducible nitric-oxide synthase and tumor necrosis factor-alpha production is promoted.

Genetic analysis of host resistance: Toll-like receptor signaling and immunity at large

Classical genetic methods, driven by phenotype rather than hypotheses, generally permit the identification of all proteins that serve nonredundant functions in a defined biological process. Long before this goal is achieved, and sometimes at the very outset, genetics may cut to the heart of a biological puzzle. So it was in the field of mammalian innate immunity. The positional cloning of a spontaneous mutation that caused lipopolysaccharide resistance and susceptibility to Gram-negative infection led directly to the understanding that Toll-like receptors (TLRs) are essential sensors of microbial infection. Other mutations, induced by the random germ line mutagen ENU (N-ethyl-N-nitrosourea), have disclosed key molecules in the TLR signaling pathways and helped us to construct a reasonably sophisticated portrait of the afferent innate immune response. A still broader genetic screen--one that detects all mutations that compromise survival during infection--is permitting fresh insight into the number and types of proteins that mammals use to defend themselves against microbes.

Novel lymphotoxin alpha (LTalpha) knockout mice with unperturbed tumor necrosis factor expression: reassessing LTalpha biological functions

Lymphotoxin alpha (LTalpha) can exist in soluble form and exert tumor necrosis factor (TNF)-like activity through TNF receptors. Based on the phenotypes of knockout (KO) mice, the physiological functions of LTalpha and TNF are considered partly redundant, in particular, in supporting the microarchitecture of the spleen and in host defense. We exploited Cre-LoxP technology to generate a novel neomycin resistance gene (neo) cassette-free LTalpha-deficient mouse strain (neo-free LTalpha KO [LTalphaDelta/Delta]). Unlike the "conventional" LTalpha-/- mice, new LTalphaDelta/Delta animals were capable of producing normal levels of systemic TNF upon lipopolysaccharide (LPS) challenge and were susceptible to LPS/D-galactosamine (D-GalN) toxicity. Activated neutrophils, monocytes, and macrophages from LTalphaDelta/Delta mice expressed TNF normally at both the mRNA and protein levels as opposed to conventional LTalpha KO mice, which showed substantial decreases in TNF. Additionally, the spleens of the neo-free LTalpha KO mice displayed several features resembling those of LTbeta KO mice rather than conventional LTalpha KO animals. The phenotype of the new LTalphaDelta/Delta mice indicates that LTalpha plays a smaller role in lymphoid organ maintenance than previously thought and has no direct role in the regulation of TNF expression.

Specific recognition of apoptotic cells reveals a ubiquitous and unconventional innate immunity

The purpose of physiological cell death is the noninflammatory clearance of cells that have become inappropriate or nonfunctional. Consistent with this function, the recognition of apoptotic cells by professional phagocytes, including macrophages and dendritic cells, triggers a set of potent anti-inflammatory responses manifest on multiple levels. The immediate-early inhibition of proinflammatory cytokine gene transcription in the phagocyte is a proximate consequence of recognition of the apoptotic corpse, independent of subsequent engulfment and soluble factor involvement. Here, we show that recognition is linked to a characteristic signature of responses, including MAPK signaling events and the ablation of proinflammatory transcription and cytokine secretion. Specific recognition and response occurs without regard to the origin (species, tissue type, or suicidal stimulus) of the apoptotic cell and does not involve Toll-like receptor signaling. These features mark this as an innate immunity fundamentally distinct from the discrimination of "self" versus "other" considered to be the hallmark of conventional immunity. This profound unconventional innate immune discrimination of effete from live cells is as ubiquitous as apoptotic cell death itself, manifest by professional and nonprofessional phagocytes and nonphagocytic cell types alike. Innate apoptotic immunity provides an intrinsic anti-inflammatory circuit that attenuates proinflammatory responses dynamically and may act systemically as a powerful physiological regulator of immunity.

Autocrine tumor necrosis factor alpha links endoplasmic reticulum stress to the membrane death receptor pathway through IRE1alpha-mediated NF-kappaB activation and down-regulation of TRAF2 expression

NF-kappaB is critical for determining cellular sensitivity to apoptotic stimuli by regulating both mitochondrial and death receptor apoptotic pathways. The endoplasmic reticulum (ER) emerges as a new apoptotic signaling initiator. However, the mechanism by which ER stress activates NF-kappaB and its role in regulation of ER stress-induced cell death are largely unclear. Here, we report that, in response to ER stress, IKK forms a complex with IRE1alpha through the adapter protein TRAF2. ER stress-induced NF-kappaB activation is impaired in IRE1alpha knockdown cells and IRE1alpha(-/-) MEFs. We found, however, that inhibiting NF-kappaB significantly decreased ER stress-induced cell death in a caspase-8-dependent manner. Gene expression analysis revealed that ER stress-induced expression of tumor necrosis factor alpha (TNF-alpha) was IRE1alpha and NF-kappaB dependent. Blocking TNF receptor 1 signaling significantly inhibited ER stress-induced cell death. Further studies suggest that ER stress induces down-regulation of TRAF2 expression, which impairs TNF-alpha-induced activation of NF-kappaB and c-Jun N-terminal kinase and turns TNF-alpha from a weak to a powerful apoptosis inducer. Thus, ER stress induces two signals, namely TNF-alpha induction and TRAF2 down-regulation. They work in concert to amplify ER-initiated apoptotic signaling through the membrane death receptor.

Nucleotide analogues with immunobiological properties: 9-[2-Hydroxy-3-(phosphonomethoxy)propyl]-adenine (HPMPA), -2,6-diaminopurine (HPMPDAP), and their N6-substituted derivatives

Newly developed acyclic nucleoside phosphonates, derivatives of adenine and 2,6-diaminopurine bearing the 2-hydroxy-3-(phosphonomethoxy)propyl (HPMP) moiety at the N9-side chain (i.e., HPMPA and HPMPDAP, respectively) were screened for in vitro immunobiological activity, using mouse resident peritoneal macrophages and splenocytes. Both HPMPA and HPMPDAP augmented the interferon-gamma-triggered production of NO as well as expression of inducible nitric oxide synthase (iNOS) mRNA in macrophages. HPMPDAP activated secretion of tumor necrosis factor-alpha (TNF-alpha), chemokines "regulated-upon-activation, normal T cell expressed and secreted" (RANTES) and macrophage inflammatory protein-1alpha (MIP-1alpha), and marginally also secretion of interleukin-10 (IL-10) in both macrophages and splenocytes. The HPMPA, less prominently than HPMPDAP, elevated only secretion of RANTES and TNF-alpha. The compounds also activated secretion of TNF-alpha (HPMPDAP > HPMPA) in human peripheral blood mononuclear cells (PBMC). Distinct N6-substituted derivatives, i.e., N6-dimethyl-, N6-cyclopropyl-, N6-piperidin-1-yl-, N6-(2-methoxyethyl)-, N6-(2-hydroxyethyl)-, N6-allyl- and N6-2-(dimethylamino)ethyl-HPMPA/HPMPDAP as well as 6-thio and 6-hydroxy derivatives usually showed loss of the activity compared to the parent compounds. The immunomodulatory effects were found to be at least in part dependent on P1 purinoreceptors, and mediated by transcriptional factor nuclear factor-kappaB.

Relative corticosteroid insensitivity of peripheral blood mononuclear cells in severe asthma

RATIONALE AND OBJECTIVES

Patients with severe asthma have a poor therapeutic response to corticosteroid therapy, and corticosteroid responsiveness cannot be easily measured in these patients. We hypothesized that this poor response is associated with a reduced effect of corticosteroids to inhibit cytokine release from activated peripheral blood mononuclear cells (PBMCs).

METHODS

Patients with severe asthma were defined by American Thoracic Society criteria. We compared the suppression of LPS-induced cytokine release (monocyte chemotactic protein-1 [MCP-1], macrophage inflammatory protein [MIP] 1alpha, RANTES, tumor necrosis factor alpha, interleukin 1beta (IL-1beta), IL-8, IFN-gamma, IL-6, IL-10, and granulocyte-macrophage colony-stimulating factor [GM-CSF]) by dexamethasone from PBMCs of patients with severe asthma (n = 16), patients with nonsevere asthma (n = 19), and normal volunteers (n = 10).

RESULTS

There was no difference in baseline spontaneous or stimulated release of these cytokines among groups. LPS-induced release of 10 cytokines was less suppressed by dexamethasone (10(-6) M) in patients with severe asthma compared with patients with nonsevere asthma, with statistical significance achieved for IL-1beta (p < 0.03), IL-8 (p < 0.03), and MIP-1alpha (p < 0.003), and borderline significance for IL-6 (p = 0.054). There was less difference between the two groups for dexamethasone at 10(-8) M. Nuclear histone deacetylase (HDAC) and histone acetyltransferase activities were reduced in patients with severe asthma compared with patients with nonsevere asthma (p < 0.01). HDAC activity reduction correlated directly to the degree of steroid insensitivity of GM-CSF (r = 0.57, p < 0.01) and IFN-gamma (r = 0.56, p < 0.05) release. Reduction in histone acetyltransferase activity related to corticosteroid use rather than asthma severity.

CONCLUSIONS

Patients with severe asthma have diminished corticosteroid sensitivity of PBMCs when compared with patients with nonsevere asthma, associated with a reduction in HDAC activity that parallels the impaired corticosteroid sensitivity.

Calcium-dependent expression of TNF-α in neural cells is mediated by the calcineurin/NFAT pathway

We report induction of TNF-alpha via the calcium/calcineurin/NFAT pathway in PC12 neural cells. In PC12, expression of TNF-alpha mRNA, protein and TNF-alpha gene promoter activity was induced by co-stimulation with phorbol ester and either calcium ionophore A23187 or the L-type Voltage Gated Calcium Channel agonist Bay K 8644. Pre-treatment with calcineurin inhibitors CsA or FK506 inhibited the dominant calcium-dependent component of this induction, limiting it to the level achieved with phorbol ester alone. Promoter activation by Bay was abolished by nifedipine, a specific inhibitor of L-type Voltage Gated Calcium Channels. Exogenous NFAT protein transactivated the TNF-alpha promoter, and the peptide VIVIT-a specific inhibitor of calcineurin/NFAT binding-blocked calcium-inducible transactivation of the TNF-alpha promoter. Given proposed functions of TNF-alpha in spatial learning, memory and the pathogenesis of neurodegenerative diseases, the data presented suggest an important role for calcineurin/NFAT signaling in these key neurological processes.