The regulation of the human tumor necrosis factor alpha promoter region in macrophage, T cell, and B cell lines

Regulation of Cyclooxygenase-2 Expression in Human T Cells by Glucocorticoid Receptor-Mediated Transrepression of Nuclear Factor of Activated T Cells

Cyclooxygenase (COX) is the key enzyme in prostanoid synthesis from arachidonic acid (AA). Two isoforms, named COX-1 and COX-2, are expressed in mammalian tissues. The expression of COX-2 isoform is induced by several stimuli including cytokines and mitogens, and this induction is inhibited by glucocorticoids (GCs). We have previously shown that the transcriptional induction of COX-2 occurs early after T cell receptor (TCR) triggering, suggesting functional implications of this enzyme in T cell activation. Here, we show that dexamethasone (Dex) inhibits nuclear factor of activated T cells (NFAT)-mediated COX-2 transcriptional induction upon T cell activation. This effect is dependent on the presence of the GC receptor (GR), but independent of a functional DNA binding domain, as the activation-deficient GRLS7 mutant was as effective as the wild-type GR in the repression of NFAT-dependent transcription. Dex treatment did not disturb NFAT dephosphorylation, but interfered with activation mediated by the N-terminal transactivation domain (TAD) of NFAT, thus pointing to a negative cross-talk between GR and NFAT at the nuclear level. These results unveil the ability of GCs to interfere with NFAT activation and the induction of pro-inflammatory genes such as COX-2, and explain some of their immunomodulatory properties in activated human T cells.

SRI-42127, a novel small molecule inhibitor of the RNA regulator HuR, potently attenuates glial activation in a model of lipopolysaccharide-induced neuroinflammation

Glial activation with the production of pro-inflammatory mediators is a major driver of disease progression in neurological processes ranging from acute traumatic injury to chronic neurodegenerative diseases such as amyotrophic lateral sclerosis and Alzheimer's disease. Posttranscriptional regulation is a major gateway for glial activation as many mRNAs encoding pro-inflammatory mediators contain adenine- and uridine-rich elements (ARE) in the 3' untranslated region which govern their expression. We have previously shown that HuR, an RNA regulator that binds to AREs, plays a major positive role in regulating inflammatory cytokine production in glia. HuR is predominantly nuclear in localization but translocates to the cytoplasm to exert a positive regulatory effect on RNA stability and translational efficiency. Homodimerization of HuR is necessary for translocation and we have developed a small molecule inhibitor, SRI-42127, that blocks this process. Here we show that SRI-42127 suppressed HuR translocation in LPS-activated glia in vitro and in vivo and significantly attenuated the production of pro-inflammatory mediators including IL1β, IL-6, TNF-α, iNOS, CXCL1, and CCL2. Cytokines typically associated with anti-inflammatory effects including TGF-β1, IL-10, YM1, and Arg1 were either unaffected or minimally affected. SRI-42127 suppressed microglial activation in vivo and attenuated the recruitment/chemotaxis of neutrophils and monocytes. RNA kinetic studies and luciferase studies indicated that SRI-42127 has inhibitory effects both on mRNA stability and gene promoter activation. In summary, our findings underscore HuR's critical role in promoting glial activation and the potential for SRI-42127 and other HuR inhibitors for treating neurological diseases driven by this activation.

Current Genetic Survey and Potential Gene-Targeting Therapeutics for Neuromuscular Diseases

Neuromuscular diseases (NMDs) belong to a class of functional impairments that cause dysfunctions of the motor neuron-muscle functional axis components. Inherited monogenic neuromuscular disorders encompass both muscular dystrophies and motor neuron diseases. Understanding of their causative genetic defects and pathological genetic mechanisms has led to the unprecedented clinical translation of genetic therapies. Challenged by a broad range of gene defect types, researchers have developed different approaches to tackle mutations by hijacking the cellular gene expression machinery to minimize the mutational damage and produce the functional target proteins. Such manipulations may be directed to any point of the gene expression axis, such as classical gene augmentation, modulating premature termination codon ribosomal bypass, splicing modification of pre-mRNA, etc. With the soar of the CRISPR-based gene editing systems, researchers now gravitate toward genome surgery in tackling NMDs by directly correcting the mutational defects at the genome level and expanding the scope of targetable NMDs. In this article, we will review the current development of gene therapy and focus on NMDs that are available in published reports, including Duchenne Muscular Dystrophy (DMD), Becker muscular dystrophy (BMD), X-linked myotubular myopathy (XLMTM), Spinal Muscular Atrophy (SMA), and Limb-girdle muscular dystrophy Type 2C (LGMD2C).

Membrane-bound TNF mediates microtubule-targeting chemotherapeutics-induced cancer cytolysis via juxtacrine inter-cancer-cell death signaling

Microtubule-targeting agents (MTAs) are a class of most widely used chemotherapeutics and their mechanism of action has long been assumed to be mitotic arrest of rapidly dividing tumor cells. In contrast to such notion, here we show—in many cancer cell types—MTAs function by triggering membrane TNF (memTNF)-mediated cancer-cell-to-cancer-cell killing, which differs greatly from other non-MTA cell-cycle-arresting agents. The killing is through programmed cell death (PCD), either in way of necroptosis when RIP3 kinase is expressed, or of apoptosis in its absence. Mechanistically, MTAs induce memTNF transcription via the JNK-cJun signaling pathway. With respect to chemotherapy regimens, our results establish that memTNF-mediated killing is significantly augmented by IAP antagonists (Smac mimetics) in a broad spectrum of cancer types, and with their effects most prominently manifested in patient-derived xenograft (PDX) models in which cell–cell contacts are highly reminiscent of human tumors. Therefore, our finding indicates that memTNF can serve as a marker for patient responsiveness, and Smac mimetics will be effective adjuvants for MTA chemotherapeutics. The present study reframes our fundamental biochemical understanding of how MTAs take advantage of the natural tight contact of tumor cells and utilize memTNF-mediated death signaling to induce the entire tumor regression.

Inhibition of early T cell cytokine production by arsenic trioxide occurs independently of Nrf2

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a stress-activated transcription factor that induces a variety of cytoprotective genes. Nrf2 also mediates immunosuppressive effects in multiple inflammatory models. Upon activation, Nrf2 dissociates from its repressor protein, Keap1, and translocates to the nucleus where it induces Nrf2 target genes. The Nrf2-Keap1 interaction is disrupted by the environmental toxicant and chemotherapeutic agent arsenic trioxide (ATO). The purpose of the present study was to determine the effects of ATO on early events of T cell activation and the role of Nrf2 in those effects. The Nrf2 target genes Hmox-1, Nqo-1, and Gclc were all upregulated by ATO (1–2 μM) in splenocytes derived from wild-type, but not Nrf2-null, mice, suggesting that Nrf2 is activated by ATO in splenocytes. ATO also inhibited IFNγ, IL-2, and GM-CSF mRNA and protein production in wild-type splenocytes activated with the T cell activator, anti-CD3/anti-CD28. However, ATO also decreased production of these cytokines in activated splenocytes from Nrf2-null mice, suggesting the inhibition is independent of Nrf2. Interestingly, ATO inhibited TNFα protein secretion, but not mRNA expression, in activated splenocytes suggesting the inhibition is due to post-transcriptional modification. In addition, c-Fos DNA binding was significantly diminished by ATO in wild-type and Nrf2-null splenocytes activated with anti-CD3/anti-CD28, consistent with the observed inhibition of cytokine production by ATO. Collectively, this study suggests that although ATO activates Nrf2 in splenocytes, inhibition of early T cell cytokine production by ATO occurs independently of Nrf2 and may instead be due to impaired AP-1 DNA binding.

Associations between genetic and epigenetic variations in cytokine genes and mild persistent breast pain in women following breast cancer surgery

Persistent pain following breast cancer surgery is a significant problem. Both inherited and acquired mechanisms of inflammation appear to play a role in the development and maintenance of persistent pain. In this longitudinal study, growth mixture modeling was used to identify persistent breast pain phenotypes based on pain assessments obtained prior to and monthly for 6months following breast cancer surgery. Associations between the "no pain" and "mild pain" phenotypes and single nucleotide polymorphisms (SNPs) spanning 15 cytokine genes were evaluated. The methylation status of the CpG sites found in the promoters of genes associated with pain group membership was determined using bisulfite sequencing. In the multivariate analysis, three SNPs (i.e., interleukin 6 (IL6) rs2069840, C-X-C motif chemokine ligand 8 (CXCL8) rs4073, tumor necrosis factor (TNF) rs1800610) and two TNF CpG sites (i.e., c.-350C, c.-344C) were associated with pain group membership. These findings suggest that variations in IL6, CXCL8, and TNF are associated with the development and maintenance of mild persistent breast pain. CpG methylation within the TNF promoter may provide an additional mechanism through which TNF alters the risk for mild persistent breast pain after breast cancer surgery. These genetic and epigenetic variations may help to identify individuals who are predisposed to the development of mild levels of persistent breast pain following breast cancer surgery.

Regulation of human glioblastoma cell death by combined treatment of cannabidiol, γ-radiation and small molecule inhibitors of cell signaling pathways

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults. The challenging problem in cancer treatment is to find a way to upregulate radiosensitivity of GBM while protecting neurons and neural stem/progenitor cells in the brain. The goal of the present study was upregulation of the cytotoxic effect of γ-irradiation in GBM by non-psychotropic and non-toxic cannabinoid, cannabidiol (CBD). We emphasized three main aspects of signaling mechanisms induced by CBD treatment (alone or in combination with γ-irradiation) in human GBM that govern cell death: 1) CBD significantly upregulated the active (phosphorylated) JNK1/2 and MAPK p38 levels with the subsequent downregulation of the active phospho-ERK1/2 and phospho-AKT1 levels. MAPK p38 was one of the main drivers of CBD-induced cell death, while death levels after combined treatment of CBD and radiation were dependent on both MAPK p38 and JNK. Both MAPK p38 and JNK regulate the endogenous TRAIL expression. 2) NF-κB p65-P(Ser536) was not the main target of CBD treatment and this transcription factor was found at high levels in CBD-treated GBM cells. Additional suppression of p65-P(Ser536) levels using specific small molecule inhibitors significantly increased CBD-induced apoptosis. 3) CBD treatment substantially upregulated TNF/TNFR1 and TRAIL/TRAIL-R2 signaling by modulation of both ligand and receptor levels followed by apoptosis. Our results demonstrate that radiation-induced death in GBM could be enhanced by CBD-mediated signaling in concert with its marginal effects for neural stem/progenitor cells and astrocytes. It will allow selecting efficient targets for sensitization of GBM and overcoming cancer therapy-induced severe adverse sequelae.

Tumor necrosis factor-alpha gene promoter methylation in Japanese adults with chronic periodontitis and rheumatoid arthritis

BACKGROUND AND OBJECTIVE

Over-expression of tumor necrosis factor-alpha (TNF-α) plays a pathological role in chronic periodontitis (CP) and rheumatoid arthritis (RA), which might be regulated by the epigenetic mechanism. The aim of the present study was to evaluate whether there is a unique methylation profile of the TNF-α gene promoter in blood cells of individuals with CP and RA.

MATERIAL AND METHODS

The study participants consisted of 30 Japanese adults with RA (RA group), 30 race-matched adults with CP only (CP group) and 30 race-matched healthy controls (H group). Genomic DNA isolated from peripheral blood was modified by sodium bisulfite and analyzed, by direct sequencing, to investigate DNA methylation of the TNF-α gene promoter region. The level of TNF-α produced in mononuclear cells stimulated with Porphyromonas gingivalis lipopolysaccharide was determined using ELISA.

RESULTS

Twelve cytosine-guanine dinucleotide (CpG) motifs were identified in the TNF-α promoter fragment from -343 to +57 bp. The CP group showed a significantly higher methylation rate and frequency at -72 bp than the H group (p < 0.01). The RA group exhibited significantly higher methylation rates at seven CpG motifs (-302, -163, -119, -72, -49, -38 and +10 bp), and significantly higher methylation frequencies at six CpG motifs (-163, -119, -72, -49, -38 and +10 bp), than the H group (p < 0.01 for all comparisons). The levels of TNF-α produced were significantly different between individuals with and without methylation at -163 bp (p = 0.03).

CONCLUSION

These results suggest that the hypermethylated status of CpG motifs in the TNF-α gene promoter in blood cells may be unique to Japanese adults with CP and RA.

Pharmacological mechanism underlying anti-inflammatory properties of two structurally divergent coumarins through the inhibition of pro-inflammatory enzymes and cytokines

Background

The aim of the present study is to investigate the effects of two structurally divergent coumarins, calipteryxin (1) and (3’S,4’S)-3’,4’-disenecioyloxy-3’,4’-dihydroseselin (2) from Seseli recinosum, in lipopolysaccharide (LPS)-stimulated murine macrophages.

Methods

The nitrite production was evaluated using Griess reagent. The protein and mRNA expression levels were investigated through Western blot and quantitative real time-PCR analyses. The NF-κB and AP-1 DNA-binding activities were assessed using an electrophoretic mobility shift assay. The docking studies were performed with Glide XP in Schrödinger suite (version 2013).

Results

The results of the present study revealed that calipteryxin (1) and (3’S,4’S)-3’,4’-disenecioyloxy-3’,4’-dihydroseselin (2) treatment showed potent inhibitory effects on pro-inflammatory enzymes and cytokines associated with molecular signaling pathways. Treatment with calipteryxin and (3’S,4’S)-3’,4’-disenecioyloxy-3’,4’-dihydroseselin also decreased the production of nitric oxide (NO), tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β) in a dose-dependent manner. Additionally, both coumarins inhibited the LPS-induced protein and mRNA expression levels of nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in RAW264.7 cells. To explore the potential mechanisms underlying the inhibitory activity of coumarin derivatives, the protein signaling pathways for NF-κB, mitogen-activated protein kinase (MAPK) and Akt were examined. Calipteryxin and (3’S,4’S)-3’,4’-disenecioyloxy-3’,4’-dihydroseselin markedly reduced the LPS-stimulated phosphorylation of IKKα/β, p-IκBα and IκBα degradation as well as the nuclear translocation of the p65 subunit of pro-inflammatory transcription factor NF-κB. In addition, calipteryxin and (3’S,4’S)-3’,4’-disenecioyloxy-3’,4’-dihydroseselin) considerably inhibited the LPS-induced expression of ERK, c-Jun N-terminal kinase (JNK), p38 and Akt proteins. Furthermore, both coumarins significantly inhibited c-Jun expression in the nucleus.

Conclusions

Taken together, these results support the therapeutic potential and molecular mechanism of calipteryxin and (3’S,4’S)-3’,4’-disenecioyloxy-3’,4’-dihydroseselin associated with inflammatory diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s12950-015-0087-y) contains supplementary material, which is available to authorized users.

HIF-1α and PFKFB3 Mediate a Tight Relationship Between Proinflammatory Activation and Anerobic Metabolism in Atherosclerotic Macrophages

OBJECTIVE

Although it is accepted that macrophage glycolysis is upregulated under hypoxic conditions, it is not known whether this is linked to a similar increase in macrophage proinflammatory activation and whether specific energy demands regulate cell viability in the atheromatous plaque.

APPROACH AND RESULTS

We studied the interplay between macrophage energy metabolism, polarization, and viability in the context of atherosclerosis. Cultured human and murine macrophages and an in vivo murine model of atherosclerosis were used to evaluate the mechanisms underlying metabolic and inflammatory activity of macrophages in the different atherosclerotic conditions analyzed. We observed that macrophage energetics and inflammatory activation are closely and linearly related, resulting in dynamic calibration of glycolysis to keep pace with inflammatory activity. In addition, we show that macrophage glycolysis and proinflammatory activation mainly depend on hypoxia-inducible factor and on its impact on glucose uptake, and on the expression of hexokinase II and ubiquitous 6-phosphofructo-2-kinase. As a consequence, hypoxia potentiates inflammation and glycolysis mainly via these pathways. Moreover, when macrophages' ability to increase glycolysis through 6-phosphofructo-2-kinase is experimentally attenuated, cell viability is reduced if subjected to proinflammatory or hypoxic conditions, but unaffected under control conditions. In addition to this, granulocyte-macrophage colony-stimulating factor enhances anerobic glycolysis while exerting a mild proinflammatory activation.

CONCLUSIONS

These findings, in human and murine cells and in an animal model, show that hypoxia potentiates macrophage glycolytic flux in concert with a proportional upregulation of proinflammatory activity, in a manner that is dependent on both hypoxia-inducible factor -1α and 6-phosphofructo-2-kinase.

Association of TNF -1031 C/C as a potential protection marker for leprosy development in Amazonas state patients, Brazil

Polymorphisms present in the TNF promoter region has shown to influence the gene transcription. Leprosy displays different clinical manifestations according to the immune responses of the individual infected with Mycobacterium leprae. In this study, we evaluated the single nucleotide polymorphisms (SNPs) -238 G/A (rs361525), -308 G/A (rs1800629), -857 C/T (rs1799724), -863 A/C (rs1800630) and -1031 T/C (rs1799964) in the promoter region of the TNF to see whether these SNPs influence host-susceptibility to leprosy and the different clinical manifestation. Nucleotide sequencing was performed with DNA samples from 108 leprosy patients and 253 control subjects. An association between -1031 C/C genotype and protection from leprosy was observed when leprosy patients were compared to controls (OR 0.11; 95% CI=0.01-0.82; p=0.012). The -857 C/T genotype may be associated with susceptibility to leprosy (OR=1.81; 95% CI=1.09-3.00; p=0.028). Similar genotype and allele frequencies for the SNPs -308 G/A and -238 G/A were observed between leprosy patients and control subjects. Altogether, TNF polymorphisms in the promoter region may be predictive of leprosy outcome.

Anti-inflammatory effects of Cordyceps mycelium (Paecilomyces hepiali, CBG-CS-2) in Raw264.7 murine macrophages

Cordyceps (CS) is a traditional Chinese herb with various biological effects that include immune modulation. CBG-CS-2 is a strain, Paecilomyces hepiali, of the Cordyceps spp. The anti-inflammatory effects of CBG-CS-2 were investigated. The water-soluble fraction of CBG-CS-2 has high anti-inflammatory activity in LPS-induced Raw264.7 macrophages. We tested the role of CBG-CS-2 on the anti-inflammation cascade in LPS-stimulated Raw264.7 cells. CBG-CS-2 significantly decreased NO production, iNOS expression, and pro-inflammatory cytokine secretion in a dose-dependent manner. To investigate the mechanism by which CBG-CS-2 inhibits NO, iNOS, and pro-inflammatory cytokines, we examined the activities of NF-κB and AP-1 in LPS-activated macrophages. The results demonstrate that CBG-CS-2 suppresses the production and expression of NO, iNOS, and pro-inflammatory cytokines in LPS-activated macrophages via inhibition of NF-κB and AP-1, which may play an important role in inflammation. These findings suggest that CBG-CS-2 has modulatory effects on the inflammatory system in macrophages, and that it can serve as a useful anti-inflammatory dietary supplement or drug.

Glucocorticoid receptor dimerization is required for proper recovery of LPS-induced inflammation, sickness behavior and metabolism in mice

Endogenous glucocorticoids are essential for mobilizing energy resources, restraining inflammatory responses and coordinating behavior to an immune challenge. Impaired glucocorticoid receptor (GR) function has been associated with impaired metabolic processes, enhanced inflammation and exaggerated sickness and depressive-like behaviors. To discern the molecular mechanisms underlying GR regulation of physiologic and behavioral responses to a systemic immune challenge, GR(dim) mice, in which absent GR dimerization leads to impaired GR-DNA-binding-dependent mechanisms but intact GR protein-protein interactions, were administered low-dose lipopolysaccharide (LPS). GR(dim)-LPS mice exhibited elevated and prolonged levels of plasma corticosterone (CORT), interleukin (IL)-6 and IL-10 (but not plasma tumor necrosis factor-α (TNFα)), enhanced early expression of brain TNFα, IL-1β and IL-6 mRNA levels, and impaired later central TNFα mRNA expression. Exaggerated sickness behavior (lethargy, piloerection, ptosis) in the GR(dim)-LPS mice was associated with increased early brain proinflammatory cytokine expression and late plasma CORT levels, but decreased late brain TNFα expression. GR(dim)-LPS mice also exhibited sustained locomotor impairment in the open field, body weight loss and metabolic alterations measured by indirect calorimetry, as well as impaired thermoregulation. Taken together, these data indicate that GR dimerization-dependent DNA-binding mechanisms differentially regulate systemic and central cytokine expression in a cytokine- and time-specific manner, and are essential for the proper regulation and recovery of multiple physiologic responses to low-dose endotoxin. Moreover, these results support the concept that GR protein-protein interactions are not sufficient for glucocorticoids to exert their full anti-inflammatory effects and suggest that glucocorticoid responses limited to GR monomer-mediated transcriptional effects could predispose individuals to prolonged behavioral and metabolic sequelae of an enhanced inflammatory state.

A new chimeric protein represses HIV-1 LTR-mediated expression by DNA methylase

Once the human immunodeficiency virus (HIV) genome is inserted into the host genome, the virus cannot be removed, which results in latency periods and makes it difficult to eradicate. The majority of strategies to eradicate HIV have been based on preventing virus latency, thereby enabling antiretroviral drugs to act against HIV replication. Another innovative strategy is permanently silencing the integrated virus to prevent the spread of infection. Epigenetic processes are natural mechanisms that can silence viral replication. We describe a new chimeric protein (IN3b) that consists of a HIV-1 integrase domain, which recognises the HIV long terminal repeat (LTR) and the catalytic domain of DNA methyltransferase DNMT3b. Our objective was to silence HIV replication by the specific delivery of the catalytic methyltransferase domain to the LTR promoter to induce its methylation. We found that our IN3b chimeric protein was expressed in the nucleus and decreased LTR-associated HIV genome expression and HIV replication. Therefore, the IN3b chimeric protein may be an effective tool against HIV replication and maybe used in a new line of research to induce or maintain HIV latency.

The specific, reversible JNK inhibitor SP600125 improves survivability and attenuates neuronal cell death in experimental cerebral malaria (ECM)

Cerebral malaria (CM) is the most severe complication of Plasmodium falciparum in humans and major cause of death. SP600125 is a specific, small molecule inhibitor of JNK that prevents the phosphorylation of c-Jun and blocks the expression of proinflammatory cytokines and attenuates neuronal apoptosis in several neurodegenerative disorders. We evaluated the effect of SP600125 treatment on the survival of Plasmodium berghei ANKA (PbA)-infected C57BL/6J mice. Administration of SP600125 improved survival in PbA-infected C57BL6J mice but has no effect on parasitemia. Further, SP600125 administration resulted in attenuation of neuronal cell death along with inhibition of proinflammatory mediators TNF-α and COX-2 and proapoptotic mediators p-c-Jun and active caspase 3 in PbA-infected mice. The promising findings of this study make SP600125 a potential agent for supportive therapy to alleviate inflammation and neuronal cell death associated with CM.

African swine fever virus controls the host transcription and cellular machinery of protein synthesis

Throughout a viral infection, the infected cell reprograms the gene expression pattern in order to establish a satisfactory antiviral response. African swine fever virus (ASFV), like other complex DNA viruses, sets up a number of strategies to evade the host's defense systems, such as apoptosis, inflammation and immune responses. The capability of the virus to persist in its natural hosts and in domestic pigs, which recover from infection with less virulent isolates, suggests that the virus displays effective mechanisms to escape host defense systems. ASFV has been described to regulate the activation of several transcription factors, thus regulating the activation of specific target genes during ASFV infection. Whereas some reports have concerned about anti-apoptotic ASFV genes and the molecular mechanisms by which ASFV interferes with inducible gene transcription and immune evasion, less is yet known regarding how ASFV regulates the translational machinery in infected cells, although a recent report has shown a mechanism for favored expression of viral genes based on compartmentalization of viral mRNA and ribosomes with cellular translation factors within the virus factory. The viral mechanisms involved both in the regulation of host genes transcription and in the control of cellular protein synthesis are summarized in this review.

KSRP: a checkpoint for inflammatory cytokine production in astrocytes

Chronic inflammation in the central nervous system (CNS) is a central feature of many neurodegenerative and autoimmune diseases. As an immunologically competent cell, the astrocyte plays an important role in CNS inflammation. It is capable of expressing a number of cytokines such as tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β) that promote inflammation directly and through the recruitment of immune cells. Checkpoints are therefore in place to keep tight control over cytokine production. Adenylate/uridylate-rich elements (ARE) in the 3' untranslated region of cytokine mRNAs serve as a major checkpoint by regulating mRNA stability and translational efficiency. Here, we examined the impact of KH-type splicing regulatory protein (KSRP), an RNA binding protein which destabilizes mRNAs via the ARE, on cytokine expression and paracrine phenotypes of primary astrocytes. We identified a network of inflammatory mediators, including TNF-α and IL-1β, whose expression increased 2 to 4-fold at the RNA level in astrocytes isolated from KSRP(-/-) mice compared to littermate controls. Upon activation, KSRP(-/-) astrocytes produced TNF-α and IL-1β at levels that exceeded control cells by 15-fold or more. Conditioned media from KSRP(-/-) astrocytes induced chemotaxis and neuronal cell death in vitro. Surprisingly, we observed a prolongation of half-life in only a subset of mRNA targets and only after selective astrocyte activation. Luciferase reporter studies indicated that KSRP regulates cytokine gene expression at both transcriptional and post-transcriptional levels. Our results outline a critical role for KSRP in regulating pro-inflammatory mediators and have implications for a wide range of CNS inflammatory and autoimmune diseases.

Anti-inflammatory mechanism of 15,16-epoxy-3α-hydroxylabda-8,13(16),14-trien-7-one via inhibition of LPS-induced multicellular signaling pathways

Phytochemical investigation of Leonurus japonicus has led to the isolation of a labdane diterpene derivative, 15,16-epoxy-3α-hydroxylabda-8,13(16),14-trien-7-one (1), which was tested for its in vitro anti-inflammatory effects. The results demonstrated that 1 exhibits an inhibitory effect on LPS-stimulated RAW 264.7 macrophages. The anti-inflammatory action shown by 1 suppressed LPS-induced NF-κB activation, resulting in the down-regulation of iNOS and COX-2 protein expression, attributable to the inhibitory action of LPS-induced NO and PGE(2) production. Compound 1 inhibited LPS-induced phosphorylation and the degradation of inhibitory kappa B (IκBα) and decreased the nuclear translocation of p50 and p65. In addition, 1 exhibited an inhibitory effect on LPS-induced NF-κB-DNA and AP-1-DNA binding activity, using an electrophoretic mobility shift assay with NF-κB- and AP-1-specific (32)P-labeled probes. The LPS-induced mitogen-activated protein kinases (p-JNK, p-p38, and p-ERK) and p-Akt were inhibited after 30 and 10 min of LPS stimulation, respectively. In addition, TNF-α production was suppressed by 1.

Exendin-4 upregulates the expression of Wnt-4, a novel regulator of pancreatic β-cell proliferation

The Wnt-signaling pathway regulates β-cell functions. It is not known how the expression of endogenous Wnt-signaling molecules is regulated in β-cells. Therefore, we investigated the effect of antidiabetic drugs and glucose on the expression of Wnt-signaling molecules in β-cells. Primary islets were isolated and cultured. The expression of Wnt-signaling molecules (Wnt-4, Wnt-10b, Frizzled-4, LRP5, TCF7L2) and TNFα was analyzed by semiquantitative PCR and Western blotting. Transient transfections were carried out and proliferation assays of INS-1 β-cells performed using [(3)H]thymidine uptake and BrdU ELISA. Insulin secretion was quantified. A knockdown (siRNA) of Wnt-4 in β-cells was carried out. Exendin-4 significantly increased the expression of Wnt-4 in β-cells on the mRNA level (2.8-fold) and the protein level (3-fold) (P < 0.001). The effect was dose dependent, with strongest stimulation at 10 nM, and it was maintained after long-term stimulation over 4 wk. Addition of exd-(9-39), a GLP-1 receptor antagonist, abolished the effect of exendin-4. Treatment with glucose, insulin, or other antidiabetic drugs had no effect on the expression of any of the examined Wnt-signaling molecules. Functionally, Wnt-4 antagonized the activation of canonical Wnt-signaling in β-cells. Wnt-4 had no effect on glucose-stimulated insulin secretion or insulin gene expression. Knocking down Wnt-4 decreased β-cell proliferation to 45% of controls (P < 0.05). In addition, Wnt-4 and exendin-4 treatment decreased the expression of TNFaα mRNA in primary β-cells. These data demonstrate that stimulation with exendin-4 increases the expression of Wnt-4 in β-cells. Wnt-4 modulates canonical Wnt signaling and acts as regulator of β-cell proliferation and inflammatory cytokine release. This suggests a novel mechanism through which GLP-1 can regulate β-cell proliferation.

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

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

Direct inhibition of TNF-α promoter activity by Fanconi anemia protein FANCD2

Fanconi anemia (FA), an inherited disease, is associated with progressive bone marrow failure, predisposition to cancer, and genomic instability. Genes corresponding to 15 identified FA complementation groups have been cloned, and each gene product functions in the response to DNA damage induced by cross-linking agents and/or in protection against genome instability. Interestingly, overproduction of inflammatory cytokines such as tumor necrosis factor alpha (TNF-α) and aberrant activation of NF-κB-dependent transcriptional activity have been observed in FA cells. Here we demonstrated that FANCD2 protein inhibits NF-κB activity in its monoubiquitination-dependent manner. Furthermore, we detected a specific association between FANCD2 and an NF-κB consensus element in the TNF-α promoter by electrophoretic mobility shift assays (EMSA) and chromatin immunoprecipitation (ChIP) assay. Therefore, we propose FANCD2 deficiency promotes transcriptional activity of the TNF-α promoter and induces overproduction of TNF-which then sustains prolonged inflammatory responses. These results also suggest that artificial modulation of TNFα production could be a promising therapeutic approach to FA.

Molecular mechanisms by which saturated fatty acids modulate TNF-α expression in mouse macrophage lineage

Many macrophage functions are modulated by fatty acids (FAs), including cytokine release, such as tumor necrosis factor-α (TNF-α). TNF-α is of great interest due to its role in the inflammation process observed in several diseases such as rheumatoid arthritis, atherosclerosis, and obesity. However, the mechanisms by which FA effects occur have not been completely elucidated yet. In this study, we used a mouse monocyte lineage (J774 cells) to evaluate the effect of 50 and 100 μM of saturated (palmitic and stearic acids), monounsaturated (oleic acid) and polyunsaturated (linoleic acid) FAs on TNF-α production. Alterations in gene expression, poly(A) tail length and activation of transcription factors were evaluated. Oleic and linoleic acids, usually known as neutral or pro-inflammatory FA, inhibited LPS-induced TNF-α secretion by the cells. Saturated FAs were potent inducers of TNF-α expression and secretion under basal and inflammatory conditions (in the presence of LPS). Although the effect of the saturated FA was similar, the mechanism involved in each case seem to be distinct, as palmitic acid increased EGR-1 and CREB binding activity and stearic acid increased mRNA poly(A) tail. These results may contribute to the understanding of the molecular mechanisms by which saturated FAs modulate the inflammatory response and may lead to design of associations of dietary and pharmacological strategies to counteract the pathological effects of TNF-α.

Suppression of tumour necrosis factor-alpha by Schizonepeta tenuifolia water extract via inhibition of IkappaBalpha degradation and Jun N-terminal kinase/stress-activated protein kinase activation

OBJECTIVES

The anti-inflammatory effects of an aqueous extract of Schizonepeta tenuifolia on lipopolysaccharide (LPS)-induced tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in vivo and in vitro have been investigated.

METHODS

C57BL/6 mice were orally administered phosphate-buffered saline (control) or S. tenuifolia water extract (50, 200, 500 or 1000 mg/kg) for 10 days before intraperitoneal administration of LPS (1.3 mg/kg). Blood samples were obtained 1 h after LPS challenge, followed by determination of TNF-alpha and IL-6 levels. Peritoneal macrophages from thioglycollate-injected mice were obtained and stimulated with LPS and S. tenuifolia water extract for viability assay, cytokine analysis, real-time RT PCR and Western blotting.

KEY FINDINGS

Oral administration of S. tenuifolia water extract to mice significantly reduced LPS-induced serum levels of TNF-alpha, but not IL-6. When peritoneal macrophages were treated in vitro with S. tenuifolia water extract, the inhibition of LPS-induced TNF-alpha was more pronounced than that of IL-6 at the level of secreted protein and mRNA. S. tenuifolia water extract reduced the degradation of IkappaBalpha and the nuclear relocation of p65 NF-kappaB, but the phosphorylation of IkappaBalpha was not affected. Inhibition of c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) by S. tenuifolia water extract led secondarily to the inhibition of phospho-c-Jun and phospho-ATF-2.

CONCLUSIONS

These results indicated that the downregulation of TNF-alpha by S. tenuifolia water extract may have involved the inhibition of both IkappaBalpha degradation and activation of c-Jun and ATF-2 involving suppression of JNK/SAPK.

Pulmonary inflammation after intraperitoneal administration of ultrafine titanium dioxide (TiO2) at rest or in lungs primed with lipopolysaccharide

Nanoparticles are widely used in nanomedicines, including for targeted delivery of pharmacological, therapeutic, and diagnostic agents. Since nanoparticles might translocate across cellular barriers from the circulation into targeted organs, it is important to obtain information concerning the pathophysiologic effects of these particles through systemic migration. In the present study, acute pulmonary responses were examined after intraperitoneal (ip) administration of ultrafine titanium dioxide (TiO(2), 40 mg/kg) in mice at rest or in lungs primed with lipopolysaccharide (LPS, ip, 5 mg/kg). Ultrafine TiO(2) exposure increased neutrophil influx, protein levels in bronchoalveolar lavage (BAL) fluid, and reactive oxygen species (ROS) activity of BAL cells 4 h after exposure. Concomitantly, the levels of proinflammatory mediators, such as tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and macrophage inflammatory protein (MIP)-2 in BAL fluid and mRNA expression of TNF-alpha and IL-1beta in lung tissue were elevated post ultrafine TiO(2) exposure. Ultrafine TiO(2) exposure resulted in significant activation of inflammatory signaling molecules, such as c-Src and p38 MAP kinase, in lung tissue and alveolar macrophages, and the nuclear factor (NF)-kappaB pathway in pulmonary tissue. Furthermore, ultrafine TiO(2) additively enhanced these inflammatory parameters and this signaling pathway in lungs primed with lipopolysaccharide (LPS). Contrary to this trend, a synergistic effect was found for TNF-alpha at the level of protein and mRNA expression. These results suggest that ultrafine TiO(2) (P25) induces acute lung inflammation after ip administration, and exhibits additive or synergistic effects with LPS, at least partly, via activation of oxidant-dependent inflammatory signaling and the NF-kappaB pathway, leading to increased production of proinflammatory mediators.

High affinity receptor for IgE stimulation activates protein kinase D augmenting activator protein-1 activity for cytokine producing in mast cells

Protein kinase D (PKD) is a serine-threonine kinase involved in the activation of a variety of cells. In mast cells, activation of PKD by cross-linking of high affinity receptor for IgE (FcepsilonRI) has been reported, but little is known for its effects on cytokine production. We investigated the roles of PKD on FcepsilonRI-induced activator protein-1 (AP-1) activation and proinflammatory cytokine productions in mast cells. Pharmacological inhibition of PKD strongly inhibited production of interleukin (IL)-13 and tumor necrosis factor (TNF)-alpha induced by FcepsilonRI stimulation, and the overexpression of PKD significantly increased the IL-13 and TNF-alpha production. Reporter assay revealed that the overexpression of PKD enhanced FcepsilonRI-induced IL-13 promoter activation, and that the 5'-flanking region of IL-13 gene from positions -110 to -52 was under the regulation of PKD. The overexpression of PKD enhanced the induction of AP-1 luciferase activity by FcepsilonRI stimulation, while it had no effect on luciferase activities dependent upon NF-kappaB and NF-AT activated by FcepsilonRI stimulation. In EMSA, c-Jun and c-Fos appear to be the major components of AP-1 complexes activated by FcepsilonRI stimulation. Moreover the overexpression of PKD strongly enhanced the phosphorylation of both c-Jun and c-Fos following FcepsilonRI stimulation. Although stress-activated protein kinase/c-Jun N-terminal kinase (JNK) is known to be an important regulator for c-Jun phosphorylation and AP-1 activation, overexpression and inhibition of PKD had no effects on JNK phosphorylation. These results suggest that PKD may play a pivotal role in FcepsilonRI-induced cytokine production in mast cells through the activation of c-Jun, c-Fos, and AP-1.

Targeting innate immunity protein kinase signalling in inflammation

Inflammation is an evolutionarily conserved host reaction that is initiated in response to trauma, tissue damage and infection. It leads to changes in tissue homeostasis and blood flow, immune-cell activation and migration, and secretion of cytokines and mediators in a spatio-temporally coordinated manner. Progress in understanding of the mechanisms of the inflammatory response has identified various protein kinases that act as essential signalling components and therefore represent potential therapeutic targets. This article summarizes advances in the identification and validation of such targets, and discusses key issues for the development of small-molecule kinase inhibitors as a new generation of oral anti-inflammatory drugs, including feedback loops, inhibitor specificity and combination therapy.

Systems biology evaluation of immune responses induced by human host defence peptide LL-37 in mononuclear cells

The immune system is very complex, it involves the integrated regulation and expression of hundreds of proteins. To understand in greater detail how the human host defence immunomodulatory peptide LL-37 interacts with innate immunity, a systems approach was pursued. Polychromatic flow cytometry was employed to demonstrate that within human peripheral blood mononuclear cells, CD14+ monocytes, myeloid and plasmocytoid dendritic cells and T- and B-lymphocytes, all responded to LL-37, with the differential production of intracellular cytokines. Microarray analyses with CD14+ monocytes indicated the differential expression of 475 genes in response to stimulation with LL-37. To understand this complex response, bioinformatic interrogation, using InnateDB, of the gene ontology, signalling pathways and transcription factor binding sites was undertaken. Activation of the IkappaBalpha/NFkappaB, mitogen-activated protein kinases p38, ERK1/2 and JNK, and PI3K signalling pathways in response to LL-37 was demonstrated by pathway and ontology over-representation analyses, and confirmed experimentally by inhibitor studies. Computational analysis of the predicted transcription factor binding sites upstream of the genes that were regulated by LL-37 predicted the involvement of several transcription factors including NFkappaB and five novel factors, AP-1, AP-2, SP-1, E2F1, and EGR, which were experimentally confirmed to respond to LL-37 by performing transcription factor array studies on nuclear extracts from LL-37 treated mononuclear cells. These data are discussed as reflecting the integration of several responsive signalling pathways through the involvement of transcription factor complexes in gene expression activated by LL-37 in human mononuclear cells.

The gep oncogenes, Galpha(12) and Galpha(13), upregulate the transforming growth factor-beta1 gene

Transforming growth factor-beta1 (TGFbeta1) plays a role in neoplastic transformation and transdifferentiation. Galpha(12) and Galpha(13), referred to as the gep oncogenes, stimulate mitogenic pathways. Nonetheless, no information is available regarding their roles in the regulation of the TGFbeta1 gene and the molecules linking them to gene transcription. Knockdown or knockout experiments using murine embryonic fibroblasts and hepatic stellate cells indicated that a Galpha(12) and Galpha(13) deficiency reduced constitutive, auto-stimulatory or thrombin-inducible TGFbeta1 gene expression. In contrast, transfection of activated mutants of Galpha(12) and Galpha(13) enabled the knockout cells to promote TGFbeta1 induction. A promoter deletion analysis suggested that activating protein 1 (AP-1) plays a role in TGFbeta1 gene transactivation, which was corroborated by the observation that a deficiency of the G-proteins decreased the AP-1 activity, whereas their activation enhanced it. Moreover, mutation of the AP-1-binding site abrogated the ability of Galpha(12) and Galpha(13) to induce the TGFbeta1 gene. Transfection of a dominant-negative mutant of Rho or Rac, but not Cdc42, prevented gene transactivation and decreased AP-1 activity downstream of Galpha(12) and Galpha(13). In summary, Galpha(12) and Galpha(13) regulate the expression of the TGFbeta1 gene through an increase in Rho/Rac-dependent AP-1 activity, implying that the G-protein-coupled receptor (GPCR)-Galpha(12) pathway is involved in the TGFbeta1-mediated transdifferentiation process.

Activation of transcription factors and gene expression by oxidized low-density lipoprotein

It is well recognized that oxidized LDL (OxLDL) plays a crucial role in the initiation and progression of atherosclerosis. Many biological effects of OxLDL are mediated through signaling pathways, especially via the activation of transcription factors, which in turn stimulate the expression of genes involved in the inflammatory and oxidative stress response or in cell cycle regulation. In this review, we will discuss the various transcription factors activated by OxLDL, the studied cell types, the active compounds of the OxLDL particle, and the downstream genes when identified. Identification of the transcription factors and some of the downstream genes regulated by OxLDL has helped us understand the molecular mechanism involved in generation of the atherosclerotic plaque.

African swine fever virus blocks the host cell antiviral inflammatory response through a direct inhibition of PKC-theta-mediated p300 transactivation

During a viral infection, reprogramming of the host cell gene expression pattern is required to establish an adequate antiviral response. The transcriptional coactivators p300 and CREB binding protein (CBP) play a central role in this regulation by promoting the assembly of transcription enhancer complexes to specific promoters of immune and proinflammatory genes. Here we show that the protein A238L encoded by African swine fever virus counteracts the host cell inflammatory response through the control of p300 transactivation during the viral infection. We demonstrate that A238L inhibits the expression of the inflammatory regulators cyclooxygenase-2 (COX-2) and tumor necrosis factor alpha (TNF-alpha) by preventing the recruitment of p300 to the enhanceosomes formed on their promoters. Furthermore, we report that A238L inhibits p300 activity during the viral infection and that its amino-terminal transactivation domain is essential in the A238L-mediated inhibition of the inflammatory response. Importantly, we found that the residue serine 384 of p300 is required for the viral protein to accomplish its inhibitory function and that ectopically expressed PKC-theta completely reverts this inhibition, thus indicating that this signaling pathway is disrupted by A238L during the viral infection. Furthermore, we show here that A238L does not affect PKC-theta enzymatic activity, but the molecular mechanism of this viral inhibition relies on the lack of interaction between PKC-theta and p300. These findings shed new light on how viruses alter the host cell antiviral gene expression pattern through the blockade of the p300 activity, which represents a new and sophisticated viral mechanism to evade the inflammatory and immune defense responses.

Different methylation of the TNF-alpha promoter in cortex and substantia nigra: Implications for selective neuronal vulnerability

Increasing evidence has linked inflammatory processes to neurodegenerative disorders, including Alzheimer's and Parkinson's disease (PD). Tumor necrosis factor alpha (TNF-alpha) is a key inflammatory cytokine and several studies linked increased TNF-alpha to dopaminergic cell death in PD. The TNF-alpha promoter sequence contains several CpG dinucleotides located within or next to transcription factor binding sites. To test the hypothesis whether the methylation state of the TNF-alpha promoter contributes to increased expression of TNF-alpha in PD we compared DNA from different brain regions (substantia nigra pars compacta (SNpc) and cortex) of PD patients and neurologically healthy, age and sex matched controls by bisulfite sequencing of the TNF-alpha promoter region. The TNF-alpha promoter DNA from SNpc was significantly less methylated in comparison to DNA from cortex; however both in PD patients and controls. Although there was a tendency for hypomethylation in PD, our analysis of the 10 CpGs in the TNF-alpha core promoter region (-258 to -35 relative to the TSS) revealed no particular pattern in PD patients compared to control and identified no particular hypomethylated position in cortex or SNpc DNA. Electrophoretic mobility shift and luciferase reporter assays showed that methylation of specific solitary CpG in the TNF-alpha promoter resulted in reduced binding of the transcription factors AP-2 and Sp1, respectively, and suppressed TNF-alpha promoter activity. The brain region specific methylation state of solitary CpG in the TNF-alpha promoter thus determines transcription factor binding efficacy and TNF-alpha expression. A lesser degree of methylation of the TNF-alpha promoter in SNpc cells could underlie the increased susceptibility of dopaminergic neurons to TNF-alpha mediated inflammatory reactions.

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, characterization and expression analysis of the gene for a putative lipopolysaccharide-induced TNF-alpha factor of the Pacific oyster, Crassostrea gigas

Lipopolysaccharide-induced TNF-alpha factor (LITAF) is an important transcription factor that mediates the expression of inflammatory cytokines, including TNF-alpha, in lipopolysaccharide (LPS)-induced processes. In the present study, the Pacific oyster Crassostrea gigas LITAF (Cg-LITAF) gene was cloned and characterized. The full-length Cg-LITAF cDNA consists of 906bp and encodes a polypeptide of 115 amino acids. The Cg-LITAF gene consists of three exons and two introns, with a length of approximately 1.8kb. The Cg-LITAF protein showed 34-45% amino acid sequence identity with other known LITAF sequences. Although the Cg-LITAF coding sequence (115 aa) is shorter than all previously reported LITAF genes, the LITAF domain which contains two CXXC motifs is well conserved. An in vivo expression study showed that Cg-LITAF mRNA was expressed predominantly in gills and moderately in digestive gland and labial palps of healthy oysters. The accumulation of Cg-LITAF mRNA in oyster haemocytes determined by real-time PCR showed the peak 12h after bacterial challenge. This expression pattern suggests that Cg-LITAF is a potent factor in the regulation of genes that are involved in innate defence mechanisms.

c-Jun amino terminal kinase 1 deficient mice are protected from streptozotocin-induced islet injury

In vitro studies have implicated the c-Jun amino terminal kinase (JNK) in cytokine-induced pancreatic injury leading to a loss of insulin production and hyperglycemia. We examined the role of JNK1 in the multiple low dose streptozotocin (MLD-STZ) model in which islet injury and hyperglycemia are dependent upon T cell immunity and pro-inflammatory cytokines. MLD-STZ in wild type mice induced islet leukocyte infiltration, cytokine production, beta-cell apoptosis, and hyperglycemia. In contrast, Jnk1-/- mice were substantially protected from a loss of insulin producing cells and hyperglycemia in the MLD-STZ model despite a marked islet T cell and macrophage infiltrate. Based upon several lines of evidence, this protection was attributed to a reduction in TNF-alpha production by infiltrating Jnk1-/- macrophages leading to reduced beta-cell apoptosis. In conclusion, JNK1 signaling plays an essential role in macrophage induced beta-cell apoptosis and the development of hyperglycemia in MLD-STZ induced pancreatic injury.

Epigenetic regulation of tumor necrosis factor alpha

Tumor necrosis factor alpha (TNF-alpha) is a potent cytokine which regulates inflammation via the induction of adhesion molecules and chemokine expression. Its expression is known to be regulated in a complex manner with transcription, message turnover, message splicing, translation, and protein cleavage from the cell surface all being independently regulated. This study examined both cell lines and primary cells to understand the developmental regulation of epigenetic changes at the TNF-alpha locus. We demonstrate that epigenetic modifications of the TNF-alpha locus occur both developmentally and in response to acute stimulation and, importantly, that they actively regulate expression. DNA demethylates early in development, beginning with the hematopoietic stem cell. The TNF-alpha locus migrates from heterochromatin to euchromatin in a progressive fashion, reaching euchromatin slightly later in differentiation. Finally, histone modifications characteristic of a transcriptionally competent gene occur with myeloid differentiation and progress with differentiation. Additional histone modifications characteristic of active gene expression are acquired with stimulation. In each case, manipulation of these epigenetic variables altered the ability of the cell to express TNF-alpha. These studies demonstrate the importance of epigenetic regulation in the control of TNF-alpha expression. These findings may have relevance for inflammatory disorders in which TNF-alpha is overproduced.

A new device to study ex-vivo the effects of extracorporeal photochemotherapy on the immune system

Extracorporeal photochemotherapy (ECP) is a medical procedure effective in the treatment of several different T-cell mediated diseases such as cutaneous T-cell lymphoma and Graft-versus-Host Disease. During ECP treatment the patient's blood is processed by means of a cell separator to collect leukocytes (leukapheresis), mostly lymphocytes and monocytes, which are then incubated with the photoactive drug 8-methoxypsoralen (8-MOP), exposed to ultraviolet-A light (UV-A) and reinfused to the patient. It has been suggested that during ECP not only UV-A irradiation but also changes in the environmental condition may be relevant. Although ECP has been shown to have an in-vivo immunomodulatory effect, the mechanisms through which ECP exerts its effect remain elusive. One of the reasons for this incomplete knowledge is the absence of a reliable model for ECP. In order to investigate the effect of ECP on the peripheral immune system, we developed a new device which mimics the complete ECP cycle including blood transit through the cell separator. Peripheral blood samples (50ml) were obtained from volunteers and processed using a peristaltic pump. Peripheral blood mononuclear cells (PBMC) were then collected and treated with 8-MOP and UV-A under the same conditions used for the patients' therapy. Using this strategy we investigated 8-MOP, UV-A and their combined effect on the production of the pro-inflammatory cytokines interferon-gamma (IFN-gamma), interleukine-2 (IL-2) and tumor necrosis factor-alpha (TNF-alpha) in PBMC with and without polyclonal stimulation. We firstly demonstrated that our device does not affect total red and white blood cell counts. After 8-MOP and UV-A irradiation a significant decrease was observed in both activated CD4(+) and CD8(+) T lymphocytes producing IFN-gamma, IL-2 and TNF-alpha. Our findings are in line with those previously obtained in humans after complete ECP treatment, thus suggesting that our newly developed device is suitable for investigating the mechanism of action of ECP ex-vivo.

Genetic variation at the TNF locus and the risk of severe sequelae of ocular Chlamydia trachomatis infection in Gambians

Tumor necrosis factor (TNF) is thought to be a key mediator of the inflammatory and fibrotic response to Chlamydia trachomatis (Ct) infection. A large matched-pair case-control study investigated putative functional single nucleotide polymorphisms (SNPs) across the major histocompatibility complex (MHC) class III region, including TNF and its immediate neighbors nuclear factor of kappa light polypeptide gene enhancer in B cells (IkappaBL), inhibitor like 1 and lymphotoxin alpha (LTA) in relation to the risk of scarring sequelae of ocular Ct infection. Haplotype and linkage disequilibrium analysis demonstrated two haplotypes, differing at position TNF-308, conferring an increased risk of trichiasis. The TNF-308A allele, and its bearing haplotype, correlated with increased TNF production in lymphocyte cultures stimulated with chlamydial elementary body antigen. Thus TNF-308A may determine directly, or be a marker of a high TNF producer phenotype associated with increased risk of sequelae of chlamydial infection. Multivariate analysis provided evidence for the presence of additional risk-associated variants near the TNF locus.

Signal transduction pathways of tumor necrosis factor--mediated lung injury induced by ozone in mice

RATIONALE

Increasing evidence suggests that tumor necrosis factor (TNF)-alpha plays a key role in pulmonary injury caused by environmental ozone (O(3)) in animal models and human subjects. We previously determined that mice genetically deficient in TNF response are protected from lung inflammation and epithelial injury after O(3) exposure.

OBJECTIVES

The present study was designed to determine the molecular mechanisms of TNF receptor (TNF-R)-mediated lung injury induced by O(3).

METHODS

TNF-R knockout (Tnfr(-/-)) and wild-type (Tnfr(+/+)) mice were exposed to 0.3 ppm O(3) or air (for 6, 24, or 48 h), and lung RNA and proteins were prepared. Mice deficient in p50 nuclear factor (NF)-kappaB (Nfkb1(-/-)) or c-Jun-NH(2) terminal kinase 1 (Jnk1(-/-)) and wild-type controls (Nfkb1(+/+), Jnk1(+/+)) were exposed to O(3) (48 h), and the role of NF-kappaB and mitogen-activated protein kinase (MAPK) as downstream effectors of lung injury was analyzed by bronchoalveolar lavage analyses.

RESULTS

O(3)-induced early activation of TNF-R adaptor complex formation was attenuated in Tnfr(-/-) mice compared with Tnfr(+/+) mice. O(3) significantly activated lung NF-kappaB in Tnfr(+/+) mice before the development of lung injury. Basal and O(3)-induced NF-kappaB activity was suppressed in Tnfr(-/-) mice. Compared with Tnfr(+/+) mice, MAPKs and activator protein (AP)-1 were lower in Tnfr(-/-) mice basally and after O(3). Furthermore, inflammatory cytokines, including macrophage inflammatory protein-2, were differentially expressed in Tnfr(-/-) and Tnfr(+/+) mice after O(3). O(3)-induced lung injury was significantly reduced in Nfkb1(-/-) and Jnk1(-/-) mice relative to respective control animals.

CONCLUSIONS

Results suggest that NF-kappaB and MAPK/AP-1 signaling pathways are essential in TNF-R-mediated pulmonary toxicity induced by O(3).

Interleukin-1β and tetradecanoylphorbol acetate-induced biosynthesis of tumor necrosis factor α in human hepatoma cells involves the transcription factors ATF2 and c-Jun and stress-activated protein kinases

The proinflammatory cytokine tumor necrosis factor (TNF) alpha is mainly produced in cells from the monocyte/macrophage lineage. TNFalpha is also a key signaling molecule in the liver functioning as an important physiological and pathogenic mediator. In hepatocytes or human hepatoma cells TNFalpha is expressed at extremely low levels but TNFalpha biosynthesis can be induced by interleukin (IL)-1beta or 12-O-tetradecanoylphorbol-13-acetate (TPA). Here, we show that IL-1beta and TPA stimulated TNFalpha gene transcription in hepatoma cells mediated by a composite TPA-responsive element/cAMP response element. Both IL-1beta and TPA triggered phosphorylation and activation of the basic region leucine zipper transcription factors c-Jun and ATF2 and expression of dominant-negative mutants of c-Jun and ATF2-reduced TNFalpha promoter activity and secretion of TNFalpha. Expression of the nuclear dual-specific MAP kinase phosphatase-1 (MKP-1) blocked TNFalpha promoter activity and TNFalpha secretion following IL-1beta or TPA stimulation, indicating that MKP-1 functions as a nuclear shut-of-device of IL-1beta and TPA-induced TNFalpha expression.

Inhibition of inducible tumor necrosis factor-α expression by the fungal epipolythiodiketopiperazine gliovirin

TNF-alpha is a major pro-inflammatory cytokine that regulates further cytokine induction, especially of IL-1 and IL-6, in many human diseases including cancer, inflammation and immune disorders. In a search for new inhibitors of inducible TNF-alpha promoter activity and expression, cultures of the imperfect fungus Trichoderma harzianum were found to produce gliovirin, a previously isolated epipolythiodiketopiperazine. Gliovirin inhibited inducible TNF-alpha promoter activity and synthesis in LPS/IFN-gamma-stimulated macrophages/monocytes and Jurkat T-cells, co-stimulated with 12-O-tetradecanoylphorbol-13-acetate (TPA)/ionomycin, in a dose-dependent manner, with IC(50) values ranging from 0.21 to 2.1 microM (0.1-1 microg/ml). Studies on the mode of action revealed that gliovirin suppresses TNF-alpha synthesis by inhibiting the activation of extracellular signal-regulated kinase (ERK), thereby blocking the pathway leading to activation of the transcription factors AP-1 and NF-kappaB, the latter of which is involved in the inducible expression of many pro-inflammatory genes. Gliovirin also significantly reduced TPA/ionomycin-induced IL-2 mRNA levels and synthesis in Jurkat cells at low micromolar concentrations.

The acetaminophen-derived bioactive N-acylphenolamine AM404 inhibits NFAT by targeting nuclear regulatory events

AM404 is a synthetic TRPV1/CB(1) hybrid ligand with inhibitory activity on the anandamide transporter and is used for the pharmacological manipulation of the endocannabinoid system. It has been recently described that acetaminophen is metabolised in the brain to form the bioactive N-acylphenolamine AM404 and therefore, we have evaluated the effect of this metabolite in human T cells, discovering that AM404 is a potent inhibitor of TCR-mediated T-cell activation. Moreover, we found that AM404 specifically inhibited both IL-2 and TNF-alpha gene transcription and TNF-alpha synthesis in CD3/CD28-stimulated Jurkat T cells in a FAAH independent way. To further characterize the biochemical inhibitory mechanisms of AM404, we examined the signaling pathways that regulate the activation of the transcription factors NF-kappaB, NFAT and AP-1 in Jurkat cells. We found that AM404 inhibited both the binding to DNA and the transcriptional activity of endogenous NFAT and the transcriptional activity driven by the over expressed fusion protein Gal4-NFAT (1-415). However, AM404 did not affect early steps in NFAT signaling such as CD3-induced calcium mobilization and NFAT1 dephosphorylation. The NFAT inhibitory activity of AM404 seems to be quite specific since this compound did not interfere with the signaling pathways leading to AP-1 or NF-kappaB activation. These findings provide new mechanistic insights into the immunological effects of AM404 which in part could explain some of the activities ascribed to the widely used acetaminophen.

TNFalpha mediates the skeletal effects of thyroid-stimulating hormone

We have shown recently that by acting on the thyroid-stimulating hormone (TSH) receptor (TSHR), TSH negatively regulates osteoclast differentiation. Both heterozygotic and homozygotic TSHR null mice are osteopenic with evidence of enhanced osteoclast differentiation. Here, we report that the accompanying elevation of TNFalpha, an osteoclastogenic cytokine, causes the increased osteoclast differentiation. This enhancement in TSHR-/- and TSHR+/- mice is abrogated in compound TSHR-/-/TNFalpha-/- and TSHR+/-/TNFalpha+/- mice, respectively. In parallel studies, we find that TSH directly inhibits TNFalpha production, reduces the number of TNFalpha-producing osteoclast precursors, and attenuates the induction of TNFalpha expression by IL-1, TNFalpha, and receptor activator of NF-kappaB ligand. TSH also suppresses osteoclast formation in murine macrophages and RAW-C3 cells. The suppression is more profound in cells that overexpress the TSHR than those transfected with empty vector. The overexpression of ligand-independent, constitutively active TSHR abrogates osteoclast formation even under basal conditions and in the absence of TSH. Finally, IL-1/TNFalpha and receptor activator of NF-kappaB ligand fail to stimulate AP-1 and NF-kappaB binding to DNA in cells transfected with TSHR or constitutively active TSHR. The results suggest that TNFalpha is the critical cytokine mediating the downstream antiresorptive effects of TSH on the skeleton.

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.

The viral protein A238L inhibits TNF-alpha expression through a CBP/p300 transcriptional coactivators pathway

African swine fever virus (ASFV) is able to inhibit TNF-alpha-induced gene expression through the synthesis of A238L protein. This was shown by the use of deletion mutants lacking the A238L gene from the Vero cell-adapted Ba71V ASFV strain and from the virulent isolate E70. To further analyze the molecular mechanism by which the viral gene controls TNF-alpha, we have used Jurkat cells stably transfected with the viral gene to identify the TNF-alpha regulatory elements involved in the induction of the gene after stimulation with PMA and calcium ionophore. We have thus identified the cAMP-responsive element and kappa3 sites on the TNF-alpha promoter as the responsible of the gene activation, and demonstrate that A238L inhibits TNF-alpha expression through these DNA binding sites. This inhibition was partially reverted by overexpression of the transcriptional factors NF-AT, NF-kappaB, and c-Jun. Furthermore, we present evidence that A238L inhibits the activation of TNF-alpha by modulating NF-kappaB, NF-AT, and c-Jun trans activation through a mechanism that involves CREB binding protein/p300 function, because overexpression of these transcriptional coactivators recovers TNF-alpha promoter activity. In addition, we show that A238L is a nuclear protein that binds to the cyclic AMP-responsive element/kappa3 complex, thus displacing the CREB binding protein/p300 coactivators. Taken together, these results establish a novel mechanism in the control of TNF-alpha gene expression by a viral protein that could represent an efficient strategy used by ASFV to evade the innate immune response.

Activation of ERK1/2 and TNF-α production are mediated by calcium/calmodulin, and PKA signaling pathways during Mycobacterium bovis infection

Mycobacterium bovis bacillus Calmette-Guérin (BCG)-induced tumor necrosis factor (TNF)-alpha secretion via an extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase-dependent mechanism is an important host defence mechanism against Mycobacterium tuberculosis in human monocytes. We now define distinct signaling pathways that regulate induction of TNF-alpha and activation of ERK1/2 by intracellular signaling mechanisms during M. bovis infection. We determined that M. bovis BCG-induced ERK 1/2 activation occurs through a mechanism that requires intracellular calcium and likely involves a calmodulin-sensitive step. In contrast, M. bovis BCG can induce p38 mapk activation by a calcium (Ca2+)/calmodulin-independent mechanism. Interestingly, we present evidence that M. bovis BCG activates protein kinase A (PKA), since pretreatment of monocytes with H-89, a inhibitor of PKA activity, blocked the ability of M. bovis BCG to induce ERK1/2 activation. These results were further supported by the fact that treatment of cells with KT5720, another well-described inhibitor of PKA activity, significantly diminished the effect of M. bovis BCG on ERK1/2 activation. Furthermore, secretion of TNF-alpha in M. bovis-infected human monocytes was also dependent on Ca2+/calmodulin, and PKA pathways. Finally, addition of H-89 significantly diminished TNF-alpha mRNA expression in M. bovis-infected human monocytes. These results indicate that the Ca2+/calmodulin, and PKA pathways play important regulatory roles in monocyte signaling upon M. bovis infection.

Anti-arthritic Effects of Ephedra sinica STAPF Herb-Acupuncture: Inhibition of Lipopolysaccharide-Induced Inflammation and Adjuvant-Induced Polyarthritis

Anti-inflammatory and anti-arthritic effects of water distillates of Ephedra sinica STAPF (ES), in herb-acupuncture, on the inflammatory responses of arthritis was investigated using phorbol 12-myristate 13-acetate (PMA)/lipopolysaccharide (LPS)-induced human macrophage and adjuvant-induced arthritic rat. The luciferase reporter vectors driven by the tumor necrosis factor (TNF)-alpha and cyclooxygenase-2 promoters were transiently transfected into U937 cells, which were then differentiated and stimulated by PMA and LPS, respectively, to develop an in vitro anti-inflammation assay system. The luciferase activities, observed in the activated U937 cells, were significantly inhibited by ES herb-acupuncture, compared to those of PD98509 and berberine. To evaluate ES herb-acupuncture as a novel anti-arthritic therapy, a polyarthritic rat model was developed using heat-killed Mycobacterium tuberculosis, and 50 mul of ES distillate was subcutaneously injected into the ST36 acupoint on each knee joint. While the articular indexes of arthritic rats were evidently decreased by ES herb-acupuncture, their body weights did not regain their initial levels. This may be due to the accelerating effects of ES on weight-loss and fat consumption. The mRNA expressions of TNF-alpha and interleukin (IL)-6 genes, which were closely stimulated in the arthritic rat joints, were found to be restored to the normal levels through the ES treatment. In the case of IL-1beta, the recovery was not significant but substantial. The anti-arthritic effect of ES herb-acupuncture was not found in the ES-treated/non-acupoint group. In conclusion, the ES herb-acupuncture into the ST36 acupoint was found to be effective in alleviating the inflammatory response and thus arthritic symptoms in adjuvant-induced arthritic rats.

GCF2/LRRFIP1 represses tumor necrosis factor alpha expression

Tumor necrosis factor alpha (TNF-alpha) is an important mediator of inflammation, apoptosis, and the development of secondary lymphoid structures. Multiple polymorphic microsatellites have been identified in and around the gene, and there are also multiple single-base pair biallelic polymorphisms in the introns and promoter. The TNF-alpha -308 promoter polymorphism is a G-to-A transition which has been statistically associated with various autoimmune disorders. Some studies have found that it may directly mediate the increased transcription of TNF-alpha in some circumstances. This study characterizes proteins interacting at the polymorphic promoter site. Affinity purification of binding proteins and confirmatory chromatin immunoprecipitation assays were used to identify the proteins. Electrophoretic mobility shift analyses and surface plasmon resonance were used to define binding characteristics. Proteins interacting at this site include GCF2/LRRFIP1 and Ets-1. GCF2/LRRFIP1 appears to act as a repressor and occupies the -308 site in cells that do not make TNF-alpha. Cells competent to produce TNF-alpha have Ets-1 bound to the -308 promoter site. Active transcription is accompanied by NF-kappaB and c-Jun binding to the proximal promoter. Thus, dynamic changes on the TNF-alpha promoter, particularly at the -308 site, accompany the transition from repressed to active transcription. GCF2/LRRFIP1 is the first TNF-alpha repressor identified.