Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UNIPROT:P43026 (lipopolysaccharide)
62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Polymorphonuclear leukocytes (PMN) play an important role in eradicating bacterial infections. To test if PMN of patients with systemic lupus erythematosus (SLE) have defective capacity to produce IL-12, IL-12 p35 gene transcription and p70 excretion by PMN were evaluated in SLE patients and normal subjects. Peripheral blood PMN from 25 patients with active SLE and 25 normal individuals were stimulated with lipopolysaccharide (LPS, 100ng/mL) in the presence or absence of recombinant interferon (IFN)-gamma (5-200IU/mL). The IL-12 p35 gene transcripts were analyzed by reverse transcription - polymerase chain reaction (RT-PCR) and the IL-12 p70 in culture supenatants was quantified by enzyme immunoassay (EIA). At the 6th hour of stimulation, IL-12 expression in PMN of SLE patients was less prominent than that of the normal controls. The IL-12 was produced by normal PMN on LPS stimulation in the absence of IFN-gamma. IFN-gamma enhanced the IL-12 production by normal PMN stimulated with LPS, but it inhibited the IL-12 production in PMN from active lupus patients in the presence of LPS. Analysis with PCR using the same primers on the chromosomal DNA showed that p35 gene was intact in SLE patients. These results have suggested that SLE-PMN may have defect in IL-12 expression and the defect may be exaggerated in the presence of IFN-gamma which normally stimulates IL-12 production. This may account for increased susceptibility to multiple infections in patients with active SLE.
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PMID:Decreased IL-12 production by polymorphonuclear leukocytes in patients with active systemic lupus erythematosus. 1247 78

Interleukin (IL)-12 (p70), composed of p35 and p40 subunits, stimulates cellular immunity and inflammation. Stimulation of IL-12 production by smokeless tobacco extract (STE) could increase the chances of oral inflammatory disease. However, p40 forms homodimers and is part of IL-23 heterodimers. Expression of p35 and p40 in response to lipopolysaccharide (LPS) and interferon (IFN)-gamma requires activation of nuclear factor-kappa-B (NF-kappaB) and interferon regulatory factor (IRF) transcription factors. To determine the impact of STE on expression of p35 and p40, the activities of p35 and p40 promoter reporter plasmids in RAW264.7 cells stimulated with STE alone or in the presence of IFN-gamma and LPS were assessed. In addition, nuclear localizations of NF-kappaB p50, p65 and IRF-1, -2 and -8 in RAW264.7 cells treated with STE were evaluated. The results show that STE alone stimulates p40 and p35 promoter activity and enhances IFN-gamma-induced p40 and p35 promoter activity. In contrast, STE had no effect on LPS-induced p35 and p40 promoter activity and diminished IFN-gamma/LPS-induced p35 promoter activity. STE had little effect upon nuclear localization of IRFs, but it stimulated nuclear localization of both NF-kappaB p50 and p65. STE also stimulated IFN-gamma-induced activation of NF-kappaB p50 but reduced nuclear localization of IFN-gamma- and IFN-gamma/LPS-induced NF-kappaB p65. SN50, an inhibitor of NF-kappaB nuclear localization, significantly lowered STE-induced p35 and p40 promoter activity. These results suggest that STE stimulation of bioactive IL-12 production is correlated with its impact upon both p35 and p40 and can be attributed in part through an effect upon NF-kappaB p50 nuclear localization.
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PMID:Modulation of IL-12 p35 and p40 promoter activity by smokeless tobacco extract is associated with an effect upon activation of NF-kappaB but not IRF transcription factors. 1275 42

Bioactive interleukin (IL)-12 is a 70 000-molecular weight (MW) heterodimeric cytokine comprising p40 and p35 chains. However, p40 can also form homodimers that antagonize bioactive IL-12 or heterodimerize with p19 to form IL-23, which exhibits overlapping yet distinct functions to that of IL-12. We now define distinct signalling mechanisms that regulate lipopolysaccharide (LPS)-mediated induction of IL-12 p40 and p35 in macrophages and which may therefore provide therapeutic targets for precise and specific fine-tuning of cytokine responses. Thus, whilst LPS-induced p38 mitogen-activated protein kinase (MAPkinase) activation is required for the induction of both p40 and p35 subunits, Erk MAPkinase signalling mediates negative feedback regulation of p40, but not p35, production. Such Erk MAPkinase activation is downstream of calcium influx and targets LPS-induced IL-12 p40 transcription by suppressing the synthesis of the transcription factor, interferon regulatory factor-1 (IRF-1). In contrast, negative regulation of the p35 subunit of IL-12 occurs via a calcium-dependent, but Erk-independent, mechanism, which is likely to involve nuclear factor (NF)-kappa B signalling. Finally, the importance of both Erk and p38 MAPkinases in differentially regulating IL-12 p40 and p35 production is underscored by each being targeted by ES-62, a product secreted by parasitic filarial nematodes to polarize the immune system towards an anti-inflammatory phenotype conducive to their survival.
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PMID:Differential regulation of interleukin-12 p40 and p35 induction via Erk mitogen-activated protein kinase-dependent and -independent mechanisms and the implications for bioactive IL-12 and IL-23 responses. 1280 88

Human herpesvirus 6 (HHV-6) is a potentially immunosuppressive agent that has been suggested to act as a cofactor in the progression of HIV disease. Exposure of human macrophages to HHV-6A or HHV-6B profoundly impaired their ability to produce interleukin 12 (IL-12) upon stimulation with interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS). By contrast, the production of tumor necrosis factor-alpha (TNF-alpha); regulated on activation, normal T-cell expressed and secreted (RANTES); and macrophage inflammatory protein 1 beta (MIP-1 beta) was not negatively affected. To exclude the involvement of IL-12-suppressive cytokines, such as IL-10 and TNF-alpha, the viral stocks were fractionated by ultra-centrifugation. The bulk of the suppressive activity was recovered within the virion-rich pelleted fraction that was virtually devoid of such cytokines. IL-12 suppression was independent of viral replication, and the effect was not abrogated upon ultraviolet-light inactivation of the viral inoculum. The mechanism of HHV-6-mediated IL-12 suppression was investigated by RNase protection assays, which demonstrated unaltered levels of IL-12 p35 mRNA and only a modest reduction in p40 mRNA, which was insufficient to account for the near-complete loss of both extracellular and intracellular IL-12 protein. Moreover, both the IFN-gamma and the LPS signaling pathways were intact in HHV-6-treated cells. These data suggest that HHV-6 can dramatically affect the generation of effective cellular immune responses, providing a novel potential mechanism of HHV-6-mediated immunosuppression.
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PMID:Selective suppression of IL-12 production by human herpesvirus 6. 1282

We have isolated and characterized cDNAs and genes for pufferfish, Fugu rubripes, (Fugu) orthologues of mammalian interleukin (IL)-12 subunits (IL-12 p35 and IL-12 p40). The deduced amino acid sequences of the Fugu IL-12 subunits showed homology with mammalian IL-12 subunits (p35: 50.4-58.0% similarity; p40: 51.2-55.4% similarity). Phylogenetic analysis confirmed that Fugu IL-12 p35 and p40 genes cluster with their mammalian counterpart lineages. The genomic organization of each of the Fugu IL-12 subunit genes is similar to that of the corresponding mouse IL-12 subunit genes, although the Fugu genes are very compact due to small intron size. Comparative genomic analysis showed conserved syntenies within the IL-12 p35 and p40 regions between Fugu and human, indicating that the Fugu IL-12 p35 and p40 genes are orthologues for mammalian IL-12 p35 and p40 encoding genes, respectively. Expression of IL-12 p35 mRNA was observed in lymphoid tissues and several non-lymphoid tissues, while expression of IL-12 p40 mRNA was constitutive and nearly ubiquitous. In the spleen and head kidney, expression of IL-12 p35 was induced by polyriboinosinic polyribocytidylic acid [poly(I:C)] and not by lipopolysaccharide (LPS), while expression of IL-12 p40 was constitutive and unresponsive to both poly(I:C) and LPS. These results indicate that IL-12 levels are regulated by production of IL-12 p35 mRNA and suggest that IL-12 in fish may be involved in antiviral defense. This is the first report of the identification and characterization of IL-12 subunit cDNAs and genes in a non-mammalian vertebrate.
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PMID:Identification and characterization of Fugu orthologues of mammalian interleukin-12 subunits. 1284

Interleukin (IL)-12 is a heterodimeric cytokine that is critical for the development of a T-helper-1 immune response and immunity against intracellular pathogens. The IL-12 p40 gene product, expressed specifically in macrophages and dendritic cells, heterodimerizes with p35 to form bioactive IL-12, and heterodimerizes with p19 to comprise the cytokine IL-23. Regulation of the murine IL-12 p40 promoter is complex. Multiple cis-acting elements have been characterized that are involved in activation by bacterial products. However, molecular mechanisms through which interferon (IFN)-gamma and bacterial products synergistically activate IL-12 p40 gene expression are less clear. In this study, a composite NFAT/ICSBP binding site at -68 to -54 is identified that is functionally important for p40 promoter activation by lipopolysaccharide (LPS) and LPS plus IFN-gamma. DNA binding of NFAT and ICSBP is demonstrated on the endogenous promoter by chromatin immunoprecipitation. NFAT is required for ICSBP binding to this region. Overexpression of NFAT and ICSBP synergistically activates the p40 promoter. A dominant negative NFAT molecule attenuates LPS- and IFN-gamma-activated endogenous IL-12 p40 mRNA expression. A physical association between NFAT and ICSBP in the absence of DNA is detected by co-immunoprecipitation of endogenous proteins. Three NFAT domains are required for ICSBP interaction. Finally, in LPS- and IFN-gamma-activated RAW-264.7 cells, the association between NFAT and ICSBP is abrogated by IL-10 priming.
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PMID:Activation of the murine interleukin-12 p40 promoter by functional interactions between NFAT and ICSBP. 1287 85

Monocytes can develop into dendritic cells (DCs) that migrate to lymph nodes (LNs) and present antigens to T cells. However, we find that this differentiation is blocked when monocytes accumulate subcutaneously in response to bacteria or lipopolysaccharide (LPS). The inhibition of DC differentiation is mediated by the bacteria and in conjunction with inflammatory cells recruited at the site of injection. Inhibition of migratory DC development was reversed in Toll-like receptor (TLR)4-mutated mice when LPS, but not whole bacteria, was injected, suggesting that TLR4 is one but not the only mediator of the inhibition. The block imposed by bacteria was partly relieved by the absence of interleukin (IL)-12 p40, but not by individual absence of several cytokines involved in DC differentiation or in inflammation, i.e., IL-6, IL-10, IL-12 p35, and interferon gamma. Consistent with the inability of monocytes to yield migrating DCs, and the finding that other DCs had limited access to particulate or bacterial antigens, these antigens were weakly presented to T cells in the draining LN. These results illustrate that bacteria-associated signals can have a negative regulatory role on adaptive immunity and that local innate responses for containment of infectious bacteria can at least initially supersede development of adaptive responses.
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PMID:Lipopolysaccharide or whole bacteria block the conversion of inflammatory monocytes into dendritic cells in vivo. 1456 83

Interleukin (IL)-12 is a heterodimeric cytokine consisting of the p40 and p35 chains encoded on separate chromosomes. Coordinated expression of the two constituent genes is crucial for appropriate immune responses in timing, location, and magnitude. Interferon (IFN)-gamma priming of IL-12 production by macrophages represents an important physiological process in vivo for escalated cellular response to microbial infections. We provide evidence that IFN regulatory factor (IRF)-1-deficient macrophages have a selective impairment in mRNA synthesis of IL-12 p35 but not the p40 gene, and a strong deficiency in the production of IL-12 p70 but not p40. We demonstrate that the levels of IL-12 p35 protein stimulated by IFN-gamma and lipopolysaccharide (LPS) correspond to those of its mRNA, and that the nuclear factor kappaB signaling pathway is essential for the induction of IL-12 p35 transcription by LPS. IRF-1 plays a major role in the transcriptional activation of the IL-12 p35 gene, but not of the p40 gene, by physically interacting with an inverted IRF element within the IL-12 p35 promoter upon IFN-gamma activation. Moreover, IRF-1-mediated transcriptional activation of the p35 promoter requires the cooperation of two adjacent Sp1 elements. Thus, IRF-1 acts as a critical component of IFN-gamma signaling in the selective activation of IL-12 p35 transcription in synergy with LPS-mediated events.
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PMID:Differential regulation of interleukin (IL)-12 p35 and p40 gene expression and interferon (IFN)-gamma-primed IL-12 production by IFN regulatory factor 1. 1456 84

To gain insight into the inability of newborns to mount efficient Th1 responses, we analyzed the molecular basis of defective IL-12(p35) expression in human neonatal monocyte-derived dendritic cells (DCs). Determination of IL-12(p35) pre-mRNA levels by real-time RT-PCR revealed that transcriptional activation of the gene in lipopolysaccharide-stimulated neonatal DCs was strongly impaired compared with adult DCs. We next showed that p50/p65 and p65/p65 dimers interact with kB#1 site, a critical cis-acting element of the IL-12(p35) promoter. We found that LPS-induced p65 activation was similar in adult and newborn DCs. Likewise, in vitro binding activity to the Sp1#1 site, previously shown to be critical for IL-12(p35) gene activation, did not differ in adults and newborns. Since the accessibility to this Sp1#1 site was found to depend on nucleosome remodeling, we used a chromatin accessibility assay to compare remodeling of the relevant nucleosome (nuc-2) in adult and neonatal DCs. We observed that nuc-2 remodeling in neonatal DCs was profoundly impaired in response to lipopolysaccharide. Both nuc-2 remodeling and IL-12(p35) gene transcription were restored upon addition of recombinant interferon-gamma. We conclude that IL-12(p35) transcriptional repression in neonatal DCs takes place at the chromatin level.
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PMID:A defect in nucleosome remodeling prevents IL-12(p35) gene transcription in neonatal dendritic cells. 1505 64

Interleukin-12 (IL-12) is a heterodimeric cytokine comprising p40 and p35 subunits produced mainly by monocytes and macrophages, and plays an essential role in the regulation of the differentiation of Th1 cells. Green tea polyphenols exhibit potent anti-oxidative activities and anti-inflammatory effects by modulating cytokine production. We investigated the effect of catechins on IL-12p40 production in murine macrophages induced by bacterial lipopolysaccharide (LPS). Pretreatment with several catechins at doses of 0.3-30 microM suppressed IL-12 p40 production by murine peritoneal exudate cells (PEC) and J774.1 cells in a dose-dependent manner. Decreases in protein production were primarily due to down-regulation of the transcription of IL-12p40 mRNA. Of the various catechins, (-)-epigallocatechin gallate (EGCG) was the most potent inhibitor, followed by (-)-gallocatechin gallate (GCG) and (-)-epicatechin gallate (ECG). EGCG inhibited LPS-induced phosphorylation of p38 mitogen-activated protein kinase (MAPK), but not Jun N-terminal kinase (JNK), while EGCG augmented LPS-induced phosphorylation of p44/p42 extracellular signal-related kinase (ERK). In addition, both EGCG and GCG inhibited LPS-induced degradation of IkappaBalpha with concomitant inhibition of nuclear protein binding to NF-kappaB site and synthesis of IRF-1. These results suggest that gallate-containing catechins, particularly EGCG, inhibits LPS-induced IL-12p40 production in murine macrophages by inhibiting p38 MAPK while enhancing p44/p42 ERK, leading to the inhibition of IkappaBalpha degradation and NF-kappaB activation.
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PMID:Effect of various catechins on the IL-12p40 production by murine peritoneal macrophages and a macrophage cell line, J774.1. 1534 Feb 18


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