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Elevation of IL-12 p40 and its antibody in myasthenia gravis with thymoma.

We examined the serum levels of cytokines, interferon (IFN)-alpha, IFN-gamma, interleukin (IL)-4, IL-12 p40, and IL-12 p70; those that affect the T helper 1 and 2 balance in patients with myasthenia gravis (MG). Among the cytokines tested, only IL-12 p40, together with the serum titer of anti-IL-12 p40 antibody, was significantly elevated in MG with thymoma. Their elevation was independent of the histopathology of thymoma. Thymectomy decreased the levels of IL-12 p40 accompanied by the anti-acetylcholine receptor antibody, but not anti-IL-12 p40 antibodies. These data strongly suggest the association of IL-12 p40 and its autoantibody with the immunopathology of MG with thymoma.

Adolescent↗

Inhibition of the Na(+)/H(+) antiporter suppresses IL-12 p40 production by mouse macrophages.

The amiloride-inhibitable Na(+)/H(+) antiporter plays an important role in macrophage activation. The intracellular pathways leading to interleukin (IL)-12 p40 production by activated macrophages are incompletely understood. In the present study, we examined the contribution of the Na(+)/H(+) antiporter to the production of IL-12 p40. Amiloride or its analogs decreased the production of IL-12 p40 in macrophages stimulated with bacterial lipopolysaccharide and interferon-gamma. The order of potency of amiloride analogs was consistent with the proposition that the effect of amiloride is mediated by the inhibition of the Na(+)/H(+) antiporter. The effect of amiloride was post-transcriptional, as IL-12 p40 mRNA levels induced by lipopolysaccharide and interferon-gamma were not affected by this inhibitor. Furthermore, the inhibitory effect of amiloride on IL-12 p40 production was not a result of interference with the activation of the p38 and p42/44 mitogen-activated protein kinases or c-Jun kinase. In summary, the production of IL-12 p40 requires a functional Na(+)/H(+) antiporter.

Amiloride↗

The interleukin 12 p40 gene promoter is primed by interferon gamma in monocytic cells.

Interleukin (IL) 12 is a proinflammatory cytokine produced by phagocytic cells, B cells, and other antigen-presenting cells that modulates adaptive immune responses by favoring the generation of T helper type 1 cells. IL-12 mediates some of its physiological activities by acting as a potent inducer of interferon (IFN) gamma production by T and natural killer cells. IFN-gamma enhances the ability of the phagocytic cells to produce IL-12 and other proinflammatory cytokines. Thus, IL-12-induced IFN-gamma acts in a positive feedback loop that represents an important amplifying mechanism in the inflammatory response to infections. We show here that IFN-gamma enhances IL-12 production mostly by priming phagocytic cells for lipopolysaccharide (LPS)-induced transcription of the IL-12 p40 gene, which encodes the heavy chain of the IL-12 heterodimer; furthermore, IFN-gamma directly induces transcription of the IL-12 p35 gene, which encodes the light chain of IL-12, and has at least an additive effect with LPS stimulation in inducing its transcription. The priming effect of IFN-gamma on the LPS-induced p40 gene transcription requires preincubation of the cells with IFN-gamma for at least 8 h to obtain a maximal effect. The priming effect of IFN-gamma for IL-12 production is predominantly at the transcriptional level for both the p40 and the p35 gene, and no evidence for a major role of posttranscriptional or translational mechanisms was found. A 3.3-kb human IL-12 p40 promoter construct transfected into cell lines recapitulated the tissue specificity of the endogenous gene, being silent in two human T cell lines, constitutively active in two human Epstein-Barr virus-positive B lymphoblastoid cell lines, and LPS inducible in the human THP-1 and mouse RAW264.7 monocytic cell lines. Because the RAW264.7 cell line is easily transfectable and regulates the endogenous IL-12 p40 gene in response to IFN-gamma or LPS similarly to human monocytes, it was used for analysis of the regulation of the cloned human IL-12 p40 promoter. A requirement for the region between -222 and -204 in both LPS responsiveness and IFN-gamma priming was established. This region contains an ets consensus sequence that was shown to mediate activation of the promoter by IFN-gamma and LPS, as well as by a cotransfected ets-2. The -222 construct was also regulated in a tissue-specific manner. Two other elements, IRF-1 located at -730 to -719, and NF-IL6 at -520 to -512, were also studied by deletion analysis, which did not result in decreased response to IFN-gamma and LPS stimulation.

Animals↗

Interleukin 12 p40 production by barrier epithelial cells during airway inflammation.

Human airway epithelial cells appear specially programmed for expression of immune response genes implicated in immunity and inflammation. To better determine how this epithelial system operates in vivo, we analyzed its behavior in mouse models that allow for in vitro versus in vivo comparison and genetic modification. Initial comparisons indicated that tumor necrosis factor alpha induction of epithelial intercellular adhesion molecule 1 required sequential induction of interleukin (IL)-12 (p70) and interferon gamma, and unexpectedly localized IL-12 production to airway epithelial cells. Epithelial IL-12 was also inducible during paramyxoviral bronchitis, but in this case, initial IL-12 p70 expression was followed by 75-fold greater expression of IL-12 p40 (as monomer and homodimer). Induction of IL-12 p40 was even further increased in IL-12 p35-deficient mice, and in this case, was associated with increased mortality and epithelial macrophage accumulation. The results placed epithelial cell overgeneration of IL-12 p40 as a key intermediate for virus-inducible inflammation and a candidate for epithelial immune response genes that are abnormally programmed in inflammatory disease. This possibility was further supported when we observed IL-12 p40 overexpression selectively in airway epithelial cells in subjects with asthma and concomitant increases in airway levels of IL-12 p40 (as homodimer) and airway macrophages. Taken together, these results suggest a novel role for epithelial-derived IL-12 p40 in modifying the level of airway inflammation during mucosal defense and disease.

Adult↗

Enhanced induction of interleukin-12(p40) secretion by human macrophages infected with Mycobacterium avium complex isolates from disseminated infection in AIDS patients.

Interleukin-12 (IL-12) is a key cytokine in the immune response to infection with Mycobacterium avium complex (MAC). Human immunodeficiency virus infection, a predisposing factor for disseminated MAC infection, causes a drop of bioactive IL-12(p70), mainly by decreasing the constitutive production of p35. IL-12(p40) and tumor necrosis factor-alpha (TNF-alpha) levels in supernatants of MAC-infected human monocyte-derived macrophages with intracellular growth rates were compared. Isolates from AIDS patients showed high growth rates and induced low TNF-alpha but high IL-12(p40) levels. In contrast, environmental isolates with fast growth rates induced only low levels of IL-12(p40) secretion. The increased IL-12(p40) stimulus seen with the clinical isolates could lead to a p40 surplus, which, alone or as the (p40)2 homodimer, has immunosuppressive properties. An immunosuppressive effect of MAC isolates may be an important advantage for their survival in vivo and may explain the contribution of MAC infection to the progression of AIDS.

Acquired Immunodeficiency Syndrome↗

The expression of IL-12 p40 and its homologue, Epstein-Barr virus-induced gene 3, in inflammatory bowel disease.

BACKGROUND: It has recently been suggested that Crohn's Disease (CD) is associated with an exaggerated T helper 1 cytokine response as manifest by increased production of interleukin-12 (IL-12) and interferon-gamma (IFN-gamma). Epstein-Barr virus-induced gene 3 (EBI3) encodes a 34-kDa glycoprotein that is 27% identical to the p40 unit of IL-12 and has recently been reported to be up-regulated in ulcerative colitis (UC). AIM: To determine whether mucosal expression of IL-12 p40 or EBI3 correlates with inflammatory bowel disease (IBD). PATIENTS/METHODS: mRNA expression in colonic mucosa from patients with UC, Crohn's disease (CD) and non-IBD controls was measured by reverse-transcribed real-time polymerase chain reaction (PCR). RESULTS: EBI3 was significantly increased in both involved and uninvolved colonic mucosa in patients with UC. Although IL-12 p40 was increased in some patients with CD relative to non-IBD controls, the increase was not statistically significant. However, 5-aminosalicylic acid (5-ASA) use was significantly correlated with reduced IL-12 p40 levels in the patients with CD, but not in UC cases. A similar reduction was not seen in 5-ASA-treated UC patients. CONCLUSION: IL-12 p40 expression in CD is heterogeneous. In contrast, expression of the IL-12 p40 homologue, EBI3, is up-regulated in nearly all UC cases and in a subset of CD.

Adult↗

Inhibitors of ATP-binding cassette transporters suppress interleukin-12 p40 production and major histocompatibility complex II up-regulation in macrophages.

ATP-binding cassette (ABC) transporters are a large family of proteins whose role is to translocate various substances across biological membranes. They include the Tangier disease protein ABC1, sulfonylurea receptors (SUR), multidrug resistance protein (MDR), and cystic fibrosis transmembrane regulator (CFTR). In the current study, we investigated the involvement of ABC transporters in the regulation of lipopolysaccharide (LPS) and/or interferon (IFN)-gamma-induced interleukin (IL)-12 p40 and tumor necrosis factor (TNF)-alpha production, nitric oxide formation, as well as major histocompatibility complex II up-regulation in macrophages. The general ABC transporter inhibitor glibenclamide suppressed both IL-12 p40 and nitric oxide production. However, glibenclamide failed to affect the production of TNF-alpha. The selective ABC1 inhibitors 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid and sulfobromophthalein mimicked the suppressive effect of glibenclamide on IL-12 p40 production. On the other hand, both the MDR inhibitor verapamil and CFTR blocker 2,2'-iminodibenzoic acid failed to suppress the production of IL-12 p40. Furthermore, selective inhibitors and activators of SURs were without effect. In agreement with the pharmacological data, macrophages expressed mRNA for ABC1, but not SURs or CFTR. Intracellular levels of IL-12 p40 were decreased by glibenclamide, suggesting that glibenclamide does not affect IL-12 p40 secretion. The effect of glibenclamide did not involve an interference with the activation of the p38 and p42/44 mitogen-activated protein kinases or c-Jun kinase. Glibenclamide also suppressed IFN-gamma-induced up-regulation of major histocompatibility complex II. Taken together, our results indicate that ABC proteins regulate LPS and/or IFN-gamma-induced macrophage activation.

ATP-Binding Cassette Transporters↗

Treatment with homodimeric interleukin-12 (IL-12) p40 protects mice from IL-12-dependent shock but not from tumor necrosis factor alpha-dependent shock.

The role of interleukin-12 (IL-12) was investigated in different shock models using anti-IL-12 reagents. IL-12 is composed of two disulfide-bonded subunits, p35 and p40. The IL-12 p40 homodimer (p40)2 has been shown to be a potent IL-12 antagonist in vitro. We investigated its in vivo inhibitory capacity in different shock models of mice. We could demonstrate that (p40)2 is able to protect mice from septic shock in primarily IL-12-dependent models such as the Shwartzman reaction and lipopolysaccharide (LPS)-induced shock, whereas (p40)2 has no effect in the tumor necrosis factor alpha-dependent LPS/D-GalN shock model. In IL-12-dependent shock models, (p40)2 inhibits IL-12-induced gamma interferon production and thereby interferes with the cascade of cytokine release, finally leading to death.

Animals↗

Herpes simplex virus type 1 and 2 intracellular p40: type-specific and cross-reactive antigenic determinants on peptides generated by partial proteolysis.

Intracellular p40 is a class of protein ranging in molecular weight from 39,000 to 45,000 that is immunoprecipitated from herpes simplex virus type 1 (HSV-1)- and HSV-2-infected cell extracts by mouse monoclonal antibodies or guinea pig antisera against HSV-1 and HSV-2 nucleocapsid p40. Analysis by a two-dimensional gel system showed that HSV-1 and HSV-2 intracellular p40 each consisted of three major components. However, these HSV-1 and HSV-2 proteins differed in charge and size. Analysis of Staphylococcus aureus V8 protease partial digests by two-dimensional gel electrophoresis indicated that none of the peptides of HSV-1 and HSV-2 intracellular p40 were identical. Immunoprecipitation of the partial digest products of intracellular p40-1 and p40-2 with homologous and heterologous guinea pig antisera resulted in the precipitation of various combinations of peptides indicating the presence of either type-specific or cross-reactive antigenic determinants.

Antigens, Viral↗

Multiple PU.1 sites cooperate in the regulation of p40(phox) transcription during granulocytic differentiation of myeloid cells.

The p40(phox) protein, a regulatory component of the phagocyte NADPH oxidase, is preferentially expressed in cells of myeloid lineage. We investigated transcriptional regulation of the p40(phox) gene in HL-60 myeloid cells. Deletion analysis of approximately 6 kb of the 5'-flanking sequence of the gene demonstrated that the proximal 106 base pair of the promoter exhibited maximum reporter activity. This region contains 3 potential binding sites for PU.1, a myeloid-restricted member of the ets family of transcription factors. Mutation or deletion of each PU.1 site decreased promoter activity, and the level of activity mediated by each site correlated with its binding avidity for PU.1, as determined by gel shift competition assays. Mutation of all 3 sites abolished promoter activity in myeloid cells. PU.1-dependent expression was also observed in the Raji B-cell line, whereas the moderate level of promoter reporter activity in the nonmyeloid HeLa cell line was independent of PU.1. Chromatin immunoprecipitation assay demonstrated occupation of the PU.1 sites by PU.1 in vivo in HL-60 cells. Cotransfection of the pGL3-p40-106 reporter construct with a dominant-negative PU.1 mutant dramatically reduced promoter activity, whereas the overexpression of PU.1 increased promoter activity. Promoter activity and transcript levels of p40(phox) increased in HL-60 cells during dimethyl sulfoxide-induced differentiation toward the granulocyte phenotype, and this was associated with increased cellular levels of PU.1 protein. Our findings demonstrate that PU.1 binding at multiple sites is required for p40(phox) gene transcription in myeloid cells and that granulocytic differentiation is associated with the coordinated up-regulation of PU.1 and p40(phox) expression.

Animals↗

Regulation of IL-12 p40 promoter activity in primary human monocytes: roles of NF-kappaB, CCAAT/enhancer-binding protein beta, and PU.1 and identification of a novel repressor element (GA-12) that responds to IL-4 and prostaglandin E(2).

Appropriate regulation of IL-12 expression is critical for cell-mediated immune responses. In the present study, we have analyzed the regulation of IL-12 p40 promoter activity in primary human monocytes in vivo. Accordingly, we analyzed the p40 promoter by in vivo footprinting in resting and activated primary human blood CD14(+) monocytes. Interestingly, footprints at binding sites for trans-activating proteins such as C/EBP, NF-kappaB, and ETS were only found upon stimulation with LPS and IFN-gamma. In contrast, a footprint over a purine-rich sequence at -155, termed GA-12 (GATA sequence in the IL-12 promoter), was observed in resting, but not activated, cells. Further characterization of this site revealed specific complex formation at a protected GATA core motif in unstimulated primary monocytes and RAW264.7 macrophages. Mutagenesis within the GA-12 sequence caused a significant up-regulation of inducible IL-12 p40 promoter activity in both transient and stable transfection systems, suggesting a repressor function of this site. Furthermore, binding activity of the GA-12 binding protein GAP-12 was increased by treatment with two potent inhibitors of IL-12 expression, IL-4 and PGE(2). Finally, we observed that IL-4-mediated repression of IL-12 p40 promoter activity is critically dependent on an intact GA-12 sequence. In summary, our data underline the complex regulation of the human IL-12 p40 promoter and identify GA-12 as a potent, novel repressor element that mediates IL-4-dependent suppression of inducible promoter activity in monocytes. Regulation of GAP-12 binding may thus modulate IL-12 p40 gene expression.

Animals↗

Transcriptional Regulation of the Gene, Encoding p40 Subunit of IL-12 and IL-23, in Murine Macrophages.

Interleukin-12 (IL-12) is an immunomodulatory cytokine with broad spectrum of activities, central of which are stimulation of NK cells, and promoting differentiation of T helper cells towards Th1 phenotype. IL-12 consists of two unrelated subunits, p35 and p40. Recently discovered cytokine, IL-23, which has both unique properties and those overlapping with IL-12, also contains p40 associated with another subunit, p19. Both IL-12 and IL-23 transmit the signal through receptors associated with JAK-STAT pathways. One of the critical components in the control of both IL-12 and IL-23 regulation is the transcriptional control of p40 gene which is induced in macrophages and dendritic cells in response to bacterial endotoxin, IFN-gamma and other stimuli. In the present study we report on the structure of the transcriptional unit of the murine p40 gene, its promoter and inducible expression of p40 in murine macrophages. Our findings are consistent with multi-level regulation of p40 expression.

Journal Article↗

[Effect of an immunomodulator (P40) on Escherichia coli urinary infection in the rat].

The preventive effects of various doses of the immunomodulator P40 on the experimental E. coli infection of the upper and lower urinary tract have been investigated in the rat. Under our experimental conditions, P40 only weakly influenced the bacteriological picture of the infection in rats infected by the upper route. However, the development of nephropathia might be decreased. By contrast, P40 was found to prevent the development of infection in two thirds of cases infected by the lower route. The preventive effect of P40 on infections of the lower urinary tract seems to be mostly medicated by the stimulation of phagocytosis, although both humoral and cellular immunity are likely to be involved. In contrast, the defense is most probably to be ascribed to cellular immunity in infections of the upper urinary tract. For the future, conditions will have to be specified which enable P40 to express predominantly its stimulating effect on cellular immunity. Furthermore, the choice of the minimum active dose together with its fractionated administration will prevent side-effects (prostatitis) while resulting in equally pronounced protective action. Since P40 has already successfully been used in man for the treatment of both infectious and tumoral processes, it could as well be used for the prevention of relapses in recurrent urinary infections.

Adjuvants, Immunologic↗

Genomic structure, chromosomal localization, start of transcription, and tissue expression of the human p40-phox, a new component of the nicotinamide adenine dinucleotide phosphate-oxidase complex.

p40-phox is a newly isolated cytosolic component of the nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase that copurifies with p67-phox. Although its function is not well defined, preliminary evidence indicates that it is a component of the cytosolic complex. We report the characterization of the human p40-phox gene, which is single copy and spans approximately 18 kb with 10 exons. Based on fluorescent in situ hybridization (FISH) studies and analysis of somatic hybrid cell lines, the chromosomal location of p40-phox is human chromosome 22q13.1. The start of transcription has been mapped to bp -156. The expression of p40-phox message is restricted to hematopoietic cells. In addition to identifying the mRNA transcript on Northern blot analysis in cells known to express components of the NADPH-oxidase, polymorphonuclear leukocytes, monocytes, B lymphoblastoid cell lines, and eosinophils, p40-phox is also expressed in two other cell types of white cell lineage, mast cells, and basophils. In addition, the mRNA for p40-phox is expressed in megakaryocytic cells, but not in erythroid cells.

Base Sequence↗

Cloning, promoter analysis and expression in response to bacterial exposure of sea bass (Dicentrarchus labrax L.) interleukin-12 p40 and p35 subunits.

Interleukin-12 (IL-12) is a heterodimeric cytokine pivotal in resistance to microbial and viral infections. In the search for immunoregulatory genes in sea bass the genes for the two IL-12 subunits p40 and p35 were cloned and sequenced. Molecular characterization of these two genes was performed at both the cDNA and genomic levels. Sea bass IL-12 p40 and p35 conserve most cysteines involved in the intra-chain disulfide bonds of human IL-12 subunits as well as the important structural residues for human IL-12 heterodimerization. The gene organization of sea bass IL-12 p40 is similar to the human orthologue, whilst the sea bass IL-12 p35 gene structure, as reported for pufferfish, differs from the human one in containing an additional exon and lacking a second copy of a duplicated exon present in the mammalian genes. The promoter analysis of both sea bass and pufferfish IL-12 genes showed the presence of the main cis-acting elements involved in the transcriptional regulation of human and mouse orthologues. The involvement of IL-12 in sea bass anti-bacterial immune responses was demonstrated by investigating the expression profiles of IL-1beta, IL-12 p40 and p35 in the head-kidney and spleen following intraperitoneal injection of UV-killed and live Photobacterium damselae ssp. piscicida (Phdp). Finally, the importance of nuclear factor (NF)-kappaB on UV-killed Phdp-induced IL-12 p40 and p35 gene transcription was shown by the use of pyrrolidine dithiocarbamate (PDTC).

Amino Acid Sequence↗

Structure and characterization of hamster IL-12 p35 and p40.

Complementary DNAs coding for two subunits of hamster interleukin-12 (IL-12), p35 and p40, were cloned from a hamster dendritic cell (DC) cDNA library. The cloning demonstrated that hamster IL-12 consisted of a p35 subunit with 216 amino acid (aa) residues and a p40 subunit with 327 aa. Structural comparison of hamster p35 and p40 at the protein level showed the highest homologies with each counterpart of sigmodon (hispid cotton rat). The gene expressions of hamster IL-12 p35 and p40 in bone marrow (BM) cells cultured in the presence of mouse granulocyte macrophage-colony-stimulating factor (mGM-CSF) and IL-4 were up-regulated during culture. Immunoblot analysis of 293 cells transfected with hamster p35 and p40 expression vectors suggested the presence of a covalently linked p35/p40 heterodimer. Furthermore, supernatant from the 293 cells transfected with both expression vectors induced the up-regulation of interferon-gamma (IFN-gamma) mRNA in hamster splenocytes, indicating that the p35/p40 heterodimer IL-12 protein present in the supernatant was functional. These results suggest that the vectors containing hamster IL-12 cDNA might be suitable tools for developing an immunotherapeutic approach against experimental cancer in a hamster model.

Amino Acid Sequence↗

A TaqI polymorphism in the 3'UTR of the IL-12 p40 gene correlates with increased IL-12 secretion.

Interleukin-12 (IL-12) is a key cytokine for the induction of Th1 immune responses. We evaluated whether a TaqI polymorphism in the 3'UTR of the IL-12 p40 gene affects secretion of IL-12 in vitro, and whether this polymorphism is associated with susceptibility to Crohn's disease (CD). IL-12 p40 and p70 secretion by monocytes in relation to genotype was determined in 63 healthy donors. Genotype and allele frequencies of the TaqI polymorphism in 150 CD patients were compared with 145 ethnically matched healthy controls (HC). No significant association was found between genotype and IL-12 p40 secretion after stimulation of monocytes with SAC+IFNgamma. In contrast, increasing IL-12 p70 secretion was found across the categories of non-carriers, heterozygotes and homozygotes for the variant allele (median values+/-SEM: 147+/-27, 282+/-51 and 482+/-34 pg/ml, respectively; P<0.005). The allele and genotype frequencies of this polymorphism in patients with CD did not differ statistically significantly from HC. The presence of a TaqI polymorphism in the IL12 p40 3'UTR correlates with increased in vitro IL-12 p70, but not p40 secretion. While this polymorphism does not appear to be correlated with susceptibility to CD in the limited population of patients tested here, it could influence the occurrence of the disease in certain subsets of patients.

3' Untranslated Regions↗

Interleukin-12 subunits p35 and p40 of Indian water buffalo (Bubalus bubalis) maintain high sequence homology with those of other ruminants.

The immune system of Indian water buffalo (Bubalus bubalis), one of the major dairy animals of the tropics, has received little attention. cDNAs encoding the two subunits of the heterodimeric interleukin (IL)-12 of Indian water buffalo were isolated from concanavalin A-stimulated lymphocytes. The 710-bp p35 and 1012-bp p40 subunits were amplified by reverse transcriptase polymerase chain reaction (RT-PCR), cloned, sequenced and compared with other ruminant sequences. The IL-12 p35 subunit cDNA had nine nucleotide variations and shared 98.1% amino acid identity with the cattle IL-12 p35. The IL-12 p40 cDNA had 13 nucleotide variations and had 97.5% amino acid identity with the cattle IL-12 p40. Both the subunits showed strict conservation in the predicted secondary structure and critical amino acid residues compared with other ruminant IL-12 molecules. Buffalo IL-12 p40 recombinant protein expressed in Escherichia coli cross-reacted with cattle anti-IL-12 p40 monoclonal antibody. Our study indicates a high level of conservation of this key cytokine among ruminants.

Amino Acid Sequence↗