Abstract
IL-12 plays a critical role in the development of cell-mediated immune responses and in the pathogenesis of inflammatory and autoimmune disorders. Dexamethasone (DXM), an anti-inflammatory glucocorticoid, has been shown to inhibit IL-12p40 production in LPS-stimulated monocytic cells. In this study, we investigated the molecular mechanism by which DXM inhibits IL-12p40 production by studying the role of the mitogen-activated protein kinases (MAPKs), and the key transcription factors involved in human IL-12p40 production in LPS-stimulated monocytic cells. A role for c-Jun N-terminal kinase (JNK) MAPK in LPS-induced IL-12p40 regulation in a promonocytic THP-1/CD14 cell line was demonstrated by using specific inhibitors of JNK activation, SP600125 and a dominant-negative stress-activated protein/extracellular signal-regulated kinase kinase-1 mutant. To identify transcription factors regulating IL-12p40 gene transcription, extensive deletion analyses of the IL-12p40 promoter was performed. The results revealed the involvement of a sequence encompassing the AP-1-binding site, in addition to that of NF-kappaB. The role of AP-1 in IL-12p40 transcription was confirmed by using antisense c-fos and c-jun oligonucleotides. Studies conducted to understand the regulation of AP-1 and NF-kappaB activation by JNK MAPK revealed that both DXM and SP600125 inhibited IL-12p40 gene transcription by inhibiting the activation of AP-1 and NF-kappaB transcription factors as revealed by luciferase reporter and gel mobility shift assays. Taken together, our results suggest that DXM may inhibit IL-12p40 production in LPS-stimulated human monocytic cells by down-regulating the activation of JNK MAPK, the AP-1, and NF-kappaB transcription factors.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adult
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Anthracenes / pharmacology
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Base Sequence
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Binding, Competitive / drug effects
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Binding, Competitive / genetics
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Binding, Competitive / immunology
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Cell Line, Tumor
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Dexamethasone / pharmacology*
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Down-Regulation / drug effects*
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Down-Regulation / immunology
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Enzyme Activation / drug effects
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Enzyme Activation / immunology
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Enzyme Inhibitors / pharmacology
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Humans
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Immunosuppressive Agents / pharmacology
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Interleukin-12 / antagonists & inhibitors*
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Interleukin-12 / biosynthesis
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Interleukin-12 / genetics
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Interleukin-12 / physiology
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Interleukin-12 Subunit p40
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JNK Mitogen-Activated Protein Kinases
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Lipopolysaccharide Receptors / biosynthesis
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Lipopolysaccharides / pharmacology*
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Macrophage Activation / drug effects
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Macrophage Activation / immunology
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Mitogen-Activated Protein Kinase 1 / metabolism
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Mitogen-Activated Protein Kinase 3
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Mitogen-Activated Protein Kinases / antagonists & inhibitors*
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Mitogen-Activated Protein Kinases / genetics
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Mitogen-Activated Protein Kinases / metabolism
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Mitogen-Activated Protein Kinases / physiology
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Molecular Sequence Data
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Monocytes / drug effects
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Monocytes / enzymology
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Monocytes / immunology*
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Monocytes / metabolism
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NF-kappa B / antagonists & inhibitors*
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NF-kappa B / metabolism
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Oligonucleotides, Antisense / pharmacology
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Promoter Regions, Genetic
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Protein Binding / drug effects
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Protein Binding / genetics
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Protein Binding / immunology
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Protein Subunits / antagonists & inhibitors*
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Protein Subunits / biosynthesis
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Protein Subunits / genetics
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Protein Subunits / physiology
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Proto-Oncogene Proteins c-fos / genetics
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Transcription Factor AP-1 / antagonists & inhibitors*
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Transcription Factor AP-1 / metabolism
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Transcription, Genetic
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p38 Mitogen-Activated Protein Kinases
Substances
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Anthracenes
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Enzyme Inhibitors
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Immunosuppressive Agents
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Interleukin-12 Subunit p40
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Lipopolysaccharide Receptors
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Lipopolysaccharides
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NF-kappa B
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Oligonucleotides, Antisense
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Protein Subunits
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Proto-Oncogene Proteins c-fos
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Transcription Factor AP-1
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Interleukin-12
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pyrazolanthrone
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Dexamethasone
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JNK Mitogen-Activated Protein Kinases
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Mitogen-Activated Protein Kinase 1
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Mitogen-Activated Protein Kinase 3
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Mitogen-Activated Protein Kinases
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p38 Mitogen-Activated Protein Kinases