title: Dexamethasone inhibits IL-12p40 production in lipopolysaccharide-stimulated human monocytic cells by down-regulating the activity of c-Jun N-terminal kinase, the activation protein-1, and NF-kappa B transcription factors.
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.
authors.affiliation: Department of Pediatrics, University of Ottawa, Ottawa, Ontario K1H 8L1, Canada.
authors.forename: Wei
authors.initials: W
authors.lastname: Ma
authors.forename: Katrina
authors.initials: K
authors.lastname: Gee
authors.forename: Wilfred
authors.initials: W
authors.lastname: Lim
authors.forename: Kelly
authors.initials: K
authors.lastname: Chambers
authors.forename: Jonathan B
authors.initials: JB
authors.lastname: Angel
authors.forename: Maya
authors.initials: M
authors.lastname: Kozlowski
authors.forename: Ashok
authors.initials: A
authors.lastname: Kumar
mesh_terms: D000328:Adult; D000873:Anthracenes / Q000494:pharmacology; D001483:Base Sequence; D001667:Binding, Competitive / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D045744:Cell Line, Tumor; D003907:Dexamethasone / Q000494:pharmacology*; D015536:Down-Regulation / Q000187:drug effects* / Q000276:immunology; D004789:Enzyme Activation / Q000187:drug effects / Q000276:immunology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology; D018664:Interleukin-12 / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D053762:Interleukin-12 Subunit p40; D048031:JNK Mitogen-Activated Protein Kinases; D018950:Lipopolysaccharide Receptors / Q000096:biosynthesis; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008262:Macrophage Activation / Q000187:drug effects / Q000276:immunology; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D008969:Molecular Sequence Data; D009000:Monocytes / Q000187:drug effects / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000378:metabolism; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D021122:Protein Subunits / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D018808:Transcription Factor AP-1 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014158:Transcription, Genetic; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D000873:Anthracenes; D004791:Enzyme Inhibitors; D007166:Immunosuppressive Agents; D053762:Interleukin-12 Subunit p40; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D016328:NF-kappa B; D016376:Oligonucleotides, Antisense; D021122:Protein Subunits; D016760:Proto-Oncogene Proteins c-fos; D018808:Transcription Factor AP-1; D018664:Interleukin-12; C432165:pyrazolanthrone; D003907:Dexamethasone; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases