title: Involvement of mitogen-activated protein kinases and NFkappaB in LPS-induced CD40 expression on human monocytic cells.
abstract: CD40 is a costimulatory molecule linking innate and adaptive immune responses to bacterial stimuli, as well as a critical regulator of functions of other costimulatory molecules. The mechanisms regulating lipopolysaccharide (LPS)-induced CD40 expression have not been adequately characterized in human monocytic cells. In this study we used a human monocytic cell line, THP-1, to investigate the possible mechanisms of CD40 expression following LPS exposure. Exposure to LPS resulted in a dose- and time-dependent increase in CD40 expression. Further studies using immunoblotting and pharmacological inhibitors revealed that mitogen-activated protein kinases (MAPKs) and NFkappaB were activated by LPS exposure and involved in LPS-induced CD40 expression. Activation of MAPKs was not responsible for LPS-induced NFkappaB activation. TLR4 was expressed on THP-1 cells and pretreatment of cells with a Toll-like receptor 4 (TLR4) neutralizing antibody (HTA125) significantly blunted LPS-induced MAPK and NFkappaB activation and ensuing CD40 expression. Additional studies with murine macrophages expressing wild type and mutated TLR4 showed that TLR4 was implicated in LPS-induced ERK and NFkappaB activation, and CD40 expression. Moreover, blockage of MAPK and NFkappaB activation inhibited LPS-induced TLR4 expression. In summary, LPS-induced CD40 expression in monocytic cells involves MAPKs and NFkappaB.
authors.affiliation: Center for Environmental Medicine, Asthma, and Lung Biology, University of North Carolina, Chapel Hill, NC 27599, USA. Weidong_Wu@med.unc.edu
authors.forename: Weidong
authors.initials: W
authors.lastname: Wu
authors.forename: Neil E
authors.initials: NE
authors.lastname: Alexis
authors.forename: Xian
authors.initials: X
authors.lastname: Chen
authors.forename: Philip A
authors.initials: PA
authors.lastname: Bromberg
authors.forename: David B
authors.initials: DB
authors.lastname: Peden
mesh_terms: D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D002070:Butadienes / Q000494:pharmacology; D019013:CD40 Antigens / Q000378:metabolism*; D002460:Cell Line; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D024202:Electrophoretic Mobility Shift Assay; D005434:Flow Cytometry; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D015151:Immunoblotting; D007976:Leupeptins / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D016328:NF-kappa B / Q000378:metabolism*; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011135:Polysaccharides, Bacterial / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D015398:Signal Transduction; D013450:Sulfones / Q000494:pharmacology; D013997:Time Factors; D051197:Toll-Like Receptor 4 / Q000378:metabolism
chemical_list: C434003:3-(4-methylphenylsulfonyl)-2-propenenitrile; D000873:Anthracenes; D002070:Butadienes; D019013:CD40 Antigens; D007093:Imidazoles; D007976:Leupeptins; D016328:NF-kappa B; D009570:Nitriles; D011135:Polysaccharides, Bacterial; D047428:Protein Kinase Inhibitors; D011725:Pyridines; D013450:Sulfones; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; C113580:U 0126; C432165:pyrazolanthrone; D020928:Mitogen-Activated Protein Kinases; C093642:SB 203580; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde