Up-regulation of ICAM-1 by cytokines in human tracheal smooth muscle cells involves an NF-kappa B-dependent signaling pathway that is only partially sensitive to dexamethasone.
Although the precise mechanisms by which steroids mediate their therapeutic effects remain unknown, steroids have been reported to abrogate cytokine-induced activation of the transcription factor NF-kappa B. In some cell types, NF-kappa B activation is necessary to regulate cytokine-mediated cellular functions. However, compelling evidence suggests that the steroid inhibition of NF-kappa B is complex and cell specific. Using EMSA, we show that stimulation with TNF-alpha or IL-1 beta induces NF-kappa B DNA-binding activity in human airway smooth muscle cells. TNF-alpha and IL-1 beta also increased luciferase activity in airway smooth muscle cells transfected with a reporter plasmid containing kappa B enhancer elements. Cytokines activated NF-kappa B by rapidly degrading its cytosolic inhibitor I kappa B alpha, which was then regenerated after 60 min. Cytokine-mediated I kappa B alpha reappearance was completely blocked by the protein synthesis inhibitor cycloheximide. Inhibition of cytokine-mediated I kappa B alpha proteolysis using the protease inhibitors N-tosyl-L -phenylalanine chloromethyl ketone and N-acetyl-L -leucinyl-L -leucinyl-norleucinal also inhibited cytokine-mediated early expression of ICAM-1. Although dexamethasone partially inhibited IL-1 beta- and TNF-alpha-induced up-regulation of ICAM-1 at 4 h, dexamethasone had no effect on cytokine-induced ICAM-1 expression at 18-24 h. In addition, neither cytokine-induced degradation or resynthesis of I kappa B alpha nor NF-kappa B DNA-binding activity were affected by dexamethasone. In cells transfected with the luciferase reporter, dexamethasone did not affect TNF-alpha-induced NF-kappa B-dependent transcription. Interestingly, cytokine-mediated expression of cyclooxygenase-2 was completely abrogated by dexamethasone at 6 h. Together, these data demonstrate that cytokine-mediated NF-kappa B activation and ICAM-1 expression involve activation of a steroid-insensitive pathway.
Amrani
Y
Y
Pulmonary, Allergy, and Critical Care Division, Department of Medicine, University of Pennsylvania Medical Center, Philadelphia 19104, USA. amrani@mail.med.upenn.edu
Lazaar
A L
AL
Panettieri
R A
RA
D001692:Biological Transport / Q000187:drug effects; D002478:Cells, Cultured; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D016207:Cytokines / Q000037:antagonists & inhibitors / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology*; D006801:Humans; D020672:I-kappa B Proteins; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis / Q000378:metabolism*; D007375:Interleukin-1 / Q000502:physiology; D007527:Isoenzymes / Q000096:biosynthesis; D008565:Membrane Proteins; D009130:Muscle, Smooth / Q000166:cytology / Q000201:enzymology / Q000276:immunology / Q000378:metabolism*; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis; D015398:Signal Transduction / Q000187:drug effects* / Q000276:immunology; D014132:Trachea / Q000166:cytology / Q000201:enzymology / Q000276:immunology / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology; D015854:Up-Regulation / Q000187:drug effects* / Q000276:immunology
D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D016207:Cytokines; D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D007375:Interleukin-1; D007527:Isoenzymes; D008565:Membrane Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1; D000072000:NF-KappaB Inhibitor alpha; D003907:Dexamethasone; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases