title: Acute effect of cigarette smoke on TNF-alpha release by macrophages mediated through the erk1/2 pathway.
abstract: Pulmonary emphysema is a major cause of mortality and morbidity in chronic obstructive pulmonary disease (COPD). Cigarette smoking is a major risk factor in the development of pulmonary emphysema. In this study, we investigated the acute effect of cigarette smoke in vitro on the production of tumour necrosis factor-alpha (TNF-alpha) using differentiated U937 cells, a macrophage model system. We found that stimulation of the macrophages with cigarette smoke media (CSM) leads to a rapid activation of extracellular-regulated kinases 1 and 2 (erk1/2), p90RSK and a transient decrease in phosphorylation of PKB/akt. The CSM also caused the subsequent induction of TNF-alpha release. Our studies revealed that U0126, an inhibitor of the erk1/2 pathway, markedly suppressed CSM-induced TNF-alpha release. Consistent with this finding, U0126 blocked CSM-stimulated erk1/2 phosphorylation, as well as phosphorylation of the downstream kinase, p90RSK. On the other hand, the PI3-K inhibitor, LY294002, and epidermal growth factor receptor (EGFR)-specific inhibitor, AG1478, did not suppress the release of TNF-alpha. Thus, CSM induction of TNF-alpha production by differentiated macrophages is regulated primarily via the erk1/2 pathway.
authors.affiliation: Department of Medicine, University of British Columbia and Vancouver Coastal Health Research Institute, Jack Bell Research Centre, 255-2660 Oak St, Vancouver, BC, Canada V6H 3Z6.
authors.forename: Loutfig
authors.initials: L
authors.lastname: Demirjian
authors.forename: Raja T
authors.initials: RT
authors.lastname: Abboud
authors.forename: Hong
authors.initials: H
authors.lastname: Li
authors.forename: Vincent
authors.initials: V
authors.lastname: Duronio
mesh_terms: D002070:Butadienes / Q000494:pharmacology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D020935:MAP Kinase Signaling System; D008264:Macrophages / Q000201:enzymology* / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009570:Nitriles / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012906:Smoke / Q000009:adverse effects*; D013997:Time Factors; D014026:Nicotiana / Q000009:adverse effects*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
chemical_list: D002070:Butadienes; D009570:Nitriles; D012906:Smoke; D014409:Tumor Necrosis Factor-alpha; C113580:U 0126; D051057:Proto-Oncogene Proteins c-akt; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3