title: Differential activation of the inflammasome in THP-1 cells exposed to chrysotile asbestos and Libby "six-mix" amphiboles and subsequent activation of BEAS-2B cells.
abstract: Inflammatory responses of THP-1 cells (macrophage cell line) exposed to chrysotile asbestos (Chry) and Libby six-mix (LIB) and the subsequent impact on bronchial epithelial cells were determined. Direct treatment of THP-1 cells with Chry caused cell death, activation of caspase-1 and release of IL-1β, while the addition of caspase-1 inhibitor, Z-YVAD-FMK, reduced IL-1β, suggesting that Chry activated the caspase-1 mediated Nod-like receptor protein 3 (NLRP3) inflammasome; by comparison, LIB had less effects on all of these parameters. Expression of antioxidant enzymes, protein oxidation and nitration, and lipid peroxides in THP-1 cells treated with the two particles suggest that LIB generated more reactive oxygen species (ROS) than the same dose of Chry. Differences in fiber length and surface area suggest a possible role for particulate size in the differential activation of the inflammasome. BEAS-2B cells, representing the bronchial epithelium, treated with supernatants of medium from Chry- or LIB-treated THP-1 cells (conditioned medium) activated the MAPK cascade, increased phosphorylation of ERK and Cot (MAP3K8), increased AP-1 binding activity and induced IL-6 release. To verify that IL-1β from THP-1 cells was responsible for activation of BEAS-2B, conditioned medium with added IL-1Ra, an IL-1β antagonist, was applied to BEAS-2B. Results show that IL-1Ra attenuated effects of conditioned medium, supporting a role of IL-1β, as a secondary mediator, in the transduction of inflammatory signaling from the macrophage to epithelial cells. The effects of LIB-conditioned medium appeared to be less dependent on IL-1β. In conclusion, Chry and LIB induce differential inflammatory responses in THP-1 cells that subsequently lead to differential effects in epithelial cells.
authors.affiliation: Department of Medicine, University of Vermont College of Medicine, Burlington, VT 05405, USA.
authors.forename: Muyao
authors.initials: M
authors.lastname: Li
authors.forename: Mickey E
authors.initials: ME
authors.lastname: Gunter
authors.forename: Naomi K
authors.initials: NK
authors.lastname: Fukagawa
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017636:Asbestos, Amphibole / Q000633:toxicity*; D017632:Asbestos, Serpentine / Q000633:toxicity*; D001980:Bronchi / Q000187:drug effects; D002352:Carrier Proteins / Q000187:drug effects / Q000378:metabolism; D020170:Caspase 1 / Q000378:metabolism; D002460:Cell Line; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects* / Q000276:immunology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D058847:Inflammasomes / Q000276:immunology*; D053590:Interleukin 1 Receptor Antagonist Protein / Q000494:pharmacology; D053583:Interleukin-1beta / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D008264:Macrophages / Q000276:immunology*; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D010766:Phosphorylation; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D018808:Transcription Factor AP-1 / Q000378:metabolism
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D017636:Asbestos, Amphibole; D017632:Asbestos, Serpentine; D002352:Carrier Proteins; D017077:Culture Media, Conditioned; D058847:Inflammasomes; D053590:Interleukin 1 Receptor Antagonist Protein; D053583:Interleukin-1beta; D015850:Interleukin-6; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C453881:NLRP3 protein, human; D011518:Proto-Oncogene Proteins; D017382:Reactive Oxygen Species; D018808:Transcription Factor AP-1; C460579:benzyloxycarbonyltyrosyl-valyl-alanyl-aspartic acid fluoromethyl ketone; D048049:Extracellular Signal-Regulated MAP Kinases; D020930:MAP Kinase Kinase Kinases; C069937:MAP3K8 protein, human; D020170:Caspase 1