title: Differential immunomodulatory responses to nine polycyclic aromatic hydrocarbons applied by passive dosing.
abstract: Studying the effects of hydrophobic chemicals using in vitro cell based methods is hindered by the difficulty in bringing and keeping these chemicals in solution. Their effective concentrations are often lower than their nominal concentrations. Passive dosing is one approach that provides defined and stable dissolved concentrations during in vitro testing, and was applied to control and maintain freely dissolved concentrations of polycyclic aromatic hydrocarbons (PAHs) at levels up to their aqueous solubility limit. The immunomodulatory effects of 9 different PAHs at aqueous solubility on human bronchial epithelial cells were determined by analysing the cytokine promoter expression of 4 different inflammatory cytokines using stably transfected recombinant A549 cell lines. Diverse immunomodulatory responses were found with the highest induction observed for the most hydrophobic PAHs chrysene, benzo(a)antracene and benzo(a)pyrene. Cytokine promoter expression was then studied in dose response experiments with acenaphthene, phenanthrene and benzo(a)anthracene. The strongest induction was observed for benzo(a)anthracene. Cell viability analysis was performed and showed that none of the PAHs induced cytotoxicity at any of the concentrations tested. Overall, this study shows that (1) immunomodulatory effects of PAHs can be studied in vitro at controlled freely dissolved concentrations, (2) the most hydrophobic PAHs were the strongest inducers and (3) induction was often higher at lower exposure levels and decreased then with concentration despite the apparent absence of cytotoxicity.
authors.affiliation: Department of Molecular Biology, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria. Electronic address: geja.oostingh@fh-salzburg.ac.at.
authors.forename: Gertie J
authors.initials: GJ
authors.lastname: Oostingh
authors.affiliation: Department of Environmental Science, Aarhus University, Frederiksborgvej 399, DK-4000 Roskilde, Denmark.
authors.forename: Kilian E C
authors.initials: KE
authors.lastname: Smith
authors.affiliation: Department of Molecular Biology, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Tischler
authors.affiliation: Department of Molecular Biology, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria.
authors.forename: Isabella
authors.initials: I
authors.lastname: Radauer-Preiml
authors.affiliation: Department of Environmental Science, Aarhus University, Frederiksborgvej 399, DK-4000 Roskilde, Denmark.
authors.forename: Philipp
authors.initials: P
authors.lastname: Mayer
mesh_terms: D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007155:Immunologic Factors / Q000008:administration & dosage* / Q000737:chemistry / Q000633:toxicity*; D016209:Interleukin-8 / Q000235:genetics; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D011084:Polycyclic Aromatic Hydrocarbons / Q000008:administration & dosage* / Q000737:chemistry / Q000633:toxicity*; D011401:Promoter Regions, Genetic; D012828:Silicones / Q000008:administration & dosage / Q000737:chemistry; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics
chemical_list: C508606:CXCL8 protein, human; D007155:Immunologic Factors; D016209:Interleukin-8; D016328:NF-kappa B; D011084:Polycyclic Aromatic Hydrocarbons; D012828:Silicones; D014409:Tumor Necrosis Factor-alpha
keywords: Cell culture; Immunomodulation; Passive dosing; Polycyclic aromatic hydrocarbons