ABSTRACT
Exposure to elevated concentrations of ambient ultrafine particulate matter has been associated with increased morbidity and mortality in the public. The particle parameters triggering the underlying mechanisms are largely unknown. The aim of this study was to compare biological in vitro-effects of ultrafine model particles (hematite, silicasol) of different composition and different sizes to evaluate the influence of these parameters. Human epithelial (A549) and macrophage (THP-1, Mono Mac 6) cell lines in mono-culture as well as in co-culture were used as cellular models. The uptake of hematite particles into A549 cells was identified by light microscopy and confirmed by transmission electron microscopy. The loss of membrane integrity measured by the lactate dehydrogenase assay as well as the induction of interleukin-6 and interleukin-8 release were affected by the particles in a dose dependent manner. This study demonstrated that particle size and particle composition, respectively, were responsible for the observed biological effects. Furthermore, the co-cultures of epithelial cells (A549) and macrophages (Mono Mac 6 or differentiated THP-1) showed an increased sensitivity to particles concerning the cytokine release in comparison to the mono-cultures of each cell type.
Subject(s)
Air Pollutants, Occupational/adverse effects , Epithelial Cells/metabolism , Inflammation/etiology , Macrophages, Alveolar/metabolism , Nanostructures/adverse effects , Cell Communication , Cells, Cultured , Coculture Techniques , Cytokines/metabolism , Ferric Compounds/adverse effects , Humans , Particle Size , Respiratory Mucosa/cytology , Respiratory Mucosa/metabolism , Silicon Dioxide/adverse effectsABSTRACT
Photoexcitation of rhodopsin activates a heterotrimeric G-protein cascade leading to cyclic GMP hydrolysis in vertebrate photoreceptors. Light-induced exchanges of the visual G-protein transducin between the outer and inner segment of rod photoreceptors occur through the narrow connecting cilium. Here we demonstrate that transducin colocalizes with the Ca(2+)-binding protein centrin 1 in a specific domain of this cilium. Coimmunoprecipitation, centrifugation, centrin overlay, size exclusion chromatography, and kinetic light-scattering experiments indicate that Ca(2+)-activated centrin 1 binds with high affinity and specificity to transducin. The assembly of centrin-G-protein complex is mediated by the betagamma-complex. The Ca(2+)-dependent assembly of a G protein with centrin is a novel aspect of the supply of signaling proteins in sensory cells and a potential link between molecular translocations and signal transduction in general.
Subject(s)
Calcium-Binding Proteins/metabolism , Calcium/metabolism , Chromosomal Proteins, Non-Histone/metabolism , Heterotrimeric GTP-Binding Proteins/metabolism , Photoreceptor Cells, Vertebrate/metabolism , Animals , Cattle , Centrifugation , Chromatography, Gel , Light , Macromolecular Substances , Mice , Mice, Inbred C57BL , Microscopy, Immunoelectron , Molecular Weight , Photoreceptor Cells, Vertebrate/ultrastructure , Precipitin Tests , Protein Binding , Rats , Rats, Sprague-Dawley , Retina/cytology , Retina/metabolism , Retina/ultrastructure , Scattering, Radiation , Signal Transduction , Substrate Specificity , Transducin/metabolismABSTRACT
Fly ash from a municipal waste incinerator was used as a model for atmospheric particles in order to identify parameters relevant for the induction of adverse health effects. The aim of this study was to compare the biological effects of the total incinerator fly ash (IFA), the soluble and the insoluble fraction with the effects of quartz by in vitro toxicity studies. The previously sized fly ash (< 20 microns) was characterized by elemental composition and particle size distribution. The particles were administered to rat alveolar macrophages (NR8383) and human bronchial epithelial cells (BEAS-2B) at different amounts via the medium. The total IFA and its insoluble fraction were shown to induce cytotoxicity and cytokine release in a dose-dependent manner. The soluble fraction was nearly unable to induce cytotoxicity and TNF-alpha release but showed potent induction of IL-8 release in BEAS-2B cells at increasing concentrations. Quartz caused similar effects compared to IFA in NR8383 but was less effective in BEAS-2B.
