In vitro effects of nitrogen dioxide on the release of nitric oxide by bovine alveolar macrophages

In vitro genotoxicity assay of sidestream smoke using a human bronchial epithelial cell line

Genotoxic effects of air contaminants, such as gaseous or particulate compounds, have been difficult to investigate due to inefficient methods for exposing cell cultures directly to these substances. New cultivation and exposure techniques enable treatment of epithelial cells with sample atmospheres with subsequent in vitro assays, as demonstrated by a new system called CULTEX (CULTEX: patent No. DE 19801763; PCT/EP99/00295), which uses a transwell membrane technique for direct exposure of complex mixtures, for example sidestream cigarette smoke, at the air/liquid interface. The sensitivity and susceptibility of human bronchial epithelial cells to this complex mixture have already been shown for cytotoxic endpoints. In this study, genotoxic effects of sidestream cigarette smoke at different concentrations were assessed using the alkaline comet assay. HFBE 21 cells were exposed for 1 h to clean air, nitrogen dioxide or sidestream smoke. Exposure of the cells to sidestream cigarette smoke induced DNA strand breaks in a dose-dependent manner. The combination of gas phase exposure and the comet assay provides a realistic and efficient model for sensitive detection of DNA strand breaks induced by airborne and inhalable compounds.

In vitro effects of incinerator fly ash on pulmonary macrophages and epithelial cells

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.

A method for in vitro analysis of the biological activity of complex mixtures such as sidestream cigarette smoke

Studies of the cytotoxicity of air contaminants such as gaseous or particulate compounds and complex mixtures have traditionally used in animal experiments because of the difficulties in exposing cell cultures directly to these substances. New cultivation and exposure techniques enhance the efficiency of in vitro methods, as demonstrated by a new system called CULTEX* which uses a transwell membrane technique for direct exposure of complex mixtures like sidestream cigarette smoke at the air/liquid interface. The factors influencing the susceptibility of human bronchial epithelial cells (e.g. gas flow rate or duration of exposure) were studied and the cells were finally exposed for one hour to clean air or different concentrations of sidestream smoke. The biological parameters estimated were number of cells, metabolic activity and glutathione concentration. After exposure of the cells to sidestream cigarette smoke, dose-dependent effects were measured. Thus, the introduction of these cultivation and exposure techniques offers new testing strategies for the toxicological evaluation of a broad range of airborne and inhalable compounds.