Biochemical and morphological changes in lung tissue and isolated lung cells of rats induced by short-term nitrogen dioxide exposure

Molecular dynamics exploring of atmosphere components interacting with lung surfactant phospholipid bilayers

Sulfur dioxide (SO₂), nitrogen oxide (NO₂) and ozone (O₃) in the atmosphere are significantly correlated with various respiratory and cardiovascular diseases. High doses of each of these gases or a mixture can change the physical and chemical properties of the lung membrane, thus leading to an increased pulmonary vascular permeability and structural failure of the alveolar cell membrane. In the present study, detailed molecular dynamic (MD) modeling was applied to investigate the effects of SO₂, NO₂, O₃ and mixtures of these gases on the dipalmitoyl phosphatidylcholine (DPPC) phospholipid bilayer. The results showed that several key physical properties, including the mass density, lipid ordering parameter, lipid diffusion, and electrostatic potential of the cell membrane, have been changed by the binding of different compounds. This resulted in significant variations and more disorder in the DPPC bilayer. The multiple analyses of membrane properties proved the toxicity of NO₂, O₃, and SO₂ to the DPPC bilayer, providing a theoretical basis for the experimental phenomenon that SO₂, NO₂ and O₃ can cause lung cell apoptosis. For the single systems, the damage to DPPC bilayer caused by O₃ was more serious than NO₂ and SO₂. More importantly, the MD simulations using the mixtures of SO₂, NO₂, and O₃ showed a much greater decline of membrane fluidity and the aggravation of membrane damage than the single systems, indicating a synergistic effect when NO₂, SO₂, and O₃ coexisted in the atmosphere, which could lead to much more severe damage and greater toxicities to the lung.

Pulmonary effects of inhaled limonene ozone reaction products in elderly rats

d-Limonene is an unsaturated volatile organic chemical found in cleaning products, air fresheners and soaps. It is oxidized by ozone to secondary organic aerosols consisting of aldehydes, acids, oxidants and fine and ultra fine particles. The lung irritant effects of these limonene ozone reaction products (LOP) were investigated. Female F344 rats (2- and 18-month-old) were exposed for 3 h to air or LOP formed by reacting 6 ppm d-limonene and 0.8 ppm ozone. BAL fluid, lung tissue and cells were analyzed 0 h and 20 h later. Inhalation of LOP increased TNF-alpha, cyclooxygenase-2, and superoxide dismutase in alveolar macrophages (AM) and Type II cells. Responses of older animals were attenuated when compared to younger animals. LOP also decreased p38 MAP kinase in AM from both younger and older animals. In contrast, while LOP increased p44/42 MAP kinase in AM from younger rats, expression decreased in AM and Type II cells from older animals. NF-kappaB and C/EBP activity also increased in AM from younger animals following LOP exposure but decreased or was unaffected in Type II cells. Whereas in younger animals LOP caused endothelial cell hypertrophy, perivascular and pleural edema and thickening of alveolar septal walls, in lungs from older animals, patchy accumulation of fluid within septal walls in alveolar sacs and subtle pleural edema were noted. LOP are pulmonary irritants inducing distinct inflammatory responses in younger and older animals. This may contribute to the differential sensitivity of these populations to pulmonary irritants.

Exposure of human lung cells to native diesel motor exhaust--development of an optimized in vitro test strategy

To investigate the effects of native diesel motor exhaust on human lung cells in vitro, a new experimental concept was developed using an exposure device on the base of the cell cultivation system CULTEX (Patent No. DE19801763.PCT/EP99/00295) to handle the cells during a 1-h exposure period independent of an incubator and next to an engine test rig. The final experimental set-up allows the investigation of native (chemically and physically unmodified) diesel exhaust using short distances for the transportation of the gas to the target cells. The analysis of several atmospheric compounds as well as the particle concentration of the exhaust was performed by online monitoring in parallel. To validate the complete system we concentrated on the measurement of two distinct viability parameters after exposure to air and undiluted, diluted and filtered diesel motor exhaust generated under different engine operating conditions. Cell viability was not influenced by the exposure to clean air, whereas dose-dependent cytotoxicity was found contingent on the dosage of exhaust. Additionally, the quality of exhaust, represented by two engine operating conditions (idling, higher load), also showed well-distinguishable cytotoxicity. In summary, the experimental set-up allows research on biological effects of native engine emissions using short exposure times.