Fig 1.
Production of the pro-inflammatory marker IL-8 after a 24 h exposure of three different cell culture setups (A549 and THP-1 monocultures and A549/THP-1 co-culture) to four doses (25, 75, 150 and 200 μg/ml) of PM1 samples from the combustion of three different wood logs and wood pellets. Bars represent the increase in IL8 secretion by the cells in comparison to unexposed control cells + SEM of the experimental averages. Asterisks indicate significance from blank control. a indicates significance from the birch log PM1 sample, b indicates significance from the beech log PM1 sample, c indicates significance from the spruce log PM1 sample, d indicates significance from the pellet combustion PM1 sample; § indicates significance from the A549 monoculture, # indicates significance from the THP-1 monoculture, $ indicates significance from the A549/THP-1 co-culture.
Fig 2.
Production of the pro-inflammatory markers (A) TGFβ, (B) GM-CSF, (C) IL-1β and (D) TNFα by a co-culture of A549 and THP-1 cells after a 24 h exposure of the cells to four doses (25, 75, 150 and 200 μg/ml) of PM1 samples from the combustion of three different wood logs and wood pellets. Bars represent the fold-change compared to unexposed control cells + SEM of the experimental averages. Asterisks indicate significance from unexposed control cells. a indicates significance from the birch log PM1 sample, b indicates significance from the beech log PM1 sample, c indicates significance from the spruce log PM1 sample, d indicates significance from the pellet combustion PM1 sample.
Fig 3.
Oxidative stress assessed with the DCF-assay after a 24 h exposure of three different cell culture setups (A549 and THP-1 monocultures and A549/THP-1 co-culture) to four doses (25, 75, 150 and 200 μg/ml) of particulate samples from the combustion of three different wood logs and wood pellets. Each bar represents the average of eight experiments. Whiskers indicate the standard error of the mean (SEM), asterisks indicate significance from blank control. a indicates significance from the birch log PM1 sample, b indicates significance from the beech log PM1 sample, c indicates significance from the spruce log PM1 sample, d indicates significance from the pellet combustion PM1 sample. § indicates significance from the A549 monoculture, # indicates significance from the THP-1 monoculture, $ indicates significance from the A549/THP-1 co-culture.
Fig 4.
Cellular Metabolic Activity assessed with the MTT-test after a 24 h exposure of three different cell culture setups (A549 and THP-1 monocultures and A549/THP-1 co-culture) to four doses (25, 75, 150 and 200 μg/ml) of particulate samples from the combustion of three different wood logs and wood pellets. Each bar represents the average of eight experiments. Whiskers indicate the standard error of the mean (SEM), asterisks indicate significance from unexposed control cells. a indicates significance from the birch log PM1 sample, b indicates significance from the beech log PM1 sample, c indicates significance from the spruce log PM1 sample, d indicates significance from the pellet combustion PM1 sample. § indicates significance from the A549 monoculture, # indicates significance from the THP-1 monoculture, $ indicates significance from the A549/THP-1 co-culture.
Fig 5.
Cell membrane integrity assessed with the PI exclusion assay after a 24 h exposure of three different cell culture setups (A549 and THP-1 monocultures and A549/THP-1 co-culture) to four doses (25, 75, 150 and 200 μg/ml) of particulate samples from the combustion of three different wood logs and wood pellets. Each bar represents the average of eight experiments. Whiskers indicate the standard error of the mean (SEM), asterisks indicate significance from unexposed control cells. a indicates significance from the birch log PM1 sample, b indicates significance from the beech log PM1 sample, c indicates significance from the spruce log PM1 sample, d indicates significance from the pellet combustion PM1 sample. § indicates significance from the A549 monoculture, # indicates significance from the THP-1 monoculture, $ indicates significance from the A549/THP-1 co-culture.
Fig 6.
DNA fragmentation in THP-1 cells after a 24 h exposure to four doses (25, 75, 150 and 200 μg/ml) of PM1 samples from the combustion of three different wood logs and wood pellets expressed as percentage of DNA in the tail. Each bar represents the average of four independent experiments with 100 analyzed cells/assay + SEM of the experimental averages. Asterisks indicate statistical significance from blank control, a indicates significance from the birch log PM1 sample, b indicates significance from the beech log PM1 sample, c indicates significance from the spruce log PM1 sample, d indicates significance from the pellet combustion PM1 sample.
Table 1.
Spearman correlation of the chemical constituents with the toxicity endpoints.