Particulate emissions from the combustion of pellet, charcoal and wood induce different cytotoxic responses in A549 cells

Summary This study aims to investigate the biological effects of biomass combustion-derived particles (PM10) collected from the emission of heating systems operating with pellet, charcoal and wood. Monocultures of human A549 alveolar cells were used to study the PM-induced effects. Different biological endpoints were evaluated. Pellet-derived particles seems to have higher toxic properties in comparison with charcoal and wood ones, suggesting a correlation between their chemical properties and toxicological profile. These data demonstrate that biomass combustion-derived particles may activate different toxicological pathways, suggesting that the fuel type and its quality may have an important role in the strategies to prevent respiratory diseases. Introduction Biomass largely contribute to particulate air pollution and likely to the adverse health effects observable in the exposed populations, including increased lung cancer risk, exacerbation of respiratory diseases and cardiovascular function impairment. Several studies, focusing on the potential toxicological effects of biomass-derived particles, are reported in literature and the results have shown different responses on the biological endpoints investigated on in vitro and in vivo systems. Differences among results are related to the use of diverse particles types, whose difference in composition may depend on the specific fuel, the combustion conditions, and the combustion appliances used (Jalava et al., 2012; Sussan et al., 2014). In the present study, we investigate the possible different toxicological properties of particles collected during the combustion of different fuels under identical conditions in the same stove (commonly used). Methodology and Results PM10 particles were morphologically and chemically characterized. A549 cells were exposed for 24h to 5 μg/cm2 PM. Cell viability, inflammatory response, antioxidant and xenobiotic metabolism activity, DNA damage and cell cycle alterations were investigated. Pellet-derived particles decreased cell viability, inducing necrosis, while charcoal and wood mainly induced apoptosis. Oxidative stress-related responses and cytochrome P450 enzymes activation were observed after exposure to all the combustion particles tested. Furthermore, DNA lesions and cell cycle arrest were observed only after pellet exposure. Differences in particles toxicity properties could be explained by their chemical composition, since pellet has a higher amount of metals with respect to charcoal and wood, which have higher quantities of PAHs. Among metals, the highest concentration of zinc (Zn) was observed in pellet. Literature data report that high concentration of Zn in PM correspond to higher particles toxic properties. For this a cell cycle analysis after cells exposure to particles pre-incubated with TPEN, a zinc chelator has been performed. The results obtained show that pellet, in the presence of TPEN, is unable to induce the cycle arrest. Conclusions These data suggest that differences in the responses induced by biomass particles may be related to the activation of different pathways in the lung. Further studies will elucidate the molecular mechanisms responsible for these toxic effects, and will improve our knowledge on PM-induced respiratory disease. Acknowledgement This work was supported by Cariplo Foundation (2013-1038) and MAECI project (ID PGR00786).