Acute systemic and lung inflammation in C57Bl/6J mice after intratracheal aspiration of particulate matter from small-scale biomass combustion appliances based on old and modern technologies

Abstract

Inflammation is regarded as an important mechanism behind mortality and morbidity experienced by cardiorespiratory patients exposed to urban air particulate matter (PM). Small-scale biomass combustion is an important source of particulate air pollution. In this study, we investigated association between inflammatory responses and chemical composition of PM₁ emissions from seven different small-scale wood combustion appliances representing old and modern technologies. Healthy C57Bl/6J mice were exposed by intratracheal aspiration to single dose (10 mg/kg) of particulate samples. At 4 and 18 h after the exposure, bronchoalveolar lavage fluid (BALF) as well as serum was collected for subsequent analyses of inflammatory indicators (interleukin (IL)-6, IL-1β, IL-12, and IL-10; tumor necrosis factor-α (TNF-α); keratinocyte-derived chemoattractant (KC), and interferon-γ (IFN-γ)) in multiplexing assay. When the responses to the PM₁ samples were compared on an equal mass basis, the PM from modern technology appliances increased IL-6, KC, and IL-1β levels significantly in BALF at 4 and 18 h after the exposure. In contrast, these responses were seen only at 4 h time point in serum. Increased cytokine concentrations correlated with metal-rich ash related compounds which were more predominant in the modern technology furnaces emissions. These particles induced both local and systemic inflammation. Instead, polycyclic hydrocarbon (PAH) rich PM₁ samples from old technology (OT) evoked only minor inflammatory responses. In conclusion, the combustion technology largely affects the toxicological and chemical characteristics of the emissions. The large mass emissions of old combustion technology should be considered, when evaluating the overall harmfulness between the appliances. However, even the small emissions from modern technologies may pose significant toxic risks.

Keywords::

• Small-scale wood combustion
• particulate matter
• inflammation
• chemical composition

Acknowledgements

This project belongs to lead program of University of Eastern Finland (Sustainable Bioenergy, Climate Change, and Health). The authors acknowledge Heli Martikainen and Miia Koistinen for skilled technical assistance and Annika Virén for PAH analysis. Dr. Ewen MacDonald is acknowledged for revising the language of the manuscript.

Declaration of interest

This study is funded by the Austrian Kplus program of the Federal Government of Austria, the State Government of Styria and the State Government of Lower Austria and was supported by the Academy of Finland. The authors report no declaration of interest.