Livestock farm particulate matter enhances airway inflammation in mice with or without allergic airway disease

Effects of airborne biological particulate matter (BioPM; from livestock farms) on the pulmonary airways are not well studied. The aim of the present study was to investigate whether fine (<2.5 μm) BioPM derived from indoor animal stables (two chicken and two pig farms) could modify airway allergic responses by using a mouse model of allergic airway disease (allergic asthma). After intraperitoneal ovalbumin (OVA) sensitization mice were either intranasally challenged with OVA (allergic mice) or saline (non-allergic controls). Mice were also intranasally treated with farm-derived BioPM. Bronchoalveolar lavage fluid (BALF), blood and lung tissues were collected one day after intranasal exposure. BioPM from all the farms caused an acute neutrophilic inflammatory response in non-allergic mice. In allergic mice, BioPM derived from pig farm 2 induced a larger cellular inflammatory response than other farm-derived BioPM. All farm BioPM elicited Th17 cytokine (Interleukin (IL)-23) production except chicken farm 2, whereas Th2 cytokine (IL-5) increase was only induced by BioPM collected from chicken farm 2. These results indicate the exposure of BioPM from chicken and pig farms may cause the enhancement of airway allergic response in mice following exposure to OVA. More variation in the responses between farms was observed in allergic than non-allergic mice. Understanding the source and doses of BioPM that may affect the airway allergic response could help susceptible individuals to avoid worsening their respiratory diseases.