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Because of their importance in maintaining normal respiratory function, this study was designed to evaluate the impact of barn dust on swine macrophages. As measures of macrophage function, we evaluated the activation of NF-κB, cytokine production, cell surface marker expression and the phagocytic and antibacterial capabilities of porcine macrophages after in vitro exposure to an organic swine barn dust extract (ODE).
ODE treatment induced AMϕ secretion of both pro- and anti-inflammatory cytokines, suggesting a complex activation profile. Additionally, ODE induced expression of genes (TLR2, NOD2) involved in sensing Gram-positive bacteria, a major component of barn dust. ODE exposure also enhanced the expression of several cell surface markers of activation, including a receptor for the porcine reproductive and respiratory syndrome virus. Moreover, two key functions of AMϕ, phagocytosis and bacterial killing, were impaired after exposure to ODE. Treatment with ODE for the first 72h of differentiation also inhibited the ability of monocyte-derived macrophages to translocate NF-κB to the nucleus following endotoxin stimulation.
Taken together, these results demonstrate, for the first time, that organic dust extract exposure negatively affects pig macrophage activation and function, potentially enhancing host susceptibility to a variety of respiratory infections.
Knetter SM, Tuggle CK, Wannemuehler MJ, Ramer-Tait AE. Organic barn dust extract exposure impairs porcine macrophage function in vitro: Implications for respiratory health. Vet Immunol Immunopathol. 2014 Jan 15;157(1-2):20-30. doi: 10.1016/j.vetimm.2013.10.019. Epub 2013 Nov 5.