Mixed exposure to bacterial lipopolysaccharide and seafood proteases augments inflammatory signalling in an airway epithelial cell model (A549)

Seafood industry workers exhibit increased prevalence of respiratory symptoms due to exposure to bioaerosols containing a mixture of bioactive agents. In this study, a human pulmonary epithelial cell model (A549) was exposed to mixtures of bacterial lipopolysaccharide (LPS) and protease-activated receptor-2 (PAR-2) agonists H-Ser-Leu-Ile-Gly-Lys-Val-NH₂ (SLIGKV-NH₂), purified salmon (Salmo salar) trypsin or purified king crab (Paralithodes camtschaticus) trypsin. The inflammatory response was measured based on nuclear factor-kappa B (NF-κB) activation of transcription in a luciferase reporter gene assay and interleukin 8 (IL-8) secretion in an enzyme-linked immunosorbent assay. We observed that mixtures of SLIGKV-NH₂ or trypsins with LPS augmented the activation of NF-κB and secretion of IL-8. The effect on IL-8 secretion was synergistic when both trypsins and LPS were used in the lower concentration range. The results demonstrate that exposure to mixtures of agents that are relevant to seafood industry workplaces may lead to increased inflammatory signalling compared with exposure to the individual agents alone. Furthermore, the results indicate that synergism may occur with the combined exposure to seafood trypsins and LPS and is most likely to occur when exposure to either agent is low.