EGFR-dependent IL8 Production by Airway Epithelial Cells after Exposure to the Food Flavoring Chemical 2,3-butanedione.

2,3-butanedione (DA), a component of artificial butter flavoring, is associated with the development of occupational bronchiolitis obliterans (BO), a disease of progressive airway fibrosis resulting in lung function decline. Neutrophilic airway inflammation is a consistent feature of BO across a range of clinical contexts and may contribute to disease pathogenesis. Therefore, we sought to determine the importance of the neutrophil chemotactic cytokine interleukin-8 (IL-8) in DA induced lung disease using in-vivo and in-vitro model systems. First, we demonstrated that levels of Cinc-1, the rat homolog of IL-8, are increased in the lung fluid and tissue compartment in a rat model of DA-induced BO. Next, we demonstrated that DA increased IL-8 production by the pulmonary epithelial cell line NCI-H292 and by primary human airway epithelial cells grown under physiologically relevant conditions at an air-liquid interface. We then tested the hypothesis that DA induced epithelial IL-8 protein occurs in an EGFR dependent manner. In these in vitro experiments we demonstrated that epithelial IL-8 protein is blocked by the EGFR tyrosine kinase inhibitor AG1478 and by inhibition of tumor necrosis factor-alpha converting enzyme (TACE) using the small molecule inhibitor, TAPI-1. Finally, we demonstrated that DA induced IL-8 is dependent upon ERK1/2 and MEK activation downstream of EGFR signaling using the small molecule inhibitors AG1478 and PD98059. Together these novel in-vivo and in-vitro observations support that EGFR dependent IL-8 production occurs in DA induced BO. Further studies are warranted to determine the importance of IL-8 in BO pathogenesis.