Proteases fromAspergillus fumigatusInduce Interleukin (IL)–6 and IL‐8 Production in Airway Epithelial Cell Lines by Transcriptional Mechanisms

Proteases secreted by Aspergillus fumigatus induce the production of cytokines by epithelial cells, including interleukin (IL)-6 and IL-8. In the present study, we focused on the mechanism(s) by which A. fumigatus-derived proteases elicit cytokine production in epithelial cells. In the epithelial cell line A549, IL-6 and IL-8 mRNA levels were enhanced by proteases as a result of transcriptional induction of the respective genes. Transcriptional induction of both genes coincided with enhanced DNA binding of nuclear factor (NF)-kappaB and NF-IL6, whereas activator protein-1 was unlikely to be involved. The enhanced transcriptional activity could be inhibited by the addition of chymostatin, showing serine protease dependency. Posttranscriptional mechanisms affecting the stability of IL-6 and IL-8 mRNAs were not involved in protease-induced IL-6 and IL-8 production. These data show that after exposure to A. fumigatus-derived proteases, IL-6 and IL-8 gene expressions are up-regulated as a result of transcriptional mechanisms.