Induction of interleukin-8 release by lung epithelium with cystic fibrosisepithelial lining fluid is marginally affected by inhibitors of Interleukin-1 beta

Interleukin-1 beta (IL-1 beta) and neutrophil elastase (NE) are present in the epithelial lining fluid (ELF) of patients with cystic fibrosis (CF). Bo th factors activate surrounding cells including lung epithelial cells, caus ing release. of IL-8, a potent chemoattractant for neutrophils. Previous st udies showed upregulation of IL-8 release by lung epithelial cells as a fun ction of NE in CF; however, few studies addressed the relationship between IL-1 beta and activation of lung epithelial cells in CF lungs. Confluent la yers of AS49 cells, a type II-like human lung epithelial cell line, were in cubated overnight with IL-1 beta (0-5 ng/ml) or NE (100 nM), and supernatan ts were analyzed for IL-8 by enzyme-linked immunosorbent assay (ELISA). Bot h IL-1 beta and NE led to a significant increase in IL-8. 12.8 +/- 2.8 ng/m l and 0.8 +/- 0.3 ng/ml, respectively. Next, bronchoalveolar lavage (BAL) s amples were obtained from one healthy adult volunteer and six patients with CF and measured for IL-8 and IL-1 beta concentrations by ELISA. Both IL-8 (range 169.00 +/- 156.57 to 1742.04 +/- 338.98 pg/ml) and IL-1 beta (range 0-24.26 +/- 0.52 pg/ml) were detected in CF specimens, whereas neither was detected in the volunteer's specimen. Normal and CF BALs then were incubate d overnight at a 1:10 dilution with confluent A549 cells. Analysis by ELISA of cell-free supernatants revealed increased IL-8 production from cells st imulated with CF BALs only Similar experiments were performed with BAL supe rnatants that had been incubated with soluble IL-1 type II receptor, solubl e IL-1 receptor antagonist, or a peptide inhibitor of NE. Addition of IL-1 inhibitors had a marginal effect on the amount of IL-8 release after incuba tion with CF BAL samples, whereas inhibition of NE had no effect. Our resul ts indicate that other factors present in ELF in CF account for IL-8 releas e from lung epithelial cells.