The role of recombinant human elafin in the resistance of A549 cells against Pseudomonas aeruginosa biofilm.

BACKGROUND Pseudomonas aeruginosa, an opportunistic respiratory pathogen, often causes pulmonary infection in patients with chronic inflammatory airway diseases and forms drug-resistant biofilm. Elafin, a natural antibiotic, has antimicrobial properties against Gram-negative bacteria. OBJECTIVES This study investigated the effects of elafin on the resistance of epithelial cells against P.aeruginosa biofilm. METHODS A549 epithelial cells transfected with pEGFP-N1-elafin or pEGFP-N1 were stimulated with tumor necrosis factor (TNF), P.aeruginosa supernatant and Escherichia coli supernatant followed by co-incubation for 24 h to form P.aeruginosa biofilms. RESULTS We found structural changes in the biofilms of all groups, especially the P.aeruginosa group. Bacterial counts in the TNF (3.238 +/- 0.356 x 10(6) CFU/cm(2)) and P.aeruginosa (3.317 +/- 0.247 x 10(6) CFU/cm(2)) groups were lower than in the control group (5.946 +/- 0.453 x 10(6) CFU/cm(2); p < 0.01). In the P.aeruginosa group, the bacterial count was lower than that of the E. coli group (5.138 +/- 0.391x 10(6) CFU/cm(2); p < 0.05). Bacterial clearance rates were higher in P.aeruginosa (44.2%) and TNF groups (45.6%) than in the E. coli group (13.6%). Cell intactness rates in pEGFP-N1-elafin-transfected groups were consistently higher than those of the control group (p < 0.01); the P.aeruginosa group rate at 24 h was the highest. Compared to the control group, the TNF, P.aeruginosa and E. coli groups showed increased elafin mRNA and protein in cells (p < 0.05), and contents in the TNF and P.aeruginosa group were higher than in the E. coli group (p< 0.05). CONCLUSION Overexpression of elafin in epithelial cells attenuated the damage of P.aeruginosa biofilm on epithelia. P.aeruginosa has the potential to induce elafin expression.