Proteins released from Pseudomonas aeruginosa (Pa) referent and clinical strains under microaerobiosis and their effects on cystic fibrosis airways

Little is known about changes in protein secretion in Pa laboratory and clinical strains induced by oxygen limitation and their effects on epithelial cells. Here, we demonstrated that conditioned medium from PAO1 and clinical strain AA2 under aerobiosis induced a statistically significant increase of about 2.9 and 4.9 times, respectively of IL-8 and TNF-_ mRNA, in CF airway epithelial cells. This induction was reduced of about 25% when strains were grown under microaerobiosis, suggesting that adaptation to microaerobiosis reduces Pa pathogenicity. Two-dimensional capillary chromatography–tandem mass spectrometry (MudPIT) identified 75 polypeptides released by PAO1 and 198 by AA2 in aerobiosis. Differential expression was observed under microaerobiosis when compared to aerobiosis with 6 proteins up-regulated in PAO1 and 7 proteins upregulated in AA2; 4 proteins were downregulated in AA2. 7 proteases were released from AA2 while only 1 from PAO1 with strong down modulation of alkaline metalloprotease in microaerobiosis by AA2 as confirmed by proteolytic activity assay. Identification of virulence factors might be facilitated by this combined approach suggesting molecular targets for pharmacological intervention. Supported by: Italian Cystic Fibrosis Research Foundation FFCgrant17/2006; Comitato Vicenza-Associazione Veneta Lotta contro la Fibrosi Cistica; Azienda Ospedaliera Verona, Italy. Equal contribution: C Cigana and P Mauri.