Our study demonstrates for the first time important differences in the activation of the NF-kB pathway in anaerobic CF lung inflammation between P. histicola and P. aeruginosa, and shows a relationship between the alternative NF-κB signalling pathway (utilised by P. histicola) and the HIF-1α signalling pathway (summarised in Fig 5). This evidence concerns the gene NFKB1 and cystic fibrosis.