Figure 1.

Interactions in the cystic fibrosis lung. The complex interplay between microbial competition and the human immune system results in increased secretion of pro-inflammatory cytokines, microbial virulence factors and consequently tissue damage and bacterial invasion of the epithelial barrier. Mixed species infections lead to a stronger decrease in ciliary beating and increased goblet cell hyperplasia and tissue fibrosis, which are characteristic of cystic fibrosis disease progression. PQS, Pseudomonas quinolone signal; T3SS, type 3 secretion system; AI-2, autoinducer 2.