PIGR and cystic fibrosis: A further evidence of the complex interplay between microenvironment and host regulation of epithelial pIgR expression is coming from studies in CF, where our group showed that in the dedifferentiated lower airway epithelium (135), the intrinsic downregulation of pIgR expression seen upon CFTR dysfunction, is upregulated and overcome in vivo, likely as a result of the presence of opportunistic bacteria such as P. aeruginosa (69).