Pseudomonas aeruginosa (Pa) utilises quorum sensing
(QS) to mediate several virulence factors including growth in biofilms.
Intriguing in vitro data suggests QS signalling molecules can be “sensed” at
the epithelial surface via the T2R38 (bitter taste) receptor expressed on air-
way cilia (Lee RJ, et al. J Clin Invest. 2012;122:4145-59). Activation of this
receptor is predicted to lead to changes in ciliary beat frequency and nitric
oxide production, which may enhance bacterial clearance. Three common
polymorphisms exist in the gene coding for this receptor, altering the amino
acid sequence at positions 49, 262, and 296 and correlating with receptor
function; the functional allele has proline-alanine-valine (PAV) whereas the
non-functional allele has alanine-valine-isoleucine (AVI) at these residues.
In vitro response to QS molecules has been shown to be greatest in cells
with the PAV/PAV genotype. We hypothesised that the T2R38 receptor
may be important in host defence against Pa in people with cystic fibrosis
(CF) and that T2R38 genotype may therefore modify infection status and
clinical outcomes.