Direct detection of N-acylhomoserine lactones in cystic fibrosis sputum

Abstract

Pseudomonas aeruginosa and Burkholderia cepacia cause destructive lung disease in cystic fibrosis (CF) patients. Both pathogens emploỳ quorum sensing', i.e. cell-to-cell communication, via diffusible N-acyl-L-homoserine lactone (AHL) signal molecules, to regulate the production of a number of virulence determinants in vitro. However, to date, evidence that quorum sensing systems are functional and play a role in vivo is lacking. This study presents the first direct evidence for the presence of AHLs in CF sputum. A total of 42 samples from 25 CF patients were analysed using lux-based Escherichia coli AHL biosensors. AHLs were detected in sputum from patients colonised by P. aeruginosa or B. cepacia but not Staphylococcus aureus. Furthermore, using liquid chromatography-mass spectrometry and thin layer chromatography, we confirmed the presence of N-hexanoylhomoserine lactone and N-(3-oxododecanoyl)homoserine lactone respectively in sputum samples from patients colonised by P. aeruginosa. ß

Pseudomonal airway colonisation: risk factor for bronchiolitis obliterans syndrome after lung transplantation?

“…aeruginosa has evolved into one of the most common and refractory nosocomial pathogens of immunocompromised patients due to its resistance to many antibiotics and a pre-dilection to colonise surfaces, especially injured epithelium, in a biofilm form, orchestrated by intercellular 'quorumsensing' signalling molecules (QSM) [34,35]. The endobronchial presence of QSM was demonstrated in both colonised CF patients [36][37][38][39] and in clinically stable, though possibly colonised, LTx recipients [40]. QSM have an intrinsic immunomodulatory capacity resulting in suppressed T-cell proliferation, neutrophil chemotaxis and chemokine (especially IL-8) or cytokine release from bronchial epithelial cells [41][42][43][44].…”

Proteomic analysis of Pseudomonas aeruginosa grown under magnesium limitation

“…These results provide a strong functional correlation between LPS modification enzyme levels and the LPS structural modifications seen in this environmental condition, confirming the validity of ICAT analysis. A number of P. aeruginosa virulence factors are regulated by quorum sensing bacterial communication via small molecule signals N-(3-oxododecanoyl)-L-homoserine lactone (3OC12-HSL) and N-butyryl-L-homoserine lactone (C4-HSL) [24,25,26,13]. The quantitative protein profiles indicated that magnesium limitation induced several quorum sensing proteins including the 3OC12-HSL synthase LasI [27] and the starvation and general stress-response regulator RelA [28,29] (Table 2).…”

Mouse and Human Cell Activation by N -Dodecanoyl- dl -Homoserine Lactone, a Chromobacterium violaceum Autoinducer

“…In P. aeruginosa, two acyl-homoserine lactone-based systems, the las and rhl systems, have been described (10,12,14). Apart from its quorum-sensing function, the P. aeruginosa N-3-oxododecanoyl-homoserine lactone (3-oxo-C 12 -HSL) autoinducer has been suggested to modulate the immune responses of the infected host.…”