Dubhfeasa Slattery

The Role of Short-Chain Fatty Acids, Produced by Anaerobic Bacteria, in the Cystic Fibrosis Airway

RATIONALE Anaerobic bacteria are present in large numbers in the airways of people with cystic fibrosis (PWCF). In the gut, anaerobes produce short-chain fatty acids (SCFAs) that modulate immune and inflammatory processes. OBJECTIVES To investigate the capacity of anaerobes to contribute to cystic fibrosis (CF) airway pathogenesis via SCFAs. METHODS Samples of 109 PWCF were processed using anaerobic microbiological culture with bacteria present identified by 16S RNA sequencing. SCFA levels in anaerobic supernatants and bronchoalveolar lavage (BAL) were determined by gas chromatography. The mRNA and/or protein expression of two SCFA receptors, GPR41 and GPR43, in CF and non-CF bronchial brushings and 16HBE14o(-) and CFBE41o(-) cells were evaluated using reverse transcription polymerase chain reaction, Western blot analysis, laser scanning cytometry, and confocal microscopy. SCFA-induced IL-8 secretion was monitored by ELISA. MEASUREMENTS AND MAIN RESULTS Fifty-seven (52.3%) of 109 PWCF were anaerobe positive. Prevalence increased with age, from 33.3% to 57.7% in PWCF younger (n = 24) and older (n = 85) than 6 years of age. All evaluated anaerobes produced millimolar concentrations of SCFAs, including acetic, propionic, and butyric acids. SCFA levels were higher in BAL samples of adults than in those of children. GPR41 levels were elevated in CFBE41o(-) versus 16HBE14o(-) cells; CF versus non-CF bronchial brushings; and 16HBE14o(-) cells after treatment with cystic fibrosis transmembrane conductance regulator inhibitor CFTR(inh)-172, CF BAL, or inducers of endoplasmic reticulum stress. SCFAs induced a dose-dependent and pertussis toxin-sensitive IL-8 response in bronchial epithelial cells, with a higher production of IL-8 in CFBE41o(-) than in 16HBE14o(-) cells. CONCLUSIONS This study illustrates that SCFAs contribute to excessive production of IL-8 in CF airways colonized with anaerobes via up-regulated GPR41.

Outcome in patients with cystic fibrosis liver disease

BACKGROUND Liver disease is an important complication in CF. AIMS To determine if CFLD is a risk factor for mortality in CF, and which baseline characteristics predict all-cause mortality. METHODS Irish children with CFLD, and their age and gender matched controls were enrolled at baseline and reviewed after 10years to determine which characteristics predict mortality. RESULTS 72/84 (85.71%) participants were followed, (mean age Cases 21.71yrs SD 6.5, CF controls 23.62 SD 5.6, 22 (61%) males), with no difference in duration of follow-up. Nineteen participants (26.4%) died, 38.9% (14/36) with CFLD and 13.89% (5/36) CF controls (Odds Ratio (OR) 3.94 95% CI:1.23-12.56 p=0.005). In logistic regression, liver disease (OR 4.28 95% CI 1.07-17.16) female gender (OR 12.25 95% CI 2.37-63.24), reduced pulmonary function, (OR 5.11 95% CI 1.09-23.81) were each independent risk factors for mortality in CF. CONCLUSIONS Liver disease is an independent risk factor for mortality in CF.