Longitudinal changes in the cystic fibrosis airway microbiota with time and treatment.

BACKGROUND: Whether there is any benefit in integrating culture-independent molecular analysis of the lower airway microbiota of people with cystic fibrosis into clinical care is unclear. This study determined the longitudinal trajectory of the microbiota and if there were microbiota characteristics that corresponded with response to treatment or predicted a future pulmonary exacerbation. METHODS: At least one sputum sample was collected from 149 participants enrolled in this prospective longitudinal multi-centre study and total bacterial density and microbiota community measurements were determined and compared with clinical parameters. RESULTS: In 114 participants with paired samples when clinically stable, ∼8 months apart, the microbiota remained conserved between timepoints, regardless of whether participants received acute intravenous antibiotic treatment or not. In 62 participants, who presented with an acute exacerbation, a decrease in community richness correlated best with patient response to antibiotic treatment. Analysis of baseline samples from 30 participants who exacerbated within 4 months of their stable sample being collected and 72 participants who remained stable throughout the study showed that community characteristics such as lower richness at baseline may be predictive of an exacerbation in addition to several clinical parameters. However, lasso regression analysis indicated that only lung function (p = 0.014) was associated with a future exacerbation. CONCLUSIONS: The airway microbiota remains stable over periods <1 year with modest shifts related to treatment apparent which might provide some additional insights to patient-level measurements.

Influence of azithromycin and allograft rejection on the post-lung transplant microbiota.

BACKGROUND: Alterations in the lung microbiota may drive disease development and progression in patients with chronic respiratory diseases. Following lung transplantation (LTx), azithromycin is used to both treat and prevent chronic lung allograft dysfunction (CLAD). The objective of this study was to determine the association between azithromycin use, CLAD, acute rejection, airway inflammation, and bacterial microbiota composition and structure after LTx. METHODS: Bronchoalveolar lavage samples (n = 219) from 69 LTx recipients (azithromycin, n = 32; placebo, n = 37) from a previously conducted randomized placebo-controlled trial with azithromycin were analyzed. Samples were collected at discharge, 1, and 2 years following randomization and at CLAD diagnosis. Bacterial microbial community composition and structure was determined using 16S ribosomal RNA gene sequencing and associated with clinically important variables. RESULTS: At discharge and following 1 and 2 years of azithromycin therapy, no clear differences in microbial community composition or overall diversity were observed. Moreover, no changes in microbiota composition were observed in CLAD phenotypes. However, acute rejection was associated with a reduction in community diversity (p = 0.0009). Significant correlations were observed between microbiota composition, overall diversity, and levels of inflammatory cytokines in bronchoalveolar lavage, particularly CXCL8. CONCLUSIONS: Chronic azithromycin usage did not disturb the bacterial microbiota. However, acute rejection episodes were associated with bacterial dysbiosis.

Assessment of stability and fluctuations of cultured lower airway bacterial communities in people with cystic fibrosis.

BACKGROUND: Routine clinical culture detects a subset of the cystic fibrosis (CF) airways microbiota based on culture-independent (molecular) methods. This study aimed to determine how extended sputum culture of viable bacteria changes over time in relation to clinical status and predicts exacerbations. METHODS: Sputa from patients at a baseline stable and up to three subsequent time-points were analysed by extended-quantitative culture; aerobe/anaerobe densities, ecological indexes and community structure were assessed together with clinical outcomes. RESULTS: Eighty patients were prospectively recruited. Sputa were successfully collected and cultured at 199/267 (74.5%) study visits. Eighty-two sputa from 25 patients comprised a complete sample-set for longitudinal analyses. Bacterial density, ecological indexes and clinical outcomes were unchanged in 18 patients with three sequential stable visits. Conversely, in 7 patients who had an exacerbation, total bacterial and aerobe densities differed over four study visits (P < .001) with this difference particularly apparent between the baseline visit and completion of acute antibiotic treatment where a decrease in density was observed. Bacterial communities were more similar within than between patients but stable patients had the least variation in community structure over time. Using logistic regression in a further analysis, baseline features in 37 patients without compared to 15 patients with a subsequent exacerbation showed that clinical measures rather than bacterial density or ecological indexes were independent predictors of an exacerbation. CONCLUSIONS: Greater fluctuation in the viable bacterial community during treatment of an exacerbation than between stable visits was observed. Extended-quantitative culture did not provide prognostic information of a future exacerbation.

Proteomic profile of cystic fibrosis sputum cells in adults chronically infected with Pseudomonas aeruginosa.

Lung disease is the main cause of morbidity and mortality in cystic fibrosis (CF), and involves chronic infection and perturbed immune responses. Tissue damage is mediated mostly by extracellular proteases, but other cellular proteins may also contribute to damage through their effect on cell activities and/or release into sputum fluid by means of active secretion or cell death.We employed MudPIT (multidimensional protein identification technology) to identify sputum cellular proteins with consistently altered abundance in adults with CF, chronically infected with Pseudomonas aeruginosa, compared with healthy controls. Ingenuity Pathway Analysis, Gene Ontology, protein abundance and correlation with lung function were used to infer their potential clinical significance.Differentially abundant proteins relate to Rho family small GTPase activity, immune cell movement/activation, generation of reactive oxygen species, and dysregulation of cell death and proliferation. Compositional breakdown identified high abundance of proteins previously associated with neutrophil extracellular traps. Furthermore, negative correlations with lung function were detected for 17 proteins, many of which have previously been associated with lung injury.These findings expand our current understanding of the mechanisms driving CF lung disease and identify sputum cellular proteins with potential for use as indicators of disease status/prognosis, stratification determinants for treatment prescription or therapeutic targets.

Lung Clearance Index in Adults and Children With Cystic Fibrosis.

BACKGROUND: Lung clearance index (LCI) has good clinimetric properties and an acceptable feasibility profile as a surrogate end point in cystic fibrosis (CF). Although most studies to date have been in children, increasing numbers of adults with CF also have normal spirometric findings. Further study of LCI as an end point in adults with CF is required. Therefore, the purpose of this study was to determine the clinimetric properties of LCI across the age range of people with CF. METHODS: Clinically stable adults and children with CF and age-matched healthy control subjects were recruited. RESULTS: LCI and spirometry data for 110 subjects with CF and 61 control subjects were collected at a stable visit. The CF Questionnaire-Revised (CFQ-R) was completed by 80 of 110 subjects with CF. Fifty-six subjects with CF completed a second stable visit. The LCI coefficient of variation percent was 4.1% in adults and 6.3% in children with CF. The coefficient of repeatability of LCI was 1.2 in adults and 1.3 in children. In both adults and children, LCI (area under the receiving operator characteristic curve [AUCROC] = 0.93 and 0.84, respectively) had greater combined sensitivity and specificity to discriminate between people with CF and control subjects when compared with FEV1 (AUCROC = 0.88 and 0.60, respectively) and forced expiratory flow at 25% to 75% of the curve (AUCROC = 0.87 and 0.68, respectively). LCI correlated significantly with the CFQ-R treatment burden in adults (r = -0.37; P < .01) and children (r = -0.50; P < .01). Washout tests were successful in 90% of subjects with CF and were perceived as comfortable and easy to perform in both adults and children. CONCLUSIONS: These data support the use of LCI as a surrogate outcome measure in CF clinical trials in adults as well as in children.

Lack of Association Between Haptoglobin Phenotype and Cystic Fibrosis Outcomes.

Haptoglobin (Hp), a heme-Iron chelator, has different isoforms which are associated with variable tendency toward infections: Hp 1-1, Hp 2-1, and Hp 2-2. Cystic fibrosis (CF) outcomes are variable and influenced by genetic and environmental factors. The aim of this study was to determine whether Hp phenotype influenced disease severity in CF. One hundred forty-two CF patients from two centers were analyzed for Haptoglobin phenotype using gel electrophoresis of hemoglobin enriched serum. Clinical and microbiological data including bacterial colonization status, lung function, presence of CF-related diabetes and liver disease, rate of exacerbation, and mortality were compared between Hp phenotype groups. We found a trend toward less mucoid PA among Hp 2-2 (20.4 %) compared with Hp 1-1 and Hp 2-1 individuals (33.3 %), p = 0.317. Hp 2-2 individuals also had less antibiotic courses, and lower inflammatory markers without statistical significance. Haptoglobin phenotype is unlikely to be an important modifier of CF phenotype.

Reduced bacterial colony count of anaerobic bacteria is associated with a worsening in lung clearance index and inflammation in cystic fibrosis.

Anaerobic bacteria have been identified in abundance in the airways of cystic fibrosis (CF) subjects. The impact their presence and abundance has on lung function and inflammation is unclear. The aim of this study was to investigate the relationship between the colony count of aerobic and anaerobic bacteria, lung clearance index (LCI), spirometry and C-Reactive Protein (CRP) in patients with CF. Sputum and blood were collected from CF patients at a single cross-sectional visit when clinically stable. Community composition and bacterial colony counts were analysed using extended aerobic and anaerobic culture. Patients completed spirometry and a multiple breath washout (MBW) test to obtain LCI. An inverse correlation between colony count of aerobic bacteria (n = 41, r = -0.35; p = 0.02), anaerobic bacteria (n = 41, r = -0.44, p = 0.004) and LCI was observed. There was an inverse correlation between colony count of anaerobic bacteria and CRP (n = 25, r = -0.44, p = 0.03) only. The results of this study demonstrate that a lower colony count of aerobic and anaerobic bacteria correlated with a worse LCI. A lower colony count of anaerobic bacteria also correlated with higher CRP levels. These results indicate that lower abundance of aerobic and anaerobic bacteria may reflect microbiota disruption and disease progression in the CF lung.

Carotenoids and co-antioxidants in age-related maculopathy: design and methods.

Age-related macular degeneration (AMD), is the leading cause of blind registration in the Western World among individuals 65 years or older. Early AMD, a clinical state without overt functional loss, is said to be present clinically when yellowish deposits known as drusen and/or alterations of fundus pigmentation are seen in the macular retina. Although the etiopathogenesis of AMD remains uncertain, there is a growing body of evidence in support of the view that cumulative oxidative damage plays a causal role. Appropriate dietary antioxidant supplementation is likely to be beneficial in maintaining visual function in patients with AMD, and preventing or delaying the progression of early AMD to late AMD. The Carotenoids in Age-Related Maculopathy (CARMA) Study is a randomized and double-masked clinical trial of antioxidant supplementation versus placebo in 433 participants with either early AMD features of sufficient severity in at least one eye or any level of AMD in one eye with late AMD (neovascular AMD or central geographic atrophy) in the fellow eye. The aim of the CARMA Study is to investigate whether lutein and zeaxanthin, in combination with co-antioxidants (vitamin C, E, and zinc), has a beneficial effect on visual function and/or prevention of progression from early to late stages of disease. The primary outcome is improved or preserved distance visual acuity at 12 months. Secondary outcomes include improved or preserved interferometric acuity, contrast sensitivity, shape discrimination ability, and change in AMD severity as monitored by fundus photography. This article outlines the CARMA Study design and methodology, including its rationale.