Stability of interleukin 8 and neutrophil elastase in bronchoalveolar lavage fluid following long-term storage

Changing Prevalence of Lower Airway Infections in Young Children with Cystic Fibrosis

Rationale: Historical studies suggest that airway infection in cystic fibrosis initiates with Staphylococcus aureus and Haemophilus influenzae, with later emergence of Pseudomonas aeruginosa. Aspergillus species are regarded as relatively infrequent, late-occurring infections.Objectives: To assess the prevalence and change in prevalence of early lower airway infections in a modern cohort of children with cystic fibrosis.Methods: All infants diagnosed with cystic fibrosis after newborn screening participating in the Australian Respiratory Early Surveillance Team for Cystic Fibrosis (AREST CF) cohort study between 2000 and 2018 were included. Participants prospectively underwent BAL at 3-6 months, 1 year, and annually up to 6 years of age. Lower airway infection prevalence was described. Changes in prevalence patterns were assessed longitudinally using generalized estimating equations controlling for age and repeated visits.Measurements and Main Results: A total of 380 infants underwent 1,759 BALs. The overall prevalence and median age of first acquisition of the most common infections were as follows: S. aureus, 11%, 2.5 years; P. aeruginosa, 8%, 2.4 years; Aspergillus species, 11%, 3.2 years; and H. influenzae, 9%, 3.1 years. During the study, a significant decrease in prevalence of P. aeruginosa (P < 0.001) and S. aureus (P < 0.001) was observed with a significant change toward more aggressive treatment. Prevalence of Aspergillus infections did not significantly change (P = 0.669).Conclusions: Aspergillus species and P. aeruginosa are commonly present in the lower airways from infancy. The decrease in prevalence of P. aeruginosa and S. aureus since 2000, coinciding with a more aggressive therapeutic approach, has resulted in Aspergillus becoming the most commonly isolated pathogen in young children. Further research is warranted to understand the implication of these findings.

Carotenoids and Markers of Oxidative Stress in Human Observational Studies and Intervention Trials: Implications for Chronic Diseases

Carotenoids include C30, C40 and C50 terpenoid-based molecules, many of which constitute coloured pigments. However, >1100 of these are known to occur in nature and only about a dozen are known to play a role in our daily diet. Carotenoids have received much attention due to their proposed health benefits, including reducing the incidence of chronic diseases, such as cardiovascular disease and diabetes. Many of these diseases are characterized by chronic inflammation co-occurring with oxidative stress, characterized by, for example, enhanced plasma F2-isoprostane concentrations, malondialdehyde, and 8-hydroxyguanosine. Though carotenoids can act as direct antioxidants, quenching, for example, singlet oxygen and peroxide radicals, an important biological function appears to rest also in the activation of the body's own antioxidant defence system, related to superoxide-dismutase, catalase, and glutathione-peroxidase expression, likely due to the interaction with transcription factors, such as nuclear-factor erythroid 2-related factor 2 (Nrf-2). Though mostly based on small-scale and observational studies which do not allow for drawing conclusions regarding causality, several supplementation trials with isolated carotenoids or food items suggest positive health effects. However, negative effects have also been reported, especially regarding beta-carotene for smokers. This review is aimed at summarizing the results from human observational studies/intervention trials targeting carotenoids in relation to chronic diseases characterized by oxidative stress and markers thereof.

The clinical significance of oropharyngeal cultures in young children with cystic fibrosis

In children with cystic fibrosis (CF) the associations between oropharyngeal swabs (OPSs) for detection of Pseudomonas and lung disease have not been evaluated.OPS and bronchoalveolar lavage (BAL) samples were obtained annually in children with CF from 2005 to 2017. OPS test characteristics were calculated using BAL as "gold standard". Results were related to lung inflammation (BAL neutrophil elastase and interleukin-8), structural lung disease (chest computed tomography PRAGMA-CF (Perth-Rotterdam Annotated Grid Morphometric Analysis for CF) scores), respiratory exacerbations and future detection of Pseudomonas on BAL.From 181 patients, 690 paired OPS-BAL cultures were obtained. Prevalence of Pseudomonas in BAL was 7.4%. OPS sensitivity was 23.0% and specificity was 91.4%, reducing the post-test probability for a positive BAL following a negative OPS to 6.3%. Pseudomonas on OPS was not associated with lung inflammation or respiratory exacerbations, but was weakly associated with current PRAGMA-CF %Disease score (p=0.043). Pseudomonas on BAL was associated with positive neutrophil elastase (OR 4.17, 95% CI 2.04-8.53; p<0.001), increased interleukin-8 (p<0.001), increased all baseline PRAGMA computed tomography scores (p<0.001), progression of PRAGMA computed tomography scores (p<0.05) and increased risk of respiratory exacerbations (incidence rate ratio 2.11, 95% CI 1.15-3.87; p=0.017).In children with CF OPSs only marginally change the probability of detecting lower airway Pseudomonas and are not associated with lung disease indices nor exacerbations risk.

The AREST CF experience in biobanking - More than just tissues, tubes and time

Research to further improve outcomes for people with CF is dependent upon well characterised, archived and accessible clinical specimens. The recent article by Beekman et al. published in Journal of Cystic Fibrosis summarised a scientific meeting at the 13th ECFS Basic Science Conference. This meeting discussed how well-annotated, clinical biobanks for CF could be established in Europe to meet the needs of therapeutic development. The Australian Respiratory Early Surveillance Team for Cystic Fibrosis (AREST CF) has conducted biobanking of CF research and clinical specimens since the late 1990s and is custodian of the most comprehensive paediatric CF biobank in the world that focuses on the first years of life. This short communication will describe the approach undertaken by AREST CF in establishing a clinical specimen biobank.

Alpha-1 Antitrypsin Mitigates the Inhibition of Airway Epithelial Cell Repair by Neutrophil Elastase

Neutrophil elastase (NE) activity is associated with many destructive lung diseases and is a predictor for structural lung damage in early cystic fibrosis (CF), which suggests normal maintenance of airway epithelium is prevented by uninhibited NE. However, limited data exist on how the NE activity in airways of very young children with CF affects function of the epithelia. The aim of this study was to determine if NE activity could inhibit epithelial homeostasis and repair and whether any functional effect was reversible by antiprotease alpha-1 antitrypsin (α1AT) treatment. Viability, inflammation, apoptosis, and proliferation were assessed in healthy non-CF and CF pediatric primary airway epithelial cells (pAECnon-CF and pAECCF, respectively) during exposure to physiologically relevant NE. The effect of NE activity on pAECCF wound repair was also assessed. We report that viability after 48 hours was significantly decreased by 100 nM NE in pAECnon-CF and pAECCF owing to rapid cellular detachment that was accompanied by inflammatory cytokine release. Furthermore, both phenotypes initiated an apoptotic response to 100 nM NE, whereas ≥ 50 nM NE activity significantly inhibited the proliferative capacity of cultures. Similar concentrations of NE also significantly inhibited wound repair of pAECCF, but this effect was reversed by the addition of α1AT. Collectively, our results demonstrate free NE activity is deleterious for epithelial homeostasis and support the hypothesis that proteases in the airway contribute directly to CF structural lung disease. Our results also highlight the need to investigate antiprotease therapies in early CF disease in more detail.

Matrix metalloproteinase activation by free neutrophil elastase contributes to bronchiectasis progression in early cystic fibrosis

Neutrophil elastase is the most significant predictor of bronchiectasis in early-life cystic fibrosis; however, the causal link between neutrophil elastase and airway damage is not well understood. Matrix metalloproteinases (MMPs) play a crucial role in extracellular matrix modelling and are activated by neutrophil elastase. The aim of this study was to assess if MMP activation positively correlates with neutrophil elastase activity, disease severity and bronchiectasis in young children with cystic fibrosis.Total MMP-1, MMP-2, MMP-7, MMP-9, tissue inhibitor of metalloproteinase (TIMP)-2 and TIMP-1 levels were measured in bronchoalveolar lavage fluid collected from young children with cystic fibrosis during annual clinical assessment. Active/pro-enzyme ratio of MMP-9 was determined by gelatin zymography. Annual chest computed tomography imaging was scored for bronchiectasis.A higher MMP-9/TIMP-1 ratio was associated with free neutrophil elastase activity. In contrast, MMP-2/TIMP-2 ratio decreased and MMP-1 and MMP-7 were not detected in the majority of samples. Ratio of active/pro-enzyme MMP-9 was also higher in the presence of free neutrophil elastase activity, but not infection. Across the study cohort, both MMP-9/TIMP-1 and active MMP-9 were associated with progression of bronchiectasis.Both MMP-9/TIMP-1 and active MMP-9 increased with free neutrophil elastase and were associated with bronchiectasis, further demonstrating that free neutrophil elastase activity should be considered an important precursor to cystic fibrosis structural disease.

Protease-antiprotease imbalances differ between Cystic Fibrosis patients' upper and lower airway secretions

BACKGROUND

Balanced levels of proteases and anti-proteases are essential in host defense systems. In CF patients' lungs, elevated protease/anti-protease-ratios contribute to damage of airway tissue and premature death with the inherited disease. Little is known about upper airway protease equilibrium in CF.

METHODS

Neutrophil elastase (NE), Secretory leukocyte protease inhibitor (SLPI), matrix metalloproteinase (MMP)9, tissue inhibitors of metalloproteinase (TIMP)1, cathepsin S (CTSS) and the corresponding cellular distribution were assessed in the nasal lavage (NL) and sputum of 40 CF patients.

RESULTS

Concentrations of all proteases and anti-proteases were markedly higher in sputum than in NL (NE: 10-fold, SLPI: 5000-fold). Interestingly, the NE/SLPI ratio was 726-fold higher in NL compared to sputum, while the MMP9/TIMP1 ratio was 4.5-fold higher in sputum compared to NL.

DISCUSSION

This first study to compare protease/anti-protease networks of CF upper and lower airways by NL and sputum reveals substantial differences between both compartments' immunological responses. This finding may have implications for sinonasal and pulmonary treatment, possibly leading to new therapeutic approaches.

Determinants of culture success in an airway epithelium sampling program of young children with cystic fibrosis

AIM OF THE STUDY

The bronchial brushing technique presents an opportunity to establish a gold standard in vitro model of Cystic Fibrosis (CF) airway disease. However, unique obstacles exist when establishing CF airway epithelial cells (pAECCF). We aimed to identify determinants of culture success through retrospective analysis of a program of routinely brushing children with CF.

MATERIALS AND METHODS

Anaesthetised children (CF and non-CF) had airway samples taken which were immediately processed for cell culture. Airway data for the CF cohort was obtained from clinical records and the AREST CF database.

RESULTS

Of 260 brushings processed for culture, 114 (43.8%) pAECCF successfully cultured to passage one (P1) and 63 (24.2% of total) progressed to passage two (P2). However, >80% of non-CF specimens (pAECnon-CF) cultured to P2 from similar cell numbers. Within the CF cohort, specimens successfully cultured to P2 had a higher initial cell count and lower proportion of severe CF mutation phenotype than those that did not proliferate beyond initial seeding. Elevated airway IL-8 concentration was also negatively associated with culture establishment. Contamination by opportunistic pathogens was observed in 81 (31.2% of total) cultures and brushings from children with lower respiratory tract infections were more likely to co-culture contaminating flora.

CONCLUSIONS

Lower passage rates of pAECCF cultures uniquely contrasts with pAECnon-CF despite similar cell numbers. An equivalent establishment rate of CF nasal epithelium reported elsewhere, significant associations to CFTR mutation phenotype, elevated airway IL-8 and opportunistic pathogens all suggest this is likely related to the CF disease milieu.

Translational research in pediatrics III: bronchoalveolar lavage

The role of flexible bronchoscopy and bronchoalveolar lavage (BAL) for the care of children with airway and pulmonary diseases is well established, with collected BAL fluid most often used clinically for microbiologic pathogen identification and cellular analyses. More recently, powerful analytic research methods have been used to investigate BAL samples to better understand the pathophysiological basis of pediatric respiratory disease. Investigations have focused on the cellular components contained in BAL fluid, such as macrophages, lymphocytes, neutrophils, eosinophils, and mast cells, as well as the noncellular components such as serum molecules, inflammatory proteins, and surfactant. Molecular techniques are frequently used to investigate BAL fluid for the presence of infectious pathologies and for cellular gene expression. Recent advances in proteomics allow identification of multiple protein expression patterns linked to specific respiratory diseases, whereas newer analytic techniques allow for investigations on surfactant quantification and function. These translational research studies on BAL fluid have aided our understanding of pulmonary inflammation and the injury/repair responses in children. We review the ethics and practices for the execution of BAL in children for translational research purposes, with an emphasis on the optimal handling and processing of BAL samples.

Soluble inflammation markers in nasal lavage from CF patients and healthy controls

BACKGROUND

CF sinonasal and bronchial mucosa reveal identical ion channel defects. Nasal Lavage (NL) allows non-invasive repeated sampling of airway surface liquid. We compared inflammatory mediators in NL from CF-patients and healthy controls, and in CF in relation to sinonasal pathogen colonization.

METHODS

From 40 CF-patients (mean age 21.8yrs, SD 11.8yrs.) and 52 healthy controls (mean age 31.9yrs., SD 13.7yrs.) NL-fluid (10ml/nostril) concentrations of MPO, IL-8, IL-17A, sICAM-1, IL-1β, IL-6, TNF-α, IL-10 and IL-5 were determined using cytometric bead arrays for flow cytometry.

RESULTS

CF-patients showed significantly higher MPO-concentrations in NL-fluid and higher IL-8-levels (n.s.) than controls. MPO, IL-8, IL-17A, sICAM-1, IL-1β and IL-6 were significantly more often detectable in CF-patients than in controls. CF-patients with S. aureus colonization in both upper and lower airways had significantly elevated MPO and IL-8 levels in NL-fluid compared to S. aureus negatives.

CONCLUSION

NL-fluid differed substantially between CF-patients and healthy controls with most promising results for IL-8 and MPO, a primarily in CF-NL assessed mediator. Further studies are required to assess effects of sample collection and processing on concentrations of inflammatory markers and to evaluate potentials of NL analysis in research and clinical routine.