Alison Dicker

Neutrophil Elastase Activity is Associated with Exacerbations and Lung Function Decline in Bronchiectasis

Rationale: Sputum neutrophil elastase and serum desmosine, which is a linked marker of endogenous elastin degradation, are possible biomarkers of disease severity and progression in bronchiectasis. This study aimed to determine the association of elastase activity and desmosine with exacerbations and lung function decline in bronchiectasis. Methods: This was a single‐center prospective cohort study using the TAYBRIDGE (Tayside Bronchiectasis Registry Integrating Datasets, Genomics, and Enrolment into Clinical Trials) registry in Dundee, UK. A total of 433 patients with high‐resolution computed tomography‐confirmed bronchiectasis provided blood samples for desmosine measurement, and 381 provided sputum for baseline elastase activity measurements using an activity‐based immunosassay and fluorometric substrate assay. Candidate biomarkers were tested for their relationship with cross‐sectional markers of disease severity, and with future exacerbations, mortality and lung function decline over 3 years. Measurement and Main Results: Elastase activity in sputum was associated with the bronchiectasis severity index (r = 0.49; P < 0.0001) and was also correlated with the Medical Research Council dyspnea score (r = 0.34; P < 0.0001), FEV1% predicted (r = −0.33; P < 0.0001), and the radiological extent of bronchiectasis (r = 0.29; P < 0.0001). During a 3‐year follow‐up, elevated sputum elastase activity was associated with a higher frequency of exacerbations (P < 0.0001) but was not independently associated with mortality. Sputum elastase activity was independently associated with FEV1 decline (&bgr; coefficient, −0.139; P = 0.001). Elastase showed good discrimination for severe exacerbations with an area under the curve of 0.75 (95% confidence interval [CI], 0.72‐0.79) and all‐cause mortality (area under the curve, 0.70; 95% CI, 0.67‐0.73). Sputum elastase activity increased at exacerbations (P = 0.001) and was responsive to treatment with antibiotics. Desmosine was correlated with sputum elastase (r = 0.42; P < 0.0001) and was associated with risk of severe exacerbations (hazard ratio 2.7; 95% CI, 1.42‐5.29; P = 0.003) but not lung function decline. Conclusions: Sputum neutrophil elastase activity is a biomarker of disease severity and future risk in adults with bronchiectasis.

Neutrophil extracellular traps are associated with disease severity and microbiota diversity in patients with chronic obstructive pulmonary disease

&NA; Figure. No caption available. Background: Neutrophil extracellular traps (NETs) have been observed in the airway in patients with chronic obstructive pulmonary disease (COPD), but their clinical and pathophysiologic implications have not been defined. Objective: We sought to determine whether NETs are associated with disease severity in patients with COPD and how they are associated with microbiota composition and airway neutrophil function. Methods: NET protein complexes (DNA‐elastase and histone‐elastase complexes), cell‐free DNA, and neutrophil biomarkers were quantified in soluble sputum and serum from patients with COPD during periods of disease stability and during exacerbations and compared with clinical measures of disease severity and the sputum microbiome. Peripheral blood and airway neutrophil function were evaluated by means of flow cytometry ex vivo and experimentally after stimulation of NET formation. Results: Sputum NET complexes were associated with the severity of COPD evaluated by using the composite Global Initiative for Obstructive Lung Disease scale (P < .0001). This relationship was due to modest correlations between NET complexes and FEV1, symptoms evaluated by using the COPD assessment test, and higher levels of NET complexes in patients with frequent exacerbations (P = .002). Microbiota composition was heterogeneous, but there was a correlation between NET complexes and both microbiota diversity (P = .009) and dominance of Haemophilus species operational taxonomic units (P = .01). Ex vivo airway neutrophil phagocytosis of bacteria was reduced in patients with increased sputum NET complexes. Consistent results were observed regardless of the method of quantifying sputum NETs. Failure of phagocytosis could be induced experimentally by incubating healthy control neutrophils with soluble sputum from patients with COPD. Conclusion: NET formation is increased in patients with severe COPD and associated with more frequent exacerbations and a loss of microbiota diversity.

Genetic mannose binding lectin deficiency is associated with airway microbiota diversity and reduced exacerbation frequency in COPD

Background In cystic fibrosis and bronchiectasis, genetic mannose binding lectin (MBL) deficiency is associated with increased exacerbations and earlier mortality; associations in COPD are less clear. Preclinical data suggest MBL interferes with phagocytosis of Haemophilus influenzae, a key COPD pathogen. We investigated whether MBL deficiency impacted on clinical outcomes or microbiota composition in COPD. Methods Patients with COPD (n=1796) underwent MBL genotyping; linkage to health records identified exacerbations, lung function decline and mortality. A nested subcohort of 141 patients, followed for up to 6 months, was studied to test if MBL deficiency was associated with altered sputum microbiota, through 16S rRNA PCR and sequencing, or airway inflammation during stable and exacerbated COPD. Findings Patients with MBL deficiency with COPD were significantly less likely to have severe exacerbations (incidence rate ratio (IRR) 0.66, 95% CI 0.48 to 0.90, p=0.009), or to have moderate or severe exacerbations (IRR 0.77, 95% CI 0.60 to 0.99, p=0.047). MBL deficiency did not affect rate of FEV1 decline or mortality. In the subcohort, patients with MBL deficiency had a more diverse lung microbiota (p=0.008), and were less likely to be colonised with Haemophilus spp. There were lower levels of airway inflammation in patients with MBL deficiency. Interpretation Patients with MBL deficient genotype with COPD have a lower risk of exacerbations and a more diverse lung microbiota. This is the first study to identify a genetic association with the lung microbiota in COPD.

The past decade in bench research into pulmonary infectious diseases: What do clinicians need to know?

Respiratory infections are primarily treated with antibiotics, drugs that are mostly inexpensive and have been widely available since the 1940s and 1950s. Nevertheless, despite antibiotics, the burden of disease in pneumonia, bronchiectasis, cystic fibrosis, COPD and rare respiratory infections remains exceptionally high. There is an urgent need for translational studies to develop new treatments or new biomarkers to improve outcomes in these conditions. The ‘translational gaps’ between bench science and clinical practice are particularly challenging in respiratory infections. This is partly due to the poor representativeness of animal models of infection to human disease, and a long‐term lack of investment into pulmonary infection research.

Profile of the ProAxsis active neutrophil elastase immunoassay for precision medicine in chronic respiratory disease

ABSTRACT Introduction: Neutrophil elastase (NE) is a 29kDa serine protease released from the azurophilic granules of neutrophils. It may be directly involved in the pathogenesis and disease progression in cystic fibrosis, bronchiectasis and COPD through the degradation of airway elastin and by impairing host defence. Areas covered: Measurement of NE activity has emerged as a promising biomarker strategy in inflammatory lung disease. The authors review studies where NE activity has been linked with clinical outcomes such as lung function decline, exacerbation frequency or other cross-sectional and longitudinal markers of disease severity. In this article the evidence for NE measurement, and the strengths and weaknesses of a commercially available immunoassay which can specifically detect NE activity in human biological samples such as sputum and bronchoalveolar lavage are reviewed. Expert commentary: NE is a promising biomarker for stratifying severity disease. NE also appears to be responsive to antibiotic and other treatments, potentially therefore allowing it to be used as an indicator of treatment response in clinical trials.

Disbiosis microbiana en las bronquiectasias y la fibrosis quística

Identification and treatment of bacterial infection is central to our management of bronchiectasis, whether caused by cystic fibrosis or by other underlying disorders.1 The pathophysiology of these diseases is understood to be a vicious cycle of infection, inflammation, and tissue damage which we attempt to break by eradicating or suppressing pathogenic bacteria using inhaled, oral, and intravenous antibiotics.1,2 Our understanding of this pathophysiology is being changed, however, by developments in molecular microbiology and genomics. Non-culture based methods of identifying bacteria, viruses, and fungi in the lungs of CF and bronchiectasis patients is a rapidly expanding field of research. By utilising highthroughput sequencing platforms to target conserved regions of DNA, such as the bacterial 16S rRNA gene, identification of the bacteria present in sputum, bronchoalveolar lavage (BAL) or upper airway swabs is possible without the need for microbial culture.3There is potential to identify potential pathogens more sensitively, to identify non-culturable bacteria, to understand “phenotypes” of disease based on microbiota profiles, and to better understand the impact of treatment on microbes and the host response. Cystic fibrosis is perhaps the most intensively studied condition with respect to the lung microbiome. Recent data show that the upper airway microbiome starts to change in CF infants in the first year of life, with overgrowth of Staphylococcus even in children without antibiotic treatment.4,5 As disease progresses, the proteobacteria increase in relative abundance, with the emergence of “traditional” CF pathogens such as Pseudomonas spp. Longitudinal studies have found that the lung microbiota is stable over time, at least in the short term, and does not vary significantly during exacerbations.6 One of the largest studies in CF patients to date (n=269) confirmed patterns of microbiota diversity observed in other smaller-scale studies; dysbiosis (a reduction in microbiota diversity with dominance of one or a few genera) is associated with more severe disease, age, and increasing antibiotic use.7 A subset of genera, namely Veillonella, Burkholderia, Prevotella, Streptococcus,