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

An optimized method of extracting and quantifying active Neutrophil serine proteases from human whole blood cells

Purpose

Neutrophil serine proteases (NSPs) are implicated in numerous inflammatory diseases. Thus, a robust methodology to monitor and quantify NSPs is important to study disease progression and evaluate the effect of pharmacological interventions. A comparison of the various methods used to extract NSPs from neutrophil granulocytes has not been published, providing the impetus to conduct this method optimization and comparison study.

Methods

Two NSP recovery methodologies were evaluated on samples from five human donors: zymosan stimulation and cell pellet extraction. For the zymosan stimulation method, 1 mL donor blood was added to zymosan and samples were incubated at 37°C for 30 min while shaking. Samples were then centrifuged, and the plasma was collected for quantitation of NSP activity. For the cell pellet extraction procedure, 2 mL whole blood samples were centrifuged into white blood cell pellets following red blood cell lysis. To each pellet, three sequential lysis steps were performed using either 0.05% Nonidet P-40 Substitute (NP40) or 0.02% Triton X-100 lysis buffers under agitation followed by centrifugation. NSP activities were quantified using an exogenous peptide substrate specific to each of the three NSPs being analyzed: neutrophil elastase, cathepsin G, and proteinase 3.

Results and discussion

The zymosan stimulation method resulted in lower recovery of active NSPs and was unable to stimulate significant release of active cathepsin G. In contrast, the NP40 pellet extraction method showed consistent inter-donor NSP release with greater recoveries of active NSPs than the Triton method or the zymosan stimulation method. Overall, the pellet extraction procedure provided 13.3-fold greater recovery of active neutrophil elastase, 283-fold greater recovery of active cathepsin G, and 2.9-fold greater recovery of active proteinase 3 than the zymosan method.

Conclusion

The NP40 cell pellet extraction method resulted in greater extraction of active NSPs compared to the other methods investigated here, which may allow for a more accurate and complete biomarker profile when evaluating human clinical samples.

Pathophysiology of Bronchiectasis

Bronchiectasis is a complex, heterogeneous disorder defined by both a radiological abnormality of permanent bronchial dilatation and a clinical syndrome. There are multiple underlying causes including severe infections, mycobacterial disease, autoimmune conditions, hypersensitivity disorders, and genetic conditions. The pathophysiology of disease is understood in terms of interdependent concepts of chronic infection, inflammation, impaired mucociliary clearance, and structural lung damage. Neutrophilic inflammation is characteristic of the disease, with elevated levels of harmful proteases such as neutrophil elastase associated with worse outcomes. Recent data show that neutrophil extracellular trap formation may be the key mechanism leading to protease release and severe bronchiectasis. Despite the dominant of neutrophilic disease, eosinophilic subtypes are recognized and may require specific treatments. Neutrophilic inflammation is associated with elevated bacterial loads and chronic infection with organisms such as Pseudomonas aeruginosa. Loss of diversity of the normal lung microbiota and dominance of proteobacteria such as Pseudomonas and Haemophilus are features of severe bronchiectasis and link to poor outcomes. Ciliary dysfunction is also a key feature, exemplified by the rare genetic syndrome of primary ciliary dyskinesia. Mucus symptoms arise through goblet cell hyperplasia and metaplasia and reduced ciliary function through dyskinesia and loss of ciliated cells. The contribution of chronic inflammation, infection, and mucus obstruction leads to progressive structural lung damage. The heterogeneity of the disease is the most challenging aspect of management. An understanding of the pathophysiology of disease and their biomarkers can help to guide personalized medicine approaches utilizing the concept of "treatable traits."

ERS International Congress 2020: highlights from the Respiratory Infections assembly

In the coronavirus disease 2019 (COVID-19) pandemic year 2020, the 30th European Respiratory Society (ERS) International Congress took place for the first time in a fully virtual format. Despite the challenging nature of the task to create and deliver an online event of this size and scope, it turned out to be a great success, welcoming over 33 000 delegates to the specially designed online platform and offering more than 450 scientific and educational sessions. Somewhat predictably, this year's ERS International Congress dedicated a full day to the topic of COVID-19, highlighting that infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a respiratory disease that is particularly important this year. In this article, the Early Career Members of the Assembly 10 (Respiratory Infections and Tuberculosis) review some of the most interesting sessions including presentations and posters on respiratory infections and tuberculosis that were deemed as important.

This is a comprehensive summary of several interesting sessions from #ERSCongress 2020 including presentations and posters on respiratory infections and tuberculosis that were deemed as importanthttps://bit.ly/2OtrYXH

Sputum and salivary protein biomarkers and point-of-care biosensors for the management of COPD

Chronic obstructive pulmonary disease (COPD) has become one of the most fatal diseases of the century considering mortality and morbidity levels worldwide. This disease is an inflammatory response to environmental stress and tobacco smoking. Although spirometry is the gold-standard diagnostic test administrated in primary and secondary care, it often exhibits low accuracy in cases of predicting disease worsening and possible bias due to the operator, patient, and conditions. Recent developments in proteomics research suggest that the presence of protein biomarkers can aid in the accurate diagnosis and prediction of disease outcomes. This review presents the cutting-edge research progress in the area of protein biomarkers towards the management of COPD. The literature review was confined to protein biomarkers in saliva and sputum because testing these bodily fluids shows great promise for point-of-care (POC) testing due to its practicality, non-invasiveness and inexpensive handling and sampling. Although it is conclusive that more studies on sputum and saliva are needed, this review studies the promising clinical value of interleukin (IL)-6 and IL-8, matrix metalloproteinase (MMP)-8 and MMP-9, C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-α), and neutrophil elastase (NE). Following the critical analysis of salivary and sputum biomarkers, the recent development of POC biosensors for the multiplexed detection of biomarkers is also reported. Overall, the review aims to explore the possibility for the future development of POC sensors for chronic lung disease management utilizing clinically relevant biomarkers in saliva and sputum.

Neutrophil elastase as a biomarker for bacterial infection in COPD

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is predominantly associated with neutrophilic inflammation. Active neutrophil elastase (NE) is a serine proteinase, secreted by neutrophils, in response to inflammation and pathogen invasion. We sought to investigate if NE could be used as a biomarker for bacterial infection in patients with COPD.

METHODS

NE was quantified using ProteaseTag® Active NE Immunoassay (ProAxsis, Belfast) from the sputum of COPD subjects at stable state, exacerbation and 2 weeks post treatment visit.

RESULTS

NE was measured in 90 samples from 30 COPD subjects (18 males) with a mean (range) age of 65 (45-81) years and mean (SD) FEV₁ of 47% (18). The geometric mean (95%CI) of NE at stable state was 2454 ng/mL (1460 to 4125 ng/mL). There was a significant increase in NE levels at an exacerbation (p = 0.003), and NE levels were higher in a bacterial-associated exacerbation (NE log difference 3.873, 95% CI of log difference 1.396 to 10.740, p = 0.011). NE was an accurate predictor of a bacteria-associated exacerbation (area (95%CI) under the receiver operator characteristic curve 0.812 (0.657 to 0.968).

CONCLUSION

NE is elevated during exacerbations of COPD. NE may be a viable biomarker for distinguishing a bacterial exacerbation in patients with COPD.

TRIAL REGISTRATION

Leicestershire, Northamptonshire and Rutland ethics committee (reference number: 07/H0406/157).

Personalised anti-inflammatory therapy for bronchiectasis and cystic fibrosis: selecting patients for controlled trials of neutrophil elastase inhibition

Background

Neutrophil elastase (NE) has been linked to lung neutrophil dysfunction in bronchiectasis and cystic fibrosis (CF), making NE inhibition a potential therapeutic target. NE inhibitor trials have given mixed result perhaps because not all patients have elevated airway NE activity.

Methods

We tested whether a single baseline sputum NE measurement or a combination of clinical parameters could enrich patient populations with elevated NE activity for "personalised medicine". Intra- and interindividual variations of total and active NE levels in induced sputum from patients with CF or bronchiectasis were monitored over 14 days. Patients with established CF and bronchiectasis (n=5 per group) were recruited. NE was measured using three different methods: one total and two active NE assays. Subsequently, we analysed the association between clinical parameters and NE from a large bronchiectasis cohort study (n=381).

Results

All three assays showed a high degree of day-to-day variability (0-233% over 14 days). There were strong correlations found between all assays (p<0.0001). Despite high day-to-day variability, patients could be stratified into "high" or "low" groups based on moderate cut-off levels. In the bronchiectasis cohort study, factors most associated with high sputum NE levels were: Pseudomonas aeruginosa infection (β-estimate 11.5, 95% CI -6.0-29.0), sputum colour (β-estimate 10.4, 95% CI 4.3-16.6), Medical Research Council dyspnoea score (β-estimate 6.4, 95% CI 1.4-11.4) and exacerbation history (β-estimate 3.4, 95% CI 1.4-5.3). Collectively, P. aeruginosa infection, sputum colour and exacerbation frequency provided the greatest specificity for "high" NE (98.7%, 95% CI 7.0-99.6%).

Conclusion

These results show that patients with bronchiectasis and CF can be effectively divided into "high" or "low" groups, based on sputum NE assays or clinical inclusion criteria.

Blood and sputum protein biomarkers for chronic obstructive pulmonary disease (COPD)

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is a heterogeneous set of disorders, characterized by airflow limitation, and reduced lung function. Despite increasing knowledge regarding its pathophysiology, there has been limited advancement in therapeutics and the current treatment strategy is symptom management and prevention of exacerbations. Areas covered: Biomarkers represent important tools for the implementation of precision medicine. As fundamental molecules of all living processes, proteins could provide crucial information about how genes interact with the environment. Proteomics studies could act as important tools in identifying reliable biomarkers to enable a more precise therapeutic approach. In this review, we will explore the most promising blood and sputum protein biomarkers in COPD that have been consistently reported in the literature. Expert commentary: Given the complexity of COPD, no single protein biomarker has been able to improve the outcomes of COPD patients. According to preliminary studies, precision medicine in COPD will likely require a combination of different proteins in a biomarker panel for clinical translation. With advancements in current mass spectrometry techniques, an enhancement in the identification of new biomarkers will be observed, and improvements in sequence database search can fill in potential gaps between biomarker discovery and patient care.