Sputum sol neutrophil elastase activity in bronchiectasis: differential modulation by syndecan-1

Increased Neutrophil Elastase in Affected Lobes of Bronchiectasis and Correlation of Its Levels between Sputum and Bronchial Lavage Fluid

BACKGROUND

Neutrophil elastase (NE) has been proposed as a potential biomarker for evaluating the severity and prognosis of bronchiectasis. This study aimed to compare bronchial lavage quantification of NE levels and activities with those of sputum.

METHODS

A cross-sectional study was conducted in which 24 Vietnamese adults with bronchiectasis were enrolled from June 2023 to August 2023. All participants underwent bronchoscopy to collect bronchial lavage fluid (BLF) from two bronchial locations: one in the region with the greatest bronchial dilatation and one in the normal bronchi or in patients with all lobes affected, the least abnormal lobe (abnormal BLF [ABLF] and normal BLF [NBLF], respectively). Spontaneously expectorated sputum was also collected.

RESULTS

Out of 24 cases, the prevalence of mild, moderate and severe bronchiectasis was 14/24 (58.4%), 5/24 (20.8%), and 5/24 (20.8%), respectively. NE concentration and activity were significantly higher in sputum and ABLF than in NBLF (p<0.001). Sputum and ABLF were highly correlated (r=0.841, p<0.001) with no significant difference in NE activity between sputum and ABLF. Higher levels of NE activity were seen in more severe bronchiectasis than in mild bronchiectasis in all samples but were only statistically significant for NE activity in sputum (r=0.418, p=0.042).

CONCLUSION

NE activity and concentration are elevated in areas of the lung most affected by bronchiectasis. Sputum is a valid surrogate of pulmonary NE levels, as they correlate strongly with ABLF and confirm in a Vietnamese population the relationship between NE activity and disease severity.

Neutrophil Elastase Targets Select Proteins on Human Blood-Monocyte-Derived Macrophage Cell Surfaces

Neutrophil elastase (NE) has been reported to be a pro-inflammatory stimulus for macrophages. The aim of the present study was to determine the impact of NE exposure on the human macrophage proteome and evaluate its impact on pro-inflammatory signals. Human blood monocytes from healthy volunteers were differentiated to macrophages and then exposed to either 500 nM of NE or control vehicle for 2 h in triplicate. Label-free quantitative proteomics analysis identified 41 differentially expressed proteins in the NE versus control vehicle datasets. A total of 26 proteins were downregulated and of those, 21 were cell surface proteins. Importantly, four of the cell surface proteins were proteoglycans: neuropilin 1 (NRP1), syndecan 2 (SDC2), glypican 4 (GPC4), and CD99 antigen-like protein 2 (CD99L2) along with neuropilin 2 (NRP2), CD99 antigen (CD99), and endoglin (ENG) which are known interactors. Additional NE-targeted proteins related to macrophage function were also measured including CD40, CD48, SPINT1, ST14, and MSR1. Collectively, this study provides a comprehensive unbiased view of selective NE-targeted cell surface proteins in chronically inflamed lungs.

Biomarkers in bronchiectasis

Bronchiectasis is a heterogeneous disease with multiple aetiologies and diverse clinical features. There is a general consensus that optimal treatment requires precision medicine approaches focused on specific treatable disease characteristics, known as treatable traits. Identifying subtypes of conditions with distinct underlying biology (endotypes) depends on the identification of biomarkers that are associated with disease features, prognosis or treatment response and which can be applied in clinical practice. Bronchiectasis is a disease characterised by inflammation, infection, structural lung damage and impaired mucociliary clearance. Increasingly there are available methods to measure each of these components of the disease, revealing heterogeneous inflammatory profiles, microbiota, radiology and mucus and epithelial biology in patients with bronchiectasis. Using emerging biomarkers and omics technologies to guide treatment in bronchiectasis is a promising field of research. Here we review the most recent data on biomarkers in bronchiectasis.

The roles of neutrophils in non-tuberculous mycobacterial pulmonary disease

Non-tuberculous Mycobacterial Pulmonary Disease (NTM-PD) is an increasingly recognised global health issue. Studies have suggested that neutrophils may play an important role in controlling NTM infection and contribute to protective immune responses within the early phase of infection. However, these cells are also adversely associated with disease progression and exacerbation and can contribute to pathology, for example in the development of bronchiectasis. In this review, we discuss the key findings and latest evidence regarding the diverse functions of neutrophils in NTM infection. First, we focus on studies that implicate neutrophils in the early response to NTM infection and the evidence reporting neutrophils' capability to kill NTM. Next, we present an overview of the positive and negative effects that characterise the bidirectional relationship between neutrophils and adaptive immunity. We consider the pathological role of neutrophils in driving the clinical phenotype of NTM-PD including bronchiectasis. Finally, we highlight the current promising treatments in development targeting neutrophils in airways diseases. Clearly, more insights on the roles of neutrophils in NTM-PD are needed in order to inform both preventative strategies and host-directed therapy for these important infections.

Research advances and clinical management of bronchiectasis: Chinese perspective

Bronchiectasis is a debilitating chronic suppurative airway disease that confers a substantial burden globally. Despite the notable prevalence, research on bronchiectasis in mainland China remains in its infancy. Nevertheless, there has been a significant leap in the quantity and quality of research, which has contributed to the ever-improving clinical practice. A nationwide collaborative platform has been established to foster multicentre studies, which will help increase the level of evidence further. Here, we summarise the status quo of clinical management and consider the research priorities for bronchiectasis that have been published previously. We also highlight the efforts of the Chinese medical communities to outline the core tasks that need to be addressed within the next decade.

Neutrophil extracellular traps in chronic lung disease: implications for pathogenesis and therapy

Neutrophilic inflammation has a key role in the pathophysiology of multiple chronic lung diseases. The formation of neutrophil extracellular traps (NETs) has emerged as a key mechanism of disease in neutrophilic lung diseases including asthma, COPD, cystic fibrosis and, most recently, bronchiectasis. NETs are large, web-like structures composed of DNA and anti-microbial proteins that are able to bind pathogens, prevent microbial dissemination and degrade bacterial virulence factors. The release of excess concentrations of proteases, antimicrobial proteins, DNA and histones, however, also leads to tissue damage, impaired mucociliary clearance, impaired bacterial killing and increased inflammation. A number of studies have linked airway NET formation with greater disease severity, increased exacerbations and overall worse disease outcomes across the spectrum of airway diseases. Treating neutrophilic inflammation has been challenging in chronic lung disease because of the delicate balance between reducing inflammation and increasing the risk of infections through immunosuppression. Novel approaches to suppressing NET formation or the associated inflammation are in development and represent an important therapeutic target. This review will discuss the relationship between NETs and the pathophysiology of cystic fibrosis, asthma, COPD and bronchiectasis, and explore the current and future development of NET-targeting therapies.

NETs contribute to the pathophysiology of chronic lung disease. Immunomodulating therapies that may reduce inflammatory mediators and NET formation, without compromising bacterial clearance, offer a new treatment path for patients. https://bit.ly/3fyJC6I

Airway inflammation and dysbiosis in antibody deficiency despite the presence of IgG

BACKGROUND

Patients with antibody deficiency suffer chronic respiratory symptoms, recurrent exacerbations and progressive airways disease despite systemic replacement of Immunoglobulin G. Little is known about the respiratory tract biology of these patients.

OBJECTIVE

To measure immunoglobulin levels, inflammatory cytokines and mediators of tissue damage in serum and sputum from patients with antibody deficiency and healthy controls; to analyse the respiratory microbiome in the same cohorts.

METHODS

We obtained paired sputum and serum samples from 31 immunocompetent subjects and 67 antibody deficient patients, the latter divided on computed tomography scan appearance into 'abnormal airways' (bronchiectasis or airway thickening) or 'normal airways'. We measured inflammatory cytokines, immunoglobulin levels, neutrophil elastase, matrix-metalloproteinase-9, urea, albumin and total protein levels using standard assays. We employed V3-V4 region 16S sequencing for microbiome analysis.

RESULTS

Immunodeficient patients had markedly reduced Immunoglobulin A in sputum but higher concentrations of Immunoglobulin G compared to healthy controls. Inflammatory cytokines and tissue damage markers were higher in immunodeficient patients, who also exhibited dysbiosis with over-representation of pathogenic taxa and significantly reduced alpha diversity compared to immunocompetent individuals. These differences were seen regardless of airway morphology. Sputum matrix metalloproteinase-9 and elastase correlated inversely with alpha diversity in the antibody deficient group, as did sputum Immunoglobulin G, which correlated positively with several inflammatory markers, even after correction for albumin levels.

CONCLUSION

Patients with antibody deficiency, even with normal lung imaging, exhibit inflammation and dysbiosis in their airways despite higher levels of Immunoglobulin G compared to healthy controls.

The emerging role of proteases in α1-antitrypsin deficiency and beyond

α1-Antitrypsin deficiency (AATD) has been historically under-recognised and under-diagnosed; recently it has begun to receive greater interest in terms of attempts at deeper elucidation of pathology and treatment options. However, the concept of disease phenotypes within AATD (emphysema, chronic bronchitis, bronchiectasis or a combination of phenotypes) has not been proposed or studied. Of the three neutrophil serine proteases, neutrophil elastase was historically believed to be the sole contributor to disease pathology in AATD. Recently, Proteinase-3 has been increasingly studied as an equal, if not greater, contributor to the disease process. Cathepsin G, however, has not been extensively evaluated in this area. Matrix metalloproteinases have also been mentioned in the pathogenesis of AATD but have not been widely explored. This article considers the available evidence for differential protease activity in patients with AATD, including the contribution to distinct phenotypes of the disease. Owing to limited literature in this area, extrapolations from studies of other chronic lung diseases with similar phenotypes, including COPD and bronchiectasis, have been made. We consider a new framework of understanding defined by protease-driven endotypes of disease which may lead to new opportunities for precision medicine.

The Blood Neutrophil Count After 1 Month of Treatment Predicts the Radiologic Severity of Lung Disease at Treatment End

BACKGROUND

Lung disease after tuberculous confers significant morbidity. However, the determinants of persistent lung damage in TB are not well established. We investigated associations between TB-associated radiologic changes and sociodemographic factors, surrogates of bacillary burden, and blood inflammatory markers at initiation of therapy and after 1 month.

RESEARCH QUESTION

What are the predictors of radiologic severity at the end of TB treatment for TB?

STUDY DESIGN AND METHODS

We collected data from patients treated for drug-sensitive pulmonary TB at our center over a 5.5-year period. We recorded age, sex, ethnicity, smoking status, symptom duration, sputum smear grade, time to culture positivity, and blood results (C-reactive protein and neutrophil count) at baseline and after 1 month of treatment. Chest radiographs obtained at baseline, 2 months, and end of treatment were assessed independently by two radiologists and scored using a validated system. Relationships between predictor variables and radiologic outcomes were assessed using linear or binary logistic regression.

RESULTS

We assessed 154 individuals with a mean age of 37 years, 63% of whom were men. In a multivariate analysis, baseline radiologic severity correlated with sputum smear grade (P = 0.003) and neutrophil count (P < 0.001). At end of treatment, only the 1-month neutrophil count was associated significantly with overall radiologic severity in the multivariate analysis (r = 0.34; P = 0.003) and remained significant after controlling for baseline radiologic scores. The 1-month neutrophil count also was the only independent correlate of volume loss and pleural thickening at the end of treatment and was significantly higher in patients with persistent cavitation or effusion vs those without.

INTERPRETATION

Persistent neutrophilic inflammation after 1 month of TB therapy is associated with poor radiologic outcome, suggesting a target for interventions to minimize lung disease after tuberculous.

Novel Lung Tropic Adeno-Associated Virus Capsids for Therapeutic Gene Delivery

Efforts to identify mutations that underlie inherited genetic diseases combined with strides in the development of gene therapy vectors over the last three decades have culminated in the approval of several adeno-associated virus (AAV)-based gene therapies. Genetic diseases that manifest in the lung such as cystic fibrosis (CF) and surfactant deficiencies, however, have so far proven to be elusive targets. Early clinical trials in CF using AAV serotype 2 (AAV2) achieved safety, but not efficacy endpoints; however, importantly, these studies provided critical information on barriers that need to be surmounted to translate AAV lung gene therapy toward clinical success. Bolstered with an improved understanding of AAV biology and more clinically relevant lung models, next-generation molecular biology and bioinformatics approaches have given rise to novel AAV capsid variants that offer improvements in transduction efficiency, immunological profile, and the ability to circumvent physical barriers in the lung such as mucus. This review discusses the principal limiting barriers to clinical success in lung gene therapy and focuses on novel engineered AAV capsid variants that have been developed to overcome those challenges.

A patenting perspective on human neutrophil elastase (HNE) inhibitors (2014-2018) and their therapeutic applications

INTRODUCTION

Human neutrophil elastase (HNE) is involved in a variety of serious chronic diseases, especially cardiopulmonary pathologies. For this reason, the regulation of HNE activity represents a promising therapeutic approach, which is evident by the development of a number of new and selective HNE inhibitors, both in the academic and pharmaceutical environments.

AREAS COVERED

The present review analyzes and summarizes the patent literature regarding human neutrophil elastase inhibitors for the treatment of cardiopulmonary diseases over 2014-2018.

EXPERT OPINION

HNE is an interesting and defined target to treat various inflammatory diseases, including a number of cardiopulmonary pathologies. The research in this field is quite active, and a number of HNE inhibitors are currently in various stages of clinical development. In addition, new opportunities for HNE inhibitor development stem from recent studies demonstrating the involvement of HNE in many other inflammatory pathologies, including rheumatoid arthritis, inflammatory bowel disease, skin diseases, and cancer. Furthermore, the development of dual HNE/proteinase 3 inhibitors is being pursued as an innovative approach for the treatment of neutrophilic inflammatory diseases. Thus, these new developments will likely stimulate new and increased interest in this important therapeutic target and for the development of novel and selective HNE inhibitors.

Pathophysiology and Genetics of Bronchiectasis Unrelated to Cystic Fibrosis

Bronchiectasis is characterized by deregulated inflammatory response and recurrent bacterial infection resulting in progressive lung damage and an irreversible dilatation of bronchi and bronchioles. Generally accepted model of the development of bronchiectasis is the "vicious cycle hypothesis" that proposes compromising of the mucociliary clearance by an initial event, which leads to the infection of the respiratory tract followed by further impairment of mucociliary function, bacterial proliferation, and more inflammation. Bronchiectasis is a very common symptom in patients with cystic fibrosis (CF), while bronchiectasis unrelated to CF is heterogeneous pathology of unknown cause with a large number of potential contributory factors and poorly understood pathogenesis. It is presumed that bronchiectasis unrelated to CF is a multifactorial condition predisposed by genetic factors. Different molecules have been implicated in the onset and development of idiopathic bronchiectasis, as well as modulation of the disease severity and response to therapy. Most of these molecules are involved in the processes that contribute to the homeostasis of the lung tissue, especially mucociliary clearance, protease-antiprotease balance, and immunomodulation. Evaluation of the studies performed towards investigation of the role these molecules play in bronchiectasis identifies genetic variants that may be of potential importance for clinical management of the disease, and also of interest for future research efforts. This review focuses on the molecules with major roles in lung homeostasis and their involvement in bronchiectasis unrelated to CF.

Synthesized Heparan Sulfate Competitors Attenuate Pseudomonas aeruginosa Lung Infection

Several chronic respiratory diseases are characterized by recurrent and/or persistent infections, chronic inflammatory responses and tissue remodeling, including increased levels of glycosaminoglycans which are known structural components of the airways. Among glycosaminoglycans, heparan sulfate (HS) has been suggested to contribute to excessive inflammatory responses. Here, we aim at (i) investigating whether long-term infection by Pseudomonas aeruginosa, one of the most worrisome threat in chronic respiratory diseases, may impact HS levels, and (ii) exploring HS competitors as potential anti-inflammatory drugs during P. aeruginosa pneumonia. P. aeruginosa clinical strains and ad-hoc synthesized HS competitors were used in vitro and in murine models of lung infection. During long-term chronic P. aeruginosa colonization, infected mice showed higher heparin/HS levels, evaluated by high performance liquid chromatography-mass spectrometry after selective enzymatic digestion, compared to uninfected mice. Among HS competitors, an N-acetyl heparin and a glycol-split heparin dampened leukocyte recruitment and cytokine/chemokine production induced by acute and chronic P. aeruginosa pneumonia in mice. Furthermore, treatment with HS competitors reduced bacterial burden during chronic murine lung infection. In vitro, P. aeruginosa biofilm formation decreased upon treatment with HS competitors. Overall, these findings support further evaluation of HS competitors as a novel therapy to counteract inflammation and infection during P. aeruginosa pneumonia.

Neutrophil elastase in bronchiectasis

The role of neutrophil elastase (NE) is poorly understood in bronchiectasis because of the lack of preclinical data and so most of the assumptions made about NE inhibitor potential benefit is based on data from CF. In this context, NE seems to be a predictor of long-term clinical outcomes and a possible target of treatment. In order to better evaluate the role of NE in bronchiectasis, a systematic search of scientific evidence was performed.Two investigators independently performed the search on PubMed and included studies published up to May 15, 2017 according to predefined criteria. A final pool of 31 studies was included in the systematic review, with a total of 2679 patients. For each paper data of interest were extracted and reported in table.In this review sputum NE has proved useful as an inflammatory marker both in stable state bronchiectasis and during exacerbations and local or systemic antibiotic treatment. NE has also been associated with risk of exacerbation, time to next exacerbation and all-cause mortality. This study reviews also the role of NE as a specific target of treatment in bronchiectasis. Inhibition of NE is at a very early stage and future interventional studies should evaluate safety and efficacy for new molecules and formulations.

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 (β 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.

Rationale and Design of the Genomic Research in Alpha-1 Antitrypsin Deficiency and Sarcoidosis Study. Alpha-1 Protocol

Severe deficiency of alpha-1 antitrypsin has a highly variable clinical presentation. The Genomic Research in Alpha-1 Antitrypsin Deficiency and Sarcoidosis α1 Study is a prospective, multicenter, cross-sectional study of adults older than age 35 years with PiZZ or PiMZ alpha-1 antitrypsin genotypes. It is designed to better understand if microbial factors influence this heterogeneity. Clinical symptoms, pulmonary function testing, computed chest tomography, exercise capacity, and bronchoalveolar lavage (BAL) will be used to define chronic obstructive pulmonary disease (COPD) phenotypes that can be studied with an integrated systems biology approach that includes plasma proteomics; mouth, BAL, and stool microbiome and virome analysis; and blood microRNA and blood mononuclear cell RNA and DNA profiling. We will rely on global genome, transcriptome, proteome, and metabolome datasets. Matched cohorts of PiZZ participants on or off alpha-1 antitrypsin augmentation therapy, PiMZ participants not on augmentation therapy, and control participants from the Subpopulations and Intermediate Outcome Measures in COPD Study who match on FEV1 and age will be compared. In the primary analysis, we will determine if the PiZZ individuals on augmentation therapy have a difference in lower respiratory tract microbes identified compared with matched PiZZ individuals who are not on augmentation therapy. By characterizing the microbiome in alpha-1 antitrypsin deficiency (AATD), we hope to define new phenotypes of COPD that explain some of the diversity of clinical presentations. As a unique genetic cause of COPD, AATD may inform typical COPD pathogenesis, and better understanding of it may illuminate the complex interplay between environment and genetics. Although the biologic approaches are hypothesis generating, the results may lead to development of novel biomarkers, better understanding of COPD phenotypes, and development of novel diagnostic and therapeutic trials in AATD and COPD. Clinical trial registered with www.clinicaltrials.gov (NCT01832220).

Neutrophil elastase inhibitors for the treatment of (cardio)pulmonary diseases: Into clinical testing with pre-adaptive pharmacophores

Alpha-1 antitrypsin deficiency is linked with an increased risk of suffering from lung emphysema. This discovery from the 1960s led to the development of the protease-antiprotease (im)balance hypothesis: Overshooting protease concentrations, especially high levels of elastase were deemed to have an destructive effect on lung tissue. Consequently, it was postulated that efficient elastase inhibitors could alleviate the situation in patients. However, despite intensive drug discovery efforts, even five decades later, no neutrophil elastase inhibitors are available for a disease-modifying treatment of (cardio)pulmonary diseases such as chronic obstructive pulmonary disease. Here, we critically review the attempts to develop effective human neutrophil elastase inhibitors while strongly focussing on recent developments. On purpose and with perspective distortion we focus on recent developments. One aim of this review is to classify the known HNE inhibitors into several generations, according to their binding modes. In general, there seem to be three major challenges in the development of suitable elastase inhibitors: (1) assuring sufficient potency, (2) securing selectivity, and (3) achieving metabolic stability especially under pathophysiological conditions. Impressive achievements have been made since 2001 with the identification of potent nonreactive, reversible small molecule inhibitors. The most modern inhibitors bind HNE via an induced fit with a frozen bioactive conformation that leads to a significant boost in potency, selectivity, and stability ('pre-adaptive pharmacophores'). These 5th generation inhibitors might succeed in re-establishing the protease-antiprotease balance in patients for the first time.

S-maltoheptaose targets syndecan-bound effectors to reduce smoking-related neutrophilic inflammation

Cigarette smoke induces injury and neutrophilic inflammation in the airways of smokers. The stability and activity of inflammatory effectors, IL8 and neutrophil elastase (NE), can be prolonged by binding to airway heparan sulfate (HS)/syndecan-1, posing risk for developing chronic obstructive pulmonary disease(COPD). We hypothesize that antagonizing HS/syndecan-1 binding of the inflammatory effectors could reduce smoking-related neutrophil-mediated airway inflammation. Analysis of bronchoalveolar lavage fluid(BALF) of COPD patients found both total and unopposed NE levels to be significantly higher among smokers with COPD than non-COPD subjects. Similar NE burden was observed in smoke-exposed rats compared to sham air controls. We chose sulfated-maltoheptaose(SM), a heparin-mimetic, to antagonize HS/sydecan-1 binding of the inflammatory mediators in airway fluids and lung tissues of the smoke-exposed rat model. Airway treatment with SM resulted in displacement of CINC-1 and NE from complexation with bronchio-epithelial HS/syndecan-1, dissipating the chemokine gradient for neutrophil flux across to the bronchial lumen. Following SM displacement of NE from shed HS/syndecan-1 in bronchial fluids, NE became accessible to inhibition by α₁-antitrypsin endogenous in test samples. The antagonistic actions of SM against syndecan-1 binding of NE and CINC-1 in smoke-exposed airways suggest new therapeutic opportunities for modulating airway inflammation in smokers with SM delivery.

Sputum matrix metalloproteinase-8 and -9 and tissue inhibitor of metalloproteinase-1 in bronchiectasis: clinical correlates and prognostic implications

BACKGROUND AND OBJECTIVE

The triplet of airway infection, inflammation and bronchial wall destruction associated with excessive matrix metalloproteinases (MMP) release and imbalance of tissue inhibitor metalloproteinase-1 (TIMP-1) is implicated in bronchiectasis. We sought to determine the associations between sputum MMP (MMP-8, MMP-9) and TIMP-1 and the severity of bronchiectasis; the utility of MMP in predicting risks of future bronchiectasis exacerbations (BE); and the changes in MMP levels during BE.

METHODS

We recruited 102 patients with stable bronchiectasis and 22 healthy subjects. For bronchiectasis patients, baseline measurements consisted of sputum inflammation and MMP measurements, bacterial culture, spirometry and chest high-resolution computed tomography (HRCT). Bronchiectasis patients were followed up for 1 year to determine the frequency of BE. Changes in MMP levels during BE were assessed in 36 bronchiectasis patients.

RESULTS

Sputum MMP-8, MMP-9 and MMP-9/TIMP-1 ratio in bronchiectasis patients were significantly increased compared with healthy subjects. MMP-8 and MMP-9 levels, but not TIMP-1, were positively correlated with clinical measures, including HRCT scores, spirometry and Bronchiectasis Severity Index. Seventy-nine bronchiectasis patients were included in survival analyses of BE. Lower levels of baseline MMP-9 were associated with reduced risks of and a longer time to the first BE during follow-up. MMP-8 and MMP-9, but not TIMP-1 or MMP-9/TIMP-1 ratio, were significantly heightened during BE.

CONCLUSIONS

Sputum MMP might be useful biomarkers for the assessment of bronchiectasis severity and the prediction of future risks of BE. Our results provide the rationales for the future clinical application of MMP inhibitors.

Management of bronchiectasis in adults

Formerly regarded as a rare disease, bronchiectasis is now increasingly recognised and a renewed interest in the condition is stimulating drug development and clinical research. Bronchiectasis represents the final common pathway of a number of infectious, genetic, autoimmune, developmental and allergic disorders and is highly heterogeneous in its aetiology, impact and prognosis. The goals of therapy should be: to improve airway mucus clearance through physiotherapy with or without adjunctive therapies; to suppress, eradicate and prevent airway bacterial colonisation; to reduce airway inflammation; and to improve physical functioning and quality of life. Fortunately, an increasing body of evidence supports interventions in bronchiectasis. The field has benefited greatly from the introduction of evidence-based guidelines in some European countries and randomised controlled trials have now demonstrated the benefit of long-term macrolide therapy, with accumulating evidence for inhaled therapies, physiotherapy and pulmonary rehabilitation. This review provides a critical update on the management of bronchiectasis focussing on emerging evidence and recent randomised controlled trials.

Overcoming the cystic fibrosis sputum barrier to leading adeno-associated virus gene therapy vectors

Gene therapy has not yet improved cystic fibrosis (CF) patient lung function in human trials, despite promising preclinical studies. In the human CF lung, inhaled gene vectors must penetrate the viscoelastic secretions coating the airways to reach target cells in the underlying epithelium. We investigated whether CF sputum acts as a barrier to leading adeno-associated virus (AAV) gene vectors, including AAV2, the only serotype tested in CF clinical trials, and AAV1, a leading candidate for future trials. Using multiple particle tracking, we found that sputum strongly impeded diffusion of AAV, regardless of serotype, by adhesive interactions and steric obstruction. Approximately 50% of AAV vectors diffused >1,000-fold more slowly in sputum than in water, with large patient-to-patient variation. We thus tested two strategies to improve AAV diffusion in sputum. We showed that an AAV2 mutant engineered to have reduced heparin binding diffused twice as fast as AAV2 on average, presumably because of reduced adhesion to sputum. We also discovered that the mucolytic N-acetylcysteine could markedly enhance AAV diffusion by altering the sputum microstructure. These studies underscore that sputum is a major barrier to CF gene delivery, and offer strategies for increasing AAV penetration through sputum to improve clinical outcomes.

Neutrophil elastase gene polymorphisms: modulators of response to therapy in childhood bronchiectasis?

BACKGROUND

The aim of this study was to investigate polymorphisms in the promoter region of the neutrophil elastase (ELANE) gene as potential modulators of the therapeutic response in children with idiopathic bronchiectasis.

METHODS

The study included 48 children between 5 and 17 years old who were diagnosed with idiopathic bronchiectasis based on high-resolution computed tomography of the thorax. In all patients therapy included administration of antibiotics, anti-inflammatory drugs, expectorants, and postural drainage. Response to therapy was evaluated by the change in FeNO levels before and after administration of therapy. The ELANE promoter region polymorphisms were analyzed by PCR-direct DNA sequencing.

RESULTS

According to the predicted activity of ELANE genotypes, subjects were divided into two groups: low/intermediate activity (n = 18) and high activity (n = 30). Subjects in the group with high-activity genotype had higher initial FeNO levels and this difference was statistically significant (t = 2.906; p = 0.006). The difference between FeNO levels before and after therapy was also statistically significantly higher in children with high-activity genotype (t = 3.329; p = 0.002). Statistically significant correlation was observed between the change in FeNO levels and ELANE genotypes (r = 0.350; p = 0.015).

CONCLUSION

Children with high-activity genotype had higher initial FeNO levels and showed better response to therapy than children with low/intermediate-activity genotypes.

Airway disease in alpha-1 antitrypsin deficiency

Although less well appreciated than pulmonary emphysema, inflammation of the airways is an early and important finding in alpha-1 antitrypsin deficiency (AATD). The spectrum of clinical presentations of airways disease includes cough and wheezing that is frequently diagnosed as asthma. Study of the airways inflammation in sputum or the proximal airways usually reveals neutrophilic inflammation. Although there is significant phenotypic variation, tubular airways dilation consistent with bronchiectasis is a common finding in areas of panlobular emphysema in severely deficient AATD. Other phenotypes of varicose and saccular bronchiectasis have been described. Since AAT may impact the course of bacterial, mycobacterial and viral clearance, future studies of the airway microbiota will inform whether airway pathogens are responsible for some pulmonary AATD phenotypes. Whether airways disease improves with AAT augmentation therapy remains unknown.

Phase II study of a neutrophil elastase inhibitor (AZD9668) in patients with bronchiectasis

Neutrophil elastase (NE) activity is increased in bronchiectasis and may play a role in this condition. We wished to determine the effect of AZD9668, a selective oral inhibitor of NE. Efficacy and safety of AZD9668 60 mg twice daily over 4 weeks were evaluated in a randomised, double-blind, placebo-controlled, parallel-group, Phase II, signal-searching study in patients with bronchiectasis. Outcome measures included: waking and post-waking sputum neutrophil counts; lung function tests; 24-h sputum weight; BronkoTest(®) diary card data; St George's Respiratory Questionnaire for COPD patients (SGRQ-C); sputum NE activity; inflammatory biomarker levels; desmosine levels; adverse events, safety haematology and biochemistry. AZD9668 levels in plasma and sputum were measured to confirm exposure. Thirty-eight patients were randomised: 16 to placebo and 22 to AZD9668. There was no change in sputum neutrophils with AZD9668. Forced expiratory volume in 1 s improved by 100 mL in the AZD9668 group compared with placebo (p = 0.006). Significant changes (defined a priori as p < 0.1) in favour of AZD9668 were also seen in slow vital capacity, plasma interleukin-8, and post-waking sputum interleukin-6 and Regulated on Activation, Normal T-cell Expressed and Secreted levels. Non-significant changes in favour of AZD9668 were seen in other lung function tests, sputum weight and the SGRQ-C. AZD9668 was well tolerated. In this small signal-searching study, 4 weeks' treatment with AZD9668 improved lung function in patients with bronchiectasis and there were trends for reductions in sputum inflammatory biomarkers. Larger studies of longer duration would be needed to confirm the potential benefits of this agent in bronchiectasis.

REGISTRATION

NCT00769119.

AZD9668: pharmacological characterization of a novel oral inhibitor of neutrophil elastase

N-{[5-(methanesulfonyl)pyridin-2-yl]methyl}-6-methyl-5-(1-methyl-1H-pyrazol-5-yl)-2-oxo-1-[3-(trifluoromethyl)phenyl]-1,2-dihydropyridine-3-carboxamide (AZD9668) is a novel, oral inhibitor of neutrophil elastase (NE), an enzyme implicated in the signs, symptoms, and disease progression in NE-driven respiratory diseases such as bronchiectasis and chronic obstructive pulmonary disease via its role in the inflammatory process, mucus overproduction, and lung tissue damage. In vitro and in vivo experiments were done to evaluate the binding kinetics, potency, and selectivity of AZD9668, its effects in whole-blood and cell-based assays, and its efficacy in models of lung inflammation and damage. In contrast to earlier NE inhibitors, the interaction between AZD9668 and NE was rapidly reversible. AZD9668 was also highly selective for NE over other neutrophil-derived serine proteases. In cell-based assays, AZD9668 inhibited plasma NE activity in zymosan-stimulated whole blood. In isolated human polymorphonuclear cells, AZD9668 inhibited NE activity on the surface of stimulated cells and in the supernatant of primed, stimulated cells. AZD9668 showed good crossover potency to NE from other species. Oral administration of AZD9668 to mice or rats prevented human NE-induced lung injury, measured by lung hemorrhage, and an increase in matrix protein degradation products in bronchoalveolar lavage (BAL) fluid. In an acute smoke model, AZD9668 reduced the inflammatory response to cigarette smoke as indicated by a reduction in BAL neutrophils and interleukin-1β. Finally, AZD9668 prevented airspace enlargement and small airway wall remodeling in guinea pigs in response to chronic tobacco smoke exposure whether dosed therapeutically or prophylactically. In summary, AZD9668 has the potential to reduce lung inflammation and the associated structural and functional changes in human diseases.

Neutrophil elastase, proteinase 3 and cathepsin G: physicochemical properties, activity and physiopathological functions

Polymorphonuclear neutrophils form a primary line of defense against bacterial infections using complementary oxidative and non-oxidative pathways to destroy phagocytized pathogens. The three serine proteases elastase, proteinase 3 and cathepsin G, are major components of the neutrophil primary granules that participate in the non-oxidative pathway of intracellular pathogen destruction. Neutrophil activation and degranulation results in the release of these proteases into the extracellular medium as proteolytically active enzymes, part of them remaining exposed at the cell surface. Extracellular neutrophil serine proteases also help kill bacteria and are involved in the degradation of extracellular matrix components during acute and chronic inflammation. But they are also important as specific regulators of the immune response, controlling cellular signaling through the processing of chemokines, modulating the cytokine network, and activating specific cell surface receptors. Neutrophil serine proteases are also involved in the pathogenicity of a variety of human diseases. This review focuses on the structural and functional properties of these proteases that may explain their specific biological roles, and facilitate their use as molecular targets for new therapeutic strategies.

Upregulation of ICAM-1 expression in bronchial epithelial cells by airway secretions in bronchiectasis

The airway epithelium participates in chronic airway inflammation by expressing adhesion molecules that mediate the transmigration of neutrophils into the inflamed airways. We hypothesize that, in patients with bronchiectasis, cytokines in their bronchial secretions enhance the expression of intercellular cell adhesion molecule (ICAM-1) in the bronchial epithelium and thus contribute to sustained recruitment of neutrophils into the inflamed airways. In the present study, we investigated the effect of bronchial secretions on the regulation of ICAM-1 in bronchial epithelial cells, and its modulation by pharmacologic agents. The expression of ICAM-1 mRNA and protein in human bronchial epithelial cells upon exposure to sputum sol from subjects with bronchiectasis were evaluated by reverse transcription-polymerase chain reaction (RT-PCR) and ELISA, respectively. Modulating effects of dexamethasone, ibuprofen, MK-663 or triptolide on ICAM-1 regulation were investigated in vitro. We demonstrated that changes in ICAM-1 expression correlated with levels of TNF-alpha in the sputum sol, and treatment of sol samples with TNF-alpha antibodies attenuated both the increase in ICAM-1 mRNA and protein. The role of TNF-alpha was further demonstrated when TNF-alpha elicited dose dependent increase in ICAM-1 expression. The sputum effect could also be suppressed dose-dependently by pre-incubation of bronchial epithelial cells with dexamethasone, ibuprofen, MK-663 or triptolide. Evidence is thus provided for the upregulation of bronchial epithelial ICAM-1 expression by airway secretions in bronchiectasis and a specific role for TNF-alpha in the secretions. The success of drug attenuation of this upregulation provides insight into possible therapeutic paradigms in the management of the disease.

The sulfate groups of chondroitin sulfate- and heparan sulfate-containing proteoglycans in neutrophil plasma membranes are novel binding sites for human leukocyte elastase and cathepsin G

Human leukocyte elastase (HLE) and cathepsin G (CG) are expressed at high levels on the surface of activated human neutrophils (PMN) in catalytically active but inhibitor-resistant forms having the potential to contribute to tissue injury. Herein we have investigated the mechanisms by which HLE and CG bind to PMN plasma membranes. (125)I-Labeled HLE and CG bind to PMN at 0 degrees C in a saturable and reversible manner (K(D) = 5.38 and 4.36 x 10(-7) m and 11.5 and 8.1 x 10(6) binding sites/cell, respectively). Incubation of PMN with radiolabeled HLE and CG in the presence of a 200-fold molar excess of unlabeled HLE, CG, myeloperoxidase, lactoferrin, proteinase 3, phenylmethylsulfonyl fluoride (PMSF)-inactivated HLE, or PMSF-inactivated CG inhibited binding of radiolabeled ligands. This indicates that these PMN granule proteins share binding sites on PMN and that functional active sites of HLE and CG are not required for their binding to PMN. The sulfate groups of heparan sulfate- and chondroitin sulfate-containing proteoglycans are the PMN binding sites for HLE and CG since binding of HLE and CG to PMN was inhibited by incubating PMN with 1) trypsin, chondroitinase ABC, and heparitinases, but not other glycanases, and 2) purified chondroitin sulfates, heparan sulfate, and other sulfated molecules, but not with non-sulfated glycans. Thus, heparan sulfate- and chondroitin sulfate-containing proteoglycans are low affinity, high volume PMN surface binding sites for HLE and CG, which are well suited to bind high concentrations of active serine proteinases released from degranulating PMN.

IL-23 mediates inflammatory responses to mucoid Pseudomonas aeruginosa lung infection in mice

Patients with cystic fibrosis (CF) develop chronic Pseudomonas aeruginosa lung infection with mucoid strains of P. aeruginosa; these infections cause significant morbidity. The immunological response in these infections is characterized by an influx of neutrophils to the lung and subsequent lung damage over time; however, the underlying mediators to this response are not well understood. We recently reported that IL-23 and IL-17 were elevated in the sputum of patients with CF who were actively infected with P. aeruginosa; however, the importance of IL-23 and IL-17 in mediating this inflammation was unclear. To understand the role that IL-23 plays in initiating airway inflammation in response to P. aeruginosa, IL-23p19(-/-) (IL-23 deficient) and wild-type (WT) mice were challenged with agarose beads containing a clinical, mucoid isolate of P. aeruginosa. Levels of proinflammatory cytokines, chemokines, bacterial dissemination, and inflammatory infiltrates were measured. IL-23-deficient mice had significantly lower induction of IL-17, keratinocyte-derived chemokine (KC), and IL-6, decreased bronchoalveolar lavage (BAL) neutrophils, metalloproteinase-9 (MMP-9), and reduced airway inflammation than WT mice. Despite the reduced level of inflammation in IL-23p19(-/-) mice, there were no differences in the induction of TNF and interferon-gamma or in bacterial dissemination between the two groups. This study demonstrates that IL-23 plays a critical role in generating airway inflammation observed in mucoid P. aeruginosa infection and suggests that IL-23 could be a potential target for immunotherapy to treat airway inflammation in CF.

EPI-hNE4, a proteolysis-resistant inhibitor of human neutrophil elastase and potential anti-inflammatory drug for treating cystic fibrosis

EPI-hNE4 (depelstat) is a potent inhibitor of human neutrophil elastase derived from human inter-alpha-trypsin inhibitor and designed to control the excess proteolytic activity in the sputum of cystic fibrosis patients. We analyzed its resistance to the proteolysis it is likely to encounter at inflammatory sites in vivo. EPI-hNE4 resisted hydrolysis by neutrophil matrix metalloproteases (MMPs) and serine proteases that are released from activated neutrophils in inflammatory lung secretions, including MMP-8 and MMP-9, and the elastase-related protease 3 and cathepsin G. It also resisted degradation by epithelial lung cell MMP-7 but was broken down by the Pseudomonas aeruginosa metalloelastase pseudolysin, when used in a purified system, but not when this protease competed with equimolar amounts of neutrophil elastase. We also investigated the inhibitory properties of EPI-hNE4 at the surface of purified blood neutrophils and in the sputum of cystic fibrosis patients where neutrophil elastase is in both a soluble and a gel phase. The elastase at the neutrophil surface was fully inhibited by EPI-hNE4 and formed soluble complexes. The elastase in cystic fibrosis sputum supernatants was inhibited by stoichiometric amounts of EPI-hNE4, allowing titration of the protease. But the percentage of inhibition in whole sputum homogenates varied from 50 to 100%, depending on the sample tested. EPI-hNE4 was rapidly cleaved by the digestive protease pepsin in vitro. Therefore, EPI-hNE4 seems to be an elastase inhibitor suitable for use in aerosols to treat patients with cystic fibrosis.

Neutrophil granule proteins as targets of leukemia-specific immune responses

PURPOSE OF REVIEW

Recent progress in the identification of leukemia antigens has stimulated the development of vaccines to treat hematological malignancies. Here we review the identification and characterization of the myeloid leukemia-specific antigens proteinase 3 and neutrophil elastase found in the primary (azurophil) granule proteins of granulocytes and their precursors. A peptide 'PR1' derived from these proteins induces powerful HLA-A0201-restricted CD8 T-cell proliferation. PR1-specific T cells are cytotoxic to leukemia and myelodysplastic syndrome progenitors, and occur at low frequencies in normal individuals. Frequencies are higher in patients with myeloid leukemias, and highest in patients with chronic myeloid leukemia entering molecular remission after allogeneic stem cell transplantation.

RECENT FINDINGS

These observations, together with the known association of autoimmunity to proteinase 3 and neutrophil elastase in Wegener's granulomatosis, support the concept that there is a natural immunity to primary granule proteins which can be boosted to enhance immunity to leukemia. Preliminary reports indicate that PR1 peptide vaccination induces significant increases in PR1-specific cytotoxic T cells with rapid and durable remissions in some patients with advanced myeloid leukemias.

SUMMARY

These promising developments in antileukemia vaccines have stimulated research to optimize vaccine delivery and modify regulation of natural T-cell immunity to primary granule proteins to improve treatment of otherwise refractory myeloid leukemias and myelodysplastic syndrome.

SP-A binds alpha1-antitrypsin in vitro and reduces the association rate constant for neutrophil elastase

Background

α1-antitrypsin and surfactant protein-A (SP-A) are major lung defense proteins. With the hypothesis that SP-A could bind α1-antitrypsin, we designed a series of in vitro experiments aimed at investigating the nature and consequences of such an interaction.

Methods and results

At an α1-antitrypsin:SP-A molar ratio of 1:1, the interaction resulted in a calcium-dependent decrease of 84.6% in the association rate constant of α1-antitrypsin for neutrophil elastase. The findings were similar when SP-A was coupled with the Z variant of α1-antitrypsin. The carbohydrate recognition domain of SP-A appeared to be a major determinant of the interaction, by recognizing α1-antitrypsin carbohydrate chains. However, binding of SP-A carbohydrate chains to the α1-antitrypsin amino acid backbone and interaction between carbohydrates of both proteins are also possible. Gel filtration chromatography and turnover per inactivation experiments indicated that one part of SP-A binds several molar parts of α1-antitrypsin.

Conclusion

We conclude that the binding of SP-A to α1-antitrypsin results in a decrease of the inhibition of neutrophil elastase. This interaction could have potential implications in the physiologic regulation of α1-antitrypsin activity, in the pathogenesis of pulmonary emphysema, and in the defense against infectious agents.

Antiprotease Function of Airway Secretions in Purulent Tracheobronchitis

STUDY OBJECTIVES

Unopposed activity of the serine protease, human leukocyte elastase (HLE), is detectable in the airways of patients with purulent tracheobronchitis. The aim of this study was to assess the compartmentalization of HLE activity in the liquid sol phase and the solid gel phase of airway secretions.

DESIGN

Seventy samples of tracheobrochial aspirates were obtained from patients who had hypersecretion and were receiving mechanical ventilation.

METHODS

Samples were separated into sol and gel ("mucous pellet") phases, and HLE activity was measured using chromogenic substrate degradation. HLE was eluted from the mucous pellet using hypertonic saline solution, 1 mol/L, or bovine pancreatic deoxyribonuclease (DNase), 16 micromol/L.

RESULTS

HLE activity partitioned between the sol and gel phases of the secretions, with most of the activity present in the gel phase (32:1 ratio of gel to sol HLE activity). The activity of HLE was 95% inhibited when bound to the gel phase, but activity appeared to be largely restored after elution from the gel phase. The gel phase was capable of binding additional exogenous HLE, and its binding capacity for exogenous HLE was not saturated by concentrations that exceeded the highest clinically relevant HLE levels (1.1 mg/mL). Hypertonic saline solution and DNase I efficiently liberated endogenous and exogenous gel phase-bound HLE activity, suggesting that electrostatic bonds and DNA, respectively, play important roles in binding HLE to the gel phase.

CONCLUSIONS

The solid phase of airway secretions is a more important modulator of elastase-antielastase balance than has been previously recognized.

Potential role of inhibitors of neutrophil elastase in treating diseases of the airway

The potential therapeutic use of inhibitors of neutrophil elastase (NE) is reviewed with emphasis on diseases of the airway. In addition to its proteolytic properties, NE is a potent secretagogue and may be pro-inflammatory. The properties of natural occurring inhibitors of NE such as alpha-one antitrypsin and secretory leukoprotease inhibitor are reviewed. In addition, recombinant versions of naturally occurring inhibitors and synthetic small molecule inhibitors are potential therapies for respiratory diseases. For recombinant proteins, aerosol administration has been the preferred method of delivery. The inhaled mode of delivery can complicate the determination of dose responsiveness and thus the evaluation of safety and efficacy of these agents. In addition to the aerosolization issue, there remain other significant barriers to the successful deployment of these agents in clinical trials. These include the need for high standards for purification of recombinant proteins, the lack of understanding of interaction with airway secretions, the controversy over role of NE in the pathogenesis of nonhereditary COPD, and asthma, while the need for the safety of new classes of systemically delivered small molecules will need to be established.

Proteolytic Regulation of the Urokinase Receptor/CD87 on Monocytic Cells by Neutrophil Elastase and Cathepsin G

The urokinase receptor (CD87) participates to the pericellular proteolytic potential of migrating cells and to the recruitment of leukocytes during inflammation. It consists of three structurally homologous domains, with the C-terminal domain D3 attached to cell membranes through a GPI anchor. CD87 is susceptible to an endoproteolytic processing removing the N-terminal domain D1 and generating truncated D2D3 membrane species, thus modulating CD87-associated functions. Full-length or truncated CD87 can be also released from cells via juxtamembrane cleavage by phospholipases and/or by yet unidentified proteinases. Using a recombinant CD87 and the CD87-positive monocytic U937 cell line and isolated blood monocytes, we show by protein immunoblotting and flow immunocytometry that the human neutrophil serine-proteinases elastase and cathepsin G cleave CD87 within the D1-D2 linker sequence, while in addition cathepsin G is highly efficient in cleaving the C terminus of D3. The combination of cathepsin G and elastase provided by degranulated neutrophils results in enzymatic cooperation leading to the release from monocytic cells of a truncated D2D3 species resembling that previously described in pathological body fluids. Using mass spectrometry analysis, the proteolytic fragmentation of synthetic peptides mapping the D1-D2 linker and D3 C-terminal domains identifies potential cleavage sites for each enzyme and suggests the existence of a mechanism regulating the CD87(D1-D2)-associated chemotactic activity. Finally, isolated or combined elastase and cathepsin G drastically reduce the capacity of cells to bind urokinase. Secretable leukocyte serine-proteinases are thus endowed with high potential for the regulation of CD87 expression and function on inflammatory cells.