Sputum biomarkers of inflammation in cystic fibrosis lung disease

Changes in physiological, functional and structural markers of cystic fibrosis lung disease with treatment of a pulmonary exacerbation

BACKGROUND

Clinical trials in cystic fibrosis (CF) have been hindered by the paucity of well characterised and clinically relevant outcome measures.

AIM

To evaluate a range of conventional and novel biomarkers of CF lung disease in a multicentre setting as a contributing study in selecting outcome assays for a clinical trial of CFTR gene therapy.

METHODS

A multicentre observational study of adult and paediatric patients with CF (>10 years) treated for a physician-defined exacerbation of CF pulmonary symptoms. Measurements were performed at commencement and immediately after a course of intravenous antibiotics. Disease activity was assessed using 46 assays across five key domains: symptoms, lung physiology, structural changes on CT, pulmonary and systemic inflammatory markers.

RESULTS

Statistically significant improvements were seen in forced expiratory volume in 1 s (p<0.001, n=32), lung clearance index (p<0.01, n=32), symptoms (p<0.0001, n=37), CT scores for airway wall thickness (p<0.01, n=31), air trapping (p<0.01, n=30) and large mucus plugs (p=0.0001, n=31), serum C-reactive protein (p<0.0001, n=34), serum interleukin-6 (p<0.0001, n=33) and serum calprotectin (p<0.0001, n=31).

DISCUSSION

We identify the key biomarkers of inflammation, imaging and physiology that alter alongside symptomatic improvement following treatment of an acute CF exacerbation. These data, in parallel with our study of biomarkers in patients with stable CF, provide important guidance in choosing optimal biomarkers for novel therapies. Further, they highlight that such acute therapy predominantly improves large airway parameters and systemic inflammation, but has less effect on airway inflammation.

Sputum biomarkers of inflammation and lung function decline in children with cystic fibrosis

RATIONALE

Progressive lung function decline is a defining feature of cystic fibrosis (CF). Because airway inflammation plays a central role in CF lung disease, inflammatory biomarkers that can be used to monitor disease activity would be valuable.

OBJECTIVES

Examine longitudinal relationships between sputum biomarkers and lung function.

METHODS

In this prospective, longitudinal cohort study, sputum induction was performed annually over 3 years in 35 children with CF. Sputum was assayed for mediators related to proteolysis and a panel of inflammatory cytokines.

MEASUREMENTS AND MAIN RESULTS

Sputum neutrophil elastase, tissue inhibitor of metalloproteinase-1, and TNF-α increased over time, whereas neutrophil elastase antiprotease complexes (NEAPCs) and secretory leukoprotease inhibitor (SLPI) significantly decreased over time. Higher detectable baseline neutrophil elastase was associated with more rapid lung function decline. Similar results for neutrophil elastase were observed in a validation cohort. When categorizing subjects as "rapid" or "slow" decliners, logistic regression demonstrated that the initial measurement of neutrophil elastase had the highest individual predictive value for subsequent lung function decline, whereas neutrophil elastase, IL-8, and IL-6 had the highest combined predictive value. Lung function decline was associated with increases in neutrophil counts, neutrophil elastase, and IL-1β and declines in NEAPCs and SLPI.

CONCLUSIONS

In children with CF, a single determination of sputum biomarkers, particularly neutrophil elastase, has predictive value for subsequent lung function decline, and longitudinal changes in sputum inflammatory biomarkers are related to lung function changes. Based on our results, sputum neutrophil elastase was the most informative biomarker to monitor disease activity.

Progress in cystic fibrosis and the CF Therapeutics Development Network

Cystic fibrosis (CF), the most common life-shortening genetic disorder in Caucasians, affects approximately 70 000 individuals worldwide. In 1998, the Cystic Fibrosis Foundation (CFF) launched the CF Therapeutics Development Network (CF-TDN) as a central element of its Therapeutics Development Programme. Designed to accelerate the clinical evaluation of new therapies needed to fulfil the CFF mission to control and cure CF, the CF-TDN has conducted 75 clinical trials since its inception, and has contributed to studies as varied as initial safety and proof of concept trials to pivotal programmes required for regulatory approval. This review highlights recent and significant research efforts of the CF-TDN, including a summary of contributions to studies involving CF transmembrane conductance regulator (CFTR) modulators, airway surface liquid hydrators and mucus modifiers, anti-infectives, anti-inflammatories, and nutritional therapies. Efforts to advance CF biomarkers, necessary to accelerate the therapeutic goals of the network, are also summarised.

Sputum biomarkers and the prediction of clinical outcomes in patients with cystic fibrosis

Lung function, acute pulmonary exacerbations (APE), and weight are the best clinical predictors of survival in cystic fibrosis (CF); however, underlying mechanisms are incompletely understood. Biomarkers of current disease state predictive of future outcomes might identify mechanisms and provide treatment targets, trial endpoints and objective clinical monitoring tools. Such CF-specific biomarkers have previously been elusive. Using observational and validation cohorts comprising 97 non-transplanted consecutively-recruited adult CF patients at the Intermountain Adult CF Center, University of Utah, we identified biomarkers informative of current disease and predictive of future clinical outcomes. Patients represented the majority of sputum producers. They were recruited March 2004-April 2007 and followed through May 2011. Sputum biomarker concentrations were measured and clinical outcomes meticulously recorded for a median 5.9 (interquartile range 5.0 to 6.6) years to study associations between biomarkers and future APE and time-to-lung transplantation or death. After multivariate modeling, only high mobility group box-1 protein (HMGB-1, mean = 5.84 [log ng/ml], standard deviation [SD] = 1.75) predicted time-to-first APE (hazard ratio [HR] per log-unit HMGB-1 = 1.56, p-value = 0.005), number of future APE within 5 years (0.338 APE per log-unit HMGB-1, p<0.001 by quasi-Poisson regression) and time-to-lung transplantation or death (HR = 1.59, p = 0.02). At APE onset, sputum granulocyte macrophage colony stimulating factor (GM-CSF, mean 4.8 [log pg/ml], SD = 1.26) was significantly associated with APE-associated declines in lung function (−10.8 FEV₁% points per log-unit GM-CSF, p<0.001 by linear regression). Evaluation of validation cohorts produced similar results that passed tests of mutual consistency. In CF sputum, high HMGB-1 predicts incidence and recurrence of APE and survival, plausibly because it mediates long-term airway inflammation. High APE-associated GM-CSF identifies patients with large acute declines in FEV₁%, possibly providing a laboratory-based objective decision-support tool for determination of an APE diagnosis. These biomarkers are potential CF reporting tools and treatment targets for slowing long-term progression and reducing short-term severity.

Metabolomic profiling of regulatory lipid mediators in sputum from adult cystic fibrosis patients

Retained respiratory tract (RT) secretions, infection, and exuberant inflammatory responses are core abnormalities in cystic fibrosis (CF) lung disease. Factors contributing to the destructive CF airway inflammatory processes remain incompletely characterized. The pro-oxidative inflammatory CF RT milieu is known to contain enzymatically and nonenzymatically produced regulatory lipid mediators, a panel of structurally defined oxidized metabolites of polyunsaturated fatty acids known to play a role in pathology related to inflammation. Using an extraction protocol that maximizes recoveries of sputum-spiked deuterated standards, coupled with an LC/MS/MS detection system, this study presents a metabolomic method to assess a broad spectrum of regulatory lipid mediators in freshly obtained sputum from CF patients. A broad range of both proinflammatory and anti-inflammatory lipid mediators was detected, including PGE2, PGD2, TXB2, LTB4, 6-trans-LTB4, 20-OH-LTB4, 20-COOH-LTB4, 20-HETE, 15-HETE, 11-HETE, 12-HETE, 8-HETE, 9-HETE, 5-HETE, EpETrEs, diols, resolvin E1, 15-deoxy-PGJ2, and LXA4. The vast majority of these oxylipins have not been reported previously in CF RT secretions. Whereas direct associations of individual proinflammatory lipid mediators with compromised lung function (FEV-1) were observed, the relationships were not robust. However, multiple statistical analyses revealed that the regulatory lipid mediators profile taken in aggregate proved to have a stronger association with lung function in relatively stable outpatient adult CF patients. Our data reveal a relative paucity of the anti-inflammatory lipid mediator lipoxin A4 in CF sputum. Patients displaying detectable levels of the anti-inflammatory lipid mediator resolvin E1 demonstrated a better lung function compared to those patients with undetectable levels. Our data suggest that comprehensive metabolomic profiling of regulatory lipid mediators in CF sputum should contribute to a better understanding of the molecular mechanisms underlying CF RT inflammatory pathobiology. Further studies are required to determine the extent to which nutritional or pharmacological interventions alter the regulatory lipid mediators profile of the CF RT and the impact of potential modulations of RT regulatory lipid mediators on the clinical progression of CF lung disease.

Sputum tobramycin concentrations in cystic fibrosis patients with repeated administration of inhaled tobramycin

BACKGROUND

Dosing of tobramycin solution for inhalation (TSI) in cystic fibrosis (CF) patients was based on single-dose pharmacokinetic studies. This investigation was prompted by evidence of possible antibiotic accumulation in respiratory secretions with repeated dosing. The objectives were to evaluate whether tobramycin accumulates in respiratory secretions with repeated inhalation, compare total and biologically active tobramycin concentrations in CF sputum, and evaluate sputum induction for obtaining secretions for drug concentration assay.

METHODS

Individuals with CF ≥10 years of age were enrolled at the beginning of a course of TSI, 300 mg twice daily for 28 days. Two study visits were conducted, 1-2 days and 24-28 days after initiation of TSI treatment. Induced sputum and expectorated sputum samples were collected for measurement of trough and peak tobramycin concentrations at each visit. Total tobramycin concentrations were measured by high-pressure liquid chromatography and bioactive concentrations by bioassay.

RESULTS

Twenty participants completed the study. Trough concentrations were similar at visits 1 and 2, as were peak concentrations. Trough bioactive and total tobramycin concentrations were similar (mean ratio 1.2, 95% CI 0.56, 1.87), but peak bioactive concentrations were significantly lower than peak total concentrations (mean ratio 0.33, 95% CI 0.23, 0.44). Sputum induction was well tolerated.

CONCLUSIONS

No evidence of significant drug accumulation in respiratory secretions with repeat dosing of TSI was seen. Peak bioactive concentrations, although lower than peak total concentrations, were still generally well within the bactericidal range. Sputum induction as a method for determining airway drug concentrations appears safe and feasible.

Role of respiratory viruses in pulmonary exacerbations in children with cystic fibrosis

BACKGROUND

The role of respiratory viruses in cystic fibrosis (CF) exacerbations is incompletely understood.

METHODS

Cross-sectional study of CF children with a pulmonary exacerbation. Mid-turbinate swabs were tested by a direct immunofluorescent antibody assay and a multiplex PCR panel (ResPlex II v2.0, Qiagen). Resplex II was also applied to sputum or throat swab samples. Pulmonary function tests and quality of life and severity scores were recorded. Sputum cell counts, bacterial density and cytokines were measured.

RESULTS

26/43 (60.5%) subjects tested positive for at least one respiratory virus by any diagnostic method applied to any sample type. Virus-positive patients were younger (p=0.047), more likely to be male (p=0.029), and had higher CF clinical severity (p=0.041) and lower quality of life (physical) scores (p=0.023) but similar IL-8, neutrophil percentage and elastase levels.

CONCLUSIONS

Compared to non-viral exacerbations, viral-related exacerbations were associated with worse severity and quality of life scores but similar pulmonary inflammation.

Mapping the transcriptional machinery of the IL-8 gene in human bronchial epithelial cells

IL-8 released from bronchial epithelial cells infected with Pseudomonas aeruginosa plays a crucial role in the chronic lung pathology of patients affected by cystic fibrosis. Novel anti-inflammatory approaches will benefit from a thorough understanding of the regulatory mechanisms involved in the transcription of this chemokine to identify potential pharmacological targets. We addressed this issue by investigating the role of phosphoproteins and transcription factors (TFs) on transcription of IL-8 gene in the human bronchial epithelial IB3-1, CuFi-1, and Calu-3 cells. P. aeruginosa increased the basal phosphorylation of the ERK1/2 pathway components 90-kDa ribosomal S6 kinase (RSK)1/2 and mitogen- and stress-activated kinase-2 and of the p38 MAPK pathway components p38α/δ/γ and heat shock protein 27 (HSP27). The involvement of these kinases in the expression of IL-8 gene was confirmed with pharmacological inhibitors of ERK1/2, RSK, p38, and HSP27 both at transcription and secretion levels. Transfection of TF decoy oligodeoxynucleotides, designed to interfere with the interaction of the TFs NF-κB, NF-IL6, AP-1, CREB, and CHOP with the corresponding consensus sequences identified in the IL-8 promoter, reduced the P. aeruginosa-dependent transcription of IL-8, suggesting their participation in the transcriptional machinery. Stimulation of IB3-1 cells with IL-1β led to a similar pattern of activation, whereas the pattern of phosphoproteins and of TFs modulated by TNF-α differentiated sharply. In conclusion, the results highlight a novel role for RSK1/2 and HSP27 phosphoproteins and of the cooperative role of the TFs NF-κB, NF-IL6, AP-1, CHOP, and CREB in P. aeruginosa-dependent induction of transcription of the IL-8 gene in human bronchial epithelial cells.

Alcohol fixation of induced sputum samples for applications in rural communities

BACKGROUND

Sputum induction is a tool recommended for the assessment of airway inflammation and disease management. Currently, its use is limited because samples need to be processed within 3 h of induction (ie, while cells are viable); therefore, this procedure is unavailable to most clinicians.

OBJECTIVE

To develop a fixation method for induced sputum samples that allows for a delay in processing while maintaining sample integrity and not altering the standard processing method.

METHODS

Sputum samples were collected and split into three portions: a fresh sample processed using the routine method (within 3 h, using dithiothreitol); fixation in alcohol followed by delayed processing using the routine method (within 48 h to 72 h, using dithiothreitol); and fixation in formaldehyde followed by delayed processing using an alternative method (within 48 h to 72 h, using proteolysis). For each method, cytospins were prepared and differential cell counts were performed.

RESULTS

Fixation in alcohol provides accurate measures of eosinophils and macrophages, but not neutrophils. Formaldehyde fixation provides accurate measures of neutrophils and macrophages, but not eosinophils.

DISCUSSION

Alcohol fixation is a superior method for eosinophil quantification. It requires alteration of standardized methods for sputum sample processing and should be recommended for monitoring eosinophilic airway disease in settings where immediate processing of a sputum sample is not possible.

Using bacterial biomarkers to identify early indicators of cystic fibrosis pulmonary exacerbation onset

Acute periods of pulmonary exacerbation are the single most important cause of morbidity in cystic fibrosis patients, and may be associated with a loss of lung function. Intervening prior to the onset of a substantially increased inflammatory response may limit the associated damage to the airways. While a number of biomarker assays based on inflammatory markers have been developed, providing useful and important measures of disease during these periods, such factors are typically only elevated once the process of exacerbation has been initiated. Identifying biomarkers that can predict the onset of pulmonary exacerbation at an early stage would provide an opportunity to intervene before the establishment of a substantial immune response, with major implications for the advancement of cystic fibrosis care. The precise triggers of pulmonary exacerbation remain to be determined; however, the majority of models relate to the activity of microbes present in the patient's lower airways of cystic fibrosis. Advances in diagnostic microbiology now allow for the examination of these complex systems at a level likely to identify factors on which biomarker assays can be based. In this article, we discuss key considerations in the design and testing of assays that could predict pulmonary exacerbations.

Bergamot (Citrus bergamia Risso) fruit extracts and identified components alter expression of interleukin 8 gene in cystic fibrosis bronchial epithelial cell lines

Background

Cystic fibrosis (CF) airway pathology is a fatal, autosomal, recessive genetic disease characterized by extensive lung inflammation. After induction by TNF-α, elevated concentrations of several pro-inflammatory cytokines (i.e. IL-6, IL-1β) and chemokines (i.e. IL-8) are released from airway epithelial cells. In order to reduce the excessive inflammatory response in the airways of CF patients, new therapies have been developed and in this respect, medicinal plant extracts have been studied. In this article we have investigated the possible use of bergamot extracts (Citrus bergamia Risso) and their identified components to alter the expression of IL-8 associated with the cystic fibrosis airway pathology.

Methods

The extracts were chemically characterized by ¹H-NMR (nuclear magnetic resonance), GC-FID (gas chromatography-flame ionization detector), GC-MS (gas chromatography-mass spectrometry) and HPLC (high pressure liquid chromatography). Both bergamot extracts and main detected chemical constituents were assayed for their biological activity measuring (a) cytokines and chemokines in culture supernatants released from cystic fibrosis IB3-1 cells treated with TNF-α by Bio-Plex cytokine assay; (b) accumulation of IL-8 mRNA by real-time PCR.

Results

The extracts obtained from bergamot (Citrus bergamia Risso) epicarps contain components displaying an inhibitory activity on IL-8. Particularly, the most active molecules were bergapten and citropten. These effects have been confirmed by analyzing mRNA levels and protein release in the CF cellular models IB3-1 and CuFi-1 induced with TNF-α or exposed to heat-inactivated Pseudomonas aeruginosa.

Conclusions

These obtained results clearly indicate that bergapten and citropten are strong inhibitors of IL-8 expression and could be proposed for further studies to verify possible anti-inflammatory properties to reduce lung inflammation in CF patients.

Protein biomarkers in cystic fibrosis research: where next?

Cystic fibrosis is one of the most common life-limiting inherited disorders. Its clinical impact manifests chiefly in the lung, pancreas, gastrointestinal tract and sweat glands, with lung disease typically being most detrimental to health. The median age for survival has increased dramatically over the past decades, largely thanks to advances in understanding of the mechanisms and consequences of disease, leading to the development of better therapies and treatment regimes. The discovery of dysregulated protein biomarkers linked to cystic fibrosis has contributed considerably to this end. This article outlines clinical trials targeting known protein biomarkers, and the current and future contributions of proteomic techniques to cystic fibrosis research. The treatments described range from those designed to provide functional copies of the mutant protein responsible for cystic fibrosis, to others addressing the associated symptoms of chronic inflammation. Preclinical research has employed proteomics to help elucidate pathways and processes implicated in disease that might present opportunities for therapy or prognosis. Global analyses of cystic fibrosis have detected the differential expression of proteins involved in inflammation, proteolytic activity and oxidative stress, which are recognized symptoms of the cystic fibrosis phenotype. The dysregulation of other processes, such as the complement and mitochondrial systems, has also been implicated. A number of studies have focused specifically on proteins that interact with the cystic fibrosis protein, with the goal of restoring its normal proteostasis. Consequently, proteins involved in synthesis, folding, degradation, translocation and localization of the protein have been identified as potential therapeutic targets. Cystic fibrosis patients are prone to lung infections that are thought to contribute to chronic inflammation, and thus proteomic studies have also searched for microbiological biomarkers to use in early infection diagnosis or as indicators of virulence. The review concludes by proposing a future role for proteomics in the high-throughput validation of protein biomarkers under consideration as outcome measures for use in clinical trials and routine disease monitoring.

Potential of anti-inflammatory treatment for cystic fibrosis lung disease

Cystic fibrosis (CF) is the most common life-shortening genetic disorder in Caucasians. With improved diagnosis and treatment, survival has steadily increased. Unfortunately, the overwhelming majority of patients still die from respiratory failure caused by structural damage resulting from airway obstruction, recurrent infection, and inflammation. Here, we discuss the role of inflammation and the development of anti-inflammatory therapies to treat CF lung disease. The inflammatory host response is the least addressed component of CF airway disease at this time. Current challenges in both preclinical and clinical investigation make the identification of suitable anti-inflammatory drugs more difficult. Despite this, many researchers are making significant progress toward this goal and the CF research community has reason to believe that new therapies will emerge from these efforts.

Isolation and characterization of microparticles in sputum from cystic fibrosis patients

Background

Microparticles (MPs) are membrane vesicles released during cell activation and apoptosis. MPs have different biological effects depending on the cell from they originate. Cystic fibrosis (CF) lung disease is characterized by massive neutrophil granulocyte influx in the airways, their activation and eventually apoptosis. We investigated on the presence and phenotype of MPs in the sputum, a rich non-invasive source of inflammation biomarkers, of acute and stable CF adult patients.

Methods

Spontaneous sputum, obtained from 21 CF patients (10 acute and 11 stable) and 7 patients with primary ciliary dyskinesia (PCD), was liquefied with Sputasol. MPs were counted, visualized by electron microscopy, and identified in the supernatants of treated sputum by cytofluorimetry and immunolabelling for leukocyte (CD11a), granulocyte (CD66b), and monocyte-macrophage (CD11b) antigens.

Results

Electron microscopy revealed that sputum MPs were in the 100-500 nm range and did not contain bacteria, confirming microbiological tests. CF sputa contained higher number of MPs in comparison with PCD sputa. Levels of CD11a⁺-and CD66b⁺-, but not CD11b⁺-MPs were significantly higher in CF than in PCD, without differences between acute and stable patients.

Conclusions

In summary, MPs are detectable in sputa obtained from CF patients and are predominantly of granulocyte origin. This novel isolation method for MPs from sputum opens a new opportunity for the study of lung pathology in CF.

Pseudomonas aeruginosa biofilm infections in cystic fibrosis: insights into pathogenic processes and treatment strategies

IMPORTANCE OF THE FIELD

CF airway mucus can be infected by opportunistic microorganisms, notably Pseudomonas aeruginosa. Once organisms are established as biofilms, even the most potent antibiotics have little effect on their viability, especially during late-stage chronic infections. Better understanding of the mechanisms used by P. aeruginosa to circumvent host defenses and therapeutic intervention strategies is critical for advancing novel treatment strategies.

AREAS COVERED IN THIS REVIEW

Inflammatory injury in CF lung, role of neutrophils in pathogenesis, P. aeruginosa biofilms, mucoidy and its relationship with poor airway oxygenation, mechanisms by which P. aeruginosa biofilms in the CF airway can be killed.

WHAT THE READER WILL GAIN

An understanding of the processes that P. aeruginosa undergoes during CF airway disease and clues to better treat such infections in future.

TAKE HOME MESSAGE

The course of CF airway disease is a process involving host and microbial factors that often dictate frequency of pulmonary exacerbations, thus affecting the overall course. In the past decade significant discoveries have been made regarding the pathogenic processes used by P. aeruginosa to bypass the immune system. Many new and exciting features of P. aeruginosa now illuminate weaknesses in the organism that may render it susceptible to inexpensive compounds that force its own destruction.

Lung transplantation for cystic fibrosis

Lung transplantation is a complex, high-risk, potentially life-saving therapy for the end-stage lung disease of cystic fibrosis (CF). The decision to pursue transplantation involves comparing the likelihood of survival with and without transplantation as well as assessing the effect of wait-listing and transplantation on the patient's quality of life. Although recent population-based analyses of the US lung allocation system for the CF population have raised controversies about the survival benefits of transplantation, studies from the United Kingdom and Canada have suggested a definite survival advantage for those receiving transplants. In response to these and other controversies, leaders in transplantation and CF met together in Lansdowne, Virginia, to consider the state of the art in lung transplantation for CF in an international context, focusing on advances in surgical technique, measurement of outcomes, use of prognostic criteria, variations in local control over listing, and prioritization among the United States, Canada, the United Kingdom, and The Netherlands, patient adherence before and after transplantation and other issues in the broader context of lung transplantation. Finally, the conference members carefully considered how efforts to improve outcomes for lung transplantation for CF lung disease might best be studied. This Roundtable seeks to communicate the substance of our discussions.

Measuring and improving respiratory outcomes in cystic fibrosis lung disease: opportunities and challenges to therapy

Cystic fibrosis (CF) is a life-shortening disease with significant morbidity. Despite overall improvements in survival, patients with CF experience frequent pulmonary exacerbations and declining lung function, which often accelerates during adolescence. New treatments target steps in the pathogenesis of lung disease, such as the basic defect in CF (CF Transmembrane Conductance Regulator [CFTR]), pulmonary infections, inflammation, and mucociliary clearance. These treatments offer hope but also present challenges to patients, clinicians, and researchers. Comprehensive assessment of efficacy is critical to identify potentially beneficial treatments. Lung function and pulmonary exacerbation are the most commonly used outcome measures in CF clinical research. Other outcome measures under investigation include measures of CFTR function; biomarkers of infection, inflammation, lung injury and repair; and patient-reported outcomes. Molecular diagnostics may help elucidate the complex CF airway microbiome. As new treatments are developed for patients with CF, efforts should be made to balance treatment burden with quality of life. This review highlights emerging treatments, obstacles to optimizing outcomes, and key future directions for research.

18F-fluorodeoxyglucose-PET/CT imaging of lungs in patients with cystic fibrosis

BACKGROUND

Airway inflammation plays a critical role in the progression of cystic fibrosis (CF) lung disease, and in the destruction of airways and lung parenchyma. Current methods to assess CF lung disease (BAL, spirometry, and high-resolution CT scanning), do not always accurately reflect actual disease states. Fluorodeoxyglucose (FDG)-PET scanning has been used previously to image infection and inflammation. In this study, we assessed the use of (18)F-FDG PET/CT scanning to evaluate and monitor lung inflammation and/or infection in patients with CF.

METHODS

PET/CT scans were performed in 20 patients with CF (age range, 14 to 54 years); 7 of 20 patients underwent repeat PET/CT scans during and after acute exacerbations. The results were compared with clinical information and with images from eight control subjects with no known lung disease.

RESULTS

Foci of enhanced activity were observed on FDG-PET scans of patients with CF but not those of control subjects. Higher focal activity (standardized uptake value, > 3.0) was seen during disease exacerbation and infection. Coregistered CT scan images assisted in the localization of PET foci and showed corresponding CT scan findings, with many additional findings on CT scans that were not seen on PET scans. Foci seen on high-intensity PET scans during exacerbations disappeared after antibiotic therapy and the resolution of exacerbation, while corresponding CT scan findings remained unchanged.

CONCLUSIONS

PET/CT imaging demonstrated the presence of foci of enhanced uptake that may reflect active focal infectious or inflammatory processes in the lungs. These foci can be cleared with antibiotic therapy. Further studies are needed to validate these results and to determine whether FDG-PET/CT scanning can predict the nature/severity of disease in patients with CF.

Sputum desmosine during hospital admission for pulmonary exacerbation in cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) lung disease is characterized by structural changes in the airways and parenchyma. No sputum biomarker exists to measure the degree of active structural destruction during pulmonary exacerbation in patients with CF. The noninvasive measurement of desmosine, a breakdown product of elastin, may reflect ongoing lung injury and serve as a biomarker of short-term damage. Our objectives were to measure desmosine in the sputum of patients with CF hospitalized for treatment of a pulmonary exacerbation and to explore the correlation between desmosine levels and other markers of clinical improvement, including lung function and inflammatory mediators, following hospitalization.

METHODS

Sputum and blood samples collected and lung function measurements were made at multiple time points during hospitalization. We used a repeated measures model, adjusted for age and time between measurements, to compare log-transformed sputum desmosine levels across multiple time points and to correlate those levels with related variables.

RESULTS

Desmosine levels were measured by radioimmunoassay in 71 expectorated sputum samples from 19 patients with CF hospitalized for 26 pulmonary exacerbations (range of results, 0 to 200 pmol/L desmosine/mL). Sputum desmosine levels decreased significantly during the first week of hospitalization (p = 0.04). Desmosine levels were positively associated with plasma C-reactive protein (rho = 0.59; p = 0.03), sputum interleukin-8 (rho = 0.86; p < 0.01), and sputum neutrophil elastase (rho = 0.78; p < 0.01).

CONCLUSIONS

Sputum desmosine, a novel measure of acute structural lung injury, may serve as a marker of structural lung damage occurring during exacerbations of lung disease in CF.

Pseudomonas aeruginosa biofilms in the respiratory tract of cystic fibrosis patients

The present study was undertaken to investigate the appearance and location of Pseudomonas aeruginosa in the cystic fibrosis (CF) lung and in sputum. Samples include preserved tissues of CF patients who died due to chronic P. aeruginosa lung infection prior to the advent of intensive antibiotic therapy, explanted lungs from 3 intensively treated chronically P. aeruginosa infected CF patients and routine sputum from 77 chronically P. aeruginosa infected CF patients. All samples were investigated microscopically using hematoxylin-eosin (HE), Gram and alcian-blue stain, PNA FISH and immunofluorescence for alginate.Investigation of the preserved tissues revealed that prior to aggressive antibiotic therapy, P. aeruginosa infection and destruction of the CF lung correlated with the occurrence of mucoid (alginate) bacteria present in aggregating structures surrounded by pronounced polymorphonuclear-leukocyte (PMN) inflammation in the respiratory zone (9/9). Non-mucoid bacteria were not observed here, and rarely in the conductive zone (1/9). However, in the explanted lungs, the P. aeruginosa aggregates were also mucoid but in contrast to the autopsies, they were very rare in the respiratory zone but abundant in the sputum of the conductive zone (3/3), which also contained abundances of PMNs (3/3). Non-mucoid and planktonic P. aeruginosa were also observed here (3/3).In conclusion, the present intensive antibiotic therapy of chronic P. aeruginosa infections, at the Copenhagen CF Centre, seems to restrain but not eradicate the bacteria from the conductive zone, whereas the remaining healthy respiratory zone appears to be protected, for a long period, from massive biofilm infection. This strongly suggests that the conductive zone serves as a bacterial reservoir where the bacteria are organized in mucoid biofilms within the mucus, protected against antibiotics and host defenses.

Activity and interactions of liposomal antibiotics in presence of polyanions and sputum of patients with cystic fibrosis

Background

To compare the effectiveness of liposomal tobramycin or polymyxin B against Pseudomonas aeruginosa in the Cystic Fibrosis (CF) sputum and its inhibition by common polyanionic components such as DNA, F-actin, lipopolysaccharides (LPS), and lipoteichoic acid (LTA).

Methodology

Liposomal formulations were prepared from a mixture of 1,2-Dimyristoyl-sn-Glycero-3-Phosphocholine (DMPC) or 1,2-Dipalmitoyl-sn-Glycero-3-Phosphocholine (DPPC) and Cholesterol (Chol), respectively. Stability of the formulations in different biological milieus and antibacterial activities compared to conventional forms in the presence of the aforementioned inhibitory factors or CF sputum were evaluated.

Results

The formulations were stable in all conditions tested with no significant differences compared to the controls. Inhibition of antibiotic formulations by DNA/F-actin and LPS/LTA was concentration dependent. DNA/F-actin (125 to 1000 mg/L) and LPS/LTA (1 to 1000 mg/L) inhibited conventional tobramycin bioactivity, whereas, liposome-entrapped tobramycin was inhibited at higher concentrations - DNA/F-actin (500 to 1000 mg/L) and LPS/LTA (100 to 1000 mg/L). Neither polymyxin B formulation was inactivated by DNA/F-actin, but LPS/LTA (1 to 1000 mg/L) inhibited the drug in conventional form completely and higher concentrations of the inhibitors (100 to 1000 mg/L) was required to inhibit the liposome-entrapped polymyxin B. Co-incubation with inhibitory factors (1000 mg/L) increased conventional (16-fold) and liposomal (4-fold) tobramycin minimum bactericidal concentrations (MBCs), while both polymyxin B formulations were inhibited 64-fold.

Conclusions

Liposome-entrapment reduced antibiotic inhibition up to 100-fold and the CFU of endogenous P. aeruginosa in sputum by 4-fold compared to the conventional antibiotic, suggesting their potential applications in CF lung infections.

Revisiting the role of cystic fibrosis transmembrane conductance regulator and counterion permeability in the pH regulation of endocytic organelles

Organellar acidification by the electrogenic vacuolar proton-ATPase is coupled to anion uptake and cation efflux to preserve electroneutrality. The defective organellar pH regulation, caused by impaired counterion conductance of the mutant cystic fibrosis transmembrane conductance regulator (CFTR), remains highly controversial in epithelia and macrophages. Restricting the pH-sensitive probe to CFTR-containing vesicles, the counterion and proton permeability, and the luminal pH of endosomes were measured in various cells, including genetically matched CF and non-CF human respiratory epithelia, as well as cftr(+/+) and cftr(-/-) mouse alveolar macrophages. Passive proton and relative counterion permeabilities, determinants of endosomal, lysosomal, and phagosomal pH-regulation, were probed with FITC-conjugated transferrin, dextran, and Pseudomonas aeruginosa, respectively. Although CFTR function could be documented in recycling endosomes and immature phagosomes, neither channel activation nor inhibition influenced the pH in any of these organelles. CFTR heterologous overexpression also failed to alter endocytic organellar pH. We propose that the relatively large CFTR-independent counterion and small passive proton permeability ensure efficient shunting of the proton-ATPase-generated membrane potential. These results have implications in the regulation of organelle acidification in general and demonstrate that perturbations of the endolysosomal organelles pH homeostasis cannot be linked to the etiology of the CF lung disease.

Human neutrophil peptides and phagocytic deficiency in bronchiectatic lungs

RATIONALE

A well-known clinical paradox is that severe bacterial infections persist in the lungs of patients with cystic fibrosis (CF) despite the abundance of polymorphonuclear neutrophils (PMN) and the presence of a high concentration of human neutrophil peptides (HNP), both of which are expected to kill the bacteria but fail to do so. The mechanisms remain unknown.

OBJECTIVES

This study examined several possible mechanisms to understand this paradox.

METHODS

PMN were isolated from sputum and blood of subjects with and without CF or non-CF bronchiectasis for phagocytic assays. HNP isolated from patients with CF were used to stimulate healthy PMN followed by phagocytic tests.

MEASUREMENTS AND MAIN RESULTS

PMN isolated from the sputum of the bronchiectatic patients display defective phagocytosis that correlated with high concentrations of HNP in the lung. When healthy PMN were incubated with HNP, decreased phagocytic capacity was observed in association with depressed surface Fc gamma RIII, actin-filament remodeling, enhanced intracellular Ca(2+), and degranulation. Treatment of PMN with an intracellular Ca(2+) blocker or alpha1-proteinase inhibitor to attenuate the activity of HNP largely prevented the HNP-induced phagocytic deficiency. Intratracheal instillation of HNP in Pallid mice (genetically deficient in alpha1-proteinase inhibitor) resulted in a greater PMN lung infiltration and phagocytic deficiency compared with wild-type mice.

CONCLUSIONS

HNP or PMN alone exert antimicrobial ability, which was lost as a result of their interaction. These effects of HNP may help explain the clinical paradox seen in patients with inflammatory lung diseases, suggesting HNP as a novel target for clinical therapy.

Highlights of a workshop to discuss targeting inflammation in cystic fibrosis

A workshop to discuss anti-inflammatory approaches in the treatment of CF was held at Novartis Institutes for Biomedical Research (NIBR, Horsham, UK) in March 2008. Key opinion leaders in the field (Hugo De Jonge, Stuart Elborn, Erich Gulbins, Mike Konstan, Rick Moss, Scott Randell and Adriano Rossi), and NIBR scientists were brought together to collectively address three main aims: (i) to identify anti-inflammatory targets in CF, (ii) to evaluate the pros and cons of targeting specific cell types and (iii) to discuss model systems to profile potential therapeutic agents. The highlights of the workshop are captured in this review.

Potential role of high-mobility group box 1 in cystic fibrosis airway disease

RATIONALE

High-mobility group box 1 (HMGB1) is a potent inflammatory mediator elevated in sepsis and rheumatoid arthritis, although its role in cystic fibrosis (CF) lung disease is unknown.

OBJECTIVES

To determine whether HMGB1 contributes to CF lung inflammation, including neutrophil chemotaxis and lung matrix degradation.

METHODS

We used sputum and serum from subjects with CF and a Scnn1b-transgenic (Scnn1b-Tg) mouse model that overexpresses beta-epithelial Na(+) channel in airways and mimics the CF phenotype, including lung inflammation. Human secretions and murine bronchoalveolar lavage fluid (BALF) was assayed for HMGB1 by Western blot and ELISA. Neutrophil chemotaxis was measured in vitro after incubation with human neutrophils. The collagen fragment proline-glycine-proline (PGP) was measured by tandem mass spectroscopy.

MEASUREMENTS AND MAIN RESULTS

HMGB1 was detected in CF sputum at higher levels than secretions from normal individuals. Scnn1b-Tg mice had elevated levels of HMGB1 by Western blot and ELISA. We demonstrated that dose-dependent chemotaxis of human neutrophils stimulated by purified HMGB1 was partially dependent on CXC chemokine receptors and that this could be duplicated in CF sputum and BALF from Scnn1b-Tg mice. Neutralization by anti-HMGB1 antibody, in both the sputum and BALF-reduced chemotaxis, which suggested that HMGB1 contributed to the chemotactic properties of these samples. Intratracheal administration of purified HMGB1 induced neutrophil influx into the airways of mice and promoted the release of PGP. PGP was also elevated in Scnn1b-Tg mice and CF serum.

CONCLUSIONS

HMGB1 expression contributes to pulmonary inflammation and lung matrix degradation in CF airway disease and deserves further investigation as a biomarker and potential therapeutic target.

Challenges in translating plasma proteomics from bench to bedside: update from the NHLBI Clinical Proteomics Programs

The emerging scientific field of proteomics encompasses the identification, characterization, and quantification of the protein content or proteome of whole cells, tissues, or body fluids. The potential for proteomic technologies to identify and quantify novel proteins in the plasma that can function as biomarkers of the presence or severity of clinical disease states holds great promise for clinical use. However, there are many challenges in translating plasma proteomics from bench to bedside, and relatively few plasma biomarkers have successfully transitioned from proteomic discovery to routine clinical use. Key barriers to this translation include the need for "orthogonal" biomarkers (i.e., uncorrelated with existing markers), the complexity of the proteome in biological samples, the presence of high abundance proteins such as albumin in biological samples that hinder detection of low abundance proteins, false positive associations that occur with analysis of high dimensional datasets, and the limited understanding of the effects of growth, development, and age on the normal plasma proteome. Strategies to overcome these challenges are discussed.

Profound functional and signaling changes in viable inflammatory neutrophils homing to cystic fibrosis airways

Blood neutrophils recruited to cystic fibrosis (CF) airways are believed to be rapidly killed by resident bacteria and to passively release elastase and other toxic by-products that promote disease progression. By single-cell analysis, we demonstrate that profound functional and signaling changes readily occur within viable neutrophils recruited to CF airways, compared with their blood counterparts. Airway neutrophils have undergone conventional activation, as shown by decreased intracellular glutathione, increased lipid raft assembly, surface mobilization of CD11b+ and CD66b+ granules, and increased levels of the cytoskeleton-associated phospho-Syk kinase. Unexpectedly, they also mobilize to the surface CD63+ elastase-rich granules, usually confined intracellularly, and lose surface expression of CD16 and CD14, both key receptors in phagocytosis. Furthermore, they express CD80, major histocompatibility complex type II, and the prostaglandin D2 receptor CD294, all normally associated with other lineages, which reflects functional reprogramming. This notion is reinforced by their decreased total phosphotyrosine levels, mirroring a postactivated stage, and increased levels of the phospho-S6 ribosomal protein, a key anabolic switch. Thus, we identified a subset of neutrophils within CF airways with a viable but dysfunctional phenotype. This subset provides a possible therapeutic target and indicates a need to revisit current paradigms of CF airway disease.