DNA concentrations in BAL fluid of cystic fibrosis patients with early lung disease: influence of treatment with dornase alpha

Shifting paradigms in Pseudomonas aeruginosa biofilm research

Biofilms formed by Pseudomonas aeruginosa have long been recognized as a challenge in clinical settings. Cystic fibrosis, endocarditis, device-related infections, and ventilator-associated pneumonia are some of the diseases that are considerably complicated by the formation of bacterial biofilms, which are resistant to most current antimicrobial therapies. Due to intense research efforts, our understanding of the molecular events involved in P. aeruginosa biofilm formation, maintenance, and antimicrobial resistance has advanced significantly. Over the years, several dogmas regarding these multicellular structures have emerged. However, more recent data reveal a remarkable complexity of P. aeruginosa biofilms and force investigators to continually re-evaluate previous findings. This chapter provides examples in which paradigms regarding P. aeruginosa biofilms have been challenged, reflecting the need to critically re-assess what is emerging in this rapidly growing field. In this process, several avenues of research have been opened that will ultimately provide the foundation for the development of preventative measures and therapeutic strategies to successfully treat P. aeruginosa biofilm infections.

Cystic fibrosis: a review of pulmonary and nutritional therapies

In summary, there is a significant interplay between the pulmonary manifestations and nutritional status of CF patients. The advances in CF clinical care in the past 2 decades are mainly attributed to anti-infective therapy as well as aggressive nutritional management. Currently, there are multiple therapeutic agents that are in clinical trial that target either the underlying CFTR defect or the downstream effects of CFTR. The broad spectrum of therapeutic agents being studied as well as the advances in therapies that target the underlying CFTR defect are exciting, making it likely that at least one of the treatments will make a major difference in how we will treat CF in the future.

Is a longer time interval between recombinant human deoxyribonuclease (dornase alfa) and chest physiotherapy better? A multi-center, randomized crossover trial

BACKGROUND

Although the benefits of recombinant human deoxyribonuclease (dornase alfa) in patients with cystic fibrosis (CF) are established, its optimal timing in relation to physiotherapy is unknown. As its enzymatic effect lasts for 6-11 hr, dornase alfa may be more efficacious if the time interval between inhalation and chest physiotherapy is increased. The aim of this study was to investigate if a longer time interval between dornase alfa nebulization and chest physiotherapy improves clinical outcomes of subjects with CF.

METHODS

A single-blind randomized cross-over trial was conducted on subjects with CF from outpatients of four hospitals. Subjects were in stable health and studied over 6 weeks (utilizing 14-day blocks of morning or evening dornase alfa administration with 14 days washout). Usual regimens for physiotherapy and exercise were unaltered. Thus changing the times altered the dwell time of dornase alfa prior to physiotherapy. Long interval was defined as dwell time of >6 hr and short as < or =6 hr. Outcomes were measured at pre and post each regimen.

RESULTS

Twenty subjects aged 7-40 years completed the study. At end of long interval regimen, (median interval = 11.1 hr), FEF(25-75%) and CF-specific quality of life significantly improved compared to baseline values and to short interval regimen (median interval = 0.25 hr) outcomes. FVC, FEV(1), sputum weights, and adherence were similar in both regimens.

CONCLUSIONS

A longer time interval between dornase alfa and physiotherapy is more efficacious than short interval. Administration timing of dornase alfa based on patient choice to incorporate longer interval time is likely to be the best regimen for patients previously established on dornase alfa nebulization.

Traitement de l'inflammation bronchique dans la mucoviscidose

Cystic fibrosis airway inflammation is characterized by neutrophilic efflux and high levels of proinflammatory cytokines such as IL-8 and IL-6. Inhaled corticosteroids are widely used despite lack of evidence of efficacity. Despite evidence of efficacity of ibuprofen, many clinicians have chosen not to use this therapy because of concerns regarding potential side effects. Azithromycin has antiinflammatory properties and is effective in cystic fibrosis (CF) patients. Deoxyribonuclease (rhDNase) has been shown to improve lung function in patients with cystic fibrosis and may also have a positive effect on inflammation. Other antiinflammatory drugs are in the process of validation.

Sputum biomarkers of inflammation in cystic fibrosis lung disease

Pulmonary biomarkers are being used more frequently to monitor disease activity and evaluate response to treatment in individuals with cystic fibrosis (CF). This article summarizes the current state of knowledge of biomarkers of inflammation relevant to CF lung disease, and the tools to measure inflammation, with specific emphasis on sputum. Sputum is a rich, noninvasive source of biomarkers of inflammation and infection. Sputum induction, through the inhalation of hypertonic saline, has expanded the possibilities for monitoring airway inflammation and infection, especially in individuals who do not routinely expectorate sputum. We critically examine the existing data supporting the validity of sputum biomarkers in CF, with an eye toward their application as surrogate endpoints or outcome measures in CF clinical trials. Further validation studies are needed regarding the variability of inflammatory biomarker measurements, and to evaluate how these biomarkers relate to disease severity, and to longitudinal changes in lung function and other clinical endpoints. We highlight the need to incorporate sputum collection, by induction if necessary, and measurement of sputum biomarkers into routine CF clinical care. In the future, pulmonary biomarkers will likely be useful in predicting disease progression, indicating the onset and resolution of a pulmonary exacerbation, and assessing response to current therapies or candidate therapeutics.

Inflammation and anti-inflammatory therapies for cystic fibrosis

Cystic fibrosis lung disease is characterized by a self-propagating cycle of obstruction, infection, and inflammation. The inflammatory response, which accounts for the majority of the morbidity and mortality of the disease, begins early in life, becomes persistent, and is excessive relative to the bacterial burden. Therapies aimed at decreasing the inflammatory response represent a relatively new strategy for treatment. This article reviews the current state of the art of anti-inflammatory therapy in cystic fibrosis and introduces clinical trials that are underway.

Mucolytics in cystic fibrosis

Mucus accumulation in the lower airways is a key feature of cystic fibrosis (CF) lung disease. The major component of mucus in CF is not mucin derived from mucus producing cells but rather pus that includes viscous material such as polymerized DNA derived from degraded neutrophils. This has important implications for mucolytic therapy aiming to improve mucus clearance from the airways, since degradation of mucin may not be a suitable treatment strategy. In addition, thinning of secretions may not always be beneficial, since it may negatively affect certain aspects of mucus transport such as cough clearance. While inhaled N-acetylcysteine has been used as a mucolytic drug in CF for decades, there is little evidence that it has any beneficial effect. Dornase alfa has been shown to reduce pulmonary exacerbations and improve lung function and is currently the only mucolytic agent with proven efficacy in CF. Newer agents targeting other components of CF mucus, such as filamentous actin, are currently in development. Ultimately, drugs that are mucokinetic, which preserve viscoelasticity, rather than mucolytic may prove to be beneficial for CF lung disease in the future.

MUC5AC and MUC5B mucins increase in cystic fibrosis airway secretions during pulmonary exacerbation

RATIONALE

Cystic fibrosis (CF) is believed to be associated with mucus hypersecretion; thus, the principal airway gel-forming mucins, MUC5AC and MUC5B, are also expected to be increased relative to non-CF secretions. However, we have shown that these mucins are decreased during stable CF disease.

OBJECTIVES

In this study, we determine if these mucins increase during a pulmonary exacerbation of CF.

METHODS

Expectorated sputum was collected from 11 adults with CF during stable disease and then during a pulmonary exacerbation and from 12 healthy control subjects. MUC5AC and MUC5B proteins were measured by Western blot. DNA content was measured using microfluorimetry.

RESULTS

MUC5AC protein increased by 908% and MUC5B by 59% (p < 0.05 for both) during an exacerbation compared with periods of stable disease. During stable disease, the vol/vol quantity of MUC5AC protein was 89% less than normal mucus, and the mucin-associated sugars, measured using a lectin binding assay, were 46% less compared with normal mucus. The concentration of DNA in CF sputum did not increase during an exacerbation.

CONCLUSIONS

During a CF exacerbation, concentration of secreted mucin increased to the amount found in mucus from normal subjects, suggesting that the capacity to secrete mucin in response to an infection or inflammatory stimulus is preserved in CF airways. This might help to protect the airway from injury.

CF-Emerging therapies: Modulation inflammation

Persistent and dysregulated inflammation, combined with an exaggerated host response is a major contributor to CF lung disease. As lung disease progresses, neutrophil accumulation in the airways ensues. Modulation of CF airway inflammation may result in either beneficial or deleterious side effects, resulting in more harm than good. Antibiotics, in particular, macrolides which act as a long-term anti-inflammatory agent with an excellent safety profile, and dornase alpha, are very interesting agents; steroids are not indicated in CF except in very special situations, and other promising agents such as leukotriene modifiers, high-dose N-acetylcysteine, anti-elastase and anti-cytokines require further research. Research should focus on early treatment, before lung damage has occurred.

Effect of aerosolized rhDNase (Pulmozyme) on pulmonary colonization in patients with cystic fibrosis

BACKGROUND

Aerosolized recombinant human deoxyribonuclease (rhDNase I (Pulmozyme)) has previously been shown to increase pulmonary function and reduce exacerbations of respiratory symptoms in cystic fibrosis (CF) patients with moderate to severe reduction in pulmonary function.

AIM

To analyse whether aerosolized Pulmozyme could reduce the number of bacterial infections in the lower respiratory airways of CF patients without chronic pulmonary infection.

METHODS

Patients were randomized either to aerosolized Pulmozyme 2(1/2) mg once daily or to no rhDNase treatment. The study period was 1 y, and the study was blinded for the Department of Clinical Microbiology.

RESULTS

Overall, the number of positive cultures was significantly higher in the untreated group (82%) compared with the treated group (72%) (p<0.05). The most striking difference was found for Staphylococcus aureus, with a prevalence of 30% in the untreated group compared with 16% in the treated group (chi2 test, p<0.0001). Pulmonary function (FEV1) in the treated group showed a significant increase of 7.3% compared to 0.9% in the untreated group (p<0.05).

CONCLUSION

Long-term DNase treatment was beneficial to CF patients without chronic lower respiratory tract infection, leading to reduced demand for antibiotics and to improved lung function.

Nonclassical pathway of Pseudomonas aeruginosa DNA-induced interleukin-8 secretion in cystic fibrosis airway epithelial cells

Pseudomonas aeruginosa is a critical colonizer of the respiratory tract in cystic fibrosis. The chronic infections with this microorganism contribute to excessive inflammation and progressive lung damage in cystic fibrosis patients. The full repertoire of Pseudomonas products that promote inflammation in the cystic fibrosis lung is not known. Here we show that P. aeruginosa DNA released from the bacterium, but not human DNA from epithelial cells or Escherichia coli DNA, displays proinflammatory properties and induces human respiratory epithelial cells to secrete interleukin-8 (IL-8), a key chemokine causing excessive neutrophil infiltration in the cystic fibrosis lung. IL-8 secretion was not due to an increase in NF-kappaB- or activator protein-1-dependent IL-8 promoter transcription, but instead depended on p38 and Erk mitogen-activated protein kinases. No secretion of IL-8 was observed using conventional Toll-like receptor 9 ligands (CpG oligonucleotides), although it could be demonstrated that parts of the Toll-like receptor 9-signaling pathway were functional, since class B and C CpG oligonucleotide ligands stimulated production of RANTES chemokine. The IL-8 secretion in response to P. aeruginosa DNA was decreased by treatments that inhibit acidification of intracellular organelles, using chloroquine, a pH-neutralizing compound, or bafilomycin A1, an inhibitor of vacuolar H+-ATPase. These data indicate that DNA released from P. aeruginosa during chronic infections may significantly contribute to the proinflammatory processes in cystic fibrosis. Our findings also show that treatments with drugs diminishing organellar acidification may reduce the inflammatory response in cystic fibrosis.

Anti-inflammatory therapy in cystic fibrosis

Inflammation plays a major role in the pathophysiology of lung disease in CF. This response is probably triggered primarily as a reaction to the inability of the affected lung to resist the invasion of the most common bacterial pathogens seen in this disease, namely, Staphylococcus aureus, Haemophilus influenzae and Pseudomonas aeruginosa. Debate continues as to whether there may or may not be a pre-inflammation of the lungs as part of the basic functional defect of CFTR. The anti-inflammatory treatment modalities most tested to date are: oral corticosteroids, effective but associated with significant long-term side effects, inhaled corticosteroids, so far not proven to be effective probably because of difficulty with absorption through the viscid surface secretions of the lung and ibuprofen, potentially effective but inhibited by the need to monitor drug levels invasively and potential gastrointestinal side effects. The most promising newcomer is macrolide antibiotics such as azithromycin acting as a long-term anti-inflammatory agent with an excellent safety profile.

Recombinant human deoxyribonuclease for cystic fibrosis

BACKGROUND

Recombinant human deoxyribonuclease (rhDNase) is currently used to treat pulmonary disease (the major cause of morbidity and mortality) in cystic fibrosis.

OBJECTIVES

To determine whether the use of rhDNase in cystic fibrosis is associated with improved mortality and morbidity compared to placebo or other mucolytics and to identify any adverse events associated with its use.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group trials register which comprises references identified from comprehensive electronic database searches, handsearching relevant journals and abstracts from conferences. Date of the most recent search of the Group's register: January 2003.

SELECTION CRITERIA

All randomized and quasi-randomized controlled trials where rhDNase was compared to either placebo, standard therapy or another mucolytic.

DATA COLLECTION AND ANALYSIS

Trials were independently assessed for inclusion criteria and the lead reviewer and a colleague carried out analysis of methodological quality and data extraction.

MAIN RESULTS

The searches identified 38 trials, of which 12 trials met our inclusion criteria, including a total of 2294 participants. Three additional studies examined the health care cost from one of the clinical trials. Ten studies compared rhDNase to placebo; one compared daily rhDNase with hypertonic saline and alternate day rhDNase; and one compared daily rhDNase to hypertonic saline. Study duration varied from six days to two years. The number of deaths was not significant between treatment groups. Lung function improved in the treated groups, with significant differences at one month, three months, six months and two years. The mean percentage change in FEV1in the two largest trials were 5.80 (95% CI 3.99 to 7.61) and 3.24 (95% CI 1.03 to 5.45). There was no excess of adverse effects except voice alteration (and rash, which were reported more frequently in one trial in the treated groups. Insufficient data were available to analyse differences in antibiotic treatment, inpatient stay and quality of life.

REVIEWER'S CONCLUSIONS

There is evidence to show that therapy with rhDNase over a one month period is associated with an improvement in lung function in CF, results from a trial lasting six months also showed the same effect. Therapy over a two year period (based on one trial) significantly improved FEV1 in children and there was a non-significant reduction in the risk of infective exacerbations. Voice alteration and rash appear to be the only adverse events reported with increased frequency in randomised controlled trials.