Lung disease in cystic fibrosis--an updated concept

Airway clearance techniques compared to no airway clearance techniques for cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) is an inherited progressive life-limiting disease characterised by the build-up of abnormally thick, sticky mucus affecting mostly the lungs, pancreas, and digestive system. Airway clearance techniques (ACTs), traditionally referred to as chest physiotherapy, are recommended as part of a complex treatment programme for people with CF. The aim of an ACTs is to enhance mucociliary clearance and remove viscous secretions from the airways within the lung to prevent distal airway obstruction. This reduces the infective burden and associated inflammatory effects on the airway epithelia.  There are a number of recognised ACTs, none of which have shown superiority in improving short-term outcomes related to mucus transport. This systematic review, which has been updated regularly since it was first published in 2000, considers the efficacy of ACTs compared to not performing any ACT in adults and children with CF. It is important to continue to review this evidence, particularly the long-term outcomes, given the recent introduction of highly effective modulator therapies and the improved health outcomes and potential changes to CF management associated with these drugs.

OBJECTIVES

To determine the effectiveness and acceptability of airway clearance techniques compared to no airway clearance techniques or cough alone in people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register, which comprises references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings, to 17 October 2022. We searched ongoing trials registers (Clinicaltrials.gov and the WHO International Clinical Trials Registry Platform) to 7 November 2022.

SELECTION CRITERIA

We included randomised or quasi-randomised studies that compared airway clearance techniques (chest physiotherapy) with no airway clearance techniques or spontaneous cough alone in people with CF.

DATA COLLECTION AND ANALYSIS

Both review authors independently assessed study eligibility, extracted data, and assessed the risk of bias of the included studies. We used GRADE methodology to assess the certainty of the evidence.

MAIN RESULTS

We included 11 cross-over studies (153 participants) and one parallel study (41 participants). There were differences between studies in how the interventions were delivered, with several intervention groups combining more than one ACT. One study used autogenic drainage; five used conventional chest physiotherapy; nine used positive expiratory pressure (PEP), with one study varying the water pressure between arms; three studies used oscillating PEP; two used exercise; and two used high-frequency chest wall oscillation (HFCWO). Of the 12 included studies, 10 were single-treatment studies, and two delivered the intervention over two consecutive days (once daily in one study, twice daily in the second). This substantial heterogeneity in the treatment interventions precluded pooling of data for meta-analysis. Blinding of participants, caregivers, and clinicians is impossible in airway clearance studies; we therefore judged all studies at unclear risk of performance bias. Lack of information in eight studies made assessment of risk of bias unclear for most other domains.  We rated the certainty of evidence as low or very low due to the short-term cross-over trial design, small numbers of participants, and uncertain risk of bias across most or all domains. Six studies (84 participants) reported no effect on pulmonary function variables following intervention; but one study (14 participants) reported an improvement in pulmonary function following the intervention in some of the treatment groups. Two studies reported lung clearance index: one (41 participants) found a variable response to treatment with HFCWO, whilst another (15 participants) found no effect on lung clearance index with PEP therapy (low-certainty evidence). Five studies (55 participants) reported that ACTs, including coughing, increased radioactive tracer clearance compared to control, while a further study (eight participants) reported no improvement in radioactive tracer clearance when comparing PEP to control, although coughing was discouraged during the PEP intervention. We rated the certainty of evidence on the effect of ACTs on radioactive tracer clearance as very low. Four studies (46 participants) investigated the weight of mucus cleared from the lungs and reported greater secretions during chest physiotherapy compared to a control. One study (18 participants) reported no differences in sputum weight (very low-certainty evidence).

AUTHORS' CONCLUSIONS

The evidence from this review shows that ACTs may have short-term effects on increasing mucus transport in people with CF. All included studies had short-term follow-up; consequently, we were unable to draw any conclusions on the long-term effects of ACTs compared to no ACTs in people with CF. The evidence in this review represents the use of airway clearance techniques in a CF population before widespread use of cystic fibrosis transmembrane conductance regulator (CFTR) modulators. Further research is needed to determine the effectiveness and acceptability of airway clearance in those treated with highly effective CFTR modulators.

Short-term effects of a novel bronchial drainage device: A pilot cohort study in subjects with cystic fibrosis

Background and Aims

In cystic fibrosis (CF) airways, impaired airway mucociliary clearance and mucus accumulation due to cystic fibrosis transmembrane conductance regulator defects contribute to inflammation, progressive structural lung damage, and decline of lung function. Physiotherapy is essential to promote mucus mobilization and removal in CF and is a key element of rehabilitation measures, but conventional techniques may be suboptimal to mobilize viscous mucus. This study aimed to test the specific effects of a novel bronchial drainage device (BDD) (Simeox®; PhysioAssist) in subjects with CF and evaluate lung function, diaphragm mobility, and sputum properties.

Methods

This prospective monocentric clinical cohort study in the setting of outpatient physiotherapy of CF patients (n = 21) with stable CF lung disease collected pulmonary lung function tests (PFT), diaphragm mobility, and sputum properties before and after two physiotherapy sessions using the novel BDD. PFT was assessed using spirometry and diaphragm mobility using m-mode ultrasound analysis. Spontaneous sputum samples were collected before and after using the BDD and analyzed for microstructure and DNA concentrations.

Results

PFT parameters (FEV1, FVC, MEF25/50/75) were not affected by the use of the BDD. Ultrasound analysis of diaphragm mobility revealed an increase in maximum diaphragm excursion upon the intervention. Mucus analysis demonstrated altered microstructure and higher DNA concentrations collected after using the BDD compared to samples collected before. Pearson correlation analysis showed significant correlations between changes in mucus properties and DNA levels in respective mucus samples.

Conclusion

Our results demonstrate that the novel BDD improves diaphragm mobility and alters sputum properties in subjects with CF. The novel BDD with unique properties may be further studied as a device in CF-specific physiotherapy to facilitate sputum mobilization of CF patients.

Investigating outcome measures for assessing airway clearance techniques in adults with cystic fibrosis: protocol of a single-centre randomised controlled crossover trial

Introduction

Airway clearance techniques (ACTs) are a gold standard of cystic fibrosis management; however, the majority of research evidence for their efficacy is of low standard; often attributed to the lack of sensitivity from outcome measures (OMs) used historically. This randomised controlled trial (RCT) investigates these standard OMs (sputum weight, forced expiratory volume in 1 s) and new OMs (electrical impedance tomography (EIT), multiple breath washout (MBW) and impulse oscillometry (IOS)) to determine the most useful measures of ACT.

Methods and analysis

This is a single-centre RCT with crossover design. Participants perform MBW, IOS and spirometry, and then are randomised to either rest or supervised ACT lasting 30–60 min. MBW, IOS and spirometry are repeated immediately afterwards. EIT and sputum are collected during rest/ACT. On a separate day, the OMs are performed with the other intervention. Primary endpoint is difference in change in OMs before and after ACT/rest. Sample size was calculated with 80% power and significance of 5% for each OM (target n=64).

Ethics and dissemination

Ethics approval was gained from the London–Chelsea Research Ethics Committee (reference 16/LO/0995, project ID 154635). Dissemination will involve scientific conference presentation and publication in a peer-reviewed journal.

Trial registration numbers

ISRCTN11220163 and NCT02721498.

Oscillating devices for airway clearance in people with cystic fibrosis

BACKGROUND

Chest physiotherapy is widely prescribed to assist the clearance of airway secretions in people with cystic fibrosis. Oscillating devices generate intra- or extra-thoracic oscillations orally or external to the chest wall. Internally they create variable resistances within the airways, generating controlled oscillating positive pressure which mobilises mucus. Extra-thoracic oscillations are generated by forces outside the respiratory system, e.g. high frequency chest wall oscillation. This is an update of a previously published review.

OBJECTIVES

To identify whether oscillatory devices, oral or chest wall, are effective for mucociliary clearance and whether they are equivalent or superior to other forms of airway clearance in the successful management of secretions in people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches and hand searches of relevant journals and abstract books of conference proceedings. Latest search of the Cystic Fibrosis Trials Register: 29 July 2019. In addition we searched the trials databases ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform. Latest search of trials databases: 15 August 2019.

SELECTION CRITERIA

Randomised controlled studies and controlled clinical studies of oscillating devices compared with any other form of physiotherapy in people with cystic fibrosis. Single-treatment interventions (therapy technique used only once in the comparison) were excluded.

DATA COLLECTION AND ANALYSIS

Two authors independently applied the inclusion criteria to publications, assessed the quality of the included studies and assessed the evidence using GRADE.

MAIN RESULTS

The searches identified 82 studies (330 references); 39 studies (total of 1114 participants) met the inclusion criteria. Studies varied in duration from up to one week to one year; 20 of the studies were cross-over in design. The studies also varied in type of intervention and the outcomes measured, data were not published in sufficient detail in most of these studies, so meta-analysis was limited. Few studies were considered to have a low risk of bias in any domain. It is not possible to blind participants and clinicians to physiotherapy interventions, but 13 studies did blind the outcome assessors. The quality of the evidence across all comparisons ranged from low to very low. Forced expiratory volume in one second was the most frequently measured outcome and while many of the studies reported an improvement in those people using a vibrating device compared to before the study, there were few differences when comparing the different devices to each other or to other airway clearance techniques. One study identified an increase in frequency of exacerbations requiring antibiotics whilst using high frequency chest wall oscillation when compared to positive expiratory pressure (low-quality evidence). There were some small but significant changes in secondary outcome variables such as sputum volume or weight, but not wholly in favour of oscillating devices and due to the low- or very low-quality evidence, it is not clear whether these were due to the particular intervention. Participant satisfaction was reported in 13 studies but again with low- or very low-quality evidence and not consistently in favour of an oscillating device, as some participants preferred breathing techniques or techniques used prior to the study interventions. The results for the remaining outcome measures were not examined or reported in sufficient detail to provide any high-level evidence.

AUTHORS' CONCLUSIONS

There was no clear evidence that oscillation was a more or less effective intervention overall than other forms of physiotherapy; furthermore there was no evidence that one device is superior to another. The findings from one study showing an increase in frequency of exacerbations requiring antibiotics whilst using an oscillating device compared to positive expiratory pressure may have significant resource implications. More adequately-powered long-term randomised controlled trials are necessary and outcomes measured should include frequency of exacerbations, individual preference, adherence to therapy and general satisfaction with treatment. Increased adherence to therapy may then lead to improvements in other parameters, such as exercise tolerance and respiratory function. Additional evidence is needed to evaluate whether oscillating devices combined with other forms of airway clearance is efficacious in people with cystic fibrosis.There may also be a requirement to consider the cost implication of devices over other forms of equally advantageous airway clearance techniques. Using the GRADE method to assess the quality of the evidence, we judged this to be low or very low quality, which suggests that further research is very likely to have an impact on confidence in any estimate of effect generated by future interventions.

Positive expiratory pressure physiotherapy for airway clearance in people with cystic fibrosis

BACKGROUND

Chest physiotherapy is widely prescribed to assist the clearance of airway secretions in people with cystic fibrosis (CF). Positive expiratory pressure (PEP) devices provide back pressure to the airways during expiration. This may improve clearance by building up gas behind mucus via collateral ventilation and by temporarily increasing functional residual capacity. The developers of the PEP technique recommend using PEP with a mask in order to avoid air leaks via the upper airways and mouth. In addition, increasing forced residual capacity (FRC) has not been demonstrated using mouthpiece PEP. Given the widespread use of PEP devices, there is a need to determine the evidence for their effect. This is an update of a previously published review.

OBJECTIVES

To determine the effectiveness and acceptability of PEP devices compared to other forms of physiotherapy as a means of improving mucus clearance and other outcomes in people with CF.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising of references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. The electronic database CINAHL was also searched from 1982 to 2017. Most recent search of the Group's CF Trials Register: 20 February 2019.

SELECTION CRITERIA

Randomised controlled studies in which PEP was compared with any other form of physiotherapy in people with CF. This included, postural drainage and percussion (PDPV), active cycle of breathing techniques (ACBT), oscillating PEP devices, thoracic oscillating devices, bilevel positive airway pressure (BiPaP) and exercise.

DATA COLLECTION AND ANALYSIS

Three authors independently applied the inclusion and exclusion criteria to publications, assessed the risk of bias of the included studies and assessed the quality of the evidence using the GRADE recommendations.

MAIN RESULTS

A total of 28 studies (involving 788 children and adults) were included in the review; 18 studies involving 296 participants were cross-over in design. Data were not published in sufficient detail in most of these studies to perform any meta-analysis. In 22 of the 28 studies the PEP technique was performed using a mask, in three of the studies a mouthpiece was used with nose clips and in three studies it was unclear whether a mask or mouthpiece was used. These studies compared PEP to ACBT, autogenic drainage (AD), oral oscillating PEP devices, high-frequency chest wall oscillation (HFCWO) and BiPaP and exercise. Forced expiratory volume in one second was the review's primary outcome and the most frequently reported outcome in the studies (24 studies, 716 participants). Single interventions or series of treatments that continued for up to three months demonstrated little or no difference in effect between PEP and other methods of airway clearance on this outcome (low- to moderate-quality evidence). However, long-term studies had equivocal or conflicting results regarding the effect on this outcome (low- to moderate-quality evidence). A second primary outcome was the number of respiratory exacerbations. There was a lower exacerbation rate in participants using PEP compared to other techniques when used with a mask for at least one year (five studies, 232 participants; moderate- to high-quality evidence). In one of the included studies which used PEP with a mouthpiece, it was reported (personal communication) that there was no difference in the number of respiratory exacerbations (66 participants, low-quality evidence). Participant preference was reported in 10 studies; and in all studies with an intervention period of at least one month, this was in favour of PEP. The results for the remaining outcome measures (including our third primary outcome of mucus clearance) were not examined or reported in sufficient detail to provide any high-quality evidence; only very low- to moderate-quality evidence was available for other outcomes. There was limited evidence reported on adverse events; these were measured in five studies, two of which found no events. In a study where infants performing either PEP or PDPV experienced some gastro-oesophageal reflux , this was more severe in the PDPV group (26 infants, low-quality evidence). In PEP versus oscillating PEP, adverse events were only reported in the flutter group (five participants complained of dizziness, which improved after further instructions on device use was provided) (22 participants, low-quality evidence). In PEP versus HFCWO, from one long-term high-quality study (107 participants) there was little or no difference in terms of number of adverse events; however, those in the PEP group had fewer adverse events related to the lower airways when compared to HFCWO (high-certainty evidence). Many studies had a risk of bias as they did not report how the randomisation sequence was either generated or concealed. Most studies reported the number of dropouts and also reported on all planned outcome measures.

AUTHORS' CONCLUSIONS

The evidence provided by this review is of variable quality, but suggests that all techniques and devices described may have a place in the clinical treatment of people with CF. Following meta-analyses of the effects of PEP versus other airway clearance techniques on lung function and patient preference, this Cochrane Review demonstrated that there was high-quality evidence that showed a significant reduction in pulmonary exacerbations when PEP using a mask was compared with HFCWO. It is important to note that airway clearance techniques should be individualised throughout life according to developmental stages, patient preferences, pulmonary symptoms and lung function. This also applies as conditions vary between baseline function and pulmonary exacerbations.

Randomised cross-over trial evaluating the short-term effects of non-invasive ventilation as an adjunct to airway clearance techniques in adults with cystic fibrosis

Introduction

Non-invasive ventilation (NIV) is used in cystic fibrosis (CF) to support airway clearance techniques (ACTs) by augmenting tidal volumes and reducing patient effort. However, the evidence base for this is limited. We hypothesised that NIV, in addition to usual ACT, would increase sputum clearance. In addition, we investigated ease of sputum clearance (EoC), work of breathing (WoB) and NIV tolerability.

Methods

Adults with CF (16+ years) at the end of hospitalisation for a pulmonary exacerbation were randomised to a cross-over trial of NIV-supported ACT or ACT alone in two consecutive days. No other changes to standard care were made. The primary outcome was the total 24-hour expectorated sputum wet weight after the intervention. Spirometry was completed pre-treatment and post-treatment. Oxygen saturations were measured pre-treatment, during treatment and post-treatment. EoC and WoB were assessed using Visual Analogue Scale.

Results

14 subjects completed the study (7 male, mean age 35 [SD 17] years, mean forced expiratory volume in 1 s [FEV₁] 49 [20] % predicted). The difference between treatment regimens was −0.98 g sputum (95% CI −11.5 to 9.6, p=0.84) over 24 hours. During treatment oxygen saturations were significantly higher with NIV-supported ACT (mean difference 2.0, 95% CI 0.9 to 2.6, p=0.0004). No other significant differences were found in post-treatment FEV₁, EoC, WoB, oxygen saturations or subject preference.

Conclusions

There was no difference in treatment effect between NIV-supported ACT and ACT alone, although the study was underpowered. Oxygen saturations were significantly higher during NIV-supported ACT, but with no effect on post-treatment saturations. NIV was well tolerated.

Trial registration number

NCT01885650.

Oscillating devices for airway clearance in people with cystic fibrosis

BACKGROUND

Chest physiotherapy is widely prescribed to assist the clearance of airway secretions in people with cystic fibrosis. Oscillating devices generate intra- or extra-thoracic oscillations orally or external to the chest wall. Internally they create variable resistances within the airways, generating controlled oscillating positive pressure which mobilises mucus. Extra-thoracic oscillations are generated by forces outside the respiratory system, e.g. high frequency chest wall oscillation. This is an update of a previously published review.

OBJECTIVES

To identify whether oscillatory devices, oral or chest wall, are effective for mucociliary clearance and whether they are equivalent or superior to other forms of airway clearance in the successful management of secretions in people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches and hand searches of relevant journals and abstract books of conference proceedings. Latest search of the Cystic Fibrosis Trials Register: 27 April 2017.In addition we searched the trials databases ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform. Latest search of trials databases: 26 April 2017.

SELECTION CRITERIA

Randomised controlled studies and controlled clinical studies of oscillating devices compared with any other form of physiotherapy in people with cystic fibrosis. Single-treatment interventions (therapy technique used only once in the comparison) were excluded.

DATA COLLECTION AND ANALYSIS

Two authors independently applied the inclusion criteria to publications and assessed the quality of the included studies.

MAIN RESULTS

The searches identified 76 studies (302 references); 35 studies (total of 1138 participants) met the inclusion criteria. Studies varied in duration from up to one week to one year; 20 of the studies were cross-over in design. The studies also varied in type of intervention and the outcomes measured, data were not published in sufficient detail in most of these studies, so meta-analysis was limited. Few studies were considered to have a low risk of bias in any domain. It is not possible to blind participants and clinicians to physiotherapy interventions, but 11 studies did blind the outcome assessors.Forced expiratory volume in one second was the most frequently measured outcome. One long-term study (seven months) compared oscillatory devices with either conventional physiotherapy or breathing techniques and found statistically significant differences in some lung function parameters in favour of oscillating devices. One study identified an increase in frequency of exacerbations requiring antibiotics whilst using high frequency chest wall oscillation when compared to positive expiratory pressure. There were some small but significant changes in secondary outcome variables such as sputum volume or weight, but not wholly in favour of oscillating devices. Participant satisfaction was reported in 15 studies but this was not specifically in favour of an oscillating device, as some participants preferred breathing techniques or techniques used prior to the study interventions. The results for the remaining outcome measures were not examined or reported in sufficient detail to provide any high level evidence.

AUTHORS' CONCLUSIONS

There was no clear evidence that oscillation was a more or less effective intervention overall than other forms of physiotherapy; furthermore there was no evidence that one device is superior to another. The findings from one study showing an increase in frequency of exacerbations requiring antibiotics whilst using an oscillating device compared to positive expiratory pressure may have significant resource implications. More adequately-powered long-term randomised controlled trials are necessary and outcomes measured should include frequency of exacerbations, individual preference, adherence to therapy and general satisfaction with treatment. Increased adherence to therapy may then lead to improvements in other parameters, such as exercise tolerance and respiratory function. Additional evidence is needed to evaluate whether oscillating devices combined with other forms of airway clearance is efficacious in people with cystic fibrosis.There may also be a requirement to consider the cost implication of devices over other forms of equally advantageous airway clearance techniques. Using the GRADE method to assess the quality of the evidence, we judged this to be low or very low quality, which suggests that further research is very likely to have an impact on confidence in any estimate of effect generated by future interventions.

The clinical benefits of long-term supplementation with omega-3 fatty acids in cystic fibrosis patients - A pilot study

Effectiveness of omega-3 supplementation in cystic fibrosis (CF) remains controversial. This study sought to evaluate clinical status, exercise tolerance, inflammatory parameters, and erythrocyte fatty acid profile after 1 year of oral omega-3 supplementation in CF patients. Fifteen ΔF508-homozygous patients undergoing chronic azithromycin were randomized to receive omega-3 fish oil supplementation at a dose of 60mg/Kg/day or placebo. In comparison with the previous year, in the supplemented group, the number of pulmonary exacerbations decreased at 12 months (1.7 vs. 3.0, p<0.01), as did the duration of antibiotic therapy (26.5 days vs. 60.0 days, p<0.025). Supplementation significantly increased the levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) as early as <3 months of administration, with concomitant decreases in arachidonic acid (AA) levels. This pilot study suggests that long-term omega-3 supplementation offers several clinical benefits as to the number of exacerbations and duration of antibiotic therapy in CF patients.

Chest physiotherapy compared to no chest physiotherapy for cystic fibrosis

BACKGROUND

Chest physiotherapy is widely used in people with cystic fibrosis in order to clear mucus from the airways. This is an updated version of previously published reviews.

OBJECTIVES

To determine the effectiveness and acceptability of chest physiotherapy compared to no treatment or spontaneous cough alone to improve mucus clearance in cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Date of the most recent search of the Group's Cystic Fibrosis Trials Register: 02 June 2015.

SELECTION CRITERIA

Randomised or quasi-randomised clinical studies in which a form of chest physiotherapy (airway clearance technique) were taken for consideration in people with cystic fibrosis compared with either no physiotherapy treatment or spontaneous cough alone.

DATA COLLECTION AND ANALYSIS

Both authors independently assessed study eligibility, extracted data and assessed the risk of bias in the included studies. There was heterogeneity in the published outcomes, with variable reporting which meant pooling of the data for meta-analysis was not possible.

MAIN RESULTS

The searches identified 157 studies, of which eight cross-over studies (data from 96 participants) met the inclusion criteria. There were differences between studies in the way that interventions were delivered, with several of the intervention groups combining more than one treatment modality. One included study looked at autogenic drainage, six considered conventional chest physiotherapy, three considered oscillating positive expiratory pressure, seven considered positive expiratory pressure and one considered high pressure positive expiratory pressure. Of the eight studies, six were single-treatment studies and in two, the treatment intervention was performed over two consecutive days (once daily in one, twice daily in the other). This enormous heterogeneity in the treatment interventions prevented any meta-analyses from being performed. Blinding of participants, caregivers or clinicians in airway clearance studies is impossible; therefore this was not considered as a high risk of bias in the included studies. Lack of protocol data made assessment of risk of bias unclear for the majority of other criteria.Four studies, involving 28 participants, reported a higher amount of expectorated secretions during chest physiotherapy as compared to a control. One study, involving 18 participants, reported no significant differences in sputum weight. In five studies radioactive tracer clearance was used as an outcome variable. In three of these (28 participants) it was reported that chest physiotherapy, including coughing, increased radioactive tracer clearance as compared to the control period. One study (12 participants) reported increased radioactive tracer clearance associated with all interventions compared to control, although this was only reported to have reached significance for postural drainage with percussion and vibrations; and the remaining study (eight participants) reported no significant difference in radioactive tracer clearance between chest physiotherapy, without coughing, compared to the control period. Three studies, involving 42 participants reported no significant effect on pulmonary function variables following intervention; but one further study did report significant improvement in pulmonary function following the intervention in some of the treatment groups.

AUTHORS' CONCLUSIONS

The results of this review show that airway clearance techniques have short-term effects in the terms of increasing mucus transport. No evidence was found on which to draw conclusions concerning the long-term effects.

Positive expiratory pressure physiotherapy for airway clearance in people with cystic fibrosis

BACKGROUND

Chest physiotherapy is widely prescribed to assist the clearance of airway secretions in people with cystic fibrosis. Positive expiratory pressure (PEP) devices provide back pressure to the airways during expiration. This may improve clearance by building up gas behind mucus via collateral ventilation and by temporarily increasing functional residual capacity. Given the widespread use of PEP devices, there is a need to determine the evidence for their effect. This is an update of a previously published review.

OBJECTIVES

To determine the effectiveness and acceptability of PEP devices compared to other forms of physiotherapy as a means of improving mucus clearance and other outcomes in people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising of references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. The electronic database CINAHL was also searched from 1982 to 2013.Most recent search of the Group's Cystic Fibrosis Trial Register: 02 December 2014.

SELECTION CRITERIA

Randomised controlled studies in which PEP was compared with any other form of physiotherapy in people with cystic fibrosis. This included, postural drainage and percussion, active cycle of breathing techniques, oscillating PEP devices, thoracic oscillating devices, bilevel positive airway pressure (BiPaP) and exercise. Studies also had to include one or more of the following outcomes: change in forced expiratory volume in one second; number of respiratory exacerbations; a direct measure of mucus clearance; weight of expectorated secretions; other pulmonary function parameters; a measure of exercise tolerance; ventilation scans; cost of intervention; and adherence to treatment.

DATA COLLECTION AND ANALYSIS

Three authors independently applied the inclusion and exclusion criteria to publications and assessed the risk of bias of the included studies.

MAIN RESULTS

A total of 26 studies (involving 733 participants) were included in the review. Eighteen studies involving 296 participants were cross-over in design. Data were not published in sufficient detail in most of these studies to perform any meta-analysis. These studies compared PEP to active cycle of breathing techniques (ACBT), autogenic drainage (AD), oral oscillating PEP devices, high frequency chest wall oscillation (HFCWO) and Bi level PEP devices (BiPaP) and exercise.Forced expiratory volume in one second was the review's primary outcome and the most frequently reported outcome in the studies. Single interventions or series of treatments that continued for up to three months demonstrated no significant difference in effect between PEP and other methods of airway clearance on this outcome. However, long-term studies had equivocal or conflicting results regarding the effect on this outcome. A second primary outcome was the number of respiratory exacerbations. There was a lower exacerbation rate in participants using PEP compared to other techniques when used with a mask for at least one year. Participant preference was reported in 10 studies; and in all studies with an intervention period of at least one month, this was in favour of PEP. The results for the remaining outcome measures were not examined or reported in sufficient detail to provide any high-level evidence. The only reported adverse event was in a study where infants performing either PEP or postural drainage with percussion experienced some gastro-oesophageal reflux. This was more severe in the postural drainage with percussion group. Many studies had a risk of bias as they did not report how the randomisation sequence was either generated or concealed. Most studies reported the number of dropouts and also reported on all planned outcome measures.

AUTHORS' CONCLUSIONS

Following meta-analyses of the effects of PEP versus other airway clearance techniques on lung function and patient preference, this Cochrane review demonstrated that there was a significant reduction in pulmonary exacerbations in people using PEP compared to those using HFCWO in the study where exacerbation rate was a primary outcome measure. It is important to note, however, that there may be individual preferences with respect to airway clearance techniques and that each patient needs to be considered individually for the selection of their optimal treatment regimen in the short and long term, throughout life, as circumstances including developmental stages, pulmonary symptoms and lung function change over time. This also applies as conditions vary between baseline function and pulmonary exacerbations.However, meta-analysis in this Cochrane review has shown a significant reduction in pulmonary exacerbations in people using PEP in the few studies where exacerbation rate was a primary outcome measure.

Oscillating devices for airway clearance in people with cystic fibrosis

BACKGROUND

Chest physiotherapy is widely prescribed to assist the clearance of airway secretions in people with cystic fibrosis. Oscillating devices generate intra- or extra-thoracic oscillations orally or external to the chest wall. Internally they create variable resistances within the airways, generating controlled oscillating positive pressure which mobilises mucus. Extra-thoracic oscillations are generated by forces outside the respiratory system, e.g. high frequency chest wall oscillation.

OBJECTIVES

To identify whether oscillatory devices, oral or chest wall, are effective for mucociliary clearance and whether they are equivalent or superior to other forms of airway clearance in the successful management of secretions in people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches and hand searches of relevant journals and abstract books of conference proceedings. Latest search of the Cystic Fibrosis Trials Register: 13 January 2014.

SELECTION CRITERIA

Randomised controlled studies and controlled clinical studies of oscillating devices compared with any other form of physiotherapy in people with cystic fibrosis. Single-treatment interventions (therapy technique used only once in the comparison) were excluded.

DATA COLLECTION AND ANALYSIS

Two authors independently applied the inclusion criteria to publications and assessed the quality of the included studies.

MAIN RESULTS

The searches identified 68 studies with a total of 288 references; 35 studies (total of 1050 participants) met the inclusion criteria. Studies varied in duration from up to one week to one year; 20 of the studies were cross-over in design. The studies also varied in type of intervention and the outcomes measured, furthermore data were not published in sufficient detail in most of these studies, so meta-analysis was limited. Few studies were considered to have a low risk of bias in any domain. It is not possible to blind participants and clinicians to physiotherapy interventions, but 10 studies did blind the outcome assessors.Forced expiratory volume in one second was the most frequently measured outcome. One long-term study (seven months) compared oscillatory devices with either conventional physiotherapy or breathing techniques and found statistically significant differences in some lung function parameters in favour of oscillating devices. One study identified an increase in frequency of exacerbations requiring antibiotics whilst using high frequency chest wall oscillation when compared to positive expiratory pressure. There were some small but significant changes in secondary outcome variables such as sputum volume or weight, but not wholly in favour of oscillating devices. Participant satisfaction was reported in 15 studies but this was not specifically in favour of an oscillating device, as some participants preferred breathing techniques or techniques used prior to the study interventions. The results for the remaining outcome measures were not examined or reported in sufficient detail to provide any high level evidence.

AUTHORS' CONCLUSIONS

There was no clear evidence that oscillation was a more or less effective intervention overall than other forms of physiotherapy; furthermore there was no evidence that one device is superior to another. The findings from one study showing an increase in frequency of exacerbations requiring antibiotics whilst using an oscillating device compared to positive expiratory pressure may have significant resource implications. More adequately-powered long-term randomised controlled trials are necessary and outcomes measured should include frequency of exacerbations, patient preference, adherence to therapy and general satisfaction with treatment. Increased adherence to therapy may then lead to improvements in other parameters, such as exercise tolerance and respiratory function. Additional evidence is needed to evaluate whether oscillating devices combined with other forms of airway clearance is efficacious in people with cystic fibrosis.

Chest physiotherapy compared to no chest physiotherapy for cystic fibrosis

BACKGROUND

Chest physiotherapy is widely used in people with cystic fibrosis in order to clear mucus from the airways.

OBJECTIVES

To determine the effectiveness and acceptability of chest physiotherapy compared to no treatment or spontaneous cough alone to improve mucus clearance in cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Date of the most recent search of the Group's Cystic Fibrosis Trials Register: 04 February 2013.

SELECTION CRITERIA

Randomised or quasi-randomised clinical studies in which a form of chest physiotherapy (airway clearance technique) were taken for consideration in people with cystic fibrosis compared with either no physiotherapy treatment or spontaneous cough alone.

DATA COLLECTION AND ANALYSIS

Both authors independently assessed study eligibility, extracted data and assessed study quality. There was heterogeneity in the published outcomes, with variable reporting which meant pooling of the data for meta-analysis was not possible.

MAIN RESULTS

The searches identified 144 studies, of which eight cross-over studies (data from 96 participants) met the inclusion criteria. There were differences between studies in the way that interventions were delivered, with several of the intervention groups combining more than one treatment modality. One included study looked at autogenic drainage, six considered conventional chest physiotherapy, three considered oscillating positive expiratory pressure, seven considered positive expiratory pressure and one considered high pressure positive expiratory pressure. Of the eight studies, six were single-treatment studies and in two, the treatment intervention was performed over two consecutive days (once daily in one, twice daily in the other). This enormous heterogeneity in the treatment interventions prevented any meta-analyses from being performed.Four studies, involving 28 participants, reported a higher amount of expectorated secretions during chest physiotherapy as compared to a control. One study, involving 18 participants, reported no significant differences in sputum weight. In five studies radioactive tracer clearance was used as an outcome variable. In three of these (28 participants) it was reported that chest physiotherapy, including coughing, increased radioactive tracer clearance as compared to the control period. One study (12 participants) reported increased radioactive tracer clearance associated with all interventions compared to control, although this was only reported to have reached significance for postural drainage with percussion and vibrations; and the remaining study (eight participants) reported no significant difference in radioactive tracer clearance between chest physiotherapy, without coughing, compared to the control period. Three studies, involving 42 participants reported no significant effect on pulmonary function variables following intervention; but one further study did report significant improvement in pulmonary function following the intervention in some of the treatment groups.

AUTHORS' CONCLUSIONS

The results of this review show that airway clearance techniques have short-term effects in the terms of increasing mucus transport. No evidence was found on which to draw conclusions concerning the long-term effects.

Oscillating devices for airway clearance in people with cystic fibrosis

BACKGROUND

Chest physiotherapy is widely prescribed to assist the clearance of airway secretions in people with cystic fibrosis (CF). Oscillating devices generate intra- or extra-thoracic oscillations orally or external to the chest wall. Internally they create variable resistances within the airways, generating controlled oscillating positive pressure which mobilises mucus. Extra-thoracic oscillations are generated by forces outside the respiratory system, e.g. high frequency chest wall oscillation.

OBJECTIVES

To determine the effectiveness and acceptability of oscillating devices compared to other forms of physiotherapy to improve respiratory function, mucus clearance and other outcomes in people with CF.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches and hand searches of relevant journals and abstract books of conference proceedings. Most recent search of the Cystic Fibrosis Trials Register: November 2008.

SELECTION CRITERIA

Randomised controlled studies and controlled clinical studies of oscillating devices compared with any other form of physiotherapy in people with CF.

DATA COLLECTION AND ANALYSIS

Two authors independently applied the inclusion criteria to publications and assessed the quality of the included studies.

MAIN RESULTS

Two hundred and sixty-five studies were identified; thirty studies (total of 708 participants) met the inclusion criteria. Single treatment interventions (therapy technique used only once in the comparison) were excluded. Studies varied in duration from up to one week to one year in duration. Nineteen of the studies were cross-over in design. Data were not published in sufficient detail in most of these studies to perform meta-analysis.Forced expiratory volume in one second (FEV(1)) was the most frequently measured outcome. Results did not show significant difference in effect between oscillating devices and other methods of airway clearance on FEV(1) or other lung function parameters. Where there has been a small but significant change in secondary outcome variables such as sputum volume or weight this has not been wholly in favour of oscillating devices. Participant satisfaction was reported in eleven studies, but this was not specifically in favour of an oscillating device as some participants preferred breathing techniques or techniques used prior to the study interventions. The results for the remaining outcome measures were not examined or reported in sufficient detail to provide any high level evidence.

AUTHORS' CONCLUSIONS

There was no clear evidence that oscillation was a more or less effective intervention overall than other forms of physiotherapy. More adequately-powered long-term randomised controlled trials are needed.

Effects of changes in lung volume on oscillatory flow rate during high-frequency chest wall oscillation

BACKGROUND

The effectiveness of high-frequency chest wall oscillation (HFCWO) in mucolysis and mucous clearance is thought to be dependant on oscillatory flow rate (Fosc). Therefore, increasing Fosc during HFCWO may have a clinical benefit.

OBJECTIVES

To examine effects of continuous positive airway pressure (CPAP) on Fosc at two oscillation frequencies in healthy subjects and patients with airway obstruction.

METHODS

Five healthy subjects and six patients with airway obstruction underwent 12 randomized trials of HFCWO (CPAP levels of 0 cm H2O, 2 cm H2O, 4 cm H2O, 6 cm H2O, 8 cm H2O and 10 cm H2O at frequencies of 10 Hz and 15 Hz) within a body plethysmograph, allowing measurements of changes in lung volume. Fosc was measured by reverse plethysmography using a 20 L isothermic chamber near the mouth. At the end of each randomized trial, an inspiratory capacity manoeuvre was used to determine end-expiratory lung volume (EELV).

RESULTS

EELV increased significantly (P<0.05) with each level of CPAP regardless of oscillation frequency. Fosc also significantly increased with CPAP (P<0.05) and it was correlated with EELV (r=0.7935, P<0.05) in obstructed patients but not in healthy subjects (r=0.125, P=0.343). There were no significant differences in perceived comfort across the levels of CPAP.

CONCLUSIONS

Significant increases in Fosc with CPAP-induced increases in lung volume were observed, suggesting that CPAP may be useful as a therapeutic adjunct in patients who have obstructive airway disease and who require HFCWO.

Pseudomonas aeruginosa: resistance and therapeutic options at the turn of the new millennium

Pseudomonas aeruginosa is a major cause of nosocomial infections. This organism shows a remarkable capacity to resist antibiotics, either intrinsically (because of constitutive expression of beta-lactamases and efflux pumps, combined with low permeability of the outer-membrane) or following acquisition of resistance genes (e.g., genes for beta-lactamases, or enzymes inactivating aminoglycosides or modifying their target), over-expression of efflux pumps, decreased expression of porins, or mutations in quinolone targets. Worryingly, these mechanisms are often present simultaneously, thereby conferring multiresistant phenotypes. Susceptibility testing is therefore crucial in clinical practice. Empirical treatment usually involves combination therapy, selected on the basis of known local epidemiology (usually a beta-lactam plus an aminoglycoside or a fluoroquinolone). However, therapy should be simplified as soon as possible, based on susceptibility data and the patient's clinical evolution. Alternative drugs (e.g., colistin) have proven useful against multiresistant strains, but innovative therapeutic options for the future remain scarce, while attempts to develop vaccines have been unsuccessful to date. Among broad-spectrum antibiotics in development, ceftobiprole, sitafloxacin and doripenem show interesting in-vitro activity, although the first two molecules have been evaluated in clinics only against Gram-positive organisms. Doripenem has received a fast track designation from the US Food and Drug Administration for the treatment of nosocomial pneumonia. Pump inhibitors are undergoing phase I trials in cystic fibrosis patients. Therefore, selecting appropriate antibiotics and optimising their use on the basis of pharmacodynamic concepts currently remains the best way of coping with pseudomonal infections.

Breathing Pattern Adopted by Children with Cystic Fibrosis with Mild to Moderate Pulmonary Impairment during Exercise

BACKGROUND

It is well known that severe lung impairment in cystic fibrosis (CF) may compromise respiratory muscle function at rest. Even though patients with CF and severe obstructive lung disease exhibit an abnormal breathing pattern during exercise (due to expiratory flow limitation), patients with CF and normal lung function reportedly have a normal breathing pattern.

OBJECTIVES

The aim of the study was to assess the precise characteristics of the ventilatory pattern adopted during exercise by children with CF and mild to moderate lung disease.

METHODS

Nine children diagnosed as having mild to moderate CF and 9 healthy children with a similar age distribution participated in this study. Both groups performed a continuous incremental cycling protocol. Breathing and timing components were assessed during exercise.

RESULTS

Differences in the breathing pattern between children with CF and controls during exercise are illustrated in Hey plot which described a rapid shallow breathing pattern in children with CF. During exercise, children with CF showed a significantly lower mean inspiratory flow than healthy children (p < 0.001), whereas the mean expiratory flow was higher (p < 0.001). Children with CF also showed a significant increase in the end-tidal carbon dioxide pressure, which may indicate the emergence of hypercapnia.

CONCLUSIONS

During exercise, children with CF (even those not suffering from advanced disease) showed signs of rapid, shallow breathing and an increase in the ventilatory response. This was essentially due to an increase in the mean inspiratory flow, which in turn suggests an expiratory flow limitation. The children were also predisposed to hypercapnia.

Positive expiratory pressure physiotherapy for airway clearance in people with cystic fibrosis

BACKGROUND

Chest physiotherapy is widely prescribed to assist the clearance of airway secretions in people with cystic fibrosis (CF). Positive expiratory pressure (PEP) devices provide constant back pressure to the airways during expiration. This may improve clearance by building up gas behind mucus via collateral ventilation. Given the widespread use of PEP devices, there is a need to determine the evidence for their effect.

OBJECTIVES

To determine the effectiveness and acceptability of PEP devices compared to other forms of physiotherapy as a means of improving mucus clearance and other outcomes in people with CF.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising of references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. The electronic database CINAHL was also searched from 1982 to 2001. Most recent search of the Group's register: February 2006.

SELECTION CRITERIA

Randomised controlled studies in which PEP was compared with any other form of physiotherapy in people with CF.

DATA COLLECTION AND ANALYSIS

Two authors independently applied the inclusion and exclusion criteria to publications and assessed the quality of the included studies.

MAIN RESULTS

Forty studies were identified and twenty-five studies involving 507 participants met the review inclusion criteria. Most included studies had low scores on a scale of study quality. Twenty of these studies involving 300 participants were cross-over in design. Data were not published in sufficient detail in most of these studies to perform meta-analysis.Forced expiratory volume in one second (FEV1) was the most frequently measured outcome. Single interventions or series of treatments continued for up to three months demonstrated no significant difference in effect between PEP and other methods of airway clearance on FEV1. Long-term studies had equivocal or conflicting results regarding the effect on FEV1. Participant preference was reported in nine studies. In all studies with an intervention period of at least one month, measures of participant preference were in favour of PEP. The results for the remaining outcome measures were not examined or reported in sufficient detail to provide any high level evidence.

AUTHORS' CONCLUSIONS

There was no clear evidence that PEP was a more or less effective intervention overall than other forms of physiotherapy. There was limited evidence that PEP was preferred by participants compared to other techniques, but this finding is from studies of low quality.

Effect of body position on maximal expiratory pressure and flow in adults with cystic fibrosis

Maximum expiratory pressure (MEP) and peak expiratory flow rate (PEFR) are used as surrogate measures of cough and huff strength. Some body positions (particularly head-down tilt) significantly affect these measures in people with normal respiratory function and with chronic obstructive pulmonary disease. This may have implications for people with cystic fibrosis (CF), who use coughing and huffing and may use gravity-assisted drainage positions for airway clearance. Previous research concluded that body position does not affect MEP in people with CF, although head-down tilt was not examined and PEFR was not measured. This study investigated the effect of body position on MEP and PEFR in 20 adults with stable CF. Repeated measures of MEP and PEFR were performed across seven positions (standing, chair-sitting, sitting in bed with backrest vertical, sitting in bed with backrest at 45 degrees , supine, side-lying, and side-lying with head-down tilt 20 degrees ) in random order. During testing, reflux sensation and oxygenation were monitored. MEP was significantly reduced in side-lying and in the head-down tilt position. PEFRs were significantly reduced in the three-quarters sitting, supine, side-lying, and head-down positions. Oxygenation and reflux scores were worst in the head-down position. Despite statistical significance, the differences observed between positions in this stable population were of small magnitude. The effect of body position on MEP and PEFR may be more relevant during airway clearance treatments of the acutely unwell person with CF.

Gingipain-Specific IgG in the Sera of Patients With Periodontal Disease Is Necessary for Opsonophagocytosis ofPorphyromonas gingivalis

BACKGROUND

Porphyromonas gingivalis is a primary etiologic agent of generalized aggressive periodontitis (GAgP), and gingipains, a group of cysteine proteinases, are critical virulence factors expressed by this organism. GAgP patients develop specific antibodies to gingipains; however, the function of these antibodies in the clearance of P. gingivalis infection is poorly understood.

METHODS

In this study, we defined the levels of gingipain-specific antibodies in GAgP patient sera and examined the ability of gingipain-specific antibodies to facilitate opsonophagocytosis of P. gingivalis by human polymorphonuclear leukocytes (PMNs) using a fluorescent phagocytosis assay.

RESULTS

GAgP patient sera possessed elevated levels of P. gingivalis-, arginine-gingipain (Rgp)A-, RgpB-, and lysine-gingipain (Kgp)-specific IgG (Kgp > RgpA > P. gingivalis > RgpB). Adsorption of GAgP sera with P. gingivalis whole organisms, RgpA, RgpB, and Kgp conjugated to sepharose beads reduced opsonophagocytosis of P. gingivalis by PMNs.

CONCLUSIONS

Our studies demonstrate that GAgP patient sera possess elevated levels of P. gingivalis- and gingipain-specific IgG. Furthermore, we show that gingipain antibodies promote uptake of P. gingivalis by PMNs, and our data suggest that gingipain-specific antibodies may be important for the control of P. gingivalis infections.

Conventional chest physiotherapy compared to other airway clearance techniques for cystic fibrosis

BACKGROUND

Cystic fibrosis is an inherited life-limiting disorder, characterised by pulmonary infections and thick airway secretions. Chest physiotherapy has been integral to clinical management in facilitating removal of airway secretions. Conventional chest physiotherapy techniques (CCPT) have depended upon assistance during treatments, while more contemporary airway clearance techniques are self-administered, facilitating independence and flexibility.

OBJECTIVES

To compare CCPT with other airway clearance techniques in terms of their effects on respiratory function, individual preference, adherence, quality of life and other outcomes.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group trials register which comprises references identified from comprehensive electronic database searches and handsearching of relevant journals and abstract books of conference proceedings. We also searched CINAHL from 1982 to 2002 and AMED from 1985 to 2002. Date of most recent search: January 2004.

SELECTION CRITERIA

Randomised or quasi-randomised clinical trials including those with a cross-over design where CCPT was compared with other airway clearance techniques. Studies of less than seven days duration were excluded.

DATA COLLECTION AND ANALYSIS

Two reviewers allocated quality scores to relevant studies and independently extracted data. If we were unable to extract data, we invited authors to submit their data. We excluded studies from meta-analysis when data were lost or study design precluded comparison. For some continuous outcomes, we used the generic inverse variance method for meta-analysis of data from cross-over trials and data from parallel-designed trials were incorporated for comparison. We also examined efficacy of specific techniques and effects of treatment duration.

MAIN RESULTS

Seventy-eight publications were identified by the searches. Twenty-nine of these were included, representing 15 data sets with 475 participants. There was no difference between CCPT and other airway clearance techniques in terms of respiratory function measured by standard lung function tests. Studies undertaken during acute exacerbations demonstrated relatively large gains in respiratory function irrespective of airway clearance technique. Longer-term studies demonstrated smaller improvements or deterioration over time. Ten studies reported individual preferences for technique, with participants tending to favour self-administered techniques. Heterogeneity in the measurement of preference precluded these data from meta-analysis.

AUTHORS' CONCLUSIONS

This review demonstrated no advantage of CCPT over other airway clearance techniques in terms of respiratory function. There was a trend for participants to prefer self-administered airway clearance techniques. Limitations of this review included a paucity of well-designed, adequately-powered, long-term trials.

Differential immune modulatory activity of Pseudomonas aeruginosa quorum-sensing signal molecules

Pseudomonas aeruginosa releases a spectrum of well-regulated virulence factors, controlled by intercellular communication (quorum sensing) and mediated through the production of small diffusible quorum-sensing signal molecules (QSSM). We hypothesize that QSSM may in fact serve a dual purpose, also allowing bacterial colonization via their intrinsic immune-modulatory capacity. One class of signal molecule, the N-acylhomoserine lactones, has pleiotropic effects on eukaryotic cells, particularly those involved in host immunity. In the present study, we have determined the comparative effects of two chemically distinct and endobronchially detectable QSSM, N-(3-oxododecanoyl)-L-homoserine lactone (3-oxo-C12-HSL) and 2-heptyl-3-hydroxy-4 (1H)-quinolone or the Pseudomonas quinolone signal (PQS), on human leukocytes exposed to a series of stimuli designed to detect differential immunological activity in vitro. 3-Oxo-C12-HSL and PQS displayed differential effects on the release of interleukin-2 (IL-2) when human T cells were activated via the T-cell receptor and CD28 (a costimulatory molecule). 3-Oxo-C12-HSL inhibited cell proliferation and IL-2 release; PQS inhibited cell proliferation without affecting IL-2 release. Both molecules inhibited cell proliferation and the release of IL-2 following mitogen stimulation. Furthermore, in the presence of Escherichia coli lipopolysaccharide, 3-oxo-C12-HSL inhibited tumor necrosis factor alpha release from human monocytes, as reported previously (K. Tateda et al., Infect. Immun. 64:37-43, 1996), whereas PQS did not inhibit in this assay. These data highlight the presence of two differentially active immune modulatory QSSM from P. aeruginosa, which are detectable endobronchially and may be active at the host/pathogen interface during infection with P. aeruginosa, should the bronchial airway lymphoid tissues prove to be accessible to QSSM.

Improved lung function and body mass index associated with long-term use of Macrolide antibiotics

BACKGROUND

A number of studies have suggested that the non-antimicrobial actions of macrolide antibiotics may be valuable in treating patients with cystic fibrosis. The use of long-term macrolide antibiotics for the management of CF patients colonised by Pseudomonas aeruginosa and progressive pulmonary disease was introduced into our clinic in 1997. A retrospective study was undertaken to assess of the impact of this therapy.

METHODS

Twenty patients with progressive pulmonary disease (>10% fall in FEV(1) over 12 months despite optimising conventional therapy) were commenced on Azithromycin, 250 mg daily during a 21-month period. At the time of assessment they had remained on therapy for a mean of 0.9 years. Changes in lung function, weight, body mass index (BMI) and frequency of pulmonary exacerbations were assessed. A group of 20 patients with stable lung function and matched as far as possible for age and sex was identified for comparison.

RESULTS

Pulmonary function increased significantly in the Azithromycin group with FEV1% predicted increasing from a mean of 50.2-59.1% (P=0.001) while FVC% predicted increase from 64.5 to 76.1% (P=0.002). There was small but non-significant fall in lung function in the comparison group. Body mass index increased by a mean of 1.1 in the Azithromycin group but remained unchanged in the comparison group. The number of pulmonary exacerbations requiring intravenous antibiotics declined by 48.3% in macrolide treated subjects compared to the pre-treatment period (P<0.025); frequency of exacerbations in the control group was unchanged.

CONCLUSION

Long-term Azithromycin treatment in patients with progressive deterioration in lung function appears to have led to an improvement in pulmonary function, increased body mass index and decreased the frequency of pulmonary exacerbations requiring intravenous antibiotics.

A simple and reliable method for rapid production and purification of Pseudomonas aeruginosa haemolytic phospholipase C

AIMS

To design a simple method to produce active recombinant Pseudomonas aeruginosa haemolytic phospholipase C (PLC).

METHOD AND RESULTS

Pseudomonas aeruginosa PLC is a virulence factor mainly involved in inflammatory and cytotoxic responses. While ammonium sulphate purification requires large amounts of bacterial suspensions and leads to low yields, production of recombinant protein in Escherichia coli is no more successful because of frequent inclusion bodies and accumulation of inactive PLC in the periplasmic space. Using an inducible system based on the glucose-repressed inv1 promoter in the yeast Schizosaccharomyces pombe, we were able to produce up to 10 IU ml(-1) of pure toxin within 24 h.

CONCLUSIONS

This work describes the first method to easily get recombinant haemolytic PLC.

SIGNIFICANCE AND IMPACT OF THE STUDY

This method provides a powerful tool to study the mechanisms leading to its cellular toxicity.

Positive expiratory pressure physiotherapy for airway clearance in people with cystic fibrosis

BACKGROUND

Chest physiotherapy is widely prescribed to assist the clearance of airway secretions in people with cystic fibrosis (CF). Positive expiratory pressure (PEP) devices provide constant back pressure to the airways during expiration. This may improve clearance by building up gas behind mucus via collateral ventilation. Given the widespread use of PEP devices, there is a need to determine the evidence for their effect.

OBJECTIVES

To determine the effectiveness and acceptability of PEP devices compared to other forms of physiotherapy as a means of improving mucus clearance and other outcomes in people with CF.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group trials register comprising of references identified from comprehensive electronic database searches and handsearching of relevant journals and abstract books of conference proceedings. The electronic database CINAHL was also searched from 1982 to 2001. Most recent search of the Group's register: November 2003.

SELECTION CRITERIA

Randomised controlled trials in which PEP was compared with any other form of physiotherapy in people with CF.

DATA COLLECTION AND ANALYSIS

Two reviewers independently applied the inclusion and exclusion criteria to publications and assessed the quality of the included studies.

MAIN RESULTS

Thirty-three studies were identified and twenty studies involving 429 participants met review inclusion criteria. Most included studies had low scores on a scale of study quality. Sixteen of these studies involving 257 participants were cross-over in design. Data were not published in sufficient detail in these studies to perform meta-analysis.Forced expiratory volume in one second (FEV1) was the most frequently measured outcome. Single interventions or series of treatments continued for up to one month demonstrated no significant difference in effect between PEP and other methods of airway clearance on FEV1. Long-term studies had equivocal or conflicting results regarding the effect on FEV1. Patient preference was reported in nine studies. In all studies with an intervention period of at least one month, measures of patient preference were in favour of PEP. The results for the remaining outcome measures were not examined or reported in sufficient detail to provide any high level evidence.

REVIEWER'S CONCLUSIONS

There was no clear evidence that PEP was a more or less effective intervention overall than other forms of physiotherapy. There was limited evidence that PEP was preferred by participants compared to other techniques but this finding is from studies of low quality.

Changes in pulmonary mechanics with increasing disease severity in children and young adults with cystic fibrosis

As forced expiratory volume in 1 second (FEV(1)) is a major predictor of outcome in patients with cystic fibrosis (CF), we investigated the effect of FEV(1) on pulmonary mechanics in children and young adults with CF. We measured respiratory rate; tidal volume; minute ventilation; arterial blood gases; sniff esophageal pressure; dynamic lung compliance; total pulmonary resistance; intrinsic positive end expiratory pressure; and total, elastic, and resistive work of breathing in 32 patients (FEV(1) range: 12-49% predicted). We observed correlations between FEV(1) and Pa(O(2)) (r = 0.76, p < 0.0001) and Pa(CO(2)) (r = -0.70, p < 0.0001), FEV(1) and respiratory rate/tidal volume (r = -0.41, p = 0.02), FEV(1) and dynamic lung compliance (r = 0.64, p < 0.0001), and FEV(1) and total work of breathing (r = -0.52, p = 0.002) and elastic work of breathing (r = -0.60. p = 0.0003). No correlations were observed between FEV(1) and sniff esophageal pressure (p = 0.5), minute ventilation (p = 0.9), total pulmonary resistance (p = 0.3), intrinsic positive end expiratory pressure (p = 0.3), or resistive work of breathing (p = 0.1). As FEV(1) declines in children and young adults with CF, there is an increase in the elastic load and work of breathing, resulting in a rapid shallow breathing pattern, that is associated with further impairment of gas exchange.

Lung infections associated with cystic fibrosis

While originally characterized as a collection of related syndromes, cystic fibrosis (CF) is now recognized as a single disease whose diverse symptoms stem from the wide tissue distribution of the gene product that is defective in CF, the ion channel and regulator, cystic fibrosis transmembrane conductance regulator (CFTR). Defective CFTR protein impacts the function of the pancreas and alters the consistency of mucosal secretions. The latter of these effects probably plays an important role in the defective resistance of CF patients to many pathogens. As the modalities of CF research have changed over the decades from empirical histological studies to include biophysical measurements of CFTR function, the clinical management of this disease has similarly evolved to effectively address the ever-changing spectrum of CF-related infectious diseases. These factors have led to the successful management of many CF-related infections with the notable exception of chronic lung infection with the gram-negative bacterium Pseudomonas aeruginosa. The virulence of P. aeruginosa stems from multiple bacterial attributes, including antibiotic resistance, the ability to utilize quorum-sensing signals to form biofilms, the destructive potential of a multitude of its microbial toxins, and the ability to acquire a mucoid phenotype, which renders this microbe resistant to both the innate and acquired immunologic defenses of the host.

Anaesthesia in patients with cystic fibrosis

Cystic fibrosis is an autosomal-recessive disorder. In 1989 the gene mutation that causes cystic fibrosis was localized on the long arm of chromosome 7. Cystic fibrosis occurs in 1/2000 children and the majority now reach adulthood. In view of numerous clinical manifestations of cystic fibrosis, these patients frequently require surgery. Cystic fibrosis is therefore of increasing interest to anaesthesiologists. Preoperative assessment is reviewed. Pre-, intra- and postoperative care must be directed toward optimal clearance of viscous respiratory secretions, and should minimize the risk of postoperative respiratory complications. All procedures should be planned but it is very important to prepare patients for surgery, with daily physiotherapy, administration of therapeutic agents using aerosols, management of nutrition and pancreatic enzymes, and administration of vitamins and antibiotics if indicated. Currently, anaesthesia can safely be carried out in cystic fibrosis patients undergoing minor surgery, with very low incidence of postoperative respiratory complications. Finally, organ transplantation, and in particular lung transplantation, with all its attendant anaesthesiological implications, has improved the outcome for many patients with cystic fibrosis.

Effects of inhaled gentamicin prophylaxis on acquisition of Pseudomonas aeruginosa in children with cystic fibrosis: a pilot study

Inhaled antibiotics are an established treatment for chronic Pseudomonas aeruginosa (PA) infection in patients with cystic fibrosis (CF). However, inhaled antibiotics might also have prophylactic potential to delay acquisition of PA in early stages of the disease. From 1986-1999, all CF patients at this center who experienced defined risk situations for acquisition of PA (28 patients) received inhaled gentamicin (80 mg BID for those < 12 months; 120 mg BID for those > 12 months) for a minimum of 3 years. Twelve patients had repeated risk situations and continued this prophylaxis without interruption during the entire study period (group 1). In the remaining 16 patients, inhaled antibiotics were discontinued at various times for a variety of reasons (group 2). None of the patients in group 1, but 7 in group 2, became chronically infected with PA (P = 0.01). Lung function and chest X-ray scores were significantly worse in those 7 infected patients, when compared to the noninfected ones in both groups. This suggests that long-term-prophylaxis with inhaled gentamicin can effectively delay acquisition of PA and decrease disease progression in children with CF.

Rapid detection, identification, and enumeration of Pseudomonas aeruginosa in bottled water using peptide nucleic acid probes

A new chemiluminescent in situ hybridization (CISH) method that provides simultaneous detection, identification, and enumeration of Pseudomonas aeruginosa in bottled water within 1 working day has been developed. Individual micro-colonies of P. aeruginosa were detected directly on membrane filters following 5 h of growth by use of soybean peroxidase-labeled peptide nucleic acid (PNA) probes targeted to a species-specific sequence in P. aeruginosa rRNA. Within each micro-colony, reaction of the peroxidase with a chemiluminescent substrate generated light that was subsequently captured by film or with a digital camera system. Each spot of light represented one micro-colony of P. aeruginosa. Sensitivity and specificity for the identification of P. aeruginosa were 100% as determined by testing 28 P. aeruginosa strains and 17 other bacterial species that included closely related Pseudomonas species. Furthermore, the number of micro-colonies of P. aeruginosa represented by light spots correlated with counts of visible colonies following sustained growth. We conclude that PNA CISH speeds up traditional membrane filtration techniques and adds the specificity of PNA probe technology to generate fast and definitive results.

Catalase immunization from Pseudomonas aeruginosa enhances bacterial clearance in the rat lung

Pseudomonas aeruginosa is a common cause of infection in immunocompromised patients and is the major contributor to morbidity in individuals with cystic fibrosis (CF). The antibiotic resistance shown by this pathogen and morbidity in patients with chronic infection has encouraged investigations into the development of a vaccine. This study reports the purification of a 60 kDa protein, isolated from a mucoid strain of P. aeruginosa, identified by amino acid sequence analysis as the catalase protein (KatA). A rat model of acute P. aeruginosa respiratory infection was used to investigate the immunogenicity of KatA and determine the potential of mucosal immunization with KatA to protect against infection. Immunization regimens compared a single intra-Peyer's patch (IPP) immunization with an IPP primary inoculation followed by an intratracheal boost to the lungs. Mucosal immunization with KatA resulted in significant pulmonary clearance of both homologous (p<0.001) and heterologous (p<0.05) strains of P. aeruginosa. Both immunization regimens enhanced bacterial clearance, increased the rate of recruitment of phagocytes to the bronchoalveoli and induced KatA-specific antibody. However, the regimen that included a boost induced a more effective immune response that also resulted in better clearance of P. aeruginosa from the lungs. Mucosal immunization induced KatA- specific antibodies in the serum and the bronchoalveolar lavage, and KatA-specific lymphocyte proliferation in vitro in cells isolated from the mesenteric lymph nodes of immunized rats. The data presented suggests that KatA has the potential to afford a protective immune response against pulmonary infection by P. aeruginosa

Recurrent lower respiratory tract infections in a 14-year-old boy with tracheobronchomegaly (Mounier-Kuhn syndrome)

Tracheobronchomegaly (Mounier-Kuhn syndrome) is characterized by dilatation of the central airways, tracheobronchial outpouchings, and chronic tracheobronchitis. Most cases are diagnosed in adulthood. We report the clinical, radiographic, and bronchoscopic findings in a 14-year-old boy with tracheobronchomegaly, ptosis of the right eyelid, and redundant skin and mucosa of the upper lip, who presented with a 2-year history of recurrent lower respiratory tract infections. Pediatricians should be aware of the possibility that tracheobronchomegaly may cause clinical symptoms in childhood and adolescence. Pediatr Pulmonol. 2000; 29: 476-479.

Specific and rapid detection by fluorescent in situ hybridization of bacteria in clinical samples obtained from cystic fibrosis patients

We report on the rapid and specific detection of bacteria commonly isolated from clinical specimens from cystic fibrosis (CF) patients by fluorescent in situ hybridization (FISH). On the basis of comparative sequence analysis, we designed oligonucleotide probes complementary to species-specific 16S rRNA regions of these microorganisms and demonstrated the specificities of the probes by hybridization of different remotely related as well as closely related reference strains. Furthermore, in a pilot project we investigated 75 sputum samples and 10 throat swab specimens from CF patients by FISH and detected Pseudomonas aeruginosa, Burkholderia cepacia, Stenotrophomonas maltophilia, Haemophilus influenzae, and Staphylococcus aureus within these specimens. The specificity of FISH was 100% in comparison to the results of conventional microbial culture. In contrast, the sensitivity of standard laboratory cultivation was moderately higher, since the limit for microscopic detection of bacteria within sputum samples by FISH was approximately 4 x 10(5) CFU/ml of sputum (resulting in a 90% sensitivity for FISH). Moreover, we demonstrated that FISH will be useful for the rapid detection of bacteria that cause acute pulmonary exacerbations in CF patients, as demonstrated in patients with H. influenzae, S. aureus, and P. aeruginosa exacerbations. Therefore, FISH is a valuable additional method for the rapid and specific detection of bacteria in clinical samples from CF patients, in particular, patients with pulmonary exacerbations.

Chest physiotherapy compared to no chest physiotherapy for cystic fibrosis

BACKGROUND

Chest physiotherapy is widely used in patients with cystic fibrosis in order to clear mucus from the airways.

OBJECTIVES

To determine the effectiveness and acceptability of chest physiotherapy compared to no treatment or spontaneous cough alone to improve mucus clearance in cystic fibrosis.

SEARCH STRATEGY

Relevant trials are identified in the Cochrane Cystic Fibrosis and Genetic Disorders Group Specialised Register of Controlled Trials. This register was compiled by conducting computerised searches of Medline from 1966 to present and from Embase from 1974 to 1995. The register of randomised controlled trials is updated every three months. Unpublished work has been identified by searching through the abstract books of the three major cystic fibrosis conferences; the International Cystic Fibrosis Conference: the European Cystic Fibrosis Conference and the North American Cystic Fibrosis Conference. Date of the most recent search of the Group's specialised register: November 1999.

SELECTION CRITERIA

Randomised or quasi-randomised clinical trials in which a form of chest physiotherapy (airway clearance technique) were taken for consideration in patients with cystic fibrosis compared with either no physiotherapy treatment or spontaneous cough alone.

DATA COLLECTION AND ANALYSIS

There were no randomised controlled trials or cross over trials eligible for inclusion in the review.

MAIN RESULTS

There were no randomised controlled trials or cross over trials eligible for inclusion in the review.

REVIEWER'S CONCLUSIONS

Short-term crossover trials, which had to be excluded from this review, suggest that airway clearance regimens could have beneficial effects in patients with cystic fibrosis. However based on this review there is currently no robust scientific evidence to support the hypothesis that chest physiotherapy for the purpose of clearing airway secretions has a beneficial effect in patients with cystic fibrosis.

Quantitation of inflammatory responses to bacteria in young cystic fibrosis and control patients

Recent studies suggest that inflammation plays a role in the pathogenesis of lung disease in cystic fibrosis (CF). The goal of the present study was to quantitatively compare bronchoalveolar lavage fluid (BALF) inflammation and its relation to bacterial infection, between children with CF and children with other chronic respiratory problems. Differential cell counts, immunoreactive interleukin 8 (IL-8), and quantitative bacterial cultures were done in BALF from 54 CF (median age 1.8 yr) and 55 control patients (median age 1.0 yr) who underwent bronchoscopy for clinical indications. Among infected CF patients, those with Pseudomonas aeruginosa did not have more inflammation than those without P. aeruginosa. The ratio of neutrophils or of IL-8 to bacteria in BALF was significantly greater for CF patients compared with control subjects, regardless of pathogen. Calculation of linear regression for either neutrophils or IL-8, as a function of bacterial quantity, yielded positive slopes for both CF and control patients, but with significant elevations for CF. We conclude that the inflammatory response to bacterial infection is increased or prolonged in CF compared with control patients, and that this increase is not necessarily due to pathogens specific for CF (e.g., P. aeruginosa). These data may provide further rationale for anti-inflammatory therapy early in CF.

Chest physiotherapy in cystic fibrosis: improved tolerance with nasal pressure support ventilation

OBJECTIVE

Chest physiotherapy (CPT) is an integral part of the treatment of patients with cystic fibrosis (CF). CPT imposes additional respiratory work that may carry a risk of respiratory muscle fatigue. Inspiratory pressure support ventilation (PSV) is a new mode of ventilatory assistance designed to maintain a constant preset positive airway pressure during spontaneous inspiration with the goal of decreasing the patient's inspiratory work. The aim of our study was 1) to evaluate respiratory muscle fatigue and oxygen desaturation during CPT and 2) to determine whether noninvasive PSV can relieve these potential adverse effects of CPT.

METHODS

Sixteen CF patients in stable condition with a mean age of 13 +/- 4 years participated to the study. For CPT, we used the forced expiratory technique (FET), which consisted of one or more slow active expirations starting near the total lung capacity (TLC) and ending near the residual volume. After each expiration, the child was asked to perform a slow, nonmaximal, diaphragmatic inspiration. After one to four forced breathing cycles, the child was asked to cough and to expectorate. A typical 20-minute CPT session consisted of 10 to 15 FET maneuvers separated by rest periods of 10 to 20 breathing cycles each. During the study, each patient received two CPT sessions in random order on two different days, at the same time of day, with the same physiotherapist. During one of these two sessions, PSV was provided throughout the session (PSV session) via a nasal mask using the pressure support generator ARM25 designed for acute patients (TAEMA, Antony, France). The control session was performed with no nasal mask or PSV. Both CPT sessions were performed without supplemental oxygen. Lung function and maximal inspiratory pressures (PImax) and expiratory pressures (PEmax) were recorded before and after each CPT session.

RESULTS

Mean lung function parameters were comparable before the PSV and the control sessions. Baseline pulse oximetry (SpO2) was significantly correlated with the baseline vital capacity (% predicted) and forced expiratory volume in 1 second (FEV1) (% predicted). PSV was associated with an increase in tidal volume (Vt) from 0.42 +/- 0.01 liters to 1.0 +/- 0.02 liters. Respiratory rate was significantly lower during PSV. SpO2 between the FET maneuvers was significantly higher during PSV as compared with the control session. SpO2 decreases after FET were significantly larger during the control session (nadir: 91.8 +/- 0. 7%) than during the PSV session (93.8 +/- 0.6%). Maximal pressures decreased during the control session (from 71.9 +/- 6.1 to 60.9 +/- 5.3 cmH2O, and from 85.3 +/- 7.9 to 77.5 +/- 4.8 cmH2O, for PImax and PEmax, respectively) and increased during the PSV session (from 71.6 +/- 8.6 to 83.9 +/- 8.7 cmH2O, and from 80.4 +/- 7.8 to 88.0 +/- 7.4 cmH2O, for PImax and PEmax, respectively). The decrease in PEmax was significantly correlated with the severity of bronchial obstruction as evaluated based on baseline FEV1 (% predicted). Forced expiratory flows did not change after either CPT session. The amount of sputum expectorated was similar for the two CPT sessions (5.3 +/- 5.3 g vs 4.6 +/- 4.8 g after the control and PSV session, respectively; NS). Fifteen patients felt less tired after the PSV session. Ten patients reported that expectoration was easier with PSV, whereas 4 did not note any difference; 2 patients did not expectorate. Nine patients expressed a marked and 5 a small preference for PSV, and 2 patients had no preference. The physiotherapists found it easier to perform CPT with PSV in 14 patients and did not perceive any difference in 2 patients.

DISCUSSION

Our study in CF children shows that respiratory muscle performance, as evaluated based on various parameters, decreased after CPT and that significant falls in oxygen saturation occurred after the FET maneuvers despite the quiet breathing periods between each FET cycle. These unwanted effects of CPT were

The bronchoalveolar lavage fluid of cystic fibrosis lung transplant recipients demonstrates increased interleukin-8 and elastase and decreased IL-10

Cystic fibrosis (CF) patients continue to have reservoirs of Pseudomonas aeruginosa infection in their sinuses and trachea after transplantation, and studies indicate that nontransplanted CF patients have high bronchoalveolar lavage (BAL) levels of proinflammatory factors, interleukin-8 (IL-8), and elastase and decreased airway lavage levels of IL-10. The aims of our study were to measure the IL-8 and IL-10 levels and elastase activity in the BAL of lung transplant patients, with correlation to microbiologic and pathologic findings, and to identify any differences in the findings between CF and non-CF patients. Fifty serial BAL samples were collected from 38 lung transplant recipients over 8 months. The BAL supernatant fluid was cultured for bacterial, viral, and fungal organisms. Histologic tissue analysis was performed as indicated. The fluid IL-10 and IL-8 levels were measured in duplicate using ELISA techniques. Elastase activity was measured using a colorimetric assay system. The mean IL-8, IL-10, and elastase levels for the group studied were 1894 pg/ml, 394 pg/ml, and 4.2 U/ml, respectively. The CF patients had significantly higher levels of IL-8, with a mean value of 4093 pg/ml (p < 0.02), and lower IL-10, mean 217 pg/ml (n = 9). Elastase activity correlated strongly with IL-8 level (p < 0.04). Pseudomonas growth was associated with higher elastase and IL-8 concentrations (p < 0.02). There was no association between allograft rejection and the markers studied. CF transplanted patients have higher airway lavage concentrations of IL-8 and elastase correlated to the presence of Pseudomonas in the lower airway. They also have lower BAL levels of anti-inflammatory cytokine IL-10.

Lef1 transcription factor expression defines airway progenitor cell targets for in utero gene therapy of submucosal gland in cystic fibrosis

Cystic fibrosis (CF) has emerged as a paradigm disorder for assessing the utility of gene therapy in the treatment of genetic diseases. It is hypothesized that submucosal glands may play an important role in the pathophysiology of CF lung disease. However, this region poses several significant obstacles for gene therapy due to its inaccessibility from the lumen of adult proximal airways. In utero gene therapy to correct submucosal gland dysfunction in CF provides an attractive alternative strategy to target gland progenitor cells prior to gland formation and morphogenesis. Such approaches will require the use of integrating vectors capable of transducing expanding stem-cell/progenitor-cell populations in the lung. We described a newborn-ferret model of the proximal airway which was used to evaluate the phenotypic characteristics of submucosal gland progenitors and to test gene therapy strategies for targeting these cell types. To this end, we have isolated the ferret cDNA to the lymphoid enhancing factor 1 (Lef1) and have demonstrated that its mRNA expression specifically defines a subset of surface airway epithelial progenitor cells involved in the formation of primordial submucosal gland buds and subsequent gland morphogenesis. Such findings suggest that the transcriptional switch regulating activation of Lef1 expression defines the phenotype of early submucosal gland progenitor cells. In an effort to prove the principle of gene targeting to this progenitor-cell population, we evaluated the efficiency of recombinant retroviral vectors to target submucosal glands in a xenograft model system. Findings from these studies demonstrated successful gene targeting to progenitor cells of submucosal gland buds which was stable throughout subsequent gland development. In summary, these studies have provided evidence for the existence of phenotypically distinct submucosal gland progenitor cells which represent appropriate targets for gene therapy of submucosal glands in CF.

Urinary N-acetyl-beta-D-glucosaminidase activity in patients with cystic fibrosis on long-term gentamicin inhalation

OBJECTIVE

To investigate possible renal toxicity of long-term gentamicin inhalation in patients with cystic fibrosis.

METHODS

Urinary N-acetyl-beta-D-glucosaminidase (NAG) activity was measured during routine respiratory clinic visits. Outpatient records were reviewed for data on long-term gentamicin inhalation, and parents and patients were interviewed for compliance. Exclusion criteria were irregular gentamicin inhalation, urinary infection or other febrile illness, intravenous aminoglycoside treatment during the previous three months, and diabetes mellitus. Patients were assigned to three groups: group 1, current gentamicin inhalation; group 2, previous gentamicin inhalation that had been stopped at least three months ago; and group 3, never any gentamicin inhalation.

RESULTS

52 patients (34 girls, 18 boys), mean (SD) age 11.5 (5.7) years, entered the study. Patients currently on gentamicin inhalation (n = 20) were significantly younger and had higher urinary NAG activity (0.83 (0.57) U/mmol creatinine) than the 23 patients without gentamicin inhalation (0.26 (0.10) (p = 0.0001) and the nine patients with previous gentamicin inhalation (0.32 (0.15) (p = 0.0125). Twelve patients on current gentamicin inhalation had raised NAG values but all those in groups 2 and 3 had NAG values within the normal range. In patients currently on gentamicin inhalation, there was a positive correlation between urinary NAG activity and cumulative dose of nebulised gentamicin (r = 0.60, p = 0.0049).

CONCLUSIONS

Long-term gentamicin inhalation in patients with cystic fibrosis poses a risk of renal toxicity. It is not known whether further treatment might result in more severe renal damage.

Vector-specific complementation profiles of two independent primary defects in cystic fibrosis airways

Cystic fibrosis (CF) lung disease has been linked to multiple primary defects in airway epithelia caused by a dysfunctional cystic fibrosis transmembrane conductance regulator (CFTR) gene. These defects include altered Cl- and Na+ permeability as well as intracellular defects in glycoprotein processing. This apparent diversity in CFTR function is reflected in the complex patterning of CFTR expression in airway epithelia. Such complexities present challenges in the design of CF gene therapies that are capable of reconstituting the endogenous patterns of CFTR gene expression in appropriate target cells. Using a human bronchial xenograft model of the CF airway, we have evaluated the efficacy of recombinant adenoviral and cationic liposome-mediated gene transfer to correct Cl- permeability and mucous sulfation defects found in CF lung disease. Results from these studies demonstrated a clear vector-specific complementation profile for these two defects that was dependent on the type of cell transduced and the level of transgene expression. Single-dose administration of recombinant adenovirus effectively transduced high levels of CFTR transgene expression in 11 +/- 1% of epithelial cells and was capable of correcting cAMP-induced changes in Cl- permeability to 91 +/- 14% that seen in non-CF airways. However, this level of transgene expression was incapable of reversing defects in mucous sulfation due to the lack of efficient targeting to goblet cells. In contrast, cationic liposome-mediated delivery of CFTR encoding plasmids to CF airways achieved extremely low levels of transgene expression with insignificant correction (7.4 +/- 2.4%) of cAMP-induced Cl- permeability. This low level of transgene expression, however, efficiently reduced mucous sulfation to levels seen in non-CF airways. Differences in the complementation profiles of these two vectors in correcting Cl- permeability and mucous sulfation defects mirror the ability of recombinant adenovirus and liposomes to reconstitute only certain features of the endogenous distribution and abundance of CFTR protein expression. Such findings suggest that the level of intracellular CFTR required to facilitate proper glycoprotein processing may be much lower than that needed to mediate bulk Cl- flow across the airway epithelium. In summary, these data present the first example by which two different vector systems can efficiently complement independent primary defects associated with a single dysfunctional gene.

Pulmonary function in hospitalized infants and toddlers with cystic fibrosis

In older children with cystic fibrosis (CF), well-documented improvements in lung function occur during hospitalization for treatment of pulmonary exacerbations.

OBJECTIVES

(1) To test the hypothesis that improvement in lung function occurs in infants and toddlers hospitalized because of CF pulmonary exacerbations. (2) To compare changes in lung function measured during forced expiratory flow and tidal breathing.

STUDY DESIGN

Seventeen infants and toddlers with CF were evaluated at the beginning and end of hospitalization by the rapid thoracic compression technique to yield maximal flow at forced residual capacity. Tidal mechanics were measured by the esophageal balloon technique to yield lung conductance and compliance.

RESULTS

Lung function improved during the course of hospitalization. The greatest change was observed in measurements of maximal flow at functional residual capacity (.VmaxFRC), increasing from 38.5% +/- 6% predicted (mean +/- SEM) to 59.8% +/- 6% at the end (p < 0.005). Lung conductance (GL) increased from 60% +/- 6% to 78% +/- 8% (p < 0.02); lung compliance (CL) increased from 66% +/- 5% to 75% +/- 5% (p < 0.03). The degree of improvement of .VmaxFRC, GL, and CL was related to baseline measurements; those with poorer pulmonary function at baseline had the greatest degree of improvement during hospitalization.

CONCLUSION

Assessments of airflow obstruction from measurements of .VmaxFRC and GL do not necessarily demonstrate similar findings in a given infant with CF, perhaps because these two techniques measure different physiologic properties. Changes in .VmaxFRC may best reflect the predominant pathophysiology of lung disease in infants and toddlers with CF.

Osmoprotectant-dependent expression of plcH, encoding the hemolytic phospholipase C, is subject to novel catabolite repression control in Pseudomonas aeruginosa PAO1

Expression of the hemolytic phospholipase C (PlcH) of Pseudomonas aeruginosa is induced under phosphate starvation conditions or in the presence of the osmoprotectants choline and glycine betaine. Because choline and glycine betaine may serve as carbon and energy sources in addition to conferring osmoprotection to P. aeruginosa, it seemed possible that induction of plcH is subject to catabolite repression control (CRC) by tricarboxylic cycle intermediates such as succinate. Total phospholipase (PLC) activity in osmoprotectant-induced cultures of P. aeruginosa PAO1 supplemented with 20 mM succinate was three- to fourfold lower than the levels in cultures supplemented with the non-catabolite-repressive substrate lactate. Analyses of osmoprotectant-dependent plcH expression in a derivative of strain PAO1 containing a plcH::lacZ operon fusion showed that (i) succinate prevented induction of plcH expression by osmoprotectants; and (ii) addition of succinate reduced or shut down further expression of plcH in osmoprotectant-induced bacteria, while cultures supplemented with lactate had little or no change in plcH expression. RNase protection analysis confirmed that repression of plcH occurs at the transcriptional level. However, a P. aeruginosa mutant decoupled in CRC exhibited a phenotype similar to that of the wild-type strain (PAO1) with respect to succinate-dependent repression of plcH expression. Osmoprotectant-induced total PLC activities, levels of expression of plcH measured with the same plcH::lacZ fusion, and levels of plcH transcription in a CRC-deficient strain reflected those seen in strain PAO1. This indicates that CRC of plcH functions by a distinct mechanism which differs from that regulating the glucose or mannitol catabolic pathway. A strain carrying a mutation in vfr, which encodes the Escherichia coli Crp homolog in P. aeruginosa, still exhibited a wild-type phenotype with respect to osmoprotectant-dependent expression and CRC of plcH. These data indicate that there is a novel CRC system that regulates the expression of plcH in P. aeruginosa.

Distribution of disease in cystic fibrosis: correlation with pulmonary function

STUDY OBJECTIVE

We hypothesized that the radiographic distribution of disease is important in determining pulmonary function, with the lower lung zones of more importance than the upper lung zones. To test this hypothesis, we retrospectively studied patients with cystic fibrosis, a disease with a known proclivity for the upper lung zones.

SUBJECTS AND METHODS

Two hundred seventy-six chest radiographs obtained at 2- to 3-year intervals from 51 patients were scored by two radiologists using a 100-point visual severity scale. The distribution of disease was assessed by dividing the lungs into four equal horizontal zones and scoring each zone for the severity of disease. There were 146 concurrent chest radiographs and pulmonary function tests from which multiple linear regression was used to correlate these zonal scores with FEV1/FVC percent predicted.

RESULTS

There was excellent interobserver agreement, intraclass correlation coefficients >0.7. The distribution of disease became predominant in the upper lung zones as the patients aged. Although the median score in the upper lung zones was nearly twice that of the lower lung zones, the lower lung zones were nearly three times (partial F ratio; 6.9 lower zone score vs 2.4 upper lung zone score) as important in determining pulmonary function.

CONCLUSION

The regional distribution of disease is important in determining pulmonary function. Sparing of the lower lung zones is important in preserving pulmonary function.

Opportunities for the use of aerosolized alpha 1-antitrypsin for the treatment of cystic fibrosis

Cystic fibrosis (CF), the most common lethal genetic disease affecting the white population, owes its morbidity and mortality primarily to the devastating effects of chronic inflammation and infection within the pulmonary airways. It has become increasingly recognized that the host's response to Pseudomonas species and Staphylococcus aureus infection plays a paramount role in CF lung destruction and eventual development of respiratory insufficiency. A massive pulmonary influx of neutrophils, and accompanying excessive levels of neutrophil elastase (NE), can be detected in the bronchoalveolar fluid of even very young children with CF. The excess of NE adversely affects the CF airways by enhancing mucus secretion, directly injuring airway tissues, exacerbating the inflammatory process by attracting more neutrophils, and derailing opsonization and elimination of bacterial pathogens, particularly Pseudomonas aeruginosa. Neutralization of excess NE by delivering supplemental alpha 1-antitrypsin to the airways via aerosolization represents an exciting new potential therapy for CF lung disease.