Effect of antibiotic treatment on inflammatory markers and lung function in cystic fibrosis patients with Pseudomonas cepacia

RNA sequencing data from neutrophils of patients with cystic fibrosis reveals potential for developing biomarkers for pulmonary exacerbations

BACKGROUND

There is no effective way to predict cystic fibrosis (CF) pulmonary exacerbations (CFPE) before they become symptomatic or to assess satisfactory treatment responses.

METHODS

RNA sequencing of peripheral blood neutrophils from CF patients before and after therapy for CFPE was used to create transcriptome profiles. Transcripts with an average transcripts per million (TPM) level > 1.0 and a false discovery rate (FDR) < 0.05 were used in a cosine K-nearest neighbor (KNN) model. Real time PCR was used to corroborate RNA sequencing expression differences in both neutrophils and whole blood samples from an independent cohort of CF patients. Furthermore, sandwich ELISA was conducted to assess plasma levels of MRP8/14 complexes in CF patients before and after therapy.

RESULTS

We found differential expression of 136 transcripts and 83 isoforms when we compared neutrophils from CF patients before and after therapy (>1.5 fold change, FDR-adjusted P < 0.05). The model was able to successfully separate CF flare samples from those taken from the same patients in convalescence with an accuracy of 0.75 in both the training and testing cohorts. Six differently expressed genes were confirmed by real time PCR using both isolated neutrophils and whole blood from an independent cohort of CF patients before and after therapy, even though levels of myeloid related protein MRP8/14 dimers in plasma of CF patients were essentially unchanged by therapy.

CONCLUSIONS

Our findings demonstrate the potential of machine learning approaches for classifying disease states and thus developing sensitive biomarkers that can be used to monitor pulmonary disease activity in CF.

Clinical utility of C-reactive protein to predict treatment response during cystic fibrosis pulmonary exacerbations

Rationale

C-reactive protein (CRP) is a systemic marker of inflammation that correlates with disease status in cystic fibrosis (CF). The clinical utility of CRP measurement to guide pulmonary exacerbation (PEx) treatment decisions remains uncertain.

Objectives

To determine whether monitoring CRP during PEx treatment can be used to predict treatment response. We hypothesized that early changes in CRP can be used to predict treatment response.

Methods

We reviewed all PEx events requiring hospitalization for intravenous (IV) antibiotics over 2 years at our institution. 83 PEx events met our eligibility criteria. CRP levels from admission to day 5 were evaluated to predict treatment non-response, using a modified version of a prior published composite definition. CRP was also evaluated to predict time until next exacerbation (TUNE).

Measurements and main results

53% of 83 PEx events were classified as treatment non-response. Paradoxically, 24% of PEx events were characterized by a ≥ 50% increase in CRP levels within the first five days of treatment. Absolute change in CRP from admission to day 5 was not associated with treatment non-response (p = 0.58). Adjusted for FEV₁% predicted, admission log₁₀ CRP was associated with treatment non-response (OR: 2.39; 95% CI: 1.14 to 5.91; p = 0.03) and shorter TUNE (HR: 1.60; 95% CI: 1.13 to 2.27; p = 0.008). The area under the receiver operating characteristics (ROC) curve of admission CRP to predict treatment non-response was 0.72 (95% CI 0.61–0.83; p<0.001). 23% of PEx events were characterized by an admission CRP of > 75 mg/L with a specificity of 90% for treatment non-response.

Conclusions

Admission CRP predicts treatment non-response and time until next exacerbation. A very elevated admission CRP (>75mg/L) is highly specific for treatment non-response and might be used to target high-risk patients for future interventional studies aimed at improving exacerbation outcomes.

Role of C-reactive protein as a biomarker for prediction of the severity of pulmonary exacerbations in patients with cystic fibrosis

Background

Pulmonary exacerbation is one of the main risk factors for death in patients with cystic fibrosis. Several biomarkers have proven useful in the diagnosis and treatment of pulmonary exacerbations, although none has been associated with severity. The objective of the present study was to investigate whether C-reactive protein (CRP) level was associated with the severity of pulmonary exacerbation requiring admission to hospital in patients with cystic fibrosis.

Methods

We designed a severity index for exacerbations based on 4 clinical parameters and determined whether there was an association between CRP levels and severity of the exacerbation. We also investigated the association between CRP and baseline functional and clinical variables.

Results

Twenty-seven patients with cystic fibrosis required 62 admissions to hospital. CRP levels were not significantly associated with the severity index, although they were associated with specific patient characteristics: colonization by Pseudomonas aeruginosa, allergic bronchopulmonary aspergillosis, treatment with oral corticosteroids, and number of severe exacerbations treated with intravenous antibiotics during the previous year.

Conclusions

CRP level is not associated with the severity of pulmonary exacerbations, but it is associated with specific clinical characteristics. This simple scoring system (severity index) could prove very useful for evaluating the severity of exacerbations.

Systematic review of blood biomarkers in cystic fibrosis pulmonary exacerbations

BACKGROUND

Biomarkers reflective of disease activity in cystic fibrosis (CF) have the potential to improve patient care, particularly during CF pulmonary exacerbations (CFPEs). Although blood-based biomarkers have been studied in CFPE for nearly 3 decades, none have been integrated into routine clinical practice. To facilitate progress in this area, we performed a systematic review evaluating blood-based biomarkers during CFPE.

METHODS

MEDLINE, EMBASE, and CENTRAL were searched to identify relevant studies published from January 1995 to August 2012. We included all full-text studies examining systemic (blood-based) biomarkers to aid in the diagnosis of CFPE, predict outcomes of CFPE, and/or monitor the response to CFPE treatment.

RESULTS

Seventy-eight unique blood-based biomarkers have been studied to date, mainly inflammatory cytokines, acute phase reactants, and markers of oxidative stress. C-reactive protein (CRP) consistently correlated with disease activity, with a statistically significant increase from stable to exacerbation state in five of six studies, and changes in response to CFPE treatment, with a statistically significant decrease from the beginning to the end of CFPE treatment in 18 of 20 studies. Other promising biomarkers of CFPE disease activity include neutrophil elastase antiproteinase complex, IL-6, myeloperoxidase (MPO), lactoferrin, and calprotectin.

CONCLUSIONS

Although there are several blood-based biomarkers with evidence for application within the CFPE setting, CRP has been the most widely studied biomarker demonstrating the potential for clinical usefulness. Further validation studies and clinical trials are required to determine whether blood-based biomarkers can be used to ultimately improve health outcomes in the setting of a CFPE.

Antibiotic Treatment of Multidrug-Resistant Organisms in Cystic Fibrosis

Respiratory tract infection with eventual respiratory failure is the major cause of morbidity and mortality in cystic fibrosis (CF). Infective exacerbations need to be treated promptly and effectively to minimize potentially accelerated attrition of lung function. The choice of antibiotic depends on in vitro sensitivity patterns. However, physicians treating patients with CF are increasingly faced with infection with multidrug-resistant isolates of Pseudomonas aeruginosa. In addition, innately resistant organisms such as Burkholderia cepacia complex, Stenotrophomonas maltophilia and Achromobacter (Alcaligenes) xylosoxidans are becoming more prevalent. Infection with methicillin-resistant Staphylococcus aureus (MRSA) is also a problem. These changing patterns probably result from greater patient longevity and increased antibiotic use for acute exacerbations and maintenance care. Multidrug-resistant P. aeruginosa infection may be treated successfully by using two antibiotics with different mechanisms of action. In practice antibiotic choices have usually been made on a best-guess basis, but recent research suggests that more directed therapy can be achieved through the application of multiple-combination bactericidal testing (MCBT). Aerosol delivery of tobramycin for inhalation solution achieves high endobronchial concentrations that may overcome bacterial resistance as defined by standard laboratory protocols. Resistance to colistin is rare and this antibiotic should be seen as a valuable second-line drug to be reserved for multidrug-resistant P. aeruginosa. The efficacy of new antibiotic groups such as the macrolides needs to be evaluated.CF units should adopt strict segregation policies to interrupt person-to-person spread of B. cepacia complex. Treatment of panresistant strains is difficult and often arbitrary. Combination antibiotic therapy is recommended, usually tobramycin and high-dose meropenem and/or ceftazidime, but the choice of treatment regimen should always be guided by the clinical response.The clinical significance of S. maltophilia, A. xylosoxidans and MRSA infection in CF lung disease remains uncertain. If patients show clinical decline and are chronically colonized/infected with either of the former two pathogens, treatment is recommended but efficacy data are lacking. There are defined microbiological reasons for attempting eradication of MRSA but there are no proven deleterious effects of this infection on lung function in patients with CF. Various treatment protocols exist but none has been subject to a randomized, controlled trial. Multidrug-resistant microorganisms are an important and growing issue in the care of patients with CF. Each patient infected with such strains should be assessed individually and antibiotic treatment planned according to in vitro sensitivity, patient drug tolerance, and results of in vitro studies which may direct the physician to antibiotic combinations most likely to succeed.

Duration of effect of intravenous antibiotics on spirometry and sputum cytokines in children with cystic fibrosis

Intravenous (IV) antibiotics are a mainstay of therapy in children with cystic fibrosis. It is unclear, however, over what period associated improvements in pulmonary function are maintained, and to what extent the underlying inflammatory process is impeded in children admitted for a course of IV antibiotics. This was a prospective, interventional study of 14 children (median age, 14 years; interquartile range, 10-14) with cystic fibrosis who were regular sputum producers and who required admission for a 2-week course of IV antibiotics. Children performed spirometry and provided a sputum sample prior to starting IV antibiotics and then weekly for 6 weeks, the first 2 weeks of which IV antibiotics were given. Sputum IL-8, TNF-alpha, IL-6, IL-10, MIP1-alpha, and elastase were measured. Seven children were asked to repeat the protocol in a subsequent exacerbation to assess similarities in response to therapy. Significant improvements were seen in forced expired volume in 1 sec (FEV(1)) in association with IV antibiotics (27% relative improvement in predicted from baseline to end of week 1, median FEV(1) 41.3% increasing to 52.2%), but this continued only 1 week following cessation of antibiotics. Although IL-8 demonstrated a trend for reduction in association with antibiotics, no significant profile was demonstrated for any of the cytokines assessed. IL-10 was detectable in 64% of samples (all <100 pg/ml). In children with two episodes assessed, although there was a close correlation of FEV(1) and FVC between exacerbations (before antibiotics), no significant correlation was seen for IL-8, TNF-alpha, or IL-10 measured in both sets of samples at any sample point (indeed, a discordant response was seen between sample points in the two exacerbations). Although FEV(1) temporarily improves in response to admission for IV antibiotics, no such response is seen in sputum cytokine values. In addition, assessment of cytokines in subsequent exacerbations does not show a similar pattern of response to treatment.

Total energy expenditure in stable patients with cystic fibrosis

BACKGROUND AND AIMS

Undernutrition is a common problem in patients with cystic fibrosis and is associated with a poor prognosis. The two aims of this study were to assess and compare the two main field techniques in the measurement of total energy expenditure and, secondly, to assess total energy expenditure in stable patients and compare with healthy controls.

METHODS

Resting energy expenditure was measured using indirect calorimetry and total energy expenditure was measured using 24-h heart rate (HR) methodology and doubly isotopically labelled water.

RESULTS

Seventeen patients, mean age 23 years and FEV(1)52% predicted and thirteen controls were recruited. Resting energy expenditure was higher in patients 0.24 (0.03) MJ/kg Fat-Free Mass (FFM) compared to controls 0.22 (0.02) MJ/kg FFM, P=0.02. Twenty-four hour heart rate underestimated total energy expenditure, 9.49 (1.85) MJ/day in patients compared to 11.69 (2.79) MJ/day using doubly labelled water. There was no difference in total energy expenditure in patients and controls using both methods, 11.69 (2.79) MJ/day compared to 11.38 (2.71) MJ/day using doubly isotopically labelled water.

CONCLUSIONS

In clinically stable young adult patients with moderately severe respiratory disease total energy expenditure is comparable to that an a control population despite in increase in resting energy expenditure and both 24-h HR and doubly isotopically labelled water are suitable for use in patients with cystic fibrosis.

Neutrophil elastase/alpha 1-proteinase inhibitor complex levels decrease in plasma of cystic fibrosis patients during long-term oral beta-carotene supplementation

Lung inflammation in cystic fibrosis (CF) is associated with an increased release from activated neutrophils of oxidants and proteinases. Free radical generation is not efficiently neutralized, and the major anti-proteinase, alpha 1-proteinase inhibitor (alpha 1-PI) is thought to be oxidatively inactivated. We hypothesized that enhanced antioxidant protection could represent an additional long-term strategy to attentuate the host inflammatory response. The effect on plasma neutrophil elastase/alpha 1-PI (NE/alpha 1-PI) complex levels (as a marker of lung inflammation) and plasma malondialdehyde concentrations (as a marker of lipid peroxidation) of additional oral beta-carotene supplementation was studied in 33 CF patients who had already received long-term vitamin E supplementation. In the presence of a more than 10-fold increase in plasma beta-carotene concentrations (mean +/- SEM) (0.09 +/- 0.01 to 1.07 +/- 0.19 mumol/L; p < 0.0001), a small increase in plasma alpha-tocopherol concentrations (23.8 +/- 1.31 to 28.4 +/- 1.81 mumol/L; p = 0.02), and a more than 50% decrease in plasma malondialdehyde concentrations (1.00 +/- 0.07 to 0.46 +/- 0.03 mumol/L; p < 0.0001), plasma NE/alpha 1-PI complex levels decreased from 102.2 +/- 16.0 to 83.0 +/- 10.4 micrograms/L; (p = 0.02). Plasma retinol concentrations increased (1.05 +/- 0.06 to 1.23 +/- 0.07 mumol/L; p = 0.0001) due to conversion of beta-carotene to retinol, which could have contributed to the decrease in NE/alpha 1-PI complex levels. Based on these results, we speculate that efficient antioxidant supplementation could attenuate lung inflammation in CF.

Is Burkholderia (Pseudomonas) cepacia disseminated from cystic fibrosis patients during physiotherapy?

Burkholderia cepacia is well recognized as a potential respiratory pathogen in cystic fibrosis (CF) patients and there is increasing concern about nosocomial acquisition. Environmental contamination with B. cepacia before, during and after physiotherapy was studied in eight adult CF patients. Air was sampled using a surface air sampler, and horizontal surfaces and pillows were sampled with moistened swabs and contact plates, respectively. Thirty-nine (40%) of 97 air samples were positive and counts ranged from 1-63 cfu/m3. Forty-four percent of samples taken after physiotherapy were positive. B. cepacia was not recovered from sinks or horizontal surfaces but the pillows of three patients were positive. B. cepacia is disseminated into the immediate environment by adult CF patients receiving physiotherapy. The potential risk of person-to-person transmission during hospitalization justifies the recommendation that B. cepacia-positive patients should be segregated from other CF patients.

Once-daily tobramycin therapy in lower respiratory tract infections

In a multicenter Italian study of 104 adult patients with severe bacterial lower respiratory tract infections, the safety and efficacy of a regimen of high dose, once-daily tobramycin alone or in combination with antipseudomonas betalactams was assessed. The overall bacteriological response was an elimination of the original pathogen in 70% of the patients while the overall clinical response mirrored the bacteriological results with a successful clinical outcome in 78% of patients. Adverse experiences were, in general, few and mild without oto- or nephrotoxicity. The once-daily, high dose regimen of tobramycin proved to be a safe and efficacious therapy for severe lower respiratory tract infections in adult patients.