Lower airway inflammation in infants and young children with cystic fibrosis

Exhaled breath condensate adenosine tracks lung function changes in cystic fibrosis

Measurement of exhaled breath condensate (EBC) biomarkers offers a noninvasive means to assess airway disease, but the ability of EBC biomarkers to track longitudinal changes in disease severity remains unproven. EBC was collected from pediatric patients with cystic fibrosis (CF) during regular clinic visits over 1 yr. EBC biomarkers urea, adenosine (Ado), and phenylalanine (Phe) were measured by mass spectrometry, and biomarker ratios were used to control for variable dilution of airway secretions. EBC biomarker ratios were assessed relative to lung function in longitudinal, multivariate models and compared with sputum inflammatory markers and quality of life assessment (CFQ-R). EBC was successfully analyzed from 51 subjects during 184 visits (3.6 ± 0.9 visits per subject). EBC Ado/urea ratio was reproducible in duplicate samples (r = 0.62, P < 0.01, n = 20) and correlated with sputum neutrophil elastase (β = 2.5, P < 0.05). EBC Ado/urea correlated with the percentage predicted of forced expiratory volume in 1 s in longitudinal, multivariate models (β = -2.9, P < 0.01); EBC Ado/Phe performed similarly (β = -2.1, P < 0.05). In contrast, IL-8 and elastase measured in spontaneously expectorated sputum (n = 57 samples from 25 subjects) and the CFQ-R respiratory scale (n = 90 tests from 47 subjects) were not significantly correlated with lung function. EBC was readily collected in a clinic setting from a wide range of subjects. EBC Ado tracked longitudinal changes in lung function in CF, with results similar to or better than established measures.

Early lung disease in cystic fibrosis

Lung disease in patients with cystic fibrosis is characterised by inflammation and recurrent and chronic infections leading to progressive loss in pulmonary function and respiratory failure. Early management of disease results in substantially improved pulmonary function at first testing (at roughly 6 years of age), but the annual decline in pulmonary function tests in older patients has remained unchanged showing how important the early years are in the disease process. Treatment regimens for patients with cystic fibrosis have changed from predominantly symptomatic treatment to preventive or causal (ie, treatments that address the underlying mechanisms of disease) therapeutic interventions. The infant and preschool age (2-5 years) could represent a unique period of opportunity to postpone or even prevent the onset of cystic fibrosis lung disease. We summarise the current knowledge and the methods used to characterise and quantify early lung disease. We discuss treatment strategies including new drugs that are being developed and their potential role in the treatment of early lung disease in patients with cystic fibrosis.

Macrophage-mediated inflammation and disease: a focus on the lung

The lung is exposed to a vast array of inhaled antigens, particulate matter, and pollution. Cells present in the airways must therefore be maintained in a generally suppressive phenotype so that excessive responses to nonserious irritants do not occur; these result in bystander damage to lung architecture, influx of immune cells to the airways, and consequent impairment of gas exchange. To this end, the resident cells of the lung, which are predominantly macrophages, are kept in a dampened state. However, on occasion the suppression fails and these macrophages overreact to antigenic challenge, resulting in release of inflammatory mediators, induction of death of lung epithelial cells, deposition of extracellular matrix, and development of immunopathology. In this paper, we discuss the mechanisms behind this macrophage-mediated pathology, in the context of a number of inflammatory pulmonary disorders.

Prevention of chronic Pseudomonas aeruginosa infection in people with cystic fibrosis

Cystic fibrosis is the most common genetically inherited disease in the Caucasian population, with approximately 30,000 patients in the USA and more than 50,000 patients worldwide. The primary defect in the cystic fibrosis transmembrane regulator gene affects the production and/or function of the cystic fibrosis transmembrane regulator protein. Depending on the severity of the genetic defect, patients may have minimal disease expression (e.g., male infertility) or multisystem involvement, including recurrent respiratory infection progressing to respiratory failure, hepatobiliary disease, exocrine pancreatic insufficiency, diabetes mellitus and gastrointestinal tract motility problems. Pseudomonas aeruginosa is commonly isolated from the lower respiratory tract in early childhood. Chronic infection is associated with increased morbidity and mortality. P. aeruginosa infection may be acquired from the environment or by person-to-person contact. Clinicians should adopt a proactive protocol to prevent chronic infection. The cornerstones of such a policy are microbiological surveillance, infection control and antibiotic-based eradication regimens.

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.

Exhaled nitric oxide

Nitric oxide (NO) is now considered an important biomarker for respiratory disease. Studies have confirmed that the fractional concentration of exhaled nitric oxide (FENO) is elevated in the airways of patients who have asthma in comparison with controls. The level of FENO correlates well with the presence and level of inflammation, and decreases with glucocorticoid treatment. NO has potential to be used not only as a diagnostic aid but also as a management tool for assessing severity, monitoring response to therapy, and gaining control of asthma symptoms. This article reviews the biology of NO and its role in respiratory disease.

Inflammatory responses to individual microorganisms in the lungs of children with cystic fibrosis

BACKGROUND

We hypothesized that the inflammatory response in the lungs of children with cystic fibrosis (CF) would vary with the type of infecting organism, being greatest with Pseudomonas aeruginosa and Staphylococcus aureus.

METHODS

A microbiological surveillance program based on annual bronchoalveolar lavage (BAL) collected fluid for culture and assessment of inflammation was conducted. Primary analyses compared inflammation in samples that grew a single organism with uninfected samples in cross-sectional and longitudinal analyses.

RESULTS

Results were available for 653 samples from 215 children with CF aged 24 days to 7 years. A single agent was associated with pulmonary infection (≥10(5) cfu/mL) in 67 BAL samples, with P. aeruginosa (n = 25), S. aureus (n = 17), and Aspergillus species (n = 19) being the most common. These microorganisms were associated with increased levels of inflammation, with P. aeruginosa being the most proinflammatory. Mixed oral flora (MOF) alone was isolated from 165 BAL samples from 112 patients, with 97 of these samples having a bacterial density ≥10(5) cfu/mL, and was associated with increased pulmonary inflammation (P < .001). For patients with current, but not past, infections there was an association with a greater inflammatory response, compared with those who were never infected (P < .05). However, previous infection with S. aureus was associated with a greater inflammatory response in subsequent BAL.

CONCLUSIONS

Pulmonary infection with P. aeruginosa, S. aureus, or Aspergillus species and growth of MOF was associated with significant inflammatory responses in young children with CF. Our data support the use of specific surveillance and eradication programs for these organisms. The inflammatory response to MOF requires additional investigation.

Future directions in early cystic fibrosis lung disease research: an NHLBI workshop report

Since the 1989 discovery that mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause cystic fibrosis (CF), there has been substantial progress toward understanding the molecular basis for CF lung disease, leading to the discovery and development of new therapeutic approaches. However, the earliest impact of the loss of CFTR function on airway physiology and structure and its relationship to initial infection and inflammation are poorly understood. Universal newborn screening for CF in the United States represents an unprecedented opportunity for investigating CF clinical manifestations very early in life. Recently developed animal models with pulmonary phenotypic manifestations also provide a window into the early consequences of this genetic disorder. For these reasons, the National Heart, Lung, and Blood Institute (NHLBI) convened a working group of extramural experts, entitled "Future Research Directions in Early CF Lung Disease" on September 21-22, 2010, to identify future research directions of great promise in CF. The priority areas identified included (1) exploring pathogenic mechanisms of early CF lung disease; (2) leveraging newborn screening to elucidate the natural history of early lung disease; (3) developing a spectrum of biomarkers of early lung disease that reflects CF pathophysiology, clinical outcome, and response to treatment; (4) exploring the role of genetics/genomics (e.g., modifier genes, gene-environmental interactions, and epigenetics) in early CF pathogenesis; (5) defining early microbiological events in CF lung disease; and (6) elucidating the initial airway inflammatory, remodeling, and repair mechanisms in CF lung disease.

Initial interrogation, confirmation and fine mapping of modifying genes: STAT3, IL1B and IFNGR1 determine cystic fibrosis disease manifestation

We have used a stepwise approach consisting of initial interrogation, confirmation and fine mapping to analyze STAT3, IL1B and IFNGR1 as modifiers of cystic fibrosis disease building upon the data and sample collection of the European Cystic Fibrosis Twin and Sibling Study. We have observed direct correlation between the length of the intronic microsatellite STAT3Sat to STAT3 expression levels among F508del-CFTR homozygous patients (P=0.0075), and an association of longer STAT3Sat-alleles with the presence of CFTR-mediated residual chloride secretion (P=0.0031), measured as the manifestation of the CF basic defect in intestinal tissue. Both, family-based analysis by TDT and case-reference comparison identified consistently the same intragenic IL1B haplotype as a risk variant (P(raw)=0.055 for TDT, P(raw)<0.3 for case-reference comparison). Using haplotype-guided hierarchical fine mapping, we have identified two single nucleotide exchanges for which concordant and discordant sibling pairs differ at a 7 kb-spanning core haplotype in IFNGR1 (P(raw)=0.0113). Taken together, our findings imply that immunorelevant pathways and ion secretion, dominated by CFTR in intestinal and respiratory epithelium, merge at the level of the epithelial cell to integrate the signaling of cytokines due to innate and acquired immune defense.

Macrolides: from in vitro anti-inflammatory and immunomodulatory properties to clinical practice in respiratory diseases

BACKGROUND

Macrolides have long been recognised to exert immunomodulary and anti-inflammatory actions. They are able to suppress the "cytokine storm" of inflammation and to confer an additional clinical benefit through their immunomodulatory properties.

METHODS

A search of electronic journal articles was performed using combinations of the following keywords: macrolides, COPD, asthma, bronchitis, bronchiolitis obliterans, cystic fibrosis, immunomodulation, anti-inflammatory effect, diabetes, side effects and systemic diseases.

RESULTS

Macrolide effects are time- and dose-dependent, and the mechanisms underlying these effects remain incompletely understood. Both in vitro and in vivo studies have provided ample evidence of their immunomodulary and anti-inflammatory actions. Importantly, this class of antibiotics is efficacious with respect to controlling exacerbations of underlying respiratory problems, such as cystic fibrosis, asthma, bronchiectasis, panbrochiolitis and cryptogenic organising pneumonia. Macrolides have also been reported to reduce airway hyper-responsiveness and improve pulmonary function.

CONCLUSION

This review provides an overview on the properties of macrolides (erythromycin, clarithromycin, roxithromycin, azithromycin), their efficacy in various respiratory diseases and their adverse effects.

Autophagy stimulation by rapamycin suppresses lung inflammation and infection by Burkholderia cenocepacia in a model of cystic fibrosis

Cystic fibrosis (CF) is the most common inherited lethal disease of Caucasians which results in multi organ dysfunction. However, 85% of the deaths are due to pulmonary infections. Infection by Burkholderia cenocepacia (B. cepacia) is a particularly lethal threat to CF patients because it causes severe and persistent lung inflammation and is resistant to nearly all available antibiotics. In CFTR ΔF508 mouse macrophages, B. cepacia persists in vacuoles that do not fuse with the lysosomes and mediates increased production of IL-1β. It is believed that intracellular bacterial survival contributes to the persistence of the bacterium. Here we show for the first time that in wild-type macrophages but not in ΔF508 macrophages, many B. cepacia reside in autophagosomes that fuse with lysosomes at later stages of infection. Accordingly, association and intracellular survival of B. cepacia are higher in CFTR-ΔF508 (ΔF508) macrophages than in WT macrophages. An autophagosome is a compartment that engulfs non-functional organelles and parts of the cytoplasm then delivers them to the lysosome for degradation to produce nutrients during periods of starvation or stress. Furthermore, we show that B. cepacia downregulates autophagy genes in WT and ΔF508 macrophages. However, autophagy dysfunction is more pronounced in ΔF508 macrophages since they already have compromised autophagy activity. We demonstrate that the autophagy-stimulating agent, rapamycin markedly decreases B. cepacia infection in vitro by enhancing the clearance of B. cepacia via induced autophagy. In vivo, Rapamycin decreases bacterial burden in the lungs of CF mice and drastically reduces signs of lung inflammation. Together, our studies reveal that if efficiently activated, autophagy can control B. cepacia infection and ameliorate the associated inflammation. Therefore, autophagy is a novel target for new drug development for CF patients to control B. cepacia infection and accompanying inflammation.

Review of recombinant human deoxyribonuclease (rhDNase) in the management of patients with cystic fibrosis

The most important problem in cystic fibrosis (CF) lung disease is chronic airway inflammation and infection, which starts early in life. To prevent severe lung damage, it is important to mobilize as much sputum as possible from the lung on a daily basis. RhDNase is an enzyme that breaks down DNA strands in airway secretions, hydrolyzes the DNA present in sputum/mucus of CF patients, reducing viscosity in the lungs and promoting secretion clearance. Several well performed trials have proven its efficacy in young CF patients with mild disease as well as in older patients with more advanced lung disease. Daily inhalation of this agent slows down lung function decline and decreases the frequency of respiratory exacerbations. The drug is well tolerated by most patients independent of the severity of lung disease.

Reduced surface toll-like receptor-4 expression and absent interferon-γ-inducible protein-10 induction in cystic fibrosis airway cells

ABSTRACT As part of the innate and adaptive immune system, airway epithelial cells secrete proinflammatory cytokines after activation of Toll-like receptors (TLRs) by pathogens. Nevertheless, cystic fibrosis (CF) airways are chronically infected with Pseudomonas aeruginosa, suggesting a modified immune response in CF. The authors have shown that in CF bronchial epithelial cells, a reduced surface expression of TLR-4 causes a diminished interleukin (IL)-8 and IL-6 response upon lipopolysaccharide (LPS) stimulation. However, there is no information regarding activation of the MyD88 (myeloid differentiation primary response gene 88)-independent TLR-4 signaling pathway by LPS, which results in the activation of adaptive immune responses by secretion of the T cell-recruiting chemokine interferon-γ-inducible protein (IP)-10. Therefore, the authors investigated the induction of IP-10 in CF bronchial epithelial cell line CFBE41o- and its CFTR-corrected isotype under well-differentiating conditions. TLR-4 surface expression was significantly reduced in CFBE41o- by a factor of 2, compared to the CFTR-corrected cells. In CFTR-corrected cells, stimulation with LPS increased IP-10 secretion. Incubating cells with siRNA directed against TLR-4 inhibited the LPS stimulated increase of IP-10 in CFTR-corrected cells. The reduced TLR-4 surface expression in CF cells causes the loss of induction of IP-10 by LPS. This could compromise adaptive immune responses in CF due to a reduced T-cell recruitment.

Targeting airway inflammation in cystic fibrosis in children: past, present, and future

Inflammation is a major component of the vicious cycle characterizing cystic fibrosis (CF) pulmonary disease. If untreated, this inflammatory process irreversibly damages the airways, leading to bronchiectasis and ultimately respiratory failure. Anti-inflammatory drugs for CF lung disease appear to have beneficial effects on disease progression. These agents include oral corticosteroids and ibuprofen, as well as azithromycin, which, in addition to its antimicrobial effects, also possess anti-inflammatory properties. Inhaled corticosteroids, antioxidants, nutritional supplements, and protease inhibitors have a limited impact on the disease. Adverse effects limit therapy with oral corticosteroids and ibuprofen. Azithromycin appears to be safe and effective, and is thus the most promising anti-inflammatory therapy available for patients with CF. Pharmacologic therapy with anti-inflammatory agents should be started early in the disease course, before extensive irreversible lung damage has occurred. To optimize anti-inflammatory therapy, it is necessary to understand the mechanism of action of these agents in the CF lung, to determine which of these agents would provide the most benefit to patients with CF, and to determine which therapies should be initiated at what age or stage of lung disease.

Down-regulation of cytokine-induced interleukin-8 requires inhibition of p38 mitogen-activated protein kinase (MAPK) via MAPK phosphatase 1-dependent and -independent mechanisms

Down-regulation of overabundant interleukin (IL)-8 present in cystic fibrosis (CF) airways could ease excessive neutrophil burden and its deleterious consequences for the lung. IL-8 production in airway epithelial cells, stimulated with e.g. inflammatory cytokines IL-1β and tumor necrosis factor (TNF)-α, is regulated by several signaling pathways including nuclear factor (NF)-κB and p38 mitogen-activated protein kinase (MAPK). We previously demonstrated that the anti-inflammatory drugs dexamethasone and ibuprofen suppress NF-κB; however, only dexamethasone down-regulates cytokine-induced IL-8, highlighting the importance of non-NF-κB mechanisms. Here, we tested the hypothesis that down-regulation of cytokine-induced IL-8 requires modulation of the MAPK phosphatase (MKP)-1/p38 MAPK/mRNA stability pathway. The effects of dexamethasone (5 nm) and ibuprofen (480 μm) on this pathway and IL-8 were studied in CF (CFTE29o-, CFBE41o-) and non-CF (1HAEo-) airway epithelial cells. We observed that dexamethasone, but not ibuprofen, destabilizes IL-8 mRNA and up-regulates MKP-1 mRNA. Further, siRNA silencing of MKP-1, via p38 MAPK, leads to IL-8 overproduction and diminishes the anti-IL-8 potential of dexamethasone. However, MKP-1 overexpression does not significantly alter IL-8 production. By contrast, direct inhibition of p38 MAPK (inhibitor SB203580) efficiently suppresses IL-8 with potency comparable with dexamethasone. Similar to dexamethasone, SB203580 decreases IL-8 mRNA stability. Dexamethasone does not affect p38 MAPK activation, which excludes its effects upstream of p38 MAPK. In conclusion, normal levels of MKP-1 are necessary for a full anti-IL-8 potential of pharmacological agents; however, efficient pharmacological down-regulation of cytokine-induced IL-8 also requires direct effects on p38 MAPK and mRNA stability independently of MKP-1.

Pseudomonas aeruginosa biofilms in cystic fibrosis

The persistence of chronic Pseudomonas aeruginosa lung infections in cystic fibrosis (CF) patients is due to biofilm-growing mucoid (alginate-producing) strains. A biofilm is a structured consortium of bacteria, embedded in a self-produced polymer matrix consisting of polysaccharide, protein and DNA. In CF lungs, the polysaccharide alginate is the major part of the P. aeruginosa biofilm matrix. Bacterial biofilms cause chronic infections because they show increased tolerance to antibiotics and resist phagocytosis, as well as other components of the innate and the adaptive immune system. As a consequence, a pronounced antibody response develops, leading to immune complex-mediated chronic inflammation, dominated by polymorphonuclear leukocytes. The chronic inflammation is the major cause of the lung tissue damage in CF. Biofilm growth in CF lungs is associated with an increased frequency of mutations, slow growth and adaptation of the bacteria to the conditions in the lungs, and to antibiotic therapy. Low bacterial metabolic activity and increase of doubling times of the bacterial cells in CF lungs are responsible for some of the tolerance to antibiotics. Conventional resistance mechanisms, such as chromosomal β-lactamase, upregulated efflux pumps, and mutations of antibiotic target molecules in the bacteria, also contribute to the survival of P. aeruginosa biofilms. Biofilms can be prevented by early aggressive antibiotic prophylaxis or therapy, and they can be treated by chronic suppressive therapy.

Macrophage responses to CF pathogens: JNK MAP kinase signaling by Burkholderia cepacia complex lipopolysaccharide

Chronic bacterial colonization of the airways with opportunistic pathogens is the primary cause of morbidity and mortality in cystic fibrosis (CF) patients. Burkholderia cepacia complex (Bcc) organisms pose a particular challenge in CF lung disease, due in part to their ability to trigger a fulminant pneumonia. This study compares the U937 macrophage response to two Bcc species, B. cenocepacia and Burkholderia multivorans, against Pseudomonas aeruginosa and Staphylococcus aureus. The two Bcc strains demonstrated higher levels of U937 macrophage internalization compared with both P. aeruginosa and S. aureus. Both the Bcc strains also stimulated significantly greater levels of tumor necrosis factor-α and interleukin-1β from macrophages when compared with P. aeruginosa. Further examination of the macrophage response to B. multivorans demonstrated that the lipopolysaccharide component of these bacteria was a potent inducer of proinflammatory cytokines and was shown to signal predominantly through the c-Jun N-terminal kinase mitogen-activated protein kinase pathway. These studies further characterize the host response to Bcc and in particular B. multivorans, now the predominant Bcc species in many CF populations.

Elevated miR-155 promotes inflammation in cystic fibrosis by driving hyperexpression of interleukin-8

Cystic Fibrosis (CF) is characterized by a massive proinflammatory phenotype in the lung arising from profound expression of inflammatory genes, including interleukin-8 (IL-8). We have previously reported that IL-8 mRNA is stabilized in CF lung epithelial cells, resulting in concomitant hyperexpression of IL-8 protein. However, the mechanistic link between mutations in CFTR and acquisition of the proinflammatory phenotype in the CF airway has remained elusive. We hypothesized that specific microRNAs (miRNAs) might mediate this linkage. To identify the potential link, we screened an miRNA library for differential expression in ΔF508-CFTR and wild type CFTR lung epithelial cell lines. Of 22 differentially and significantly expressed miRNAs, we found that expression of miR-155 was more than 5-fold elevated in CF IB3-1 lung epithelial cells in culture, compared with control IB3-1/S9 cells. Clinically, miR-155 was also highly expressed in CF lung epithelial cells and circulating CF neutrophils biopsied from CF patients. We report here that high levels of miR-155 specifically reduced levels of SHIP1, thereby promoting PI3K/Akt activation. However, overexpressing SHIP1 or inhibition of PI3K in CF cells suppressed IL-8 expression. Finally, we found that phospho-Akt levels were elevated in CF lung epithelial cells and were specifically lowered by either antagomir-155 or elevated expression of SHIP1. We therefore suggest that elevated miR-155 contributes to the proinflammatory expression of IL-8 in CF lung epithelial cells by lowering SHIP1 expression and thereby activating the PI3K/Akt signaling pathway. These data suggest that miR-155 may play an important role in the activation of IL-8-dependent inflammation in CF.

Clinical significance of microbial infection and adaptation in cystic fibrosis

A select group of microorganisms inhabit the airways of individuals with cystic fibrosis. Once established within the pulmonary environment in these patients, many of these microbes adapt by altering aspects of their structure and physiology. Some of these microbes and adaptations are associated with more rapid deterioration in lung function and overall clinical status, whereas others appear to have little effect. Here we review current evidence supporting or refuting a role for the different microbes and their adaptations in contributing to poor clinical outcomes in cystic fibrosis.

Burkholderia cenocepacia O polysaccharide chain contributes to caspase-1-dependent IL-1beta production in macrophages

Burkholderia cenocepacia infections in CF patients involve heightened inflammation, fatal sepsis, and high antibiotic resistance. Proinflammatory IL-1β secretion is important in airway inflammation and tissue damage. However, little is known about this pathway in macrophages upon B. cenocepacia infection. We report here that murine macrophages infected with B. cenocepacia K56-2 produce proinflammatory cytokine IL-1β in a TLR4 and caspase-1-mediated manner. We also determined that the OPS (O antigen) of B. cenocepacia LPS contributes to IL-1β production and pyroptotic cell death. Furthermore, we showed that the malfunction of the CFTR channel augmented IL-1β production upon B. cenocepacia infection of murine macrophages. Taken together, we identified eukaryotic and bacterial factors that contribute to inflammation during B. cenocepacia infection, which may aid in the design of novel approaches to control pulmonary inflammation.

Sputum induction in routine clinical care of children with cystic fibrosis

OBJECTIVE

To determine the microbiological yield of induced sputum (IS) samples compared with conventional airway samples, spontaneously expectorated sputum and throat swabs, in children with cystic fibrosis (CF) attending an outpatient clinic.

STUDY DESIGN

Ninety-five children with CF (75 able to spontaneously expectorate sputum) were included in this prospective cross-sectional comparative study. After obtaining expectorated sputum or throat swabs samples, IS was obtained by performing the sputum induction procedure using an eFlow device (PARI, Starnberg, Germany). CF bacterial culture results were compared between the two procedures.

RESULTS

Differences in culture results between samples were observed in 25 of 94 (27%) patients. IS had a significantly higher yield for CF pathogens, with 80% of the differences being due to detection of additional organisms in IS samples. Overall, SI was well tolerated, but 12 of 95 cases had a >20% postinduction decline in forced expiratory volume in 1 second. The whole SI procedure took 30 to 85 minutes of clinic time, and its estimated additional cost was $150 (US)/patient.

CONCLUSIONS

Induced sputum has a higher microbiological yield compared with the conventional samples in children with CF, even in patients capable of expectorating sputum spontaneously. Although sputum induction is safe and tolerable, it is time-consuming and expensive in routine clinical settings.

MAPK signaling pathways regulate IL-8 mRNA stability and IL-8 protein expression in cystic fibrosis lung epithelial cell lines

Cystic fibrosis (CF) is characterized by a massive proinflammatory phenotype in the lung, caused by mutations in the CFTR gene. IL-8 and other proinflammatory mediators are elevated in the CF airway, and the immediate mechanism may depend on disease-specific stabilization of IL-8 mRNA in CF lung epithelial cells. MAPK signaling pathways impact directly on IL-8 protein expression in CF cells, and we have hypothesized that the mechanism may also involve stabilization of the IL-8 mRNA. To test this hypothesis, we have examined the effects of pharmacological and molecular inhibitors of p38, and downstream MK2, ERK1/2, and JNK, on stability of IL-8 mRNA in CF lung epithelial cells. We previously showed that tristetraprolin (TTP) was constitutively low in CF and that raising TTP destabilized the IL-8 mRNA. We therefore also tested these effects on CF lung epithelial cells stably expressing TTP. TTP binds to AU-rich elements in the 3'-UTR of the IL-8 mRNA. We find that inhibition of p38 and ERK1/2 reduces the stability of IL-8 mRNA in parental CF cells. However, neither intervention further lowers TTP-dependent destabilization of IL-8 mRNA. By contrast, inhibition of the JNK-2 pathway has no effect on IL-8 mRNA stability in parental CF cell, but rather increases the stability of the message in cells expressing high levels of TTP. However, we find that inhibition of ERK1/2 or p38 leads to suppression of the effect of JNK-2 inhibition on IL-8 mRNA stability. These data thus lend support to our hypothesis that constitutive MAPK signaling and proteasomal activity might also contribute, along with aberrantly lower TTP, to the proinflammatory phenotype in CF lung epithelial cells by increasing IL-8 mRNA stability and IL-8 protein expression.

Lactate in cystic fibrosis sputum

BACKGROUND

Antibiotic therapy is thought to improve lung function in patients with cystic fibrosis (CF) by decreasing neutrophil-derived inflammation. We investigated the origin and clinical significance of lactate in the chronically inflamed CF lung.

METHODS

Lactate was measured in sputa of 18 exacerbated and 25 stable CF patients via spectrophotometry and gaschromatography. Lung function was assessed via spirometry. Seven patients with chronic obstructive pulmonary disease (COPD) and three patients with acute lung inflammation served as control groups. Neutrophil and bacterial lactate production was assessed under aerobic and anaerobic conditions.

RESULTS

In sputum specimens of patients with respiratory exacerbations lactate concentrations decreased significantly (p<0.005) from 3.4±2.3mmol/L to 1.4±1.4mmol/L after 2-3 weeks of intravenous antibiotics. Successful treatment was reflected in 16 patients (88.9%) by FVC increase associated with lactate decrease (p<0.05). In every single sputum lactate was detectable (3.0±3.1mmol/L, range 0.2-14.1mmol/L). Lactate was lower (1.6±0.8mmol/L) in sputa from seven COPD patients, and it was below the detection limit in three patients with acute lung inflammation. Neutrophil lactate production accumulated up to 10.5mmol/L after 4 days, whereas bacterial lactate production did not appear to contribute substantially to sputum lactate concentrations.

CONCLUSIONS

Successful antibiotic therapy is reflected by a decrease in lactate concentrations. Neutrophils are the most likely source for lactate in sputum of CF patients. Therefore lactate may be used to monitor responses to antibiotic therapy as an adjunct to lung function measurements.

Evaluation of the efficacy of real-time polymerase chain reaction for the routine early detection of Pseudomonas aeruginosa in cystic fibrosis sputum and throat swab specimens

A longitudinal study of 2099 sputa and throat swabs received from 183 pediatric cystic fibrosis patients over a 29-month period was used to evaluate the efficacy of real-time polymerase chain reaction (PCR) for the early detection of Pseudomonas aeruginosa as compared to microbiologic culture. Real-time PCR resulted in an increased number of specimens identified as P. aeruginosa positive. The sensitivity of culture was 82% (373/453) and of PCR was 93% (420/453) when considering both positive culture and PCR results as true positives. Of the 80 specimens identified as PCR positive/culture negative for P. aeruginosa, the subsequent patient sample in 32.5% (26/80) of specimens concerned was identified as P. aeruginosa culture positive, suggesting that PCR has the potential to detect P. aeruginosa earlier than the microbiologic culture. Real-time PCR analysis found no evidence of the Liverpool and Manchester epidemic P. aeruginosa strains in the cohort examined. The findings of this study highlight the importance of specimen collection protocols to ensure that adequate samples are received at the laboratory for testing, thereby minimizing the potential for reporting of false-negative P. aeruginosa culture results.

Monocytes from children with clinically stable cystic fibrosis show enhanced expression of Toll-like receptor 4

Lung disease in patients with cystic fibrosis (CF) is characterized by recurrent bacterial respiratory infections and intense airway inflammation. Pattern recognition receptors such as Toll-like receptor 2 (TLR2) and TLR4 identify bacterial pathogens and activate the innate immune response. We therefore hypothesized that increased expression of these receptors would be found on circulating immune cells from children with CF. A cohort of 66 young children (median age 3 years) with CF was studied and compared to both healthy controls (n = 14) and children without CF who were being investigated for recurrent respiratory infections (non-CF disease controls; n = 17) of a similar age. Surface expression of TLR2 and TLR4 on peripheral blood monocytes was analyzed using flow cytometry. TLR4 expression was significantly higher in patients with CF compared to healthy controls (P = 0.017) and non-CF disease controls (P = 0.025) but did not vary according to the presence or absence of pulmonary infection with Gram-negative or Gram-positive bacteria (P = 0.387) in the CF group. In contrast, TLR2 expression was similar across all three study groups (P = 0.930). The increased surface expression of TLR4 seen in young children with CF appears to be related to having CF per se and not related to current pulmonary infection.

Potential of anti-inflammatory treatment for cystic fibrosis lung disease

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

A diagnostic PCR assay for the detection of an Australian epidemic strain of Pseudomonas aeruginosa

Background

Chronic lung infection with the bacterium Pseudomonas aeruginosa is one of the hallmarks of cystic fibrosis (CF) and is associated with worsening lung function, increased hospitalisation and reduced life expectancy. A virulent clonal strain of P. aeruginosa (Australian epidemic strain I; AES-I) has been found to be widespread in CF patients in eastern Australia.

Methods

Suppression subtractive hybridization (SSH) was employed to identify genetic sequences that are present in the AES-I strain but absent from the sequenced reference strain PAO1. We used PCR to evaluate the distribution of several of the AES-I loci amongst a collection of 188 P. aeruginosa isolates which was comprised of 35 AES-I isolates (as determined by PFGE), 78 non-AES-I CF isolates including other epidemic CF strains as well as 69 P. aeruginosa isolates from other clinical and environmental sources.

Results

We have identified a unique AES-I genetic locus that is present in all 35 AES-I isolates tested and not present in any of the other 153 P. aeruginosa strains examined. We have used this unique AES-I locus to develop a diagnostic PCR and a real-time PCR assay to detect the presence of P. aeruginosa and AES-I in patient sputum samples.

Conclusions

We have developed diagnostic PCR assays that are 100% sensitive and 100% specific for the P. aeruginosa strain AES-I. We have also shown that Whatman FTA^® Elute cards may be used with PCR-based assays to rapidly detect the presence of P. aeruginosa strains in CF sputum.

The changing microbial epidemiology in cystic fibrosis

Infection of the airways remains the primary cause of morbidity and mortality in persons with cystic fibrosis (CF). This review describes salient features of the epidemiologies of microbial species that are involved in respiratory tract infection in CF. The apparently expanding spectrum of species causing infection in CF and recent changes in the incidences and prevalences of infection due to specific bacterial, fungal, and viral species are described. The challenges inherent in tracking and interpreting rates of infection in this patient population are discussed.

Early bronchiectasis in cystic fibrosis detected by surveillance CT

There is emerging evidence that cystic fibrosis lung disease begins early in infancy. Newborn screening allows early detection and surveillance of pulmonary disease and the possibility of early intervention in this life-shortening condition. We report two children with cystic fibrosis who underwent a comprehensive assessment from diagnosis that included measurement of lung function, limited-slice high-resolution CT and BAL performed annually. Early aggressive surveillance enabled significant lung disease and bronchiectasis to be detected during the first few years of life and led to a change in management, highlighting a clinical role for CT scanning during the preschool years in children with cystic fibrosis.

Platelet proinflammatory activity in clinically stable patients with CF starts in early childhood

BACKGROUND

Early onset chronic inflammation is present in CF. Platelets may contribute to inflammation by cytokine release and interaction with leukocytes.

METHODS

Parameters of platelet proinflammatory function (soluble CD62P, soluble CD40L, the percentage of platelet-leukocyte aggregates, platelet CD62P) and platelet procoagulatory function (PAC-1-binding to activated integrin alpha(IIb)beta(3) and expression of integrin alpha(IIb)beta(3)=CD41a) were measured in patients and controls.

RESULTS

Levels of sCD62P, sCD40L were increased in CF irrespective of age and activity of inflammation. The number of platelet-leukocyte aggregates was elevated in older CF patients. PAC-1-binding to platelets decreased with growing activity of inflammation. Exocytosis of CD41a upon platelet activation was reduced.

CONCLUSION

In CF, platelet proinflammatory activity is increased at very young age already and might promote inflammation and tissue damage. On the other hand, platelets seem to downregulate the activation of their most important integrin (alpha(IIb)beta(3)) for clot formation.

The antioxidant role of thiocyanate in the pathogenesis of cystic fibrosis and other inflammation-related diseases

Cystic fibrosis (CF) is a pleiotropic disease, originating from mutations in the CF transmembrane conductance regulator (CFTR). Lung injuries inflicted by recurring infection and excessive inflammation cause approximately 90% of the morbidity and mortality of CF patients. It remains unclear how CFTR mutations lead to lung illness. Although commonly known as a Cl(-) channel, CFTR also conducts thiocyanate (SCN(-)) ions, important because, in several ways, they can limit potentially harmful accumulations of hydrogen peroxide (H(2)O(2)) and hypochlorite (OCl(-)). First, lactoperoxidase (LPO) in the airways catalyzes oxidation of SCN(-) to tissue-innocuous hypothiocyanite (OSCN(-)), while consuming H(2)O(2). Second, SCN(-) even at low concentrations competes effectively with Cl(-) for myeloperoxidase (MPO) (which is released by white blood cells), thus limiting OCl(-) production by the enzyme. Third, SCN(-) can rapidly reduce OCl(-) without catalysis. Here, we show that SCN(-) and LPO protect a lung cell line from injuries caused by H(2)O(2); and that SCN(-) protects from OCl(-) made by MPO. Of relevance to inflammation in other diseases, we find that in three other tested cell types (arterial endothelial cells, a neuronal cell line, and a pancreatic beta cell line) SCN(-) at concentrations of > or =100 microM greatly attenuates the cytotoxicity of MPO. Humans naturally derive SCN(-) from edible plants, and plasma SCN(-) levels of the general population vary from 10 to 140 microM. Our findings raise the possibility that insufficient levels of antioxidant SCN(-) provide inadequate protection from OCl(-), thus worsening inflammatory diseases, and predisposing humans to diseases linked to MPO activity, including atherosclerosis, neurodegeneration, and certain cancers.

The triterpenoid CDDO limits inflammation in preclinical models of cystic fibrosis lung disease

Excessive inflammation in cystic fibrosis (CF) lung disease is a contributor to progressive pulmonary decline. Effective and well-tolerated anti-inflammatory therapy may preserve lung function, thereby improving quality and length of life. In this paper, we assess the anti-inflammatory effects of the synthetic triterpenoid 2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid (CDDO) in preclinical models of CF airway inflammation. In our experiments, mice carrying the R117H Cftr mutation have significantly reduced airway inflammatory responses to both LPS and flagellin when treated with CDDO before inflammatory challenge. Anti-inflammatory effects observed include reduced airway neutrophilia, reduced concentrations of proinflammatory cytokines and chemokines, and reduced weight loss. Our findings with the synthetic triterpenoids in multiple cell culture models of CF human airway epithelia agree with effects previously described in other disease models (e.g., neoplastic cells). These include the ability to reduce NF-kappaB activation while increasing nuclear factor erythroid-related factor 2 (Nrf2) activity. As these two signaling pathways appear to be pivotal in regulating the net inflammatory response in the CF airway, these compounds are a promising potential anti-inflammatory therapy for CF lung disease.

Innate immune receptors on neutrophils and their role in chronic lung disease

Neutrophils, the prototypic cells of the innate immune system, are recruited to infected sites to protect the human body from invading pathogens. To accomplish this function, neutrophils sense pathogens and endogenous damage-associated molecules via innate immune receptors, such as Toll-like receptors (TLRs) and other pattern recognition receptors. This defence function is essential for the pulmonary microenvironment where the host is faced with millions of particles and pathogens inhaled daily. Chronic lung diseases, such as cystic fibrosis or chronic obstructive pulmonary disease are characterized by a neutrophil accumulation and chronic bacterial colonization of the airways. Consequently, insights into the role of TLRs on neutrophils in chronic lung diseases are of high relevance for further diagnostic and therapeutic approaches. Here we summarize and discuss recent advances in the expression, regulation and functional role of TLRs on neutrophils in chronic lung diseases.

Cough-generated aerosols of Pseudomonas aeruginosa and other Gram-negative bacteria from patients with cystic fibrosis

BACKGROUND

Pseudomonas aeruginosa is the most common bacterial pathogen in patients with cystic fibrosis (CF). Current infection control guidelines aim to prevent transmission via contact and respiratory droplet routes and do not consider the possibility of airborne transmission. It was hypothesised that subjects with CF produce viable respirable bacterial aerosols with coughing.

METHODS

A cross-sectional study was undertaken of 15 children and 13 adults with CF, 26 chronically infected with P aeruginosa. A cough aerosol sampling system enabled fractioning of respiratory particles of different sizes and culture of viable Gram-negative non-fermentative bacteria. Cough aerosols were collected during 5 min of voluntary coughing and during a sputum induction procedure when tolerated. Standardised quantitative culture and genotyping techniques were used.

RESULTS

P aeruginosa was isolated in cough aerosols of 25 subjects (89%), 22 of whom produced sputum samples. P aeruginosa from sputum and paired cough aerosols were indistinguishable by molecular typing. In four cases the same genotype was isolated from ambient room air. Approximately 70% of viable aerosols collected during voluntary coughing were of particles <or=3.3 microm aerodynamic diameter. P aeruginosa, Burkholderia cenocepacia, Stenotrophomonas maltophilia and Achromobacter xylosoxidans were cultivated from respiratory particles in this size range. Positive room air samples were associated with high total counts in cough aerosols (p = 0.003). The magnitude of cough aerosols was associated with higher forced expiratory volume in 1 s (r = 0.45, p = 0.02) and higher quantitative sputum culture results (r = 0.58, p = 0.008).

CONCLUSION

During coughing, patients with CF produce viable aerosols of P aeruginosa and other Gram-negative bacteria of respirable size range, suggesting the potential for airborne transmission.

TLR-4-mediated innate immunity is reduced in cystic fibrosis airway cells

Airway epithelial cells contribute to the inflammatory response of the lung, and their innate immune response is primarily mediated via Toll-like receptor (TLR) signaling. Cystic fibrosis (CF) airways are chronically infected with Pseudomonas aeruginosa, suggesting a modified immune response in CF. We investigated the TLR-4 expression and the inflammatory profile (IL-8 and IL-6 secretion) in CF bronchial epithelial cell line CFBE41o- and its CF transmembrane ion condcutance regulator (CFTR)-corrected counterpart grown under air-liquid interface conditions after stimulation with lipopolysaccharide (LPS) from gram-negative bacteria. In CFTR-corrected cells, IL-8 and IL-6 secretions were constitutively activated but significantly increased after LPS stimulation compared with CFBE41o-. Blocking TLR-4 by a specific antibody significantly inhibited IL-8 secretion only in CFTR-corrected cells. Transfection with specific siRNA directed against TLR-4 mRNA significantly reduced the response to LPS in both cell lines. Fluorescence-activated cell sorter analysis revealed significantly higher levels of TLR-4 surface expression in CFTR-corrected cells. In histologic lung sections of patients with CF, the TLR-4 expression in the bronchial epithelium was significantly reduced compared with healthy control subjects. In CF the loss of CFTR function appears to decrease innate immune responses, possibly by altering the expression of TLR-4 on airway epithelial cells. This may contribute to chronic bacterial infection of CF airways.

Loss of CFTR results in reduction of histone deacetylase 2 in airway epithelial cells

Inflammatory cytokines, particularly the neutrophil chemoattractant IL-8, are elevated in the cystic fibrosis (CF) airway, even in the absence of detectable infection. The transcriptional regulation of many inflammatory genes, including IL8 (CXCL8), involves chromatin remodeling through histone acetylation. NF-kappaB is known to facilitate histone acetylation of IL8 and other proinflammatory gene promoters, but we find that increased NF-kappaB activation cannot explain the elevated IL8 expression and promoter acetylation seen in CFTR-deficient cells. Recognized components of the NF-kappaB-coactivator complex, acetyltransferase CBP, p300, and the histone deacetylase HDAC1, are unchanged by CFTR activity. However, we find that the histone acetyltransferase (HAT)/HDAC balance is sensitive to CFTR function, as cells with reduced or absent CFTR function have decreased HDAC2 protein, resulting in hyperacetylation of the IL8 promoter and increased IL8 transcription. Reduced HDAC2 and HDAC2 activity, but not HDAC2 mRNA, is observed in cells deficient in CFTR. Suppressing HDAC2 expression with HDAC2 short hairpin RNA (shRNA) results in increased IL8 expression and promoter acetylation comparable with CFTR-deficient cells. Treating CFTR-deficient cells with N-acetyl-cysteine (NAC) increases HDAC2 expression to near control levels. Our data suggest that there is an intrinsic alteration in the HAT/HDAC balance in cells lacking CFTR function in vitro and in native CF tissue and that oxidative stress is likely contributing to this alteration. This mechanism, found in other inflammatory airway diseases, provides an explanation for the apparent dysregulation of inflammatory mediators seen in the CF airway, as reduced histone deacetylation would potentially influence many genes.

Tristetraprolin regulates IL-8 mRNA stability in cystic fibrosis lung epithelial cells

Cystic fibrosis (CF) is due to mutations in the CFTR gene and is characterized by hypersecretion of the proinflammatory chemokine IL-8 into the airway lumen. Consequently, this induces the highly inflammatory cellular phenotype typical of CF. Our initial studies revealed that IL-8 mRNA is relatively stable in CF cells compared with those that had been repaired with [WT]CFTR (wild-type CFTR). Relevantly, the 3'-UTR of IL-8 mRNA contains AU-rich sequences (AREs) that have been shown to mediate posttranscriptional regulation of proinflammatory genes upon binding to ARE-binding proteins including Tristetraprolin (TTP). We therefore hypothesized that very low endogenous levels of TTP in CF cells might be responsible for the relative stability of IL-8 mRNA. As predicted, increased expression of TTP in CF cells resulted in reduced stability of IL-8 mRNA. An in vitro analysis of IL-8 mRNA stability in CF cells also revealed a TTP-induced enhancement of deadenylation causing reduction of IL-8 mRNA stability. We conclude that enhanced stability of IL-8 mRNA in TTP-deficient CF lung epithelial cells serve to drive the proinflammatory cellular phenotype in the CF lung.