CF airway epithelia display exaggerated host defense responses and prolonged cilia loss during RSV infection

BACKGROUND

In individuals with cystic fibrosis (CF), respiratory viral infections frequently result in hospitalization and have been linked to secondary bacterial infection and colonization, highlighting viral infections as possible contributors to CF lung disease progression. We hypothesized that expression of antiviral host defense genes is dysregulated in CF airway epithelia.

METHODS

We infected primary CF and Non-CF airway epithelia with respiratory syncytial virus (RSV) and characterized their responses at 12 hr, 24 hr, 48 hr, 72 hr, and 120 hr post infection (hpi) by RNA sequencing (RNAseq).

RESULTS

Our analysis revealed strikingly different gene expression profiles for the CF and Non-CF epithelia over the course of the infection. While both CF and Non-CF cells exhibited an early signature for interferon signaling and antiviral defense pathways, this response was relatively exaggerated and sustained in CF epithelia. We also observed, in both genotypes, a transient downregulation of cilia-associated genes and loss of ciliary activity by 72 hpi. Interestingly, recovery of cilia activity was delayed in the CF epithelia.

CONCLUSIONS

These findings further our understanding of innate immune dysfunction in the CF airway epithelium and suggest that virus-induced cilia injury may further compromise host defenses in CF airways.

Transcriptomic analysis of primary nasal epithelial cells reveals altered interferon signalling in preterm birth survivors at one year of age

Introduction: Many survivors of preterm birth (<37 weeks gestation) have lifelong respiratory deficits, the drivers of which remain unknown. Influencers of pathophysiological outcomes are often detectable at the gene level and pinpointing these differences can help guide targeted research and interventions. This study provides the first transcriptomic analysis of primary nasal airway epithelial cells in survivors of preterm birth at approximately 1 year of age. Methods: Nasal airway epithelial brushings were collected, and primary cell cultures established from term (>37 weeks gestation) and very preterm participants (≤32 weeks gestation). Ex vivo RNA was collected from brushings with sufficient cell numbers and in vitro RNA was extracted from cultured cells, with bulk RNA sequencing performed on both the sample types. Differential gene expression was assessed using the limma-trend pipeline and pathway enrichment identified using Reactome and GO analysis. To corroborate gene expression data, cytokine concentrations were measured in cell culture supernatant. Results: Transcriptomic analysis to compare term and preterm cells revealed 2,321 genes differentially expressed in ex vivo samples and 865 genes differentially expressed in cultured basal cell samples. Over one third of differentially expressed genes were related to host immunity, with interferon signalling pathways dominating the pathway enrichment analysis and IRF1 identified as a hub gene. Corroboration of disrupted interferon release showed that concentrations of IFN-α2 were below measurable limits in term samples but elevated in preterm samples [19.4 (76.7) pg/ml/µg protein, p = 0.03]. IFN-γ production was significantly higher in preterm samples [3.3 (1.5) vs. 9.4 (17.7) pg/ml/µg protein; p = 0.01] as was IFN-β [7.8 (2.5) vs. 13.6 (19.5) pg/ml/µg protein, p = 0.01]. Conclusion: Host immunity may be compromised in the preterm nasal airway epithelium in early life. Altered immune responses may lead to cycles of repeated infections, causing persistent inflammation and tissue damage which can have significant impacts on long-term respiratory function.

Abnormal functional lymphoid tolerance and enhanced myeloid exocytosis are characteristics of resting and stimulated PBMCs in cystic fibrosis patients

Introduction

Cystic Fibrosis (CF) is the commonest genetically inherited disease (1 in 4,500 newborns) and 70% of people with CF (pwCF) harbour the F508Del mutation, resulting in misfolding and incorrect addressing of the channel CFTR to the epithelial membrane and subsequent dysregulation of fluid homeostasis. Although studies have underscored the importance and over-activation of myeloid cells, and in particular neutrophils in the lungs of people with CF (pwCF), relatively less emphasis has been put on the potential immunological bias in CF blood cells, at homeostasis or following stimulation/infection.

Methods

Here, we revisited, in an exhaustive fashion, in pwCF with mild disease (median age of 15, median % FEV1 predicted = 87), whether their PBMCs, unprimed or primed with a 'non specific' stimulus (PMA+ionomycin mix) and a 'specific' one (live P.a =PAO1 strain), were differentially activated, compared to healthy controls (HC) PBMCs.

Results

1) we analysed the lymphocytic and myeloid populations present in CF and Control PBMCs (T cells, NKT, Tgd, ILCs) and their production of the signature cytokines IFN-g, IL-13, IL-17, IL-22. 2) By q-PCR, ELISA and Luminex analysis we showed that CF PBMCs have increased background cytokines and mediators production and a partial functional tolerance phenotype, when restimulated. 3) we showed that CF PBMCs low-density neutrophils release higher levels of granule components (S100A8/A9, lactoferrin, MMP-3, MMP-7, MMP-8, MMP-9, NE), demonstrating enhanced exocytosis of potentially harmful mediators.

Discussion

In conclusion, we demonstrated that functional lymphoid tolerance and enhanced myeloid protease activity are key features of cystic fibrosis PBMCs.

Association between early respiratory viral infections and structural lung disease in infants with cystic fibrosis

BACKGROUND

Infants with cystic fibrosis (CF) develop structural lung disease early in life, and viral infections are associated with progressive lung disease. We hypothesized that the presence of respiratory viruses would be associated with structural lung disease on computed tomography (CT) of the chest in infants with CF.

METHODS

Infants with CF were enrolled before 4 months of age. Multiplex PCR assays were performed on nasal swabs to detect respiratory viruses during routine visits and when symptomatic. Participants underwent CT imaging at approximately 12 months of age. Associations between Perth-Rotterdam Annotated Grid Morphometric Analysis for CF (PRAGMA-CF) CT scores and respiratory viruses and symptoms were assessed with Spearman correlation coefficients.

RESULTS

Sixty infants were included for analysis. Human rhinovirus was the most common virus detected, on 28% of tested nasal swabs and in 85% of participants. The median (IQR) extent of lung fields that was healthy based on PRAGMA-CF was 98.7 (0.8)%. There were no associations between PRAGMA-CF and age at first virus, or detection of any virus, including rhinovirus, respiratory syncytial virus, or parainfluenza. The extent of airway wall thickening was associated with ever having wheezed (ρ = 0.31, p = 0.02) and number of encounters with cough (ρ = 0.25, p = 0.0495).

CONCLUSIONS

Infants with CF had minimal structural lung disease. We did not find an association between respiratory viruses and CT abnormalities. Wheezing and frequency of cough were associated with early structural changes.

Rhinovirus-induced anti-viral interferon secretion is not deficient and not delayed in sinonasal epithelial cells of patients with chronic rhinosinusitis with nasal polyp

Dysregulated innate and adaptive immune response to rhinoviral infection plays an important role in the exacerbation or progressive course of chronic rhinosinusitis (CRS). However, few studies have evaluated whether rhinovirus-induced production of anti-viral interferon is deficient or delayed in inflammatory epithelial cells of patients with CRS with nasal polyps. The aim of the present study is to investigate the replication rates of rhinovirus 16 (RV 16), RV16-induced antiviral interferon secretion, and the expression levels of pattern recognition receptors after RV 16 infection or TLR3 stimulation with poly (I: C) in normal and inflammatory epithelial cells. Inflammatory epithelial cells were obtained from CRS patients with nasal polyps and normal epithelial cells were derived from ethmoid sinus mucosa during endoscopic reduction of blowout fracture or uncinate process mucosa of patients with septal deviation. Cultured cells were infected with RV 16 or treated with poly (I: C) for 24, 48, and 72 h. Cells and media were harvested at each time point and used to evaluate RV16 replication rates, the secretion of IFN-β, -λ1, -λ2, viperin, Mx, and OAS, and the expression levels of TRL3, RIG-I, MDA5, phospho-NFκB, and phospho-IRF3. RV replication rates reached peak levels 48 h after inoculation in both normal and inflammatory epithelial cells and showed no difference between both groups of epithelial cells at any time point. The release of IFN-β, -λ1, and -λ2 in normal and inflammatory epithelial cells was also strongly induced 48 h after RV16 inoculation but reached peak levels 24 h after poly (I: C) treatment. The expression levels of viperin, Mx, OAS, TLR3, RIG-I, MDA5, phospho-NFκB, and phospho-IRF3 showed similar patterns in both groups of epithelial cells. These results suggest that the production of RV16-induced antiviral interferons is not deficient or delayed in inflammatory epithelial cells from CRS patients with nasal polyps.

Pseudomonas aeruginosa modulates neutrophil granule exocytosis in an in vitro model of airway infection

A population of neutrophils recruited into cystic fibrosis (CF) airways is associated with proteolytic lung damage, exhibiting high expression of primary granule exocytosis marker CD63 and reduced phagocytic receptor CD16. Causative factors for this population are unknown, limiting intervention. Here we present a laboratory model to characterize responses of differentiated airway epithelium and neutrophils following respiratory infection. Pediatric primary airway epithelial cells were cultured at the air–liquid interface, challenged individually or in combination with rhinovirus (RV) and Pseudomonas aeruginosa, then apically washed with medical saline to sample epithelial infection milieus. Cytokine multiplex analysis revealed epithelial antiviral signals, including IP‐10 and RANTES, increased with exclusive RV infection but were diminished if P. aeruginosa was also present. Proinflammatory signals interleukin‐1α and β were dominant in P. aeruginosa infection milieus. Infection washes were also applied to a published model of neutrophil transmigration into the airways. Neutrophils migrating into bacterial and viral–bacterial co‐infection milieus exhibited the in vivo CF phenotype of increased CD63 expression and reduced CD16 expression, while neutrophils migrating into milieus of RV‐infected or uninfected cultures did not. Individually, bacterial products lipopolysaccharide and N‐formylmethionyl‐leucyl‐phenylalanine and isolated cytokine signals only partially activated this phenotype, suggesting that additional soluble factors in the infection microenvironment trigger primary granule release. Findings identify P. aeruginosa as a trigger of acute airway inflammation and neutrophil primary granule exocytosis, underscoring potential roles of airway microbes in prompting this neutrophil subset. Further studies are required to characterize microbes implicated in primary granule release, and identify potential therapeutic targets.

Immunoglobulin A Mucosal Immunity and Altered Respiratory Epithelium in Cystic Fibrosis

The respiratory epithelium represents the first chemical, immune, and physical barrier against inhaled noxious materials, particularly pathogens in cystic fibrosis. Local mucus thickening, altered mucociliary clearance, and reduced pH due to CFTR protein dysfunction favor bacterial overgrowth and excessive inflammation. We aimed in this review to summarize respiratory mucosal alterations within the epithelium and current knowledge on local immunity linked to immunoglobulin A in patients with cystic fibrosis.

Current evidence on the effect of highly effective CFTR modulation on interleukin-8 in cystic fibrosis

INTRODUCTION

Cystic fibrosis (CF) is a genetically inherited disease, with mortality and morbidity associated with respiratory disease. The inflammatory response in CF is characterized by excessive neutrophil influx to the airways, mainly due to the increased local production and retention of interleukin-8 (IL-8), a potent neutrophil chemoattractant.

AREAS COVERED

We discuss how the chemokine IL-8 dominates the inflammatory profile of the airways in CF lung disease. Cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapies are designed to correct the malfunctioning protein resulting from specific CFTR mutations. This review covers current evidence on the impact of CFTR impairment on levels of IL-8 and outlines the influence of effective CFTR modulation on inflammation in CF with a focus on cytokine production. Review of the literature was carried out using the PUBMED database, Google Scholar, and The Cochrane Library databases, using several appropriate generic terms.

EXPERT OPINION

Therapeutic interventions specifically targeting the defective CFTR protein have improved the outlook for CF. Accumulating studies on the effect of highly effective CFTR modulation on inflammation indicate an impact on IL-8 levels. Further studies are required to increase our knowledge of early onset innate inflammatory dysregulation and on anti-inflammatory mechanisms of CFTR modulators.

Cystic Fibrosis Clinical Isolates of Aspergillus fumigatus Induce Similar Muco-inflammatory Responses in Primary Airway Epithelial Cells

Aspergillus is increasingly associated with lung inflammation and mucus plugging in early cystic fibrosis (CF) disease during which conidia burden is low and strains appear to be highly diverse. It is unknown whether clinical Aspergillus strains vary in their capacity to induce epithelial inflammation and mucus production. We tested the hypothesis that individual colonising strains of Aspergillus fumigatus would induce different responses. Ten paediatric CF Aspergillus isolates were compared along with two systemically invasive clinical isolates and an ATCC reference strain. Isolates were first characterised by ITS gene sequencing and screened for antifungal susceptibility. Three clusters (A-C) of Aspergillus isolates were identified by ITS. Antifungal susceptibility was variable, particularly for itraconazole. Submerged CF and non-CF monolayers as well as differentiated primary airway epithelial cell cultures were incubated with conidia for 24 h to allow germination. None of the clinical isolates were found to significantly differ from one another in either IL-6 or IL-8 release or gene expression of secretory mucins. Clinical Aspergillus isolates appear to be largely homogenous in their mucostimulatory and immunostimulatory capacities and, therefore, only the antifungal resistance characteristics are likely to be clinically important.

Overcoming Challenges to Make Bacteriophage Therapy Standard Clinical Treatment Practice for Cystic Fibrosis

Individuals with cystic fibrosis (CF) are given antimicrobials as prophylaxis against bacterial lung infection, which contributes to the growing emergence of multidrug resistant (MDR) pathogens isolated. Pathogens such as Pseudomonas aeruginosa that are commonly isolated from individuals with CF are armed with an arsenal of protective and virulence mechanisms, complicating eradication and treatment strategies. While translation of phage therapy into standard care for CF has been explored, challenges such as the lack of an appropriate animal model demonstrating safety in vivo exist. In this review, we have discussed and provided some insights in the use of primary airway epithelial cells to represent the mucoenvironment of the CF lungs to demonstrate safety and efficacy of phage therapy. The combination of phage therapy and antimicrobials is gaining attention and has the potential to delay the onset of MDR infections. It is evident that efforts to translate phage therapy into standard clinical practice have gained traction in the past 5 years. Ultimately, collaboration, transparency in data publications and standardized policies are needed for clinical translation.

Clinical characteristics of SARS-CoV-2 infection in children with cystic fibrosis: An international observational study

BACKGROUND

The presence of co-morbidities, including underlying respiratory problems, has been identified as a risk factor for severe COVID-19 disease. Information on the clinical course of SARS-CoV-2 infection in children with cystic fibrosis (CF) is limited, yet vital to provide accurate advice for children with CF, their families, caregivers and clinical teams.

METHODS

Cases of SARS-CoV-2 infection in children with CF aged less than 18 years were collated by the CF Registry Global Harmonization Group across 13 countries between 1 February and 7 August 2020.

RESULTS

Data on 105 children were collated and analysed. Median age of cases was ten years (interquartile range 6-15), 54% were male and median percentage predicted forced expiratory volume in one second was 94% (interquartile range 79-104). The majority (71%) of children were managed in the community during their COVID-19 illness. Out of 24 children admitted to hospital, six required supplementary oxygen and two non-invasive ventilation. Around half were prescribed antibiotics, five children received antiviral treatments, four azithromycin and one additional corticosteroids. Children that were hospitalised had lower lung function and reduced body mass index Z-scores. One child died six weeks after testing positive for SARS-CoV-2 following a deterioration that was not attributed to COVID-19 disease.

CONCLUSIONS

SARS-CoV-2 infection in children with CF is usually associated with a mild illness in those who do not have pre-existing severe lung disease.

Diagnostic value of sputum cultures in children under 2 years of age with chronic suppurative lung diseases

BACKGROUND

Acquiring sputum cultures from infants is considered challenging. We describe their yield in infants with cystic fibrosis (CF) and other chronic suppurative lung diseases (CSLDs).

METHODS

Retrospective medical record review over a 4-year period, for infants aged 0-2 years with ≥2 airway bacterial cultures acquired by deep suction or induced sputum ≥4 weeks apart. Data included demographics, culture results, and clinical status.

RESULTS

A total of 98 infants (16 CF) were evaluated and 534 sputum cultures acquired, 201 in CF and 333 in CSLD. There were 12 (2-23), median (range) cultures/CF infant, and 3 (2-21)/CSLD infant. Age at first culture was 3.8 (1-19.5) months for CF and 10.4 (0.5-22) months for CSLD; p = .016. In total, 360 cultures (67%) were positive for any bacteria, with 170/234 (73%) positive during exacerbations, compared with 190/300 (63%) during routine visits; p = .05. More infants with CF than CSLD had cultures positive for Staphylococcus aureus (SA; 75% vs. 34%; p = .004) throughout the period. Pseudomonas aeruginosa (PA) was common in both CF and CSLD (56% and 44%, respectively; p = .42) and increased over time for CF but was high throughout for CSLD. The number of hospital days before PA acquisition was 6 (10.2) for CF and 28.8 (38.7) for CSLD (p = .003). No CF but 6/82 (7%) CSLD infants had chronic PA (p = .56).

CONCLUSIONS

Sputum cultures showed that infection, in particular PA, is common in CF and CSLD whereas SA is more common in CF. Prospective studies are warranted to elucidate the role of active surveillance in guiding antibiotic therapy.

An adapted novel flow cytometry methodology to delineate types of cell death in airway epithelial cells

Current methodologies to measure apoptotic and necrotic cell death using flow cytometry do not adequately differentiate between the two. Here, we describe a flow cytometry methodology adapted to airway epithelial cells (AEC) to sufficiently differentiate apoptotic and necrotic AEC. Specifically, cell lines and primary AEC (n = 12) were permeabilized or infected with rhinovirus 1b (RV1b) over 48 h. Cell death was then measured via annexin V/propidium iodide (A5/PI) or annexin V/TO-PRO-3 (A5/TP3) staining using a novel flow cytometry and gating methodology adapted to AEC. We show that A5/PI staining could not sufficiently differentiate between types of cell death following RV1b infection of primary AEC. However, A5/TP3 staining was able to distinguish six cell death populations (viable, necrotic, debris, A5⁺ apoptotic, A5^– apoptotic, apoptotic bodies) after permeabilization or infection with RV1b, with phenotypic differences were observed in apoptotic populations. Collectively, using a staining and gating strategy never adapted to AEC, A5/TP3 could accurately differentiate and quantify viable, necrotic, and apoptotic AEC following RV1b infection.

Dysregulated signalling pathways in innate immune cells with cystic fibrosis mutations

Cystic fibrosis (CF) is one of the most common life-limiting recessive genetic disorders in Caucasians, caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR). CF is a multi-organ disease that involves the lungs, pancreas, sweat glands, digestive and reproductive systems and several other tissues. This debilitating condition is associated with recurrent lower respiratory tract bacterial and viral infections, as well as inflammatory complications that may eventually lead to pulmonary failure. Immune cells play a crucial role in protecting the organs against opportunistic infections and also in the regulation of tissue homeostasis. Innate immune cells are generally affected by CFTR mutations in patients with CF, leading to dysregulation of several cellular signalling pathways that are in continuous use by these cells to elicit a proper immune response. There is substantial evidence to show that airway epithelial cells, neutrophils, monocytes and macrophages all contribute to the pathogenesis of CF, underlying the importance of the CFTR in innate immune responses. The goal of this review is to put into context the important role of the CFTR in different innate immune cells and how CFTR dysfunction contributes to the pathogenesis of CF, highlighting several signalling pathways that may be dysregulated in cells with CFTR mutations.

Airway cholinergic history modifies mucus secretion properties to subsequent cholinergic challenge in diminished chloride and bicarbonate conditions

NEW FINDINGS

What is the central question of this study? What is the impact of airway cholinergic history on the properties of airway mucus secretion in a cystic fibrosis-like environment? What is the main finding and its importance? Prior cholinergic challenge slightly modifies the characteristics of mucus secretion in response to a second cholinergic challenge in a diminished bicarbonate and chloride transport environment. Such modifications might lead to retention of mucus on the airway surface, thereby potentiating exacerbations of airway disease.

ABSTRACT

Viral infections precipitate exacerbations in many airway diseases, including asthma and cystic fibrosis. Although viral infections increase cholinergic transmission, few studies have examined how cholinergic history modifies subsequent cholinergic responses in the airway. In our previous work, we found that airway resistance in response to a second cholinergic challenge was increased in young pigs with a history of airway cholinergic stimulation. Given that mucus secretion is regulated by the cholinergic nervous system and that abnormal airway mucus contributes to exacerbations of airway disease, we hypothesized that prior cholinergic challenge would also modify subsequent mucus responses to a secondary cholinergic challenge. Using our established cholinergic challenge-rechallenge model in pigs, we atomized the cholinergic agonist bethanechol or saline control to pig airways. Forty-eight hours later, we removed tracheas and measured mucus secretion properties in response to a second cholinergic stimulation. The second cholinergic stimulation was conducted in conditions of diminished chloride and bicarbonate transport to mimic a cystic fibrosis-like environment. In pigs previously challenged with bethanechol, a second cholinergic stimulation produced a mild increase in sheet-like mucus films; these films were scarcely observed in animals originally challenged with saline control. The subtle increase in mucus films was not associated with changes in mucociliary transport. These data suggest that prior cholinergic history might modify mucus secretion characteristics with subsequent stimulation in certain environmental conditions or disease states. Such modifications and/or more repetitive stimulation might lead to retention of mucus on the airway surface, thereby potentiating exacerbations of airway disease.

Rhinovirus Infection Drives Complex Host Airway Molecular Responses in Children With Cystic Fibrosis

Early-life viral infections are responsible for pulmonary exacerbations that can contribute to disease progression in young children with cystic fibrosis (CF). The most common respiratory viruses detected in the CF airway are human rhinoviruses (RV), and augmented airway inflammation in CF has been attributed to dysregulated airway epithelial responses although evidence has been conflicting. Here, we exposed airway epithelial cells from children with and without CF to RV in vitro. Using RNA-Seq, we profiled the transcriptomic differences of CF and non-CF airway epithelial cells at baseline and in response to RV. There were only modest differences between CF and non-CF cells at baseline. In response to RV, there were 1,442 and 896 differentially expressed genes in CF and non-CF airway epithelial cells, respectively. The core antiviral responses in CF and non-CF airway epithelial cells were mediated through interferon signaling although type 1 and 3 interferon signaling, when measured, were reduced in CF airway epithelial cells following viral challenge consistent with previous reports. The transcriptional responses in CF airway epithelial cells were more complex than in non-CF airway epithelial cells with diverse over-represented biological pathways, such as cytokine signaling and metabolic and biosynthetic pathways. Network analysis highlighted that the differentially expressed genes of CF airway epithelial cells' transcriptional responses were highly interconnected and formed a more complex network than observed in non-CF airway epithelial cells. We corroborate observations in fully differentiated air–liquid interface (ALI) cultures, identifying genes involved in IL-1 signaling and mucin glycosylation that are only dysregulated in the CF airway epithelial response to RV infection. These data provide novel insights into the CF airway epithelial cells' responses to RV infection and highlight potential pathways that could be targeted to improve antiviral and anti-inflammatory responses in CF.

Ivacaftor or lumacaftor/ivacaftor treatment does not alter the core CF airway epithelial gene response to rhinovirus

BACKGROUND

Aberrant responses by the cystic fibrosis airway epithelium during viral infection may underly the clinical observations. Whether CFTR modulators affect antiviral responses by CF epithelia is presently unknown. We tested the hypothesis that treatment of CF epithelial cells with ivacaftor (Iva) or ivacaftor/lumacaftor (Iva/Lum) would improve control of rhinovirus infection.

METHODS

Nineteen CF epithelial cultures (10 homozygous for p.Phe508del as CFTR Class 2, 9 p.Phe508del/p.Gly551Asp as Class 3) were infected with rhinovirus 1B at multiplicity of infection 12 for 24 h. Culture RNA and supernatants were harvested to assess gene and protein expression respectively.

RESULTS

RNA-seq analysis comparing rhinovirus infected cultures to control identified 796 and 629 differentially expressed genes for Class 2 and Class 3, respectively. This gene response was highly conserved when cells were treated with CFTR modulators and were predicted to be driven by the same interferon-pathway transcriptional regulators (IFNA, IFNL1, IFNG, IRF7, STAT1). Direct comparisons between treated and untreated infected cultures did not yield any differentially expressed genes for Class 3 and only 68 genes for Class 2. Changes were predominantly related to regulators of lipid metabolism and inflammation, aspects of epithelial biology known to be dysregulated in CF. In addition, CFTR modulators did not affect viral copy number, or levels of pro-inflammatory cytokines produced post-infection.

CONCLUSIONS

Though long-term clinical data is not yet available, results presented here suggest that first generation CFTR modulators do not interfere with core airway epithelial responses to rhinovirus infection. Future work should investigate the latest triple modulation therapies.

Rhinovirus Infection Is Associated With Airway Epithelial Cell Necrosis and Inflammation via Interleukin-1 in Young Children With Cystic Fibrosis

Introduction: The responses of cystic fibrosis (CF) airway epithelial cells (AEC) to rhinovirus (RV) infection are likely to contribute to early pathobiology of lung disease with increased neutrophilic inflammation and lower apoptosis reported. Necrosis of AEC resulting in airway inflammation driven by IL-1 signaling is a characteristic finding in CF detectable in airways of young children. Being the most common early-life infection, RV-induced epithelial necrosis may contribute to early neutrophilic inflammation in CF via IL-1 signaling. As little is known about IL-1 and biology of CF lung disease, this study assessed cellular and pro-inflammatory responses of CF and non-CF AEC following RV infection, with the hypothesis that RV infection drives epithelial necrosis and IL-1 driven inflammation. Methods:Primary AEC obtained from children with (n = 6) and without CF (n = 6) were infected with RV (MOI 3) for 24 h and viable, necrotic and apoptotic events quantified via flow cytometry using a seven-step gating strategy (% total events). IL-1α, IL-1β, IL-1Ra, IL-8, CXCL10, CCL5, IFN-β, IL-28A, IL-28B, and IL-29 were also measured in cell culture supernatants (pg/mL). Results:RV infection reduced viable events in non-CF AEC (p < 0.05), increased necrotic events in non-CF and CF AEC (p < 0.05) and increased apoptotic events in non-CF AEC (p < 0.05). Infection induced IL-1α and IL-1β production in both phenotypes (p < 0.05) but only correlated with necrosis (IL-1α: r = 0.80; IL-1β: r = 0.77; p < 0.0001) in CF AEC. RV infection also increased IL-1Ra in non-CF and CF AEC (p < 0.05), although significantly more in non-CF AEC (p < 0.05). Finally, infection stimulated IL-8 production in non-CF and CF AEC (p < 0.05) and correlated with IL-1α (r = 0.63 & r = 0.74 respectively; p < 0.0001). Conclusions:This study found RV infection drives necrotic cell death in CF AEC. Furthermore, RV induced IL-1 strongly correlated with necrotic cell death in these cells. As IL-1R signaling drives airway neutrophilia and mucin production, these observations suggest RV infection early in life may exacerbate inflammation and mucin accumulation driving early CF lung disease. Since IL-1R can be targeted therapeutically with IL-1Ra, these data suggest a new anti-inflammatory therapeutic approach targeting downstream effects of IL-1R signaling to mitigate viral-induced, muco-inflammatory triggers of early lung disease.

Progress in Model Systems of Cystic Fibrosis Mucosal Inflammation to Understand Aberrant Neutrophil Activity

In response to recurrent infection in cystic fibrosis (CF), powerful innate immune signals trigger polymorphonuclear neutrophil recruitment into the airway lumen. Exaggerated neutrophil proteolytic activity results in sustained inflammation and scarring of the airways. Consequently, neutrophils and their secretions are reliable clinical biomarkers of lung disease progression. As neutrophils are required to clear infection and yet a direct cause of airway damage, modulating adverse neutrophil activity while preserving their pathogen fighting function remains a key area of CF research. The factors that drive their pathological behavior are still under investigation, especially in early disease when aberrant neutrophil behavior first becomes evident. Here we examine the latest findings of neutrophils in pediatric CF lung disease and proposed mechanisms of their pathogenicity. Highlighted in this review are current and emerging experimental methods for assessing CF mucosal immunity and human neutrophil function in the laboratory.

Airway Surface Liquid Has Innate Antiviral Activity That Is Reduced in Cystic Fibrosis

Although chronic bacterial infections and inflammation are associated with progressive lung disease in patients with cystic fibrosis (CF), much less is known regarding the contributions of respiratory viral infections to this process. Clinical studies suggest that antiviral host defenses may be compromised in individuals with CF, and CF airway epithelia exhibit impaired antiviral responses in vitro. Here, we used the CF pig model to test the hypothesis that the antiviral activity of respiratory secretions is reduced in CF. We developed an in vitro assay to measure the innate antiviral activity present in airway surface liquid (ASL) from CF and non-CF pigs. We found that tracheal and nasal ASL from newborn non-CF pigs exhibited dose-dependent inhibitory activity against several enveloped and encapsidated viruses, including Sendai virus, respiratory syncytial virus, influenza A, and adenovirus. Importantly, we found that the anti-Sendai virus activity of nasal ASL from newborn CF pigs was significantly diminished relative to non-CF littermate controls. This diminution of extracellular antiviral defenses appears to be driven, at least in part, by the differences in pH between CF and non-CF ASL. These data highlight the novel antiviral properties of native airway secretions and suggest the possibility that defects in extracellular antiviral defenses contribute to CF pathogenesis.

Preterm birth: Born too soon for the developing airway epithelium?

Birth prior to term interrupts the normal development of the respiratory system and consequently results in poor respiratory outcomes that persist throughout childhood. The mechanisms underpinning these poor respiratory outcomes are not well understood, but intrinsic abnormalities within the airway epithelium may be a contributing factor. Current evidence suggests that the airway epithelium is both structurally and functionally abnormal after preterm birth, with reports of epithelial thickening and goblet cell hyperplasia in addition to increased inflammation and apoptosis in the neonatal intensive care unit. However, studies focusing on the airway epithelium are limited and many questions remain unanswered; including whether abnormalities are a direct result of interrupted development, a consequence of exposure to inflammatory stimuli in the perinatal period or a combination of the two. In addition, the difficulty of accessing airway tissue has resulted in the majority of evidence being collected in the pre-surfactant era which may not reflect contemporary preterm birth. This review examines the consequences of preterm birth on the airway epithelium and explores the clinical relevance of currently available models whilst highlighting the need to develop a clinically relevant in vitro model to help further our understanding of the airway epithelium in preterm birth.

Azithromycin reduces airway inflammation induced by human rhinovirus in lung allograft recipients

BACKGROUND AND OBJECTIVE

Human rhinovirus (RV) is a common upper and lower respiratory pathogen in lung allograft recipients causing respiratory tract exacerbation and contributing towards allograft dysfunction and long-term lung decline. In this study, we tested the hypothesis that RV could infect both the small and large airways, resulting in significant inflammation.

METHODS

Matched large and small airway epithelial cells (AEC) were obtained from five lung allograft recipients. Primary cultures were established, and monolayers were infected with RV1b over time with varying viral titre. Cell viability, receptor expression, viral copy number, apoptotic induction and inflammatory cytokine production were also assessed at each region. Finally, the effect of azithromycin on viral replication, induction of apoptosis and inflammation was investigated.

RESULTS

RV infection caused significant cytotoxicity in both large AEC (LAEC) and small AEC (SAEC), and induced a similar apoptotic response in both regions. There was a significant increase in receptor expression in the LAEC only post viral infection. Viral replication was elevated in both LAEC and SAEC, but was not significantly different. Prophylactic treatment of azithromycin reduced viral replication and dampened the production of inflammatory cytokines post-infection.

CONCLUSION

Our data illustrate that RV infection is capable of infecting upper and lower AEC, driving cell death and inflammation. Prophylactic treatment with azithromycin was found to mitigate some of the detrimental responses. Findings provide further support for the prophylactic prescription of azithromycin to minimize the impact of RV infection.

Airway microenvironment alterations and pathogen growth in cystic fibrosis

Cystic Fibrosis Transmembrane Regulator (CFTR) dysfunction is associated with epithelial cell vulnerability and with dysregulation of the local inflammatory responses resulting in excessive airway neutrophilic inflammation and pathogen growth. In combination with impaired mucociliary clearance, and dysregulation of defense function, bacterial infection follows with eventual airway damage and remodeling. Because of these inherent vulnerabilities, viral infections are also more severe and prolonged and appear to render the airway even more prone to bacterial infection. Airway acidity, deficient nitric oxide production and increased iron concentrations, further enhance the airway milieu's susceptibility to infection. Novel diagnostic techniques of the airway microbiome elucidate the coexistence of an array of non-virulent taxa beyond the recognized virulent organisms, predominantly Pseudomonas aeruginosa. The complex interplay between these two bacterial populations, including upregulation of virulence genes and utilization of mucin as a nutrient source, modulates the action of pathogens, modifies the CF airway milieu and contributes to the processes leading to airway derangement. The review provides an update on recent advances of the complex mechanisms that render the CF airway vulnerable to inflammation, infection and ultimately structural damage, the key pathogenetic elements of CF. The recent contributions on CF pathogenesis will hopefully help in identifying new prophylactic measures and therapeutic targets for this highly destructive disorder.

Exacerbations of chronic respiratory diseases

Respiratory viral infections including human rhinovirus (RV) infection have been identified as the most important environmental trigger of exacerbations of chronic lung diseases. While well established as the most common viral infections associated with exacerbations of asthma and chronic obstructive pulmonary disease, RVs and other respiratory viruses are also now thought to be important in triggering exacerbations of cystic fibrosis and the interstitial lung diseases. Here, we summarize the epidemiological evidence the supports respiratory viruses including RV as triggers of exacerbations of chronic lung diseases. We propose that certain characteristics of RVs may explain why they are the most common trigger of exacerbations of chronic lung diseases. We further highlight the latest mechanistic evidence supporting how and why common respiratory viral infections may enhance and promote disease triggering exacerbation events, through their interactions with the host immune system, and may be affected by ongoing treatments. We also provide a commentary on how new treatments may better manage the disease burden associated with respiratory viral infections and the exacerbation events that they trigger.

Modulation of the unfolded protein response pathway as an antiviral approach in airway epithelial cells

INTRODUCTION

Rhinovirus (RV) infection is a major cause of cystic fibrosis (CF) lung morbidity with limited therapeutic options. Various diseases involving chronic inflammatory response and infection are associated with endoplasmic reticulum (ER) stress and subsequent activation of the unfolded protein response (UPR), an adaptive response to maintain cellular homeostasis. Recent evidence suggests impaired ER stress response in CF airway epithelial cells, this might be a reason for recurrent viral infection in CF. Therefore, assuming that ER stress inducing drugs have antiviral properties, we evaluated the activation of the UPR by selected ER stress inducers as an approach to control virus replication in the CF bronchial epithelium.

METHODS

We assessed the levels of UPR markers, namely the glucose-regulated protein 78 (Grp78) and the C/EBP homologous protein (CHOP), in primary CF and control bronchial epithelial cells and in a CF and control bronchial epithelial cell line before and after infection with RV. The cells were also pretreated with ER stress-inducing drugs and RV replication and shedding was measured by quantitative RT-PCR and by a TCID₅₀ assay, respectively. Cell death was assessed by a lactate dehydrogenate (LDH) activity test in supernatants.

RESULTS

We observed a significantly impaired induction of Grp78 and CHOP in CF compare to control cells following RV infection. The ER stress response could be significantly induced in CF cells by pharmacological ER stress inducers Brefeldin A, Tunicamycin, and Thapsigargin. The chemical induction of the UPR pathway prior to RV infection of CF and control cells reduced viral replication and shedding by up to two orders of magnitude and protected cells from RV-induced cell death.

CONCLUSION

RV infection causes an impaired activation of the UPR in CF cells. Rescue of the ER stress response by chemical ER stress inducers reduced significantly RV replication in CF cells. Thus, pharmacological modulation of the UPR might represent a strategy to control respiratory virus replication in the CF bronchial epithelium.

Use of a Primary Epithelial Cell Screening Tool to Investigate Phage Therapy in Cystic Fibrosis

Antimicrobial-resistant microbes are an increasing threat to human health. In cystic fibrosis (CF), airway infections with Pseudomonas aeruginosa remain a key driver of lung damage. With few new antibiotics on the development horizon, alternative therapeutic approaches are needed against antimicrobial-resistant pathogens. Phage therapy, or the use of viruses that infect bacteria, is one proposed novel therapy to treat bacterial infections. However, the airways are complex microenvironments with unique characteristics that may affect the success of novel therapies. Here, three phages of P. aeruginosa (E79, F116, and one novel clinically derived isolate, designated P5) were screened for activity against 21 P. aeruginosa strains isolated from children with CF. Of these, phage E79 showed broad antibacterial activity (91% of tested strains sensitive) and was selected for further assessment. E79 genomic DNA was extracted, sequenced, and confirmed to contain no bacterial pathogenicity genes. High titre phage preparations were then purified using ion-exchange column chromatography and depleted of bacterial endotoxin. Primary airway epithelial cells derived from children with CF (n = 8, age range 0.2–5.5 years, 5 males) or healthy non-CF controls (n = 8, age range 2.5–4.0 years, 4 males) were then exposed to purified phage for 48 h. Levels of inflammatory IL-1β, IL-6, and IL-8 cytokine production were measured in culture supernatant by immunoassays and the extent of cellular apoptosis was measured using a ssDNA kit. Cytokine and apoptosis levels were compared between E79-stimulated and unstimulated controls, and, encouragingly, purified preparations of E79 did not stimulate any significant inflammatory cytokine responses or induce apoptosis in primary epithelial cells derived from children with or without CF. Collectively, this study demonstrates the feasibility of utilizing pre-clinical in vitro culture models to screen therapeutic candidates, and the potential of E79 as a therapeutic phage candidate in CF.

Elucidating the Interaction of CF Airway Epithelial Cells and Rhinovirus: Using the Host-Pathogen Relationship to Identify Future Therapeutic Strategies

Chronic lung disease remains the primary cause of mortality in cystic fibrosis (CF). Growing evidence suggests respiratory viral infections are often more severe in CF compared to healthy peers and contributes to pulmonary exacerbations (PEx) and deterioration of lung function. Rhinovirus is the most prevalent respiratory virus detected, particularly during exacerbations in children with CF <5 years old. However, even though rhinoviral infections are likely to be one of the factors initiating the onset of CF lung disease, there is no effective targeted treatment. A better understanding of the innate immune responses by CF airway epithelial cells, the primary site of infection for viruses, is needed to identify why viral infections are more severe in CF. The aim of this review is to present the clinical impact of virus infection in both young children and adults with CF, focusing on rhinovirus infection. Previous in vitro and in vivo investigations looking at the mechanisms behind virus infection will also be summarized. The review will finish on the potential of transcriptomics to elucidate the host-pathogen responses by CF airway cells to viral infection and identify novel therapeutic targets.

The role of noncoding RNAs in regulating epithelial responses in COPD

Chronic obstructive pulmonary disease (COPD), one of the leading causes of death in the world, is a chronic inflammatory disease of the airways usually caused by long-term exposure to inhaled irritants. Airway epithelial cells (AECs) play a key role in initializing COPD and driving the exacerbation of this disease through the release of various cytokines. This AEC-derived cytokine response is tightly regulated possibly through the regulatory effects of noncoding RNAs (ncRNAs). Although the importance of ncRNAs in pulmonary diseases has been increasingly realized, little is known about the role of ncRNA in the regulation of inflammatory responses in COPD. This review outlines the features of AEC-derived cytokine responses in COPD and how ncRNAs regulate these inflammatory responses.

Effects of human rhinovirus on epithelial barrier integrity and function in children with asthma

BACKGROUND

Bronchial epithelial tight junctions (TJ) have been extensively assessed in healthy airway epithelium. However, no studies have yet assessed the effect of human rhinovirus (HRV) infection on the expression and resultant barrier function in epithelial tight junctions (TJ) in childhood asthma.

OBJECTIVES

To investigate the impact of HRV infection on airway epithelial TJ expression and barrier function in airway epithelial cells (AECs) of children with and without asthma. Furthermore, to test the hypothesis that barrier integrity and function is compromised to a greater extent by HRV in AECs from asthmatic children.

METHODS

Primary AECs were obtained from children with and without asthma, differentiated into air-liquid interface (ALI) cultures and infected with rhinovirus. Expression of claudin-1, occludin and zonula occluden-1 (ZO-1) was assessed via qPCR, immunocytochemistry (ICC), in-cell western (ICW) and confocal microscopy. Barrier function was assessed by transepithelial electrical resistance (TER; R_T ) and permeability to fluorescent dextran.

RESULTS

Basal TJ gene expression of claudin-1 and occludin was significantly upregulated in asthmatic children compared to non-asthmatics; however, no difference was seen with ZO-1. Interestingly, claudin-1, occludin and ZO-1 protein expression was significantly reduced in AEC of asthmatic children compared to non-asthmatic controls suggesting possible post-transcriptional inherent differences. HRV infection resulted in a transient dissociation of TJ and airway barrier integrity in non-asthmatic children. Although similar dissociation of TJ was observed in asthmatic children, a significant and sustained reduction in TJ expression concurrent with both a significant decrease in TER and an increase in permeability in asthmatic children was observed.

CONCLUSION

This study demonstrates novel intrinsic differences in TJ gene and protein expression between AEC of children with and without asthma. Furthermore, it correlates directly the relationship between HRV infection and the resultant dissociation of epithelial TJ that causes a continued altered barrier function in children with asthma.

Assessment of p.Phe508del-CFTR functional restoration in pediatric primary cystic fibrosis airway epithelial cells

BACKGROUND

Mutations in the cystic fibrosis transmembrane regulator (CFTR) gene can reduce function of the CFTR ion channel activity and impair cellular chloride secretion. The gold standard method to assess CFTR function of ion transport using the Ussing chamber requires a high number of airway epithelial cells grown at air-liquid interface, limiting the application of this method for high throughput screening of potential therapeutic compounds in primary airway epithelial cells (pAECs) featuring less common CFTR mutations. This study assessed an alternative approach, using a small scale halide assay that can be adapted for a personalized high throughput setting to analyze CFTR function of pAEC.

METHODS

Pediatric pAECs derived from children with CF (pAECCF) were established and expanded as monolayer cultures, before seeding into 96-well plates for the halide assay. Cells were then transduced with an adenoviral construct containing yellow fluorescent protein (eYFP) reporter gene, alone or in combination with either wild-type CFTR (WT-CFTR) or p.Phe508del CFTR. Four days post transduction, cells were stimulated with forskolin and genistein, and assessed for quenching of the eYFP signal following injection of iodide solution into the assay media.

RESULTS

Data showed that pAECCF can express eYFP at high efficiency following transduction with the eYFP construct. The halide assay was able to discriminate functional restoration of CFTR in pAECCF treated with either WT-CFTR construct or the positive controls syntaxin 8 and B-cell receptor-associated protein 31 shRNAs.

SIGNIFICANCE

The current study demonstrates that the halide assay can be adapted for pediatric pAECCF to evaluate restoration of CFTR function. With the ongoing development of small molecules to modulate the folding and/or activity of various mutated CFTR proteins, this halide assay presents a small-scale personalized screening platform that could assess therapeutic potential of molecules across a broad range of CFTR mutations.

Conditionally reprogrammed primary airway epithelial cells maintain morphology, lineage and disease specific functional characteristics

Current limitations to primary cell expansion led us to test whether airway epithelial cells derived from healthy children and those with asthma and cystic fibrosis (CF), co-cultured with an irradiated fibroblast feeder cell in F-medium containing 10 µM ROCK inhibitor could maintain their lineage during expansion and whether this is influenced by underlying disease status. Here, we show that conditionally reprogrammed airway epithelial cells (CRAECs) can be established from both healthy and diseased phenotypes. CRAECs can be expanded, cryopreserved and maintain phenotypes over at least 5 passages. Population doublings of CRAEC cultures were significantly greater than standard cultures, but maintained their lineage characteristics. CRAECs from all phenotypes were also capable of fully differentiating at air-liquid interface (ALI) and maintained disease specific characteristics including; defective CFTR channel function cultures and the inability to repair wounds. Our findings indicate that CRAECs derived from children maintain lineage, phenotypic and importantly disease-specific functional characteristics over a specified passage range.

The AREST CF experience in biobanking - More than just tissues, tubes and time

Research to further improve outcomes for people with CF is dependent upon well characterised, archived and accessible clinical specimens. The recent article by Beekman et al. published in Journal of Cystic Fibrosis summarised a scientific meeting at the 13th ECFS Basic Science Conference. This meeting discussed how well-annotated, clinical biobanks for CF could be established in Europe to meet the needs of therapeutic development. The Australian Respiratory Early Surveillance Team for Cystic Fibrosis (AREST CF) has conducted biobanking of CF research and clinical specimens since the late 1990s and is custodian of the most comprehensive paediatric CF biobank in the world that focuses on the first years of life. This short communication will describe the approach undertaken by AREST CF in establishing a clinical specimen biobank.

The potential of phage therapy in cystic fibrosis: Essential human-bacterial-phage interactions and delivery considerations for use in Pseudomonas aeruginosa-infected airways

As antimicrobial-resistant microbes become increasingly common and a significant global issue, novel approaches to treating these infections particularly in those at high risk are required. This is evident in people with cystic fibrosis (CF), who suffer from chronic airway infection caused by antibiotic resistant bacteria, typically Pseudomonas aeruginosa. One option is bacteriophage (phage) therapy, which utilises the natural predation of phage viruses upon their host bacteria. This review summarises the essential and unique aspects of the phage-microbe-human lung interactions in CF that must be addressed to successfully develop and deliver phage to CF airways. The current evidence regarding phage biology, phage-bacterial interactions, potential airway immune responses to phages, previous use of phages in humans and method of phage delivery to the lung are also summarised.

Viral interference and the live-attenuated intranasal influenza vaccine: Results from a pediatric cohort with cystic fibrosis

BACKGROUND

The objective of this study was to explore the effects of viral co-detection in individuals recently vaccinated with the live-attenuated intranasal influenza virus vaccine (LAIV) on the detection of influenza RNA.

METHODS

Before the 2013-2014 influenza season, nasal swabs were obtained from 59 pediatric participants with cystic fibrosis (CF) and 17 of their healthy siblings immediately before vaccination and 4 times during the week of follow-up. Real-time RT-PCR assays were used to detect influenza RNA. Co-detection of a non-influenza respiratory virus (NIRV) at the time of vaccination was determined by a multiplex RT-PCR assay. Differences in the proportions and rates of influenza detection and their 95% credible intervals (CrI) were estimated.

RESULTS

Influenza RNA was detected in 16% fewer participants (95% CrI: -7, 39%) throughout follow-up in the NIRV-positive group compared with the NIRV-negative group (59% vs. 75%). This was also observed in participants with CF alone (66% vs. 74%; RD = 8% 95% CrI: -16, 33%) as well as in healthy participants only (75% vs. 30%; RD = 45%, 95% CrI: -2, 81%). Influenza was detected in NIRV-negative subjects for 0.49 d more compared with NIRV-positive subjects (95% CrI: -0.37, 1.26).

CONCLUSION

The observed proportion of subjects in whom influenza RNA was detected and the duration of detection differed slightly between NIRV- positive and -negative subjects. However, wide credible intervals for the difference preclude definitive conclusions. If true, this observed association may be related to a recent viral respiratory infection, a phenomenon known as viral interference.

Viruses in cystic fibrosis patients' airways

Although bacteria have historically been considered to play a major role in cystic fibrosis (CF) airway damage, a strong impact of respiratory viral infections (RVI) is also now recognized. Emerging evidence confirms that respiratory viruses are associated with deterioration of pulmonary function and exacerbation and facilitation of bacterial colonization in CF patients. The aim of this review is to provide an overview of the current knowledge on respiratory viruses in CF airways, to discuss the resulting inflammation and RVI response, to determine how to detect the viruses, and to assess their clinical consequences, prevalence, and interactions with bacteria. The most predominant are Rhinoviruses (RVs), significantly associated with CF exacerbation. Molecular techniques, and especially multiplex PCR, help to diagnose viral infections, and the coming rise of metagenomics will extend knowledge of viral populations in the complex ecosystem of CF airways. Prophylaxis and vaccination are currently available only for Respiratory syncytial and Influenza virus (IV), but antiviral molecules are being tested to improve CF patients' care. All the points raised in this review highlight the importance of taking account of RVIs and their potential impact on the CF airway ecosystem.

Neutrophil plasticity enables the development of pathological microenvironments: implications for cystic fibrosis airway disease

INTRODUCTION

The pathological course of several chronic inflammatory diseases, including cystic fibrosis, chronic obstructive pulmonary disease, and rheumatoid arthritis, features an aberrant innate immune response dominated by neutrophils. In cystic fibrosis, neutrophil burden and activity of neutrophil elastase in the extracellular fluid have been identified as strong predictors of lung disease severity.

REVIEW

Although neutrophils are generally considered to be rigid, pre-programmed effector leukocytes, recent studies suggest extensive plasticity in how neutrophil functions unfold upon recruitment to peripheral tissues, and how they choose their ultimate fate. Indeed, upon migration to cystic fibrosis airways, neutrophils display dysregulated lifespan, metabolic activation, and altered effector and regulatory functions, consistent with profound adaptation and phenotypic reprogramming. Licensed by signals present in cystic fibrosis airway microenvironment to survive and develop these novel functions, neutrophils orchestrate, in partnership with the epithelium and with the resident microbiota, the evolution of a pathological microenvironment. This microenvironment is defined by altered proteolytic, redox, and metabolic balance and the presence of stable luminal structures in which neutrophils and microbes coexist.

CONCLUSIONS

The elucidation of molecular mechanisms driving neutrophil plasticity in vivo will open new treatment opportunities designed to modulate, rather than block, the crucial adaptive functions fulfilled by neutrophils. This review aims to outline emerging mechanisms of neutrophil plasticity and their participation in the building of pathological microenvironments in the context of cystic fibrosis and other diseases with similar features.

Effect of human rhinovirus infection on airway epithelium tight junction protein disassembly and transepithelial permeability

RATIONALE

No studies have assessed the effects of human rhinovirus (HRV) infection on epithelial tight junctions (TJs) and resultant barrier function.

AIM OF THE STUDY

To correlate viral infection with TJ disassembly, epithelial barrier integrity, and function.

MATERIALS AND METHODS

Human airway epithelial cells were infected with HRV minor serotype 1B (HRV-1B) at various 50% tissue culture infectivity doses (TCID₅₀) over 72 hours. HRV replication was assessed by quantitative-polymerase chain reaction (qPCR) while cell viability and apoptosis were assessed by proliferation and apoptotic assays, respectively. Protein expression of claudin-1, occludin, and zonula occludens protein-1 (ZO-1) was assessed using In-Cell™ Western assays. Transepithelial permeability assays were performed to assess effects on barrier functionality. RT² Profiler focused qPCR arrays and pathway analysis evaluating associations between human TJ and antiviral response were performed to identify potential interactions and pathways between genes of interests.

RESULTS

HRV-1B infection affected viability that was both time and TCID₅₀ dependent. Significant increases in apoptosis and viral replication post-infection correlated with viral titer. Viral infection significantly decreased claudin-1 protein expression at the lower TCID₅₀, while a significant decrease in all three TJ protein expressions occurred at higher TCID₅₀. Decrease in protein expression was concomitant with significant increases in epithelial permeability of fluorescein isothiocynate labeled-dextran 4 and 20 kDa. Analysis of focused qPCR arrays demonstrated a significant decrease in ZO-1 gene expression. Furthermore, network analysis between human TJ and antiviral response genes revealed possible interactions and regulation of TJ genes via interleukin (IL)-15 in response to HRV-1B infection.

CONCLUSION

HRV-1B infection directly alters human airway epithelial TJ expression leading to increased epithelial permeability potentially via an antiviral response of IL-15.

Pulmonary Exacerbations in Children with Cystic Fibrosis

Pulmonary exacerbations treated with intravenous antibiotics have significant, well-characterized negative consequences on clinical outcomes in cystic fibrosis (CF). The impact of milder exacerbations in children with CF, commonly treated with oral antibiotics, are less well defined. Pulmonary exacerbations have multiple triggers, but viral infections are particularly common in children. Children with CF and healthy control subjects have similar frequencies of viral respiratory infections, but there is evidence of greater virus-related morbidity in patients with CF, likely due to a combination of increased viral load, more pronounced inflammatory response, and more pronounced impairment in mucociliary clearance. In recent clinical trials in children, definitions have been used that are more symptom based rather than intervention based. These studies have demonstrated differences in the spectrum of symptoms between children and older patients but have also shown that, despite low threshold definitions, a considerable number of patients receive treatment for events not fulfilling the pulmonary exacerbation criteria. Additional research is needed to determine the impact of these milder exacerbations on lung function recovery and time to subsequent exacerbation as well as long-term outcomes such as mortality.

Influenza Virus Detection Following Administration of Live-Attenuated Intranasal Influenza Vaccine in Children With Cystic Fibrosis and Their Healthy Siblings

Background.  We aimed to explore the detection profile of influenza viruses following live-attenuated intranasal influenza vaccination (LAIV) in children aged 2-19 years with and without cystic fibrosis (CF). Methods.  Before the 2013-2014 influenza season, flocked nasal swabs were obtained before vaccination and 4 times in the week of follow-up from 76 participants (n_CF: 57; n_healthy: 19). Influenza was detected by reverse transcription polymerase chain reaction (RT-PCR) assays. A Bayesian hierarchical logistic regression model was used to estimate the effect of CF status and age on influenza detection. Results.  Overall, 69% of the study cohort shed influenza RNA during follow-up. The mean duration of RT-PCR detection was 2.09 days (95% credible interval [CrI]: 1.73-2.48). The odds of influenza RNA detection on day 1 following vaccination decreased with age in years (odds ratio [OR]: 0.82 per year; 95% CrI: 0.70-0.95), and subjects with CF had higher odds of influenza RNA detection on day 1 of follow-up (OR: 5.09; 95% CrI: 1.02-29.9). Conclusion.  Despite the small sample size, our results indicate that LAIV vaccine strains are detectable during the week after LAIV, mainly in younger individuals and vaccinees with CF. It remains unclear whether recommendations for avoiding contact with severely immunocompromised patients should differ for these groups.

Alpha-1 Antitrypsin Mitigates the Inhibition of Airway Epithelial Cell Repair by Neutrophil Elastase

Neutrophil elastase (NE) activity is associated with many destructive lung diseases and is a predictor for structural lung damage in early cystic fibrosis (CF), which suggests normal maintenance of airway epithelium is prevented by uninhibited NE. However, limited data exist on how the NE activity in airways of very young children with CF affects function of the epithelia. The aim of this study was to determine if NE activity could inhibit epithelial homeostasis and repair and whether any functional effect was reversible by antiprotease alpha-1 antitrypsin (α1AT) treatment. Viability, inflammation, apoptosis, and proliferation were assessed in healthy non-CF and CF pediatric primary airway epithelial cells (pAECnon-CF and pAECCF, respectively) during exposure to physiologically relevant NE. The effect of NE activity on pAECCF wound repair was also assessed. We report that viability after 48 hours was significantly decreased by 100 nM NE in pAECnon-CF and pAECCF owing to rapid cellular detachment that was accompanied by inflammatory cytokine release. Furthermore, both phenotypes initiated an apoptotic response to 100 nM NE, whereas ≥ 50 nM NE activity significantly inhibited the proliferative capacity of cultures. Similar concentrations of NE also significantly inhibited wound repair of pAECCF, but this effect was reversed by the addition of α1AT. Collectively, our results demonstrate free NE activity is deleterious for epithelial homeostasis and support the hypothesis that proteases in the airway contribute directly to CF structural lung disease. Our results also highlight the need to investigate antiprotease therapies in early CF disease in more detail.

Impaired airway epithelial cell responses from children with asthma to rhinoviral infection

BACKGROUND

The airway epithelium forms an effective immune and physical barrier that is essential for protecting the lung from potentially harmful inhaled stimuli including viruses. Human rhinovirus (HRV) infection is a known trigger of asthma exacerbations, although the mechanism by which this occurs is not fully understood.

OBJECTIVE

To explore the relationship between apoptotic, innate immune and inflammatory responses to HRV infection in airway epithelial cells (AECs) obtained from children with asthma and non-asthmatic controls. In addition, to test the hypothesis that aberrant repair of epithelium from asthmatics is further dysregulated by HRV infection.

METHODS

Airway epithelial brushings were obtained from 39 asthmatic and 36 non-asthmatic children. Primary cultures were established and exposed to HRV1b and HRV14. Virus receptor number, virus replication and progeny release were determined. Epithelial cell apoptosis, IFN-β production, inflammatory cytokine release and epithelial wound repair and proliferation were also measured.

RESULTS

Virus proliferation and release was greater in airway epithelial cells from asthmatics but this was not related to the number of virus receptors. In epithelial cells from asthmatic children, virus infection dampened apoptosis, reduced IFN-β production and increased inflammatory cytokine production. HRV1b infection also inhibited wound repair capacity of epithelial cells isolated from non-asthmatic children and exaggerated the defective repair response seen in epithelial cells from asthmatics. Addition of IFN-β restored apoptosis, suppressed virus replication and improved repair of airway epithelial cells from asthmatics but did not reduce inflammatory cytokine production.

CONCLUSIONS

Collectively, HRV infection delays repair and inhibits apoptotic processes in epithelial cells from non-asthmatic and asthmatic children. The delayed repair is further exaggerated in cells from asthmatic children and is only partially reversed by exogenous IFN-β.

Digging through the Obstruction: Insight into the Epithelial Cell Response to Respiratory Virus Infection in Patients with Cystic Fibrosis

Respiratory virus infections are common but generally self-limiting infections in healthy individuals. Although early clinical studies reported low detection rates, the development of molecular diagnostic techniques by PCR has led to an increased recognition that respiratory virus infections are associated with morbidity and acute exacerbations of chronic lung diseases, such as cystic fibrosis (CF). The airway epithelium is the first barrier encountered by respiratory viruses following inhalation and the primary site of respiratory viral replication. Here, we describe how the airway epithelial response to respiratory viral infections contributes to disease progression in patients with CF and other chronic lung diseases, including the role respiratory viral infections play in bacterial acquisition in the CF patient lung.

Rhinovirus-associated pulmonary exacerbations show a lack of FEV1 improvement in children with cystic fibrosis

BACKGROUND

Respiratory viral infections lead to bronchial inflammation in patients with cystic fibrosis, especially during pulmonary exacerbations. The aim of this study was to determine the impact of viral-associated pulmonary exacerbations in children with cystic fibrosis and failure to improve forced expiratory volume in 1 s (FEV1 ) after an appropriate treatment.

METHODS

We lead a pilot study from January 2009 until March 2013. Children with a diagnosis of cystic fibrosis were longitudinally evaluated three times: at baseline (Visit 1), at the diagnosis of pulmonary exacerbation (Visit 2), and after exacerbation treatment (Visit 3). Nasal and bronchial samples were analyzed at each visit with multiplex viral respiratory PCR panel (qualitative detection of 16 viruses). Pulmonary function tests were recorded at each visit, in order to highlight a possible failure to improve them after treatment. Lack of improvement was defined by an increase in FEV1 less than 5% between Visit 2 and Visit 3.

RESULTS

Eighteen children were analyzed in the study. 10 patients failed to improve by more than 5% their FEV1 between Visit 2 and Visit 3. Rhinovirus infection at Visit 2 or Visit 3 was the only risk factor significantly associated with such a failure (OR, 12; 95% CI, 1·3-111·3), P = 0·03.

CONCLUSIONS

Rhinovirus infection seems to play a role in the FEV1 recovery after pulmonary exacerbation treatment in children with cystic fibrosis. Such an association needs to be confirmed by a large-scale study because this finding may have important implications for pulmonary exacerbation management.

Airway epithelial repair in health and disease: Orchestrator or simply a player?

Epithelial cells represent the most important surface of contact in the body and form the first line of defence of the body to external environment. Consequently, epithelia have numerous roles in order to maintain a homeostatic defence barrier. Although the epithelium has been extensively studied over several decades, it remains the focus of new research, indicating a lack of understanding that continues to exist around these cells in specific disease settings. Importantly, evidence is emerging that airway epithelial cells in particular have varied complex functions rather than simple passive roles. One area of current interest is its role following injury. In particular, the epithelial-specific cellular mechanisms regulating their migration during wound repair remain poorly understood and remain an area that requires much needed investigation. A better understanding of the physiological, cellular and molecular wound repair mechanisms could assist in elucidating pathological processes that contribute to airway epithelial pathology. This review attempts to highlight migration-specific and cell-extracellular matrix (ECM) aspects of repair used by epithelial cells under normal and disease settings, in the context of human airways.

Biodiesel exhaust-induced cytotoxicity and proinflammatory mediator production in human airway epithelial cells

Increasing use of biodiesel has prompted research into the potential health effects of biodiesel exhaust exposure. Few studies directly compare the health consequences of mineral diesel, biodiesel, or blend exhaust exposures. Here, we exposed human epithelial cell cultures to diluted exhaust generated by the combustion of Australian ultralow-sulfur-diesel (ULSD), unprocessed canola oil, 100% canola biodiesel (B100), and a blend of 20% canola biodiesel mixed with 80% ULSD. The physicochemical characteristics of the exhaust were assessed and we compared cellular viability, apoptosis, and levels of interleukin (IL)-6, IL-8, and Regulated on Activation, Normal T cell Expressed and Secreted (RANTES) in exposed cultured cells. Different fuel types produced significantly different amounts of exhaust gases and different particle characteristics. All exposures resulted in significant apoptosis and loss of viability when compared with control, with an increasing proportion of biodiesel being correlated with a decrease in viability. In most cases, exposure to exhaust resulted in an increase in mediator production, with the greatest increases most often in response to B100. Exposure to pure canola oil (PCO) exhaust did not increase mediator production, but resulted in a significant decrease in IL-8 and RANTES in some cases. Our results show that canola biodiesel exhaust exposure elicits inflammation and reduces viability of human epithelial cell cultures in vitro when compared with ULSD exhaust exposure. This may be related to an increase in particle surface area and number in B100 exhaust when compared with ULSD exhaust. Exposure to PCO exhaust elicited the greatest loss of cellular viability, but virtually no inflammatory response, likely due to an overall increase in average particle size.

Rhinovirus Load Is High despite Preserved Interferon-β Response in Cystic Fibrosis Bronchial Epithelial Cells

Lung disease in cystic fibrosis (CF) is often exacerbated following acute upper respiratory tract infections caused by the human rhinovirus (HRV). Pathophysiology of these exacerbations is presently unclear and may involve deficient innate antiviral or exaggerated inflammatory responses in CF airway epithelial cells. Furthermore, responses of CF cells to HRV may be adversely affected by pre-exposure to virulence factors of Pseudomonas (P.) aeruginosa, the microorganism that frequently colonizes CF airways. Here we examined production of antiviral cytokine interferon-β and inflammatory chemokine interleukin-8, expression of the interferon-responsive antiviral gene 2'-5'-oligoadenylate synthetase 1 (OAS1), and intracellular virus RNA load in primary CF (delF508 CFTR) and healthy airway epithelial cells following inoculation with HRV16. Parallel cells were exposed to virulence factors of P. aeruginosa prior to and during HRV16 inoculation. CF cells exhibited production of interferon-β and interleukin-8, and expression of OAS1 at levels comparable to those in healthy cells, yet significantly higher HRV16 RNA load during early hours post-inoculation with HRV16. In line with this, HRV16 RNA load was higher in the CFBE41o- dF cell line overexpessing delF508 CFTR, compared with the isogenic control CFBE41o- WT (wild-type CFTR). Pre-exposure to virulence factors of P. aeruginosa did not affect OAS1 expression or HRV16 RNA load, but potentiated interleukin-8 production. In conclusion, CF cells demonstrate elevated HRV RNA load despite preserved interferon-β and OAS1 responses. High HRV load in CF airway epithelial cells appears to be due to deficiencies manifesting early during HRV infection, and may not be related to interferon-β.