A systematic review of antimicrobial therapy in children with tracheostomies

Tracheostomies are indicated in children to facilitate long-term ventilatory support, aid in the management of secretions, or manage upper airway obstruction. Children with tracheostomies often experience ongoing airway complications, of which respiratory tract infections are common. They subsequently receive frequent courses of broad-spectrum antimicrobials for the prevention or treatment of respiratory tract infections. However, there is little consensus in practice with regard to the indication for treatment/prophylactic antimicrobial use, choice of antimicrobial, route of administration, or duration of treatment between different centers. Routine antibiotic use is associated with adverse effects and an increased risk of antimicrobial resistance. Tracheal cultures are commonly obtained from pediatric tracheostomy patients, with the aim of helping guide antimicrobial therapy choice. However, a positive culture alone is not diagnostic of infection and the role of routine surveillance cultures remains contentious. Inhaled antimicrobial use is also widespread in the management of tracheostomy-associated infections; this is largely based on the theoretical benefits of higher airway antibiotic concentrations. The role of prophylactic inhaled antimicrobial use for tracheostomy-associated infections remains largely unproven. This systematic review summarizes the current evidence base for antimicrobial selection, duration, and administration route in pediatric tracheostomy-associated infections. It also highlights significant variation in practice between centers and the urgent need for further prospective evidence to guide the management of these vulnerable patients.

Unsupervised home spirometry is not equivalent to supervised clinic spirometry in children and young people with cystic fibrosis: Results from the CLIMB-CF study

BACKGROUND

Handheld spirometry allows monitoring of lung function at home, of particular importance during the COVID-19 pandemic. Pediatric studies are unclear on whether values are interchangeable with traditional, clinic-based spirometry. We aimed to assess differences between contemporaneous, home (unsupervised) and clinic (supervised) spirometry and the variability of the former. The accuracy of the commercially available spirometer used in the study was also tested.

METHODS

Data from participants in the Clinical Monitoring and Biomarkers to stratify severity and predict outcomes in children with cystic fibrosisc (CLIMB-CF) Study aged ≥ 6 years who had paired (±1 day) clinic and home forced expiratory volume in 1 s (FEV1 ) readings were analyzed. Variability during clinical stability over 6-months was assessed. Four devices from Vitalograph were tested using 1 and 3 L calibration syringes.

RESULTS

Sixty-seven participants (median [interquartile range] age 10.7 [7.6-13.9] years) provided home and clinic FEV1 data pairs. The mean (SD) FEV1 % bias was 6.5% [±8.2%]) with wide limits of agreement (-9.6% to +22.7%); 76.2% of participants recorded lower results at home. Coefficient of variation of home FEV1 % during stable periods was 9.9%. Data from the testing of the handheld device used in CLIMB-CF showed a potential underread.

CONCLUSION

In children and adolescents, home spirometry using hand-held equipment cannot be used interchangeably with clinic spirometry. Home spirometry is moderately variable during clinical stability. New handheld devices underread, particularly at lower volumes of potential clinical significance for smaller patients; this suggests that supervision does not account fully for the discrepancy. Opportunities should be taken to obtain dual device measurements in clinic, so that trend data from home can be utilized more accurately.

Tracheostomy in children is associated with neutrophilic airway inflammation

BACKGROUND

Tracheostomies in children are associated with significant morbidity, poor quality of life, excess healthcare costs and excess mortality. The underlying mechanisms facilitating adverse respiratory outcomes in tracheostomised children are poorly understood. We aimed to characterise airway host defence in tracheostomised children using serial molecular analyses.

METHODS

Tracheal aspirates, tracheal cytology brushings and nasal swabs were prospectively collected from children with a tracheostomy and controls. Transcriptomic, proteomic and metabolomic methods were applied to characterise the impact of tracheostomy on host immune response and the airway microbiome.

RESULTS

Children followed up serially from the time of tracheostomy up to 3 months postprocedure (n=9) were studied. A further cohort of children with a long-term tracheostomy were also enrolled (n=24). Controls (n=13) comprised children without a tracheostomy undergoing bronchoscopy. Long-term tracheostomy was associated with airway neutrophilic inflammation, superoxide production and evidence of proteolysis when compared with controls. Reduced airway microbial diversity was established pre-tracheostomy and sustained thereafter.

CONCLUSIONS

Long-term childhood tracheostomy is associated with a inflammatory tracheal phenotype characterised by neutrophilic inflammation and the ongoing presence of potential respiratory pathogens. These findings suggest neutrophil recruitment and activation as potential exploratory targets in seeking to prevent recurrent airway complications in this vulnerable group of patients.

Automatic oxygen control for reducing extremes of oxygen saturation: a randomised controlled trial

OBJECTIVE

The objective of this study was to evaluate the efficacy of the automatic oxygen control (A-Fio₂) in reducing the percentage of time spent in severe hypoxaemia (Spo₂ <80%) in preterm infants for the time period on invasive ventilation and/or nasal continuous positive airway pressure (NCPAP) delivered by AVEA ventilator.

DESIGN

A parallel arm randomised controlled trial.

SETTING

A level-III neonatal intensive care unit.

PATIENTS

Preterm infants (<33 weeks birth gestation) who received invasive ventilation or NCPAP in the first 72 hours of age.

INTERVENTIONS

A-Fio₂ vs manual (M-Fio₂) oxygen control.

OUTCOMES

The primary outcome of the study was percentage of time spent in severe hypoxaemia (Spo₂ <80%).

RESULTS

44 infants were randomised to either A-Fio₂ or M-Fio₂ arm and continued in the study for the period of respiratory support (invasive ventilation and/or NCPAP). The total number of study days in A-Fio2 and M-Fio₂ arm were 194 and 204 days, respectively. The percentage of time spent in Spo₂ <80% was significantly lower with A-Fio₂ compared with M-Fio₂ (median of 0.1% (IQR: 0.07-0.7) vs 0.6% (0.2-2); p=0.03). The number of prolonged episodes (>60 s) of Spo₂ <80% per day was also significantly lower in A-Fio₂ (0.3 (0.0-2) vs 2 (0.6-6); p=0.02).

CONCLUSION

A-Fio₂ was associated with statistically significant reduction in the percentage of time spent in severe hypoxaemia when compared with M-Fio₂ in preterm infants receiving respiratory support.

TRIAL REGISTRATION NUMBER

NCT04223258.

Providing care for children with tracheostomies: a qualitative interview study with parents and health professionals

OBJECTIVES

To explore the experience of caring for children with tracheostomies from the perspectives of parents and health professional caregivers.

DESIGN

Qualitative semistructured interview study.

SETTING

One region in England covered by a tertiary care centre that includes urban and remote rural areas and has a high level of deprivation.

PARTICIPANTS

A purposive sample of health professionals and parents who care for children who have, or have had, tracheostomies and who received care at the tertiary care centre.

INTERVENTION

Interviews undertaken by telephone or video link.

PRIMARY AND SECONDARY OUTCOME MEASURES

Qualitative reflexive thematic analysis with QSR Nvivo 12.

RESULTS

This paper outlines key determinants and mediators of the experiences of caregiving and the impact on psychological and physical health and quality of life of parents and their families, confidence of healthcare providers and perceived quality of care. For parents, access to care packages and respite care at home as well as communication and relationships with healthcare providers are key mediators of their experience of caregiving, whereas for health professionals, an essential influence is multidisciplinary team working and support. We also highlight a range of challenges focused on the shared care space, including: a lack of standardisation in access to different support teams, care packages and respite care, irregular training and updates, and differences in health provider expertise and experiences across departments and shift patterns, exacerbated in some settings by limited contact with children with tracheostomies.

CONCLUSIONS

Understanding the experiences of caregiving can help inform measures to support caregivers and improve quality standards. Our findings suggest there is a need to facilitate further standardisation of care and support available for parent caregivers and that this may be transferable to other regions. Potential solutions to be explored could include the development of a paediatric tracheostomy service specification, increasing use of paediatric tracheostomy specialist nurse roles, and addressing the emotional and psychological support needs of caregivers.

Protocol for CLASSIC PBB: comparison of lower airway sampling strategies in children with protracted bacterial bronchitis

BACKGROUND

Protracted bacterial bronchitis (PBB) is an endobronchial infection and a the most common cause of chronic wet cough in young children. It is treated with antibiotics, which can only be targeted if the causative organism is known. As most affected children do not expectorate sputum, lower airway samples can only be obtained by bronchoalveolar lavage (BAL) samples taken during flexible bronchoscopy (FB-BAL). This is invasive and is therefore reserved for children with severe or relapsing cases. Most children with PBB are treated empirically with broad spectrum antibiotics. CLASSIC PBB will compare the pathogen yield from two less invasive strategies with that from FB-BAL to see if they are comparable.

METHODS

131 children with PBB from four UK centres referred FB-BAL will be recruited. When attending for FB-BAL, they will have a cough swab and an induced sputum sample obtained. The primary outcome will be the discordance of the pathogen yield from the cough swab and the induced sputum when compared with FB-BAL. Secondary outcomes will be the sensitivity of each sampling strategy, the success rate of the induced sputum in producing a usable sample and the tolerability of each of the three sampling strategies.

DISCUSSION

If either or both of the two less invasive airway sampling strategies are shown to be a useful alternative to FB-BAL, this will lead to more children with PBB having lower airway samples enabling targeted antibiotic prescribing. It would also reduce the need for FB, which is known to be burdensome for children and their families.

TRIAL REGISTRATION NUMBER

ISRCTN79883982.

Diaphragm electrical activity during weaning of nasal high-flow therapy in preterm infants

OBJECTIVE

To determine whether electrical activity of the diaphragm (Edi) changes with weaning nasal high-flow (HF) therapy in preterm infants according to a standardised protocol.

DESIGN

Prospective observational cohort study.

SETTING

Neonatal intensive care unit.

PATIENTS

Preterm infants born at <32 weeks gestation, receiving nasal HF as part of routine clinical care.

INTERVENTIONS

Infants recruited to the study had their HF weaned according to set clinical criteria. Edi was measured using a modified gastric feeding tube serially from baseline (pre-wean) to 24-hours post-wean.

MAIN OUTCOME MEASURES

Change in Edi from baseline was measured at four time points up to 24 hours after weaning. Minimum Edi during expiration, maximum Edi during inspiration and amplitude of the Edi signal (Edi_delta) were measured. Clinical parameters (heart rate, respiratory rate and fraction of inspired oxygen) were also recorded.

RESULTS

Forty preterm infants were recruited at a mean corrected gestational age of 31.6 (±2.7) weeks. Data from 156 weaning steps were analysed, 91% of which were successful. Edi did not change significantly from baseline during flow reduction steps, but a significant increase in diaphragm activity was observed when discontinuing HF (median increase in Edi_delta immediately post-discontinuation 1.7 µV (95% CI: 0.6 to 3.0)) and at 24 hours 1.9 µV (95% CI: 0.7 to 3.8)). No significant difference in diaphragm activity was observed between successful and unsuccessful weaning steps.

CONCLUSIONS

A protocolised approach to weaning has a high probability of success. Edi does not change with reducing HF rate, but significantly increases with discontinuation of HF from 2 L/min.

Exploring the impact of elexacaftor-tezacaftor-ivacaftor treatment on opinions regarding airway clearance techniques and nebulisers: TEMPO a qualitative study in children with cystic fibrosis, their families and healthcare professionals

Background

Cystic fibrosis (CF) is a genetic condition caused by variants in the cystic fibrosis transmembrane conductance regulator (CFTR) gene that primarily impacts the lungs. Treatments historically have been symptomatic to improve airway clearance and treat infection. However, CFTR modulator drugs have recently been developed that target the underlying defect. The triple combination of elexacaftor-tezacaftor-ivacaftor (ETI) was approved in 2020 in England for over 80% of people with CF aged over 12 years and in 2022 extended to those over 6 years. ETI treatment is associated with substantial improvements in lung function. The experience of children with CF starting on ETI or their views regarding future treatments have not been well studied. This study aimed to explore the opinions of children with CF, their parents/carers and healthcare professionals (HCPs) on the impact of ETI, airway clearance techniques (ACTs) and nebulised treatments.

Methods

Semistructured qualitative interviews were performed with 10 children with CF, 7 parents/carers and 10 HCPs. Audio recordings were transcribed and analysed using reflexive thematic analysis.

Results

Four main themes were identified: ‘Kaftrio changed my life’, ‘Your entire life is dictated by the CF timetable’, ‘Simplifying treatment-hopes and fears’ and ‘Kaftrio is a game-changer’ along with several subthemes and an overarching theme of ‘I still can’t get my head around how three tablets can do what Kaftrio done’.

Conclusions

Despite the highly positive impact of ETI on the health of children with CF some concerns remain about the longer-term outcomes of reducing ACTs or nebulised treatments. ETI has prompted a shift in treatment for many and offers an opportunity to personalise approaches.

Elexacaftor-Tezacaftor-Ivacaftor improve Gastro-Oesophageal reflux and Sinonasal symptoms in advanced cystic fibrosis

Upper gastrointestinal and upper airway disease are common in cystic fibrosis (CF) and may contribute to lower airway infection and inflammation. In a longitudinal cohort study of 32 patients (23 men; median age 32.5 years) with advanced CF lung disease (median FEV₁ 24.8% predicted) starting elexacaftor-tezacaftor-ivacaftor, the reflux symptom index score fell from a pre-treatment median (IQR) of 15 (11-23) to 5 (2.8-7.3) (p<0.001), the Hull airway reflux score fell from a median of 26.5 (16.3-39) to 7.5 (4-12) (p<0.001), and the sinonasal outcome score from a median of 36.5 (22-24) to 20 (10-32) (p<0.001) at 6 months on treatment. Mean FEV₁% predicted rose by 9.2 points, the median respiratory domain score of the CF Questionnaire-Revised rose by 27.8 points and mean body mass index rose by 2.6 kg/m². In addition to improving lung function and weight, CFTR modulators improve upper airway and gastro-oesophageal reflux symptoms in advanced CF.

National Cohort Study of Health Care Resource Use After Pediatric Tracheostomy

This cohort study uses Hospital Episode Statistics admission data to evaluate hospital resource use and associated costs for pediatric tracheostomy.

Conjunctival epithelial cells resist productive SARS-CoV-2 infection

Conjunctival epithelial cells, which express viral-entry receptors angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine type 2 (TMPRSS2), constitute the largest exposed epithelium of the ocular surface tissue and may represent a relevant viral-entry route. To address this question, we generated an organotypic air-liquid-interface model of conjunctival epithelium, composed of basal, suprabasal, and superficial epithelial cells, and fibroblasts, which could be maintained successfully up to day 75 of differentiation. Using single-cell RNA sequencing (RNA-seq), with complementary imaging and virological assays, we observed that while all conjunctival cell types were permissive to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genome expression, a productive infection did not ensue. The early innate immune response to SARS-CoV-2 infection in conjunctival cells was characterised by a robust autocrine and paracrine NF-κB activity, without activation of antiviral interferon signalling. Collectively, these data enrich our understanding of SARS-CoV-2 infection at the human ocular surface, with potential implications for the design of preventive strategies and conjunctival transplantation.

Exposure to bile and gastric juice can impact the aerodigestive microbiome in people with cystic fibrosis

Studies of microbiota reveal inter-relationships between the microbiomes of the gut and lungs. This relationship may influence the progression of lung disease, particularly in patients with cystic fibrosis (CF), who often experience extraoesophageal reflux (EOR). Despite identifying this relationship, it is not well characterised. Our hypothesis is that the gastric and lung microbiomes in CF are related, with the potential for aerodigestive pathophysiology. We evaluated gastric and sputum bacterial communities by culture and 16S rRNA gene sequencing in 13 CF patients. Impacts of varying levels of bile acids, pepsin and pH on patient isolates of Pseudomonas aeruginosa (Pa) were evaluated. Clonally related strains of Pa and NTM were identified in gastric and sputum samples from patients with symptoms of EOR. Bacterial diversity was more pronounced in sputa compared to gastric juice. Gastric and lung bile and pepsin levels were associated with Pa biofilm formation. Analysis of the aerodigestive microbiomes of CF patients with negative sputa indicates that the gut can be a reservoir of Pa and NTM. This combined with the CF patient's symptoms of reflux and potential aspiration, highlights the possibility of communication between microorganisms of the gut and the lungs. This phenomenon merits further research.

Treating nontuberculous mycobacteria in children with cystic fibrosis: a multicentre retrospective study

BACKGROUND

Respiratory infection with nontuberculous mycobacteria (NTM) in children with cystic fibrosis (CF) has increased in prevalence. The condition is difficult to diagnose and treatments are complex with limited evidence to guide practice. This study describes the approaches to diagnosis, management and consequences of treatment in a multicentre cohort of children with CF in the UK.

METHODS

Retrospective data were collected from 11 CF specialist centres from patients less than 17 years old, treated for NTM infection between 2006 and 2017. Descriptive statistics were used to describe the clinical characteristics of children treated. Treatment regimens, adverse events and success of treatment, with respect to lung function and culture conversion, were evaluated.

RESULTS

Data from 70 patients treated for NTM pulmonary disease were collated (60 Mycobacterium abscessus complex (MABSC); 10 M. avium complex (MAC)). Older age and previous diagnosis of allergic bronchopulmonary aspergillosis were all significantly associated with NTM. There was a wide variance in drug choice and side effects were reported with all agents. NTM eradication occurred in 80% of patients with MAC and 48% with MABSC, with variable outcomes on lung function.

CONCLUSIONS

Diagnosis and treatment of NTM infection in children with CF is challenging. Treatment success is not guaranteed, particularly for MABSC. Large clinical trials are urgently required to evaluate treatment regimes and their suitability and efficacy in children.

Diagnosis and management of asthma in children

Asthma is the the most common chronic respiratory condition of childhood worldwide, with around 14% of children and young people affected. Despite the high prevalence, paediatric asthma outcomes are inadequate, and there are several avoidable deaths each year. Characteristic asthma features include wheeze, shortness of breath and cough, which are typically triggered by a number of possible stimuli. There are several diagnostic challenges, and as a result, both overdiagnosis and underdiagnosis of paediatric asthma remain problematic.Effective asthma management involves a holistic approach addressing both pharmacological and non-pharmacological management, as well as education and self-management aspects. Working in partnership with children and families is key in promoting good outcomes. Education on how to take treatment effectively, trigger avoidance, modifiable risk factors and actions to take during acute attacks via personalised asthma action plans is essential.This review aimed to provide an overview of good clinical practice in the diagnosis and management of paediatric asthma. We discuss the current diagnostic challenges and predictors of life-threatening attacks. Additionally, we outline the similarities and differences in global paediatric asthma guidelines and highlight potential future developments in care. It is hoped that this review will be useful for healthcare providers working in a range of child health settings.

Impact of COVID-19 on carers of children with tracheostomies

OBJECTIVES

To explore the impact of the COVID-19 pandemic on the experiences of caregivers of children with tracheostomies.

DESIGN

Qualitative semistructured interviews.

SETTING

All participants were currently, or had previously cared for, a tracheostomised child who had attended a tertiary care centre in the North of England. Health professionals were purposively sampled to include accounts from a range of professions from primary, community, secondary and tertiary care.

PARTICIPANTS

Carers of children with tracheostomies (n=34), including health professionals (n=17) and parents (n=17).

INTERVENTIONS

Interviews were undertaken between July 2020 and February 2021 by telephone or video link.

MAIN OUTCOME MEASURE

Qualitative reflexive thematic analysis with QSR NVivo V.12.

RESULTS

The pandemic has presented an additional and, for some, substantial challenge when caring for tracheostomised children, but this was not always felt to be the most overriding concern. Interviews demonstrated rapid adaptation, normalisation and varying degrees of stoicism and citizenship around constantly changing pandemic-related requirements, rules and regulations. This paper focuses on four key themes: 'reconceptualising safe care and safe places'; 'disrupted support and isolation'; 'relationships, trust and communication'; and 'coping with uncertainty and shifting boundaries of responsibility'. These are described within the context of the impact on the child, the emotional and physical well-being of carers and the challenges to maintaining the values of family-centred care.

CONCLUSIONS

As we move to the next phase of the pandemic, we need to understand the impact on vulnerable groups so that their needs can be prioritised.

Precision Medicine Based on CFTR Genotype for People with Cystic Fibrosis

Cystic fibrosis (CF) is an autosomal recessive genetic condition that is caused by variants in the cystic fibrosis transmembrane conductance regulator gene. This causes multisystem disease due to dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) ion channel at the apical surface of epithelia. Until recently, treatment was directed at managing the downstream effects in affected organs, principally improving airway clearance and treating infection in the lungs and improving malabsorption in the gastrointestinal tract. Care delivered by multidisciplinary teams has yielded incremental improvements in outcomes. However, the development of small-molecule CFTR modulator drugs over the last decade has heralded a new era of CF therapeutics. Modulators target the underlying defect and improve CFTR function. Either monotherapy or a combination of modulators is used depending on the specific genotype and class of CFTR disease-causing variants that an individual has. Both ivacaftor and the ivacaftor/tezacaftor/elexacaftor combination have been demonstrated to be associated with clinically very significant benefits in randomised trials and have rapidly been made available as part of standard care in many countries. CFTR modulators represent one of the best examples of precision medicine to date. They are expensive, however, and equity of access to them worldwide remains an issue. Studies and approvals are also ongoing for children under the age of 6 years for ivacaftor/tezacaftor/elexacaftor. Furthermore, no modulators are available for around 10% of the people with CF. In this review, we firstly summarise the genetics, pathophysiology and clinical problems associated with CF. We then discuss the development of CFTR modulators and key clinical trials to support their use along with other potential future therapeutic approaches.

Characterising the allergic profile of children with cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) is a genetic condition that affects multiple organ systems. Allergic bronchopulmonary aspergillosis (ABPA) is a well-recognised problem but other allergic conditions are less well documented in CF.

OBJECTIVE

To characterise the allergic profile of a cohort of children with CF, with a focus on those with ABPA.

METHODS

A cohort of children with CF were interviewed and retrospective data were collected regarding their allergic histories and other relevant clinical features.

RESULTS

The cohort included 37 children with median age of 9 years (interquartile range: 6-12). There was a history of ≥1 allergic condition(s) in 28/37 children (76%). The most common allergic condition was allergic rhinitis (AR) in 21/37 (57%) and 16 of these 21 children (76%) had another allergic condition. All children with ABPA (8) had another allergic condition. In some children ABPA exacerbations appeared to be seasonal, suggesting possible cross-sensitisation between Aspergillus fumigatus and aeroallergens associated with seasonal AR. Allergic conditions were also common in children with Pseudomonas aeruginosa infection.

Delayed induction of type I and III interferons mediates nasal epithelial cell permissiveness to SARS-CoV-2

The nasal epithelium is a plausible entry point for SARS-CoV-2, a site of pathogenesis and transmission, and may initiate the host response to SARS-CoV-2. Antiviral interferon (IFN) responses are critical to outcome of SARS-CoV-2. Yet little is known about the interaction between SARS-CoV-2 and innate immunity in this tissue. Here we apply single-cell RNA sequencing and proteomics to a primary cell model of human nasal epithelium differentiated at air-liquid interface. SARS-CoV-2 demonstrates widespread tropism for nasal epithelial cell types. The host response is dominated by type I and III IFNs and interferon-stimulated gene products. This response is notably delayed in onset relative to viral gene expression and compared to other respiratory viruses. Nevertheless, once established, the paracrine IFN response begins to impact on SARS-CoV-2 replication. When provided prior to infection, recombinant IFNβ or IFNλ1 induces an efficient antiviral state that potently restricts SARS-CoV-2 viral replication, preserving epithelial barrier integrity. These data imply that the IFN-I/III response to SARS-CoV-2 initiates in the nasal airway and suggest nasal delivery of recombinant IFNs to be a potential chemoprophylactic strategy.

Tracheostomy trends in paediatric intensive care

Paediatric tracheostomy is most commonly performed in children on the paediatric intensive care unit (PICU) to facilitate long-term ventilation. We sought to identify trends in UK tracheostomy practice in PICUs. Data were analysed from 250 261 admissions, including 4409 children tracheostomised between 2003 and 2017. The incidence of tracheostomy in 2017 was approximately half that in 2003 (incidence rate ratio=0.48, 95% CI 0.40 to 0.57). The percentage of patients tracheostomised during a PICU admission, as a proportion of all admissions, was 2.44% (n=319) in 2003 and reduced to 0.97% (n=180) in 2017. Nevertheless, we identified great variability in practice between different PICUs with tracheostomy rates between 0.0% and 4.0% of all admissions. Risk-adjusted PICU mortality was comparable between tracheostomised children and all admissions to PICU.

Acute cigarette smoke or extract exposure rapidly activates TRPA1-mediated calcium influx in primary human airway smooth muscle cells

Tobacco smoking is the largest risk factor for developing chronic obstructive pulmonary disease (COPD), and is associated with hyperresponsiveness of airway smooth muscle (ASM). Chronic exposure to cigarette smoke (CS) leads to airway inflammation and remodelling. However, the direct effect of gaseous CS or CS extract (CSE) on human airway smooth muscle cell (hASMC) function remains poorly understood. This study investigated the acute effect of CS/CSE on calcium homeostasis, a key regulator of ASM physiology and pathophysiology. Primary hASMC were isolated from non-smoking donor lungs, and subjected to Ca2+ imaging studies. We found that both CS, and CSE, rapidly elevated cytosolic Ca2+ in hASMC through stimulation of plasmalemmal Ca2+ influx, but excluded store-operated and L-type Ca2+ channels as mediators of this effect. Using a specific pharmacological inhibitor, or shRNA-driven knockdown, we established that both CS and CSE stimulated Ca2+ influx in hASMC through the neurogenic pain receptor channel, transient receptor potential ankyrin 1 (TRPA1). CS/CSE-dependent, TRPA1-mediated Ca2+ influx led to myosin light-chain phosphorylation, a key process regulating ASM contractility. We conclude that TRPA1 is likely an important link between CS/CSE exposure and airway hyperresponsiveness, and speculate that acute CS/CSE-induced Ca2+ influx could lead to exacerbated ASM contraction and potentially initiate further chronic pathological effects of tobacco smoke.

Lung biopsy in children: when is it useful?

AIM

To provide a further insight into the usefulness of lung biopsy in children.

METHODS

Lung biopsies in children from January 2007 to December 2017 were reviewed (n=39). The histology results were categorised as: definitive diagnosis, normal lung parenchyma, inconclusive.

RESULTS

Lung biopsy provided a definitive diagnosis in 25 (64%) cases. A suspected diagnosis was confirmed in 16 (41%) and a new diagnosis was found in 9 (23%) children. Histology was inconclusive in 11 (28%) cases and normal in 3 (8%). Fifteen (38%) children had treatment altered due to the biopsy result.

CONCLUSION

Lung biopsy mostly confirmed the suspected diagnosis and was associated with a low procedure related morbidity (n=1) and mortality (n=0). Importantly, the biopsy result identified a pathology which altered treatment in over one third of patients. However, in a number of cases the histology was inconclusive, therefore careful patient selection is recommended to maximise diagnostic yield.

Interferon regulatory factor 8 regulates expression of acid ceramidase and infection susceptibility in cystic fibrosis

Most patients with cystic fibrosis (CF) suffer from acute and chronic pulmonary infections with bacterial pathogens, which often determine their life quality and expectancy. Previous studies have demonstrated a downregulation of the acid ceramidase in CF epithelial cells resulting in an increase of ceramide and a decrease of sphingosine. Sphingosine kills many bacterial pathogens, and the downregulation of sphingosine seems to determine the infection susceptibility of cystic fibrosis mice and patients. It is presently unknown how deficiency of the cystic fibrosis transmembrane conductance regulator (CFTR) connects to a marked downregulation of the acid ceramidase in human and murine CF epithelial cells. Here, we employed quantitative PCR, western blot analysis, and enzyme activity measurements to study the role of IRF8 for acid ceramidase regulation. We report that genetic deficiency or functional inhibition of CFTR/Cftr results in an upregulation of interferon regulatory factor 8 (IRF8) and a concomitant downregulation of acid ceramidase expression with CF and an increase of ceramide and a reduction of sphingosine levels in tracheal and bronchial epithelial cells from both human individuals or mice. CRISPR/Cas9- or siRNA-mediated downregulation of IRF8 prevented changes of acid ceramidase, ceramide, and sphingosine in CF epithelial cells and restored resistance to Pseudomonas aeruginosa infections, which is one of the most important and common pathogens in lung infection of patients with CF. These studies indicate that CFTR deficiency causes a downregulation of acid ceramidase via upregulation of IRF8, which is a central pathway to control infection susceptibility of CF cells.

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.

Clinical and molecular characterization of the R751L-CFTR mutation

Cystic fibrosis (CF) arises from mutations in the CF transmembrane conductance regulator (CFTR) gene, resulting in progressive and life-limiting respiratory disease. R751L is a rare CFTR mutation that is poorly characterized. Our aims were to describe the clinical and molecular phenotypes associated with R751L. Relevant clinical data were collected from three heterozygote individuals harboring R751L (2 patients with G551D/R751L and 1 with F508del/R751L). Assessment of R751L-CFTR function was made in primary human bronchial epithelial cultures (HBEs) and Xenopus oocytes. Molecular properties of R751L-CFTR were investigated in the presence of known CFTR modulators. Although sweat chloride was elevated in all three patients, the clinical phenotype associated with R751L was mild. Chloride secretion in F508del/R751L HBEs was reduced compared with non-CF HBEs and associated with a reduction in sodium absorption by the epithelial sodium channel (ENaC). However, R751L-CFTR function in Xenopus oocytes, together with folding and cell surface transport of R751L-CFTR, was not different from wild-type CFTR. Overall, R751L-CFTR was associated with reduced sodium chloride absorption but had functional properties similar to wild-type CFTR. This is the first report of R751L-CFTR that combines clinical phenotype with characterization of functional and biological properties of the mutant channel. Our work will build upon existing knowledge of mutations within this region of CFTR and, importantly, inform approaches for clinical management. Elevated sweat chloride and reduced chloride secretion in HBEs may be due to alternative non-CFTR factors, which require further investigation.

Transplantation for congenital heart disease is associated with an increased risk of Epstein-Barr virus-related post-transplant lymphoproliferative disorder in children

BACKGROUND

Children undergoing heart transplant are at higher risk of developing post-transplant lymphoproliferative disorder (PTLD) than other solid organ recipients. The factors driving that risk are unclear. This study investigated risk factors for PTLD in children transplanted at 1 of 2 United Kingdom pediatric cardiac transplantation centers.

METHODS

All children (<18 years, n = 200) transplanted at our institution over a 16-year period were analyzed. Freedom from PTLD was assessed using the Kaplan-Meier method and Cox proportional regression.

RESULTS

PTLD occurred in 17 of 71 children transplanted for congenital heart disease (CHD) and 18 of 129 transplanted for acquired cardiomyopathy (ACM). The cumulative incidence of all PTLD was 21.1% at 5 years after transplant. Median time from transplant to PTLD was 2.9 years (interquartile range: 0.9-4.6). Negative Epstein-Barr virus (EBV) serostatus pre-transplant (adjusted hazard ratio [HR]: 2.7, 95% CI: 1.3-5.6, p = 0.01) and underlying CHD (adjusted HR: 3.2, 95% CI: 1.4-7.4, p = 0.007) were independently associated with higher risk of PTLD. Age at thymectomy was significantly different between children with CHD and ACM (0.4 vs 5.5 years, p < 0.01). Median CD4⁺ and CD8⁺ T lymphocyte counts at 2 years after transplant were significantly lower in children transplanted for CHD vs ACM (CD4⁺: 391/µl vs 644/µl, p = 0.01; CD8⁺: 382/µl vs 500/µl, p = 0.01). At 5 years after transplant, those differences persisted among patients who developed PTLD (CD4⁺, 430/µl vs 963/µl, p < 0.01 and CD8⁺, 367/µl vs 765/µl, p < 0.01).

CONCLUSION

Underlying CHD is an independent risk factor for PTLD and is associated with a younger age at thymectomy. A persistent association with altered T lymphocyte subsets may contribute to the impaired response to primary EBV infection and increase the risk of PTLD.

Recombinant Acid Ceramidase Reduces Inflammation and Infection in Cystic Fibrosis

Rationale: In cystic fibrosis the major cause of morbidity and mortality is lung disease characterized by inflammation and infection. The influence of sphingolipid metabolism is poorly understood with a lack of studies using human airway model systems.Objectives: To investigate sphingolipid metabolism in cystic fibrosis and the effects of treatment with recombinant human acid ceramidase on inflammation and infection.Methods: Sphingolipids were measured using mass spectrometry in fully differentiated cultures of primary human airway epithelial cells and cocultures with Pseudomonas aeruginosa. In situ activity assays, Western blotting, and quantitative PCR were used to investigate function and expression of ceramidase and sphingomyelinase. Effects of treatment with recombinant human acid ceramidase on sphingolipid profile and inflammatory mediator production were assessed in cell cultures and murine models.Measurements and Main Results: Ceramide is increased in cystic fibrosis airway epithelium owing to differential function of enzymes regulating sphingolipid metabolism. Sphingosine, a metabolite of ceramide with antimicrobial properties, is not upregulated in response to P. aeruginosa by cystic fibrosis airway epithelia. Tumor necrosis factor receptor 1 is increased in cystic fibrosis epithelia and activates NF-κB signaling, generating inflammation. Treatment with recombinant human acid ceramidase, to decrease ceramide, reduced both inflammatory mediator production and susceptibility to infection.Conclusions: Sphingolipid metabolism is altered in airway epithelial cells cultured from people with cystic fibrosis. Treatment with recombinant acid ceramidase ameliorates the two pivotal features of cystic fibrosis lung disease, inflammation and infection, and thus represents a therapeutic approach worthy of further exploration.

Trends in nontuberculous mycobacteria infection in children and young people with cystic fibrosis

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NTM infection in children with CF is a major clinical concern and challenge.

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Prevalence of NTM in children in the UK CF registry stabilised from 2016 to 18.

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This prevalence, however, remained substantially higher than in 2010.

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We highlight the need for high quality studies in this area.

Nontuberculous mycobacteria (NTM) infection is of growing concern in cystic fibrosis (CF). UK CF Registry data were analyzed from 2016 to 2018. Prevalence of infection stabilized in the pediatric age-group during this period but remained substantially higher than in 2010. Allergic bronchopulmonary aspergillosis and Pseudomonas aeruginosa infection were associated with NTM infection.

Diagnostic and economic evaluation of a point-of-care test for respiratory syncytial virus

Respiratory syncytial virus is a common cause of bronchiolitis. Historically, point-of-care tests have involved antigen detection technology with limited sensitivity. The aim of this study was to prospectively evaluate the diagnostic accuracy and model the economic impact of the Roche cobas® Liat® point-of-care influenza A/B and respiratory syncytial virus test.

The “DEC-RSV” study was a multi-centre, prospective, observational study in children under 2 years presenting with viral respiratory symptoms. A nasopharyngeal aspirate sample was tested using the point-of-care test and standard laboratory-based procedures. The primary outcome was accuracy of respiratory syncytial virus detection. The cost implications of adopting a point-of-care test were modelled using study data.

A total of 186 participants were recruited, with both tests performed on 177 samples. The point-of-care test was invalid for 16 samples (diagnostic yield 91%) leaving 161 available for primary analysis. After resolving discrepancies, the cobas® Liat® respiratory syncytial virus test had 100.00% (95% CI 96.07%–100.00%) sensitivity and 98.53% (95% CI 92.08%–99.96%) specificity. Median time to result was 0.6 h (interquartile range (IQR) 0.5–1) for point-of-care testing and 28.9 h (IQR 26.3–48.1) for standard laboratory testing. Estimated non-diagnostic cost savings for 1000 patients, based on isolation decision-making on point-of-care test result, were £57 010, which would increase to £94 847 when cohort nursing is used.

In young children the cobas® Liat® point-of-care respiratory syncytial virus test has high diagnostic accuracy using nasopharyngeal aspirates (currently an off-licence sample type). Time to result is clinically important and was favourable compared to laboratory-based testing. The potential exists for cost savings when adopting the point-of-care test.

This prospective evaluation of the cobas Liat point-of-care RSV test in children demonstrated high diagnostic accuracy using nasopharyngeal aspirate samples, with favourable time to result compared to usual laboratory-based testing procedureshttps://bit.ly/2yKKmUB

Epidemiology of Nontuberculous Mycobacteria Infection in Children and Young People With Cystic Fibrosis: Analysis of UK Cystic Fibrosis Registry

Background

Infection with nontuberculous mycobacteria (NTM) is of growing clinical concern in people with cystic fibrosis (CF). The epidemiology of infection in children and young people remains poorly understood. Our goal was to investigate the epidemiology of NTM infection in the pediatric age group using data from the UK CF Registry.

Methods

Data from 2010–2015 for individuals aged <16 years (23200 observations from 5333 unique individuals) were obtained. Univariate analysis of unique individuals comparing all key clinical factors and health outcomes to NTM status was performed. The significant factors that were identified were used to generate a multivariate logistic regression model that, following step-wise removal, generated a final parsimonious model.

Results

The prevalence of individuals with a NTM-positive respiratory culture increased every year from 2010 (45 [1.3%]) to 2015 (156 [3.8%]). Allergic bronchopulmonary aspergillosis (odds ratio [OR], 2.66; P = 5.0 × 10⁻⁸), age (OR, 1.08; P = 3.4 × 10⁻¹⁰), and intermittent Pseudomonas aeruginosa infection (OR, 1.51; P = .004) were significantly associated with NTM infection.

Conclusions

NTM infection is of increasing prevalence in the UK pediatric CF population. This study highlights the urgent need for work to establish effective treatment and prevention strategies for NTM infection in young people with CF.

Developing a core outcome set for children with protracted bacterial bronchitis

Background

Protracted bacterial bronchitis (PBB) is a chronic endobrochial infection and a leading cause of chronic wet cough in children. There is an urgent need for a randomised controlled trial to investigate the optimal treatment but there is no core outcome set (COS) to inform choice of outcomes. A COS is a standardised set of outcomes representing the minimum that should be measured and reported in clinical trials of a specific condition. We have developed a COS for PBB.

Methods

Potential core outcomes were collated from a systematic review, interviews with parents and a clinician survey. A two-round Delphi survey of healthcare professionals identified which outcomes had consensus for inclusion. The final COS was agreed at a consensus meeting of parent representatives and clinicians.

Results

20 outcomes were identified for the Delphi survey. After two rounds, 10 reached consensus. These were combined and edited at the consensus meeting into the final six: 1) Resolution of cough assessed using a cough score/diary recorded daily by parent(s) during treatment; 2) relapse of chronic wet cough and/or cumulative antibiotic treatment during ≥12 months follow-up; 3) change in child's quality of life (parent-proxy reporting for young children); 4) emergence of antibiotic resistance; 5) development of bronchiectasis diagnosed on clinically indicated computed tomography scans; and 6) microbiological clearance of identified respiratory pathogen if samples readily available.

Conclusions

We have developed a COS for PBB which will reduce the outcome heterogeneity and bias of future clinical trials, as well as promoting comparison between studies.

A core outcome set for protracted bacterial bronchitis in children that will reduce outcome heterogeneity and bias in future clinical trials and promote meta-analysishttp://bit.ly/2PDQvHL

Physiological effects of high-flow nasal cannula therapy in preterm infants

OBJECTIVE

High-flow nasal cannula (HFNC) therapy is increasingly used in preterm infants despite a paucity of physiological studies. We aimed to investigate the effects of HFNC on respiratory physiology.

STUDY DESIGN

A prospective randomised crossover study was performed enrolling clinically stable preterm infants receiving either HFNC or nasal continuous positive airway pressure (nCPAP). Infants in three current weight groups were studied: <1000 g, 1000-1500 g and >1500 g. Infants were randomised to either first receive HFNC flows 8-2 L/min and then nCPAP 6 cm H₂O or nCPAP first and then HFNC flows 8-2 L/min. Nasopharyngeal end-expiratory airway pressure (pEEP), tidal volume, dead space washout by nasopharyngeal end-expiratory CO₂ (pEECO₂), oxygen saturation and vital signs were measured.

RESULTS

A total of 44 preterm infants, birth weights 500-1900 g, were studied. Increasing flows from 2 to 8 L/min significantly increased pEEP (mean 2.3-6.1 cm H₂O) and reduced pEECO₂ (mean 2.3%-0.9%). Tidal volume and transcutaneous CO₂ were unchanged. Significant differences were seen between pEEP generated in open and closed mouth states across all HFNC flows (difference 0.6-2.3 cm H₂O). Infants weighing <1000 g received higher pEEP at the same HFNC flow than infants weighing >1000 g. Variability of pEEP generated at HFNC flows of 6-8 L/min was greater than nCPAP (2.4-13.5 vs 3.5-9.9 cm H₂O).

CONCLUSIONS

HFNC therapy produces clinically significant pEEP with large variability at higher flow rates. Highest pressures were observed in infants weighing <1000 g. Flow, weight and mouth position are all important determinants of pressures generated. Reductions in pEECO₂ support HFNC's role in dead space washout.

Neutrophils in community-acquired pneumonia: parallels in dysfunction at the extremes of age

"Science means constantly walking a tight rope" Heinrich Rohrer, physicist, 1933. Community-acquired pneumonia (CAP) is the leading cause of death from infectious disease worldwide and disproportionately affects older adults and children. In high-income countries, pneumonia is one of the most common reasons for hospitalisation and (when recurrent) is associated with a risk of developing chronic pulmonary conditions in adulthood. Pneumococcal pneumonia is particularly prevalent in older adults, and here, pneumonia is still associated with significant mortality despite the widespread use of pneumococcal vaccination in middleand high-income countries and a low prevalence of resistant organisms. In older adults, 11% of pneumonia survivors are readmitted within months of discharge, often with a further pneumonia episode and with worse outcomes. In children, recurrent pneumonia occurs in approximately 10% of survivors and therefore is a significant cause of healthcare use. Current antibiotic trials focus on short-term outcomes and increasingly shorter courses of antibiotic therapy. However, the high requirement for further treatment for recurrent pneumonia questions the effectiveness of current strategies, and there is increasing global concern about our reliance on antibiotics to treat infections. Novel therapeutic targets and approaches are needed to improve outcomes. Neutrophils are the most abundant immune cell and among the first responders to infection. Appropriate neutrophil responses are crucial to host defence, as evidenced by the poor outcomes seen in neutropenia. Neutrophils from older adults appear to be dysfunctional, displaying a reduced ability to target infected or inflamed tissue, poor phagocytic responses and a reduced capacity to release neutrophil extracellular traps (NETs); this occurs in health, but responses are further diminished during infection and particularly during sepsis, where a reduced response to granulocyte colony-stimulating factor (G-CSF) inhibits the release of immature neutrophils from the bone marrow. Of note, neutrophil responses are similar in preterm infants. Here, the storage pool is decreased, neutrophils are less able to degranulate, have a reduced migratory capacity and are less able to release NETs. Less is known about neutrophil function from older children, but theoretically, impaired functions might increase susceptibility to infections. Targeting these blunted responses may offer a new paradigm for treating CAP, but modifying neutrophil behaviour is challenging; reducing their numbers or inhibiting their function is associated with poor clinical outcomes from infection. Uncontrolled activation and degranulation can cause significant host tissue damage. Any neutrophil-based intervention must walk the tightrope described by Heinrich Rohrer, facilitating necessary phagocytic functions while preventing bystander host damage, and this is a significant challenge which this review will explore.

Real-Time, Semi-Automated Fluorescent Measurement of the Airway Surface Liquid pH of Primary Human Airway Epithelial Cells

In recent years, the importance of mucosal surface pH in the airways has been highlighted by its ability to regulate airway surface liquid (ASL) hydration, mucus viscosity and activity of antimicrobial peptides, key parameters involved in innate defense of the lungs. This is of primary relevance in the field of chronic respiratory diseases such as cystic fibrosis (CF) where these parameters are dysregulated. While different groups have studied ASL pH both in vivo and in vitro, their methods report a relatively wide range of ASL pH values and even contradictory findings regarding any pH differences between non-CF and CF cells. Furthermore, their protocols do not always provide enough details in order to ensure reproducibility, most are low throughput and require expensive equipment or specialized knowledge to implement, making them difficult to establish in most labs. Here we describe a semi-automated fluorescent plate reader assay that enables the real-time measurement of ASL pH under thin film conditions that more closely resemble the in vivo situation. This technique allows for stable measurements for many hours from multiple airway cultures simultaneously and, importantly, dynamic changes in ASL pH in response to agonists and inhibitors can be monitored. To achieve this, the ASL of fully differentiated primary human airway epithelial cells (hAECs) are stained overnight with a pH-sensitive dye in order to allow for the reabsorption of the excess fluid to ensure thin film conditions. After fluorescence is monitored in the presence or absence of agonists, pH calibration is performed in situ to correct for volume and dye concentration. The method described provides the required controls to make stable and reproducible ASL pH measurements, which ultimately could be used as a drug discovery platform for personalized medicine, as well as adapted to other epithelial tissues and experimental conditions, such as inflammatory and/or host-pathogen models.

Sphingolipids as targets for inhalation treatment of cystic fibrosis

Studies over the past several years have demonstrated the important role of sphingolipids in cystic fibrosis (CF), chronic obstructive pulmonary disease and acute lung injury. Ceramide is increased in airway epithelial cells and alveolar macrophages of CF mice and humans, while sphingosine is dramatically decreased. This increase in ceramide results in chronic inflammation, increased death of epithelial cells, release of DNA into the bronchial lumen and thereby an impairment of mucociliary clearance; while the lack of sphingosine in airway epithelial cells causes high infection susceptibility in CF mice and possibly patients. The increase in ceramide mediates an ectopic expression of β1-integrins in the luminal membrane of CF epithelial cells, which results, via an unknown mechanism, in a down-regulation of acid ceramidase. It is predominantly this down-regulation of acid ceramidase that results in the imbalance of ceramide and sphingosine in CF cells. Correction of ceramide and sphingosine levels can be achieved by inhalation of functional acid sphingomyelinase inhibitors, recombinant acid ceramidase or by normalization of β1-integrin expression and subsequent re-expression of endogenous acid ceramidase. These treatments correct pulmonary inflammation and prevent or treat, respectively, acute and chronic pulmonary infections in CF mice with Staphylococcus aureus and mucoid or non-mucoid Pseudomonas aeruginosa. Inhalation of sphingosine corrects sphingosine levels only and seems to mainly act against the infection. Many antidepressants are functional inhibitors of the acid sphingomyelinase and were designed for systemic treatment of major depression. These drugs could be repurposed to treat CF by inhalation.