Complexity, temporal stability, and clinical correlates of airway bacterial community composition in primary ciliary dyskinesia

[Primary ciliary dyskinesia]

Primary ciliary dyskinesia (PCD) is a rare genetic disorder with a variable clinical phenotype that is accompanied by reduced motility of the cilia in the respiratory tract and numerous other organs. This leads to various characteristic symptoms and disease manifestations, primarily affecting the lungs (chronic persistent productive cough, bronchiectasis), the nose and paranasal sinuses (chronic persistent rhinitis or rhinosinusitis) as well as the middle ear (chronic otitis media, middle ear effusion). Moreover, PCD is associated with impaired fertility or lateralization defects (situs anomalies, congenital heart defects). The diagnostics of PCD are complex and require a combination of several sophisticated instrument-based diagnostic procedures. Through thorough history taking and evaluation, suspected cases can be comparatively well identified based on typical clinical features and referred to further diagnostics. In recent years, molecular genetic analysis through panel diagnostics or whole exome and whole genome sequencing, has gained in importance as this enables affected individuals to participate in disease-specific and genotype-specific clinical trials. Although the current treatment is purely symptomatic, the earliest possible diagnosis is crucial for connecting patients to specialized PCD centers, which can have a significant impact on the clinical course of the affected individuals.

The airway microbiota in siblings with primary ciliary dyskinesia: Related factors and correlation with clinical characteristics

OBJECTIVES-AIM

We aimed to show the composition and structure of and explore affecting factors on airway microbiota in primary ciliary dyskinesia (PCD) patients using culture-independent techniques.

METHOD

A cross-sectional observational study was performed. We recruited 14 PCD patients (seven pairs of siblings) and nine parents. Bacterial rDNA was extracted from sputum and nasal samples. Sputum samples were also inoculated on suitable bacteriological media.

RESULTS

Thirty-three separate genera were detected in sputum samples of PCD patients, and 41 were in nasal samples of parents. The detected genera were dominated by phyla Proteobacteria in PCD patients and their parents. Culture-dependent analyses could not detect many of the bacterial species detected with culture-independent analyses. There were no significant differences in alpha diversity between the siblings' pairs, and siblings' samples did not cluster together nearly as strongly as nonsiblings' samples. Patients who had no new complaints and no bacterial growth with the culture-dependent method at the time of study and patients who had no Haemophilus influenzae growth in the previous year had a significantly greater diversity (p < .05). Microbiota communities tended to cluster together by age, pulmonary exacerbation status, the existence of at least one H. influenzae growth with culture-dependent analyses in the previous year, and forced expiratory volume in 1 sec z and FEF25-75 z-scores.

CONCLUSION

The airway microbiota of patients with PCD have presented more diverse bacterial communities than had been indicated with culture-dependent methods. The study identifies relationships between bacterial airway microbiota composition and the clinical measures of patients. Sibling pairs have no more community similarities than nonsibling PCD patients. Our results may indicate that the patients' clinical characteristics, which determine the disease severity, might affect the PCD microbiome.

Airway microbiota correlated with pulmonary exacerbation in primary ciliary dyskinesia patients

IMPORTANCE

PCD is a rare disease characterized by productive cough, rhinitis, and recurrent infections of the upper and lower airways. Because the diagnosis of PCD is often delayed, patients receive more antibiotics, experience a heavier financial burden, and have a worse prognosis; thus, it is very important to identify the pathogeny and use the correct antibiotic. In this large single-center study of PCD microbiota, we identified an outline of the bacterial microbes from the respiratory tract; furthermore, we found that the microbiota diversity in pediatric sputum was richer than that in pediatric BALF through sequencing, indicating a heterogeneous community structure. The microbiota diversity and richness were lower during pulmonary exacerbation than during pulmonary stabilization. A significantly higher abundance of Pseudomonas had a moderate distinguishing effect for lung exacerbation, which attracted more attention for the study of Pseudomonas therapy in pediatric patients with PCD.

Primary ciliary dyskinesia

BACKGROUND AND OBJECTIVES

Primary ciliary dyskinesia (PCD, ORPHA:244) is a group of rare genetic disorders characterized by dysfunction of motile cilia. It is phenotypically and genetically heterogeneous, with more than 50 genes involved. Thanks to genetic, clinical, and functional characterization, immense progress has been made in the understanding and diagnosis of PCD. Nevertheless, it is underdiagnosed due to the heterogeneous phenotype and complexity of diagnosis. This review aims to help clinicians navigate this heterogeneous group of diseases. Here, we describe the broad spectrum of phenotypes associated with PCD and address pitfalls and difficult-to-interpret findings to avoid misinterpretation.

METHOD

Review of literature CONCLUSION: PCD diagnosis is complex and requires integration of history, clinical picture, imaging, functional and structural analysis of motile cilia and, if available, genetic analysis to make a definitive diagnosis. It is critical that we continue to expand our knowledge of this group of rare disorders to improve the identification of PCD patients and to develop evidence-based therapeutic approaches.

Physiology and pathophysiology of human airway mucus

The mucus clearance system is the dominant mechanical host defense system of the human lung. Mucus is cleared from the lung by cilia and airflow, including both two-phase gas-liquid pumping and cough-dependent mechanisms, and mucus transport rates are heavily dependent on mucus concentration. Importantly, mucus transport rates are accurately predicted by the gel-on-brush model of the mucociliary apparatus from the relative osmotic moduli of the mucus and periciliary-glycocalyceal (PCL-G) layers. The fluid available to hydrate mucus is generated by transepithelial fluid transport. Feedback interactions between mucus concentrations and cilia beating, via purinergic signaling, coordinate Na+ absorptive vs Cl- secretory rates to maintain mucus hydration in health. In disease, mucus becomes hyperconcentrated (dehydrated). Multiple mechanisms derange the ion transport pathways that normally hydrate mucus in muco-obstructive lung diseases, e.g., cystic fibrosis (CF), chronic obstructive pulmonary disease (COPD), non-CF bronchiectasis (NCFB), and primary ciliary dyskinesia (PCD). A key step in muco-obstructive disease pathogenesis is the osmotic compression of the mucus layer onto the airway surface with the formation of adherent mucus plaques and plugs, particularly in distal airways. Mucus plaques create locally hypoxic conditions and produce airflow obstruction, inflammation, infection, and, ultimately, airway wall damage. Therapies to clear adherent mucus with hydrating and mucolytic agents are rational, and strategies to develop these agents are reviewed.

Design and manufacture of a lyophilised faecal microbiota capsule formulation to GMP standards

Faecal microbiota transplant (FMT) is an established and effective treatment for recurrent Clostridioides difficile infection (CDI) and has many other potential clinical applications. However, preparation and quality of FMT is poorly standardised and clinical studies are hampered by a lack of well-defined FMT formulations that meet regulatory standards for medicines. As an alternative to FMT suspensions for administration by nasojejunal tube or colonoscopy, which is invasive and disliked by many patients, this study aimed to develop a well-controlled, standardised method for manufacture of lyophilised FMT capsules and to provide stability data allowing storage for extended time periods. Faecal donations were collected from healthy, pre-screened individuals, homogenised, filtered and centrifuged to remove dietary matter. The suspension was centrifuged to pellet bacteria, which were resuspended with trehalose and lyophilised to produce a powder which was filled into 5 enteric-coated capsules (size 0). Live-dead bacterial cell quantitative PCR assay showed <10 fold viable bacterial load reduction through the manufacturing process. No significant loss of viable bacterial load was observed after storage at -80 °C for 36 weeks (p = 0.24, n = 5). Initial clinical experience demonstrated that the capsules produced clinical cure in patients with CDI with no adverse events reported (n = 7). We provide the first report of a detailed manufacturing protocol and specification for an encapsulated lyophilised formulation of FMT. As clinical trials into intestinal microbiota interventions proceed, it is important to use a well-controlled investigational medicinal product in the studies so that any beneficial results can be replicated in clinical practice.

Correlation between Sputum Bacterial Culture Positive Rate and Drug Sensitivity Test Results and Disease Severity inInpatients and Its Clinical Significance: A SystematicReview and Meta-Analysis

Objective. To systematically evaluate the correlation between the positive rate of sputum bacterial culture and the results of drug sensitivity test and the severity of the disease and its clinical significance, so as to provide evidence-based medicine for clinical application. Methods. PubMed, Embase, ScienceDirect, Cochrane Library, China Knowledge Network Database (CNKI), China VIP Database, Wanfang Database, and China Biomedical Literature Database (CBM) online database were used. The retrieval time limit was from the establishment of the database to the present. Data for all included studies were extracted by two independent researchers, and the risk of bias for the quality of each included study was assessed by the Cochrane Handbook 5.1.0 criteria. RevMan5.4 statistical software was used to analyze the collected data by meta. Results. In the end, 6 RCT articles were included. Overall, 613 samples were included in 6 RCT studies. The correlation between the positive rate of sputum bacterial culture in inpatients and the severity of the disease was meta-analyzed. The heterogeneity test results showed that Chi2 = 177.20, df = 3, P < 0.00001, and I2 = 98%, indicating that there was obvious heterogeneity among the included research data. It was considered that there was a correlation between the positive rate of sputum bacterial culture and the severity of the disease. The correlation between the results of the drug sensitivity test of inpatients and the severity of the disease was evaluated. The results of the heterogeneity test showed that Chi2 = 0.00, df = 1, P = 1 > 0.05, and I2 = 0%, indicating that there was no heterogeneity among the included research data. In addition, the combined effect of WMD was analyzed by the fixed effect model. The combined effect dose WMD test was Z = 6.58 (P < 0.00001). It was considered that there was a correlation between the results of the drug sensitivity test and the severity of the disease. Conclusion. There is a correlation between positive sputum culture and drug sensitivity test results and the severity of the disease in hospitalized patients. In clinical practice, for hospitalized patients, the positive sputum bacterial culture rate and drug sensitivity test results can be used to guide the appropriate use of antibiotics. Due to the low input from the literature, more studies with higher methodological quality and longer follow-up are needed for further validation.

No smoke without fire: the impact of cigarette smoking on the immune control of tuberculosis

Cigarette smoke (CS) exposure is a key risk factor for both active and latent tuberculosis (TB). It is associated with delayed diagnosis, more severe disease progression, unfavourable treatment outcomes and relapse after treatment. Critically, CS exposure is common in heavily populated areas with a high burden of TB, such as China, India and the Russian Federation. It is therefore prudent to evaluate interventions for TB while taking into account the immunological impacts of CS exposure. This review is a mechanistic examination of how CS exposure impairs innate barrier defences, as well as alveolar macrophage, neutrophil, dendritic cell and T-cell functions, in the context of TB infection and disease.

Porphyromonas pasteri and Prevotella nanceiensis in the sputum microbiota are associated with increased decline in lung function in individuals with cystic fibrosis

Although anaerobic bacteria exist in abundance in cystic fibrosis (CF) airways, their role in disease progression is poorly understood. We hypothesized that the presence and relative abundance of the most prevalent, live, anaerobic bacteria in sputum of adults with CF were associated with adverse clinical outcomes. This is the first study to prospectively investigate viable anaerobic bacteria present in the sputum microbiota and their relationship with long-term outcomes in adults with CF. We performed 16S rRNA analysis using a viability quantitative PCR technique on sputum samples obtained from a prospective cohort of 70 adults with CF and collected clinical data over an 8 year follow-up period. We examined the associations of the ten most abundant obligate anaerobic bacteria present in the sputum with annual rate of FEV₁ change. The presence of Porphyromonas pasteri and Prevotella nanceiensis were associated with a greater annual rate of FEV₁ change; −52.3 ml yr⁻¹ (95 % CI-87.7;−16.9), –67.9 ml yr⁻¹ (95 % CI-115.6;−20.1), respectively. Similarly, the relative abundance of these live organisms were associated with a greater annual rate of FEV₁ decline of −3.7 ml yr⁻¹ (95 % CI: −6.1 to −1.3, P=0.003) and −5.3 ml yr⁻¹ (95 % CI: −8.7 to −1.9, P=0.002) for each log₂ increment of abundance, respectively. The presence and relative abundance of certain anaerobes in the sputum of adults with CF are associated with a greater rate of long-term lung function decline. The pathogenicity of anaerobic bacteria in the CF airways should be confirmed with further longitudinal prospective studies with a larger cohort of participants.

Comparison of the airway microbiota in children with chronic suppurative lung disease

RATIONALE

The airway microbiota is important in chronic suppurative lung diseases, such as primary ciliary dyskinesia (PCD) and cystic fibrosis (CF). This comparison has not previously been described but is important because difference between the two diseases may relate to the differing prognoses and lead to pathological insights and potentially, new treatments.

OBJECTIVES

To compare the longitudinal development of the airway microbiota in children with PCD to that of CF and relate this to age and clinical status.

METHODS

Sixty-two age-matched children (age range 0.5-17 years) with PCD or CF (n=31 in each group) were recruited prospectively and followed for 1.1 years. Throat swabs or sputum as well as clinical information were collected at routine clinical appointments. 16S rRNA gene sequencing was performed.

MEASUREMENTS AND MAIN RESULTS

The microbiota was highly individual and more diverse in PCD and differed in community composition when compared with CF. While Streptococcus was the most abundant genus in both conditions, Pseudomonas was more abundant in CF with Haemophilus more abundant in PCD (P_adj=0.0005). In PCD only, an inverse relationship was seen in the relative abundance of Streptococcus and Haemophilus with age.

CONCLUSIONS

Bacterial community composition differs between children with PCD and those with CF. Pseudomonas is more prevalent in CF and Haemophilus in PCD, at least until infection with Pseudomonas supervenes. Interactions between organisms, particularly members of Haemophilus, Streptococcus and Pseudomonas genera appear important. Study of the interactions between these organisms may lead to new therapies or risk stratification.

Lower airway clinical outcome measures for use in primary ciliary dyskinesia research: a scoping review

Objectives

Disease-specific, well-defined and validated clinical outcome measures are essential in designing research studies. Poorly defined outcome measures hamper pooling of data and comparisons between studies. We aimed to identify and describe pulmonary outcome measures that could be used for follow-up of patients with primary ciliary dyskinesia (PCD).

Methods

We conducted a scoping review by systematically searching MEDLINE, Embase and the Cochrane Database of Systematic Reviews online databases for studies published from 1996 to 2020 that included ≥10 PCD adult and/or paediatric patients.

Results

We included 102 studies (7289 patients). 83 studies reported on spirometry, 11 on body plethysmography, 15 on multiple-breath washout, 36 on high-resolution computed tomography (HRCT), 57 on microbiology and 17 on health-related quality of life. Measurement and reporting of outcomes varied considerably between studies (e.g. different scoring systems for chest HRCT scans). Additionally, definitions of outcome measures varied (e.g. definition of chronic colonisation by respiratory pathogen), impeding direct comparisons of results.

Conclusions

This review highlights the need for standardisation of measurements and reporting of outcome measures to enable comparisons between studies. Defining a core set of clinical outcome measures is necessary to ensure reproducibility of results and for use in future trials and prospective cohorts.

Placentas delivered by pre-pregnant obese women have reduced abundance and diversity in the microbiome

Maternal pre‐pregnancy obesity may have an impact on both maternal and fetal health. We examined the microbiome recovered from placentas in a multi‐ethnic maternal pre‐pregnant obesity cohort, through an optimized microbiome protocol to enrich low bacterial biomass samples. We found that the microbiomes recovered from the placentas of obese pre‐pregnant mothers are less abundant and less diverse when compared to those from mothers of normal pre‐pregnancy weight. Microbiome richness also decreases from the maternal side to the fetal side, demonstrating heterogeneity by geolocation within the placenta. In summary, our study shows that the microbiomes recovered from the placentas are associated with pre‐pregnancy obesity.

Importance

Maternal pre‐pregnancy obesity may have an impact on both maternal and fetal health. The placenta is an important organ at the interface of the mother and fetus, and supplies nutrients to the fetus. We report that the microbiomes enriched from the placentas of obese pre‐pregnant mothers are less abundant and less diverse when compared to those from mothers of normal pre‐pregnancy weight. More over, the microbiomes also vary by geolocation within the placenta.

Primary Ciliary Dyskinesia

Primary ciliary dyskinesia (PCD) is an inherited cause of bronchiectasis. The estimated PCD prevalence in children with bronchiectasis is up to 26% and in adults with bronchiectasis is 1 to 13%. Due to dysfunction of the multiple motile cilia of the respiratory tract patients suffer from poor mucociliary clearance. Clinical manifestations are heterogeneous; however, a typical patient presents with chronic productive cough and rhinosinusitis from early life. Other symptoms reflect the multiple roles of motile cilia in other organs and can include otitis media and hearing loss, infertility, situs inversus, complex congenital heart disease, and more rarely other syndromic features such as hydrocephalus and retinitis pigmentosa. Awareness, identification, and diagnosis of a patient with PCD are important for multidisciplinary care and genetic counseling. Diagnosis can be pursued through a multitest pathway which includes the measurement of nasal nitric oxide, sampling the nasal epithelium to assess ciliary function and structure, and genotyping. Diagnosis is confirmed by the identification of a hallmark ultrastructural defect or pathogenic mutations in one of > 45 PCD causing genes. When a diagnosis is established management is centered around improving mucociliary clearance through physiotherapy and treatment of infection with antibiotics. The first international randomized controlled trial in PCD has recently been conducted showing azithromycin is effective in reducing exacerbations. It is likely that evidence-based PCD-specific management guidelines and therapies will be developed in the near future. This article examines prevalence, clinical features, diagnosis, and management of PCD highlighting recent advances in basic science and clinical care.

Mucociliary Respiratory Epithelium Integrity in Molecular Defense and Susceptibility to Pulmonary Viral Infections

Mucociliary defense, mediated by the ciliated and goblet cells, is fundamental to respiratory fitness. The concerted action of ciliary movement on the respiratory epithelial surface and the pathogen entrapment function of mucus help to maintain healthy airways. Consequently, genetic or acquired defects in lung defense elicit respiratory diseases and secondary microbial infections that inflict damage on pulmonary function and may even be fatal. Individuals living with chronic and acute respiratory diseases are more susceptible to develop severe coronavirus disease-19 (COVID-19) illness and hence should be proficiently managed. In light of the prevailing pandemic, we review the current understanding of the respiratory system and its molecular components with a major focus on the pathophysiology arising due to collapsed respiratory epithelium integrity such as abnormal ciliary movement, cilia loss and dysfunction, ciliated cell destruction, and changes in mucus rheology. The review includes protein interaction networks of coronavirus infection-manifested implications on the molecular machinery that regulates mucociliary clearance. We also provide an insight into the alteration of the transcriptional networks of genes in the nasopharynx associated with the mucociliary clearance apparatus in humans upon infection by severe acute respiratory syndrome coronavirus-2.

The airways microbiome of individuals with asthma treated with high and low doses of inhaled corticosteroids

BACKGROUND

Inhaled corticosteroids (ICS) are the mainstay of asthma treatment, but evidence suggests a link between ICS usage and increased rates of respiratory infections. We assessed the composition of the asthmatic airways microbiome in asthma patients taking low and high dose ICS and the stability of the microbiome over a 2 week period.

METHODS

We prospectively recruited 55 individuals with asthma. Of these, 22 were on low-dose ICS and 33 on high-dose ICS (16 on budesonide, 17 on fluticasone propionate). Sputum from each subject underwent DNA extraction, amplification and 16S rRNA gene sequencing of the bacterial component of the microbiome. 19 subjects returned for further sputum induction after 24 h and 2 weeks.

RESULTS

A total of 5,615,037 sequencing reads revealed 167 bacterial taxa in the asthmatic airway samples, with the most abundant being Streptococcus spp. No significant differences in sputum bacterial load or overall community composition were seen between the low- and high-dose ICS groups. However, Streptococcus spp. showed significantly higher relative abundance in subjects taking low-dose ICS (p = 0.002). Haemophilus parainfluenzae was significantly more abundant in subjects on high-dose fluticasone propionate than those on high-dose budesonide (p = 0.047). There were no statistically significant changes in microbiota composition over a 2-week period.

DISCUSSION

Whilst no significant differences were observed between the low- and high-dose ICS groups, increased abundance of the potential pathogen H. parainfluenzae was observed in patients taking high-dose fluticasone propionate compared to those taking high-dose budesonide. The microbiota were stable over fourteen days, providing novel evidence of the established community of bacteria in the asthmatic airways.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov NCT02671773.

[Management of Primary Ciliary Dyskinesia]

Die Primäre Ciliäre Dyskinesie (PCD, MIM 242650) ist eine seltene hereditäre Multisystemerkrankung mit klinisch heterogenem Phänotyp. Leitsymptom ist eine chronische Sekretretention der oberen und unteren Atemwege, welche durch die Dysfunktion motiler respiratorischer Zilien entsteht. In der Folge kommt es zur Ausbildung von Bronchiektasen, häufig zu einer Infektion durch Pseudomonas aeruginosa sowie einer abnehmenden Lungenfunktion bis hin zum Lungenversagen.

Bislang gibt es kaum evidenzbasierte Therapieempfehlungen, da randomisierte Langzeitstudien zur Behandlung der PCD fehlten. In diesem Jahr wurden die Daten einer ersten placebokontrollierten Medikamentenstudie bei PCD veröffentlicht. Anlässlich dieses Meilensteins im Management der PCD wurde der vorliegende Übersichtsartikel als Konsens von Patientenvertretern sowie Klinikern, die langjährige Erfahrung in der Behandlung der PCD haben, verfasst. Diese Arbeit bietet eine Zusammenfassung aktuell eingesetzter Behandlungsverfahren, die überwiegend auf persönlichen Erfahrungen und Expertenmeinungen beruhen oder von anderen Atemwegserkrankungen wie der Cystischen Fibrose (CF), COPD oder Bronchiektasen-Erkrankung abgeleitet werden. Da es derzeit keine kurative Therapie für PCD gibt, stehen symptomatische Maßnahmen wie die regelmäßige Reinigung der Atemwege und die Behandlung von rezidivierenden Atemwegsinfektionen im Fokus. Nicht respiratorische Manifestationen werden organspezifisch behandelt. Um neben der ersten Medikamentenstudie mehr evidenzbasiertes Wissen zu generieren, werden weitere Projekte etabliert, u. a. ein internationales PCD-Register. Hierüber wird Patienten der Zugang zu klinischen und wissenschaftlichen Studien erleichtert und die Vernetzung behandelnder Zentren gefördert. Des Weiteren können Erkenntnisse über eine Genotyp-spezifische Erkrankungsschwere erlangt werden, um folglich die therapeutische Versorgung der Patienten zu verbessern und somit zu individualisieren.

Clinical features and management of children with primary ciliary dyskinesia in England

OBJECTIVE

In England, the National Health Service commissioned a National Management Service for children with primary ciliary dyskinesia (PCD). The aims of this study were to describe the health of children seen in this Service and compare lung function to children with cystic fibrosis (CF).

DESIGN

Multi-centre service evaluation of the English National Management PCD Service.

SETTING

Four nationally commissioned PCD centres in England.

PATIENTS

333 children with PCD reviewed in the Service in 2015; lung function data were also compared with 2970 children with CF.

RESULTS

Median age at diagnosis for PCD was 2.6 years, significantly lower in children with situs inversus (1.0 vs 6.0 years, p<0.001). Compared with national data from the CF Registry, mean (SD) %predicted forced expiratory volume in one second (FEV₁) was 76.8% in PCD (n=240) and 85.0% in CF, and FEV₁ was lower in children with PCD up to the age of 15 years. Approximately half of children had some hearing impairment, with 26% requiring hearing aids. Children with a lower body mass index (BMI) had lower FEV₁ (p<0.001). One-third of children had positive respiratory cultures at review, 54% of these grew Haemophilus influenzae.

CONCLUSIONS

We provide evidence that children with PCD in England have worse lung function than those with CF. Nutritional status should be considered in PCD management, as those with a lower BMI have significantly lower FEV₁. Hearing impairment is common but seems to improve with age. Well-designed and powered randomised controlled trials on management of PCD are needed to inform best clinical practice.

Registries and collaborative studies for primary ciliary dyskinesia in Europe

Primary ciliary dyskinesia (PCD) is a rare inherited disease characterised by malfunctioning cilia leading to a heterogeneous clinical phenotype with many organ systems affected. There is a lack of data on clinical presentation, prognosis and effectiveness of treatments, making it mandatory to improve the scientific evidence base.

This article reviews the data resources that are available in Europe for clinical and epidemiological research in PCD, namely established national PCD registries and national cohort studies, plus two large collaborative efforts (the international PCD (iPCD) Cohort and the International PCD Registry), and discusses their strengths, limitations and perspectives.

Denmark, Cyprus, Norway and Switzerland have national population-based registries, while England and France conduct multicentre cohort studies. Based on the data contained in these registries, the prevalence of diagnosed PCD is 3–7 per 100 000 in children and 0.2–6 per 100 000 in adults. All registries, together with other studies from Europe and beyond, contribute to the iPCD Cohort, a collaborative study including data from over 4000 PCD patients, and to the International PCD Registry, which is part of the ERN (European Reference Network)-LUNG network.

This rich resource of readily available, standardised and contemporaneous data will allow obtaining fast answers to emerging clinical and research questions in PCD.

The growing collaborative network of national and international registries and cohort studies of patients with PCD provides an excellent resource for research on this rare diseasehttps://bit.ly/3dto75l

Primary ciliary dyskinesia in the genomics age

Primary ciliary dyskinesia is a genetically and clinically heterogeneous syndrome. Impaired function of motile cilia causes failure of mucociliary clearance. Patients typically present with neonatal respiratory distress of unknown cause and then continue to have a daily wet cough, recurrent chest infections, perennial rhinosinusitis, otitis media with effusion, and bronchiectasis. Approximately 50% of patients have situs inversus, and infertility is common. While understanding of the underlying genetics and disease mechanisms have substantially advanced in recent years, there remains a paucity of evidence for treatment. Next-generation sequencing has increased gene discovery, and mutations in more than 40 genes have been reported to cause primary ciliary dyskinesia, with many other genes likely to be discovered. Increased knowledge of cilia genes is challenging perceptions of the clinical phenotype, as some genes reported in the last 5 years are associated with mild respiratory disease. Developments in genomics and molecular medicine are rapidly improving diagnosis, and a genetic cause can be identified in approximately 70% of patients known to have primary ciliary dyskinesia. Groups are now investigating novel and personalised treatments, although gene therapies are unlikely to be available in the near future.

A retrospective analysis of the pathogens in the airways of patients with primary ciliary dyskinesia

INTRODUCTION

Primary ciliary dyskinesia (PCD) is a rare genetically heterogeneous disorder of motile cilia, which leads to recurrent and chronic airway infections. Detailed information about infection causing pathogens is scarce. With this study, we aimed to determine the prevalence and susceptibility of the most common respiratory pathogens in PCD patients retrospectively in a cross-sectional and the dynamics of the microbiological diversity in a longitudinal study.

METHODS

Microbiological and clinical data of 106 patients between 2010 and 2016 were analysed cross-sectionally and of 28 patients longitudinally. Dynamics in microbiological diversity were assessed by calculating the mean rate of alteration (MRA).

RESULTS

Haemophilus influenzae was the most common pathogen (n = 41; 38.7%) followed by Staphylococcus aureus (n = 36; 34%), Moraxella catarrhalis (n = 18; 17%) and Pseudomonas aeruginosa (n = 16; 15.1%). Nontuberculous mycobacteria were cultured from two patients (1.9%). H. influenzae was the most prevalent pathogen in children (n = 31; 45.6%), S. aureus in adults (n = 15; 39%). Two patients were infected by methicillin-resistant S. aureus. P. aeruginosa was mostly susceptible to standard antibiotics with highest rates of resistance against fosfomycin (63.6%; 7/11). The culture of P. aeruginosa correlated negatively with age adjusted FEV₁% predicted (p = 0.04), while the MRA was positively associated with age (rho 0.411, p = 0.032).

DISCUSSION

In PCD patients, the prevalence of pathogens differed in children and adults with H. influenzae and S. aureus being the most common pathogens in children, S. aureus and P. aeruginosa in adults, respectively. Unexpectedly, the MRA increased by age.

Bronchiectasis: Treatment decisions for pulmonary exacerbations and their prevention

Interest in bronchiectasis has increased over the past two decades, as shown by the establishment of disease-specific registries in several countries, the publication of management guidelines and a growing number of clinical trials to address evidence gaps for treatment decisions. This review considers the evidence for defining and treating pulmonary exacerbations, the approaches for eradication of newly identified airway pathogens and the methods to prevent exacerbations through long-term treatments from a pragmatic practice-based perspective. Areas for future studies are also explored. Watch the video abstract.

Variation in treatment strategies for the eradication of Pseudomonas aeruginosa in primary ciliary dyskinesia across European centers

Primary ciliary dyskinesia (PCD) is a rare disease causing motile cilia dysfunction, recurrent airway infection, and bronchiectasis. Airway infection management strategies are borrowed from cystic fibrosis. The aim of this study is to describe the management of airway infection with Pseudomonas aeruginosa (PA) in children and adults with PCD across European centers. An online survey questionnaire was sent electronically using SurveyMonkey® to 55 PCD centers in 36 European countries. Fifty-two responded from 43 centers in 26 countries, a response rate of 70%. Most (89%) countries did not have written guidelines for PCD management. Airway sampling for infection detection at each clinic visit was more likely when follow-up was frequent. Eighty-seven percent of centers chose to treat the first PA isolate, most prescribing combined oral ciprofloxacin and inhaled colistimethate sodium (43%, n = 18). The preferred treatment for chronic infection with PA was nebulized colistimethate in 51% (n = 22). In summary, considerable variation exists across European centers in the frequency of patient follow-up and airway sampling for infection, treatment goals, and the management of PA infection. Few centers had written guidelines for PCD management. Clinical trials to determine optimal treatment of PA in PCD patients are urgently needed.

The lung microbiome

Historically, our understanding of lung microbiology has relied on insight gained through culture-based diagnostic approaches that employ selective culture conditions to isolate specific pathogens. The relatively recent development of culture-independent microbiota-profiling techniques, particularly 16S rRNA (ribosomal ribonucleic acid) gene amplicon sequencing, has enabled more comprehensive characterisation of the microbial content of respiratory samples. The widespread application of such techniques has led to a fundamental shift in our view of respiratory microbiology. Rather than a sterile lung environment that can become colonised by microbes during infection, it appears that a more nuanced balance exists between what we consider respiratory health and disease, mediated by mechanisms that influence the clearance of microbes from the lungs. Where airway defences are compromised, the ongoing transient exposure of the lower airways to microbes can lead to the establishment of complex microbial communities within the lung. Importantly, the characteristics of these communities, and the manner in which they influence lung pathogenesis, can be very different from those of their constituent members when viewed in isolation. The lung microbiome, a construct that incorporates microbes, their genetic material, and the products of microbial genes, is increasingly central to our understanding of the regulation of respiratory physiology and the processes that underlie lung pathogenesis.

Bacterial infections in patients with primary ciliary dyskinesia: Comparison with cystic fibrosis

Primary ciliary dyskinesia (PCD) is an autosomal recessive disorder associated with severely impaired mucociliary clearance caused by defects in ciliary structure and function. Although recurrent bacterial infection of the respiratory tract is one of the major clinical features of this disease, PCD airway microbiology is understudied. Despite the differences in pathophysiology, assumptions about respiratory tract infections in patients with PCD are often extrapolated from cystic fibrosis (CF) airway microbiology. This review aims to summarize the current understanding of bacterial infections in patients with PCD, including infections with Pseudomonas aeruginosa, Staphylococcus aureus, and Moraxella catarrhalis, as it relates to bacterial infections in patients with CF. Further, we will discuss current and potential future treatment strategies aimed at improving the care of patients with PCD suffering from recurring bacterial infections.

Cephalosporin-3'-Diazeniumdiolate NO Donor Prodrug PYRRO-C3D Enhances Azithromycin Susceptibility of Nontypeable Haemophilus influenzae Biofilms

PYRRO-C3D is a cephalosporin-3-diazeniumdiolate nitric oxide (NO) donor prodrug designed to selectively deliver NO to bacterial infection sites. The objective of this study was to assess the activity of PYRRO-C3D against nontypeable Haemophilus influenzae (NTHi) biofilms and examine the role of NO in reducing biofilm-associated antibiotic tolerance. The activity of PYRRO-C3D on in vitro NTHi biofilms was assessed through CFU enumeration and confocal microscopy. NO release measurements were performed using an ISO-NO probe. NTHi biofilms grown on primary ciliated respiratory epithelia at an air-liquid interface were used to investigate the effects of PYRRO-C3D in the presence of host tissue. Label-free liquid chromatography-mass spectrometry (LC/MS) proteomic analyses were performed to identify differentially expressed proteins following NO treatment. PYRRO-C3D specifically released NO in the presence of NTHi, while no evidence of spontaneous NO release was observed when the compound was exposed to primary epithelial cells. NTHi lacking β-lactamase activity failed to trigger NO release. Treatment significantly increased the susceptibility of in vitro NTHi biofilms to azithromycin, causing a log fold reduction (10-fold reduction or 1-log-unit reduction) in viability (P < 0.05) relative to azithromycin alone. The response was more pronounced for biofilms grown on primary respiratory epithelia, where a 2-log-unit reduction was observed (P < 0.01). Label-free proteomics showed that NO increased expression of 16 proteins involved in metabolic and transcriptional/translational functions. NO release from PYRRO-C3D enhances the efficacy of azithromycin against NTHi biofilms, putatively via modulation of NTHi metabolic activity. Adjunctive therapy with NO mediated through PYRRO-C3D represents a promising approach for reducing biofilm-associated antibiotic tolerance.

Host-microbiome interactions in acute and chronic respiratory infections

Respiratory infection is a leading cause of global morbidity and mortality. Understanding the factors that influence risk and outcome of these infections is essential to improving care. We increasingly understand that interactions between the microbial residents of our mucosal surfaces and host regulatory systems is fundamental to shaping local and systemic immunity. These mechanisms are most well defined in the gastrointestinal tract, however analogous systems also occur in the airways. Moreover, we now appreciate that the host-microbiota interactions at a given mucosal surface influence systemic host processes, in turn, affecting the course of infection at other anatomical sites. This review discusses the mechanisms by which the respiratory microbiome influences acute and chronic airway disease and examines the contribution of cross-talk between the gastrointestinal and respiratory compartments to microbe-mucosa interactions.

The Relationship Between Airway Antioxidant Levels, Alcohol Use Disorders, and Cigarette Smoking

BACKGROUND

Alcohol use disorders (AUDs) and cigarette smoking are associated with pulmonary oxidative stress, likely related to antioxidant depletion. Pulmonary oxidative stress may adversely affect innate immunity, leading to increased pneumonia susceptibility and severity, including development of the acute respiratory distress syndrome. In people with AUDs, most of whom smoke, antioxidant therapy can potentially restore immune cell function and attenuate pneumonia development. Challenges to human investigations of antioxidant therapies include an inability to identify pulmonary oxidative stress noninvasively and the optimal route to deliver pulmonary antioxidants. We sought to determine whether bronchoalveolar lavage (BAL) measures of thiol antioxidants from a 50-ml upper airway aliquot approximated those in the alveolar space and to determine whether AUDs and/or smoking affected these relationships.

METHODS

Healthy human subjects with and without AUDs, including smokers and nonsmokers, underwent BAL. Samples obtained after the first 50-ml normal saline aliquot were analyzed as representing bronchial airways; subsequent 50-ml aliquots were analyzed as representative of the alveolar space. Reduced and oxidized (GSSG) glutathione, cysteine (Cys), and its oxidized species, cystine, along with mixed disulfides (MDs) were quantified using high-performance liquid chromatography. The percent of total thiols present in their oxidized forms, and thiol redox potentials, were calculated.

RESULTS

Positive correlations between upper and lower BAL fluid thiol species were observed that were most robust for GSSG (ρ = 0.85), Cys (ρ = 0.83), and MDs (ρ = 0.69), but poor for thiol redox potential measures. In contrast to nonsmokers (either with or without AUDs), in subjects with AUDs who smoked, upper BAL fluid %GSSG, Cys, and MD measures were relatively increased compared to lower.

CONCLUSIONS

A small volume BAL procedure may be suitable to assess intrapulmonary oxidative stress related to thiol depletion. Factors including AUDs and smoking may disproportionately increase upper airways oxidative stress that could be relevant for therapeutic interventions.

Study protocol, rationale and recruitment in a European multi-centre randomized controlled trial to determine the efficacy and safety of azithromycin maintenance therapy for 6 months in primary ciliary dyskinesia

Background

Clinical management of primary ciliary dyskinesia (PCD) respiratory disease is currently based on improving mucociliary clearance and controlling respiratory infections, through the administration of antibiotics. Treatment practices in PCD are largely extrapolated from more common chronic respiratory disorders, particularly cystic fibrosis, but no randomized controlled trials (RCT) have ever evaluated efficacy and safety of any pharmacotherapeutics used in the treatment of PCD. Maintenance therapy, with the macrolide antibiotic azithromycin, is currently widely used in chronic respiratory diseases including PCD. In addition to its antibacterial properties, azithromycin is considered to have beneficial anti-inflammatory and anti-quorum-sensing properties.

The aim of this study is to determine the efficacy of azithromycin maintenance therapy for 6 months on respiratory exacerbations in PCD. The secondary objectives are to evaluate the efficacy of azithromycin on lung function, ventilation inhomogeneity, hearing impairment, and symptoms (respiratory, sinus, ears and hearing) measured on a PCD-specific health-related quality of life instrument, and to assess the safety of azithromycin maintenance therapy in PCD.

Methods

The BESTCILIA trial is a European multi-centre, double-blind, randomized, placebo-controlled, parallel group study. The intervention is tablets of azithromycin 250/500 mg according to body weight or placebo administered three times a week for 6 months. Subjects with a confirmed diagnosis of PCD, age 7–50 years, are eligible for inclusion. Chronic pulmonary infections with Gram-negative bacteria or any recent occurrence of non-tuberculous mycobacteria are exclusion criteria. The planned number of subjects to be included is 125. The trial has been approved by the Research Ethics Committees of the participating institutions.

Discussion

We present a study protocol of an ongoing RCT, evaluating for the first time, the efficacy and safety of a pharmacotherapeutic treatment for patients with PCD. The RCT evaluates azithromycin maintenance therapy, a drug already commonly prescribed in other chronic respiratory disorders. Furthermore, the trial will utilize the Lung clearance index and new, PCD-specific quality of life instruments as outcome measures for PCD. Recruitment is hampered by frequent occurrence of Pseudomonas aeruginosa infection, exacerbations at enrolment, and the patients’ perception of disease severity and necessity of additional management and treatment during trial participation.

Trial registration

EudraCT 2013-004664-58 (date of registration: 2014-04-08).

Bacterial evolution in PCD and CF patients follows the same mutational steps

Infections with Pseudomonas aeruginosa increase morbidity in primary ciliary dyskinesia (PCD) and cystic fibrosis (CF) patients. Both diseases are associated with a defect of the mucociliary clearance; in PCD caused by non-functional cilia, in CF by changed mucus. Whole genome sequencing of P. aeruginosa isolates from CF patients has shown that persistence of clonal lineages in the airways is facilitated by genetic adaptation. It is unknown whether this also applies to P. aeruginosa airway infections in PCD. We compared within-host evolution of P. aeruginosa in PCD and CF patients. P. aeruginosa isolates from 12 PCD patients were whole genome sequenced and phenotypically characterised. Ten out of 12 PCD patients were infected with persisting clone types. We identified convergent evolution in eight genes, which are also important for persistent infections in CF airways: genes related to antibiotic resistance, quorum sensing, motility, type III secretion and mucoidity. We document phenotypic and genotypic parallelism in the evolution of P. aeruginosa across infected patients with different genetic disorders. The parallel changes and convergent adaptation and evolution may be caused by similar selective forces such as the intensive antibiotic treatment and the inflammatory response, which drive the evolutionary processes.

A longitudinal study characterising a large adult primary ciliary dyskinesia population

Primary ciliary dyskinesia (PCD) in adults has not been well described. In this retrospective observational study we aimed to characterise a large adult population and identify features associated with disease progression.

We retrospectively analysed 151 adult patients at a single tertiary centre at baseline and longitudinally for a median of 7 years.

We found significant variation in age at diagnosis (median 23.5 years; range <1–72 years). Older age at diagnosis was associated with impaired baseline forced expiratory volume in 1 s (FEV1) (r= −0.30, p=0.01) and increased Pseudomonas aeruginosa colonisation (difference in medians 17 years (95% CI 4.5–20 years); p=0.002). Lung function decline was estimated at FEV1 decline of 0.49% predicted per year. Lung function decline was associated with ciliary ultrastructure, with microtubular defect patients having the greatest decline (p=0.04). High-resolution computed tomography (HRCT) scores of severity of bronchial wall dilatation (p<0.001) and extent of bronchiectasis (p=0.03) additionally showed evidence of modifying FEV1 decline with age.

Our study reveals that a large proportion of adult PCD patients are diagnosed late, with impaired FEV1 and increased P. aeruginosa colonisation. Increased disease burden on HRCT and ciliary ultrastructure may predict progressive lung function decline. This study characterises a large adult PCD population, identifies features associated with disease progression and highlights the need for prospective trials to determine whether early diagnosis of high-risk subgroups alongside optimal management can modify disease progression.

Clinical analysis of patients with primary ciliary dyskinesia in mainland China

BACKGROUND AND AIMS

Primary ciliary dyskinesia (PCD) is a rare, genetic disorder featured with dysfunctional motility of cilia. Clinical presentations of PCD include situs inversus, repeated respiratory tract infections, otitis media, sinusitis and infertility. This study aims to provide clinical strategies on diagnosis and treatment of PCD.

METHODS

Clinical data of seven patients diagnosed as PCD in Zhongshan Hospital, Fudan University were analyzed. We also extracted data from other cases in mainland China from the China Academic Journals Full-Text Database by the end of 2012. A total of 127 cases of PCD were summarized and analyzed in this study.

RESULTS

Seven patients in Zhongshan Hospital, Fudan University were finally confirmed to have PCD. All of them had clinical history of recurrent respiratory infection. Imaging analysis showed varying degrees of bronchiectasis. Pulmonary function tests in four patients showed combined obstructive and restrictive patterns. Three cases were confirmed to have PCD by electron microscopy. We then further extracted information from literature for those 127 PCD patients in mainland China. All of them had chronic respiratory infection. Seven cases were complicated with recurrent otitis media and 15 cases were complicated with infertility. A total of 119 patients were diagnosed with situs inversus totalis (94%). Among those 127 patients, only 9 patients' diagnosis was confirmed by electron microscopy. Four patients received sinus resection, and one patient received pulmonary lobectomy due to recurrent hemoptysis. One patient died of massive hemoptysis.

CONCLUSIONS

Being a rare disease and easily confused with uncomplicated bronchiectasis, PCD diagnosis warrants particular attention. Recurrent respiratory infection, especially situs inversus could be the most important indicator of this disease.

Recent advances in primary ciliary dyskinesia genetics

Primary ciliary dyskinesia (PCD) is a rare genetically heterogeneous disorder caused by the abnormal structure and/or function of motile cilia. The PCD diagnosis is challenging and requires a well-described clinical phenotype combined with the identification of abnormalities in ciliary ultrastructure and/or beating pattern as well as the recognition of genetic cause of the disease. Regarding the pace of identification of PCD-related genes, a rapid acceleration during the last 2-3 years is notable. This is the result of new technologies, such as whole-exome sequencing, that have been recently applied in genetic research. To date, PCD-causative mutations in 29 genes are known and the number of causative genes is bound to rise. Even though the genetic causes of approximately one-third of PCD cases still remain to be found, the current knowledge can already be used to create new, accurate genetic tests for PCD that can accelerate the correct diagnosis and reduce the proportion of unexplained cases. This review aims to present the latest data on the relations between ciliary structure aberrations and their genetic basis.

Recent advances in primary ciliary dyskinesia genetics

Primary ciliary dyskinesia (PCD) is a rare genetically heterogeneous disorder caused by the abnormal structure and/or function of motile cilia. The PCD diagnosis is challenging and requires a well-described clinical phenotype combined with the identification of abnormalities in ciliary ultrastructure and/or beating pattern as well as the recognition of genetic cause of the disease. Regarding the pace of identification of PCD-related genes, a rapid acceleration during the last 2–3 years is notable. This is the result of new technologies, such as whole-exome sequencing, that have been recently applied in genetic research. To date, PCD-causative mutations in 29 genes are known and the number of causative genes is bound to rise. Even though the genetic causes of approximately one-third of PCD cases still remain to be found, the current knowledge can already be used to create new, accurate genetic tests for PCD that can accelerate the correct diagnosis and reduce the proportion of unexplained cases. This review aims to present the latest data on the relations between ciliary structure aberrations and their genetic basis.

Diagnosis and management of primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is an inherited autosomal-recessive disorder of motile cilia characterised by chronic lung disease, rhinosinusitis, hearing impairment and subfertility. Nasal symptoms and respiratory distress usually start soon after birth, and by adulthood bronchiectasis is invariable. Organ laterality defects, usually situs inversus, occur in ∼50% of cases. The estimated prevalence of PCD is up to ∼1 per 10,000 births, but it is more common in populations where consanguinity is common. This review examines who to refer for diagnostic testing. It describes the limitations surrounding diagnosis using currently available techniques and considers whether recent advances to genotype patients with PCD will lead to genetic testing and screening to aid diagnosis in the near future. It discusses the challenges of monitoring and treating respiratory and ENT disease in children with PCD.