Primary Ciliary Dyskinesia.

Primary ciliary dyskinesia (PCD) is a rare, genetic disease characterized by dysfunctional motile cilia and abnormal mucociliary clearance, resulting in chronic sino-oto-pulmonary disease, neonatal respiratory distress, subfertility, and organ laterality defects. Over the past 2 decades, research and international collaborations have led to an improved understanding of disease prevalence, classic and variable phenotypes, novel diagnostics, genotype-phenotype correlations, long term morbidity, and innovative therapeutics. However, PCD is often underrecognized in clinical settings and the recent analyses of genetic databases suggest that only a fraction of these patients are being accurately diagnosed. Knowledge of significant advancements, from pathophysiology to the expanded range of clinical manifestations, will have important clinical impacts. These may include increasing disease recognition, improving diagnostic testing and management, and establishing an adequate pool of affected patients to enroll in upcoming clinical therapeutic trials. The objective of this state-of-the-art review is for readers to gain a greater understanding of the clinical spectrum of motile ciliopathies, cutting-edge diagnostic practices, emerging genotype-phenotype associations, and currently accepted management of people with PCD.

Recessively Inherited Deficiency of Secreted WFDC2 (HE4) Causes Nasal Polyposis and Bronchiectasis.

RATIONALE: Bronchiectasis is a pathological dilatation of the bronchi in the respiratory airways associated with environmental or genetic causes (e.g., cystic fibrosis, primary ciliary dyskinesia and primary immunodeficiency disorders), but most cases remain idiopathic. OBJECTIVES: To identify novel genetic defects in unsolved cases of bronchiectasis presenting with severe rhinosinusitis, nasal polyposis, and pulmonary Pseudomonas aeruginosa infection. METHODS: DNA was analyzed by next-generation or targeted Sanger sequencing. RNA was analyzed by quantitative PCR and single-cell RNA sequencing. Patient-derived, cells, cell cultures and secretions (mucus, saliva, seminal fluid) were analyzed by Western blotting and immunofluorescence microscopy, and mucociliary activity was measured. Blood serum was analyzed by electrochemiluminescence immunoassay. Protein structure and proteomic analyses were used to assess the impact of a disease-causing founder variant. MEASUREMENTS AND MAIN RESULTS: We identified bi-allelic pathogenic variants in WFDC2 in 11 individuals from 10 unrelated families originating from the United States, Europe, Asia, and Africa. Expression of WFDC2 was detected predominantly in secretory cells of control airway epithelium and also in submucosal glands. We demonstrate that WFDC2 is below the limit of detection in blood serum and hardly detectable in samples of saliva, seminal fluid, and airway surface liquid from WFDC2-deficient individuals. Computer simulations and deglycosylation assays indicate that the disease-causing founder variant p.Cys49Arg structurally hampers glycosylation and thus secretion of mature WFDC2. CONCLUSIONS: WFDC2 dysfunction defines a novel molecular etiology of bronchiectasis characterized by the deficiency of a secreted component of the airways. A commercially available blood test combined with genetic testing allows its diagnosis. This article is open access and distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).

A BEAT-PCD consensus statement: a core outcome set for pulmonary disease interventions in primary ciliary dyskinesia.

Background: Consistent use of reliable and clinically appropriate outcome measures is a priority for clinical trials, with clear definitions to allow comparability. We aimed to develop a core outcome set (COS) for pulmonary disease interventions in primary ciliary dyskinesia (PCD). Methods: A multidisciplinary international PCD expert panel was set up. A list of outcomes was created based on published literature. Using a modified three-round e-Delphi technique, the panel was asked to decide on relevant end-points related to pulmonary disease interventions and how they should be reported. First, inclusion of an outcome in the COS was determined. Second, the minimum information that should be reported per outcome. The third round finalised statements. Consensus was defined as ≥80% agreement among experts. Results: During the first round, experts reached consensus on four out of 24 outcomes to be included in the COS. Five additional outcomes were discussed in subsequent rounds for their use in different subsettings. Consensus on standardised methods of reporting for the COS was reached. Spirometry, health-related quality-of-life scores, microbiology and exacerbations were included in the final COS. Conclusion: This expert consensus resulted in a COS for clinical trials on pulmonary health among people with PCD.

Safety and efficacy of the epithelial sodium channel blocker idrevloride in people with primary ciliary dyskinesia (CLEAN-PCD): a multinational, phase 2, randomised, double-blind, placebo-controlled crossover trial.

BACKGROUND: Mucociliary clearance is dysfunctional in people with primary ciliary dyskinesia, resulting in the accumulation of dehydrated mucus in the airways that is difficult to clear. We undertook a study to assess the benefit on lung function of treatment with a nebulised epithelial sodium channel (ENaC) blocker, idrevloride, with or without hypertonic saline, in people with primary ciliary dyskinesia. METHODS: The CLEAN-PCD trial was a phase 2, randomised, double-blind, placebo-controlled crossover trial conducted at 32 tertiary adult and paediatric care centres and university hospitals in Canada, Denmark, Germany, Italy, the Netherlands, Poland, the UK, and the USA. People with a confirmed diagnosis of primary ciliary dyskinesia, aged 12 years or older, with a percentage of predicted FEV1 (ppFEV1) in the range of 40% to <90%, were randomly assigned in a 2:2:1:1 ratio (block size=6), stratified by ppFEV1 at screening, to one of four sequences: (1) idrevloride in hypertonic saline in treatment period 1 then hypertonic saline in treatment period 2; (2) hypertonic saline in treatment period 1 then idrevloride in hypertonic saline in treatment period 2; (3) idrevloride in treatment period 1 then placebo in treatment period 2; and (4) placebo in treatment period 1 then idrevloride in treatment period 2. The idrevloride dose was 85 µg and hypertonic saline was 4·2% NaCl. 3 mL of each study treatment was nebulised twice daily for 28 days in treatment periods 1 and 2; the two 28-day treatment periods were separated by a 28-day washout period. The primary endpoint was absolute change from baseline in ppFEV1 after 28 days. Safety assessments and reports of adverse events were made at clinic visits during each treatment period and by a follow-up telephone call 28 days after the last dose of study drug. Additionally, adverse events could be reported at a follow-up telephone call 3 days after the start of dosing and as they arose. Participants who received at least one dose of study drug were included in the safety analyses (safety set), and those who also had spirometry data were included in the efficacy analyses (full analysis set). The completed study is registered (EudraCT 2015-004917-26; ClinicalTrials.govNCT02871778). FINDINGS: Between Sep 14, 2016, and May 31, 2018, 216 patients were screened and 123 were randomly assigned to one of four crossover sequences. Across the two treatment periods, treatment with idrevloride in hypertonic saline was initiated in 80 patients and completed in 78 patients (all 78 had data available and were included in the analysis); hypertonic saline initiated in 81 patients and completed in 76 patients (75 had data available and were included in the analysis); idrevloride initiated in 37 patients and completed in 35 patients (34 had data available and were included in the analysis); and placebo initiated in 36 patients and completed in 34 patients (all 34 had data available and were included in the analysis). Greater absolute increases in ppFEV1 from baseline to 28 days of treatment were seen with idrevloride in hypertonic saline (least-squares mean absolute change from baseline 1·0 percentage points, 95% CI -0·4 to 2·4) than with hypertonic saline alone (least-squares mean absolute change from baseline of -0·5 percentage points, -2·0 to 0·9; difference 1·5 percentage points, 95% CI <0·1 to 3·0; p=0·044). There was no significant difference in ppFEV1 for the parallel comparison of idrevloride in hypertonic saline compared with placebo or the crossover comparison of idrevloride with placebo. Adverse events were similar across treatments (57 to 65% of patients). Cough occurred in a greater proportion of participants during treatments that contained idrevloride or hypertonic saline compared with placebo, and oropharyngeal pain occurred in a greater proportion of participants during idrevloride treatments than during treatment with hypertonic saline alone or placebo, whereas chest discomfort was more common during treatments that included hypertonic saline. INTERPRETATION: In this phase 2 crossover study, idrevloride in hypertonic saline was safe and associated with improved lung function over a 28-day period in people with primary ciliary dyskinesia compared with hypertonic saline alone. Larger, longer clinical studies are warranted to explore the potential benefits of idrevloride in combination with hypertonic saline in people with primary ciliary dyskinesia. FUNDING: Parion Sciences, under agreement with Vertex Pharmaceuticals.

Situs Ambiguus Is Associated With Adverse Clinical Outcomes in Children With Primary Ciliary Dyskinesia.

BACKGROUND: Primary ciliary dyskinesia (PCD) is a rare disorder of motile cilia associated with situs abnormalities. At least 12% of patients with PCD have situs ambiguus (SA), including organ laterality defects falling outside normal arrangement (situs solitus [SS]) or mirror image inversion (situs inversus totalis [SIT]). RESEARCH QUESTION: Do patients with PCD and SA achieve worse clinical outcomes compared with those with SS or SIT? STUDY DESIGN AND METHODS: This cross-sectional, multicenter study evaluated participants aged 21 years or younger with PCD. Participants were classified as having SA, including heterotaxy, or not having SA (SS or SIT). Markers of disease severity were compared between situs groups, adjusting for age at enrollment and severe CCDC39 or CCDC40 genotype, using generalized linear models and logistic and Poisson regression. RESULTS: In 397 participants with PCD (mean age, 8.4 years; range, 0.1-21), 42 patients were classified as having SA, including 16 patients (38%) with complex cardiovascular malformations or atrial isomerism, 13 patients (31%) with simple CVM, and 13 patients (31%) without cardiovascular malformations. Of these, 15 patients (36%) underwent cardiac surgery, 24 patients (57%) showed an anatomic spleen abnormality, and seven patients (17%) showed both. The remaining 355 participants did not have SA, including 152 with SIT and 203 with SS. Overall, 70 participants (17%) harbored the severe CCDC39 or CCDC40 genotype. Compared with participants without SA, those with SA showed lower median BMI z scores (P = .03), lower FVC z scores (P = .01), and more hospitalizations and IV antibiotic courses for acute respiratory infections during the 5 years before enrollment (P < .01). Participants with cardiovascular malformations requiring surgery or with anatomic spleen abnormalities showed lower median BMI z scores and more hospitalizations and IV therapies for respiratory illnesses compared with participants without SA. INTERPRETATION: Children with PCD and SA achieve worse nutritional and pulmonary outcomes with more hospitalizations for acute respiratory illnesses than those with SS or SIT combined. Poor nutrition and increased hospitalizations for respiratory infections in participants with SA and PCD are associated with cardiovascular malformations requiring cardiac surgery, splenic anomalies, or both. TRIAL REGISTRY: ClinicalTrials.gov; Nos.: NCT02389049 and NCT00323167; URL: www. CLINICALTRIALS: gov.

Airway Disease in Children with Primary Ciliary Dyskinesia: Impact of Ciliary Ultrastructure Defect and Genotype.

Rationale: Primary ciliary dyskinesia (PCD) is characterized by impaired mucociliary clearance, recurrent respiratory infections, progressive airway damage, and obstructive lung disease. Although the association of ciliary ultrastructure defect/genotype with the severity of airflow obstruction has been well characterized, their association with airway abnormalities on chest computed tomography (CT) has been minimally evaluated. Objectives: We sought to delineate the association of ciliary defect class/genotype with chest CT scores in children with PCD. Methods: Cross-sectional analysis of children with PCD (N = 146) enrolled in a prospective multicenter observational study, stratified by defect type: outer dynein arm (ODA), ODA/inner dynein arm (IDA), IDA/microtubular disorganization (MTD), and normal/near normal ultrastructure with associated genotypes. CTs were scored using the MERAGMA-PCD (Melbourne-Rotterdam Annotated Grid Morphometric Analysis for PCD), evaluating airway abnormalities in a hierarchical order: atelectasis, bronchiectasis, bronchial wall thickening, and mucus plugging/tree-in-bud opacities. The volume fraction of each component was expressed as the percentage of total lung volume. The percentage of disease was computed as the sum of all components. Regression analyses were used to describe the association between clinical predictors and CT scores. Results: Acceptable chest CTs were obtained in 141 children (71 male): 57 ODA, 20 ODA/IDA, 40 IDA/MTD, and 24 normal/near normal. The mean (standard deviation) age was 8.5 (4.6) years, forced expiratory volume in 1 second (FEV1) percent predicted was 82.4 (19.5), and %Disease was 4.6 (3.5). Children with IDA/MTD defects had a higher %Disease compared with children with ODA defects (2.71% higher [95% confidence interval (CI), 1.37-4.06; P < 0.001]), driven by higher %Mucus plugging (2.35% higher [1.43-3.26; P < 0.001]). Increasing age, lower body mass index, and lower FEV1 were associated with a higher %Disease (0.23%; 95% CI, 0.11-0.35; P < 0.001 and 0.03%; 95% CI, 0.01-0.04; P = 0.008 and 0.05%; 95% CI, 0.01-0.08; P = 0.011, respectively). Conclusions: Children with IDA/MTD defects had significantly greater airway disease on CT, primarily mucus plugging, compared with children with ODA defects.

Laterality Defects in Primary Ciliary Dyskinesia: Relationship to Ultrastructural Defect or Genotype.

Rationale: The association between organ laterality abnormalities and ciliary ultrastructural defect or genotype in primary ciliary dyskinesia is poorly understood. Objectives: To determine if there is an association between presence and/or type of laterality abnormality and ciliary ultrastructural defect or genotype. Methods: Participants with primary ciliary dyskinesia in a multicenter, prospective study were grouped based on ciliary ultrastructural defect or genotype. In a retrospective analysis of these data, the association of ciliary ultrastructural defect or genotype and likelihood of a laterality abnormality was evaluated by logistic regression adjusted for presence of two loss-of-function versus one or more not-loss-of-function variants. Results: Of 559 participants, 286 (51.2%), 215 (38.5%), and 58 (10.4%) were identified as having situs solitus, situs inversustotalis, and situs ambiguus, respectively; heterotaxy, defined as situs ambiguus with complex cardiovascular defects, was present in 14 (2.5%). Compared with the group with inner dynein arm defects with microtubular disorganization, laterality defects were more likely in the outer dynein arm defects group (odds ratio [OR], 2.07; 95% confidence interval [CI], 1.21-3.54; P < 0.01) and less likely in the normal/near normal ultrastructure group (OR, 0.04; 95% CI, 0.013-0.151; P < 0.01). Heterotaxy was present in 11 of 242 (4.5%) in the outer dynein arm defects group but 0 of 96 in the inner dynein arm defects with microtubular disorganization group (P = 0.038). Conclusion: In primary ciliary dyskinesia, risk of a laterality abnormality differs by ciliary ultrastructural defect. Pathophysiologic mechanisms underlying these differences require further exploration.

Airway Inflammation in Children with Primary Ciliary Dyskinesia.

Rationale: The role of airway inflammation in disease pathogenesis in children with primary ciliary dyskinesia (PCD) is poorly understood. Objectives: We investigated relationships between sputum inflammation measurements, age, lung function, bronchiectasis, airway infection, and ultrastructural defects in children with PCD. Methods: Spontaneously expectorated sputum was collected from clinically stable children and adolescents with PCD ages 6 years and older participating in a multicenter, observational study. Sputum protease and inflammatory cytokine concentrations were correlated with age, lung function, and chest computed tomography measures of structural lung disease, whereas differences in concentrations were compared between ultrastructural defect categories and between those with and without detectable bacterial infection. Results: Sputum from 77 children with PCD (39 females [51%]; mean [standard deviation] age, 13.9 [4.9] yr; mean [standard deviation] forced expiratory volume in 1 second [FEV1]% predicted, 80.8 [20.5]) was analyzed. Sputum inflammatory marker measurements, including neutrophil elastase activity, IL-1ß (interleukin-1ß), IL-8, and TNF-α (tumor necrosis factor α) concentrations, correlated positively with age, percentage of bronchiectasis, and percentage of total structural lung disease on computed tomography, and negatively with lung function. Correlations between neutrophil elastase concentrations and FEV1% predicted and percentage of bronchiectasis were -0.32 (95% confidence interval, -0.51 to -0.10) and 0.46 (0.14 to 0.69), respectively. Sputum neutrophil elastase, IL-1ß, and TNF-α concentrations were higher in those with detectable bacterial pathogens. Participants with absent inner dynein arm and microtubular disorganization had similar inflammatory profiles compared with participants with outer dynein arm defects. Conclusions: In this multicenter pediatric PCD cohort, elevated concentrations of sputum proteases and cytokines were associated with impaired lung function and structural damage as determined by chest computed tomography, suggesting that sputum inflammatory measurements could serve as biomarkers in PCD.

Association of Neonatal Hospital Length of Stay with Lung Function in Primary Ciliary Dyskinesia.

Rationale: Primary ciliary dyskinesia (PCD), an inherited lung disease, is characterized by abnormal ciliary function leading to progressive bronchiectasis. There is wide variability in respiratory disease severity at birth and later in life. Objectives: To evaluate the association between neonatal hospital length of stay (neonatal-LOS) and supplemental oxygen duration (SuppO2) with lung function in pediatric PCD. We hypothesized that longer neonatal-LOS and SuppO2 are associated with worse lung function (i.e., forced expiratory volume in 1 second percent predicted [FEV1pp]). Methods: We performed a secondary analysis of the Genetic Disorders of Mucociliary Clearance Consortium prospective longitudinal multicenter cohort study. Participants enrolled, during 2006-2011, were <19 years old with a confirmed PCD diagnosis and followed annually for 5 years. The exposure variables were neonatal-LOS and SuppO2, counted in days since birth. The outcome, FEV1pp, was measured annually by spirometry. The associations of neonatal-LOS and SuppO2 with FEV1pp were evaluated with a linear mixed-effects model with repeated measures and random intercepts, adjusted for age and ciliary ultrastructural defects. Results: Included were 123 participants (male, 47%; mean enrollment age, 8.3 yr [range, 0 to 18 yr]) with 578 visits (median follow-up, 5 yr). The median neonatal-LOS was 9 d (range, 1 to 90 d), and median SuppO2 was 5 d (range, 0 to 180 d). Neonatal-LOS was associated with worse lung function (-0.27 FEV1pp/d [95% confidence interval, -0.53 to -0.01]; P = 0.04). SuppO2 was not associated with lung function. Conclusions: Neonatal-LOS is associated with worse lung function in pediatric PCD, independent of age and ultrastructural defects. Future research on the mechanisms of neonatal respiratory distress and its management may help us understand the variability of lung health outcomes in PCD.

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

BACKGROUND: Infants with cystic fibrosis (CF) develop structural lung disease early in life, and viral infections are associated with progressive lung disease. We hypothesized that the presence of respiratory viruses would be associated with structural lung disease on computed tomography (CT) of the chest in infants with CF. METHODS: Infants with CF were enrolled before 4 months of age. Multiplex PCR assays were performed on nasal swabs to detect respiratory viruses during routine visits and when symptomatic. Participants underwent CT imaging at approximately 12 months of age. Associations between Perth-Rotterdam Annotated Grid Morphometric Analysis for CF (PRAGMA-CF) CT scores and respiratory viruses and symptoms were assessed with Spearman correlation coefficients. RESULTS: Sixty infants were included for analysis. Human rhinovirus was the most common virus detected, on 28% of tested nasal swabs and in 85% of participants. The median (IQR) extent of lung fields that was healthy based on PRAGMA-CF was 98.7 (0.8)%. There were no associations between PRAGMA-CF and age at first virus, or detection of any virus, including rhinovirus, respiratory syncytial virus, or parainfluenza. The extent of airway wall thickening was associated with ever having wheezed (ρ = 0.31, p = 0.02) and number of encounters with cough (ρ = 0.25, p = 0.0495). CONCLUSIONS: Infants with CF had minimal structural lung disease. We did not find an association between respiratory viruses and CT abnormalities. Wheezing and frequency of cough were associated with early structural changes.

Emerging Genotype-Phenotype Relationships in Primary Ciliary Dyskinesia.

Primary ciliary dyskinesia (PCD) is a rare inherited condition affecting motile cilia and leading to organ laterality defects, recurrent sino-pulmonary infections, bronchiectasis, and severe lung disease. Research over the past twenty years has revealed variability in clinical presentations, ranging from mild to more severe phenotypes. Genotype and phenotype relationships have emerged. The increasing availability of genetic panels for PCD continue to redefine these genotype-phenotype relationships and reveal milder forms of disease that had previously gone unrecognized.

Hyperinflation is associated with increased respiratory rate and is a more sensitive measure of cystic fibrosis lung disease during infancy compared to forced expiratory measures.

BACKGROUND: The goal of this study was to identify clinical features associated with abnormal infant pulmonary function tests (iPFTs), specifically functional residual capacity (FRC), in infants with cystic fibrosis (CF) diagnosed via newborn screen (NBS). We hypothesized that poor nutritional status in the first 6-12 months would be associated with increased FRC at 12-24 months. METHODS: This study utilized a combination of retrospectively and prospectively collected data from ongoing research studies and iPFTs performed for clinical indications. Demographic and clinical features were obtained from the electronic medical record. Forced expiratory flows and volumes were obtained using the raised volume rapid thoracoabdominal technique (RVRTC) and FRC was measured via plethysmography. RESULTS: A total of 45 CF NBS infants had iPFTs performed between 12 and 24 months. Mean forced vital capacity, forced expiratory volume in 0.5 s, and forced expiratory flows were all within normal limits. In contrast, the mean FRC z-score was 2.18 (95% confidence interval [CI] = 1.48, 2.88) and the mean respiratory rate (RR) z-score was 1.42 (95% CI = 0.95, 1.89). There was no significant association between poor nutritional status and abnormal lung function. However, there was a significant association between higher RR and increased FRC, and a RR cutoff of 36 breaths/min resulted in 92% sensitivity to detect hyperinflation with 32% specificity. CONCLUSION: These results suggest that FRC is a more sensitive measure of early CF lung disease than RVRTC measurements and that RR may be a simple, noninvasive clinical marker to identify CF NBS infants with hyperinflation.

Advances in the Diagnosis and Treatment of Primary Ciliary Dyskinesia: A Review.

IMPORTANCE: Primary ciliary dyskinesia (PCD) is a rare, inherited condition involving motile cilia that line the upper and lower respiratory tracts, leading to chronic infections of the paranasal sinuses, middle ear, and bronchi that begin during infancy. Unfortunately, despite its early presentation, PCD is often recognized late. OBSERVATIONS: People with PCD have diverse clinical manifestations, including chronic upper and lower respiratory tract disease, laterality defects, and subfertility. Through efforts of multinational clinical collaboratives, 4 cardinal features have been described that identify people who likely have PCD: unexplained neonatal respiratory distress, left-right laterality defects, daily wet cough, and nonseasonal rhinosinusitis beginning before 6 months of age. Recent advances in the understanding of the genetics and pathogenesis of the disease have led to a revolution in the approach to screening and diagnostic testing. Moreover, PCD has a broad clinical spectrum, and genotype-phenotype associations are beginning to be recognized. CONCLUSIONS AND RELEVANCE: A high index of suspicion remains critical in diagnosing PCD. Children who have at least 2 of the major clinical features should be considered for further evaluation. Nevertheless, while newer tools have improved diagnostic capabilities, there is no single test that will diagnose every person with the disease. In people suspected of having PCD, nasal nitric oxide measurement is a useful screen, followed by diagnostic genetic testing and if negative, ciliary ultrastructural analysis. Despite otolaryngologic manifestations being common in infancy and persisting into adulthood, they have been understudied. Indeed, there are few randomized clinical trials examining the medicosurgical approaches to respiratory disease.

Lung inflammation and simulated airway resistance in infants with cystic fibrosis.

Cystic fibrosis (CF) is characterized by small airway disease; but central airways may also be affected. We hypothesized that airway resistance estimated from computational fluid dynamic (CFD) methodology in infants with CF was higher than controls and that early airway inflammation in infants with CF is associated with airway resistance. Central airway models with a median of 51 bronchial outlets per model (interquartile range 46,56) were created from chest computed tomography scans of 18 infants with CF and 7 controls. Steady state airflow into the trachea was simulated to estimate central airway resistance in each model. Airway resistance was increased in the full airway models of infants with CF versus controls and in models trimmed to 33 bronchi. Airway resistance was associated with markers of inflammation in bronchoalveolar lavage fluid obtained approximately 8 months earlier but not with markers obtained at the same time. In conclusion, airway resistance estimated by CFD modeling is increased in infants with CF compared to controls and may be related to early airway inflammation.

Pediatric lung transplantation: Dynamics of the microbiome and bronchiolitis obliterans in cystic fibrosis.

BACKGROUND: Compositional changes in the microbiome are associated with the development of bronchiolitis obliterans (BO) after lung transplantation (LTx) in adults with cystic fibrosis (CF). The association between the lower airway bacterial community and BO after LTx in children with CF remains largely unexplored and is possibly influenced by frequent antibiotic therapy. The objectives of this study were to examine the relationship between bacterial community dynamics and the development of BO and analyze antibiotic resistance trends in children after LTx for CF. METHODS: For 3 years from the time of transplant, 12 LTx recipients were followed longitudinally, with 5 subjects developing BO during the study period. A total of 82 longitudinal bronchoalveolar lavage samples were collected during standard of care bronchoscopies. Metagenomic shotgun sequencing was performed on the extracted microbial DNA from bronchoalveolar lavage specimens. Taxonomic profiling was constructed using WEVOTE pipeline. The longitudinal association between development of BO and temporal changes in bacterial diversity and abundance were evaluated with MetaLonDA. The analysis of antibiotic resistance genes was performed with the ARGs-OAP v2.0 pipeline. RESULTS: All recipients demonstrated a Proteobacteria-predominant lower airways community. Temporal reduction in bacterial diversity was significantly associated with the development of BO and associated with neutrophilia and antibiotic therapy. Conversely, an increasing abundance of the phylum Actinobacteria and the orders Neisseriales and Pseudonocardiales in the lower airways was significantly associated with resilience to BO. A more diverse bacterial community was related to a higher expression of multidrug resistance genes and increased proteobacterial abundance. CONCLUSIONS: Decreased diversity within bacterial communities may suggest a contribution to pediatric lung allograft rejection in CF.

Early Diagnosis and Intervention in Cystic Fibrosis: Imagining the Unimaginable.

Cystic fibrosis is the most common life-shortening genetic disease affecting Caucasians, clinically manifested by fat malabsorption, poor growth and nutrition, and recurrent sinopulmonary infections. Newborn screening programs for cystic fibrosis are now implemented throughout the United States and in many nations worldwide. Early diagnosis and interventions have led to improved clinical outcomes for people with cystic fibrosis. Newer cystic fibrosis transmembrane conductance regulator potentiators and correctors with mutation-specific effects have increasingly been used in children, and these agents are revolutionizing care. Indeed, it is possible that highly effective modulator therapy used early in life could profoundly affect the trajectory of cystic fibrosis lung disease, and primary prevention may be achievable.

Prevention of cystic fibrosis: The beginning of the end?

Prenatal and postnatal treatment with a CFTR modifier attenuates pathological changes in a ferret model of cystic fibrosis (Sun et al., this issue).