Homozygous loss-of-function mutations in MNS1 cause laterality defects and likely male infertility

The clinical spectrum of ciliopathies affecting motile cilia spans impaired mucociliary clearance in the respiratory system, laterality defects including heart malformations, infertility and hydrocephalus. Using linkage analysis and whole exome sequencing, we identified two recessive loss-of-function MNS1 mutations in five individuals from four consanguineous families: 1) a homozygous nonsense mutation p.Arg242* in four males with laterality defects and infertility and 2) a homozygous nonsense mutation p.Gln203* in one female with laterality defects and recurrent respiratory infections additionally carrying homozygous mutations in DNAH5. Consistent with the laterality defects observed in these individuals, we found Mns1 to be expressed in mouse embryonic ventral node. Immunofluorescence analysis further revealed that MNS1 localizes to the axonemes of respiratory cilia as well as sperm flagella in human. In-depth ultrastructural analyses confirmed a subtle outer dynein arm (ODA) defect in the axonemes of respiratory epithelial cells resembling findings reported in Mns1-deficient mice. Ultrastructural analyses in the female carrying combined mutations in MNS1 and DNAH5 indicated a role for MNS1 in the process of ODA docking (ODA-DC) in the distal respiratory axonemes. Furthermore, co-immunoprecipitation and yeast two hybrid analyses demonstrated that MNS1 dimerizes and interacts with the ODA docking complex component CCDC114. Overall, we demonstrate that MNS1 deficiency in humans causes laterality defects (situs inversus) and likely male infertility and that MNS1 plays a role in the ODA-DC assembly.

Lung function in patients with primary ciliary dyskinesia: an iPCD Cohort study

Primary ciliary dyskinesia (PCD) has been considered a relatively mild disease, especially compared to cystic fibrosis (CF), but studies on lung function in PCD patients have been few and small.This study compared lung function from spirometry of PCD patients to normal reference values and to published data from CF patients. We calculated z-scores and % predicted values for forced expiratory volume in 1 s (FEV₁) and forced vital capacity (FVC) using the Global Lung Function Initiative 2012 values for 991 patients from the international PCD Cohort. We then assessed associations with age, sex, country, diagnostic certainty, organ laterality, body mass index and age at diagnosis in linear regression models. Lung function in PCD patients was reduced compared to reference values in both sexes and all age groups. Children aged 6-9 years had the smallest impairment (FEV₁ z-score -0.84 (-1.03 to -0.65), FVC z-score -0.31 (-0.51 to -0.11)). Compared to CF patients, FEV₁ was similarly reduced in children (age 6-9 years PCD 91% (88-93%); CF 90% (88-91%)), but less impaired in young adults (age 18-21 years PCD 79% (76-82%); CF 66% (65-68%)). The results suggest that PCD affects lung function from early in life, which emphasises the importance of early standardised care for all patients.

Development of a novel device for objective respiratory rate measurement in low-resource settings

Objective

To evaluate a novel device (Respimometer) for objective measurement of respiratory rate (RR) in low-resource settings.

Design

Description of prototype development, with proof-of-concept pilot field study at four paediatric healthcare facilities in Butembo, Democratic Republic of the Congo (DRC). The instrument was tested in healthy adult volunteers (n=10) and Congolese children (n=42) and compared with timed breaths (adults) or by reference comparator capnography (children). Correlation and Bland-Altman plots were generated for paired measurements.

Results

The Respimometer is shaped like an oral thermometer and is placed in the mouth of the participants. RR is measured by thermistors positioned at the nasal outlet, which detect the temperature change between inhaled and exhaled breaths. In adult volunteers, the correlation coefficient between the delivered RR and the Respimometer measurement was median 0.992 (IQR 0.980–0.999). Measurement bias was −0.50 min−1 (95% CI −1.1 to +0.07, p=0.093), with upper and lower limits of agreement of −5.2 min−1 and 4.2 min−1, respectively. Among Congolese children, there was no evidence of bias: mean difference in RR +1.0 min−1 (95% CI −2.1 to +4.1, p=0.52). The upper and lower limits of agreement were −18 and +20 min−1, respectively.

Conclusion

The Respimometer can accurately measure the RR in healthy adults and children in DRC. A simple and accurate instrument could facilitate the diagnosis of pneumonia by community health workers in low-income and middle-income countries, leading to reduced pneumonia-related deaths.

Mutations in C11orf70 Cause Primary Ciliary Dyskinesia with Randomization of Left/Right Body Asymmetry Due to Defects of Outer and Inner Dynein Arms

Primary ciliary dyskinesia (PCD) is characterized by chronic airway disease, male infertility, and randomization of the left/right body axis as a result of defects of motile cilia and sperm flagella. We identified loss-of-function mutations in the open-reading frame C11orf70 in PCD individuals from five distinct families. Transmission electron microscopy analyses and high-resolution immunofluorescence microscopy demonstrate that loss-of-function mutations in C11orf70 cause immotility of respiratory cilia and sperm flagella, respectively, as a result of the loss of axonemal outer (ODAs) and inner dynein arms (IDAs), indicating that C11orf70 is involved in cytoplasmic assembly of dynein arms. Expression analyses of C11orf70 showed that C11orf70 is expressed in ciliated respiratory cells and that the expression of C11orf70 is upregulated during ciliogenesis, similar to other previously described cytoplasmic dynein-arm assembly factors. Furthermore, C11orf70 shows an interaction with cytoplasmic ODA/IDA assembly factor DNAAF2, supporting our hypothesis that C11orf70 is a preassembly factor involved in the pathogenesis of PCD. The identification of additional genetic defects that cause PCD and male infertility is of great importance for the clinic as well as for genetic counselling.

Evaluation of clinically and physiologically atypical asthma: If it doesn't wheeze it may still be asthma

OBJECTIVE

Children with asthma-like symptoms may not clinically wheeze. The objectives of this study were to evaluate if children, without physician-documented wheeze, wheeze during bronchial-challenge-testing (BCT), and if measurements of O₂Sat and respiratory rate during BCT improve the BCT sensitivity?

METHODS

Seven hundred and twenty-four children, who were referred for suspicion of asthma, performed a BCT. Positive BCT was determined by the provocation concentration (PC) which resulted in a 20% decrease in FEV₁ (PC₂₀), (in those who were able to perform spirometry, group B), or (in those unable to perform spirometry, group A) a 50% increase in respiratory rate (PC_RR), or a 5% decrease in oxygen-saturation (PC_O2-Sat) or appearance of wheezing (PC_wheeze).

RESULTS

Five hundred and seven BCTs were positive: group A n = 89 age, median (IQR), 3 (2.5-3.7) years (17.6%), were unable to perform spirometry, and group B n = 418 age 10.7 (6.8-15.6) years (82.4%), were able to perform spirometry. Children, without physician-documented wheeze in the total population (groups A plus B), were more likely (65.5%) to have a positive BCT without wheeze compared with those with physician-documented wheeze (41.0%, P < 0.001). In group A, adding PC_RR and PC_O2-Sat increased BCT sensitivity by 23.6%.

CONCLUSIONS

Many children in both groups did not wheeze despite reaching BCT endpoints. Children without physician-documented wheeze tended not to wheeze at BCT. This may result in clinical under-diagnosis of asthma if depending on the presence of wheeze. In young children, adding PC_RR and PC_O2-Sat substantially increases BCT sensitivity and may improve asthma diagnosis.

Growth and nutritional status, and their association with lung function: a study from the international Primary Ciliary Dyskinesia Cohort

Chronic respiratory disease can affect growth and nutrition, which can influence lung function. We investigated height, body mass index (BMI), and lung function in patients with primary ciliary dyskinesia (PCD).In this study, based on the international PCD (iPCD) Cohort, we calculated z-scores for height and BMI using World Health Organization (WHO) and national growth references, and assessed associations with age, sex, country, diagnostic certainty, age at diagnosis, organ laterality and lung function in multilevel regression models that accounted for repeated measurements.We analysed 6402 measurements from 1609 iPCD Cohort patients. Height was reduced compared to WHO (z-score -0.12, 95% CI -0.17 to -0.06) and national references (z-score -0.27, 95% CI -0.33 to -0.21) in male and female patients in all age groups, with variation between countries. Height and BMI were higher in patients diagnosed earlier in life (p=0.026 and p<0.001, respectively) and closely associated with forced expiratory volume in 1 s and forced vital capacity z-scores (p<0.001).Our study indicates that both growth and nutrition are affected adversely in PCD patients from early life and are both strongly associated with lung function. If supported by longitudinal studies, these findings suggest that early diagnosis with multidisciplinary management and nutritional advice could improve growth and delay disease progression and lung function impairment in PCD.

Clinical impact of Pseudomonas aeruginosa colonization in patients with Primary Ciliary Dyskinesia

BACKGROUND

Airway infections in Primary Ciliary Dyskinesia (PCD) are caused by different microorganisms, including pseudomonas aeruginosa (PA). The aim of this study was to investigate the association of PA colonization and the progression of lung disease in PCD.

METHODS

Data from 11PCD centers were retrospectively collected from 2008 to 2013. Patients were considered colonized if PA grew on at least two separate sputum cultures; otherwise, they were classified as non-colonized. These two groups were compared on the lung function computed tomography (CT) Brody score and other clinical parameters.

RESULTS

Data were available from 217 patients; 60 (27.6%) of whom were assigned to the colonized group. Patients colonized with PA were older and were diagnosed at a later age. Baseline forced expiratory volume at 1 s (FEV₁) was lower in the colonized group (72.4 ± 22.0 vs. 80.1 ± 18.9, % predicted, p = 0.015), but FEV₁ declined throughout the study period was similar in both groups. The colonized group had significantly worse CT-Brody scores (36.07 ± 24.38 vs. 25.56 ± 24.2, p = 0.034). A subgroup analysis with more stringent definitions of colonization revealed similar results.

CONCLUSIONS

Lung PA colonization in PCD is associated with more severe disease as shown by the FEV₁ and CT score. However, the magnitude of decline in pulmonary function was similar in colonized and non-colonized PCD patients.

DNAH11 Localization in the Proximal Region of Respiratory Cilia Defines Distinct Outer Dynein Arm Complexes

Primary ciliary dyskinesia (PCD) is a recessively inherited disease that leads to chronic respiratory disorders owing to impaired mucociliary clearance. Conventional transmission electron microscopy (TEM) is a diagnostic standard to identify ultrastructural defects in respiratory cilia but is not useful in approximately 30% of PCD cases, which have normal ciliary ultrastructure. DNAH11 mutations are a common cause of PCD with normal ciliary ultrastructure and hyperkinetic ciliary beating, but its pathophysiology remains poorly understood. We therefore characterized DNAH11 in human respiratory cilia by immunofluorescence microscopy (IFM) in the context of PCD. We used whole-exome and targeted next-generation sequence analysis as well as Sanger sequencing to identify and confirm eight novel loss-of-function DNAH11 mutations. We designed and validated a monoclonal antibody specific to DNAH11 and performed high-resolution IFM of both control and PCD-affected human respiratory cells, as well as samples from green fluorescent protein (GFP)-left-right dynein mice, to determine the ciliary localization of DNAH11. IFM analysis demonstrated native DNAH11 localization in only the proximal region of wild-type human respiratory cilia and loss of DNAH11 in individuals with PCD with certain loss-of-function DNAH11 mutations. GFP-left-right dynein mice confirmed proximal DNAH11 localization in tracheal cilia. DNAH11 retained proximal localization in respiratory cilia of individuals with PCD with distinct ultrastructural defects, such as the absence of outer dynein arms (ODAs). TEM tomography detected a partial reduction of ODAs in DNAH11-deficient cilia. DNAH11 mutations result in a subtle ODA defect in only the proximal region of respiratory cilia, which is detectable by IFM and TEM tomography.

Mutation of serine/threonine protein kinase 36 (STK36) causes primary ciliary dyskinesia with a central pair defect

Primary ciliary dyskinesia (PCD) is a genetic condition of impaired ciliary beating, characterized by chronic infections of the upper and lower airways and progressive lung failure. Defects of the outer dynein arms are the most common cause of PCD. In about half of the affected individuals, PCD occurs with situs inversus (Kartagener syndrome). A minor PCD subgroup including defects of the radial spokes (RS) and central pair (CP) is hallmarked by the absence of laterality defects, subtle beating abnormalities, and unequivocally apparent ultrastructural defects of the ciliary axoneme, making their diagnosis challenging. We identified homozygous loss-of-function mutations in STK36 in one PCD-affected individual with situs solitus. Transmission electron microscopy analysis demonstrates that STK36 is required for cilia orientation in human respiratory epithelial cells, with a probable localization of STK36 between the RS and CP. STK36 screening can now be included for this rare and difficult to diagnose PCD subgroup.

Workshop Report: Aerosol Delivery to Spontaneously Breathing Tracheostomized Patients

The number of pediatric and adult patients requiring tracheostomy has increased. Many of them require aerosol therapy as part of their treatment. Practitioners have little guidance on how to optimize drug delivery in this population. The following is a report of a workshop dedicated to review the current status of aerosol delivery to spontaneously breathing tracheostomized patients and to provide practice recommendations.

The international primary ciliary dyskinesia cohort (iPCD Cohort): methods and first results

Data on primary ciliary dyskinesia (PCD) epidemiology is scarce and published studies are characterised by low numbers. In the framework of the European Union project BESTCILIA we aimed to combine all available datasets in a retrospective international PCD cohort (iPCD Cohort).

We identified eligible datasets by performing a systematic review of published studies containing clinical information on PCD, and by contacting members of past and current European Respiratory Society Task Forces on PCD. We compared the contents of the datasets, clarified definitions and pooled them in a standardised format.

As of April 2016 the iPCD Cohort includes data on 3013 patients from 18 countries. It includes data on diagnostic evaluations, symptoms, lung function, growth and treatments. Longitudinal data are currently available for 542 patients. The extent of clinical details per patient varies between centres. More than 50% of patients have a definite PCD diagnosis based on recent guidelines. Children aged 10–19 years are the largest age group, followed by younger children (≤9 years) and young adults (20–29 years).

This is the largest observational PCD dataset available to date. It will allow us to answer pertinent questions on clinical phenotype, disease severity, prognosis and effect of treatments, and to investigate genotype–phenotype correlations.

The iPCD Cohort offers a unique opportunity to study PCD in an international retrospective cohort of >3000 patientshttp://ow.ly/rn0m304Jgsu

Collecting clinical data in primary ciliary dyskinesia- challenges and opportunities

Rationale: Primary ciliary dyskinesia (PCD) is under diagnosed and underestimated. Most clinical research has used some form of questionnaires to capture data but none has been critically evaluated particularly with respect to its end-user feasibility and utility.

Objective: To critically appraise a clinical data collection questionnaire for PCD used in a large national PCD consortium in order to apply conclusions in future PCD research.

Methods: We describe the development, validation and revision process of a clinical questionnaire for PCD and its evaluation during a national clinical PCD study with respect to data collection and analysis, initial completion rates and user feedback.

Results: 14 centers participating in the consortium successfully completed the revised version of the questionnaire for 173 patients with various completion rates for various items. While content and internal consistency analysis demonstrated validity, there were methodological deficiencies impacting completion rates and end-user utility. These deficiencies were addressed resulting in a more valid questionnaire.

Conclusions: Our experience may be useful for future clinical research in PCD. Based on the feedback collected on the questionnaire through analysis of completion rates, judgmental analysis of the content, and feedback from experts and end users, we suggest a practicable framework for development of similar tools for various future PCD research.

Evaluating Caregiver Management of Asthma Exacerbations at Home

BACKGROUND: Effective management of asthma in the home setting requires asthma education from a health professional along with written plans for asthma exacerbations. These approaches can result in fewer acute asthma visits, fewer missed school days and better asthma control. Nevertheless, a large number of asthma exacerbations result in emergency department visits or hospital admission. Several studies suggest that care-givers may lack the knowledge, the skills, or the confidence to provide care for their child during an asthma exacerbation.

OBJECTIVES: The objective of this study was to determine the proportion of caregivers who appropriately manage their child’s acute asthma at home (as per the 2014 Global Initiative for Asthma guidelines) and to identify factors that may be associated with deviations from these guidelines.

DESIGN/METHODS: We studied caregivers of children who are known to suffer from asthma using a paper based questionnaire in a single-center outpatient asthma clinic. Caregivers of children aged 3 to 17 years with a physician made diagnosis of asthma greater than 6 months in duration were included. To avoid a diagnosis of bronchiolitis from our study group, new consultations for wheezing or cough without a prior diagnosis of asthma, and less than 3 years of age were excluded. For statistical analysis, we used Excel and STATA 11 for the z test of proportions and comparison of means with a one way ANOVA (a = 0.05).

RESULTS: Among the 45 caregivers surveyed, most had children with well controlled asthma based on low scores from a standard asthma control test and a limited number of emergency room visits (1.5±0.1 per year). Sixty-four percent of caregivers were able to correctly identify the initial treatment with 2 puffs of Ventolin; however, 54% did not choose repeating Ventolin treatment within 20 minutes for ongoing symptoms. Moreover, only 58% of caregivers had ever been given a written asthma action plan. Caregivers had a higher degree of confidence (reported on a scale of 1-10) in initiating management (8.9±1.5) compared with stopping treatment (7.3±2.5).

CONCLUSION: Despite a high degree of confidence in starting treatment for asthma attacks, half of the caregivers surveyed identified inappropriate steps to manage asthma exacerbations at home. Providing a written asthma action plan may improve caregiver confidence and knowledge in asthma exacerbation management. However, routine assessment and review by a healthcare professional is essential in reinforcing recommended behaviours for home asthma management.

Dry-Powder Inhaler Delivery of Aerosolized Tobramycin with in Vitro Models of Tracheostomized Paediatric Patients

BACKGROUND: Tracheostomies are not uncommon in the pediatric population and are necessary in situations such as long-term cardiorespiratory compromise or fixed airway obstructions. Delivery of aerosolized medication allows for directed therapy to the lungs and is an important component of therapeutic management. However there is surprisingly little literature that quantifies delivery of aerosol medication through tracheostomies. During Pseudomonas aeruginosa respiratory infections, tobramycin is frequently administered using nebulizers, like the PARI LC Plus (LC Plus), which are known to have drawbacks, most notably the time burden. Dry-powder inhalers, like the TOBI Podhaler (Podhaler), can deliverhigher payloads of medication to the airway and in a shorter time. Currently no data exists that evaluates aerosol delivery of drypower inhalers through tracheostomies.

OBJECTIVES: The aim of the study is to investigate and quantify the amount of aerosolized tobramycin delivered to the lungs of in vitro trache-ostomized spontaneously breathing pediatric patient models when using the Podhaler in comparison to the current gold-standard, the LC Plus nebulizer.

DESIGN/METHODS: In vitro tracheostomized models of a 6- and 12-year old trachea were created. Aerosol was delivered to the tracheos-tomy models with the LC Plus and Podhaler, using their respective breathing patterns. Aerosolized medication was captured on a Respirgard II filter placed at the distal end of the trachea (lung filter), the amount was quantified using a colorimetric tobramycin assay and expressed as a percent charge of emitted dose. Drug trapped on the lung filter represented the amount of aerosol delivered to the respiratory tract. Three devices of each type were tested in triplicate to ensure repeatability.

RESULTS: A total of 36 runs (LC Plus: 18, Podhaler: 18) were completed and demonstrated the Podhaler’s consistent outperformance of the LC Plus. The results are expressed as mean ± standard deviation in percent charge (LC Plus vs. Podhaler); all runs (24.1±3.7 vs. 86.6±8.7), 6-year old model (23.2±2.6 vs. 82.1±9.9) and 12-year old (24.1±4.5 vs. 86.6±4.2). The results were statistically significant (P-values &lt;&lt;&lt; 0.01), based on an unpaired t-tests due to unequal variance.

CONCLUSION: The study’s findings demonstrate that the Podhaler significantly outperformed the LC plus in delivering tobramycin to in vitro pediatric tracheostomized models. These results can be generalized to the tracheostomized adult population, and suggest that tobramycin delivery using the Podhaler is a feasible option and a future clinical study is warranted.

Systematic Analysis of CCNO Variants in a Defined Population: Implications for Clinical Phenotype and Differential Diagnosis

Reduced generation of multiple motile cilia (RGMC) is a novel chronic destructive airway disease within the group of mucociliary clearance disorders with only few cases reported. Mutations in two genes, CCNO and MCIDAS, have been identified as a cause of this disease, both leading to a greatly reduced number of cilia and causing impaired mucociliary clearance. This study was designed to identify the prevalence of CCNO mutations in Israel and further delineate the clinical characteristics of RGMC. We analyzed 170 families with mucociliary clearance disorders originating from Israel for mutations in CCNO and identified two novel mutations (c.165delC, p.Gly56Alafs*38; c.638T>C, p.Leu213Pro) and two known mutations in 15 individuals from 10 families (6% prevalence). Pathogenicity of the missense mutation (c.638T>C, p.Leu213Pro) was demonstrated by functional analyses in Xenopus. Combining these 15 patients with the previously reported CCNO case reports revealed rapid deterioration in lung function, an increased prevalence of hydrocephalus (10%) as well as increased female infertility (22%). Consistent with these findings, we demonstrate that CCNO expression is present in murine ependyma and fallopian tubes. CCNO is mutated more frequently than expected from the rare previous clinical case reports, leads to severe clinical manifestations, and should therefore be considered an important differential diagnosis of mucociliary clearance disorders.