Primary Ciliary Dyskinesia

Assessing Olfactory Acuity in Primary Ciliary Dyskinesia with the RSPH4A Founder Mutation

Background/Objectives: Primary Ciliary Dyskinesia (PCD) is a rare genetic condition characterized by compromised mucociliary clearance and chronic respiratory manifestations. Anosmia, or the loss of smell, is a lesser-known but clinically relevant symptom that can significantly impact patient safety, nutritional status, and the overall quality of life. The RSPH4A (c.921+3_921+6delAAGT) founder mutation is highly prevalent among Puerto Rican individuals with PCD and may carry distinct phenotypic implications. This study aimed to evaluate olfactory function in Puerto Rican PCD patients with this mutation using the Brief Smell Identification Test (BSIT®) and to assess associations with age and sex. Methods: We conducted a case-control study involving 30 participants, including 15 PCD patients with genetically confirmed RSPH4A mutations and 15 age- and sex-matched healthy controls. All participants completed the BSIT, and BSIT scores were compared by diagnosis, sex, and age. Results: PCD patients had significantly lower BSIT scores than controls (p = 0.0015). When stratified by sex, both male (p = 0.0289) and female (p = 0.0178) PCD patients demonstrated significantly lower BSIT scores compared to their respective healthy counterparts. Regression analysis showed a significant inverse correlation between age and BSIT score in the PCD group (r2 = 0.2873; p = 0.0395), while no such relationship was observed in controls (r2 = 0.0096; p = 0.7283). Among PCD patients, age-related decline in olfactory function was more pronounced in females (r2 = 0.71; p = 0.005) than in males (r2 = 0.31; p = 0.25). Conclusions: These findings demonstrate that the RSPH4A founder mutation is associated with measurable olfactory impairment in PCD patients, particularly in females and with advancing age. The routine assessment of olfactory function should be considered in the clinical evaluation of patients with PCD, as anosmia may represent a key phenotypic feature and contribute to disease burden.

An Innovative Transmission Electron Microscopy-Based Ultrastructural Imaging Methodology for the Diagnosis of Respiratory Ciliary Disorders

Transmission electron microscopy is a classical methodology for diagnosing many ciliary disorders. However, heterogeneity in sampling, low yield of ciliary epithelium by cytology, improper fixation, and different orientations of cylindrical axes of cilia section create difficulties in achieving the appropriate ciliary ultrastructure for diagnosis. We have reported an improvement in the number and proportion of ciliary epithelial cells up to 32 times. These include cleaning the nose before sample collection, changing the collection brush used for the cervical cytology (eight times), and paired nose collection (four times). We have optimized the primary fixation to preserve cilia ultrastructure, modified ultra-sectioning, and improved the number of reportable ultrastructure of cilia by tilting the sample angles of α axes (up to ±40°) and β axes (up to ±25°). These optimizations resulted in ∼20 times more reportable cilia (parallel to cylindrical axes concerning the electron beam, clearly visible dynein arms, 9 + 2 patterns, and compound cilia). This resulted in an enhanced diagnosis of ciliary disorders, up to 67% (reported in 135 among 200 patients), compared with 5% achieved using conventional routine practices at our facility. With certain advancements in conventional method, we could achieve an accuracy comparable to the new sophisticated cryo-electron tomography imaging.

Primary ciliary dyskinesia: Aetiology, diagnosis and clinical management

Primary ciliary dyskinesia (PCD) is a rare genetic disorder characterised by abnormal function of motile cilia. The condition usually manifests in early life with neonatal distress, chronic sinopulmonary disease and organ laterality disorders. In adults, it is an underdiagnosed cause of bronchiectasis as well as subfertility. This review provides an overview of PCD for clinicians. We discuss its aetiology, its presentation, how it is diagnosed and its multidisciplinary clinical management.

Impact of Aerobic Exercise on Oxygenation, Pulmonary Function, and Nasal Nitric Oxide in Primary Ciliary Dyskinesia

Background

Primary Ciliary Dyskinesia (PCD) is a rare genetic disorder characterized by impaired mucociliary clearance, resulting in chronic respiratory complications. While exercise benefits respiratory health, its impacts on PCD remain understudied.

Objective

The objective of this study was to assess how moderate aerobic exercise influences FEV1, SpO2, and nNO levels in PCD patients, with a focus on short-term post-exercise changes.

Methods

This is a matched case-control pilot study involving 12 PCD patients homozygous for the RSPH4A (c.921+3_921+6del) mutation and 12 healthy controls (HC). Baseline FEV1, SpO2, and nNO levels were measured before participants underwent a six-minute exercise challenge test (ECT) on a stationary bicycle. Post-exercise measurements included FEV1 at 5, 10, 15, and 20 minutes, nNO after final spirometry, and SpO2 at 5 minutes.

Results

The PCD group experienced a significant increase in SpO2 from 95.5% ± 2.1 to 97.7% ± 1.5 post-exercise (p < 0.05), while the HC group had stable SpO2 levels with a minor increase from 97.9% ± 1.5 to 98.9% ± 1.4 (p = 0.14). No significant changes in FEV1 or nNO levels were observed post-exercise in either group. One HC participant exhibited exercise-induced bronchoconstriction.

Conclusion

Aerobic exercise improves oxygenation in PCD patients without adverse effects on pulmonary function or nNO levels. Further research is necessary due to the small sample size and genetic homogeneity to confirm these findings and evaluate long-term outcomes. Moreover, this pilot study highlights the safety and potential respiratory benefits of aerobic exercise in PCD patients, supporting further investigation into its role in clinical management.

Therapies Used by Children With Primary Ciliary Dyskinesia: A Natural History Study

INTRODUCTION

Primary ciliary dyskinesia (PCD) management has not been systematically evaluated and is largely empirical.

METHODS

Pediatric participants with PCD were enrolled in a prospective, longitudinal, multicenter, observational study. Therapies were recorded at annual visits and categorized by type. Age-related trends in prevalence of therapies were described by serial cross-sectional analyses. Generalized estimating equations analyzed covariates affecting prevalence of certain therapies and whether these covariates impacted oral antibiotic courses.

RESULTS

A total of 137 participants completed 897 visits over 13 years. All but one received ≥ 1 antibiotic courses during study participation, most often cephalosporins (74%) or amoxicillin-clavulanate (73%). Thirty-one percent reported chronic azithromycin use. Per participant, there was an average of 2.3 (SD = 2.2) oral antibiotic courses annually. The rate of reported antibiotic courses at the 6 United States sites was 2.6 times higher compared to the Canadian site (p < 0.001). As patients got older, they were more likely to report use of amoxicillin-clavulanate (p < 0.001), chronic azithromycin (p < 0.001), fluroquinolones (p < 0.001), inhaled steroids with long-acting beta-agonists (p = 0.010), and hypertonic saline (p < 0.001). Compared to outer dynein arm defects, those with inner dynein arm/microtubular disorganization defects reported increased use of chronic azithromycin (p = 0.011) and inhaled steroids (p = 0.015).

DISCUSSION

Older participants and those with inner dynein arm/microtubular disorganization defects reported more therapies likely due to disease progression and more severe phenotypes, respectively. We report that a wide range of therapies are used in PCD without disease-specific studies defining benefits and risks.

Optical Methods for Determining the Phagocytic Activity Profile of CD206-Positive Macrophages Extracted from Bronchoalveolar Lavage by Specific Mannosylated Polymeric Ligands

Macrophage (Mph) polarization and functional activity play an important role in the development of inflammatory lung conditions. The previously widely used bimodal classification of Mph into M1 and M2 does not adequately reflect the full range of changes in polarization and functional diversity observed in Mph in response to various stimuli and disease states. Here, we have developed a model for the direct assessment of Mph from bronchial alveolar lavage fluid (BALF) functional alterations, in terms of phagocytosis activity, depending on external stimuli, such as exposure to a range of bacteria (E. coli, B. subtilis and L. fermentum). We have employed polymeric mannosylated ligands (the "trapping ligand") specifically targeting the CD206 receptor to selectively isolate activated Mph from the BALF of patients with pulmonary inflammatory conditions: primary ciliary dyskinesia (PCD), pneumonia and bronchial asthma. An "imaging ligand" allows for the subsequent visualization of the isolated cells using a sandwich technique. Five model strains of E. coli, MH-1, JM109, BL21, W3110 and ATCC25922, as well as B. subtilis and L. fermentum strains, each exhibiting distinct properties and expressing red fluorescent protein (RFP), were used as a phagocytosis substrate. Fluorometric, FTIR- and confocal laser scanning microscopy (CLSM) assessments of the phagocytic response of Mph to these bacterial cells were performed. Mph absorbed different strains of E. coli with different activities due to the difference in the surface villosity of bacterial cells (pili and fimbriae, as well as signal patterns). In the presence of other competitor cells (like those of Lactobacilli), the phagocytic activity of Mph is changed between two and five times and strongly dependent on the bacterial strain. The relative phagocytic activity indexes obtained for BALF-Mph in comparison with that obtained for model human CD206+ Mph in the M1 polarization state (derived from THP-1 monocyte cultures) were considered as a set of parameters to define the Mph polarization profile from the BALF of patients. Mannan as a marker determining the selectivity of the binding to the CD 206 mannose receptor of Mph significantly inhibited the phagocytosis of E. coli and B. subtilis in cases of pneumonia, suggesting an important role of CD206 overexpression in acute inflammation. Conversely, L. fermentum binding was enhanced in PCD, possibly reflecting altered macrophage responsiveness in chronic lung diseases. Our approach based on the profiling of Mph from patient BALF samples in terms of phagocytosis for a range of model bacterial strains is important for the subsequent detailed study of the factors determining dangerous conditions and resistance to existing therapeutic options.

Primary ciliary dyskinesia as a rare cause of male infertility: case report and literature overview

BACKGROUND

Primary ciliary dyskinesia (PCD) is a heterogenous disease caused by mutations of miscellaneous genes which physiologically play an important role in proper structure and/or function of various cellular cilia including sperm flagella. Besides male infertility, the typical phenotypes, based on decreased mucociliary clearance, are lifelong respiratory issues, i.e., chronic bronchitis leading to bronchiectasis, chronic rhinosinusitis, and chronic otitis media. Moreover, since motile cilia are important during embryological development in the sense of direction of gut rotation, 50% of affected individuals develop situs inversus - so-called Kartagener's syndrome.

CASE PRESENTATION

We present two cases of PCD as a rare cause of male infertility.

CONCLUSIONS

Primary ciliary dyskinesia should be suspected in infertile males having (sub)normal sperm concentration values with persistent zero motility together with patient's and/or family history of respiratory symptoms like bronchiectasis, chronic cough, rhinitis, recurrent sinusitis, and otitis media. Due to more than 50 identified mutations until now, the causal mechanism of male infertility is miscellaneous and not in all cases known in detail. Besides impaired sperm motility, other mechanisms significantly decreasing efficacy of assisted reproduction techniques play a pivotal role. Thus, proper diagnostic work-up including, among others, sperm DNA fragmentation, is mandatory to avoid ineffective treatment burden.

Whole genome sequencing enhances molecular diagnosis of primary ciliary dyskinesia

BACKGROUND

Primary ciliary dyskinesia (PCD) is a genetic disorder affecting motile cilia. Most cases are inherited recessively, due to variants in >50 genes that result in abnormal or absent motile cilia. This leads to chronic upper and lower airway disease, subfertility, and laterality defects. Given overlapping clinical features and genetic heterogeneity, diagnosis can be difficult and often occurs late. Of those tested an estimated 30% of genetically screened PCD patients still lack a molecular diagnosis. A molecular diagnosis allows for appropriate clinical management including prediction of phenotypic features correlated to genotype. Here, we aimed to identify how readily a genetic diagnosis could be made using whole genome sequencing (WGS) to facilitate identification of pathogenic variants in known genes as well as novel PCD candidate genes.

METHODS

WGS was used to screen for pathogenic variants in eight patients with PCD.

RESULTS

7/8 cases had homozygous or biallelic variants in DNAH5, DNAAF4 or DNAH11 classified as pathogenic or likely pathogenic. Three identified variants were deletions, ranging from 3 to 13 kb, for which WGS identified precise breakpoints, permitting confirmation by Sanger sequencing. WGS yielded identification of a de novo variant in a novel PCD gene TUBB4B.

CONCLUSION

Here, WGS uplifted genetic diagnosis of PCD by identifying structural variants and novel modes of inheritance in new candidate genes. WGS could be an important component of the PCD diagnostic toolkit, increasing molecular diagnostic yield from current (70%) levels, and enhancing our understanding of fundamental biology of motile cilia and variants in the noncoding genome.

Cotranslational molecular condensation of cochaperones and assembly factors facilitates axonemal dynein biogenesis

Axonemal dynein, the macromolecular machine that powers ciliary motility, assembles in the cytosol with the help of dynein axonemal assembly factors (DNAAFs). These DNAAFs localize in cytosolic foci thought to form via liquid-liquid phase separation. However, the functional significance of DNAAF foci formation and how the production and assembly of multiple components are so efficiently coordinated, at such enormous scale, remain unclear. Here, we unveil an axonemal dynein production and assembly hub enriched with translating heavy chains (HCs) and DNAAFs. We show that mRNAs encoding interacting HCs of outer dynein arms colocalize in cytosolic foci, along with nascent HCs. The formation of these mRNA foci and their colocalization relies on HC translation. We observe that a previously identified DNAAF assembly, containing the DNAAF Lrrc6 and cochaperones Ruvbl1 and Ruvbl2, colocalizes with these HC foci, and is also dependent on HC translation. We additionally show that Ruvbl1 is required for the recruitment of Lrrc6 into the HC foci and that both proteins function cotranslationally. We propose that these DNAAF foci are anchored by stable interactions between translating HCs, ribosomes, and encoding mRNAs, followed by cotranslational molecular condensation of cochaperones and assembly factors, providing a potential mechanism that coordinates HC translation, folding, and assembly at scale.

Associations between respiratory pathogens and lung function in primary ciliary dyskinesia: cross-sectional analysis from the PROVALF-PCD cohort

Introduction

Respiratory pathogens are frequently isolated from airway samples in primary ciliary dyskinesia (PCD) patients. Few studies have investigated associations between these pathogens and lung function, with current management based on evidence from cystic fibrosis. We investigated the association between commonly isolated respiratory pathogens and lung function in PCD patients.

Methods

Using a cross-sectional design, we prospectively collected clinical and concurrent microbiology data from 408 participants with probable or confirmed PCD, aged ≥5 years, from 12 countries. We used Global Lung Function Initiative 2012 references to calculate forced expiratory volume in 1 s (FEV1) z-scores. For 351 patients (86%) with complete data, we assessed the association of the four most frequently isolated pathogens with lung function by fitting multilevel linear models with country as random intercept, adjusted for age at diagnosis, age at lung function, use of antibiotic prophylaxis and body mass index z-scores.

Results

Individuals with Pseudomonas aeruginosa growth in culture had significantly lower FEV1 z-scores (β= -0.87, 95% CI -1.40- -0.34), adjusted for presence of Haemophilus influenzae, methicillin-sensitive Staphylococcus aureus and Streptococcus pneumoniae, and for covariates. When stratified by age, associations remained strong for adults but not for children. Results were similar when ciliary defects by transmission electron microscopy were included in the models and when restricting analysis to only confirmed PCD cases.

Conclusions

We found that P. aeruginosa was associated with worse lung function in individuals with PCD, particularly adults. These findings suggest that it is prudent to aim for P. aeruginosa eradication in the first instance, and to treat exacerbations promptly in colonised patients.

Development and Initial Characterization of Pigs with DNAI1 Mutations and Primary Ciliary Dyskinesia

Mutations in more than 50 different genes cause primary ciliary dyskinesia (PCD) by disrupting the activity of motile cilia that facilitate mucociliary transport (MCT). Knowledge of PCD has come from studies identifying disease-causing mutations, characterizing structural cilia abnormalities, finding genotype-phenotype relationships, and studying the cell biology of cilia. Despite these important findings, we still lack effective treatments and people with PCD have significant pulmonary impairment. As with many other diseases, a better understanding of pathogenic mechanisms may lead to effective treatments. To pursue disease mechanisms, we used CRISPR-Cas9 to develop a PCD pig with a disrupted DNAI1 gene. PCD pig airway cilia lacked the outer dynein arm and had impaired beating. MCT was impaired under both baseline conditions and after cholinergic stimulation in PCD pigs. Neonatal PCD pigs developed neonatal respiratory distress with evidence of atelectasis, air trapping, and airway mucus obstruction. Despite airway mucus accumulation, lung bacterial counts were similar between neonatal wild-type and PCD pigs. Sinonasal disease was present in all neonatal PCD pigs. Older PCD pigs developed worsening airway mucus obstruction, inflammation, and bacterial infection. This pig model closely mimics the disease phenotype seen in people with PCD and can be used to better understand the pathophysiology of PCD airway disease.

A novel splicing mutation DNAH5 c.13,338 + 5G > C is involved in the pathogenesis of primary ciliary dyskinesia in a family with primary familial brain calcification

BACKGROUND

Primary ciliary dyskinesia (PCD) is an autosomal recessive hereditary disease characterized by recurrent respiratory infections. In clinical manifestations, DNAH5 (NM_001361.3) is one of the recessive pathogenic genes. Primary familial brain calcification (PFBC) is a neurodegenerative disease characterized by bilateral calcification in the basal ganglia and other brain regions. PFBC can be inherited in an autosomal dominant or recessive manner. A family with PCD caused by a DNAH5 compound heterozygous variant and PFBC caused by a MYORG homozygous variant was analyzed.

METHODS

In this study, we recruited three generations of Han families with primary ciliary dyskinesia combined with primary familial brain calcification. Their clinical phenotype data were collected, next-generation sequencing was performed to screen suspected pathogenic mutations in the proband and segregation analysis of families was carried out by Sanger sequencing. The mutant and wild-type plasmids were constructed and transfected into HEK293T cells instantaneously, and splicing patterns were detected by Minigene splicing assay. The structure and function of mutations were analyzed by bioinformatics analysis.

RESULTS

The clinical phenotypes of the proband (II10) and his sister (II8) were bronchiectasis, recurrent pulmonary infection, multiple symmetric calcifications of bilateral globus pallidus and cerebellar dentate nucleus, paranasal sinusitis in the whole group, and electron microscopy of bronchial mucosa showed that the ciliary axoneme was defective. There was also total visceral inversion in II10 but not in II8. A novel splice variant C.13,338 + 5G > C and a frameshift variant C.4314delT (p. Asn1438lysfs *10) were found in the DNAH5 gene in proband (II10) and II8. c.347_348dupCTGGCCTTCCGC homozygous insertion variation was found in the MYORG of the proband. The two pathogenic genes were co-segregated in the family. Minigene showed that DNAH5 c.13,338 + 5G > C has two abnormal splicing modes: One is that part of the intron bases where the mutation site located is translated, resulting in early translation termination of DNAH5; The other is the mutation resulting in the deletion of exon76.

CONCLUSIONS

The newly identified DNAH5 splicing mutation c.13,338 + 5G > C is involved in the pathogenesis of PCD in the family, and forms a compound heterozygote with the pathogenic variant DNAH5 c.4314delT lead to the pathogenesis of PCD.

Primary Ciliary Dyskinesia Associated Disease-Causing Variants in CCDC39 and CCDC40 Cause Axonemal Absence of Inner Dynein Arm Heavy Chains DNAH1, DNAH6, and DNAH7

Disease-causing bi-allelic DNA variants in CCDC39 and CCDC40 are frequent causes of the hereditary disorder of primary ciliary dyskinesia (PCD). The encoded proteins form a molecular ruler complex, crucial for maintaining the 96 nm repeat units along the ciliary axonemes. Defects of those proteins cause a stiff, rapid, and flickery ciliary beating pattern, recurrent respiratory infections, axonemal disorganization, and abnormal assembly of GAS8, CCDC39, and DNALI1. We performed molecular characterization of the defects in the 96 nm axonemal ruler due to disease-causing variants in CCDC39 and CCDC40 and analyzed the effect on additional axonemal components. We identified a cohort of 51 individuals with disease-causing variants in CCDC39 and CCDC40 via next-generation sequencing techniques and demonstrated that the IDA heavy chains DNAH1, DNAH6, and DNAH7 are conspicuously absent within the respiratory ciliary axonemes by immunofluorescence analyses. Hence, we show for the first time that the centrin2 (CETN2) containing IDAs are also affected. These findings underscore the crucial role of CCDC39 and CCDC40 in the assembly and function of IDAs in human respiratory cilia. Thus, our data improve the diagnostics of axonemal ruler defects by further characterizing the associated molecular IDA defects.

Compartmentalized mitochondrial ferroptosis converges with optineurin-mediated mitophagy to impact airway epithelial cell phenotypes and asthma outcomes

A stable mitochondrial pool is crucial for healthy cell function and survival. Altered redox biology can adversely affect mitochondria through induction of a variety of cell death and survival pathways, yet the understanding of mitochondria and their dysfunction in primary human cells and in specific disease states, including asthma, is modest. Ferroptosis is traditionally considered an iron dependent, hydroperoxy-phospholipid executed process, which induces cytosolic and mitochondrial damage to drive programmed cell death. However, in this report we identify a lipoxygenase orchestrated, compartmentally-targeted ferroptosis-associated peroxidation process which occurs in a subpopulation of dysfunctional mitochondria, without promoting cell death. Rather, this mitochondrial peroxidation process tightly couples with PTEN-induced kinase (PINK)-1(PINK1)-Parkin-Optineurin mediated mitophagy in an effort to preserve the pool of functional mitochondria and prevent cell death. These combined peroxidation processes lead to altered epithelial cell phenotypes and loss of ciliated cells which associate with worsened asthma severity. Ferroptosis-targeted interventions of this process could preserve healthy mitochondria, reverse cell phenotypic changes and improve disease outcomes.

Estimates of primary ciliary dyskinesia prevalence: a scoping review

Background

Primary ciliary dyskinesia (PCD) is a rare multisystem genetic disease caused by dysfunctional motile cilia. Despite PCD being the second most common inherited airway disease after cystic fibrosis, PCD continues to be under-recognised globally owing to nonspecific clinical features and the lack of a gold standard diagnostic test. Commonly repeated prevalence estimates range from one in 10 000 to one in 20 000, based on regional epidemiological studies with known limitations. The purpose of this scoping review was to appraise the PCD literature, to determine the best available global PCD prevalence estimate and to inform the reader about the potential unmet health service needs in PCD. The primary objective of the present study was to systematically review the literature about PCD prevalence estimates.

Methods

A scoping review was conducted following the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for scoping reviews (PRISMA-ScR) methodology. Included studies estimated PCD prevalence and used cohort, clinical or genomic data. Case reports, conference abstracts, review articles, animal studies or non-English articles were excluded.

Results

A literature review identified 3484 unique abstracts; 34 underwent full-text review and eight met the inclusion/exclusion criteria. Seven articles were based on epidemiological studies of specific geographical regions and provided prevalence estimates that ranged from approximately one to 44.1 in 100 000. Only one study estimated global prevalence, using two large genomic databases, and calculated it to be ∼13.2 in 100 000 (based on pathogenic variants in 29 disease-causing genes).

Conclusions

A population-based genomic approach for estimating global prevalence has found that PCD is much more prevalent than previously cited in the literature. This highlights the potential unmet health service needs of people living with PCD.

Regional anesthesia in a patient with primary ciliary dyskinesia: A case report

BACKGROUND

Primary ciliary dyskinesia (PCD) is an inherited autosomal-recessive disorder of impaired mucociliary clearance characterized by chronic respiratory diseases, otolaryngological diseases, central nervous system abnormalities, reproductive system abnormalities, and cardiac function abnormalities. General anesthesia in these patients is associated with a higher incidence of respiratory complications than in patients without the disease.

CASE SUMMARY

A 16-year-old male patient was referred to the emergency room complaining of right ankle pain due to distal tibiofibular fracture. Three years prior, he had been diagnosed with PCD. At that time, he had experienced several episodes of pneumonia, sinusitis, and chronic middle ear infections, for which he underwent surgical interventions. At the current admission, he presented with cough and sputum but no other respiratory symptoms. A chest computed tomography scan revealed centrilobular ground-glass opacities in both lower lobes and a calcified nodule in the left lower lobe. For the surgical procedure and postoperative pain management, combined spinal-epidural anesthesia was employed. The patient's postoperative pain score was measured by the numerical rating scale (NRS). On the day of surgery, his NRS was 5 points. By the second postoperative day, the NRS score had decreased to 2-3 points. The epidural catheter was removed on the fourth day following the operation. The patient was subsequently discharged no respiratory complications.

CONCLUSION

We performed combined spinal-epidural anesthesia in a patient with PCD. The patient experienced no additional respiratory complications and was discharged with a low NRS score for pain.

Genetic Spectrum and Clinical Characteristics of Patients with Primary Ciliary Dyskinesia: a Belgian Single Center Study

PURPOSE

We aimed to examine the correlation between clinical characteristics and the pathogenic gene variants in patients with Primary Ciliary Dyskinesia (PCD).

METHODS

We conducted a retrospective single-center study in patients with PCD followed at the University Hospitals Leuven. We included patients with genetically confirmed PCD and described their genotype, data from ultrastructural ciliary evaluation and clinical characteristics. Genotype/phenotype correlations were studied in patients with the most frequently involved genes.

RESULTS

We enrolled 74 patients with a median age of 25.58 years. The most frequently involved genes were DNAH11 (n = 23) and DNAH5 (n = 19). The most frequent types of pathogenic variants were missense (n = 42) and frameshift variants (n = 36) and most patients had compound heterozygous variants (n = 44). Ciliary ultrastructure (p < 0.001), situs (p = 0.015) and age at diagnosis (median 9.50 vs 4.71 years, p = 0.037) differed between DNAH11 and DNAH5. When correcting for situs this difference in age at diagnosis was no longer significant (p = 0.973). Patients with situs inversus were diagnosed earlier (p = 0.031). Respiratory tract microbiology (p = 0.161), lung function (cross-sectional, p = 0.829 and longitudinal, p = 0.329) and chest CT abnormalities (p = 0.202) were not significantly different between DNAH11 and DNAH5 variants.

CONCLUSION

This study suggests a genotype-phenotype correlation for some of the evaluated clinical characteristics of the two most frequently involved genes in this study, namely DNAH11 and DNAH5.

Two Japanese Pediatric Patients With Primary Ciliary Dyskinesia Caused by Loss-of-Function Variants in the CCNO gene

Primary ciliary dyskinesia (PCD) is a rare congenital disorder caused by pathogenic variants of genes related to cilia. Here, we report two Japanese pediatric patients with PCD caused by pathogenic compound heterozygous variants in the cyclin O (CCNO) gene (Case 1, NM_021147.4:c.[262C>T];[781delC], p.[Gln88Ter];[Leu261fs]; Case 2, c.[262C>T];[c.248_252dupTGCCC], p.[Gln88Ter];[Gly85fs]). The clinical symptoms of the patients were varied. Neither of the patients had situs inversus. Transmission electron microscopy of the respiratory cilia from the nasal mucosa in Case 1 showed a remarkable reduction of cilia and the few residual cilia had central pair defects and microtubular disorganization.

The primary ciliary dyskinesia-related genetic risk score is associated with susceptibility to adult-onset asthma

BACKGROUND

Disturbance of mucociliary clearance is an important factor in the pathogenesis of asthma. We hypothesized that common variants in genes responsible for ciliary function may contribute to the development of asthma with certain phenotypes.

METHODS

Three independent adult Japanese populations (including a total of 1,158 patients with asthma and 2,203 non-asthmatic healthy participants) were studied. First, based on the ClinVar database (https://www.ncbi.nlm.nih.gov/clinvar/), we selected 12 common single-nucleotide polymorphisms (SNPs) with molecular consequences (missense, nonsense, and 3'-untranslated region mutation) in 5 primary ciliary dyskinesia (PCD)-related genes and calculated a PCD-genetic risk score (GRS) as a cumulative effect of these PCD-related genes. Second, we performed a two-step cluster analysis using 3 variables, including PCD-GRS, forced expiratory volume in 1 second (%predicted FEV1), and age of asthma onset.

RESULTS

Compared to adult asthma clusters with an average PCD-GRS, clusters with high and low PCD-GRS had similar overall characteristics: adult-onset, female predominance, preserved lung function, and fewer features of type 2 immunity as determined by IgE reactivity and blood eosinophil counts. The allele frequency of rs1530496, a SNP representing an expression quantitative trait locus (eQTL) of DNAH5 in the lung, showed the largest statistically significant difference between the PCD-GRS-High and PCD-GRS-Low asthma clusters (p = 1.4 x 10-15).

CONCLUSION

Genes associated with PCD, particularly the common SNPs associated with abnormal expression of DNAH5, may have a certain influence on the development of adult-onset asthma, perhaps through impaired mucociliary clearance.

Pulmonary functions, nasal symptoms, and quality of life in patients with primary ciliary dyskinesia (PCD)

BACKGROUND

Several factors may influence quality of life (QOL) for patients with primary ciliary dyskinesia (PCD). We aimed to evaluate the association between pulmonary functions, nasal symptoms and QOL in PCD patients.

METHODS

A prospective single center study. Patients performed spirometry, whole body plethysmography, forced oscillation technique (FOT), lung clearance index (LCI), 6-min walk test (6MWT), and filled two questionnaires: a specific PCD QOL questionnaire (PCD-QOL) and Sino-nasal outcome test (SNOT-22) questionnaire, assessing symptoms of chronic rhinosinusitis and health related QOL.

RESULTS

Twenty-seven patients (56% females), age 19.4 ± 10.5 years were included; their, FEV1 was 74.6 ± 22.7%, and RV/TLC was (157.3 ± 39.3% predicted). Health perception and lower respiratory symptoms domains of PCD-QOL had the lowest score (median [IQR]: 50 [33.3-64.6] and 57.1 [38.9-72.2], respectively). FOT parameters correlated with several PCD-QOL domains. R5 z-score (indicating total airway resistance) and AX z-score (indicating airway reactance) correlated negatively with physical domain (r = -0.598, p = .001, and r = -0.42, p = .03, respectively); R5 z-score also correlated negatively with hearing domain (r = -0.57, p = .002). R5-20 z-score (indicating small airway resistance) correlated negatively with role domain (r = -0.49, p = .03). SNOT-22 score correlated negatively with several PCD-QOL domains (lower respiratory symptoms r = -0.77, p < .001; physical r = -0.72, p < .001; upper respiratory symptoms r = -0.66, p < .001). No correlations were found between spirometry values, LCI, 6MWT, and PCD-QOL.

CONCLUSIONS

FOT suggested small airway dysfunction, and correlated negatively with several PCD-QOL domains. Nasal symptoms had strong negative correlations with PCD-QOL. Larger longitudinal studies will further elucidate factors affecting QOL in PCD.

A gel-coated air-liquid-interface culture system with tunable substrate stiffness matching healthy and diseased lung tissues

Since its invention in the late 1980s, the air-liquid-interface (ALI) culture system has been the standard in vitro model for studying human airway biology and pulmonary diseases. However, in a conventional ALI system, cells are cultured on a porous plastic membrane that is much stiffer than human airway tissues. Here, we develop a gel-ALI culture system by simply coating the plastic membrane with a thin layer of hydrogel with tunable stiffness matching that of healthy and fibrotic airway tissues. We determine the optimum gel thickness that does not impair the transport of nutrients and biomolecules essential to cell growth. We show that the gel-ALI system allows human bronchial epithelial cells (HBECs) to proliferate and differentiate into pseudostratified epithelium. Furthermore, we discover that HBECs migrate significantly faster on hydrogel substrates with stiffness matching that of fibrotic lung tissues, highlighting the importance of mechanical cues in human airway remodeling. The developed gel-ALI system provides a facile approach to studying the effects of mechanical cues in human airway biology and in modeling pulmonary diseases.NEW & NOTEWORTHY In a conventional ALI system, cells are cultured on a plastic membrane that is much stiffer than human airway tissues. We develop a gel-ALI system by coating the plastic membrane with a thin layer of hydrogel with tunable stiffness matching that of healthy and fibrotic airway tissues. We discover that human bronchial epithelial cells migrate significantly faster on hydrogel substrates with pathological stiffness, highlighting the importance of mechanical cues in human airway remodeling.

Absolute quantitation of human wild-type DNAI1 protein in lung tissue using a nanoLC-PRM-MS-based targeted proteomics approach coupled with immunoprecipitation

BACKGROUND

Dynein axonemal intermediate chain 1 protein (DNAI1) plays an essential role in cilia structure and function, while its mutations lead to primary ciliary dyskinesia (PCD). Accurate quantitation of DNAI1 in lung tissue is crucial for comprehensive understanding of its involvement in PCD, as well as for developing the potential PCD therapies. However, the current protein quantitation method is not sensitive enough to detect the endogenous level of DNAI1 in complex biological matrix such as lung tissue.

METHODS

In this study, a quantitative method combining immunoprecipitation with nanoLC-MS/MS was developed to measure the expression level of human wild-type (WT) DNAI1 protein in lung tissue. To our understanding, it is the first immunoprecipitation (IP)-MS based method for absolute quantitation of DNAI1 protein in lung tissue. The DNAI1 quantitation was achieved through constructing a standard curve with recombinant human WT DNAI1 protein spiked into lung tissue matrix.

RESULTS

This method was qualified with high sensitivity and accuracy. The lower limit of quantitation of human DNAI1 was 4 pg/mg tissue. This assay was successfully applied to determine the endogenous level of WT DNAI1 in human lung tissue.

CONCLUSIONS

The results clearly demonstrate that the developed assay can accurately quantitate low-abundance WT DNAI1 protein in human lung tissue with high sensitivity, indicating its high potential use in the drug development for DNAI1 mutation-caused PCD therapy.

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.

The First Case of a Homozygous CCNO NM 021147.4 Mutation Associated With Primary Ciliary Dyskinesia in Two Indian Siblings

Primary ciliary dyskinesia (PCD) is a heterogeneous autosomal recessive disease marked by organ lateralization in 50% of patients, chronic sinopulmonary disease, infertility in men, and neonatal respiratory distress. Respiratory control cells contain CCNO in their apical cytoplasm, which is necessary for the development of multiciliate cells, basal body amplification, and migration. Reduced generation of multiple motile cilia, a rare form of PCD, has been linked to CCNO gene abnormalities. Individuals with CCNO mutations have been reported to suffer from severe lower respiratory infections that cause progressive impairment of lung function. For the first time, we describe the CCNO NM 021147.4 (c.258 262dup.p, Gln88argfs*8 Homozygous) gene mutation in an Indian consanguineous family that resulted in severe PCD.

Cilia-related diseases

More and more attention is paid to diseases such as internal transfer and brain malformation which are caused by the abnormal morphogenesis of cilia. These cilia-related diseases are divided into two categories: ciliopathy resulting from defects of primary cilia and primary ciliary dyskinesia (PCD) caused by functional dysregulation of motile cilia. Cilia are widely distributed, and their related diseases can cover many human organs and tissues. Recent studies prove that primary cilia play a key role in maintaining homeostasis in the cardiovascular system. However, molecular mechanisms of cilia-related diseases remain elusive. Here, we reviewed recent research progresses on characteristics, molecular mechanisms and treatment methods of ciliopathy and PCD. Our review is beneficial to the further research on the pathogenesis and treatment strategies of cilia-related diseases.

Lack of CFAP54 causes primary ciliary dyskinesia in a mouse model and human patients

Primary ciliary dyskinesia (PCD) is a highly heterogeneous recessive inherited disorder. FAP54, the homolog of CFAP54 in Chlamydomonas reinhardtii, was previously demonstrated as the C1d projection of the central microtubule apparatus of flagella. A Cfap54 knockout mouse model was then reported to have PCD-relevant phenotypes. Through whole-exome sequencing, compound heterozygous variants c.2649_2657delinC (p. E883Dfs*47) and c.7312_7313insCGCAGGCTGAATTCTTGG (p. T2438delinsTQAEFLA) in a new suspected PCD-relevant gene, CFAP54, were identified in an individual with PCD. Two missense variants, c.4112A>C (p. E1371A) and c.6559C>T (p. P2187S), in CFAP54 were detected in another unrelated patient. In this study, a minigene assay was conducted on the frameshift mutation showing a reduction in mRNA expression. In addition, a CFAP54 in-frame variant knock-in mouse model was established, which recapitulated the typical symptoms of PCD, including hydrocephalus, infertility, and mucus accumulation in nasal sinuses. Correspondingly, two missense variants were deleterious, with a dramatic reduction in mRNA abundance from bronchial tissue and sperm. The identification of PCD-causing variants of CFAP54 in two unrelated patients with PCD for the first time provides strong supportive evidence that CFAP54 is a new PCD-causing gene. This study further helps expand the disease-associated gene spectrum and improve genetic testing for PCD diagnosis in the future.

Cardiac Laterality: Surgical Results of Right Atrial Isomerism

Right atrial isomerism (RAI) is a complex entity with varying diagnostic and treatment outcomes due to its rarity. Treatment options range from palliative to corrective surgeries, resulting in heterogeneous outcomes. The aim of this study was to analyze the results obtained after cardiac surgery in patients with RAI. A retrospective study was conducted, including patients diagnosed with RAI who underwent cardiac surgery. Their follow-up was from 1 January 2010 to 31 March 2020. Demographic characteristics and perioperative conditions were described. Thirty-eight patients were included, the median age was 4 years (IQR 2-9.2) and 57.9% were men. The main diagnoses were atrioventricular canal (63.2%) and pulmonary stenosis (55.3%). The most common surgical procedures were modified Blalock-Taussig shunt (65.8%) and total cavopulmonary connection with an extracardiac conduit fenestrated without cardiopulmonary bypass (15.9%). We did not find any factors associated with negative outcomes in these patients. The overall survival was 86.8%, with a better outcome in those who did not require reintubation (log rank, p < 0.01). The survival of RAI was similar to other centers. Individuals with RAI should be evaluated rigorously to determine an adequate repair strategy, considering high morbidity and mortality.

Results and perinatal outcomes from 189 ICSI cycles of couples with asthenozoospermic men and flagellar defects assessed by transmission electron microscopy

RESEARCH QUESTION

Do patients presenting with flagella ultrastructural defects as assessed by electron microscopy, and defined within three phenotypes (dysplasia of the fibrous sheath [DFS], primary flagellar dyskinesia [PFD] and non-specific flagellar abnormalities [NSFA]), have decreased chances of success in intracytoplasmic sperm injection (ICSI) or adverse obstetric and neonatal outcomes?

DESIGN

Retrospective analysis of 189 ICSI cycles from 80 men with spermatozoa flagellum ultrastructural defects (DFS [n = 16]; PFD [n = 14]; NSFA [n = 50] compared with a control group (n = 97). Cycles were cumulatively analysed. All fresh and frozen embryo transfers resulting from each ICSI attempt were included. The effect of transmission electron microscopy (TEM) phenotype on the main ICSI outcomes was assessed by a multivariate logistic regression combined with a generalized linear mixed model to account for the non-independence of the observations.

RESULTS

No predictive value of TEM phenotype was found on the main outcomes of ICSI, namely fertilization rates, pregnancy and delivery rates, and cumulative pregnancy and delivery rates. Cumulative pregnancy rates ranged from 29.0-43.3% in the different TEM phenotype subgroups compared with 36.8% in the control group. Cumulative live birth rates ranged from 24.6-36.7% compared with 31.4% in the control group. No increase was found in miscarriages, preterm births, low birth weights or birth abnormalities.

CONCLUSIONS

Data on the cumulative chances of success in ICSI of patients with ultrastructural flagellar defects, a rare cause of male infertility often associated with an underlying genetic cause, are reassuring, as are obstetrical and neonatal outcomes in this population.

Muco-Obstructive Lung Disease: A Systematic Review

Muco-obstructive lung disease is a new classification under the diseases of respiratory tract. A lot of discussion is still going on regarding this new group of diseases. It is characterised by obstruction of the respiratory tract with a thick mucin layer. Usually in normal individuals, the mucus is swept out of the respiratory system while coughing in the form of sputum or phlegm, but if the consistency of the mucus is thick, or the amount is heavy or there is a certain defect in the ciliary function of the respiratory tract, the mucus is not cleared and it gets accumulated in the lungs alveoli, therefore blocking it. The mucus trapped in the distal airways cannot be cleared by coughing therefore forming a layer in the alveoli and bronchioles. Long-standing condition causes inflammation and infection. This new group of diseases specifically includes chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), primary ciliary dyskinesia (PCD) and non-cystic fibrosis bronchiectasis (NCFB). Asthma, although an obstructive disease of the lung, is not particularly included under muco-obstructive lung disease. The major symptoms with which these diseases present are sputum production, chronic cough and acute exacerbations of the condition. The mucus adheres to the lung parenchyma causing airway obstruction and hyperinflation. In this article, we will see how muco-obstructive lung diseases affect the normal physiology of the respiratory system and how is it different from other obstructive and restrictive lung diseases. We will individually look into all the four conditions that come under the category of muco-obstructive lung diseases.

Primary ciliary dyskinesia diagnosis and management and its implications in America: a mini review

Introduction

Primary ciliary dyskinesia (PCD) is a rare genetic disorder that can result in significant morbidity and mortality if left untreated. Clinical manifestations of PCD include recurrent respiratory infections, laterality defects, and infertility, all of which arise from impaired or absent ciliary motility. Diagnostic approaches for PCD may include high-speed video microscopy, measurement of nasal nitric oxide levels, and genetic testing; however, no single definitive diagnostic test exists. The present study aims to highlight the lack of standardized diagnostic and treatment guidelines for PCD in Latin America (Central and South America, and the Caribbean). To this effect, we compared North American and European recommendations for the diagnosis and management of PCD and found that certain diagnostic tools and treatment options mentioned in these guidelines are not readily accessible in many Latin American countries.

Methods & Results

This review gathers disease information in North America, Europe, and Latin America organizing guideline results into tables for clarity and potential interventions. Management information for Latin America is inferred from case reports, as most findings are from North American recommendations and studies on PubMed, Google Scholar, and Scopus. Treatment and management information is based on North American and European standards.Among 5,774 publications reviewed, only 15 articles met the inclusion criteria (focused on PCD management, peer-reviewed, and located in America). No clinical guideline for PCD in Latin America was found, but recommendations on respiratory management from Colombia and Chile were discovered. The lack of guidelines in Latin America may originate from limited resources and research on the disease in those countries.

Discussion

PCD lacks documentation, research, and recommendations regarding its prevalence in Latin America, likely due to unfavorable economic conditions. This disadvantage results in limited access to diagnostic tests available in North America and Europe. The PICADAR score, discussed in this review, can be used in low-income nations as a screening tool for the disorder.

Biallelic mutations in CFAP54 cause male infertility with severe MMAF and NOA

BACKGROUND

Spermatogenic impairments can lead to male infertility by different pathological conditions, such as multiple morphological abnormalities of the sperm flagella (MMAF) and non-obstructive azoospermia (NOA). Genetic factors are involved in impaired spermatogenesis.

METHODS AND RESULTS

Here, we performed genetic analyses through whole-exome sequencing in a cohort of 334 Han Chinese probands with severe MMAF or NOA. Biallelic variants of CFAP54 were identified in three unrelated men, including one homozygous frameshift variant (c.3317del, p.Phe1106Serfs*19) and two compound heterozygous variants (c.878G>A, p.Arg293His; c.955C>T, p.Arg319Cys and c.4885C>T, p.Arg1629Cys; c.937G>A, p.Gly313Arg). All of the identified variants were absent or extremely rare in the public human genome databases and predicted to be damaging by bioinformatic tools. The men harbouring CFAP54 mutations exhibited abnormal sperm morphology, reduced sperm concentration and motility in ejaculated semen. Significant axoneme disorganisation and other ultrastructure abnormities were also detected inside the sperm cells from men harbouring CFAP54 mutations. Furthermore, immunofluorescence assays showed remarkably reduced staining of four flagellar assembly-associated proteins (IFT20, IFT52, IFT122 and SPEF2) in the spermatozoa of CFAP54-deficient men. Notably, favourable clinical pregnancy outcomes were achieved with sperm from men carrying CFAP54 mutations after intracytoplasmic sperm injection treatment.

CONCLUSION

Our genetic analyses and experimental observations revealed that biallelic deleterious mutations of CFAP54 can induce severe MMAF and NOA in humans.

In Vitro Effect of Combined Hypertonic Saline and Salbutamol on Ciliary Beating Frequency and Mucociliary Transport in Human Nasal Epithelial Cells of Healthy Volunteers and Patients with Cystic Fibrosis

Background: Inhalation of hypertonic saline (HS) is standard of care in patients with cystic fibrosis (CF). However, it is unclear if adding salbutamol has-besides bronchodilation-further benefits, for example, on the mucociliary clearance. We assessed this in vitro by measuring the ciliary beating frequency (CBF) and the mucociliary transport rate (MCT) in nasal epithelial cells (NECs) of healthy volunteers and patients with CF. Aims: To investigate the effect of HS, salbutamol, and its combination on (muco)ciliary activity of NECs in vitro, and to assess potential differences between healthy controls and patients with CF. Methods: NECs obtained from 10 healthy volunteers and 5 patients with CF were differentiated at the air-liquid interface and aerosolized with 0.9% isotonic saline ([IS] control), 6% HS, 0.06% salbutamol, or combined HS and salbutamol. CBF and MCT were monitored over 48-72 hours. Results: In NECs of healthy controls, the absolute CBF increase was comparable for all substances, but CBF dynamics were different: HS increased CBF slowly and its effect lasted for an extended period, salbutamol and IS increased CBF rapidly and the effect subsided similarly fast, and HS and salbutamol resulted in a rapid and long-lasting CBF increase. Results for CF cells were comparable, but less pronounced. Similar to CBF, MCT increased after the application of all the tested substances. Conclusion: CBF and MCT of NECs of healthy participants and CBF of patients with CF increased upon treatment with aerosolized IS, HS, salbutamol, or HS and salbutamol, showing a relevant effect for all tested substances. The difference in the CBF dynamics can be explained by the fact that the properties of the mucus are changed differently by different saline concentrations.

Mucolytic treatment of chronic rhinosinusitis in a murine model of primary ciliary dyskinesia

Background: Genetic defects in motile cilia cause primary ciliary dyskinesia (PCD), a rare disease with no specific therapeutics. Individuals with PCD often have impaired fertility and laterality defects and universally suffer from upper and lower airway diseases. Chronic rhinosinusitis is a universal feature of PCD, and mucus accumulation and subsequent infections of the sinonasal cavity cause significant morbidity in individuals with PCD. Despite this, there are no approved treatments that specifically target mucus. Objective: The goals of this study were to determine whether computed tomography (CT) imaging could be used to quantify mucus accumulation and whether the use of a mucolytic agent to reduce disulfide cross-links present in mucins would improve the effectiveness of nasal lavage at removing mucus in a murine model of PCD. Methods: Adult mice with a deletion of the axonemal dynein Dnaic1 were imaged using CT scanning to characterize mucus accumulation. The animals were then treated by nasal lavage with saline, with/without the disulfide-reducing agent tris(2-carboxyethyl)phosphine. Post-treatment CT scans were used to quantify improvement in the sinonasal cavity. Results: Mucus accumulation in the nasal cavity was readily quantified by CT. Compared to sham-treated control animals, nasal lavage with/without a mucolytic agent resulted in a significant reduction of accumulated mucus (p < 0.01). Treatment with the mucolytic agent showed a greater reduction of accumulated mucus than treatment with saline alone. Conclusion: The results suggest that inclusion of a mucolytic agent may increase the effectiveness of nasal lavage at reducing mucus burden in PCD.

Risk factors for the deterioration of pulmonary function in primary ciliary dyskinesia

BACKGROUND

PCD is a genetic disease leading to a decline in pulmonary function. There is only little knowledge of factors determining the long-term pulmonary outcome. Especially adherence has not been addressed yet although being an independent risk factor for an increased loss of lung capacity in other chronic respiratory diseases.

OBJECTIVE

Assessing the impact of bacterial airway colonization and adherence on long-term lung function in patients with PCD.

METHODS

Data on colonization and lung function parameters like forced expiratory volume in the first second (FEV1, Z-score) and lung clearance index (LCI2,5% ) were collected for 7.01 ± 2.2 years (893 quarters) in 44 PCD patients. Adherence was classified as good, moderate or poor. The impact of both adherence and colonization was assessed for the long-term course of FEV1, the association of colonization with lung function also quarterly.

STATISTICS

Kruskall-Wallis test, T test, ANOVA, linear regression, linear mixed model.

RESULTS

Chronic colonization did not show any impact on the for long-term course of FEV1 , but adherence was a significant factor: patients with good adherence showed better FEV1 at the end of the observation period than children with poor adherence (-0.15 ± 0.88 vs. -2.63 ± 1.79, p < 0.01).

CONCLUSION

Adherence has not yet been investigated for PCD. However, we found it to be a major significant factor affecting long-term FEV1 in PCD. Thus, it should be taken into consideration in the treatment protocols for PCD.

Case Report: A Novel Homozygous Mutation of Cyclin O Gene Mutation in Primary Ciliary Dyskinesia with Short Stature

Background

Primary ciliary dyskinesia (PCD) is a group of autosomal recessive genetic diseases caused by abnormal ciliary ultrastructure and/or function, resulting in reduced ciliary clearance function or other dysfunctions. PCD is one of the causes of recurrent respiratory tract infections in children. At present, there is no gold standard for diagnosis. In patients clinically suspected with PCD, a variety of examination methods are available to assist in diagnosis, such as high-speed video microscopic imaging to analyze ciliary movement patterns, transmission electron microscopy to observe ciliary ultrastructure, genetic testing, and detection of nitric oxide content in nasal expiratory air.

Case Description

We present a case summary of the clinical data and treatment process of a child with PCD and short stature induced by Novel exon 1 of CCNO mutation (NM-021147.5) at c.323del, and the proband father and mother were heterozygous mutators, who was diagnosed and treated in the Pediatric Healthcare Department of our hospital. We treated the child with recombinant human growth hormone to increase the height, and the patient was also advised to improve nutrition, prevent and control infections, and encouraged sputum expectoration. We also recommended regular follow-up visits to the outpatient department, and to seek other symptomatic and supportive treatments as necessary.

Conclusion

The height and nutritional status of the child improved after treatment. We also reviewed relevant literature to help clinicians improve their understanding of this disease.

DNAH11 and a Novel Genetic Variant Associated with Situs Inversus: A Case Report and Review of the Literature

BACKGROUND

Primary ciliary dyskinesia (PCD), also known as the immotile-cilia syndrome, is a clinically and genetically heterogeneous syndrome. Improper function of the cilia causes impaired mucociliary clearance. Neonatal respiratory distress, rhinosinusitis, recurrent chest infections, wet cough, and otitis media are respiratory presentations of this disease. It could also manifest as infertility in males as well as laterality defects in both sexes, such as situs abnormalities (Kartagener syndrome). During the past decade, numerous pathogenic variants in 40 genes have been identified as the causatives of primary ciliary dyskinesia. DNAH11 (dynein axonemal heavy chain 11) is a gene that is responsible for the production of cilia's protein and encodes the outer dynein arm. Dynein heavy chains are motor proteins of the outer dynein arms and play an essential role in ciliary motility. Case Presentation. A 3-year-old boy, the offspring of consanguineous parents, was referred to the pediatric clinical immunology outpatient department with a history of recurrent respiratory tract infections and periodic fever. Furthermore, on medical examination, situs inversus was recognized. His lab results revealed elevated levels of erythrocyte sedimentation rate (ESR) and C reactive protein (CRP). Serum IgG, IgM, and IgA levels were normal, while IgE levels were elevated. Whole exome sequencing (WES) was performed for the patient. WES demonstrated a novel homozygous nonsense variant in DNAH11 (c.5247G > A; p. Trp1749Ter).

CONCLUSION

We reported a novel homozygous nonsense variant in DNAH11 in a 3-year-old boy with primary ciliary dyskinesia. Biallelic pathogenic variants in one of the many coding genes involved in the process of ciliogenesis lead to PCD.

Revisiting Host-Pathogen Interactions in Cystic Fibrosis Lungs in the Era of CFTR Modulators

Cystic fibrosis transmembrane conductance regulator (CFTR) modulators, a new series of therapeutics that correct and potentiate some classes of mutations of the CFTR, have provided a great therapeutic advantage to people with cystic fibrosis (pwCF). The main hindrances of the present CFTR modulators are related to their limitations in reducing chronic lung bacterial infection and inflammation, the main causes of pulmonary tissue damage and progressive respiratory insufficiency, particularly in adults with CF. Here, the most debated issues of the pulmonary bacterial infection and inflammatory processes in pwCF are revisited. Special attention is given to the mechanisms favoring the bacterial infection of pwCF, the progressive adaptation of Pseudomonas aeruginosa and its interplay with Staphylococcus aureus, the cross-talk among bacteria, the bronchial epithelial cells and the phagocytes of the host immune defenses. The most recent findings of the effect of CFTR modulators on bacterial infection and the inflammatory process are also presented to provide critical hints towards the identification of relevant therapeutic targets to overcome the respiratory pathology of pwCF.

Pathophysiology of pulmonary nontuberculous mycobacterial (NTM) disease

In recent years, the incidence and prevalence of pulmonary nontuberculous mycobacterial (NTM) disease have increased worldwide. Although the reasons for this increase are unclear, dealing with this disease is essential. Pulmonary NTM disease is a chronic pulmonary infection caused by NTM bacteria, which are ubiquitous in various environments. In Japan, Mycobacterium avium-intracellulare complex (MAC) accounts for approximately 90% of the causative organisms of pulmonary NTM disease, which is also called pulmonary MAC disease or pulmonary MAI disease. It is important to elucidate the pathophysiology of this disease, which occurs frequently in postmenopausal women despite the absence of obvious immunodeficiency. The pathophysiology of this disease has not been fully elucidated; however, it can largely be divided into bacterial (environmental) and host-side problems. The host factors can be further divided into immune and airway problems. The authors suggest that the triangular relationship between bacteria, immunity, and the airway is important in the pathophysiology of this disease. The latest findings on the pathophysiology of pulmonary NTM disease are reviewed.

Use of dornase alfa in pediatric patients without cystic fibrosis

OBJECTIVES

Literature regarding clinical benefits of dornase alfa (DNase) in pediatric patients without cystic fibrosis is lacking. In December 2020, the study institution implemented restrictions to limit DNase use in this patient population. The primary objective was adherence to DNase ordering restrictions. Secondary objectives included length of stay, respiratory function, and use of inhaled mucolytic agents.

METHODS

This single-center retrospective chart review included patients less than 18 years of age who received DNase one year prior to through one year after order restriction implementation. Data collected included patient demographics and respiratory clinical parameters. Dosing regimens for DNase, n-acetylcysteine, and hypertonic saline were collected, as well as changes in length of stay (LOS) and adherence to ordering restrictions.

RESULTS

Of 101 total DNase orders, 45 were placed after implementation of ordering restrictions and 16 (36%) met all ordering criteria. Hospital and intensive care unit (ICU) LOS after implementation of restrictions were not significantly different (p = 0.767 and p = 0.219, respectively). There was no significant change in patients' mean oxygenation index (p = 0.252) or FiO2% (p = 0.113) 24 hours after DA administration.

CONCLUSION

Respiratory function did not significantly change after DNase administration. Implementing restrictions on DNase did not impact intensive care unit or hospital LOS. Adherence to DNase ordering restrictions could be improved.

Anesthetic Management of Patients With Kartagener Syndrome: A Systematic Review of 99 Cases

KARTAGENER SYNDROME (KS) is characterized by the triad of chronic sinusitis, bronchiectasis, and situs inversus. The mirrored anatomy and respiratory infections in patients with KS patients pose great challenges for anesthetic management. The aim of this review is to summarize published cases with the hope of helping anesthesiologists perform anesthesia in patients with KS more safely. A comprehensive literature search for all cases of anesthetic management of KS patients was performed in Pubmed, EMBASE, CNKI, and Wanfang Database. The extracted data included age, sex, type of surgery, preoperative treatment, type of anesthesia, anesthetic agents, airway management, central venous catheterization, transesophageal echocardiogram, reversal of neuromuscular blockade, adverse events during the surgery, and postoperative complications. The study authors included 82 single-case reports, 3 case series, and 1 case cohort, with a total number of 99 patients. The most common surgical procedures were thoracic surgery (51.5%), which was followed by ear, nose, and throat surgery (16.5%), and general surgery (14.5%). The preoperative treatment of the patients was reported in only 20 patients, and included antibiotics, bronchodilators, steroids, chest physiotherapy, and postural drainage. General anesthesia was performed for 85.4% of the surgeries, and regional anesthesia was performed in 14.6% of the cases. For nonthoracic surgery, an endotracheal tube was the most commonly used airway device. For thoracic surgery, a double-lumen tube was the most commonly used airway device. The intraoperative process was uneventful in most patients, and most patients recovered smoothly in the postoperative course.

The EZ-Blocker® for one-lung ventilation in a patient with Kartagener syndrome and tracheal bronchus -a case report

BACKGROUND

The tracheal bronchus in Kartagener syndrome is a rare case that may cause difficulty in one-lung ventilation (OLV). Here we reported a case of successful OLV using bronchial blocker in a patient with tracheal bronchus and Kartagener syndrome (KS).

CASE

A 66-year-old female patient with Kartagener syndrome was admitted for left-side diaphragmatic plication. The patient's preoperative computed tomography image showed a tracheal bronchus of the apical segment in the right upper lobe. The patient received epidural analgesia and general anesthesia through total intravenous anesthesia. An EZ-Blocker® (Teleflex Life Sciences Ltd., Ireland) was used to perform OLV.

CONCLUSIONS

OLV through an EZ-Blocker® can be successfully performed in tracheal bronchus patients with Kartagener syndrome without side effects.

Towards an atomic model of a beating ciliary axoneme

The axoneme of motile cilia and eukaryotic flagella is an ordered assembly of hundreds of proteins that powers the locomotion of single cells and generates flow of liquid and particles across certain mammalian tissues. The symmetric and organized structure of the axoneme has invited structural biologists to unravel its intricate architecture at different scales. In the last few years, single-particle cryo-electron microscopy provided high-resolution structures of axonemal complexes that comprise dozens of proteins and are key to cilia function. This review summarizes unique structural features of the axoneme and the framework they provide to understand cilia assembly, the mechanism of ciliary beating, and clinical conditions associated with impaired cilia motility.

Cilia Ultrastructure Associated with Primary Ciliary Dyskinesia in Omani Patients

Objectives

Primary ciliary dyskinesia (PCD) is a disorder affecting the structure and function of the motile cilia of the respiratory system. Transmission electron microscopy is one method that can be used to examine ciliary ultrastructure in airway biopsies. Although the role of ultrastructural findings in PCD has been described in the literature, this role has not been well-studied in the Middle East or, specifically, Oman. This study aimed to describe ultrastructural features in Omani patients with high suspicion of PCD.

Methods

This retrospective cross-sectional study included 129 adequate airway biopsies obtained from Omani patients attending pulmonary clinics at Sultan Qaboos University Hospital and the Royal Hospital, Muscat, Oman, from 2010 to 2020 who were suspected of having PCD.

Results

Ciliary ultrastructural abnormalities in the current study population were outer dynein arm (ODA) associated with inner dynein arm (IDA) defects (8%), microtubular disorganisation associated with IDA defect (5%) and isolated ODA defect (2%). Most of the biopsies showed normal ultrastructure (82%).

Conclusion

In Omani patients suspected to have PCD, normal ultrastructure was the most common feature.

Homozygous variants in AKAP3 induce asthenoteratozoospermia and male infertility

BACKGROUND

As a common type of asthenoteratozoospermia, multiple morphological abnormalities of the sperm flagella (MMAF) can cause male infertility. Previous studies have revealed genetic factors as a major cause of MMAF. The known MMAF-associated genes are involved in the mitochondrial sheath, outer dense fibre or axoneme of the sperm flagella. These findings indicate the genetic heterogeneity of MMAF.

METHODS AND RESULTS

Here, we conducted genetic analyses using whole-exome sequencing in a cohort of 150 Han Chinese men with asthenoteratozoospermia. Homozygous deleterious variants of AKAP3 (A-kinase anchoring protein 3) were identified in two MMAF-affected men from unrelated families. One AKAP3 variant was a frameshift (c.2286_2287del, p.His762Glnfs*22) and the other variant was a missense mutation (c.44G>A, p.Cys15Tyr), which was predicted to be damaging by multiple bioinformatics tools. Further western blotting and immunofluorescence assays revealed the absence of AKAP3 in the spermatozoa from the man harbouring the homozygous frameshift variant, whereas the expression of AKAP3 was markedly reduced in the spermatozoa of the man with the AKAP3 missense variant p.Cys15Tyr. Notably, the clinical outcomes after intracytoplasmic sperm injection (ICSI) were divergent between these two cases, suggesting a possibility of AKAP3 dosage-dependent prognosis of ICSI treatment.

CONCLUSIONS

Our study revealed AKAP3 as a novel gene involved in human asthenoteratozoospermia.

Homozygous mutation in DNAAF4 causes primary ciliary dyskinesia in a Chinese family

Primary ciliary dyskinesia (PCD) is a rare autosomal recessive disorder that affects the structure and function of motile cilia, leading to classic clinical phenotypes, such as situs inversus, chronic sinusitis, bronchiectasis, repeated pneumonia and infertility. In this study, we diagnosed a female patient with PCD who was born in a consanguineous family through classic clinical manifestations, transmission electron microscopy and immunofluorescence staining. A novel DNAAF4 variant NM_130810: c.1118G>A (p. G373E) was filtered through Whole-exome sequencing. Subsequently, we explored the effect of the mutation on DNAAF4 protein from three aspects: protein expression, stability and interaction with downstream DNAAF2 protein through a series of experiments, such as transfection of plasmids and Co-immunoprecipitation. Finally, we confirmed that the mutation of DNAAF4 lead to PCD by reducing the stability of DNAAF4 protein, but the expression and function of DNAAF4 protein were not affected.

LOF variants identifying candidate genes of laterality defects patients with congenital heart disease

Defects in laterality pattern can result in abnormal positioning of the internal organs during the early stages of embryogenesis, as manifested in heterotaxy syndrome and situs inversus, while laterality defects account for 3~7% of all congenital heart defects (CHDs). However, the pathogenic mechanism underlying most laterality defects remains unknown. In this study, we recruited 70 laterality defect patients with CHDs to identify candidate disease genes by exome sequencing. We then evaluated rare, loss-of-function (LOF) variants, identifying candidates by referring to previous literature. We chose TRIP11, DNHD1, CFAP74, and EGR4 as candidates from 776 LOF variants that met the initial screening criteria. After the variants-to-gene mapping, we performed function research on these candidate genes. The expression patterns and functions of these four candidate genes were studied by whole-mount in situ hybridization, gene knockdown, and gene rescue methods in zebrafish models. Among the four genes, trip11, dnhd1, and cfap74 morphant zebrafish displayed abnormalities in both cardiac looping and expression patterns of early signaling molecules, suggesting that these genes play important roles in the establishment of laterality patterns. Furthermore, we performed immunostaining and high-speed cilia video microscopy to investigate Kupffer's vesicle organogenesis and ciliogenesis of morphant zebrafish. Impairments of Kupffer's vesicle organogenesis or ciliogenesis were found in trip11, dnhd1, and cfap74 morphant zebrafish, which revealed the possible pathogenic mechanism of their LOF variants in laterality defects. These results highlight the importance of rare, LOF variants in identifying disease-related genes and identifying new roles for TRIP11, DNHD1, and CFAP74 in left-right patterning. Additionally, these findings are consistent with the complex genetics of laterality defects.

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.

Clinical and genetic spectrum of primary ciliary dyskinesia in Chinese patients: a systematic review

Background

Primary ciliary dyskinesia (PCD) represents a highly heterogenous disorder with extensive clinical and genetic patterns among populations of different geographic location and ethnic origin. However, data about Chinese patients are limited. We aimed to summarize the clinical and genetic spectrum of Chinese PCD patients based on all available literatures.

Methods

We searched Embase, Pubmed, Web of Science and Chinese databases including CNKI, SinoMed and Wanfang from 1981 to 2021, to identify articles reporting patients with PCD in China, which had included information about transmission electron microscopy and/or genetic testing.

Results

A total of 244 Chinese PCD patients in 52 articles were included. Of these patients, the mean age was 13.1 years, and 55 patients (22.5%) were diagnosed with PCD after 18 years old. Compared with patients diagnosed with PCD in childhood or infancy, patients diagnosed with PCD in adulthood had a higher prevalence of chronic wet cough, sinusitis, Pseudomonas aeruginosa (PA) isolation and radiological bronchiectasis as well as worse lung function. 25 PCD-related genes were identified in 142 patients, and DNAH5, DNAH11, CCDC39 and CCDC40 were the most frequently detected mutations. More than half of genetic variants were loss-of-function mutations, and the majority of these variants were seen only once. Correlations between PCD phenotype, genotype and ciliary ultrastructure were also evidenced.

Conclusions

Diagnostic delay and under-recognition of PCD remain a big issue in China, which contributes to progressive lung disease and PA infection indicating worse outcome. Specialist equipment and expertise are urgently required to facilitate the early diagnosis and treatment of PCD.

Trial registry

PROSPERO; No.: CRD42021257804; URL:www.crd.york.ac.uk/prospero/

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02427-1.