Primary ciliary dyskinesia

A homozygous human WNT11 variant is associated with laterality, heart and renal defects

Wnt signaling plays important roles during vertebrate development, including left-right axis specification as well as heart and kidney organogenesis. We identified a homozygous human WNT11 variant in an infant with situs inversus totalis, complex heart defects and renal hypodysplasia, and used Xenopus embryos to functionally characterize this variant. WNT11c.814delG encodes a protein with reduced stability that lost signaling activity in vivo. This is remarkable, because the variant encodes a truncated ligand with nearly identical length and predicted structure to dominant-negative Wnts. Furthermore, we demonstrate that alteration of the truncated C-terminal end can restore stability and signaling activity similarly to Xenopus dominant-negative Wnt11b. Our study also suggests similar functions for WNT11 in human development as those described in model organisms. Therefore, biallelic WNT11 dysfunction should be considered a novel genetic cause of syndromal human phenotypes presenting with congenital heart defects and renal hypoplasia, with or without laterality defects. The work presented here enhances our understanding of human development and structure-function relationships in Wnt ligands.

Artificial oocyte activation technology as adjuvant therapy for primary ciliary dyskinesia: a report of eight cases and literature review

OBJECTIVE

To explore the clinical application effect and feasibility of intracytoplasmic sperm injection (ICSI) combined with artificial oocyte activation (AOA) technology in the treatment of male infertility caused by primary ciliary dyskinesia (PCD).

CASES REPORT

Between April 2022 and April 2024, our hospital's reproductive center treated a total of eight patients diagnosed with PCD and concurrent male infertility. Among them, six patients were treated with ICSI in conjunction with AOA as an adjuvant therapy, with their oocytes being subjected to ionomycin treatment for a duration of 15 min post-ICSI. One patient underwent ICSI alone, while another patient chose to use donor sperm. Ultimately, we assessed the fertilization rates and transferable embryo rates of all patients. The statistical results showed that the six patients who received ICSI combined with AOA achieved an average fertilization rate of 77.9% and a transferable embryo rate of 66.7%. Four of these patients achieved clinical pregnancy and live birth after embryo transfer. In contrast, the patient who received only ICSI had a fertilization rate of 51.7% and a transferable embryo rate of 20%.

CONCLUSIONS

AOA can be used as an adjuvant treatment in ICSI cycles for patients with PCD accompanied by male infertility. It not only increases the fertilization rate but also potentially improves embryo quality, thereby enhancing the transferable embryo rate.

Kartagener syndrome with minimal change disease: a case report

BACKGROUND

Kartagener syndrome is characterized by chronic sinusitis, bronchiectasis, and total visceral transposition. While there are few reports of Kartagener syndrome combined with kidney disease, there are none that specifically report Kartagener syndrome in conjunction with minimal change disease. This is the first report of a rare case of Kartagener syndrome with minimal change disease, which presented with the typical triad and was clinically diagnosed.

CASE PRESENTATION

A 24-year-old Chinese woman was admitted to the hospital with 2 weeks of foamy urine and edema of the eyelid and lower limbs. After admission, the examination indicated nephrotic syndrome and total visceral transposition. Computed tomography imaging revealed sinusitis bronchiectasis, and she was diagnosed with minimal change disease with Kartagener syndrome. A renal biopsy revealed minimal changes. After symptomatic antiinflammatory therapy, the patient was given telmisartan 50 mg orally once daily to reduce urinary protein levels. A total of 1 month after discharge, her 24-h urine protein content was < 1 g, with normal liver function and improved kidney disease.

CONCLUSION

We describe a rare case of Kartagener syndrome accompanied by glomerular disease and minimal change disease. The patient was treated symptomatically with antiinflammatory agents and will be monitored long term. We believe our findings will provide valuable guidance and reference for the treatment of such cases in the future.

Assessment of liquid media requirements for storing and evaluating respiratory cilia motility

Mucociliary clearance is critical for maintaining normal lung function. Respiratory cilia which drive mucociliary clearance are commonly studied by measuring cilia beat frequency (CBF). There is currently significant variation within the literature regarding what is a normal value for CBF, this may be due in part to the large variety of liquid media used to suspend, maintain, and image ciliated cells. This study aimed to conduct a thorough examination to assess how media choice influences respiratory cilia motility. To accomplish this, Adult C57/BL6 mouse trachea samples were incubated in eight commonly used liquid media including: Saline, Dulbecco's Phosphate-Buffered Saline (DPBS), Hanks' Balanced Salt Solution (HBSS), Medium 199 (M199), Dulbecco's Modified Eagle's Medium (DMEM), Roswell Park Memorial Institute Medium (RPMI), Minimum Essential Medium (MEM), and Leibovitz's L-15 Medium (L-15); with or without 10% FBS supplementation. The effects of storage time (0-12 hours) and storage temperature (4 °C or room temperature) were also assessed. All media except saline were found to be equally effective in maintaining cilia function in airway samples that were freshly harvested and immediately imaged. Saline, however, significantly reduced the number of cells with motile cilia. A more complex pattern emerged when samples were stored before imaging. In saline, cilia function was significantly impaired after just one hour of storage. Samples stored in all other media showed strong maintenance of motile cilia function, with only minor changes. Notably, cilia function was better preserved with storage at 4 °C, while room temperature storage generally led to significant increases in CBF, especially in media containing FBS. Lastly, FBS supplementation was essential for maintaining cilia motility in L-15 media, as L-15 without FBS resulted in significant decreases in cilia motility following storage at either 4 °C or room temperature. In conclusion, saline should only be used if cilia are to be imaged immediately, as cilia stored in saline quickly lose motile function. All other commonly used media appear equally capable of maintaining motile cilia function for up to 12 hours when stored at 4 °C. Surprisingly, DPBS was just as effective as more expensive media in preserving ciliated samples. Storing ciliated tissue at room temperature generally leads to increased CBF, particularly in media containing FBS. Finally, L-15 media alone specifically requires the addition of 10% FBS to maintain cilia motility. These findings provide a valuable foundation for standardizing the handling, collection, and transport of ciliated samples for motile cilia assessment.

Evaluation of the Clinical and Genetic Characteristics of Primary Ciliary Dyskinesia Patients With Situs Inversus Totalis

BACKGROUND

Situs inversus totalis (SIT) is present in approximately 40%-50% of patients with primary ciliary dyskinesia (PCD). We evaluated the relationships between novel genetic results and the clinical and radiological characteristics of PCD patients with SIT.

METHODS

The study included 48 patients diagnosed with PCD and SIT. Demographic and clinical features, disease-related scores (Bhalla, Primary Ciliary Dyskinesia Rule [PICADAR], and American Thoracic Society [ATS]), and genetic analyses were retrospectively assessed.

RESULTS

The median age of patients was 13 (6.5-16) years, and parental consanguinity was observed in 43 (89.58%) patients. Bhalla score was available in 31 patients and "moderate and severe" score was observed in 19 (61.29%) patients. The median PICADAR score was 10 (8-11), and 34 (70.83%) patients had a high (≥ 10) PICADAR score. The ATS score was found to be 4 in 24 (50%) patients and 3 in 20 (43.75%) patients. Genetic data were available in 40 patients and mutations were found in 27 (67.5%) patients. The most common pathogenic variants were DNAH5 in 8 (20%), CCDC103 in 4 (10%), and CCDC39 in 3 (7.5%) patients. Subjects with any genetic variants may be older, have a greater frequency of parental consanguinity, higher Bhalla score, and higher ATS score (p < 0.05). DNAH5 mutation was associated with a lower likelihood of neonatal ICU stay and neonatal respiratory distress-related symptoms (p = 0.036 and 0.015, respectively).

CONCLUSIONS

Situs abnormalities may be a warning sign for the early diagnosis of PCD. Early diagnosis of PCD through genetic analysis is important for preventing chronic lung pathologies and predicting prognosis and may improve the quality of life.

Undocking of an extensive ciliary network induces proteostasis and cell fate switching resulting in severe primary ciliary dyskinesia

Primary ciliary dyskinesia is a rare monogenic syndrome that is associated with chronic respiratory disease, infertility, and laterality defects. Although more than 50 genes causative of primary ciliary dyskinesia have been identified, variants in the genes encoding coiled-coil domain-containing 39 (CCDC39) and CCDC40 in particular cause severe disease that is not explained by loss of ciliary motility alone. Here, we sought to understand the consequences of these variants on cellular functions beyond impaired motility. We used human cells with pathogenic variants in CCDC39 and CCDC40, Chlamydomonas reinhardtii genetics, cryo-electron microscopy, and proteomics to define perturbations in ciliary assembly and cilia stability, as well as multiple motility-independent pathways. Analysis of proteomics of cilia from patient cells identified that the absence of the axonemal CCDC39/CCDC40 heterodimer resulted in the loss of a network of more than 90 ciliary structural proteins, including 14 that were defined as ciliary address recognition proteins, which provide docking for the missing structures. The absence of the network impaired microtubule architecture, activated cell quality control pathways, switched multiciliated cell fate to mucus-producing cells and resulted in a defective periciliary barrier. In CCDC39 variant cells, these phenotypes were reversed through expression of a normal CCDC39 transgene. These findings indicate that the CCDC39/CCDC40 heterodimer functions as a scaffold to support the assembly of an extensive network of ciliary proteins, whose loss results in both motility-dependent and motility-independent phenotypes that may explain the severity of disease. Gene therapy might be a potential treatment option to be explored in future studies.

Plasmid Gene Therapy for Monogenic Disorders: Challenges and Perspectives

Monogenic disorders are a group of human diseases caused by mutations in single genes. While some disease-altering treatments offer relief and slow the progression of certain conditions, the majority of monogenic disorders still lack effective therapies. In recent years, gene therapy has appeared as a promising approach for addressing genetic disorders. However, despite advancements in gene manipulation tools and delivery systems, several challenges remain unresolved, including inefficient delivery, lack of sustained expression, immunogenicity, toxicity, capacity limitations, genomic integration risks, and limited tissue specificity. This review provides an overview of the plasmid-based gene therapy techniques and delivery methods currently employed for monogenic diseases, highlighting the challenges they face and exploring potential strategies to overcome these barriers.

Motile Cilia in Female and Male Reproductive Tracts and Fertility

Motile cilia are evolutionarily conserved organelles. In humans, multiciliated cells (MCCs), assembling several hundred motile cilia on their apical surface, are components of the monolayer epithelia lining lower and upper airways, brain ventricles, and parts of the reproductive tracts, the fallopian tube and uterus in females, and efferent ductules in males. The coordinated beating of cilia generates a force that enables a shift of the tubular fluid, particles, or cells along the surface of the ciliated epithelia. Uncoordinated or altered cilia motion or cilia immotility may result in subfertility or even infertility. Here, we summarize the current knowledge regarding the localization and function of MCCs in the human reproductive tracts, discuss how cilia and cilia beating-generated fluid flow directly and indirectly contribute to the processes in these organs, and how lack or improper functioning of cilia influence human fertility.

Move-PCD-a multi-center longitudinal randomized controlled superiority trial on the effect of a 6-month individualized supported physical activity (PA) program on quality of life (QoL) in children, adolescents, and adults with primary ciliary dyskinesia

BACKGROUND

Primary ciliary dyskinesia (PCD) is a rare genetical disease with malfunction of the motile cilia leading to impaired muco-ciliary clearance in the respiratory tract. There is no cure for PCD, only supportive therapy aimed at minimizing the progression of the disease and improving the patient's quality of life (QoL). Physical activity (PA) is one of these recommended supportive therapies for people with PCD (pwPCD). However, there is no scientific evidence to support this recommendation. In addition, regular medical advice to increase PA remains largely ineffective in pwPCD.

METHODS

To test the main hypothesis, that an individualized and supported PA program leads to a better QoL 6 months after randomization (QoL-PCD questionnaire) compared to usual recommendation in pwPCD, 158 pwPCD aged 7 to 55 years are to be included in this multi-center randomized controlled trial (RCT). After the screening visit, a 1:1 randomization stratified by age group and FEV1 will be performed. A QoL-PCD questionnaire, motor test, and lung function will be carried out at regular intervals in both groups. PA is recorded in both groups using activity trackers during the study period. The main aim of the trial is to estimate the difference in the change of QoL between the groups after 6 months. Therefore, our full analysis set consists of all randomized patients and analysis is performed using the intention-to-treat principle. Statistical software R ( http://www.r-project.org ) is used. Ethical approvement without any reservations: RUB Bochum Ethics Committee (No. 23-7938; December 4, 2023). Recruitment start: March 2024.

DISCUSSION

Limitations result from the rarity of PCD with its broad disease spectrum and the large age range. These are reduced by stratified randomization and the measurement of the individual change in QoL as primary endpoint. In our view, only a PA program tailored to individual needs with close contact to trainers offers the chance to meet personal needs of pwPCD and to establish PA as a pillar of therapy in the long term. The study protocol explains all procedures and methods of recruitment, implementation of the study visits and intervention, measures for patient and data safety, and for minimizing risks and bias.

TRIAL REGISTRATION

German Clinical Trials Register (DRKS) 00033030. Registered on December 7, 2023. Update 10 July 2024. STUDY PROTOCOL VERSION 10: Version 1.2; 12 June 2024.

Nontuberculous Mycobacteria, Mucociliary Clearance, and Bronchiectasis

Nontuberculous mycobacteria (NTM) are environmental and ubiquitous, but only a few species are associated with disease, often presented as nodular/bronchiectatic or cavitary pulmonary forms. Bronchiectasis, airways dilatations characterized by chronic productive cough, is the main presentation of NTM pulmonary disease. The current Cole's vicious circle model for bronchiectasis proposes that it progresses from a damaging insult, such as pneumonia, that affects the respiratory epithelium and compromises mucociliary clearance mechanisms, allowing microorganisms to colonize the airways. An important bronchiectasis risk factor is primary ciliary dyskinesia, but other ciliopathies, such as those associated with connective tissue diseases, also seem to facilitate bronchiectasis, as may occur in Lady Windermere syndrome, caused by M. avium infection. Inhaled NTM may become part of the lung microbiome. If the dose is too large, they may grow excessively as a biofilm and lead to disease. The incidence of NTM pulmonary disease has increased in the last two decades, which may have influenced the parallel increase in bronchiectasis incidence. We propose that ciliary dyskinesia is the main promoter of bronchiectasis, and that the bacteria most frequently involved are NTM. Restoration of ciliary function and impairment of mycobacterial biofilm formation may provide effective therapeutic alternatives to antibiotics.

Loss of an extensive ciliary connectome induces proteostasis and cell fate switching in a severe motile ciliopathy

Motile cilia have essential cellular functions in development, reproduction, and homeostasis. Genetic causes for motile ciliopathies have been identified, but the consequences on cellular functions beyond impaired motility remain unknown. Variants in CCDC39 and CCDC40 cause severe disease not explained by loss of motility. Using human cells with pathological variants in these genes, Chlamydomonas genetics, cryo-electron microscopy, single cell RNA transcriptomics, and proteomics, we identified perturbations in multiple cilia-independent pathways. Absence of the axonemal CCDC39/CCDC40 heterodimer results in loss of a connectome of over 90 proteins. The undocked connectome activates cell quality control pathways, switches multiciliated cell fate, impairs microtubule architecture, and creates a defective periciliary barrier. Both cilia-dependent and independent defects are likely responsible for the disease severity. Our findings provide a foundation for reconsidering the broad cellular impact of pathologic variants in ciliopathies and suggest new directions for therapies.

Gene dosage of independent dynein arm motor preassembly factors influences cilia assembly in Chlamydomonas reinhardtii

Motile cilia assembly utilizes over 800 structural and cytoplasmic proteins. Variants in approximately 58 genes cause primary ciliary dyskinesia (PCD) in humans, including the dynein arm (pre)assembly factor (DNAAF) gene DNAAF4. In humans, outer dynein arms (ODAs) and inner dynein arms (IDAs) fail to assemble motile cilia when DNAAF4 function is disrupted. In Chlamydomonas reinhardtii, a ciliated unicellular alga, the DNAAF4 ortholog is called PF23. The pf23-1 mutant assembles short cilia and lacks IDAs, but partially retains ODAs. The cilia of a new null allele (pf23-4) completely lack ODAs and IDAs and are even shorter than cilia from pf23-1. In addition, PF23 plays a role in the cytoplasmic modification of IC138, a protein of the two-headed IDA (I1/f). As most PCD variants in humans are recessive, we sought to test if heterozygosity at two genes affects ciliary function using a second-site non-complementation (SSNC) screening approach. We asked if phenotypes were observed in diploids with pairwise heterozygous combinations of 21 well-characterized ciliary mutant Chlamydomonas strains. Vegetative cultures of single and double heterozygous diploid cells did not show SSNC for motility phenotypes. When protein synthesis is inhibited, wild-type Chlamydomonas cells utilize the pool of cytoplasmic proteins to assemble half-length cilia. In this sensitized assay, 8 double heterozygous diploids with pf23 and other DNAAF mutations show SSNC; they assemble shorter cilia than wild-type. In contrast, double heterozygosity of the other 203 strains showed no effect on ciliary assembly. Immunoblots of diploids heterozygous for pf23 and wdr92 or oda8 show that PF23 is reduced by half in these strains, and that PF23 dosage affects phenotype severity. Reductions in PF23 and another DNAAF in diploids affect the ability to assemble ODAs and IDAs and impedes ciliary assembly. Thus, dosage of multiple DNAAFs is an important factor in cilia assembly and regeneration.

RBL2 represses the transcriptional activity of Multicilin to inhibit multiciliogenesis

A core pathophysiologic feature underlying many respiratory diseases is multiciliated cell dysfunction, leading to inadequate mucociliary clearance. Due to the prevalence and highly variable etiology of mucociliary dysfunction in respiratory diseases, it is critical to understand the mechanisms controlling multiciliogenesis that may be targeted to restore functional mucociliary clearance. Multicilin, in a complex with E2F4, is necessary and sufficient to drive multiciliogenesis in airway epithelia, however this does not apply to all cell types, nor does it occur evenly across all cells in the same cell population. In this study we further investigated how co-factors regulate the ability of Multicilin to drive multiciliogenesis. Combining data in mouse embryonic fibroblasts and human bronchial epithelial cells, we identify RBL2 as a repressor of the transcriptional activity of Multicilin. Knockdown of RBL2 in submerged cultures or phosphorylation of RBL2 in response to apical air exposure, in the presence of Multicilin, allows multiciliogenesis to progress. These data demonstrate a dynamic interaction between RBL2 and Multicilin that regulates the capacity of cells to differentiate and multiciliate. Identification of this mechanism has important implications for facilitating MCC differentiation in diseases with impaired mucociliary clearance.

Impact of primary ciliary dyskinesia: Beyond sinobronchial syndrome in Japan

Primary ciliary dyskinesia (PCD) is a rare genetic disorder characterized by impaired motile cilia function, particularly in the upper and lower airways. To date, more than 50 causative genes related to the movement, development, and maintenance of cilia have been identified. PCD mostly follows an autosomal recessive inheritance pattern, in which PCD symptoms manifest only in the presence of pathogenic variants in both alleles. Several genes causing PCD have been recently identified that neither lead to situs inversus nor cause definitive abnormalities in ciliary ultrastructure. Importantly, the distribution of disease-causing genes and pathogenic variants varies depending on ethnicity. In Japan, homozygosity for a ∼27.7-kb deletion of DRC1 is estimated to be the most common cause of PCD, presumably as a founder mutation. The clinical picture of PCD is similar to that of sinobronchial syndrome, thus making its differentiation from diffuse panbronchiolitis and other related disorders difficult. Given the diagnostic challenges, many cases remain undiagnosed or misdiagnosed, particularly in adults. While no fundamental cure is currently available, lifelong medical subsidies are provided in Japan, and proper respiratory management, along with continued prevention and treatment of infections, is believed to mitigate the decline in respiratory function. Timely action will be necessary when specific treatments for PCD become available in the future. This narrative review focuses on variations in the disease status of PCD in a non-Western country.

RBL2 represses the transcriptional activity of Multicilin to inhibit multiciliogenesis

A core pathophysiologic feature underlying many respiratory diseases is multiciliated cell dysfunction, leading to inadequate mucociliary clearance. Due to the prevalence and highly variable etiology of mucociliary dysfunction in respiratory diseases, it is critical to understand the mechanisms controlling multiciliogenesis that may be targeted to restore functional mucociliary clearance. Multicilin, in a complex with E2F4, is necessary and sufficient to drive multiciliogenesis in airway epithelia, however this does not apply to all cell types, nor does it occur evenly across all cells in the same cell population. In this study we further investigated how co-factors regulate the ability of Multicilin to drive multiciliogenesis. Combining data in mouse embryonic fibroblasts and human bronchial epithelial cells, we identify RBL2 as a repressor of the transcriptional activity of Multicilin. Knockdown of RBL2 in submerged cultures or phosphorylation of RBL2 in response to apical air exposure, in the presence of Multicilin, allows multiciliogenesis to progress. These data demonstrate a dynamic interaction between RBL2 and Multicilin that regulates the capacity of cells to differentiate and multiciliate. Identification of this mechanism has important implications for facilitating MCC differentiation in diseases with impaired mucociliary clearance.