Mucociliary Clearance Disorder Research Articles

Growing from common ground: nontuberculous mycobacteria and bronchiectasis.

Bronchiectasis and nontuberculous mycobacteria (NTM) are intricately intertwined, with NTM capable of being both a cause and consequence of bronchiectatic disease. This narrative review focuses on the common ground of bronchiectasis and NTM pulmonary disease (NTM-PD) in terms of diagnostic approach, underlying risk factors and treatment strategies. NTM-PD diagnosis relies on a combination of clinical, radiological and microbiological criteria. Although their epidemiology is complicated by detection and reporting biases, the prevalence and pathogenicity of NTM species vary geographically, with Mycobacterium avium complex and Mycobacterium abscessus subspecies most frequently isolated in bronchiectasis-associated NTM-PD. Diagnosis of nodular bronchiectatic NTM-PD should prompt investigation of host factors, including disorders of mucociliary clearance, connective tissue diseases and immunodeficiencies, either genetic or acquired. Treatment of NTM-PD in bronchiectasis involves a multidisciplinary approach and considers the (sub)species involved, disease severity and comorbidities. Current guideline-based antimicrobial treatment of NTM-PD is considered long, cumbersome and unsatisfying in terms of outcomes. Novel treatment regimens and strategies are being explored, including rifampicin-free regimens and inclusion of clofazimine and inhaled antibiotics. Host-directed therapies, such as immunomodulators and cytokine-based therapies, might enhance antimycobacterial immune responses. Optimising supportive care, as well as pathogen- and host-directed strategies, is crucial, highlighting the need for personalised approaches tailored to individual patient needs. Further research is warranted to elucidate the complex interplay between host and mycobacterial factors, informing more effective management strategies.

The Non-Invasive Detection of Pulmonary Exacerbations in Disorders of Mucociliary Clearance with Breath Analysis: A Systematic Review.

Background: Disorders of mucociliary clearance, such as cystic fibrosis (CF), primary ciliary dyskinesia (PCD) and bronchiectasis of unknown origin, are characterised by periods with increased respiratory symptoms, referred to as pulmonary exacerbations. These exacerbations are hard to predict and associated with lung function decline and the loss of quality of life. To optimise treatment and preserve lung function, there is a need for non-invasive and reliable methods of detection. Breath analysis might be such a method. Methods: We systematically reviewed the existing literature on breath analysis to detect pulmonary exacerbations in mucociliary clearance disorders. Extracted data included the study design, technique of measurement, definition of an exacerbation, identified compounds and diagnostic accuracy. Results: Out of 244 identified articles, 18 were included in the review. All studies included patients with CF and two also with PCD. Age and the definition of exacerbation differed between the studies. There were five that measured volatile organic compounds (VOCs) in exhaled breath using gas chromatography with mass spectrometry, two using an electronic nose and eleven measured organic compounds in exhaled breath condensate. Most studies showed a significant correlation between pulmonary exacerbations and one or multiple compounds, mainly hydrocarbons and cytokines, but the validation of these results in other studies was lacking. Conclusions: The detection of pulmonary exacerbations by the analysis of compounds in exhaled breath seems possible but is not near clinical application due to major differences in results, study design and the definition of an exacerbation. There is a need for larger studies, with a longitudinal design, international accepted definition of an exacerbation and validation of the results in independent cohorts.

IFT74 variants cause skeletal ciliopathy and motile cilia defects in mice and humans.

Motile and non-motile cilia play critical roles in mammalian development and health. These organelles are composed of a 1000 or more unique proteins, but their assembly depends entirely on proteins synthesized in the cell body and transported into the cilium by intraflagellar transport (IFT). In mammals, malfunction of non-motile cilia due to IFT dysfunction results in complex developmental phenotypes that affect most organs. In contrast, disruption of motile cilia function causes subfertility, disruption of the left-right body axis, and recurrent airway infections with progressive lung damage. In this work, we characterize allele specific phenotypes resulting from IFT74 dysfunction in human and mice. We identified two families carrying a deletion encompassing IFT74 exon 2, the first coding exon, resulting in a protein lacking the first 40 amino acids and two individuals carrying biallelic splice site mutations. Homozygous exon 2 deletion cases presented a ciliary chondrodysplasia with narrow thorax and progressive growth retardation along with a mucociliary clearance disorder phenotype with severely shorted cilia. Splice site variants resulted in a lethal skeletal chondrodysplasia phenotype. In mice, removal of the first 40 amino acids likewise results in a motile cilia phenotype but with little effect on primary cilia structure. Mice carrying this allele are born alive but are growth restricted and developed hydrocephaly in the first month of life. In contrast, a strong, likely null, allele of Ift74 in mouse completely blocks ciliary assembly and causes severe heart defects and midgestational lethality. In vitro studies suggest that the first 40 amino acids of IFT74 are dispensable for binding of other IFT subunits but are important for tubulin binding. Higher demands on tubulin transport in motile cilia compared to primary cilia resulting from increased mechanical stress and repair needs could account for the motile cilia phenotype observed in human and mice.

Муколитическая терапия при респираторных заболеваниях у детей

Рассмотрены патогенетические механизмы нарушений мукоцилиарного транспорта при респираторной патологии у детей. Произведен анализ лекарственных средств муколитического действия, их эффективности и безопасности.

Mutations in TP73 cause impaired mucociliary clearance and lissencephaly

TP73 belongs to the TP53 family of transcription factors and has therefore been well studied in cancer research. Studies in mice, however, have revealed non-oncogenic activities related to multiciliogenesis. Utilizing whole-exome sequencing analysis in a cohort of individuals with a mucociliary clearance disorder and cortical malformation, we identified homozygous loss-of-function variants in TP73 in seven individuals from five unrelated families. All affected individuals exhibit a chronic airway disease as well as a brain malformation consistent with lissencephaly. We performed high-speed video microscopy, immunofluorescence analyses, and transmission electron microscopy in respiratory epithelial cells after spheroid or air liquid interface culture to analyze ciliary function, ciliary length, and number of multiciliated cells (MCCs). The respiratory epithelial cells studied display reduced ciliary length and basal bodies mislocalized within the cytoplasm. The number of MCCs is severely reduced, consistent with a reduced numberof cells expressing the transcription factors crucial for multiciliogenesis (FOXJ1, RFX2). Our data demonstrate that autosomal-recessive deleterious variants in the TP53 family member TP73 cause a mucociliary clearance disorder due to a defect in MCC differentiation.

Three-dimensional assessment of bronchiectasis in a mouse model of mucociliary clearance disorder.

Synchrotron-based imaging allows for detection of bronchiectasis-like phenotypes in mice with mucociliary clearance disorders https://bit.ly/3gXGdP3

Super-Resolution Microscopy and FIB-SEM Imaging Reveal Parental Centriole-Derived, Hybrid Cilium in Mammalian Multiciliated Cells.

Motile cilia are cellular beating machines that play a critical role in mucociliary clearance, cerebrospinal fluid movement, and fertility. In the airways, hundreds of motile cilia present on the surface of a multiciliated epithelia cell beat coordinately to protect the epithelium from bacteria, viruses, and harmful particulates. During multiciliated cell differentiation, motile cilia are templated from basal bodies, each extending a basal foot-an appendage linking motile cilia together to ensure coordinated beating. Here, we demonstrate that among the many motile cilia of a multiciliated cell, a hybrid cilium with structural features of both primary and motile cilia is harbored. The hybrid cilium is conserved in mammalian multiciliated cells, originates from parental centrioles, and its cellular position is biased and dependent on ciliary beating. Furthermore, we show that the hybrid cilium emerges independently of other motile cilia and functions in regulating basal body alignment.

Morphological and functional state of the nasal cavity after surgical interventions in the vertical section of the lacrimal ducts

Objectives - to compare the condition of the nasal cavity after a dacryocystorhinostomy of external and endonasal access. Material and methods. Comparative assessment of the results of the study of 96 patients with chronic dacryocystitis was done. The patients were divided into 2 groups: group 1 included persons who underwent the videoendoscopic endonasal dacryocystorhinostomy; group 2 - patients with external dacryocystorhinostomy. For all the participants, there were registered the complaints and anamnesis, the data of video-endoscopy of the nasal cavity, anterior active rhinomanometry, transport and olfactory functions. The information on the state of the nasal cavity after surgery in the vertical section of the lacrimal ducts was also obtained. Results. In both groups we revealed the changes in the mucous membrane, in the anatomical structures of the nasal cavity, in the mobility of the ciliated epithelium, respiratory functions and olfaction. When comparing the results in both groups, the statistically significant differences were found in the questionnaire data - a complaint of lacrimation, and the data on the mucociliary clearance disorders (p

Evaluation of mucociliary clearance in the postoperative period after a maxillary sinus surgery

Objectives - evaluation of the local function of the mucociliary clearance (MCC) in the postoperative period in patients with foreign bodies in the maxillary sinuses, who have undergone various surgical treatment. Material and methods. Using an original analysis technique for highspeed digital video recording of a microscopic picture of a specimen, obtained by brush biopsy from specific regions of the nasal cavity and paranasal sinus under endoscopic control, the MCC of the nasal mucosa was evaluated in the control group (n=60) and in the group of patients, who received various surgery (n=60) of maxillary sinuses. Results. We obtained the data on persistent and apparent local MCC disorders in the field of the surgical intervention in the postoperative period. Conclusion. Surgical interventions with access not in the area of the natural ostium of the maxillary sinus are more gentle, since they do not injure the mucociliary clearance in the key region - the ostium.

Chronic Rhinosinusitis in Children: Pathophysiology, Evaluation, and Medical Management.

Pediatric chronic rhinosinusitis (CRS) is a common disorder that carries significant morbidity. The diagnosis requires sinus symptoms that persist despite standard medical therapy greater than 3months. Viral infections, allergies, and anatomic differences in children lead to chronic obstruction of the osteomeatal complex. Chronic rhinosinusitis as a diagnosis is a conglomeration of multiple phenotypes and endotypes. As such, the diagnosis and management are complex. New survey studies provide some consensus on prevalence and management of this disease in children. In this review, we highlight the differential diagnosis of pediatric CRS, including non-eosinophilic/infectious variants, eosinophilic variants with and without nasal polyps, allergic fungal sinusitis, aspirin-exacerbated respiratory disease, primary immunodeficiency, and disorders of mucociliary clearance. Further, we detail treatment options that should be considered. Finally, we feature emerging potential treatment options of CRS, including anti-immunoglobulin E, interleukin-5, and interleukin-4 receptor alpha subunit.

Therapeutic Approach to Mucociliary Disorders

Disorders of mucociliary clearance (MCC) occur from thickening of the mucus so that cilia function is impaired. Or cilia may be impaired directly, as in chlorine exposure. Increased attention to MCC will aid in the reduction of antibiotic abuse.

GEMC1 is a critical regulator of multiciliated cell differentiation.

The generation of multiciliated cells (MCCs) is required for the proper function of many tissues, including the respiratory tract, brain, and germline. Defects in MCC development have been demonstrated to cause a subclass of mucociliary clearance disorders termed reduced generation of multiple motile cilia (RGMC). To date, only two genes, Multicilin (MCIDAS) and cyclin O (CCNO) have been identified in this disorder in humans. Here, we describe mice lacking GEMC1 (GMNC), a protein with a similar domain organization as Multicilin that has been implicated in DNA replication control. We have found that GEMC1-deficient mice are growth impaired, develop hydrocephaly with a high penetrance, and are infertile, due to defects in the formation of MCCs in the brain, respiratory tract, and germline. Our data demonstrate that GEMC1 is a critical regulator of MCC differentiation and a candidate gene for human RGMC or related disorders.

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

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

GemC1 controls multiciliogenesis in the airway epithelium

Multiciliated cells are terminally differentiated, post-mitotic cells that form hundreds of motile cilia on their apical surface. Defects in multiciliated cells lead to disease, including mucociliary clearance disorders that result from ciliated cell disfunction in airways. The pathway controlling multiciliogenesis, however, remains poorly characterized. We showed that GemC1, previously implicated in cell cycle control, is a central regulator of ciliogenesis. GemC1 is specifically expressed in ciliated epithelia. Ectopic expression of GemC1 is sufficient to induce early steps of multiciliogenesis in airway epithelial cells ex vivo, upregulating McIdas and FoxJ1, key transcriptional regulators of multiciliogenesis. GemC1 directly transactivates the McIdas and FoxJ1 upstream regulatory sequences, and its activity is enhanced by E2F5 and inhibited by Geminin. GemC1-knockout mice are born with airway epithelia devoid of multiciliated cells. Our results identify GemC1 as an essential regulator of ciliogenesis in the airway epithelium and a candidate gene for mucociliary disorders.

Orphan disease of the nose and paranasal sinuses

Rare rhinological diseases are a diagnostic challenge. From the primary manifestation until the final diagnosis it may take several months or even up to years in which the disease progress is uncontrolled and the disease insufficiently treated. This results in (irreversible) damage and possibly life-threatening situations. The unexpected course of a (misdiagnosed) disease should lead to further diagnostic considerations and steps to detect the orphan disease at a stage as early as possible. In the present work granulomatous diseases of the nose and sinuses caused by mycobacteria, treponemes, klebsiella, fungi and protozoa as well as vasculitis, sarcoidosis, rosacea, the cocaine-induced midline destruction, the nasal extranodal NK/T-cell lymphoma and cholesterol granuloma are discussed. Furthermore diseases with disorders of mucociliary clearance as the primary ciliary dyskinesia and cystic fibrosis are presented taking into account the current literature.

Mutations in CCNO and MCIDAS lead to a mucociliary clearance disorder due to reduced generation of multiple motile cilia

Mutations in CCNO and MCIDAS lead to a mucociliary clearance disorder due to reduced generation of multiple motile cilia

Mcidas and GemC1 are key regulators for the generation of multiciliated ependymal cells in the adult neurogenic niche.

Multiciliated cells are abundant in the epithelial surface of different tissues, including cells lining the walls of the lateral ventricles in the brain and the airway epithelium. Their main role is to control fluid flow and defects in their differentiation are implicated in many human disorders, such as hydrocephalus, accompanied by defects in adult neurogenesis and mucociliary disorder in the airway system. Here we show that Mcidas, which is mutated in human mucociliary clearance disorder, and GemC1 (Gmnc or Lynkeas), previously implicated in cell cycle progression, are key regulators of multiciliated ependymal cell generation in the mouse brain. Overexpression and knockdown experiments show that Mcidas and GemC1 are sufficient and necessary for cell fate commitment and differentiation of radial glial cells to multiciliated ependymal cells. Furthermore, we show that GemC1 and Mcidas operate in hierarchical order, upstream of Foxj1 and c-Myb transcription factors, which are known regulators of ependymal cell generation, and that Notch signaling inhibits GemC1 and Mcidas function. Our results suggest that Mcidas and GemC1 are key players in the generation of multiciliated ependymal cells of the adult neurogenic niche.

Diagnostics of disorders of mucociliary clearance in patients with chronic obstructive pulmonary disease by determining content of medium weight molecules in sputum.

Investigation of mucociliary clearance (MCC) condition in 90 patients with COPD was performed according to the stage of the disease by determining the level of biochemical indicator of sputum - medium weight molecules (MWM). To determine the effect of chronic inflammation in the respiratory tract on a general condition of the organism, MWM content in blood serum was investigated. To reduce the influence of comorbidity on MWM content in blood serum, patients with COPD without or with mild comorbidity in remission were selected, and the results were compared with those of healthy people (control group, n = 20). The results showed a direct correlation between the severity of airflow limitation and concentration of MWM in sputum, this was accompanied by increasing of viscosity and adhesive performance of sputum and violation of the optimal conditions of MCC functioning. The fact established allows to use determination of MWM content in sputum of COPD patients as a noninvasive and accessible for pulmonology practice method, which allows to quickly and adequately assess MCC condition and aggregate of metabolic abnormalities in patients’ respiratory tract. Chronic inflammation in respiratory tract is accompanied by disorders of determined indicators in the serum as well, but increase of MWM content in sputum is specific, while the accumulation of MWM in serum of patients with COPD is not specific.

MCIDAS mutations result in a mucociliary clearance disorder with reduced generation of multiple motile cilia.

Reduced generation of multiple motile cilia (RGMC) is a rare mucociliary clearance disorder. Affected persons suffer from recurrent infections of upper and lower airways because of highly reduced numbers of multiple motile respiratory cilia. Here we report recessive loss-of-function and missense mutations in MCIDAS-encoding Multicilin, which was shown to promote the early steps of multiciliated cell differentiation in Xenopus. MCIDAS mutant respiratory epithelial cells carry only one or two cilia per cell, which lack ciliary motility-related proteins (DNAH5; CCDC39) as seen in primary ciliary dyskinesia. Consistent with this finding, FOXJ1-regulating axonemal motor protein expression is absent in respiratory cells of MCIDAS mutant individuals. CCNO, when mutated known to cause RGMC, is also absent in MCIDAS mutant respiratory cells, consistent with its downstream activity. Thus, our findings identify Multicilin as a key regulator of CCNO/FOXJ1 for human multiciliated cell differentiation, and highlight the 5q11 region containing CCNO and MCIDAS as a locus underlying RGMC.

Multicilin drives centriole biogenesis via E2f proteins.

Multiciliate cells employ hundreds of motile cilia to produce fluid flow, which they nucleate and extend by first assembling hundreds of centrioles. In most cells, entry into the cell cycle allows centrioles to undergo a single round of duplication, but in differentiating multiciliate cells, massive centriole assembly occurs in G0 by a process initiated by a small coiled-coil protein, Multicilin. Here we show that Multicilin acts by forming a ternary complex with E2f4 or E2f5 and Dp1 that binds and activates most of the genes required for centriole biogenesis, while other cell cycle genes remain off. This complex also promotes the deuterosome pathway of centriole biogenesis by activating the expression of deup1 but not its paralog, cep63. Finally, we show that this complex is disabled by mutations in human Multicilin that cause a severe congenital mucociliary clearance disorder due to reduced generation of multiple cilia. By coopting the E2f regulation of cell cycle genes, Multicilin drives massive centriole assembly in epithelial progenitors in a manner required for multiciliate cell differentiation.