Primary ciliary dyskinesia: a review

A quantitative super-resolution imaging toolbox for diagnosis of motile ciliopathies

Airway clearance of pathogens and particulates relies on motile cilia. Impaired cilia motility can lead to reduction in lung function, lung transplant, or death in some cases. More than 50 proteins regulating cilia motility are linked to primary ciliary dyskinesia (PCD), a heterogeneous, mainly recessive genetic lung disease. Accurate PCD molecular diagnosis is essential for identifying therapeutic targets and for initiating therapies that can stabilize lung function, thereby reducing socioeconomic impact of the disease. To date, PCD diagnosis has mainly relied on nonquantitative methods that have limited sensitivity or require a priori knowledge of the genes involved. Here, we developed a quantitative super-resolution microscopy workflow: (i) to increase sensitivity and throughput, (ii) to detect structural defects in PCD patients' cells, and (iii) to quantify motility defects caused by yet to be found PCD genes. Toward these goals, we built a localization map of PCD proteins by three-dimensional structured illumination microscopy and implemented quantitative image analysis and machine learning to detect protein mislocalization, we analyzed axonemal structure by stochastic optical reconstruction microscopy, and we developed a high-throughput method for detecting motile cilia uncoordination by rotational polarity. Together, our data show that super-resolution methods are powerful tools for improving diagnosis of motile ciliopathies.

Knowledge of Rare Respiratory Diseases among Paediatricians and Medical School Students

Alpha-1-antitrypsin deficiency (AATD) and primary ciliary dyskinesia (PCD) are underdiagnosed rare diseases showing a median diagnostic delay of five to ten years, which has negative effects on patient prognosis. Lack of awareness and education among healthcare professionals involved in the management of these patients have been suggested as possible causes. Our aim was to assess knowledge of these diseases among paediatricians and medical school students to determine which knowledge areas are most deficient. A survey was designed with questions testing fundamental aspects of the diagnosis and treatment of AATD and PCD. A score equal to or greater than 50% of the maximum score was set as the level necessary to ensure a good knowledge of both diseases. Our results indicate a profound lack of knowledge of rare respiratory diseases among paediatric professionals and medical students, suggesting that it is necessary to increase rare respiratory diseases training among all physicians responsible for suspecting and diagnosing them; this will allow early diagnosis and the setup of preventive measures and appropriate early-stage treatment. The first step in closing this knowledge gap could be to include relevant material in the medical syllabus.

Stabilization of primary cilia reduces abortive cell cycle re-entry to protect injured adult CNS neurons from apoptosis

Abortive cell cycle (ACC) re-entry of apoptotic neurons is a recently characterized phenomenon that occurs after central nervous system (CNS) injury or over the course of CNS disease. Consequently, inhibiting cell cycle progression is neuroprotective in numerous CNS pathology models. Primary cilia are ubiquitous, centriole-based cellular organelles that prevent cell cycling, but their ability to modulate abortive cell cycle has not been described. Here, we show that neuronal cilia are ablated in-vitro and in-vivo following injury by hypoxia or optic nerve transection (ONT), respectively. Furthermore, forced cilia resorption sensitized neurons to these injuries and enhanced cell death. In contrast, pharmacological inhibition or shRNA knockdown of the proteins that disassemble the cilia increased neuron survival and decreased the phosphorylation of retinoblastoma (Rb), a master switch for cell cycle re-entry. Our findings show that the stabilization of neuronal primary cilia inhibits, at least transiently, apoptotic cell cycling, which has implications for future therapeutic strategies that halt or slow the progression of neurodegenerative diseases and acute CNS injuries.

Severe pulmonary disease in an adult primary ciliary dyskinesia population in Brazil

Primary Ciliary Dyskinesia (PCD) is underdiagnosed in Brazil. We enrolled patients from an adult service of Bronchiectasis over a two-year period in a cross-sectional study. The inclusion criteria were laterality disorders (LD), cough with recurrent infections and the exclusion of other causes of bronchiectasis. Patients underwent at least two of the following tests: nasal nitric oxide, ciliary movement and analysis of ciliary immunofluorescence, and genetic tests (31 PCD genes + CFTR gene). The clinical characterization included the PICADAR and bronchiectasis scores, pulmonary function, chronic Pseudomonas aeruginosa (cPA) colonization, exhaled breath condensate (EBC) and mucus rheology (MR). Forty-nine of the 500 patients were diagnosed with definite (42/49), probable (5/49), and clinical (2/49) PCD. Twenty-four patients (24/47) presented bi-allelic pathogenic variants in a total of 31 screened PCD genes. A PICADAR score > 5 was found in 37/49 patients, consanguinity in 27/49, LD in 28/49, and eight PCD sibling groups. FACED diagnosed 23/49 patients with moderate or severe bronchiectasis; FEV1 ≤ 50% in 25/49 patients, eight patients had undergone lung transplantation, four had been lobectomized and cPA+ was determined in 20/49. The EBC and MR were altered in all patients. This adult PCD population was characterized by consanguinity, severe lung impairment, genetic variability, altered EBC and MR.

Cinnamaldehyde in flavored e-cigarette liquids temporarily suppresses bronchial epithelial cell ciliary motility by dysregulation of mitochondrial function

Aldehydes in cigarette smoke (CS) impair mitochondrial function and reduce ciliary beat frequency (CBF), leading to diminished mucociliary clearance (MCC). However, the effects of aldehyde e-cigarette flavorings on CBF are unknown. The purpose of this study was to investigate whether cinnamaldehyde, a flavoring agent commonly used in e-cigarettes, disrupts mitochondrial function and impairs CBF on well-differentiated human bronchial epithelial (hBE) cells. To this end, hBE cells were exposed to diluted cinnamon-flavored e-liquids and vaped aerosol and assessed for changes in CBF. hBE cells were subsequently exposed to various concentrations of cinnamaldehyde to establish a dose-response relationship for effects on CBF. Changes in mitochondrial oxidative phosphorylation and glycolysis were evaluated by Seahorse Extracellular Flux Analyzer, and adenine nucleotide levels were quantified by HPLC. Both cinnamaldehyde-containing e-liquid and vaped aerosol rapidly yet transiently suppressed CBF, and exposure to cinnamaldehyde alone recapitulated this effect. Cinnamaldehyde impaired mitochondrial respiration and glycolysis in a dose-dependent manner, and intracellular ATP levels were significantly but temporarily reduced following exposure. Addition of nicotine had no effect on the cinnamaldehyde-induced suppression of CBF or mitochondrial function. These data indicate that cinnamaldehyde rapidly disrupts mitochondrial function, inhibits bioenergetic processes, and reduces ATP levels, which correlates with impaired CBF. Because normal ciliary motility and MCC are essential respiratory defenses, inhalation of cinnamaldehyde may increase the risk of respiratory infections in e-cigarette users.

The development and functions of multiciliated epithelia

Multiciliated cells are epithelial cells that are in contact with bodily fluids and are required for the proper function of major organs including the brain, the respiratory system and the reproductive tracts. Their multiple motile cilia beat unidirectionally to remove particles of external origin from their surface and/or drive cells or fluids into the lumen of the organs. Multiciliated cells in the brain are produced once, almost exclusively during embryonic development, whereas in respiratory tracts and oviducts they regenerate throughout life. In this Review, we provide a cell-to-organ overview of multiciliated cells and highlight recent studies that have greatly increased our understanding of the mechanisms driving the development and function of these cells in vertebrates. We discuss cell fate determination and differentiation of multiciliated cells, and provide a comprehensive account of their locations and functions in mammals.

Reactivation of flagellar motility in demembranated Leishmania reveals role of cAMP in flagellar wave reversal to ciliary waveform

The flagellum of parasitic trypanosomes is a multifunctional appendage essential for its viability and infectivity. However, the biological mechanisms that make the flagellum so dynamic remains unexplored. No method is available to access and induce axonemal motility at will to decipher motility regulation in trypanosomes. For the first time we report the development of a detergent-extracted/demembranated ATP-reactivated model for studying flagellar motility in Leishmania. Flagellar beat parameters of reactivated parasites were similar to live ones. Using this model we discovered that cAMP (both exogenous and endogenous) induced flagellar wave reversal to a ciliary waveform in reactivated parasites via cAMP-dependent protein kinase A. The effect was reversible and highly specific. Such an effect of cAMP on the flagellar waveform has never been observed before in any organism. Flagellar wave reversal allows parasites to change direction of swimming. Our findings suggest a possible cAMP-dependent mechanism by which Leishmania responds to its surrounding microenvironment, necessary for its survival. Our demembranated-reactivated model not only serves as an important tool for functional studies of flagellated eukaryotic parasites but has the potential to understand ciliary motility regulation with possible implication on human ciliopathies.

Diagnosis of primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a genetic disorder of ciliary structure or function. It results in mucus accumulation and bacterial colonization of the respiratory tract which leads to chronic upper and lower airway infections, organ laterality defects, and fertility problems. We review the respiratory signs and symptoms of PCD, as well as the screening tests for and diagnostic investigation of the disease, together with details related to ciliary function, ciliary ultrastructure, and genetic studies. In addition, we describe the difficulties in diagnosing PCD by means of transmission electron microscopy, as well as describing patient follow-up procedures.

Basal body multipotency and axonemal remodelling are two pathways to a 9+0 flagellum

Eukaryotic cilia/flagella exhibit two characteristic ultrastructures reflecting two main functions; a 9+2 axoneme for motility and a 9+0 axoneme for sensation and signalling. Whether, and if so how, they interconvert is unclear. Here we analyse flagellum length, structure and molecular composition changes in the unicellular eukaryotic parasite Leishmania during the transformation of a life cycle stage with a 9+2 axoneme (the promastigote) to one with a 9+0 axoneme (the amastigote). We show 9+0 axonemes can be generated by two pathways: by de novo formation and by restructuring of existing 9+2 axonemes associated with decreased intraflagellar transport. Furthermore, pro-basal bodies formed under conditions conducive for 9+2 axoneme formation can form a 9+0 axoneme de novo. We conclude that pro-centrioles/pro-basal bodies are multipotent and not committed to form either a 9+2 or 9+0 axoneme. In an alternative pathway structures can also be removed from existing 9+2 axonemes to convert them to 9+0.

Whether basal bodies are pre-committed to form 9+2 motile or 9+0 sensory axonemes and whether interconversion occurs between the two types of axonemes is not clear. Here, the authors used the unicellular eukaryote Leishmania as a model system to demonstrate that 9+0 axonemes can be formed de novo or by restructuring of 9+2 axonemes.

Number of nexin links detectable at standard electron microscopy of normal human nasal cilia and at nexin link deficiency

BACKGROUND

Eleven years ago we had described three patients with missing nexin links as a possible cause of primary ciliary dyskinesia (PCD). The assumption was substantiated last year by finding a mutation in these patients.

MATERIALS AND METHODS

We counted the nexin links, inner (IDA) and outer (ODA) dynein arms and microtubuli in each of, if possible, 50 cilia in 41 patients with normal cilia, 4 patients with deficiency of nexin links only and 4 with deficiency of nexin links and IDA.

RESULTS

In the control group the median number of nexin links was 4.5 per cilium, range 3.4-5.3. In the second group the mean numbers of nexin links per cilium were 1.1-1.4, in the third group 0.8-1.2, per patient. The median number of IDA was in the control group 4.2, range 3.3-5.2. In groups 2 and 3 the numbers were 3.0-3.5 and 0.2-1.0, respectively. Numbers of ODA were normal in all groups.

CONCLUSIONS

It is possible to reliable count the number of nexin links in nasal human cilia and to distinguish cases with missing nexin links from normal controls.

Exome sequencing identifies mutations in CCDC114 as a cause of primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous, autosomal-recessive disorder, characterized by oto-sino-pulmonary disease and situs abnormalities. PCD-causing mutations have been identified in 14 genes, but they collectively account for only ~60% of all PCD. To identify mutations that cause PCD, we performed exome sequencing on six unrelated probands with ciliary outer dynein arm (ODA) defects. Mutations in CCDC114, an ortholog of the Chlamydomonas reinhardtii motility gene DCC2, were identified in a family with two affected siblings. Sanger sequencing of 67 additional individuals with PCD with ODA defects from 58 families revealed CCDC114 mutations in 4 individuals in 3 families. All 6 individuals with CCDC114 mutations had characteristic oto-sino-pulmonary disease, but none had situs abnormalities. In the remaining 5 individuals with PCD who underwent exome sequencing, we identified mutations in two genes (DNAI2, DNAH5) known to cause PCD, including an Ashkenazi Jewish founder mutation in DNAI2. These results revealed that mutations in CCDC114 are a cause of ciliary dysmotility and PCD and further demonstrate the utility of exome sequencing to identify genetic causes in heterogeneous recessive disorders.

Kartagener's syndrome--anaesthetic considerations for ENT surgery

Kartagener's syndrome is a rare autosomal recessive disorder presenting a triad of sinusitis, bronchicetasis and situs inversus with dextrocardia. It occurs in 50% of patients with situs inversus. The most important anesthetic implications of Kartegener's syndrome surgery are assessement of pulmonary and cardiac structure and function. We present a case of 43-year-old woman with chronic rhinosinusitis with polyps and bilateral sectetory otitis media. The chest radiograph and CT scans showed dextrocardia and situs inversus with chronic bronchitis without bronchiectasis. Spirometry showed forced expiratory volume in one second (FEV1) of 2.66 L and forced vital capacity (FVC) of 3.62 L. Electroechography showed no cardiac abnormalities with 55-60% of EF. The anesthetic implications of Kartagener's syndrome are varied. The regional or general anesthesia might be involved with sinus surgery, ear surgery, pulmonary surgery, infertility or abdominal and cardiac surgery. The main anesthetic considerations among patients with Kartagener's syndrome are related to the pulmonary function which include preoperative respiratory infections due to bronchiectasis. We should also monitor potentially occluded congenital heart diseases. Kartagener's syndrome is a rare disease and when the patient need an operation we have to consider surgery with regional or general anesthesia. The general anesthesia would be safe after complete preanaesthetic examination of the patient. The ECG, chest CT scans, spirometry and echocardiography are mandatory before the operation.

Lower airway nitric oxide is increased in children with sickle cell disease

OBJECTIVES

To determine alveolar and airways nitric oxide (NO) levels in children with sickle cell disease (SCD).

STUDY DESIGN

Multiple flows fractional exhaled NO (FE(NO)), bronchial NO flux (J'aw(NO)), and alveolar NO concentration (Ca(NO)) were determined prospectively in 16 non-atopic children with SCD in a tertiary ambulatory clinic and compared with those in 10 children with primary ciliary dyskinesia and 22 healthy control subjects. Differences in FE(NO), J'aw(NO), and Ca(NO) were compared with mixed model analysis and Mann-Whitney tests.

RESULTS

Children with SCD had reference range FE(NO) at 50 mL/sec, but FE(NO) was elevated across all flows compared with healthy control subjects (mean difference=2.10±0.91 parts per billion, P=.03). Subjects with SCD had increased J'aw(NO) (1177±533 picoliters per second versus 833±343 picolitres per second, P=.03), and Ca(NO) was no different from control subjects. In contrast, children with primary ciliary dyskinesia had decreased FE(NO) (mean difference=3.36±1.24 parts per billion, P<.01) and J'aw(NO) (507±259 picoliters per second versus 833±343 picoliters per second, P<.01).

CONCLUSIONS

Lower airways NO is increased in children with SCD. Elevation of J'aw(NO) may represent dysregulation of NO metabolism or subclinical airways inflammation.

Ultrastructural pathology of primary ciliary dyskinesia: report about 125 cases in Germany

Background

Primary ciliary dyskinesia (PCD) is a rare genetically induced disorder of cilia inducing mainly respiratory diseases. Transmission electron microscopy (TEM) analysis of ciliary ultrastructure is classically used for diagnosis. We report our experience of TEM investigations in a large series of patients.

Methods

TEM analysis performed of 742 biopsies from patients with suspected PCD was reviewed retrospectively. Ultrastructural defects were analysized further in 125 cases with changes typical for PCD.

Results

In 18.1% of patients diagnosis of PCD was made because of morphological alterations, in 68.2% secondary changes were seen. In 13.7% material was not feasible for analysis. Mostly defects of dynein arms were detected in PCD (96.8%). In particular defects of the inner arms (51.2%) and combined dynein defects (37.6%) were found. Total loss of dynein arms was dominant. Only in 3.2% deficiencies of central structures were found alone. Associated situs inversus or dextracardia was reported clinically in 21.4%.

Conclusions

TEM analysis is possible in most patients and a useful tool for diagnosis of PCD. Functional and genetic analysis should be done additionally. Registers should be installed to collect all available informations and push further research.

Development and validation of a method of cilia motility analysis for the early diagnosis of primary ciliary dyskinesia

BACKGROUND

Primary ciliary dyskinesia (PCD) is a clinically uniform entity, but cilia motility and structure can vary between patients, making the diagnostic difficult. The aim of this study was to evaluate the sensitivity and specificity in diagnosing PCD of a system of high-resolution digital high-speed video analysis with proprietary software that we developed for analysis of ciliary motility (Desinsoft-Bio 200). The secondary aim was to correlate nasal ciliary activity with clinical and structural abnormalities in PCD.

MATERIAL AND METHODS

We analysed nasal mucociliary transport, cilia ultrastructure, nasal ciliary beat frequency and beat pattern studied by high-resolution digital high-speed video in 25 cases of PCD (11 Kartagener syndrome), 27 secondary ciliary dyskinesia and 34 healthy volunteers.

RESULTS

Nasal mucociliary transport was defective in both primary and secondary ciliary dyskinesia. Ciliary immotility was observed only in 6 patients with Kartagener syndrome and correlated with the absence of dynein. We observed a correlation between partial dynein deficiencies and ciliary dyskinesia. Cilia activity and structure was normal in secondary ciliary dyskinesia.

CONCLUSION

Nasal mucociliary transport showed high sensitivity for PCD diagnosis with a low specificity. High-resolution digital high-speed video has a high sensitivity and specificity for diagnosing PCD. This system of video analysis is more useful than ultrastructural study and mucociliary transport for PCD screening. Dynein absence is correlated with cilia immotility and is more common in patients with Kartagener syndrome.

Primary ciliary dyskinesia: evaluation using cilia beat frequency assessment via spectral analysis of digital microscopy images

Ciliary beat frequency (CBF) measurements provide valuable information for diagnosing of primary ciliary dyskinesia (PCD). We developed a system for measuring CBF, used it in association with electron microscopy to diagnose PCD, and then analyzed characteristics of PCD patients. The CBF measurement system was based on power spectra measured through digital imaging. Twenty-four patients suspected of having PCD (age 1-19 yr) were selected from a group of 75 children and adolescents with pneumopathies of unknown causes. Ten healthy, nonsmoking volunteers (age ≥ 17 yr) served as a control group. Nasal brush samples were collected, and CBF and electron microscopy were performed. PCD was diagnosed in 12 patients: 5 had radial spoke defects, 3 showed absent central microtubule pairs with transposition, 2 had outer dynein arm defects, 1 had a shortened outer dynein arm, and 1 had a normal ultrastructure. Previous studies have reported that the most common cilia defects are in the dynein arm. As expected, the mean CBF was higher in the control group (P < 0.001) and patients with normal ultrastructure (P < 0.002), than in those diagnosed with cilia ultrastructural defects (i.e., PCD patients). An obstructive ventilatory pattern was observed in 70% of the PCD patients who underwent pulmonary function tests. All PCD patients presented bronchial wall thickening on chest computed tomography scans. The protocol and diagnostic techniques employed allowed us to diagnose PCD in 16% of patients in this study.

Oda16/Wdr69 is essential for axonemal dynein assembly and ciliary motility during zebrafish embryogenesis

In the alga Chlamydomonas reinhardtii, Oda16 functions during ciliary assembly as an adaptor for intraflagellar transport of outer arm dynein. Oda16 orthologs only occur in genomes of organisms that use motile cilia; however, such cilia play multiple roles during vertebrate development and the contribution of Oda16 to their assembly remains unexplored. We demonstrate that the zebrafish Oda16 ortholog (Wdr69) is expressed in organs with motile cilia and retains a role in dynein assembly. Antisense morpholino knockdown of Wdr69 disrupts ciliary motility and results in multiple phenotypes associated with vertebrate ciliopathies. Affected cilia included those in Kupffer's vesicle, where Wdr69 plays a role in generation of asymmetric fluid flow and establishment of organ laterality, and otic vesicles, where Wdr69 is needed to develop normal numbers of otoliths. Analysis of cilium ultrastructure revealed loss of outer dynein arms in morphant embryos. These results support a remarkable level of functional conservation for Oda16/Wdr69.

Cilia motility and structure in primary and secondary ciliary dyskinesia

BACKGROUND

Primary ciliary dyskinesia (PCD) is a clinically uniform entity, although cilia motility and structure can vary among patients, making diagnosis difficult. Chronic sinusitis, bronchiectasis, sinus hypoplasia, secretory otitis media, and low fertility are common in PCD patients. The aim of this work was to correlate nasal ciliary activity with clinical and structural abnormalities in PCD. A secondary aim was to evaluate the usefulness of high-resolution digital high-speed video (DHSV) in the diagnosis of PCD.

METHODS

We analyzed nasal mucociliary transport and cilia ultrastructure by electron microscopy and studied nasal ciliary beat frequency (CBF) and beat pattern using high-resolution DHSV imaging in 34 healthy volunteers, 25 individuals with PCD (including 11 with Kartagener's syndrome [KS]with situs inversus), and 27 with secondary ciliary dyskinesia (SCD).

RESULTS

Nasal mucociliary transport was defective in the PCD and SCD patients. Ciliary immotility was observed in only six KS patients and was correlated with the absence of dynein. We observed a correlation between partial dynein deficiency and an uncoordinated, stiffly vibrating ciliary beat. Cilia activity and structure were normal in the SCD patients.

CONCLUSION

Nasal mucociliary transport showed a sensitivity of 100% for the diagnosis of PCD but has low specificity. High-resolution DHSV imaging has high sensitivity and specificity for the diagnosis of PCD. Video analysis is probably more useful than the study of mucociliary transport and cilia ultrastructure in screening for PCD. The absence of dynein was correlated with ciliary immotility and was more common in KS patients.

ENT manifestations in patients with primary ciliary dyskinesia: prevalence and significance of otorhinolaryngologic co-morbidities

Primary ciliary dyskinesia (PCD) is a rare inherited disease with a prevalence of about 1:20,000. The underlying pathogenesis is disrupted ciliary function, which results in delayed mucus transportation leading to chronic inflammation, mainly in the upper and lower respiratory tract. Although the pathogenesis of the disease and its clinical presentation is somewhat understood, data regarding the prevalence of accompanying symptoms is limited, especially in the field of otorhinolaryngology. A total of 44 patients diagnosed with PCD answered a questionnaire regarding the diagnosis and clinical presentation of the disease, their medical history and clinical manifestations, and medical treatment in the field of otorhinolaryngology. The majority of participants (70%) had seen a physician more than 50 times before the diagnosis was made at an average age of 10.9 ± 14.4 years. As much as 59% of all patients had recurring problems at the paranasal sinuses and 69% of these patients needed corresponding surgical intervention. Even more patients (81%) suffered from recurring otitis media and, as a result, 78% of these patients underwent paracentesis with temporary tympanostomy tubes at least once at an average age of 9.5 ± 13.0 years. Otorhinolaryngologic symptoms, especially chronic otitis media and chronic rhinosinusitis, are frequently associated with PCD. Surgical intervention to treat these symptoms is common. The awareness of this disease should be raised, especially among ENT physicians, and surgical intervention should be indicated carefully.

Total situs inversus: a rare anomaly presenting to a chiropractic teaching clinic

OBJECTIVE

The purpose of this article is to describe a patient with a previously undiagnosed rare anomaly, total situs inversus (TSI), and discuss the range of clinical presentations and complications associated with this and other situs anomalies. An emphasis is directed toward educating the clinician concerning the potential diagnostic challenges posed by patients with TSI and the need for patient education.

CLINICAL FEATURES

The patient was a 26-year-old white woman who presented to a chiropractic teaching clinic for a scoliosis evaluation and underwent full-spine radiography. The cardiac silhouette and gastric air bubble were evident on the right side.

INTERVENTION AND OUTCOME

Radiography including a 2-view chest and 1-view abdomen series was performed. Examination showed a complete mirror image presentation of the cardiothoracic and visceral organs. The patient was informed of her diagnosis and associated complications and counseled concerning how typical health complaints may present atypically in patients with situs anomalies. The patient has not experienced complications associated with the TSI.

CONCLUSION

Total situs inversus is a rare autosomal recessive anomaly. This article highlights the classification and nomenclature of situs anomalies and their clinical presentations and complications. In addition, the importance of thorough patient education and counseling in those with situs anomalies is emphasized.

Ultrastructural abnormalities of respiratory cilia: a 25-year experience

CONTEXT

Ciliary dyskinesia is a rare, but significant, cause of chronic respiratory infections, and transmission electron microscopy is a critical adjunct to making the diagnosis.

OBJECTIVE

To investigate a single institution's experience with patients demonstrating abnormal ciliary ultrastructure.

DESIGN

Retrospective clinicopathologic review of 278 bronchial or nasal turbinate brushings or biopsies from 1983 through 2007.

RESULTS

There were 12 women and 9 men (mean age, 19.6 years; range, 1-54 years) with abnormal ciliary ultrastructure. Clinical history was unavailable in 3 patients, 15 (83%) of 18 patients presented with chronic or recurrent upper respiratory infections, and 3 (17%) presented with infertility. Seven (39%) of 18 patients had findings of Kartagener syndrome with situs inversus, dextrocardia, and bronchiectasis. Truncation or absence of inner or outer dynein arms occurred in 15 (71%) of 21 cases, and 5 (24%) revealed transposition defects with displacement of the central microtubules and peripheral doublets in 9 + 0 and 8 + 1 patterns. Radial spoke defects with microtubular disarray occurred in 4 (19%) of 21 cases. Compound cilia with multiple axonemes within a single outer sheath and supernumerary microtubules each occurred in 2 (10%) of the cases. Random ciliary orientation was also found in 2 (10%) of the cases, and dense granular basal body inclusions occurred in 1 case (5%). Multiple abnormalities occurred in 6 (29%) of the 21 cases.

CONCLUSIONS

Most patients presented with chronic respiratory tract infections or infertility. Dynein arm defects, transposition defects, and radial spoke defects were the most commonly encountered abnormal findings. Less-frequent abnormal findings included compound cilia, supernumerary microtubules, and dense granular basal body inclusions.

Mutations in Hydin impair ciliary motility in mice

Chlamydomonas reinhardtii hydin is a central pair protein required for flagellar motility, and mice with Hydin defects develop lethal hydrocephalus. To determine if defects in Hydin cause hydrocephalus through a mechanism involving cilia, we compared the morphology, ultrastructure, and activity of cilia in wild-type and hydin mutant mice strains. The length and density of cilia in the brains of mutant animals is normal. The ciliary axoneme is normal with respect to the 9 + 2 microtubules, dynein arms, and radial spokes but one of the two central microtubules lacks a specific projection. The hydin mutant cilia are unable to bend normally, ciliary beat frequency is reduced, and the cilia tend to stall. As a result, these cilia are incapable of generating fluid flow. Similar defects are observed for cilia in trachea. We conclude that hydrocephalus in hydin mutants is caused by a central pair defect impairing ciliary motility and fluid transport in the brain.

The primary cilium at the crossroads of mammalian hedgehog signaling

Cilia function as critical sensors of extracellular information, and ciliary dysfunction underlies diverse human disorders including situs inversus, polycystic kidney disease, retinal degeneration, and Bardet-Biedl syndrome. Importantly, mammalian primary cilia have recently been shown to mediate transduction of Hedgehog (Hh) signals, which are involved in a variety of developmental processes. Mutations in several ciliary components disrupt the patterning of the neural tube and limb bud, tissues that rely on precisely coordinated gradients of Hh signal transduction. Numerous components of the Hh pathway, including Patched, Smoothened, and the Gli transcription factors, are present within primary cilia, indicating that key steps of Hh signaling may occur within the cilium. Because dysregulated Hh signaling promotes the development of a variety of human tumors, cilia may also have roles in cancer. Together, these findings have shed light on one mechanism by which primary cilia transduce signals critical for both development and disease.

Genetic causes of bronchiectasis: primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous disorder reflecting abnormalities in the structure and function of motile cilia and flagella, causing impairment of mucociliary clearance, left-right body asymmetry, and sperm motility. Clinical manifestations include respiratory distress in term neonates, recurrent otosinopulmonary infections, bronchiectasis, situs inversus and/or heterotaxy, and male infertility. Genetic discoveries are emerging from family-based linkage studies and from testing candidate genes. Mutations in 2 genes, DNAI1 and DNAH5, frequently cause PCD as an autosomal recessive disorder. A clinical genetic test has been recently established for DNAI1 and DNAH5, which involves sequencing 9 exons that harbor the most common mutations. This approach will identify at least one mutation in these 2 genes in approximately 25% of PCD patients. If biallelic mutations are identified, the test is diagnostic. If only one mutation is identified, the full gene may be sequenced to search for a trans-allelic mutation. As more disease-causing gene mutations are identified, broader genetic screening panels will further identify patients with PCD. Ongoing investigations are beginning to identify genetic mutations in novel clinical phenotypes for PCD, such as congenital heart disease and male infertility, and new associations are being established between 'ciliary' genetic mutations and clinical phenotypes.

Oralfacialdigital-like syndrome with respiratory tract symptoms from birth and ultrastructural centriole/basal body disarray

A girl with polydactyly has had respiratory tract problems, including atelectasis, since birth. She has a high arched palate, a tongue hamartoma and dysmorphic face. Electron microscopy of nasal and bronchial brush biopsies repeatedly revealed centriole/basal body disarray and extreme sparseness of cilia. At the age of 2 years and 11 months, she displayed retardation of both motor and mental skills.

CONCLUSION

The manifestations tally with a ciliopathy, partly with the Bardet--Biedl syndrome (BBS) but especially with the oralfacialdigital syndrome (OFDS); however, with the addition of persistent respiratory tract problems. As these two syndromes are considered to be due to mutations affecting the centriole/basal body apparatus, the ultrastructural demonstration of disarray of these structures, never before demonstrated in such a patient, is of fundamental interest.

Pathogenesis of Bronchiectasis

Cystic fibrosis (CF) typically follows a more severe clinical course than non-CF bronchiectasis. Despite this recognized difference, the underpinnings of respiratory biology support a common pathogeneses of the anatomic deformations of bronchiectasis. This article reviews the observed manifestations among the related diseases of bronchiectasis and CF and discusses some of their similarities and differences. As more details of the mechanisms of bronchiectasis are unveiled, more parallels among the seemingly disparate causes of CF and non-CF bronchiectasis are recognized. With these insights, more opportunities to halt the vicious circle have become apparent.

Genetic defects in ciliary structure and function

Cilia, hair-like structures extending from the cell membrane, perform diverse biological functions. Primary (genetic) defects in the structure and function of sensory and motile cilia result in multiple ciliopathies. The most prominent genetic abnormality involving motile cilia (and the respiratory tract) is primary ciliary dyskinesia (PCD). PCD is a rare, usually autosomal recessive, genetically heterogeneous disorder characterized by sino-pulmonary disease, laterality defects, and male infertility. Ciliary ultrastructural defects are identified in approximately 90% of PCD patients and involve the outer dynein arms, inner dynein arms, or both. Diagnosing PCD is challenging and requires a compatible clinical phenotype together with tests such as ciliary ultrastructural analysis, immunofluorescent staining, ciliary beat assessment, and/or nasal nitric oxide measurements. Recent mutational analysis demonstrated that 38% of PCD patients carry mutations of the dynein genes DNAI1 and DNAH5. Increased understanding of the pathogenesis will aid in better diagnosis and treatment of PCD.

Molecular approaches to brain asymmetry and handedness

In the human brain, distinct functions tend to be localized in the left or right hemispheres, with language ability usually localized predominantly in the left and spatial recognition in the right. Furthermore, humans are perhaps the only mammals who have preferential handedness, with more than 90% of the population more skillful at using the right hand, which is controlled by the left hemisphere. How is a distinct function consistently localized in one side of the human brain? Because of the convergence of molecular and neurological analysis, we are beginning to consider the puzzle of brain asymmetry and handedness at a molecular level.

Role of the upper airways in patients with chronic cough

PURPOSE OF THE REVIEW

Chronic cough can be caused by a number of factors, including infections, rhinosinusitis, asthma and environmental stimuli. This paper reviews recent findings and opinions regarding the role played by the upper airways in chronic cough.

RECENT FINDINGS

Chronic cough has a significant impact on quality of life, which is more pronounced in women. In Western countries, the reported occurrence of rhinosinusitis in patient groups with chronic cough ranges from 8% to 81%. Allergic rhinitis is a risk factor for later development of asthma. In children, bronchiectasis is combined with upper airway abnormalities in the majority of cases. Increased expression of the capsaicin receptor subtype named 'transient receptor potential vanilloid-1', which correlates with capsaicin cough response, has been identified in patients with chronic cough. Patients with airway chemical sensitivity and chronic cough as one symptom have augmented capsaicin cough sensitivity that is related to changed levels of nerve growth factor in nasal lavage.

SUMMARY

Involvement of the upper airways in chronic cough has been confirmed in several studies. However, there are considerable differences between different health centres in the occurrence of rhinosinusitis as a cause of chronic cough. In patients with chronic cough of various causes, a neurochemical alteration in both the upper and the lower airways appears to have taken place, followed by increased cough sensitivity.

Knockout mouse models of sperm flagellum anomalies

To date, 21 knockout mouse models are known to bear specific anomalies of the sperm flagellum structures leading to motility disorders. In addition, genes responsible for flagellar defects of two well-known spontaneous mutant mice have recently been identified. These models reveal genetic factors, which are required for the proper assembly of the axoneme, the annulus, the mitochondrial sheath and the fibrous sheath. Many of these genetic factors follow unexpected cellular pathways to act on sperm flagellum morphogenesis. These mouse models may bear anomalies which are restricted to the spermatozoa or display more complex phenotypes that often include neuropathies and/or cilia-related diseases. In human, several structural disorders of the sperm flagellum found in brothers or consanguineous men probably have a genetic origin, but the genes involved have not yet been identified. The mutant mice we present in this review are invaluable models, which can be used to identify potential candidate genes for infertile men with specific sperm flagellum anomalies.

Transmission electron microscopy in the diagnosis of primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is an autosomal recessive disease with extensive genetic heterogeneity. Dyskinetic or completely absent motility of cilia predisposes to recurrent pulmonary and upper respiratory tract infections resulting in bronchiectasis. Also infections of the middle ear are common due to lack of ciliary movement in the Eustachian tube. Men have reduced fertility due to spermatozoa with absent motility or abnormalities in the ductuli efferentes. Female subfertility and tendency to ectopic pregnancy has also been suggested. Headache, a common complaint in PCD patients, has been associated with absence of cilia in the brain ventricles, leading to decreased circulation of the cerebrospinal fluid. Finally, half of the patients with PCD has situs inversus, probably due to the absence of ciliary motility in Hensen's node in the embryo, which is responsible for the unidirectional flow of fluid on the back of the embryo, which determines sidedness. PCD, which is an inborn disease, should be distinguished from secondary ciliary dyskinesia (SCD) which is an acquired disease. Transmission electron microscopy is the most commonly used method for diagnosis of PCD, even though alternative methods, such as determination of ciliary motility and measurement of exhaled nitric oxide (NO) may be considered. The best method to distinguish PCD from SCD is the determination of the number of inner and outer dynein arms, which can be carried out reliably on a limited number of ciliary cross-sections. There is also a significant difference in the ciliary orientation (determined by the direction of a line drawn through the central microtubule pair) between PCD and SCD, but there is some overlap in the values, making this parameter less suitable to distinguish PCD from SCD.