The saccharin method for testing mucociliary function in patients suspected of having primary ciliary dyskinesia

In order to evaluate the clinical value of the saccharin test as a practical and simple measure of mucociliary clearance, nasal mucociliary clearance (NMCC) and ciliary ultrastructure were studied in 22 patients suspected of having primary ciliary dyskinesia (PCD) based on the saccharin test. Ten patients fulfilling the diagnostic criteria of PCD had a pathological response to the saccharin test (transport time greater than 60 minutes), and this was consistently associated with ultrastructural defects, specific for PCD. These results validate the suitability of the clinical use of the saccharin test as a screening procedure for NMCC. The false-negative results obtained in three cases of PCD, all with borderline values, cannot be ascribed to ineffectiveness of the test, but rather to the persistence of some motility by certain defective cilia, detectable by microphoto-oscillographic investigation of specimens obtained by nasal biopsy or brushing.     

Diagnostik der primären ziliären Dyskinesie

Primary ciliary dyskinesia (PCD) is a phenotypically and genetically heterogeneous genetic disorder. The respiratory disease phenotype which is characterized by upper and lower airway infections results from inborn defects of respiratory cilia responsible for defective mucociliary clearance. Randomization of left/right body asymmetry is responsible for situs inversus (Kartagener’s syndrome) in half of affected individuals. As a screening test nasal nitric oxide measurement can be used. Establishment of the diagnosis currently relies on electron microscopy, high-resolution immunofluorescence analysis, and/or direct evaluation of ciliary beat by light microscopy. Recently mutations in the four genes DNAI1, DNAH5, TXNDC3, and DNAH11 that all encode for outer dynein arm proteins have been linked to recessive PCD. For diagnostic testing especially DNAH5 and DNAI1 mutation screening is useful, because they are responsible for more than 50% of PCD cases with outer dynein arm defects. Rarely mutations in RPGR (PCD + retinitis pigmentosa) and OFD1 (PCD + complex mental retardation syndrome) have been identified in X-linked recessive PCD variants.     

Dyskinésie ciliaire primitive

Primary ciliary dyskinesia (PCD, MIM 242650) is an inherited respiratory disease caused by functional and ultrastructural abnormalities of respiratory cilia. This disorder, which affects 1 in 16,000 individuals, is usually transmitted as an autosomal recessive trait. In half the cases, PCD is associated with situs inversus (Kartagener syndrome). PCD is characterized by impaired mucociliary clearance resulting from a lack of ciliary motion, which is responsible for recurrent respiratory infections. The most frequent and first identified ciliary defect involves the dynein arms. The genetic heterogeneity underlying PCD is extremely important, and only three genes have as yet been identified in a few PCD patients with absence of outer dynein arms. The main clinical symptoms, at pulmonary and ENT levels, the abnormalities of ciliary structure and function, and the molecular basis of PCD will be reported in this review.     

Primary ciliary dyskinesia and nasal mucociliary clearance

In this study, nasal mucociliary clearance is investigated in patients with primary ciliary dyskinesia, patients with other respiratory tract infections and healthy persons. Mucociliary clearance is established with a drop of albumen labelled with 99m-Tc. From this study it appears that measurement of mucociliary clearance in the nose can serve as a reliable screening method. If a patient with respiratory tract infections shows a normal mucociliary clearance rate there is no primary ciliary dyskinesia, and a biopsy of ciliated epithelium is not necessary. If, after repeated examinations, a normal clearance rate cannot be demonstrated, a biopsy of ciliated epithelium should be taken for studying ciliary activity and ciliary ultrastructure.     

Update of respiratory tract disease in children with primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a rare genetic disease characterized by abnormal ciliary structure and function leading to impaired mucociliary clearance and chronic progressive sinopulmonary disease. Upper and lower respiratory tract manifestations are cardinal features of PCD. This review summarizes the current state of knowledge of respiratory tract disease in individuals with PCD and highlights the challenges in identifying and quantifying lung disease in very young children with PCD. No specific therapies are available to correct ciliary dysfunction in PCD. Treatment is not evidence based, and recommendations are largely extrapolated from cystic fibrosis and other conditions with impaired mucociliary clearance. There is a pressing need to develop and validate outcome measures, including patient-reported outcomes, that could be used to evaluate potential therapies in PCD. This review concludes with recommendations for clinical endpoints and outcome measures and a prioritized list of treatments to study in PCD clinical trials.     

Nasal nitric oxide measurements for the screening of primary ciliary dyskinesia.

Primary ciliary dyskinesia (PCD) presents to general practitioners with symptoms pertinent to a variety of specialists because of the involvement of ciliated epithelium in the upper/lower respiratory tract, ears, eyes and genital tract. There is no easy, reliable screening test for PCD, and thus, the majority of patients remain undiagnosed. Nitric oxide (NO) is measurable in nasal air of normal subjects and found to be low in cystic fibrosis (CF) and very low in PCD. Recently, it was suggested to play an important role in regulating ciliary motility. The aim of this study was to evaluate whether measurements of nasal NO could be used to screen for PCD. Nasal NO was measured from the nasal cavity by a chemiluminescence analyser in subjects with PCD, healthy controls, CF, idiopathic bronchiectasis, Young's syndrome and lone sinusitis. Nasal NO was significantly lower in PCD (64.0+/-36.6) compared with normal controls (759+/-145.8), idiopathic bronchiectasis (734+/-163.7), CF (447.5+/-162.6), lone sinusitis (1487+/-734) and Young's syndrome (644+/-129.9). Nasal NO was also significantly lower in PCD than CF patients. Measurement of nasal nitric oxide may therefore be used clinically in various specialities to screen suspected patients for primary ciliary dyskinesia.     

Nasal ciliary ultrastructure and function in patients with primary ciliary dyskinesia compared with that in normal subjects and in subjects with various respiratory diseases

In an attempt to establish the relevance of ciliary ultrastructure to the pathophysiologic aspects of respiratory tract disease, we compared quantitatively the ultrastructure and function of cilia from healthy subjects (atopic and nonatopic nonsmokers, asymptomatic smokers) and patients with a variety of respiratory diseases (cystic fibrosis, chronic rhinitis, bronchiectasis associated with hypogammaglobulinemia, chronic bronchitis) with cilia from patients with primary ciliary dyskinesia (PCD). In healthy subjects and patients with non-PCD respiratory disease, approximately 5% of the cilia evaluated had ultrastructural abnormalities. Ciliary beat frequency was significantly higher in the chronic rhinitis group (15.3 +/- 1.2 Hz) than in the other non-PCD groups, which were within the normal range (12.5 +/- 1.7 Hz), and in all non-PCD cases ciliary wave form was normal. In each of these groups, normal mucociliary transport had been previously demonstrated. By contrast, in patients with PCD, the proportion of cilia with ultrastructural abnormalities was significantly greater than in the normal subjects and those with non-PCD respiratory disease (p less than 0.0001). In addition, beat frequency was significantly reduced, ciliary wave form was grossly abnormal, and pulmonary and nasal mucociliary transport were virtually absent. These findings demonstrate the relevance of ciliary ultrastructural abnormalities to altered ciliary function and lend support to the primary role of the demonstrated abnormalities in the respiratory tract disease of PCD.     

Normal nasal mucociliary clearance in CF children: evidence against a CFTR-related defect.

Studies on mucociliary clearance (MCC) in cystic fibrosis (CF) have produced conflicting results. This study aimed to differentiate primary (ion transport-related) from secondary (inflammatory) causes of delayed MCC in CF. Nasal MCC was measured in 50 children (CF, primary ciliary dyskinesia (PCD) and no respiratory disease). Nasal lavage fluid was analysed for interleukin (IL)-8 and tumour necrosis factor-alpha. Similar measurements were obtained in adult CF patients with and without chronic sinusitis (CS). Children with CF had neither delayed MCC nor increased levels of cytokines. Conversely, children with PCD had prolonged MCC times (all >30 min) and significantly raised levels of IL-8. CS-positive CF adults had significantly slower MCC than CS-negative subjects, but IL-8 levels were low and similar in both groups. Decreased airway surface liquid and delayed mucociliary clearance are the postulated primary mechanisms in cystic fibrosis. However, the current study reports that cystic fibrosis children have normal nasal mucociliary clearance. Abnormalities appeared in cystic fibrosis adults with symptoms of chronic sinus disease, suggesting a secondary rather than primary phenomenon. Studies to explore this mechanism in the distal, more sparsely-ciliated airways could aid an understanding of pathogenesis and the development of new treatments.     

Primary ciliary dyskinesia and upper airway diseases

Primary ciliary dyskinesia (PCD) is a rare and difficultto-diagnose disease with morbidity related to infections of the upper and lower respiratory tract. The disease is caused by mutations in genes that are required for proper ciliary function. The defect in ciliary function results in reduced or absent mucociliary clearance, thereby predisposing the affected individual to repeated bacterial infections. Recent advances in the understanding of the basic biology and function of the cilium have led to the identification of some of the genes that are mutated in cases of PCD. Further studies of this disease will likely lead to earlier diagnosis, better treatment, and improved outcomes.     

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.     

Nasal and lower airway level of nitric oxide in children with primary ciliary dyskinesia.

Exhaled nitric oxide can be detected in exhaled air and is readily measured by chemiluminescence. It is thought to be involved in both the regulation of ciliary motility and host defence. Recently, upper airway NO has been found to be reduced in a small number of children with primary ciliary dyskinesia (PCD) and its measurement has been recommended as a diagnostic test for this condition. The aim of this study was to compare the levels of NO in the upper and lower airways in a larger number of children with proven PCD with those found in healthy children. Exhaled NO was measured in the upper airway by direct nasal sampling during a breath-hold and in the lower airway as the end-tidal plateau level, using a chemiluminescence NO analyser. Upper airway NO levels were significantly lower in PCD (n = 21) than in the healthy children (n = 60) (mean +/-SD, 97+/-193, 664+/-298 parts per billion (ppb), respectively, p<0.0001). In PCD, the lower airway NO levels were also reduced (2.17+/-1.18, 5.94+/-3.49 ppb, respectively, p<0.0001). The levels were not associated with steroid use and did not correlate with lung function. Although there was some overlap between normal children and those with primary ciliary dyskinesia with regard to lower airway NO, nasal NO discriminated between the two groups in all but one child in each group. Measurement of nasal NO therefore may be a useful screening test for primary ciliary dyskinesia.     

Nitric oxide in primary ciliary dyskinesia

Nitric oxide is continually synthesised in the respiratory epithelium and is upregulated in response to infection or inflammation. Primary ciliary dyskinesia (PCD) is characterised by recurrent sinopulmonary infections due to impaired mucociliary clearance. Despite chronic infections, nasal nitric oxide in such patients is markedly reduced and is used as a screening test for this condition. These low levels were first described >15 yrs ago but the underlying mechanisms have yet to be fully elucidated. We review epithelial nitric oxide synthesis, release and measurement in the upper airways with particular reference to PCD. The key hypotheses that have been proposed to explain the low nitric oxide levels in this condition are explored and the potential benefits of augmenting airway nitric oxide levels are considered. Further work in these patients clarifying both whether the respiratory epithelium is able to biosynthesise normal levels of nitric oxide and the role played by abnormalities in the anatomy of the paranasal sinuses is essential. While nitric oxide augmentation is unlikely to be beneficial in common PCD phenotypes, it has potential in the treatment of secondary dyskinesias and may also improve treatment of bacterial infections, particularly where biofilms are implicated.     

Primäre ziliare Dyskinesie

Primary ciliary dyskinesia (PCD) is an autosomal recessive disease characterized by abnormal ciliary motion and impaired mucociliary clearance. The prevalence of PCD is approximately 1:20,000 live births. Since cilia are common in many organs of the body, there is a wide variety of clinical manifestations in patients with PCD. Due to an extensive genetic heterogeneity the course of the disease varies largely, but with increasing age, the clinical symptoms are dominated by repeated respiratory infections and ultimately respiratory insufficiency. In the presence of situs inversus, which is observed in 50% of affected individuals, the diagnosis is easy, In cases of doubt, analyses of the kinetics and infrastructure of the cilia are necessary. The treatment of PCD is symptomatic. With optimal medical and physiotherapeutic management, the prognosis quoad vitam is good and life expectancy is nearly normal.     

Mucus properties in children with primary ciliary dyskinesia: comparison with cystic fibrosis

OBJECTIVE: It has been assumed that cystic fibrosis (CF) lung disease is due in part to abnormal airway mucus. Primary ciliary dyskinesia (PCD) is a form of bronchiectasis that is similar to CF in many ways but is caused by congenital defects in mucociliary clearance. Our objective was to compare the biophysical and transport properties of CF and PCD sputa in subjects matched for age and degree of lung function impairment. DESIGN, SETTING, PARTICIPANTS: PCD patients (n = 19; mean age, 9.5 +/- 3.0 years [+/- SD]; FEV1, 65.0 +/- 7.8 L) were recruited from the clinic at the Royal Brompton Hospital. Patients with CF (n = 30, mean age, 10.8 +/- 2.6 years; FEV1, 61.8 +/- 22.8 L) were identified from the Wake Forest University School of Medicine CF Center. Pulmonary function testing and sputum collection were performed as part of routine, scheduled clinic visits. MEASUREMENTS: Pulmonary function was measured by spirometry, and sputum was collected during the pulmonary function test maneuver. Some patients were longitudinally assessed at visits during the course of 3 years. Sputum properties measured were dynamic viscoelasticity, wettability, cohesivity, interfacial (surface) tension, solids composition, DNA and interleukin (IL)-8 concentration, in vitro mucociliary transportability, and cough transportability. RESULTS: Inflammation as measured by IL-8 concentration was three times greater in the PCD sputa (p < 0.0001). There were no significant differences in the sputum biophysical or transport properties comparing CF with PCD sputum. CONCLUSIONS: It is unlikely that established CF lung disease is principally due to abnormal sputum properties, and it is more likely that the biophysical and transport properties reflect disease severity regardless of whether bronchiectasis is due to CF or PCD.     

Primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is an inherited disorder characterized by impaired ciliary function that leads to an array of clinical manifestations including chronic bronchitis, chronic sinusitis, chronic otitis media, situs inversus (in approximately 50% of cases), and infertility. The underlying genetic and molecular defects have not been defined. Molecular genetic studies have demonstrated multiple gene loci. In a few families, defects in genes encoding ciliary dynein proteins have been identified. PCD is an interesting disease to compare with cystic fibrosis (CF) because both are airway diseases associated with impaired mucociliary clearance and with chronic infection of the airways leading to bronchiectasis as well as chronic infection of the sinuses that may be associated with nasal polyposis. The progression of the lower airway disease appears less rapid in PCD. Unlike CF, PCD is commonly associated with chronic otitis media, respiratory problems during the neonatal period, and situs inversus, suggesting that ciliary function is also important for clearing fluid/bacteria from the middle ear, for clearing fluid from the fetal lung during the transition to an air-filled neonatal lung, and for directing laterality of organs during embryonic development. The management for PCD lung disease is similar to that for CF and other diseases with chronic bronchitis leading to bronchiectasis.     

Effect of aerosolized uridine-5'-triphosphate on airway clearance with cough in patients with primary ciliary dyskinesia.

Primary ciliary dyskinesia (PCD) is a genetic disease characterized by abnormal ciliary structure and function and impaired mucociliary clearance. Because patients with PCD use cough clearance as an airway defense mechanism, we tested the hypothesis that aerosolized uridine-5'-triphosphate (UTP) would improve clearance during cough by its actions to stimulate Cl- secretion and mucin release by goblet cells. We measured clearance during cough in 12 patients with PCD (ages 14 to 71 yr, FEV1 43% to 89% predicted) in a double blind, randomized, crossover study after aerosolization of a single dose of UTP (5 mg/ml, 3.5 ml) or vehicle (0.12% saline, 3.5 ml). Clearance during cough (whole lung) was quantified during and after a series of controlled coughs by measuring the clearance of [99mTc]Fe2O3 particles via gamma camera scanning over 120 min. Safety parameters were recorded during and after drug delivery. Aerosolized UTP improved whole-lung clearance during cough as compared with vehicle (from 0 to 60 min: 0.40 +/- 0.07%/min [UTP] versus 0.26 +/- 0. 04%/min [vehicle] [mean +/- SEM], p = 0.01), and from 0 to 120 min: 0.38 +/- 0.05%/min [UTP] versus 0.25 +/- 0.04%/ min [vehicle], p = 0. 02). Aerosolized UTP is safe, with no serious adverse effects. Whole-lung clearance during cough in patients with defective ciliary function is enhanced after inhalation of UTP.     

The challenges of diagnosing primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a rare genetic disorder of ciliary structure and function. The diagnosis can be challenging, particularly when using nongenetic assays. The "gold standard" diagnostic test is ultrastructural analysis of respiratory cilia obtained by nasal scrape or brush biopsy. A few specialized centers use high-speed videomicroscopy to examine ciliary beat. Certain beat patterns correlate with ultrastructural defects, and, in some cases, subtle alterations in beat pattern can be seen when ultrastructure is normal. Recent studies have shown that nasal nitric oxide (NO) is very low in patients with PCD compared with healthy control subjects; therefore, this assay may be a useful screening or adjunctive test for PCD. Because acute respiratory illnesses may yield alterations in ciliary ultrastructure, ciliary beat, and nasal NO values, these tests should be performed during a stable baseline period. Identification of an array of PCD genes has provided the opportunity for making a definitive genetic diagnosis for PCD in some cases. All of these approaches have a role in diagnosing PCD. For example, PCD has been confirmed by identifying disease-causing mutations in a heavy dynein chain gene in individuals with normal ciliary ultrastructure but subtle defects in ciliary beat and low nasal NO. Priorities to improve nongenetic diagnostic capability include standardization of nasal NO as a screening test and the development of specialized centers using uniform approaches for the analysis of ciliary ultrastructure and ciliary beat pattern. Another chapter in this issue (see Zariwala and colleagues, pp. 430) addresses the progress toward improved capabilities for definitive genetic testing.     

Nasal nitric oxide in atypical primary ciliary dyskinesia

BACKGROUND: Atypical cases of primary ciliary dyskinesia (PCD) may present with minimal transmission electron microscopy (TEM) defects. The diagnostic role of nasal nitric oxide (nNO) levels was evaluated in those patients. METHODS: Sixty-four children with recurrent pneumonia were studied with ciliary motion analysis, TEM, and nNO. RESULTS: Investigations indicated PCD in 12 patients, secondary ciliary dyskinesia (SCD) in 50 patients, and normal results in 2 patients. In 4 of 50 children with SCD, atypical PCD was considered possible. The mean (+/- SD) nNO was 130 +/- 46.95 parts per billion in children affected by PCD, 127.79 +/- 68.58 parts per billion in atypical patients, and 760 +/- 221 parts per billion in children with SCD. Three to 5 months later, the nNO level was 132.75 +/- 55.76 parts per billion in children with atypical disease and 778.00 +/- 197 parts per billion in children with SCD. CONCLUSION: Low levels of nNO may help to identify patients with atypical PCD.     

Effect of L-arginine infusion on airway NO in cystic fibrosis and primary ciliary dyskinesia syndrome.

Airway nitric oxide concentrations in patients with cystic fibrosis or primary ciliary dyskinesia syndrome have been shown to be lower than in healthy subjects. Decreased NO concentrations may contribute to impaired ciliary clearance, respiratory tract infections, or obstructive lung disease in these conditions. Nasal and exhaled NO concentrations were compared before and after infusion of 500 mg x kg(-1) L-arginine, the substrate of NO synthases, in 11 cystic fibrosis (CF) patients, seven primary ciliary dyskinesia (PCD) syndrome patients, and 11 control subjects. Baseline nasal and exhaled NO concentrations were significantly lower in both CF and PCD syndrome patients than in controls (p<0.01). In controls, the maximum increase of NO was seen immediately after L-arginine infusion in the upper airways (1.8-fold) and 3 h after the infusion in the lower airways (1.4-fold). Although NO concentrations also increased significantly in both CF (1.9-fold and 1.6-fold, respectively) and PCD syndrome patients (1.4-fold and 1.8-fold, respectively), concentrations remained subnormal compared with baseline values of controls. Pulmonary function remained unchanged in both patient groups. In conclusion, the low airway nitric oxide formation in both cystic fibrosis and primary ciliary dyskinesia syndrome patients can be augmented by L-arginine administration. The finding that pulmonary function remained unchanged in both conditions may be due to the fact that normalization of airway nitric oxide concentrations could not be achieved.     

Primäre ziliäre Dyskinesie

Primary ciliary dyskinesia (PCD) is a rare autosomal recessive disorder with defective structure or function of normally motile cilia, leading to chronic upper and lower respiratory tract infections, fertility problems and organ site abnormalities. The PCD is a genetically heterogeneous condition entailing a broad range of different disease variants. Diagnosing these different PCD phenotypes requires a combined approach using complementary methods for detection of defects of ciliary function, ultrastructure and composition as well as low nasal nitric oxide values and biallelic genetic mutations. To date, mutations in 31 different genes have been linked to PCD permitting a genetic diagnosis in approximately 60?% of cases. Due to the lack of adequate trials evidence-based knowledge on the epidemiology, disease course and management of PCD is currently lacking. An international PCD registry has been developed to overcome these limitations (www.pcdregistry.eu) and is currently recruiting patients. Current treatment regimens have to rely on expert opinions and on experience gained from other respiratory diseases. The management of PCD includes surveillance of pulmonary function, culturing upper and lower airway secretions and diagnostic imaging. Daily airway clearance techniques as well as prompt antibiotic treatment of infections are the cornerstones of PCD treatment regimens.