Ciliary disorientation alone as a cause of primary ciliary dyskinesia syndrome

Ciliary Videomicroscopy: A Long Beat from the European Respiratory Society Guidelines to the Recognition as a Confirmatory Test for Primary Ciliary Dyskinesia

Primary ciliary dyskinesia (PCD) is a rare inherited ciliopathy in which respiratory cilia are stationary or dyskinetic. The clinical presentation of PCD is highly non-specific since it includes infections and disorders of the upper (otitis and rhinosinusitis) and lower (neonatal respiratory distress, bronchitis, pneumonia and bronchiectasis) airways, starting in early life. Clinical examination alone does not allow a PCD diagnosis, which relies on several concordant tests, since none are sensitive or specific enough alone. Despite being the most sensitive and specific test to diagnose PCD, digital high-speed videomicroscopy (DHSV) is not sufficiently standardized, preventing its use with complete confidence as a confirmatory diagnostic test for PCD, or its inclusion in a diagnostic algorithm. Since the 2017 ERS recommendations for PCD diagnosis, three main issues remain to be solved in order to optimize DHSV ciliary beating evaluation: the problem in defining an accurate sensitivity and specificity as there is no gold standard method to diagnose all PCD cases, a lack of standardization in the operating procedure for processing respiratory samples, and in the choice of measured parameters (self-operating or not). The development of new automated analysis approaches is promising and will require full clinical validation.

Multicellular modeling of ciliopathy by combining iPS cells and microfluidic airway-on-a-chip technology

Mucociliary clearance is an essential lung function that facilitates the removal of inhaled pathogens and foreign matter unidirectionally from the airway tract and is innately achieved by coordinated ciliary beating of multiciliated cells. Should ciliary function become disturbed, mucus can accumulate in the airway causing subsequent obstruction and potentially recurrent pneumonia. However, it has been difficult to recapitulate unidirectional mucociliary flow using human-derived induced pluripotent stem cells (iPSCs) in vitro and the mechanism governing the flow has not yet been elucidated, hampering the proper humanized airway disease modeling. Here, we combine human iPSCs and airway-on-a-chip technology, to demonstrate the effectiveness of fluid shear stress (FSS) for regulating the global axis of multicellular planar cell polarity (PCP), as well as inducing ciliogenesis, thereby contributing to quantifiable unidirectional mucociliary flow. Furthermore, we applied the findings to disease modeling of primary ciliary dyskinesia (PCD), a genetic disease characterized by impaired mucociliary clearance. The application of an airway cell sheet derived from patient-derived iPSCs and their gene-edited counterparts, as well as genetic knockout iPSCs of PCD causative genes, made it possible to recapitulate the abnormal ciliary functions in organized PCP using the airway-on-a-chip. These findings suggest that the disease model of PCD developed here is a potential platform for making diagnoses and identifying therapeutic targets and that airway reconstruction therapy using mechanical stress to regulate PCP might have therapeutic value.

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.

Multi-scale alignment of respiratory cilia and its relation to mucociliary function

The tracheobronchial tree is lined by a mucociliary epithelium containing millions of multiciliated cells. Their integrated oscillatory activity continuously propels an overlying pollution-protecting mucus layer in cranial direction, leading to mucociliary clearance - the primary defence mechanism of the airways. Mucociliary transport is commonly thought to co-emerge with the collective ciliary motion pattern under appropriate geometrical and rheological conditions. Proper ciliary alignment is therefore considered essential to establish mucociliary clearance in the respiratory system. Here, we used volume electron microscopy in combination with high-speed reflection contrast microscopy in order to examine ciliary orientation and its spatial organization, as well as to measure the propagation direction of metachronal waves and the direction of mucociliary transport on bovine tracheal epithelia with reference to the tracheal long axis (TLA). Ciliary orientation is measured in terms of the basal body orientation (BBO) and the axonemal orientation (AO), which are commonly considered to coincide, both equivalently indicating the effective stroke as well as the mucociliary transport direction. Our results, however, reveal that only the AO is in line with the mucociliary transport, which was found to run along a left-handed helical trajectory, whereas the BBO was found to be aligned with the TLA. Furthermore, we show that even if ciliary orientation remains consistent between adjacent cells, ciliary orientation exhibits a gradual shift within individual cells. Together with the symplectic beating geometry, this intracellular orientational pattern could provide for the propulsion of highly viscous mucus and likely constitutes a compromise between efficiency and robustness.

Multi-scale spatial heterogeneity enhances particle clearance in airway ciliary arrays

Mucus clearance constitutes the primary defence of the respiratory system against viruses, bacteria and environmental insults [1]. This transport across the entire airway emerges from the integrated activity of thousands of multiciliated cells, each containing hundreds of cilia, which together must coordinate their spatial arrangement, alignment and motility [2, 3]. The mechanisms of fluid transport have been studied extensively at the level of an individual cilium [4, 5], collectively moving metachronal waves [6-10], and more generally the hydrodynamics of active matter [11, 12]. However, the connection between local cilia architecture and the topology of the flows they generate remains largely unexplored. Here, we image the mouse airway from the sub-cellular (nm) to the organ scales (mm), characterising quantitatively its ciliary arrangement and the generated flows. Locally we measure heterogeneity in both cilia organisation and flow structure, but across the trachea fluid transport is coherent. To examine this result, a hydrodynamic model was developed for a systematic exploration of different tissue architectures. Surprisingly, we find that disorder enhances particle clearance, whether it originates from fluctuations, heterogeneity in multiciliated cell arrangement or ciliary misalignment. This resembles elements of 'stochastic resonance' [13-15], in the sense that noise can improve the function of the system. Taken together, our results shed light on how the microstructure of an active carpet [16, 17] determines its emergent dynamics. Furthermore, this work is also directly applicable to human airway pathologies [1], which are the third leading cause of deaths worldwide [18].

Cytoplasmic "ciliary inclusions" in isolation are not sufficient for the diagnosis of primary ciliary dyskinesia

BACKGROUND

The diagnosis of primary ciliary dyskinesia (PCD) is difficult and requires a combination of clinical features, nasal nitric oxide testing, cilia ultrastructural analysis by electron microscopy (EM), and genetics. A recently described cytoplasmic ultrastructural change termed "ciliary inclusions" was reported to be diagnostic of PCD; however, no supporting evidence of PCD was provided. In this study, we sought to confirm, or refute, the diagnosis of PCD in subjects with "ciliary inclusions" on EM.

METHODS

Six subjects from five families with previous lab reports of "ciliary inclusions" on EMs of ciliated cells were identified and evaluated at a Genetic Disorders of Mucociliary Clearance Consortium site. We performed a detailed clinical history, nasal nitric oxide measurement, genetic testing including whole-exome sequencing (WES), and when possible, repeat ciliary EM study.

RESULTS

Only one of six subjects had multiple and persistent clinical features congruent with PCD. No subject had situs inversus. Only one of six subjects had a very low nasal nitric oxide level. No "ciliary inclusions" were found in three subjects who had a repeat ciliary EM, and ciliary axonemal ultrastructures were normal. Genetic testing, including WES, was negative for PCD-causing genes, and for pathogenic variants in gene pathways that might cause "ciliary inclusions," such as ciliary biogenesis.

CONCLUSION

"Ciliary Inclusions", in isolation, are not sufficient to diagnosis PCD. If seen, additional studies should be done to pursue an accurate diagnosis.

Lack of GAS2L2 Causes PCD by Impairing Cilia Orientation and Mucociliary Clearance

Primary ciliary dyskinesia (PCD) is a genetic disorder in which impaired ciliary function leads to chronic airway disease. Exome sequencing of a PCD subject identified an apparent homozygous frameshift variant, c.887_890delTAAG (p.Val296Glyfs^∗13), in exon 5; this frameshift introduces a stop codon in amino acid 308 of the growth arrest-specific protein 2-like 2 (GAS2L2). Further genetic screening of unrelated PCD subjects identified a second proband with a compound heterozygous variant carrying the identical frameshift variant and a large deletion (c.867_^∗343+1207del; p.?) starting in exon 5. Both individuals had clinical features of PCD but normal ciliary axoneme structure. In this research, using human nasal cells, mouse models, and X.laevis embryos, we show that GAS2L2 is abundant at the apical surface of ciliated cells, where it localizes with basal bodies, basal feet, rootlets, and actin filaments. Cultured GAS2L2-deficient nasal epithelial cells from one of the affected individuals showed defects in ciliary orientation and had an asynchronous and hyperkinetic (GAS2L2-deficient = 19.8 Hz versus control = 15.8 Hz) ciliary-beat pattern. These results were recapitulated in Gas2l2^-/- mouse tracheal epithelial cell (mTEC) cultures and in X. laevis embryos treated with Gas2l2 morpholinos. In mice, the absence of Gas2l2 caused neonatal death, and the conditional deletion of Gas2l2 impaired mucociliary clearance (MCC) and led to mucus accumulation. These results show that a pathogenic variant in GAS2L2 causes a genetic defect in ciliary orientation and impairs MCC and results in PCD.

Coordination of eukaryotic cilia and flagella

Propulsion by slender cellular appendages called cilia and flagella is an ancient means of locomotion. Unicellular organisms evolved myriad strategies to propel themselves in fluid environments, often involving significant differences in flagella number, localisation and modes of actuation. Remarkably, these appendages are highly conserved, occurring in many complex organisms such as humans, where they may be found generating physiological flows when attached to surfaces (e.g. airway epithelial cilia), or else conferring motility to male gametes (e.g. undulations of sperm flagella). Where multiple cilia arise, their movements are often observed to be highly coordinated. Here I review the two main mechanisms for motile cilia coordination, namely, intracellular and hydrodynamic, and discuss their relative importance in different ciliary systems.

Challenges in nasal drug absorption: how far have we come?

The nasal route is commonly used for local delivery of drugs to treat inflammatory conditions. It is also an attractive route for systemic delivery of some drugs. Irrespective of intended use, administered drugs must permeate the epithelial or olfactory membrane to be effective. The enthusiasm for potential use of the nasal route for systemic drug delivery has not been met by comparable success. In this paper, the anatomical and physiological attributes of the nasal cavity and paranasal sinuses important for drug delivery and challenges limiting drug absorption are discussed. Efforts made so far in improving nasal drug absorption such as overcoming restrictive nasal geometry and paranasal sinuses accessibility, mucociliary clearance, absorption barriers, metabolism and drug physicochemical challenges are discussed. Highlights on future prospects of nasal drug delivery/absorption were discussed.

European Respiratory Society guidelines for the diagnosis of primary ciliary dyskinesia

The diagnosis of primary ciliary dyskinesia is often confirmed with standard, albeit complex and expensive, tests. In many cases, however, the diagnosis remains difficult despite the array of sophisticated diagnostic tests. There is no "gold standard" reference test. Hence, a Task Force supported by the European Respiratory Society has developed this guideline to provide evidence-based recommendations on diagnostic testing, especially in light of new developments in such tests, and the need for robust diagnoses of patients who might enter randomised controlled trials of treatments. The guideline is based on pre-defined questions relevant for clinical care, a systematic review of the literature, and assessment of the evidence using the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) approach. It focuses on clinical presentation, nasal nitric oxide, analysis of ciliary beat frequency and pattern by high-speed video-microscopy analysis, transmission electron microscopy, genotyping and immunofluorescence. It then used a modified Delphi survey to develop an algorithm for the use of diagnostic tests to definitively confirm and exclude the diagnosis of primary ciliary dyskinesia; and to provide advice when the diagnosis was not conclusive. Finally, this guideline proposes a set of quality criteria for future research on the validity of diagnostic methods for primary ciliary dyskinesia.

Automated image analysis reveals the dynamic 3-dimensional organization of multi-ciliary arrays

Multi-ciliated cells (MCCs) use polarized fields of undulating cilia (ciliary array) to produce fluid flow that is essential for many biological processes. Cilia are positioned by microtubule scaffolds called basal bodies (BBs) that are arranged within a spatially complex 3-dimensional geometry (3D). Here, we develop a robust and automated computational image analysis routine to quantify 3D BB organization in the ciliate, Tetrahymena thermophila. Using this routine, we generate the first morphologically constrained 3D reconstructions of Tetrahymena cells and elucidate rules that govern the kinetics of MCC organization. We demonstrate the interplay between BB duplication and cell size expansion through the cell cycle. In mutant cells, we identify a potential BB surveillance mechanism that balances large gaps in BB spacing by increasing the frequency of closely spaced BBs in other regions of the cell. Finally, by taking advantage of a mutant predisposed to BB disorganization, we locate the spatial domains that are most prone to disorganization by environmental stimuli. Collectively, our analyses reveal the importance of quantitative image analysis to understand the principles that guide the 3D organization of MCCs.

Summary: We develop an automated computational image analysis routine to quantify basal body organization, which detects subtle spatial phenotypes resulting from environmental and genetic perturbations.

DisAp-dependent striated fiber elongation is required to organize ciliary arrays

DisAp is a novel kinetodesmal fiber component that is essential for force-dependent fiber elongation and the alignment of basal body orientation in multiciliary arrays.

Cilia-organizing basal bodies (BBs) are microtubule scaffolds that are visibly asymmetrical because they have attached auxiliary structures, such as striated fibers. In multiciliated cells, BB orientation aligns to ensure coherent ciliary beating, but the mechanisms that maintain BB orientation are unclear. For the first time in Tetrahymena thermophila, we use comparative whole-genome sequencing to identify the mutation in the BB disorientation mutant disA-1. disA-1 abolishes the localization of the novel protein DisAp to T.thermophila striated fibers (kinetodesmal fibers; KFs), which is consistent with DisAp’s similarity to the striated fiber protein SF-assemblin. We demonstrate that DisAp is required for KFs to elongate and to resist BB disorientation in response to ciliary forces. Newly formed BBs move along KFs as they approach their cortical attachment sites. However, because they contain short KFs that are rotated, BBs in disA-1 cells display aberrant spacing and disorientation. Therefore, DisAp is a novel KF component that is essential for force-dependent KF elongation and BB orientation in multiciliary arrays.

Primary ciliary dyskinesia. Recent advances in diagnostics, genetics, and characterization of clinical disease

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous recessive disorder of motile cilia that leads to oto-sino-pulmonary diseases and organ laterality defects in approximately 50% of cases. The estimated incidence of PCD is approximately 1 per 15,000 births, but the prevalence of PCD is difficult to determine, primarily because of limitations in diagnostic methods that focus on testing ciliary ultrastructure and function. Diagnostic capabilities have recently benefitted from (1) documentation of low nasal nitric oxide production in PCD and (2) discovery of biallelic mutations in multiple PCD-causing genes. The use of these complementary diagnostic approaches shows that at least 30% of patients with PCD have normal ciliary ultrastructure. More accurate identification of patients with PCD has also allowed definition of a strong clinical phenotype, which includes neonatal respiratory distress in >80% of cases, daily nasal congestion and wet cough starting soon after birth, and early development of recurrent/chronic middle-ear and sinus disease. Recent studies, using advanced imaging and pulmonary physiologic assessments, clearly demonstrate early onset of lung disease in PCD, with abnormal air flow mechanics by age 6-8 years that is similar to cystic fibrosis, and age-dependent onset of bronchiectasis. The treatment of PCD is not standardized, and there are no validated PCD-specific therapies. Most patients with PCD receive suboptimal management, which should include airway clearance, regular surveillance of pulmonary function and respiratory microbiology, and use of antibiotics targeted to pathogens. The PCD Foundation is developing a network of clinical centers, which should improve diagnosis and management of PCD.

Primary ciliary dyskinesia. Recent advances in diagnostics, genetics, and characterization of clinical disease

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous recessive disorder of motile cilia that leads to oto-sino-pulmonary diseases and organ laterality defects in approximately 50% of cases. The estimated incidence of PCD is approximately 1 per 15,000 births, but the prevalence of PCD is difficult to determine, primarily because of limitations in diagnostic methods that focus on testing ciliary ultrastructure and function. Diagnostic capabilities have recently benefitted from (1) documentation of low nasal nitric oxide production in PCD and (2) discovery of biallelic mutations in multiple PCD-causing genes. The use of these complementary diagnostic approaches shows that at least 30% of patients with PCD have normal ciliary ultrastructure. More accurate identification of patients with PCD has also allowed definition of a strong clinical phenotype, which includes neonatal respiratory distress in >80% of cases, daily nasal congestion and wet cough starting soon after birth, and early development of recurrent/chronic middle-ear and sinus disease. Recent studies, using advanced imaging and pulmonary physiologic assessments, clearly demonstrate early onset of lung disease in PCD, with abnormal air flow mechanics by age 6-8 years that is similar to cystic fibrosis, and age-dependent onset of bronchiectasis. The treatment of PCD is not standardized, and there are no validated PCD-specific therapies. Most patients with PCD receive suboptimal management, which should include airway clearance, regular surveillance of pulmonary function and respiratory microbiology, and use of antibiotics targeted to pathogens. The PCD Foundation is developing a network of clinical centers, which should improve diagnosis and management of PCD.

Kif3a interacts with Dynactin subunit p150 Glued to organize centriole subdistal appendages

Formation of cilia, microtubule-based structures that function in propulsion and sensation, requires Kif3a, a subunit of Kinesin II essential for intraflagellar transport (IFT). We have found that, Kif3a is also required to organize centrioles. In the absence of Kif3a, the subdistal appendages of centrioles are disorganized and lack p150(Glued) and Ninein. Consequently, microtubule anchoring, centriole cohesion and basal foot formation are abrogated by loss of Kif3a. Kif3a localizes to the mother centriole and interacts with the Dynactin subunit p150(Glued). Depletion of p150(Glued) phenocopies the effects of loss of Kif3a, indicating that Kif3a recruitment of p150(Glued) is critical for subdistal appendage formation. The transport functions of Kif3a are dispensable for subdistal appendage organization as mutant forms of Kif3a lacking motor activity or the motor domain can restore p150(Glued) localization. Comparison to cells lacking Ift88 reveals that the centriolar functions of Kif3a are independent of IFT. Thus, in addition to its ciliogenic roles, Kif3a recruits p150(Glued) to the subdistal appendages of mother centrioles, critical for centrosomes to function as microtubule-organizing centres.

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.

Diagnostic testing of patients suspected of primary ciliary dyskinesia

RATIONALE

Electron microscopy (EM) of ciliated epithelium is widely used to diagnose primary ciliary dyskinesia (PCD). Ciliary beat frequency (CBF) has been used to screen samples to determine whether EM is indicated. Beat pattern analysis has been advocated as an additional diagnostic test. Neither has been subject to formal review.

OBJECTIVES

To determine the ability of CBF and beat pattern analysis to predict EM-diagnosed PCD.

METHODS

CBF calculation and beat pattern analysis, using high-speed video microscopy, and EM were performed on nasal tissue from 371 patients consecutively referred to the Leicester Royal Infirmary for diagnostic assessment for PCD. With EM as the "gold standard," receiver operating characteristic (ROC) curves were constructed and sensitivity, specificity, and positive (PPV) and negative (NPV) predictive values were calculated for CBF less than 11 Hz, ciliary dyskinesia score equal to or exceeding 2, at least 90% of ciliated edges beating dyskinetically, and an immotility index equal to or exceeding 10%.

MEASUREMENTS AND MAIN RESULTS

PCD was excluded in 270 patients and confirmed in 70 by EM. The sensitivity, specificity, PPV, and NPV for CBF less than 11 Hz were 87.1, 77.2, 50.0, and 95.8%, respectively. These values were higher for ciliary dyskinesia scores equal to or exceeding 2 (92.5, 97.6, 91.2, and 98.0%) and when at least 90% of ciliated edges were dyskinetic (97.1, 95.3, 84.6, and 99.2%). ROCs confirmed that the ciliary dyskinesia score and percentage of dyskinetic edges were superior screening indices compared with CBF and the immotility index.

CONCLUSIONS

The use of CBF alone to screen which biopsies should have EM will result in a significant number of missed diagnoses. Ciliary beat pattern analysis is a more sensitive and specific test for PCD with higher PPV and NPV.

Cilia orientation and the fluid mechanics of development

Motile cilia produce large-scale fluid flows crucial for development and physiology. Defects in ciliary motility cause a range of disease symptoms including bronchiectasis, hydrocephalus, and situs inversus. However, it is not enough for cilia to be motile and generate a flow -- the flow must be driven in the proper direction. Generation of properly directed coherent flow requires that the cilia are properly oriented relative to tissue axes. Genetic, molecular, and ultrastructural studies have begun to suggest pathways linking cilia orientation to planar cell polarity (PCP) and other long-range positional cues and also suggest that cilia-driven flow can itself play a causal role in orienting the cilia that create it. Errors in cilia orientation have been observed in human ciliary disease patients, suggesting that orientation defects may constitute a novel class of ciliopathies with a distinct etiology at the cell biological level.

Aspiration, Bronchial Obstruction, Bronchiectasis, and Related Disorders

The conducting airways play a pivotal role in the spectrum of pulmonary pathology, not only as conduits for injurious agents to enter the lung, but also as an anatomic compartment that is affected by a diverse array of primary or secondary bronchocentric diseases. This chapter discusses aspiration and bronchial obstruction in detail, with emphasis on the aspiration of toxic, infective, or particulate matter. Lung abscess, a frequent complication of obstruction or aspiration, is also reviewed. Both aspiration and lung abscess are reconsidered within the context of pulmonary infectious disease mainly in Chapter 8 on bacterial infections, and to some extent in the chapters on mycobacterial (Chapter 9), fungal (Chapter 10), and parasitic diseases (Chapter 14).

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.

Ciliary central microtubular orientation is of no clinical significance in bronchiectasis

It has been suggested that patients with bronchiectasis might have increased central microtubular orientation angle (CMOA), which leads to poor coordination of ciliary beating, and consequently impairment of airway defence. We have employed transmission electron microscopy to assess CMOA of ciliated nasal mucosa in a cohort of 133 (81F, 56.8+/-16.1yr) stable bronchiectasis and 59 healthy subjects (30F, 49.3+/-22.1yr). There was no significant difference in CMOA between bronchiectasis (13.2 degree) and control subjects (13.0 degree, P=0.82). There was no significant difference in CMOA among patients according to the etiology of bronchiectasis, presence of nasal symptoms, or sputum status of Pseudomonas aeruginosa infection. Patients with more severe bronchiectasis, i.e. those with FEV(1) <60%, FVC <60%, or more than 4 bronchiectatic lung lobes, had significantly lower CMOA than their counterparts (P<0.05). There was no correlation between CMOA with age, 24h sputum volume, exacerbation frequency, FEV(1), FVC, or the number of bronchiectatic lung lobes (P>0.05). CMOA correlated with ciliary beat frequency (negative), and the percent of cilia showing ultrastructural or microtubular defects (P<0.05). Central microtubular orientation angle does not correlate with clinically important parameters, in contrary to the results reported by previously published smaller scale studies.

The secondary nature of ciliary (dis)orientation in secondary and primary ciliary dyskinesia

OBJECTIVE

Ciliary orientation (COR) is an important parameter of mucociliary clearance and ciliary disorientation has been reported in cases of acquired abnormalities [secondary ciliary dyskinesia (SCD)] and in a very few cases as the single abnormality in primary ciliary dyskinesia (PCD). The etiology, pathogenesis, consequences and relevance of ciliary (dis)orientation are still unclear.

MATERIAL AND METHODS

To elucidate the primary or secondary nature of ciliary (dis)orientation, COR was measured in 179 non-PCD and 59 PCD patients. COR was measured in biopsies and after ciliogenesis in culture and was correlated with a number of functional and ultrastructural parameters. COR was defined as the SD of the angles of lines through the central pair of microtubules using transmission electron microscopy. Internationally accepted normal values for COR are < or = 20 degrees; COR values of 20-35 degrees indicate increased disorientation; and COR values > 35 degrees represent a random orientation.

RESULTS

For non-PCD biopsies, COR increased with increasing SCD, from 15 +/- 7 degrees (n = 54) for normal (< 5%) SCD to 28 +/- 8 degrees (n = 16) for severe (> 25%) SCD. No correlation was found between COR and ciliary beat frequency. However, increased COR values (28 +/- 8 degrees) were found for immotility (n = 8), compared to (coordinated) ciliary activity (19 +/- 9 degrees) (n = 121). After ciliogenesis no ultrastructural abnormalities were found and COR was normal (13 +/- 5 degrees; n = 308). COR can therefore be considered to be secondary in non-PCD and correlates with SCD percentage and ciliary motility. In biopsies from PCD patients with dynein deficiency and with normal ultrastructure, COR was increased, to 28 +/- 11 degrees (n = 32) and 21 +/- 7 degrees (n = 15), respectively, and in cases with central pair abnormalities COR was random (38 +/- 11 degrees; n = 12). After ciliogenesis COR remained random in the PCD group with central pair abnormalities (38 +/- 9 degrees; n = 15), and was increased in the PCD groups with dynein deficiency (24 +/- 10 degrees; n = 35) and normal ultrastructure (25 +/- 8 degrees; n = 17). Ciliary disorientation was never found as the single abnormality.

CONCLUSION

COR can be considered to be secondary in PCD. Both ciliary (im)motility and SCD percentage contribute to COR.

The office management of recalcitrant rhinosinusitis

The patient referred to the otolaryngologist for the treatment of CRS has received many therapies for the condition. Newer therapies available focus on the anti-inflammatory therapies and local application of antimicrobial and antifungal agents to the sinus cavities. Much clinical work remains to be done to prove the efficacy of currently available treatments. The recent advances in the understanding of allergic and immune mechanisms may allow eventual intervention at the level of cytokines and other immunomodulators of inflammation. The complex cascade of interleukins and proinflammatory agents in CRS patients may some day allow "silver bullet" therapies in the properly selected patient. Until then, a systematic approach to the evaluation of these patients and management with the currently available treatment modalities may help relieve the symptoms in patients with CRS.

Ciliary beat pattern is associated with specific ultrastructural defects in primary ciliary dyskinesia

BACKGROUND

The main symptoms of primary ciliary dyskinesia (PCD) are nasal rhinorrhea or blockage and moist-sounding cough. Diagnosis can be difficult and is based on an abnormal ciliary beat frequency, accompanied by specific abnormalities of the ciliary axoneme. It is unknown whether determining ciliary beat pattern related to specific ultrastructural ciliary defects might help in the diagnosis of PCD.

OBJECTIVE

We sought to determine ciliary beat pattern and beat frequency (CBF) associated with the 5 common ultrastructural defects responsible for PCD.

METHODS

Nasal brushings were performed on 56 children with PCD. Ciliary movement was recorded using digital high-speed video imaging to assess beat frequency and pattern. Electron microscopy was performed.

RESULTS

In patients with an isolated outer dynein arm or with an outer and inner dynein arm defect, 55% and 80% of cilia were immotile, respectively. Cilia that moved were only flickering. Mean CBF (+/- 95% CI) was 2.3 Hz (+/- 1.2) and 0.8 Hz(+/- 0.8), respectively. Cilia with an isolated inner dynein arm or a radial spoke defect had similar beat patterns. Cilia appeared stiff, had a reduced amplitude, and failed to bend along their length. Immotile cilia were present in 10% of cilia with an inner dynein arm defect and in 30% of radial spoke defects. Mean CBF was 9.3 Hz (+/- 2.6) and 6.0 Hz (+/- 3.1), respectively. The ciliary transposition defect produced a large circular beat pattern (mean CBF, 10.7 Hz [+/- 1.1]). No cilia were immotile.

CONCLUSIONS

Different ultrastructural defects responsible for PCD result in predictable beat patterns. Recognition of these might help in the diagnostic evaluation of patients suspected of having PCD.

Functional analysis of cilia and ciliated epithelial ultrastructure in healthy children and young adults

BACKGROUND

There are very few data on normal ciliary beat frequency, beat pattern, and ultrastructure in healthy children and adults. A study was undertaken to define ciliary structure, beat frequency and beat pattern in a healthy paediatric and young adult population.

METHODS

Ciliated epithelial samples were obtained from 76 children and adult volunteers aged 6 months to 43 years by brushing the inferior nasal turbinate. Beating cilia were recorded using a digital high speed video camera which allowed analysis of ciliary beat pattern and beat frequency. Tissue was fixed for transmission electron microscopy.

RESULTS

The mean ciliary beat frequency for the paediatric population (12.8 Hz (95% CI 12.3 to 13.3)) was higher than for the adult group (11.5 Hz (95% CI 10.3 to 12.7 Hz), p<0.01, t test); 10% (range 6-24%) of ciliated edges were found to have areas of dyskinetically beating cilia. All samples had evidence of mild epithelial damage. This reflected changes found in all measurements used for assessment of epithelial damage. Ciliary ultrastructural defects were found in less than 5% of cilia.

CONCLUSION

Normal age related reference ranges have been established for ciliary structure and beat frequency. In a healthy population localised epithelial damage may be present causing areas of ciliary dyskinesia.

Directional disorder of ciliary metachronal waves using two-dimensional correlation map

The interrelationship of cilia and the order of wave directions are important factors that determine the effectiveness of cilia to transport materials in mucociliary systems of the respiratory tract. The interrelationship of cilia and the directional disorder of ciliary metachronal wave were analyzed using digital microscopic images. The degree of synchronization between ciliary beats was determined by the correlation factor between two different spots. To find out the uniphase directions of beating cilia, principal axes of inertia were applied to the two-dimensional correlation map calculated from sequential ciliary images. The standard deviation of determined wave directions in a region of interest (ROI) was defined as a measure of metachronal wave disorder. The pooled mean of metachronal wave disorder was 23.4 +/- 8.79 degrees in ROIs of 8 microm x 8 microm and 25.4 +/- 6.46 degrees in 32 microm x 24 microm from the sphenoid sinus mucosa of five normal subjects. Our result shows that there is a considerable variation in metachronal wave directions of cilia beating on the epithelium.

Changing paradigms in the diagnosis and management of bronchiectasis

The face of bronchiectasis may have changed in recent years but individual cases continue to pose difficult challenges. As childhood infection becomes less of a problem, alternative causes of bronchiectasis are increasingly recognized which themselves offer new problems of diagnosis and management. Evolving concepts of pathogenesis suggest alternative strategies for treatment but as yet the evidence base on which to make firm decisions is lacking. Antibacterial regimens are not universally applicable and individualized protocols with parenteral, nebulized or continuous antibacterial therapy are increasingly used in the treatment of patients with bronchiectasis. Despite the theoretical appeal of using mucolytic or anti-inflammatory drugs their roles are still uncertain and have yet to be examined in adequate clinical trials. The factors determining disease progression are still poorly understood but in some patients worsening airflow obstruction heralds the onset of ventilatory failure. The management of the latter requires bronchodilators and controlled oxygen therapy, and strategies including non-invasive ventilation are increasingly an option. Changing indications for surgery are evident with fewer palliative resections but a developing role for transplantation.

Ciliary dyskinesia associated with hydrocephalus and mental retardation in a Jordanian family

OBJECTIVE

To describe the presentation and genetic transmission of ciliary dyskinesia syndrome associated with hydrocephalus and mental retardation in 3 generations of a family.

PATIENTS AND METHODS

A large Jordanian family included 9 individuals in 3 generations with recurrent pulmonary infections; 4 male siblings have been diagnosed as having mental retardation, and a maternal uncle was believed to have been similarly affected. Chromosome analysis of the family showed a normal karyotype.

RESULTS

Electron microscopy of the nasal cilia from 3 affected siblings showed features of primary ciliary dyskinesia. Computed tomographic scans of the brains of all 4 affected siblings showed hydrocephalus.

CONCLUSIONS

The recurrent pulmonary infections and hydrocephalus in this large Jordanian family are likely related to ciliary dyskinesia, which appears to follow an autosomal recessive mode of inheritance. The unusual presentation of ciliary dyskinesia, hydrocephalus, and mental retardation may be due to a new genetic mutation.

Discinesia ciliar primária

Discinesia ciliar primária é uma doença autossômica recessiva caracterizada pela história de infecções repetidas do trato respiratório superior e inferior, otite média, bronquite e rinossinusite, associada a situs inversus na metade dos casos. O diagnóstico é estabelecido pela análise ciliar ultra-estrutural de espécimes respiratórios, após a exclusão inicial de outras doenças, como fibrose cística, deficiência de alfa-1-antitripsina, imunodeficiências (IgG, neutrófilos e complemento) e síndrome de Young. O propósito deste artigo é revisar os achados clínicos, o diagnóstico e o manejo da discinesia ciliar primária, incluindo um fluxograma diagnóstico.

Primary ciliary dyskinesia syndrome associated with abnormal ciliary orientation in infants

Primary ciliary dyskinesia (PCD) syndrome associated with abnormal ciliary orientation but with normal ciliary ultrastructure has been described in adults, but there are no normal ranges for orientation in infants, despite the fact that half of all patients with PCD present in the new-born period. Nasal brush biopsies were obtained from eight infants (three males), mean age 13.1 months, range 7-23, in order to determine ciliary orientation. They had no upper or lower airway disease and normal organ arrangement and were undergoing general anaesthesia for other reasons. Two infants with typical PCD syndrome but normal ultrastructure of individual cilia also had orientation studies. In the eight normal subjects, a mean of 254 central pairs was examined, range 82-453. The mean ciliary orientation was 14.9 degrees, range 12.9-17.5. The two infants with PCD syndrome but normal ultrastructure of individual cilia had ciliary orientation of (Case 1) 44.5 degrees (range 10.6-64.5) in 218 central pairs; and on a second occasion, 28.9 degrees, (range 9.0-47.5) in 259 central pairs; for Case 2, 24.4 degrees, (range 13.1-38.4) in 196 central pairs. The normal range for ciliary orientation is similar in infants to that described in other work in adults. The two cases of phenotypic primary ciliary dyskinesia in the presence of normal ciliary ultrastructure but abnormal ciliary orientation in infants supports the contention that measurement of ciliary orientation should be part of the assessment of ciliary structure and function in cases of possible primary ciliary dyskinesia, in particular when the ultrastructure of individual cilia appear to be normal.

Diagnostic evaluation of mucociliary transport: from symptoms to coordinated ciliary activity after ciliogenesis in culture

Mucociliary transport is one of the most important local defense mechanisms of the airways, but it is prone to many and frequent acquired abnormalities and to inherited abnormalities. These abnormalities result in basic physiologic disturbances leading to a number of respiratory symptoms and signs. In order to critically evaluate the diagnostic value of parameters of this mucociliary cascade, the results of ciliary investigations in over 500 individuals (controls, acquired, and inherited abnormalities) were reviewed. Ciliary beat frequency, ciliary coordination and ultrastructural abnormalities were measured and evaluated in biopsies and after ciliogenesis in culture. There is a considerable overlap for all investigated parameters in biopsy material of controls, secondary, and primary ciliary dyskinesia. There is not one parameter that is diagnostic for primary ciliary dyskinesia or can be used as an exclusion criterion. After ciliogenesis in culture, cilia are always completely normal except for the inherited abnormalities. Absence of coordinated ciliary activity after ciliogenesis in culture is 100% sensitive and specific for the diagnosis of primary ciliary dyskinesia.

Ciliary function analysis for the diagnosis of primary ciliary dyskinesia: advantages of ciliogenesis in culture

The gold standard for the diagnosis of primary ciliary dyskinesia (PCD) is a dynein deficiency shown with transmission electron microscopy. However, there are many cases of PCD without dynein deficiency. When considering ciliary function, there are similar problems of sensitivity in diagnosis and there is also a major lack of specificity. Based on the normal ciliary function and ultrastructure and the absence of secondary abnormalities after ciliogenesis in sequential monolayer-suspension culture, the diagnostic value of ciliary function analysis after ciliogenesis was investigated in more than 70 PCD and 640 non-PCD cases. In biopsies, ciliary immotility was found in 66% of PCD cases but was also found in 8% of non-PCD cases. PCD was later confirmed in 61% of the biopsies with ciliary immotility. Normal ciliary beat frequency (CBF) was found in 20% of PCD biopsies. Coordinated ciliary activity was observed in 10% of PCD cases. After ciliogenesis in culture, ciliary immotility was present in 78% of the PCD cases but never in non-PCD cases. CBF was normal after ciliogenesis in 7% of the PCD cases and was always found in non-PCD cases. Absence of coordinated ciliary activity was found in 100% of PCD cases and 0% of non-PCD cases. In conclusion, while ciliary function analysis in a biopsy never proves, nor excludes the diagnosis of PCD, after ciliogenesis in culture CBF measurement can be diagnostic for PCD and reaches 100% specificity and sensitivity when considering coordinated ciliary activity, making it the single 100% diagnostic parameter for PCD.

Special techniques in diagnostic electron microscopy

The power of electron microscopy as a diagnostic tool can be amplified considerably by the application of ancillary preparative and analytic methods. Subcellular chemistry and structure can be examined by various forms of microprobe analysis and by special staining methods, including cytochemical, immunocytochemical, and negative staining. Qualitative ultrastructural examination can be augmented by morphometric analysis. Correlative microscopic survey methods can be used as a means of targeting ultrastructural investigations. This article provides an overview of the use of these special techniques in the diagnosis and classification of tumors and other selected pathologic processes.

Correlations among mucociliary transport, ciliary function, and ciliary structure

Mucociliary transport is one of the most important defense mechanisms of the airway. Mucociliary transport time or rate, as measured using the saccharin test or the radioisotope technique, respectively, is clinically the most relevant parameter, although subject to large intra- and interindividual variability. There is no correlation between mucociliary transport in vivo and ciliary beat frequency ex vivo. Preliminary evidence demonstrates that mucociliary transport correlates with ciliary structure and orientation as investigated with transmission and scanning electron microscopy. A correlation is presented between ciliary beat frequency and secondary ciliary abnormalities. This correlation can best be described according to the logistic sigmoid model (r = 0.69). Based on these functional data, an ultrastructural distinction is proposed among normal (less than 5%), light (5 to 15%), moderate (15 to 25%), and severe (more than 25%) secondary ciliary dyskinesia.