Quantitative analysis of ciliary ultrastructure in patients with primary ciliary dyskinesia

Quantitative Assessment of Ciliary Ultrastructure with the Use of Automatic Analysis: PCD Quant

The ciliary ultrastructure can be damaged in various situations. Such changes include primary defects found in primary ciliary dyskinesia (PCD) and secondary defects developing in secondary ciliary dyskinesia (SCD). PCD is a genetic disease resulting from impaired ciliary motility causing chronic disease of the respiratory tract. SCD is an acquired condition that can be caused, for example, by respiratory infection or exposure to tobacco smoke. The diagnosis of these diseases is a complex process with many diagnostic methods, including the evaluation of ciliary ultrastructure using transmission electron microscopy (the golden standard of examination). Our goal was to create a program capable of automatic quantitative analysis of the ciliary ultrastructure, determining the ratio of primary and secondary defects, as well as analysis of the mutual orientation of cilia in the ciliary border. PCD Quant, a program developed for the automatic quantitative analysis of cilia, cannot yet be used as a stand-alone method for evaluation and provides limited assistance in classifying primary and secondary defect classes and evaluating central pair angle deviations. Nevertheless, we see great potential for the future in automatic analysis of the ciliary ultrastructure.

Additional role of bronchial mucosal biopsy for ciliary structural abnormality in diagnosis of primary ciliary dyskinesia

Background

Transmission electron microscopy (TEM) is one of diagnostic tests for primary ciliary dyskinesia (PCD). The mucosal samples obtained for cilia examination are generally procured from the nasal turbinate, but these specimens often yield inadequate results. The bronchial mucosa is recognized as an alternative sample, but no study has examined the additional utility of bronchial mucosa compared with nasal mucosa in the diagnosis of PCD.

Methods

The medical records of 96 patients who underwent TEM for suspected PCD between April 1997 and June 2017 were reviewed. Patients were divided into three groups based on the site of mucosal biopsy: nasal biopsy (NB) group with nasal mucosal biopsy only; bronchial biopsy (BB) group with bronchial mucosal biopsy only; and nasal and bronchial biopsy (NBB) group with a combination of nasal and bronchial mucosal biopsies.

Results

The rate of PCD diagnosis was 28.8% (17/59) in the NB group, 41.2% (7/17) in the BB group, and 60.0% (12/20) in the NBB group. The yield of PCD diagnosis significantly increased in the NBB group compared with the NB group (P=0.012). In the NBB group, 25.0% (5/20) of patients were diagnosed with PCD by nasal mucosal biopsy, and 35.0% (7/20) of patients were additionally diagnosed by bronchial mucosal biopsy. The presence of sinusitis or bronchiectasis was not associated with prediction of PCD diagnosis from nasal or bronchial mucosal biopsy.

Conclusions

The combination of nasal and bronchial mucosal biopsy for TEM showed higher yields of PCD diagnosis than nasal mucosal biopsy alone.

Histologic and Ultrastructural Findings in Dogs With Chronic Respiratory Disease Suspected of Ciliary Dyskinesia

Mucociliary clearance is a main defense mechanism of the respiratory tract, which can be inherently impaired in primary ciliary dyskinesia (PCD) or reversibly altered in secondary ciliary dyskinesia (SCD). Limited diagnostic test availability likely leads to misdiagnosis or underdiagnosis of PCD in animals. This study evaluated the light and transmission electron microscopy (TEM) changes in the respiratory mucosa of 15 dogs with chronic respiratory disease suspected of PCD. Necropsy was performed in 1 case and 2 dogs were used as negative controls. PCD was confirmed in 1 dog, which presented with chronic otitis, bronchopneumonia, hydrocephalus and ultrastructural abnormalities in 84% of the assessed cilia, including absence of dynein arms and microtubular changes. The 14 other cases showed only nonspecific alterations, such as ciliary disorientation, compound cilia, ciliary edema, and axoneme bubbles in a minority of the evaluated cilia and were classified as SCD. Ciliary ultrastructural analysis can confirm a diagnosis of PCD if specific abnormalities exist. TEM remains an important investigational tool in veterinary medicine, as no other specific test for PCD in dogs has been standardized yet.

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.

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.

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.

Mutations in dynein genes in patients affected by isolated non-syndromic asthenozoospermia

BACKGROUND

Asthenozoospermia (AZS) is a common cause of male infertility characterized by reduced forward motility (WHO grade A+B sperm motility <50% or A < 25%) or absent sperm motility in fresh ejaculate. AZS may exist as an isolated disorder, in combination with other sperm anomalies or as part of a syndromic association. Up to date, only a few genes, constituting the cilia/flagella structure, have been associated with isolated AZS in humans, whereas several other genes are known to be involved in syndromic form of AZS, including primary ciliary dyskinesia (PCD) and Kartagener syndrome (KS). Axonemal ultrastructural defects, including absent or shortened arms of dyneins, can be found in >50% of PCD/KS patients. Approximately 90% of KS male patients are affected by AZS. The majority of KS patients can be ascribed to dynein genes mutations.

METHODS

Mutation screening of DNAI1, DNAH5 and DNAH11 genes was performed in 90 patients with isolated non-syndromic AZS and 200 controls.

RESULTS

We found three mutations (one in each gene) specifically associated with AZS in seven patients (7.8%). Mutations are inherited from the mothers and may be found in familial clusters. No ultrastructural axonemal anomaly was detected in sperm.

CONCLUSIONS

We report for the first time a possible association between mutations in dynein genes and isolated AZS. Male carriers of the mutations always exhibit AZS, whereas female carriers manifest no alterations in either fertility or pulmonary clearance.