Functional analysis and evaluation of respiratory cilia in healthy Chinese children

Abstract

Background: To aid in the diagnosis of Primary Ciliary Dyskinesia (PCD) and to evaluate the respiratory epithelium in respiratory disease, normal age-related reference ranges are needed for ciliary beat frequency (CBF), beat pattern and ultrastructure. Our aim was to establish reference ranges for healthy Chinese children.

Methods: Ciliated epithelial samples were obtained from 135 healthy Chinese children aged below 18 years by brushing the inferior nasal turbinate. CBF and beat pattern were analysed from high speed video recordings. Epithelial integrity and ciliary ultrastructure were assessed using transmission electronic microscopy.

Results: The mean CBF from 135 children studied was 10.1 Hz (95% CI 9.8 to 10.4). Approximately 20% (ranged 18.0-24.2%) of ciliated epithelial edges were found to have areas of dyskinetically beating cilia. Normal beat pattern was observed in ciliated epithelium from all subjects. We did not find any effect of exposure to second hand smoke on CBF in our subjects. Microtubular defects were found in 9.3% of all of the cilia counted in these children, while other ciliary ultrastructural defects were found in less than 3%.

Conclusions: We established the reference range for CBF, beat pattern and ultrastructure in healthy Chinese children. Using similar methodology, we found a lower overall mean CBF than previously obtained European values. This study highlights the need to establish normative data for ciliary function in different populations.

Keywords: Beat frequency; Beat pattern; Chinese children; Nasal cilia; Reference data; Ultrastructure.

Fig. 1

Relationship of the ciliary beat frequency (CBF) with age (years). a Mean CBF plotted against age for all subjects showing a negative correlation between increasing age and a reduction in CBF. Mean (solid line) and ± 1.96 standard deviation (dashed line) regression lines were indicated. b Ciliated edges with the highest and CBF within a nasal sample plotted against age for all subjects. Mean (solid line) and ± 1.96 standard deviation (dashed line) regression lines were indicated. c Ciliated edges with the lowest CBF within a nasal sample plotted against age for all subjects. Mean (solid line) and ± 1.96 standard deviation (dashed line) regression lines were indicated

Fig. 2

Transmission electron micrographs showing the normal epithelium and the parameters assessed to examine the epithelial damage. a Normal with a normal healthy mitochondrion (arrow, bar = 1 μm). b Loss of cilia, grade 3, and a cell with a damaged mitochondrion (arrow, bar = 1 μm). c Cellular extrusion, grade 2, (bar = 2 μm). d Cytoplasmic blebbing, grade 2 (arrow, bar = 2 μm)

Fig. 3

Transmission electron micrographs illustrating the assessment of epithelial integrity. a Normal nasal epithelium with an intact ciliated surface and minimal disruption (epithelial integrity score = 0, bar = 2 μm). b Abnormal epithelium with severely disrupted cell surface and marked loss of cilia (epithelial integrity score = 4, bar = 2 μm)

Fig. 4

Transmission electron micrographs demonstrating the representative image of ciliary ultrastructural defects. a Normal. b-e Microtubule defects. f-g Central microtubules defects. h Compound cilia. i Combination of microtubule defects.