The Effect of Aging on Nasal Mucociliary Clearance, Beat Frequency, and Ultrastructure of Respiratory Cilia

Abstract

The increased susceptibility of the elderly to lower respiratory tract infection cannot be fully explained. Although mucociliary clearance, which is affected by ciliary beating and ultrastructure, plays a crucial role in the defense of the airways against inhaled microbes, little is known of the effects of aging on these parameters. We studied the nasal mucociliary clearance (NMCC) time, ciliary beat frequency, and ultrastructure of respiratory cilia in a cohort of healthy volunteers (age range 11 to 90 yr). Ciliary beat frequency of ciliated nasal epithelial cells was obtained via an established photometric method, and NMCC time was measured with the saccharine test. There was a correlation of ciliary beat frequency (r = -0.48, p = 0.0001) and NMCC time r = 0.64, p < 0.001) with increasing age. Transmission electron microscopy revealed an increase in the percent of subjects exhibiting microtubular disarrangement and single central microtubules with aging (p = 0.002 and p = 0.005, respectively). Subjects older than 40 yr of age had significantly slower ciliary beat frequency, higher percent of ciliary cross-sections displaying single tubules, and longer NMCC time than their younger counterparts (p < 0.05). These findings may help explain the frequent occurrence of respiratory infection in the elderly.

The Effect of Ageing on Nasal Mucociliary Clearance in Women: A Pilot Study

“…Our results are in accordance with those of Ho et al [10] who studied NMC time along with ciliary beat frequency and ultrastructure of respiratory cilia, which are determinants of the efficiency of ciliary action. They found that there was a significant difference between the NMC time for subjects under and over the age of 40 years and that there was a significant correlation between NMC time and age.…”

“…Although this might be explained by ciliary defects or impaired mucociliary clearance or physiologic/structural changes in the senescent lung, very little data exists on the effect of ageing on mucociliary clearance [10].…”

“…Anatomical changes that occur with ageing include nasal mucosal damage which has accumulated from infections over the years, ciliary ultrastructural defects such as the occurrence of increased central microtubular disorientation, age-related changes in lung morphology resulting in altered proportions of elastic tissues and collagen [10], and alterations in the cross-linkage of ageing collagen [11].…”

“…This could be the result of abnormal ciliary ultrastructure or occur de novo [3,10]. Additionally, quantitative and qualitative changes in respiratory mucus and a lower tracheal mucus velocity could be causes of impaired mucociliary clearance among the elderly [10].…”

“…Though some researchers have reported that there is no gender difference in NMC [10,17], the study would have been more comprehensive had it included male subjects as well. (ii) Small sample size: this is a preliminary study to assess the effect of age on NMC in a population of periurban women.…”