Ciliary function and motor protein composition of human fallopian tubes

Abstract

Study question: What is the motor protein composition and function of human fallopian tube (FT) cilia?

Summary answer: Although the motor protein composition and function of human FT cilia resemble that of respiratory cilia, females with primary ciliary dyskinesia (PCD) are not necessarily infertile.

What is known already: FTs are lined with multiple motile cilia, which show a 9 + 2 ultrastructure by transmission electron microscopy. Case reports suggest an increased incidence of subfertility and ectopic pregnancy in women with PCD, a disease characterized by dysfunction of motile cilia and flagella.

Study design, size, duration: This study consisted of an observational laboratory study on human FT specimens from five healthy females recruited from April 2012 to December 2013 and a descriptive observational retrospective analysis of a clinical PCD database.

Participants/materials, setting, methods: Human FT tissue was obtained from five healthy females after tubal ligation during caesarean delivery. Motor protein composition was assessed by immunofluorescence microscopy using antibodies against dynein arms and nexin-dynein regulatory complex subunits. Ciliary motility was analysed by high-speed video microscopy. A retrospective search of our database of PCD individuals was performed for information on conception and childbirth.

Main results and the role of chance: The motor protein composition of human FT cilia was identical to that of respiratory cilia. FT cilia showed coordinated beating, resulting in a directed fluid flow towards the uterine cavity. We identified nine PCD individuals with severe dysfunction of respiratory cilia who gave birth to children after spontaneous conception. This suggests that ciliary beating is not the key motor of ovum transport.

Limitations, reason for caution: FT cilia of affected PCD females were not available for analysis. Thus, it remains to be proven that FT cilia indeed show the same defects as respiratory cilia in PCD individuals. Comprehensive epidemiological studies are needed to determine the extent of female (sub-) fertility in PCD.

Wider implications of the findings: Knowledge of the exact protein composition and function of FT cilia will contribute to a better understanding of cilia-generated fluid flow in female reproduction. These findings are important for subsequent studies of function and protein composition of FT cilia in PCD patients.

Keywords: PCD; cilia; motor proteins; oviduct.