Mucus and the mare: how little we know.

The study explores the role of mucus and mucociliary currents in equine (horse) uterine health and fertility, acknowledging the undefined but potential significant part these biological components may play in preventing uterine infections, which are a leading cause of horse infertility.

Understanding Mucociliary Current Roles in Mammalian Biology

• The article recounts the recognized part played by mucociliary currents in protecting mucous membranes, including in respiratory tracts of mammals as well as being involved in feeding and oxygenation processes among aquatic invertebrates.
• It is suggested that these mucociliary currents also play an undiscovered role in uterine defence in horses.

Uterine Defence and Mucus

• Traditionally in horse biology, phagocytosis – where cells ‘eat’ pathogens – was considered the primary line of uterine defense.
• However, some doubts have been raised about the effectiveness of phagocytosis within the uterine lumen, leading researchers to propose other underlying defences, such as mucociliary currents.

Uterine Anatomy and Mucociliary Clearance

• The work indicates that the uterine epithelium shows a pattern of alternating mucus-secreting and ciliated cells, which are configured to support a mucopolysaccharide blanket, a feature shared with mucociliary membranes in many other species.
• It also notes that the uterine and cervical folds might represent anatomical adaptations favoring mucociliary clearance.
• Equally, it was found that ciliated cells gathered from uterine lavages often exhibited motion, an indication of active mucociliary activity.

Disruption of Mucociliary Clearance and Infections

• The study links disruptions of mucociliary clearance to the development of mucosal infections in humans, naming conditions such as pneumonia, chronic sinusitis, and otitis media as examples.
• It suggests that similar disruptions may contribute to uterine infections in horses, which could be associated with accumulations of uterine fluid, loss of endometrial folds, and cervical trauma.

Clinical Implications and Future Studies

• The researchers discuss possible clinical implications of mucociliary clearance in equine uterine health and fertility, underpinning the need for future in-depth studies.
• While considerable knowledge gaps remain, understanding the role of mucus and mucociliary clearance in equine uterine health could open new avenues for the treatment and prevention of infertility in horses.