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Ciliary function in horses with inflammatory lung disease
Dorothee Bienzle, Professor, Pathobiology, DVM Guelph, PhD McMaster, Diplomate ACVP

Cilia are small hair-like extensions on cells that line the nose, trachea and larger airways. The function of cilia is to move a layer of mucus produced by cells in the lower airways toward the mouth for swallowing, and therefore to protect the lung from inhaled particles. Thus, cells with cilia that constantly beat to move a layer of mucus “outward” line the entire upper airway. Inhaled bacteria, molds and particles “stick” to the mucus layer, and are then moved by beating ciliary toward the mouth. People and animals born with cilia that are defective in the proteins necessary for ciliary movement (“primary ciliary dyskinesia”) have recurrent pneumonia throughout their life as well as abnormalities in other organs. In conditions such as asthma and heaves, recurrent inflammation of the airways results in injury to cells lining the airways, including ciliated epithelial cells. It is thought that in these conditions cilia do not regenerate properly, leading to a vicious cycle of poor clearance of particles by shortened or poorly beating cilia and recurring inflammation. Viral infections of the nose and lungs have also very recently been recognized to affect the function of cilia. We will collect epithelial cells from healthy horses’ noses with a simple short medical brush, put the cells into culture and measure how well they move particles mimicking bacteria (fluorescent beads). We will compare the results from nasal samples to tracheal samples obtained with a bronchoscope and a longer medical brush. If cilia in samples from the nose function similar to those from the trachea, routine samples for assessments can be readily acquired. Once the functional assays are established we will collect samples from young and older horses with mild and severe lung inflammation (“inflammatory airway disease”, IAD, and “heaves”), respectively, to measure how cilia function in these conditions and to assess their appearance. If abnormal cilia function is a consistent feature of respiratory diseases of horses, inhaled medication to change the composition of mucus and/or to increase the production of mucus may be helpful.