(218f) Viscoelastic Response of Mucus on Live Epithelial Cell Cultures

Mucus that lines the eyes, airway, and intestines acts as the primary defense against foreign particles and infectious agents by trapping the invaders and preventing them from penetrating the cell layer. Effective mucus clearance, and thus removal of the trapped invaders, is vital for healthy immune function. In cases of disease, such as asthma and cystic fibrosis, mucus properties can change to become more solid-like, resulting in impaired mucus transport. While increased solids concentration of mucus has been associated with the inhibition of mucociliary clearance in the lungs, the mechanism of mucus transport impairment remains unclear. Thus far it has not been feasible to directly measure mucus properties on live cells as it is produced by the epithelial cell layer, neglecting the relationship between the physiological environment and mucus rheology. A new instrument, the “Magnetic Live Cell Rheometer”, recently developed by the Fuller group has been adapted to examine mucus rheology in situ via magnetic microrheology. Human epithelial cells (HECs) are grown in air-liquid interface (ALI) cultures, mimicking the epithelial surface environment. During rheological experiments, we maintain cells at ALI and use micron scale magnetic wires (microwires) to probe the properties of the mucus layer. We apply and remove a magnetic force and track microwire displacement to determine the compliance and viscosity of healthy and pathologic mucus on the respective HEC cultures. We then use dithiothreitol (DTT)to break down mucin disulfide bond crosslinks to examine the role of this crosslinking in determining mucus elasticity and viscosity. With this method, we demonstrate the ability to study mucus rheology in a physiologically relevant environment, examine phenotypic differences in mucus rheology, and rapidly test drugs on mucociliary mechanics.