The Role of Airway Surface Liquid in the Primary Management of Rhinosinusitis

Abstract

Airway surface liquid forms part of the innate defence mechanism of the respiratory system, including the nasal and paranasal sinuses. Successful mucociliary clearance, which lies at the centre of this defence mechanism, involves the synchronized function of two structures, namely, the periciliary liquid layer and the mucus layer. The two structures have collectively been termed the 'two phase airway surface liquid' system. This system is kept hydrated through regulation of sodium and chloride transport. A well hydrated airway surface liquid that allows the periciliary liquid layer to extend over the height of the outstretched cilia keeping mucus away from the epithelia is considered to be essential for effective mucus clearance and sinonasal health. This mechanism assists in trapping and eliminating foreign particles and, together with antimicrobial peptides, maintains a sterile environment in the nasal and paranasal sinuses, which are continually exposed to microorganisms in the external environment. In diseases such as rhinosinusitis, the mucociliary clearance capacity is diminished; the first line of defence is disrupted allowing for bacterial invasion and infection. This manuscript explores the prospect of an alternative approach for the prophylaxis and primary management of rhinosinusitis based on the maintenance of a well hydrated airway surface liquid.