Investigating the Underlying Mechanisms Responsible for the Effectiveness of Behavioral Cough Suppression Therapy

UC North Ballroom

Several studies provide evidence to support that refractory chronic cough (RCC) may be related to hypersensitivity of afferent receptors expressed on C-fibers in airway epithelium. The primary known sensory receptor involved in regulation of cough sensitivity is the transient receptor potential vanilloid 1 (TRPV1). TRPV1 receptors are found in the epithelial layer of the bronchus, larynx, and nose, and are very plastic. In other words, they are easily influenced by endogenous and exogenous stimulants. Behavioral cough suppression therapy (BCST) has been shown to improve RCC symptoms in approximately 80% of patients. Several studies have shown a change in cough sensitivity following successful BCST, as evidenced by a change in capsaicin cough-challenge testing. However, the underlying mechanism that results in reduced cough sensitivity is unknown. Given that capsaicin is a known agonist of the TRPV1 receptor, and the high degree of plasticity of TRPV1 receptors, we hypothesize that the improvement seen after BCST is due to down-modulation of TRPV1 receptors through a neuroplastic mechanism. To test this hypothesis, we will use Western Blot analysis and quantitative polymerase chain reaction (qPCR) to quantify TRPV1 expression in biopsies of epithelial tissue obtained from the nose and larynx (epiglottis) of patients with RCC pre and post-BCST. An improved understanding of the mechanism responsible for the treatment effect of BCST may help to increase its application in the clinical setting as well as open doors to other potential treatments for RCC. The University of Montana Institutional Review Board has approved this study. Participant recruitment is currently underway. We anticipate having data on up to four participants by Fall Voice 2019.

Keywords: refractory chronic cough; behavioral cough suppression therapy; transient receptor potential vanilloid 1 (TRPV1)