Abstract

Background: Excessive activation of afferent nerves in the esophagus is assumedly a major mechanisms of cough associated with GER, which may lead to sensitization of cough reflex. Transient receptor potential (TRP) channels have an important role for converting external stimuli into biological response. We reported an increased gene expression of TRPV1 and TRPV4 in the esophagus of GER patients with cough ERS 2019. However, association between protein expression of these channels in the esophagus and GER-associated cough is still unknown.

Method: We prospectively recruited untreated GER patients with (n=32, C+) and without (n=5, C-) cough. Esophageal endoscopy was performed to determine the presence and severity of reflux esophagitis (RE), and to obtain biopsy specimens, which were examined for TRPV1 and TRPV4 protein expression by western blot analysis.

Result: Age, sex distribution, smoking history, prevalence/severity of RE, and GER symptom scores did not differ between the C+ and C- groups. TRPV4 expression was significantly increased in the C+ group than in the C- group (p < 0.0001), but TRPV1 expression was similar in the two groups. The expressions of both receptors were unrelated to the presence/severity of RE or GER symptom scores.

Conclusions: Cough in GER patients is associated with the increased expression of TRPV4 in the esophagus but not with RE or reflux symptoms. Further studies are needed to elucidate the pathogenesis and precise roles of the increased TRPV4.