The potential role for impaired mucosal integrity in the generation of esophageal pain using capsaicin in humans: an explorative study

OBJECTIVES: Esophageal pain is mediated by sensory nerves, most importantly via the activation of the Transient Receptor Potential Vanilloid 1 (TRPV1) capsaicin receptor. TRPV1 is activated and sensitized by a broad range of pungent compounds, as well as inflammatory mediators and tissue irritants. Luminal stressors are suggested to impair the barrier function, which results in consequent activation of these sensory nerve terminals and pain. Here we investigated the effect of the perfusion of capsaicin, a TRPV1 agonist, on mucosal impedance and pain in asymptomatic volunteers.

METHODS: Thirteen asymptomatic volunteers completed a single blind, saline-controlled, randomized crossover study. Capsaicin or saline was perfused for 30 min in the distal oesophagus. Visual Analogue Scale (VAS) pain intensity scores and intraluminal impedance indicating mucosal integrity were determined. Distal and proximal biopsies were obtained 10 min later to measure TRPV1 mRNA and Trpv1 immunopositivity, as well as the intercellular space area.

RESULTS: Capsaicin perfusion resulted in significantly greater pain intensity (P=0.047) and impaired recovery of the mucosal impedance compared to saline-treated controls (P=0.027). Pain response was significantly associated with decreased mucosal impedance. Similar dynamics were seen in the proximal esophagus, but mucosal impedance recovered entirely to the pre-infusion values there. There was a significant association between mucosal impedance and intercellular space width in the distal esophagus. TRPV1 transcription and expression were not significantly altered within this observation period.

DISCUSSION: Esophageal capsaicin perfusion results in pain, which is likely to be explained by impaired mucosal impedance and defective restoration capacity in the distal esophagus.