The Role of Mast Cells on Duodenal Permeability After Duodenal Acid Perfusion in Healthy Volunteers

Despite intensive research, the pathophysiology of functional dyspepsia remains unknown. The investigators recently demonstrated that functional dyspepsia patients display impaired duodenal mucosal integrity and low-grade mucosal inflammation. As studies have also shown that functional dyspepsia patients present with an increased spontaneous duodenal acid exposure, the hypothesis of this study is that increased duodenal acid exposure results in increased duodenal permeability via mast cell activation. This will also induce activation of the duodenogastric reflex, resulting in gastric relaxation, eventually leading to the generation of dyspeptic symptoms. The general aim of this project is to assess the effect of mast cell inhibition on duodenal mucosal integrity and intragastric pressure of healthy volunteers after acid infusion in the duodenum.

The study will be a randomized, double-blind, cross-over study in 20 healthy volunteers and consists of 2 parts. (1) In the first part, 10 healthy volunteers will be perfused with acid (0.1N HCl) or 0.9% saline during 30 minutes at a rate of 5 mL/min with an interval of at least one month. During acid/saline perfusion, intragastric pressure will be measured with a high resolution manometry system to evaluate activation of the duodenogastric reflex. Dyspeptic symptoms will be scored 1 minute before and every 5 minutes during the infusion. After perfusion, endoscopy will be performed and duodenal biopsies will be obtained to evaluate mucosal integrity using Ussing chambers and by assessing the expression of cell-to-cell adhesion proteins (real-time PCR, immunofluorescence and western blot). (2) In the second part, 10 healthy volunteers will be perfused with acid after a placebo treatment and after treatment with the mast cell stabilizer disodium cromoglycate 100mg 4x2/day (with an interval of at least one month). The rest of the study continues as described in part 1.