Fig. 1: Schematic overview of the study design and procedures.

At baseline, healthy controls and patients with functional dyspepsia (FD) underwent clinical study procedures including symptom evaluation, collection of peripheral blood and feces. Duodenal biopsies were collected during gastroduodenoscopy. FD patients were followed-up after high-dose proton pump inhibitor therapy (PPI) and clinical procedures were repeated. Created with BioRender.com.