Presence of commensal house dust mite allergen in human gastrointestinal tract: a potential contributor to intestinal barrier dysfunction

BackgroundAbnormal gut barrier function is the basis of gut inflammatory disease. It is known that house dust mite (HDM) aero-allergens induce inflammation in respiratory mucosa. We have recently reported allergen from Dermatophagoides pteronyssinus (Der p1) to be present in rodent gut.ObjectiveTo examine whether Der p1 is present in human gut and to assess its effect on gut barrier function and inflammation.DesignColonic biopsies, gut fluid, serum and stool were collected from healthy adults during endoscopy. Der p1 was measured by ELISA. Effect of HDM was assessed on gut permeability, tight-junction and mucin expression, and cytokine production, in presence or absence of cysteine protease inhibitors or serine protease inhibitors. In vivo effect of HDM was examined in mice given oral HDM or protease-neutralised HDM. Role of HDM in low-grade inflammation was studied in patients with IBS.ResultsHDM Der p1 was detected in the human gut. In colonic biopsies from healthy patients, HDM increased epithelial permeability (p