Genetic Determinism of Epithelial Barrier Defects in Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is the first reason for consultation in gastroenterology and his prevalence reach 5% of the general population. IBS is characterized by abdominal discomfort, diarrhea or constipation and decreased quality of life. Recent facts on IBS pathophysiology show association between mucosal immunity activation (mast cells and their proteases) and epithelial permeability disorder. Permeability disorder can be reproduced by application of colonic biopsies cultures supernatants on in-vitro cell cultures. In parallel, tight junctions proteins mRNA (ZO-1, Occludin) decrease is observed ex-vivo in biopsies and in-vitro. Gut bacterial proteases (cystein and serin proteases) may also play a role. In human, proteases activity is correlated with IBS symptoms severity. Proteases activity increase (cystein and serin proteases) is poorly understood, and this increase could be subjected to a genetic determinism (decrease in proteases inhibitors genes expression - Serpin A1/E1). Objectives: 1/ To study relations between proteases activity (in stool and colonic biopsies supernatants), proteases inhibitors genes expression and mucosal cellular infiltrate (IBS patients and healthy subjects). 2/ Establishing a correlation between proteases activity, mucosal micro-inflammation and symptoms. 3/ To evaluate proteases inhibitors therapeutic potential. Method: Subjects will be recruited in gastroenterology consultation. IBS patients will answer to Rome III criteria. Patients coming for screening colonoscopy will be defined as healthy subjects. Colonic biopsies will be sent in real time to the research laboratory (EA 6302) for supernatants collecting, mRNA expression studies (Serpins, ZO-1, occludin, cytokines), proteases activity / permeability measurements and proteases inhibitors reversibility tests. Histologic study will also be performed. Expected results: 1/ Decreased expression of proteases inhibitors genes in subjects with IBS. 2/ Correlation of symptoms with proteases activity intensity. 3/ Demonstration of restorative potential of proteases inhibitors.