Mycobacterium avium paratuberculosis invades human small-intestinal goblet cells and elicits inflammation.

Crohn disease is a chronic inflammatory bowel disease of unknown etiology. Mycobacterium avium paratuberculosis (MAP) was found in the gut of patients with Crohn disease, but causality was not established. Fully developed, germ-free human small intestine and colon were established by subcutaneous transplantation of fetal gut into SCID (severe combined immunodeficiency) mice thereafter infected by direct intraluminal inoculation of MAP. We have found that MAP actively invades the human gut epithelial goblet cells of the small intestine, inducing severe tissue damage and inflammation. These observations indicate that MAP can specifically colonize the normal human small intestine and can elicit inflammation and severe mucosal damage.