Role of epithelial-to-mesenchymal transition in inflammatory bowel disease.

Intestinal fibrosis is an inevitable complication in patients with inflammatory bowel disease (IBD), occurring in its two major clinical manifestations: ulcerative colitis and Crohn's disease. Fibrosis represents the final outcome of the host reaction to persistent inflammation which triggers a prolonged wound healing response resulting in the excessive deposition of extracellular matrix, eventually leading to intestinal dysfunction. The process of epithelial-to-mesenchymal transition (EMT) represents an embryonic program relaunched during wound healing, fibrosis and cancer. Here we discuss the initial observations and the most recent findings highlighting the role of EMT in inflammatory bowel disease-associated intestinal fibrosis and fistulae formation. In addition, we briefly review the knowledge acquired on the cognate process of endothelial-to-mesenchymal transition (EndMT). Understanding EMT functionality and the molecular mechanisms underlying the activation of this mesenchymal program will permit designing new therapeutic strategies to halt the fibrogenic response in the intestine.