The fate of myofibroblasts during the development of fibrosis in Crohn's disease

Intestinal fibrosis is a devastating complication in patients with inflammatory bowel disease. Its characteristics include the loss of regular peristalsis and nutrition absorption, excessive deposition of extracellular matrix (ECM) components, thickness of intestinal lumen due to the formation of strictures and of scar tissue. As a major cell type involved in fibrogenesis, the myofibroblasts have already been shown to have a plastic and heterogeneous function in producing abundant collagen, fibronectin and connective tissue growth factor. The primary sources of ECM-producing and vimentin-positive myofibroblasts come from different precursor cells, including bone marrow-derived mesenchymal cells, fibrocytes, pericytes, epithelial to mesenchymal transition and endothelial to mesenchymal transition. Recent immunological research findings suggest that numerous cytokines and chemokines made from macrophages, in addition to T cells and other myeloid cell types, are also important drivers of myofibroblast differentiation and hence of the activation of myofibroblast-mediated transforming growth factor and collagen production. In this review we discuss the origins, roles and cell signaling of myofibroblasts during the development of fibrosis in different organs, particularly in Crohn's disease. Finally, we suggest that the epigenetic and immunological regulation of myofibroblast differentiation may provide a novel antifibrotic strategy in the near future.