Fibrocytes are mesenchymal cells that arise from monocyte precursors. They are present in injured organs and have both the inflammatory features of macrophages and the tissue remodelling properties of fibroblasts. Chronic inflammatory stimuli mediate the differentiation, trafficking and accumulation of these cells in fibrosing conditions associated with autoimmunity, cardiovascular disease and asthma. This Opinion article discusses the immunological mediators controlling fibrocyte differentiation and recruitment, describes the association of fibrocytes with chronic inflammatory diseases and compares the potential roles of fibrocytes in these disorders with those of macrophages and fibroblasts. It is hoped that this information prompts new opportunities for the study of these unique cells.
Bibliographical noteFunding Information:
We wish to thank E. Tarquino for excellent help with manuscript preparation. We gratefully acknowledge funding from the following sources: the US National Institutes of Health (NIH grant UL1RR024139), the Scleroderma Foundation, the American Thoracic Society and a TRI award from Yale Department of Medicine (all to E.L.H.).