Potential role for bone marrow-derived fibrocytes in the orbital fibroblast heterogeneity associated with thyroid-associated ophthalmopathy.

Fibroblast heterogeneity has been recognized for decades, but the basis for multiple phenotypes among these cells has been investigated only recently. More than 15 years ago, Bucalla and his colleagues described for the first time a population of fibroblast-like cells among circulating mononuclear blood cells. Subsequently these mesenchymal cells, termed fibrocytes, have been characterized and found to participate in normal and pathological tissue remodelling. In this review, I have attempted to present the evidence generated thus far suggesting that fibrocytes are participants in autoimmune diseases where tissues are injured and undergo remodelling. Aspects of their phenotype suggest that they are well suited to help orchestrate immune responses through mononuclear cell recruitment and their ability to produce inflammatory mediators and extracellular matrix molecules. These attributes also raise the possibility that they might be useful targets against which therapeutic agents might be aimed.