Gene expression of tenascin is altered in normal scars and keloids

Tenascin is an extracellular matrix molecule with structural similarity to fibronectin. An increase in extracellular matrix content of both tenascin and fibronectin is associated with early wound healing and with various skin fibroses. However, the relationship of tenascin and fibronectin expression during scar remodeling and the formation of pathologic scars such as keloids is unknown. Expression of tenascin in normal and abnormal human scars was examined and compared with that of fibronectin by immunohistochemistry and in situ hybridization. Tenascin and fibronectin protein and messenger RNA contents were elevated in normal, mature scars relative to quiescent skin, similar to the situation during earlier stages of healing. Tenascin and fibronectin expression was further enhanced in keloids relative to normal skin and scar, and, as has been shown for fibronectin, tenascin expression in uninjured skin adjacent to keloids was indistinguishable from that in quiescent skin from unaffected individuals. These data suggest that tenascin and fibronectin gene expression are coordinated during later stages of normal wound healing and that a defect involving common regulatory elements for these genes is associated with the formation of keloids.