Keratinocytes in human wounds express αvβ6 integrin

Cell adhesion receptors of the integrin family play a major role during re-epithelialization of human wounds. We have previously documented that the expression of αv family integrins is induced in keratinocytes of mucosal wounds. In the present investigation, we extended these studies to determine whether αvβ6 integrin is expressed during wound healing in humans. Mucosal and epidermal wound sections from 1- to 7-day-old wounds were used for immunolocalization of integrins and their putative ligands. In addition, freshly isolated epidermal keratinocytes were used to study integrin expression in vitro. Expression of αvβ6 integrin appeared relatively late during mucosal and dermal wound healing. Maximal expression was seen in 7-day-old wounds in which epithelial sheets had fused and granulation tissue was present. Fibronectin and tenascin, both possible ligands for αvβ36 integrin, were found concentrated underneath the basal epithelial cells expressing this receptor, and the maximal expression of tenascin coincided with that of αvβ6 integrin. Freshly isolated epidermal keratinocytes did not stain for αvβ6 integrin but began to express this integrin after subculturing. Our results suggest that the expression of αvβ6 integrin, a putative binding integrin for fibronectin and tenascin, is induced in keratinocytes when epithelial sheets fuse during wound healing.