Re-epithelialization of normal human excisional wounds is associated with a switch from alpha v beta 5 to alpha v beta 6 integrins

Abstract

During cutaneous wound repair, keratinocytes move laterally across the wound surface. For this lateral movement epidermal cells must disassemble their tenacious connections to the basement membrane and their neighbouring cells, and express surface receptors that permit translocation over the wound surface extracellular matrix. If the basement membrane is disrupted, the epidermis migrates over a provisional matrix that contains fibrinogen, fibronectin, vitronectin and tenascin. Although alpha 5 beta 1 integrin, a fibronectin receptor, is expressed by human epidermis during re-epithelialization of excisional and incisional wounds, the spatial and temporal patterns of vitronectin, tenascin, and other fibronectin receptors are less clear. Other potential receptors include alpha v beta 5 for vitronectin and alpha v beta 6 for fibronectin and tenascin. To study provisional matrix integrin expression during human wound healing, full-thickness 4-mm punch biopsies were performed on the inner surface of the upper arm in adult volunteers. At 3, 7 and 14 days after injury wound sites were excised, bisected, quick frozen in liquid nitrogen, and examined for the expression of alpha 5, beta 1, alpha v, beta 5 and beta 6. At 3 days, alpha 5 beta 1 and alpha v beta 5, but not alpha v beta 6, appeared around the basal and suprabasalar cells of the migrating epidermis. At 7 days, alpha 5 beta 1, alpha v beta 5, and alpha v beta 6 appeared around the perimeter of the basal cells of the migrating epidermis. By 14 days, when re-epithelialization was complete, all basal and suprabasalar cells overlying the wound expressed alpha 5 beta 1 and alpha v beta 6, but not alpha v beta 5. Thus, alpha v appeared to switch its heterodimeric association from beta 5 to beta 6 subunit during re-epithelialization.