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Alteration of Integrin Expression in Migrating Epidermal Cells and Fibronectin Distribution in the Dermis with Pressure Ulcers

Failure of re‐epithelialization characterizes the pathophysiology of chronic wounds. However, the mechanism of this failure has not been fully clarified. During the re‐epithelialization of acute wounds, migrating epidermal cells up‐regulate integrins α5β1, αvβ5, αvβ6 and these integrins play an important role in the re‐epithelialization process. Laminin‐1 is a basement membrane component which appears during the late phase of the re‐epithelialization process. In this study, with 6 specimens from burn patients (acute wounds, control) and 11 specimens from patients with pressure ulcers, we examined the expression of α5β1 in the migrating epidermis, laminin‐1 at the dermal‐epidermal junction and fibronectin in the dermis by an immunohistochemical method. We then compared the findings for α5β1 with histological, laminin‐1 and fibronectin distribution findings. In 8 out of the 11 pressure ulcer specimens, the expression of α5β1 significantly decreased or was negative while it increased in the control. The degree of expression correlated well with histological findings of epidermal elongation over the wound bed. Moreover, fibronectin distribution in all the pressure ulcer specimens decreased considerably while it increased in three out of the six burn specimens. A statistically significant correlation was found between the distance at which the cells were positively stained for α5β1 and the distance at which they were negatively stained for laminin‐1 in both the burn (control) and pressure ulcer specimens. Our data demonstrated that the decrease in α5β1 expression correlated with the failure in re‐epithelialization of chronic wounds (pressure ulcers). It was also suggested that the decrease in fibronectin distribution was responsible for the failure of the re‐epithelialization process.