Expression And Significance Of α₅β₁ Integrin And Fibronectin (FN) In Abnormal Scars

Objective: To study the expression of α5β1 integrin and FN in different stages abnormal scar and to investigate the role and significance of α5β1 integrin and FN in the formation and development of abnormal scars.Methods: Expression of α5β1 integrin and FN was observed in samples of 25 hypertrophic scars (HS), 25 keloids (K) and 10 normal skins(NS) with SP immunohistochemical method. The results were semi-quantified with histological scoring. Employing colloidal gold immuno-electron microscopic technique, we observed the expression and distribution of α5β1 integrin in fibroblasts(FBs) in middle layer of dermis of HS, K of different stages and NS as well as the ultrastructure of FBs.Results: ① The expression levels of α5β1 integrin and FN in FBs of abnormal scars were higher than those of NS and the expression ofα5β1 integrin and FN in FBs of K was increased in comparison with that of HS(P＜0.01). With the increase of duration of scaring, the expression of α5β1 integrin and FN in FBs of HS decreased but such a change was not observed in FBs of K. In scars of less than 6 months and 6 to 12months ,the expression of α5β1 integrin in FBs showed no statistical difference between HS and K(P＞0.05).However,the expression of α5β1 integrin in FBs of K was increased compared to that of HS in the scars of 13 to 24 months and over 24months duration (P＜0.01). Except the expression of FN on FBs showed no statistical difference between HS and K in the scars of 13 to 24 months duration(P＞0.05), the changes in expression of FN were similar to those of α5β1 integrin. ② The immuno-electron microscopic observation revealed that the expression of α5β1 integrin in FBs of abnormal scars was stronger than that of NS, plenty of colloidal gold granules accumulated on the surface of FBs with a tendency to form cluster in abnormal scars under 6 months duration and the endoplasmic reticulum was plentiful. The colloidal gold granules and the number of endoplasmic reticulm decreased in FBs of HS over 24 months duration. However, the change was not found in FBs of K over 24 months duration.Conclusions: ① α5β1 integrin and its ligand FN appear to be closely associated with the formation and development of abnormal scars. ② The expression of α5β1 integrin and FN in FBs of K lasting longer duration may account for the overabundant collagen accumulation in K. ③To find the way to decrease the expression level of α5β1 integrin in FBs may be a new approach to inhibit the hypertrophy of abnormal scars and to soften scars.