| Background:Pathological scar, including hyperplastic scar and keloid, was widely formed after the operation, trauma and burns. Compared with the normal skin, the proliferation and activity of fibroblast were enhanced in hyperplastic scar and keloid, and then large amounts of collagen were produced and causing Ⅰ/Ⅲ collagen deposition in tissues. As a member of neurotrophin family, nerve growth factor (NGF) could promote the proliferation of scar fibroblasts, and it was mainly in form of a precursor in the body. In recent years, people gradually realize that proNGF is an important apoptosis factor, which is widely distributed in the nervous system and the other tissues. In order to known whether NGF and proNGF associated with hyperplastic scar, this study observed the expression of NGF and proNGF in pathological scar and normal skin by immunohistochemistry and Western blot method.Objective:To observe the expression of NGF and proNGF in pathological scars and normal skin, and explore its role and significance in the process of pathological scar formation.Methods:23cases of hyperplastic scar and20cases of keloid (pathological scar groups) and20cases of normal skin (control group) were collected, made serial sections for HE staining, morphological differences were observed under the microscope. Immunohistochemical techniques were used to detect the expression of NGF and proNGF in hyperplastic scars, keloids and normal skin. Western blot detected the differences in protein expression.Results:Compared with normal skin, the basal layer and prickle cell layer of the epidermis were thick in the hyperplastic scar. Cell arranged loosely and disordered, some may have dermal tissue embedding. Dermal papilla was less, low and flat and reticular layer was thick. The collagen fiber was hyperplasia, partly hyaline degeneration. There were a lot of fibroblasts, and cell volume was large and rich in cytoplasm. Epidermis is atrophy in keloid, epidermal cells arranged loosely, embedded dermal tissue. Dermal papilla was less, and reticular layer was thick and dense, collagen nodules could be formed. There were a large amount of fibroblasts which cell volume was large and rich in cytoplasm.Expressions of NGF were positive in the three tissue types. In hyperplastic scar and keliod, it was mainly expressed in the basal layer of the epidermis and fibroblasts; and in normal skin it was located in the basal layer of the epidermis and skin appendages. Through immunohistochemistry, we found the NGF expressions in normal skin were significantly lower than that in hyperplastic scar(t=27.54, P<0.01) and keloid(t=26.82, P<0.01). Western blot showed the protein expressions of NGF in normal skin were significantly lower than that in hyperplastic scar(t=16.22, P<0.01) and keloid(t=15.19, P<0.01).Expressions of proNGF were all found positive in the three tissue types, mainly at epidermal cells and fibroblasts. Through immunohistochemistry, we found the proNGF expressions in normal skin were significantly higher than that in hyperplastic scar(x2=8.23, P<0.05) and keloid(x2=8.29, P<0.05). Western blot showed the protein expressions of proNGF in normal skin were significantly higher than that in hyperplastic scar(t=14.02, P<0.01)and keloid(t=20.80,P<0.01). Conclusions:NGF and proNGF were positive expressed in normal skin, hyperplastic scar and keloid, its expression mainly located in the basal layer of the epidermis and fibroblasts. The expression of NGF in hyperplastic scar and keloid was significantly higher than that in normal skin, and the expression of proNGF in hyperplastic scar and keloid is significantly lower than that of normal skin, no significant difference was found between the two factor expressions in hyperplastic scar and keloid. It suggests that NGF and proNGF are closely related to tissue hyperplasia, the protein levels of NGF/proNGF may be related to pathological scars, and play a role in the development of scar. |
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