A Study On Collagen Constitute And Affected Factors In Hypertrophic Of Different Age Periods

Background: Hypertrophic scarring (HTS) following burn injury is a common, disfiguring, and functionally limiting form of dermal fibrosis. Clinically, it is characterized by excessive dermal fibrosis and scarring resulting from the imbalance between collagen synthesis and degradation during wound healing. Incidence of scarring is related to age factor. This kind of phenomenon is maybe caused by many factors of collagen synthesis and degradation. Its pathogenesis is not well understood. Objective: To investigate the distinction of ratio of collagen in hypertrophic and its causes in different age period, so as to provide a theoretical base for clinical special treatment of scar. Method: ① The expression of type I and type III collagen were measured with Immunohistochemistry in different age hypertrophic and normal skin. The quantities of type I and type III collagen and the ratios were analyzed. ② The expression of Cytokine TGF-β1 was measured with Immunohistochemistry in hypertrophic and normal skin. ③ mRNA expressions of collagenase (MMP-1) and tissue inhibitor of metalloproteinase (TIMP-1) were measured with in situ hybridization technique. Results: ①The ration of type I/type III collagen in HTS was increased compared with normal skin(NS), and relative quantification of type I collagen in HTS was significantly increased. The ration of type I/type III collagen in HTS group of 1-19 year old was increased compared with the group of 20-50 year old. The ration of type I/type III collagen in normal skin had an guadually increased tendency. ② The expression of TGF-β1 protein in HTS was enhanced. The expression of TGF-β1 in HTS group of 1-19 year old significantly increased more than the group of 20-50 year old. ③ Significant increase in expression of TIMP-1 mRNA in HTS was observed, but the expression of MMP-1 was lower both in HTS and in NS. The expression of TIMP-1 mRNA in HTS is 7.8 timer than MMP-1. The expression of TIMP-1 mRNA and the expression of MMp-1 in HTS group of 1-19 year old and the group of 20-50 year old had no different. Conclusion: ①Significantly increased TGF-β1 that stimulates fibroblast synthesizing more type I collagen and enhance the ration of type I/type III collagen may be a cause of higher Incidence of scarring in the period of 1-19 year old(period child and teenager ). ②Higher expression of TIMP-1 mRNA and lower expression of MMP-1 mRNA is the one of Factors causing HTS. Expressions of TIMP-1 and MMP-1 have no directly relationship with age. ③Collagen synthesis and regulation of its constitute are finished during a definite period. They keep relatively steady state within 6 month to 2-3 years.