Matrix metalloproteinases and tissue inhibitors of metalloproteinases in patients with different types of scars and keloids.

BACKGROUND: Hypertrophic scars and keloids are fibroproliferative skin disorders characterised by progressive deposition of collagen. Our study is designed to investigate the expression and concentration of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in different types of scars and keloids.

METHODS: Total RNA from 19 proliferative hypertrophic scar samples of patients with extended burns (total body surface area (TBSA): 21+/-12%), 18 mature hypertrophic scar samples from patients after elective surgery, 14 keloid samples and 18 normotrophic scar samples was, respectively, extracted, and then mRNA was isolated. Besides, biopsies were obtained from non-scarred skin of the patients and extraction of total RNA performed. Relative mRNA expression of MMP 2, MMP 9, TIMP 1 and TIMP 2 was measured with reverse transcriptase polymerase chain reaction (RT-PCR). Serum concentrations of MMP-1, -2, -9, TIMP-1, and -2 were determined using an enzyme-linked immunosorbent assay (ELISA).

RESULTS: Patients with extended hypertrophic scars after burn trauma presented a significantly higher TIMP-1 concentration (p<0.05) in their sera than the other patients. The relative expression of MMP 2 was significantly higher in samples of proliferative hypertrophic scars after burn injury. The relative expression of TIMP 1 and TIMP 2 was significantly higher in scar tissue of patients with proliferative and mature hypertrophic scars and keloids than in their regular skin and in scar samples of patients with normotrophic scars. The expression of TIMP 1 was significantly higher in samples of patients with keloids than in patients with hypertrophic scars.

CONCLUSIONS: The concentration of TIMP-1 in sera of patients varies depending on the size of the involved fibrotic scar tissue. A decrease in MMP-to-TIMP expression in scar tissue may contribute to increased synthesis and deposition of collagen, leading to a severe fibrotic reaction with pathologic scar formation. The results implicate non-operative therapy options in these patients that not only down-regulate TIMPs but also increase the activity of MMPs.