Elevated expression of extracellular matrix metalloproteinase inducer (CD147) and membrane-type matrix metalloproteinases in venous leg ulcers

BACKGROUND: Matrix metalloproteinases (MMPs) contribute to matrix remodelling in venous leg ulcers. Extracellular MMP inducer (EMMPRIN; CD147) has been reported to increase MMP expression, and membrane type 1 MMP (MT1-MMP) has been implicated in the activation of MMPs. OBJECTIVES: To examine whether and to what degree EMMPRIN, MMP-2, MT1-MMP and membrane type 2 MMP (MT2-MMP) are expressed in venous leg ulcers as well as the association with MMP activity. METHODS: EMMPRIN, MMP-2, MT1-MMP and MT2-MMP were analysed by zymography and immunohistochemistry in biopsies from healthy skin and lesional tissue from venous leg ulcers. RESULTS: Zymography provided direct evidence of increased proteolytic activity of MMP-2 in lesional skin in comparison with healthy controls. Immunostaining showed intense expression of EMMPRIN, MMP-2, MT1-MMP and MT2-MMP in dermal structures of venous leg ulcers, whereas only EMMPRIN and MMP-2 showed elevated expression in perivascular regions. Our findings indicate that venous leg ulcers are characterized by elevated expression of EMMPRIN, MMP-2, MT1-MMP and MT2-MMP. The immunohistological findings of skin alterations reflect the dynamic process of activation of soluble and membrane-bound MMPs, which may be highly induced by EMMPRIN. CONCLUSIONS: These data suggest for the first time that membrane-bound MMPs may favour enhanced turnover of the extracellular matrix and support unrestrained MMP activity in venous leg ulcers.