Systemic sclerosis is a fibrotic autoimmune disease in which aberrant remodeling of the extracellular matrix in organs disturbs their functionalities. The aim of this study was to investigate the expression of gelatinases on systemic sclerosis. Consequently, a mouse model of systemic sclerosis was employed and the gelatinolytic activity of gelatinases was evaluated on the fibrotic tissues of this model. Two groups of ten mice were considered in this work: a group of systemic sclerosis model and

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... control group. For the generation of systemic sclerosis model, mice received bleomycin, while the control group was subjected to phosphate buffered saline (PBS) reception. Mice were tested for fibrosis by using trichrome staining, hydroxyproline measurement and α-SMA detection in tissue sections. Additionally, the gelatinolytic activity of matrix metalloproteinase 2 and matrix metalloproteinase 9 were measured using gelatin zymography in lungs and skin tissue homogenates. The obtained results indicated that subcutaneous injection of bleomycin-induced fibrosis in skin and lung tissues of mice. Pro and active forms of matrix methaloproteinase 9 were increased in fibrotic lung tissues (p<0.05 and p<0.01, respectively), while, the gelatinolytic activity of MMP2 was unaffected in these tissues. Additionally, in skin tissues of bleomycin-treated animals, both pro and active forms of MMP9 and MMP2 were increased (p<0.05). Pro and active forms of gelatinases increase differently in skin and lung tissues of bleomycin-induced scleroderma.