Active matrix metalloproteinase-2 upregulation in the abdominal skin of patients with direct inguinal hernia

Abstract

Background: Prior studies suggest impaired collagen metabolism involving the whole abdominal wall including the skin in patients with abdominal hernia. We compared expression patterns of matrix metalloproteinase-2 (MMP-2) and its modulators membrane type-1-matrix metalloproteinase (MT-1 MMP) and tissue inhibitor of metalloproteinase-2 (TIMP-2) in the skin of patients with and without primary inguinal hernia.

Materials and methods: Skin biopsy specimens from abdominal wall incisions were obtained during surgery from patients with direct inguinal hernia, indirect inguinal hernia or without hernia (controls). MMP-2, MT-1 MMP and TIMP-2 expression were determined using immunocytochemistry and immunoblotting in intact tissue and in cultured fibroblasts isolated from the biopsies. The degradation activity of MMP-2 was semiquantitatively determined using zymography.

Results: Significantly greater active MMP-2 expression was observed in skin fibroblasts obtained from patients with direct hernia compared with controls. MT1-MMP expression was directly correlated with MMP-2 expression with most intense staining produced in patients with direct or indirect inguinal hernia. TIMP-2, was maximally expressed in the control group, with significantly diminished expression levels recorded in the hernia groups.

Conclusions: Our findings indicate active MMP-2 upregulation in the abdominal skin of patients with direct inguinal hernia. This metalloproteinase plays a role in matrix degradation, weakening the abdominal wall. Skin disorders and previously described transversalis fascia defects in these patients could point to a systemic collagen metabolism abnormality as a risk factor for direct hernia.