Synthesis of type I and III collagen, expression of fibronectin and matrix metalloproteinases-1 and -13 in hernial sac of patients with inguinal hernia

Since many years the importance of a weakness of the soft tissue for the development of hernias is discussed controversially. The tensile strength of the tissue is supposed to depend largely on the varying proportion of type I collagen with its high tensile strength and the immature type III collagen. Their relation is regulated by several collagenases, mainly matrix metalloproteinases-1 and -13 (MMP-1 and MMP-13), whereas fibronectin plays a key role for the adherence of cells within the extracellular matrix. The aim of this study was to investigate whether an alteration in type I and type III collagen synthesis, amounts of MMP-1 and MMP-13 and the expression of fibronectin were associated with the development of inguinal hernia. We analysed the hernial sac of patients with indirect (n = 9) and direct (n = 7) inguinal hernias and peritoneum in controls (n = 7) by immunohistochemistry and Western blot analysis. The results showed that the ratio of relative amount of I/III collagen was markedly decreased in patients with either indirect or direct hernias as compared with controls (p < 0.001) with a concomitant increase in type III collagen synthesis. MMP-13 was expressed neither in the hernial sac nor in the peritoneum of the controls, but the positive reactions of MMP-1 were found in the surface of the subserosa of the hernial sac in patients with indirect or direct hernias without any difference compared to controls. Furthermore, the relative amount of fibronectin in patients with either indirect or direct hernias is not significantly different from controls (p > 0.05). In regard to the known alterations of the collagen metabolism in fascia and skin of hernia patients the changed collagen I/III ratio with its increase of type III collagen in hernial sacs support the presence of a systemic disturbance of collagen metabolism. The absence of changes of the expression of collagenases (MMP-1, MMP-13) and the constant levels of fibronectin underline the central role of collagen synthesis for the development of indirect or direct hernias.