Fibroblasts from the transversalis fascia of young patients with direct inguinal hernias show constitutive MMP-2 overexpression

Abstract

Objective: To determine the expression pattern of certain metalloproteinases (MMPs) known to be involved in the degradation of the extracellular matrix in cultured fibroblasts from the transversalis fascia (TF) of patients with inguinal hernia.

Summary background data: Inguinal hernia is a common pathology, the cause of which remains unknown. It is, however, clear that the TF is one of the anatomical structures that may impede the formation of hernias, and particularly the direct type of hernia. In previous studies the authors found enhanced MMP-2 expression in TF specimens in vivo. The persistence of increased expression in cultured fibroblasts might support the idea of a genetic defect as the cause for this pathology.

Methods: Fibroblasts from the TF of patients with direct and indirect inguinal hernia were cultured and compared with those obtained from control TF in terms of MMP (MMP-2 and MMP-9) expression.

Results: Significant active MMP-2 expression was shown by TF fibroblasts from young patients with direct hernias. These findings were confirmed by immunosorbent assay, immunoblotting, and zymography of the fibroblast culture media. No MMP-9 expression was detected.

Conclusion: These results indicate that MMP-2 may be involved in the TF matrix degradative process in patients with direct hernia. The persistence of changes in MMP-2 levels in the cell cultures appears to suggest a genetic defect or irreversible change as the origin of this pathology rather than environmental factors, which may later participate in the development of the hernial process.

Figure 1. MMP-2 expression by immunoblot analysis. (A) 20- to 40-year-old group. (B) 41- to 60-year-old group. Lanes 1 and 4: control; lanes 2 and 5: indirect hernia; lanes 3 and 6: direct hernia. An MMP-2 immunoreactive band was observed at approximately 110 kd. Molecular mass markers are indicated (myosin, 204 kd; β-galactosidase, 120 kd; bovine serum albumin, 80 kd).

Figure 2. MMP-2 expression by immunoblot analysis in the presence (right panel) and absence (left panel) of 2-mercaptoethanol. Molecular mass markers are indicated (myosin, 204 kd; β-galactosidase, 120 kd; bovine serum albumin, 80 kd).

Figure 3. Quantification of MMP-2 by enzyme-linked immunosorbent assay. Results are expressed in ng/mL. In both age groups, significant differences were found in the direct hernia patients compared with the other groups (* P < .05). (A) 20- to 40-year-old group. (B) 41- to 60-year-old group.

Figure 4. Gelatinolytic activity determined by gelatin zymography. (A) 20- to 40-year-old group. (B) 41- to 60-year-old group. Lanes 1 and 4: control; lanes 2 and 5: indirect hernia; lanes 3 and 6: direct hernia. A white band corresponding pro-MMP-2 was observed at approximately 68 kd.

Figure 5. Percentage of active MMP-2 levels based on gelatin zymography optical density measurements. (A) 20- to 40-year-old group: control/indirect, * P < .05; control/direct, * P < .05; indirect/direct, not significant. (B) 41- to 60-year-old group: control/indirect, not significant; control/direct, ** P < .05; indirect/direct, not significant.