Circulating matrix metalloproteinases and their inhibitors in inguinal hernia and abdominal aortic aneurysm

There is evidence supporting the role of matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) in aortic and abdominal wall connective tissue degeneration, resulting in aneurysm and hernia formation. Furthermore, clinical association studies have demonstrated increased prevalence of abdominal wall hernias in patients with aortic aneurysms. Our objective was to estimate the levels of MMPs and TIMPs in the blood of patients with aortic aneurysm and inguinal hernia, in order to investigate whether there is potential pathogenic linkage of impaired collagen metabolism.

Plasma concentrations of MMP-9, MMP-2, TIMP-1 and TIMP-2 were quantified using ELISA in 33 male patients with abdominal aortic aneurysm and 91 male patients with inguinal hernia. They were consecutive patients undergoing repair during the study period. The same substances were measured in 35 healthy male controls.

MMP-9 and MMP-2 concentrations were lower in the plasma of patients with inguinal hernia and abdominal aortic aneurysm than controls, with hernia patients having the lowest circulating levels. The levels of TIMP-2 were significantly elevated in patients with inguinal hernia and significantly reduced in patients with aortic aneurysm, whereas opposite correlations were found for circulating TIMP-1.

Different patterns of circulating MMP and TIMP levels were found in patients with aneurysm and hernia compared with controls. Underlying pathogenic processes implicating MMPs and TIMPs in connective tissue metabolism are expressed by differing plasma levels in the two disease states. Further research including combined plasma and tissue analyses is required to further investigate potential common pathogenesis of these diseases.