Demonstration of interstitial collagenase in abdominal aortic aneurysm disease

This study was performed to evaluate the presence of interstitial collagenase, now known as matrix metalloproteinase-1 (MMP-1), in specimens of abdominal aortic aneurysms (AAA). Eight AAA and four control infrarenal aortas were evaluated. After homogenization and extraction of soluble proteins, immunoblots of the extracts equalized for protein content were performed with a specific antibody to MMP-1. Under native conditions, immunoreactive material was distributed between M(r) 27 kDa to > 106 kDa. When the extracts were reduced and denatured, immunoreactive bands were detected in AAA at the expected M(r)'s of the secreted isoforms (57 and 52 kDa), whereas control aortic extracts had low levels of detectable immunoreactive material. Only extracts from AAA demonstrated significant immunoreactivity to the lower M(r) isoforms (22, 25, and 27 kDa), which correspond to reported cleavage products of MMP-1. Preliminary immunofluorescent studies of AAA localized MMP-1 to cells present in the adventitia of AAA. These findings will help to resolve disagreement in the recent literature regarding the presence of collagenolytic activity in AAA disease.