Expression of collagenase-3 (MMP-13) in human abdominal aortic aneurysms and vascular smooth muscle cells in culture

Abstract

Collagen degradation is important in the pathogenesis of abdominal aortic aneurysms (AAA) but the enzymes responsible are undefined. Collagenase-3 is a recently described matrix metalloproteinase (MMP-13) with limited tissue distribution and a highly regulated pattern of expression. Using reverse transcription-polymerase chain reaction and Southern blots, amplification products corresponding to MMP-13 were uniformly detected in samples of AAA and atherosclerotic aorta (ATH), but not in normal aortic controls. By densitometric analysis of blots normalized to beta-actin, the expression of MMP-13 was 1.8-fold higher in AAA compared to ATH (P < 0.05). Immunoreactive MMP-13 was localized to medial smooth muscle cells (SMC) in AAA tissue and to human vascular SMC in culture, which also expressed MMP-13 mRNA. These findings indicate for the first time that SMC production of MMP-13 may contribute to the pathophysiologic progression of AAA.