Association of Matrix Metalloproteinase Levels with Collagen Degradation in the Context of Abdominal Aortic Aneurysm

Objective/Background Matrix metalloproteinases (MMPs) have already been identified as key players in the pathogenesis of abdominal aortic aneurysm (AAA). However, the current data remain inconclusive. In this study, the expression of MMPs at mRNA and protein levels were investigated in relation to the degradation of collagen I and collagen III. Methods Tissue samples were obtained from 40 patients with AAA undergoing open aortic repair, and from five healthy controls during kidney transplantation. Expression of MMPs 1, 2, 3, 7, 8, 9, and 12, and tissue inhibitor of metalloproteinase (TIMP)1, and TIMP2 were measured at the mRNA level using quantitative reverse transcription polymerase chain reaction. At the protein level, MMPs, collagen I, and collagen III, and their degradation products carboxy-terminal collagen cross-links (CTX)-I and CTX-III, were quantified via enzyme linked immunosorbent assay. In addition, immunohistochemistry and gelatine zymography were performed. Results In AAA, significantly enhanced mRNA expression was observed for MMPs 3, 9, and 12 compared with controls ( p ≤ .001). MMPs 3, 9, and 12 correlated significantly with macrophages ( p = .007, p = .018, and p = .015, respectively), and synthetic smooth muscle cells with MMPs 1, 2, and 9 ( p = .020, p = .018, and p = .027, respectively). At the protein level, MMPs 8, 9, and 12 were significantly elevated in AAA ( p = .006, p = .0004, and p