Extracellular Matrix Composition and Remodeling in Human Abdominal Aortic Aneurysms: A Proteomics Approach

Abstract

Abdominal aortic aneurysms (AAA) are characterized by pathological remodeling of the aortic extracellular matrix (ECM). However, besides the well-characterized elastolysis and collagenolysis little is known about changes in other ECM proteins. Previous proteomics studies on AAA focused on cellular changes without emphasis on the ECM. In the present study, ECM proteins and their degradation products were selectively extracted from aneurysmal and control aortas using a solubility-based subfractionation methodology and analyzed by gel-liquid chromatography-tandem MS and label-free quantitation. The proteomics analysis revealed novel changes in the ECM of AAA, including increased expression as well as degradation of collagen XII, thrombospondin 2, aortic carboxypeptidase-like protein, periostin, fibronectin and tenascin. Proteomics also confirmed the accumulation of macrophage metalloelastase (MMP-12). Incubation of control aortic tissue with recombinant MMP-12 resulted in the extensive fragmentation of these glycoproteins, most of which are novel substrates of MMP-12. In conclusion, our proteomics methodology allowed the first detailed analysis of the ECM in AAA and identified markers of pathological ECM remodeling related to MMP-12 activity. Abdominal aortic aneurysms (AAA) are characterized by pathological remodeling of the aortic extracellular matrix (ECM). However, besides the well-characterized elastolysis and collagenolysis little is known about changes in other ECM proteins. Previous proteomics studies on AAA focused on cellular changes without emphasis on the ECM. In the present study, ECM proteins and their degradation products were selectively extracted from aneurysmal and control aortas using a solubility-based subfractionation methodology and analyzed by gel-liquid chromatography-tandem MS and label-free quantitation. The proteomics analysis revealed novel changes in the ECM of AAA, including increased expression as well as degradation of collagen XII, thrombospondin 2, aortic carboxypeptidase-like protein, periostin, fibronectin and tenascin. Proteomics also confirmed the accumulation of macrophage metalloelastase (MMP-12). Incubation of control aortic tissue with recombinant MMP-12 resulted in the extensive fragmentation of these glycoproteins, most of which are novel substrates of MMP-12. In conclusion, our proteomics methodology allowed the first detailed analysis of the ECM in AAA and identified markers of pathological ECM remodeling related to MMP-12 activity. Abdominal aortic aneurysms (AAA) 1The abbreviations used are:AAAAbdominal aortic aneurysmACLPAortic carboxypeptidase-like proteinECMExtracellular matrixeSODextracellular superoxide dismutaseLTQLinear trap quadrupoleMMPMatrix metalloproteinaseTIMPTissue inhibitor of metalloproteinasesLCliquid chromatographyMS/MStandem MS. affect 2–10% of the elderly population (1Alcorn H.G. Wolfson Jr., S.K. Sutton-Tyrrell K. Kuller L.H. O'Leary D. Risk factors for abdominal aortic aneurysms in older adults enrolled in The Cardiovascular Health Study.Arterioscler. Thromb. Vasc. Biol. 1996; 16: 963-970Crossref PubMed Scopus (284) Google Scholar, 2Baumgartner I. Hirsch A.T. Abola M.T. Cacoub P.P. Poldermans D. Steg P.G. Creager M.A. Bhatt D.L. Cardiovascular risk profile and outcome of patients with abdominal aortic aneurysm in out-patients with atherothrombosis: data from the Reduction of Atherothrombosis for Continued Health (REACH) Registry.J Vasc Surg. 2008; 48: 808-814Abstract Full Text Full Text PDF PubMed Scopus (71) Google Scholar) and are histopathologically characterized by the extensive degeneration of the aortic extracellular matrix (ECM) (3Golledge J. Tsao P.S. Dalman R.L. Norman P.E. Circulating markers of abdominal aortic aneurysm presence and progression.Circulation. 2008; 118: 2382-2392Crossref PubMed Scopus (209) Google Scholar). The breakdown of structural proteins, in particular medial elastin and collagen I and III, is responsible for the inability of the