title: Membrane-type 1 matrix metalloproteinase regulates macrophage-dependent elastolytic activity and aneurysm formation in vivo.
abstract: During arterial aneurysm formation, levels of the membrane-anchored matrix metalloproteinase, MT1-MMP, are elevated dramatically. Although MT1-MMP is expressed predominately by infiltrating macrophages, the roles played by the proteinase in abdominal aortic aneurysm (AAA) formation in vivo remain undefined. Using a newly developed chimeric mouse model of AAA, we now demonstrate that macrophage-derived MT1-MMP plays a dominant role in disease progression. In wild-type mice transplanted with MT1-MMP-null marrow, aneurysm formation induced by the application of CaCl2 to the aortic surface was almost completely ablated. Macrophage infiltration into the aortic media was unaffected by MT1-MMP deletion, and AAA formation could be reconstituted when MT1-MMP+/+ macrophages, but not MT1-MMP+/+ lymphocytes, were infused into MT1-MMP-null marrow recipients. In vitro studies using macrophages isolated from either WT/MT1-MMP-/- chimeric mice, MMP-2-null mice, or MMP-9-null mice demonstrate that MT1-MMP alone plays a dominant role in macrophage-mediated elastolysis. These studies demonstrate that destruction of the elastin fiber network during AAA formation is dependent on macrophage-derived MT1-MMP, which unexpectedly serves as a direct-acting regulator of macrophage proteolytic activity.
authors.affiliation: Department of Surgery, University of Nebraska Medical Center, Omaha, Nebraska, 68198, USA. wxiong@unmc.edu
authors.forename: Wanfen
authors.initials: W
authors.lastname: Xiong
authors.forename: Rebecca
authors.initials: R
authors.lastname: Knispel
authors.forename: Jason
authors.initials: J
authors.lastname: MacTaggart
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Greiner
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Weiss
authors.forename: B Timothy
authors.initials: BT
authors.lastname: Baxter
mesh_terms: D000818:Animals; D001011:Aorta / Q000378:metabolism / Q000473:pathology; D017544:Aortic Aneurysm, Abdominal / Q000139:chemically induced / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D002122:Calcium Chloride / Q000633:toxicity; D004195:Disease Models, Animal; D004549:Elastin / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008264:Macrophages / Q000201:enzymology* / Q000473:pathology; D053509:Matrix Metalloproteinase 13 / Q000235:genetics / Q000378:metabolism*; D020778:Matrix Metalloproteinase 2 / Q000235:genetics / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout
chemical_list: D004549:Elastin; D053509:Matrix Metalloproteinase 13; C507081:Mmp13 protein, mouse; D020778:Matrix Metalloproteinase 2; C522362:Mmp2 protein, mouse; D020780:Matrix Metalloproteinase 9; C501830:Mmp9 protein, mouse; D002122:Calcium Chloride