title: Involvement of MMPs in the outward remodeling of collateral mesenteric arteries.
abstract: Persistent elevation in shear stress within conduit or resistance arteries causes structural luminal expansion, which serves to normalize shear stress while maintaining increased flow to the downstream vasculature. Although it is known that this adaptation involves cellular proliferation and remodeling of the extracellular matrix, the specific cellular events underlying these responses are poorly understood. Matrix metalloproteinases (MMPs) contribute to extensive remodeling of the extracellular matrix in conduit vessels and vein grafts exposed to high flow. However, involvement of MMPs in remodeling of small muscular collateral arteries, which are exposed to less severe increases in shear stress, has not been tested. We utilized an established model of outward remodeling in mesenteric collateral arteries to determine whether MMPs were upregulated during the remodeling response and to test whether MMP activity was required for luminal expansion. By 4 days, MMP-2 and membrane type 1 MMP (MT1-MMP), but not MMP-9, protein levels were significantly elevated in collateral arteries, as assessed by gelatin zymography and immunostaining. MMP-2 and MT1-MMP proteins, together with their respective transcriptional activators c-Jun and Egr-1 were localized predominantly to the smooth muscle layer of the collateral arteries. The general MMP inhibitor doxycycline prevented luminal expansion of collateral arteries but did not affect the endothelial cell proliferative or medial growth responses. In conclusion, this study provides evidence that MMP-2 and MT1-MMP are upregulated in collateral arteries exposed to elevated shear stress and that MMP activity is essential for the full remodeling response that leads to outward luminal expansion.
authors.affiliation: School of Kinesiology and Health Sciences, Rm. 341 Farquharson, York Univ., 4700 Keele St., Toronto, ON Canada M3J 1P3. thaas@yorku.ca
authors.forename: Tara L
authors.initials: TL
authors.lastname: Haas
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Doyle
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Distasi
authors.forename: Laura E
authors.initials: LE
authors.lastname: Norton
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Sheridan
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Unthank
mesh_terms: D000818:Animals; D001158:Arteries / Q000601:surgery; D049109:Cell Proliferation; D003097:Collateral Circulation; D004318:Doxycycline / Q000494:pharmacology; D051766:Early Growth Response Protein 1 / Q000378:metabolism; D004789:Enzyme Activation; D005109:Extracellular Matrix / Q000378:metabolism*; D007082:Ileum / Q000098:blood supply*; D008026:Ligation; D008297:Male; D053511:Matrix Metalloproteinase 14 / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D020782:Matrix Metalloproteinases / Q000378:metabolism*; D008638:Mesenteric Arteries / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D023421:Models, Animal; D011480:Protease Inhibitors / Q000494:pharmacology; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013152:Splanchnic Circulation; D013314:Stress, Mechanical; D013997:Time Factors; D017539:Tunica Intima / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D015854:Up-Regulation
chemical_list: D051766:Early Growth Response Protein 1; C486110:Egr1 protein, rat; D011480:Protease Inhibitors; D016755:Proto-Oncogene Proteins c-jun; D020782:Matrix Metalloproteinases; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D053511:Matrix Metalloproteinase 14; D004318:Doxycycline