title: Urokinase plasminogen activator independent early experimental thrombus resolution: MMP2 as an alternative mechanism.
abstract: Deep-vein thrombosis (DVT) resolution is thought to be primarily a urokinase plasminogen activator (uPA) -dependent mechanism, although observations suggest other non-fibrinolytic mechanisms may exist. We explored the role of matrix metalloproteinase (MMP) -2 and -9 in early DVT resolution in uPA-deficient mice. Male B6/SVEV (WT) and genetically matched uPA -/- mice underwent inferior vena cava (IVC) ligation to create stasis venous thrombi, with IVC and thrombus harvest. Thrombus size was similar between WT and uPA -/- mice at day 4, suggesting early non uPA-dependent resolution. Intrathrombus neutrophils and monocytes were reduced 3- and 3.5-fold in uPA -/- mice as compared with WT. By ELISA, tumour necrosis factor α and interleukin 1β were not altered, while interferon (IFN)γ was significantly elevated in uPA -/- mice. A compensatory increase in thrombus tPA was not observed, plasmin activity was reduced and PAI-1 was elevated 2.5-fold in uPA -/- mice. Active MMP2, but not MMP9, was elevated 3-fold in uPA -/- mice as compared with WT as well as MMP-14, an MMP2 activator. Collagen type IV and fibrinogen were reduced in uPA -/- mice thrombi as compared with WT. IFNγ induces MMP2, and blockade of IFNγ was associated with larger venous thrombi and reduced active MMP2, as compared with WT. Consistently, MMP2 -/- mice had larger VT as compared with WT controls, despite normal thrombus plasmin levels. Taken together, early experimental venous thrombus resolution is independent of uPA, and, in part, inflammatory cell influx. MMP2-dependent thrombolysis is an important compensatory mechanism of venous thrombus resolution, possibly by collagen type IV metabolism, and may represent an exploitable therapeutic avenue.
authors.affiliation: Jobst Vascular Surgery Laboratory, Section of Vascular Surgery, University of Michigan Medical School, Ann Arbor, Michigan, USA.
authors.forename: Vikram
authors.initials: V
authors.lastname: Sood
authors.forename: Catherine E
authors.initials: CE
authors.lastname: Luke
authors.forename: K Barry
authors.initials: KB
authors.lastname: Deatrick
authors.forename: Joseph
authors.initials: J
authors.lastname: Baldwin
authors.forename: Erin M
authors.initials: EM
authors.lastname: Miller
authors.forename: Megan
authors.initials: M
authors.lastname: Elfline
authors.forename: Gilbert R
authors.initials: GR
authors.lastname: Upchurch
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Wakefield
authors.forename: Peter K
authors.initials: PK
authors.lastname: Henke
mesh_terms: D000818:Animals; D024141:Collagen Type IV / Q000378:metabolism; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D005340:Fibrinogen / Q000378:metabolism; D007371:Interferon-gamma / Q000378:metabolism; D053583:Interleukin-1beta / Q000378:metabolism; D007962:Leukocytes / Q000276:immunology; D008026:Ligation; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D012333:RNA, Messenger / Q000378:metabolism; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014568:Urokinase-Type Plasminogen Activator / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D014682:Vena Cava, Inferior / Q000601:surgery; D020246:Venous Thrombosis / Q000201:enzymology* / Q000235:genetics / Q000276:immunology
chemical_list: D024141:Collagen Type IV; D053583:Interleukin-1beta; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D005340:Fibrinogen; D014568:Urokinase-Type Plasminogen Activator; D020778:Matrix Metalloproteinase 2; C522362:Mmp2 protein, mouse; D020780:Matrix Metalloproteinase 9; C501830:Mmp9 protein, mouse