Vein wall remodeling after deep vein thrombosis: differential effects of low molecular weight heparin and doxycycline.
BACKGROUND
Venous thrombus resolution sets up an early intense inflammatory reaction, from which vein wall damage results. Tissue response to injury includes matrix metalloproteinase (MMP) activation and extracellular matrix protein turnover. This study sought to determine the effect of exogenous MMP inhibition and its potential attenuation of early vein wall injury.


METHODS
Rats received treatment beginning 24 hr after a stasis venous thrombosis by near occlusive ligation and until harvest at day 7. Three groups were evaluated: (1) vehicle saline controls (NaCl), (2) low molecular weight heparin (LMWH; Lovenox, 3 mg/kg daily SQ), and (3) doxycycline (DOXY, 30 mg/kg daily PO). Thrombus size (mg/mm), levels of tumor necrosis factor alpha (TNF alpha) and D-dimer by colorimetric assay, and monocytes counts by immunohistochemistry were assessed. Vein wall assessment included stiffness by tensiometry, interleukin 1beta (IL-1 beta protein levels by enzyme-linked immunosorbent assay, MMP2 and -9 by zymography, and histological analysis of intimal thickness (IT). Comparisons were by t-test to control. p < 0.05 was considered significant.


RESULTS
Thrombus sizes were similar at days 2 and 7 for all three groups, while thrombus TNFalpha was increased in 2-day LMWH- and DOXY-treated groups (NaCl = 1.0 +/- 0.8, LWMH = 9 +/- 3, DOXY = 27 +/- 5 pg/mg protein, n = 6-8, p < 0.05) and at 7 days in the DOXY group (NaCl = 3.0 +/- 2.5, DOXY = 23 +/- 4.2 pg/mg protein, n = 5, p < 0.05). Vein wall stiffness at 7 days was less with LMWH treatment, but not with DOXY, compared to controls (NaCl = 0.33 +/- 0.05, LMWH = 0.17 +/- 0.03, DOXY = 0.43 +/- 0.09 N/mm, n = 5-7, p < 0.05). Vessel-wall IL-1 beta was reduced only in the DOXY group at 7 days (NaCl = 26 +/- 3, LMWH = 38 +/- 17, DOXY = 6 +/- 3 pg/mg protein, n = 4-6, p < 0.05), as was the IT score versus controls (NaCl = 2.2 +/- 0.6, LMWH =1.7 +/- 0.3, DOXY = 0.8 +/- 0.20, n = 4-6, p < 0.05). Zymographic MMP9 activity was significantly reduced at 2 days in the LMWH and DOXY groups (NaCl = 85 +/- 24, LMWH = 23 +/- 7( *), DOXY = 13 +/- 5 U/mg protein, n = 6-8, p < 0.05). MMP2 zymographic activity, thrombus monocyte cell counts, and D-dimer activity were not significantly different across groups.


CONCLUSIONS
Treatment with LMWH or DOXY did not alter the size of deep vein thrombosis, mildly altered thrombus composition, and differentially affected vein wall injury, despite similar reductions in early MMP9 activity. Whether exogenous MMP inhibition affects long-term vein wall fibrosis will require further study.
Sood
Vikram
V
Jobst Vascular Surgery Laboratory, Section of Vascular Surgery, University of Michigan Medical School, Ann Arbor, MI, USA.
Luke
Cathy
C
Miller
Erin
E
Mitsuya
Mayo
M
Upchurch
Gilbert R
GR
Wakefield
Thomas W
TW
Myers
Dan D
DD
Henke
Peter K
PK
D000818:Animals; D004195:Disease Models, Animal; D004318:Doxycycline / Q000494:pharmacology*; D004548:Elasticity; D017984:Enoxaparin / Q000494:pharmacology*; D005338:Fibrin Fibrinogen Degradation Products / Q000378:metabolism; D005343:Fibrinolytic Agents / Q000494:pharmacology*; D005355:Fibrosis; D053583:Interleukin-1beta / Q000378:metabolism; D008026:Ligation; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D061965:Matrix Metalloproteinase Inhibitors; D017395:Plasminogen Activator Inhibitor 1 / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism; D014682:Vena Cava, Inferior / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D020246:Venous Thrombosis / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology
D017984:Enoxaparin; D005338:Fibrin Fibrinogen Degradation Products; D005343:Fibrinolytic Agents; D053583:Interleukin-1beta; D061965:Matrix Metalloproteinase Inhibitors; D017395:Plasminogen Activator Inhibitor 1; D011480:Protease Inhibitors; D014409:Tumor Necrosis Factor-alpha; C036309:fibrin fragment D; D014568:Urokinase-Type Plasminogen Activator; D020778:Matrix Metalloproteinase 2; C522363:Mmp2 protein, rat; D020780:Matrix Metalloproteinase 9; D004318:Doxycycline