Suppression of atherosclerotic plaque progression and instability by tissue inhibitor of metalloproteinase-2: involvement of macrophage migration and apoptosis.
BACKGROUND
Matrix metalloproteinase (MMP)-associated extracellular matrix degradation is thought to contribute to the progression and rupture of atherosclerotic plaques. However, direct evidence of this concept remains elusive. We hypothesized that overexpression of tissue inhibitor of metalloproteinase (TIMP)-1 or TIMP-2 would attenuate atherosclerotic plaque development and instability in high fat-fed apolipoprotein E-knockout (apoE(-/-)) mice.


RESULTS
Seventy male apoE(-/-) mice (n=10/group) fed a high-fat diet for 7 weeks were injected intravenously with first-generation adenoviruses expressing the gene for human TIMP-1 (RAdTIMP-1) or TIMP-2 (RAdTIMP-2) or a control adenovirus (RAd66) and were fed a high-fat diet for a further 4 weeks. Analysis of brachiocephalic artery plaques revealed that RAdTIMP-2 but not RAdTIMP-1 infection resulted in a marked reduction (48+/-13%, P<0.05) in lesion area compared with that in control animals. Markers associated with plaque instability, assessed by smooth muscle cell and macrophage content and the presence of buried fibrous caps, were significantly reduced by RAdTIMP-2. Effects on lesion size were not sustained with first-generation adenoviruses, but murine TIMP-2 overexpression mediated by helper-dependent adenoviral vectors exerted significant effects on plaques assessed 11 weeks after infection. In an attempt to determine the mechanism of action, we treated macrophages and macrophage-derived foam cells with exogenous TIMP-2 in vitro. TIMP-2 significantly inhibited migration and apoptosis of macrophages and foam cells, whereas TIMP-1 failed to exert similar effects.


CONCLUSIONS
Overexpression of TIMP-2 but not TIMP-1 inhibits atherosclerotic plaque development and destabilisation, possibly through modulation of macrophage and foam cell behavior. Helper-dependent adenovirus technology is required for these effects to be maintained long term.
Johnson
Jason L
JL
Bristol Heart Institute, University of Bristol, Bristol, England. jason.l.johnson@bristol.ac.uk
Baker
Andrew H
AH
Oka
Kazuhiro
K
Chan
Lawrence
L
Newby
Andrew C
AC
Jackson
Christopher L
CL
George
Sarah J
SJ
D000256:Adenoviridae; D000818:Animals; D001057:Apolipoproteins E / Q000172:deficiency; D050197:Atherosclerosis / Q000503:physiopathology / Q000517:prevention & control*; D004195:Disease Models, Animal; D018450:Disease Progression; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D005822:Genetic Vectors; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000097:blood; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000235:genetics* / Q000627:therapeutic use
D001057:Apolipoproteins E; D004791:Enzyme Inhibitors; D019715:Tissue Inhibitor of Metalloproteinase-1; D019716:Tissue Inhibitor of Metalloproteinase-2