Oxidized low-density lipoprotein regulates matrix metalloproteinase-9 and its tissue inhibitor in human monocyte-derived macrophages.
BACKGROUND
Macrophages in human atherosclerotic plaques produce a family of matrix metalloproteinases (MMPs), which may influence vascular remodeling and plaque disruption. Because oxidized LDL (ox-LDL) is implicated in many proatherogenic events, we hypothesized that ox-LDL would regulate expression of MMP-9 and tissue inhibitor of metalloproteinase-1 (TIMP-1) in monocyte-derived macrophages. MWRHOSA AND RESULTS: Mononuclear cells were isolated from normal human subjects with Ficoll-Paque density gradient centrifugation, and adherent cells were allowed to differentiate into macrophages during 7 days of culture in plastic dishes. On day 7, by use of serum-free medium, the macrophages were incubated with various concentrations of native LDL (n-LDL) and copper-oxidized LDL. Exposure to ox-LDL (10 to 50 microg/mL) increased MMP-9 mRNA expression as analyzed by Northern blot, protein expression as measured by ELISA and Western blot, and gelatinolytic activity as determined by zymography. The increase in MMP-9 expression was associated with increased nuclear binding of transcription factor NF-kappaB and AP-1 complex on electromobility shift assay. In contrast, ox-LDL (10 to 50 microg/mL) decreased TIMP-1 expression. Ox-LDL-induced increase in MMP-9 expression was abrogated by HDL (100 microg/mL). n-LDL had no significant effect on MMP-9 or TIMP-1 expression.


CONCLUSIONS
These data demonstrate that unlike n-LDL, ox-LDL upregulates MMP-9 expression while reducing TIMP-1 expression in monocyte-derived macrophages. Furthermore, HDL abrogates ox-LDL-induced MMP-9 expression. Thus, ox-LDL may contribute to macrophage-mediated matrix breakdown in the atherosclerotic plaques, thereby predisposing them to plaque disruption and/or vascular remodeling.
Atherosclerosis Research Center, Division of Cardiology, and the Burns and Allen Research Institute, Cedars-Sinai Medical Center and UCLA School of Medicine, Los Angeles, CA, USA.
X P
XP
Xu
S R
SR
Meisel
J M
JM
Ong
S
S
Kaul
B
B
Cercek
T B
TB
Rajavashisth
B
B
Sharifi
P K
PK
Shah
D017364:Collagenases / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D008075:Lipoproteins, HDL / Q000494:pharmacology; D008077:Lipoproteins, LDL / Q000378:metabolism / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D020780:Matrix Metalloproteinase 9; D016328:NF-kappa B / Q000378:metabolism; D010084:Oxidation-Reduction; D012333:RNA, Messenger / Q000032:analysis; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000235:genetics*; D018808:Transcription Factor AP-1 / Q000378:metabolism
D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D016328:NF-kappa B; D012333:RNA, Messenger; D019715:Tissue Inhibitor of Metalloproteinase-1; D018808:Transcription Factor AP-1; C099252:oxidized low density lipoprotein; D017364:Collagenases; D020780:Matrix Metalloproteinase 9