Type I collagen induces tissue factor expression and matrix metalloproteinase 9 production in human primary monocytes through a redox-sensitive pathway.
BACKGROUND
Tissue factor (TF), the main trigger of coagulation cascade, is a major component of the atherosclerotic plaque. Matrix metalloproteinases (MMPs) are recognized as key mediators of extracellular matrix remodeling during inflammation. It was recently emphasized that both TF and MMP-9 were overexpressed in atherosclerotic plaques, suggesting a role of both molecules in plaque instability and thrombogenicity.


OBJECTIVE
The present study was designed to determine whether human monocytes could co-express TF and MMP-9 when the cells interact with type I collagen, a major component of the extracellular matrix and atherosclerotic plaque.


METHODS
Human monocytes were isolated by elutriation and incubated in collagen I-coated plates. Tissue factor and MMP-9 expression were examined using real-time reverse transcription-polymerase chain reaction, flow cytometry, western blot and zymography. The activation of nuclear factor-kappa B (NF-kappaB) and the role of reactive oxygen species (ROS) in TF and MMP-9 production was studied using gel shift experiments, antioxidants pyrrolidine dithiocarbamate (PDTC) and N-acetyl-cysteine (NAC), and apocynin (a specific inhibitor of the NADPH oxidase).


RESULTS
Type I collagen induced TF expression and increased MMP-9 production. In addition, the pro-inflammatory tumor necrosis factor-alpha (TNF-alpha), produced in response to collagen I, increased MMP-9 production. PDTC and NAC inhibited NF-kappaB activation during monocyte interaction with collagen I. Finally, both antioxidants and apocynin decreased the expression of TF, TNF-alpha, and MMP-9.


CONCLUSIONS
These results indicate a new mechanism in the monocyte expression of TF and MMP-9 in response to collagen I involving a ROS-dependent pathway linked to the activation of the NADPH oxidase.
EA3801, URCA and Laboratory of Haematology, CHU Robert Debré, Reims, France.
S
S
Poitevin
R
R
Garnotel
F
F
Antonicelli
P
P
Gillery
P
P
Nguyen
D000098:Acetophenones / Q000494:pharmacology; D000111:Acetylcysteine / Q000494:pharmacology; D001483:Base Sequence; D015153:Blotting, Western; D002478:Cells, Cultured; D024042:Collagen Type I / Q000502:physiology*; D016207:Cytokines / Q000502:physiology; D017931:DNA Primers; D024202:Electrophoretic Mobility Shift Assay; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D006801:Humans; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis*; D009000:Monocytes / Q000201:enzymology / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D010084:Oxidation-Reduction; D011759:Pyrrolidines / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013859:Thiocarbamates / Q000494:pharmacology; D013925:Thromboplastin / Q000378:metabolism*
D000098:Acetophenones; D024042:Collagen Type I; D016207:Cytokines; D017931:DNA Primers; D016328:NF-kappa B; D011759:Pyrrolidines; D017382:Reactive Oxygen Species; D013859:Thiocarbamates; C020972:pyrrolidine dithiocarbamic acid; D013925:Thromboplastin; C056165:acetovanillone; D020780:Matrix Metalloproteinase 9; D000111:Acetylcysteine