Gender differences in rat aortic smooth muscle cell matrix metalloproteinase-9.
BACKGROUND
A predilection exists for men to develop abdominal aortic aneurysms (AAAs), but the reasons for this gender predisposition are not known. Matrix metalloproteinase-9 (MMP-9) has been implicated in both human and experimental AAAs. This investigation tested the hypothesis that male and female gender differences exist in the production of MMP-9 by rat aortic smooth muscle cells (RASMCs).


METHODS
In the first set of experiments, cultured male and female RASMCs were stimulated with interleukin-1 beta (IL-1beta) at 2 ng/mL. Messenger RNA was extracted from the RASMCs and gene expression of MMP-9 and tissue inhibitor of metalloproteinase-1 (TIMP-1), an MMP-9 inhibitor, was measured by quantitative real-time polymerase chain reaction. Cell culture media were collected for measurement of MMP-9 protein levels and MMP-9 activity by Western blotting and gelatin zymography, respectively. In the second set of experiments, male RASMCs were treated with 17-beta-estradiol (10(-10) to 10(-6) mol/L) and MMP-9 activity was measured. In the third set of experiments, male rats were pretreated with estradiol, and MMP-9 activity was measured in the media from explanted aortas.


RESULTS
MMP-9 gene expression was 10-fold higher in male versus female RASMCs (p=0.003). MMP-9 protein levels (p=0.005) and gelatinolytic activities (p=0.01) were also greater in male than female RASMCs. TIMP-1 expression was fourfold higher in male versus female RASMCs (p<0.001). Estradiol-treated male RASMCs did not exhibit a decrease in MMP-9 activity. But aortic explants from male rats pretreated with 17-beta-estradiol had 60% less MMP-9 activity than explants from male controls (p=0.03).


CONCLUSIONS
MMP-9 and TIMP-1 are greater in male than in female RASMCs. These findings support the tenet that gender-related differences in MMP-9 may contribute to AAA formation.
Woodrum
Derek T
DT
Jobst Vascular Research Laboratories, Section of Vascular Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI, USA.
Ford
John W
JW
Ailawadi
Gorav
G
Pearce
Charles G
CG
Sinha
Indranil
I
Eagleton
Matthew J
MJ
Henke
Peter K
PK
Stanley
James C
JC
Upchurch
Gilbert R
GR
D000818:Animals; D001011:Aorta / Q000166:cytology; D017544:Aortic Aneurysm, Abdominal / Q000209:etiology; D015153:Blotting, Western; D002478:Cells, Cultured; D005260:Female; D015870:Gene Expression; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis*; D061965:Matrix Metalloproteinase Inhibitors; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000201:enzymology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012737:Sex Factors; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000096:biosynthesis
D061965:Matrix Metalloproteinase Inhibitors; D012333:RNA, Messenger; D019715:Tissue Inhibitor of Metalloproteinase-1; D020780:Matrix Metalloproteinase 9