Increased
expression of matrix metalloproteinase-9 in the eutopic
endometrial tissue of women with endometriosis
In endometriosis remodelling of the extracellular matrix
(ECM) is a prerequisite for the implantation of endometrial
tissue in ectopic locations.
Researchers at the Centre Hospitalier Universitaire
de Quebec in Canada detected immunoreactive matrix metalloproteinase-9
(MMP-9) throughout endometrial tissue and identified
von Willebrand factor (vWF)-positive endothelial cells,
CD45-positive leukocytes, CD3-positive T lymphocytes
and CD68-positive macrophages as cells expressing MMP-9
in the stroma.
They found an increased expression of MMP-9 in the
uterine endometrial tissue of women with endometriosis,
as assessed by zymography and enzyme-linked immunosorbent
assay (ELISA) (P < 0.05). However, RT-PCR did not
show a statistically significant increase in MMP-9 mRNA
expression in these tissues (P = 0.14).
There was no significant difference between women with
and without endometriosis in the expression of tissue
inhibitor of MMPs (TIMP)-1, a known natural inhibitor
of the pro- and active forms of MMP-9, whether tested
by ELISA or by RT-PCR (P = 0.46 and 0.37, respectively).
Interestingly, the ratio of MMP-9/TIMP-1 expression
was significantly higher in women with endometriosis
than in normal women both at the protein and the mRNA
levels (P < 0.05).
The researchers concluded that these findings make
plausible the involvement of MMP-9/TIMP-1 imbalance
in the invasiveness of the endometrial tissue of patients
with endometriosis and the ectopic development of the
disease.
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