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Matrix metalloproteinases in normal menstruation
1Prince Henry's Institute of Medical Research, Clayton, Victoria, Australia.
Abstract:
Matrix metalloproteinases (MMP) are strongly implicated in menstruation. Messenger RNA for proMMP-1 and -3 was detectable in normal cycle endometrium only peri-menstrually and menstrually, although mRNA for their tissue inhibitors, TIMP-1 and TIMP-2, was present throughout the cycle. MMP-1, -3 and -9 were demonstrated immunohistochemically to be specifically associated with degraded tissue in menstrual endometrium. Activated mast cells and eosinophils, which release regulators of MMP expression and activators of latent enzymes, were also a marked feature of menstrual endometrium. Cultured endometrial stromal cells released MMP-1, -2, -3 and -9 and TIMP-1 and -2, whereas production by epithelial cells was minimal. Progesterone withdrawal from stromal cell cultures (for the final 4 days of a 10 day culture) increased the release of all four enzymes: all but MMP-2 were also stimulated by interleukin-1 or tumour necrosis factor alpha added to short-term stromal cultures. We postulate that an alteration in the balance of MMP and their inhibitors and the activation of MMP are prerequisites for tissue degradation at menstruation, and that this is regulated by a combination of progesterone withdrawal and paracrine factors from epithelial and stromal cells and from mast cells and eosinophils.
Insights
Matrix metalloproteinases (MMPs) play a key role in menstruation. Their activity and regulation by inhibitors, progesterone withdrawal, and inflammatory cells are crucial for endometrial tissue breakdown during the menstrual cycle.
Area of Science:
- Reproductive Biology
- Molecular Endocrinology
- Cellular Biology
Background:
- Matrix metalloproteinases (MMPs) are enzymes involved in tissue remodeling.
- MMPs are strongly implicated in the physiological process of menstruation.
- Understanding MMP regulation is key to understanding endometrial breakdown.
Purpose of the Study:
- To investigate the role and regulation of MMPs and their inhibitors (TIMPs) in human endometrium during the menstrual cycle.
- To determine the cellular sources of MMPs and TIMPs in endometrial tissue.
- To explore the influence of progesterone withdrawal and inflammatory cytokines on MMP production.
Main Methods:
- Detection of MMP and TIMP mRNA in endometrial tissue via RT-PCR.
- Immunohistochemical analysis to localize MMPs in menstrual endometrium.
- In vitro culture of human endometrial stromal and epithelial cells.
- Treatment of cell cultures with progesterone withdrawal, IL-1, and TNF-α.
Main Results:
- ProMMP-1 and -3 mRNA were detected specifically during menstruation, while TIMP-1 and -2 mRNA were present throughout the cycle.
- MMP-1, -3, and -9 were localized to degraded tissue in menstrual endometrium.
- Endometrial stromal cells released MMP-1, -2, -3, -9, TIMP-1, and TIMP-2; epithelial cells produced minimal amounts.
- Progesterone withdrawal, IL-1, and TNF-α increased MMP release from stromal cells.
Conclusions:
- An imbalance between MMPs and TIMPs, along with MMP activation, is essential for menstrual tissue degradation.
- Progesterone withdrawal and paracrine factors from various endometrial cells and inflammatory cells regulate this process.
- These findings elucidate key molecular mechanisms driving menstruation.