Matrix Metalloproteinase Expression and Regulation During Pregnancy, Term Labour, and Postpartum

It is widely accepted that pregnancy, spontaneous term labour (TL), and postpartum (PP) involution is associated with changes in the cellular and extracellular composition of the uterus. These changes involve metalloproteinases (MMPs) secretion by myometrial smooth muscle cells and infiltrating leukocytes. MMP activation results in collagenolysis, modulation of cellular behaviour and barrier function. I hypothesize that during late gestation, the expression and activity of myometrial MMPs and their tissue inhibitors (TIMPs) increase in preparation for TL, and are regulated by mechanical stretch. The current in vivo study demonstrated that gene and protein expression of MMP-7 and MMP-11 were upregulated during TL, suggesting labour promotion; whereas other MMPs (2, 3, 8, 9, 10, 12) were induced only during the early PP period. The sources of myometrial MMPs during TL and PP include myocytes and resident leukocytes. In vitro studies did not support the regulation of myometrial MMP expression by mechanical stretch.M.Sc