The importance of extracellular matrix in the induction of preterm delivery

Evidence suggests that in the lower uterine segment at term an increased pr oduction of tumor necrosis factor (TNF) alpha and interleukin (IL)-1 beta i nduces an increase in the expression of adhesion molecules by the endotheli um. The expression of endothelial-leukocyte adhesion molecule-1 and vascula r cell adhesion molecule-1 were found to increase from a cervical dilatatio n of 2-3 cm and reaches a maximum at cervical dilatation of more than 6 cm. Increased adhesiveness of the endothelium leads to extravasation of neutro phils into the cervical stroma. The chemotaxis and degranulation of these c ells is triggered by a rise in the concentration of IL-8 found in the lower uterine segment when cervical dilatation progresses. A significant increas e in stroma invasion by neutrophils with progressive cervical dilatation wa s observed. This finding coincides with a rise in the granulocytic matrix m etalloproteinases (MMP)-8 and MMP-9 concentrations up to complete cervical dilatation. We found similar patterns of cytokine concentrations in the low er uterine segment of patients with preterm delivery: at 2-3 cm dilatation the concentrations of IL-1 beta, IL-6- und IL-8 were significantly higher t han at less than 2 cm. Concomitantly, we also found an increase in MMP-8, M MP-9 and tissue inhibitor of metalloproteinases-1 concentrations from less than 2 cm to 2-3 cm cervical dilatation. These findings suggest that the ch anges in the lower uterine segment during preterm parturition seem to be si milar to those at term and both resemble an inflammatory process.