Immunolocalization of MMP-2 and MMP-9 in placenta of humans with gestational diabetes mellitus

Gestational diabetes mellitus, occurring during pregnancy, is a metabolic disorder characterized by hyperglycemia due to a defect in insulin secretion, insulin efficiency or both. It has been reported that Matrix metalloproteinases (MMPs) have undertaken an important role in trophoblast invasion. The most powerful reactions for MMP-2 were found in regions where trophoblast cells had invaded maternal tissues. In addition, the highest MMP-9 activities were detected at points of contact between fetal and maternal tissues. This situation suggests that MMPs are involved in the separation of placenta from uterus wall during birth. In our study, with signed informed consent, placentas which were obtained with normal delivery and caesarean sections from 15 gestational diabetes mellitus (GDM) diagnosed and 15 without any systemic disease (control group) pregnant mothers, were used. Following routine paraffin monitoring of tissue samples from central and peripheral parts of maternal and fetal surfaces of obtained placentas, some sections obtained from paraffin blocks were immunostained by HE, PAS, and Masson's Trichrome stains and remaining sections were immunostained for MMP-2 and MMP-9, and they were evaluated by light microscopy and viewed. In some GDM cases, a significant increase was observed in terminal villi, syncytial knot and bridges of both central and peripheral placenta. It was found that fetal capillaries were extremely dilated and were quite close to syncytiotrophoblasts. In almost all PAS-stained placentas of GDM group, trophoblast basement membrane was noticed to be thickened in some parts. MMP-2 reaction was weakly expressed in maternal and fetal surface, and no significant difference between the two groups was observed. When MMP-9 expression was compared between the groups, an increase in decidual cells of diabetic group and a decrease in syncytial nodes were noticed. In fetal surface, a decrease in expression level was detected in chorionic villus syncytiotrophoblasts, chorionic villus stroma, stem villus syncytiotrophoblasts, stem villous stroma and chorionic plate. Compared with control group, an increase was observed in number of capillary proliferation, perivillous fibrin deposition, syncytial knot and syncytial bridges in terminal villi of placentas of GDM group. Regarding our findings, MMP-9 plays a more active role than MMP-2 in gestational diabetic placentas was concluded.