Immunohistochemical expression of matrix metalloproteinases 1 and 2 (MMP-1 and MMP-2) and tissue inhibitor of metalloproteinase 2 (TIMP-2) in ruptured and non-ruptured tubal ectopic pregnancies

Objective. Recent evidence suggests that matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) are crucial for trophoblast implantation in normal pregnancy. To evaluate the expression of MMP-1, MMP2, and the tissue inhibitor of MMP-2 (TIMP-2) along the invasive pathway of trophoblast in ruptured and non-ruptured tubal ectopic pregnancies, we performed a retrospective immunohistochemical study. Methods: In 15 tissue specimens of patients with ruptured (N = 7) and non-ruptured (N = 8) first trimester tubal ectopic pregnancies who underwent laparoscopic salpingectomy, immunohistochemical staining against MMP-1, MMP-2, and TIMP-2 was performed. Serial paraffin sections were photographed and digitized for a computerized quantitative image analysis. Mean percentages of positive stained areas by MMP-1, MMP-2, and TIMP-2 antibodies in the extravillous trophoblast were determined for ruptured and non-ruptured tubal ectopic pregnancies and compared. Results: In our 15 tissue specimens of ectopic pregnancies MMP-1 and TIMP-2 were found to be more prominent in the immunohistochemical distribution pattern than MMP-2. However, no statistically significant difference could be detected between the mean percentages of positive stained area by MMP-1, MMP-2, and TIMP-2 antibodies in ruptured and non-ruptured tubal pregnancies. Discussion: For the first time, we measured the comparative immunohistochemical expression of MMP-1, MMP-2, and TIMP-2 in ruptured and non-ruptured tubal ectopic pregnancies. Although our results did not show any statistically significant difference between ruptured and non-ruptured tubal ectopic pregnancies, we conelude that MMP-1, MMP-2, and TIMP-2 are functionally involved in the highly proliferative early first part of ectopic implantation.