Studies on peptidase enzymes in human endometrium and placenta

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Human endometrium expresses cell-surface peptidase antigens of aminopeptidase N (APN), neutral endopeptidase (NEP), and dipeptidyl peptidase IV (DPPIV). By an indirect immunofluorescence staining with specific monoclonal antibodies, it revealed that the expressions of these peptidases are cell-type specific and change dynamically during menstruation cycle and pregnancy. APN and NEP are expressed on endometrial stromal cells, and their expression are weak during proliferative phase. After ovulation, APN expression increases and decidual cells in early pregnancy express very strong APN antigen. NEP also increases during secretory phase and gradually decreases after decidualization. DPPIV is exclusiveiy expressed on glandular epithelial cells, and most prominent expression is seen during mid-secretory phase, suggesting its role in blastocyst implantation. These findings suggest the hormonal control of endometrial cell peptidase expression, and in vitro culture with purified stromal cells … More indicated the important role of progesterone and estrogen in the induction of APN antigen expression as well as biological activity of the enzyme. When a APN inhibitor, bestatin, was added to in vitro stromal cell differentiation (decidualization) system induced by progesterone, cell differentiation indicated by prolactin production and morphological transformation was inhibited dose-dependently. Therefore APN is also an important molecule for endometrial cell differentiation. In the first trimester chorionic villi, cytotrophoblasts expressed both NEP and DPPIV,but syncytiotrophoblasts expressed only NEP.Stromal cells in the chorionic villi expressed APN,NEP and DPPIV at various intensities. In the term placenta, villous syncytiotrophoblasts expressed NEP weakly, and the villous stromal cells intensely expressed APN and DPPIV.Thus it is suggested that three peptidases are very useful marker of endometrial and placental cells, and are important molecules in endometrial physiology and pregnancy maintenance. Less