Takahide Mori

The Expression of Peptidase Antigens, CD10/Neutral Endopeptidase, CD13/Aminopeptidase N, and CD26/Dipeptidyl Peptidase IV in Human Endometrium

Peptidase enzymes are known to be widely distributed in plasma and tissues. As such, they are considered to play important roles in the local regulation of biologically active peptides, including peptide hormones, growth factors, and cytokines. In the uterine endometrium, it has been suggested that some peptidase enzymes in the endometrial epithelium play an important role in blastocyst implantation. In rabbits, the uterine epithelium undergoes extensive morphological change during the peri-implantation phase, and dynamic changes in aminopeptidase and dipeptidyl peptidase IV activities on the surface of endometrial epithelial cells have been reported in histochemical experiments (Classen-Linke et al., 1987). Furthermore, proteinase inhibitors have been shown to block implantation in rabbits (Denker, 1977). In humans, we have reported that the cluster of differentiation (CD) antigens, CD10 and CD13, were expressed in the endometrial stromal cells, and that CD26 antigens were localized in the glandular epithelial cells (Imai et al., 1992a, 1992b). CD10, CD13, and CD26 antigens were shown to be identical to neutral endopeptidase (NEP) (Letarte et al, 1988), aminopeptidase N (APN) (Look et al. 1989), and dipeptidyl peptidase IV (DPP IV) (Mattern et al., 1989; Stein et al., 1989;Ulmer et al., 1990) respectively, all of which are cell surface peptidases. Since a variety of peptide factors, including peptide hormones, growth factors, and cytokines, have been suggested to play important roles in regulating endometrial cell proliferation/differentiation, these peptidase enzymes are thought to be involved in the regulation of human endometrial function and the implantation process.