Expression patterns of cathepsins B, H, K, L and S in the human endometrium

Cathepsins B, H, K, L and S belong to the family of lysosomal cysteine prot einases and participate in a variety of proteolytic processes, including de gradation of the extracellular matrix (ECM), In the present study, we used Northern hybridization to demonstrate the presence of mRNAs for cathepsins B, H, K, L and S in human endometrium during both the proliferative and sec retory phases of menstrual cycle, The mRNA levels for cathepsins H and K we re significantly lower in secretory phase endometrium in comparison with pr oliferative phase endometrium, Immunohistochemical localization of the diff erent cathepsins revealed widespread distribution of all cathepsins in both stroma and epithelial cells, The immunoreactivity for cathepsins B, H and K exhibited changes related to endometrial location and/or to the phase of the cycle, The strongest immunoreactivity for cathepsins B, H, L and S was observed in the surface epithelium of the endometrium, The staining for cat hepsins was predominantly intracellular, but immunoreactivity was also dete cted on the surface of small lymphoid cells in the stroma, The findings of the present study suggest that cysteine cathepsins are needed for normal de velopment and function of human endometrium during both the proliferative a nd secretory phases.