Expression of galectin-8 on human endometrium: Molecular and cellular aspects

BACKGROUND The up-regulation of galectin-3, galectin-9, and galectin-15 expression in the luminal and glandular epithelium was reported in preparation of the endometrium for embryo implantation at the midlutheal phase. However, no data was available regarding the expression and the distribution pattern of galectin-8 in the human endometrium during a regular menstrual cycle. OBJECTIVE The current study designed to investigate the expression and the distribution pattern of galectin-8, a beta-galactoside-binding lectin in the human endometrium during both proliferative and luteal phases of a regular menstrual cycle. MATERIALS AND METHODS Endometrial biopsies were obtained from the anterior wall of the uterine cavity of 16 women (proliferative phase: n=4, lutheal phase: n=12). All female patients with mean age of 37.5 years were fertile (range 25-45). Each biopsy was divided into three pieces; one piece was fixed in formaldehyde for light microscopy and immunohistochemistry. The second portion fixed in glutaraldehyde for scanning electron microscopy and the third portion was prepared for western blot analysis. RESULTS Data of immunoblotting revealed a molecular weight of 34 kD band with high intensity in the lutheal phase samples. The immunohistochemistry staining demonstrated that galectin-8 expressed at a very low concentration during the proliferative phase, but showed a high expression throughout the lutheal phase. The expression of galectin-8 observed in luminal surface epithelium, glandular epithelium and stroma. CONCLUSION The up-regulation of the expression of galectin-8 during lutheal phase may suggest galectin-8 as one of the potential molecular marker of the endometrial receptivity. These data propose that galectin-8 may play an important role during the initial events of human embryo implantation.