Integrin adhesion molecules in the human endometrium: Correlation with the normal and abnormal menstrual cycle

Abstract

Integrins are a class of cell adhesion molecules that participate in cell-cell and cell-substratum interactions and are present on essentially all human cells. The distribution of nine different a and β integrin subunits in human endometrial tissue at different stages of the menstrual cycle was determined using immunoperoxidase staining. Glandular epithelial cells expressed primarily α2, α3, and α6 (collagen/laminin receptors), while stromal cells expressed predominantly α5 (fibronectin receptor). The presence of a, on glandular epithelial cells was cycle specific, found only during the secretory phase. Expression of both subunits of the vitronectin receptor, α,β3, also underwent cycle specific changes on endometrial epithelial cells. Immunostaining for a, increased throughout the menstrual cycle, while the β3 subunit appeared abruptly on cycle day 20 on luminal as well as glandular epithelial cells. Discordant luteal phase biopsies (≥ 3 d "out of phase") from infertility patients exhibited delayed epithelial β3 immunostaining. These results demonstrate similarities, as well as specific differences, between endometrium and other epithelial tissues. Certain integrin moieties appear to be regulated within the cycling endometrium and disruption of integrin expression may be associated with de-creased uterine receptivity and infertility.