COLONY-STIMULATING FACTOR-I AND C-FMS EXPRESSION IN HUMAN ENDOMETRIAL TISSUES AND PLACENTA DURING THE MENSTRUAL-CYCLE AND EARLY-PREGNANCY

Colony-stimulating factor-1 (CSF-1), a growth factor produced by monocytes, macrophages, fibroblasts, and endothelial cells, has been implicated in the functional regulation and growth of the murine placenta through the presence of the CSF-1 receptor, c-fms, found in this tissue. In this study we examined the tissue levels of CSF-1 by RIA and the relative expression of CSF-1 and c-fms mRNA by Northern blot analysis in human endometrial, decidual, and placental tissues during the normal menstrual cycle and early pregnancy. All endometrial, decidual, and placental tissues demonstrated extractable immunoreactive CSF-1 and expressed the 4.0-kilobase CSF-1 mRNA species. First trimester decidual tissue expressed higher levels of CSF-1 mRNA than proliferative (3.2-fold higher; P < 0.01) or secretory (2.4-fold higher; P < 0.01) endometrial tissues, whereas proliferative and secretory endometrial tissues expressed similar levels of CSF-1 mRNA. Tissue extractable levels of immunoreactive CSF-1 were 3.2-fold (P < 0.05) higher in first trimester decidual tissue and 2.9-fold (P < 0.05) higher in secretory endometrial tissue compared to levels in proliferative endometrial tissue, whereas first trimester decidua and secretory endometrial tissues had similar levels of immunoreactive CSF-1. There was expression of c-fms mRNA in all endometrial and first trimester decidual tissue samples, with little change during the menstrual cycle and early pregnancy. In placenta, there was a positive correlation of increasing CSF-1 and c-fms mRNA expression with increasing gestational age. These results suggest that there is increased local production of CSF-1 in tissues found at the maternal-fetal interface during the time of implantation and early pregnancy. This increased production of CSF-1 may play a role in decidual function and placental growth through the presence of c-fms in these tissues.