Clinical studies of uterine CSF3 infusion to promote endometrial growth and implantation report mixed results. There are no scientific studies of CSF3 impact on the endometrium or how it may influence fertility.
We hypothesise CSF3 influences endometrial receptivity. Our aim to investigate the mechanisms by which CSF3 impacst receptivity and potential embryo interaction.
Uterine lavage and tissue curettage were collected, with informed consent, from fertile (n= early secretory, n=15 mid-secretory) and idiopathic infertile (n= 18 early secretory, n=18 mid-secretory) women. Lavage CSF3 was assayed using Luminex assay. Isolated primary epithelial cells were stimulated with estrogen and progesterone; the CSF3 in media measured by Luminex, and CSF3R of cells determined by western blot. Immunohistochemical analysis for CSF3R performed on fertile and idiopathic infertile endometrium. Response to chronic and acute exposure of ECC1 endometrial epithelial cells (adhesion and proliferation) and HTR-8/SVneo trophoblast cells (invasion and migration) to glycosylated (CSF3-G) and non-glycosylated (CSF3-NG) CSF3 were monitored using Xcelligence.
CSF3 was elevated in lavage of idiopathic infertile women compared to fertile women during early secretory (p=0.019) and mid-secretory phases (p=0.020). Primary epithelial cells increased secretion of CSF3 in response to progesterone, while CSF3R was down-regulated. Immunohistochemistry showed reduced or absent epithelial CSF3R in tissue from secretory phase infertile women, compared with fertile controls.
Acute exposure of ECC-1 to CSF3-NG or CSF3-G increased ECC1 cell adhesion, a similar increase evident after chronic exposure to CSF3-NG but not CSF3-G. Acute treatment of ECC-1 with CSF3-G or CSF3-NG enhanced proliferation (*p<0.05). However, chronic treatment with CSF3-G inhibited proliferation, an effect not evident with CSF3-NG.
HTR-8/SVneo cells treated with CSF3-NG, but not CSF3-G, showed significantly enhanced migration, while invasion significantly increased with both CSF3-G and CSF3-NG (*p<0.05).
Elevated CSF3 in a negative feedback with CSF3R, is associated with infertility; exerting actions on both endometrium and trophoblast.