111. LIF REGULATION OF EPITHELIAL CELL FUCOSYLTRANSFERASE EXPRESSION IN MOUSE ENDOMETRIUM DURING EARLY PREGNANCY

Abstract

Fucosyltransferase (FUT) enzymes are key regulators of glycosylated structures mediating embryo attachment to uterine epithelial cells at implantation. The identity of local regulatory signals is unknown. We have previously shown that macrophage co-culture significantly increases epithelial cell FUT2 and FUT4 mRNA expression in vitro, and the effect of co-culture is replicated with macrophage conditioned media. We aimed to define the identity of macrophage-secreted agents active in regulating FUT expression in mouse uterine epithelial cells, and to investigate the importance of macrophages for FUT expression in vivo.  FUT1, FUT2, and FUT4 mRNAs were measured by qRT-PCR and data was normalised to β-actin mRNA in mouse uterine epithelial cells after culture with cytokines known to be secreted by macrophages. mRNA was also quantified in luminal epithelium laser-microdissected from mouse uterus on day 4 after mating with intact males or seminal vesicle deficient (SVX) males, to induce normal or depleted uterine macrophage populations respectively. Lectin staining on day 4 pc was quantified using ImageJ software in an alternate model of transient, systemic macrophage ablation following diphtheria toxin administration to CD11b-DTR transgenic mice.  Epithelial FUT2 mRNA expression was specifically enhanced in vitro by addition of rLIF (2 ng/ml) (mean relative expression ± SEM, control 100 ± 5.6; rLIF 162.1 ± 11.5). Depletion of macrophages by mating with seminal vesicle deficient males reduced epithelial FUT2 mRNA expression on day 4 pc (intact 100 ± 9.1; SVX 73.5 ± 8.6). Depletion of macrophages in the CD11b-DTR mouse model caused a 30% reduction in the expression of the resulting glycoprotein epitope (α1,2 fucose) as observed by intensity of endometrial epithelial UEA-1 staining (control 100 ± 10; CD11b-DTR 72 ± 9) 24 hr post diphtheria toxin administration.  In conclusion, these data demonstrate that endometrial epithelial FUT2 mRNA synthesis in preparation for embryo implantation is mediated via LIF and potentially other factors secreted from macrophages recruited during the inflammatory response to insemination. Uterine macrophage abundance and phenotype may thus be a determinant of receptivity to implantation.