Macrophages regulate expression of α1,2-fucosyltransferase genes in human endometrial epithelial cells

The epithelial cell surface of the endometrium undergoes substantial biochemical changes to allow embryo attachment and implantation in early pregnancy. We hypothesized that tissue macrophages influence these events to promote uterine receptivity. To investigate the role of macrophages in regulating epithelial cell expression of genes linked to glycan-mediated embryo adhesion, Ishikawa, RL95-2 and HEC1A endometrial epithelial cells were cultured alone or with unactivated or lipopolysaccharide-activated monocytic U937 cells, separated using transwell inserts. Expression of mRNAs encoding two α1,2-fucosyltransferases (FUT1, FUT2) was increased in all three epithelial cell lines following co-culture with U937 cells, and was associated with increased fucosylation of cell surface glycoproteins detected using lectins from Ulex europaeus (UEA-1) and Dolichos biflorus (DBA). FUT1 induction by U937 cells also occurred in primary endometrial epithelial cells collected in luteal but not proliferative phase. Activation of the interleukin-6 (IL6)/leukemia inhibitory factor (LIF) cytokine signaling pathway with phosphorylation of STAT3 and elevated SOCS3 mRNA expression was evident in epithelial cells stimulated by U937 co-culture. Several recombinant macrophage-secreted cytokines exerted stimulatory or inhibitory effects on FUT1 and FUT2 mRNA expression, and the macrophage-derived cytokine LIF partially replicated the effects of U937 cells on both FUT1 and FUT2 expression and UEA-1 and DBA lectin reactivity in Ishikawa cells. These results suggest that macrophage-derived factors including LIF might facilitate development of an implantation-receptive endometrium by regulating surface glycan structures in epithelial cells. Abnormal phenotypes or altered abundance of uterine macrophages could contribute to the pathophysiology of primary unexplained infertility in women.