Interferon-λ contributes to endometrial receptivity

Immunotherapy has been commonly used to prevent recurrent pregnancy loss in women with inadequate uterus receptivity or immunological imbalance. Many immune regulators are now identified as having crucial roles at the embryo-maternal interface. However, the clinical efficacy of immunity-related markers during the peri-implantation period remains to be explored in depth. Here, we demonstrated that endometrial expression of interferon-λ (IFN-λ), regarded as a newer class of interferons, is aberrantly lower in women who suffered from recurrent implantation failure than that in fertile control. We further uncovered genetic and biochemical evidence that IFN-λ is induced directly by estrogen in the endometrial cells, and IFN-λ pathway may play multiple roles involving the inflammatory response, uterine receptivity, cell migration, and blastocyst adhesion. Furthermore, we indicated IFN-λ lessens the sensitivity of endometrium to FASL-mediated apoptosis. In addition to uncovering this IFN-λ as a novel nonredundant regulator that participates in the fetal-maternal immune interaction, our study helps to elucidate the underlying causes of spontaneous pregnancy loss in women.