These studies may lend promising insights to Tregs as therapeutic targets because of their ability to influence pregnancy outcome through IL-10-dependent or independent mechanisms. While specific decidual cell subsets still remain to be characterized, the

role of IL-10 is manifesting from breakthrough work regarding cross talk between different decidual immune cells. Recent research shows that gd12 murine trophoblasts co-cultured with dendritic cells (DCs)-induced uNK cells to expand and produce IL-10, demonstrating that uNK cells are a rich source of IL-10 which could be required for maintaining their non-cytotoxic phenotype.45,46. These data reveal that production of IL-10, and other pregnancy based cytokines, is context dependent and regulated by an intricate network Vadimezan cell line of cellular cross talk based on the decidual milieu. This assertion is further supported by a recent report that explored the role of Galectin-1, an immunoregulatory glycan binding protein, in the context of pregnancy. Gal1−/−

mice displayed increased Crenolanib mouse rates of fetal loss when compared to WT counterparts. Injection of recombinant Gal-1 into Gal-1−/− mice rescued pregnancy. This was directly associated with an increased number of decidual tolerogenic DCs which in turn induced expansion of IL-10-producing Tregs. Importantly, IL-10 neutralization or Treg depletion upon Gal-1 reconstitution abrogated the rescue of pregnancy.47 Such a scenario could also be envisioned for human pregnancy old (Fig. 2).These data show the existence of an intricate network of trophoblast-DC-IL-10-Treg-based fetal-tolerance that remains to be further elucidated. Successful pregnancy outcome is associated with immune tolerance and de novo angiogenesis at the maternal–fetal

interface. Is there a link between these two events and does IL-10 contribute to angiogenesis? Our recent work provides evidence for both these processes. We have demonstrated that the non-cytotoxic phenotype of human uNK cells is maintained through production of vascular endothelial growth factor c (VEGF C) by these cells and VEGF C-mediated MHC class I expression on endothelial cells and trophoblasts.48,49 Interestingly, IL-10 was found to induce VEGF C production by first trimester trophoblast cells under certain conditions (unpublished observations). Along similar lines, our recent results invoke the role of the water channels aquaporins (AQPs), particularly, at the maternal–fetal interface. AQP1 is a potent effector of fluid volume regulation and is expressed in both human and mouse placenta. AQP1 plays an important role in angiogenesis, and our recent work demonstrates that expression of the AQP1 channel may be directly controlled by the presence of IL-10. We show that IL-10 induces the expression of aquaporin 1 (AQP1) in human trophoblasts as well as in murine placental tissues.