AXL Inhibition in Macrophages Stimulates Host-versus-Leukemia Immunity and Eradicates Naïve and Treatment-Resistant Leukemia.

Acute leukemias are systemic malignancies associated with a dire outcome. Because of low immunogenicity, leukemias display a remarkable ability to evade immune control and are often resistant to checkpoint blockade. Here, we discover that leukemia cells actively establish a suppressive environment to prevent immune attacks by co-opting a signaling axis that skews macrophages toward a tumor-promoting tissue repair phenotype, namely the GAS6/AXL axis. Using aggressive leukemia models, we demonstrate that ablation of the AXL receptor specifically in macrophages, or its ligand GAS6 in the environment, stimulates antileukemic immunity and elicits effective and lasting natural killer cell- and T cell-dependent immune response against naïve and treatment-resistant leukemia. Remarkably, AXL deficiency in macrophages also enables PD-1 checkpoint blockade in PD-1-refractory leukemias. Finally, we provide proof-of-concept that a clinical-grade AXL inhibitor can be used in combination with standard-of-care therapy to cure established leukemia, regardless of AXL expression in malignant cells. SIGNIFICANCE: Alternatively primed myeloid cells predict negative outcome in leukemia. By demonstrating that leukemia cells actively evade immune control by engaging AXL receptor tyrosine kinase in macrophages and promoting their alternative priming, we identified a target which blockade, using a clinical-grade inhibitor, is vital to unleashing the therapeutic potential of myeloid-centered immunotherapy.This article is highlighted in the In This Issue feature, p. 2659.

Acceleration of TAA-Induced Liver Fibrosis by Stress Exposure Is Associated with Upregulation of Nerve Growth Factor and Glycopattern Deviations.

Liver fibrosis results from many chronic injuries and may often progress to cirrhosis and hepatocellular carcinoma (HCC). In fact, up to 90% of HCC arise in a cirrhotic liver. Conversely, stress is implicated in liver damage, worsening disease outcome. Hence, stress could play a role in disrupting liver homeostasis, a concept that has not been fully explored. Here, in a murine model of TAA-induced liver fibrosis we identified nerve growth factor (NGF) to be a crucial regulator of the stress-induced fibrogenesis signaling pathway as it activates its receptor p75 neurotrophin receptor (p75NTR), increasing liver damage. Additionally, blocking the NGF decreased liver fibrosis whereas treatment with recombinant NGF accelerated the fibrotic process to a similar extent than stress challenge. We further show that the fibrogenesis induced by stress is characterized by specific changes in the hepatoglycocode (increased ß1,6GlcNAc-branched complex N-glycans and decreased core 1 O-glycans expression) which are also observed in patients with advanced fibrosis compared to patients with a low level of fibrosis. Our study facilitates an understanding of stress-induced liver injury and identify NGF signaling pathway in early stages of the disease, which contributes to the established fibrogenesis.

Altered Glycosylation Contributes to Placental Dysfunction Upon Early Disruption of the NK Cell-DC Dynamics.

Immune cells [e. g., dendritic cells (DC) and natural killer (NK) cells] are critical players during the pre-placentation stage for successful mammalian pregnancy. Proper placental and fetal development relies on balanced DC-NK cell interactions regulating immune cell homing, maternal vascular expansion, and trophoblast functions. Previously, we showed that in vivo disruption of the uterine NK cell-DC balance interferes with the decidualization process, with subsequent impact on placental and fetal development leading to fetal growth restriction. Glycans are essential determinants of reproductive health and the glycocode expressed in a particular compartment (e.g., placenta) is highly dependent on the cell type and its developmental and pathological state. Here, we aimed to investigate the maternal and placental glycovariation during the pre- and post-placentation period associated with disruption of the NK cell-DC dynamics during early pregnancy. We observed that depletion of NK cells was associated with significant increases of O- and N-linked glycosylation and sialylation in the decidual vascular zone during the pre-placental period, followed by downregulation of core 1 and poly-LacNAc extended O-glycans and increased expression of branched N-glycans affecting mainly the placental giant cells and spongiotrophoblasts of the junctional zone. On the other hand, expansion of DC induced a milder increase of Tn antigen (truncated form of mucin-type O-glycans) and branched N-glycan expression in the vascular zone, with only modest changes in the glycosylation pattern during the post-placentation period. In both groups, this spatiotemporal variation in the glycosylation pattern of the implantation site was accompanied by corresponding changes in galectin-1 expression. Our results show that pre- and post- placentation implantation sites have a differential glycopattern upon disruption of the NK cell-DC dynamics, suggesting that immune imbalance early in gestation impacts placentation and fetal development by directly influencing the placental glycocode.

Galectin-3 deficiency in pregnancy increases the risk of fetal growth restriction (FGR) via placental insufficiency.

Fetal growth restriction (FGR) is the most common pregnancy complication in developed countries. Pregnancies affected by FGR, frequently concur with complications and high risk of neonatal morbidity and mortality. To date, no approved treatment is available for pregnant women affected with FGR. The objective of this study was to investigate the contribution of galectin-3 (gal-3), a ß-galactoside binding protein involved in pregnancy, placental function and fetal growth. We demonstrated that lack of gal-3 during mouse pregnancy leads to placental dysfunction and drives FGR in the absence of a maternal preeclampsia syndrome. Analysis of gal-3 deficient dams revealed placental inflammation and malperfusion, as well as uterine natural killer cell infiltration with aberrant activation. Our results also show that FGR is associated with a failure to increase maternal circulating gal-3 levels during the second and third trimester in human pregnancies. Placentas from human pregnancies affected by FGR displayed lower gal-3 expression, which correlated with placental dysfunction. These data highlight the importance of gal-3 in the promotion of proper placental function, as its absence leads to placental disease and subsequent FGR.

The chimera-type galectin-3 is a positive modulator of trophoblast functions with dysregulated expression in gestational diabetes mellitus.

PROBLEM: From conception, a delicate regulation of galectins, a family of carbohydrate-binding proteins, is established to ensure maternal immune tolerance in pregnancy. Though galectin-3 (gal-3), the only chimera-type galectin, is abundantly expressed at the feto-maternal interface; the physiological role of this lectin during pregnancy remains to be fully elucidated and requires further investigation. METHOD OF STUDY: In this study, we analyzed serum gal-3 levels during the course of healthy gestation. Trophoblast functions were evaluated upon gal-3 exogenous stimulation using trophoblastic cell lines (e.g. , HIPEC65, SGHPL-4, and BeWo cells). Finally, we investigated variations in peripheral gal-3 levels associated with the development of spontaneous abortion and gestational diabetes mellitus (GDM). RESULTS: Gal-3 circulating levels increased as normal pregnancy progressed. In vitro experiments showed that exogenous gal-3 positively regulated trophoblast functions inducing invasion, tube formation, and fusion. Compared with normal pregnant women, circulating gal-3 levels were significantly decreased in patients who developed GDM. CONCLUSION: Our results reveal a physiological role for gal-3 during pregnancy, promoting proper trophoblast functions associated with healthy gestation. GDM is associated with a failure to increase circulating gal-3 levels late in gestation. Thus, dysregulation of gal-3 may indicate a contribution of the chimera-type lectin to this adverse pregnancy outcome.

NK cell-derived IL-10 is critical for DC-NK cell dialogue at the maternal-fetal interface.

DC-NK cell interactions are thought to influence the development of maternal tolerance and de novo angiogenesis during early gestation. However, it is unclear which mechanism ensures the cooperative dialogue between DC and NK cells at the feto-maternal interface. In this article, we show that uterine NK cells are the key source of IL-10 that is required to regulate DC phenotype and pregnancy success. Upon in vivo expansion of DC during early gestation, NK cells expressed increased levels of IL-10. Exogenous administration of IL-10 was sufficient to overcome early pregnancy failure in dams treated to achieve simultaneous DC expansion and NK cell depletion. Remarkably, DC expansion in IL-10-/- dams provoked pregnancy loss, which could be abrogated by the adoptive transfer of IL-10+/+ NK cells and not by IL-10-/- NK cells. Furthermore, the IL-10 expressing NK cells markedly enhanced angiogenic responses and placental development in DC expanded IL-10-/- dams. Thus, the capacity of NK cells to secrete IL-10 plays a unique role facilitating the DC-NK cell dialogue during the establishment of a healthy gestation.

4-methylumbelliferone inhibits hepatocellular carcinoma growth by decreasing IL-6 production and angiogenesis.

Cirrhosis is characterized by an excessive accumulation of extracellular matrix components including hyaluronic acid (HA) and is widely considered a preneoplastic condition for hepatocellular carcinoma (HCC). 4-Methylumbelliferone (4MU) is an inhibitor of HA synthesis and has anticancer activity in an orthotopic HCC model with underlying fibrosis. Our aim was to explore the effects of HA inhibition by 4MU orally administered on tumor microenvironment. Hepa129 tumor cells were inoculated orthotopically in C3H/HeJ male mice with fibrosis induced by thioacetamide. Mice were orally treated with 4MU. The effects of 4MU on angiogenesis were evaluated by immunostaining of CD31 and quantification of proangiogenic factors (vascular endothelial growth factor, VEGF, interleukin-6, IL-6 and C-X-C motif chemokine 12, CXCL12). IL-6 was also quantified in Hepa129 cells in vitro after treatment with 4MU. Migration of endothelial cells and tube formation were also analyzed. As a result, 4MU treatment decreases tumor growth and increased animal survival. Systemic levels of VEGF were significantly inhibited in 4MU-treated mice. Expression of CD31 was reduced after 4MU therapy in liver parenchyma in comparison with control group. In addition, mRNA expression and protein levels of IL-6 and VEGF were inhibited both in tumor tissue and in nontumoral liver parenchyma. Interestingly, IL-6 production was dramatically reduced in Kupffer cells isolated from 4MU-treated mice, and in Hepa129 cells in vitro. Besides, 4MU was able to inhibit endothelial cell migration and tube formation. In conclusion, 4MU has antitumor activity in vivo and its mechanisms of action involve an inhibition of angiogenesis and IL-6 production. 4MU is an orally available molecule with potential for HCC treatment.

Contractile activity of human follicular dendritic cells.

Follicular dendritic cells (FDCs) present antigens to B cells in the lymphoid follicle and inhibit B-cell apoptosis. In previous work, we obtained human FDC lines that allowed us to study the antigen phenotype and functions of these cells, finding that they expressed α-smooth muscle (SM) actin (a protein involved in cell contraction) and were able to contract collagen gel matrixes in gel contraction assays. Actin polymerization associated with cell contractility is essential for many cellular functions. We report here that interleukin (IL)-2 and interferon (IFN)-γ increased FDC contractility, and IL-10 reduced contractility, whereas IL-4 had no effect. Tumor necrosis factor (TNF) and lymphotoxin (LT)-α1ß2, cytokines involved in FDC differentiation, also increased FDC contractility. In different cell systems, cell contraction is related with the incorporation of α-SM actin into stress fibers. By confocal microscopy, we showed that cytochalasin D, an inhibitor of actin polymerization, inhibited α-SM actin incorporation and relaxed FDCs. Likewise, IL-10 significantly decreased the proportion of FDCs with α-SM actin-positive stress fibers, whereas cytokines that increased FDC contractility also increased this proportion. However, none of the cytokines tested significantly affected α-SM actin expression as determined by flow cytometry. IL-10, in addition to decreasing FDC contractility, increased the inhibitory activity of FDC in spontaneous B-cell apoptosis (P<0.05), but the other cytokines did not affect this activity. We conclude that cytokines related with FDC physiology regulate the contractility of these cells, and IL-10 also regulates the effect of FDC on B-cell apoptosis.

Liaison between natural killer cells and dendritic cells in human gestation.

A successful pregnancy relies on immunological adaptations that allow the fetus to grow and develop in the uterus, despite being recognized by maternal immune cells. Among several immunocompetent cell types present within the human maternal/fetal interface, DC-SIGN(+) dendritic cells (DCs) and CD56(+) natural killer (NK) cells are of major importance for early pregnancy maintenance, not only generating maternal immunological tolerance but also regulating stromal cell differentiation. Previous reports show the presence of NK-DC cell conjugates in first trimester human decidua, suggesting that these cells may play a role in the modulation of the local immune response within the uterus. While effective immunity is necessary to protect the mother from harmful pathogens, some form of tolerance must be activated to avoid an immune response against fetal antigens. This review article discusses current evidence concerning the functions of DC and NK cells in pregnancy and their liaison in human decidua.

Balanced levels of nerve growth factor are required for normal pregnancy progression.

Nerve growth factor (NGF), the first identified member of the family of neurotrophins, is thought to play a critical role in the initiation of the decidual response in stress-challenged pregnant mice. However, the contribution of this pathway to physiological events during the establishment and maintenance of pregnancy remains largely elusive. Using NGF depletion and supplementation strategies alternatively, in this study, we demonstrated that a successful pregnancy is sensitive to disturbances in NGF levels in mice. Treatment with NGF further boosted fetal loss rates in the high-abortion rate CBA/J x DBA/2J mouse model by amplifying a local inflammatory response through recruitment of NGF-expressing immune cells, increased decidual innervation with substance P(+) nerve fibres and a Th1 cytokine shift. Similarly, treatment with a NGF-neutralising antibody in BALB/c-mated CBA/J mice, a normal-pregnancy model, also induced abortions associated with increased infiltration of tropomyosin kinase receptor A-expressing NK cells to the decidua. Importantly, in neither of the models, pregnancy loss was associated with defective ovarian function, angiogenesis or placental development. We further demonstrated that spontaneous abortion in humans is associated with up-regulated synthesis and an aberrant distribution of NGF in placental tissue. Thus, a local threshold of NGF expression seems to be necessary to ensure maternal tolerance in healthy pregnancies, but when surpassed may result in fetal rejection due to exacerbated inflammation.

Getting too sweet: galectin-1 dysregulation in gestational diabetes mellitus.

Galectin-1 (gal-1) is a prototype carbohydrate-binding protein, whose dysregulation is associated with adverse pregnancy outcomes such as spontaneous abortion and pre-eclampsia. Furthermore, it is known that faulty gal-1 protein production or gene regulation can be caused by single-nucleotide polymorphisms in the LGALS1 gene. Gestational diabetes mellitus (GDM) is also an adverse pregnancy outcome and the most common metabolic disorder during gestation. However, gal-1 expression patterns during GDM remain largely unknown. Our aims were to define local and peripheral gal-1 expression patterns during pregnancy, and to investigate LGALS1 gene polymorphisms in GDM patients. Circulating gal-1 levels were determined by ELISA in GDM patients and normal pregnant controls, and LGALS1 gene polymorphisms were assessed for association with GDM. Placental tissues were collected from control and GDM term pregnancies to evaluate local gal-1 expression by immunofluorescence. Our results show that GDM is associated with a failure to increase circulating gal-1 levels during the second and third trimester, as well as overexpression of gal-1 in placental tissue. Additionally, the LGALS1 polymorphism rs4820294 was associated with the development of GDM. In pregnancies complicated by GDM, we observed gal-1 dysregulation both locally in the placenta and peripherally in the circulation. Furthermore, the association between the LGALS1 polymorphism and GDM may indicate a genetic contribution to this adverse pregnancy outcome.

Involvement of galectin-1 in reproduction: past, present and future.

BACKGROUND: After recognition of its pivotal contribution to fetomaternal tolerance, the study of galectin-1 (gal-1) functions in the context of pregnancy became an attractive topic in reproductive medicine. Despite considerable advances in the understanding of the immuno- and growth-regulatory properties of gal-1 at the fetal-maternal interface, many functional aspects of this lectin in reproduction are only emerging. METHODS: The published literature was searched using Pubmed focusing on gal-1 signalling and functional properties at the maternal-fetal interface, including data on its implication in pregnancy disorders and malignancies of the female reproductive system. Papers discussing animal and human studies were included. RESULTS: This review provides an overview of gal-1 functions during pregnancy, such as modulation of maternal immune responses and roles in embryo implantation and placentation. We also emphasize the role of gal-1 in key regulatory processes, including trophoblast migration, invasion, syncytium formation and expression of non-classical MHC class I molecules (HLA-G). In addition, we argue in favour of gal-1 pro-angiogenic properties, as observed in tumourigenesis and other pathological settings, and its implication in the angiogenesis process associated with early gestation. CONCLUSION: The involvement of gal-1 in the regulation of different processes during the establishment, development and maintenance of pregnancy could be described as unique. Gal-1 has emerged as an important lectin with major functions in pregnancy.

Dendritic cells regulate angiogenesis associated with liver fibrogenesis.

During liver fibrogenesis the immune response and angiogenesis process are fine-tuned resulting in activation of hepatic stellate cells that produce an excess of extracellular matrix proteins. Dendritic cells (DC) play a central role modulating the liver immunity and have recently been implicated to favour fibrosis regression; although their ability to influence the development of fibrogenesis is unknown. Therefore, we explored whether the depletion of DC during early stages of liver injury has an impact in the development of fibrogenesis. Using the CD11c.DTR transgenic mice, DC were depleted in two experimental models of fibrosis in vivo. The effect of anti-angiogenic therapy was tested during early stages of liver fibrogenesis. DC depletion accelerates the development of fibrosis and as a consequence, the angiogenesis process is boosted. We observed up-regulation of pro-angiogenic factors together with an enhanced vascular endothelial growth factor (VEGF) bioavailability, mainly evidenced by the decrease of anti-angiogenic VEGF receptor 1 (also known as sFlt-1) levels. Interestingly, fibrogenesis process enhanced the expression of Flt-1 on hepatic DC and administration of sFlt-1 was sufficient to abrogate the acceleration of fibrogenesis upon DC depletion. Thus, DC emerge as novel players during the development of liver fibrosis regulating the angiogenesis process and thereby influencing fibrogenesis.

Differential immunoregulation in successful oocyte donation pregnancies compared with naturally conceived pregnancies.

In oocyte donation (OD) pregnancies, there is a higher level of antigenic dissimilarity between mother and fetus compared with naturally conceived (NC) pregnancies. We hypothesize that a higher degree and/or a different type of immunoregulation is necessary to maintain an uncomplicated OD pregnancy. Different immunological aspects of successful OD pregnancies (n=28) were compared with those of NC pregnancies (n=51), and non-donor IVF (n=20) pregnancies. Maternal peripheral blood mononuclear cells (mPBMCs) were characterized by flow cytometry; the outcome correlated with the number of mother-child HLA mismatches. The fetus-specific alloreactivity of mPBMCs was measured in a mixed lymphocyte reaction. The percentages of CD4(+)CD25(bright) and CD4(+)CD25(dim) cells were higher in mPBMCs of OD and IVF pregnancies compared with NC pregnancies. The percentage of CD4(+)CD25(dim) cells in mPBMCs of OD pregnancies correlated positively with the number of HLA mismatches. Functional studies showed a lower proliferative response to umbilical cord blood by mPBMCs in OD pregnancies. In conclusion, we found a higher degree of peripheral immunoregulation in OD and IVF pregnancies compared with NC pregnancies. A higher number of HLA mismatches in successful OD pregnancies leads to increased percentages of activated T cells in peripheral blood, but not to a higher alloreactivity to the fetus. These studies show that immunoregulation in OD pregnancy is different from that in NC pregnancies. The antigenic dissimilarity in OD pregnancies may play a role in the pathophysiology of preeclampsia.

Interfering with Gal-1-mediated angiogenesis contributes to the pathogenesis of preeclampsia.

Preeclampsia (PE) is a pregnancy-specific disorder characterized by sudden onset of hypertension and proteinuria in the second half of pregnancy (>20 wk). PE is strongly associated with abnormal placentation and an excessive maternal inflammatory response. Galectin-1 (Gal-1), a member of a family of carbohydrate-binding proteins, has been shown to modulate several processes associated with placentation and to promote maternal tolerance toward fetal antigens. Here, we show that Gal-1 exhibits proangiogenic functions during early stages of pregnancy, promoting decidual vascular expansion through VEGF receptor 2 signaling. Blocking Gal-1-mediated angiogenesis or lectin, galactoside-binding, soluble, 1 deficiency results in a spontaneous PE-like syndrome in mice, mainly by deregulating processes associated with good placentation and maternal spiral artery remodeling. Consistent with these findings, we observed a down-regulation of Gal-1 in patients suffering from early onset PE. Collectively, these results strengthen the notion that Gal-1 is required for healthy gestation and highlight Gal-1 as a valuable biomarker for early PE diagnosis.

Galectin-1 influences trophoblast immune evasion and emerges as a predictive factor for the outcome of pregnancy.

Galectin-1 (gal-1) is expressed at the feto-maternal interface and plays a role in regulating the maternal immune response against placental alloantigens, contributing to pregnancy maintenance. Both decidua and placenta contribute to gal-1 expression and may be important for the maternal immune regulation. The expression of gal-1 within the placenta is considered relevant to cell-adhesion and invasion of trophoblasts, but the role of gal-1 in the immune evasion machinery exhibited by trophoblast cells remains to be elucidated. In this study, we analyzed gal-1 expression in preimplantation human embryos and first-trimester decidua-placenta specimens and serum gal-1 levels to investigate the physiological role played by this lectin during pregnancy. The effect on human leukocyte antigen G (HLA-G) expression in response to stimulation or silencing of gal-1 was also determined in the human invasive, proliferative extravillous cytotrophoblast 65 (HIPEC65) cell line. Compared with normal pregnant women, circulating gal-1 levels were significantly decreased in patients who subsequently suffered a miscarriage. Human embryos undergoing preimplantation development expressed gal-1 on the trophectoderm and inner cell mass. Furthermore, our in vitro experiments showed that exogenous gal-1 positively regulated the membrane-bound HLA-G isoforms (HLA-G1 and G2) in HIPEC65 cells, whereas endogenous gal-1 also induced expression of the soluble isoforms (HLA-G5 and -G6). Our results suggest that gal-1 plays a key role in pregnancy maternal immune regulation by modulating HLA-G expression on trophoblast cells. Circulating gal-1 levels could serve as a predictive factor for pregnancy success in early human gestation.

CXCR4(+) dendritic cells promote angiogenesis during embryo implantation in mice.

Early pregnancy is characterized by decidual adaption to the developing embryo involving angiogenesis and vascular growth. Failure of decidual vascular expansion is linked to diseases of pregnancy. Dendritic cells (DC) have been associated with vascular growth during early gestation, though it is unknown whether their capacity to modulate angiogenesis is ubiquitous to all DC subsets. Here, we show that DC normally found associated with the decidual vasculature co-express the C-X-C chemokine receptor type 4 (CXCR4). In addition, we demonstrate that impaired homing of CXCR4(+)DC during early gestation provoked a disorganized decidual vasculature with impaired spiral artery remodeling later in gestation. In contrast, adoptive transfer experiments provided evidence that CXCR4(+)DC are able to rescue early pregnancy by normalizing decidual vascular growth and delivery of pro-angiogenic factors, which results in adequate remodeling of the spiral arteries during placental development. Taken together, our results indicate an important role of CXCR4(+)DC in the regulation of decidual angiogenesis and highlight the importance of the CXCL12/CXCR4 pathway during this process, suggesting that this may represent a key pathway to evaluate during pregnancy pathologies associated with impaired vascular expansion.

Profiling Lgals9 splice variant expression at the fetal-maternal interface: implications in normal and pathological human pregnancy.

Disruption of fetal-maternal tolerance mechanisms can contribute to pregnancy complications, including spontaneous abortion. Galectin-9 (LGALS9), a tandem repeat lectin associated with immune modulation, is expressed in the endometrium during the mid and late secretory phases and in decidua during human early pregnancy. However, the role of LGALS9 during pregnancy remains poorly understood. We used real-time PCR and immunohistochemical staining to analyze the expression of Lgals9/LGALS9 during mouse gestation as well as in human tissues obtained from normal pregnancy and spontaneous abortions. In mice, three Lgals9 splice variants were detected, the expression of which was differentially regulated during gestation. Furthermore, decidual Lgals9 expression was deregulated in a mouse model of spontaneous abortion, whereas placental levels did not change. We further found that the LGALS9 D5 isoform suppresses interferon gamma production by decidual natural killer cells. In human patients, six Lgals9 splice variants were detected, and a decrease in Lgals9 D5/10 was associated with spontaneous abortion. Altogether, these results show a differential regulation of Lgals9 isoform expression during normal and pathological pregnancies and designate Lgals9 as a potential marker for adverse pregnancy outcomes.

Uterine NK cells are critical in shaping DC immunogenic functions compatible with pregnancy progression.

Dendritic cell (DC) and natural killer (NK) cell interactions are important for the regulation of innate and adaptive immunity, but their relevance during early pregnancy remains elusive. Using two different strategies to manipulate the frequency of NK cells and DC during gestation, we investigated their relative impact on the decidualization process and on angiogenic responses that characterize murine implantation. Manipulation of the frequency of NK cells, DC or both lead to a defective decidual response characterized by decreased proliferation and differentiation of stromal cells. Whereas no detrimental effects were evident upon expansion of DC, NK cell ablation in such expanded DC mice severely compromised decidual development and led to early pregnancy loss. Pregnancy failure in these mice was associated with an unbalanced production of anti-angiogenic signals and most notably, with increased expression of genes related to inflammation and immunogenic activation of DC. Thus, NK cells appear to play an important role counteracting potential anomalies raised by DC expansion and overactivity in the decidua, becoming critical for normal pregnancy progression.