Uterine NK cells in murine pregnancy

Efeito do hipotireoidismo materno na expressão espaço-temporal de mediadores imunológicos e população de células natural killers na decídua e na glândula metrial de ratas

RESUMO Estudou-se o efeito do hipotireoidismo materno na expressão espaço-temporal de mediadores imunológicos e na população de células natural killers (NK) na decídua e na glândula metrial de ratas durante a gestação. Avaliou-se a detecção imunoistoquímica de interferon γ (IFNγ), do fator inibidor de migração (MIF), da interleucina 15 (IL15), do óxido nítrico sintase induzível (iNOS), a marcação com lectina DBA para evidenciação das células NK uterinas DBA+ e a expressão gênica de Ifnγ e Nos2. O hipotireoidismo aumentou o iNOS aos sete dias, a IL15 e o MIF aos 10 e 12 dias, o IFNγ e o MIF aos 14 DG e a expressão dos transcritos gênicos para iNos aos 12 e 19 dias e para Ifnγ aos 14 DG. O hipotireoidismo reduziu a imunomarcação de MIF e lectina DBA aos sete dias, lectina DBA aos 10 e 14 DG, IFNγ aos 12 dias, e a expressão de Ifnγ aos 10 e 19 DG e de iNOS aos 12, 14 e 19 DG, bem como reduziu seus transcritos gênicos aos 10 e 14 DG. Conclui-se que o hipotireoidismo compromete o perfil imunológico na interface materno-fetal ao longo da gestação, particularmente por reduzir o fator anti-inflamatório iNOS e a população de células uNK DBA+.

Emerging roles of atypical chemokine receptor 3 (ACKR3) in normal development and physiology

The discovery that atypical chemokine receptors (ACKRs) can initiate alternative signaling pathways rather than classical G-protein coupled receptor (GPCR) signaling has changed the paradigm of chemokine receptors and their roles in modulating chemotactic responses. The ACKR family has grown over the years, with discovery of new functions and roles in a variety of pathophysiological conditions. However, the extent to which these receptors regulate normal physiology is still continuously expanding. In particular, atypical chemokine receptor 3 (ACKR3) has proven to be an important receptor in mediating normal biological functions, including cardiac development and migration of cortical neurons. In this review, we illustrate the versatile and intriguing role of ACKR3 in physiology.

The microstructure in the placenta is influenced by the functional diversity of HLA-G allelic variants

The main expression sites of HLA-G are human extravillous trophoblast cells. The interaction of HLA-G with uterine NK cells promotes their maturation and differentiation into decidual NK (dNK) cells. dNK cells secrete chemokines, cytokines, and proangiogenic factors in favor of a vascular remodeling and an immune suppressive microenvironment of the decidua. HLA-G is the most polymorphic member of the oligomorphic non-classical HLA molecule family; yet, the impact of polymorphic differences is not comprehensively understood. sHLA-G levels in embryo culture medium correlate with successful pregnancy; however, it remains questionable if HLA-G allelic diversity impacts on the outcome of dNK cell development. We utilized synthetic sHLA-G*01:01, 01:03, and 01:04 molecules and transduced K652/mHLA-G*01:01, 01:03, and 01:04 cells to study the biological interaction between HLA-G alleles and primary NK cells of human term placenta. Despite its low frequency, HLA-G*01:04 and not the most prevalent allele HLA-G*01:01 appear to be strong catalysts of dNK cell proliferation. Concluding, this study illustrates novel insights into the impact and binding efficiency of the three most common variants of HLA-G on primary placental NK cells.

Flutamide ameliorates uterine decidualization and angiogenesis in the mouse hyperandrogenemia model during mid-pregnancy

Background/Aim

Patients with polycystic ovary syndrome (PCOS), characterized by anovulation, hyperandrogenemia and polycystic ovaries, are still vulnerable to undergo recurrent pregnancy loss and premature labor even though the ovulatory process is pharmacologically recovered. However, its potential mechanism remains unknown. Thus, our aim was to investigate the effect and mechanism of hyperandrogenemia and flutamide (a non-steroidal anti-androgen) on the embryo implantation and pregnancy during mid-pregnancy.

Methods

We used a mouse model in which PCOS-like hyperandrogenemia was induced by subcutaneous injection of testosterone propionate. In this model, we observed the effect of hyperandrogenemia and flutamide on the decidualization, angiogenesis and uNK cells by methods of immunohistochemistry, quantitative PCR, western blotting and Dolichos biflorus agglutinin (DBA) lectin staining.

Results

Testosterone and flutamide treatment did not significantly influence the numbers of implanted embryo compared with the control group. However, different doses of testosterone significantly increased the ratio of resorbed /implanted embryo, decreased the level of prl8a2 mRNA and cyclin D3 protein, inhibited the uterine angiogenesis and reduced the numbers of uNK cells, but combined treatment with flutamide markedly decreased the resorbed embryos, increased expressions of prl8a2 mRNA and cyclin D3 protein and angiogenesis and numbers of uNK cells.

Conclusion

Flutamide treatment can efficiently ameliorate the hyperandrogenemia-induced the disorders in aspects of decidualization, angiogenesis and uNK cells, which further improve the poor endometrial receptivity in PCOS patients.

Morphology and physiology of rat placenta for toxicological evaluation

The placenta plays a pivotal role in fetal growth, and placental dysfunction and injury are associated with embryo/fetal toxicity. Histological examination of the rat placenta for safety evaluation provides valuable clues to the mechanisms of this toxicity. However, the placenta has specific and complex biological features unlike those of other organs, and placental structure dramatically changes depending on the time during the gestation period. Thus, time-dependent histopathological examination of the rat placenta should be performed based on the understanding of normal developmental changes in morphology and function. The placentas of rats and humans are both anatomically classified as discoid and hemochorial types. However, there are differences between rats and humans in terms of placental histological structure, the fetal-maternal interface, and the function of the yolk sac. Therefore, extrapolation of placental toxicity from rats to humans should be done cautiously in the evaluation of risk factors. This review describes the development, morphology, physiology, and toxicological features of the rat placenta and the differences between the rat and human placenta to enable accurate evaluation of reproductive and developmental toxicity in studies.

17β-Estradiol induces proliferation of endometrial NK cells (CD56+) in postmenopausal women

OBJECTIVE

The aim of this report was to evaluate the impact of hormone replacement therapy (HRT) on lymphocytic infiltration of the endometrium in postmenopausal women.

METHOD

This study included 58 Japanese patients who had undergone hysterectomy at the University Hospital of Occupational and Environmental Health, Japan. Before surgery, nine patients had received 17β-estradiol (E2), 0.72 mg transdermally for 2-8 weeks (E2 group); 16 patients had received an Estra-1,3,5(10)-triene-3,16α, 17β-triol (E3) vaginal tablet 0.5 mg per month five times (E3 group); and 19 patients had received 17β-estradiol, 0.62 mg, and norethindrone acetate (P), 2.70 mg for 3-16 weeks (E2 + P group). Fourteen patients received no HRT (control group). We examined uterine tissue specimens immunohistochemically for CD45+, CD3+, CD4+, CD8+, CD20+, CD56+, and Ki67 antigen-positive cells.

RESULTS

The numbers of CD56 + cells were significantly increased in the E2 group compared with all other groups (E2 vs. E3: 7.0 vs. 0.75, p = 0.017; E2 vs. E2 + P: 7.0 vs. 0.58, p = 0.009; E2 vs.

CONTROL

7.0 vs. 0.43, p = 0.010). The numbers of CD3+ cells were significantly increased in the E2 group compared with the control group (149.3 vs. 42.6, p = 0.008).

CONCLUSION

17β-Estradiol induced the proliferation of endometrial uterine natural killer cells (CD56+) in postmenopausal women.

The regulation of ovary and conceptus on the uterine natural killer cells during early pregnancy

Uterine natural killer (uNK) cells are short-lived, terminally differentiated and the most abundant lymphocytes in the uterus which play a crucial role in the spiral arteriole modification and establishment of successful pregnancy. Dysregulation of uNK cells has been linked to gestational implications such as recurrent pregnancy loss, preeclampsia and fetal growth retardation. There is evidence showing that progesterone and estrogen can regulate the recruitment, proliferation, differentiation and function of uNK cells via direct action on intracellular nuclear receptors or through intermediary cells in the uterus during early pregnancy. As the deepening of related research in this field, the role of conceptus in such regulation has received extensive attention, it utilizes endocrine signaling (hCG), juxtacrine signaling (HLA-C, HLA-E, HLA-G) and paracrine signaling (cytokines) to facilitate the activities of uNK cells. In addition, under the influence of ovarian hormones, conceptus can increase expression of PIBF and HLA-G molecules to reduce cytotoxicity of uNK cells and promote angiogenesis. In this review, we aim to concentrate on the novel findings of ovarian hormones in the regulation of uNK cells, emphasize the regulatory role of conceptus on uNK cells and highlight the proposed issues for future research in the field.

Microvascular lesions and changes in cell proliferation and death, and cytokine expression in the placentas of mice experimentally infected with Equid Herpesvirus 1

This study describes the changes observed in the placentas of mice experimentally infected with an abortigenic strain of EHV-1 at mid-pregnancy and euthanized at days 3 and 4 post-infection. We analyzed microscopic vascular alterations, cell proliferation and death by immunohistochemistry, and the expression of IFN-γ, TNF-α and the IL-10 by qPCR and flow cytometry. Infected mice showed slight respiratory signs and ruffled fur during the first two days post-infection. Virus isolation and DNA detection were positive only in the lungs of the infected mice. Vascular congestion, increase in the labyrinth area, and a significant reduction in fetal capillary endothelium surface of infected placentas were found. Cell proliferation was significantly reduced in the infected placentas, whereas the apoptosis was significantly increased. IL10, TNF and IFN-γ showed different expression in the infected placentas and uteri. The effects of EHV-1 during pregnancy depend on different pathogenic mechanisms in which vascular alterations, and cell death and proliferation and local cytokine changes are compromised.

An Evaluation of the Impact of PD-1 Pathway Blockade on Reproductive Safety of Therapeutic PD-1 Inhibitors

This report discusses the principles of reproductive toxicity risk assessment for biopharmaceuticals blocking the PD-1/programmed cell death ligand 1 (PD-L1) pathway, which have been developed for the treatment of patients with advanced malignancies. The PD-1/PD-L1 pathway is a T-cell co-inhibitory pathway that normally maintains immune tolerance to self. Its role in pregnancy is to maintain immune tolerance to the fetal allograft. In cancer patients, this signaling pathway is hijacked by some neoplasms to avoid immune destruction. PD-1/PD-L1-blocking agents enhance functional activity of the target lymphocytes to eventually cause immune rejection of the tumor. A therapeutic blockade of PD-1/PD-L1 pathway that occurs at full target engagement provides a unique challenge to address the risk to pregnancy because disruption of the same pathway may also reduce or abrogate maternal immune tolerance to the fetal alloantigens inherited through the father. Typically, nonclinical reproductive and developmental toxicity (DART) studies in animals (rats and rabbits) with clinical drug candidates are conducted to identify potential risk in humans and to determine exposure margin for the effects on reproduction as part of the risk assessment. However, for biopharmaceuticals for which the desired mechanism of action cannot be separated from potential deleterious effects to the fetus and when the only relevant toxicology species is nonhuman primate (NHP), the risk to reproduction can be predicted by a mechanism-based assessment using data generated from murine surrogate models as supportive information without conducting DART in NHPs. Such an approach has been used in the evaluation of pregnancy risk of anti-PD-1 agent, pembrolizumab, and has been demonstrated as an important alternative to performing DART studies in NHPs.

The role of decidual cells in uterine hemostasis, menstruation, inflammation, adverse pregnancy outcomes and abnormal uterine bleeding

BACKGROUND

Human pregnancy requires robust hemostasis to prevent hemorrhage during extravillous trophoblast (EVT) invasion of the decidualized endometrium, modification of spiral arteries and post-partum processes. However, decidual hemorrhage (abruption) can occur throughout pregnancy from poorly transformed spiral arteries, causing fetal death or spontaneous preterm birth (PTB), or it can promote the aberrant placentation observed in intrauterine growth restriction (IUGR) and pre-eclampsia; all leading causes of perinatal or maternal morbidity and mortality. In non-fertile cycles, the decidua undergoes controlled menstrual bleeding. Abnormal uterine bleeding (AUB) accompanying progestin-only, long-acting, reversible contraception (pLARC) accounts for most discontinuations of these safe and highly effective agents, thereby contributing to unwanted pregnancies and abortion. The aim of this study was to investigate the role of decidual cells in uterine hemostasis, menstruation, inflammation, adverse pregnancy outcomes and abnormal uterine bleeding.

METHODS

We conducted a critical review of the literature arising from PubMed searches up to December 2015, regarding in situ and in vitro expression and regulation of several specific proteins involved in uterine hemostasis in decidua and cycling endometrium. In addition, we discussed clinical and molecular mechanisms associated with pLARC-induced AUB and pregnancy complications with abruptions, chorioamnionitis or pre-eclampsia.

RESULTS

Progestin-induced decidualization of estradiol-primed human endometrial stromal cells (HESCs) increases in vivo and in vitro expression of tissue factor (TF) and type-1 plasminogen activator inhibitor (PAI-1) while inhibiting plasminogen activators (PAs), matrix metalloproteinases (MMPs), and the vasoconstrictor, endothelin-1 (ET-1). These changes in decidual cell-derived regulators of hemostasis, fibrinolysis, extracellular matrix (ECM) turnover, and vascular tone prevent hemorrhage during EVT invasion and vascular remodeling. In non-fertile cycles, progesterone withdrawal reduces TF and PAI-1 while increasing PA, MMPs and ET-1, causing menstrual-associated bleeding, fibrinolysis, ECM degradation and ischemia. First trimester decidual hemorrhage elicits later adverse outcomes including pregnancy loss, pre-eclampsia, abruption, IUGR and PTB. Decidual hemorrhage generates excess thrombin that binds to decidual cell-expressed protease-activated receptors (PARs) to induce chemokines promoting shallow placentation; such bleeding later in pregnancy generates thrombin to down-regulate decidual cell progesterone receptors and up-regulate cytokines and MMPs linked to PTB. Endometria of pLARC users display ischemia-induced excess vasculogenesis and progestin inhibition of spiral artery vascular smooth muscle cell proliferation and migration leading to dilated fragile vessels prone to bleeding. Moreover, aberrant TF-derived thrombin signaling also contributes to the pathogenesis of endometriosis via induction of angiogenesis, inflammation and cell survival.

CONCLUSION

Perivascular decidualized HESCs promote endometrial hemostasis during placentation yet facilitate menstruation through progestational regulation of hemostatic, proteolytic, and vasoactive proteins. Pathological endometrial hemorrhage elicits excess local thrombin generation, which contributes to pLARC associated AUB, endometriosis and adverse pregnancy outcomes through several biochemical mechanisms.

Relationship between uterine natural killer cells and unexplained repeated miscarriage

OBJECTIVE

To evaluate the relation between uterine killer (uK) cells and unexplained repeated miscarriage (RM).

MATERIAL AND METHODS

Eighty women with unexplained repeated miscarriage and missed miscarriage of current pregnancy were studied. Fetal viability and gestational age of the current pregnancy were confirmed by ultrasound, followed by suction evacuation to collect abortion specimens and uterine wall curettage to collect decidua specimens. Abortion specimens were collected for long-term monolayer cell culture and subsequent chromosome analysis using conventional G-banding. Decidua specimens were subjected to immunohistochemical staining using monoclonal antibodies specific to CD56+ and CD16+ expressed by uK cells.

RESULTS

CD56+ CD16+ uK cells were found in 85% [68/80] of the studied decidua specimens of women with unexplained repeated miscarriage; 88.5% [54/61] had normal abortion karyotyping and 73.7% [14/19] had abnormal abortion karyotyping. Moreover, 73.75% [59/80] of the studied women with a past history of early miscarriage had CD56+ CD16+ uK cells in their decidua specimens, and 66.25% [53/80] of studied women with a past history of late miscarriage had CD56+ CD16+ uK cells in their decidua specimens; the association between early and late miscarriage and CD56+ CD16+ uK cells in decidua specimens was significant.

CONCLUSION

CD56+CD16+ uK cells were predominant in the decidua specimens of the studied women with repeated miscarriage. A significant association was found between the presence of CD56+ CD16+ uK cells in the studied decidua specimens and unexplained repeated miscarriage.

Cellular Regulation of the Uterine Microenvironment That Enables Embryo Implantation

Implantation of the fertilized egg into the maternal uterus is a crucial step in pregnancy establishment. Increasing evidence suggests that its success depends on various cell types of the innate immune system and on the fine balance between inflammatory and anti-inflammatory processes. In addition, it has recently been established that regulatory T cells play a superordinate role in dictating the quality of uterine environment required for successful pregnancy. Here, we discuss the cellular regulation of uterine receptivity with emphasis on the function and regulation of cells from the innate and adaptive immune system.

Hectd1 is required for development of the junctional zone of the placenta

The placenta plays a critical role in the growth and survival of the fetus. Here we demonstrate that the Homologous to the E6-AP Carboxyl Terminus (HECT) domain E3 ubiquitin ligase, Hectd1, is essential for development of the mouse placenta. Hectd1 is widely expressed during placentation with enrichment in trophoblast giant cells (TGCs) and other trophoblast-derived cell subtypes in the junctional and labyrinth zones of the placenta. Disruption of Hectd1 results in mid-gestation lethality and intrauterine growth restriction (IUGR). Variable defects in the gross structure of the mutant placenta are found including alterations in diameter, thickness and lamination. The number and nuclear size of TGCs is reduced. Examination of subtype specific markers reveals altered TGC development with decreased expression of Placental lactogen-1 and -2 (Pl1 and Pl2) and increased expression of Proliferin (Plf). Reduced numbers of spongiotrophoblasts and glycogen trophoblasts were also found at the junctional zone of the Hectd1 mutant placenta. Finally, there was an increase in immature uterine natural killer (uNK) cells in the maternal decidua of the Hectd1 mutant placenta. Proliferation and apoptosis are differentially altered in the layers of the placenta with an increase in both apoptosis and proliferation in the maternal decidua, a decrease in proliferation and increase in apoptosis in the labyrinth layer and both unchanged in the junctional zone. Together these data demonstrate that Hectd1 is required for development of multiple cell types within the junctional zone of the placenta.

Interferon-γ protects first-trimester decidual cells against aberrant matrix metalloproteinases 1, 3, and 9 expression in preeclampsia

Human extravillous trophoblast (EVT) invades the decidua via integrin receptors and subsequently degrades extracellular matrix proteins. In preeclampsia (PE), shallow EVT invasion elicits incomplete spiral artery remodeling, causing reduced uteroplacental blood flow. Previous studies show that preeclamptic decidual cells, but not interstitial EVTs, display higher levels of extracellular matrix-degrading matrix metalloproteinase (MMP)-9, but not MMP-2. Herein, we extend our previous PE-related assessment of MMP-2 and MMP-9 to include MMP-1, which preferentially degrades fibrillar collagens, and MMP-3, which can initiate a local proteolytic cascade. In human first-trimester decidual cells incubated with estradiol, tumor necrosis factor-α (TNF-α) significantly enhanced MMP-1, MMP-3, and MMP-9 mRNA and protein levels and activity measured by real-time quantitative RT-PCR, ELISA, immunoblotting, and zymography, respectively. In contrast, interferon γ (IFN-γ) reversed these effects and medroxyprogesterone acetate elicited further reversal. Immunoblotting revealed that p38 mitogen-activated protein kinase signaling mediated TNF-α enhancement of MMP-1, MMP-3, and MMP-9, whereas IFN-γ inhibited p38 mitogen-activated protein kinase phosphorylation. Unlike highly regulated MMP-1, MMP-3, and MMP-9, MMP-2 mRNA and protein expression was constitutive in decidual cells. Because inflammation underlies PE-associated shallow EVT invasion, these results suggest that excess macrophage-derived TNF-α augments expression of MMP-1, MMP-3, and MMP-9 in decidual cells to interfere with normal stepwise EVT invasion of the decidua. In contrast, decidual natural killer cell-derived IFN-γ reverses such TNF-α-induced MMPs to protect against PE.

MicroRNAs, immune cells and pregnancy

MicroRNAs (miRNAs) are a recently discovered class of non-coding RNAs that are expressed in many cell types, where they regulate the expression of complementary RNAs, thus modulating the stability and translation of mRNAs. miRNAs are predicted to regulate the expression of ∼50% of all protein coding genes in mammals. Therefore, they participate in virtually all cellular processes investigated so far. Altered miRNAs expressions are associated with both physiological (pregnancy) and pathological processes (cancer). As the dynamic maternal-fetal interface plays a critical role in the maintenance of successful pregnancy, it is not surprising that the miRNAs that are unique to reproductive tissues are abundantly expressed. Research in this field has demonstrated the presence and dysregulation of a distinct set of pregnancy-associated miRNAs; however, most studies have centered on localizing various miRNAs in reproductive microdomains associated with normal or complicated pregnancies. Although several independent miRNA regulatory mechanisms associated with endometrial receptivity, immune cells, angiogenesis and placental development have been studied, miRNA-mediated regulation of pregnancy remains poorly understood. This review provides a summary of the current data on miRNA regulation as well as functional profiles of miRNAs that are found in the uterus, in immune cells associated with maternal tolerance to the fetus, and those involved in angiogenesis and placental development.

The up side of decidual natural killer cells: new developments in immunology of pregnancy

Early phases of human pregnancy are associated with the accumulation of a unique subset of natural killer (NK) cells in the maternal decidua. Decidual NK (dNK) cells that are devoid of cytotoxicity play a pivotal role in successful pregnancy. By secreting large amounts of cytokines/chemokines and angiogenic factors, dNK cells participate in all steps of placentation including trophoblast invasion into the maternal endometrium and vascular remodelling. In this review, we summarize some of dNK cell features and discuss more recent exciting data that challenge the conventional view of these cells. Our new data demonstrate that dNK cells undergo fine tuning or even subvert their classical inhibitory machinery and turn into a real defence force in order to prevent the spread of viruses to fetal tissue. Today it is not clear how these phenotypic and functional adaptations impact cellular cross-talk at the fetal-maternal interface and tissue homeostasis. Ultimately, precise understanding of the molecular mechanisms that govern dNK cell plasticity during congenital human cytomegalovirus infection should lead to the design of more robust strategies to reverse immune escape during viral infection and cancer.

Tumor endothelial marker 1-specific DNA vaccination targets tumor vasculature

Tumor endothelial marker 1 (TEM1; also known as endosialin or CD248) is a protein found on tumor vasculature and in tumor stroma. Here, we tested whether TEM1 has potential as a therapeutic target for cancer immunotherapy by immunizing immunocompetent mice with Tem1 cDNA fused to the minimal domain of the C fragment of tetanus toxoid (referred to herein as Tem1-TT vaccine). Tem1-TT vaccination elicited CD8+ and/or CD4+ T cell responses against immunodominant TEM1 protein sequences. Prophylactic immunization of animals with Tem1-TT prevented or delayed tumor formation in several murine tumor models. Therapeutic vaccination of tumor-bearing mice reduced tumor vascularity, increased infiltration of CD3+ T cells into the tumor, and controlled progression of established tumors. Tem1-TT vaccination also elicited CD8+ cytotoxic T cell responses against murine tumor-specific antigens. Effective Tem1-TT vaccination did not affect angiogenesis-dependent physiological processes, including wound healing and reproduction. Based on these data and the widespread expression of TEM1 on the vasculature of different tumor types, we conclude that targeting TEM1 has therapeutic potential in cancer immunotherapy.

Decidual cell regulation of natural killer cell-recruiting chemokines: implications for the pathogenesis and prediction of preeclampsia

First trimester human decidua is composed of decidual cells, CD56(bright)CD16(-) decidual natural killer (dNK) cells, and macrophages. Decidual cells incubated with NK cell-derived IFN-γ and either macrophage-derived TNF-α or IL-1β synergistically enhanced mRNA and protein expression of IP-10 and I-TAC. Both chemokines recruit CXCR3-expressing NK cells. This synergy required IFN-γ receptor 1 and 2 mediation via JAK/STAT and NFκB signaling pathways. However, synergy was not observed on neutrophil, monocyte, and NK cell-recruiting chemokines. Immunostaining of first trimester decidua localized IP-10, I-TAC, IFN-γR1, and -R2 to vimentin-positive decidual cells versus cytokeratin-positive interstitial trophoblasts. Flow cytometry identified high CXCR3 levels on dNK cells and minority peripheral CD56(bright)CD16(-) pNK cells and intermediate CXCR3 levels on the majority of CD56(dim)CD16(+) pNK cells. Incubation of pNK cells with either IP-10 or I-TAC elicited concentration-dependent enhanced CXCR3 levels and migration of both pNK cell subsets that peaked at 10 ng/mL, whereas each chemokine at a concentration of 50 ng/mL inhibited CXCR3 expression and pNK cell migration. Deciduae from women with preeclampsia, a leading cause of maternal and fetal morbidity and mortality, displayed significantly lower dNK cell numbers and higher IP-10 and I-TAC levels versus gestational age-matched controls. Significantly elevated IP-10 levels in first trimester sera from women eventually developing preeclampsia compared with controls, identifying IP-10 as a novel, robust early predictor of preeclampsia.

Transcription factor Runx3 regulates interleukin-15-dependent natural killer cell activation

Natural killer cells belong to the family of innate lymphoid cells comprising the frontline defense against infected and transformed cells. Development and activation of natural killer cells is highly dependent on interleukin-15 signaling. However, very little is known about the transcription program driving this process. The transcription factor Runx3 is highly expressed in natural killer cells, but its function in these cells is largely unknown. We show that loss of Runx3 impaired interleukin-15-dependent accumulation of mature natural killer cells in vivo and under culture conditions and pregnant Runx3(-/-) mice completely lack the unique population of interleukin-15-dependent uterine natural killer cells. Combined chromatin immunoprecipitation sequencing and differential gene expression analysis of wild-type versus Runx3-deficient in vivo activated splenic natural killer cells revealed that Runx3 cooperates with ETS and T-box transcription factors to drive the interleukin-15-mediated transcription program during activation of these cells. Runx3 functions as a nuclear regulator during interleukin-15-dependent activation of natural killer cells by regulating the expression of genes involved in proliferation, maturation, and migration. Similar studies with additional transcription factors will allow the construction of a more detailed transcriptional network that controls natural killer cell development and function.

Ovarian stimulation affects the population of mouse uterine NK cells at early pregnancy

The aim of this study was to determine the influence of ovarian stimulation on endometrial mouse NK cell population. For superovulation, the female adult NMRI mice were injected i.p. with 10 IU of the pregnant mare serum gonadotropin followed 48 h later by an i.p. injection of 10 IU human chorionic gonadotropin hormone. Ovarian stimulated and nonstimulated mice were mated with fertile male. The presence of vaginal plug proved natural pregnancy, and this day was considered as day one of pregnancy. Tissue samples were prepared from the uterine horn and spleen of both groups of study on 7th day of pregnancy. Serum estradiol-17β and progesterone were measured at the same time. The tissue cryosections were prepared and double stained for CD 161 and CD3 markers, and NK cells population was analyzed. Relative frequency of NK cells was significantly lower in stroma and myometrium in hyperstimulated mice compared with the control group. However, no difference was seen in percentage of NK cells in spleen. The ovarian stimulation influences the proportion of uterine NK cells and may affect the embryo implantation.

Decidual natural killer cell interactions with trophoblasts are impaired in pregnancies at increased risk of preeclampsia

Transformation of the uterine spiral arteries (SAs) during pregnancy is critical to support the developing fetus, and is impaired in some pregnancy disorders, including preeclampsia. Decidual natural killer (dNK) cells play a role in SA remodeling, although their interactions with fetal trophoblast remain unclear. A uterine artery Doppler resistance index (RI) in the first trimester of pregnancy can be used as a proxy measure of the extent of SA remodeling; we have used this technique to characterize dNK cells from pregnancies with normal (normal RI) and impaired (high RI) SA remodeling, which display least and highest risk of developing preeclampsia, respectively. We examined the impact of dNK cell secreted factors on trophoblast motility, chemoattraction, and signaling pathways to determine the contribution of dNK cells to SA transformation. We demonstrated that the chemoattraction of the trophoblast by dNK cells is impaired in pregnancies with high RI, as is the ability to induce trophoblast outgrowth from placental villous explants. These processes are dependent on activation of the extracellular signal-regulated kinase 1/2 and phosphatidylinositol 3-kinase-Akt signaling pathways, which were altered in trophoblasts incubated with secreted factors from dNK cells from high RI pregnancies. Therefore, by characterizing pregnancies using uterine artery Doppler RI before dNK cell isolation, we have identified that impaired dNK-trophoblast interactions may lead to poor placentation. These findings have implications for pregnancy pathological conditions, such as preeclampsia.

Natural killer cells promote immune tolerance by regulating inflammatory TH17 cells at the human maternal-fetal interface

Natural killer (NK) cells accumulate at the maternal-fetal interface in large numbers, but their exact roles in successful pregnancy remain poorly defined. Here, we provide evidence that T(H)17 cells and local inflammation can occur at the maternal-fetal interface during natural allogenic pregnancies. We found that decidual NK cells promote immune tolerance and successful pregnancy by dampening inflammatory T(H)17 cells via IFN-γ secreted by the CD56(bright)CD27(+) NK subset. This NK-cell-mediated regulatory response is lost in patients who experience recurrent spontaneous abortions, which results in a prominent T(H)17 response and extensive local inflammation. This local inflammatory response further affects the regulatory function of NK cells, leading to the eventual loss of maternal-fetal tolerance. Thus, our data identify NK cells as key regulatory cells at the maternal-fetal interface by suppressing T(H)17-mediated local inflammation.

Cellular senescence induced by CD158d reprograms natural killer cells to promote vascular remodeling

Natural killer (NK) cells, which have an essential role in immune defense, also contribute to reproductive success. NK cells are abundant at the maternal-fetal interface, where soluble HLA-G is produced by fetal trophoblast cells during early pregnancy. Soluble HLA-G induces a proinflammatory response in primary, resting NK cells on endocytosis into early endosomes where its receptor, CD158d, resides. CD158d initiates signaling through DNA-PKcs, Akt, and NF-κB for a proinflammatory and proangiogenic response. The physiological relevance of this endosomal signaling pathway, and how activation of CD158d through soluble ligands regulates NK cell fate and function is unknown. We show here that CD158d agonists trigger a DNA damage response signaling pathway involving cyclin-dependent kinase inhibitor p21 expression and heterochromatin protein HP1-γ phosphorylation. Sustained activation through CD158d induced morphological changes in NK cell shape and size, and survival in the absence of cell-cycle entry, all hallmarks of senescence, and a transcriptional signature of a senescence-associated secretory phenotype (SASP). SASP is a program that can be induced by oncogenes or DNA damage, and promotes growth arrest and tissue repair. The secretome of CD158d-stimulated senescent NK cells promoted vascular remodeling and angiogenesis as assessed by functional readouts of vascular permeability and endothelial cell tube formation. Retrospective analysis of the decidual NK cell transcriptome revealed a strong senescence signature. We propose that a positive function of senescence in healthy tissue is to favor reproduction through the sustained activation of NK cells to remodel maternal vasculature in early pregnancy.

Effect of estrogen on rat placental development depending on gestation stage

We examined the sequential histopathological changes in the placenta from rats exposed to estrogen. 17 β-estrogiol-3-benzoate was intraperitoneally administered at 100 μg/animal/day during GD 6 to GD 8 (GD6-8 treated group), GD 9 to GD 11 (GD9-11 treated group) and GD 12 to GD 14 (GD12-14 treated group), and the placentas were sampled on GDs 11, 13, 15, 17, and 21. Fetal mortality rates were increased up to approximately 50% in the GD6-8 and 9-11 treated groups, but there was no change of fetal weight on GD 21. An increase in placental weight and a reduction in fetal/placental weight ratio were detected during GD 17 to GD 21 in the GD6-8 treated group. Histopathologically, hypoplasia of metrial gland was detected with defective development of spiral arteries in the GD6-8 and GD9-11 treated groups. A decrease in the thickness of metrial gland was observed from GD 11 onwards in the GD6-8 treated group and from GD 13 onwards in the GD9-11 treated group. The endovascular trophoblasts invaded into the spiral arteries in the deep part of metrial gland in these treated groups. The number of phospho-histone H3 positive cells was decreased on GD 11 or GD 13 in these groups. In the decidua basalis, transitory necrosis was observed with hemorrhage on GD 13 in the GD6-8 and GD9-11 treated groups. In the labyrinth zone, cystic dilatation of the sinusoid was observed with congestion in the GD6-8 treated group, resulting in an increased placental weight. Therefore, we consider that estrogen inhibits the proliferation of decidualized endometrial stromal cells in the metrial gland, and leads to metrial gland hypoplasia with less development of the spiral arteries. The reduced utero-placental blood flow is supposed to be one of the important factors for poor reproductive performance.

A deficiency in haem oxygenase-1 induces foetal growth restriction by placental vasculature defects

Haem oxygenase-1 (HO-1), the rate-limiting enzyme in haem degradation, plays a role in angiogenesis and vasculogenesis and is highly expressed in the placenta. Deficiencies in HO-1 are associated with several pregnancy disorders, such as recurrent miscarriages and pre-eclampsia. The unique combination of tissue protective, smooth muscle relaxing and angiogenesis regulatory properties makes HO-1 a key player in the maintenance of a healthy pregnancy through a direct effect on placental structural and vascular development, thus affecting foetal development.

CONCLUSION

  Therefore, we conclude that HO-1 plays an important role in placental vasculature development and a deficiency in HO-1 may contribute to pregnancy complications, such as pre-eclampsia, spontaneous abortions and premature births.

Innate immunity, decidual cells, and preeclampsia

Preeclampsia (PE) manifested by hypertension and proteinuria complicates 3% to 8% of pregnancies and is a leading cause of fetal-maternal morbidity and mortality worldwide. It may lead to intrauterine growth restriction, preterm delivery, and long-term sequelae in women and fetuses, and consequently cause socioeconomic burden to the affected families and society as a whole. Balanced immune responses are required for the maintenance of successful pregnancy. Although not a focus of most studies, decidual cells, the major resident cell type at the fetal-maternal interface, have been shown to modulate the local immune balance by interacting with other cell types, such as bone marrow derived-immune cells, endothelial cells, and invading extravillous trophoblasts. Accumulating evidence suggests that an imbalanced innate immunity, facilitated by decidual cells, plays an important role in the pathogenesis of PE. Thus, this review will discuss the role of innate immunity and the potential contribution of decidual cells in the pathogenesis of PE.

Mechanisms of NK cell activation: CD4(+) T cells enter the scene

Natural killer (NK) cells are innate lymphocytes involved in immunosurveillance through their cytotoxic activity and their capacity to secrete inflammatory cytokines. NK cell activation is necessary to initiate effector functions and results from a complex series of molecular and cellular events. We review here the signals that trigger NK cells and discuss recent findings showing that, besides antigen-presenting cells, T cells can play a central role in the initiation of NK cell activation in lymph nodes.

Effect of cisplatin on rat placenta development

We examined the sequential histopathological changes in the placenta from rats exposed to cisplatin. Cisplatin was intraperitoneally administered at 2 mg/kg/day during GDs 11-12 (GD11,12-treated group), or GDs 13-14 (GD13,14-treated group), and the placentas were sampled on GDs 13, 15, 17 and 21. Fetal mortality rates were increased up to approximately 65% from GD 17 onward, and fetal weights were decreased on GD 21 in the GD11,12-treated group. A reduction in placental weights was detected from GD 15 onward, and the placentas on GD 21 were macroscopically small and thin in both treated groups. Histopathologically, in the GD13,14-treated group, an increase in apoptotic cells was detected on GDs 15 and 17 in the labyrinth zone, and on GD 21 in the basal zone, resulting in labyrinth zone hypoplasia. By contrast, in the GD11,12-treated group, an increase in apoptotic cells was detected on GDs 13, 15 and 17 in the labyrinth zone, and during the experimental period in the basal zone. A decrease in Phospho-Histone H3 positive cells was detected on GD 13 in the labyrinth zone and basal zone, resulting in hypoplasia of the labyrinth zone and basal zone. In addition, a marked decrease in glycogen cell-islands in the basal zone was also detected on GDs 15 and 17. There was a reduction in interstitial invasion of glycogen cell-like trophoblasts into the metrial gland on GD 15, resulting in metrial gland hypoplasia. Therefore, we consider that cisplatin administration in pregnant rats induces growth arrest of the labyrinth zone and basal zone, leading to small placenta. It is assumed that metrial gland hypoplasia is secondarily induced by the failure of glycogen cell island development associated with basal zone hypoplasia.

Origin, phenotype and function of human natural killer cells in pregnancy

During the early phases of pregnancy, natural killer (NK) cells are the predominant lymphoid cells in the human decidua. Here, rather than act as killers and/or drivers of inflammation, NK cells contribute to tissue building and remodeling and formation of new vessels due to the release of interleukin-8, vascular endothelial growth factor, stromal cell-derived factor-1 and interferon gamma-inducible protein-10. Here, we propose that the interaction of NK cells with CD14(+) myelomonocytic cells to promote induction of T regulatory cells plays a pivotal role in immunosuppression and tolerance towards the fetus allograft. Importantly, CD34(+) hematopoietic precursors are present in human decidua and may give rise to decidual NK cells. Defects in decidual NK cell generation, or in appropriate functional interactions with other cell types, could have major consequences for successful pregnancy.

Maternal heme oxygenase 1 regulates placental vasculature development via angiogenic factors in mice

The placental vasculature is critical for nutrient, gas, and waste exchange between the maternal and fetal systems. Its development depends on the proper expression and interaction of angiogenesis and associated growth factors. Heme oxygenase (HMOX), the enzyme for heme degradation, plays a role in angiogenesis and is highly expressed in the placenta. To evaluate the role of maternal HMOX1, the inducible HMOX isozyme, on placental vasculature formation, mice with a partial deficiency in Hmox1 (Hmox1(+/-)) were used. Three-dimensional images of placental vasculatures as well as spiral arteries from Hmox1(+/+) or Hmox1(+/-) placentas were created by vascular corrosion casting technique and imaged by micro-computerized tomography (microCT). The structures and morphologies of fetomaternal interfaces were observed by histological staining and the ultrastructure of uterine natural killer (uNK) cells, a major regulator in spiral artery remodeling, was analyzed by transmission electron microscopy. A group of growth factors and angiogenic factors from the decidua/mesometrial lymphoid aggregate of pregnancy (MLAp) as well as labyrinth regions were quantified using an angiogenesis PCR array kit and compared between Hmox1(+/+) or Hmox1(+/-) placentas. In conclusion, a partial deficiency of maternal Hmox1 resulted in the malformation of fetomaternal interface, insufficiency of spiral artery remodeling, and alteration of uNK cell differentiation and maturation. These changes were independent of the fetal genotype, but relied on the maternal HMOX1 level, which determined the balance of expression levels of pro- and antiangiogenic factors in the decidua/MLAp region. These results implied that Hmox1 polymorphisms among the human population might contribute to some unexplained cases of pregnancy disorders, such as fetal growth retardation and preeclampsia.

Toxicological pathology in the rat placenta

The placenta grows rapidly for a short period with high blood flow during pregnancy and has multifaceted functions, such as its barrier function, nutritional transport, drug metabolizing activity and endocrine action. Consequently, the placenta is a highly susceptible target organ for drug- or chemical-induced adverse effects, and many placenta-toxic agents have been reported. However, histopathological examination of the placenta is not generally performed, and the placental toxicity index is only the placental weight change in rat reproductive toxicity studies. The placental cells originate from the trophectoderm of the embryo and the endometrium of the dam, proliferate and differentiate into a variety of tissues with interaction each other according to the development sequence, resulting in formation of a placenta. Therefore, drug- or chemical-induced placental lesions show various histopathological features depending on the toxicants and the exposure period, and the pathogenesis of placental toxicity is complicated. Placental weight assessment appears not to be enough to evaluate placental toxicity, and reproductive toxicity studies should pay more attention to histopathological evaluation of placental tissue. The detailed histopathological approaches to investigation of the pathogenesis of placental toxicity are considered to provide an important tool for understanding the mechanism of teratogenicity and developmental toxicity with embryo lethality, and could benefit reproductive toxicity studies.

How does variability of immune system genes affect placentation?

Formation of the placenta is a crucial step in mammalian pregnancy. Apart from its function in ensuring an optimal supply of nutrients and oxygen to the fetus, the placenta is also the interface at which allo-recognition of invading trophoblast cells by the maternal immune system can potentially occur. We summarise here the “state of the art” on how variability of immune system genes that code for major histocompatibility complex (MHC) molecules and natural killer receptors (NKR) may impact on human placentation. MHC and NKR are the most polymorphic human genes. Our recent reports point out that specific combinations of fetal MHC and maternal NKR genes in humans correlate with the risk of pre-eclampsia, recurrent miscarriage (RM) and fetal growth restriction (FGR). Research in this field is still at an early stage and future studies in mouse and humans will be needed before the results can be translated to clinical applications. We discuss our recent work, as well as the opportunities offered by mouse genetics, to understand the cellular and molecular mechanisms underlying immune interactions at the maternal-fetal interface.

The impairment of metrial gland development in tamoxifen exposed rats

We examined the sequential histopathological changes in the placenta from rats exposed to tamoxifen. Tamoxifen was administered intraperitoneally at doses of 0 and 2 mg/kg/day on gestation days (GDs) 8, 9 and 10, and the placentas were sampled on GDs 11, 13, 15, 17, and 21. The fetal mortality rates in the tamoxifen group were increased up to 56%. However, there were no effects on the weights of live embryos/fetuses and their placentas. Histopathologically, the size of metrial gland in the tamoxifen group was reduced on all sampling times. The spiral arteries appeared less well developed in the hypoplastic metrial gland. A decrease in uterine natural killer (uNK) cells and mitotic uNK cells around the spiral arteries in the metrial gland was detected from GD 13 onward and on GDs 11 and 13, respectively. There were no obvious changes in the labyrinth zone or basal zone. We consider that the anti-estrogen effect of tamoxifen inhibits the proliferation of decidualized endometrial stromal cells in the metrial gland and leads to inhibition of the proliferative activity of uNK cells, followed by defective development of spiral arteries, and metrial gland hypoplasia. It is assumed that the metrial gland hypoplasia might be involved in the tamoxifen-induced embryo/fetus-toxicity.

Spatiotemporal patterns of macrophage migration inhibitory factor (Mif) expression in the mouse placenta

BACKGROUND

Macrophage migration inhibitory factor (MIF) has special pro-inflammatory roles, affecting the functions of macrophages and lymphocytes and counter-regulating the effects of glucocorticoids on the immune response. The conspicuous expression of MIF during human implantation and early embryonic development also suggests this factor acts in reproductive functions. The overall goal of this study was to evaluate Mif expression by trophoblast and embryo placental cells during mouse pregnancy.

METHODS

Mif was immunolocalized at implantation sites on gestation days (gd) 7.5, 10.5, 13.5 and 17.5. Ectoplacental cones and fetal placentas dissected from the maternal tissues were used for Western blotting and qRT-PCR assays on the same gestation days.

RESULTS

During the post-implantation period (gd7.5), trophoblast giant cells showed strong Mif reactivity. In later placentation phases (gds 10.5-17.5), Mif appeared to be concentrated in the junctional zone and trophoblast giant cells. Mif protein expression increased significantly from gd7.5 to 10.5 (p = 0.005) and from gd7.5 to 13.5 (p = 0.03), remaining at high concentration as gestation proceeded. Higher mRNA expression was found on gd10.5 and was significantly different from gd13.5 (p = 0.048) and 17.5 (p = 0.009).

CONCLUSIONS

The up-regulation of Mif on gd10.5 coincides with the stage in which the placenta assumes its three-layered organization (giant cells, spongiotrophoblast and labyrinth zones), fetal blood circulation begins and population of uNK cells reaches high proportions at the maternal counter part of the placenta, suggesting that Mif may play a role in either the placentation or in the adaptation of the differentiated placenta to the uterus or still in gestational immunomodulatory responses. Moreover, it reinforces the possibility of specific activities for Mif at the maternal fetal interface.

Hormonal regulation of uterine natural killer cells in mouse preimplantation uterus

Uterine Natural Killer (uNK) cells are the most abundant lymphocyte population recruited in the uteri during murine and human pregnancy. Previous investigation on uNK cells during mouse pregnancy focused more on its accumulation in postimplantation periods, which were believed to play important roles in regulating trophoblast invasion and angiogenesis towards successful placentation. However, by using recently developed methods of Dolichos biflorus agglutinin (DBA) lectin, a closer examination during mouse preimplantation revealed that there were also dynamic regulations of uNK cell, suggesting a major regulation by steroid hormones. Here we provide a detailed examination of uNK cells distribution during mouse early pregnancy by DBA lectin reactivity, with emphasis on preimplantation period and its hormonal regulation profiles. Our results showed that uNK precursor cells or its cell membrane specific components could be recruited in the uterus by estrogen or/and progesterone, and the effects could be completely abolished by specific antagonists of their nuclear receptors (estrogen and progesterone receptor). These results suggested that the preimplantation uterus, through concerted hormone regulation, could recruit uNK precursor cell or its specific cellular component, which might be conducive for uterine receptivity and further uNK construction/function during postimplantation.

Natural Killer cells: keepers of pregnancy in the turnstile of the environment

During early pregnancy, an orchestrated endocrine-immunological scenario of maternal adaptation toward tolerance of the semiallogeneic fetus is required. Mechanisms preventing fetal loss by protecting the immune privilege of the gravid uterus, i.e. Galectin-1 or regulatory T cells, have recently been identified. Further, the presence of a unique population of Natural Killer (NK) cells, in humans identified by their CD56(+++)Galectin (Gal)-1(+)CD16(-) phenotype in the uterine lining (decidua), has been proposed to be a pivotal aspect of maternal adaptation to pregnancy. Decidual NK (dNK) cells comprise the largest population of immune cells during the first trimester in human decidua and control trophoblast invasion and vascular remodeling through their ability to secrete an array of angiogenesis-regulating molecules, chemokines and cytokines. A wealth of environmental factors, such as smoking, altered nutrition, pollution or stress has been proposed to peril not only pregnancy, but also fetal development. Further, published evidence supports that NK cells act as sentinel cells and environmental challenges can change their phenotype, e.g. via epigenetic pathways. We here review the effect of environmental factors, largely stress perception, on NK cells and its implication for pregnancy, fetal development and general health. As NK cells may not only be passive responders to the environment, but can also be 'educated and licensed', we propose novel strategies aiming to take advantage of the versatility of NK cells in maintaining immunosurveillance and tissue homeostasis.

Do molecular signals from the conceptus influence endometrium decidualization in rodents?

A critical period in establishing pregnancy occurs after the onset of implantation but before placental development. Evidence strongly suggests that abnormalities occurring during this period can result in pregnancy termination or in pre-eclampsia; the latter may lead to small-for-gestational-weight offspring that are likely to be unhealthy. Clearly, events occurring in the endometrium during the implantation process are crucial for proper fetal development and for optimal offspring health. In several mammalian species bi-directional communication between the conceptus and endometrium during implantation is required for successful pregnancy. Although different implantation and placentation modes occur in different mammalian species, common aspects of this bi-directional signaling may exist. The molecular signals from the trophoblast cells of the conceptus, which direct endometrial changes during implantation progression, are well known in some nonrodent species. Currently, we know little about such signaling in rodents during implantation progression, when the endometrium undergoes decidualization. This review focuses on data that support the hypothesis that paracrine signals from the rodent conceptus influence decidualization. Where possible, these findings are compared and contrasted with information currently known in other species that exhibit different implantation modes.

Preeclampsia--a placenta developmental biology perspective

There are abundant theories in the scientific literature that propose a range of pathophysiological pathways for preeclampsia. In this review we discuss some of the contributions made to this field from the perspective of a placental developmental biology laboratory. We discuss an underlying immune component of preeclampsia associated with expression of HLA-G and also a beneficial function of decidual NK cells. We conclude by summarizing newer findings regarding the anti-angiogenic expression of soluble fms-like tyrosine kinase (sFlt-1) and its role in the development of preeclampsia.

Dermatan sulfate proteoglycan biglycan as a potential selectin L/CD44 ligand involved in selective recruitment of peripheral blood CD16(-) natural killer cells into human endometrium

Unique CD16(-) NK cells acutely increase in the human uterine endometrium after ovulation. The origin of these NK cells remains unknown, but they may be recruited selectively from the circulation. Proteoglycans and their glycosaminoglycan side-chains expressed on endometrial microvascular endothelial cells play a key role in lymphocyte tethering/rolling, the initial step of lymphocyte extravasation. In this study, we sought for the potential proteoglycans involved in tethering/rolling of peripheral blood CD16(-) NK cells on endometrial microvascular endothelial cells. As compared with CD16(+) NK cells and non-NK cells, enriched peripheral blood CD16(-) NK cells bound preferably to immobilized glycosaminoglycans except for keratan sulfate. CD16(-) NK cells bound maximally to dermatan sulfate (DS), which was diminished by enzymatic pretreatment with dermatanase and chondroitinase ABC, but not with chondroitinase ACII. The binding capacity of CD16(-) NK cells to DS was attenuated by blocking antibodies against selectin L and CD44 or pretreatment of CD16(-) NK cells with IL-15. Of three known DS proteoglycans, biglycan and decorin but not epiphycan were expressed in the human cycling endometrium. In the endometrial microvessels, the immunoreactivity for biglycan was greater in the secretory phase than in the proliferative phase, and there was little, if any, immunoreactivity for decorin throughout the menstrual cycle. The ovarian steroid progesterone enhanced biglycan expression in cultured human uterine microvascular endothelial cells. These findings demonstrated that DS proteoglycan biglycan is a potential selectin L/CD44 ligand involved in tethering/rolling of peripheral blood CD16(-) NK cells on endometrial microvascular endothelial cells.

NKT cells at the maternal-fetal interface

Establishment of the maternal-fetal interface is characterized by the influx of maternal NK cells, macrophages, and T cells into the decidua. Although a great deal has been learned about the function of NK cells in the decidua, comparatively little is known of decidual T cell function. NKT cells are an unusual T cell subset capable of producing both Th1-like and Th2-like cytokines. Unlike conventional alphabeta T cells that recognize peptides in the context of MHC molecules, NKT cells recognize glycolipids presented by the MHC class I-like molecule, CD1d. Recent reports have demonstrated that NKT cells and CD1d are present at the maternal-fetal interface. Moreover, activation of NKT cells can have dramatic effects on pregnancy. In this article, we will review basic aspects of NKT cell biology and summarize the recent literature on NKT cells at the maternal-fetal interface.

Deviations in populations of peripheral blood mononuclear cells and endometrial macrophages in the cow during pregnancy

The presence of conceptus alloantigens necessitates changes in maternal immune function. Here, we used the cow to evaluate whether species with epitheliochorial placentation have changes in specific leukocyte populations during pregnancy similar to those reported in species with hemotropic placentae. At days 33–34 of pregnancy, there was no effect of pregnancy status on the number of cells positive for CD8, CD4, γδT cell receptor, or the monocyte marker CD68 in the peripheral blood mononuclear cell (PBMC) population. There was, however, an increase in the proportion of CD4+cells that were positive for CD25. There was no effect of status on the proportion of PBMCs that were CD8+when comparing preparturient cows to nonpregnant cows. However, preparturient cows had an increased percentage of PBMCs that were γδT cells and CD4+CD25+and a tendency for a lower percentage that were CD68+cells. Using immunolocalization with anti-CD68, it was found that pregnant cows had increased numbers of CD68+cells in the endometrial stroma as early as days 54–100 of gestation; this increase persisted through the last time examined (day 240 of gestation). Cells positive for CD68 were also positive for another macrophage/monocyte marker, CD14. In conclusion, pregnancy in the cow is associated with changes in peripheral and endometrial leukocyte numbers, which are similar to patterns observed in other species.