Prognostic role of indoleamine 2,3-dioxygenase in endometrial carcinoma

Objective

Indoleamine-2,3-dioxygenase (IDO) suppresses the function of T-lymphocytes and is an important immune escape mechanism for cancer. Therefore, it is to be expected that IDO influences prognosis of cancer patients. This study aimed to investigate the prognostic role of IDO expression in a large cohort of endometrial carcinoma (EC) patients.

Methods

A tissue microarray containing primary EC tissue of 355 patients treated in a single institution was used to evaluate IDO expression. Expression of IDO was associated with clinicopathological characteristics, survival and previously determined numbers of CD8⁺ and Foxp3⁺ T-lymphocytes.

Results

IDO^high expression was associated with lower numbers of intratumoral CD8⁺ T-lymphocytes (p = 0.031). Next to well-known prognostic parameters, IDO^high expression was independently associated with poor disease specific survival in the general cohort of EC patients (HR 2.62, 95% C.I. 1.48-4.66, p = 0.001) and among patients with early stage EC (HR 3.06, 95% C.I. 1.10-8.54, p = 0.032).

Conclusion

Our results show that IDO expression is associated with poor survival. This provides evidence that further research into the use of IDO blocking agents in cancer treatment is valid where it might be a promising new therapeutic strategy.     

Immunosuppression by placental indoleamine 2,3-dioxygenase: a role for mesenchymal stem cells

BACKGROUND/OBJECTIVES: Mesenchymal stem cells (MSC) can be isolated from human placenta and have the potential to contribute to the immunosuppressive properties of placental tissue. The objectives of this study were to investigate the phenotype and differentiation characteristics of MSC derived from human placenta and evaluate the role of the tryptophan degrading enzyme, indoleamine 2,3 dioxygenase (IDO), in mediating their immunosuppressive affect. METHODS: MSC obtained from placental tissue (pMSC) were characterised using flow cytometry and tested for multipotency by determining differentiation into all mesenchymal lineages. The immunosuppressive properties of pMSC were tested in allogeneic mixed lymphocyte reactions and IDO expression and activity were measured by semi-quantitative real-time PCR and HPLC respectively. RESULTS: Multipotent stem cells were isolated from placenta and displayed chondrogenic, osteogenic and limited adipogenic differentiation. Cell surface antigen expression of pMSC was similar to bone marrow MSC (bMSC) with lack of the haematopoietic and common leukocyte markers (CD34, CD45), and expression of adhesion (CD29, CD166, CD44) and stem cell (CD 90, CD105, CD73) markers. Placental MSC were suppressive of allogeneic T-cell proliferation, an effect which was intensified following IDO induction by IFN-gamma. Replenishment of tryptophan or treatment with the IDO-blocker, 1-methyl-tryptophan (1-MT), attenuated the immunosuppressive action of pMSC. CONCLUSIONS: These results suggest that placental tissue contains MSC, which are phenotypically and functionally similar to bMSC, and that IDO is a key mediator of their immunosuppressive effect. Further investigation is needed to determine if pMSC function effects pregnancy outcome.     

Indoleamine 2,3-dioxygenase: distribution and function in the developing human placenta

Studies in mice have suggested that the placenta is protected from immune rejection by maternal T cells by means of localised indoleamine 2,3-dioxygenase dependent depletion of tryptophan. To determine whether such mechanisms might operate in the human placenta, we have studied the physiological importance of human placental indoleamine 2,3-dioxygenase immunohistochemically and functionally. Indoleamine 2,3-dioxygenase is detectable immunohistochemically from day 6 human blastocysts and thereafter throughout pregnancy in syncytiotrophoblasts, extravillous cytotrophoblasts and macrophages in the villous stroma and in the fetal membranes. Interferon-gamma added to villous explants markedly stimulates indoleamine 2,3-dioxygenase protein expression in macrophages. Indoleamine 2,3-dioxygenase-mediated tryptophan degradation in the first trimester villous and decidual tissue explants is stimulated by interferon-gamma and inhibited by 1-methyl-tryptophan (an inhibitor of indoleamine 2,3-dioxygenase). Peripheral blood mononuclear cell proliferation is controlled by indoleamine 2,3-dioxygenase-mediated tryptophan degradation. These results suggest the cellular basis of a mechanism present at the human maternal-fetal interface involved in regulating the maternal immune response to conceptus.     

Expression of indoleamine 2,3-dioxygenase in the rhesus monkey and common marmoset

Indoleamine 2,3-dioxygenase (IDO) catalyzes the initial and rate-limiting step of tryptophan degradation along the kynurenine pathway, and is hypothesized to limit tryptophan availability at embryo implantation and prevent maternal T cell activation at the maternal–fetal interface. To determine if nonhuman primates are suitable models for investigating the role of IDO during pregnancy, we defined the expression of IDO in the rhesus monkey and common marmoset with particular attention to the female reproductive tract and placenta. IDO mRNA was detected by RT-PCR in the rhesus monkey term placenta, lung, small intestine, spleen, lymph node and nonpregnant uterus, and also in the common marmoset placenta. Immunohistochemical analysis of rhesus monkey tissues localized IDO to glandular epithelium of nonpregnant endometrium and first trimester decidua, vessel endothelium of nonpregnant myometrium, first trimester decidua and term decidua, and villous vessel endothelium and syncytiotrophoblast of term placenta. Western blot analysis confirmed IDO in rhesus monkey term placenta. In the common marmoset, IDO was detected in glandular epithelium of the nonpregnant uterus and in the decidua at day 60 and day 128 of gestation. IDO activity was higher in rhesus monkey and common marmoset decidua and placentas than in other tissues. Confirmation of IDO expression in rhesus monkey and common marmoset uterine and placental tissues supports the hypothesis that this enzyme regulates immune activation at the maternal–fetal interface and demonstrates that nonhuman primates may provide models with distinct similarities to human placentation to study the role of IDO in maternal–fetal immune dialogue.     

Expression of indoleamine 2,3-dioxygenase in the rhesus monkey and common marmoset

Indoleamine 2,3-dioxygenase (IDO) catalyzes the initial and rate-limiting step of tryptophan degradation along the kynurenine pathway, and is hypothesized to limit tryptophan availability at embryo implantation and prevent maternal T cell activation at the maternal-fetal interface. To determine if nonhuman primates are suitable models for investigating the role of IDO during pregnancy, we defined the expression of IDO in the rhesus monkey and common marmoset with particular attention to the female reproductive tract and placenta. IDO mRNA was detected by RT-PCR in the rhesus monkey term placenta, lung, small intestine, spleen, lymph node and nonpregnant uterus, and also in the common marmoset placenta. Immunohistochemical analysis of rhesus monkey tissues localized IDO to glandular epithelium of nonpregnant endometrium and first trimester decidua, vessel endothelium of nonpregnant myometrium, first trimester decidua and term decidua, and villous vessel endothelium and syncytiotrophoblast of term placenta. Western blot analysis confirmed IDO in rhesus monkey term placenta. In the common marmoset, IDO was detected in glandular epithelium of the nonpregnant uterus and in the decidua at day 60 and day 128 of gestation. IDO activity was higher in rhesus monkey and common marmoset decidua and placentas than in other tissues. Confirmation of IDO expression in rhesus monkey and common marmoset uterine and placental tissues supports the hypothesis that this enzyme regulates immune activation at the maternal-fetal interface and demonstrates that nonhuman primates may provide models with distinct similarities to human placentation to study the role of IDO in maternal-fetal immune dialogue.     

Localization of indoleamine 2,3-dioxygenase and 4-hydroxynonenal in normal and pre-eclamptic placentae

This study was undertaken to compare placental levels of 2,3-Dioxygenase (IDO), a free radical scavenger, and 4-Hydroxynonenal (4-HNE), a major by-product of lipid peroxidation, in normal and pre-eclamptic pregnancies. Placentae were collected at caesarean section from women with a term, normal singleton pregnancy (37-40 weeks' gestation, n=10) and women with a term singleton pregnancy complicated by pre-eclampsia (n=10). IDO and 4-HNE localization and intensity was studied by semi-quantitative immunohistochemistry and differences between groups were analysed using the Mann-Whitney U test. Immunostaining for IDO was located primarily in endothelial cell nuclei, with a reduced level of staining in the cytoplasm, in most capillaries from all placentae examined. A significantly higher level of IDO immunostaining was observed in normal placentae compared to pre-eclamptic placentae (P=0.008). 4-HNE was located mainly in the cytoplasm of syncytiotrophoblast cells of all placentae examined. There were no significant differences in the pattern or intensity of 4-HNE immunostaining levels between normal and pre-eclamptic pregnancies (P=0.684). Our IDO results support the hypothesis of decreased anti-oxidative capability in the placenta and the possibility of an ineffective compensatory mechanism against increased oxidative stress in the fetus.     

Pathophysiology of placenta creta: the role of decidua and extravillous trophoblast

Placenta creta is associated with massive postpartum hemorrhage and commonly leads to emergency hysterectomy. While the exact pathogenesis of placenta creta is unknown, proposed hypotheses include a primary deficiency of decidua, abnormal maternal vascular remodeling, excessive trophoblastic invasion, or a combination thereof. To assess these changes in placenta creta, we retrospectively reviewed 49 cases of gravid hysterectomy, 38 with and 11 without the diagnosis of creta, gathered clinical data, and evaluated histopathology of extravillous trophoblast. Specifically, we evaluated maternal vessels for remodeling by endovascular trophoblast, as well as the morphology and depth of invasion of interstitial trophoblast at the implantation site. Compared to controls, cases with creta had decreased proportion of remodeled vessels, with many vessels displaying partial physiologic change. Cases with creta also demonstrated vascular remodeling deeper in the myometrium; however, vascular remodeling of large outer myometrial vessels was only demonstrated in increta and percreta cases, and was absent in both non-creta and accreta. As previously reported, interstitial trophoblast invaded the uterine wall to a significantly greater depth in placenta creta; however, there was no significant difference between creta subtypes. Finally, Ki-67 staining was rarely observed in extravillous trophoblast, except in the trophoblast columns of first trimester creta cases. We, therefore, conclude that the pathogenesis of placenta creta is multi-dimensional, involving increased, but incomplete trophoblast invasion in a background of absent decidua. We further propose that placenta increta and percreta are not due to a further invasion of extravillous trophoblast in the uterine wall, rather they likely arise secondary to dehiscence of a scar, leading to the presence of chorionic villi deep within the uterine wall, and thus give extravillous trophoblast greater access to the deep myometrium.     

Coding region polymorphisms in the indoleamine 2,3-dioxygenase (INDO) gene and recurrent spontaneous abortion

Indoleamine 2,3-dioxygenase (INDO) catalyzes degradation of the indole ring of indoleamines and locally depletes tryptophan. INDO expression suppresses T cell proliferation and activation. Genetic variation in the INDO gene may contribute to the variable INDO enzyme expression, activity and severity of some diseases. Recurrent spontaneous abortion (RSA) is a common pregnancy complication and the exact causes of RSA are not yet known. We performed an association study between INDO single nucleotide polymorphisms (SNPs) and RSA. To identify INDO SNPs we sequenced DNA samples for ten exons and adjacent intronic regions from 111 RSA patients. Consequently 10 SNPs were detected; four in exons (one in exon 4, two in exon 9 and one in exon 10) and six in intronic regions (one in intron 3, three in intron 6, one in intron 8 and one in intron 9). Three (IVS3+562 del C, IVS8+116 T→G and IVS9+2431 G→A) of these ten SNPs have been registered at the NCBI SNP database. Statistical analysis of allele, genotype and haplotype frequency distribution in the three most frequent SNPs (IVS3+562 del C, IVS6+61 G→A and IVS9+2431 G→A) showed no significant differences between the 111 RSA and 105 matched control women. CGA and CGG were the most frequent haplotypes in both the RSA and control groups. We conclude that there is no association between INDO polymorphisms and susceptibility of Iranian women to RSA.     

Localisation of glucose transport in the ruminant placenta: implications for sequential use of transporter isoforms

The facilitative glucose transporters 1 and 3 are the major routes for glucose transport across placental membranes. Using light and electron microscope immunocytochemistry on acrylic sections this study shows a similar pattern of expression from mid to late pregnancy in all four ruminants examined [cow, deer, ewe and goat]. GT1 and GT3 are localised on different membrane layers of the synepitheliochorial placental barrier and glucose must utilise both isoforms sequentially to pass from the maternal to fetal circulations. It is suggested that this arrangement is designed to support the high glucose utilisation by the multilayered placenta in the ruminant.     

Identification of kynurenine pathway enzyme mRNAs and metabolites in human placenta: up-regulation by inflammatory stimuli and with clinical infection

OBJECTIVE: The purpose of this study was to determine whether placental-derived kynurenines (neuroactive metabolites that are derived from tryptophan) contributes to infection-mediated fetal cerebral injury. STUDY DESIGN: Placentae and cord blood were obtained from term deliveries (n = 16) and preterm deliveries with or without intrauterine bacterial infection (n = 8 per group). We investigated whether the placenta expressed messenger RNAs of kynurenine metabolite-forming enzymes, the effects of infection in vivo on the expression of these enzymes by the placenta, the in vitro effects of bacterial endotoxin lipopolysaccharide on expression and kynurenine metabolite output by the placenta, and the kynurenine metabolite levels in umbilical cord blood. RESULTS: Placentae expressed messenger RNA of tryptophan-degrading enzymes and synthesized several compounds. The expression of several enzymes increased significantly in placentae that were exposed to infection and/or lipopolysaccharide. Lipopolysaccharide also induced significant increases in placental kynurenine and quinolinic acid output. Kynurenine and quinolinic acid in cord blood of fetuses who were exposed to infection were elevated significantly. CONCLUSION: Inflammatory mediated release of kynurenines from placentae exposes the fetus to significant amounts of potentially neurotoxic substances.     

Review: A high capacity of the human placenta for genetic and epigenetic variation: implications for assessing pregnancy outcome

Genetic and epigenetic studies of the human placenta can help to clarify the underlying mechanisms of placenta-associated diseases. However, such studies have also revealed a considerable degree of within- and between-placenta variability, which can be attributed to a variety of influences. We illustrate the inherent heterogeneity in the placenta using examples from two types of studies: 1) chromosomal mosaicism and 2) DNA methylation variation. We discuss the factors that may influence the distribution of variation and how, understanding the source of this variation is important for interpreting data used to investigate and predict clinical outcomes.     

Heparan sulfate proteoglycans in the basement membranes of the human placenta and decidua

Basement membranes lie at the epithelial-mesenchymal interface of most tissues. These thin layers of highly specialized extracellular matrix vary in composition in different tissues and also over the course of tissue morphogenesis. Heparan sulfate proteoglycans, which were originally identified in basement membranes, interact with extracellular matrix proteins, growth factors and cell receptors, and influence cellular signaling. Members of this family in the human placenta and decidua that act principally in linking to collagen IV and laminin networks include perlecan, agrin, and collagen XVIII, each of which have characteristic locations. Perlecan is widely expressed in trophoblasts, the villous and endothelial basement membranes, villous stroma, and decidua, whereas collagen XVIII is not expressed in trophoblasts. Agrin expression is quite limited, occurring only in the decidua and villous stroma. Pathological conditions may alter the expression and structure of the covalently attached glycosaminoglycan chains of these molecules in the placenta. Such changes may result in remodeling of the basement membrane during placental development with consequent adverse effects, as seen for example in gestational diabetes and other diseases or experimental models.     

Localization of 15-hydroxy prostaglandin dehydrogenase in human fetal membranes, decidua, and placenta during pregnancy.

Localization of NAD(+)-dependent 15-hydroxy prostaglandin dehydrogenase (type I-PGDH) may influence local concentrations of bioactive eicosanoids within intrauterine tissues. In early pregnancy (6-9 weeks), IR-PGDH was localized by immunohistochemistry to syncytiotrophoblast, cytotrophoblast, and intermediate trophoblast of placenta. At 23-30 weeks of gestation and at term IR-PGDH was present in syncytiotrophoblast and intermediate trophoblast, but not in cytotrophoblast in placenta. It was absent from amnion, and distributed within the trophoblast cell layer of extraplacental chorion variably at 23-30 weeks, but consistently at term. We speculate that PGDH is ideally localized to metabolize and to maintain low concentrations of primary prostaglandins in the fetal membranes for much of gestation.     

早孕蜕膜组织淋巴细胞在妊娠中的作用

目的 探讨子宫内膜局部免疫细胞在妊娠中的作用,方法 采用免疫组化技术和原位杂交技术,研究２０例正常孕妇的早孕蜕膜组织内淋巴细胞的分布,表型特征及穿孔素蛋白和ｍＲＮＡ的表达。结果 早孕蜕膜组织内Ｔ总淋巴细胞（ＣＤ３淋巴细胞）抑制或杀伤了Ｔ淋巴细胞（ＣＤ８淋巴细胞）较少,约占３％,辅助Ｔ淋巴细胞（ＣＤ４淋巴细胞）极少,甚至看不到,早孕蜕膜组织内大部分淋巴细胞为表达穿孔素的自然杀伤样细胞ＣＤ（５６非典型     

Review: Functional role of uterine natural killer (uNK) cells in human early pregnancy decidua

Leukocytes comprise approximately 30–40% of decidual stromal cells in early human pregnancy. The major leukocyte component is the uterine natural killer (uNK) cells. Despite over 20 years of research the functional role of these cells in situ remains unknown although they have been proposed to play roles in immunotolerance, regulation of trophoblast invasion and remodeling of the spiral arteries. Herein we review the functional roles of this important decidual cell type.