l-Tryptophan-Induced Vasodilation Is Enhanced in Preeclampsia: Studies on Its Uptake and Metabolism in the Human Placenta

l-tryptophan induces IDO (indoleamine 2,3-dioxygenase) 1-dependent vasodilation. IDO1 is expressed in placental endothelial cells and downregulated in preeclampsia. Hypothesizing that this may contribute to diminished placental perfusion, we studied l-tryptophan-induced vasodilation in healthy and early-onset preeclampsia placental arteries, focusing on placental kynurenine pathway alterations. Despite IDO1 downregulation, kynurenine pathway metabolite concentrations (measured with ultra-performance liquid chromatography-tandem mass spectrometry) were unaltered in preeclamptic versus healthy placentas. Most likely, this is due to enhanced l-tryptophan uptake, evidenced by increased l-tryptophan levels in preeclamptic placentas. Ex vivo perfused cotyledons from healthy and preeclamptic placentas released similar amounts of l-tryptophan and kynurenine pathway metabolites into the circulations. This release was not altered by adding l-tryptophan in the maternal circulation, suggesting that l-tryptophan metabolites act intracellularly. Maternally applied l-tryptophan did appear in the fetal circulation, confirming placental passage of this essential amino acid. After in vitro incubation of placental arteries with IDO1-upregulating cytokines interferon-γ and tumor necrosis factor-α, l-tryptophan induced vasodilation. This vasodilation was attenuated by both IDO1 and nitric oxide (NO) synthase inhibitors. Despite IDO1 downregulation, l-tryptophan-induced relaxation was enhanced in preeclamptic versus healthy placental arteries. However, cytokine stimulation additionally upregulated the LAT (l-type amino acid transporter) 1 in preeclamptic placental arteries only. Vasodilation to the lipophilic, transporter independent ethyl ester of l-tryptophan was reduced in preeclamptic versus healthy placental arteries, in agreement with reduced IDO1 expression. In conclusion, l-tryptophan induces IDO1- and NO-dependent relaxation in placental arteries, which is determined by l-tryptophan uptake rather than IDO1 expression. Increased l-tryptophan uptake might compensate for reduced IDO1 expression in preeclamptic placentas.

Unravelling the biological secrets of microchimerism by single-cell analysis

The presence of microchimeric cells is known for >100 years and well documented since decades. Earlier, microchimeric cells were mainly used for cell-based non-invasive prenatal diagnostics during early pregnancy. Microchimeric cells are also present beyond delivery and are associated to various autoimmune diseases, tissue repair, cancer and immune tolerance. All these findings were based on low complexity studies and occasionally accompanied by artefacts not allowing the biological functions of microchimerism to be determined. However, with the recent developments in single-cell analysis, new means to identify and characterize microchimeric cells are available. Cell labelling techniques in combination with single-cell analysis provide a new toolbox to decipher the biology of microchimeric cells at molecular and cellular level. In this review, we discuss how recent developments in single-cell analysis can be applied to determine the role and function of microchimeric cells.

Target Cell Pre-enrichment and Whole Genome Amplification for Single Cell Downstream Characterization

Rare target cells can be isolated from a high background of non-target cells using antibodies specific for surface proteins of target cells. A recently developed method uses a medical wire functionalized with anti-epithelial cell adhesion molecule (EpCAM) antibodies for in vivo isolation of circulating tumor cells (CTCs)1. A patient-matched cohort in non-metastatic prostate cancer showed that the in vivo isolation technique resulted in a higher percentage of patients positive for CTCs as well as higher CTC counts as compared to the current gold standard in CTC enumeration. As cells cannot be recovered from current medical devices, a new functionalized wire (referred to as Device) was manufactured allowing capture and subsequent detachment of cells by enzymatic treatment. Cells are allowed to attach to the Device, visualized on a microscope and detached using enzymatic treatment. Recovered cells are cytocentrifuged onto membrane-coated slides and harvested individually by means of laser microdissection or micromanipulation. Single-cell samples are then subjected to single-cell whole genome amplification allowing multiple downstream analysis including screening and target-specific approaches. The procedure of isolation and recovery yields high quality DNA from single cells and does not impair subsequent whole genome amplification (WGA). A single cell's amplified DNA can be forwarded to screening and/or targeted analysis such as array comparative genome hybridization (array-CGH) or sequencing. The device allows ex vivo isolation from artificial rare cell samples (i.e. 500 target cells spiked into 5 mL of peripheral blood). Whereas detachment rates of cells are acceptable (50 - 90%), the recovery rate of detached cells onto slides spans a wide range dependent on the cell line used (<10 - >50%) and needs some further attention. This device is not cleared for the use in patients.

In Situ Detection and Quantification of AR-V7, AR-FL, PSA, and KRAS Point Mutations in Circulating Tumor Cells

BACKGROUND

Liquid biopsies can be used in castration-resistant prostate cancer (CRPC) to detect androgen receptor splice variant 7 (AR-V7), a splicing product of the androgen receptor. Patients with AR-V7-positive circulating tumor cells (CTCs) have greater benefit of taxane chemotherapy compared with novel hormonal therapies, indicating a treatment-selection biomarker. Likewise, in those with pancreatic cancer (PaCa), KRAS mutations act as prognostic biomarkers. Thus, there is an urgent need for technology investigating the expression and mutation status of CTCs. Here, we report an approach that adds AR-V7 or KRAS status to CTC enumeration, compatible with multiple CTC-isolation platforms.

METHODS

We studied 3 independent CTC-isolation devices (CellCollector, Parsortix, CellSearch) for the evaluation of AR-V7 or KRAS status of CTCs with in situ padlock probe technology. Padlock probes allow highly specific detection and visualization of transcripts on a cellular level. We applied padlock probes for detecting AR-V7, androgen receptor full length (AR-FL), and prostate-specific antigen (PSA) in CRPC and KRAS wild-type (wt) and mutant (mut) transcripts in PaCa in CTCs from 46 patients.

RESULTS

In situ analysis showed that 71% (22 of 31) of CRPC patients had detectable AR-V7 expression ranging from low to high expression [1–76 rolling circle products (RCPs)/CTC]. In PaCa patients, 40% (6 of 15) had KRAS mut expressing CTCs with 1 to 8 RCPs/CTC. In situ padlock probe analysis revealed CTCs with no detectable cytokeratin expression but positivity for AR-V7 or KRAS mut transcripts.

CONCLUSIONS

Padlock probe technology enables quantification of AR-V7, AR-FL, PSA, and KRAS mut/wt transcripts in CTCs. The technology is easily applicable in routine laboratories and compatible with multiple CTC-isolation devices.

Multiplex Gene Expression Profiling of In Vivo Isolated Circulating Tumor Cells in High-Risk Prostate Cancer Patients

BACKGROUND

Molecular characterization of circulating tumor cells (CTCs) is important for selecting patients for targeted treatments. We present, for the first time, results on gene expression profiling of CTCs isolated in vivo from high-risk prostate cancer (PCa) patients compared with CTC detected by 3 protein-based assays-CellSearch^®, PSA-EPISPOT, and immunofluorescence of CellCollector^® in vivo-captured CTCs-using the same blood draw.

METHODS

EpCAM-positive CTCs were isolated in vivo using the CellCollector from 108 high-risk PCa patients and 36 healthy volunteers. For 27 patients, samples were available before and after treatment. We developed highly sensitive multiplex RT-qPCR assays for 14 genes (KRT19, EpCAM, CDH1, HMBS, PSCA, ALDH1A1, PROM1, HPRT1, TWIST1, VIM, CDH2, B2M, PLS3, and PSA), including epithelial markers, stem cell markers, and epithelial-to-mesenchymal-transition (EMT) markers.

RESULTS

We observed high heterogeneity in gene expression in the captured CTCs for each patient. At least 1 marker was detected in 74 of 105 patients (70.5%), 2 markers in 45 of 105 (40.9%), and 3 markers in 16 of 105 (15.2%). Epithelial markers were detected in 31 of 105 (29.5%) patients, EMT markers in 46 of 105 (43.8%), and stem cell markers in 15 of 105 (14.3%) patients. EMT-marker positivity was very low before therapy (2 of 27, 7.4%), but it increased after therapy (17 of 27, 63.0%), whereas epithelial markers tended to decrease after therapy (2 of 27, 7.4%) compared with before therapy (13 of 27, 48.1%). At least 2 markers were expressed in 40.9% of patients, whereas the positivity was 19.6% for CellSearch, 38.1% for EPISPOT, and 43.8% for CellCollector-based IF-staining.

CONCLUSIONS

The combination of in vivo CTC isolation with downstream RNA analysis is highly promising as a high-throughput, specific, and ultrasensitive approach for multiplex liquid biopsy-based molecular diagnostics.

Abstract 1716: GSTP1 promoter methylation in in-vivo isolated CTCs from high-risk prostate cancer patients

Introduction: Glutathione S-transferase 1 (GSTP1) has been reported to function as tumor suppressor gene in various types of human cancers. GSTP1 inactivation is associated with CpG island promoter hypermethylation in the majority of prostate cancers (PCs). The initiation of minimal residual disease (MRD) and especially the detection of circulating tumor cells (CTCs) in patients’ peripheral blood represents a negative prognostic parameter for recurrence-free survival. The aim of the present study was to assess the methylation status of the GSTP1 gene in CTCs that were isolated, using the CellCollector® (GILUPI, GmbH), a novel clinical device designed for the in vivo isolation of EpCAM-positive CTCs. Patients and methods: In-vivo isolation of CTCs was performed by using CellCollector® from high-risk prostate cancer patients (n=97) and 20 healthy volunteers. For all these patients, the Ab coated region of the CellCollector® was washed in PBS , cut, and stored in Trizol reagent till analysis and DNA was further prior to the analysis isolated DNA was modified by sodium bisulfite (SB) and subjected to a real time MSP assay specific for GSTP1 methylation. In all cases, peripheral blood was also collected and used for CTC analysis by Immunostaining and the CellSearch® system. Results: All DNA samples were first checked for their quality. Based on the quality evaluation of all available DNA samples, only 63 DNAs were further qualified for analysis. GSTP1 promoter was found methylated in 12/63 (19%) the EpCAM positive fraction of in-vivo isolated CTCs. Moreover, in 5/12 (41.7%) patients for which GSTP1 promoter was found methylated, CTCs were also detected by the CellSearch® and 7 /12 (58.3%) for which GSTP1 promoter was also found positive, CTCs were also detected by the Immunostaining. Conclusion: GSTP1 promoter is methylated in in-vivo isolated CTCs from high-risk prostate cancer patients. GSTP1 promoter methylation in in-vivo isolated CTCs should be prospectively validated as a novel tumor biomarker for prostate cancer patients in a large cohort of patients. Acknowledgements: This research has been co-financed by the European Union (European Regional Development Fund - ERDF) and Greek national funds through the Operational Program ‘‘Competitiveness and Entrepreneurship’’ of the National Strategic Reference Framework (NSRF) - Research Funding Program: “ERA-NET on Translational Cancer Research (TRANSCAN) Joint Transnational Call for Proposals 2011 (JTC 2011) on: “Validation of biomarkers for personalised cancer medicine

Citation Format: Athina N. Markou, Panagiotis Paraskevopoulos, Marifili Lazaridou, Shukun Chen, Thomas Kroneis, Monika Świerczewska, Joanna Budna, Andra Kuske, Tobias M. Gorges, Maciej Zabel, Peter Sedlmayr, Catherine Alix-Panabieres, Klaus Pantel, Evi Lianidou. GSTP1 promoter methylation in in-vivo isolated CTCs from high-risk prostate cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1716. doi:10.1158/1538-7445.AM2017-1716

Detection of Fetal Sex, Aneuploidy and a Microdeletion from Single Placental Syncytial Nuclear Aggregates

OBJECTIVES

A key problem in prenatal screening using extra-embryonic cells is the feasibility of extracting usable DNA from a small number of cells. Syncytial nuclear aggregates (SNAs) are multinucleated structures shed from the placenta. This study assesses the potential of SNAs as a source of fetal DNA for the detection of genetic abnormalities.

METHODS

SNAs were collected in vitro. Whole-genome amplification was used to amplify DNA from single SNAs, and DNA quality and quantity was assessed by spectrophotometry and PCR. Confocal microscopy was used to count nuclei within SNAs, determine metabolic activity and investigate DNA damage. Fetal sex and chromosomal/genetic abnormalities were investigated with array-comparative genomic hybridization (aCGH).

RESULTS

DNA was amplified from 81% of the individual SNAs. A mean of 61 ± 43 nuclei were found per SNA. DNA strand breaks were found in 76% of the SNAs. Seventy-five percent of SNAs yielded whole-genome-amplified DNA of sufficient quality for aCGH after storage and shipping. Individual SNAs from the same pregnancy reliably gave the same chromosomal profile, and fetal sex and trisomies could be detected. A microdeletion was detected in one pregnancy.

CONCLUSION

SNAs could provide a source of extra-embryonic DNA for the prenatal screening/diagnosis of fetal sex and chromosomal and sub-chromosomal genetic abnormalities.

The role of placental tryptophan catabolism

This review discusses the mechanisms and consequences of degradation of tryptophan (Trp) in the placenta, focusing mainly on the role of indoleamine 2,3-dioxygenase-1 (IDO1), one of three enzymes catalyzing the first step of the kynurenine pathway of Trp degradation. IDO1 has been implicated in regulation of feto-maternal tolerance in the mouse. Local depletion of Trp and/or the presence of metabolites of the kynurenine pathway mediate immunoregulation and exert antimicrobial functions. In addition to the decidual glandular epithelium, IDO1 is localized in the vascular endothelium of the villous chorion and also in the endothelium of spiral arteries of the decidua. Possible consequences of IDO1-mediated catabolism of Trp in the endothelium encompass antimicrobial activity and immunosuppression, as well as relaxation of the placental vasotonus, thereby contributing to placental perfusion and growth of both placenta and fetus. It remains to be evaluated whether other enzymes mediating Trp oxidation, such as indoleamine 2,3-dioxygenase-2, Trp 2,3-dioxygenase, and Trp hydroxylase-1 are of relevance to the biology of the placenta.

Distribution of decidual natural killer cells and macrophages in the neighbourhood of the trophoblast invasion front: a quantitative evaluation

STUDY QUESTION

Do decidual natural killer (dNK) cells and decidual macrophages (dMph) become enriched in the vicinity of the trophoblast invasion front?

SUMMARY ANSWER

Morphometric image analysis and areal cell density calculations, which excluded observer bias, showed an enrichment of decidual leukocytes in the neighbourhood of the trophoblast invasion front.

WHAT IS KNOWN ALREADY

In previous studies, the number of decidual leukocytes was visually counted in medium- or high power fields. These methods, however, cannot reveal the exact spatial relationship between leukocytes and invasive trophoblast cells, and are therefore prone to subjective errors. Thus, a more objective approach is required.

STUDY DESIGN, SIZE, DURATION

Applying a new method of morphometric image analysis, leukocyte populations were studied in human tissue fragments derived from first trimester placentation sites (n = 7) as well as in co-cultures of first trimester decidual tissue with placental villi of the same pregnancy representing an appropriate in vitro model of trophoblast invasion (n = 15).

PARTICIPANTS/MATERIALS, SETTINGS, METHODS

First trimester decidual tissue was obtained from women undergoing elective terminations of pregnancy at 7-10 weeks of gestational age. Tissue sections were double-stained immunohistochemically for markers of dNK cells or dMph on one hand, and for invasive extravillous trophoblast cells on the other. To analyse the distribution of leukocytes, distinct cell compartments as well as cell neighbourhood areas were defined. Finally, relative areal cell densities were calculated and these data were compared with those of an in vitro model of trophoblast invasion as well as with tissue fragments derived from decidua parietalis without trophoblast cells.

MAIN RESULTS AND THE ROLE OF CHANCE

At first trimester placentation sites, a higher density of dNK cells as well as of dMph was found in close proximity to the invasive trophoblast (P ≤ 0.01), compared with the average areal cell density of decidual leukocytes in the tissue with exclusion of the trophoblast. The highest areal cell density of leukocytes was determined up to a distance of 20 μm from the trophoblast cells, whereas in more distant regions it was even lower than average, indicating a migration of these leukocytes towards the trophoblast invasion front. In the three-dimensional co-culture model, however, we found an enrichment of dMph (P ≤ 0.01) but not of dNK cells (P > 0,05) in the neighbourhood of the invasive trophoblast.

LIMITATIONS, REASONS FOR CAUTION

The morphometric image analysis depends on intense immunohistochemical staining that is free of background and cross-reactivity.

WIDER IMPLICATIONS OF THE FINDINGS

The presented method will be useful not only for the investigation of recurrent miscarriage but also in the fields of tumour immunology and inflammation.

STUDY FUNDING/COMPETING INTEREST(S)

The study was supported by the European Commission (Network of Excellence 'The Control of Embryo Implantation (EMBIC)', FP6-512040, lead researcher: P.S.), and by the Franz Lanyar Foundation of the Medical University of Graz, Austria (Grant #347). None of the authors declared a conflict of interests.

Are morphological criteria sufficient for the identification of circulating tumor cells in renal cancer?

Background

Single circulating tumor cells (CTCs) or circulating tumor microemboli (CTMs) are potential biomarkers of renal cell cancer (RCC), however studies of CTCs/CTMs in RCC are limited. In this pilot study we aimed to evaluate a novel blood filtration technique suited for cytomorphological classification, immunocytochemical and molecular characterization of filtered, so called circulating non-hematologic cells (CNHCs) - putative CTCs/CTMs - in patients with RCC.

Methods

Blood of 40 patients with renal tumors was subjected to ScreenCell® filtration. CNHCs were classified according to cytomorphological criteria. Immunocytochemical analysis was performed with antibodies against CD45, CD31 and carbonic anhydrase IX (CAIX, a RCC marker). DNA of selected CNHCs and respective primary tumors was analysed by array-CGH.

Results

CNHC-clusters with malignant or uncertain malignant cytomorphological features - putative CTMs - were negative for CD45, positive for CD31, while only 6% were CAIX positive. Array-CGH revealed that 83% of malignant and uncertain malignant cells did represent with a balanced genome whereas 17% presented genomic DNA imbalances which did not match the aberrations of the primary tumors. Putative single CTCs were negative for CD45, 33% were positive for CD31 and 56% were positive for CAIX.

Conclusions

The majority of CNHC-clusters, putative CTMs, retrieved by ScreenCell® filtration may be of endothelial origin. Morphological criteria seem to be insufficient to distinguish malignant from non-malignant cells in renal cancer.

Placental expression of indoleamine 2,3-dioxygenase

This review focuses on the placental expression of the tryptophan-degrading enzyme indoleamine 2,3-dioxygenase-1 (IDO1) and its potential roles, which may not only encompass immunosuppression and antimicrobial activity, but also vasodilation based on the endothelial expression on both sides of the feto-maternal interface.

Exercise increases the frequency of circulating hematopoietic progenitor cells, but reduces hematopoietic colony-forming capacity

Circulating hematopoietic progenitor cells (CPCs) may be triggered by physical exercise and/or normobaric hypoxia from the bone marrow. The aim of the study was to investigate the influence of physical exercise and normobaric hypoxia on CPC number and functionality in the peripheral blood as well as the involvement of oxidative stress parameters as possibly active agents. Ten healthy male subjects (25.3±4.4 years) underwent a standardized cycle incremental exercise test protocol (40 W+20 W/min) under either normoxic (FiO2 ∼0.21) or hypoxic conditions (FiO2<0.15, equals 3,500 m, 3 h xposure) within a time span of at least 1 week. Blood was drawn from the cubital vein before and 10, 30, 60, and 120 min after exercise. The number of CPCs in the peripheral blood was analyzed by flow cytometry (CD34/CD45-positive cells). The functionality of cells present was addressed by secondary colony-forming unit-granulocyte macrophage (CFU-GM) assays. To determine a possible correlation between the mobilization of CPCs and reactive oxygen species, parameters for oxidative stress such as malondialdehyde (MDA) and myeloperoxidase (MPO) were obtained. Data showed a significant increase of CPC release under normoxic as well as hypoxic conditions after 10 min of recovery (P<0.01). Most interestingly, although CD34+/CD45dim cells increased in number, the proliferative capacity of CPCs decreased significantly 10 min after cessation of exercise (P<0.05). A positive correlation between CPCs and MDA/MPO levels turned out to be significant for both normoxic and hypoxic conditions (P<0.05/P<0.01). Hypoxia did not provoke an additional effect. Although the CPC frequency increased, the functionality of CPCs decreased significantly after exercise, possibly due to the influence of increased oxidative stress levels.

Galectin-1 confers immune privilege to human trophoblast: implications in recurrent fetal loss

Mechanisms accounting for the protection of the fetal semi-allograft from maternal immune cells remain incompletely understood. In previous studies, we showed that galectin-1 (Gal1), an immunoregulatory glycan-binding protein, hierarchically triggers a cascade of tolerogenic events at the mouse fetomaternal interface. Here, we show that Gal1 confers immune privilege to human trophoblast cells through the modulation of a number of regulatory mechanisms. Gal1 was mainly expressed in invasive extravillous trophoblast cells of human first trimester and term placenta in direct contact with maternal tissue. Expression of Gal1 by the human trophoblast cell line JEG-3 was primarily controlled by progesterone and pro-inflammatory cytokines and impaired T-cell responses by limiting T cell viability, suppressing the secretion of Th1-type cytokines and favoring the expansion of CD4(+)CD25(+)FoxP3(+) regulatory T (T(reg)) cells. Targeted inhibition of Gal1 expression through antibody (Ab)-mediated blockade, addition of the specific disaccharide lactose or retroviral-mediated siRNA strategies prevented these immunoregulatory effects. Consistent with a homeostatic role of endogenous Gal1, patients with recurrent pregnancy loss showed considerably lower levels of circulating Gal1 and had higher frequency of anti-Gal1 auto-Abs in their sera compared with fertile women. Thus, endogenous Gal1 confers immune privilege to human trophoblast cells by triggering a broad tolerogenic program with potential implications in threatened pregnancies.

Amnion-derived mesenchymal stromal cells show angiogenic properties but resist differentiation into mature endothelial cells

Mesenchymal stromal cells derived from the human amnion (hAMSC) currently play an important role in stem cell research, as they are multipotent cells that can be isolated using noninvasive methods and are immunologically tolerated in vivo. The objective of this study was to evaluate their endothelial differentiation potential with regard to a possible therapeutic use in vascular diseases. hAMSC were isolated from human term placentas and cultured in Dulbecco's modified Eagle's medium (DMEM) (non-induced hAMSC) or endothelial growth medium (EGM-2) (induced hAMSC). Induced hAMSC changed their fibroblast-like toward an endothelial-like morphology, and were able to take up acetylated low-density lipoprotein and form endothelial-like networks in the Matrigel assay. However, they did not express the mature endothelial cell markers von Willebrand factor and vascular endothelial-cadherin. Gene expression analysis revealed that induced hAMSC significantly downregulated pro-angiogenic genes such as tenascin C, Tie-2, vascular endothelial growth factor A (VEGF-A), CD146, and fibroblast growth factor 2 (FGF-2), whereas they significantly upregulated anti-angiogenic genes such as serpinF1, sprouty1, and angioarrestin. Analysis of protein expression confirmed the downregulation of FGF-2 and Tie-2 (27%±8% and 13%±1% of non-induced cells, respectively) and upregulation of the anti-angiogenic protein endostatin (226%±4%). Conditioned media collected from hAMSC enhanced viability of endothelial cells and had a stabilizing effect on endothelial network formation as shown by lactate dehydrogenase and Matrigel assay, respectively. In summary, endothelial induced hAMSC acquired some angiogenic properties but resisted undergoing a complete differentiation into mature endothelial cells by upregulation of anti-angiogenic factors. Nevertheless, they had a survival-enhancing effect on endothelial cells that might be useful in a variety of cell therapy or tissue-engineering approaches.

Vascular endothelial expression of indoleamine 2,3-dioxygenase 1 forms a positive gradient towards the feto-maternal interface

We describe the distribution of indoleamine 2,3-dioxygenase 1 (IDO1) in vascular endothelium of human first-trimester and term placenta. Expression of IDO1 protein on the fetal side of the interface extended from almost exclusively sub-trophoblastic capillaries in first-trimester placenta to a nearly general presence on villous vascular endothelia at term, including also most bigger vessels such as villous arteries and veins of stem villi and vessels of the chorionic plate. Umbilical cord vessels were generally negative for IDO1 protein. In the fetal part of the placenta positivity for IDO1 was restricted to vascular endothelium, which did not co-express HLA-DR. This finding paralleled detectability of IDO1 mRNA in first trimester and term tissue and a high increase in the kynurenine to tryptophan ratio in chorionic villous tissue from first trimester to term placenta. Endothelial cells isolated from the chorionic plate of term placenta expressed IDO1 mRNA in contrast to endothelial cells originating from human umbilical vein, iliac vein or aorta. In first trimester decidua we found endothelium of arteries rather than veins expressing IDO1, which was complementory to expression of HLA-DR. An estimation of IDO activity on the basis of the ratio of kynurenine and tryptophan in blood taken from vessels of the chorionic plate of term placenta indicated far higher values than those found in the peripheral blood of adults. Thus, a gradient of vascular endothelial IDO1 expression is present at both sides of the feto-maternal interface.

Verification of the genomic identity of candidate microchimeric cells

Microchimerism has been studied in the context of a variety of diseases which include autoimmune diseases (such as systemic sclerosis, rheumatoid arthritis, systemic lupus erythematosus and autoimmune thyroid diseases), cancer (e.g., of the cervix, thyroid gland, lung, breast), tissue repair, transplantation and transfusion. It may become relevant in the context of cell-based non-invasive prenatal diagnosis. But how to safely identify individual microchimeric cells? This is a nontrivial question, for which a solution has recently been suggested.

Combined molecular genetic and cytogenetic analysis from single cells after isothermal whole-genome amplification

BACKGROUND

Analysis of chromosomal aberrations or single-gene disorders from rare fetal cells circulating in the blood of pregnant women requires verification of the cells' genomic identity. We have developed a method enabling multiple analyses at the single-cell level that combines verification of the genomic identity of microchimeric cells with molecular genetic and cytogenetic diagnosis.

METHODS

We used a model system of peripheral blood mononuclear cells spiked with a colon adenocarcinoma cell line and immunofluorescence staining for cytokeratin in combination with DNA staining with the nuclear dye TO-PRO-3 in a preliminary study to define candidate microchimeric (tumor) cells in Cytospin preparations. After laser microdissection, we performed low-volume on-chip isothermal whole-genome amplification (iWGA) of single and pooled cells.

RESULTS

DNA fingerprint analysis of iWGA aliquots permitted successful identification of all analyzed candidate microchimeric cell preparations (6 samples of pooled cells, 7 samples of single cells). Sequencing of 3 single-nucleotide polymorphisms was successful at the single-cell level for 20 of 32 allelic loci. Metaphase comparative genomic hybridization (mCGH) with iWGA products of single cells showed the gains and losses known to be present in the genomic DNA of the target cells.

CONCLUSIONS

This method may be instrumental in cell-based noninvasive prenatal diagnosis. Furthermore, the possibility to perform mCGH with amplified DNA from single cells offers a perspective for the analysis of nonmicrochimeric rare cells exhibiting genomic alterations, such as circulating tumor cells.

Measurement of cell death by oxidative stress in three-dimensional spheroids from trophoblast and in fragments of decidua tissue

We report a new morphometric method for measurement of the amount of cell death in three-dimensional multicellular spheroids of the trophoblast-like cell line AC1-M59 and of cultured pieces of decidua tissue (decidua spheroids) in response to a cytotoxic agent. The viability of the spheroids was assessed by adding propidium iodide to the culture medium at the end of the toxic treatment. On fluorescence and brightfield images of serial cryosections the areas of propidium iodide fluorescence and the entire corresponding spheroids were measured by applying digital image processing and ratiometrical quantification. As an example, we evaluated the cytotoxic effect of hydrogen peroxide on both types of spheroids. The relative potency of hydrogen peroxide to induce tissue damage was assessed quantitatively for determination of the minimal concentration that leads to an increase in cytotoxicity. The method presented suggests general applicability for in vitro determination of toxicity against tissues.

Neuroendocrine circuitry and endometriosis: progesterone derivative dampens corticotropin-releasing hormone-induced inflammation by peritoneal cells in vitro

Clinical symptoms of endometriosis, such as pain and infertility, can be described as persistent stressors. Such continuous exposure to stress may severely affect the equilibrium and bidirectional communication of the endocrine and immune system, hereby further aggravating the progression of endometriosis. In the present study, we aimed to tease apart mediators that are involved in the stress response as well as in the progression of endometriosis. Women undergoing diagnostic laparoscopy due to infertility were recruited (n = 69). Within this cohort, early stage of endometriosis were diagnosed in n = 30 and advanced stage of endometriosis in n = 8. Levels of progesterone in serum were determined. Frequency of progesterone receptor (PR) expression on CD56(+) and CD8(+) peritoneal lymphocytes was analysed by flow cytometry. The production of tumour necrosis factor (TNF) and interleukin (IL)-10 by peritoneal leukocytes upon stimulation with the potent stress mediator corticotropin-releasing hormone (CRH) and the progesterone derivative dydrogesterone, or both, were evaluated. Furthermore, the production of progesterone-induced blocking factor (PIBF) by peritoneal leukocytes and the expression of PR in endometriotic tissue were investigated. Levels of progesterone in serum were decreased in women with endometriosis and inversely correlated to pain scores. Furthermore, an increased frequency of CD56(+)PR(+) and CD8(+)PR(+) peritoneal lymphocytes was present in advanced endometriosis. The TNF/IL-10 ratio, reflecting cytokine secretion by peritoneal cells, was higher in cells derived from endometriosis patients and could be further heightened by CRH stimulation, whereas stimulation with dydrogesterone abrogated the CRH-mediated inflammation. Finally, the expression of PIBF by peritoneal leukocytes was increased in endometriosis. Low levels of progesterone in the follicular phase could be responsible for the progression of endometriosis and related pain. Peripheral CRH, increasing upon high psychological stress, might contribute to the peritoneal inflammation present in endometriosis. The therapeutic application of progesterone derivatives, CRH blocking agents as well as improvement of stress coping may disrupt the vicious circle between the chronic peritoneal inflammation and high perception of psychological stress in endometriosis.

Automatic retrieval of single microchimeric cells and verification of identity by on-chip multiplex PCR

The analysis of rare cells is not an easy task. This is especially true when cells representing a fetal microchimerism are to be utilized for the purpose of non-invasive prenatal diagnosis because it is both imperative and difficult to avoid contaminating the minority of fetal cells with maternal ones. Under these conditions, even highly specific biochemical markers are not perfectly reliable. We have developed a method to verify the genomic identity of rare cells that combines automatic screening for enriched target cells (based on immunofluorescence labelling) with isolation of single candidate microchimeric cells (by laser microdissection and subsequent laser catapulting) and low-volume on-chip multiplex PCR for DNA fingerprint analysis. The power of the method was tested using samples containing mixed cells of related and non-related individuals. Single-cell DNA fingerprinting was successful in 74% of the cells analysed (55/74), with a PCR efficiency of 59.2% (860/1452) for heterozygous loci. The identification of cells by means of DNA profiling was achieved in 100% (12/12) of non-related cells in artificial mixtures and in 86% (37/43) of cells sharing a haploid set of chromosomes and was performed on cells enriched from blood and cells isolated from tissue. We suggest DNA profiling as a standard for the identification of microchimerism on a single-cell basis.

Alternatively activated macrophages regulate extracellular levels of the hormone placental lactogen via receptor-mediated uptake and transcytosis

Alternatively activated (M2) macrophages regulate immune responses and tissue remodelling. In many tissues including placenta, M2 express stabilin-1, a multidomain protein that exerts a dual role as a scavenger receptor for acetylated low density lipoprotein (acLDL) and SPARC (secreted protein acidic and rich in cysteine) and as an intracellular cargo carrier for SI-CLP. Using yeast two-hybrid screening, we identified the developmental hormone placental lactogen (PL) as a novel ligand of stabilin-1. In Chinese hamster ovary-stabilin-1 cells and M2, FACS and confocal microscopy demonstrated that stabilin-1 mediates internalization and endosomal sorting of PL. In M2 macrophages, PL was partially degraded in lysosomes; part of PL escaped degradation and was delivered to novel PL+ storage vesicles lacking endosomal/lysosomal markers. During formation, PL+ vesicles underwent transient interaction with the trans-Golgi network (TGN). Upon placement of PL-loaded M2 into PL-free medium, PL was secreted into the supernatant. Leupeptin, an inhibitor of lysosomal hydrolases, reduced PL degradation, enhanced sorting of PL into the TGN/storage vesicle pathway and increased PL secretion. Thus, processing of PL in M2 macrophages occurs either by the classical lysosomal pathway or by a novel TGN-associated trans-secretory pathway. Macrophages isolated from human placental villi efficiently endocytosed PL-FITC and transported it to the storage vesicles. Our data show that extracellular PL levels are determined by uptake, degradation, storage, and release in M2. During pregnancy PL concentration reaches 10 microg/ml in maternal circulation and stays below 0.5 microg/ml in fetal circulation. We propose that stabilin-1-positive macrophages determine the difference in PL levels between maternal and fetal circulation.

High availability of intravascular tissue factor in neonates

In the present study, we compared the levels of intravascular tissue factor (TF) present in cord versus adult whole blood (WB) prior and after lipopolysaccharide (LPS) stimulation. High levels of intravascular TF might help to explain the clinically observed efficient clotting of cord blood despite low levels of procoagulatory factors. Quantitative reverse transcription-polymerase chain reaction revealed same (basal) TF mRNA expression levels in both native cord and adult WB, and approximately same increase in TF mRNA expression owing to LPS incubation in both cord and adult WB (normalized to the housekeeping gene beta-actin). Flow-cytometric (fluorescence activated cell sorting) analysis revealed significantly higher surface TF antigen exposure on the neonatal monocyte membrane in native WB samples, and approximately same ability of neonatal and adult monocytes to express TF upon LPS-stimulation. Thrombelastography revealed significantly shorter clotting times of native cord versus adult WB (527+/-41 vs. 592+/-23 s, P<0.05). Moreover, shortening of clotting times owing to LPS-stimulation was significantly more pronounced in cord versus adult WB (29.65+/-3.35% vs. 12.03+/-6.23%, P<0.05). Because both quantitative reverse transcription-polymerase chain reaction and fluorescence activated cell sorting analysis revealed same capability of both neonatal and adult monocytes to express TF upon LPS-stimulation, this efficient shortening effect in cord WB might be explained by the constitutively high number of monocytes present in neonates. We suggest that the high levels of intravascular TF present in neonates (prior and after LPS-stimulation) might help to explain the clinically observed efficient clotting of cord blood despite low levels of procoagulatory factors.

Indoleamine 2,3-Dioxygenase in Materno-Fetal Interaction

The mechanism of maternal immunotolerance of the semiallogeneic fetus has been a matter of intense investigation. The tryptophan-degrading enzyme indoleamine 2,3-dioxygenase (IDO) is reported to be critically implicated. This article discusses findings pertaining to the role of IDO in pregnancy, its location at the feto-maternal interface, systemic induction of IDO in pregnancy and the association of IDO to spontaneous abortion and preeclampsia. Whereas there is a large body of evidence supporting the relevance of IDO as a key immunoregulatory factor in feto-maternal tolerance, open questions remain concerning as to its role.

Monocyte-mediated T-cell suppression and augmented monocyte tryptophan catabolism after human hematopoietic stem-cell transplantation

T-cell dysfunction after human hematopoietic stem-cell transplantation (HSCT) is generally attributed to intrinsic T-cell defects. Here we show that the characteristic impaired proliferative responses to polyclonal stimulation of post-HSCT peripheral blood mononuclear cells (PB-MCs) were markedly (4-fold) improved by T-cell enrichment. Conversely, addback of post-HSCT monocytes to these enriched T cells dampened their proliferative responses, suggesting that post-HSCT monocytes effectively mediate T-cell suppression. As a mechanism possibly contributing to monocyte-mediated T-cell suppression, we investigated monocyte tryptophan catabolism by indoleamine 2,3-dioxygenase into kynurenine, which has been implicated in regulating T-cell responses. Compared with controls, all post-HSCT monocyte-containing cell cultures (total PBMCs, monocytes, and monocyte/T-cell cocultures), but not monocyte-depleted populations, secreted elevated amounts of kynurenine. Blockade of tryptophan catabolism improved the proliferative responses. The slightly increased kynurenine release and substantial release of neopterin by unstimulated post-HSCT monocytes suggests that they were in a state of continuous activation. Superimposed on this state, stimulation of these cells caused a striking, additional increase (10-fold) in kynurenine release, and they triggered marked apoptosis of autologous post-HSCT T cells. We conclude that the amplified kynurenine release by post-HSCT monocytes, particularly induced upon stimulation, may underlie their suppressor activity, which in turn may contribute to the depressed T-cell immune responses after HSCT.

Macrophages of human first trimester decidua express markers associated to alternative activation

PROBLEM

Depending on the type of their activation, macrophages may promote TH1- or TH2-type of immune responses. To date, not much is known about the activation phenotype of decidua macrophages, which - together with NK cells - constitute the majority of bone marrow derived cells at this location.

METHOD OF STUDY

The study was based on analysis of healthy first trimester decidua by immunohistochemistry and flow cytometry. We analyzed expression of markers characteristic for alternatively activated macrophages (Mphi2).

RESULTS

The markers MS-1 (stabilin-1) and coagulation factor XIIIa were found expressed in the interior of decidua macrophages (DMphi). In contrast, indoleamine 2,3-dioxygenase (IDO), an enzyme induced in macrophages by IFNgamma, was not present in DMphi.

CONCLUSIONS

First trimester DMphi display phenotypic markers associated to alternatively activated macrophages. In addition, absence of IDO indicates that DMphi are not under a predominant influence of IFNgamma.

Inhibition of lung carcinoma cell growth by high density lipoprotein-associated ?-tocopheryl-succinate

Alpha-tocopheryl-succinate (alphaTS) is a synthetic, anti-neoplastic derivative of alpha-tocopherol. Here we studied the effects of free and high-density lipoprotein subclass 3 (HDL3)-associated alphaTS on the growth of human (A549) and mouse Lewis (LL2) lung carcinoma cells. Both free and HDL3-associated alphaTS inhibited A549 growth in a time- and concentration-dependent manner. Treatment of A549 cells with alphaTS-enriched HDL3 led to DNA fragmentation and a time-dependent decrease in immunoreactivity of poly(ADP-ribose)polymerase. Uptake experiments revealed a high capacity for selective alphaTS uptake in excess of holoparticle endocytosis. Overexpression of scavenger receptor class B, type I (SR-BI), the prime receptor mediating selective lipid uptake, in A549 cells resulted in significantly increased selective alphaTS uptake, a finding associated with complete cellular growth arrest. The present in vitro findings were verified in an in vivo model: tumor inoculation in C57BL6 was performed with either wild-type, beta-galactosidase- or SR-BI-overexpressing LL2 cells. After tumor inoculation, the animals received six consecutive intravenous injections of alphaTS. This experimental setup resulted in significantly reduced tumor burden in animals that were inoculated with SR-BI-overexpressing LL2 cells but not in animals inoculated with wild-type or beta-galactocidase-transfected cells. Based on our in vitro and in vivo findings, we propose that SR-BI could provide a novel route for HDL3-mediated drug delivery of anti-neoplastic drugs.

Fetal nucleated red blood cells in peripheral blood of pregnant women: detection and determination of location on a slide using laser-scanning cytometry

OBJECTIVE

The purpose of the study was to assess the feasibility of analysis of fetal nucleated red blood cells (NRBC) present in the maternal circulation by laser-scanning cytometry.

METHODS

CD71-positive cells were obtained by magnetic cell sorting of peripheral blood of pregnant women after density centrifugation. Immunofluorescence for the Hbgamma-chain was combined with fluorescent staining of DNA (TO-PRO-3) and fluorescence in situ hybridization (FISH) with a Y-chromosome specific probe. The cells were scanned on a slide using a laser-scanning cytometer (LSC). Events double positive for Hbgamma and TO-PRO-3 were relocated and their morphology and FISH reactivity were visually assessed. Determination of male fetal sex with LSC was compared with findings from amniocentesis.

RESULTS

In 8/15 pregnancies with male fetuses and in 0/9 with females (apart from one case with a male/female twin pregnancy), we detected Y-chromosome-positive NRBC. In pregnancies with female fetuses, Y-chromosome-positive cells other than NRBC were found in all women who had previously given birth to male babies, whereas women with no abortion and no male babies in their history did not present with Y-chromosome-positive non-NRBC.

CONCLUSION

On the basis of automatic relocation of once-defined cells of fetal origin from the current pregnancy, laser-scanning cytometry is likely to facilitate repeated (poly-)FISH analysis and single-cell PCR for noninvasive prenatal diagnosis.

Effects of low concentrations of cadmium on immunoglobulin E production by human B lymphocytes in vitro

Exposure to cadmium (Cd) can cause a variety of biological effects including alterations of immune responses in animals and humans. Both immunosuppression and immunoenhancement have been reported. The present study was aimed at investigating the consequences of exposure to Cd on the human immunoglobulin (Ig) E synthesis, using purified peripheral blood B lymphocytes and IL-4 and anti-human CD40 monoclonal antibody (a-CD40 mAb) as stimuli. Low concentrations of Cd (0.1-10 microM) markedly inhibited production of IgE in a concentration-dependent manner. IgG production, in contrast to IgE, showed a tendency towards being enhanced by Cd, although with a certain individual variability; IgM production was not affected. Cd failed to alter immediate surface expression of the activation markers CD69 and CD23 indicating that early activation events were not impaired. However, the portion of activated B cells was diminished by Cd after stimulation for more than 24 h, paralleled by a concomitant decrease in viability and a subsequent reduction in proliferation. These data suggest that the mechanism of Cd action on activated B cells involved pathways that interrupted an effectively initiated cell activation and induced a cytotoxic signal. Results from this study thus provide further evidence for and new information on the immunotoxic and immunomodulatory effects of Cd on human immune responses.

B7 family molecules are favorably positioned at the human maternal-fetal interface

The human placenta utilizes both active and passive mechanisms to evade rejection by the maternal immune system. We investigated the pattern of expression of the B7 family of immunomodulatory molecules B7-H1 (PD-L1), B7-2 (CD86), and B7-1 (CD80) at the term maternal-fetal interface. Northern blot and reverse transcription-polymerase chain reaction (RT-PCR) analyses showed that B7-H1 mRNA is abundant in term placenta and that cytotrophoblasts are sources of this message. Immunohistochemistry demonstrated that B7-H1 is constitutively expressed by the syncytiotrophoblast and by extravillous cytotrophoblasts, both of which are juxtaposed to maternal blood and tissue. By contrast, placental stromal cells, including macrophages, lacked the protein. Expression of B7-H1 protein was low in first-trimester placenta compared to second- and third-trimester tissue (P < 0.05) and was enhanced in cultured cytotrophoblasts by treatment with either interferon-gamma or epidermal growth factor (P < 0.05), suggesting that one or both of these mediators regulates B7-H1 expression in the placenta. RT-PCR and immunofluorescence analysis of term placental tissue revealed different patterns of expression of the immunostimulatory protein, B7-2. In contrast to B7-H1, B7-2 mRNA and protein were absent in cytotrophoblast cells but present in maternal macrophages and some fetal macrophages. The B7-1 mRNA and protein were absent at the maternal-fetal interface. These studies document expression of the B7 family proteins at the maternal-fetal interface and demonstrate that B7-H1 is positioned such that it could facilitate protection of fetal cells against activated maternal leukocytes. Conversely, B7-2 was absent on trophoblasts and was appropriately localized to fetal and maternal macrophages, which may participate in antigen presentation.

Expression of Indoleamine 2,3-Dioxygenase In Carcinoma of Human Endometrium And Uterine Cervix

Expression of indoleamine 2,3-dioxygenase (IDO) in epithelium of the endometrium and the cervix is not restricted to normal but also present in carcinomatous tissue. The enzyme was found in the majority of cases studied, pioneer cells at the invasion front of the tumors being especially strongly reactive in immunohistology. In addition, also cells in the peritumoral infiltrate of the stroma expressed IDO. Taken together, these findings together with previous data on the immunosuppressive impact of tryptophan depletion suggest IDO-induced suppression of antitumoral immune response in both adenocarcinoma and squamous cell carcinoma of endometrium and cervix. On the other hand, IDO as also known to inhibit tumor cell proliferation by tryptophan depletion.

Expression of functional Fas ligand in choriocarcinoma

PROBLEM

In the course of pregnancy, fetal trophoblast cells and in that of choriocarcinoma-etiology, trophoblast derived tumor cells, invade the uterine mucosa without causing rejection by decidual leukocytes. Fas ligand (FasL, CD95L, APO-IL), a central regulator of the immune system, has been implicated in the maintenance of immune privileged sites, such as the eye, the testis and the pregnant uterus by inducing apoptosis in activated infiltrating leukocytes. In normal pregnancy FasL, which is expressed by trophoblast cells, appears to contribute to the immune privilege of the pregnant uterus. As choriocarcinoma derives from trophoblast we wanted to assess the expression of FasL in this tissue.

METHOD OF STUDY

Immunohistochemistry, immunofluorescence, TUNEL-assay, Western blotting, coculture experiments and flourescence-associated cell sorter-analysis were the techniques used.

RESULTS

Expression of FasL was found on cells of choriocarcinoma in paraffin sections in situ and on three choriocarcinoma cell lines such as JEG-3, JAR and BeWo. These results were confirmed by Western blotting. In coculture experiments choriocarcinoma cells induced apoptosis in a Jurkat cell line - sensitive to FasL mediated killing. However, when the Jurkat cells were pre-incubated with a Fas-blocking monoclonal antibody, apoptosis was abolished to a great extent.

CONCLUSION

Our findings show that choriocarcinoma cells express FasL and this aforementioned molecule is biologically active. We assume that FasL expression on choriocarcinoma cells may contribute to control of anti-tumor responses by inducing apoptosis in activated Fas bearing leukocytes.

Detection and relocation of rare events. A comparative study using the laser scanning cytometer and the Metafer/RCDetect microscope scanning system

We compared instrumental analysis of enriched cord blood nucleated red blood cells (CB-NRBC) out of in vitro contamination preparations of dilutions of minute volumes of male cord blood into peripheral blood from nonpregnant women. This was done using the laser scanning cytometer (LSC) and the Metafer/RCDetect microscope scanning system, both allowing for relocation of positive cells defined on the basis of fluorescence parameters. Both instruments were efficient in performing scanning and relocation; a difference in the recovery of CB-NRBC was not significant and can be explained by the method of preparation used.

Absence of HLA-G expression in macrophages of human decidua

PROBLEM

Macrophages - together with natural killer (NK) cells - constitute the majority of bone marrow derived infiltrating cells in the decidua. As interferon-gamma (IFN-gamma), a cytokine produced by NK cells, has been reported to induce expression of human leukocyte antigen (HLA-G) in monocytic cells, suggesting expression of HLA-G on decidua macrophages potentially stimulated by IFN-gamma, the question arises whether decidua macrophages in normal pregnancy express HLA-G.

METHOD OF STUDY

The study was based on immunohistochemistry and flow cytometry. In order to exclude that potentially elusive soluble HLA-G was not detected by immunohistochemistry, we performed in addition RT-PCR of flow-sorted decidua macrophages.

RESULTS

Our findings indicate that HLA-G is not present on macrophages of first trimester or term decidua in either membrane-bound or soluble form. Transcripts for soluble HLA-G1 and -G2 were not detected.

CONCLUSIONS

We exclude a role of HLA-G on the surface of decidua macrophages or of soluble HLA-G1 or -G2 as a secretory product of decidua macrophages with regard to interaction with HLA-G receptors present in or outside the decidua.

Physiological leukocytosis during pregnancy is associated with changes in glucose transporter expression of maternal peripheral blood granulocytes and monocytes

PROBLEM

The scarce data on glucose transporter expression of leukocytes are contradictory and nothing is known about changes accompanying physiological leukocytosis during pregnancy, which imposes acute metabolic demands on the cells.

METHOD OF STUDY

Cytospin preparations of intravascular leukocytes were searched immunocytochemically for the high affinity glucose transporters GLUT1, 3 and 4. Pregnancy-associated quantitative changes in transporter expression were assessed by flow cytometry.

RESULTS

Granulocytes and monocytes stained for GLUT1, 3 and 4. Major changes in cell surface transporter expression during pregnancy were a 36% (P < 0.05) down-regulation of granulocyte GLUT1 at term, and an increase in monocyte GLUT3 levels to 137% (P < 0.05), paralleled by a 24% (P < 0.05) decrease in GLUT4 content in second trimester. Apart from a minor subpopulation, lymphocytes were negative for these carriers.

CONCLUSION

GLUT1, 3 and 4 are abundantly expressed in granulocytes and monocytes. The particular isoforms are differentially regulated during pregnancy, suggesting an individual functional significance.