Chemokine receptor expression by human syncytiotrophoblast

Regulation and Function of Chemokines at the Maternal–Fetal Interface

Successful pregnancy requires the maternal immune system to tolerate the semi-allogeneic embryo. A good trophoblast function is also essential for successful embryo implantation and subsequent placental development. Chemokines are initially described in recruiting leukocytes. There are rich chemokines and chemokine receptor system at the maternal–fetal interface. Numerous studies have reported that they not only regulate trophoblast biological behaviors but also participate in the decidual immune response. At the same time, the chemokine system builds an important communication network between fetally derived trophoblast cells and maternally derived decidual cells. However, abnormal functions of chemokines or chemokine receptors are involved in a series of pregnancy complications. As growing evidence points to the roles of chemokines in pregnancy, there is a great need to summarize the available data on this topic. This review aimed to describe the recent research progress on the regulation and function of the main chemokines in pregnancy at the maternal–fetal interface. In addition, we also discussed the potential relationship between chemokines and pregnancy complications.

CXCL12 in normal and pathological pregnancies: A review

The survival of allogeneic fetuses during pregnancy is a rather paradoxical phenomenon with a complex mechanism. Chemokine ligand12 (CXCL12) and its receptors CXC chemokine receptor (CXCR)4 and 7 are extensively found in placenta tissues and cells, including trophoblast cells, vascular endothelial cells, and decidual stromal and decidual immune cells (eg, NK cells and regulatory T cells). Evidence has illustrated that the CXClL12/CXCR4/CXCR7 axis could enhance the cross talk at the maternal-fetal interface through multiple processes, such as invasion and placental angiogenesis, which appears to be critical signaling components in placentation and fetal outcome. In addition, an increasing number of studies have demonstrated that the CXCL12/CXCR4/CXCR7 axis also stands out for its pleiotropic roles in several pregnancy-associated diseases (eg, recurrent spontaneous abortion (RSA), pre-eclampsia (PE), and preterm labor). In the present review, the different biological properties and signaling in physiological and pathological pregnancy conditions of CXCL12/CXCR4/CXCR7 axis were discussed, with the aim of obtaining a further understanding of the regulatory mechanisms and highlighting their potential as a target for therapeutic approaches.

The role of trophoblast cell receptor expression in HIV-1 passage across the placenta in pre-eclampsia: an observational study

OBJECTIVE

To compare expression of markers of HIV and associated receptors (p24, CD4, CCR5 and ICAM-2) in placentae and umbilical cords of HIV-associated and pre-eclamptic pregnancies to elucidate any association between these conditions in mother-to-child transmission.

DESIGN

Cross-sectional immunohistochemical analysis of target receptor expression.

SETTING

Laboratory-based study of primigravidae attending a district hospital in South Africa.

POPULATION OR SAMPLE

Retrospectively collected placental tissue (stratified into four groups according to HIV status of normotensive and pre-eclamptic participants (n = 20/group).

METHOD

Immunohistochemistry utilising CD4 (1:1), p24 (1:10), CCR5 (1:80) and ICAM-2 (1:100) antibodies was performed using light microscopy for image acquisition and analysis.

MAIN OUTCOME MEASURES

Evaluate the expression of receptors on syncytiotrophoblast involved in in utero transmission of HIV.

RESULTS

Syncytiotrophoblast was immunopositive for CD4 and CCR5 antibody with greater expression of CCR5 in HIV-positive versus HIV-negative groups (F_1,159  = 6.979, P = 0.009) and normotensive versus pre-eclamptic groups (F_1,159  = 8.803, P = 0.003). p24 was present in both placentae and umbilical cords of babies that were HIV-negative at 6 weeks. ICAM-2 immunostaining was observed in the syncytiotrophoblast across study groups and was significantly higher in the HIV-negative pre-eclamptic group (χ² (3)  = 45.3; P < 0.001).

CONCLUSION

Concurrent CD4 and CCR5 receptor expression demonstrates possible in utero viral entry routes across the placental barrier. ICAM-2 expression may influence HIV passage across the placenta or restoration of risk of pre-eclampsia in HAART-treated mothers. HIV was found in fetal circulation regardless of antiretroviral treatment. Further confirmatory ultrastructural and molecular work is warranted.

TWEETABLE ABSTRACT

CD4, CCR5 and ICAM-2 on syncytiotrophoblast may facilitate HIV infection of passage across the placenta.

How has the study of the human placenta aided our understanding of partially methylated genes?

While the human genome sequence is relatively uniform between the cells of an individual, the DNA methylation of the genome (methylome) has unique features in different cells, tissues and stages of development. Recent genome-wide sequencing of the methylome has revealed large partially methylated domains (PMDs) in the human placenta. Unlike CpG islands and Polycomb-regulated regions, which can also have low levels of methylation, placental PMDs cover approximately 37% of the human genome and are associated with inaccessible chromatin and the repression of tissue-specific genes. Here, we summarize the interesting biological questions that have arisen as a result of finding PMDs in the human placenta, including how PMDs form, what they do, how they evolved and how they might be relevant to human disease.

Different regions of HIV-1 subtype C env are associated with placental localization and in utero mother-to-child transmission

HIV infections are initiated by a limited number of variants that diverge into a diverse quasispecies swarm. During in utero mother-to-child transmission (IU MTCT), transmitted viral variants must pass through multiple unique environments, and our previously published data suggest a nonstochastic model of transmission. As an alternative to a stochastic model of viral transmission, we hypothesize that viral selection in the placental environment influences the character of the viral quasispecies when HIV-1 is transmitted in utero. To test this hypothesis, we used single-template amplification to isolate HIV-1 envelope gene (env) sequences from both peripheral plasma and the placentas of eight nontransmitting (NT) and nine IU-transmitting participants. Statistically significant compartmentalization between peripheral and placental HIV-1 env was detected in one of the eight NT cases and six of the nine IU MTCT cases. In addition, viral sequences isolated from IU MTCT placental tissue showed variation in env V1 loop lengths compared to matched maternal sequences, while NT placental env sequences did not. Finally, comparison of env sequences from NT and IU MTCT participants indicated statistically significant differences in Kyte-Doolittle hydropathy in the signal peptide, C2, V3, and C3 regions. Our working hypothesis is that the hydropathy differences in Env associated with IU MTCT alter viral cellular tropism or affinity, allowing HIV-1 to efficiently infect placentally localized cells.

CXCL12/CXCR4 expression in trophoblasts takes part in materno-fetal immune tolerance and vascular remodeling

In this study, we investigated the expression of CXCL12 (SDF-1)/CXCR4 in trophoblasts and the role they play in the gestation. Immunochemistry was used to detect the expression of CXCR4 and CXCL12 in human villi and placenta. Highly purified extra-villous trophoblasts (EVTs) ere detected for CXCR4 and CXCL12 in vitro by immunocytochemistry. The chemotaxis of CXCL12 was tested in transwell and the chemotactic activity was quantitatively examined. It was suggested that both CXCR4 and CXCL12 were expressed in trophoblasts and were decreased with the gestation time P < 0.05). In a certain coverage, CXCL12 exhibited chemotactic activity which was positively correlated with its concentration [(r) = 0.68, P < 0.01], the maximum chemotactic index (CI) was 1.62 +/- 0.12. Our results suggest that interaction between CXCR4 and CXCL12 is involved in materno-fetal immunological tolerance in all three trimesters of gestation and contributes to the invasion of EVTs during pregnancy.

Distinct efficacy of HIV-1 entry inhibitors to prevent cell-to-cell transfer of R5 and X4 viruses across a human placental trophoblast barrier in a reconstitution model in vitro

Background and methods

HIV-1 cell-to-cell transmission is more efficient than infection of permissive cells with cell-free particles. The potency of HIV-1 entry inhibitors to inhibit such transmission is not well known. Herein, we evaluated the efficacy of this new class of antiretrovirals to block cell-to-cell transmission of HIV-1 in a model of reconstitution of the human placental trophoblast barrier in vitro.

Results

Our data show that CCR5 antagonists and T20 inhibit the passage of the virus across the BeWo cell monolayer in contact with PBMCs infected with an R5 (Ba-L) and a dualtropic (A204) HIV-1 with IC50s in the range of 100 – 5,000 nM for TAK779; 90 to 15,000 nM for SCH-350581 and 3,000 to 20,000 nM for T20. The CXCR4 antagonist AMD3100 is also effective against X4 HIV-1 infected PBMCs in our model with IC50 comprised between 4 nM and 640 nM. HIV-1 entry inhibitors are less efficient to block cell-to-cell virus transmission than cell-free HIV-1 infection of PBMCs and CCR5 antagonists do not prevent PBMC infection by dual tropic HIV-1 in contrast to cell-to-cell infection in our model.

Surprisingly, T20 (and C34) do not block cell-to-cell transmission of X4 HIV-1 but, rather, increase 80 to 140 fold, compared to control without drug, the passage of the virus across the trophoblast barrier. Additional experiments suggest that the effect of T20 on BeWo/PBMC-X4 HIV-1 is due to an increase of effector-target cells fusion.

Conclusion

Our results support further evaluation of HIV-1 coreceptor antagonists, alone or combined to other antiretrovirals, in a perspective of prevention but warn on the use of T20 in patients bearing X4 HIV-1 at risk of transmission.

Immunological mechanisms affecting angiogenesis and their relation to porcine pregnancy success

Prenatal mortality due to loss of lymphocyte-promoted endometrial angiogenesis is being investigated as a major cause of litter reductions during pregnancy in pigs. This review discusses immune mechanisms influencing porcine endometrial angiogenesis as well as additional signalling molecules that may play important roles in the compromise of peri-implantation and mid-gestation fetal pig survival. These include dendritic cells, signalling molecules such as toll-like receptors, chemokines and ficolins. Together these cells and molecules regulate immune responses and, ideally, protect the mother and prevent immune-based conceptus losses. Dendritic cells were recently shown to be angiogenic. Their tolerogenic role at the maternal-fetal interface coupled with the ability to secrete and respond to angiogenic factors suggests that dendritic cells are the key coordinators of angiogenesis at the porcine maternal-fetal interface. Chemokines coordinate the localization of immune effector and endothelial cells. The balance between pro-angiogenic and anti-angiogenic chemokines is addressed in relation to conceptus viability. Ficolins, components of the lectin-mediated complement activation pathway, are used for self/non-self recognition. Together, these components of the immune system could regulate lymphocyte- and non-lymphocyte-promoted endometrial angiogenesis to determine conceptus survival.

Downregulation of CCR5 expression on cells by recombinant adenovirus containing antisense CCR5, a possible measure to prevent HIV-1 from entering target cells

Chemokine (C-C motif) receptor 5 (CCR5) is one of the major co-receptors for the macrophage (M)-tropic HIV-1. To prevent HIV-1 from entering into target cells, we inhibited CCR5 expression on target cell surface by recombinant adenovirus containing anti-sense CCR5 cDNA. A fragment of 653 bp cDNA located in the 5' region of CCR5 cDNA was reversely inserted into pAdTrack-CMV. Recombinant adenovirus containing antisense CCR5 cDNA (Ad-antiR5) was obtained by homologous recombination of resultant plasmid with the adenoviral backbone plasmid pAdEasy-2 in E. coli BJ5183 and then packed in AD-293 cells. Rate of positive CCR5 on U937 cell surface measured by flow cytometry was decreased from 89.53% to 1.88% after U937 cells infected with Ad-antiR5 for 24 hours, and this reduction lasted at least for 10 days. After challenged with HIV-1, the U937 cells infected with Ad-antiR5 produced much less p24 antigen in cultured medium than those infected with control recombinant adenovirus and the uninfected cells. The recombinant adenovirus had no effect on chemotactic activity and proliferation of the U937 cells. Therefore, the recombinant adenovirus containing anti-sense CCR5 cDNA can down-regulate CCR5 expression on U937 cells and protect the cells from HIV-1 infection without effects on their chemotaxis activity and proliferation function.

Tumour necrosis factor-alpha stimulates HIV-1 replication in single-cycle infection of human term placental villi fragments in a time, viral dose and envelope dependent manner

Background

The placenta plays an important role in the control of in utero HIV-1 mother-to-child transmission (MTCT). Proinflammatory cytokines in the placental environment are particularly implicated in this control. We thus investigated the effect of TNF-α on HIV-1 expression in human placental tissues in vitro.

Results

Human placental chorionic villi fragments were infected with varying doses of luciferase reporter HIV-1 pseudotypes with the R5, X4-Env or the vesicular stomatitis virus protein G (VSV-G). Histocultures were then performed in the presence or absence of recombinant human TNF-α. Luciferase activity was measured at different time points in cell lysates or on whole fragments using ex vivo imaging systems.

A significant increase in viral expression was detected in placental fragments infected with 0.2 ng of p24 antigen/fragment (P = 0.002) of VSV-G pseudotyped HIV-1 in the presence of TNF-α seen after 120 hours of culture. A time independent significant increase of viral expression by TNF-α was observed with higher doses of VSV-G pseudotyped HIV-1. When placental fragments were infected with R5-Env pseudotyped HIV-1, a low level of HIV expression at 168 hours of culture was detected for 3 of the 5 placentas tested, with no statistically significant enhancement by TNF-α. Infection with X4-Env pseudotyped HIV-1 did not lead to any detectable luciferase activity at any time point in the absence or in the presence of TNF-α.

Conclusion

TNF-α in the placental environment increases HIV-1 expression and could facilitate MTCT of HIV-1, particularly in an inflammatory context.

Two Novel Proteins Bind Specifically to Trichosanthin on Choriocarcinoma Cell Membrane

Trichosanthin is the active protein component in the Chinese herb Trichosanthes kirilowi, which has distinct pharmacological properties. The cytotoxicity of trichosanthin was demonstrated by its selective inhibition of various choriocarcinoma cells. When Jar cells were treated with trichosanthin, the influx of calcium into the cells was observed by confocal laser scanning microscopy. When the distribution of trichosanthin-binding proteins on Jar cells was studied, two classes of binding sites for trichosanthin were shown by radioligand binding assay. Furthermore, the cytoplasmic membrane of Jar cells was biotinylated and the trichosanthin-binding proteins were isolated with trichosanthin-coupled Sepharose beads. Two protein bands with molecular masses of about 50 kDa and 60 kDa were revealed, further characterization of which should shed light on the mechanism of the selective cytotoxicity of trichosanthin to Jar cells.

Chemokine CXCL16, a scavenger receptor, induces proliferation and invasion of first-trimester human trophoblast cells in an autocrine manner

BACKGROUND

The aim of this study was to investigate whether CXCL16/CXCR6, a newly identified chemokine pair, is expressed in first-trimester human placenta and whether they affect the trophoblast cell biology, since we have found CXCR6 highly transcribed in first-trimester human trophoblast cells previously.

METHODS

We analysed the transcription and translation of CXCR6 and CXCL16 in purified first-trimester human trophoblast cells by real-time RT-PCR and immunochemical staining. We then examined the kinetic secretion of CXCL16 in the supernatant of primary-cultured trophoblast by enzyme-linked immunosorbent assay. We further investigated effects of CXCL16 on the proliferation and invasion of trophoblast cells in vitro.

RESULTS

We found the chemokine pair CXCL16/CXCR6 was transcribed and translated in first-trimester trophoblast cells and JAR line. In addition, the primary-cultured trophoblasts secreted CXCL16 spontaneously and continuously in 100-h culture. Treating trophoblasts with CXCL16 induced marked proliferation and invasion in vitro.

CONCLUSION

The findings from this study have demonstrated for the first time that CXCR6 and CXCL16 are co-expressed by first-trimester human trophoblast cells and stimulate their proliferation and invasion in an autocrine/paracrine manner. It suggests that CXCL16 plays important roles in human extravillous cytotrophoblast invasion and placentation.

Hypoxia-inducible factor-dependent histone deacetylase activity determines stem cell fate in the placenta

Hypoxia-inducible factor (HIF) is a heterodimeric transcription factor composed of HIFα and the arylhydrocarbon receptor nuclear translocator(ARNT/HIF1β). Previously, we have reported that ARNT function is required for murine placental development. Here, we used cultured trophoblast stem (TS)cells to investigate the molecular basis of this requirement. In vitro, wild-type TS cell differentiation is largely restricted to spongiotrophoblasts and giant cells. Interestingly, Arnt-null TS cells differentiated into chorionic trophoblasts and syncytiotrophoblasts, as demonstrated by their expression of Tfeb, glial cells missing 1 (Gcm1) and the HIV receptor CXCR4. During this process, a region of the differentiating Arnt-null TS cells underwent granzyme B-mediated apoptosis,suggesting a role for this pathway in murine syncytiotrophoblast turnover. Surprisingly, HIF1α and HIF2α were induced during TS cell differentiation in 20% O2; additionally, pVHL levels were modulated during the same time period. These results suggest that oxygen-independent HIF functions are crucial to this differentiation process. As histone deacetylase(HDAC) activity has been linked to HIF-dependent gene expression, we investigated whether ARNT deficiency affects this epigenetic regulator. Interestingly, Arnt-null TS cells had reduced HDAC activity,increased global histone acetylation, and altered class II HDAC subcellular localization. In wild-type TS cells, inhibition of HDAC activity recapitulated the Arnt-null phenotype, suggesting that crosstalk between the HIFs and the HDACs is required for normal trophoblast differentiation. Thus, the HIFs play important roles in modulating the developmental plasticity of stem cells by integrating physiological, transcriptional and epigenetic inputs.

Monocyte chemotactic protein-2 and -3 in amniotic fluid: relationship to microbial invasion of the amniotic cavity, intra-amniotic inflammation and preterm delivery

OBJECTIVE

To evaluate the presence of monocyte chemotactic protein (MCP)-2 and MCP-3 in cervical and amniotic fluid in women in preterm labor.

STUDY DESIGN

Cervical and amniotic fluid was sampled from women with singleton pregnancies (< or =34 weeks) in preterm labor (n = 58).

RESULTS

Monocyte chemotactic protein-2 (range: 80-583 pg/ml) and MCP-3 (range: 36-649 pg/ml) were detectable in 7/58 women in preterm labor. Monocyte chemotactic protein-3 was found significantly more often in amniotic fluid of women delivered within 7 days (P < 0.001), <34 weeks (P = 0.002), or with intra-amniotic inflammation (P < 0.001) and microbial invasion of the amniotic fluid (P = 0.003). Women in preterm labor had detectable levels of MCP-2 significantly more often if they gave birth before 34 weeks of gestation (P = 0.038) or had intra-amniotic inflammation (P = 0.042).

CONCLUSIONS

The presence of MCPs in amniotic fluid of women in preterm labor was associated with preterm birth before 34 weeks of gestation (MCP-2 and MCP-3), microbial invasion (MCP-3), and inflammation (MCP-2 and MCP-3) of the amniotic cavity.

Stromal cell-derived factor-1 (SDF-1) signalling regulates human placental trophoblast cell survival

Stromal cell-derived factor-1 (SDF-1 or CXCL12) is the physiologic ligand for the chemokine receptor CXCR4. CXCR4-mediated signalling regulates cell migration and apoptosis in certain haematopoietic and neuronal cells. Using gene profiling, we determined that CXCR4 is the only chemokine receptor for which mRNA expression is regulated during trophoblast differentiation in vitro. Based on the known effects of CXCR4 ligation, we hypothesized that CXCR4 activation may regulate placental trophoblast cell survival (i.e. protection from apoptosis), an important mechanism for the establishment and maintenance of the uteroplacental barrier. Human cytotrophoblasts (CTBs) were cultured in defined media and treated with graded doses of SDF-1 (10-100 ng/ml) or with an anti-CXCR4 neutralizing antibody. Exposure to anti-CXCR4 antibody reduced CTB cell numbers by 25-40%. Treatment with SDF-1 decreased the proportions of apoptotic terminal deoxynucleotidyl transferase-mediated dUTP-FITC nick-end labelling(+) cells (apoptotic index [AI] of 2.79+/-0.61% [control] versus 1.88+/-0.56% [SDF-1]; P<0.05) and caspase-activated cells (AI of 7.95+/-2.49% [control] versus 3.81+/-1.49% [SDF-1]; P<0.05). We determined that SDF-1 also activated the triple MAP Kinase isoforms ERK1/2 and p38 in trophoblasts. Immunocytochemistry confirmed SDF-1-induced nuclear translocation of phosphorylated ERK1/2. Blocking of ERK1/2 signalling with the specific inhibitor PD98059 reversed SDF-1-mediated inhibition of apoptosis (AI of 1.65+/-0.34 [SDF-1] versus 3.50+/-0.5 [SDF-1 + PD98059]; P<0.05), suggesting that SDF-1 acts through this pathway as a trophoblast survival factor. These results indicate that SDF-1/CXCR4 signalling stimulates anti-apoptotic pathways in cultured trophoblasts. This chemotactic ligand/receptor system may promote trophoblast survival during pregnancy. Alterations in SDF-1 and/or CXCR4 expression or function may be associated with specific pregnancy disorders.

Differential expression of CXCR4 receptor in early and term human placenta

Chemokines and their receptors play a crucial role in regulation of T-cell migration and differentiation. Recent findings suggest that these proteins can also regulate cell functions such as angiogenesis and proliferation. Besides, CXCR4, a chemokine receptor, is one of the two major co-receptors for entry of the HIV virus during the late stages of HIV infection. We have studied the expression of CXCR4 in early (8-10 weeks) and term human placenta. Immunofluorescence staining and RT-PCR analysis revealed a differential expression of the CXCR4 receptor. Densitometric analysis revealed a two fold higher expression of the CXCR4 mRNA in early as compared to term placenta. This finding suggests that the expression of CXCR4 receptor may be developmentally regulated and its role in the early stages of pregnancy is implicated, when embryogenesis and organogenesis takes place. The fact that only 1-2 per cent of the placental transmission of the HIV virus takes place in the early placenta may also be correlated with our findings, suggesting that CXCR4 may not have a direct role in the transmission of HIV infection in the placenta.

Evaluation of Cytokeratin 7 as an accurate intracellular marker with which to assess the purity of human placental villous trophoblast cells by flow cytometry

Villous trophoblast cells (TC) obtained from first trimester and term human placentae after trypsin/Percoll gradient isolation were immunodepleted of contaminant cells. The level of purity was assessed by the intracellular expression of the pan trophoblast marker cytokeratin-7 (CK7) and comparisons were made with the GB25 trophoblast-specific (cytotrophoblast+syncytiotrophoblast) cell surface marker. The presence of contaminating cells was traced with intracellular vimentin, or cell surface CD2, CD36, and CD163 markers and evaluated by flow cytometric analysis. The pattern of CK7 expression by trophoblast cells was also analyzed by immunofluorescence microscopy. Most batches of TC from first trimester or term placentae (92+/-3% and 96+/-2%, respectively) showed a high percentage of CK7 expressing cells, with less than 2% contaminating vimentin positive cells. In some batches of TC with a lower percentage (65+/-4%) of CK7-expressing cells, no vimentin was found, but a low percentage of CD36-expressing cells was evidenced, with no presence of CD2, and/or CD163-expressing cells. The intracellular CK7 signal correlated significantly with that of GB25 (p<0.05) cell surface expression in TC of term placentae. The choriocarcinoma BeWo and Jar cell lines also showed high levels (>92%) of CK7-expressing cells. Conversely, the control U87 astrocytoma cell line showed a high percentage (>90%) of vimentin but no CK7-expressing cells. These results provide evidence that the mutually exclusive pattern of intracellular CK7/vimentin expression of human TC can be used for evaluation by flow cytometry of the purity of primary human trophoblast cells.

The Expression of CXCR4/CXCL12 in First-Trimester Human Trophoblast Cells1

Chemokines and chemokine receptors have been implicated as pivotal players in many physiological and pathological situations, but little is known about the expression and function of chemokines and chemokine receptors at the materno-fetal interface. In this study, we first analyzed the transcription of 18 chemokine receptors in first-trimester human trophoblast cells. Among these receptors, CXCR4 was found highly transcribed. We demonstrated afterward that both CXCR4 and CXCL12 (stromal cell-derived factor-1; SDF-1) were expressed in trophoblast cells. Primary cultured trophoblast cells were also found secreting CXCL12 spontaneously. To identify the functional role of CXCR4/CXCL12 in these cells, we treated trophoblast cells with recombinant human (rh)SDF-1 alpha and analyzed the cell viability and signaling pathway. The results showed that rhSDF-1 alpha increased the viability of trophoblast cells and the activation of extracellular signal-regulated kinases signaling pathway in vitro. Our findings suggest that first-trimester trophoblast cells express functional CXCR4/CXCL12, which may play an important role in early pregnancy such as stimulating trophoblast cell proliferation or differentiation in an autocrine manner.

High prevalence of autoreactive, neuroantigen-specific CD8+ T cells in multiple sclerosis revealed by novel flow cytometric assay

Multiple sclerosis (MS) is an inflammatory, demyelinating disease of the central nervous system (CNS) with features suggestive of T-cell-mediated pathology. Most prior reports have focused on CD4(+) T cells with the underlying assumption that MS is predominantly a CD4(+) T helper 1 (Th1)-mediated disease. In this report, we used a novel flow cytometric approach to evaluate autoreactive T-cell responses against a large variety of neuroantigenic targets. We found that both CD4(+) and CD8(+) T cells targeted against several CNS autoantigens were widely prevalent in patients with MS and healthy individuals. Whereas the distribution of CD4(+) responses was similar in different groups, patients with relapsing-remitting MS showed a higher proportion of CNS-specific CD8(+) responses. Autoreactive CD4(+) T cells from patients with MS exhibited a more differentiated Th1 phenotype compared with healthy subjects. Similarly, CNS-specific CD8(+) T-cell responses from patients with MS were functionally distinct from those in healthy individuals. Collectively, these studies reveal the high prevalence of class I-restricted autoreactive CD8(+) T-cell responses in MS that has been underappreciated thus far. The results emphasize the need to evaluate both CD4(+) and CD8(+) T-cell responses in MS and to make both subsets a consideration in the development of novel therapeutic strategies.

Trophoblasts acquire a chemokine receptor, CCR1, as they differentiate towards invasive phenotype

At the human feto-maternal interface, trophoblasts differentiate towards extravillous trophoblasts (EVTs) and form the cell column. EVTs acquire invasive activity in the distal part of the cell column and begin to migrate into the maternal tissue. We previously reported that dipeptidyl peptidase IV (DPPIV) is expressed on EVTs in the proximal part of cell column and is involved in the inhibition of their migration. Because DPPIV has been shown to degrade several chemokines, we examined possible roles of chemokines in EVT migration. Immunohistochemistry demonstrated that C-C chemokine receptor 1 (CCR1) was hardly detected on cytotrophoblasts and syncytiotrophoblast but was expressed on EVTs in the cell column. In vitro, CCR1 protein was also present on the surface of EVTs that grew out from chorionic villous explants cultured under 20% O2. Chemokines that can bind to CCR1 (CCR1 ligands), such as regulated on activation, normal T cell expressed and secreted (RANTES) and macrophage inflammatory protein-1alpha (MIP-1alpha), were confirmed in the decidual tissues by RT-PCR and immunohistochemistry. These CCR1 ligands promoted the migration of the EVTs that were isolated from the explant cultures in vitro. These results indicate that CCR1 is expressed on trophoblasts as they differentiate to EVTs and that CCR1 ligands produced from the decidual tissue induce EVT migration. By contrast, CCR1 was scarcely expressed on EVTs that grew out from villous explants cultured in 1% O2, indicating that a relatively high oxygenic environment is needed to induce CCR1 expression. Moreover, CCR1 expression on the isolated EVTs was significantly reduced in the presence of decidua-conditioned medium. Such regulation of CCR1 by surrounding oxygenic and decidual environments supports a close correlation between EVT invasion and their expression of CCR1. This study demonstrates that trophoblasts acquire CCR1 as they differentiate to an invasive phenotype at the villus-anchoring sites and indicates a novel role for the chemokine-CCR1 system in the initial step of trophoblastic invasion towards the maternal tissue.

Predominant Intracellular Expression of CXCR4 and CCR5 in Purified Primary Trophoblast Cells from First Trimester and Term Human Placentae

PROBLEM

The aim of the present study was to define the expression of CXCR4 and CCR5 on non-cultured non-stimulated primary human trophoblast cells (TCs) immediately after their immunopurification.

METHOD OF STUDY

We have evaluated by flow cytometric analysis and immunofluorescence, highly purified primary TCs prepared from first trimester (8.2 +/- 0.3 weeks, n = 15) and term (Caesarean section, n = 10) placentae for the cell surface and intracellular expression of CXCR4 and CCR5.

RESULTS

There was a high level of individual variability for CXCR4 and CCR5 expression between trophoblast batches. In first trimester and term placentae TCs, we found a greater number of TCs preparations expressing intracellular CXCR4 than CCR5 (P < 0.05). Both receptors were predominantly localized in the intracellular compartment of TCs, whatever if isolated from first trimester or term placentae.

CONCLUSIONS

The functional consequences of the predominance of CXCR4 expression and of cellular addressing are briefly discussed.

Regulation of blastocyst migration, apposition, and initial adhesion by a chemokine, interferon gamma-inducible protein 10 kDa (IP-10), during early gestation

For a pregnancy to be established, initial apposition and adhesion of the blastocyst to maternal endometrium must occur in a coordinated manner; however, a key factor(s) that mediates the trophoblast cell migration and attachment to the apical surface of the endometrium has not been identified. In this study, we examined the effect of an endometrial chemokine, interferon-gamma-inducible protein 10 kDa (IP-10), on conceptus migration to the endometrial epithelium. We first studied endometrial IP-10 mRNA expression, which was localized in the subepithelial stromal region, and detected the protein in the uterine flushing media during early pregnancy. Expression of IP-10 mRNA by the endometrium of cyclic animals was stimulated by the addition of a conceptus factor interferon-tau (IFN-tau). Immunofluorescent analysis revealed that IP-10 receptor, CXCR3, was localized in the trophoblast cells, to which biotinylated-recombinant caprine IP-10 (rcIP-10) bound. Chemotaxis assay indicated that rcIP-10 stimulated the migration of trophoblast cells, and the effects of rcIP-10 were neutralized by the pretreatment with an anti-IP-10 antibody. Adhesive activity of trophoblast cells to fibronectin was promoted by rcIP-10, and the effect was inhibited by the use of anti-IP-10 antibody. Further adhesion experiments demonstrated that binding of trophoblast cells to fibronectin was completely inhibited by a peptide of the Arg-Gly-Asp (RGD) sequence, which binds to integrins alpha5beta1, alphaVbeta1, alphaVbeta3, and alphaVbeta5, whereas non-binding peptide containing Arg-Gly-Glu (RGE) had minimal effects. More importantly, rcIP-10 promoted the adhesion of trophoblast cells to primary cells isolated from endometrial epithelium. Furthermore, rcIP-10 stimulated the expression of integrin alpha5, alphaV, and beta3 subunit mRNA in trophoblast cells. These findings suggest that endometrial IP-10 regulates the establishment of apical interactions between trophoblast and epithelial cells during early gestation.

Effect of CCR5-delta32 heterozygosity on the risk of perinatal HIV-1 infection: a meta-analysis

Several studies have investigated whether heterozygosity for a 32-basepair deletion in the CC chemokine receptor 5 gene (CCR5-Delta32 ) affects susceptibility to perinatal HIV-1 infection, but results have been inconclusive. We performed a meta-analysis of published data from 11 studies of HIV-1 perinatally exposed children who were genotyped for the CCR5-Delta32 polymorphism. The crude overall HIV-1 infection rates, by simple data pooling, were 20% (one of five) amongCCR5-Delta32 homozygote children, 39% (131 of 335) among CCR5-Delta32 heterozygote children, and 40% (1408 of 3526) among wild-type CCR5 homozygote children. Compared with wild-type homozygotes, the random effects risk ratio for heterozygotes was 1.04 (95% confidence interval [CI], 0.92-1.17) among all children (N = 3861) and 1.03 (95% CI, 0.90-1.17) among those of European descent (n = 2890). Results were similar when adjusted for the available data on the CCR2-641 polymorphism (n = 1542). The meta-analysis clarifies that perinatal infection is not significantly altered by heterozygosity for CCR5-Delta32 in the child.

Human herpesvirus 6 variant a infects human term syncytiotrophoblasts in vitro and induces replication of human immunodeficiency virus type 1 in dually infected cells

Human herpesvirus 6 (HHV-6) and human immunodeficiency virus type 1 (HIV-1) may interact during transplacental transmission of HIV-1. The placental syncytiotrophoblast layer serves as the first line of defense of the fetus against viruses. Patterns of replication of HHV-6 variant A (HHV-6A) and HIV-1 were analyzed in singly and dually infected human term syncytiotrophoblast cells cultured in vitro. For this purpose, the GS strain of HHV-6A and the Ba-L and IIIB strains of HIV-1 were used. HHV-6A replication was restricted at the level of early gene products in singly infected syncytiotrophoblasts, whereas no viral protein expression was found in cells infected with HIV-1 alone. Coinfection of syncytiotrophoblast cells with HHV-6A and HIV-1 resulted in production of infectious HIV-1. In contrast, no enhancement of HHV-6A expression was observed in cell cultures infected with both viruses. Uninfected syncytiotrophoblast cells were found to express CXCR4 and CCR3 but not CD4 or CCR5 receptors. Infection of syncytiotrophoblasts with HHV-6A did not induce CD4 expression and had no influence on chemokine receptor expression. Activation of HIV-1 from latency in coinfected cells was mediated by the immediate-early (IE)-A and IE-B gene products of HHV-6A. Open reading frames U86 and U89 of the IE-A region were able to activate HIV-1 replication in a synergistic manner. The data suggest that in vivo double infection of syncytiotrophoblast cells with HHV-6A and HIV-1 could contribute to the transplacental transmission of HIV-1 but not HHV-6A.