Immunocytological evidence for hematopoiesis in the early human placenta

Hematopoiesis has previously been observed in the human yolk sac, in placental villi and in the embryonic aorta. Here, our immunocytological study at 24 and 35 days showed packed erythroblasts in the placental vessels, mitotic figures and anti-Ki-67 reactions within these cells. Morphologically, the erythroblasts and vessels were similar to those found in the yolk sac during primitive hematopoiesis. In addition, numerous extravascular erythroblasts were found in the villous core. Positive reactions were obtained in erythroblasts using antibodies against glycophorin-A, GATA-2 and C-kit that characterize the hematopoietic cells. However, erythroblasts did not react with anti-CD34 and anti-CD45. In this respect, they differ from the hematopoietic cell clusters observed in the aorta of the human embryo. The staining for glycophorin-A was maintained in erythroblasts at 6-7 weeks and 12-14 weeks. Anti-GATA-2 reaction was decreased in erythroblasts and appeared in the perivillous cytotrophoblast. Anti-C-kit signal was detected in endothelial cells at 6-7 weeks and switched to stromal and perivascular cells at 12-14 weeks. By term, anti-GATA-2 staining was still present in the trophoblast and appeared in vessels while anti-C-kit was negative. For the leukocytes marker CD15, a staining was found in the endothelium at 35 days, 6-7 and 12-14 weeks and in leukocytes at term. CD45 antibody decorated the leukocytes at 12-14 weeks and at term. Erythroblasts undergo a primitive hematopoiesis in the early placental vessels that may be of value for the embryo in a period of low oxygen environment.

Separation of trophoblastic and vascular cell lineages and vascular maturation in early human placental development

The trophoblast and vascular cell lineages have been studied by immunohistochemistry at 6 and 12-14 weeks of pregnancy. Perivillous and extravillous cytotrophoblasts were specifically stained by anti-cytokeratin 7 whereas endothelial cells were labelled by anti-CD34 at these two stages of pregnancy. Perivillous and extravillous cytotrophoblasts together with erythroblasts showed mitotic figures and anti-Ki67 positive nuclei at the 6th week. In the perivillous cytotrophoblast, the number of Ki67 positive nuclei decreased by 12-14 weeks and the staining was limited to the proximal extravillous trophoblast of cell islands. Some endothelial and perivascular cells were labelled with anti-Ki67 at 12-14 weeks. Erythroblasts did not stain at all at this stage. Endothelial cells bound lectin UEA1 and vessels exhibited a fluorescent signal after anti-myosin staining at 12-14 weeks. These data showed that the cytotrophoblast and endothelial cell lineages are not related from 6 to 12-14 weeks of pregnancy. Because mitotic figures or anti-Ki67 staining were not observed in endothelium or perivascular cells at the 6th week, it seems likely that the endothelial cells committed to vasculogenesis derived from stromal cells. By 12-14 weeks, endothelial cells had nearly achieved their maturation by acquiring 1-fucosyl-binding sites revealed by UEA1-lectin binding and insuring their own renewal by mitosis. The maturation of perivascular cells at 12-14 weeks was shown by the anti-sm-myosin staining. We conclude that placental vasculogenesis involves mesenchymal cells rather than trophoblast. The differenciation of vessels organizing from random plexi to a vascular arborescence may involve paracrine regulatory loops with the trophoblast.

HLA-G expression in trophoblast cells is independent of embryonic development

HLA-G is a nonclassical major histocompatibility complex class I molecule that is selectively expressed on cytotrophoblasts at the feto-maternal interface where it may play a major role in maternal-fetal tolerance. In this study, we compared HLA-G expression in trophoblasts from normal and pathologic pregnancies by immunohistochemical analysis. First, we found a defective HLA-G expression in miscarriages associated with hypotrophic but normal eggs. Conversely, by studying molar pregnancies, we observed a high HLA-G expression in complete and partial hydatidiform moles. Finally, HLA-G expression could be visualized in extravillous trophoblasts that develop outside of their normal environment, as reported here in ectopic pregnancies. Taken together, these results suggest that HLA-G expression in extravillous trophoblasts is induced in an autonomous manner, independently of embryonic development, and may be an integral part of placental development allowing its tolerance from maternal immune system.

[Cytological screening of uterine cervical cancer by samples in liquid medium (CytoRich). Preliminary study of a series of 111 292 patients]

We report on the preliminary results of a series of 111,292 patients who benefited from a liquid medium sample (CytoRich) for cervical cancer screening. The number of dubious or limited smears was reduced by 0.03% and 0.53% respectively. The junction zone was better explored, and metaplastic changes were observed in 35.71% of the cases. This method improved the identification of low-grade lesions by +56% (2751/111,292; 2.47%) and of high-grade lesions by +75% (860/111,292; 0.77%), with a reduction in the number of ASCUS/AGUS by -44% (2065/111,292; 1.85%). This preliminary study confirms the results already published. The results demonstrating cytohistological correlation should prove to be a decisive factor, enabling the testing of the sensitivity and specificity of this technique. It will then be possible to envisage a future 'new paradigm' for screening cervical cancer as the result of a liquid medium sample, computer-assisted screening and HPV viral identification by Hybrid capture II.

Evidence for infection of the human embryo with adeno-associated virus in pregnancy

Previous reports have demonstrated the presence of DNA of the human helper virus-dependent adeno-associated parvovirus (AAV) in uterine tissue and curettage material from early miscarriage. To examine infection of embryonic tissue during pregnancy, amnion fluids were analysed for the presence of AAV. Using polymerase chain reaction, AAV DNA was detected in 64 out of 238 DNA samples extracted from amnion cells. DNA of helper viruses were found in 12% (papillomavirus) and 18% (cytomegalovirus) of the samples (double infections with AAV in eight and nine cases, respectively). Furthermore, infectious AAV virions were found in 13 out of 43 AAV DNA-containing samples. In mothers with AAV DNA-positive amnion fluids, premature amniorrhexis and premature labour occurred significantly more frequently (P < 0.001). Using an immunofluorescence assay, 24% of newborn sera (unrelated to the amnion fluid samples) were found to contain IgM antibodies to AAV, in most cases paralleled by IgM antibodies in the mother's sera. The data demonstrate that AAV infection can occur in utero at early and at late stages of pregnancy. The observed complications at delivery should encourage studies to clarify possible pathological consequences of AAV infection in pregnancy and a possible latent infection of the fetus.

Human genital tissues containing DNA of adeno-associated virus lack DNA sequences of the helper viruses adenovirus, herpes simplex virus or cytomegalovirus but frequently contain human papillomavirus DNA

The detection of DNA of the helper virus-dependent adeno-associated virus type 2 (AAV-2) in biopsies of material from spontaneous abortion and in tissue samples from the uterus raises the question of whether sequences of known helper viruses can be detected simultaneously within the same specimen despite the lack of histological evidence for the presence of lytic viruses. Therefore, we performed PCR analyses with primers detecting DNA sequences of viruses (adenovirus, herpes simplex virus and human cytomegalovirus) known for their helper activity in the replication of adeno-associated viruses. In addition, PCR was performed to detect DNA of human papillomaviruses (HPV), which were recently shown to be able to help AAV replication in vitro. In no cases were sequences of the known helper viruses found. However, HPV DNA was detected in approximately 60% of paraffin sections from uterus biopsies and cervical lesions containing AAV DNA and in approximately 70% of material from early miscarriage. This finding suggests that HPV may be a helper virus for AAV.

Interaction of human papillomavirus type 16 and adeno-associated virus type 2 co-infecting human cervical epithelium

Recently, we hypothesized that the tumour-suppressive, human helper-virus-dependent, adeno-associated parvoviruses (AAV) may interfere with transforming functions of human papillomaviruses (HPV) in the development of cervical carcinoma. Here, we demonstrate that in cervical epithelium containing papillomavirus DNA, AAV DNA can be detected in a replication-competent form and that AAV proteins are expressed. In cultured cells containing integrated AAV-2 DNA, transfection of HPV-16 DNA induced rescue of infectious AAV-2, revealing helper functions of HPV-16. Similarly, cotransfection of HPV-16 and AAV-2 DNAs into human epithelial cell lines led to replication of AAV-2, and, in keratinocytes, to a cytopathic effect. These data suggest an interaction of the two viruses, possibly influencing the development of HPV-related lesions.

Antagonism of 2 virus-infections in the development of cervical-cancer - (review - hypothesis)

The recent detection of DNA of the human adeno-associated viruses in the majority of biopsies of the cervix uteri suggests an interaction of these tumor suppressive parvoviruses with human papillomaviruses which are causally linked to the development of cervical cancer. Based on available virological and pathological data, a hypothesis is presented on a probably antagonistic action of the two viruses in cells of the cervical epithelium. The presence of viruses with oncosuppressive properties in the tissue which is the main target of transformation by papillomaviruses should stimulate investigations on interactions of these two viruses to improve prevention and therapy of genital cancer.

Detection of adeno-associated virus DNA in human genital tissue and in material from spontaneous abortion

The human helper virus-dependent parvovirus, adeno-associated virus (AAV) has never been associated with disease in humans [Berns et al. (1987): Advances in Virus Research 32:243-306; Siegl et al. (1985): Intervirology 23:61-73]. However, in pregnant mice, infection with AAV induces early abortion [Botquin et al. (1993): Journal of Cancer Research and Clinical Oncology 119:24]. We investigated whether this common human virus may be found in human genital tissue or in curettage material from spontaneous abortion. Using the polymerase chain reaction (PCR) AAV type 2 DNA was amplified in histological sections of 19 of 30 biopsies of the uterine mucosa. In addition, AAV-2 DNA was detected in abortion material during the first trimester of pregnancy (12/30 cases were positive) but not in material of abortion from the second or third trimester (9 cases). Whereas in tissues from the uterus AAV DNA was found only by PCR, large amounts of viral DNA were detectable by Southern blot analysis in abortion material. In situ hybridization revealed DNA of AAV to be present in the villous moiety (trophoblast) of the placenta but not in the embryo or decidua. in the same cells, AAV proteins (including the replication-associated rep proteins) were detected by immunofluorescence analysis. These results suggest (1) that AAV infects the uterine mucosa (possibly persistently) and (2) that it can replicate in trophoblast cells. This might disturb placenta development and may play a role in early miscarriage.(ABSTRACT TRUNCATED AT 250 WORDS)