The 4th Conference of the International Federation of Placental Associations, Tokyo, Japan, 1-3 October 1998

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CONFERENCE REPORT The 4th Conference of the International Federation of Placental Associations, Tokyo, Japan, 1–3 October 1998 S. R. Sooranna Department of Maternal & Fetal Medicine, Division of Paediatrics, Obstetrics & Gynaecology, Imperial School of Medicine, Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH, UK Paper accepted 6 November 1998

Tokyo Medical College Hospital was the venue for the fourth IFPA meeting which was held in conjunction with the sixth Conference of the Japanese Placenta Association and the sixteenth Annual Meeting on Trophoblastic Diseases. The Medical College is located in the Shinjuku area of the city, close to the JR Station and next door to the Tokyo Hilton Hotel where many of the participants stayed. The meeting was truly international in attracting over 200 participants from 26 different countries. With 32 plenary lectures, three distinguished guest speakers and two educational seminars, 12 workshops with some 82 speakers and 124 poster presentations, the meeting was a great success for all participants. The President of the meeting was Professor Masaomi Takayama who organized it in conjunction with colleagues and several medical students, all based at the Tokyo Medical College Hospital. Professor Takayama opened the meeting, the main theme of which was ‘the control mechanism of proliferation and invasive function of placental trophoblastic cells’. In his opening remarks he emphasized that these topics were the main subjects of both participating study groups and he talked about the importance of human pregnancy in archaeological times. Indeed, the logo of the meeting was a Jamon clay figure depicting a pregnant woman from the Sapporo area of Japan dating back to around 2000 years . The scientific program was professionally arranged and each section was chaired by two eminent chairpersons, invariably one from the host country and one from abroad. It was fitting that the first session of the scientific meeting was initiated by Professor Hiroaki Soma, a distinguished long-standing member of both the IFPA and the JPA. His lecture dealt with the identification of Gaucher cells in the chorionic villi associated with recurrent hydrops fetalis. Although Gaucher’s disease is rare in the Japanese population (1 : 500 000), placental examination is advised in order to detect the risk of recurrence in subsequent pregnancies. Professor Peter Kaufmann followed with a talk on the pathology of trophoblast invasion using his now legendary cascades of superimposed overhead projections. As with any subject he tackles, the lecture was clear and the audience was 0143–4004/99/040281+04 $12.00/0

treated to a visual display of the sequential steps of the biological processes of interest. In this case he dissected the steps of normal haemochorial placentation and showed that when cells leave the proliferative phase they enter the invasive phase and express Fas (CD95) and TNF receptors followed by activation of the initiator caspases (e.g. caspase 8). When compared to abnormal pregnancies, such as pre-eclampsia or tubal pregnancy, it seems that the switches for these processes are not clearly defined. Hence extravillous trophoblast cannot be clearly classified into distinct proliferative and invasive phenotypes. Dr Donald Morrish used subtractive cDNA libraries of in vitro differentiating term cytotrophoblast to determine possible genetic regulators of human trophoblast differentiation. Using this relatively new technique his group cloned two novel genes, PL74 and PL48. PL74 is a new member of the TGF-â family that is expressed by normal and choriocarcinoma cells and it inhibited cell proliferation. Its expression was regulated by IFN-ã and EGF. PL48 is a tumour-suppressor gene which, when transfected into BeWo cells, inhibited cell proliferation and induced apoptosis. This gene also induced differentiation in some cells. The role of the matrix metalloproteinases in mediating trophoblastic invasion during implantation was the subject of Dr Chikashi Tachi’s lecture. His data showed that trophoblast cells strongly express MT1-MMP during active endometrial invasion in vivo and that this expression is downregulated by cell-cell contact. Unexpectedly, in the less invasive goat trophoblast, MT1–MMP expression was also evident. Dr Paul Bischof carried on the theme of trophoblast invasion by looking at endometrial factors that regulate this process. The endometrial cytokines such as LIF, TNF, TGF-â and Il-1 markedly influenced the secretion and/or activation of MMP-2 (gelatinase A), MMP-9 (gelatinase B) and TIMP. Dr Toshihiko Terao talked about a specific urinary trypsin inhibitor (UTI) found in fetal urine and amniotic fluid which has anti-inflammatory properties. This 67-kDa glycoprotein, consisting of 143 amino acids, depressed the production of inflammatory cytokines such as Il-1 and Il-8. UTI, when given as vaginal suppositories, inhibited premature cervical ripening  1999 W. B. Saunders Company Ltd

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induced by Il-8 probably by regulating the concentration of calcium ions. He concluded that the substance may be helpful in the treatment of pre-term labour. The last plenary lecture of the morning session was given by Professor Gernot Desoye who revitalized interest in endothelin, the most potent vasoconstrictor known to date, being 10 times more potent than angiotensin II. His investigations of endothelin and its receptor distribution in trophoblast from normal and pre-eclamptic pregnancies suggested that ET-1 stimulates the proliferation of first trimester trophoblast via ETA and ETB receptors, whereas the invasion-stimulating effect is mediated only via the ETB receptor. Such differential receptor effects corresponded with the receptor location (i.e. the proliferative trophoblast expressed ETA and ETB receptors whereas the invasive phenotype expressed the ETB receptors). The evidence presented by Professor Desoye highlighted the role that endothelin and its receptors play in the complex processes regulating trophoblast invasion. The first of three specially invited lectures was given at the end of the morning session. Professors Takayama and Boyd introduced Professor Hiroshi Nakajima, who is Director General Emeritus of the World Health Organization, to speak on reproductive health as priority care for the 21st century. Professor Nakajima, a distinguished neurophysiologist who has recently retired from active research, talked about the broader aspects of reproductive health incorporating discussions on the social, ethical as well as political dimensions of the subject. One of the major goals of the WHO is that all men and women should have the right to safe, effective, affordable and acceptable methods of fertility controls of their choice. There should be integration of maternal and child health and family planning. He talked about unsafe abortions and the effects of diseases such as AIDS on reproductive health. Another major priority of the WHO is a Safe Motherhood Campaign and a major target is to reduce maternal mortality by half within the next 5 years. The second and third specially invited lectures were equally impressive and well delivered. The second, by Professor Norio Wake of Kyusyu University, was given at the end of the afternoon session of the first day. He talked about the molecular mechanisms of choriocarcinoma development. His group had concentrated on defining a critical region on chromosome 7 that was invariably missing in surgically removed choriocarcinoma tissues and cell lines and their observations of bi-allelic deletions strongly suggest the presence of tumour suppressor gene(s) within this region. H19, which is a maternally derived imprinted gene, is enhanced in choriocarcinomas and its regulation may be essential for normal development. The third special lecture was given by Professor Geoffrey Altshuler from the University of Oklahoma, Health Sciences Centre, at the end of the morning session of the second day. He skilfully reviewed how placental pathology can give clues for the inter-disciplinary clarification of fetal disease. His lecture contained strong-held personal views such as the need for a greater say by the basic scientist to verify pathologyadduced placental causes of perinatal diseases. As expected,

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his concluding remark that ‘the placenta is like a diary of gestational life’, was well received by the audience. Over the 3 days two educational seminars were given over the lunch periods. The first, by Dr Sumiharu Noji, was on the molecular mechanisms of limb initiation, formation and development in the vertebrate. His elegant experiments using chick embryos showed the importance of members of the fibroblast growth factor family (in particular FGF8 and 10) in these processes. In attempts to elucidate the factors determining limb identity, Dr Noji’s group cloned chick Tbx5 and Tbx4 genes to use as forelimb and hindlimb markers, respectively. He concluded that expression of these genes in the limb bud was involved in limb identities in all vertebrates. The second lunch-time seminar was given by Dr Christoph Simm, who is one of that rare breed who possess doctorates in medicine as well as physics. He lectured on the new developments in diagnostic ultrasound technology and although I think that a large part of this talk was above the heads of most of the audience, the amazing progress shown to have been made in ultrasound imaging over the last 20 years impressed everyone. The Plenary Session for the afternoon concentrated on gestational trophoblastic disease (GTD) mostly from various countries in Eastern Asia. These were given by Dr Sompop Limpongsanurak (Thailand), Dr Gabor Than (Hungary), Dr Su-Cheng Huang (Taiwan), Dr Setsuko Goto (Japan) and Dr Danh Do Duc (Vietnam). Unfortunately Dr Shilang Wang (China) was unable to obtain a visa to attend. These lectures related experiences of GTD management in the different countries. Actinomycin-D and methotrexate appeared to be the treatment of choice in most centres for low risk cases, whereas high risk management additionally required the inclusion of chemotherapy with vincristine and cyclophosphamide. The evening session of the first day commenced with Professor Peeyush Lala who discussed in detail the control mechanisms of proliferation and invasion in human trophoblast and their alteration during trophoblastic tumour progression. His group used extravillous trophoblast (EVT) cells of the human placenta which are able to proliferate, migrate and invade the decidual tissues in vivo. In vitro, these functions of EVT cells from normal first trimester pregnancies were shown to be stringently controlled by numerous growth factors. Transfection of EVT cells by SV40 Tag produced immortal, hyperproliferative and hyperinvasive cells which were deficient in gap junctional intercellular communication but were incapable of anchorage independent growth or tumorigenicity in nude mice. The transition of normal EVT cells to the premalignant type was associated with several changes, such as a downregulation of connexin-40, TIMP-1 and TIMP-2. He hoped that these cells would provide a new in vitro model for studies of stage-specific genetic changes responsible for trophoblastic tumour progression. Dr André Malassiné’s talk on the hormonal regulation of trophoblast differentiation emphasized the importance of the connexins in this process. His group showed that oestradiol, dexamethasone and hCG specifically stimulated differentiation, while progesterone was ineffective and that TGF-â1

Sooranna: Conference Report

and endothelin-1 inhibited trophoblastic fusion. Professor Kathleen Shiverick spoke on the dysregulation of trophoblast and endometrial gene expression by environmental endocrine disrupting chemicals such as those found in cigarette smoke or Agent Orange. One cigarette may contain as much as 50 ng of benzopyrene, and this agent may well interfere with uterine and trophoblast cell proliferation and invasion, which may in turn predispose an individual to infertility and impaired placental vascular development. Dr C.V. Rao gave an impressive talk relating to a paradigm shift on the targets of hCG during pregnancy, not least because of his exotic slides of scenes from around the world. Superimposed on these slides was the important message that hCG may well have several important functions other than the traditional one allocated to it (that is maintaining the corpus luteum which is the primary source of progesterone during the first 9 weeks of pregnancy). As the site of progesterone synthesis shifts to the placenta during this period it was initially thought that hCG has no further role in pregnancy. However, there is increasing evidence from Dr Rao’s and other laboratories that hCG can regulate several different functions including immunological tolerance, neuroendocrine and behavioural changes, myometrial quiescence, increased uterine blood flow and numerous other changes throughout pregnancy. Dr Keiichi Isaka rounded off the day’s session with a talk on telomerase activity in human trophoblast. Although this enzyme was originally thought to be present only in cancer cells, studies using fluorescence-based telomeric repeat amplification protocols and RT-PCR techniques enabled this group to show telomerase activity in 43% of normal placental tissues, a value which decreased with gestational age. They concluded that telomerase activity may correlate with the regulation of trophoblastic cell proliferation. The next morning we were entertained by the two editors of Placenta. Professor Colin Sibley talked about the regulation of chloride and potassium transport by the human placenta, whilst Professor Leslie Myatt discussed how nitric oxide and other reactive oxygen species regulate the fetal–placental vascular resistance. Professor Sibley’s group used trophoblast cells in culture preloaded with radiolabelled chloride or rubidium to demonstrate the existence of acute hormonal regulation of chloride and potassium ions by the human placenta. Professor Myatt’s group showed that the long-lived powerful oxidant, peroxynitrite, which is formed by interaction of the superoxide and nitric oxide free radicals, may cause vascular dysfunction. Indeed his data showed that there was an overproduction of peroxynitrite in placentae from pre-eclamptic, intrauterine growth restricted and diabetic pregnancies which can cause endothelial dysfunction and vascular damage leading to altered vascular reactivity and blood flow characteristic of these conditions. Next Dr Anthony Carter eloquently reviewed the literature relating to the regulation of maternal placental circulation. He argued that any regulation which does occur must be at the level of the intramyometrial arteries. Although these arteries have been shown in vitro to be sensitive to several vasoactive

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agents (such as arginine vasopressin, angiotensin II, AVP, endothelin-1) care must be taken in interpreting their physiological importance. There is a general lack of research into the regulation of uteroplacental blood flow and he urged the audience to pursue this field more avidly in the future. Prior to the coffee break Professor Henning Schneider talked about oxygen consumption and the relative distribution of different oxidative pathways in human placental tissue. He proposed that although, in vivo, placental metabolism consumes up to 50% of the total uteroplacental oxygen supply, under conditions of insufficient oxygen supply such as those that occur in vitro, glycolysis and other oxidative reactions are suppressed, and the functional state of the tissue is maintain by anaerobic glycolysis. Dr Greg Rice opened the next session with a talk on the role of phospholipases in cell membrane polishing, a process whereby the outer epithelial layer is maintained in a quiescent, non-reactive state. He suggested that phospholipase A2, which is abundantly expressed in human gestational tissues from where it is secreted extracellularly, plays a significant role in several cell membrane-dependent events including terminal cellular differentiation and association with exogenous proteins and foreign cell membranes. Professor Joan Hunt then updated the audience on potential functions of the four currently known apoptosis-inducing TNF supergene family members, all of which are present in the human placenta. These are TNF-á, lyphotoxin-á (LT-á), Fas ligand (FasL) and TNF-related apoptosis-inducing ligand (TRAIL). Evidence suggests that FasL (which was also mentioned by Professor Kaufmann at the beginning of the meeting) protects the placenta from attack by activated maternal immune cells and restricts maternal–fetal trafficking. TNF-á has more wide-ranging powers in that it may facilitate placental remodelling as well as being involved with parturition (probably though activation of the transcription factor, NFêB). TRAIL may not only facilitate invasion but also allow placental remodelling and hormone synthesis. It appears that TRAIL and its receptor form a complex system involving additional decoy receptors. Apoptosis, also referred to as programmed cell death (PCD), is a fundamental process that occurs in all multicellular organisms and Dr Hyo-Pyo Lee argued that such a process also occurred in normal placentae. In order that PCD occurs in its proper physiological context, these deathmodulating parameters must be stringently regulated. In pathological conditions such as IUGR these control features are lost but the exact relationship between PCD and various abnormal pregnancy outcomes has yet to be investigated. Professor Richard Miller started the last session of the meeting with a discussion on the vertical transmission of HIV and other viruses to the fetus and examined the role that the placenta plays in this process. Studies from his group and others have shown that even after 12 h exposure to various types of viruses, the perfused human placental lobule allows minimal transfer to the fetus. In utero and in vitro investigations suggest that although the placenta may be itself infected with viral particles it may be a principal regulator of vertical HIV-1 transmission.

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Professor Gedes Grudzinskas won the hearts of the Japanese in the audience (and the admiration of everyone else) by taking the trouble to speak to the host participants in their own language for approximately 5 min at the beginning of his talk. This earned him a well-deserved round of applause before he launched himself into his talk concerning the screening for Down’s Syndrome in the first trimester of pregnancy from a European perspective. He suggested that there is now sufficient data to consider the introduction of screening for fetal aneuploidy between 11 and 14 weeks of pregnancy. Probably the most efficient method of screening is likely to be a combined strategy of biochemical (plasma levels of PAPP-A and beta-hCG) as well as ultrasound (nuchal translucency). Professor Kent Thornburg suggested that fetal water and nutrient acquisition by the placenta could regulate fetal heart growth in vivo. To support this theory he presented data from his laboratory showing that the syncytiotrophoblast and the fetal capillary endothelium express aquaporin-1 throughout gestation. Professor Robert Boyd reviewed the literature on the subject of the maternofetal potential difference (pd) over the past 40 years. Although much of the work has been done on animals, there are clear species and gestational differences in pd. He concluded that in humans the pdplac is not substantially different from the pdmf, and that these considerations cannot safely be ignored in analysis of fetal nutrition. Professor Shaun Brannecke (Royal Women’s Hospital, Carlton) focused on methods to diagnose preterm labour, which occurs in 7–8% of Australian births. He is embarking on a clinical trial using fetal fibronectin testing and hopes to report on this at a future IFPA meeting. Dr Miklós Török (Budapest, Hungary) then related some clinical experiences with a telemetric home monitoring system, used in prenatal care in his country with positive results. Dr Sun-Hee Chum ACKNOWLEDGEMENT I am grateful to the Little Foundation for financial support.

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confirmed the usefulness of measurements of umbilical venous erythropoietin, the number of nucleated erythrocytes and placental infarct at delivery as markers of fetal asphyxia. Dr Tsuyomu Ikenoue subsequently ended the scientific meeting by talking about the clinical significance of monochorial placentation in twin pregnancies. A total of 42 candidates were proposed for the New Investigators Award of which 30 were successful. The best poster presentation was judged to be that of Dr Atsushi Suzuki from Keio University and was entitled ‘Involvement of EAT, a BCL-2 related gene, in apoptotic mechanisms underlying human placental formation and maintenance’. He also presented his work in one of the Workshops. The poster presentations were of the usual high standards and presenters were expected to give a 5-min résumé of their work. The format of previous meetings was to have workshops every day. However, in this conference all the workshops took place on the last day and despite being well organized there was invariably some clashes of interest which meant that sometimes delegates would miss something of importance. Nevertheless, the format worked well overall. Professor Takayama closed the meeting by thanking all the participants, as well as his hard working staff, for all their efforts. The fourth IFPA meeting to be held in such an exotic location was long awaited and Tokyo lived up to its expectations with high-rise buildings, night lights and legendary Japanese hospitality. The conference banquet held on the 39th floor of the Park Hyatt Hotel was a grand and lavish affair. It was a perfect evening with delicious Japanese cuisine marked by meticulous details, such as the especially prepared labels bearing the conference logo on the bottles of red and white French wine. The only person missing from the meeting was the effervescent Professor Maurice Panigel, whom we hope to see in Schladming, Austria.