Biomedical subjects

M H F Sullivan

Publications and source records attributed to M H F Sullivan.

12 recordsLinked to original sources

PubMed2007

The effects of oxygen concentration on in vitro output of prostaglandin E2 and interleukin-6 from human fetal membranes.

Labour at all gestational ages has clear biochemical parallels with an inflammatory response, typified by the increased output of prostaglandins (PGs) and cytokines within the pregnant uterus. The main sources are the fetal membranes, including the amnion, chorion and decidua, and it is well established that stimuli [bacteria, bacterial endotoxins, interleukin (IL)-1beta, corticotrophin releasing hormone and platelet activating factor], as well as negative regulators (progesterone and IL-10), control the net output of PGs and cytokines in vitro. In this study, we have investigated the effect of oxygen tension on fetal membrane biology, as a reconsideration of the literature suggests that fetal membranes are normally exposed to approximately 3% O(2) (approximately 20 mmHg) in vivo, rather than the 20% O(2) (150 mmHg) used for in vitro culture. The output of prostaglandin E(2) from non-activated fetal membranes in response to IL-1beta was decreased by approximately 80% at 16 and 24 h of culture, whereas the inhibition of IL-6 production was time-dependent, reaching 90% after 16 h and 50% after 24 h. Tissues obtained after labour (or after the activation of inflammatory processes leading to labour) were not inhibited by the low levels of oxygen, indicating that only before the onset of labour does oxygen regulate fetal membrane biology. The data identify oxygen as a regulator of fetal membrane inflammatory functions during human pregnancy, and its mechanism of action requires further study.

Dinoprostone↗

PubMed2006

Placental ABCA1 expression is reduced in primary antiphospholipid syndrome compared to pre-eclampsia and controls.

The ATP binding cassette transporter A1 (ABCA1) mediates cellular cholesterol and phospholipid efflux, and is implicated in phosphatidylserine translocation and apoptosis. Loss of functional ABCA1 in null mice results in severe placental malformation. This study aimed to establish the placental localisation of ABCA1 and to investigate whether ABCA1 expression is altered in placentas from pregnancies complicated by pre-eclampsia and antiphospholipid syndrome. ABCA1 mRNA and protein localisation studies were carried out using in situ hybridization and immunohistochemistry. Comparisons of gene expression were performed using real-time PCR and immunoblotting. ABCA1 mRNA and protein was localised to the apical syncytium of placental villi and endothelia of fetal blood vessels within the villi. ABCA1 mRNA expression was reduced in placentas from women with APS when compared to controls (p<0.001), and this was paralleled by reductions in ABCA1 protein expression. There were no differences in ABCA1 expression between placentas from pre-eclamptic pregnancies and controls. The localisation of ABCA1 in human placenta is consistent with a role in cholesterol and phospholipid transport. The decrease in ABCA1 protein in APS may reflect reduced cholesterol transport to the fetus affecting the formation of cell membranes and decreasing the level of substrate available for steroidogenesis.

ATP Binding Cassette Transporter 1↗

PubMed2006

The links between maternal histamine levels and complications of human pregnancy.

Previous literature published since 1910 on maternal blood histamine levels and complications of pregnancy have been reviewed, showing links between hyper-histaminemia occurring in specific gestational complications including preeclampsia, spontaneous abortion, preterm labour and hyperemesis gravidarum. These complications may present with symptoms similar to those of experimentally induced high blood histamine or hyper-histaminemia in non-pregnant humans. Maternal levels of histamine in normal pregnancy decrease below values found in healthy non-pregnant women. However, in some complications of pregnancy, maternal blood histamine levels rise above those associated with normal pregnancy and may exceed normal non-pregnant circulating levels. These links between circulating maternal histamine levels and specific complications of human pregnancy suggest that further investigations to evaluate the outcome of managing maternal blood histamine levels during such complications may be warranted.

Animals↗

PubMed2005

Universal DNA primers amplify bacterial DNA from human fetal membranes and link Fusobacterium nucleatum with prolonged preterm membrane rupture.

A large number of bacterial species have been identified in fetal membranes after preterm labour (PTL) associated with intrauterine infection by microbiological culture. In this study, we have investigated a molecular and bioinformatic approach to organism identification which surmounts the need for specific and diverse microbiological culture conditions required by conventional methods. Samples of fetal membranes were taken from 37 preterm infants, and 6 normal term controls delivered by caesarean section, in which bacteria had been detected by in situ hybridization of 16S ribosomal RNA using a generic probe. Degenerate primers were designed to amplify bacterial 16S ribosomal DNA by PCR and used to amplify bacterial DNA from human fetal membranes. Amplicons were cloned, sequenced and bacteria were identified bioinformatically by comparison of sequences with known bacterial DNA genomes. In situ hybridization using an organism specific probe was then used to confirm the presence of the commonest identified organism in tissue samples. Bacterial DNA amplified from 15/43 samples, all from preterm deliveries, and the bioinformatic approach identified organisms in all cases. Multiple bacteria were identified including Mycoplasma hominis, Pasturella multocida, Pseudomonas PH1, Escherichia coli and Prevotella bivia. The commonest organism Fusobacterium nucleatum was found in 9/15 (60%) of samples. Ten of the 12 samples obtained after prolonged membrane rupture were positive for bacterial DNA, and 7 of these (70%) contained DNA from F. nucleatum. Bacteria from fetal membranes may be identified by molecular and bioinformatic methods. Further work is warranted to investigate the apparent linkage between F. nucleatum, fetal membrane rupture and preterm delivery.

Bacterial Typing Techniques↗

PubMed2004

Endocrine cell lines from the placenta.

Cell-lines derived from human placenta and chorion have been used extensively to model the endocrine functions of human trophoblast. In general terms, the endocrine functions of the primary cells and tissues are at least partially replicated within the cell-lines, suggesting that they may be used as appropriate models. There are, however, two major provisos that compromise this generalisation. Firstly, the endocrine function of placenta represents a complex interaction between cytotrophoblast, syncytiotrophoblast and multiple regulators, so a single cell population digested from the normal environment is unlikely to represent this. Secondly, the characterisation of primary trophoblast populations and of cell-lines is incomplete, complicating the assignment of functions to trophoblast populations. Despite these difficulties, useful information has been obtained from the available cell-lines, regardless of whether they have arisen spontaneously, been transformed in vitro, or derived from cancers in vivo.

Cell Line↗

PubMed2004

Maternal origin of inflammatory leukocytes in preterm fetal membranes, shown by fluorescence in situ hybridisation.

The aim of this study was to determine the maternal or fetal origin of inflammatory leukocytes in fetal membranes from cases of chorioamnionitis. Fetal membranes were collected from male preterm infants and chorioamnionitis was diagnosed histologically. Fluorescence in situ hybridisation for X and Y chromosomes was used to determine the gender of infiltrating leukocytes in the chorion and amnion. Leukocytes, trophoblast and mesenchymal cells were identified using immunohistochemistry for CD45, cytokeratin-7 and vimentin, respectively. Leukocytes present in the chorion and amnion were labelled XX, indicating maternal origin, and these cells were immunoreactive for the leukocyte marker CD45 but not for vimentin or cytokeratin-7. All other cells in the chorion and amnion were labelled XY and of fetal origin. The results indicated that maternal leukocytes invade the amnion and chorion in chorioamnionitis and we suggest that this is part of the maternal inflammatory response to intrauterine infection.

Adult↗

PubMed2004

The role of intrauterine bacteria in brain injury.

Organisms appear to be present in human fetal membranes without any apparent impact on pregnancy maintenance or the fetal brain. A clear link between chorioamnionitis and fetal brain damage suggests that tissue responses at the feto-maternal interface may be the key determinant of whether preterm labour and brain damage occur.

Bacterial Infections↗

PubMed2004

Regulation of human villous trophoblast by insulin-like growth factors and insulin-like growth factor-binding protein-1.

Many studies have implicated the insulin-like growth factors (IGFs) and insulin-like growth factor-binding protein-1 (IGFBP-1) in the control of the feto-maternal interface of human pregnancy, but many of the data are from cell lines derived from primary trophoblast or from extravillous trophoblast. We have obtained highly enriched villous cytotrophoblast (VCT) from first trimester and term human placentae, and investigated the effects of IGF-I, IGF-II and phosphoisoforms of IGFBP-1. First trimester villous trophoblast cells were regulated by all these factors. IGF-II increased cell numbers 3.5-fold after 96 h in culture, and IGF-I had less effect (1.5-fold increase) (both P<0.05). IGF-II also had a greater effect on the levels of matrix metalloproteinase (MMP)-2 and MMP-9. Phosphorylated and non-phosphorylated iso-forms of IGFBP-1 added alone increased cell numbers and MMP levels (P<0.05). IGFBP-1 did not modify the effects of IGF-II on cell numbers or on MMP production. Term VCT numbers and MMP production in vitro were unaffected by IGFs (P>0.05). Cell numbers were increased only by 100 nM IGFBP-1 isoforms (P<0.05), whereas MMP levels released from term cells were optimally increased by 1-10 nM IGFBP-1. Overall, our data show that IGFs regulate only first trimester, but not term, VCT. IGFBP-1 regulates VCT from both gestations, but the effects are concentration and end-point specific. In particular, first trimester cell numbers are more affected by low levels of IGFBP-1, whereas high levels of IGFBP-1 are needed to increase MMP and the converse applies to term VCT; low levels of IGFBP-1 have more effect on MMP levels.

Biomarkers↗

PubMed2003

The regulation of arachidonic acid metabolism in human first trimester trophoblast by cyclic AMP.

Human trophoblast cells are known to release a range of arachidonic acid metabolites into culture medium, including cyclo-oxygenase, lipoxygenase and epoxygenase products. In this study we investigated the effects of dibutyryl cyclic AMP (db cAMP) on arachidonic acid metabolism in human first trimester trophoblast cells, and also determined the distribution of metabolites between intracellular and extracellular compartments. db cAMP increased intracellular levels of radioactivity within 2 min, and extracellular levels of radioactivity were increased after 30 min. These changes were reflected in increased levels of arachidonic acid metabolites in both compartments, indicating that arachidonic acid was metabolised. db cAMP increased intracellular levels of 5,6-epoxyeicosatrienoic acid (5,6-EpETrE) within 2 min of addition to cultured cells. No changes were detected after 5-10 min, but substantial changes were found 30 min after the addition of db cAMP. The dihydroxyeicosatrienoic acid (DiHETrE) breakdown products also increased with similar kinetics. In contrast, levels of 14,15-EpETrE increased after 5-10 min.

8,11,14-Eicosatrienoic Acid↗

PubMed2002

The production of progesterone and 5,6-epoxyeicosatrienoic acid by human granulosa cells.

Previous investigations have implicated epoxygenase metabolites of arachidonic acid in the control of steroidogenesis in luteinised granulosa cells. The aim of this study was to assess this hypothesis further. We first determined the responsiveness of the cells in vitro to three different stimuli, namely luteinising hormone (LH), interleukin-1beta (IL-1beta), and dibutyryl cyclic AMP (db. cyclic AMP). Their effects were time-dependent, in that progesterone production from cells incubated for 3 days prior to stimulation responded strongly to db. cyclic AMP, to a lesser extent to LH and not to IL-1beta. After 6 days of preincubation, all three stimuli increased progesterone production, and this preincubation period was used in the remainder of the study.LH and IL-1beta increased the intracellular levels of 5,6-epoxyeicosatrienoic acid (5,6-EpETrE) maximally after 10 min, whereas db. cyclic AMP had a more rapid effect within 2-5 min. There were no changes in levels of 14,15-epoxyeicosatrienoic acid (14,15-EpETrE), indicating that the effect was specific. Levels of dihydroxy derivatives of arachidonic acid were also increased, suggesting rapid metabolism of 5,6-EpETrE to inactive 5,6-DiHETrE. The effects of 5,6-EpETrE on progesterone production were transient, which may be due to the lability of this compound in solution, and limited passage into the granulosa-luteal cell cytoplasm. These results support a role for 5,6-EpETrE in the production of progesterone by human granulosa-luteal cells.

8,11,14-Eicosatrienoic Acid↗

PubMed2002

Ultrastructure of the early human feto-maternal interface co-cultured in vitro.

BACKGROUND: The study was designed to investigate the ultrastructural features of the early human feto-maternal interface when generated by in-vitro co-culture, and compare these with findings reported previously from human pregnancies. METHODS: Placental villi and decidua parietalis tissues from 8-12 week pregnancies were co-cultured in vitro over a 4-day period. The co-incubations were ended at 24 h intervals and processed for electron microscopical studies, and for immunocytochemistry using anti-cytokeratin antibody (CAM 5.2) for trophoblast. RESULTS: Loss of the syncytium at points of contact with the decidual stroma, cytotrophoblast column formation, differentiation and invasion of extravillous trophoblast (EVT) cells into the decidual stroma over the 4-day period of co-culture were observed. Cellular components, such as actin filaments, microtubules, glycogen granules and lamellipodic processes found in EVT cells were consistent with active cellular locomotion. CONCLUSIONS: These ultrastructural studies emphasize the usefulness of this model in investigating the formation of the feto-maternal interface of human pregnancy. The recruitment of cytotrophoblast to the syncytium by a process involving fusion of the intervening plasma membranes, and the migration of EVT cells causing little or no damage to the surrounding decidual cells, resemble in-vivo data.

Cell Differentiation↗

PubMed2002

The effects of a cytokine suppressive anti-inflammatory drug on the output of prostaglandin E(2) and interleukin-1 beta from human fetal membranes.

Fetal membranes are a primary source of prostaglandins and pro-inflammatory cytokines implicated in human parturition, so the inhibition of inflammatory pathways may be of benefit in pregnancies complicated by premature labour. We have therefore investigated the effects of a cytokine-suppressant anti-inflammatory drug (CSAID) on the output of prostaglandin E(2) (PGE(2)) and interleukin (IL)-1 beta from human fetal membranes in vitro. Bacterial endotoxin increased the expression of mRNA for IL-1 beta and type-2 cyclo-oxygenase (COX-2), and there were corresponding increases in the output of IL-1 beta protein and PGE(2). The CSAID decreased IL-1 beta protein, COX-2 expression and PGE(2) output, but not mRNA for IL-1 beta, indicating a post-translational effect on the production of IL-1 beta and a transcriptional affect on COX-2, with an overall reduction in PGE(2). These findings are consistent with the effects of CSAIDs in other systems, and indicate that they are of possible use in premature labour.

Anti-Inflammatory Agents, Non-Steroidal↗