Coral larval settlement induction using tissue-associated and exuded coralline algae metabolites and the identification of putative chemical cues.

Reef-building crustose coralline algae (CCA) are known to facilitate the settlement and metamorphosis of scleractinian coral larvae. In recent decades, CCA coverage has fallen globally and degrading environmental conditions continue to reduce coral survivorship, spurring new restoration interventions to rebuild coral reef health. In this study, naturally produced chemical compounds (metabolites) were collected from two pantropical CCA genera to isolate and classify those that induce coral settlement. In experiments using four ecologically important Caribbean coral species, we demonstrate the applicability of extracted, CCA-derived metabolites to improve larval settlement success in coral breeding and restoration efforts. Tissue-associated CCA metabolites induced settlement of one coral species, Orbicella faveolata, while metabolites exuded by CCA (exometabolites) induced settlement of three species: Acropora palmata, Colpophyllia natans and Orbicella faveolata. In a follow-up experiment, CCA exometabolites fractionated and preserved using two different extraction resins induced the same level of larval settlement as the unfractionated positive control exometabolites. The fractionated CCA exometabolite pools were characterized using liquid chromatography tandem mass spectrometry, yielding 145 distinct molecular subnetworks that were statistically defined as CCA-derived and could be classified into 10 broad chemical classes. Identifying these compounds can reveal their natural prevalence in coral reef habitats and facilitate the development of new applications to enhance larval settlement and the survival of coral juveniles.

Deep connections: Divergence histories with gene flow in mesophotic Agaricia corals.

Largely understudied, mesophotic coral ecosystems lie below shallow reefs (at >30 m depth) and comprise ecologically distinct communities. Brooding reproductive modes appear to predominate among mesophotic-specialist corals and may limit genetic connectivity among populations. Using reduced representation genomic sequencing, we assessed spatial population genetic structure at 50 m depth in an ecologically important mesophotic-specialist species Agaricia grahamae, among locations in the Southern Caribbean. We also tested for hybridisation with the closely related (but depth-generalist) species Agaricia lamarcki, within their sympatric depth zone (50 m). In contrast to our expectations, no spatial genetic structure was detected between the reefs of Curaçao and Bonaire (~40 km apart) within A. grahamae. However, cryptic taxa were discovered within both taxonomic species, with those in A. lamarcki (incompletely) partitioned by depth and those in A. grahamae occurring sympatrically (at the same depth). Hybrid analyses and demographic modelling identified contemporary and historical gene flow among cryptic taxa, both within and between A. grahamae and A. lamarcki. These results (1) indicate that spatial connectivity and subsequent replenishment may be possible between islands of moderate geographic distances for A. grahamae, an ecologically important mesophotic species, (2) that cryptic taxa occur in the mesophotic zone and environmental selection along shallow to mesophotic depth gradients may drive divergence in depth-generalists such as A. lamarcki, and (3) highlight that gene flow links taxa within this relativity diverse Caribbean genus.

Historical changes (1905-present) in catch size and composition reflect altering fisheries practices on a small Caribbean island.

Effective assessments of the status of Caribbean fish communities require historical baselines to adequately understand how much fish communities have changed through time. To identify such changes and their causes, we compiled a historical overview using data collected at the beginning (1905-1908), middle (1958-1965) and end (1984-2016) of the 20th century, of the artisanal fishing practices and their effects on fish populations around Curaçao, a small island in the southern Caribbean. We documented historical trends in total catch, species composition, and catch sizes per fisher per month for different types of fisheries and related these to technological and environmental changes affecting the island's fisheries and fish communities. We found that since 1905, fishers targeted species increasingly farther from shore after species occurring closer to shore had become rare. This resulted in surprisingly similar catches in terms of weight, but not composition. Large predatory reef fishes living close to shore (e.g., large Epinephelid species) had virtually disappeared from catches around the mid-20th century, questioning the use of data from this period as baseline data for modern day fish assessments. Secondly, we compared fish landings to in-situ counts from 1969 to estimate the relative contributions of habitat destruction and overfishing to the changes in fish abundance around Curaçao. The decline in coral dominated reef communities corresponded to a concurrent decrease in the abundance and diversity of smaller reef fish species not targeted by fishers, suggesting habitat loss, in addition to fishing, caused the observed declines in reef fish abundance around Curaçao.

Costs and benefits of maternally inherited algal symbionts in coral larvae.

Many marine invertebrates provide their offspring with symbionts. Yet the consequences of maternally inherited symbionts on larval fitness remain largely unexplored. In the stony coral Favia fragum (Esper 1797), mothers produce larvae with highly variable amounts of endosymbiotic algae, and we examined the implications of this variation in symbiont density on the performance of F. fragum larvae under different environmental scenarios. High symbiont densities prolonged the period that larvae actively swam and searched for suitable settlement habitats. Thermal stress reduced survival and settlement success in F. fragum larvae, whereby larvae with high symbiont densities suffered more from non-lethal stress and were five times more likely to die compared with larvae with low symbiont densities. These results show that maternally inherited algal symbionts can be either beneficial or harmful to coral larvae depending on the environmental conditions at hand, and suggest that F. fragum mothers use a bet-hedging strategy to minimize risks associated with spatio-temporal variability in their offspring's environment.

Nitrogen and phosphorus uptake rates of different species from a coral reef community after a nutrient pulse.

Terrestrial runoff after heavy rainfall can increase nutrient concentrations in waters overlying coral reefs that otherwise experience low nutrient levels. Field measurements during a runoff event showed a sharp increase in nitrate (75-fold), phosphate (31-fold) and ammonium concentrations (3-fold) in waters overlying a fringing reef at the island of Curaçao (Southern Caribbean). To understand how benthic reef organisms make use of such nutrient pulses, we determined ammonium, nitrate and phosphate uptake rates for one abundant coral species, turf algae, six macroalgal and two benthic cyanobacterial species in a series of laboratory experiments. Nutrient uptake rates differed among benthic functional groups. The filamentous macroalga Cladophora spp., turf algae and the benthic cyanobacterium Lyngbya majuscula had the highest uptake rates per unit biomass, whereas the coral Madracis mirabilis had the lowest. Combining nutrient uptake rates with the standing biomass of each functional group on the reef, we estimated that the ammonium and phosphate delivered during runoff events is mostly taken up by turf algae and the two macroalgae Lobophora variegata and Dictyota pulchella. Our results support the often proposed, but rarely tested, assumption that turf algae and opportunistic macroalgae primarily benefit from episodic inputs of nutrients to coral reefs.

Deep down on a Caribbean reef: lower mesophotic depths harbor a specialized coral-endosymbiont community.

The composition, ecology and environmental conditions of mesophotic coral ecosystems near the lower limits of their bathymetric distributions remain poorly understood. Here we provide the first in-depth assessment of a lower mesophotic coral community (60-100 m) in the Southern Caribbean through visual submersible surveys, genotyping of coral host-endosymbiont assemblages, temperature monitoring and a growth experiment. The lower mesophotic zone harbored a specialized coral community consisting of predominantly Agaricia grahamae, Agaricia undata and a "deep-water" lineage of Madracis pharensis, with large colonies of these species observed close to their lower distribution limit of ~90 m depth. All three species associated with "deep-specialist" photosynthetic endosymbionts (Symbiodinium). Fragments of A. grahamae exhibited growth rates at 60 m similar to those observed for shallow Agaricia colonies (~2-3 cm yr(-1)), but showed bleaching and (partial) mortality when transplanted to 100 m. We propose that the strong reduction of temperature over depth (Δ5°C from 40 to 100 m depth) may play an important contributing role in determining lower depth limits of mesophotic coral communities in this region. Rather than a marginal extension of the reef slope, the lower mesophotic represents a specialized community, and as such warrants specific consideration from science and management.

Innate immune defences in the human uterus during pregnancy.

The prevention of uterine infection is critical to appropriate fetal development and term delivery. The innate immune system is one component of the uterine environment and has a role in prevention of uterine infection. Natural antimicrobials are innate immune molecules with anti-bacterial, anti-viral and anti-fungal activity. We discuss two groups of natural antimicrobials in relation to pregnancy: (i) the defensins; and (ii) the whey acidic protein motif containing proteins, secretory leukocyte protease inhibitor (SLPI) and elafin. Human beta-defensins (HBD) 1-3 are expressed by placental and chorion trophoblast, amnion epithelium and decidua in term and preterm pregnancy. Elafin shows a similar pattern of localisation while SLPI is produced only by amnion epithelium and decidua. Evidence suggests that there is aberrant production of some natural antimicrobials in pathologic conditions of pregnancy. In preterm premature rupture of membranes (PPROM) levels of SLPI and elafin are reduced in amniotic fluid and fetal membranes, respectively. Elafin and HBD3 increase in chorioamnionitis and levels of the alpha-defensins, HNP1-3, increase in maternal plasma and amniotic fluid in women affected by microbial invasion of the uterus. In vitro culture studies have suggested a mechanism for increased production of natural antimicrobials in chorioamnionitis. Elafin, SLPI, HBD2 and 3 are all upregulated by inflammatory molecules in cells derived from gestational tissues. In summary, production of natural antimicrobials at key sites within the pregnant uterus suggests an important role in prevention of uterine infection during pregnancy and labour. Aberrant production of these molecules in PPROM and chorioamnionitis suggests that they also have a role in pathologic conditions. In particular, upregulation of these molecules by inflammatory molecules present in chorioamnionitis will ensure a robust response to infection.

Expression of natural antimicrobials by human placenta and fetal membranes.

Preterm birth associated with infection is a major clinical problem. We hypothesized that this condition is associated with altered expression of natural antimicrobial molecules (beta-defensins (HBD), elafin). Therefore, we examined expression of these molecules and their regulation by proinflammatory cytokines in placentae and fetal membranes from term pregnancy. HBD1-3 and elafin were localized by immunohistochemistry in fetal membranes and placenta. Real-time quantitative PCR was used to examine mRNA expression in primary trophoblast cells treated with inflammatory molecules. HBD1-3 and elafin were immunolocalized to placental and chorion trophoblast layers of fetal membranes and placenta. Immunoreactivity was also observed in amnion epithelium and decidua. No differences were noted between samples from women who were not in labour compared to those in active labour. In in vitro cultures of primary trophoblast cells, HBD2 and elafin mRNA expression was upregulated by the proinflammatory cytokine, IL-1beta. These results suggest that the chorion and placental trophoblast layers may be key barriers to the progression of infection in the pregnant uterus. Natural antimicrobial expression may be altered in response to inflammatory mediator expression associated with the onset of labour and/or uterine infection, providing increased protection when the uterus may be particularly susceptible to infection.

Identification of eggshell membrane proteins and purification of ovotransferrin and beta-NAGase from hen egg white.

Exposure of selected Gram-positive and Gram-negative bacterial pathogens to egg shell membranes (ESM) significantly reduced their thermal resistance and/or inactivated cells. Although the components responsible for this antibacterial activity have not been conclusively identified, several proteins associated with the ESM activity have been identified including beta-N-acetylglucosaminidase, lysozyme and ovotransferrin, with each displaying varying degrees of antibacterial activity. Numerous attempts to purify active fractions of beta-N-acetylglucosaminidase, lysozyme and ovotransferrin from the ESM proved somewhat limited; however, hen egg white (HEW) beta-N-acetylglucosaminidase was purified using a two-step chromatographic procedure, isoelectric focusing followed by cation exchange chromatography. Pure fractions of ovotransferrin were also obtained in the process. SDS-PAGE electrophoresis and Matrix-Assisted Laser Desorption Time-of-Flight Mass Spectrometry were then used to partially characterize the individual protein components. Purified protein fractions such as these will be required in order to fully elucidate the mechanism responsible for the antimicrobial properties associated with the ESM.

Gastric epithelial anti-microbial peptides--histological correlation and influence of anatomical site and peptic ulcer disease.

BACKGROUND AND AIMS: Natural anti-microbial peptides are increasingly recognised for their protective effects in mucosal surfaces. We, therefore, aimed at investigating their expression in the human stomach in a range of peptic conditions. METHODS: We assessed the expression of epithelial secretory leukocyte protease inhibitor, human beta-defensins (HBD1 and HBD2), and alpha-defensin (HD5) in gastric biopsies taken from 52 patients, median age of 55 years. Expression of peptide mRNA was determined using real-time quantitative polymerase chain reaction. The activity of gastritis was graded on a 0-3 scale. RESULTS: The antrum had a median secretory leukocyte protease inhibitor of 0.93 and HBD1 of 0.42, compared with 0.13 (P = 0.001) and 0.08 units (P = 0.002) respectively in the gastric body. The antral histological scores correlated positively with HBD2 expression (r = 0.69; P< 0.001) and negatively with HBD1 (r = -0.47; P = 0.006) particularly in the absence of aspirin. Patients with Helicobacter pylori gastritis, gastric or duodenal ulcers had lower expression of HBD1 and greater expression of HBD2 than in controls. The intake of aspirin by patients infected with H. pylori was associated with marked rise in the expression of HD5 and less expression of secretory leukocyte protease inhibitor. CONCLUSIONS: Gastric epithelial anti-microbial peptides are influenced by anatomical site, grade of gastritis, peptic ulceration, and can be modulated by aspirin.

Urinalysis for interleukin-8 in the non-invasive diagnosis of acute and chronic inflammatory diseases.

BACKGROUND AND AIMS: Given its role in mediating inflammation, the use of urinary interleukin-8 (IL-8) was assessed in the non-invasive diagnosis of acute and chronic inflammatory diseases. METHODS: IL-8 was measured by an enzyme linked immunosorbent assay in random urine samples (1 ml each) carrying code numbers and taken from 208 patients: 177 adults and 31 children presenting with a range of active or inactive inflammatory conditions. RESULTS: In the appropriate controls and in patients with inactive inflammation, the median urinary IL-8 levels ranged from 7-12 pg/ml, compared with 104 pg/ml in active ulcerative colitis (p = 0.002), 54 in active Crohn's disease (p = 0.025), 93 in active rheumatoid arthritis (p = 0.001), 107 in acute cholecystitis (p<0.0001), 127 in acute appendicitis (p = 0.0001), and 548 pg/ml in urinary tract infection (p<0.0001). Children with non-viral inflammation/infection also had higher IL-8 values (median, 199 pg/ml; p = 0.0001) than those with viral infection (median, 7 pg/ml) or non-specific conditions (median, 10 pg/ml). In the study group as a whole urinary IL-8 values correlated positively with peripheral blood white cell count (r = 0.32; p < 0.001), erythrocyte sedimentation rate (r = 0.41; p<0.001), and C-reactive protein (r = 0.33; p<0.001). CONCLUSION: Taking the appropriate clinical situation into account, urinary IL-8 measurement helps in the non-invasive assessment of active inflammation in at least a number of common acute and chronic conditions.

Autocrine/paracrine regulation of apoptosis in epithelial cells by prostaglandin E2.

This study was designed to investigate the effect of IL-1alpha-induced up-regulation of cyclooxygenase-2 (COX-2) on prostaglandin E(2) (PGE(2)) secretion and the subsequent phenotypic effects of PGE(2) on epithelial cells. The effect of IL-1alpha on COX-2 expression was investigated in the T24 bladder epithelial cell line following treatment with 0, 0.05, 0.5, 1 or 10 ng/ml IL-1alpha for 1, 2, 4 or 6 h. Quantitative PCR confirmed up-regulation of expression of COX-2 with maximal expression observed following treatment with 0.5 ng/ml IL-1alpha for 1 h. Co-treatment of the cells with 0.5 ng/ml IL-1alpha in the presence or absence of 100 ng/ml IL-1 receptor antagonist (RA) abolished the up-regulation in COX-2 expression confirming that the effect of IL-1alpha is mediated via its membrane-bound receptors. Treatment with 0.5 ng/ml IL-1alpha resulted in a time-dependent increase in PGE(2) secretion with maximal secretion detected at 24 and 48 h after stimulation with IL-1alpha. Co-treatment of the cells with IL-1alpha and IL-1RA or the COX-2 enzyme inhibitor NS398 abolished the IL-1alpha mediated secretion of PGE(2). Treatment of T24 cells with 100 nM PGE(2) resulted in a significant elevation in cAMP generation confirming the expression of functional PGE(2) receptors. Finally, the effect of exogenous treatment with PGE(2) on apoptosis of T24 cells was assessed using cell death detection ELISA. T24 cells were treated with camptothecin to induce apoptosis in the presence or absence of 50 or 100 nM PGE(2) or 10 microM forskolin. Treatment of T24 cells with increasing doses of camptothecin alone resulted in a significant increase in the induction of apoptosis (P<0.01). However, co-treatment of the cells with 50 or 100 nM PGE(2) or 10 microM forskolin resulted in the inhibition of induction of the apoptotic pathway by camptothecin. These data demonstrate that PGE(2) inhibits apoptosis of epithelial cells possibly via cAMP-dependent pathway.

Administration of an antiprogesterone up-regulates estrogen receptors in the endometrium of women using Norplant: a pilot study.

OBJECTIVE: To determine the effect of a single dose of mifepristone (200 mg) on endometrial estrogen and progesterone receptors in Norplant users. DESIGN: A prospective single-blind placebo-controlled pilot study. SETTING; Women were recruited from a large family planning clinic and were studied either at the clinic or in a clinical research unit attached to a teaching hospital gynecology department. PATIENT(S): Eight women using Norplant and experiencing vaginal bleeding more often than once every 24 days. All completed the study. INTERVENTION(S): Endometrial biopsies were taken after treatment with both placebo and 200 mg of mifepristone, both given at the start of a bleeding episode. MAIN OUTCOME MEASURE(S): Expression of endometrial progesterone (PR) and estrogen (ER) receptors, ovulation, and vaginal bleeding. RESULT(S): Mifepristone administration was associated with down-regulation of PR receptor subtype B and up-regulation of ER. Women treated with mifepristone showed a tendency to increased ovulation rates and reduced vaginal bleeding. CONCLUSION(S): The effect of mifepristone on endometrial steroid receptors was consistent with functional inhibition of progesterone. The findings warrant further investigation of this regimen as a strategy to reduce frequent bleeding.

Regulation of prostaglandin availability in human fetal lung by differential localisation of prostaglandin H synthase-1 and prostaglandin dehydrogenase.

Specialisation of the respiratory portion of human fetal lung commences around 20-24 weeks gestation. In contrast, human fetal lung in vitro has the capacity to self-differentiate from 12 weeks gestation when grown in media devoid of growth factors or hormones, suggesting activation of autocrine or paracrine factors in vitro, or removal of the fetus from in utero inhibitory mechanisms. Prostaglandins play a key role during in vitro human fetal lung development and are synthesised by prostaglandin H synthase-1 (PGHS-1) and inactivated by 15-hydroxyprostaglandin dehydrogenase (PGDH) with formation of inactive 13,14-dihydro-15-keto-prostaglandins. We have used quantitative immunohistochemistry to determine expression and localisation of PGHS-1, PGDH, PGE2 and 13,14-dihydro-15-keto-PGE2 (PGEM) in human fetal lung with in situ hybridisation to localise PGHS-1 and PGDH mRNA. For the catabolic enzyme PGDH, amounts of mRNA, protein and enzyme product PGEM are increased within epithelium of distal as compared to more proximal airways. For PGHS-1, comparable amounts of mRNA, protein and enzyme product PGE2 are found in proximal and distal lung epithelium. Catabolism by PGDH is a sensitive mechanism for regulating bioavailability of prostaglandins and we propose that active catabolism of prostaglandins within human fetal lung epithelium is an inhibitory mechanism retarding epithelial differentiation in utero.

Fibroblast heterogeneity: existence of functionally distinct Thy 1(+) and Thy 1(-) human female reproductive tract fibroblasts.

Little is known about fibroblasts from the female reproductive tract, much less whether or not functional subsets exist. Fibroblasts are key as sentinel cells for recruiting white blood cells and for wound healing. The purpose of this research was to evaluate the possibility that functional subsets of fibroblasts exist in the human female reproductive tract. The strategy used was to define fibroblast subpopulations based on their surface expression of the Thy 1 antigen. In situ staining of human myometrium and endometrium showed heterogeneous staining for Thy 1. Freshly derived strains of fibroblasts from the myometrium and endometrium also demonstrated heterogeneous Thy 1 expression. For the first time, using magnetic beading and fluorescence-activated cell sorting, human myometrial fibroblasts were successfully separated into functionally unique Thy 1(+) and Thy 1(-) subsets. Both subsets produced the proinflammatory cytokines interleukin (IL)-6 and IL-8 after IL-1beta stimulation, but only the Thy 1(+) subset produced MCP-1. Furthermore, only Thy 1(+) fibroblasts up-regulated CD40 surface expression with IL-1beta or interferon-gamma treatment. Engagement of CD40 in the Thy 1(+) subpopulation induced IL-6, IL-8, and MCP-1. The discovery of functional subsets of reproductive tract fibroblasts now permits assessment of their roles in the normal functions of the reproductive tract and in disease states such as adhesions and menorrhagia.

Cd40 expression in uterine tissues: a key regulator of cytokine expression by fibroblasts.

CD40 is a cell surface receptor initially discovered on cells of the hemopoietic lineage. Its primary role on immune cells is to enhance their activation and hence their production of cytokines and immunomodulatory molecules. Recently, CD40 has also been detected on human fibroblasts. An emerging view of the fibroblast is that it is far more than a structural cell, being capable of intimate interaction with cells of the immune system. In fibroblasts from several tissues, the engagement of CD40 with its ligand (CD40L) resulted in the secretion of proinflammatory molecules such as interleukin-6 (IL-6) and IL-8. Currently, there are few data about the presence of the CD40-CD40L system in female reproductive tissues. This study investigates the expression of CD40 by human endometrium, myometrium, and cervix both in situ and in tissue explant-derived fibroblasts. CD40 was detected mainly in the perivascular region of endometrium, myometrium, and cervix. Light staining for CD40 was observed in stromal elements. Additionally, the basal epithelium of cervix expressed CD40. Fibroblastic cells derived from all three sources express low levels of CD40, and this is up-regulated with interferon-gamma treatment (500 U/mL; 72 h). When activated with interferon-gamma and CD40L, the fibroblasts secreted increased amounts of IL-6, IL-8, and MCP-1. These data suggest that the CD40-CD40L system may provide a link between the resident structural cells of these reproductive tissues and the infiltrating immune cells or activated platelets that may express CD40L. The possible interaction of CD40 with CD40L may be particularly important during events such as menstruation and cervical ripening, where up-regulation of the proinflammatory molecules IL-6 and IL-8 is viewed as critical for these processes. In addition, dysregulation of this system may be a contributory factor to problems such as menstrual dysfunction and preterm labor.

The NF-kappaB pathway in human endometrium and first trimester decidua.

Nuclear factor kappa B (NF-kappaB) regulates proinflammatory genes and may be involved in inflammation associated with reproductive events e.g. menstruation, implantation. Activation of NF-kappaB involves several protein kinases and subsequent degradation of an endogenous inhibitor, IkappaBalpha. This study details expression of NF-kappaB pathway intermediates in human endometrium and first trimester decidua. Messenger RNA was detected for IkappaBalpha, and IkappaB kinase gamma (IKKgamma, a scaffolding protein) and the protein kinases, IKKalpha, IKKbeta, NF-kappaB inducing kinase (NIK), mitogen-activated protein kinase Erk kinase kinase 1 (MEKK1) and TANK-binding kinase 1 (TBK1) using real-time quantitative polymerase chain reaction (PCR). IkappaBalpha and TBK1 mRNA were increased in the perimenstrual phase of the menstrual cycle. This suggests that there is activation of NF-kappaB due to premenstrual progesterone withdrawal, since NF-kappaB activity increases IkappaBalpha gene expression. Differential expression of NF-kappaB pathway intermediates occurred when progesterone concentrations increased in early pregnancy; IKKalpha and NIK mRNA levels increased in decidua whilst IKKbeta and MEKK1 mRNA levels declined. Expression profiles of IKKalpha and NIK proteins were determined immunohistochemically. Both were detected in glandular epithelium and endothelium of endometrium. In decidua, both were present in epithelium and decidualized stromal cells. The results of this study suggest that NF-kappaB is activated during menstruation. During early pregnancy, NF-kappaB may also be activated (via IKKalpha-NIK) and may regulate the expression of molecules vital for implantation and successful pregnancy. However, pro-inflammatory signalling to NF-kappaB (via IKKbeta-MEKK1) may be down-regulated in early pregnancy, contributing to the immunosuppressive mechanisms which prevail at this time.

Cytokine control in human endometrium.

Cytokines within endometrium participate in both menstruation and implantation but also contribute to the defence mechanisms of the mucosal epithelium. Endometrium is under the control of steroid hormones, particularly progesterone and, thus, control of cytokines by this steroid is important. Although appreciable numbers of progesterone receptors are not found in endometrial leucocytes, progesterone can modulate cytokines by acting on uterine cells expressing the receptor. The NFkappaB pathway is important in the control of cytokine synthesis and can modulate production of chemokines, matrix metalloproteinases and the inducible prostaglandin synthesis enzyme COX-2. NFkappaB activity can be inhibited by progesterone by either stimulating synthesis of IkappaB, the molecule that restrains NFkappaB in the cytosol, or after binding to the nuclear receptor, competing with NFkappaB for recognition sites on the relevant gene. In this way, progesterone can limit pro-inflammatory pathways. The major palliatives for endometrial dysfunctions such as menorrhagia and dysmenorrhoea have been the non-steroidal anti-inflammatory drugs that inhibit prostaglandin synthesis. Prostaglandins have major effects on cytokine production but the direct action of prostaglandin E on leucocytes is not a pro-inflammatory response but is to stimulate interleukin 10 and inhibit interleukin 12 synthesis. The likely effect of the non-steroidal anti-inflammatory drugs is on the cells surrounding the small blood vessels, where a synergistic action between prostaglandin and chemokine will induce leucocyte entry and activation leading to lysis of connective tissue and menstruation. At the time of implantation, tight control of cytokine synthesis is required. Although leukaemia inhibitory factor is essential to implantation, the mouse knockout models show that the prostaglandin system is also essential but that there are mutually supportive pathways that compensate for the knockout of many cytokines.

The endocrinology of menstruation--a role for the immune system.

The human endometrium displays characteristic features, both structural and functional, across the menstrual cycle. It is the sex steroid hormones, oestrogen and progesterone, that drive the endometrium through the different phases of the cycle. Oestrogen and progesterone act sequentially to regulate cellular concentrations of their respective receptors, this interaction initiates gene transcription. Thereafter a cascade of local events prepares the endometrium for implantation, but in the absence of pregnancy, progesterone withdrawal leads to menstruation and cyclic repair. Withdrawal of progesterone from an oestrogen-progesterone primed endometrium is the initiating event for the cascade of molecular and cellular interactions that result in menstruation. Progesterone withdrawal first affects cells with progesterone receptors. Early events in the menstrual process are vasoconstriction and cytokine up-regulation. The activation of lytic mechanisms is a later event and involves cells that may lack progesterone receptors, for example, uterine leucocytes and epithelial cells. Hence progesterone withdrawal results in a local increase of inflammatory mediators and the enzymes responsible for tissue breakdown. The total complex of local factors implicated in normal menstrual and aberrant menstrual bleeding are yet to be fully defined.

Increase in 15-hydroxyprostaglandin dehydrogenase activity in the ovine placentome at parturition and effect of oestrogen.

Type 1 NAD(+)-dependent 15-hydroxyprostaglandin dehydrogenase (PGDH) is the key enzyme for metabolism of active primary prostaglandins to inactive forms in gestational tissues. The present study examined the activity and immunolocalization of PGDH in the ovine placenta, fetal membranes and uterus over the latter half of pregnancy, and its potential regulation by oestradiol. Placenta, fetal membranes and myometrium were collected from sheep with known single insemination dates on days 70, 100 and 135 of gestation and in active labour demonstrated by electromyographic activity. In addition, chronically catheterized fetuses were infused with oestradiol (100 microgram kg(-1) per 24 h) (n = 5) or saline vehicle into the fetus from day 120 to day 125. PGDH activity measured in placental extracts remained constant from day 70 to day 135 of gestation, and then significantly (P < 0.05) increased by 300% in active labour. Immunoreactive PGDH was localized in the placentome at all stages and was present predominantly in the fetal component of the placentome in uninucleate, but not in binucleate, trophoblast cells. Similarly, in the fetal membranes PGDH immuno-reactivity was present in the uninucleate trophoblast but not in the binucleate cells of the chorion. PGDH immunostaining was also present in the endometrial luminal epithelium, in the smooth muscle of the myometrium, and the glandular epithelium of the cervix. Infusion of oestradiol into the fetal circulation from day 120 to day 125 of gestation had no effect on placental PGDH activity. Immunohistochemistry was used to localize oestrogen receptor alpha in intrauterine tissues to investigate further the failure of oestradiol to increase PGDH activity. Immunoreactive oestrogen receptor alpha was not present in the fetal component of the placenta, although it was expressed in adjacent maternal-derived cells. It is concluded that (1) PGDH activity increases in late gestation; (2) PGDH is expressed in uninucleate trophoblast cells in the ovine placenta and fetal membranes, and also in the maternal endometrial epithelium and stroma, myometrium and cervix; (3) oestrogen receptor alpha is not expressed in fetal cells in the placenta or fetal membranes; and (4) the increase in PGDH activity is not regulated by oestradiol administered to the fetus.