Cannabinoids stimulate prostaglandin production by human gestational tissues through a tissue- and CB1-receptor-specific mechanism.

Endocannabinoids have been implicated in the mechanisms of implantation, maintenance of pregnancy, and parturition in women. Intrauterine prostaglandin production and actions are also critical in each of these mechanisms. Hence, we have evaluated the effects of cannabinoids on prostaglandin biosynthesis by human gestational membranes. Explants of term amnion and choriodecidua were established and treated with the endogenous endocannabinoids 2-arachidonoyl glycerol and anandamide, as well as the synthetic cannabinoid CP55,940, to determine their ability to modulate PGE(2) production. The explants were also treated with CP55,940 in the presence of either SR141716A (a potent and selective antagonist of the cannabinoid receptor CB1) or NS398 [a cyclooxygenase (COX)-2 inhibitor] to determine whether any observed stimulation of PGE(2) production was mediated through the CB1-receptor and/or COX-2 activity. All three cannabinoids caused a significant increase in PGE(2) production in the amnion but not in the choriodecidua. However, separated fetal (chorion) explants responded to cannabinoid treatment in a similar manner to amnion, whereas maternal (decidual) explants did not. The enhanced PGE(2) production caused by CP55,940 was abrogated by cotreatment with either SR141716A or NS398, illustrating that the cannabinoid action on prostaglandin production in fetal membranes is mediated by CB1 agonism and COX-2. Data from Western blotting show that cannabinoid treatment results in the upregulation of COX-2 expression. This study demonstrates a potential role for endocannabinoids in the modulation of prostaglandin production in late human pregnancy, with potentially important implications for the timing and progression of term and preterm labor and membrane rupture.

Contact paracrine inhibitory networks within human gestational tissues.

We have determined the effects of separating chorion from decidua on the production of cytokines and prostaglandins. Chorionic production always exceeded that of decidua. Production rates were significantly greater in separated explants compared with intact choriodecidua, which suggests a potential contact paracrine inhibitory network.

Preferential production of prostaglandin D2 by lipopolysaccharide stimulated human choriodecidual explants.

It has been postulated that the progression of a pregnancy to term is, in part, the result of a relative maternal Th2 immunological state. Prostaglandins (PG) are critical mediators throughout pregnancy. Recent studies have demonstrated that one PG, PGD2, may be a mediator of a Th2 immunological state. To date, very little is known about the factors that regulate of PGD2 production by human gestational tissues. Placentae were collected from women undergoing Caesarean sections at term. Amnion was separated from the choriodecidua and choriodecidual explants established. Explants were allowed to equilibrate overnight in media containing 10% fetal calf serum. The following day, media were replaced with serum free media and then after an additional 24-h, media were collected and the wet weight of the tissues determined. Production rates of PGs were determined using radioimmunoassays. At all concentrations tested, LPS significantly enhanced PGD2 production by human choriodecidual explants compared to PGE2 and PGF2alpha production. Neutralization of TNF-alpha and IL-10 further increased the production of LPS stimulated PGD2 production. We suggest that a novel stimulatory pathway that drives the production of PGD2 has been uncovered.

Molecular inhibition of histone deacetylation results in major enhancement of the production of IL-1beta in response to LPS.

It has been postulated that the progression of human pregnancy to term is, in part, the result of a relative maternal Th(2) immunological state. This can be activated in some cell types by modifying DNA methylation and histone acetylation status. We demonstrate that the molecular inhibition of histone deacetylation, using trichostatin A (TSA), in human choriodecidual explants leads to a massive increase in lipopolysaccharide (LPS)-stimulated IL-1beta. The inhibition of histone deacetylation had no effect on LPS-stimulated TNF-alpha production or production of the other cytokines studied (IL-10, IL-1 receptor antagonist). The molecular inhibition of DNA methylation and histone deacetylation, using 5-aza-2'-deoxycytidine and TSA, respectively, in human choriodecidual explants also results in an increase in the basal production of TNF-alpha but not that of IL-1beta. The differential response is unique, and the relative uncoupling of IL-1beta and TNF-alpha responsiveness may have importance in other biological systems and provide new therapeutic targets for pathologies where upregulation of IL-1beta is known to be a causative factor.

Gestational age-dependent up-regulation of prostaglandin D synthase (PGDS) and production of PGDS-derived antiinflammatory prostaglandins in human placenta.

CONTEXT: The importance of prostaglandin (PG) signaling pathways to the maintenance of pregnancy and initiation of labor is well recognized. However, the complexity of these pathways and the mechanism(s) of their coordinated regulation in physiological and pathological conditions are only now being appreciated. OBJECTIVES: In this report we provide new evidence of a complete pathway for the biosynthesis and actions of PGD(2) and its metabolites within human gestational tissues. MATERIALS AND METHODS: Using immunohistochemistry and Northern and Western blotting, we demonstrate the dynamic regulation of H-type PGD synthase (PGDS) in placenta during gestation; in contrast, L-type PGDS and its PG products were detected in amniotic fluid, with increased amounts associated with labor. RESULTS: Placental tissues were shown to express both forms of the PGD(2) receptor identified to date, D prostanoid(1) (DP(1)) and DP(2)/chemotactic receptor on type 2 helper T cells, with a distribution consistent with the villous placenta being a major target, as well as source, of PGD(2). In vitro, placental PGD(2) production was shown to be stimulated upon inflammatory activation, whereas PGD(2) and its J series metabolites exerted potent inhibitory effects on placental cytokine production. CONCLUSIONS: These findings suggest that PGDS-derived prostanoids play important physiological roles in the placenta, such as immunoregulation and feto-placental communication, while potentially having a regulatory role in the processes of parturition.

Misidentification of prostamides as prostaglandins.

Prostaglandins and endogenous cannabinoid metabolites share the same lipid backbone with differing polar head groups at exactly the position through which a large molecule is attached to provide antigenicity and thus raise antisera. Hence, we hypothesized that antisera raised against prostaglandins linked to a large molecule such as BSA at the carboxyl functional group would also recognize endogenous cannabinoid metabolites and lead to highly misleading interpretations of data. We found major cross-reactivity of commercial antisera raised to prostaglandins with endocannabinoid metabolites. Furthermore, in a well-characterized cell line (WISH) or primary amnion tissue explants, endocannabinoid treatment led to increased production of endocannabinoid metabolites as opposed to primary prostaglandins. This was apparent only after separation of products by thin-layer chromatography, because they measured as prostaglandins by radioimmunoassay. These findings have major implications for our interpretation of data in situations in which these prostaglandin-like molecules are formed, and they stress the need for chromatographic or spectrometric confirmation of prostaglandin production detected by antibody-based methods.

Identification of 9alpha,11beta-prostaglandin F2 in human amniotic fluid and characterization of its production by human gestational tissues.

CONTEXT: 9alpha,11beta-Prostaglandin F(2) (9alpha,11beta-PGF(2)) can contract uterine smooth muscle with a potency equal to PGF(2alpha). Its presence in the human uterus and production by human gestational tissues is unknown. OBJECTIVE: These studies were performed to determine whether the PGD(2)-derived 9alpha,11beta-PGF(2) is both present in human amniotic fluid and synthesized by human gestational tissues and if so, whether labor-related substances could regulate its production. RESULTS: Detectable concentrations of 9alpha,11beta-PGF(2) were found in amniotic fluid samples and appeared to increase in late gestation. All gestational tissues studied synthesized 9alpha,11beta-PGF(2), with the placenta having the highest basal production rate, followed by the amnion and then the choriodecidua. IL-1beta and TNFalpha caused concentration-dependent increases in 9alpha,11beta-PGF(2) production in human amnion and choriodecidual explants. Moreover, treatment of choriodecidual and placental explants with lipopolysaccharide resulted in a significant increase in 9alpha,11beta-PGF(2) production rates, reaching a maximum of 13-fold in the choriodecidua. Studies examining the effects of the addition of exogenous PGD(2) strongly indicated that the choriodecidua has significant ability to convert PGD(2) to 9alpha,11beta-PGF(2), whereas the amnion has little. CONCLUSIONS: These results demonstrate for the first time that 9alpha,11beta-PGF(2) is present in human amniotic fluid and that it is produced by human gestational tissues and up-regulated by bacterial cell wall components and proinflammatory cytokines. We suggest that this prostaglandin may play a part in the mechanisms of human labor at term and preterm.

Differential effects of serum constituents on apoptosis induced by the cyclopentenone prostaglandin 15-deoxy-delta12,14-prostaglandin J2 in WISH epithelial cells.

Cyclopentenone prostaglandins, delta12-PGJ2 and 15d-PGJ2, have potent anti-tumour and anti-inflammatory activities, and have been shown to induce apoptosis in amnion-derived WISH cells. In this study, we have investigated the protective effects of serum and its constituents (growth factors and albumin) on delta12-PGJ2 and 15d-PGJ2-induced apoptosis in WISH cells. Serum (0.5% w/v) was protective against both delta12-PGJ2 and 15d-PGJ2-induced apoptosis. This was not due to the presence of serum-derived growth factors (EGF, IGF-1 and IGF-2), since they had no significant effect on 15d-PGJ2-induced cell death. In contrast, IGF-1 partially inhibited etoposide-induced apoptosis, confirming the presence of a functional IGF-1 receptor signalling system. Albumin was identified as the key survival factor in serum, since albumin and delipidated albumin exhibited the same level of protection from 15d-PGJ2-induced apoptosis as serum itself. The potential for serum albumin to regulate the bioactivity of cyclopentenone PGs may be of considerable importance in pathological conditions where roles for cyclopentenone PGs have been identified.

Macrophage inhibitory cytokine 1 in fetal membranes and amniotic fluid from pregnancies with and without preterm labour and premature rupture of membranes.

The placenta and fetal membranes are the site of expression of macrophage inhibitory cytokine (MIC-1), a member of the transforming growth factor (TGF)-beta superfamily. We hypothesized that MIC-1 may act as an immune regulator in pregnancy complications associated with intrauterine inflammation. Decidual cells, chorionic trophoblasts and amnion epithelial cells were identified by immunohistochemistry as the predominant MIC-1-containing cell type in term membranes. Amnion and choriodecidual explants all produced MIC-1 in culture, the latter having the greatest production rate (206 +/- 74.5 pg/mg tissue/24 h, n=6; mean +/- SEM). Production was not responsive to stimulation by pro-inflammatory cytokines. MIC-1 was detectable in 217 transabdominal amniotic fluid (AF) samples taken from 15 to 41 weeks gestation, concentrations ranging from 0.9-51.1 ng/ml. AF MIC-1 concentrations in pregnancies with premature rupture of membranes (PROM) or preterm labour, either with or without microbial invasion of the amniotic cavity, were not significantly different from those delivered at term either with or without labour. Treatment with MIC-1 (0.25-25 ng/ml) did not alter production of interleukin-6 or -8 by amnion or choriodecidual cells in vitro. We conclude that AF MIC-1 is derived from the fetal membranes and decidua, but that MIC-1 is unlikely to be involved in the pathophysiology of preterm birth or PROM.

Hypothermia suppresses inducible nitric oxide synthase and stimulates cyclooxygenase-2 in lipopolysaccharide stimulated BV-2 cells.

Hypothermia is neuroprotective, possibly through suppression of microglial activation. We investigated the effects of hypothermia on lipopolysaccharide (LPS) stimulated BV-2 cells. At 37 degrees C, LPS elicited strong increases in inducible nitric oxide synthase (iNOS), nitric oxide (NO), cyclooxygenase-2 (COX-2), tumour necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6), accompanied by translocation of nuclear factor-kappaB (NF-kappaB) to the nucleus. Hypothermia (33 degrees C) caused complete suppression of iNOS and NO, a partial reduction of IL-6 but did not prevent TNF-alpha production or NF-kappaB translocation. In contrast, LPS induced cyclooxygenase-2 (COX-2) to higher levels under hypothermic conditions. These results show that hypothermia selectively suppresses iNOS in microglia.

Critical paracrine interactions between TNF-alpha and IL-10 regulate lipopolysaccharide-stimulated human choriodecidual cytokine and prostaglandin E2 production.

Increased production of PGs by gestational membranes is believed to be a principal initiator of term and preterm labor. Intrauterine infection is associated with an inflammatory response in the choriodecidua characterized by elevated production of cytokines and PGs. The precise physiological significance of enhanced choriodecidual cytokine production in the mechanism of preterm labor remains uncertain. These studies were undertaken to dissect the roles and regulation of endogenous cytokines in regulating PG production by human choriodecidua. We used LPS treatment of human choriodecidual explants as our model system. In choriodecidual explant cultures, LPS (5 microg/ml) induced a rapid increase in TNF-alpha production, peaking at 4 h. In contrast, IL-10, IL-1beta, and PGE2 production rates peaked 8, 12, and 24 h, respectively, after LPS stimulation. Immunoneutralization studies indicated that TNF-alpha was a primary regulator of IL-1beta, IL-10, and PGE2 production, while IL-1beta stimulated only PGE2 production. Neutralization of endogenous IL-10 resulted in increased TNF-alpha and PGE2 production. IL-10 treatment markedly decreased TNF-alpha and IL-1beta production, but had no effect on PGE2 production. Taken together, these results demonstrate that the effects of LPS on choriodecidual cytokine and PG production are modulated by both positive and negative feedback loops. In the setting of an infection of the intrauterine, TNF-alpha may be a potential target for treatment intervention; IL-10 could be one such therapeutic.

Expression of angiogenic and neurotrophic factors in the human amnion and choriodecidua.

OBJECTIVE: Our objective was to identify the novel or differential expression of growth or development associated genes in the human gestational membranes that might play roles in pregnancy or in term or preterm parturition. STUDY DESIGN: Complementary DNA arrays were probed with [alpha(33)P]dCTP-labeled-complementary DNA that was prepared from the RNA of reflected amnion and choriodecidua that represent term not-in-labor, term spontaneous labor, and preterm labor with and without chorioamnionitis (n = 4 per group). Differential expression (term not-in-labor vs term spontaneous labor or preterm labor with chorioamnionitis vs preterm labor without chorioamnionitis) was evaluated by Wilcoxon tests. RESULTS: All 16 amnion samples expressed angiogenic factors (endothelin-2 and -3, vascular endothelial growth factor, and vascular endothelial growth factor-B) and neurotrophic factors (ephrin-A2, ephrin receptors-A2, -B1, -B3, -B4, and -B5, neuropilin-2, p75/nerve growth factor receptor and semaphorin-F). In both amnion and choriodecidua, the expression of vascular endothelial growth factor and the angiopoietin receptor, Tie-2, were greater with term spontaneous labor than with term not-in-labor (P <.05); increased VEGF receptor-2 (flk-1) expression was observed in term spontaneous labor choriodecidua (P <.05) but not amnion. Ephrin-A1 expression increased with term spontaneous labor in both tissues (P <.05). Semaphorin-F expression decreased with preterm labor with chorioamnionitis in choriodecidua (P <.05), although the trend was not significant in amnion (P =.1). CONCLUSION: Neurotrophic and angiogenic factor genes are expressed in amnion and choriodecidual membranes. Several of the genes exhibit differential expression with labor at term or in association with infection preterm, which suggests roles in or associated with these processes.

Regulation of prostaglandin production in an immortalized human myometrial cell line by cytokines and non-steroidal anti-inflammatory drugs.

OBJECTIVE: To test the effect of selective and non-selective inhibitors of prostaglandin H synthase-2 (PGHS-II) on basal and cytokine-stimulated prostaglandin (PG) production by the immortalized human myometrial cell line, UTLRp16. STUDY DESIGN: UTLRp16 cells were treated with interleukin (IL)-1beta (0.1, 1, 10ng/ml) and tumor necrosis factor (TNF)-alpha (1, 3, 10ng/ml) in the presence or absence of indomethacin, etodolac, 5,5-dimethyl-3-(3-fluorophenyl)-4-(4-methylsulphonyl) phenyl-2 (5H)-furanone (DFU) or nimesulide for 16h (1.6-1000nM). PG production was then measured by radioimmunoassay. RESULTS: IL-1beta and TNF-alpha both stimulated production of PGE(2) and 6-keto-PGF(1alpha) in a concentration-dependent manner. DFU showed the most PGHS-II selectivity with IL-beta-stimulated PG production, with a IC(50)(basal)/IC(50)(stimulated) ratio of 177.8, followed by nimesulide (122.5), etodolac (23.5) and indomethacin (2.7). DFU was not as selective in TNF-alpha stimulated cells (ratio 99.5). CONCLUSION: PGHS-II-selective inhibitors may be effective in the prevention of cytokine-driven myometrial PG production associated with preterm labor.