Role of Tumour Necrosis Factor ? in Stimulation of Prostaglandins F2?and E2Release by Cultured Porcine Endometrial Cells

Chemerin affects the cytokine production and the expression of their receptors in the porcine endometrium during early pregnancy and the estrous cycle: an in vitro study†

Interactions between female metabolic status, immune response, and reproductive system functioning are complex and not fully understood. We hypothesized that chemerin, considered a hormonal link between the above-mentioned processes, influences endometrial functions, particularly cytokine secretion and signaling. Using porcine endometrial explants collected during early pregnancy and the estrous cycle, we investigated chemerin effects on the secretion of interleukins (IL-1β, IL-6, and IL-8), leukemia inhibitory factor, tumor necrosis factor α, transforming growth factor α, and protein abundances of their respective receptors. Our results demonstrate chemerin modulation of cytokine secretion and receptor expression, with effects dependent on the stage of pregnancy and dose of chemerin. Furthermore, chemerin influences the phosphorylation of stress-activated protein kinase/Jun-amino-terminal kinase and nuclear factor kappa-light-chain-enhancer of activated B cells in the endometrium. Chemerin multifaceted actions, such as involvement in immune response, cell proliferation, and tissue remodeling, seem to be mediated by cytokines, at least in the endometrium. These findings underscore the potential crosstalk between chemerin and hormonal signaling pathways, providing insights into the complex mechanisms underlying early pregnancy establishment and maintenance.

Expression Profiles of Fatty Acid Transporters and the Role of n-3 and n-6 Polyunsaturated Fatty Acids in the Porcine Endometrium

Fatty acids (FAs) are important for cell membrane composition, eicosanoid synthesis, and metabolic processes. Membrane proteins that facilitate FA transport into cells include FA translocase (also known as CD36) and FA transporter proteins (encoded by SLC27A genes). The present study aimed to examine expression profiles of FA transporters in the endometrium of cyclic and early pregnant gilts on days 3 to 20 after estrus and the possible regulation by conceptus signals and polyunsaturated FAs (PUFAs). The effect of PUFAs on prostaglandin (PG) synthesis and transcript abundance of genes related to FA action and metabolism, angiogenesis, and immune response was also determined. Day after estrus and reproductive status of animals affected FA transporter expression, with greater levels of CD36, SLC27A1, and SLC27A4 observed in pregnant than in cyclic gilts. Conceptus-conditioned medium and/or estradiol-17β stimulated SLC27A1 and CD36 expression. Among PUFAs, linoleic acid decreased SLC27A1 and SLC27A6 mRNA expression, while arachidonic, docosahexaenoic, and eicosapentaenoic acids increased SLC27A4 transcript abundance. Moreover, arachidonic acid stimulated ACOX1, CPT1A, and IL1B expression and increased PGE2 and PGI2 secretion. In turn, α-linolenic acid up-regulated VEGFA, FGF2, FABP4, and PPARG mRNA expression. These results indicate the presence of an active transport of FAs in the porcine endometrium and the role of PUFAs as modulators of the uterine activity during conceptus implantation.

Impaired luteal progesterone synthesis observed in gilts with PMSG/hCG-induced estrus affects the expression of steroid, prostaglandin, and cytokine receptors in the endometrium and myometrium during the peri-implantation period

The present study aimed to examine the effect of impaired progesterone (P4) synthesis, observed in gilts with gonadotropin-induced estrus, on the uterine expression of receptors important for pregnancy establishment. Twenty prepubertal gilts received 750 IU PMSG and 500 IU hCG 72 h later, while 18 prepubertal gilts in the control group were observed daily for estrus behavior. Gilts were inseminated in their first estrus and slaughtered on days 10, 12, and 15 of pregnancy to collect endometrial and myometrial tissues for mRNA analysis using real-time PCR. As we previously described, gilts with PMSG/hCG-induced estrus showed decreased luteal P4 synthesis on days 10 and 12 of pregnancy. PMSG/hCG treatment did not affect P4 receptor mRNA expression in either uterine tissue. In the endometrium, a greater mRNA transcript abundance of estrogen receptors (ESR1 and ESR2), androgen receptor (AR), prostaglandin (PG) E2 receptors (PTGER2 and PTGER4), PGF2α receptor (PTGFR), interleukin 6 receptor (IL6R), and tumor necrosis factor α receptors (TNFRSF1A and TNFRSF1B) was detected in gilts with natural than with PMSG/hCG-induced estrus (P<0.05). In the myometrium, the mRNA expression of AR, PTGER2, and PTGFR was lower, while PGI2 receptor (PTGIR) transcript abundance was elevated in the gilts treated with PMSG/hCG as compared with the control animals (P<0.05). In summary, a decreased luteal P4 level during the peri-implantation period in gonadotropin-stimulated pigs affects endometrial and myometrial receptor expression, with the endometrium being more sensitive to impaired P4 synthesis. Whether the observed changes alter uterine receptivity to local and systemic factors remains to be elucidated.

PPARγ ligands modulate the immune response mediators in the pig myometrium - An in vitro study

The current study was conducted with the aim to investigate effects of PPARγ ligands on synthesis of nuclear receptor κB (NF-κB) and selected cytokines (IL-1β, IFNγ, TNFα, IL-4, IL-10, LIF) in the pig myometrium on days 14-15 of the estrous cycle (late-luteal phase) and days 14-15 of the gestational period (beginning of embryonic implantation). The myometrial slices were incubated in vitro for 6 h in medium containing PPARγ ligands, agonists: 15d-prostaglandin J₂ or pioglitazone, and antagonist - T0070907. The mRNA transcript and protein abundances were evaluated in tissues and culture medium. During the estrous cycle, PPARγ ligands did not have an effect on the mRNA transcript abundance of the immune response mediators used for treatments. The IL-10 protein abundance in the tissue was less when there was inclusions of pioglitazone in the medium, while the treatment with T0070907 resulted in a larger abundance of NF-κB, IL-1β (in the tissue) and IL-4 (in tissue and culture media). During the gestational period, pioglitazone or PGJ₂ suppressed mRNA IFNγ and IL-10 transcript and protein abundances (in the tissue and culture media), whereas there was an enhanced NF-κB protein abundance (in the tissue). Treatment with T0070907 had diverse effects (e.g., for NFκB inhibited mRNA transcript abundance or enhanced protein abundance). The observed changes are related mainly in tissues from pregnant animals. Responses to PPARγ antagonist are indicative of the possible involvement of PPARγ-independent factors as well as ligand-independent activation of the receptor, ligand selectivity/functionality or tissue receptivity to the factors evaluated.

Prostaglandin synthesis by the porcine corpus luteum: effect of tumor necrosis factor-α

The porcine corpus luteum (CL) displays delayed sensitivity to PGF-2α (luteolytic sensitivity, [LS]) until days 12 to 13 of cycle. The control of LS is unknown, but it is temporally associated with macrophage (which secrete tumor necrosis factor-α; TNF-α) infiltration into the CL. Other studies showed that TNF-α induces LS in vitro and that prostaglandins (PGs) may be involved in this mechanism. In experiment 1, PGF-2α and PGE secretion by luteal cells (LCs) was measured on days 4 to 14 of the estrous cycle, and the expression of PTGFS/AKR1B1 and PTGES/mPGES-1, determined by Western blot, before (day 7) vs after (day 13) the onset of LS. Results showed that the PGF-2α:PGE ratio increased significantly (P < 0.05) from day 4 to 13-14, and PTGFS/AKR1B1 and PTGES/mPGES-1 were significantly increased (P < 0.05) on day 13 (vs day 7). In experiment 2, LCs were collected from porcine CL at early (∼days 4-6) or mid (∼days 7-12) stages of the estrous cycle and cultured with 0, 0.1, 1, or 10 ng/mL TNF-α. Results showed that TNF-α significantly increased (P < 0.05) messenger RNA (mRNA) expression of cyclooxygenase (COX)-2 and mPGES-1 but not AKR1B1. TNF-α had no significant effects on AKR1B1 or mPGES protein abundance. TNF-α significantly increased (P < 0.05) PGE-2 but had no effect on PGF-2α secretion or on the PGF-2α:PGE2 ratio. In conclusion, although TNF-α increased COX2 and mPGES-1 mRNA, and PGE-2 secretion in vitro, it did not increase the PGF-2α:PGE2 ratio. Studies are currently directed toward exploring other pathways (eg, FP receptor signaling) by which TNF-α induces LS in the porcine CL.

LPS-challenged TNFα production, prostaglandin secretion, and TNFα/TNFRs expression in the endometrium of domestic cats in estrus or diestrus, and in cats with pyometra or receiving medroxyprogesterone acetate

Progesterone (P4) derivatives which are commonly used to block the cyclicity of domestic cats disturb the endocrine balance in the endometrium. The aims of this study were (i) to examine whether lipopolysaccharide (LPS) is responsible for enhancement of tumor necrosis factor-α (TNFα) secretion by the feline endometrial epithelial and stromal cells in vitro, (ii) to know whether immunolocalization of TNFα/TNFR1 and TNFR2 differs in cats at estrus or diestrus, receiving medroxyprogesterone acetate and suffering from pyometra, and (iii) to determine if TNFα-challenged prostaglandin secretion is stopped by prostaglandin synthases inhibitors. A total of 37 domestic adult cats in estrus or diestrus, receiving octane medroxyprogesterone or having clinical symptoms of pyometra, were enrolled in this study. The results obtained showed a distinct increase in LPS-challenged TNFα secretion in endometrial epithelial, but not stromal cells. TNFα augmented PG secretion was blocked by phospholipase A2 (PLA2) and cyclooxygeanase-2 (COX-2), but not by mitogen-activated protein kinase (MAPK) inhibitor. TNFα/TNFR1 and 2 protein expressions were limited mostly to the surface and glandular epithelium. TNFα/TNFRs protein was upregulated in the inflammatory uterus and hence may be involved in development of pathologic changes in the endometrial glands in cats receiving exogenous P4 as a hormonal contraceptive.

Tumor necrosis factor α up-regulates endometrial milk fat globule-epidermal growth factor 8 protein production via nuclear factor κB activation, resulting in cell migration of epithelial cells

OBJECTIVE

To explore the role of tumor necrosis factor (TNF) α, an early embryonic product, on endometrial epithelial cell migration and endometrial milk fat globule-epidermal growth factor 8 protein (MFG-E8) production.

DESIGN

In vitro study.

SETTING

Academic center.

INTERVENTION(S)

Ishikawa cells, used as surrogates for human epithelial cells, were treated with and without TNF-α.

MAIN OUTCOME MEASURE(S)

Effect of TNF-α on intracellular MFG-E8 protein was evaluated with the use of ELISA, Western blot, and subcellular fractionation. Specific inhibitors were used to study TNF-α mechanism of action. Effect of TNF-α on cell migration was studied with the use of a wound healing assay and reorganization of E-cadherin.

RESULT(S)

TNF-α induced: 1) significant up-regulation of MFG-E8 intracellular protein, which was attenuated by pretreatment with a specific inhibitor of nuclear factor κB; 2) increased transcription of MFG-E8 and other proinflammatory factors, such as interleukins 6 and 8, which were suppressed by cotreatment with hCG; and 3) significant cell migration with E-cadherin remodeling, changes associated with subcellular MFG-E8 relocalization.

CONCLUSION(S)

TNF-α up-regulates endometrial epithelial cell migration and MFG-E8 production, which are critical steps required for the endometrial changes during menstrual cycle as well as during embryonic attachment and invasion.

Effect of cytokines and ovarian steroids on equine endometrial function: an in vitro study

Regulation of immune–endocrine interactions in the equine endometrium is not fully understood. The aims of the present study were to: (1) investigate the presence of tumour necrosis factor alpha (TNF), interferon gamma (IFNG), Fas ligand (FASLG) and their receptors in the mare endometrium throughout the oestrous cycle; and (2) assess endometrial secretory function (prostaglandins), angiogenic activity and cell viability in response to TNF, oestradiol (E2), progesterone (P4) and oxytocin (OXT). Transcription of TNF and FASLG mRNA increased during the early and late luteal phase (LP), whereas IFNG mRNA increased in late LP. Transcription of the mRNA of both TNF receptors was highest in the mid-LP. All cytokines and receptors were expressed in surface and glandular epithelium, as well as in the stroma. Expression of TNF and its receptor TNFRSF1A increased during the follicular phase (FP) and mid-LP. IFNG was expressed in the mid-LP, whereas its receptor IFNR1 was expressed in the in mid- and late LP. The highest expression of FASLG and FAS occurred during the late LP. OXT increased the secretion of prostaglandin (PG) E2 and PGF2α in the FP and mid-LP. In the mid-LP, E2 and P4+E2 stimulated PGF2α secretion, whereas TNF and P4 increased cell viability. All treatments, with the exception of P4, increased nitric oxide and angiogenic activity in both phases. The coordinated action of cytokines and ovarian hormones may regulate secretory, angiogenic and proliferative functions in the equine endometrium.

Regulation of prostacyclin synthase expression and prostacyclin content in the pig endometrium

Prostaglandins (PGs) are critical regulators of a number of reproductive processes, including embryo development and implantation. In the present study, prostacyclin (PGI(2)) synthase (PGIS) mRNA and protein expression, as well as 6-keto PGF(1α) (a PGI(2) metabolite) concentration, were investigated in the pig uterus. Endometrial tissue and uterine luminal flushings were obtained on Days 4 to 18 of the estrous cycle and pregnancy. Additionally, conceptuses were collected and examined for PGIS mRNA expression and 6-keto PGF(1α) concentration. Regulation of PGI(2) synthesis in the porcine endometrium by steroids, conceptus products, and cytokines was studied in vitro and/or in vivo. Endometrial PGIS protein level increased on Days 12 and 16 in pregnant but not in cyclic gilts. Moreover, higher PGIS protein expression on Day 12 of pregnancy was accompanied by a greater content of 6-keto PGF(1α) in the endometrium. The concentration of 6-keto PGF(1α) in uterine luminal flushings increased substantially on Days 16 and 18 in pregnant gilts and was higher than in cyclic animals. Greater PGIS mRNA expression and PGI(2) metabolite concentration were detected in Day 12 and 14 conceptuses, respectively. Incubation of endometrial explants with conceptus-conditioned medium resulted in upregulation of PGIS protein expression and increased PGI(2) secretion. Moreover, PGIS mRNA and protein expression were upregulated in the endometrium collected from gravid uterine horn on Day 14 of pregnancy. In summary, PGIS is differentially expressed in the endometrium of cyclic and pregnant gilts resulting in higher PGI(2) synthesis in pregnant animals. Porcine conceptuses are important regulators of endometrial PGIS expression and PGI(2) release during the implantation period.

Mechanisms for the establishment of pregnancy in the pig

Establishment of pregnancy in pigs requires continuous function of corpora lutea and endometrial preparation for embryo implantation. Progesterone regulates expression of many proteins necessary for endometrial remodelling and embryo-maternal communications. Attaining the uterine receptivity involves progesterone priming and loss of progesterone receptors in the uterine epithelium before days 10-12 after oestrus. Spermatozoa and oocytes in oviduct alter secretion of specific proteins that exert beneficial effect on gametes and embryos. Moreover, an appropriate leucocyte activation and maintenance of delicate cytokine balance within the oviduct and uterus are important for early pregnancy. This early local immune response is rather mediated by seminal plasma components. These components also influence prostaglandin (PG) synthesis in the oviduct that is important for gamete and embryo transport. Pregnancy establishment requires the biphasic pattern of oestrogen secretion by conceptuses on days 11-12 and 15-30. Conceptus affects lipid signalling system consisting of prostaglandins and lysophosphatic acid. PG synthesis is changed by conceptus signals in favour of luteoprotective PGE(2) . Additionally, existence of PGE(2) positive feedback loop in the endometrium contributes to increased PGE(2) /PGF(2α) ratio during the peri-implantation period. PGE(2) through endometrial PGE(2) receptor (PTGER2) elevates the expression of enzymes involved in PGE(2) synthesis. Higher PGE(2) secretion in uterine lumen coincides with the elevated expression of HOXA10 transcription factor critical for implantation. A stable adhesion between conceptus and endometrium requires reduction in mucin-1 on the apical surface of epithelium and integrin activation by extracellular matrix proteins. Furthermore, growth factors, cytokines and its receptors are involved in embryo-maternal interactions.

Effect of conceptus secretions on HOXA10 and PTGS2 gene expression, and PGE2 release in co-cultured luminal epithelial and stromal cells of the porcine endometrium at the time of early implantation

Homeobox A10 (HOXA10) gene expression was demonstrated in the endometrium of adult porcine uteri, however there is little information concerning the role of this gene in the pig. Objectives of the present study were to examine: 1) the expression of HOXA10 in the endometrium of cyclic and early pregnant gilts; 2) the effect of estradiol (E(2)) and progesterone (P(4)) on HOXA10 expression in porcine luminal epithelial (LE) and stromal (ST) cells in vitro; 3) the effect of E(2) and conceptus-exposed medium (CEM) on HOXA10 and prostaglandin endoperoxide synthase (PTGS2) gene expression and prostaglandin (PG) E(2) secretion from LE and ST cells in a co-culture model. The abundance of HOXA10 mRNA was increased on day 15 of pregnancy in comparison to day 15 of the estrous cycle. Moreover, increased HOXA10 mRNA level was detected in ST cells after E(2) and P(4) treatment. E(2) stimulated the expression of HOXA10 in LE cells cultured on collagen and pre-treated with steroids, but not in LE on plastic surfaces. Addition of CEM to LE cells cultured in collagen-coated inserts of the co-culture system resulted in elevated HOXA10 and PTGS2 gene expression and PGE(2) secretion in these cells, but not in ST cells cultured in basal compartments. ST cells directly treated with E(2) or CEM showed higher levels of HOXA10 and PTGS2 expression. Blocking of estrogen receptors with ICI-182,780 did not influence the stimulatory effect of CEM. We conclude that HOXA10 expression in the porcine endometrium is closely related to the implantation process and stimulated by conceptus products. Moreover, the co-culture system of LE and ST cells is a promising model for the study of endometrial response to conceptus-derived factors.

The effect of boar seminal plasma on the release of prostaglandins and interleukin-6 by porcine endometrial and cervical cells and bovine endometrial cells

Artificial insemination (AI) of sows results in a significant elevation of prostaglandin F(2α) metabolite (PGFM) levels in peripheral plasma, whereas in mated sows such elevation is not seen. The aim of this study was to investigate whether boar seminal plasma (SP) has any effect on the release of PGFM, prostaglandin F(2α) (PGF(2α) ), prostaglandin E(2) (PGE(2) ) or interleukin-6 (IL-6) by in vitro cultured porcine endometrial (epithelial - pUE and stromal - pUS), cervical (pCE and pCS) and bovine endometrial epithelial cells (bUE). This study shows that boar SP inhibits the release of PGFM, PGF(2α) and PGE(2) by porcine endometrial and cervical cells and bovine endometrial cells after 3 and 24 h incubation. Boar SP stimulated IL-6 release by pUE, pUS and even bUE after 3 h incubation. Tumour necrosis factor α (TNFα) stimulated the release of IL-6 by pUS only after 24 h incubation, but in the presence of boar SP, this stimulation was attenuated. The overall results from these in vitro studies give us possibility to understand the difference in prostaglandin response between mated and inseminated sows. Furthermore, we demonstrated that frozen-stored epithelial and stromal cells from pig endometrium, as well as from the cervix are suitable for studying the effect of SP on the release of prostaglandins. The only prerequisite is to incubate these thawed cells with arachidonic acid as a source for the synthesis of prostaglandins. A similar effect of boar SP on porcine and bUE cells may suggest inter-species reactivity.

Oxytocin and tumor necrosis factor alpha stimulate expression of prostaglandin E2 synthase and secretion of prostaglandin E2 by luminal epithelial cells of the porcine endometrium during early pregnancy

Oxytocin (OXT) and tumor necrosis factor α (TNF) have been implicated in the control of luteolysis by stimulating endometrial secretion of luteolytic prostaglandin F(2α) (PGF(2α)). Nevertheless, OXT concentration in porcine uterine lumen increases markedly on days 11-12 of pregnancy, and TNF is expressed in endometrium during pregnancy. The objective of the study was to determine the effect of OXT and TNF on expression of the enzymes involved in PG synthesis: PG-endoperoxide synthase 2 (PTGS2), PGE(2) synthase (mPGES-1) and PGF synthase, and PGE(2) receptor (PTGER2), as well as on PG secretion by endometrial luminal epithelial cells (LECs) on days 11-12 of the estrous cycle and pregnancy. LECs isolated from gilts on days 11-12 of the estrous cycle (n=8) and pregnancy (n=7) were treated with OXT (100  nmol/l) and TNF (0.6  nmol/l) for 24  h. OXT increased PTGS2 mRNA and mPGES-1 protein contents, as well as PGE(2) secretion but only on days 11-12 of pregnancy. TNF stimulated PTGS2 and mPGES-1 mRNA, as well as mPGES-1 protein expression and PGE(2) release on days 11-12 of pregnancy and the estrous cycle. In addition, expressions of PTGER2 and PTGER4 were determined in corpus luteum (CL). Abundance of PTGER2 mRNA and PTGER4 protein in CL was upregulated on day 14 of pregnancy versus day 14 of the estrous cycle. This study indicates that TNF and OXT regulate PGE(2) synthesis in LECs during early pregnancy. PGE(2) secreted by LECs, after reaching ovaries, could have a luteoprotective effect through luteal PTGER2 and PTGER4, or may directly promote uterine function and conceptus development.

Effect of estrus induction on prostaglandin content and prostaglandin synthesis enzyme expression in the uterus of early pregnant pigs

Prostaglandins (PGs) play a pivotal role in maternal recognition of pregnancy and implantation in pigs. In the present study, PGE(2), PGF(2alpha), and PGFM (PGF(2alpha) metabolite) content, as well as PGE(2) synthase (mPGES-1) and PGF(2alpha) synthase (PGFS) expression was investigated in early pregnant gilts with natural (n=21) and PMSG/hCG-stimulated (n=19) estrus. Endometrial tissue samples, uterine luminal flushings (ULFs), and blood serum were collected on days 10-11, 12, and 15 after insemination. Additionally, day 15 conceptuses were collected for mPGES-1 and PGFS protein expression. Effect of estrus induction was observed on day 15 of pregnancy, when the content of PGE(2) in the uterine lumen was fourfold lower in gonadotropin-stimulated gilts in comparison to controls (P<0.001). Decreased PGE(2) content in ULFs of gonadotropin-treated pigs was preceded by lower endometrial mPGES-1 gene expression in hormonally-stimulated animals in comparison to control gilts (P<0.01). On the other hand, estrus induction with PMSG/hCG resulted in higher PGE(2) accumulation in the endometrial tissue on day 15 of pregnancy (P<0.01). Furthermore, PGF(2alpha) content in the endometrium and PGFM levels in blood serum were lower in gonadotropin-treated gilts, especially on day 12 after insemination when compared to control gilts (P<0.01). Finally, PGFS expression in day 15 conceptuses was decreased in animals with hormonally-induced estrus. We conclude that PMSG/hCG stimulation of prepubertal gilts to induce estrus results in changes of PG production and secretion during early pregnancy, which, in turn, may affect conceptus development, implantation, and the course of pregnancy.

Tumor necrosis factor-alpha as a possible auto-/paracrine factor affecting estrous cycle in the cat uterus

Tumor Necrosis Factor-alpha (TNFalpha) is a pleiotrophic cytokine, affects either normal or tumor cells, and influences cellular differentiation. TNFalpha role in female reproduction has been proven to be mediated through an influence on prostaglandin (PGs) synthesis and output. To evaluate the possible role of TNFalpha in an auto-/paracrine regulation in the cat uterus, mRNA expression coding for TNFalpha and its receptors (TNFR1 and TNFR2), and TNFalpha protein content at different stages of the estrous cycle were investigated. Additionally, TNFalpha involvement in PG secretion at different stages of the estrous cycle was investigated by in vitro tissue culture. Gene expressions coding for TNFalpha and TNFR1 were the highest at diestrus (P < 0.05). TNFalpha protein expression was the lowest at interestrus (P < 0.05). Nevertheless, TNFR2 was not affected by the estrous stage. TNFalpha at a dose of 1 ng/ml significantly increased PGF2alpha secretion at estrus (P < 0.01) and PGE2 secretion at diestrus (P < 0.001) after 12h incubation. Overall findings indicate that TNFalpha locally produced in the cat's uterus, stimulates PG secretion in an estrous cycle-related manner.

Effects of tumor necrosis factor-alpha on cell proliferation, prostaglandins and matrix-metalloproteinases production in rat endometrial stromal cells cultured in vitro

Tumor necrosis factor-alpha (TNF-alpha) is known as a pluripotent cell mediator, and it is implicated in the control of uterine cell growth, differentiation and function during estrous cycle and pregnancy. In this study, we investigated the effect of TNF-alpha on endometrial stromal cells derived from rat uterus (rat endometrial stromal cells, RES). RES were isolated from rat endometrium at day 5 of pregnancy. Proliferation activities of RES were measured by using bromodeoxyuridine (BrdU) labeling kit, the productions of prostaglandin E2 (PGE2) and prostaglandin F2alpha (PGF2alpha) were measured by enzyme immunoassay kits and the production of matrix metalloproteinases (MMPs) was analyzed by gelatin-zymography. TNF-alpha, as well as epidermal growth factor and fibroblast growth factor-2, significantly increased the proliferation activity of RES (P<0.05). TNF-alpha selectively stimulated the production of PGE2 in RES (P<0.05), but not the production of PGF2alpha. Additionally, TNF-alpha did not stimulate the production of MMPs in RES at the concentration of 5 ng/mL, compared with the control groups (P>0.05). In conclusion, this study demonstrates several regulational functions of TNF-alpha on RES using in vitro culture system. The effects of TNF-alpha on proliferation and MMP production of RES have been shown for the first time. We believe that these results demonstrate part of the functions of TNF-alpha in endometrium and contribute to the better understanding of endometrial functions.

Actions of a nitric oxide donor on prostaglandin production and angiogenic activity in the equine endometrium

Nitric oxide (NO) plays an important role in prostaglandin secretion and angiogenesis in the reproductive system. In the present study, the roles of the NO donor spermine NONOate and tumour necrosis factor-α (TNF; as a positive control) in prostaglandin production and angiogenic activity of equine endometria during the oestrous cycle were evaluated. In addition, the correlation between NO production and the expression of key prostaglandin synthase proteins was determined. The protein expression of prostaglandin F synthase (PGFS) increased in early and mid-luteal stages, whereas that of prostaglandin E synthase (PGES) was increased in the early luteal stage. The in vitro release of NO was highest after ovulation. There was a high correlation between NO production and PGES expression, as well as NO release and PGFS expression. There were no differences detected in prostaglandin H synthase 2 (PTGS-2) throughout the oestrous cycle and there was no correlation between PTGS-2 expression and NO. In TNF- or spermine-treated endometria, the expression of prostaglandin (PG) E2 increased in the early and mid-luteal phases, whereas that of PGF2α increased in the follicular and late luteal phases. Bovine aortic endothelial cell (BAEC) proliferation was stimulated in TNF-treated follicular-phase endometria. However, in spermine-treated endometria, NO delivered from its donor had no effect, or even an inhibitory effect, on BAEC proliferation. In conclusion, despite no change in PTGS-2 expression throughout the oestrous cycle in equine endometrial tissue, there were changes observed in the expression of PGES and PGFS, as well as in the production of PGE2 and PGF2α. In the mare, NO is involved in the secretory function of the endometrium, modulating PGE2 and PGF2α production. Even though TNF caused an increase in the production of angiogenic factors and prostaglandins, its complex action in mare uterus should be elucidated.