PGE2 Treatment Research Articles

Production of PGE2 increases in tendons subjected to repetitive mechanical loading and induces differentiation of tendon stem cells into non‐tenocytes

Whether tendon inflammation is involved in the development of tendinopathy or degenerative changes of the tendon remains a matter of debate. We explored this question by performing animal and cell culture experiments to determine the production and effects of PGE(2), a major inflammatory mediator in tendons. Mouse tendons were subjected to repetitive mechanical loading via treadmill running, and the effect of PGE(2) on proliferation and differentiation of tendon stem cells (TSCs) was assessed in vitro. Compared to levels in cage control mice, PGE(2) levels in mouse patellar and Achilles tendons were markedly increased in response to a bout of rigorous treadmill running. PGE(2) treatment of TSCs in culture decreased cell proliferation and induced both adipogenesis and osteogenesis of TSCs, as evidenced by accumulation of lipid droplets and calcium deposits, respectively. Effects of PGE(2) on both TSC proliferation and differentiation were apparently PGE(2)-dose-dependent. These findings suggest that high levels of PGE(2), which are present in tendons subjected to repetitive mechanical loading conditions in vivo as shown in this study, may result in degenerative changes of the tendon by decreasing proliferation of TSCs in tendons and also inducing differentiation of TSCs into adipocytes and osteocytes. The consequences of this PGE(2) effect on TSCs is the reduction of the pool of tenocytes for repair of tendons injured by mechanical loading, and production of fatty and calcified tissues within the tendon, often seen at the later stages of tendinopathy.

Downregulation of cyclooxygenase-1 is involved in gastric mucosal apoptosis via death signaling in portal hypertensive rats

Portal hypertension (PHT) gastropathy is a frequent complication of liver cirrhosis and one of the leading causes of death from cirrhosis. Apoptosis is widely considered to be an active energy-dependent mode of cell death and a distinct entity from necrotic cell death. It is unclear whether gastric mucosal apoptosis is involved in PHT gastropathy. Prostaglandins (PGs) produced through cyclooxygenase (COX) are thought to play a key role in protection of the gastrointestinal mucosa from injury and apoptosis. However, the role of COX in PHT gastropathy is still not clearly understood. The aims of this study were to investigate whether (1) gastric mucosal apoptosis is involved in PHT gastropathy and (2) downregulation of COX contributes to this apoptosis. In this study, we show that gastric mucosal apoptosis was remarkably increased while mucosal proliferation was inhibited in PHT rats. Gastric mucosal COX-1 was significantly suppressed at both the mRNA and protein levels, and PGE(2) was reduced in PHT rats. Further, PGE(2) treatment suppressed gastric mucosal apoptosis in PHT rats. However, gastric mucosal COX-2 levels did not differ between sham-operated rats and PHT rats. Gastric mucosal levels of tumor necrosis factor-alpha (TNF-alpha) and Fas ligand, but not TNF-related apoptosis-inducing ligand, were increased, and activated caspase-8 and caspase-3 levels were upregulated in PHT rats. The release of cytochrome c from the mitochondria to the cytosol was not observed in PHT rats. Our data indicate that downregulation of COX-1 is involved in gastric mucosal apoptosis via death signaling-mediated type-I cell death in PHT rats.

Effect of IL-1B, PGE2 and TGF-B1 treatments on OPG and RANKL gene expression and protein synthesis in osteoporotic and normal HOB

Effect of IL-1B, PGE2 and TGF-B1 treatments on OPG and RANKL gene expression and protein synthesis in osteoporotic and normal HOB

Effect of Prostaglandins A-1, E-2 and F-2a on Blood Plasma Levels of Testosterone, LH and FSH in Male Rats

Effects of the administration of PGs A-1, E-2 and F-2 alpha (150 micrograms/rat b.i.d. for 10 days) were studied. Significant increase in testicular weight was observed only in PGE-2 treated group. Testicular ascorbic acid content reduced significantly by treatment with all the PGs. PGE-2 treatment caused a significant decrease in the content of testicular cholesterol, while no change was observed in the same and prostatic acid phosphatase activity in any of the PG treated groups. Blood plasma levels of testosterone drastically reduced by both PGE-2 and PGF-2 alpha, while there was no change in the levels of plasma LH in any of the groups. Plasma FSH levels increased significantly in PGA-1 treated rats only. The results suggest that 1) There is a direct action of PG particularly PGE-2 on testicular weight. PGE-2 increases testicular weight possibly by preventing degeneration of spermatids, 2) PGE-2 acting directly on the testis, reduces testicular ascorbic acid content, stimulates the conversion of cholesterol to pregnenolone but depresses the conversion of the latter to testosterone.

The concentrations of visfatin in the follicular fluids of women undergoing controlled ovarian stimulation are correlated to the number of oocytes retrieved

To compare the concentrations of visfatin in the plasma with those in follicular fluid of women undergoing controlled ovarian stimulation and to discover their correlation to the number of oocytes retrieved. Further, to examine whether FSH or hCG affects the expression of visfatin and whether visfatin affects COX-2 expression in cultured granulosa luteal (GL) cells. A clinical and in vitro study. University hospital. Women subjected to IVF procedures were enrolled in the study. Plasma and follicular fluid visfatin levels were analyzed using ELISA. HCG, FSH, PGE2 and visfatin were added to cultured GL cells. Enzyme immunoassay and RT-PCR were performed. There was no correlation between follicular fluid and plasma visfatin levels (r = 0.443). The number of oocytes retrieved was significantly correlated to follicular visfatin levels in multiple linear regression analysis (r = 0.891, r(2) = 0.794). In vitro experiments on GL cells revealed that hCG and PGE(2) considerably increased visfatin mRNA expression. FSH did not affect visfatin mRNA expression. Treatment with visfatin caused an induction of COX-2 mRNA. The follicular fluid visfatin concentrations are correlated to the number of oocytes retrieved. Human GL cells produce visfatin, and visfatin synthesis is increased by hCG and PGE2 treatment. Visfatin can induce expression of COX-2 mRNA in GL cells.

Cyclic Adenosine 3′,5′-Monophosphate Response Element-Binding Protein and CCAAT/Enhancer-Binding Protein Mediate Prostaglandin E 2-Induced Steroidogenic Acute Regulatory Protein Expression in Endometriotic Stromal Cells

Aberrant expression of the steroidogenic acute regulatory (StAR) protein in human endometriotic stromal cells plays an important role in the development of endometriosis. Prostaglandin E(2) (PGE(2)) is a potent inducer of StAR expression in these cells; however, the mechanisms responsible for the transcriptional regulation of StAR remain to be elucidated. Herein we report that PGE(2)-induced StAR expression is independent of the transcriptional suppressor DAX-1 but is regulated by the transcriptional activator cyclic adenosine 3',5'-monophosphate (cAMP) response element-binding protein (CREB). A promoter activity assay revealed that the cis-element needed for the binding of the CCAAT/enhancer-binding protein (C/EBP) was critical for PGE(2)-induced StAR expression. Electrophoretic mobility shift assay demonstrated that this region of the StAR promoter was bound by C/EBPalpha, C/EBPbeta, and CREB. Forced expression of either C/EBPalpha or C/EBPbeta alone was sufficient to up-regulate StAR promoter activity whereas PGE(2) was needed to induce StAR promoter activity in CREB-overexpressed cells. Results from a chromatin immunoprecipitation assay demonstrated that the binding of C/EBPbeta to the StAR promoter was increased whereas CREB binding was unchanged after PGE(2) treatment. Taken together, PGE(2)-induced StAR promoter activity appears to be regulated by CREB and C/EBPbeta in a cooperative manner in ectopic human endometriotic stromal cells, providing a molecular framework for the etiology of endometriosis.

Genome-Wide Expression Analysis of Human Endometrial Stromal Cells Following In Vitro Decidualization with IL1β, PGE2, PGD2, or Butaprost Treatment.

Genome-Wide Expression Analysis of Human Endometrial Stromal Cells Following In Vitro Decidualization with IL1β, PGE2, PGD2, or Butaprost Treatment.

Human mesenchymal stem cell proliferation is regulated by PGE2 through differential activation of cAMP-dependent protein kinase isoforms

The conditions used for in vitro differentiation of hMSCs contain substances that affect the activity and expression of cyclooxygenase enzymes (COX1/COX2) and thereby the synthesis of prostanoids. hMSC constitutively produce PGE2 when cultivated in vitro. In this study we have investigated effects of PGE2 on proliferation of hMSC. We here demonstrate that one of the main control molecules in the Wnt pathway, GSK-3β, is phosphorylated at the negative regulatory site ser-9 after treating the cells with PGE2. This phosphorylation is mediated by elevation of cAMP and subsequent activation of PKA. Furthermore, PGE2 treatment leads to enhanced nuclear translocation of β-catenin, thus influencing cell proliferation. The presence of two PKA isoforms, types I and II, prompted us to investigate their individual contribution in PGE2-mediated regulation of proliferation. Specific activation of PKA type II with synthetic cAMP analogues, resulted in enhancement of proliferation. On the other side, we found that treatment of hMSC with high concentrations of PGE2 inhibited cell proliferation by arresting the cells in G 0/G 1 phase, an effect we found to be mediated by PKA I. Hence, the two different PKA isoforms seem to have opposing functions in the regulation of proliferation and differentiation in these cells.

Prostaglandin E 2–regulated cervical ripening: analysis of proteoglycan expression in the rat cervix

Prostaglandins reduce cervical resistance by reorganizing collagen fibrils. Proteoglycans are involved in collagen fibril organization and structure. We evaluated the changes in proteoglycan composition induced by prostaglandin E(2) (PGE(2)). Prostaglandins were administered intravaginally to induce cervical ripening in timed pregnant Sprague-Dawley rats. Changes in proteoglycan messenger ribonucleic acid (mRNA) expression were measured using reverse transcription (RT-PCR) for core protein. Fluorophore assisted carbohydrate gel electrophoresis (FACE) was used to evaluate proteoglycan glycosaminoglycan composition along with size exclusion high-performance liquid chromatography (HPLC). No change in core protein mRNA expression was detected after PGE(2) treatment. Total glycosaminoglycan (GAG) decreased more than 20% after PGE(2) (P = .02). FACE demonstrated a shift in disaccharide subunit composition after PGE(2), with a decrease in 4-sulfated disaccharides (P = .02). HPLC confirmed a decrease in total GAG (P = .04). Although there was no change in core protein mRNA expression, alterations in GAG composition was detected after PGE(2). The decrease in sulfated GAG could decrease electrostatic interactions that would weaken interfibrillar interactions. These findings would be consistent with a decline in cervical resistance.

Evaluation of the Antiplatelet Effects of Cilostazol, a Phosphodiesterase 3 Inhibitor, by VASP Phosphorylation and Platelet Aggregation

Cilostazol, a phosphodiesterase 3 inhibitor, is an antiplatelet drug that is widely used for preventing cardiovascular events, although, to date, there are few methods for evaluating its effects. Blood samples were taken at baseline and at 3 and 12 h in 10 healthy male subjects after 100 mg cilostazol intake. Each sample was examined by Western blot for phosphorylation levels of vasodilator-stimulated phosphoprotein (VASP), an abundant cAMP-dependent kinase substrate in platelets, and by the optical aggregometer for ADP- and collagen-induced aggregation, before and after 8 nmol/L prostaglandin E(1) (PGE(1)) treatment. Cilostazol intake did not affect VASP phosphorylation levels or the maximal aggregation rates without PGE(1) treatment. However, cilostazol intake apparently enhanced PGE(1)-induced VASP phosphorylation and PGE(1)-mediated reduction of ADP-and collagen-induced maximal aggregation rates. Levels of VASP phosphorylated at Ser157 were correlated and the maximal aggregation rates induced by ADP were inversely correlated with cilostazol concentrations in the plasma. The antiplatelet effects of cilostazol intake could be evaluated by measuring VASP phosphorylation levels and maximal aggregation rates in platelets by ex vivo treatment with a low concentration of PGE(1).

Latanoprost does not affect immune privilege of corneal allografts

The present study determined whether topical latanoprost, a prostaglandin (PG) F2α analog, influences the induction of anterior chamber-associated immune deviation (ACAID), corneal neovascularization (NV) or survival of corneal allografts in mice. BALB/c mice received topical latanoprost or PGE2 once or multiple times daily starting 4weeks prior to or the day of anterior chamber injection of C57BL/6 splenocytes. Induction of allo-specific ACAID was assessed by ear challenge with C57BL/6 splenocytes 1week after subcutaneous immunization. In a separate experiment, orthotopic corneal transplantation was performed using C57BL/6 mice as donors and BALB/c mice as recipients. Recipients were randomized in a masked fashion to receive topical latanoprost or PGE2. Graft fate was assessed clinically under surgical microscopy. Presence of MHC class II+ CD11c+ or CD11b+ cells in normal BALB/c mouse eyes following latanoprost or PGE2 administration was assessed immunohistochemically. Control mice received topical 20% dimethyl sulfoxide or no treatment. Allo-specific ACAID was induced after 2 or 6weeks of once daily treatment with latanoprost, and was induced even after 6weeks of multiple treatments with latanoprost. Conversely, mice receiving PGE2 failed to develop ACAID. Opacity and corneal NV scores for allografts treated with latanoprost were statistically indistinguishable from those for control allografts (p>0.05), whereas all allografts treated with PGE2 were rejected. Opacity and NV scores were significantly higher in these allografts than in controls (p<0.05). A number of MHC class II+ CD11c+ cells were present in the central cornea after PGE2 treatment. Topical application of latanoprost does not influence induction of ACAID or graft outcomes including opacity and NV, whereas PGE2 does. Immune privilege of corneal allograft is maintained after topical latanoprost application in mice.

Hydrogen peroxide stimulates chloride secretion in primary inner medullary collecting duct cells via mPGES-1-derived PGE2

We investigated the role and mechanism of H2O2 in regulation of NaCl transport in primary inner medullary collecting duct (IMCD) cells. IMCD cells were isolated from wild-type mice and grown onto semipermeable membranes, and short-circuit current (Isc) was determined by Ussing chamber. Exposure of IMCD cells to H2O2 at a range of 100-300 microM caused a rapid increase in Isc in a time- and dose-dependent manner. This increase was almost abolished by the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel inhibitors diphenylamine-2-carboxylic acid (DPC) and CFTR inhibitor-172. In contrast, the magnitude of stimulation was unaffected by the epithelial Na+ channel (ENaC) inhibitor amiloride. The H2O2-induced Cl(-) secretion was significantly inhibited by indomethacin, as well as by microsomal PGE synthase-1 (mPGES-1) deficiency. Like H2O2, PGE2 treatment induced a twofold increase in Isc that was reduced by the protein kinase A (PKA) inhibitors H-89 and KT5720. These data suggest that H2O2 stimulates CFTR Cl(-) channel-mediated Cl(-) secretion through cyclooxygenase- and mPGES-1-dependent release of PGE2 and subsequent activation of PKA.

The effects of vitamin C on the interaction between COX-2 expression and IGF-I axis in the human melanoma cell line, SK-MEL-2 (49.27)

Abstract Overexpression of cyclooxygenase-2 (COX-2) frequently occurs in several malignancies and the type I insulin-like growth factor receptor (IGF-IR) is important for growth, transformation, proliferation and protection from apoptosis. However the interaction between COX-2 expression and IGF-I axis in human melanoma remains obscure. Although inhibition of COX-2 could reduce tumor volumes in various murine models, selective COX-2 inhibitors could increase cardiovascular risk. Therefore, we studied the effects of vitamin C, which is known as the potent inhibitor of proliferation of human melanoma cell line, SK-MEL-2. We confirmed that the optimal concentration of vitamin C for the inhibition of proliferation without inducing apoptosis is 1.0 mM. ELISA for IGF-I and IGF-II conducted after treatment with NS-398 and vitamin C revealed that the production of IGF-II was decreased by COX-2 inhibition. RT-PCR for IGF-IR after COX-2 inhibition using NS-398 or COX-2 siRNA showed the inhibition of COX-2 expression led to dramatic down-regulation of IGF-IR expression which is restored by adding exogenous PGE2, which is produced by the enzymatic action of COX-2. Next we observed that both COX-2 and IGF-IR expression were significantly decreased after treatment of 1.0 mM vitamin C. Interestingly exogenously treated IGF-II induced IGF-IR expression and exogenous PGE2 treatment restored IGF-IR expression which is down-regulated by vitamin C. These findings suggest that vitamin C could modulate IGF-II production and then down-regulate the expression of IGF-IR by the inhibition of COX-2 expression, followed by suppression of the proliferation of human melanoma cell line, SK-MEL-2.

Cross-talk between Peroxisome Proliferator-Activated Receptor δ and Cytosolic Phospholipase A2α/Cyclooxygenase-2/Prostaglandin E2 Signaling Pathways in Human Hepatocellular Carcinoma Cells

Peroxisome proliferator-activated receptor delta (PPARdelta) is a nuclear transcription factor that is recently implicated in tumorigenesis besides lipid metabolism. This study describes the cross-talk between the PPARdelta and prostaglandin (PG) signaling pathways that coordinately regulate human hepatocellular carcinoma (HCC) cell growth. Activation of PPARdelta by its pharmacologic ligand, GW501516, enhanced the growth of three human HCC cell lines (HuH7, HepG2, and Hep3B), whereas inhibition of PPARdelta by small interfering RNA prevented growth. PPARdelta activation up-regulates the expression of cyclooxygenase (COX)-2, a rate-limiting enzyme for PG synthesis, and tumor growth. PPARdelta activation or PGE(2) treatment also induced the phosphorylation of cytosolic phospholipase A(2)alpha (cPLA(2)alpha), a key enzyme that releases arachidonic acid substrate for PG production via COX. Activation of cPLA(2)alpha by the calcium ionophore A23187 enhanced PPARdelta binding to PPARdelta response element (DRE) and increased PPARdelta reporter activity, which was blocked by the selective cPLA(2)alpha inhibitors. Consistent with this, addition of arachidonic acid to isolated nuclear extracts enhanced the binding of PPARdelta to DRE in vitro, suggesting a direct role of arachidonic acid for PPARdelta activation in the nucleus. Thus, PPARdelta induces COX-2 expression and the COX-2-derived PGE(2) further activates PPARdelta via cPLA(2)alpha. Such an interaction forms a novel feed-forward growth-promoting signaling that may play a role in hepatocarcinogenesis.

Prostaglandin E2 (PGE2) Regulates Osteoblastic Jagged1 and Expands Primitive Hematopoietic Cells In Vivo.

Parathyroid Hormone (PTH) targets osteoblastic cells (OBs) in the bone marrow microenvironment and expands hematopoietic stem cells (HSC) through Notch activation. Since PTH stimulates the Notch ligand Jagged1 (J1) in OBs, we have focused on the signaling pathways involved in this PTH effect in order to identify novel activators of the HSC niche. Osteoblastic Protein Kinase A (PKA) activation is required for the PTH-dependent J1 increase in OBs. Therefore, we hypothesized that alternative PKA activators could also regulate osteoblastic J1, alter the HSC niche, and provide additional pharmacologic tools to expand HSC in vivo. Consistent with this hypothesis, direct PKA agonists 8-bromo-cAMP and dibutyryl-cAMP stimulated J1 in osteoblastic UMR106 cells. In addition, PGE2, a member of the prostaglandin family known to stimulate PKA in OBs, was studied in vivo and in vitro. By real-time RT-PCR analysis, J1 mRNA was increased up to 5 fold at 2 hours in UMR106 cells when treated with PGE2 (10−7 M) compared to vehicle. J1 protein was also increased after treatment with PGE2. The PGE2-dependent J1 increase was blocked in the presence of the specific PKA inhibitors H89 and myristoylated PKA Inhibitory Peptide (14–22)(PKI) (200ug/ml), demonstrating that PKA is necessary for osteoblastic J1 stimulation by PGE2. Since systemic PGE2 is known to have bone anabolic effects in both humans and animal models, adult wild-type FVB/N male mice were treated with PGE2 (6mg/kg/day i.p.) for 12 days. This regimen has previously been shown to have bone anabolic effects in rats. At day 12, histologic analysis demonstrated an anabolic effect mainly on cortical bone, as was evident in the femurs and tibiae of PGE2-treated mice compared to control. This histologic finding was confirmed by histomorphometry (trabecular bone area means 41% vs 12%,p=0.0916, n=3 in both groups; cortical thickness means 138 vs 85 μm, p=0.0071, n=3 in both groups). Frequency of hematopoietic stem cells (c-Kit+, Sca1+, lin−) was increased in bone marrow from PGE2-treated vs control mice by over 20% (p=0.0018, n=8 in both groups). In summary, PGE2 stimulates J1 in osteoblastic cells through PKA activation and increases mainly cortical bone in vivo. Ongoing studies will confirm whether in vivo PGE2 treatment expands HSC, and whether osteoblastic J1 regulates this process. This study identifies PGE2 as a novel regulator of osteoblastic J1, and as a potential new microenvironmental modulator of HSC, which could be used for in vivo therapeutic HSC niche manipulation.

Involvement of Cyclooxygenase-2–Prostaglandin E2 Pathway in Interleukin-8 Production in Gastric Cancer Cells

Prostaglandin E(2) (PGE(2)) is thought to play an important role in both inflammatory and anti-inflammatory effects. The effect of PGE(2) on the proinflammatory chemokine interleukin-8 (IL-8) in the gastric epithelial cells has not been defined yet. A gastric cancer cell line (MKN45) and primary gastric fibroblasts were cocultured with Helicobacter pylori standard strain (NCTC11637). The expressions of IL-8 and cyclooxygenase 2 (COX-2) mRNA were examined by reverse transcription polymerase chain reaction (RT-PCR) amplification. The amount of IL-8 antigen secreted by the MKN45 cells and gastric fibroblasts was measured by enzyme-linked immunosorbent assay (ELISA). We examined the effects of H pylori stimulation on IL-8 and COX-2 expression levels and the effects of COX-2 inhibitor on H pylori-induced IL-8 production in the MKN45 cells and gastric fibroblasts. Furthermore, we examined the expressions of subtypes of PGE(2) receptors, the effects of arachidonic acid and PGE(2) on IL-8 production, and the effects of PGE(2) on the total cellular cyclic adenosine monophosphate (cAMP) in MKN45 cells. MKN45 cells and gastric fibroblasts expressed IL-8 and COX-2 mRNA under stimulation with H pylori. The MKN45 cells produced IL-8 and PGE(2) antigen into the culture medium with H pylori stimulation, and the production level of IL-8 and PGE(2) antigen decreased significantly with COX-2 inhibitor pretreatment (concentration: 50 muM). On the other hand, the gastric fibroblasts strongly produced IL-8 antigen even in the unstimulated condition, and the amount of IL-8 antigen was not affected by H pylori stimulation and/or COX-2 inhibitor pretreatment. The MKN45 cells expressed IL-8 mRNA and released IL-8 antigen slightly, and the expression level of IL-8 mRNA and the amount of IL-8 antigen increased significantly with PGE(2) treatment in a dose-dependent manner. PGE(2)-induced IL-8 production was inhibited by pretreatment with EP2 and EP4 antagonists. The MKN45 cells expressed EP2 and EP4 subtypes of PGE(2) receptors, and these expression levels were not affected by H pylori stimulation or PGE(2) treatment. The amount of IL-8 antigen increased slightly, but not significantly, with arachidonic acid treatment. PGE(2) treatment for 15 minutes increased the total cellular cAMP in the MKN45 cells. These results suggest that the COX-2-PGE(2) pathway may be involved in IL-8 production in gastric epithelial cells.

Prostaglandin E2 and F2α receptors in the human Fallopian tube before and after mifepristone treatment

Prostaglandins are associated with several reproductive processes in addition to their effects on the vascular system and muscular contractility. The aim of this study was to gain information about the localization of the receptors for PGE(2) (EP1-EP4) and PGF(2alpha) (FP) in the human Fallopian tube and their regulation following treatment with mifepristone. Sixteen healthy fertile women received a single dose of 200 mg mifepristone or placebo immediately after ovulation (LH+2). Laparoscopic sterilization was performed on days LH+4 to LH+6. Biopsies were taken from the Fallopian tubes bilaterally. The expression of EP1, EP2, EP3, EP4 and FP was analysed using immunohistochemistry and RT-PCR. The co-localization of prostaglandin receptors and c-kit or e-nos was analysed using confocal microscopy. The effect of progesterone, mifepristone and prostaglandin on tubal contractility was studied. The presence of EP1-EP4 and FP in the Fallopian tube was detected using immunostaining. The receptors were expressed in serosal cells, luminal epithelial cells, and the muscular wall and vessels of the Fallopian tube. Co-localization studies showed that the endothelial cells stained positive for EP1-EP4 and FP and that co-localization was seen for EP4 and c-kit. Decreased contractility was seen after progesterone treatment, whereas increased contractility was seen after PGF(2alpha) and PGE(2) treatment. These data suggest that both the transport of the embryo and the communication between the embryo and the Fallopian tube involve the action of prostaglandins through EP and FP receptors in addition to the effect of prostaglandins on the vascular system and muscular contractility.

Effects of indomethacin and dexamethasone on mechanical scratching‐induced cutaneous barrier disruption in mice

Effects of indomethacin and dexamethasone on recovery of cutaneous barrier disruption induced by mechanical scratching were examined. Cutaneous barrier was disrupted by scratching using a stainless-steel wire brush (mechanical scratching) and compared to cutaneous application of acetone/ether (1:1) mixture (AE) and tape-stripping. Increase of transepidermal water loss (TEWL), as an indicator of a broken skin barrier, and recovery period for mechanical scratching were higher and longer than those for AE treatment and tape-stripping and we also confirmed the severity of skin damage in a histological study. Topical application of moisturizers showed a temporal effect, rapidly decreased TEWL on mechanical scratching- or AE treatment-induced cutaneous barrier disruption, and gradually increased base levels from 4 to 12 h after treatment. Topical application of indomethacin or dexamethasone prolonged the recovery period for the cutaneous barrier, and concomitant use further worsened the status of the barrier. Additionally, we examined the effects of prostaglandins (PGs) and inflammatory cytokine on mechanical scratching-induced cutaneous barrier disruption pretreated with indomethacin and dexamethasone. As a results, PGD2 and interleukin (IL)-1beta significantly accelerated the recovery of cutaneous barrier disruption by mechanical scratching but such was not the case with PGE2, IL-1alpha, and tumor necrosis factor-alpha treatment. These results suggest that indomethacin and dexamethasone prolonged the recovery period caused by inhibition of PGD2 and IL-1beta. Mechanical scratching-induced cutaneous barrier disruption may be a useful method for evaluating means of recovery from skin damage.

Human cytomegalovirus induced cyclooxygenase-2 in human retinal pigment epithelial cells augments viral replication through a prostaglandin pathway

Cytomegalovirus (CMV) retinitis is characterized by alterations in retinal cell function and host responses to virus replication. The goal of this study was to evaluate the induction of cyclooxygenase-2 (COX-2) and prostaglandin (PGE) in CMV infected human retinal pigment epithelial (RPE) cells and to determine their effect on virus replication. CMV immediate early (IE) protein and COX-2 proteins were identified in RPE cells in retinal tissue sections from patients with CMV retinitis. COX-2 mRNA and protein were induced after CMV infection of human RPE cell cultures. CMV infection of RPE cells induced translocation of NF-κB from the cytoplasm to the nucleus. PGE1 and PGE2 were significantly (p<0.001) increased in human RPE cell cultures infected with CMV. Inhibition of CMV IE gene by antisense oligonucleotides abrogated induction of mRNA for COX-2 and protein synthesis of COX-2 and PGE2. PGE enhanced CMV plaque formation and real time PCR analysis revealed that PGE treatment significantly increased CMV DNA copy numbers. These studies demonstrate that when CMV replicates within human RPE cells, COX-2 induction augments virus replication via the PGE pathway. The induction of COX-2 and PGE during retinal CMV infection may augment virus replication and alter a variety of retinal physiological responses.

IL-1β regulation of BDNF expression in rat cultured hypothalamic neurons depends on the presence of glial cells

In the present study, we have shown that IL-1β increased BDNF mRNA expression in hypothalamic neuron-enriched cultures whereas it reduced this expression in mixed cultures, i.e. containing astrocytes and neurons. Because functional relationships between stress and immunity signals are well documented we investigated the possible interaction between BDNF and IL-1β in hypothalamic neurons. Notably, we investigated whether IL-1β affected BDNF expression in vitro either on hypothalamic mixed cultures or on neuron-enriched cultures. We found that the response to IL-1β was stimulatory when directly examined in neurons but was inhibitory when astrocytes were present in the cultures. Since it has been documented that astrocytes release PGE2 in response to IL-1β, we examined the effect of indomethacin (a PGE2 synthesis inhibitor) on mixed or neuron-enriched cultures treated with IL-1β. Indomethacin blocked both stimulatory and inhibitory IL-1β effects on BDNF mRNA expression whereas picrotoxin (a GABA A blocker) or MK-801 (a NMDA receptor blocker) had no effect on BDNF mRNA levels. About 3 and 6 h treatments of cells with exogenous PGE2 reproduced the effects of IL-1β on neuron-enriched or on mixed cultures suggesting that PGE2 was involved in BDNF mRNA regulation. Analysis of PGE2 receptors mRNA expression revealed that the PGE2 receptor pattern was changed when neuron-enriched cultures were treated with conditioned medium produced by astrocytes treated with IL-1β. Thus, EP3 mRNA levels were increased while EP1 and EP4 messengers were unchanged. This increased expression of the inhibitory prostaglandin receptor under astrocyte influence can explain the inhibition of BDNF mRNA levels observed in mixed cultures following IL-1β or PGE2 treatment. Finally, we demonstrated by immunocytochemistry that EP3 receptors had a neuronal localization in the hypothalamic cultures. Taken together, these data contribute to underline an emerging physiological concept postulating that a same molecule may have opposite effects as a function of the cellular context.