Concerted EP2 and EP4 Receptor Signaling Stimulates Autocrine Prostaglandin E2 Activation in Human Podocytes.
ABSTRACT: Glomerular hyperfiltration is an important mechanism in the development of albuminuria. During hyperfiltration, podocytes are exposed to increased fluid flow shear stress (FFSS) in Bowman's space. Elevated Prostaglandin E2 (PGE2) synthesis and upregulated cyclooxygenase 2 (Cox2) are associated with podocyte injury by FFSS. We aimed to elucidate a PGE2 autocrine/paracrine pathway in human podocytes (hPC). We developed a modified liquid chromatography tandem mass spectrometry (LC/ESI-MS/MS) protocol to quantify cellular PGE2, 15-keto-PGE2, and 13,14-dihydro-15-keto-PGE2 levels. hPC were treated with PGE2 with or without separate or combined blockade of prostaglandin E receptors (EP), EP2, and EP4. Furthermore, the effect of FFSS on COX2, PTGER2, and PTGER4 expression in hPC was quantified. In hPC, stimulation with PGE2 led to an EP2- and EP4-dependent increase in cyclic adenosine monophosphate (cAMP) and COX2, and induced cellular PGE2. PTGER4 was downregulated after PGE2 stimulation in hPC. In the corresponding LC/ESI-MS/MS in vivo analysis at the tissue level, increased PGE2 and 15-keto-PGE2 levels were observed in isolated glomeruli obtained from a well-established rat model with glomerular hyperfiltration, the Munich Wistar Frömter rat. COX2 and PTGER2 were upregulated by FFSS. Our data thus support an autocrine/paracrine COX2/PGE2 pathway in hPC linked to concerted EP2 and EP4 signaling.
Project description:To study the gene expression changes following application of Fluid Flow Shear Stress (FFSS) stimulus at end, post-2hr and post-24hr on mouse podocytes. We and others have started rethinking the concept of hyperfiltration as relative to changes in local biomechanical forces within the glomerulus. We believe that investigating the interplay of biomechanical forces on podocytes within the glomerulus may provide a better understanding of hyperfiltration-mediated kidney injury. The flow of glomerular ultrafiltrate creates shear stress on the surface of the podocyte. FFSS is largely exerted over the exposed outer aspect of major processes and the soma of podocytes. Our previous work suggests that COX2-PGE2-EP2 axis plays an important role in hyperfiltration-mediated injury, and targeting the EP2 receptor may have therapeutic significance. Thus to date we have identified COX-2-PGE2-EP2 axis in ‘mechanoperception’. The next logical step in this pursuit will be to address ‘mechanotransduction’, i.e. how podocyte converts the mechanical stimulus into biochemical signals that elicit specific cellular responses. To address this we took the approach of big data analysis using whole exon array analysis following application of FFSS to podocytes, and then selecting and validating pathways identified by bioinformatics tools that held biological relevance in FFSS in other epithelial cells and in EP2-mediated signaling. Overall design: 12 samples were analyzed. The samples were performed in triplicated for Control sample, for end of FFSS (end), at 2 hours following completion of FFSS (post-2hr) and 24 hours following completion of FFSS (post-24hr)
Project description:In the non-pregnant dog, ovarian cyclicity is independent of a uterine luteolysin. This is in contrast to pregnant animals where a prepartum increase of luteolytic PGF2? occurs, apparently originating in the pregnant uterus. Recently, the placenta as a source of prepartum prostaglandins (PGs) was investigated, indicating fetal trophoblast cells as the likely main source. However, the possible contribution of uterine interplacental tissues to the production of these hormones has not yet been thoroughly examined in the dog.Several key factors involved in the production and/or actions of PGs were studied: cyclooxygenase 2 (COX2, PTGS2), PGF2?-synthase (PGFS/AKR1C3), PGE2-synthase (PGES), and the respective receptors FP (PTGFR), EP2 (PTGER2) and EP4 (PGTER4), 15-hydroxyprostaglandin dehydrogenase (HPGD), PG-transporter (PGT, SLCO2A1) and progesterone receptor. Their expression and localization patterns were assessed by Real Time PCR and immunohistology in the interplacental uterine sites from pregnant dogs during the pre-implantation period (days 8-12), post-implantation (days 18-25), mid-gestation (days 35-40) and during antigestagen-induced luteolysis/abortion.Whereas only low COX2 expression was observed in uterine samples at all the selected time points, expression of PGFS/AKR1C3 strongly increased post-implantation. A gradual increase in PGES-mRNA expression was noted towards mid-gestation. FP-mRNA expression decreased significantly with the progression of pregnancy until mid-gestation. This was associated with clearly detectable expression of HPGD, which did not change significantly over time. The expression of FP and EP2-mRNA decreased significantly over time while EP4-mRNA expression remained unaffected. The antigestagen-treatment led to a significant increase in expression of COX2, PGES, EP2 and PGT (SLCO2A1) mRNA. COX2 was localized predominantly in the myometrium. The expression of PGFS/AKR1C3, which was unchanged, was localized mostly to the surface luminal epithelium. The expression of EP4, PGT and HPGH did not change during treatment, they were co-localized with PGES and EP2 in all uterine compartments.The data clearly demonstrate the basic capability of the canine pregnant uterus to produce and respond to PGs and suggests their functions both as local regulatory factors involved in the establishment and maintenance of pregnancy, as well as potential contributors to the process of parturition, supporting the myometrial contractility associated with fetal expulsion.
Project description:Bovine leukemia virus (BLV) infection is a chronic viral infection of cattle and endemic in many countries, including Japan. Our previous study demonstrated that PGE<sub>2</sub>, a product of cyclooxygenase (COX) 2, suppresses Th1 responses in cattle and contributes to the progression of Johne disease, a chronic bacterial infection in cattle. However, little information is available on the association of PGE<sub>2</sub> with chronic viral infection. Thus, we analyzed the changes in plasma PGE<sub>2</sub> concentration during BLV infection and its effects on proviral load, viral gene transcription, Th1 responses, and disease progression. Both <i>COX2</i> expression by PBMCs and plasma PGE<sub>2</sub> concentration were higher in the infected cattle compared with uninfected cattle, and plasma PGE<sub>2</sub> concentration was positively correlated with the proviral load. BLV Ag exposure also directly enhanced PGE<sub>2</sub> production by PBMCs. Transcription of BLV genes was activated via PGE<sub>2</sub> receptors EP2 and EP4, further suggesting that PGE<sub>2</sub> contributes to disease progression. In contrast, inhibition of PGE<sub>2</sub> production using a COX-2 inhibitor activated BLV-specific Th1 responses in vitro, as evidenced by enhanced T cell proliferation and Th1 cytokine production, and reduced BLV proviral load in vivo. Combined treatment with the COX-2 inhibitor meloxicam and anti-programmed death-ligand 1 Ab significantly reduced the BLV proviral load, suggesting a potential as a novel control method against BLV infection. Further studies using a larger number of animals are required to support the efficacy of this treatment for clinical application.
Project description:BACKGROUND:IL-23 is the key cytokine for generation of pathogenic IL-17-producing helper T (TH17) cells, which contribute critically to autoimmune diseases. However, how IL-23 generates pathogenic TH17 cells remains to be elucidated. OBJECTIVES:We sought to examine the involvement, molecular mechanisms, and clinical implications of prostaglandin (PG) E2-EP2/EP4 signaling in induction of IL-23-driven pathogenic TH17 cells. METHODS:The role of PGE2 in induction of pathogenic TH17 cells was investigated in mouse TH17 cells in culture in vitro and in an IL-23-induced psoriasis mouse model in vivo. Clinical relevance of the findings in mice was examined by using gene expression profiling of IL-23 and PGE2-EP2/EP4 signaling in psoriatic skin from patients. RESULTS:IL-23 induces Ptgs2, encoding COX2 in TH17 cells, and produces PGE2, which acts back on the PGE receptors EP2 and EP4 in these cells and enhances IL-23-induced expression of an IL-23 receptor subunit gene, Il23r, by activating signal transducer and activator of transcription (STAT) 3, cAMP-responsive element binding protein 1, and nuclear factor ? light chain enhancer of activated B cells (NF-?B) through cyclic AMP-protein kinase A signaling. This PGE2 signaling also induces expression of various inflammation-related genes, which possibly function in TH17 cell-mediated pathology. Combined deletion of EP2 and EP4 selectively in T cells suppressed accumulation of IL-17A+ and IL-17A+IFN-?+ pathogenic Th17 cells and abolished skin inflammation in an IL-23-induced psoriasis mouse model. Analysis of human psoriatic skin biopsy specimens shows positive correlation between PGE2 signaling and the IL-23/TH17 pathway. CONCLUSIONS:T cell-intrinsic EP2/EP4 signaling is critical in IL-23-driven generation of pathogenic TH17 cells and consequent pathogenesis in the skin.
Project description:The methylation profiles of bisulfite-modified DNA of human CD14+ monocytes were compared with derived immature dendritic cells (GM-CSF/IL-4 ), myeloid-derived suppressor cells (GM-CSF/IL-4/PGE-2), EP2 antagonized myeloid-derived suppressor cells (GM-CSF/IL-4/PGE-2/ PF 04418948 5 µM), EP4 antagonized myeloid-derived suppressor cells (GM-CSF/IL-4/PGE-2/ L-161,982 5 µM) and EP2 + EP4 antagonized myeloid-derived suppressor cells (GM-CSF/IL-4/PGE-2/PF 04418948 5 µM /L-161,982 5 µM) using the Infinium HumanMethylation450 BeadChips (Illumina, Inc., San Diego, CA,). This platform allows the interrogation of >485,000 methylation sites per sample at single-nucleotide resolution, and comprises an average of 17 CpG sites per gene in the 99% of RefSeq genes. 96% of CpG islands are covered, with additional coverage in CpG island shores and the regions flanking them. The samples were hybridized in the array following the manufacturer’s instructions. Overall design: Total DNA isolated by standard procedures from CD14+ cells (total monocytes, MOs) corresponding to six sets of samples of monocytes (MOs), derived immature DCs, myeloid-derived suppressor cells, EP2 antagonized myeloid-derived suppressor cells, EP4 antagonized myeloid-derived suppressor cells and EP2 + EP4 antagonized myeloid-derived suppressor cells (DCS and MDSCs).
Project description:Prostaglandins, PGE(2) in particular, have diverse actions on various organs, including inflammation, bone healing, bone formation, embryo implantation, induction of labour and vasodilatation, among others. However, systemic side effects have limited their clinical utility. The pharmacological activities of PGE(2) are mediated through four G protein-coupled receptor subtypes, EP1-EP4. Recent studies have shown that EP2 and EP4 receptors play important roles in regulating bone formation and resorption. EP2 and EP4 receptor-selective agonists have been shown to stimulate local or systemic bone formation, augment bone mass and accelerate the healing of fractures or bone defects in animal models upon local or systemic administration, thus, potentially offering new therapeutic options for enhancing bone formation and bone repair in humans. This review will focus on the studies related to bone formation and bone healing in the EP receptor knockout (KO) mice and the EP2 or EP4 receptor-selective agonist treated animal models.
Project description:Timely interaction between the egg and sperm is required for successful fertilization; however, little is known about the signaling therein. Prostaglandin (PG) E receptor EP2-deficient (Ptger2(-/-)) female mice exhibit a severe fertilization defect. We investigated the molecular events leading to this failure. We found increased gene expression for chemokines, such as Ccl2, Ccl7, and Ccl9, in Ptger2(-/-) cumulus cells (the somatic cells surrounding the egg) compared with wild-type cells. Furthermore, under physiological conditions, cumulus-derived chemokine signaling was found to have a dual action; CCL7 facilitates sperm migration to the cumulus-egg complex and integrin-mediated cumulus extracellular matrix (ECM) assembly to protect eggs. However, in the absence of PGE(2)-EP2 signaling, chronic CCL7 signaling results in excessive integrin engagement to the ECM, making the cumulus ECM resistant to sperm hyaluronidase, thereby preventing sperm penetration. Our findings indicate that PGE(2)-EP2 signaling negatively regulates the autocrine action of chemokines and prevents excessive cumulus ECM assembly. This interaction between PG and chemokine signaling is required for successful fertilization.
Project description:Mineral trioxide aggregate (MTA) is a commonly used dental pulp-capping material with known effects in promoting reparative dentinogenesis. However, the mechanism by which MTA induces dentine repair remains unclear. The aim of the present study was to investigate the role of prostaglandin E2 (PGE2) in dentine repair by examining the localisation and mRNA expression levels of its transporter (Pgt) and two of its receptors (Ep2 and Ep4) in a rat model of pulpotomy with MTA capping. Ep2 expression was detected in odontoblasts, endothelial cells, and nerve fibres in normal and pulpotomised tissues, whereas Pgt and Ep4 were immunolocalised only in the odontoblasts. Moreover, mRNA expression of Slco2a1 (encoding Pgt), Ptger2 (encoding Ep2), and Ptger4 (encoding Ep4) was significantly upregulated in pulpotomised dental pulp and trigeminal ganglia after MTA capping. Our results provide insights into the functions of PGE2 via Pgt and Ep receptors in the healing dentine/pulp complex and may be helpful in developing new therapeutic targets for dental disease.
Project description:Prostaglandin (PG) E(2), a major product of activated macrophages, has been implicated in atherosclerosis and plaque rupture. The PGE(2) receptors, EP2 and EP4, are expressed in atherosclerotic lesions and are known to inhibit apoptosis in cancer cells. To examine the roles of macrophage EP4 and EP2 in apoptosis and early atherosclerosis, fetal liver cell transplantation was used to generate LDLR(-/-) mice chimeric for EP2(-/-) or EP4(-/-) hematopoietic cells. After 8 weeks on a Western diet, EP4(-/-) --> LDLR(-/-) mice, but not EP2(-/-) --> LDLR(-/-) mice, had significantly reduced aortic atherosclerosis with increased apoptotic cells in the lesions. EP4(-/-) peritoneal macrophages had increased sensitivity to proapoptotic stimuli, including palmitic acid and free cholesterol loading, which was accompanied by suppression of activity of p-Akt, p-Bad, and NF-kappaB-regulated genes. Thus, EP4 deficiency inhibits the PI3K/Akt and NF-kappaB pathways compromising macrophage survival and suppressing early atherosclerosis, identifying macrophage EP4-signaling pathways as molecular targets for modulating the development of atherosclerosis.
Project description:To elucidate the pathophysiologic links between prostaglandin E(2) (PGE(2)) and osteoarthritis (OA) by characterizing the catabolic effects of PGE(2) and its unique receptors in human adult articular chondrocytes.Human adult articular chondrocytes were cultured in monolayer or alginate beads with and without PGE(2) and/or agonists of EP receptors, antagonists of EP receptors, and cytokines. Cell survival, proliferation, and total proteoglycan synthesis and accumulation were measured in alginate beads. Chondrocyte-related gene expression and phosphatidylinositol 3-kinase/Akt signaling were assessed by real-time reverse transcription-polymerase chain reaction and Western blotting, respectively, using a monolayer cell culture model.Stimulation of human articular chondrocytes with PGE(2) through the EP2 receptor suppressed proteoglycan accumulation and synthesis, suppressed aggrecan gene expression, did not appreciably affect expression of matrix-degrading enzymes, and decreased the type II collagen:type I collagen ratio. EP2 and EP4 receptors were expressed at higher levels in knee cartilage than in ankle cartilage and in a grade-dependent manner. PGE(2) titration combined with interleukin-1 (IL-1) synergistically accelerated expression of pain-associated molecules such as inducible nitric oxide synthase and IL-6. Finally, stimulation with exogenous PGE(2) or an EP2 receptor-specific agonist inhibited activation of Akt that was induced by insulin-like growth factor 1.PGE(2) exerts an antianabolic effect on human adult articular cartilage in vitro, and EP2 and EP4 receptor antagonists may represent effective therapeutic agents for the treatment of OA.