OBJECTIVE: Our objective was to test the hypothesis, in a double-blind, placebo-controlled study that vipoglanstat, an inhibitor of microsomal prostaglandin E synthase-1 (mPGES-1) which decreases prostaglandin E2 (PGE2) and increases prostacyclin biosynthesis, improves RP.
METHODS: Patients with systemic sclerosis (SSc) and ≥7 RP attacks during the last screening week prior to a baseline visit were randomised to four weeks treatment with vipoglanstat 120 mg or placebo. A daily electronic diary captured RP attacks (duration and pain) and Raynaud\'s Condition Score, with change in RP attacks/week as primary end point. Cold challenge assessments were performed at baseline and end of treatment. Exploratory endpoints included patients\' and physicians\' global impression of change, Assessment of Scleroderma-associated Raynaud\'s Phenomenon questionnaire, mPGES-1 activity, and urinary excretion of arachidonic acid metabolites.
RESULTS: Sixty-nine subjects received vipoglanstat (n = 33) or placebo (n = 36). Mean weekly number of RP attacks (baseline; vipoglanstat 14.4[SD 6.7], placebo 18.2[12.6]) decreased by 3.4[95% CI -5.8;-1.0] and 4.2[-6.5;-2.0] attacks per week (p= 0.628) respectively. All patient reported outcomes improved, with no difference between the groups. Mean change in recovery of peripheral blood flow after cold challenge did not differ between the study groups. Vipoglanstat fully inhibited mPGES-1, resulting in 57% reduction of PGE2 and 50% increase of prostacyclin metabolites in urine. Vipoglanstat was safe and well tolerated.
CONCLUSIONS: Although vipoglanstat was safe, and well tolerated in a dose achieving full inhibition of mPGES-1, it was ineffective in SSc-related RP. Further development and evaluation of vipoglanstat will therefore be in other diseases where mPGES-1 plays a pathogenetic role.

We recently demonstrated that prostaglandin production in brain endothelial cells is both necessary and sufficient for the generation of fever during systemic immune challenge. I here discuss this finding in light of the previous literature and point to some unresolved issues.

The initiation of fever has been a matter of controversy. Based on observations of little or no induction of prostaglandin synthesizing enzymes in the brain during the first phase of fever it was suggested that fever is initiated by prostaglandin released into the circulation from cells in the liver and lungs. Here we show in the mouse that prostaglandin synthesis is rapidly induced in the brain after immune challenge. These data are consistent with our recent findings in functional experiments that prostaglandin production in brain endothelial cells is both necessary and sufficient for the generation of all phases of fever.

Fever is known to be elicited by prostaglandin E2 acting on the brain, but its origin has remained disputed. We show in mice that selective deletion of prostaglandin synthesis in brain endothelial cells, but not in neural cells or myeloid cells, abolished fever induced by intravenous administration of lipopolysaccharide and that selective rescue of prostaglandin synthesis in brain endothelial cells reinstated fever. These data demonstrate that prostaglandin production in brain endothelial cells is both necessary and sufficient for eliciting fever.

Animal studies suggest that pain-related-molecule upregulation in degenerated intervertebral discs (IVDs) potentially leads to low back pain (LBP). We hypothesized that IVD mechanical stress and axial loading contribute to discogenic LBP\'s pathomechanism. This study aimed to elucidate the relationships among the clinical findings, radiographical findings, and pain-related-molecule expression in human degenerated IVDs. We harvested degenerated-IVD samples from 35 patients during spinal interbody fusion surgery. Pain-related molecules including tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-6, calcitonin gene-related peptide (CGRP), microsomal prostaglandin E synthase-1 (mPGES1), and nerve growth factor (NGF) were determined. We also recorded preoperative clinical findings including body mass index (BMI), Oswestry Disability Index (ODI), and radiographical findings including the vacuum phenomenon (VP) and spinal instability. Furthermore, we compared pain-related-molecule expression between the VP (-) and (+) groups. BMI was significantly correlated with the ODI, CGRP, and mPGES-1 levels. In the VP (+) group, mPGES-1 levels were significantly higher than in the VP (-) group. Additionally, CGRP and mPGES-1 were significantly correlated. Axial loading and mechanical stress correlated with CGRP and mPGES-1 expression and not with inflammatory cytokine or NGF expression. Therefore, axial loading and mechanical stress upregulate CGRP and mPGES-1 in human degenerated IVDs, potentially leading to chronic discogenic LBP.

Using a wild yam (Dioscorea japonica), we previously found novel anti-inflammatory and anti-carcinogenic effects via the downregulation of cyclooxygenase (COX)-2 and microsomal prostaglandin E synthase (mPGES)-1. One of the substances in wild yam is a steroidal saponin, diosgenin. We demonstrated that diosgenin suppressed COX-2 in human non-small-cell lung carcinoma A549 cells via nuclear factor-kappa B (NF-κB) translocation and the effects were reversed by a glucocorticoid receptor antagonist, RU486. In lipopolysaccharide (LPS)-induced mouse liver injury, COX-2 and mPGES-1 were induced and localized in sinusoidal macrophages and endothelial cells; however, diosgenin administration significantly suppressed Ptgs2 and Ptges expression and decreased COX-2 and mPGES-1 immunopositive cells in the sinusoids. Multiple immunohistochemical analyses showed that diosgenin had an effect on COX-2 and mPGES-1, particularly in the macrophages. Thus, we showed that diosgenin downregulated COX-2 and mPGES-1 via the glucocorticoid receptor and suppressed COX-2 and mPGES-1 in the macrophages of LPS-induced acute mouse liver injury.

Prostaglandin E synthases (PGESs) convert cyclooxygenase (COX)-derived prostaglandin H2 (PGH2) into prostaglandin E2 (PGE2) and comprise at least three types of structurally and biologically distinct enzymes. Two of these, namely microsomal prostaglandin E synthase-1 (mPGES-1) and mPGES-2, are membrane-bound enzymes. mPGES-1 is an inflammation-inducible enzyme that converts PGH2 into PGE2. mPGES-2 is a bifunctional enzyme that generally forms a complex with haem in the presence of glutathione. This enzyme can metabolise PGH2 into malondialdehyde and can produce PGE2 after its separation from haem. In this review, we discuss the role of PGESs, particularly mPGES-1 and mPGES-2, in the pathogenesis of liver diseases. A better understanding of the roles of PGESs in liver disease may aid in the development of treatments for patients with liver diseases.

The majority of anti-cancer therapies target the proliferating tumor cells, while the tumor stroma, principally unaffected, survives, and provide a niche for surviving tumor cells. Combining tumor cell and stroma-targeting therapies thus have a potential to improve patient outcome. The neuroblastoma stroma contains cancer-associated fibroblasts expressing microsomal prostaglandin E synthase-1 (mPGES-1). mPGES-1-derived prostaglandin E2 (PGE2 ) is known to promote tumor growth through increased proliferation and survival of tumor cells, immune suppression, angiogenesis, and therapy resistance, and we, therefore, hypothesize that mPGES-1 constitutes an interesting stromal target. Here, we aimed to develop a relevant in vitro model to study combination therapies. Co-culturing of neuroblastoma and fibroblast cells in 3D tumor spheroids mimic neuroblastoma tumors with regard to the cyclooxygenase/mPGES-1/PGE2 pathway. Using the spheroid model, we show that the inhibition of fibroblast-derived mPGES-1 enhanced the cytotoxic effect of doxorubicin and vincristine and significantly reduced tumor cell viability and spheroid growth. Cyclic treatment with vincristine in combination with an mPGES-1 inhibitor abrogated cell repopulation. Moreover, inhibition of mPGES-1 potentiated the cytotoxic effect of vincristine on established neuroblastoma allografts in mice. In conclusion, we established a 3D neuroblastoma model, highlighting the potential of combining stromal targeting of mPGES-1 with tumor cell targeting drugs like vincristine.

Prostaglandin E2 (PGE2), which is a potent pro-inflammatory lipid mediator, is biosynthesized from arachidonic acid by cyclooxygenase-2 (COX-2) and microsomal PGE synthase-1 (mPGES-1). Non-steroidal anti-inflammatory drugs (NSAIDs) are used clinically as COX inhibitors, but they have gastrointestinal and cardiovascular side-effects. Thus, the terminal enzyme mPGES-1 holds promise as the next therapeutic target. In this study, we found that the ellagitannins granatin A and granatin B isolated from pomegranate leaves, and geraniin, which is their structural analog, selectively suppressed mPGES-1 expression without affecting COX-2 in non-small cell lung carcinoma A549 cells. The ellagitannins also down-regulated tumor necrosis factor α, inducible nitric oxide synthase, and anti-apoptotic factor B-cell chronic lymphocytic leukemia/lymphoma 2, and induced A549 cells to undergo apoptosis. These findings indicate that the ellagitannins have anti-inflammatory and anti-carcinogenic effects, due to their specific suppression of mPGES-1.Abbreviations: Bcl-2: B-cell chronic lymphocytic leukemia/lymphoma 2; COX: cyclooxygenase; CRE: cAMP response element; DHHDP: dehydrohexahydroxydiphenoyl; Et2O: diethyl ether; EtOAc: ethyl acetate; GAPDH: glyceraldehyde 3-phosphate dehydrogenase; iNOS: inducible nitric oxide synthase; mPGES-1: microsomal prostaglandin E synthase-1; n-BuOH: water-saturated n-butanol; NSAIDs: non-steroidal anti-inflammatory drugs; NF-κB: nuclear factor-κB; PG: prostaglandin; TNF: tumor necrosis factor; TUNEL: terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling.

The importance of prostaglandin E2 in cancer progression is well established, but research on its role in cancer has so far mostly been focused on epithelial cancer in adults while the knowledge about the contribution of prostaglandin E2 to childhood malignancies is limited. Neuroblastoma, an extracranial solid tumor of the sympathetic nervous system, mainly affects young children. Patients with tumors classified as high-risk have poor survival despite receiving intensive treatment, illustrating a need for new treatments complimenting existing ones. The basis of neuroblastoma treatment e.g. chemotherapy and radiation therapy, target the proliferating genetically unstable tumor cells leading to treatment resistance and relapses. The tumor microenvironment is an avenue, still to a great extent, unexplored and lacking effective targeted therapies. Cancer-associated fibroblasts is the main source of prostaglandin E2 in neuroblastoma contributing to angiogenesis, immunosuppression and tumor growth. Prostaglandin E2 is formed from its precursor arachidonic acid in a two-step enzymatic reaction. Arachidonic acid is first converted by cyclooxygenases into prostaglandin H2 and then further converted by microsomal prostaglandin E synthase-1 into prostaglandin E2. We believe targeting of microsomal prostaglandin E synthase-1 in cancer-associated fibroblasts will be an effective future therapeutic strategy in fighting neuroblastoma.