Elevated Prostaglandin E2 Levels Research Articles

Age-Associated Increase in Skin Fibroblast–Derived Prostaglandin E2 Contributes to Reduced Collagen Levels in Elderly Human Skin

Production of type I collagen declines during aging, leading to skin thinning and impaired function. Prostaglandin E2 (PGE2) is a pleiotropic lipid mediator that is synthesized from arachidonic acid by the sequential actions of cyclooxygenases (COX) and PGE synthases (PTGES). PGE2 inhibits collagen production by fibroblasts in vitro. We report that PTGES1 and COX2 progressively increase with aging in sun-protected human skin. PTGES1 and COX2 mRNA was increased 3.4-fold and 2.7-fold, respectively, in the dermis of elderly (>80 years) versus young (21-30 years) individuals. Fibroblasts were the major cell source of both enzymes. PGE2 levels were increased 70% in elderly skin. Fibroblasts in aged skin display reduced spreading due to collagen fibril fragmentation. To investigate the relationship between spreading and PGE2 synthesis, fibroblasts were cultured on micropost arrays or hydrogels of varying mechanical compliance. Reduced spreading/mechanical force resulted in increased expression of both PTGES1 and COX2 and elevated levels of PGE2. Inhibition of PGE2 synthesis by diclofenac enhanced collagen production in skin organ cultures. These data suggest that reduced spreading/mechanical force of fibroblasts in aged skin elevates PGE2 production, contributing to reduced collagen production. Inhibition of PGE2 production may be therapeutically beneficial for combating age-associated collagen deficit in human skin.

Sustained adrenergic signaling leads to increased metastasis in ovarian cancer via increased PGE2 synthesis.

Adrenergic stimulation adversely affects tumor growth and metastasis, but the underlying mechanisms are not well understood. Here, we uncovered a novel mechanism by which catecholamines induce inflammation by increasing prostaglandin E2 (PGE2) levels in ovarian cancer cells. Metabolic changes in tumors isolated from patients with depression and mice subjected to restraint stress showed elevated PGE2 levels. Increased metabolites and PTGS2 and PTGES protein levels were found in Skov3-ip1 and HeyA8 cells treated with norepinephrine, and these changes were shown to be mediated by ADRB2 receptor signaling. Silencing PTGS2 resulted in significantly decreased migration and invasion in ovarian cancer cells in the presence of norepinephrine and decreased tumor burden and metastasis in restraint stress orthotopic models. In human ovarian cancer samples, concurrent increased ADRB2, PTGS2 and PTGES expression was associated with reduced overall and progression-free patient survival. In conclusion, increased adrenergic stimulation results in increased PGE2 synthesis via ADRB2-Nf-kB-PTGS2 axis, which drives tumor growth and metastasis.

COX/mPGES-1/PGE2 pathway depicts an inflammatory-dependent high-risk neuroblastoma subset

The majority of solid tumors are presented with an inflammatory microenvironment. Proinflammatory lipid mediators including prostaglandin E2 (PGE2) contribute to the establishment of inflammation and have been linked to tumor growth and aggressiveness. Here we show that high-risk neuroblastoma with deletion of chromosome 11q represents an inflammatory subset of neuroblastomas. Analysis of enzymes involved in the production of proinflammatory lipid mediators showed that 11q-deleted neuroblastoma tumors express high levels of microsomal prostaglandin E synthase-1 (mPGES-1) and elevated levels of PGE2. High mPGES-1 expression also corresponded to poor survival of neuroblastoma patients. Investigation of the tumor microenvironment showed high infiltration of tumor-promoting macrophages with high expression of the M2-polarization markers CD163 and CD206. mPGES-1-expressing cells in tumors from different subtypes of neuroblastoma showed differential expression of one or several cancer-associated fibroblast markers such as vimentin, fibroblast activation protein α, α smooth muscle actin, and PDGF receptor β. Importantly, inhibition of PGE2 production with diclofenac, a nonselective COX inhibitor, resulted in reduced tumor growth in an in vivo model of 11q-deleted neuroblastoma. Collectively, these results suggest that PGE2 is involved in the tumor microenvironment of specific neuroblastoma subgroups and indicate that therapeutic strategies using existing anti-inflammatory drugs in combination with current treatment should be considered for certain neuroblastomas.

Induction of lipoxin A4 by Francisella tularensis: a mechanism for regulation of pro-inflammatory responses during early-phase tularemia (INM3P.401)

Abstract During respiratory tularemia, caused by inhalation of Francisella tularensis (Ft), we postulate that bacteria establish a principally anti-inflammatory environment and subvert host cell death programs to facilitate their unfettered replication within various cell types. Here we have explored the role of lipid mediators such as lipoxin A4 (LXA4) and prostaglandin E2 (PGE2) in host inflammatory responses manifested early during infection with Ft. An inverse relationship was observed between the production of LXA4 and PGE2 suggesting that Ft induces the generation of these eicosanoids to modulate cell death and enhance its own survival. This notion is supported by our findings that Ft triggers the release of LXA4, which inhibits apoptosis of macrophages. We also have elucidated the course of tularemia in mice deficient for 5-lipoxygenase (5-LO), leaving them incapable of generating LXA4, and observed elevated levels of PGE2, increased apoptosis, increased neutrophil recruitment and elevated release of pro-inflammatory cytokines and chemokines as compared to their wild-type counterparts. 5-LO deficient mice also were found to be less susceptible to lethal doses of Ft LVS as compared to wild-type mice. Our results suggests that 5-LO activity increases susceptibility to Ft infection, suggesting that targeting this pathway may have therapeutic benefit by limiting bacterial growth in tularemic individuals and perhaps those infected with other virulent respiratory pathogens.

Differential effects of dexamethasone and rosiglitazone in a sephadex-induced model of lung inflammation in rats: possible role of tissue inhibitor of metalloproteinase-3.

Objectives:To study the effects of two different classes of drugs in sephadex-induced lung inflammation using rats and explore the potential mechanism (s).Materials and Methods:Effects of dexamethasone (0.3 mg/kg, p.o.) and rosiglitazone (10 mg/kg, p.o.) treatments were evaluated up to 3 days in sephadex challenged rats. 72 h postsephadex administration, broncho-alveolar lavage fluid (BALF) was collected for cell count and cytokine estimation. Lung tissues were harvested for gene expression and histopathology.Results:Dexamethasone treatment resulted in significant inhibition of lymphocytes, monocytes, eosinophils and neutrophils, whereas rosiglitazone inhibited eosinophils and neutrophils only. Further, dexamethasone reduced the elevated levels of prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) after sephadex challenge while rosiglitazone significantly reduced the PGE2 levels without altering LTB4 in the BALF. Hydroxyproline content in rat lung homogenate was significantly reduced with dexamethasone treatment but not with rosiglitazone. Both the drugs were found to suppress matrix metallo proteinase 9, whereas only dexamethasone showed inhibition of tumor necrosis factor-alpha and up-regulation of tissue inhibitor of metalloproteinase 3 (TIMP-3) expression and preserved the broncho-alveolar microstructure.Conclusions:Our results revealed that up-regulation of TIMP-3 corroborated well with dexamethasone mediated inhibition of collagen degradation and restoration of alveolar micro-architecture.

Wound healing effects of new 15-hydroxyprostaglandin dehydrogenase inhibitors

Previously, we reported that the antidiabetic drug ciglitazone and its analogs were potent inhibitors of 15-hydroxyprostaglandin dehydrogenase (15-PGDH). In continuing attempts to develop highly potent 15-PGDH inhibitors, a series of thiazolidinedione analogs were synthesized and tested. Compound 17 exhibited IC50 of 45nM. This compound also significantly increased levels of prostaglandin E2 (PGE2) in A549 cells by approximately eight-fold that in the control. Much experimental data suggests that PGE2 plays a role in the prevention of excessive scarring. However, it has a very short half-life in blood, its oxidization to 15-ketoprostaglandins is catalyzed by 15-PGDH. Therefore, 15-PGDH inhibitors may have utility for the therapeutic management of diseases requiring elevated PGE2 levels. Scratch wounds were analyzed in confluent monolayers of HaCaT cells. Cells exposed to compound 17 showed significantly improved wound healing with respect to a control.

Abstract 3986: Characterization of prostaglandin signaling in primary neuroblastoma

Abstract Neuroblastoma (NB) is an embryonic childhood tumor of the sympathetic nervous system. Despite intensive treatment patients in the high-risk group of NB shows a poor prognosis. We have shown the importance of inflammation in NB development and progression and that the pro-inflammatory lipid mediator prostaglandin E2 (PGE2) acts as a paracrine survival factor in NB. We have also shown that mPGES-1, essential for PGE2 synthesis, promotes growth and survival of several malignancies. In this study we focus on the abundance of prostaglandins and their specific enzymes in primary NB of different biological and clinical subsets in the aim of finding a more specific and targeted NB treatment. Levels of prostaglandins were assayed in 40 primary human NB tumors by mass spectrometry (MS) showing elevated levels of PGE2 in high risk 11q-deleted NB compared to low-risk NB whereas elevated levels of prostaglandin D2 (PGD2) could be coupled to NB with favorable clinical outcome. The expression of COX-1, COX-2, mPGES-1, L-PGDS, H-PGDS and 15-PGDH were analyzed in tumors by immunohistochemistry (IHC). Expression of mPGES-1 and L-PGDS was found in all analyzed tumors. Double stainings of mPGES-1 and the specific NB cell marker GD2 were performed on tumors with different biology using immunofluorescence. In low-risk tumors mPGES-1 is not expressed by the tumor cells whereas co-localization were found in 11q deleted high-risk tumors. To consider the level of inflammation and PGE2 signaling in these tumors we analyzed cell markers of both the innate and adaptive immune system together with mPGES-1. In all tumors mPGES-1 expressing cells are found in clusters closely together with T-cells, B-cells, dendritic cells and M1/M2 macrophages. Together this suggests an involvement of inflammatory prostaglandins in neuroblastoma development and tumor progression opening up new strategies for targeted therapies. Citation Format: Anna Kock, Karin Larsson, Linda Ljungblad, Helena Idborg, Marina Korotkova, Lotta Elfman, John-Inge Johnsen, Per-Johan Jakobsson, Per Kogner. Characterization of prostaglandin signaling in primary neuroblastoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3986. doi:10.1158/1538-7445.AM2014-3986

Prostaglandin E2 promotes features of replicative senescence in chronically activated human CD8+ T cells.

Prostaglandin E2 (PGE2), a pleiotropic immunomodulatory molecule, and its free radical catalyzed isoform, iso-PGE2, are frequently elevated in the context of cancer and chronic infection. Previous studies have documented the effects of PGE2 on the various CD4+ T cell functions, but little is known about its impact on cytotoxic CD8+ T lymphocytes, the immune cells responsible for eliminating virally infected and tumor cells. Here we provide the first demonstration of the dramatic effects of PGE2 on the progression of human CD8+ T cells toward replicative senescence, a terminal dysfunctional state associated multiple pathologies during aging and chronic HIV-1 infection. Our data show that exposure of chronically activated CD8+ T cells to physiological levels of PGE2 and iso-PGE2 promotes accelerated acquisition of markers of senescence, including loss of CD28 expression, increased expression of p16 cell cycle inhibitor, reduced telomerase activity, telomere shortening and diminished production of key cytotoxic and survival cytokines. Moreover, the CD8+ T cells also produced higher levels of reactive oxygen species, suggesting that the resultant oxidative stress may have further enhanced telomere loss. Interestingly, we observed that even chronic activation per se resulted in increased CD8+ T cell production of PGE2, mediated by higher COX-2 activity, thus inducing a negative feedback loop that further inhibits effector function. Collectively, our data suggest that the elevated levels of PGE2 and iso-PGE2, seen in various cancers and HIV-1 infection, may accelerate progression of CD8+ T cells towards replicative senescence in vivo. Inhibition of COX-2 activity may, therefore, provide a strategy to counteract this effect.

Sphingosine 1-phosphate (S1P) induces COX-2 expression and PGE2 formation via S1P receptor 2 in renal mesangial cells

Understanding the mechanisms of sphingosine 1-phosphate (S1P)-induced cyclooxygenase (COX)-2 expression and prostaglandin E2 (PGE2) formation in renal mesangial cells may provide potential therapeutic targets to treat inflammatory glomerular diseases. Thus, we evaluated the S1P-dependent signaling mechanisms which are responsible for enhanced COX-2 expression and PGE2 formation in rat mesangial cells under basal conditions. Furthermore, we investigated whether these mechanisms are operative in the presence of angiotensin II (Ang II) and of the pro-inflammatory cytokine interleukin-1β (IL-1β).Treatment of rat and human mesangial cells with S1P led to concentration-dependent enhanced expression of COX-2. Pharmacological and molecular biology approaches revealed that the S1P-dependent increase of COX-2 mRNA and protein expression was mediated via activation of S1P receptor 2 (S1P2). Further, inhibition of Gi and p42/p44 MAPK signaling, both downstream of S1P2, abolished the S1P-induced COX-2 expression. In addition, S1P/S1P2-dependent upregulation of COX-2 led to significantly elevated PGE2 levels, which were further potentiated in the presence of Ang II and IL-1β. A functional consequence downstream of S1P/S1P2 signaling is mesangial cell migration that is stimulated by S1P. Interestingly, inhibition of COX-2 by celecoxib and SC-236 completely abolished the migratory response.Overall, our results demonstrate that extracellular S1P induces COX-2 expression via activation of S1P2 and subsequent Gi and p42/p44 MAPK-dependent signaling in renal mesangial cells leading to enhanced PGE2 formation and cell migration that essentially requires COX-2. Thus, targeting S1P/S1P2 signaling pathways might be a novel strategy to treat renal inflammatory diseases.

969 Bolus Retention in Hiatal Hernias Identified by High-Resolution Esophageal Manometry With Impedance: Pathophysiological and Clinical Significance

Background & Aims: Given the previous evidence for involvement of Prostaglandin E2 (PGE2) and the EP1 receptor in processing of esophageal sensation, the present study investigated the effect of diclofenac sodium, a nonsteroidal anti-inflammatory drug, on esophageal sensation induced by distal acid infusion in healthy volunteers. Methods: Twelve healthy male subjects were enrolled in a randomized, placebo-controlled crossover study. After oral administration of either diclofenac or placebo, acid (hydrochloric acid, 0.15 mol/ L) was perfused into the lower esophagus for 30 minutes. Diclofenac (37.5 mg) was given twice at 6 hours and 2 hours before acid perfusion. Heartburn symptoms were evaluated using a validated categorical rating scale with a higher values corresponding to increasing intensity. The acid perfusion sensitivity score (APSS) was assessed. Before and after acid perfusion, endoscopic biopsies were taken from the distal esophagus. PGE2 concentration (pg/mg protein) in the biopsy samples was measured using ELISA. Results: Except in 1 subject, eleven subjects (age range 26-41, mean 32.9 years) completed this study. The APSS was significantly lower in the diclofenac group compared to the placebo group (diclofenac group vs placebo group: 79.1 ± 14.9 vs 137.1 ± 20.4, P , 0.01). The time to first sensation (min) was significantly longer after diclofenac treatment (diclofenac group vs placebo group: 13.7 ± 2.3 vs 5.6 ± 1.5, P , 0.01). PGE2 levels after acid perfusion in the esophageal biopsy samples were significantly higher in the placebo group (before acid vs after acid: 7.7 ± 1.2 vs 23.3 ± 5.2, P , 0.05), but not in the diclofenac group (before acid vs after acid: 6.4 ± 1.1 vs 11.4 ± 3.5, P . 0.05). Furthermore, there was a clear correlation between the APSS and the elevated levels of PGE2 in the esophagus (r = 0.53, P , 0.05). Conclusions & Inferences: This study demonstrated that diclofenac may attenuate acid-induced esophageal sensation by inhibition of PGE2 overproduction in the human esophagus. PGE2 in the esophagus may play a significant role in the esophageal symptom generation, and may be a new therapeutic target for controlling symptoms such as heartburn.

LGR5 promotes survival in human colorectal adenoma cells and is upregulated by PGE 2 : implications for targeting adenoma stem cells with NSAIDs

Cyclooxygenase-2 is overexpressed in the majority of colorectal tumours leading to elevated levels of prostaglandin E2 (PGE2), promoting many hallmarks of cancer. Importantly, PGE2 is reported to enhance Wnt/β-catenin signalling in colorectal carcinoma cells and in normal haematopoietic stem cells where it promotes stem cell function. Although Wnt signalling plays a crucial role in intestinal stem cells, the relationship between PGE2 and intestinal stem cells is unclear. Given that the key intestinal cancer stem cell marker LGR5 (leucine-rich G-protein coupled receptor 5) is a Wnt target and PGE2 enhances Wnt signalling, the focus of this study was to investigate whether PGE2 regulated LGR5 expression in colorectal adenoma cells and whether LGR5 was important for tumour cell survival. PGE2 upregulated LGR5 protein in adenoma (RG/C2) and carcinoma (DLD-1) cell lines. LGR5 knockdown induced cell death in RG/C2 and AA/C1 adenoma cells, suggesting that LGR5 has an important survival-promoting role in adenoma cells. Indeed, we detected LGR5 protein expression in 4 of 4 human adenoma cell lines. Furthermore, LGR5 small interfering RNA inhibited the survival-promoting effects of PGE2 in RG/C2, suggesting that PGE2 promotes adenoma cell survival, at least in part, by increasing LGR5 expression. These studies, therefore, show the first link between PGE2 and LGR5 in human colorectal adenoma and carcinoma cells and demonstrate a survival-promoting role of LGR5. As non-steroidal anti-inflammatory drugs (NSAIDs) cause adenomas to regress in FAP patients, these studies could have important implications for the mechanism by which NSAIDs are chemopreventive, as lowering PGE2 levels could reduce LGR5 expression and survival of LGR5(+) adenoma stem cells.

Prostaglandin E2 Increase in Pachydermoperiostosis Without 15-hydroprostaglandin Dehydrogenase Mutations

Pachydermoperiostosis (PDP), a form of primary hyper­trophic osteoarthropathy (PHO), is a rare hereditary disease diagnosed by the presence of the triad of digital clubbing, periostosis, and pachydermia (1, 2). Elevated prostaglandin E2 (PGE2) levels with cytokine­mediated tissue remodelling and vascular stimulation may underlie PHO and is associated with the features such as hyper­hidrosis, acroosteolysis, pachydermia, periostosis and arthritis (3). Homozygous and compound heterozygous germline mutations in the 15­hydroxyprostaglandin dehydrogenase (HPGD) gene encoding the major PGE2 catabolizing enzyme have been described in familial PHO cases (4). We report here a case of primary PDP with increased serum PGE2 levels that was not accompanied by HPGD mutations.CASE REPORTA 53­year­old man was referred to our hospital. He began to experience idiopathic symmetrical arthral­gias of both knees at around 20 years of age. Physical examination revealed thickened skin on the face and head, and marked clubbing of the fingers (Fig. 1a, b). No other remarkable physical findings were observed, and he did not present seborrhoea, acne, folliculitis or hyperhidrosis. Family history was non-contributory. All laboratory tests including serum levels of growth hormone, insulin­like growth factor­1, thyroid fun­ction, immunoglobulins, haemoglobin A1c, and bone mineral metabolism were within normal ranges, which ruled out thyroid acropathy and acromegaly. Magnetic resonance imaging of the head revealed cutis verticis gyrate (Fig. 1c). X-ray examination of the knee region revealed periostosis with cortical thickening and ec­topic ossification (Fig. 1d). Histology of the forehead skin revealed acanthosis in the epidermis, sebaceous and sweat gland enlargement, and mucin deposits in the dermis (Fig. 2). These findings met the diagnostic criteria of the complete form of PDP.Since it has been reported that PGE2 is a mediator of this disorder, we examined PGE2 levels using a com­mercial enzyme immunoassay kit (Cayman, Cayman Biochemical, Ann Arbor, MI, USA). Consistent with the previous reports, PGE2 levels were elevated in plasma (401 pg/ml, normal 3–12) and urinary (6,086 ng/mmol creatinine, normal < 50). Intriguingly, mutational analysis using genomic DNA that was isolated from the peripheral blood did not detect HPGD mutations.DISCUSSIONMutations in HPGD have been identified in 4 families affected with PHO and in a single family with isolated congenital nail clubbing as an autosomal­recessive trait (4, 5). Impaired metabolism of PGE2 is considered critical in the pathogenesis of PHO. However, in our case, no mutations in HPGD were detected despite the elevated PGE2 levels. These findings suggest that another contributing factor may affect the PGE2 increase. Consistent with our findings, a report exists of a familial case of autosomal­dominant isolated digital clubbing without any mutations in HPGD (6). Furthermore, Seifert et al. (7) found another mutation in PG trans­porter (PGT) encoding gene,

Regulation of COX2 Expression in Mouse Mammary Tumor Cells Controls Bone Metastasis and PGE2-Induction of Regulatory T Cell Migration

BackgroundThe targeting of the immune system through immunotherapies to prevent tumor tolerance and immune suppression are at the front lines of breast cancer treatment and research. Human and laboratory studies have attributed breast cancer progression and metastasis to secondary organs such as the bone, to a number of factors, including elevated levels of prostaglandin E2 (PGE2) and the enzyme responsible for its production, cyclooxygenase 2 (COX2). Due to the strong connection of COX2 with immune function, we focused on understanding how variance in COX2 expression manipulates the immune profile in a syngeneic, and immune-competent, mouse model of breast cancer. Though there have been correlative findings linking elevated levels of COX2 and Tregs in other cancer models, we sought to elucidate the mechanisms by which these immuno-suppressive cells are recruited to breast tumor and the means by which they promote tumor tolerance.Methodology/Principal FindingsTo elucidate the mechanisms by which exacerbated COX2 expression potentiates metastasis we genetically manipulated non-metastatic mammary tumor cells (TM40D) to over-express COX2 (TM40D-COX2). Over-expression of COX2 in this mouse breast cancer model resulted in an increase in bone metastasis (an observation that was ablated following suppression of COX2 expression) in addition to an exacerbated Treg recruitment in the primary tumor. Interestingly, other immune-suppressive leukocytes, such as myeloid derived suppressor cells, were not altered in the primary tumor or the circulation. Elevated levels of PGE2 by tumor cells can directly recruit CD4+CD25+ cells through interactions with their EP2 and/or EP4 receptors, an effect that was blocked using anti-PGE2 antibody. Furthermore, increased Treg recruitment to the primary tumor contributed to the greater levels of apoptotic CD8+ T cells in the TM40D-COX2 tumors.Conclusion/SignificanceDue to the systemic effects of COX2 inhibitors, we propose targeting specific EP receptors as therapeutic interventions to breast cancer progression.

Metabolite Profiles Correlate Closely with Neurobehavioral Function in Experimental Spinal Cord Injury in Rats

Traumatic spinal cord injury (SCI) results in direct physical damage and the generation of local factors contributing to secondary pathogenesis. Untargeted metabolomic profiling was used to uncover metabolic changes and to identify relationships between metabolites and neurobehavioral functions in the spinal cord after injury in rats. In the early metabolic phase, neuronal signaling, stress, and inflammation-associated metabolites were strongly altered. A dynamic inflammatory response consisting of elevated levels of prostaglandin E2 and palmitoyl ethanolamide as well as pro- and anti-inflammatory polyunsaturated fatty acids was observed. N-acetyl-aspartyl-glutamate (NAAG) and N-acetyl-aspartate (NAA) were significantly decreased possibly reflecting neuronal cell death. A second metabolic phase was also seen, consistent with membrane remodeling and antioxidant defense response. These metabolomic changes were consistent with the pathology and progression of SCI. Several metabolites, including NAA, NAAG, and the ω-3 fatty acids docosapentaenoate and docosahexaenoate correlated greatly with the established Basso, Beattie and Bresnahan locomotive score (BBB score). Our findings suggest the possibility of a biochemical basis for BBB score and illustrate that metabolites may correlate with neurobehavior. In particular the NAA level in the spinal cord might provide a meaningful biomarker that could help to determine the degree of injury severity and prognosticate neurologic recovery.

Lipopolysaccharide-Induced Fever Depends on Prostaglandin E2 Production Specifically in Brain Endothelial Cells

Immune-induced prostaglandin E2 (PGE2) synthesis is critical for fever and other centrally elicited disease symptoms. The production of PGE2 depends on cyclooxygenase-2 and microsomal prostaglandin E synthase-1 (mPGES-1), but the identity of the cells involved has been a matter of controversy. We generated mice expressing mPGES-1 either in cells of hematopoietic or nonhematopoietic origin. Mice lacking mPGES-1 in hematopoietic cells displayed an intact febrile response to lipopolysaccharide, associated with elevated levels of PGE2 in the cerebrospinal fluid. In contrast, mice that expressed mPGES-1 only in hematopoietic cells, although displaying elevated PGE2 levels in plasma but not in the cerebrospinal fluid, showed no febrile response to lipopolysaccharide, thus pointing to the critical role of brain-derived PGE2 for fever. Immunohistochemical stainings showed that induced cyclooxygenase-2 expression in the brain exclusively occurred in endothelial cells, and quantitative PCR analysis on brain cells isolated by flow cytometry demonstrated that mPGES-1 is induced in endothelial cells and not in vascular wall macrophages. Similar analysis on liver cells showed induced expression in macrophages and not in endothelial cells, pointing at the distinct role for brain endothelial cells in PGE2 synthesis. These results identify the brain endothelial cells as the PGE2-producing cells critical for immune-induced fever.

Comparison of the bronchodilating effects of inhaled β2-agonists after methacholine challenge in a human lung reperfusion model

The aim of the present investigation was to compare the onset of action and intrinsic activity of the long-acting β2-agonist GW597901 with the fast- and short-acting salbutamol as model compounds using an isolated human lung reperfusion model. Twelve resected human lung lobes were challenged with methacholine (MCh) and subsequently nebulised with either GW597901 or salbutamol. Prostaglandin E2 (PGE2) concentrations in the perfusion fluid were compared with the dose of MCh that was required to induce a bronchoconstriction. After successful MCh provocation, nebulisation of GW597901 and salbutamol fully reversed any observed bronchoconstriction. The bronchodilating effect was more pronounced for GW597901. Salbutamol revealed an immediate onset of action while the effect of GW597901 was observed with an approximate delay of 6min. Higher doses of MCh were required for a successful bronchial challenge in the presence of elevated PGE2 levels (r=0.8171, p⩽0.05). For the first time, an isolated perfused human lung model has been established for comparing the onset of action and potency of a short- and long-acting β2-agonist. We therefore conclude that it is an alternative for determination of drug effect characteristics and suitable for supplementing or predicting clinical data.

The effect of HIV and HPV coinfection on cervical COX-2 expression and systemic prostaglandin E2 levels.

Human immunodeficiency virus (HIV-1) infection causes chronic inflammation. COX-2-derived prostaglandin E(2) (PGE(2)) has been linked to both inflammation and carcinogenesis. We hypothesized that HIV-1 could induce COX-2 in cervical tissue and increase systemic PGE(2) levels and that these alterations could play a role in AIDS-related cervical cancer. Levels of cervical COX-2 mRNA and urinary PGE-M, a biomarker of systemic PGE(2) levels, were determined in 17 HIV-negative women with a negative cervical human papilloma virus (HPV) test, 18 HIV-infected women with a negative HPV test, and 13 HIV-infected women with cervical HPV and high-grade squamous intraepithelial lesions on cytology. Cervical COX-2 levels were significantly associated with HIV and HPV status (P = 0.006 and 0.002, respectively). Median levels of urinary PGE-M were increased in HIV-infected compared with uninfected women (11.2 vs. 6.8 ng/mg creatinine, P = 0.02). Among HIV-infected women, urinary PGE-M levels were positively correlated with plasma HIV-1 RNA levels (P = 0.003). Finally, levels of cervical COX-2 correlated with urinary PGE-M levels (P = 0.005). This study shows that HIV-1 infection is associated with increased cervical COX-2 and elevated systemic PGE(2) levels. Drugs that inhibit the synthesis of PGE(2) may prove useful in reducing the risk of cervical cancer or systemic inflammation in HIV-infected women.

Comparative Study of Normal and Rheumatoid Arthritis Fibroblast-Like Synoviocytes Proliferation under Cyclic Mechanical Stretch: Role of Prostaglandin E2

Fibroblast-like synoviocytes (FLSs) are one of the main contributors of prostaglandin E2 (PGE2) in the hyperplastic synovium of rheumatoid arthritis (RA) patients. cyclooxygenase-2 (COX-2)/PGE2 pathway is involved in the proliferation of several cell types. We have previously shown that mechanical stretch affects COX-2 and PGE2 production in human RA FLSs; however, its role in cell proliferation remains to be elucidated. In this study, a comparison is drawn between human RA and normal FLSs to understand the role of mechanical stretch and PGE2 on the proliferation of FLSs. The results showed that physiological level (6%, 1 Hz) of cyclic mechanical stretch significantly decreased the proliferation of RA FLSs but not normal FLSs, while the induction of apoptosis was not observed by stretch in either RA or normal FLSs. IL-1β (5 ng/ml)-induced COX-2/PGE2 levels are downregulated by stretch in RA FLSs only. Further investigation showed that high concentration (100 and 500 ng/ml) of PGE2 significantly induced cell proliferation only in RA FLSs, and this induction failed to be suppressed by stretch. In conclusion, this study demonstrated that elevated levels of PGE2 in the synovial cavity are involved in the proliferation of RA FLSs, and cyclic mechanical stretch regulates the RA synovial hyperplasia.

Combined histone deacetylase and cyclooxygenase inhibition achieves enhanced antiangiogenic effects in lung cancer cells

Prostaglandin E2 (PGE2) is an important pro-angiogenic and pro-proliferative cytokine and the key enzymes modulating its levels, cyclooxygenase (COX)-2 and 15-hydroxyprostaglandin dehydrogenase (15-PGDH) play important opposing roles in carcinogenesis. Previously we found loss of 15-PGDH expression in lung cancer and its reactivation leads to strong in vivo tumor-suppressive effect via an antiangiogenic mechanism. Here, we find that HDAC inhibitors (HDACI), such as trichostatin A (TSA) and vorinostat could reactivate 15-PGDH expression but overall induce PGE2 generation and this is the result of concomitant induction of COX-1 and -2 leading to functional promotion of endothelial cell proliferation and capillary formation. Direct TSA treatment inhibits endothelial cell proliferation and capillary formation in our study in line with prior reports as HDACIs have been shown to directly inhibit angiogenesis. The elevation of PGE2 levels induced by HDACI is potently neutralized by indomethacin (INN) or Celecoxib co-treatment and accordingly, angiogenesis is more effectively inhibited when using conditioned medium of co-treatment than either alone confirming that this effect is mediated via the PGE2 axis. Accordingly, blockage of EP2/4 receptors mitigates the stimulation of angiogenesis by excessive PGE2 generation mediated by TSA. In this study, we identify a potentially adverse effect of HDACIs through induction of both 15-PGDH and COX-2 leading to elevated PGE2 levels and thereby stimulation of angiogenesis. Co-treatment of TSA and INN shows more potent anti-angiogenic effects by inducing 15-PGDH and inhibiting COX-2. Overall, our results suggest that combined HDACI and COX inhibition should be explored clinically to achieve more meaningful benefits from HDACI therapy in lung cancer.

Mesenchymal stromal cells derived from CD271+ bone marrow mononuclear cells exert potent allosuppressive properties

BACKGROUND AIMS. Because data on the immunosuppressive effect of different subsets of mesenchymal stromal cells (MSC) are sparse, we investigated the molecular and cellular mechanisms underlying the allosuppressive effect of MSC generated from bone marrow CD271(+) cells (CD271-MSC) and asked whether this potential is comparable with that of MSC generated through plastic adherence (PA-MSC). METHODS. The immunosuppressive effect of CD271-MSC on the allogeneic reaction was investigated by mixed lymphocyte reaction (MLR). RESULTS. CD271-MSC significantly suppressed the alloantigen-induced proliferation of mononuclear cells (MNC) of two HLA-disparate donors at all MSC:MNC ratios, 1:1, 1:2 and 1:10. They also demonstrated a significantly higher allosuppression than PA-MSC at an MSC:MNC ratio of 1:1. This inhibitory effect was associated with significantly elevated levels of prostaglandin E2 (PGE2) at ratios of 1:1 and 1:2 (about 4-fold), but not at a ratio of 1:10. Indomethacin, and inhibitor of cyclooxygenase-1 and 2 necessary for the biosynthesis of PGE2, mitigated suppressive effects of CD271-MSC only at a ratio of 1:1, indicating that PGE2 is not involved in MSC-mediated inhibition when allogeneic MNC are in excess. The increase of PGE2 was associated with a significant decrease of pro-inflammatory cytokine levels (interferon-gamma and tumor necrosis-alpha), while no changes in levels of interleukin-10, soluble HLA-G and nitric oxide were observed. In addition, CD271-MSC induced an expansion of highly suppressive naive CD4(+)CD25(high)CD45RA(+)CD62L(+) T-regulatory cells, which may extend their allosuppressive effect. CONCLUSIONS. Our data suggest that CD271-MSC exert potent allosuppressive properties and therefore can be used as a reasonable alternative to PA-MSC for the treatment of patients with graft-versus-host disease.