High Concentrations Of Prostaglandin E2 Research Articles

Prostaglandin E2 Signaling Mediates Oenocytoid Immune Cell Function and Lysis, Limiting Bacteria and Plasmodium Oocyst Survival in Anopheles gambiae

Lipid-derived signaling molecules known as eicosanoids have integral roles in mediating immune and inflammatory processes across metazoans. This includes the function of prostaglandins and their cognate G protein-coupled receptors (GPCRs) to employ their immunological actions. In insects, prostaglandins have been implicated in the regulation of both cellular and humoral immune responses, yet in arthropods of medical importance, studies have been limited. Here, we describe a prostaglandin E2 receptor (AgPGE2R) in the mosquito Anopheles gambiae and demonstrate that its expression is most abundant in oenocytoid immune cell populations. Through the administration of prostaglandin E2 (PGE2) and AgPGE2R-silencing, we demonstrate that prostaglandin E2 signaling regulates a subset of prophenoloxidases (PPOs) and antimicrobial peptides (AMPs) that are strongly expressed in populations of oenocytoids. We demonstrate that PGE2 signaling via the AgPGE2R significantly limits both bacterial replication and Plasmodium oocyst survival. Additional experiments establish that PGE2 treatment increases phenoloxidase (PO) activity through the increased expression of PPO1 and PPO3, genes essential to anti-Plasmodium immune responses that promote oocyst killing. We also provide evidence that the mechanisms of PGE2 signaling are concentration-dependent, where high concentrations of PGE2 promote oenocytoid lysis, negating the protective effects of lower concentrations of PGE2 on anti-Plasmodium immunity. Taken together, our results provide new insights into the role of PGE2 signaling on immune cell function and its contributions to mosquito innate immunity that promote pathogen killing.

Tick saliva-induced programmed death-1 and PD-ligand 1 and its related host immunosuppression

The tick Rhipicephalus microplus is a harmful parasite of cattle that causes considerable economic losses to the cattle breeding industry. Although R. microplus saliva (Rm-saliva) contains several immunosuppressants, any association between Rm-saliva and the expression of immunoinhibitory molecules, such as programmed death (PD)-1 and PD-ligand 1 (PD-L1), has not been described. In this study, flow cytometric analyses revealed that Rm-saliva upregulated PD-1 expression in T cells and PD-L1 expression in CD14+ and CD11c+ cells in cattle. Additionally, Rm-saliva decreased CD69 expression in T cells and Th1 cytokine production from peripheral blood mononuclear cells. Furthermore, PD-L1 blockade increased IFN-γ production in the presence of Rm-saliva, suggesting that Rm-saliva suppresses Th1 responses via the PD-1/PD-L1 pathway. To reveal the upregulation mechanism of PD-1/PD-L1 by Rm-saliva, we analyzed the function of prostaglandin E2 (PGE2), which is known as an inducer of PD-L1 expression, in Rm-saliva. We found that Rm-saliva contained a high concentration of PGE2, and PGE2 treatment induced PD-L1 expression in CD14+ cells in vitro. Immunohistochemical analyses revealed that PGE2 and PD-L1 expression was upregulated in tick-attached skin in cattle. These data suggest that PGE2 in Rm-saliva has the potential to induce the expression of immunoinhibitory molecules in host immune cells.

ProstaglandinE2 serves a dual role in regulating the migration of dendritic cells.

Dendritic cells (DCs) are the most potent antigen-presenting cells, and are indispensable in the immune system. Prostaglandin E2 (PGE2) has been demonstrated to modulate the migration of DCs, but with inconsistent results. The present study, based on our previous research, used murine bone marrow-derived DCs to elucidate the potential regulatory mechanism of PGE2 on the migration of DCs. The results indicated that PGE2 served a dual role in regulating the migration of DCs in a dose-dependent manner. High concentrations of PGE2 inhibited cell migration, whereas low concentrations exhibited the opposite effect. Flow cytometry revealed that the expression of CC chemokine receptor type 7 on the DC surface was increased following treatment with low concentrations of PGE2 and slightly decreased by high concentrations of PGE2. The effect of PGE2 was indicated to be exerted via reorganizing the F-actin cytoskeleton using confocal micros-copy. Moreover, the regulatory effect of PGE2 on the migration of DCs was validated in vivo. Subsequent gene expression profile analyses using RNA-sequencing technology indicated that PGE2 induced alterations in the expression of multiple downstream genes and signaling pathway molecules associated with cell migration and the cytoskeleton. These findings may provide an improved understanding on the mechanism of DC migration under both pathological and physiological conditions. Moreover, the biological implications of these findings may provide a novel perspective of the immunological surveillance in the progression of different types of diseases.

Placenta-derived multipotent mesenchymal stromal cells: a promising potential cell-based therapy for canine inflammatory brain disease

BackgroundCanine inflammatory brain disease (IBD) is a severe inflammatory disorder characterized by infiltration of activated immune cell subsets into the brain and spinal cord. Multipotent mesenchymal stromal cells (MSCs) are a promising therapy for IBD, based on their potent pro-angiogenic, neuroprotective, and immunomodulatory properties. The aims of this study were to compare the immunomodulatory attributes of canine adipose-derived MSCs (ASCs) and placenta-derived MSCs (PMSCs) in vitro. These data will serve as potency information to help inform the optimal MSC cell source to treat naturally occurring canine IBD.MethodsIndoleamine 2,3 dioxygenase (IDO) activity and prostaglandin E2 (PGE2) concentration at baseline and after stimulation with interferon gamma (IFNγ) and/or tumor necrosis factor alpha (TNFα) were measured from canine ASC and PMSC cultures. Leukocyte suppression assays (LSAs) were performed to compare the ability of ASCs and PMSCs to inhibit activated peripheral blood mononuclear cell (PBMC) proliferation. IDO activity and PGE2; interleukin (IL)-2, IL-6, and IL-8; TNFα; and vascular endothelial growth factor (VEGF) concentrations were also measured from co-culture supernatants. Cell cycle analysis was performed to determine how ASCs and PMSCs altered lymphocyte proliferation.ResultsActivated canine MSCs from both tissue sources secreted high concentrations of IDO and PGE2, after direct stimulation with IFNγ and TNFα, or indirect stimulation by activated PBMCs. Both ASCs and PMSCs inhibited activated PBMC proliferation in LSA assays; however, PMSCs inhibited PBMC proliferation significantly more than ASCs. Blocking PGE2 and IDO in LSA assays determined that PGE2 is important only for ASC inhibition of PBMC proliferation. Activated ASCs increased IL-6 and VEGF secretion and decreased TNFα secretion, while activated PMSCs increased IL-6, IL-8, and VEGF secretion. ASCs inhibited lymphocyte proliferation via cell cycle arrest in the G0/G1 and PMSCs inhibited lymphocyte proliferation via induction of lymphocyte apoptosis.ConclusionOur results demonstrate that ASCs and PMSCs have substantial in vitro potential as a cell-based therapy for IBD; however, PMSCs more potently inhibited lymphocyte proliferation by inducing apoptosis of activated lymphocytes. These data suggest that the mechanism by which ASCs and PMSCs downregulate PBMC proliferation differs. Additional studies may elucidate additional mechanisms by which canine MSCs modulate neuroinflammatory responses.

E6‑regulated overproduction of prostaglandinE2 may inhibit migration of dendritic cells in human papillomavirus 16‑positive cervical lesions.

Continuous human papillomavirus (HPV) infection is a critical cause of cervical lesions; however, the specific mechanism is currently not clear. E6 is one of the most important oncoproteins associated with HPV, which regulates synthases in the production of prostaglandin E2 (PGE2). Notably, PGE2 has been reported to be upregulated in cervical lesions. An insufficient number of mature dendritic cells (DCs), which is unable to cause an effective immune response, is an important cause of cervical lesions. Therefore, this study explored the possible causes of HPV16-positive cervical lesions by identifying the relationship between E6, PGE2 and DCs. Firstly, the distribution and status of DCs in clinical biopsy specimens and animal models were analyzed with immuno-histochemistry and flow cytometry, which demonstrated that the migratory ability of DCs was inhibited in HPV16-positive cervical lesions. Furthermore, using immunohistochemistry, western blotting and ELISA, it was revealed that as the degree of cervical lesions increased, the expression of PGE2 and its synthases increased. Subsequently, as determined using Transwell and 3D migration assays, it was revealed that a high concentration of PGE2 inhibited the migration of DCs, which may explain the phenomenon observed in cervical lesions. Notably, E6 was identified to regulate PGE2 expression. The in vivo experiments indicated that E6 may increase the expression levels of PGE2 in cervical lesions, which could eventually induce inhibition of the migration of DCs. In conclusion, the present study suggested that E6 regulated overproduction of PGE2, which may induce inhibition of DC migration in HPV16-positive cervical lesions.

Inhibition of viral and bacterial trigger-stimulated prostaglandin E2 by a throat lozenge containing flurbiprofen: An in vitro study using a human respiratory epithelial cell line.

Objectives:Symptoms of sore throat result from oropharyngeal inflammation, for which prostaglandin E2 is a key mediator. Flurbiprofen is a non-steroidal anti-inflammatory that provides sore throat relief. The preliminary objective of this study was to develop an in vitro model for assessing prostaglandin E2 stimulation by viral and bacterial triggers. The primary objective was to investigate the effect of diluted flurbiprofen-containing lozenges on prostaglandin E2 concentrations in stimulated cells.Methods:Prostaglandin E2 production was stimulated in three epithelial cell lines (A549, HEp2, and clonetics bronchial/tracheal epithelial) with influenza A virus (4.5 log10 tissue culture infectious dose50/mL), or bacterial lipopolysaccharide (10µ g/mL) and peptidoglycan (3µ g/mL) and incubated overnight. Prostaglandin E2 levels were assessed by enzyme-linked immunosorbent assay up to 24 h after stimulation. The effect of flurbiprofen 8.75 mg lozenges (diluted to 0.44 mg/mL) on PGE2 production in stimulated cells was assessed in parallel; prior to viral/LPS/PEP stimulation of cells, 300 μL of test product or control was added and incubated for 30 s, 2 and 5 min (and 10 min for bacterial trigger). Prostaglandin E2 levels were measured following stimulation.Results:Viral and lipopolysaccharide/peptidoglycan infection did not consistently stimulate HEp2 cells and bronchial/tracheal epithelial cells to produce prostaglandin E2. Influenza virus, and lipopolysaccharide/peptidoglycan stimulated high prostaglandin E2 concentrations in A549: mean prostaglandin E2 concentration 106.48 pg/mL with viral stimulation vs 33.82 pg/mL for uninfected cells; 83.84 pg/mL with lipopolysaccharide/peptidoglycan vs 71.96 pg/mL for uninfected cells. Flurbiprofen produced significant reductions in virus-stimulated prostaglandin E2 vs stimulated untreated cells at 2 min (p = 0.03). Flurbiprofen produced significant reductions in lipopolysaccharide/peptidoglycan-stimulated prostaglandin E2 concentrations from 30 s (p = 0.02), and at 2, 5 and 10 min (all p < 0.005) vs stimulated untreated cells.Conclusions:A549 cells provide a suitable model for assessment of prostaglandin E2 stimulation by viral and bacterial triggers. Diluted flurbiprofen-containing lozenges demonstrated rapid anti-inflammatory activity in viral- and lipopolysaccharide/peptidoglycan-stimulated A549 cells.

The Role of Prostaglandin E2 on Osteoblast Proliferation Induced by Hydroxyapatite

Objective: Prostaglandin E2 (PGE2) plays a crucial role in regulating bone cell differentiation and proliferation. The aim of the present study was to determine whether PGE2 may regulate osteoblast proliferation induced by hydroxyapatite. Materials and Methods: Osteoblasts (HOS cell line) pre-treated with cyclooxygenase (COX) inhibitors (indomethacin, aspirin and nimesulide) were then cultured. The cells were also pre-treated with or without nimesulide and then cultured with PGE2. The cell cultures were also treated with SQ22536 (adenylyl cyclase inhibitor) and added with Db-cAMP (cAMP analog), and/or PGE2. KT5720 [protein kinase A (PKA) inhibitor.], Db-cAMP and/or forskolin (adenylyl cyclase activator)-treated cultures were used to assess the role of PKA. The role of EP2 and/or EP4 was determined by using EP2 antagonist (PF-04418948) and EP4 antagonist (L-161,982) with PGE2. All cells were cultured with or without hydroxyapatite. The levels of PGE2 and cAMP were detected from the culture supernantants and the cell proliferation was assessed colorimetrically. Results: Nimesulide and indomethacin but not aspirin suppressed partially the cell proliferation but fully PGE2 production. PGE2 abrogated nimesulide-mediated suppression of cell proliferation. The cell proliferation was enhanced by low but suppressed by high concentration of PGE2. Moreover, the SQ22536-mediated suppression of cell proliferation was abolished by Db-cAMP but not PGE2. Conversely, PGE2, Db-cAMP or forskolin failed to eliminate KT5720-mediated suppression of cell proliferation. The effect of PGE2 on cell proliferation and cAMP levels was mediated predominantly via EP2 and to a lesser extent, EP4. The results of the controls for all experiments were significantly lower than hydroxyapatite-stimulated cell cultures. Conclusion: These results suggest thatPGE2, acting via a COX-2-, cAMP-PKA- and both EP2 and EP4-dependent pathway may partially regulate hydroxyapatite-induced human osteoblasts in an autocrine fashion.

Suppression of aspirin-mediated eosinophil activation by prostaglandin E2: Relevance to aspirin and nonsteroidal anti-inflammatory drug hypersensitivity

BackgroundAspirin-exacerbated respiratory disease (AERD) is characterized by severe, sometimes life-threatening reactions to nonsteroidal anti-inflammatory drugs (NSAIDs). Mechanisms driving the disease include overproduction of leukotrienes and loss of anti-inflammatory prostaglandin E2 (PGE2) production. Many cell types contribute to the disease; however, eosinophils are markedly elevated and are important drivers of pathologic findings. ObjectiveTo investigate the capacity of aspirin and NSAIDs to drive eosinophil activation and the ability of PGE2 to inhibit this activation. MethodsEosinophils were purified from blood of healthy individuals without AERD and stimulated with lysine aspirin, ketorolac, or sodium salicylate. The role of PGE2 in altering activation was determined by incubating eosinophils with increasing doses of PGE2 before lysine aspirin stimulation. Specific PGE2 receptor use was determined by incubating eosinophils with receptor agonists and antagonists before aspirin stimulation. Cysteinyl leukotrienes (CysLTs), leukotriene B4 (LTB4), and eosinophil-derived neurotoxin (EDN) were quantified by enzyme-linked immunosorbent assay. ResultsStimulation of eosinophils with lysine aspirin, ketorolac, or sodium salicylate resulted in secretion of CysLTs and LTB4 in the absence of EDN release. Low doses of PGE2 inhibited LTB4 and CysLT release, an effect lost at higher PGE2 concentrations. Use of butaprost, an EP2 receptor agonist, suppressed lysine aspirin stimulation. This mechanism was supported by blocking activity of the EP1 and EP3 receptors. ConclusionEosinophils can be directly activated by NSAIDs via cyclooxygenase-independent pathways to produce CysLTs and LTB4. This effect can be inhibited by PGE2 acting through the EP2 receptor. The recognized loss of EP2 receptor expression combined with low PGE2 levels explains in part the sensitivity to NSAIDs.

Prostaglandin E2 triggers cytochrome P450 17α hydroxylase overexpression via signal transducer and activator of transcription 3 phosphorylation and promotes invasion in endometrial cancer.

Prostaglandin E2 (PGE2) is the most common prostaglandin in the human body, meaning that its malfunction impacts on the development of numerous diseases. Prostaglandin E synthase 2 (PTGES2) is involved in the synthesis of PGE2. In the present study, immunohistochemistry of PTGES2 was performed in 152 patients with endometrial cancer and in 66 patients with normal endometria. The results indicate a notable association among increased expression of PTGES2 and age (P=0.0092) and the depth of myometrial invasion (P<0.0001). Reverse transcription-quantitative polymerase chain reaction and western blot analysis demonstrated that cytochrome P450 17α hydroxylase (CYP17), an enzyme for androgen synthesis, is overexpressed following PGE2 stimulation via signal transducer and activator of transcription 3 (STAT3) phosphorylation. ELISA also detected increased androgen (testosterone) secretion. Further invasion of endometrial cancer cells was induced at high androgen levels and when CYP17 was overexpressed. Furthermore, the present study observed that CYP17 is overexpressed via STAT3 phosphorylation in endometrial cancer cells, which grow at a high concentration of PGE2, resulting in increased androgen secretion. Concentrations of estrogen and progesterone were not elevated, while the concentration of androgens was. Overall, a high concentration of androgens caused increased invasion of endometrial cancer cells. A high concentration of androgens, which is initiated by a high expression of PTGES2 and a high concentration of PGE2, is an important promoter of myometrial invasion in endometrial cancer.

Prostaglandin E2 Antagonizes TGF-β Actions During the Differentiation of Monocytes Into Dendritic Cells.

Inflammatory dendritic cells (DCs) are a distinct subset of DCs that derive from circulating monocytes infiltrating injured tissues. Monocytes can differentiate into DCs with different functional signatures, depending on the presence of environment stimuli. Among these stimuli, transforming growth factor-beta (TGF-β) and prostaglandin E2 (PGE2) have been shown to modulate the differentiation of monocytes into DCs with different phenotypes and functional profiles. In fact, both mediators lead to contrasting outcomes regarding the production of inflammatory and anti-inflammatory cytokines. Previously, we have shown that human semen, which contains high concentrations of PGE2, promoted the differentiation of DCs into a tolerogenic profile through a mechanism dependent on signaling by E-prostanoid receptors 2 and 4. Notably, this effect was induced despite the huge concentration of TGF-β present in semen, suggesting that PGE2 overrides the influence exerted by TGF-β. No previous studies have analyzed the joint actions induced by PGE2 and TGF-β on the function of monocytes or DCs. Here, we analyzed the phenotype and functional profile of monocyte-derived DCs differentiated in the presence of TGF-β and PGE2. DC differentiation guided by TGF-β alone enhanced the expression of CD1a and abrogated LPS-induced expression of IL-10, while differentiation in the presence of PGE2 impaired CD1a expression, preserved CD14 expression, abrogated IL-12 and IL-23 production, stimulated IL-10 production, and promoted the expansion of FoxP3+ regulatory T cells in a mixed lymphocyte reaction. Interestingly, DCs differentiated in the presence of TGF-β and PGE2 showed a phenotype and functional profile closely resembling those induced by PGE2 alone. Finally, we found that PGE2 inhibited TGF-β signaling through an action exerted by EP2 and EP4 receptors coupled to cyclic AMP increase and protein kinase A activity. These results indicate that PGE2 suppresses the influence exerted by TGF-β during DC differentiation, imprinting a tolerogenic signature. High concentrations of TGF-β and PGE2 are usually found in infectious, autoimmune, and neoplastic diseases. Our observations suggest that in these scenarios PGE2 might play a mandatory role in the acquisition of a regulatory profile by DCs.

Amniotic fluid prostaglandin E2 in pregnancies complicated by preterm prelabor rupture of the membranes

Objective: To determine amniotic fluid prostaglandin E2 concentrations in women preterm prelabor rupture of the membranes (PPROM) with respect to microbial invasion of the amniotic cavity (MIAC), intraamniotic inflammation (IAI), microbial-associated IAI, histological chorioamnionitis, and short-term neonatal morbidity.Methods: One hundred forty-five women with singleton pregnancies were included in this study. Amniotic fluid samples were obtained by transabdominal amniocentesis and were assayed for prostaglandin E2 concentrations by ELISA. IAI was defined as amniotic fluid interleukin-6 >745 pg/mL. Microbial-associated IAI was defined as the presence of both MIAC and IAI.Result: No differences in prostaglandin E2 concentrations were found between women with and without MIAC (p = 0.27). Women with IAI (p = 0.0008) and microbial-associated IAI (p = 0.01) had higher prostaglandin E2 concentrations than women without these complications. Women with histological chorioamnionitis had higher prostaglandin E2 concentrations only in crude analysis (p = 0.02), but not after adjustment for gestational age at sampling (p = 0.10). No associations between amniotic fluid prostaglandin E2 concentrations and the selected conditions of severe neonatal morbidity were found.Conclusions: The intraamniotic inflammatory response either to infectious or to non-infectious stimulus, but not MIAC per se, seems to be a main factor associated with the elevation of the amniotic fluid PGE2 concentrations in women with PPROM.

Prostaglandin E-mediated molecular mechanisms driving remodeling of the ductus arteriosus.

The ductus arteriosus (DA), a fetal arterial connection between the pulmonary arteries and aorta, normally closes after birth. Persistent DA patency usually has life-threatening consequences. In certain DA-dependent congenital heart diseases, however, patient survival depends on maintaining DA patency. Complete closure of the DA involves both functional closure, induced by muscle contraction, and anatomical closure, achieved through morphological and molecular remodeling. Anatomical closure of the DA is associated with the formation of intimal thickening, which is characterized by deposition of extracellular matrix in the subendothelial region, sparse elastic fiber formation, and migration of medial smooth muscle cells into the subendothelial space. In addition, fetal molecular remodeling that is suitable for postnatal muscle contraction has been observed in the DA. After the second trimester, high concentration of prostaglandin E2 (PGE2) causes the DA to dilate through the remainder of the fetal period. Emerging evidence from studies using pharmacological approaches and genetically modified mice suggests that, in addition to its vasodilatory effect, this chronic exposure to PGE2 promotes DA-specific anatomical and molecular remodeling through EP4, one of four receptor subtypes for PGE2. Signals that are downstream of PGE2-EP4, such as cyclic AMP (cAMP)-protein kinase A (PKA), exchange protein activated by cAMP (Epac), phospholipase C, and Wnt/β-catenin, may be involved in the regulation of intimal thickening, elastogenesis, and contraction-related genes. Understanding the physiological role of PGE2 in DA remodeling could enable more effective regulation of PDA, both in isolation and in the context of congenital cardiac anomalies.

In vitro effects of prostaglandin E2 on leucocytes from sticklebacks (Gasterosteus aculeatus) infected and not infected with the cestode Schistocephalus solidus

Many helminth parasites have evolved strategies to evade the immune response of their hosts, which includes immunomodulation. Prostaglandin E2 (PGE2) is one of the best-described immunomodulators in mammalian helminth parasite infections. We hypothesized that also in teleost fish anti-helminthic immune responses are regulated via PGE2. We used a model system consisting of the tapeworm Schistocephalus solidus and its host, the three-spined stickleback (Gasterosteus aculeatus), to investigate in vitro effects of PGE2 on head kidney leucocytes (HKL) derived from sticklebacks that were experimentally infected with S. solidus. PGE2 was tested alone or in combination with either S. solidus antigens or bacterial lipopolysaccharides (LPS). After in vitro culture, cell viability and changes in leucocyte subpopulations (granulocytes to lymphocytes ratios) were monitored by flow cytometry and HKL were tested for their capacity to produce reactive oxygen species (ROS) with a chemiluminescence assay. In short term (2 h) HKL cultures PGE2 did not change the total numbers of live HKL, but the production of ROS decreased significantly with high (0.1 μmol L−1) PGE2 concentrations. In long-term (96 h) cultures high PGE2 concentrations induced a sharp decrease of leucocytes viability, while low (0.1 pmol L−1) and intermediate (0.1 nmol L−1) concentrations of PGE2 caused elevated leucocyte viability compared to controls. This coincided with reduced ROS production in cultures with high PGE2 and elevated ROS production in cultures with low PGE2. Granulocyte to lymphocyte ratios increased with high PGE2 concentrations alone and in combination with S. solidus antigens and LPS, most prominently with HKL from S. solidus infected sticklebacks. The present study supports the hypothesis that PGE2 might be an immunomodulator in tapeworm–fish parasite–host interactions.

Prostaglandin E2 (PGE2) Exerts Biphasic Effects on Human Tendon Stem Cells

Prostaglandin E2 (PGE2) has been reported to exert different effects on tissues at low and high levels. In the present study, cell culture experiments were performed to determine the potential biphasic effects of PGE2 on human tendon stem/progenitor cells (hTSCs). After treatment with PGE2, hTSC proliferation, stemness, and differentiation were analyzed. We found that high concentrations of PGE2 (>1 ng/ml) decreased cell proliferation and induced non-tenocyte differentiation. However, at lower concentrations (<1 ng/ml), PGE2 markedly enhanced hTSC proliferation. The expression levels of stem cell marker genes, specifically SSEA-4 and Stro-1, were more extensive in hTSCs treated with low concentrations of PGE2 than in cells treated with high levels of PGE2. Moreover, high levels of PGE2 induced hTSCs to differentiate aberrantly into non-tenocytes, which was evident by the high levels of PPARγ, collagen type II, and osteocalcin expression in hTSCs treated with PGE2 at concentrations >1 ng/ml. The findings of this study reveal that PGE2 can exhibit biphasic effects on hTSCs, indicating that while high PGE2 concentrations may be detrimental to tendons, low levels of PGE2 may play a vital role in the maintenance of tendon homeostasis in vivo.

Serum concentrations of eicosanoids and lipids in dogs naturally infected with Babesia canis

Canine babesiosis is a tick-borne disease with world-wide significance caused by intraerythrocytic protozoa of the genus Babesia. The eicosanoids, as inflammatory mediators, are involved in the regulation of the immune response and inflammatory reaction. Metabolism of lipids is of great importance in babesiosis. In this study it was aimed to investigate the dynamics of serum concentration of prostaglandin E2 (PGE2), thromboxane B2 (TxB2), leukotriene B4 (LTB4), triglycerides, total cholesterol (Chol), HDL- and LDL-cholesterol in dogs naturally infected with Babesia canis and healthy dogs. Both groups were measured for all parameters on the admission day and on the first, second and seventh day of the disease. Dogs that were included in this study had systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS). It was demonstrated that the level of LTB4, PGE2, TxB2 in dogs naturally infected with B. canis significantly changed during the disease. The level of LTB4 was significantly higher during the study, while the concentration of PGE2 was significantly higher second, third and seventh day of disease in relation with healthy dogs. The level of TxB2 was significantly lower at the beginning of the disease, but after seven days concentration was significantly higher. Both group of patients with SIRS and MODS had significantly higher level of LTB4. Substained high concentrations of PGE2 were observed in dogs with MODS after therapy but not in dogs with SIRS, and LTB4 followed a similar tendency. On the other hand, increases in TxB2 were only significant in dogs with SIRS. The lipid profile in naturally infected dogs with B. canis infection was significantly changed. Further studies are needed to assess the prognostic values of lipid mediators in dogs with B. canis infection, and the ability of these markers to predict the progress of SIRS and MODS.

Prostaglandin E2 in tick saliva regulates macrophage cell migration and cytokine profile

BackgroundTicks are obligate hematophagous ectoparasites that suppress the host’s immune and inflammatory responses by secreting immuno-modulatory and anti-inflammatory molecules in their saliva. In previous studies we have shown that tick salivary gland extract (SGE) and saliva from Dermacentor variabilis have distinct effects on platelet-derived growth factor (PDGF)-stimulated IC-21 macrophage and NIH3T3-L1 fibroblast migration. Since tick saliva contains a high concentration of prostaglandin E2 (PGE2), a potent modulator of inflammation, we used a PGE2 receptor antagonist to evaluate the role of PGE2 in the different migratory responses induced by saliva and its impact on macrophage cytokine profile.MethodsAdult ticks were fed on female New Zealand white rabbits for 5-8 days. Female ticks were stimulated with dopamine/theophylline to induce salivation and saliva was pooled. Competitive enzyme immunoassays (EIA) were used to measure saliva PGE2 content and the changes in macrophage intracellular cyclic adenosine monophosphate (cAMP) levels. The effects of tick saliva on macrophage and fibroblast migration were assessed in the absence and presence of the PGE2 receptor antagonist, AH 6809, using blind well chamber assays. A cytokine antibody array was used to examine the effects of tick saliva on macrophage cytokine secretion. Statistical significance was determined by one-way ANOVA; Student Newman-Kuels post-test was used for multiple comparisons.ResultsThe saliva-induced increase in PDGF-stimulated macrophage migration was reversed by AH 6809. The inhibition of PDGF-stimulated fibroblast migration by saliva was also antagonist-sensitive. Tick saliva induced macrophages to secrete copious amounts of PGE2, and conditioned medium from these cells caused an AH 6809-sensitive inhibition of stimulated fibroblast migration, showing that macrophages can regulate fibroblast activity. We show that tick saliva decreased the secretion of the pro-inflammatory cytokines regulated and normal T cell expressed and secreted (RANTES/CCL5), tumor necrosis factor-alpha (TNF-α), and soluble TNF receptor I (sTNFRI) through a PGE2-dependent mechanism mediated by cAMP. Saliva had similar effects on lipopolysaccharide (LPS) stimulated macrophages.ConclusionsOur data show that ticks utilize salivary PGE2 to subvert the ability of macrophages to secrete pro-inflammatory mediators and recruit fibroblasts to the feeding lesion, therefore inhibiting wound healing.

Prostaglandin E2 in tick saliva regulates host cell migration and cytokine profile

Ticks are obligate ectoparasites that suppress the host's responses by secreting immunomodulatory and anti‐inflammatory molecules in their saliva. Previously, we have shown that tick salivary constituents from Dermacentor variabilis have distinctive effects on macrophage and fibroblast migration. Since tick saliva contains a high concentration of prostaglandin E2 (PGE2), we examined the effects of tick saliva on IC‐21 macrophage and NIH3T3‐L1 fibroblast migration in the absence and presence of a PGE2 antagonist. Assessment of macrophage and fibroblast migration showed the saliva‐induced changes in migration are reversed by the receptor antagonist AH 6809. Tick saliva induces macrophages to secrete copious amounts of PGE2, and conditioned medium from these cells caused a PGE2 antagonist‐sensitive inhibition on fibroblast migration. Using a cytokine antibody array, we showed tick saliva decreases the secretion of the pro‐inflammatory cytokines regulated and normal T cell expressed and secreted (RANTES/CCL5), tumor necrosis factor‐alpha (TNF‐α), and soluble TNF Receptor I (sTNFRI), through a PGE2‐dependent mechanism mediated by cyclic adenosine monophosphate (cAMP). Saliva also had similar effects on lipopolysaccharide (LPS) stimulated macrophages. Our data indicate ticks use PGE2 to regulate the acitivities of macrophages and fibroblast, cells important in the wound healing response.

Immunohistochemical Demonstration of Cyclooxygenase-2 in Glomus Tumors

Glomus tumors are benign hamartomas that account for 1% to 5% of all soft-tissue tumors of the hand. Painful spasms radiating from the lesion are typical clinical signs. As the pain production mechanism is unclear, we evaluated S100 protein, substance P, and cyclooxygenase-2 expression by immunohistochemistry in glomus tumor samples. Eight solitary glomus tumors were surgically excised and confirmed histologically by an experienced pathologist. Paraffin-embedded tissues were prepared for immunohistochemistry. The sections were stained with separate polyclonal antibodies for S100, substance P, and cyclooxygenase-2. In three of the tumors, we measured the prostaglandin E2 concentrations. All samples were positive for S100 protein and cyclooxygenase-2.Substance P was found in five of the eight samples. High prostaglandin-E2 concentrations were seen in all three samples tested. Cyclooxygenase-2-immunoreactive cells are present in solitary glomus tumors. Since cyclooxygenase-2 produces prostaglandin E2, which is thought to be a strong vasodilator, the pain could be caused by vasodilation in the glomus tumor, with increased intracapsular pressure.

A Case Report of Oseoid Osteoma in the Ulnar Cortex of the Distarl Radius Extending into the Distal Radioulnal Joint&amp;lt;br&amp;gt;—COX-2 Produced Prostaglandin E2 Possible Case of the Symptoms&amp;lt;br&amp;gt;

An 18-year-old girl presented with an osteoid osteoma in the ulnar side of the cortex of the distal radius extending into the distal radioulnar joint. The osteoid osteoma was removed from the distal radius at surgery. The patient’s symptoms were dramatically improved the day after surgery. A high concentration of prostaglandin E2 (PGE2) was seen in the joint and surrounding soft tissues, and cyclooxygenase-2 (COX-2) receptors were stained in the joint capsule and synovium inside the joint. This case report is the first to describe the concentration of PGE2 and stained COX-2 receptors in an osteoid osteoma in the ulnar cortex of the distal radius extending into the distal radioulnar joint.

Prostaglandin E2Increases Both Osteoblastic and Osteoclastic Activity in the Scales and Participates in Calcium Metabolism in Goldfish

Using our original in vitro assay system with goldfish scales, we examined the direct effect of prostaglandin E₂ (PGE₂) on osteoclasts and osteoblasts in teleosts. In this assay system, we measured the activity of alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP) as respective indicators of each activity in osteoblasts and osteoclasts. ALP activity in scales significantly increased following treatment at high concentration of PGE₂(10⁻⁷ and 10⁻⁶ M) over 6 hrs of incubation. At 18 hrs of incubation, ALP activity also significantly increased in the PGE₂ (10⁻⁹ to 10⁻⁶ M)-treated scale. In the case of osteoclasts, TRAP activity tended to increase at 6 hrs of incubation, and then significantly increased at 18 hrs of incubation by PGE₂ (10(-7) to 10⁻⁶ M) treatment. At 18 hrs of incubation, the mRNA expression of osteoclastic markers (TRAP and cathepsin K) and receptor activator of the NF-κB ligand (RANKL), an activating factor of osteoclasts expressed in osteoblasts, increased in PGE₂ treated-scales. Thus, PGE₂ acts on osteoblasts, and then increases the osteoclastic activity in the scales of goldfish as it does in the bone of mammals. In an in vivo experiment, plasma calcium levels and scale TRAP and ALP activities in the PGE₂-injencted goldfish increased significantly. We conclude that, in teleosts, PGE₂ activates both osteoblasts and osteoclasts and participates in calcium metabolism.