PGE2 Inhibition Research Articles

A series of indole-derived γ-hydroxy propiolate esters as potent anti-inflammatory agents: Design, synthesis, in-vitro and in-vivo biological studies

A variety of novel indole-derived γ-hydroxy propiolate esters were designed, synthesized, and evaluated for their anti-inflammatory activity in-vitro and in-vivo. According to the nitric oxide (NO) inhibitory analysis, all compounds showed potent NO inhibitory ability in a dose-dependent manner, with no apparent cytotoxicity. The model compound, L-37, also exhibited significant potency in PGE2 inhibition. In addition, compounds L-37 and L-39 can downregulate the expression of COX-2 enzyme at 5 μM via ELISA experiment. Compound L-37 (1 μM) also inhibited the PGF1 production as well as the expression of COX-1, but displayed weak inhibition activity towards the Leukotrienes (LT) and Thromboxane-B2 (TXB-2) production. However, the expression of 5-LOX was significantly inhibited by compound L-39 at 5 μM. Xylene-induced ear edema model was explored for in-vivo anti-inflammatory evaluation, compound L-37 showed similar inhibitory activity compared with celecoxib, approximately 80% at 50 mg/kg dosage. Every outcome showed that the newly synthesized compounds can effectively inhibit inflammation.

Interactions between aspirin and ticagrelor during experimental human endotoxaemia

Abstract Introduction Dual antiplatelet therapy (DAPT) with aspirin 75-100mg once daily (OD) and the P2Y12 inhibitor ticagrelor is a standard treatment for acute coronary syndromes. De-escalating DAPT to ticagrelor monotherapy reduces bleeding risk yet appears to have minimal ischaemic penalty in most groups. The reason for this is unclear. P2Y12 inhibition can inhibit inflammatory processes relevant to atherothrombosis but aspirin may hypothetically counter these via platelet PGE2 inhibition. We studied the regimen-dependent effects of aspirin +/- ticagrelor in a human model of endotoxaemia. Endotoxin activates toll-like receptor 4, a key damage receptor in atherogenesis. Methods 72 healthy volunteers were randomised to receive either no aspirin or aspirin 20mg twice daily (BD), 75mg OD or 300mg OD for 10 days +/- a loading dose of ticagrelor on the last day prior to receiving intravenous endotoxin administration (2ng/kg). Blood was collected at 9 timepoints from 1h pre to 6h post endotoxin. Key cytokines and prostanoids in the blood/urine were measured by ELISA, platelet function by light transmittance aggregometry and platelet-leukocyte interaction by flow cytometry. Bleeding time was measured pre and 3h post endotoxin. After >5 weeks, in a 2nd period they received the same dose of aspirin as the 1st but received ticagrelor if they had not already, and vice versa, undergoing a 2nd endotoxin challenge at the end of the period. The primary endpoint was plasma tumour necrosis factor (TNF)-α. Results 72 participants were randomised (median 22.5yrs [range 18-59], 6F:66M). A total of 128 endotoxin challenges were performed. Endotoxaemia was associated with flu-like symptoms, pyrexia, tachycardia and relative hypotension but was safe. In those not receiving aspirin, plasma TNF-α was significantly lower when receiving ticagrelor vs. no ticagrelor, but in those receiving any dose of aspirin the significant effect of ticagrelor was abolished (Fig 1). All doses of aspirin fully suppressed arachidonic acid-induced PA with or without ticagrelor despite the thromboinflammatory stimulus of endotoxaemia (Fig 2A), and significantly augmented the inhibitory effect of ticagrelor on collagen-induced PA (2B). Aspirin 75mg OD and 300mg OD, but not 20mg BD, significantly prolonged bleeding time from baseline (2C). Ticagrelor significantly prolonged bleeding time in combination with any dose of aspirin or no aspirin. Aspirin dose-dependently inhibited PGE2 release. Conclusions All doses of aspirin tested prevented the ability of ticagrelor to significantly inhibit cytokine release during experimental endotoxaemia. Aspirin 20mg BD may offer improved bleeding risk with maintained antiplatelet effect compared to standard regimens. Where ticagrelor monotherapy is an option, dropping aspirin may allow ticagrelor to exert greater beneficial effect on inflammatory pathways relevant to atherothrombosis, potentially reducing ischaemic risk whilst also reducing bleeding risk.Figure 1Figure 2

Evaluation of the antiedematogenic and anti-inflammatory properties of Ximenia americana L. (Olacaceae) bark extract in experimental models of inflammation

Edema is one of the obvious indicators of inflammation and a crucial factor to take into account when assessing a substance's capacity to reduce inflammation. We aimed to evaluate the antiedematogenic and anti-inflammatory profile of the hydroethanolic barks extract of Ximenia americana (HEXA). The possible antiedematogenic and anti-inflammatory effect of EHXA (50, 100 mg/kg and 250 mg/kg v.o) was evaluated using the paw edema induced by carrageenan, zymosan, dextran, CFA and by different agents inflammatory (serotonin, histamine, arachidonic acid and PGE2), and pleurisy model induced by carrageenan and its action on IL-1β and TNF-α levels was also evaluated. HEXA demonstrated a significant antiedematogenic effect at concentrations of 50, 100 and 250 mg/kg on paw edema induced by carrageenan, zymosan and dextran. However, the concentration of 50 mg/kg as standard, demonstrating the effect in the subchronic model, induced CFA with inhibition of 59.06 %. In models of histamine-induced paw edema, HEXA showed inhibition of − 30 min: 40.49 %, 60 min: 44.70 % and 90 min: 48.98 %; serotonin inhibition - 30 min: 57.09 %, 60 min: 66.04 % and 90 min: 61.79 %; arachidonic acid inhibition - 15 min: 36.54 %, 30 min: 51.10 %, 45 min: 50.32 % and 60 min: 76.17 %; and PGE2 inhibition - 15 min: 67.78 %, 30 min: 62.30 %, 45 min: 54.25 % and 60 min: 47.92 %. HEXA significantly reduced (p < 0.01) leukocyte migration in the pleurisy model and reduced TNF-α and IL-1β levels in pleural lavage (p < 0.0001). The results showed that HEXA has the potential to have an antiedematogenic impact in both acute and chronic inflammation processes, with a putative mode of action including the suppression or regulation of inflammatory mediators.

Evaluation of the anti-inflammatory activity of Acacia polyphylla and identification of a new apigenin-3-C- glycosylated type flavonoid

Owing to the potentially harmful adverse effects of current anti-inflammatory drugs, there is a need to identify new alternative substances. Thus, this study aimed to perform a phytochemical analysis of A. polyphylla to identify compounds responsible for its anti-inflammatory activity. Several fractions of the A. polyphylla extract were obtained and evaluated in an ex vivo anti-inflammatory assay using fresh human blood. Among the evaluated fractions, the BH fraction displayed the highest percentage of PGE2 inhibition (74.8%) compared to the reference drugs dexamethasone and indomethacin, demonstrating its excellent potential for anti-inflammatory activity. Astragalin (P1), a known 3-O-glucoside of kaempferol, was isolated from the A. polyphylla extract for the first time. In addition, a new compound (P2) was isolated and identified as the apigenin-3-C-glycosylated flavonoid. Astragalin showed moderate PGE2 activity (48.3%), whereas P2 was not anti-inflammatory. This study contributes to the phytochemical studies of A. polyphylla and confirms its anti-inflammatory potential.

Abstract 6333: Repurposing NSAIDs for chemo-immunotherapy: mechanisms beyond COX inhibition

Abstract It has been well-established that some nonsteroidal anti-inflammatory drugs (NSAIDs) have antitumor activities. The beneficial effects of these NSAIDs are mainly attributed to their ability to inhibit the production and activity of cyclooxygenases (COX1 and COX2) and prostaglandin (PGE2), which are known to promote tumor progression, angiogenesis, metastasis and immunosuppression. We recently reported that administration of indomethacin, a prototypical NSAID, can enhance the antitumor efficacy of adoptive T cell therapy in animal models. However, currently adoptive T cell therapy as a treatment option is only suitable for selected patients with certain types of cancer. Here, we set out to explore the utility of indomethacin in a chemo-immunotherapy setting that is readily applicable to a wide range of cancers. Cyclophosphamide (CTX) is a widely used antineoplastic chemotherapeutic agent with immunostimulatory activities when used at low-medium doses. We show that indomethacin had no impact on tumor growth but can significantly enhance the antitumor effect of CTX in multiple mouse tumor models. The beneficial effect of indomethacin was diminished in immunodeficient mice or CD8 T cell-depleted wild-type mice, indicating the requirement for the host immunity. Furthermore, the CTX and indomethacin regimen can sensitize tumors to anti-PD1 immunotherapy. scRNAseq analysis of tumor samples revealed the impact of indomethacin on the tumor microenvironment. Our data also indicate that the immunopotentiating effect of indomethacin can be independent of PGE2 inhibition, and involves the TRAIL-DR5 axis in promoting tumor regression. Other potential mechanisms, including modulation of chronic interferon signaling in tumor cells, have also been investigated. Altogether, our study sheds light on the multiple mechanisms underlying indomethacin’s beneficial effects, and highlights the potential of NSAID administration as a readily applicable and cost-effective approach to augment the efficacy of chemo-immunotherapy. Citation Format: Ogacheko D. Okoko, Md Y. Gazi, Xin Wang, Caitlin Brandle, Mercy Kehinde-Ige, Gary A. Piazza, Huidong Shi, Gang Zhou. Repurposing NSAIDs for chemo-immunotherapy: mechanisms beyond COX inhibition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6333.

Rational design of biodegradable sulphonamide candidates treating septicaemia by synergistic dual inhibition of COX-2/PGE2 axis and DHPS enzyme

A new series of co-drugs was designed based on hybridising the dihydropteroate synthase (DHPS) inhibitor sulphonamide scaffold with the COX-2 inhibitor salicylamide pharmacophore through biodegradable linkage to achieve compounds with synergistic dual inhibition of COX-2/PGE2 axis and DHPS enzyme to enhance antibacterial activity for treatment of septicaemia. Compounds 5 b, 5j, 5n and 5o demonstrated potent in vitro COX-2 inhibitory activity comparable to celecoxib. 5j and 5o exhibited ED50 lower than celecoxib in carrageenan-induced paw edoema test with % PGE2 inhibition higher than celecoxib. Furthermore, 5 b, 5j and 5n showed gastric safety profile like celecoxib. Moreover, in vivo antibacterial screening revealed that, 5j showed activity against S.aureus and E.coli higher than sulfasalazine. While, 5o revealed activity against E.coli higher than sulfasalazine and against S.aureus comparable to sulfasalazine. Compound 5j achieved the target goal as potent inhibitor of COX-2/PGE2 axis and in vivo broad-spectrum antibacterial activity against induced septicaemia in mice.

Anti-Inflammatory Effect of Resveratrol Derivatives via the Downregulation of Oxidative-Stress-Dependent and c-Src Transactivation EGFR Pathways on Rat Mesangial Cells.

In Taiwan, the root extract of Vitis thunbergii Sieb. et Zucc. (Vitaceae, VT) is rich in stilbenes, with resveratrol (Res) and its derivatives being the most abundant. Previously, we showed that the effect of Res derivatives against tumor necrosis factor-α (TNF-α)-stimulated inflammatory responses occurs via cPLA2/COX-2/PGE2 inhibition. This study compared and explored the underlying anti-inflammatory pharmacological mechanisms. Before stimulation with TNF-α, RMCs were treated with/without pharmacological inhibitors of specific protein kinases. The expression of inflammatory mediators was determined by Western blotting, gelatin zymography, real-time PCR, and luciferase assay. Cellular and mitochondrial ROS were measured by H2DHFDA or DHE and MitoSOX™ Red staining, respectively. The RNS level was indirectly measured by Griess reagent assay. Kinase activation and association were assayed by immunoprecipitation followed by Western blotting. TNF-α binding to TNFR recruited Rac1 and p47phox, thus activating the NAPDH oxidase-dependent MAPK and NF-κB pathways. The TNF-α-induced NF-κB activation via c-Src-driven ROS was independent from the EGFR signaling pathway. The anti-inflammatory effects of Res derivatives occurred via the inhibition of ROS derived from mitochondria and NADPH oxidase; RNS derived from iNOS; and the activation of the ERK1/2, JNK1/2, and NF-κB pathways. Overall, this study provides an understanding of the various activities of Res derivatives and their pharmacological mechanisms. In the future, the application of the active molecules of VT to health foods and medicine in Taiwan may increase.

Design, synthesis, in vitro determination and molecular docking studies of 4-(1-(tert-butyl)-3-phenyl-1H-pyrazol-4-yl) pyridine derivatives with terminal sulfonamide derivatives in LPS-induced RAW264.7 macrophage cells

In the present work, a new series of 4-(1-(tert-butyl)-3-phenyl-1H-pyrazol-4-yl) pyridine possessing terminal ethyl or propyl sulfonamides was designed and synthesized. The cytotoxic effect of the final compounds was measured by applying MTT assay in LPS-Induced RAW264.7 macrophage cells. The final target compounds were screened for their anti-inflammatory effect through their ability to inhibit NO and PGE2 production and cytokines production (TNF-α, IL-6, IL-1β) in LPS-induced RAW264.7 macrophage at 10 μM concentration. Compounds 8d, 9d, and 9k showed the highest inhibitory effect on NO production. Compounds 8d and 9k exhibited high PGE2 inhibition with IC50 values of 3.47, 2.54 μM, respectively. Compounds 8d and 9k exhibited high cytokines inhibition ≥60%. The most potent compounds 8d and 9k were tested to determine their effect on iNOS and COX-2 mRNA expression level. Compound 9k activity on iNOS and COX-2 proteins level, pro-inflammatory mediators and cytokines was determined and showed remarkable inhibition for both proteins level. Compounds 8d, 9k showed high binding affinity to COX-2 active site and exhibited similar binding interactions of the native ligand celecoxib.

Non-ulcerogenic pyrazolyl 2-hydroxychalcones and pyrazolylpyrazolines derived from naturally existing furochromone (khellin): semi-synthesis, docking study and anti-inflammatory activity

Novel pyrazolyl 2-hydroxychalcone derivatives 3a–e and pyrazolylpyrazoline derivatives 4a–e and 5a–j derived from the naturally existing furochromone (Khellin) were synthesized and evaluated for their in vivo anti-inflammatory activity. Most of the synthesized compounds showed better or comparable activity to that of Diclofenac as reference drug. Twelve compounds were evaluated for their ulcerogenic potential and exhibited no ulcerogenic effect. In addition compounds 3c, 5c and 5h as examples showed PGE2 inhibition % 88.86, 65.87 and 44.06, respectively and TNFα inhibition % 48.62, 31.11 and 16.02, respectively in rat serum samples. Compounds 3c, 5c, 5h and Celecoxib were subjected to in vitro COX-1 and COX-2 inhibition assay, showed selectivity index 45.04, 102.04, 131.58 and 185.18, respectively. The computational finding supported those of in vitro, where the pyrazolylpyrazolines interacted with the COX-2 enzyme in a similar orientation to that of Celecoxib, while chlacones were found to exhibit similar orientation to that of Diclofenac.

Reconsidering the Role of Cyclooxygenase Inhibition in the Chemotherapeutic Value of NO-Releasing Aspirins for Lung Cancer.

Nitric oxide-releasing aspirins (NO-aspirins) are aspirin derivatives that are safer than the parent drug in the gastrointestinal context and have shown superior cytotoxic effects in several cancer models. Despite the rationale for their design, the influence of nitric oxide (NO•) on the effects of NO-aspirins has been queried. Moreover, different isomers exhibit varying antitumor activity, apparently related to their ability to release NO•. Here, we investigated the effects and mode of action of NO-aspirins in non-small-cell lung cancer (NSCLC) cells, comparing two isomers, NCX4016 and NCX4040 (-meta and -para isomers, respectively). NCX4040 was more potent in decreasing NSCLC cell viability and migration and exhibited significant synergistic effects in combination with erlotinib (an epidermal growth factor receptor inhibitor) in erlotinib-resistant cells. We also studied the relationship among the effects of NO-aspirins, NO• release, and PGE2 levels. NCX4040 released more NO• and significantly decreased PGE2 synthesis relative to NCX4016; however, NO• scavenger treatment reversed the antiproliferative effects of NCX4016, but not those of NCX4040. By contrast, misoprostol (a PGE2 receptor agonist) significantly reversed the antiproliferative effect of NCX4040, but not those of NCX4016. Furthermore, misoprostol reversed the antimigratory effects of NCX4040. Overall, these results indicate that PGE2 inhibition is important in the mode of action of NO-aspirins.

Protective mechanisms of resveratrol derivatives against TNF-α-induced inflammatory responses in rat mesangial cells

IntroductionResveratrol has been reported to alleviate inflammatory responses and oxidative stress in mesangial cells and in several types of renal injury in animal models. Previously, the active resveratrol derivatives from the roots of Vitis thunbergii Sieb. & Zucc. (Vitaceae) were shown to have significant anti-platelet and anti-oxidative activities. However, the anti-inflammatory mechanisms of these resveratrol derivatives in rat mesangial cells (RMCs) have not been clarified fully. MethodsThe protective mechanisms of resveratrol derivatives involved in tumor necrosis factor-α (TNF-α)-induced inflammatory responses were assessed by Western blot analysis, real-time PCR, and RT–PCR. The involvement of various signaling molecules in these responses was investigated using selective pharmacological inhibitors. ResultsNontoxic concentrations of the resveratrol derivatives significantly attenuated cytosolic phospholipase A2 (cPLA2) and cyclooxygenase 2 (COX-2) expression in RMCs challenged by TNF-α. These resveratrol derivatives inhibited TNF-α-activated ERK1/2 and JNK1/2 without affecting p38 phosphorylation. Next, we demonstrated that TNF-α induced NF-κB activation, translocation, and promoter activity, which was inhibited by pretreatment with resveratrol derivatives in RMCs. ConclusionThe protective mechanisms of resveratrol derivatives against TNF-α-stimulated inflammatory responses via cPLA2/COX-2/PGE2 inhibition was caused by the attenuation of the JNK1/2, ERK1/2, and NF-κB signaling pathways in RMCs.

Elimination of CD4lowHLA-G+ T cells overcomes castration-resistance in prostate cancer therapy.

Androgen deprivation therapy (ADT) is a main treatment for prostate cancer (PCa) but the disease often recurs and becomes castration-resistant in nearly all patients. Recent data implicate the involvement of immune cells in the development of this castration-resistant prostate cancer (CRPC). In particular, T cells have been found to be expanded in both PCa patients and mouse models shortly after androgen deprivation. However, whether or which of the T cell subtypes play an important role during the development of CRPC is unknown. Here we identified a novel population of CD4lowHLA-G+ T cells that undergo significant expansion in PCa patients after ADT. In mouse PCa models, a similar CD4low T cell population expands during the early stages of CRPC onset. These cells are identified as IL-4-expressing TH17 cells, and are shown to be associated with CRPC onset in patients and essential for the development of CRPC in mouse models. Mechanistically, CD4lowHLA-G+ T cells drive androgen-independent growth of prostate cancer cells by modulating the activity and migration of CD11blowF4/80hi macrophages. Furthermore, following androgen deprivation, elevated PGE2-EP2 signaling inhibited the expression of CD4 in thymocytes, and subsequently induced the polarization of CD4low naïve T cells towards the IL-4-expressing TH17 phenotype via up-regulation of IL23R. Therapeutically, inactivating PGE2 signaling with celecoxib at a time when CD4lowHLA-G+ T cells appeared, but not immediately following androgen deprivation, dramatically suppressed the onset of CRPC. Collectively, our results indicate that an unusual population of CD4lowHLA-G+ T cells is essential for the development of CRPC and point to a new therapeutic avenue of combining ADT with PGE2 inhibition for the treatment of prostate cancer.

Eicosanoids and HB-EGF/EGFR in cancer.

Eicosanoids are bioactive lipids that play crucial roles in various pathophysiological conditions, including inflammation and cancer. They include both the COX-derived prostaglandins and the LOX-derived leukotrienes. Furthermore, the epidermal growth factor receptor (EGFR) pathways family of receptor tyrosine kinases also are known to play a central role in the tumorigenesis. Various antitumor modalities have been approved cancer treatments that target therapeutically the COX-2 and EGFR pathways; these include selective COX-2 inhibitors and EGFR monoclonal antibodies. Research has shown that the COX-2 and epidermal growth factor receptor pathways actively interact with each other in order to orchestrate carcinogenesis. This has been used to justify a targeted combinatorial approach aimed at these two pathways. Although combined therapies have been found to have a greater antitumor effect than the administration of single agent, this does not exempt them from the possible fatal cardiac effects that are associated with COX-2 inhibition. In this review, we delineate the contribution of HB-EGF, an important EGFR ligand, to the cardiac dysfunction related to decreased shedding of HB-EGF after COX-2/PGE2 inhibition. A better understanding of the molecular mechanisms underlying these cardiac side effects will make possible more effective regimens that use the dual-targeting approach.

New selective cyclooxygenase-2 inhibitors from cyclocoumarol: Synthesis, characterization, biological evaluation and molecular modeling

In this work, a serie of cyclocoumarol derivatives was designed, synthesized, characterized and studied for their potentialities as selective inhibitors of COX-2. All target compounds have been screened for their anti-inflammatory activity by the assay of PGE2 production. Among them, compound 5d exhibited the most potent inhibitory activity with a PGE2 inhibition compared to NS-398 (79% and 88% respectively) and showed non-inhibitory activity towards the COX-1 enzyme. Docking studies revealed the capacity of this compound to occupy the selective COX-2 cavity establishing additional hydrogen bonds between the oxygen of the methoxy group and the His90 and Arg513 of the binding site of the enzyme.

Pharmacokinetic and pharmacodynamic evaluation according to absorption differences in three formulations of ibuprofen.

ObjectiveProstaglandin E2 (PGE2) synthesis is modulated by COX2. Changes in PGE2 could be used to quantify the COX2 inhibition after ibuprofen administration. This study investigated the pharmacokinetic and pharmacodynamic relationships for COX2 inhibition according to three formulations of ibuprofen in healthy male subjects.Materials and methodsA randomized, open-label, single-dose, three-treatment, six-sequence crossover study was performed in 36 healthy South Korean male volunteers. Enrolled subjects received the following three 200 mg ibuprofen formulations: ibuprofen arginine, solubilized ibuprofen capsule, and standard ibuprofen. Pharmacokinetic and pharmacodynamic blood samples were collected for 16 hours following treatment. For pharmacodynamic evaluations, lipopolysaccharide (LPS)-induced PGE2 inhibition at each time point compared to predose was measured. Noncompartmental analysis was used for pharmacokinetic assessment, and time-weighted average inhibition (WAI) of PGE2 was applied to the pharmacodynamic evaluation.ResultsAfter a single oral dose of the ibuprofen formulations, the median times to maximum concentration were 0.42, 0.5, and 1.25 hours in ibuprofen arginine, solubilized ibuprofen capsule, and ibuprofen, respectively. The maximum observed plasma concentration was lower in ibuprofen, and the area under the plasma concentration–time curve was comparable among the three formulations. A significant difference was observed between fast-acting formulations and standard ibuprofen tablets for both maximum concentration and time taken to reach it. Individual formulations had an effect on PGE2 WAI during the 8 hours following treatment, resulting in significantly lower WAI in standard ibuprofen: ibuprofen arginine 18.4%, solubilized ibuprofen capsule 18.4%, and standard ibuprofen 11.6%.ConclusionRapid absorption and higher peak concentration were observed in ibuprofen arginine and the solubilized ibuprofen capsule. Additionally, fast-acting formulations had more predominant inhibitory activity on the COX2 enzyme.

The anti-inflammatory effects of PGE2 on human lung macrophages are mediated by the EP4 receptor.

PGE2 inhibits cytokine generation from human lung macrophages. However, the EP receptor that mediates this beneficial anti-inflammatory effect of PGE2 has not been defined. The aim of this study was to identify the EP receptor by which PGE2 inhibits cytokine generation from human lung macrophages. This was determined by using recently developed EP receptor ligands. The effects of PGE2 and EP-selective agonists on LPS-induced generation of TNF-α and IL-6 from macrophages were evaluated. The effects of EP2 -selective (PF-04852946, PF-04418948) and EP4 -selective (L-161,982, CJ-042794) receptor antagonists on PGE2 responses were studied. The expression of EP receptor subtypes by human lung macrophages was determined by RT-PCR. PGE2 inhibited LPS-induced and Streptococcus pneumoniae-induced cytokine generation from human lung macrophages. Analysis of mRNA levels indicated that macrophages expressed EP2 and EP4 receptors. L-902,688 (EP4 receptor-selective agonist) was considerably more potent than butaprost (EP2 receptor-selective agonist) as an inhibitor of TNF-α generation from macrophages. EP2 receptor-selective antagonists had marginal effects on the PGE2 inhibition of TNF-α generation, whereas EP4 receptor-selective antagonists caused rightward shifts in the PGE2 concentration-response curves. These studies demonstrate that the EP4 receptor is the principal receptor that mediates the anti-inflammatory effects of PGE2 on human lung macrophages. This suggests that EP4 receptor agonists could be effective anti-inflammatory agents in human lung disease.

Model-based prediction of the acute and long-term safety profile of naproxen in rats.

Despite the increasing importance of biomarkers as predictors of drug effects, toxicology protocols continue to rely on the experimental evidence of adverse events (AEs) as a basis for establishing the link between indicators of safety and drug exposure. Furthermore, biomarkers may facilitate the translation of findings from animals to humans. Combined with a model-based approach, biomarker data have the potential to predict long-term effects arising from prolonged drug exposure. Here, we used naproxen as a paradigm to explore the feasibility of a biomarker-guided approach for the prediction of long-term AEs in humans. An experimental toxicology protocol was set up for evaluating the effects of naproxen in rats, in which four active doses were tested (7.5, 15, 40 and 80 mg·kg(-1) ). In addition to AE monitoring and histology, a few blood samples were also collected for the assessment of drug exposure, TXB2 and PGE2 levels. Non-linear mixed effects modelling was used to analyse the data and identify covariate factors on the incidence and severity of AEs. Modelling results showed that besides drug exposure, maximum PGE2 inhibition and treatment duration were also predictors of gastrointestinal ulceration. Although PGE2 levels were clearly linked to the incidence rates, it appeared that ulceration severity is better predicted by measures of drug exposure. These results show that the use of a model-based approach provides the opportunity to integrate pharmacokinetics, pharmacodynamics and toxicity data, enabling optimization of the design, analysis and interpretation of toxicology experiments.

Ferulic Acid Ethyl Ester Attenuates Inflammatory Response by Suppressing ROS‐related NF‐κB Signaling Pathway in LPS‐induced RAW264.7 Cells

Ferulic acid ethyl ester (FAEE) is an ester derivative of ferulic acid and the latter is known for its anti‐inflammatory and antioxidant properties. Previous studies have shown that ferulic acid protects synaptosomal membrane system and neuronal cell culture systems against hydroxyl and peroxyl radical oxidation. FAEE is lipophilic and is able to easily penetrate into lipid bilayer. Therefore, the present study was designed to investigate the anti‐inflammatory effects of FAEE and its underlying mechanism in RAW264.7 cells. FAEE attenuated the release of NO, PGE2 and pro‐inflammatory cytokines such as IL‐1β, IL‐6 and TNF‐α in a dose‐dependent manner. Consistent with NO and PGE2 inhibition, FAEE suppressed LPS‐induced iNOS and COX‐2 expression as well as the promoter activities of COX‐2 and iNOS. In addition, FAEE pre‐treatment ameliorated ROS and superoxide anion levels in a time‐dependent manner. FAEE also dose‐dependently diminished LPS‐induced the activation mitogen‐activated protein kinases (MAPK) including JNK, ERK and p‐38 by phosphorylation. Furthermore, FAEE pre‐treatment suppressed the activation and translocation into the nucleus of NF‐κB in a dose‐dependent manner by western blotting and confocal microscopic abservation&lt;a name=“_GoBack”&gt;&lt;/a&gt;. The overall results indicate that FAEE may attenuate the inflammatory response of LPS‐induced RAW264.7 cells through ROS‐related MAPK/NF‐κB signaling pathway.

Paracoccidioides brasiliensis interferes on dendritic cells maturation by inhibiting PGE2 production.

Paracoccidioidomycosis (PCM) is a systemic mycosis, endemic in most Latin American countries, especially in Brazil, whose etiologic agent is the thermodimorphic fungus of the genus Paracoccidioides, comprising cryptic species of Paracoccidioides brasiliensis, S1, PS2, PS3 and Paracoccidioides lutzii. The mechanisms involved in the initial interaction of the fungus with cells of the innate immune response, as dendritic cells (DCs), deserve to be studied. Prostaglandins (PGs) are eicosanoids that play an important role in modulating functions of immune cells including DCs. Here we found that human immature DCs derived from the differentiation of monocytes cultured with GM-CSF and IL-4 release substantial concentrations of PGE2, which, however, were significantly inhibited after challenge with P. brasiliensis. In vitro blocking of pattern recognition receptors (PRRs) by monoclonal antibodies showed the involvement of mannose receptor (MR) in PGE2 inhibition by the fungus. In addition, phenotyping assays showed that after challenge with the fungus, DCs do not change their phenotype of immature cells to mature ones, as well as do not produce IL-12 p70 or adequate concentrations of TNF-α. Assays using exogenous PGE2 confirmed an association between PGE2 inhibition and failure of cells to phenotypically mature in response to P. brasiliensis. We conclude that a P. brasiliensis evasion mechanism exists associated to a dysregulation on DC maturation. These findings may provide novel information for the understanding of the complex interplay between the host and this fungus.

Improving VEGF-targeted therapies through inhibition of COX-2/PGE2 signaling

Antiangiogenic agents targeting the vascular endothelial growth factor A (VEGFA) pathway play an important role in current cancer treatment modalities but are limited by alternative angiogenesis mechanisms. Recent studies suggest that enhanced signaling through a COX-2/PGE2 axis contributes to VEGF-independent tumor angiogenesis. Thus, COX-2/PGE2 inhibition may potentiate VEGF therapies.