EP4 Expression Research Articles

Spatiotemporal EP4–fibulin-1 expression is associated with vascular intimal hyperplasia

Abstract Aims Cyclooxygenase-2–derived prostaglandin E2 (PGE2) is thought to promote vascular intimal hyperplasia (IH). It has been reported that the PGE2 receptor EP4 is upregulated in injured vessels and that EP4 signalling in vascular smooth muscle cells (VSMCs) promotes IH. In contrast, EP4 in endothelial cells has been demonstrated to restrain IH. We aimed to investigate spatiotemporal expression of EP4 and whether modulating EP4 signalling could be a viable therapeutic strategy. Methods and results We generated EP4 reporter mice (Ptger4-IRES-nlsLacZ) and found temporary but prominent EP4 expression in VSMCs of the proliferative neointima 2 weeks after femoral artery wire injury. Injury-induced IH was diminished in VSMC-targeted EP4 heterozygous deficient mice (Ptger4fl/+;SM22-Cre) 2 and 4 weeks after vascular injury compared to that in SM22-Cre, whereas injury-induced IH was exacerbated in VSMC-targeted EP4-overexpressing mice (Ptger4-Tg) compared to controls (non-Tg). We then investigated the downstream signalling of EP4 in VSMCs. Stimulation of EP4 increased mRNA and protein levels of the glycoprotein fibulin-1 in Ptger4-Tg VSMCs. Fibulin-1C recombinant proteins increased VSMC proliferation and migration through transforming growth factor (TGF)- β/Smad3, and EP4-mediated proliferation and migration were attenuated in Fbln1fl/fl;SM22-Cre VSMCs and in CRISPR/Cas9-mediated Fbln1 knockdown in Ptger4-Tg VSMCs. We generated multiple deletion mutants of fibulin-1C and found that EGF-like modules 6–8 appear to be involved in fibulin-1-mediated proliferation. Among binding partners of fibulin-1, extracellular matrix protein 1 (ECM1) was also upregulated by EP4 stimulation, and fibulin-1C and ECM1 proteins additively enhanced VSMC proliferation and migration. Injury-induced IH was attenuated in VSMC-targeted fibulin-1 deletion mice (Fbln1fl/fl;SM22-Cre) compared to Fbln1fl/fl. Furthermore, systemic EP4 antagonist administration reduced injury-induced IH in wild-type mice. Conclusion EP4 was upregulated in VSMCs of proliferative IH, and EP4 signalling promoted IH, at least in part through fibulin-1. An EP4 antagonist might be considered as a therapeutic strategy for IH.

PGE2 binding to EP2 promotes ureteral stone expulsion by relaxing ureter via the cAMP-PKA pathway

BackgroundThis study investigated the relaxation effect of PGE2 on the ureter and its role in promoting calculi expulsion following calculi development.MethodsBy using immunofluorescence and Western blot, we were able to locate EP receptors in the ureter. In vitro experiments assessed the impact of PGE2, receptor antagonists, and agonists on ureteral relaxation rate. We constructed a model of ureteral calculi with flowable resin and collected ureteral tissue from postoperative side of the ureter after obstruction surgery. Western blot analysis was used to determine the protein expression levels of EP receptors and the PGE2 terminal synthase mPGES-1. Additionally, PGE2 was added to smooth muscle cells to observe downstream cAMP and PKA changes.ResultsThe expression of EP2 and EP4 proteins in ureteral smooth muscle was verified by Western blot analysis. According to immunofluorescence, EP2 was primarily found on the cell membrane, while EP4 was found in the nucleus. In vitro, PGE2 induced concentration-dependent ureteral relaxation. Maximum diastolic rate was 70.94 ± 4.57% at a concentration of 30µM. EP2 antagonists hindered this effect, while EP4 antagonists did not. Obstructed ureters exhibited elevated mPGES-1 and EP2 protein expression (P < 0.01). Smooth muscle cells treated with PGE2 displayed increased cAMP and phosphorylated PKA.ConclusionsPGE2 binding to EP2 induces ureteral relaxation through the cAMP-PKA pathway. This will provide a new theoretical basis for the development of new therapeutic approaches for the use of PGE2 in the treatment of ureteral stones.

Zerumbone exhibits anti-inflammatory effects by suppressing eicosanoid signaling: Evidence from LPS-induced peripheral blood leukocytes

Zerumbone, a sesquiterpene isolated from Zingiber zerumbet, has many bioactivities, exhibiting anti-inflammatory properties. However, the effect of zerumbone on the eicosanoid signaling pathway has yet to be examined. Here, we deciphered the anti-eicosanoid properties of zerumbone isolated from ginger. The molecular interaction between zerumbone and eicosanoid metabolizing enzymes (COX-2, 5-LOX, FLAP, and LTA4-hydrolase) and receptors (EP-4, BLT-1, and ICAM-1) along with NOS-2 were assessed using Auto-Dock 4.2 and visualized by chimera and Liggplot+ software. Further, the leukocytes were treated with zerumbone (1–20 μM) and activated using bacterial lipopolysaccharide (LPS-10 nM). The oxidative stress (OS) markers, antioxidant enzymes, and the eicosanoid pathway mediators such as COX-2, 5-LOX, BLT-1, and EP-4 were assessed. The molecular interaction of zerumbone with eicosanoids showed a higher binding affinity with mPGES-1, followed by NOS-2, FLAP, COX-2, LTA-4-hydrolase, and BLT-1. The concentration of 5 μM zerumbone effectively prevented the generation of reactive oxygen species (ROS) and nitric oxide (NO). Likewise, zerumbone significantly (p<0.05) inhibited COX-2, 5-LOX, NOS-2, EP-4, BLT-1, and ICAM-1 expression in LPS-induced peripheral blood leukocytes from rats. Further, the zerumbone treatment on the human PBMCs activated with LPS showed significant inhibition in the expression of ICAM1, COX-2, 5-LOX, and the generation of inflammatory cytokines compared to the control. Overall, the data presented infers that zerumbone positively modulates critical enzymes and receptors of eicosanoids in leukocytes activated with lipopolysaccharides. Thus, zerumbone can be a potential anti-eicosanoid drug in managing inflammation.

Treprostinil inhibits functional activation of scleroderma (SSc) vascular smooth muscle cells (vSMCs) by inhibiting Yap and activating PPARG signaling.

Background:&#x0D; Progressive vascular wall thickness and fibrosis are the hallmarks of SSc vasculopathy. Overexpression of TGFB1 in SSc and activation of vSMCs are important steps in the pathogenesis of SSc vascular disease.&#x0D; Objectives:&#x0D; In this study, we examined the expression levels of COL1, PCNA, PFKP, IP, EP2, IP, and PTGIS in SSc skin, the effects of Treprostinil (prostacyclin analog) on cell proliferation, TGFB1-induced collagen expression in SSc-vSMCs, PPARG expression and Yap nuclear translocation.&#x0D; Methods: &#x0D; SSc and control skin biopsies were fixed and 10uM serial sections were cut for histological examination. vSMCs were isolated from involved skin and matched healthy subjects. The expression and distribution of collagen, PCNA, PFKP, IP, EP2, PTGIS, PPARG, and Yap were measured by immunohistochemical staining or immunofluorescent staining. Cell proliferation was measured by MTT assay. The mRNA expression levels were detected by qPCR.&#x0D; Results:&#x0D; The protein expression levels of collagen, PCNA, PFKP, and EP2 were increased, while the expression levels of PTGIS and IP were decreased in vSMCs of SSc-skin, compared to the control. These results suggested that defective PGI2-IP signaling in SSc-vSMCs may contribute to vessel wall thickness and vascular fibrosis in SSc. Treprostinil inhibited vSMCs proliferation, COL1A1, and PFKP mRNA expression in SSc-vSMCs in a dose-dependent fashion. Treprostinil also inhibited TGFB1-induced COL1A1 mRNA expression in SSc-vSMCs via engagement of EP2. The PPARG expression was significantly increased in treprostinil-treated SSc-vSMCs. Treprostinil decreased the nuclear location of YAP which is induced by 10%FBS and TGFB1.&#x0D; Conclusion:&#x0D; Defective PGI2-IP signaling in SSc-vSMCs is associated with enhanced expression of collagen, PCNA, and PFKP in SSc vessel walls. The antiproliferative and antifibrotic activity of treprostinil is mediated through the inhibition of YAP nuclear translocation and enhanced PPARG expression. YAP and PPARG might be promising therapeutic targets for the treatment of SSc-related vasculopathy.

Decreased Expression of EP3 Receptor mRNA in the Brain of Mouse Model of Autism Spectrum Disorder.

Accumulating evidence has implicated the role of neuroinflammation in the pathology of autism spectrum disorder (ASD), a neurodevelopmental disorder. To investigate the expression of prostaglandin EP3 (EP3) receptor mRNA in the brain of ASD mouse model. Pregnant mice were injected with valproic acid (VPA) 500 mg/kg intraperitoneally at 12.5 d gestation. The offspring were tested at the age of 5-6 weeks old for their social interaction behavior. Each mouse was assessed for prostaglandin EP3 receptor expression in the prefrontal cortical, hippocampal and cerebellar areas one day after the behavioral test. Compared to the naive, mice born to dams treated with VPA demonstrated a significantly shorter duration of sniffing behavior, a model of social interaction. Results further showed that the expression of EP3 receptor mRNA was significantly lower in all three brain regions of the mice born to VPA-treated dams. The present study provides further evidence of the relevance of the arachidonic acid cascade as an essential part of neuroinflammation in the pathology of ASD.

Therapeutic effect of Leonuri Herba aqueous decoction on primary dysmenorrhea in rats and its metabolomic analysis

This study aimed to investigate the therapeutic effect of Leonuri Herba aqueous decoction on primary dysmenorrhea(PD) and explore the underlying mechanism in conjunction with untargeted metabolomics. Forty adult female rats were randomly divi-ded into a normal group, a model control group, ibuprofen(0.12 g·kg~(-1)) group, and high-and low-dose Leonuri Herba aqueous decoction(5 and 2.5 g·kg~(-1)) groups, with eight rats in each group. The PD rat model was prepared using intramuscular injection of estradiol benzoate combined with intraperitoneal injection of pitocin. Drugs were administered by gavage from the 4th day of modeling for 7 d. After the last administration, pitocin was injected intraperitoneally, and the writhing latency and writhing times within 30 min were recorded. The uterine and ovarian coefficients were determined. Estradiol(E_2), progesterone(Prog), oxytocin(OT), cyclooxyge-nase 2(COX-2), prostaglandin E_2(PGE_2), prostaglandin F_(2α)(PGF_(2α)), and Ca~(2+) levels in uterine tissues were measured by ELISA and biochemical kits. Morphological changes in uterine and ovarian tissues were observed by hematoxylin-eosin(HE) staining. The protein expression of oxytocin receptor(OTR), prostaglandin E_2 receptor 3(EP3), and estrogen receptor alpha(ERα) in uterine tissues was detected by immunohistochemistry. The mRNA expression of OTR, PGE_2 receptors 1-4(EP1, EP2, EP3, and EP4), and PGF_(2α) receptor(FP) in uterine tissues was detected by quantitative real-time PCR. Untargeted metabolomics analysis was performed by ultra-high-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry(LC-QTOF-MS) technology to screen potential biomarkers and enrich metabolic pathways. The results showed that Leonuri Herba was able to significantly reduce the writhing times in PD rats(P&lt;0.05 or P&lt;0.01), significantly reduce the uterine and ovarian coefficients(P&lt;0.01), and improve their histomorphology. After treatment with Leonuri Herba, PGE_2 content was significantly increased(P&lt;0.05), COX-2, PGF_(2α) and Ca~(2+) content, and PGF_(2α)/PGE_2 was significantly decreased(P&lt;0.05 or P&lt;0.01), and OT content was decreased, while E_2 and Prog content tended to further increase in uterine tissues of PD rats. Correspondingly, OTR and EP3 protein expression was significantly downregulated(P&lt;0.05 or P&lt;0.01) and ERα protein expression was upregulated(P&lt;0.05) in uterine tissues. The mRNA expression of FP and EP4 in uterine tissues was significantly downregulated(P&lt;0.01), and the mRNA expression of EP1, EP3, and OTR showed a decreasing trend. The untargeted metabolomics results showed that 10 differential metabolites were restored in the plasma of PD rats after Leonuri Herba treatment. The results indicate that Leonuri Herba is effective in the prevention and treatment of PD, and the underlying mechanism may be attributed to the regulation of PGs synthesis and corresponding receptor binding.

Pylorus ligation-induced hyperacidity: synergistic prophylactic effects of linagliptin and L-arginine via up-regulation of EP4 receptor subtype and improvement of vascular endothelial damage.

Gastric hyperacidity and ulceration are chronic diseases characterized by repeated healing followed by re-exacerbation. The study aims to protect against gastric hyperacidity without interfering with gastric acid secretion. Pylorus ligation-induced hyperacidity is commonly utilized in the induction of gastric ulcers.Forty-two rats were distributed into seven groups (n = 6). Group I comprised sham-operated group. Group II served as pylorus-ligation group. Groups III-VII were given oral Linagliptin (LN; 3 and 6mg/kg), L-arginine (LA; 150 and 300mg/kg) and their combination (LN 3 + LA 150mg/kg), respectively for 7days. On the 8th day, groups II-VII were subjected to pylorus-ligation.Treatment of pylorus-ligated rats with LN, LA and their combination improved the gastric hyperacidity as exhibited by a marked reduction in the gastric juice volume, total and free acidities and pepsin contents with a noticeable increase in pH. Pre-treatment with LN, LA and their combination showed a marked alleviation in the gastric inflammatory indicators evidenced by reduction in the gastric levels of MCP-1and Il-1β as well as elevation of eNOS levels versus the sham-operated group. A marked up-regulation in the gastric gene expression of PGE, EP4 and VEGF accompanied by an improvement of the histopathologic pictures/scores, and TNF-α and caspase-3 immuno-staining were also recorded.By estimating the combination-index, it can be concluded that combining LN with LA exhibited prophylactic synergistic effects in ameliorating pylorus ligated-induced hyperacidity, mainly via up-regulation of EP4 receptor and improvement of vascular endothelial damage through VEGF expression in gastric mucosa.

Expression of steroidogenic enzymes in placentome of ewes with pregnancy toxemia after two parturition induction methods

The regulation pattern of important enzymes in placental steroidogenesis and prostaglandins in ewes with pregnancy toxemia is reviewed. The alterations of gene expressions after the administration of aglepristone and dexamethasone are also discussed. Four healthy and 22 ewes with pregnancy toxemia were included to the study. Group AG (n=9) and Group DEX (n=9) in which ewes were injected twice with 10 mg/kg of aglepristone and once with 5 ml dexamethasone, respectively; whereas negative control [Group CG (n=4)] and pregnancy toxemia [Group PT (n=4)] groups received no treatment for parturition induction. Placentomes were collected either right after parturition or C-section. mRNA extraction from total placentome, caruncle, cotyledon and caruncle part of placentomes was carried out and Real-Time PCR was performed. Serum samples were collected and cortisol, PGFM, PGE2 and estrone sulfate concentrations were measured after treatments until parturition. The lowest mRNA expressions of steroidogenic enzymes were detected in group PT. Interestingly similar expression pattern of steroidogenic enzymes in group AG was as similar as group PT. No difference was found in expressions of 3βHSD and CYP19. PTGS2/COX2 and PGFS mRNA expressions were statistically different between groups AG-DEX and in caruncle between groups, respectively (P&lt;0.005). Significant difference could clearly be observed in EP3 expression in caruncle of DEX and AG compared to CG (P&lt;0.005); however PTGES, EP1, EP2 and EP4 expressions were not statistically different among groups (P&gt;0,05). Ostrone sulfate, PGE2 and PGFM concentrations were statistically different according to the sampling time between groups however no difference was observed in cortisol. The present study has suggests that the endocrinologic pathway controlling parturition is clearly different in ewes with pregnancy toxemia. Spontaneous parturition could occur as a consequence of immune and inflammatory processes, which could be activated by by-products of fat metabolism. Dexamethasone applications has mimicked normal parturition, however the gene expression regulations, controlling uterine contractions, are observed as similar as group PT. Probably expressions of EP1 and tissue-specific counter-expressions of cervical EP genes could refer the pathogenesis of insufficient cervical dilatation, observed in pregnancy toxemia and dexamethsone applications.

Complementary roles of EP2 and EP4 receptors in malignant glioma.

Glioblastoma (GBM) is the most aggressive brain tumour in the central nervous system, but the current treatment is very limited and unsatisfactory. PGE2 -initiated cAMP signalling via EP2 and EP4 receptors is involved in the tumourigenesis of multiple cancer types. However, whether or how EP2 and EP4 receptors contribute to GBM growth largely remains elusive. We performed comprehensive data analysis of gene expression in human GBM samples and determined their expression correlations through multiple bioinformatics approaches. A time-resolved fluorescence energy transfer (TR-FRET) assay was utilized to characterize PGE2 -mediated cAMP signalling via EP2 and EP4 receptors in human glioblastoma cells. Using recently reported potent and selective small-molecule antagonists, we determined the effects of inhibition of EP2 and EP4 receptors on GBM growth in subcutaneous and intracranial tumour models. The expression of both EP2 and EP4 receptors was upregulated and highly correlated with a variety of tumour-promoting cytokines, chemokines, and growth factors in human gliomas. Further, they were heterogeneously expressed in human GBM cells, where they compensated for each other to mediate PGE2 -initiated cAMP signalling and to promote colony formation, cell invasion and migration. Inhibition of EP2 and EP4 receptors revealed that these receptors might mediate GBM growth, angiogenesis, and immune evasion in a compensatory manner. The compensatory roles of EP2 and EP4 receptors in GBM development and growth suggest that concurrently targeting these two PGE2 receptors might represent a more effective strategy than inhibiting either alone for GBM treatment.

Natural fulvic acids inhibit non-small-cell lung cancer through the COX-2/PGE2/EP4 axis: In silico and in vivo assessments

PurposeNon-small-cell lung cancer (NSCLC) is a major public health concern with a high incidence worldwide. Coal-derived fulvic acids (FAs) contain functional groups in their chemical structures. Overexpression of cyclooxygenases-2 (COX-2), prostaglandin E2 (PGE2), and the PGE2 receptor EP4 subtype (EP4) can have a potential link with the increased tumor incidence and promoted tumor growth and metastasis in NSCLC. This study aimed to assess the biological roles of coal-derived FAs in the growth and development of NSCLC and to elucidate the underlying molecular mechanisms. MethodsA web-based tool for predicting small-molecule pharmacokinetics (pkCSM) was used to analyze the absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties of FAs. Molecular docking and dynamic simulations were performed to analyze the binding affinities of COX-2 and EP4 to FA. An acute toxicity test and an antitumor study were used to analyze the toxicity and anti-NSCLC effects of FAs. Thirty NSCLC-bearing nude mice were randomly divided into five groups (six mice per group): vehicle control, positive control with 20 mg/kg body weight (BW) 5-fluorouracil, and three treatments with 25, 50, and 100 mg/kg BW FAs. The BW and tumor volume were recorded, and the COX-2, PGE2, and EP4 protein expression were measured and analyzed. ResultsUsing the predictive pkCSM algorithm, we found that FA did not cause developmental toxicity. Molecular simulations revealed that COX-2 and EP4 expression was inhibited by FA. An acute toxicity test conformed that the maximum tolerated FAs dose was >3.0 g/kg BW. The animal study demonstrated that FA treatment significantly downregulated the expression of COX-2, PGE2, and EP4 in NSCLC-bearing mice compared to that in vehicle control mice (p < 0.01). ConclusionsNatural FAs may exert anti-NSCLC effects through the COX-2/PGE2/EP4 axis.

Posttranscriptional regulation of the prostaglandin E receptor spliced-isoform EP3-γ and its implication in pancreatic β-cell failure.

In Type 2 diabetes (T2D), elevated lipid levels have been suggested to contribute to insulin resistance and β-cell dysfunction. We previously reported that the expression of the PGE2 receptor EP3 is elevated in islets of T2D individuals and is preferentially stimulated by palmitate, leading to β-cell failure. The mouse EP3 receptor generates three isoforms by alternative splicing which differ in their C-terminal domain and are referred to as mEP3α, mEP3β, and mEP3γ. We bring evidence that the expression of the mEP3γ isoform is elevated in islets of diabetic db/db mice and is selectively upregulated by palmitate. Specific knockdown of the mEP3γ isoform restores the expression of β-cell-specific genes and rescues MIN6 cells from palmitate-induced dysfunction and apoptosis. This study indicates that palmitate stimulates the expression of the mEP3γ by a posttranscriptional mechanism, compared to the other spliced isoforms, and that the de novo synthesized ceramide plays an important role in FFA-induced mEP3γ expression in β-cells. Moreover, induced levels of mEP3γ mRNA by palmitate or ceramide depend on p38 MAPK activation. Our findings suggest that mEP3γ gene expression is regulated at the posttranscriptional level and defines the EP3 signaling axis as an important pathway mediating β-cell-impaired function and demise.

The Atypical MAP Kinase MAPK15 Is Required for Lung Adenocarcinoma Metastasis via Its Interaction with NF-κB p50 Subunit and Transcriptional Regulation of Prostaglandin E2 Receptor EP3 Subtype

Studying the relatively underexplored atypical MAP Kinase MAPK15 on cancer progression/patient outcomes and its potential transcriptional regulation of downstream genes would be highly valuable for the diagnosis, prognosis, and potential oncotherapy of malignant tumors such as lung adenocarcinoma (LUAD). Here, the expression of MAPK15 in LUAD was detected by immunohistochemistry and its correlation with clinical parameters such as lymph node metastasis and clinical stage was analyzed. The correlation between the prostaglandin E2 receptor EP3 subtype (EP3) and MAPK15 expression in LUAD tissues was examined, and the transcriptional regulation of EP3 and cell migration by MAPK15 in LUAD cell lines were studied using the luciferase reporter assay, immunoblot analysis, qRT-PCR, and transwell assay. We found that MAPK15 is highly expressed in LUAD with lymph node metastasis. In addition, EP3 is positively correlated with the expression of MAPK15 in LUAD tissues, and we confirmed that MAPK15 transcriptionally regulates the expression of EP3. Upon the knockdown of MAPK15, the expression of EP3 was down-regulated and the cell migration ability was decreased in vitro; similarly, the mesenteric metastasis ability of the MAPK15 knockdown cells was inhibited in in vivo animal experiments. Mechanistically, we demonstrate for the first time that MAPK15 interacts with NF-κB p50 and enters the nucleus, and NF-κB p50 binds to the EP3 promoter and transcriptionally regulates the expression of EP3. Taken together, we show that a novel atypical MAPK and NF-κB subunit interaction promotes LUAD cell migration through transcriptional regulation of EP3, and higher MAPK15 level is associated with lymph node metastasis in patients with LUAD.

The BCG Moreau Vaccine Upregulates In Vitro the Expression of TLR4, B7-1, Dectin-1 and EP2 on Human Monocytes.

Background: Tuberculosis (TB) is currently the second greatest killer worldwide and is caused by a single infectious agent. Since Bacillus Calmette−Guérin (BCG) is the only vaccine currently in use against TB, studies addressing the protective role of BCG in the context of inducible surface biomarkers are urgently required for TB control. Methods: In this study, groups of HIV-negative adult healthy donors (HD; n = 22) and neonate samples (UCB; n = 48) were voluntarily enrolled. The BCG Moreau strain was used for the in vitro mononuclear cell infections. Subsequently, phenotyping tools were used for surface biomarker detection. Monocytes were assayed for TLR4, B7-1, Dectin-1, EP2, and TIM-3 expression levels. Results: At 48 h, the BCG Moreau induced the highest TLR4, B7-1, and Dectin-1 levels in the HD group only (p-value < 0.05). TIM-3 expression failed to be modulated after BCG infection. At 72 h, BCG Moreau equally induced the highest EP2 levels in the HD group (p-value < 0.005), and higher levels were also found in HD when compared with the UCB group (p-value < 0.05). Conclusions: This study uncovers critical roles for biomarkers after the instruction of host monocyte activation patterns. Understanding the regulation of human innate immune responses is critical for vaccine development and for treating infectious diseases.

Inhibition of Prostaglandin E2 Receptor EP3 Attenuates Oxidative Stress and Neuronal Apoptosis Partially by Modulating p38MAPK/FOXO3/Mul1/Mfn2 Pathway after Subarachnoid Hemorrhage in Rats.

Oxidative stress and neuronal apoptosis contribute to pathological processes of early brain injury (EBI) after subarachnoid hemorrhage (SAH). Previous studies demonstrated that the inhibition of prostaglandin E2 receptor EP3 suppressed oxidative stress and apoptotic effects after Alzheimer's disease and intracerebral hemorrhage. This study is aimed at investigating the antioxidative stress and antiapoptotic effect of EP3 inhibition and the underlying mechanisms in a rat mode of SAH. A total of 263 Sprague-Dawley male rats were used. SAH was induced by endovascular perforation. Selective EP3 antagonist L798106 was administered intranasally at 1 h, 25 h, and 49 h after SAH induction. EP3 knockout CRISPR and FOXO3 activation CRISPR were administered intracerebroventricularly at 48 h prior to SAH, while selective EP3 agonist sulprostone was administered at 1 h prior to SAH. SAH grade, neurological deficits, western blots, immunofluorescence staining, Fluoro-Jade C staining, TUNEL staining, 8-OHdG staining, and Nissl staining were conducted after SAH. The expression of endogenous PGES2 increased and peaked at 12 h while the expression of EP1, EP2, EP3, EP4, and Mul1 increased and peaked at 24 h in the ipsilateral brain after SAH. EP3 was expressed mainly in neurons. The inhibition of EP3 with L798106 or EP3 KO CRISPR ameliorated the neurological impairments, brain tissue oxidative stress, and neuronal apoptosis after SAH. To examine potential downstream mediators of EP3, we examined the effect of the increased expression of activated FOXO3 following the administration of FOXO3 activation CRISPR. Mechanism studies demonstrated that L798106 treatment significantly decreased the expression of EP3, p-p38, p-FOXO3, Mul1, 4-HNE, Bax, and cleaved caspase-3 but upregulated the expression of Mfn2 and Bcl-2 in SAH rats. EP3 agonist sulprostone or FOXO3 activation CRISPR abolished the neuroprotective effects of L798106 and its regulation on expression of p38MAPK/FOXO3/Mul1/Mfn2 in the ipsilateral brain after SAH. In conclusion, the inhibition of EP3 by L798106 attenuated oxidative stress and neuronal apoptosis partly through p38MAPK/FOXO3/Mul1/Mfn2 pathway post-SAH in rats. EP3 may serve as a potential therapeutic target for SAH patients.

Prostaglandin E2 receptor EP1 expression in vulvar cancer

PurposeIn recent years, incidence of vulvar cancer has been on the rise, whereas therapeutic options are still restricted. Therefore, new prognosticators and therapeutic targets are essential. Chronic inflammation plays an important role in carcinogenesis and COX-2, and its product prostaglandin E2 and its receptors EP1–4 are known to be important mediators in cancer initiation and progression.MethodsEP1 expression in vulvar cancer specimens (n = 129) was investigated via immunohistochemistry and evaluated using the well-established immunoreactive score (IRS). Subsequently, the values were correlated with clinicopathological parameters.ResultsOur analysis did not reveal EP1 expression as a negative prognostic factor in overall and disease-free survival. However, in the subgroup of patients with lymph-node metastasis, overall survival was significantly shorter in tumors with high EP1 expression. Moreover, EP1 expression correlated positively with good differentiation of the tumor, but not with p16 status or COX-2 expression.ConclusionsThis study shed first light on EP1 expression in vulvar carcinoma. EP1 expression correlated significantly with the grading of the tumor, suggesting that it influences cell differentiation. Further research on EP1 signaling may lead to a deeper understanding of the molecular mechanisms of carcinogenesis.

Blockade of prostaglandin E2 receptor 4 ameliorates peritoneal dialysis-associated peritoneal fibrosis.

Inflammatory responses in the peritoneum contribute to peritoneal dialysis (PD)-associated peritoneal fibrosis. Results of our previous study showed that increased microsomal prostaglandin E synthase-1-mediated production of prostaglandin E2 (PGE2) contributed to peritoneal fibrosis. However, the role of its downstream receptor in the progression of peritoneal fibrosis has not been established. Here, we examined the role of PGE2 receptor 4 (EP4) in the development of peritoneal fibrosis. EP4 was significantly upregulated in peritoneal tissues of PD patients with ultrafiltration failure, along with the presence of an enhanced inflammatory response. In vitro experiments showed that exposure to high glucose concentrations enhanced EP4 expression in rat peritoneal mesothelial cells (RPMCs). High-glucose-induced expression of inflammatory cytokines (monocyte chemoattractant protein-1, tumour necrosis factor α, and interleukin 1β) was significantly reduced in RPMCs treated with ONO-AE3-208, an EP4 receptor antagonist. ONO-AE3-208 also significantly decreased the expression of extracellular matrix proteins induced by high glucose concentrations. Furthermore, ONO-AE3-208 blunted activation of the NLR family pyrin domain containing 3 (NLRP3) inflammasome and phosphorylation of nuclear factor kappa B (NF-κB) (p-p65). To further investigate the functional role of EP4, ONO-AE3-208 was administrated for 4weeks in a rat model of PD, the results of which showed that ONO-AE3-208 inhibited peritoneal fibrosis and improved peritoneal dysfunction. Additionally, inflammatory cytokines in the peritoneum of PD rats treated with ONO-AE3-208 were downregulated, in line with inhibition of the NLRP3 inflammasome and NF-κB phosphorylation. In conclusion, an EP4 antagonist reduced the development of peritoneal fibrosis, possibly by suppressing NLRP3 inflammasome- and p-p65-mediated inflammatory responses. Our findings suggest that an EP4 antagonist may be therapeutically beneficial for PD-associated peritoneal fibrosis.

Prostanoid receptors in hyperfiltration-mediated glomerular injury: Novel agonists and antagonists reveal opposing roles for EP2 and EP4 receptors.

Increased fluid-flow shear stress (FFSS) contributes to hyperfiltration-induced podocyte and glomerular injury resulting in progression of chronic kidney disease (CKD). We reported that increased FFSS in vitro and in vivo upregulates PGE2 receptor EP2 (but not EP4 expression), COX2-PGE2 -EP2 axis, and EP2-linked Akt-GSK3β-β-catenin signaling pathway in podocytes. To understand and use the disparities between PGE2 receptors, specific agonists, and antagonists of EP2 and EP4 were used to assess phosphorylation of Akt, GSK3β and β-catenin in podocytes using Western blotting, glomerular filtration barrier function using in vitro albumin permeability (Palb ) assay, and mitigation of hyperfiltration-induced injury in unilaterally nephrectomized (UNX) mice at 1 and 6 months. Results show an increase in Palb by PGE2 , EP2 agonist (EP2AGO ) and EP4 antagonist (EP4ANT ), but not by EP2 antagonist (EP2ANT ) or EP4 agonist (EP4AGO ). Pretreatment with EP2ANT blocked the effect of PGE2 or EP2AGO on Palb . Modulation of EP2 and EP4 also induced opposite effects on phosphorylation of Akt and β-Catenin. Individual agonists or antagonists of EP2 or EP4 did not induce significant improvement in albuminuria in UNX mice. However, treatment with a combination EP2ANT + EP4AGO for 1 or 6 months caused a robust decrease in albuminuria. EP2ANT + EP4AGO combination did not impact adaptive hypertrophy or increased serum creatinine. Observed differences between expression of EP2 and EP4 on the glomerular barrier highlight these receptors as potential targets for intervention. Safe and effective mitigating effect of EP2ANT + EP4AGO presents a novel opportunity to delay the progression of hyperfiltration-associated CKD as seen in transplant donors.

Mechanisms by which dupilumab normalizes eicosanoid metabolism and restores aspirin-tolerance in AERD: A hypothesis

Aspirin-exacerbated respiratory disease (AERD) is associated with overproduction of proinflammatory cysteinyl leukotrienes (CysLTs), defective generation of anti-inflammatory prostaglandin E2 (PGE2), and reduced expression of the EP2 receptor for PGE2. Reduced PGE2 synthesis results from the downregulation of inducible COX-2. Because PGE2 signaling via EP2 inhibits the 5-lipoxygenase/leukotriene C4 synthase-dependent pathway, the deficient levels of both PGE2 and EP2 likely contribute to the excessive baseline production of cysteinyl leukotrienes in patients with AERD compared with in patients with aspirin-tolerant asthma. The COX-2 pathway is regulated by an autocrine metabolic loop involving IL-1β, IL-1 receptor type I, EP2, COX-2, membrane-bound PGE2 prostaglandin E2 synthase-1, and PGE2. Previous studies reported that this metabolic loop is dysregulated in patients with AERD. When the downexpressed EP2 receptor is normalized, the entire loop returns to its normal function. Cotreatment of airway cells from healthy subjects with IL-4 and IFN-γ induces alterations in the metabolic loop similar to those seen in patients with AERD. In these patients, IL-4, which is produced in excess in airways of patients with AERD, likely contributes to the alteration of normal functioning of the autocrine metabolic loop involving IL-1β, IL-1 receptor type I, EP2, COX-2, membrane-bound PGE2 prostaglandin E2 synthase-1, and PGE2. We hypothesized that by blocking IL-4 action, dupilumab normalizes EP2 expression and restores the normal functioning of the COX-2 pathway autocrine metabolic loop, thereby normalizing the synthesis of PGE2 and restoring aspirin tolerance.

Dynamics of action of a Lys-49 and an Asp-49 PLA2s on inflammasome NLRP3 activation in murine macrophages

Phospholipases A2 (PLA2s) are proteins found in snake venoms with hemolytic, anticoagulant, myotoxic, edematogenic, bactericidal and inflammatory actions. In Bothrops jararacussu snake venom were isolated a Lys49-PLA2 (BthTX-I) and an Asp49-PLA2 (BthTX-II) with myotoxic and inflammatory actions. Both PLA2s can activate the NLRP3 inflammasome, an intracytoplasmic platform that recognizes molecules released when tissue is damaged liberating IL-1β that contributes to the inflammatory response observed in envenoming. The dynamic of action of BthTX-I and BthTX-II in both thioglycollate (TG)-elicited macrophages and C2C12 myoblasts and the involvement of EP1 and EP2 receptors, and PGE2 in NLRP3 inflammasome activation were evaluated. Both toxins induced PGE2 liberation and inflammasome components (NLRP3, Caspase-1, ASC, IL-1β, and IL18), IL-6, P2X7, COX-1, COX-2, EP2 and EP4 gene expression in TG-elicited macrophages but not in C2C12 myoblasts. EP2 (PF04418948) and EP4 (GW627368X) inhibitors abolished this effect. Both PLA2s also induced NLRP3 inflammasome protein expression that was abolished with the inhibitors used. Immunofluorescence and IL-1β assays confirmed the NLRP3 activation in TG-elicited macrophages with the participation of both EP2 and EP4 receptors confirming their involvement in this effect. All in all, BthTX-I and BthTX-II activate macrophages and induce the NLRP3 inflammasome complex activation with the participation of the PGE2 via COX pathway and EP2 and EP4, both PGE2 receptors, contributing to the local inflammatory effects observed in envenoming.

New, potent, small molecule agonists of tyrosine kinase receptors attenuate dry eye disease.

Nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin3 (NT-3) bind to tyrosine kinase (Trk) receptors, TrkA, TrkB, and TrkC, respectively. This study investigated the efficacy of novel molecule agonists of Trk receptors in an in vivo model of dry eye disease (DED). Small molecule TrkC agonist (C1) and a pan-Trk agonist (pan) were synthesized for this. C57BL/6J mice were subjected to desiccating stress (DS) and received bilateral eye drops of C1, pan, or vehicle (2x/day). Dry eye signs, inflammation and expression of corneal barrier function, and conjunctival goblet cell (GC) densities were measured as part of the DED phenotype. Corneal epithelial lysates were collected for either western blot or RNA extraction. Extracted total RNAs were used for NanoString analyses. Immunofluorescent staining was performed on whole-mount corneas using anti-TNFAIP3 and anti-EP4 antibodies. Compared to vehicle, mice subjected to desiccating stress and treated with agonists pan and C1 showed improved corneal barrier function, while C1 also increased GC density. NanoString analyses revealed upregulation of specific mRNA transcripts (Ptger4, Tnfaip3, Il1a and Ptger4, Tlr3, Osal1) in pan- and C1-treated corneas compared to vehicle-treated corneas. Western blots showed that pan and C1 decreased vehicle-induced NFkB nuclear translocation after DS for one day and increased EP4 and TNFAIP3 protein levels after 5 days of DS in corneal epithelium lysates. We conclude that small-molecule agonists of Trk receptors improve DED by decreasing NFkB activation and increasing protein expression of anti-inflammatory molecules TNFAIP3 and EP4. Surprisingly, the most efficacious small molecule agonists were not TrkA selective but TrkC and panTrk, suggesting that wider exploration of TrkB and C and pan Trk agonists are warranted in efforts to treat DED.