TRPV4 Channel Signaling in Macrophages Promotes Gastrointestinal Motility via Direct Effects on Smooth Muscle Cells.

Intestinal macrophages are critical for gastrointestinal (GI) homeostasis, but our understanding of their role in regulating intestinal motility is incomplete. Here, we report that CX3C chemokine receptor 1-expressing muscularis macrophages (MMs) were required to maintain normal GI motility. MMs expressed the transient receptor potential vanilloid 4 (TRPV4) channel, which senses thermal, mechanical, and chemical cues. Selective pharmacologic inhibition of TRPV4 or conditional deletion of TRPV4 from macrophages decreased intestinal motility and was sufficient to reverse the GI hypermotility that is associated with chemotherapy treatment. Mechanistically, stimulation of MMs via TRPV4 promoted the release of prostaglandin E2 and elicited colon contraction in a paracrine manner via prostaglandin E receptor signaling in intestinal smooth muscle cells without input from the enteric nervous system. Collectively, our data identify TRPV4-expressing MMs as an essential component required for maintaining normal GI motility and provide potential drug targets for GI motility disorders.

Exploring the roles of prostanoids, leukotriens, and dietary fatty acids in cutaneous inflammatory diseases: Insights from pharmacological and genetic approaches.

Prostanoids and leukotrienes (LTs) are representative of ω6 fatty acid-derived metabolites that exert their actions through specific receptors on the cell surface. These lipid mediators, being unstable in vivo, act locally at their production sites; thus, their physiological functions remain unclear. However, recent pharmacological and genetic approaches using experimental murine models have provided significant insights into the roles of these lipid mediators in various pathophysiological conditions, including cutaneous inflammatory diseases. These lipid mediators act not only through signaling by themselves but also by potentiating the signaling of other chemical mediators, such as cytokines and chemokines. For instance, prostaglandin E2 -EP4 and LTB4 -BLT1 signaling on cutaneous dendritic cells substantially facilitate their chemokine-induced migration ability into the skin and play critical roles in the priming and/or activation of antigen-specific effector T cells in the skin. In addition to these ω6 fatty acid-derived metabolites, various ω3 fatty acid-derived metabolites regulate skin immune cell functions, and some exert potent anti-inflammatory functions. Lipid mediators act as modulators of cutaneous immune responses, and manipulating the signaling from lipid mediators has the potential as a novel therapeutic approach for human skin diseases.

PGE2 -EP3 axis promotes brown adipose tissue formation through stabilization of WTAP RNA methyltransferase.

Brown adipose tissue (BAT) functions as a thermogenic organ and is negatively associated with cardiometabolic diseases. N6 -methyladenosine (m6 A) modulation regulates the fate of stem cells. Here, we show that the prostaglandin E2 (PGE2 )-E-prostanoid receptor 3 (EP3) axis was activated during mouse interscapular BAT development. Disruption of EP3 impaired the browning process during adipocyte differentiation from pre-adipocytes. Brown adipocyte-specific depletion of EP3 compromised interscapular BAT formation and aggravated high-fat diet-induced obesity and insulin resistance in vivo. Mechanistically, activation of EP3 stabilized the Zfp410 mRNA via WTAP-mediated m6 A modification, while knockdown of Zfp410 abolished the EP3-induced enhancement of brown adipogenesis. EP3 prevented ubiquitin-mediated degradation of WTAP by eliminating PKA-mediated ERK1/2 inhibition during brown adipocyte differentiation. Ablation of WTAP in brown adipocytes abrogated the protective effect of EP3 overexpression in high-fat diet-fed mice. Inhibition of EP3 also retarded human embryonic stem cell differentiation into mature brown adipocytes by reducing the WTAP levels. Thus, a conserved PGE2 -EP3 axis promotes BAT development by stabilizing WTAP/Zfp410 signaling in a PKA/ERK1/2-dependent manner.

PGE2-EP4 signaling steers cDC2 maturation toward the induction of suppressive T-cell responses.

Dendritic cells (DCs) shape adaptive immunity in response to environmental cues such as cytokines or lipid mediators, including prostaglandin E2 (PGE2). In cancer, tumors are known to establish an enriched PGE2 microenvironment. Tumor-derived PGE2 primes regulatory features across immune cells, including DCs, facilitating tumor progression. PGE2 shapes DC function by providing signaling via its two so-called E-prostanoid receptors (EPs) EP2 and EP4. Although studies with monocyte-derived DCs have shown the importance of PGE2 signaling, the role of PGE2-EP2/EP4 on conventional DCs type 2 (cDC2s), is still poorly defined. In this study, we investigated the function of EP2 and EP4 using specific EP antagonists on human cDC2s. Our results show that EP2 and EP4 exhibit different functions in cDC2s, with EP4 modulating the upregulation of activation markers (CD80, CD86, CD83, MHC class II) and the production of IL-10 and IL-23. Furthermore, PGE2-EP4 boosts CCR type 7-based migration as well as a higher T-cell expansion capacity, characterized by the enrichment of suppressive rather than pro-inflammatory T-cell populations. Our findings are relevant to further understanding the role of EP receptors in cDC2s, underscoring the benefit of targeting the PGE2-EP2/4 axis for therapeutic purposes in diseases such as cancer.

Inducible Deletion of the Prostaglandin EP3 Receptor in Kidney Tubules of Male and Female Mice Has No Major Effect on Water Homeostasis.

The prostaglandin E2 (PGE2) receptor EP3 has been detected in the thick ascending limb (TAL) and the collecting duct of the kidney, where its actions are proposed to inhibit water reabsorption. However, EP3 is also expressed in other cell types, including vascular endothelial cells. The aim here was to determine the contribution of EP3 in renal water handling in male and female adult mice by phenotyping a novel mouse model with doxycycline-dependent deletion of EP3 throughout the kidney tubule (EP3-/- mice). RNAscope demonstrated that EP3 was highly expressed in the cortical and medullary TAL of adult mice. Compared to controls EP3 mRNA expression was reduced by >80% in whole kidney (RT-qPCR) and non-detectable (RNAscope) in renal tubules of EP3-/- mice. Under basal conditions, there were no significant differences in control and EP3-/- mice of both genders in food and water intake, bodyweight, urinary output or clinical biochemistries. No differences were detectable between genotypes in handling of an acute water load, or in their response to the vasopressin analogue dDAVP. No differences in water handling were observed when PGE2 production was enhanced using a 1% NaCl load. Expression of proteins involved in kidney water handling were not different between genotypes. This study demonstrates that renal tubular EP3 is not essential for body fluid homeostasis in males or females, even when PGE2 levels are high. The mouse model is a novel tool for examining the role of EP3 in kidney function independently of potential developmental abnormalities or systemic effects.

Comparison of the Genomic Activity of an EP4-Receptor and ß2-Adrenoceptor Agonist in BEAS-2B Human Bronchial Epithelial Cells: In Search of Compartmentalized, cAMP-dependent Gene Expression.

It has been proposed that inhaled EP4-receptor agonists could represent an new class of bronchodilators for the treatment of asthma that are as effective as ß2-adrenoceptor agonists. However, the genomic impact of such drugs is unknown despite being potentially deleterious to respiratory health. Herein, we used mRNA-seq to compare the transcriptomic responses produced by ONO-AE1-329 (an EP4-receptor agonist) and vilanterol (a ß2-adrenoceptor agonist) in BEAS-2B human airway epithelial cells. We also determined if an increase in cAMP mediated by different GPCRs promoted distinct transcriptional signatures by expanding this enquiry to include the adenosine A2B- and I-prostanoid receptor agonists, Bay-60-6583 and taprostene, respectively. Maximally-effective concentrations of ONO-AE1-329 and vilanterol significantly regulated (q{less than or equal to}0.05; {greater than or equal to}1.5-/{less than or equal to}0.67-fold) 232 and 320 genes, respectively of which 217 were shared. Spearman analysis showed these gene expression changes to be highly rank order correlated indicating that the functional overlap between the two interventions should be considerable. Unexpectedly, the genomic effects of ONO-AE1-329, vilanterol, Bay 60-6583 and taprostene were also highly rank order correlated. This finding raises the prospect that cAMP generated by any GPCR would initiate the same transcriptional program. Nevertheless, relative to vilanterol, ONO-AE1-329 typically behaved as a partial agonist that varied across transcripts. These data indicate that each ONO-AE1-329-regulated gene differs in sensitivity to cAMP and is defined by a unique receptor occupancy-response relationship. Moreover, if this relatively modest genomic response in BEAS-2B cells is retained in vivo, then inhaled EP4-receptor agonists could represent an alternative, and possibly safer, class of bronchodilators. Significance Statement The genomic consequences of ß2-adrenoceptor agonists in asthma are often overlooked despite being potentially harmful to lung health. We determined that ONO-AE1-329, an EP4-receptor agonist and effective bronchodilator, produced gene expression changes in BEAS-2B cells that were typically modest relative to the ß2-adrenoceptor agonist, vilanterol. Furthermore, ONO-AE1-329 behaved as a partial agonist that varied across transcripts. If this genomic activity is reproduced in vivo, then EP4-receptor agonists could represent an alternative, and possibly safer, class of bronchodilators.

Safety and Effectiveness of Selexipag in Pediatric Pulmonary Hypertension: A Retrospective Multi-Center Cohort Study.

OBJECTIVE: To describe the safety and effectiveness of treating pediatric patients who have pulmonary arterial hypertension (PAH) with selexipag in a real-world, multi-center cohort, given that data supporting its use in pediatric PAH are sparse. STUDY DESIGN: We report a multi-center, retrospective, cohort study of children with PAH treated with selexipag. Demographic and clinical variables were extracted from the medical records. Clinical parameters were analyzed at 3 timepoints: pre-selexipag, 3-12 months post-selexipag, and >12 months follow-up. RESULTS: Eighty-seven patients were included, 32 received selexipag as add-on to background therapy, and 55 transitioned from another prostanoid. Median starting and final doses were 4.7 and 28.5 µg/kg/dose BID, respectively. Add-on patients demonstrated improved indexed pulmonary to systemic vascular resistance ratio after selexipag initiation (PVRi/SVRi, 0.62v0.53, p=0.034) with a lower average mean pulmonary artery pressure (MPAP, 46v39 mmHg, p=NS), and oxygen consumption (VO2 max 27.8v30.9 mL/kg/min, p=NS). Transition patients demonstrated stable MPAP (47v45 mmHg, p=NS) and a lower mean PVRi (10.9v8.2 Wood units*m2, p=NS) but late functional worsening in some with VO2 max decreased at follow-up (26.0v19.5 ml/kg/min). Side effects were noted in 40% of the cohort but prompted discontinuation in only 2%. CONCLUSIONS: In a large, multi-center cohort, the oral prostacyclin agonist selexipag demonstrates favorable tolerability and effectiveness. Add-on patients demonstrated early hemodynamic improvement. Transition patients demonstrated early stability with risk of late functional worsening, highlighting the importance of ongoing monitoring.

Alterations of Prostanoid Expression and Intestinal Epithelial Barrier Functions in Ileus.

INTRODUCTION: Intestinal manipulation (IM)-induced inflammation could contribute to postoperative ileus (POI) pathophysiology via the modulation of prostanoid pathways. To identify the prostanoids involved, we aimed to characterize the profile of prostanoids and their synthesis enzyme expression in a murine model of POI and to determine whether the altered prostanoids could contribute to POI. METHODS: Four or 14 h after IM in mice, gastrointestinal (GI) motility and intestinal epithelial barrier (IEB) permeability were assessed in vivo and ex vivo in Ussing chambers. Using high sensitivity liquid chromatography-tandem mass spectrometry, we characterized the tissue profile of polyunsaturated fatty acid metabolites in our experimental model. Finally, we evaluated in vivo the effects of the prostanoids studied upon IM-induced gut dysfunctions. RESULTS: We first showed that 14 h after IM was significantly faster than jejunal transit at 4 h post-IM, although it remained significantly increased compared to the control. In contrast, we showed that IM-induced inflammation increase in jejunum permeability was similar after four and 14 h. We next showed that expression of prostacyclin synthase and hemopoietic prostaglandin-D synthase mRNA and their products were significantly reduced 14 h after IM as compared to controls. Furthermore, 15-deoxy-delta 12,14-Prostaglandin J2 reduced the IM-induced inflammation increase in IEB permeability but had no effect on GI motility. In contrast, PGI2 increased IM-induced IEB permeability and motility dysfunctions. CONCLUSIONS: Arachidonic acid derivative contributes differentially to GI dysfunction in POI. The decrease of 15-deoxy-delta 12,14-Prostaglandin J2 levels induced by IM could contribute to impaired GI dysfunctions in POI and could be considered as putative therapeutic targets to restore barrier dysfunctions associated with POI.

Alpha-linolenic acid selectively inhibits the contraction of pig coronary arteries mediated through prostanoid TP receptors.

We examined the inhibitory effects of α-linolenic acid (ALA) on the contractions of pig coronary arteries. ALA concentration-dependently inhibited the contractions elicited by U46619 and prostaglandin F2α without affecting those elicited by 80 mM KCl, histamine, acetylcholine, and serotonin. ALA rightward shifted the concentration-response curve of U46619, and Schild plot analysis revealed that ALA competitively antagonized U46619. Furthermore, ALA inhibited the increase in intracellular Ca2+ concentration caused by TP receptor stimulation but not that caused by FP receptor stimulation. These results suggest that ALA behaves as a selective antagonist of TP receptors in coronary arteries.

Marine Prostanoids with Cytotoxic Activity from Octocoral Clavularia spp.

Octocoral of the genus Clavularia is a kind of marine invertebrate possessing abundant cytotoxic secondary metabolites, such as prostanoids and dolabellanes. In our continuous natural product study of C. spp., two previously undescribed prostanoids [clavulone I-15-one (1) and 12-O-deacetylclavulone I (2)] and eleven known analogs (3-13) were identified. The structures of these new compounds were elucidated based on analysis of their 1D and 2D NMR, HRESIMS, and IR data. Additionally, all tested prostanoids (1 and 3-13) showed potent cytotoxic activities against the human oral cancer cell line (Ca9-22). The major compound 3 showed cytotoxic activity against the Ca9-22 cells with the IC50 value of 2.11 ± 0.03 µg/mL, which echoes the cytotoxic effect of the coral extract. In addition, in silico tools were used to predict the possible effects of isolated compounds on human tumor cell lines and nitric oxide production, as well as the pharmacological potentials.

Nonsteroidal anti-inflammatory drugs and implications for the cyclooxygenase pathway in embryonic development.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are a class of analgesics that inhibit the activity of cyclooxygenase isoenzymes, which drive tissue inflammation pathways. Caution should be exercised when taking these drugs during pregnancy as they increase the risk of developmental defects. Due to the high rates of NSAID use by individuals, possibilities for in utero exposure to NSAIDs are high, and it is vital that we define the potential risks these drugs pose during embryonic development. In this review, we characterize the identified roles of the cyclooxygenase signaling pathway components throughout pregnancy and discuss the effects of cyclooxygenase pathway perturbation on developmental outcomes.

Prostaglandin F2α evokes vasoconstrictor and vasodepressor activities that are both independent of the F prostanoid receptor.

The F prostanoid receptor (FP), which accounts for the therapeutic effect of PGF2α in uterine atony that leads to postpartum hemorrhage and maternal morbidity, could possibly mediate vasoconstrictor effect in small or resistance arteries to elevate blood pressure that limits the clinical use of the agent in patients with cardiovascular disorders. This study aimed to test the above hypothesis with genetically altered mice. Ex vivo and in vivo experiments were performed on control wild-type (WT) mice and mice with deficiencies in FP (FP-/- ) or thromboxane (Tx)-prostanoid receptor (the original receptor of TxA2 ; TP-/- ), and/or those with an additional deficiency in E prostanoid receptor-3 (one of the vasoconstrictor receptors of PGE2 ; EP3-/- ). Here, we show that PGF2α indeed evoked vasoconstrictor responses in the above-mentioned tissues of WT mice, which were however unaltered by FP-/- . Interestingly, such contractile responses were reversed into dilations by TP-/- /EP3-/- . A similar pattern of results was observed with the pressor effect of PGF2α under in vivo conditions. However, TP-/- alone (which could largely remove the contractile responses) did not result in relaxation to PGF2α . Also, either the ex vivo vasodilator effect or the in vivo depressor response of PGF2α obtained after the removal of TP and EP3-mediated actions was unaltered by FP-/- . Therefore, both the ex vivo vasoconstrictor action in small or resistance arteries and the systemic pressor effect of PGF2α can reflect vasoconstrictor activities derived from the non-FP receptors TP and EP3 outweighing a concurrently activated dilator effect, which is again independent of FP.

Development of fluorescent peptide G protein-coupled receptor activation biosensors for NanoBRET characterization of intracellular allosteric modulators.

G protein-coupled receptors (GPCRs) are widely therapeutically targeted, and recent advances in allosteric modulator development at these receptors offer further potential for exploitation. Intracellular allosteric modulators (IAM) represent a class of ligands that bind to the receptor-effector interface (e.g., G protein) and inhibit agonist responses noncompetitively. This potentially offers greater selectivity between receptor subtypes compared to classical orthosteric ligands. However, while examples of IAM ligands are well described, a more general methodology for assessing compound interactions at the IAM site is lacking. Here, fluorescent labeled peptides based on the Gα peptide C terminus are developed as novel binding and activation biosensors for the GPCR-IAM site. In TR-FRET binding studies, unlabeled peptides derived from the Gαs subunit were first characterized for their ability to positively modulate agonist affinity at the ß2 -adrenoceptor. On this basis, a tetramethylrhodamine (TMR) labeled tracer was synthesized based on the 19 amino acid Gαs peptide (TMR-Gαs19cha18, where cha = cyclohexylalanine). Using NanoBRET technology to detect binding, TMR-Gαs19cha18 was recruited to Gs coupled ß2 -adrenoceptor and EP2 receptors in an agonist-dependent manner, but not the Gi-coupled CXCR2 receptor. Moreover, NanoBRET competition binding assays using TMR-Gαs19cha18 enabled direct assessment of the affinity of unlabeled ligands for ß2 -adrenoceptor IAM site. Thus, the NanoBRET platform using fluorescent-labeled G protein peptide mimetics offers novel potential for medium-throughput screens to identify IAMs, applicable across GPCRs coupled to a G protein class. Using the same platform, Gs peptide biosensors also represent useful tools to probe orthosteric agonist efficacy and the dynamics of receptor activation.

Pharmacological study on the enhancing effects of U46619 on guinea pig urinary bladder smooth muscle contraction induced by acetylcholine and α,ß-methylene ATP and the possible involvement of protein kinase C.

We examined whether U46619 (a prostanoid TP receptor agonist) could enhance the contractions of guinea pig urinary bladder smooth muscle (UBSM) in response to acetylcholine (ACh) and an ATP analog (α,ß-methylene ATP (αß-MeATP)) through stimulation of the UBSM TP receptor and whether protein kinase C (PKC) is involved. U46619 (10-7 M) markedly enhanced UBSM contractions induced by electrical field stimulation and ACh/αß-MeATP (3 × 10-6 M each), the potentiation of which was completely suppressed by SQ 29,548 (a TP receptor antagonist, 6 × 10-7 M). PKC inhibitors did not attenuate the ACh-induced contractions enhanced by U46619 although they partly suppressed the U46619-enhanced, αß-MeATP-induced contractions. While phorbol 12-myristate 13-acetate (PMA, a PKC activator, 10-6 M) did not enhance ACh-induced contractions, it enhanced αß-MeATP-induced contractions, an effect that was completely suppressed by PKC inhibitors. αß-MeATP-induced contractions, both with and without U46619 enhancement, were strongly inhibited by diltiazem. U46619/PMA enhanced 50 mM KCl-induced contractions, the potentiation of which was partly/completely attenuated by PKC inhibitors. These findings suggest that U46619 potentiates parasympathetic nerve-associated UBSM contractions by stimulating UBSM TP receptors. PKC-increased Ca2+ influx through voltage-dependent Ca2+ channels may partially play a role in purinergic receptor-mediated UBSM contractions enhanced by TP receptor stimulation.

Thromboxane-Prostanoid Receptor Signaling Drives Persistent Fibroblast Activation in Pulmonary Fibrosis.

Rationale: Although persistent fibroblast activation is a hallmark of idiopathic pulmonary fibrosis (IPF), mechanisms regulating persistent fibroblast activation in the lungs have not been fully elucidated. Objectives: On the basis of our observation that lung fibroblasts express TBXA2R (thromboxane-prostanoid receptor) during fibrosis, we investigated the role of TBXA2R signaling in fibrotic remodeling. Methods: We identified TBXA2R expression in lungs of patients with IPF and mice and studied primary mouse and human lung fibroblasts to determine the impact of TBXA2R signaling on fibroblast activation. We used TBXA2R-deficient mice and small-molecule inhibitors to investigate TBXA2R signaling in preclinical lung fibrosis models. Measurements and Main Results: TBXA2R expression was upregulated in fibroblasts in the lungs of patients with IPF and in mouse lungs during experimental lung fibrosis. Genetic deletion of TBXA2R, but not inhibition of thromboxane synthase, protected mice from bleomycin-induced lung fibrosis, thereby suggesting that an alternative ligand activates profibrotic TBXA2R signaling. In contrast to thromboxane, F2-isoprostanes, which are nonenzymatic products of arachidonic acid induced by reactive oxygen species, were persistently elevated during fibrosis. F2-isoprostanes induced TBXA2R signaling in fibroblasts and mediated a myofibroblast activation profile due, at least in part, to potentiation of TGF-ß (transforming growth factor-ß) signaling. In vivo treatment with the TBXA2R antagonist ifetroban reduced profibrotic signaling in the lungs, protected mice from lung fibrosis in three preclinical models (bleomycin, Hermansky-Pudlak mice, and radiation-induced fibrosis), and markedly enhanced fibrotic resolution after bleomycin treatment. Conclusions: TBXA2R links oxidative stress to fibroblast activation during lung fibrosis. TBXA2R antagonists could have utility in treating pulmonary fibrosis.

Continuous Prostanoid Initiation in Severe Pulmonary Hypertension in the Pediatric Cardiac Intensive Care Unit.

OBJECTIVE: Limited data exists regarding prostanoid (PGI2) use in critically ill patients with pulmonary hypertension. (PH) in the pediatric cardiac intensive care unit (CICU) setting. MATERIALS AND METHODS: Single center, retrospective study of patients with diagnosis of PH who received continuous PGI2 and were admitted to CICU from January/2015 to April/2022. Data collected included patient demographics and clinical characteristics including diagnosis, etiology of PH, vasoactive and ventilatory support, length of stay, and survival. Type, initial, maximum, and final dose of PGI2 as well as hemodynamic data was obtained. Data reported as mean ± standard deviation. Significance taken p value < 0.05. RESULTS: 24 patients received PGI2 therapy at a mean age of 3.1 years, range (0-16.6 years). PGI2 was in the form of IV epoprostenol in 12 patients, IV treprostinil in 6, and SQ treprostinil in 6 patients. Mean initial dose was 2.79 ng/kg/min, max dose 18.75 ng/kg/min, and mean duration of therapy was 38.5 days. At PGI2 initiation, 21 (87.5%) were on vasoactive infusions, 19 (79.2%) mechanically ventilated (MV), and 6 (25%) were on extracorporeal membrane oxygenation (ECMO). The in-hospital mortality rate was 37.5% (n = 9). Patients MV and on ECMO support had higher risk of death (p = 0.04, and < 0.01, respectively). CONCLUSION: PGI2 therapy was tolerated in approximately 50% of patients with the most common side effect being hypotension leading to discontinuation in 1/3rd of patients. Ongoing evaluation of the benefits of PGI2 for patients in the CICU setting will help better identify patient selection, type, and dosing of PGI2.

Enhancement of Sphingomyelinase-Induced Endothelial Nitric Oxide Synthase-Mediated Vasorelaxation in a Murine Model of Type 2 Diabetes.

Sphingolipids are important biological mediators both in health and disease. We investigated the vascular effects of enhanced sphingomyelinase (SMase) activity in a mouse model of type 2 diabetes mellitus (T2DM) to gain an understanding of the signaling pathways involved. Myography was used to measure changes in the tone of the thoracic aorta after administration of 0.2 U/mL neutral SMase in the presence or absence of the thromboxane prostanoid (TP) receptor antagonist SQ 29,548 and the nitric oxide synthase (NOS) inhibitor L-NAME. In precontracted aortic segments of non-diabetic mice, SMase induced transient contraction and subsequent weak relaxation, whereas vessels of diabetic (Leprdb/Leprdb, referred to as db/db) mice showed marked relaxation. In the presence of the TP receptor antagonist, SMase induced enhanced relaxation in both groups, which was 3-fold stronger in the vessels of db/db mice as compared to controls and could not be abolished by ceramidase or sphingosine-kinase inhibitors. Co-administration of the NOS inhibitor L-NAME abolished vasorelaxation in both groups. Our results indicate dual vasoactive effects of SMase: TP-mediated vasoconstriction and NO-mediated vasorelaxation. Surprisingly, in spite of the general endothelial dysfunction in T2DM, the endothelial NOS-mediated vasorelaxant effect of SMase was markedly enhanced.

Effects of R-flurbiprofen and the oxygenated metabolites of endocannabinoids in inflammatory pain mice models.

Pain is one of the cardinal signs accompanying inflammation. The prostaglandins (PGs), synthetized from arachidonic acid by cyclooxygenase (COX)-2, are major bioactive lipids implicated in inflammation and pain. However, COX-2 is also able to metabolize other lipids, including the endocannabinoids 2-arachidonoylglycerol (2-AG) and anandamide (AEA), to give glycerol ester (PG-G) and ethanolamide (PG-EA) derivatives of the PGs. Consequently, COX-2 can be considered as a hub not only controlling PG synthesis, but also PG-G and PG-EA synthesis. As they were more recently characterized, these endocannabinoid metabolites are less studied in nociception compared to PGs. Interestingly R-profens, previously considered as inactive enantiomers of nonsteroidal anti-inflammatory drugs (NSAIDs), are substrate-selective COX inhibitors. Indeed, R-flurbiprofen can selectively block PG-G and PG-EA production, without affecting PG synthesis from COX-2. Therefore, we compared the effect of R-flurbiprofen and S-flurbiprofen in models of inflammatory pain triggered by local administration of lipopolysaccharides (LPS) and carrageenan in mice. Remarkably, the effects of flurbiprofen enantiomers on mechanical hyperalgesia seem to depend on (i) the inflammatory stimuli, (ii) the route of administration, and (iii) the timing of administration. We also assessed the effect of administration of the PG-Gs, PG-EAs, and PGs on LPS-induced mechanical hyperalgesia. Our data support the interest of studying the nonhydrolytic endocannabinoid metabolism in the context of inflammatory pain.

The Biased Activities of Prostanoids and Their Receptors: Review and Beyond.

Since the discovery of ß-arrestin, a new concept/viewpoint has arisen in G-protein coupled receptor (GPCR)-mediated signaling. The Lock and Key concept of GPCR was previously recognized as basically a single- or mono-originated pathway activated from a single receptor. However, the new concept/viewpoint allows for many- or more-than-one-originated pathways activated from a single receptor; namely, biased activities. It is well-recognized that prostanoids exhibit preferences for their corresponding cognate receptors, while promiscuous cross-reactivities have also been reported among endogenous prostanoids and their receptor family. However, of particular interest, such cross-reactivities have led to reports of their physiologically significant roles. Thus, this review discusses and considers that the endogenous prostanoids are not showing random cross-reactivities but what are showing important physiological and pathological activities as biased ligands. Moreover, why and how the biased activities are evoked by endogenous structurally similar prostanoid ligands are discussed. Furthermore, when the biased activities of endogenous prostanoids first arose is also discussed and considered. These biased activities of endogenous prostanoids are also discussed from the perspective that they may provide many benefits and/or disadvantages for all living things, any-where on this planet, who/which are utilizing, had utilized, and will utilize the prostanoids and their receptor system, as a marked driving force for evolution.

Metabolic Regulation in Adipocytes by Prostanoid Receptors.

Prostanoids are a group of typical lipid mediators that are biosynthesized from arachidonic acid by the actions of cyclooxygenases and their subsequent terminal synthases. Prostanoids exert a wide variety of actions through their specific membrane receptors on target cells. In addition to their classical actions, including fever, pain, and inflammation, prostanoids have been shown to play pivotal roles in various biological processes, such as female reproduction and the maintenance of vascular and gut homeostasis. Moreover, recent research using mice deficient in each of the prostanoid receptors, or using agonists/antagonists specific for each receptor clarified novel actions of prostanoids that had long been unknown, and the mechanisms therein. In this review, we introduce recent advances in the fields of metabolic control by prostanoid receptors such as in adipocyte differentiation, lipolysis, and adipocyte browning in adipose tissues, and discuss the potential of prostanoid receptors as a treatment target for metabolic disorders.