Antidiarrheal activity of Bridelia ferruginea bark methanolic extract involves modulation ATPases in mice and inhibition of muscarinic acetylcholine receptor (M3) and prostaglandin E2 receptor 3 (EP3) in silico

Objectives Diarrhea, an abnormal state in which the individual has about three or more daily bowel movements, is now considered one of the most challenging global public health problems. Using plant products, such as Bridelia ferruginea is an alternative treatment option. The objective of this study was to investigate the antidiarrheal activity of B. ferruginea bark methanolic extract (BfME) and the mechanisms involved. Methods BfME antidiarrheal activity was evaluated in mice model of castor oil-induced diarrhea and enteropooling. To evaluate motility, gastrointestinal transit time was carried out using phenol red meal, while intestinal activities of selected ATPases were also evaluated. Furthermore, the active components in BfME were detected by GC-MS analysis, while molecular docking of the most abundant compounds with muscarinic acetylcholine receptor (M3) and prostaglandin E2 receptor 3 (EP3) were conducted. Results BfME at 400 and 800 mg/kg showed antidiarrheal activity by delaying onset of diarrhea, reduced gastrointestinal transit and increased intestinal activities of Na+ K+-ATPase, Ca2+ Mg2+-ATPase and Mg2+-ATPase. Molecular docking revealed that γ-sitosterol, α-amyrin, and stigmasterol have outstanding binding affinity for M3 and EP3. Conclusions In view of these results, the observed antidiarrheal activity possibly occurs via the activation of ATPases activities and inhibition of M3 and EP3.

Therapeutic role of Prostaglandin E2 receptor 4 stimulation in inflammatory cardiomyopathy

Background Prostaglandin E2 receptor 4 (EP4) plays a crucial role in inflammatory diseases. Inflammatory cardiomyopathy often leads to refractory heart failure. Purpose We aimed to evaluate the role of EP4 in the development of inflammatory cardiomyopathy. Methods Experimental autoimmune myocarditis (EAM) was induced by immunization with cardiac myosin in balb/c mice. EP4 selective antagonist (CJ-42794, Cayman Chemical: 30 mg/kg/day), EP4 selective agonist (20 mg/kg/day), both, or vehicle alone was daily administrated after the immunization. Cardiac function and dimensions were assessed by echocardiography. Blood pressure and heart rate were assessed with tail-cuff method. Cardiac inflammation and fibrosis were immunohistologically examined. Molecular examination was performed by RT-PCR and immunoblotting. Results Cardiac dysfunction and dilatation were worsened on day 21 in EP4 antagonist-treated group compared with in the vehicle-treated group, accompanied by an increase in cellular infiltration area (21.7±1.9 vs. 11.0±2.7%, P=0.0367, respectively). Conversely, cardiac dysfunction and dilatation were improved in EP4 agonist-treated group compared with in the vehicle-treated group (Left ventricular fractional shortening: 69±3% vs. 40±4%, P<0.0001; Left ventricular systolic dimension: 0.7±0.1mm vs. 1.9±0.3mm, P=0.0007; respectively). These parameters did not show significant differences between both-treated group and the vehicle-treated group. The protective effect of EP4 stimulation in EAM was also kept on day 56. Moreover, cardiac fibrosis area as well as mRNA expressions of Type III collagen and brain natriuretic peptide in the bulk hearts was significantly reduced on day 56 in EP4 agonist-treated group compared with in the vehicle-treated group (12.3±2.4% vs. 24.7±3.0%, P=0.0278, respectively). Cardiac expression of phosphorylated smad 2/3 protein as well as TGF-β1 mRNA did not show significant differences between the 2 groups, while cardiac expression of RORgammat protein, the master regulator of Th17 immunity was increased in the EP4 antagonist-treated group. Conclusions EP4 activation negatively regulated the induction of cardiac autoimmunity, which alleviated cardiac dysfunction, dilatation, and fibrosis. EP4 may be a therapeutic target for preventing the development of inflammatory cardiomyopathy. FUNDunding Acknowledgement Type of funding sources: None.

Prostaglandin E2 Receptor 4 (EP4) Affects Trophoblast Functions via Activating the cAMP-PKA-pCREB Signaling Pathway at the Maternal-Fetal Interface in Unexplained Recurrent Miscarriage

Implantation consists of a complex process based on coordinated crosstalk between the endometrium and trophoblast. Furthermore, it is known that the microenvironment of this fetal–maternal interface plays an important role in the development of extravillous trophoblast cells. This is mainly due to the fact that tissues mediate embryonic signaling biologicals, among other molecules, prostaglandins. Prostaglandins influence tissue through several cell processes including differentiation, proliferation, and promotion of maternal immune tolerance. The aim of this study is to investigate the potential pathological mechanism of the prostaglandin E2 receptor 4 (EP4) in modulating extravillous trophoblast cells (EVTs) in unexplained recurrent marriage (uRM). Our results indicated that the expression of EP4 in EVTs was decreased in women experiencing uRM. Furthermore, silencing of EP4 showed an inhibition of the proliferation and induced apoptosis in vitro. In addition, our results demonstrated reductions in β- human chorionic gonadotropin (hCG), progesterone, and interleukin (IL)-6, which is likely a result from the activation of the cyclic adenosine monophosphate (cAMP)- cAMP-dependent protein kinase A (PKA)-phosphorylating CREB (pCREB) pathway. Our data might provide insight into the mechanisms of EP4 linked to trophoblast function. These findings help build a more comprehensive understanding of the effects of EP4 on the trophoblast at the fetal–maternal interface in the first trimester of pregnancy.

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

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

Prostaglandin-E2 Receptor-4 Stimulant Rescues Cardiac Malfunction during Myocarditis and Protects the Heart from Adverse Ventricular Remodeling after Myocarditis

Cardioprotective effect of prostaglandin-E2 receptor-4 (EP4) stimulation on the ischemic heart has been demonstrated. Its effect on the heart affected by myocarditis, however, remains uncertain. In this study, we investigated therapeutic effect of EP4 stimulant using a mouse model of autoimmune myocarditis (EAM) that progresses to dilated cardiomyopathy (DCM). EP4 was present in the hearts of EAM mice. Treatment with EP4 agonist (ONO-0260164: 20 mg/kg/day) improved an impaired left ventricular (LV) contractility and reduction of blood pressure on day 21, a peak myocardial inflammation. Alternatively, DCM phenotype, characterized by LV dilation, LV systolic dysfunction, and collagen deposition, without inflammatory profiles was observed on day 56, along with activation of matrix metalloproteinase (MMP) 2 critical for myocardial extracellular matrix disruption, indicating an important molecular mechanism underlying adverse ventricular remodeling after myocarditis. Continued treatment with ONO-0260164 alleviated the DCM phenotype, but this effect was counteracted by its combination with a EP4 antagonist. Moreover, ONO-0260164 inhibited in vivo proteolytic activity of MMP2 in association with up-regulation of tissue inhibitor of metalloproteinase (TIMP)-3. EP4 stimulant may be a promising and novel therapeutic agent that rescues cardiac malfunction during myocarditis and prevents adverse ventricular remodeling after myocarditis by promoting the TIMP3/MMP2 axis.

CD147 receptor is essential for TFF3-mediated signaling regulating colorectal cancer progression

Major gaps in understanding the molecular mechanisms of colorectal cancer (CRC) progression and intestinal mucosal repair have hampered therapeutic development for gastrointestinal disorders. Trefoil factor 3 (TFF3) has been reported to be involved in CRC progression and intestinal mucosal repair; however, how TFF3 drives tumors to become more aggressive or metastatic and how TFF3 promotes intestinal mucosal repair are still poorly understood. Here, we found that the upregulated TFF3 in CRC predicted a worse overall survival rate. TFF3 deficiency impaired mucosal restitution and adenocarcinogenesis. CD147, a membrane protein, was identified as a binding partner for TFF3. Via binding to CD147, TFF3 enhanced CD147-CD44s interaction, resulting in signal transducer and activator of transcription 3 (STAT3) activation and prostaglandin G/H synthase 2 (PTGS2) expression, which were indispensable for TFF3-induced migration, proliferation, and invasion. PTGS2-derived PGE2 bound to prostaglandin E2 receptor EP4 subtype (PTGER4) and contributed to TFF3-stimulated CRC progression. Solution NMR studies of the TFF3-CD147 interaction revealed the key residues critical for TFF3 binding and the induction of PTGS2 expression. The ability of TFF3 to enhance mucosal restitution was weakened by a PTGS2 inhibitor. Blockade of TFF3-CD147 signaling using competitive inhibitory antibodies or a PTGS2 inhibitor reduced CRC lung metastasis in mice. Our findings bring strong evidence that CD147 is a novel receptor for TFF3 and PTGS2 signaling is critical for TFF3-induced mucosal restitution and CRC progression, which widens and deepens the understanding of the molecular function of trefoil factors.

Myeloid-Derived Suppressor Cells Dampen Airway Inflammation Through Prostaglandin E2 Receptor 4

Emerging evidence suggests a mechanistic role for myeloid-derived suppressor cells (MDSCs) in lung diseases like asthma. Previously, we showed that adoptive transfer of MDSCs dampens lung inflammation in murine models of asthma through cyclooxygenase-2 and arginase-1 pathways. Here, we further dissected this mechanism by studying the role and therapeutic relevance of the downstream mediator prostaglandin E2 receptor 4 (EP4) in a murine model of asthma. We adoptively transferred MDSCs generated using an EP4 agonist in a murine model of asthma and studied the consequences on airway inflammation. Furthermore, pegylated human arginase-1 was used to model MDSC effector activities. We demonstrate that the selective EP4 agonist L-902,688 increased the number and suppressive activity of MDSCs through arginase-1 and nitric oxide synthase-2. These results showed that adoptive transfer of EP4-primed MDSCs, EP4 agonism alone or arginase-1 administration ameliorated lung inflammatory responses and histopathological changes in asthmatic mice. Collectively, our results provide evidence that MDSCs dampen airway inflammation in murine asthma through a mechanism involving EP4.

Inhibitory effects of a selective prostaglandin E2 receptor antagonist RQ-15986 on inflammation-related colon tumorigenesis in APC-mutant rats

Prostaglandin E2 receptor EP4 is involved in inflammation and related tumorigenesis in the colorectum. This study aimed to investigate the chemopreventive ability of RQ-15986, a selective EP4 antagonist, in colitis-related colorectal tumorigenesis. Male Kyoto APC delta rats, which have APC mutations, were treated with azoxymethane and dextran sulfate sodium and subsequently administered RQ-15986 for eight weeks. At the end of the experiment, the development of colorectal tumor was significantly inhibited in the RQ-15986-treated group. The cell proliferation of the crypts and tumors in the colorectum was decreased following RQ-15986 treatment. RQ-15986 also suppressed the expression of pro-inflammatory cytokines, including tumor necrosis factor-α, interleukin-6, interleukin-18, and monocyte chemotactic protein-1, in the colon mucosa. In addition, the expression levels of indoleamine 2,3-dioxygenase, which is involved in immune tolerance, were decreased in the colorectal epithelium and tumors of the RQ-15986-treated group. These findings indicate that RQ-15986 inhibits colitis-associated colorectal tumorigenesis by attenuating inflammation, suppressing cell proliferation, and modulating the expression of indoleamine 2,3-dioxygenase. Targeting prostaglandin E2/EP4 signaling might be a useful strategy for chemoprevention of inflammation-related colorectal cancer.