P2Y Receptors Research Articles

Age-related changes in P2Y receptor signalling in mouse cochlear supporting cells.

Our sense of hearing depends on the function of a specialised class of sensory cells, the hair cells, which are found in the organ of Corti of the mammalian cochlea. The unique physiological environment in which these cells operate is maintained by a syncitium of non-sensory supporting cells, which are crucial for regulating cochlear physiology and metabolic homeostasis. Despite their importance for cochlear function, the role of these supporting cells in age-related hearing loss, the most common sensory deficit in the elderly, is poorly understood. Here, we investigated the age-related changes in the expression and function of metabotropic purinergic receptors (P2Y1 , P2Y2 and P2Y4 ) in the supporting cells of the cochlear apical coil. Purinergic signalling in supporting cells is crucial during the development of the organ of Corti and purinergic receptors are known to undergo changes in expression during ageing in several tissues. Immunolabelling and Ca2+ imaging experiments revealed a downregulation of P2Y receptor expression and a decrease of purinergic-mediated calcium responses after early postnatal stages in the supporting cells. An upregulation of P2Y receptor expression was observed in the aged cochlea when compared to 1month-old adults. The aged mice also had significantly larger calcium responses and displayed calcium oscillations during prolonged agonist applications. We conclude that supporting cells in the aged cochlea upregulate P2Y2 and P2Y4 receptors and display purinergic-induced Ca2+ responses that mimic those observed during pre-hearing stages of development, possibly aimed at limiting or preventing further damage to the sensory epithelium. KEY POINTS: Age-related hearing loss is associated with lower hearing sensitivity and decreased ability to understand speech. We investigated age-related changes in the expression and function of metabotropic purinergic (P2Y) receptors in cochlear non-sensory supporting cells of mice displaying early-onset (C57BL/6N) and late-onset (C3H/HeJ) hearing loss. The expression of P2Y1 , P2Y2 and P2Y4 receptors in the supporting cells decreased during cochlear maturation, but that of P2Y2 and P2Y4 was upregulated in the aged cochlea. P2Y2 and P2Y4 receptors were primarily responsible for the ATP-induced Ca2+ responses in the supporting cells. The degree of purinergic expression upregulation in aged supporting cells mirrored hearing loss progression in the different mouse strains. We propose that the upregulation of purinergic-mediated signalling in the aged cochlea is subsequent to age-related changes in the hair cells and may act as a protective mechanism to limit or to avoid further damage to the sensory epithelium.

An innovative processing driven efficient transformation of rare ginsenosides enhances anti-platelet aggregation potency of notoginseng by integrated analyses of processing-(chemical) profiling-pharmacodynamics

Ethnopharmacological relevancePanax notoginseng (Burk.) F. H. Chen, a valuable Chinese herb medicine, shows a characteristic bi-directional regulation of hemostasis and activating blood circulation with ginsenosides as the predominant bioactive compounds and is a typical representative of “processing triggered heteropotency”. Aim of the studyProcessing triggered heteropotency, one of the unique theories and practices in traditional Chinese medicine, refers to that the processing will lead to change in physical and chemical properties, and eventually disparate efficacy of the crude drugs, yet the optimum process and underlying mechanism remains unclear. In this study, using Panax notoginseng (PN) as a representative sample, a processing-(chemical) profiling-pharmacodynamics (3-P) relationship was proposed to investigate the processing mechanism of PN. Materials and methodsFirstly, a temperature programmed steaming process was designed to evaluate the steaming triggered chemical transformation of triterpene saponins and the corresponding enhancement in anti-platelet aggregation activity. The steaming process was programed from the conventional 100 °C–150 °C in a time course of 0–12 h, aiming to achieve the maximized conversion of rare ginsenosides (RGs), and dynamic profile of ginsenosides were constructed by a UPLC-Q-TOF-MS/MS analysis. Then, a processing-(chemical) profiling-pharmacodynamics (3-P) relationship was assessed by using the grey relational analysis (GRA) and orthogonal projections to latent structures (OPLS), and validated by bioactive fraction of 140 °C steamed PN. Subsequently, the P2Y12-ligand binding affinity of potential candidates was analyzed by molecular docking. Finally, the dynamic changes of ginsenosides during steaming of SPN were quantitatively detected by UPLC-QQQ-MS/MS. ResultsA total of 48 differential ginsenosides were characterized and monitored including the primary and secondarily transformed saponins. The higher temperature steaming especially at 140 °C induces not only the predominant production of the RGs, but also the stronger anti-platelet aggregation activity. The 3-P relationship showed the fraction (3) of 140 °C steamed PN rich in RGs exhibits the most predominant efficacy, in which, a series of RGs including ginsenosides Rg5, Rk1, 20(S/R)-Rg3 were proven to be potent components. Molecular docking analysis suggested that ginsenosides Rg5 and Rk1 showed more strong interaction with the platelet P2Y12 receptor. Quantitative analysis found 140 °C-2h PN possessed highest contents of Rk1 and Rg5 and total RGs. ConclusionsThe integrated 3-P strategy uncovered the promising ginsenosides with anti-platelet effect, thereby revealing the material basis of PN steaming, which could provide a new enlightenment for the investigation of processing mechanism of traditional Chinese medicines.

Cell-type-specific role of P2Y2 receptor in HDM-driven model of allergic airway inflammation.

Allergic airway inflammation (AAI) is a chronic respiratory disease that is considered a severe restriction in daily life and is accompanied by a constant risk of acute aggravation. It is characterized by IgE-dependent activation of mast cells, infiltration of eosinophils, and activated T-helper cell type 2 (Th2) lymphocytes into airway mucosa. Purinergic receptor signaling is known to play a crucial role in inducing and maintaining allergic airway inflammation. Previous studies in an ovalbumin (OVA)-alum mouse model demonstrated a contribution of the P2Y2 purinergic receptor subtype (P2RY2) in allergic airway inflammation. However, conflicting data concerning the mechanism by which P2RY2 triggers AAI has been reported. Thus, we aimed at elucidating the cell-type-specific role of P2RY2 signaling in house dust mite (HDM)-driven model of allergic airway inflammation. Thereupon, HDM-driven AAI was induced in conditional knockout mice, deficient or intact for P2ry2 in either alveolar epithelial cells, hematopoietic cells, myeloid cells, helper T cells, or dendritic cells. To analyze the functional role of P2RY2 in these mice models, flow cytometry of bronchoalveolar lavage fluid (BALF), cytokine measurement of BALF, invasive lung function measurement, HDM re-stimulation of mediastinal lymph node (MLN) cells, and lung histology were performed. Mice that were subjected to an HDM-based model of allergic airway inflammation resulted in reduced signs of acute airway inflammation including eosinophilia in BALF, peribronchial inflammation, Th2 cytokine production, and bronchial hyperresponsiveness in mice deficient for P2ry2 in alveolar epithelial cells, hematopoietic cells, myeloid cells, or dendritic cells. Furthermore, the migration of bone-marrow-derived dendritic cells and bone-marrow-derived monocytes, both deficient in P2ry2, towards ATP was impaired. Additionally, we found reduced levels of MCP-1/CCL2 and IL-8 homologues in the BALF of mice deficient in P2ry2 in myeloid cells and lower concentrations of IL-33 in the lung tissue of mice deficient in P2ry2 in alveolar epithelial cells. In summary, our results show that P2RY2 contributes to HDM-induced airway inflammation by mediating proinflammatory cytokine production in airway epithelial cells, monocytes, and dendritic cells and drives the recruitment of lung dendritic cells and monocytes.

Dual antiplatelet therapy is associated with high α-tubulin acetylation in circulating platelets from coronary artery disease patients

Platelet inhibition is the main treatment strategy to prevent atherothrombotic complications after acute coronary syndrome or percutaneous coronary intervention. Despite dual antiplatelet therapy (DAPT) combining aspirin and a P2Y12 receptor inhibitor, high on-treatment platelet reactivity (HPR) persists in some patients due to poor response to treatment and is associated with ischemic risk. Tubulin acetylation has been pointed out as a hallmark of stable microtubules responsible for the discoid shape of resting platelets. However, the impact of antiplatelet treatments on this post-translational modification has never been studied. This study investigated whether tubulin acetylation differs according to antiplatelet therapy and on-treatment platelet reactivity. Platelets were isolated from arterial blood samples of 240 patients admitted for coronary angiography, and levels of α-tubulin acetylation on lysine 40 (α-tubulin K40 acetylation) were assessed by western blot. We show that platelet α-tubulin K40 acetylation was significantly increased in DAPT-treated patients. In addition, the proportion of patients with high levels of α-tubulin K40 acetylation was drastically reduced among DAPT-treated patients with HPR. Multivariate logistic regression confirmed that DAPT resulting in adequate platelet inhibition was strongly associated with elevated α-tubulin K40 acetylation. In conclusion, our study highlights the role of elevated platelet α-tubulin K40 acetylation as a marker of platelet inhibition in response to DAPT. Clinical trial registration: https://clinicaltrials.gov - NCT03034148.

Early computed tomography coronary angiography and preventative treatment in patients with suspected acute coronary syndrome: A secondary analysis of the RAPID-CTCA trial

Computed tomography coronary angiography (CTCA) offers detailed assessment of the presence of coronary atherosclerosis and helps guide patient management. We investigated influences of early CTCA on the subsequent use of preventative treatment in patients with suspected acute coronary syndrome. In this secondary analysis of a multicenter randomized controlled trial of early CTCA in intermediate-risk patients with suspected acute coronary syndrome, prescription of aspirin, P2Y12 receptor antagonist, statin, renin-angiotensin system blocker, and beta-blocker therapies from randomization to discharge were compared within then between those randomized to early CTCA or to standard of care only. Effects of CTCA findings on adjustment of these therapies were further examined. In 1,743 patients (874 randomized to early CTCA and 869 to standard of care only), prescription of P2Y12 receptor antagonist, dual antiplatelet, and statin therapies increased more in the early CTCA group (between-group difference: 4.6% [95% confidence interval, 0.3-8.9], 4.5% [95% confidence interval, 0.2-8.7], and 4.3% [95% confidence interval, 0.2-8.5], respectively), whereas prescription of other preventative therapies increased by similar extent in both study groups. Among patients randomized to early CTCA, there were additional increments of preventative treatment in those with obstructive coronary artery disease and higher rates of reductions in antiplatelet and beta-blocker therapies in those with normal coronary arteries. Prescription patterns of preventative treatment varied during index hospitalization in patients with suspected acute coronary syndrome. Early CTCA facilitated targeted individualization of these therapies based on the extent of coronary artery disease.

P2Y12 receptor residues crucial for thrombosis regulation.

Thrombosis, or the formation of blood clots, can lead to serious medical conditions such as stroke, heart attack, and deep vein thrombosis. The purinoreceptor P2Y12 plays a critical role in the thrombotic pathway and is targeted for therapy to prevent clot formation. However, it is essential to balance the regulation of thrombosis to avoid adverse situations. This study focuses on the P2Y12 receptor and aims to discern the protein residue network and differentiate residues based on their intramolecular interactions. The study utilized a statistical analysis to characterize the significant residues involved in ligand interaction, which helps to identify critical residues that are essential for the function of the receptor. A parametric analysis of interactions of residues in the intraprotein interaction was conducted, which revealed significant residue-based contacts that facilitate protein interactions. By examining the interactions between residues, the mechanisms underlying protein interactions were studied and the importance of specific residues in facilitating these interactions was determined. This research provides important information on P2Y12, and the findings based on the networkbased significance of interacting residues may contribute to the development of new therapies that target the receptor to prevent clot formation while maintaining a balance in thrombosis regulation to avoid adverse outcomes. Ultimately, this study could lead to improved treatments for thrombotic disorders and better patient outcomes.

Mind the Gap: Model-Based Switching from Selatogrel to Maintenance Therapy with Oral P2Y12 Receptor Antagonists.

Background: The P2Y12 receptor antagonist selatogrel is being developed for subcutaneous self-administration with a ready-to-use autoinjector at the onset of acute myocardial infarction (AMI) symptoms. The unique pharmacological profile of selatogrel (fast, potent, and short-acting) can bridge the time gap between the onset of AMI and first medical care. A clinical Phase 1 study showed a time-dependent pharmacodynamic interaction between selatogrel and loading doses of clopidogrel and prasugrel. As treatment switching is a common clinical practice, the assessment of subsequent switching from a clopidogrel loading dose to the first maintenance dose of oral P2Y12 receptor antagonists is highly relevant. Objectives: Model-based predictions of inhibition of platelet aggregation (IPA) for the drugs triggering pharmacodynamic interactions were to be derived to support clinical guidance on the transition from selatogrel to oral P2Y12 receptor antagonists. Methods: Scenarios with selatogrel 16 mg administration or placebo followed by a clopidogrel loading dose and, in turn, prasugrel or ticagrelor maintenance doses at different times of administration were studied. Population pharmacokinetic/pharmacodynamic modeling and simulations of different treatment scenarios were used to derive quantitative estimates for IPA over time. Results: Following selatogrel/placebo and a clopidogrel loading dose, maintenance treatment with ticagrelor or a prasugrel loading dose followed by maintenance treatment quickly achieved sustained IPA levels above 80%. Prior to maintenance treatment, a short time span from 18 to 24 h was identified where IPA levels were predicted to be lower with selatogrel than with placebo if clopidogrel was administered 12 h after selatogrel or placebo. Predicted IPA levels reached with placebo alone and a clopidogrel loading dose at 4 h were consistently lower than with selatogrel administration, followed by a clopidogrel loading dose at 12 h. If a clopidogrel loading dose is administered at 12 h, selatogrel maintains higher IPA levels up to 16 h. IPA levels are subsequently lower than on the placebo until the administration of the first maintenance dose. Conclusions: Model-based predictions informed the transition from selatogrel subcutaneous administration to oral P2Y12 therapy. The application of modeling techniques illustrates the value of employing pharmacokinetic and pharmacodynamic modeling for the simulation of various clinical scenarios of switching therapies.

Astrocytic Extracellular Vesicles Regulated by Microglial Inflammatory Responses Improve Stroke Recovery.

There are no effective treatments for post-stroke glial scar formation, which inhibits axonal outgrowth and functional recovery after stroke. We investigated whether astrocytic extracellular vesicles (AEVs) regulated by microglia modulate glial scars and improve stroke recovery. We found that peri-infarct glial scars comprised reactive astrocytes with proliferating C3d and decreased S100A10 expression in chronic stroke. In cultured astrocytes, microglia-conditioned media and treatment with P2Y1 receptor antagonists increased and reduced the area of S100A10- and C3d-expressing reactive astrocytes, respectively, by suppressing mitogen-activated protein kinase/nuclear factor-κβ (NF-κB)/tumor necrosis factor-α (TNF-α)/interleukin-1β signaling after oxygen-glucose deprivation. Intracerebral administrations of AEVs enriched miR-146a-5p, downregulated NF-κB, and suppressed TNF-α expressions, by transforming reactive astrocytes to those with S100A10 preponderance, causing functional recovery in rats subjected to middle cerebral artery occlusion. Modulating neuroinflammation in post-stroke glial scars could permit axonal outgrowth, thus providing a basis for stroke recovery with neuroprotective AEVs.

Effects of Early Exposure to Isoflurane on Susceptibility to Chronic Pain Are Mediated by Increased Neural Activity Due to Actions of the Mammalian Target of the Rapamycin Pathway.

Patients who have undergone surgery in early life may be at elevated risk for suffering neuropathic pain in later life. The risk factors for this susceptibility are not fully understood. Here, we used a mouse chronic pain model to test the hypothesis that early exposure to the general anesthetic (GA) Isoflurane causes cellular and molecular alterations in dorsal spinal cord (DSC) and dorsal root ganglion (DRG) that produces a predisposition to neuropathic pain via an upregulation of the mammalian target of the rapamycin (mTOR) signaling pathway. Mice were exposed to isoflurane at postnatal day 7 (P7) and underwent spared nerve injury at P28 which causes chronic pain. Selected groups were treated with rapamycin, an mTOR inhibitor, for eight weeks. Behavioral tests showed that early isoflurane exposure enhanced susceptibility to chronic pain, and rapamycin treatment improved outcomes. Immunohistochemistry, Western blotting, and q-PCR indicated that isoflurane upregulated mTOR expression and neural activity in DSC and DRG. Accompanying upregulation of mTOR and rapamycin-reversible changes in chronic pain-associated markers, including N-cadherin, cAMP response element-binding protein (CREB), purinergic P2Y12 receptor, glial fibrillary acidic protein (GFAP) in DSC; and connexin 43, phospho-extracellular signal-regulated kinase (p-ERK), GFAP, Iba1 in DRG, were observed. We concluded that early GA exposure, at least with isoflurane, alters the development of pain circuits such that mice are subsequently more vulnerable to chronic neuropathic pain states.

Plasma protein signatures for high on-treatment platelet reactivity to aspirin and clopidogrel in peripheral artery disease

BackgroundA significant proportion of patients with peripheral artery disease (PAD) displays a poor response to aspirin and/or the platelet P2Y12 receptor antagonist clopidogrel. This phenomenon is reflected by high on-treatment platelet reactivity (HTPR) in platelet function assays in vitro and is associated with an increased risk of adverse cardiovascular events. ObjectiveThis study aimed to elucidate specific plasma protein signatures associated with HTPR to aspirin and clopidogrel in PAD patients. Methods and resultsBased on targeted plasma proteomics, 184 proteins from two cardiovascular Olink panels were measured in 105 PAD patients. VerifyNow ASPI- and P2Y12-test values were transformed to a continuous variable representing HTPR as a spectrum instead of cut-off level-defined HTPR. Using the Boruta random forest algorithm, the importance of 3 plasma proteins for HTPR in the aspirin, six in clopidogrel and 10 in the pooled group (clopidogrel or aspirin) was confirmed. Network analysis demonstrated clusters with CD84, SLAMF7, IL1RN and THBD for clopidogrel and with F2R, SELPLG, HAVCR1, THBD, PECAM1, TNFRSF10B, MERTK and ADM for the pooled group. F2R, TNFRSF10B and ADM were higher expressed in Fontaine III patients compared to Fontaine II, suggesting their relation with PAD severity. ConclusionsA plasma protein signature, including eight targets involved in proatherogenic dysfunction of blood cell-vasculature interaction, coagulation and cell death, is associated with HTPR (aspirin and/or clopidogrel) in PAD. This may serve as important systems-based determinants of poor platelet responsiveness to aspirin and/or clopidogrel in PAD and other cardiovascular diseases and may contribute to identify novel treatment strategies.

Ticagrelor inverse agonist activity at the P2Y12 receptor is non-reversible versus its endogenous agonist adenosine 5´-diphosphate.

Ticagrelor is labelled as a reversible, direct-acting platelet P2Y12 receptor (P2Y12 R) antagonist that is indicated clinically for the prevention of thrombotic events in patients with acute coronary syndrome (ACS). As with many antiplatelet drugs, ticagrelor therapy increases bleeding risk in patients, which may require platelet transfusion in emergency situations. The aim of this study was to further examine the reversibility of ticagrelor at the P2Y12 R. Studies were performed in human platelets, with P2Y12 R-stimulated GTPase activity and platelet aggregation assessed. Cell-based bioluminescence resonance energy transfer (BRET) assays were undertaken to assess G protein-subunit activation downstream of P2Y12 R activation. Initial studies revealed that a range of P2Y12 R ligands, including ticagrelor, displayed inverse agonist activity at P2Y12 R. Only ticagrelor was resistant to washout and, in human platelet and cell-based assays, washing failed to reverse ticagrelor-dependent inhibition of ADP-stimulated P2Y12 R function. The P2Y12 R agonist 2MeSADP, which was also resistant to washout, was able to effectively compete with ticagrelor. In silico docking revealed that ticagrelor and 2MeSADP penetrated more deeply into the orthosteric binding pocket of the P2Y12 R than other P2Y12 R ligands. Ticagrelor binding to P2Y12 R is prolonged and more akin to that of an irreversible antagonist, especially versus the endogenous P2Y12 R agonist ADP. This study highlights the potential clinical need for novel ticagrelor reversal strategies in patients with spontaneous major bleeding, and for bleeding associated with urgent invasive procedures.

Understanding clopidogrel resistance: Mechanisms, detections, implications and surmount the clopidogrel resistant in order to potential solutions

Clopidogrel, a drug belonging to the thienopyridine class of antiplatelet agents, has been utilized either as a standalone medication or in combination with aspirin for averting vascular complications in patients afflicted with atherothrombotic conditions. The selective and irreversible blockade of the P2Y12 receptor by clopidogrel makes it a potent inhibitor of platelet activation and aggregation. In patients with acute coronary syndromes or undergoing percutaneous interventions, combining clopidogrel with aspirin is a crucial approach to antiplatelet therapy. The aim of this review article is to investigate the factors that contribute to clopidogrel resistance, mechanisms involved in clopidogrel resistance, evaluate it through laboratory methods and clinical implications of clopidogrel resistance. Additionally, the article explores the clinical importance of Clopidogrel Resistance and its correlation with harmful cardiovascular events. The paper concludes by proposing potential solutions to this resistance and suggesting the usage of alternative antiplatelet from the new generation.

Platelet P2Y12 signalling pathway in the dysregulated immune response during sepsis.

Sepsis is a complicated pathological condition in response to severe infection. It is characterized by a strong systemic inflammatory response, where multiple components of the immune system are involved. Currently, there is no treatment for sepsis. Blood platelets are known for their role in haemostasis, but they also participate in inflammation through cell-cell interaction and the secretion of inflammatory mediators. Interestingly, an increase in platelet activation, secretion, and aggregation with other immune cells (such as monocytes, T-lymphocytes and neutrophils) has been detected in septic patients. Therefore, antiplatelet therapy in terms of P2Y12 antagonists has been evaluated as a possible treatment for sepis. It was found that blocking P2Y12 receptors decreased platelet marker expression and limited attachment to immune cells in some studies, but not in others. This review addresses the role of platelets in sepsis and discusses whether antagonizing P2Y12 signalling pathways can alter the disease outcome. Challenges in studying P2Y12 antagonists in sepsis also are discussed. LINKED ARTICLES: This article is part of a themed issue on Platelet purinergic receptor and non-thrombotic disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.4/issuetoc.

Sex-specific effect of P2Y2 purinergic receptor on glucose metabolism during acute inflammation.

The sex of an animal impacts glucose sensitivity, but little information is available regarding the mechanisms causing that difference, especially during acute inflammation. We examined sex-specific differences in the role of the P2Y2 receptor (P2Y2R) in glucose flux with and without LPS challenge. Male and female wild-type and P2Y2R knockout mice (P2Y2R-/-) were injected with LPS or saline and glucose tolerance tests (GTT) were performed. P2Y2R, insulin receptor, and GLUT4 transporter gene expression was also evaluated. Female mice had reduced fasting plasma glucose and females had reduced glucose excursion times compared to male mice during GTT. P2Y2R-/- males had significantly decreased glucose flux throughout the GTT as compared to all female mice. Acute inflammation reduced fasting plasma glucose and the GTT area under the curve in both sexes. While both wild-type and P2Y2R-/- male animals displayed reduced fasting glucose in LPS treatment, female mice did not have significant difference in glucose tolerance, suggesting that the effects of P2Y2R are specific to male mice, even under inflammatory conditions. Overall, we conclude that the role for the purinergic receptor, P2Y2R, in regulating glucose metabolism is minimal in females but plays a large role in male mice, particularly in the acute inflammatory state.

Proton pump inhibitors and gastroprotection in patients treated with antithrombotic drugs: A cardiologic point of view.

Aspirin, other antiplatelet agents, and anticoagulant drugs are used across a wide spectrum of cardiovascular and cerebrovascular diseases. A concomitant proton pump inhibitor (PPI) treatment is often prescribed in these patients, as gastrointestinal complications are relatively frequent. On the other hand, a potential increased risk of cardiovascular events has been suggested in patients treated with PPIs; in particular, it has been discussed whether these drugs may reduce the cardiovascular protection of clopidogrel, due to pharmacodynamic and pharmacokinetic interactions through hepatic metabolism. Previously, the concomitant use of clopidogrel and omeprazole or esomeprazole has been discouraged. In contrast, it remains less known whether PPI use may affect the clinical efficacy of ticagrelor and prasugrel, new P2Y12 receptor antagonists. Current guidelines recommend PPI use in combination with antiplatelet treatment in patients with risk factors for gastrointestinal bleeding, including advanced age, concurrent use of anticoagulants, steroids, or non-steroidal anti-inflammatory drugs, and Helicobacter pylori (H. pylori) infection. In patients taking oral anticoagulant with risk factors for gastrointestinal bleeding, PPIs could be recommended, even if their usefulness deserves further data. H. pylori infection should always be investigated and treated in patients with a history of peptic ulcer disease (with or without complication) treated with antithrombotic drugs. The present review summarizes the current knowledge regarding the widespread combined use of platelet inhibitors, anticoagulants, and PPIs, discussing consequent clinical implications.

Intracellular cAMP Signaling Pathway via Gs Protein-Coupled Receptor Activation in Rat Primary Cultured Trigeminal Ganglion Cells.

G protein-coupled receptors in trigeminal ganglion (TG) neurons are often associated with sensory mechanisms, including nociception. We have previously reported the expression of P2Y12 receptors, which are Gi protein-coupled receptors, in TG cells. Activating P2Y12 receptors decreased the intracellular free Ca2+ concentration ([Ca2+]i). This indicated that intracellular adenosine 3',5'-cyclic monophosphate (cAMP) levels can mediate Ca2+ signaling in TG cells. Here, we report more extensive-expression patterns of Gs protein-coupled receptors in primary cultured TG neurons isolated from 7-day-old newborn Wistar rats and further examine the roles of these receptors in cAMP signaling using the BacMam sensor in these neurons. To identify TG neurons, we also measured [Ca2+]i using fura-2 in TG cells and measured intracellular cAMP levels. TG neurons were positive for Gαs protein-coupled receptors, beta-2 adrenergic (β2), calcitonin gene-related peptide (CGRP), adenosine A2A (A2A), dopamine 1 (D1), prostaglandin I2 (IP), and 5-hydroxytriptamine 4 (5-HT4) receptor. Application of forskolin (FSK), an activator of adenylyl cyclase, transiently increased intracellular cAMP levels in TG neurons. The application of a phosphodiesterase inhibitor augmented the FSK-elicited intracellular cAMP level increase. These increases were significantly suppressed by the application of SQ22536, an adenylyl cyclase inhibitor, in TG neurons. Application of agonists for β2, CGRP, A2A, D1-like, IP, and 5-HT4 receptors increased intracellular cAMP levels. These increases were SQ22536-sensitive. These results suggested that TG neurons express β2, CGRP, A2A, D1, IP, and 5-HT4 receptors, and the activations of these Gαs protein-coupled receptors increase intracellular cAMP levels by activating adenylyl cyclase.

Silencing of purinergic receptor P2Y2 inhibited enteric neural crest cell proliferation, invasion and migration via suppressing ERK signaling pathway in Hirschsprung disease.

The current study aimed to explore the effect and underlying mechanism of the purinergic receptor P2Y2 in regulating the loss of intestinal neurons and the intestinal neural crest in Hirschsprung's disease (HSCR). Western blotting was used to assess the expression levels of P2Y2 in colon tissues. An in vivo HSCR mouse model was established following treatment with benzalkonium chloride (BAC). We overexpressed or silenced P2Y2 in SH-SY5Y cells, and cell proliferation, migration, and invasion were subsequently investigated by CCK-8, wound healing, and transwell assays, respectively. Additionally, we implemented a xenograft model to assess the impact of P2Y2 on tumor growth as well as the expression of extracellular signal-regulated kinase (ERK). The results showed that the expression of P2Y2 protein in the colon tissues of patients with HSCR was lower than that in the normal colon tissues. P2Y2 expression is downregulated in the colon tissues of mice with HSCR. Additionally, P2Y2 silencing inhibited SH-SY5Y cell proliferation, invasion, and migration. Furthermore, adenosine 5'-triphosphate (ATP, a strong agonist of P2Y2)-induced P2Y2 overexpression enhanced the proliferation, invasion, and migration of SH-SY5Y cells. Immunofluorescence staining and western blot analysis revealed that P2Y2 silencing downregulated phosphorylated (p)-ERK in SH-SY5Y cells. In addition, treatment with PD98059, a p-ERK inhibitor, reversed the effects of ATP on SH-SY5Y cell proliferation, invasion, and migration. Finally, we demonstrated that P2Y2 silencing suppressed tumor growth and decreased p-ERK expression. Overall, the results of the present study suggest that P2Y2 plays an important role in HSCR pathogenesis. P2Y2 silencing inhibited the proliferation, invasion, and migration of nerve cells by suppressing the ERK signaling pathway. P2Y2 silencing could be considered an innovative and possible target for treating HSCR.

Cell Surface Platelet Tissue Factor Expression: Regulation by P2Y12 and Link to Residual Platelet Reactivity.

ADP-induced platelet activation leads to cell surface expression of several proteins, including TF (tissue factor). The role of ADP receptors in platelet TF modulation is still unknown. We aimed to assess the (1) involvement of P2Y1 and P2Y12 receptors in ADP-induced TF exposure; (2) modulation of TFpos-platelets in anti-P2Y12-treated patients with coronary artery disease. Based on the obtained results, we revisited the intracellular localization of TF in platelets. The effects of P2Y1 or P2Y12 antagonists on ADP-induced TF expression and activity were analyzed in vitro by flow cytometry and thrombin generation assay in blood from healthy subjects, P2Y12-/-, and patients with gray platelet syndrome. Ex vivo, P2Y12 inhibition of TF expression by clopidogrel/prasugrel/ticagrelor, assessed by VASP (vasodilator-stimulated phosphoprotein) platelet reactivity index, was investigated in coronary artery disease (n=238). Inhibition of open canalicular system externalization and electron microscopy (TEM) were used for TF localization. In blood from healthy subjects, stimulated in vitro by ADP, the percentage of TFpos-platelets (17.3±5.5%) was significantly reduced in a concentration-dependent manner by P2Y12 inhibition only (-81.7±9.5% with 100 nM AR-C69931MX). In coronary artery disease, inhibition of P2Y12 is paralleled by reduction of ADP-induced platelet TF expression (VASP platelet reactivity index: 17.9±11%, 20.9±11.3%, 40.3±13%; TFpos-platelets: 10.5±4.8%, 9.8±5.9%, 13.6±6.3%, in prasugrel/ticagrelor/clopidogrel-treated patients, respectively). Despite this, 15% of clopidogrel good responders had a level of TFpos-platelets similar to the poor-responder group. Indeed, a stronger P2Y12 inhibition (130-fold) is required to inhibit TF than VASP. Thus, a VASP platelet reactivity index <20% (as in prasugrel/ticagrelor-treated patients) identifies patients with TFpos-platelets <20% (92% sensitivity). Finally, colchicine impaired in vitro ADP-induced TF expression but not α-granule release, suggesting that TF is open canalicular system stored as confirmed by TEM and platelet analysis of patients with gray platelet syndrome. Data show that TF expression is regulated by P2Y12 and not P2Y1; P2Y12 antagonists downregulate the percentage of TFpos-platelets. In clopidogrel good-responder patients, assessment of TFpos-platelets highlights those with residual platelet reactivity. TF is stored in open canalicular system, and its membrane exposure upon activation is prevented by colchicine.

Neural targets of the enteric dopaminergic system in regulating motility of rat proximal colon.

In isolated segments of the rat proximal colon, the dopamine reuptake inhibitor GBR 12909 (GBR) causes a dilatation, while the D1-like receptor antagonist SCH 23390 (SCH) induces a tonic constriction, suggesting that neurally released dopamine tonically stimulates enteric inhibitory efferent neurons. Here, the targets of the enteric dopaminergic neurons were investigated. Cannulated segments of rat proximal colon were bathed in physiological salt solution and luminally perfused with 0.9% saline, while all drugs were applied to the bath. Spatio-temporal maps of colonic motility were constructed from video recordings of peristaltic contractions, and the maximum diameter was measured as an index of colonic contractility. GBR (1μM)-induced dilatations of colonic segments were prevented by SCH (5μM), L-nitro arginine (L-NA; 100μM), a nitric oxide synthase inhibitor, or tetrodotoxin (0.6μM). In contrast, constrictions induced by a higher concentration of SCH (20μM) were unaffected by either L-NA or tetrodotoxin. The vasoactive intestinal peptide (VIP) receptor antagonist VIP10-28 (3μM) or P2Y1 receptor antagonist MRS 2500 (1μM) had no effect on either the GBR-induced dilatation or the SCH-induced constriction. In colonic segments that had been pretreated with 6-hydroxydopamine (100μM, 3h) to deplete enteric dopamine, GBR failed to increase the colonic diameter, while SCH was still capable of constricting colonic segments. Enteric dopaminergic neurons appear to project to nitrergic neurons to dilate the proximal colon by activating neuronal D1-like receptors. In addition, constitutively activated D1-like receptors expressed in cells yet to be determined may provide a tonic inhibition on colonic constrictions.

Racial/Ethnic Disparities in Outcomes After Percutaneous Coronary Intervention

Asian American/Pacific Islanders (AAPIs) and Hispanics are growing minority United States populations, but are poorly represented in the cardiovascular literature. This study examines guideline adherence and outcomes in AAPIs and Hispanics compared with non-Hispanic Whites (NHWs) in a quaternary care center after inpatient percutaneous coronary intervention (PCI). The primary end points were inpatient post-PCI bleed, heart failure, cardiogenic shock, and all-cause mortality, whereas the secondary end point was the prescription rate of post-PCI guideline-directed medical therapy including aspirin, statins, P2Y12 receptor blockers, and cardiopulmonary rehabilitation. Intergroup differences were assessed through analysis of variance or two-way chi-square tests, and the association of race with binary outcomes was examined through logistic regression with NHW as the reference group. Compared with NHW, AAPIs, and Hispanics had higher odds of diabetes mellitus, and AAPIs had higher odds of hypertension and being on dialysis. Hispanics had higher odds of post-PCI mortality versus NHW, both in acute coronary syndrome (odds ratio [OR] 2.04, p=0.03) and elective PCI (OR2.51, p=0.04). AAPI also trended toward higher mortality than NHW in both categories. AAPIs were found to have higher odds of statin prescription (OR1.91, p=0.04). Hispanics had lower odds of ticagrelor prescription versus NHW (OR0.65, p=0.04), and AAPIs trended toward such. No differences were found for cardiopulmonary rehabilitation prescriptions in groups. This study suggests that despite quality improvement efforts, disparities remain in postprocedural outcomes in minority groups in comparison with NHW.