Thromboxane A2 Receptor Research Articles

Gender characteristics of hematuria during lithokinetic therapy in patients with nephrolithiasis

Purpose. To study gender characteristics of the severity of hematuria and compensatory mechanisms of the proaggregant component of hemostasis in patients with nephrolithiasis when prescribing litokinetic therapy (LCT), including nonsteroidal anti-inflammatory drugs (NSAIDs). Material and methods. The prospective study included 60 patients (group 1 – 30 men; group 2 – 30 women) with imaging signs of the presence of stones in the urinary tract. For 7 days, patients underwent standard LCT, including NSAIDs, an α1A-blocker (tamsulosin) and antibiotics. In vitro, the activity of the TP receptor for TxA2 and purine P2Y receptors (P2Y1 and P2Y12) was studied on a platelet suspension after 24, 48, 72 hours, 5 and 7 days. Platelet aggregation was assessed using the turbidimetric method using a ChronoLog analyzer (USA). Results. At the hospitalization stage, in both groups (before the introduction of NSAIDs), hyperreactivity of the TP-receptor was observed, and in men the activity of the TP receptor was lower, and hematuria (p<0.05) was higher than in women. The pharmacokinetics of NSAIDs in men was characterized by inhibition of cyclooxygenase (COX) in two time periods – 72 hours and 7 days, as a result of which the synthesis of TхA2 in platelets decreased and hematuria increased 4.4 times (p<0.001) compared with the hospitalization stage. In women, COX inhibition occurred within 5 days; At the same time, the preservation of normal reactivity of the TP-receptor and purine P2Y receptors ensured the implementation of a compensatory platelet response, limiting the severity of hematuria. Conclusion. Analysis of the mechanisms of gender differences in hematuria in nephrolithiasis is important for developing a personalized medicine strategy when prescribing NSAIDs.

Integrating Phenotypic and Chemoproteomic Approaches to Identify Covalent Targets of Dietary Electrophiles in Platelets.

A large variety of dietary phytochemicals has been shown to improve thrombosis and stroke outcomes in preclinical studies. Many of these compounds feature electrophilic functionalities that potentially undergo covalent addition to the sulfhydryl side chain of cysteine residues within proteins. However, the impact of such covalent modifications on the platelet activity and function remains unclear. This study explores the irreversible engagement of 23 electrophilic phytochemicals with platelets, unveiling the unique antiplatelet selectivity of sulforaphane (SFN). SFN impairs platelet responses to adenosine diphosphate (ADP) and a thromboxane A2 receptor agonist while not affecting thrombin and collagen-related peptide activation. It also substantially reduces platelet thrombus formation under arterial flow conditions. Using an alkyne-integrated probe, protein disulfide isomerase A6 (PDIA6) was identified as a rapid kinetic responder to SFN. Mechanistic profiling studies revealed SFN's nuanced modulation of PDIA6 activity and substrate specificity. In an electrolytic injury model of thrombosis, SFN enhanced the thrombolytic activity of recombinant tissue plasminogen activator (rtPA) without increasing blood loss. Our results serve as a catalyst for further investigations into the preventive and therapeutic mechanisms of dietary antiplatelets, aiming to enhance the clot-busting power of rtPA, currently the only approved therapeutic for stroke recanalization that has significant limitations.

Storage of Transfusion Platelet Concentrates Is Associated with Complement Activation and Reduced Ability of Platelets to Respond to Protease-Activated Receptor-1 and Thromboxane A2 Receptor.

Platelet activation and the complement system are mutually dependent. Here, we investigated the effects of storage time on complement activation and platelet function in routinely produced platelet concentrates. The platelet concentrates (n = 10) were stored at 22 °C for seven days and assessed daily for complement and platelet activation markers. Additionally, platelet function was analyzed in terms of their responsiveness to protease-activated receptor-1 (PAR-1) and thromboxane A2 receptor (TXA2R) activation and their capacity to adhere to collagen. Complement activation increased over the storage period for all analyzed markers, including the C1rs/C1-INH complex (fold change (FC) = 1.9; p < 0.001), MASP-1/C1-INH complex (FC = 2.0; p < 0.001), C4c (FC = 1.8, p < 0.001), C3bc (FC = 4.0; p < 0.01), and soluble C5b-9 (FC = 1.7, p < 0.001). Furthermore, the levels of soluble platelet activation markers increased in the concentrates over the seven-day period, including neutrophil-activating peptide-2 (FC = 2.5; p < 0.0001), transforming growth factor beta 1 (FC = 1.9; p < 0.001) and platelet factor 4 (FC = 2.1; p < 0.0001). The ability of platelets to respond to activation, as measured by surface expression of CD62P and CD63, decreased by 19% and 24% (p < 0.05) for PAR-1 and 69-72% (p < 0.05) for TXA2R activation, respectively, on Day 7 compared to Day 1. The extent of platelet binding to collagen was not significantly impaired during storage. In conclusion, we demonstrated that complement activation increased during the storage of platelets, and this correlated with increased platelet activation and a reduced ability of the platelets to respond to, primarily, TXA2R activation.

Regulation of platelet proaggregant activity in cyclooxygenase inhibition in patients with nephrolithiasis

Aim of the study was to establish the possibility of synergism between the TP receptor for TxA2 and purinergic P2 receptors during COX inhibition, and the effect of the resulting remodeling of signaling pathways on aggregometry parameters in patients with nephrolithiasis (NLT). Materials and Methods. The study was prospective and included 30 patients with imaging evidence of urinary tract calculi who were treated with high doses of non-selective NSAIDs for analgesia. The severity of hematuria was assessed at the time of hospitalization and during 7 days of lithokinetic therapy (LKT). Analysis of functional activity of TR-receptors, purine P2X1and P2Yreceptors of platelets (Tc) was performed by turbidimetric method on ChronoLog analyzer (USA). Agonists (ATP, ADP and Arachidonic acid) were used at concentrations of EC50 and EC10. Statistical analysis was performed using MedCalc package. Results. Two waves of COX activity decrease were revealed 24h and 72h after the beginning of NSAID administration. On the 5th day of LKT, the compensatory reaction of Tc was switched on, which was reproduced at restoration of normoreactivity of TR-receptor. Purine P2X1 – and P2Y-receptor synergism had a more pronounced inducing effect on aggregation parameters compared with the interaction between P2Y-receptor and TR-receptor or TR-receptor and P2X -receptor. On the 7th day, the residual level of COX activity was reached and hyporeactivity of TR-receptor was registered; at the same time the preserved level of TxA2 synthesis did not provide limitation of hematuria. Conclusion. Upon COX inhibition, potentiation of Tc proaggregant activity is reproduced by purine P2-receptor and TR-receptor interaction due to an increase in the rate of intracellular signalling (Slope) and the number of aggregates formed (AUC).

Chymase-independent vascular Ang-(1–12)/Ang II pathway and TXA2 generation are involved in endothelial dysfunction in the murine model of heart failure

The angiotensin (Ang)-(1–12)/Ang II pathway contributes to cardiac pathology. However, its involvement in the development of peripheral endothelial dysfunction associated with heart failure (HF) remains unknown. Therefore, this study aimed to characterise the effect of exogenous Ang-(1–12) and its conversion to Ang II on endothelial function using the murine model of HF (Tgαq*44 mice), focusing on the role of chymase and vascular-derived thromboxane A2 (TXA2).Ex vivo myographic assessments of isolated aorta showed impaired endothelium-dependent vasodilation in late-stage HF in 12-month-old Tgαq*44 mice. However, endothelium-dependent vasodilation was fully preserved in the early stage of HF in 4-month-old Tgαq*44 mice and 4- and 12-month-old FVB control mice. Ang-(1–12) impaired endothelium-dependent vasodilation in 4- and 12-month-old Tgαq*44 mice, that was associated with increased Ang II production. The chymase inhibitor chymostatin did not inhibit this response. Interestingly, TXA2 production reflected by TXB2 measurement was upregulated in response to Ang-(1–12) and Ang II in aortic rings isolated from 12-month-old Tgαq*44 mice but not from 4-month-old Tgαq*44 mice or age-matched FVB mice. Furthermore, in vivo magnetic resonance imaging showed that Ang-(1–12) impaired endothelium-dependent vasodilation in the aorta of Tgαq*44 mice and FVB mice. However, this response was inhibited by angiotensin I converting enzyme (ACE) inhibitor; perindopril, angiotensin II receptor type 1 (AT1) antagonist; losartan and TXA2 receptor (TP) antagonist-picotamide in 12-month-old-Tgαq*44 mice only.In conclusion, the chymase-independent vascular Ang-(1–12)/Ang II pathway and subsequent TXA2 overactivity contribute to systemic endothelial dysfunction in the late stage of HF in Tgαq*44 mice. Therefore, the vascular TXA2 receptor represents a pharmacotherapeutic target to improve peripheral endothelial dysfunction in chronic HF.

Jak2V617F clonal hematopoiesis promotes arterial thrombosis via platelet activation and cross talk

AbstractJAK2V617F (JAK2VF) clonal hematopoiesis (CH) has been associated with atherothrombotic cardiovascular disease (CVD). We assessed the impact of Jak2VF CH on arterial thrombosis and explored the underlying mechanisms. A meta-analysis of 3 large cohort studies confirmed the association of JAK2VF with CVD and with platelet counts and adjusted mean platelet volume (MPV). In mice, 20% or 1.5% Jak2VF CH accelerated arterial thrombosis and increased platelet activation. Megakaryocytes in Jak2VF CH showed elevated proplatelet formation and release, increasing prothrombogenic reticulated platelet counts. Gp1ba-Cre–mediated expression of Jak2VF in platelets (VFGp1ba) increased platelet counts to a similar level as in 20% Jak2VF CH mice while having no effect on leukocyte counts. Like Jak2VF CH mice, VFGp1ba mice showed enhanced platelet activation and accelerated arterial thrombosis. In Jak2VF CH, both Jak2VF and wild-type (WT) platelets showed increased activation, suggesting cross talk between mutant and WT platelets. Jak2VF platelets showed twofold to threefold upregulation of COX-1 and COX-2, particularly in young platelets, with elevated cPLA2 activation and thromboxane A2 production. Compared with controls, conditioned media from activated Jak2VF platelets induced greater activation of WT platelets that was reversed by a thromboxane receptor antagonist. Low-dose aspirin ameliorated carotid artery thrombosis in VFGp1ba and Jak2VF CH mice but not in WT control mice. This study shows accelerated arterial thrombosis and platelet activation in Jak2VF CH with a major role of increased reticulated Jak2VF platelets, which mediate thromboxane cross talk with WT platelets and suggests a potential beneficial effect of aspirin in JAK2VF CH.

Investigating the Mechanisms Underlying U46619-Induced Contraction on Porcine Lower Esophageal Sphincter.

Gastroesophageal reflux disease (GERD) is associated with an incompetent lower esophageal sphincter (LES), resulting in the reflux of gastric contents into the esophagus. U46619, a thromboxane A2 (TXA2) receptor agonist, induces contractions in various smooth muscles. Therefore, this study aimed to investigate the effects and mechanisms of action of U46619 on the porcine LES. To achieve this, contractions of the clasp and sling strips of the porcine LES, induced by U46619, were measured using isometric transducers. Furthermore, the contractile mechanism of U46619 in the porcine LES was investigated by pretreating the strips with atropine (a muscarinic receptor antagonist), tetrodotoxin (a neuronal sodium channel blocker), nifedipine (a calcium channel blocker), and Ca2+-free Krebs-Henseleit solution. Additionally, reverse transcription polymerase chain reaction (PCR) and immunohistochemistry (IHC) were performed to determine the presence of the TXA2 receptor in porcine LES. The results of this study demonstrated that U46619 caused marked concentration-dependent contractions in both porcine sling and clasp strips. The mechanism of U46619-induced contraction of the porcine LES was found to be related to calcium channels. Furthermore, the reverse transcription PCR analysis and IHC revealed that the TXA2 receptor was expressed in the clasp and sling fibers of porcine LES. Consequently, this study suggests that U46619 mediates the contraction of porcine LES through calcium channels and has potential as a therapeutic approach for treating GERD. SIGNIFICANCE STATEMENT: This study establishes that U46619 induces concentration-dependent contractions in porcine LES, primarily mediated by calcium channels. The presence of the TXA2 receptor in LES clasp and sling fibers is confirmed. These findings highlight U46619's potential as a GERD therapeutic by targeting calcium channels for LES contraction modulation.

Indocyanine green-loaded platelet activated by photodynamic and photothermal effects for selective control of wound repair

ObjectivePrompt and effective wound repair is an essential strategy to promote recovery and prevent infection in patients with various types of trauma. Platelets can release a variety of growth factors upon activation to facilitate revascularization and tissue repair, provided that their activation is uncontrollable. The present study is designed to explore the selective activation of platelets by photodynamic and photothermal effects (PDE/PTE) as well as the trauma repair mediated by PDE/PTE. Materials and MethodsIn the current research, platelets were extracted from the blood of mice. Indocyanine green (ICG) was applied to induce PDE/PTE. The uptake of ICG by platelets was detected by laser confocal microscopy and flow cytometry. The cellular integrity was measured by microscopy. The reactive oxygen species (ROS) generation and temperature of platelets were assayed by 2,7-Dichlorodihydrofluorescein diacetate (DCFH-DA) and temperature detector. The activation of platelets was measured by western blots (WB), dynamic light scattering (DLS), and scanning electron microscopy (SEM). The release of growth factor was detected by enzyme-linked immuno sorbent assay (Elisa), wherein the in vitro cell proliferation was investigated by 5-Ethynyl-2’-deoxyuridine (EDU) assay. The wound infection rates model and histological examination were constructed to assay the ICG-loaded platelet-mediated wound repair. ResultsPlatelets could load with ICG, a kind of photodynamic and photothermal agent, as carriers and remain intact. Near-infrared (NIR) laser irradiation of ICG-loaded platelets (ICG@PLT) facilitated higher temperature and ROS generation, which immediately activated ICG@PLT, as characterized by increased membrane p-selectin (CD62p), cyclooxygenase-2 (COX-2), thromboxane A2 receptor (TXA2R) expression, elevated hydrated particle size, and prominent aggregation in platelets. Further investigation revealed that massive insulin-like growth factor (IGF) and platelet-derived growth factor (PDGF) were released from the activated ICG@PLT, which also promoted the proliferation of endothelial cells and keratinocytes in co-culture. In consequence, activated platelets and increased neovascularization could be observed in rats with wound infection treated by ICG@PLT in the presence of NIR. More impressively, the hydrogel containing ICG@PLT accelerated wound healing and suppressed inflammation under NIR, exhibiting excellent wound repair properties. ConclusionTaken together, the current work identified that platelets could be activated by PDE/PTE and thereby release growth factor, potentiating wound repair in a controlled manner.

Reprogramming Megakaryocytes for Controlled Release of Platelet-like Particles Carrying a Single-Chain Thromboxane A2 Receptor-G-Protein Complex with Therapeutic Potential.

In this study, we reported that novel single-chain fusion proteins linking thromboxane A2 (TXA2) receptor (TP) to a selected G-protein α-subunit q (SC-TP-Gαq) or to α-subunit s (SC-TP-Gαs) could be stably expressed in megakaryocytes (MKs). We tested the MK-released platelet-linked particles (PLPs) to be used as a vehicle to deliver the overexpressed SC-TP-Gαq or the SC-TP-Gαs to regulate human platelet function. To understand how the single-chain TP-Gα fusion proteins could regulate opposite platelet activities by an identical ligand TXA2, we tested their dual functions-binding to ligands and directly linking to different signaling pathways within a single polypeptide chain-using a 3D structural model. The immature MKs were cultured and transfected with cDNAs constructed from structural models of the individual SC-TP-Gαq and SC-TP-Gαs, respectively. After transient expression was identified, the immature MKs stably expressing SC-TP-Gαq or SC-TP-Gαs (stable cell lines) were selected. The stable cell lines were induced into mature MKs which released PLPs. Western blot analysis confirmed that the released PLPs were carrying the recombinant SC-TP-Gαq or SC-TP-Gαs. Flow cytometry analysis showed that the PLPs carrying SC-TP-Gαq were able to perform the activity by promoting platelet aggregation. In contrast, PLPs carrying SC-TP-Gαs reversed Gq to Gs signaling to inhibit platelet aggregation. This is the first time demonstrating that SC-TP-Gαq and SC-TP-Gαs were successfully overexpressed in MK cells and released as PLPs with proper folding and programmed biological activities. This bio-engineering led to the formation of two sets of biologically active PLP forms mediating calcium and cAMP signaling, respectively. As a result, these PLPs are able to bind to identical endogenous TXA2 with opposite activities, inhibiting and promoting platelet aggregation as reprogrammed for therapeutic process. Results also demonstrated that the nucleus-free PLPs could be used to deliver recombinant membrane-bound GPCRs to regulate cellular activity in general.

Deletion of vascular thromboxane A2 receptors and its impact on angiotensin II-induced hypertension and atherosclerotic lesion formation in the aorta of Ldlr-deficient mice

The thromboxane A2 receptor (TP) has been shown to play a role in angiotensin II (Ang II)-mediated hypertension and pathological vascular remodeling. To assess the impact of vascular TP on Ang II-induced hypertension, atherogenesis, and pathological aortic alterations, i.e. aneurysms, we analysed Western-type diet-fed and Ang II-infused TPVSMC KO/Ldlr KO, TPEC KO/Ldlr KO mice and their respective wild-type littermates (TPWT/Ldlr KO). These analyses showed that neither EC- nor VSMC-specific deletion of the TP significantly affected basal or Ang II-induced blood pressure or aortic atherosclerotic lesion area. In contrast, VSMC-specific TP deletion abolished and EC-specific TP deletion surprisingly reduced the ex vivo reactivity of aortic rings to the TP agonist U-46619, whereas VSMC-specific TP knockout also diminished the ex vivo response of aortic rings to Ang II. Furthermore, despite similar systemic blood pressure, there was a trend towards less atherogenesis in the aortic arch and a trend towards fewer pathological aortic alterations in Ang II-treated female TPVSMC KO/Ldlr KO mice. Survival was impaired in male mice after Ang II infusion and tended to be higher in TPVSMC KO/Ldlr KO mice than in TPWT/Ldlr KO littermates. Thus, our data may suggest a deleterious role of the TP expressed in VSMC in the pathogenesis of Ang II-induced aortic atherosclerosis in female mice, and a surprising role of the endothelial TP in TP-mediated aortic contraction. However, future studies are needed to substantiate and further elucidate the role of the vascular TP in the pathogenesis of Ang II-induced hypertension, aortic atherosclerosis and aneurysm formation.

IPSC-derived vascular smooth muscle cell model recapitulates Loeys-Dietz-Syndrome type V aortic phenotype

Abstract Introduction Thoracic aortic aneurysm and dissection (TAAD) is a hallmark of Loeys-Dietz syndrome (LDS) and a prominent cause of morbidity and sudden death. Current drug therapies are only able to slow down but not stop or reverse aneurysm formation. TAAD pathomechanisms remain largely elusive, complicating the development of more effective treatments. Purpose The creation of a disease-relevant in vitro model, that recapitulates the disease phenotype, is incredibly valuable to gain better insights in the pathomechanisms underlying TAAD and to develop new treatments. Methods Validated induced pluripotent stem cells (iPSCs) of two male TAAD patients carrying the same pathogenic p.Asp263His variant in TGFB3 (LDS type V) and one male healthy individual were used in this study. One patient underwent a Bentall procedure at age 66 years because of insufficiency of a bicuspid aortic valve and TAA (50 mm, z-score= 5.2). The second patient presented with a type A dissection at age 31 years, also requiring Bentall surgery. The patients are distantly related, having a common ancestor allele, estimated to be arisen &amp;gt;400 years ago. We created and characterized iPSC-derived neural crest-vascular smooth muscle cell (NC-VSMC) lines from both LDS type V patients and the healthy control. Addition of a chemical thromboxane A2 receptor agonist initiated NC-VSMC contraction which was quantified by the change in impedance using the xCELLigence system and RTCA software. Additionally, the proliferation rate was quantified with the CyQuant Direct Cell Proliferation Assay Kit and inverted DMi8 fluorescence microscope (Leica). With an univariate ANOVA test, we assessed similarity of the variance between groups, after which the corresponding two-way t-test was performed. Results Within 30 minutes after thromboxane A2 receptor agonist addition, a maximal contracted state was reached, which was significantly lower for the first patient (2 clones) as compared to the control (2 cloness) (p=0.03). The time to get to this maximal contracted state was comparable between patient and control, while the surface area coverage over a duration of 1h stimulation was reduced for patient NC-VSMCs (p=0.04). Contraction of the NC-VSMC line (1 clone) from the second LDS patient did not significantly differ from the contraction profile of the control line. After one hour, U46619 was removed resulting in relaxation and full recovery for all NC-VSMCs. Proliferation rate of NC-VSMCs from all patient and control lines was around 1.5, with no significant difference between the groups (p=0.59). Conclusion We created an NC-VSMC model that recapitulates the LDS aortic phenotype with regards to reduced VSMC contractility. Although NC-VSMC lines created from the same individual showed extremely little variability, there is important variability between the lines of different patients which might be due to immaturity of the cells, environmental factors and the presence of genetic modifiers.

Abstract 17104: Characterization of a Novel, Clinically Relevant Mouse Model of Peripartum Cardiomyopathy

Pregnancy requires significantly increased cardiac output (~30%) achieved through peripheral vasodilation and increased stroke volume, due to increased end-diastolic volume. Most women resolve these physiological changes within 6 months of delivery; however, some women progress to heart failure late in pregnancy or in the immediate post-partum period. Peri-partum cardiomyopathy (PPCM) is a rare condition of largely unknown etiology which, at its most-severe and life-threatening, requires cardiac transplantation. Pre-eclampsia occurs at much higher rates in the PPCM population (~40%) compared with the generally pregnant population (~2-5%). We have previously shown that transgenic mice expressing the human-specific isoform of the TBXA2R gene (TPβ) spontaneously develop pre-eclampsia accompanied by all the associated hallmarks expected from the human disease. We now show TPβ transgenic (TPβ-Tg) mice are a model of PPCM. Using trans-thoracic echocardiographic imaging, TPβ-Tg mice had no basal phenotype; however, unlike C57/Bl6J (WT) mice that resolved the pregnancy-induced cardiac remodeling, TPβ-Tg mice had exaggerated cardiac dilatation at term (E18.5; P&lt;0.01) which increased in severity over the subsequent 6 months (P&lt;0.005). In addition, TP-Tg mice exhibited reduced ejection fraction (22±13% vs 67% in WT), significant LV wall thinning (1.12±0.16 mm vs 1.6±0.17 mm WT), and loss of LV mass (66.55±9 mg vs 95±11mg WT). Analysis of myocardium of human PPCM patients undergoing heart transplant (n=12) compared to healthy myocardium from non-diseased donors (n=42) by RT-PCR and IHC showed highly expressed TPβ in PPCM patients. In human PPCM samples, there was a significant (p&lt;0.01) dysregulation of genes associated with circadian rhythm as determined by RNAseq analysis. Quantitative PCR analysis of hearts from non-pregnant (WT=8; TPβ-Tg=4) and pregnant (WT=10; TPβ-Tg=13) mice found similar dysregulation of multiple genes associated with circadian rhythm compared to WT mice (p&lt;0.01). This indicates that PPCM may be associated with failure to terminate CLOCK signaling as a result of TPβ activation. Our results support dysregulation of TBXA2R splicing as part of the pathogenesis of PPCM and identify new therapeutic targets for this condition.

Glucagon-like Peptide-1 Receptor Pathway Attenuates Platelet Activation in Aspirin-Exacerbated Respiratory Disease.

Platelets are key contributors to allergic asthma and aspirin-exacerbated respiratory disease (AERD), an asthma phenotype involving platelet activation and IL-33-dependent mast cell activation. Human platelets express the glucagon-like peptide-1 receptor (GLP-1R). GLP-1R agonists decrease lung IL-33 release and airway hyperresponsiveness in mouse asthma models. We hypothesized that GLP-1R agonists reduce platelet activation and downstream platelet-mediated airway inflammation in AERD. GLP-1R expression on murine platelets was assessed using flow cytometry. We tested the effect of the GLP-1R agonist liraglutide on lysine-aspirin (Lys-ASA)-induced changes in airway resistance, and platelet-derived mediator release in a murine AERD model. We conducted a prospective cohort study comparing the effect of pretreatment with liraglutide or vehicle on thromboxane receptor agonist-induced invitro activation of platelets from patients with AERD and nonasthmatic controls. GLP-1R expression was higher on murine platelets than on leukocytes. A single dose of liraglutide inhibited Lys-ASA-induced increases in airway resistance and decreased markers of platelet activation and recruitment to the lung in AERD-like mice. Liraglutide attenuated thromboxane receptor agonist-induced activation as measured by CXCL7 release in plasma from patients with AERD and CD62P expression in platelets from both patients with AERD (n = 31) and nonasthmatic, healthy controls (n = 11). Liraglutide, a Food and Drug Administration-approved GLP-1R agonist for treatment of type 2 diabetes and obesity, attenuates invivo platelet activation in an AERD murine model and invitro activation in human platelets in patients with and without AERD. These data advance the GLP-1R axis as a new target for platelet-mediated inflammation warranting further study in asthma.

Inhibition of TP signaling promotes endometriosis growth and neovascularization.

Endometriosis is highly dependent on angiogenesis and lymphangiogenesis. Prostaglandin E2, an arachidonic acid metabolite, has been shown to promote the formation of new blood and lymphatic vessels. However, the role of another arachidonic acid metabolite, thromboxane A2 (TXA2) in angiogenesis and lymphangiogenesis during endometriosis remains largely unexplored. Using a murine model of ectopic endometrial transplantation, fragments from the endometrium of WT donor mice were transplanted into the peritoneal walls of recipient WT mice (WT→WT), resulting in an increase in both the area and density of blood and lymphatic vessels. Upon transplantation of endometrial tissue from thromboxane prostanoid (TP) receptor (TXA2 receptor)‑deficient (TP‑/‑) mice into TP‑/‑ mice (TP‑/‑→TP‑/‑), an increase in implant growth, angiogenesis, and lymphangiogenesis were observed along with upregulation of pro‑angiogenic and lymphangiogenic factors, including vascular endothelial growth factors (VEGFs). Similar results were obtained using a thromboxane synthase (TXS) inhibitor in WT→WT mice. Furthermore, TP‑/‑→TP‑/‑ mice had a higher number of F4/80+ cells than that of WT→WT mice, with increased expression of genes related to the anti‑inflammatory macrophage phenotype in endometrial lesions. In cultured bone marrow (BM)‑derived macrophages, the levels of VEGF‑A, VEGF‑C, and VEGF‑D decreased in a TP‑dependent manner. Furthermore, TP signaling affected the polarization of cultured BM‑derived macrophages to the anti‑inflammatory phenotype. These findings imply that inhibition of TP signaling promotes endometrial implant growth and neovascularization.

Soluble epoxide hydrolase maintains steady-state lipid turnover linked with autocrine signaling in peritoneal macrophages

Soluble epoxide hydrolase is a widely distributed bifunctional enzyme that contains N-terminal phosphatase (N-phos) and C-terminal epoxide hydrolase (C-EH) domains. C-EH hydrolyzes anti-inflammatory epoxy-fatty acids to corresponding diols and contributes to various inflammatory conditions. However, N-phos hasbeen poorly examined. In peritoneal macrophages, the N-phos inhibitor amino-hydroxybenzoic acid (AHBA) seemed to primarily interrupt the dephosphorylation of lysophosphatidates and broadly attenuated inflammation-related functions. AHBA activated intrinsic lysophosphatidate and thromboxane A2 receptors by altering lipid-metabolite distribution; downstream the signaling, phospholipase C was facilitated to dampen intracellular Ca2+ stores and AKT kinase (protein kinase B) was activated to presumably inhibit inflammatory gene expression. Our data suggest that N-phos maintains steady-state phospholipid turnover connecting autocrine signaling and is a prospective target for controlling inflammatory responses in macrophages.

On-treatment platelet reactivity through the thromboxane A2 or P2Y12 platelet receptor pathways is not affected by pelacarsen.

Pelacarsen decreases plasma levels of lipoprotein(a) [Lp(a)] and oxidized phospholipids (OxPL). It was previously reported that pelacarsen does not affect the platelet count. We now report the effect of pelacarsen on on-treatment platelet reactivity. Subjects with established cardiovascular disease and screening Lp(a) levels ≥60mg per deciliter (~ ≥150 nmol/L) were randomized to receive pelacarsen (20, 40, or 60mg every 4 weeks; 20mg every 2 weeks; or 20mg every week), or placebo for 6-12 months. Aspirin Reaction Units (ARU) and P2Y12 Reaction Units (PRU) were measured at baseline and the primary analysis timepoint (PAT) at 6 months. Of the 286 subjects randomized, 275 had either an ARU or PRU test, 159 (57.8%) were on aspirin alone and 94 (34.2%) subjects were on dual anti-platelet therapy. As expected, the baseline ARU and PRU were suppressed in subjects on aspirin or on dual anti-platelet therapy, respectively. There were no significant differences in baseline ARU in the aspirin groups or in PRU in the dual anti-platelet groups. At the PAT there were no statistically significant differences in ARU in subjects on aspirin or PRU in subjects on dual anti-platelet therapy among any of the pelacarsen groups compared to the pooled placebo group (p > 0.05 for all comparisons). Pelacarsen does not modify on-treatment platelet reactivity through the thromboxane A2 or P2Y12 platelet receptor pathways.

The mast cell stimulator compound 48/80 causes urothelium-dependent increases in murine urinary bladder contractility.

Mast cells and degranulation of preformed inflammatory mediators contribute to lower urinary tract symptoms. This study investigated pathways by which the mast cell stimulator compound 48/80 alters urinary bladder smooth muscle contractility via mast cell activation. We hypothesized that 1) mast cell degranulation causes spontaneous urinary bladder smooth muscle contractions and 2) these contractions are caused by urothelium-derived PGE2. Urothelium-intact and -denuded urinary bladder strips were collected from mast cell-sufficient (C57Bl/6) and mast cell-deficient (B6.Cg-Kitw-sh) mice to determine if compound 48/80 altered urinary bladder smooth muscle (UBSM) contractility. Electrical field stimulation was used to assess the effects of compound 48/80 on nerve-evoked contractions. Antagonists/inhibitors were used to identify prostanoid signaling pathways activated or if direct activation of nerves was involved. Compound 48/80 caused slow-developing contractions, increased phasic activity, and augmented nerve-evoked responses in both mast cell-sufficient and -deficient mice. Nerve blockade had no effect on these responses; however, they were eliminated by removing the urothelium. Blockade of P2 purinoreceptors, cyclooxygenases, or G protein signaling abolished compound 48/80 responses. However, only combined blockade of PGE2 (EP1), PGF2α (FP), and thromboxane A2 (TP) receptors inhibited compound 48/80-induced responses. Thus, the effects of compound 48/80 are urothelium dependent but independent of mast cells. Furthermore, these effects are mediated by druggable inflammatory pathways that may be used to manage inflammatory nonneurogenic bladder hyperactivity. Finally, these data strongly suggest that great care must be taken when using compound 48/80 to determine mast cell-dependent responses in the urinary bladder.NEW & NOTEWORTHY Urothelial cells are first responders to noxious contents of the urine. Our study demonstrates that the urothelium is not only a barrier but also a modulator of urinary bladder smooth muscle phasic activity and contractility independent of immune cell recruitment in response to an inflammatory insult.

Effects of the thromboxane receptor antagonist S18886 in the porcine coronary circulation

Thromboxane A2 (TxA 2 ) is a potent coronary vasoconstrictor that has been implicated in promoting decreases in myocardial perfusion in a variety of (patho)-physiologic conditions. S18886 is a promising orally-active TxA 2 receptor antagonist currently approved for investigational clinical use. However, the coronary vascular effects of S18886 are unknown and its specificity and affinity for the thromboxane receptor in the coronary circulation remain unclear. We tested the hypothesis that administration of S18886 dose-dependently attenuates coronary vasoconstriction to the TxA 2 mimetic U46619 without influencing coronary responses to prostaglandin F 2α , acetylcholine, or smooth muscle depolarization (K + ). Experiments to test this hypothesis were performed in male (n = 5) and female (n = 6) domestic swine. Hearts were excised and the left circumflex coronary artery isolated, cleaned of periadventitial fat, and cut into 3 mm rings. Isometric tension of coronary artery rings was measured in response to log order increments of U46619 (1 nM to 1 μM) with and without S18886 (0.1-100 nM). Similar isometric studies were conducted with prostaglandin F 2α (10 nM-10 μM), acetylcholine (0.1-10 μM), and KCl (5-90 mM). U46619 induced concentration dependent increases in tension development of isolated coronary artery rings (average EC50 of 42 ± 19 nM). Incubation of coronary arteries with S18886 (1 nM) significantly attenuated coronary vasoconstriction to U46619 resulting in a rightward shift of the EC50 to 187 ± 38 nM (P &lt; 0.02). Vehicle had no effect on U46619-induced contractions. Higher concentrations of S18886 (10nM and 100nM) dose-dependently reduced U46619-induced contractions by 77% ± 3 and 93% ± 6 respectively. S18886 (1 nM) antagonized coronary vasoconstriction of prostaglandin F2α (10 μM) by 68% ± 5 (P &lt; 0.0001) but had no effect on either acetylcholine or KCl-induced contraction. Data from this investigation indicate that S18886 is an effective antagonist of U46619-induced vasoconstriction in the porcine coronary circulation. While S18886 does not influence coronary smooth muscle response to either acetylcholine or activation of L-type Ca 2+ channels, attenuation of prostaglandin F 2α suggests the antagonists specificity may extend beyond TxA 2 receptor signaling. NIH R01HL158723 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Sex differences in middle cerebral artery reactivity and hemodynamics in 6-month-old Sprague-Dawley rats independent from systemic arterial stiffness or blood pressure

Cerebrovascular disease (CVD) is a major risk factor for developing cognitive impairment. Young women are protected against CVD compared with older women or men, however the underlying mechanisms are not well understood. Greater peripheral arterial stiffness has been linked to increased cerebral flow pulsatility and cognitive impairment. In this study we determined whether sex differences in middle cerebral artery (MCA) reactivity are associated with changes in cerebral [MCA, intracranial internal carotid artery (ICA)] or systemic [common carotid artery (CCA), thoracic aorta (TAo)] arterial resistance and stiffness in six month-old Sprague-Dawley (SD) rats. No differences in systolic or diastolic blood pressures measured by tail-cuff method were observed between sexes. Heart rate was higher in the female versus male SD (438±9 vs. 343±10 bpm, p&lt;0.05, n=8-12). The pulsatility (PI) and resistance indexes (RI) of left MCA and left intracranial ICA were calculated as follows: PI=(Peak systolic velocity (Vs)-End-diastolic velocity (Vd))/Vmean, or RI=(Vs-Vd)/Vs (Vevo LAZR, FUJIFILM VisualSonics). Left MCA PI and RI indexes were lower in the female versus male SD (PI: 0.75±0.09 vs. 1.17±0.11; RI: 0.49±0.04 vs. 0.63±0.03, all p&lt;0.05; n=7-8), while no differences in left ICA blood flow (n=4-9) or resistance (n=7-10) were observed between sexes. There were no differences in arterial stiffness of TAo or left CCA evaluated by pulse wave velocity (PWV) measurements. To investigate vascular reactivity, left MCA segments were isolated and mounted on a wire Multi Myograph (DMT-USA). Data were acquired and analyzed with Powerlab 8 and LabChart v8 (ADInstruments). Female left MCA had lower contraction to potassium (K+: 0.6±0.1 vs. 1±0.2 mN/mm, p&lt;0.05), but similar maximal contraction (109±10 vs. 116±6 %KMAX, p&gt;0.05) and sensitivity (7.3±0.2 vs. 7.2±0.2, p&gt;0.05) to thromboxane A2 receptor agonist U46619. Pre-incubation with indomethacin lowered maximal response (97±5 vs. 116±6 %KMAX, p&lt;0.05) and sensitivity (6.8±0.1 vs. 7.2±0.2, p&lt;0.05) to U46619 in male MCA, with no effect in female MCA (Male: 109±9 vs. 113±7 %KMAX; Female: 7.3±0.2 vs. 7.3±0.2). MCA collagen deposition (by trichrome staining) was similar between sexes, however eNOS immunoreactivity tended to increase in the female versus male MCA (7.3±2 vs. 1.2±0.6; n=3-4, p=0.07). No sex differences in MCA COX-2 expression were found. In summary, lower PI and RI of MCA in 6-month-old females suggests decreased cerebrovascular resistance compared with age-matched male SD. Increased eNOS expression may contribute to the lower contraction observed in female MCA, whereas vasoconstrictor prostaglandins appear to have a greater role in male versus female MCA. Our results demonstrate sex differences in MCA vascular reactivity associated with a protective functional profile of MCA in 6-month-old female versus male SD rats independent from changes in systemic arterial stiffness or blood pressure. Studies were supported by the WFUSM CVSC Pilot Award and NIH 5R01HL155420. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Endoplasmic reticulum protein 5 attenuates platelet endoplasmic reticulum stress and secretion in a mouse model.

Extracellular protein disulfide isomerases (PDIs), including PDI, endoplasmic reticulum protein 57 (ERp57), ERp72, ERp46, and ERp5, are required for invivo thrombus formation in mice. Platelets secrete PDIs upon activation, which regulate platelet aggregation. However, platelets secrete only ∼10% of their PDI content extracellularly. The intracellular role of PDIs in platelet function is unknown. Here, we aim to characterize the role of ERp5 (gene Pdia6) using platelet conditional knockout mice, platelet factor 4 (Pf4) Cre+/ERp5floxed (fl)/fl. Pf4Cre+/ERp5fl/fl mice developed mild macrothrombocytopenia. Platelets deficient in ERp5 showed marked dysregulation of their ER, indicated by a twofold upregulation of ER proteins, including PDI, ERp57, ERp72, ERp46, 78 kilodalton glucose-regulated protein (GRP78), and calreticulin. ERp5-deficient platelets showed an enhanced ER stress response to exvivo and invivo ER stress inducers, with enhanced phosphorylation of eukaryotic translation initiation factor 2A and inositol-requiring enzyme 1 (IRE1). ERp5 deficiency was associated with increased secretion of PDIs, an enhanced response to thromboxane A2 receptor activation, and increased thrombus formation invivo. Our results support that ERp5 acts as a negative regulator of ER stress responses in platelets and highlight the importance of a disulfide isomerase in platelet ER homeostasis. The results also indicate a previously unanticipated role of platelet ER stress in platelet secretion and thrombosis. This may have important implications for the therapeutic applications of ER stress inhibitors in thrombosis.