Thromboxane Production Research Articles

The Presence of TGFβ3 in Human Ovarian Intrafollicular Fluid and Its Involvement in Thromboxane Generation in Follicular Granulosa Cells through a Canonical TGFβRI, Smad2/3 Signaling Pathway and COX-2 Induction.

Ovarian follicular fluid (FF) has a direct impact on oocyte quality, playing key roles in fertilization, implantation, and early embryo development. In our recent study, we found FF thromboxane (TX) to be a novel factor inversely correlated with oocyte maturation and identified thrombin, transforming growth factor β (TGFβ), TNF-α, and follicular granulosa cells (GCs) as possible contributors to FF TX production. Therefore, this study sought to investigate the role of TGFβ3 in regulating TX generation in human ovarian follicular GCs. TGFβ3 was differentially and significantly present in the FF of large and small follicles obtained from IVF patients with average concentrations of 68.58 ± 12.38 and 112.55 ± 14.82 pg/mL, respectively, and its levels were correlated with oocyte maturity. In an in vitro study, TGFβ3 induced TX generation/secretion and the converting enzyme-COX-2 protein/mRNA expression both in human HO23 and primary cultured ovarian follicular GCs. While TGFβRI and Smad2/3 signaling was mainly required for COX-2 induction, ERK1/2 appeared to regulate TX secretion. The participation of Smad2/3 and COX-2 in TGFβ3-induced TX generation/secretion could be further supported by the observations that Smad2/3 phosphorylation and nuclear translocation and siRNA knockdown of COX-2 expression compromised TX secretion in GCs challenged with TGFβ3. Taken together, the results presented here first demonstrated that FF TGFβ3 levels differ significantly in IVF patients' large preovulatory and small mid-antral follicles and are positively associated with oocyte maturation. TGFβ3 can provoke TX generation by induction of COX-2 mRNA/protein via a TGFβR-related canonical Smad2/3 signaling pathway, and TX secretion possibly by ERK1/2. These imply that TGFβ3 is one of the inducers for yielding FF TX in vivo, which may play a role in folliculogenesis and oocyte maturation.

Maternal nano-titanium dioxide inhalation exposure alters placental cyclooxygenase and oxidant balance in a sexually dimorphic manner

The placenta plays a critical role in nutrient-waste exchange between the maternal and fetal circulation, and thus impacts fetal growth and development. We have previously shown that nano-titanium dioxide (nano-TiO2) inhalation exposure during gestation decreased fetal female pup and placenta mass [1], which persists in the following generation [2]. In utero exposed females, once mated, their offspring's placentas had increased capacity for H2O2 production. Generation of oxidants such as hydrogen peroxide (H2O2), have been shown to impact cyclooxygenase activity, specifically metabolites such as prostacyclin (PGI2) or thromboxane (TXA2). Therefore, we hypothesized that maternal nano-TiO2 inhalation exposure during gestation results in alterations in placental production of prostacyclin and thromboxane mediated by enhanced H2O2 production in a sexually dimorphic manner. Pregnant Sprague-Dawley rats were exposed to nano-TiO2 aerosols or filtered air (sham-control) from gestational day (GD) 10–19. Dams were euthanized on GD 20, and fetal serum and placental tissue were collected based on fetal sex. Fetal placental zones (junctional zone (JZ) and labyrinth zone (LZ)) were assessed for xanthine oxidoreductase (XOR) activity, H2O2, and catalase activity, as well as 6-keto-PGF1α and TXB2 levels. Nano-TiO2 exposed fetal female LZ demonstrated significantly greater XOR activity compared to exposed males. Exposed fetal female LZ also demonstrated significantly diminished catalase activity compared to sham-control females. Exposed fetal female LZ had significantly increased abundance of 6-keto-PGF1α compared to sham-control females and increased TXB2 compared to exposed males. In the aggregate these data indicate that maternal nano-TiO2 inhalation exposure has a greater impact on redox homeostasis and PGI2/TXA2 balance in the fetal female LZ. Future studies need to address if treatment with an XO inhibitor during gestation can prevent diminished fetal female growth during maternal nano-TiO2 inhalation exposure.

Novel thiazolopyridine derivatives of diflapolin as dual sEH/FLAP inhibitors with improved solubility

Inflammatory responses are orchestrated by a plethora of lipid mediators, and perturbations of their biosynthesis or degradation hinder resolution and lead to uncontrolled inflammation, which contributes to diverse pathologies. Small molecules that induce a switch from pro-inflammatory to anti-inflammatory lipid mediators are considered valuable for the treatment of chronic inflammatory diseases. Commonly used non-steroidal anti-inflammatory drugs (NSAIDs) are afflicted with side effects caused by the inhibition of beneficial prostanoid formation and redirection of arachidonic acid (AA) into alternative pathways. Multi-target inhibitors like diflapolin, the first dual inhibitor of soluble epoxide hydrolase (sEH) and 5-lipoxygenase-activating protein (FLAP), promise improved efficacy and safety but are confronted by poor solubility and bioavailability. Four series of derivatives bearing isomeric thiazolopyridines as bioisosteric replacement of the benzothiazole core and two series additionally containing mono- or diaza-isosteres of the phenylene spacer were designed and synthesized to improve solubility. The combination of thiazolo[5,4-b]pyridine, a pyridinylen spacer and a 3,5-Cl2-substituted terminal phenyl ring (46a) enhances solubility and FLAP antagonism, while preserving sEH inhibition. Moreover, the thiazolo[4,5-c]pyridine derivative 41b, although being a less potent sEH/FLAP inhibitor, additionally decreases thromboxane production in activated human peripheral blood mononuclear cells. We conclude that the introduction of nitrogen, depending on the position, not only enhances solubility and FLAP antagonism (46a), but also represents a valid strategy to expand the scope of application towards inhibition of thromboxane biosynthesis.

Cyclooxygenase Inhibitors and Cancer: The Missing Pieces.

At 125, aspirin still represents the cornerstone of anti-platelet therapy for the acute treatment and long-term prevention of atherothrombosis. The development of a selective regimen of low-dose aspirin for the inhibition of platelet thromboxane production was key to maximizing its antithrombotic efficacy and minimizing its gastrointestinal toxicity. Based on about 50 observational studies, published over the past 30 years, aspirin and other cyclooxygenase inhibitors have been associated with a reduced risk of colorectal cancer, and possibly other digestive tract cancers. The apparent chemopreventive effect of aspirin has been confirmed in post-hoc analyses of randomized cardiovascular trials and their meta-analyses. Moreover, prevention of sporadic colorectal adenoma recurrence was demonstrated by randomized controlled trials of low-dose aspirin and selective cyclooxygenase-2 inhibitors. A single placebo-controlled randomized trial of aspirin has shown long-term colorectal cancer prevention in patients with the Lynch syndrome. The sequential involvement of thromboxane-dependent platelet activation and cyclooxygenase-2-driven inflammatory response in the early stages of colorectal carcinogenesis may explain these clinical benefits. The aim of this mini-review is to analyze the existing evidence for a chemopreventive effect of aspirin and other cyclooxygenase inhibitors and discuss the missing pieces of this mechanistic and clinical puzzle. SIGNIFICANCE STATEMENT: Low-dose aspirin and other cyclooxygenase inhibitors have been associated with a reduced risk of colorectal cancer, and possibly other digestive tract cancers. The sequential involvement of thromboxane-dependent platelet activation and cyclooxygenase-2-driven inflammatory response in the early stages of colorectal carcinogenesis may explain these clinical benefits. The aim of this mini-review is to analyze the evidence for a chemopreventive effect of aspirin and other cyclooxygenase inhibitors and discuss the missing pieces of this mechanistic and clinical puzzle.

Aspirin Inhibits the Inflammatory Response of Protease-Activated Receptor 1 in Pregnancy Neutrophils: Implications for Treating Women with Preeclampsia.

Neutrophils expressing cyclooxygenase-2 (COX-2) extensively infiltrate maternal blood vessels in preeclampsia, associated with vascular inflammation. Because pregnancy neutrophils also express protease-activated receptor 1 (PAR-1, F2R thrombin receptor), which they do not in non-pregnant subjects, they can be activated by proteases. We tested the hypothesis that aspirin at a dose sufficient to inhibit COX-2 would reduce inflammatory responses in preeclampsia neutrophils. Neutrophils were isolated from normal pregnant and preeclamptic women at approximately 30 weeks' gestation. Normal pregnancy neutrophils were treated with elastase, a protease elevated in preeclampsia, or elastase plus aspirin to inhibit COX-2, or elastase plus pinane thromboxane, a biologically active structural analog of thromboxane and a thromboxane synthase inhibitor. Preeclamptic pregnancy neutrophils were treated with the same doses of aspirin or pinane thromboxane. Confocal microscopy with immunofluorescence staining was used to determine the cellular localization of the p65 subunit of nuclear factor-kappa B (NF-κB) and media concentrations of thromboxane were measured to evaluate the inflammatory response. In untreated neutrophils of normal pregnant women, p65 was localized to the cytosol. Upon stimulation with elastase, p65 translocated from the cytosol to the nucleus coincident with increased thromboxane production. When neutrophils were co-treated with aspirin or pinane thromboxane, elastase was not able to cause nuclear translocation of p65 or increase thromboxane. In untreated neutrophils of preeclamptic women, the p65 subunit was present in the nucleus and thromboxane production was elevated, but when preeclamptic neutrophils were treated with aspirin or pinane thromboxane, p65 was cleared from the nucleus and returned to the cytosol along with decreased thromboxane production. These findings suggest that COX-2 is a downstream mediator of PAR-1 and demonstrate that PAR-1- mediated inflammation can be inhibited by aspirin. Given the extensive and ubiquitous expression of PAR-1 and COX-2 in preeclamptic women, consideration should be given to treating women with preeclampsia using a dose of aspirin sufficient to inhibit COX-2.

Effect of Antiplatelet Activity of Aspirin on Chronic Kidney Disease

Background and aim: Individual differences in the pharmacological responsiveness to aspirin are considerable. A higher likelihood of ischemic episodes is linked to aspirin's inadequate antiplatelet actions. It has been hypothesized that chronic kidney disease (CKD) influences the pharmacologic reaction to antiplatelet drugs. The elevated chance of fatality and cardiovascular problems in CKD sufferers has already been found to be largely explained by high on-treatment platelets response (HTPR) to clopidogrel. This research aimed to examine at how aspirin affects blood clotting in CKD sufferers. Method: We performed cross-sectional research on 120 people in Medical center of Lahore taking aspirin regularly. The thromboxane production generated by AAI was used to gauge the pharmacologic reaction to aspirin. Result: Individuals with poor kidney functioning were more likely to experience HTPR to aspirin (48% vs. 23%; odds ratio, 3.17; 95% confidence interval [CI], 1.35-7.42; P = 0.007). When compared to individuals with healthy or mildly diminished kidney performance, those with mild or serious CKD had lower pharmacokinetic responsiveness to aspirin (91; interquartile ranged [IQR], 281 ng mL-1; differential in medians, 56; CI, 6-110 ng mL-1; P = 0.012). Remaining thromboxane production and glomerular filtration rate were both associated by bivariate Pearson correlation analysis (R = 0.312; R2 = 0.093; P = 0.001). Individuals with CKD were usually old age and being women. Women and aged were not significant predictors of the connection, according to multivariate linear regression analyses (R = 0.313; R2 = 0.081; P = 0.002 and P = 0.006) respectively. Conclusion: Aspirin pharmacological reaction is associated with kidney function. Individuals who have CKD are more likely to have aspirin's antiplatelet action compromised. To evaluate the therapeutic significance of this data and look into the best antithrombotic strategy for CKD individuals, additional research is required. Keywords: Chronic kidney disease, platelets, treatment, aspirin, cardiovascular

High Risk of Cardiovascular Events in Patients, Biosynthesis of Aspirin-Resistant Thromboxane And The Risk Of Stroke, Myocardial Infarction Or Death

In a higher-risk group, we investigated if aspirin resistance, which is defined as inability to reduce production of thromboxane, enhanced the risk for cardiovascular disease. Methods: The Cardiac Outcome Preventive Assessment Study collected baseline urine samples from 5000 patients. A level of urinary 11-dehydro-thromboxane B2 was measured, which is a marker of within vitro cell generation of thromboxane, in 400 cured patients with aspirin having a cardiovascular death, stroke and infarction, stroke during a 5-year follow-up and in 400 age - and matching sex control subjects, which did not have an event, using a nested case-control design. Result: After accounting for baseline differences, the risks of infarction, strokes, or cardiac mortality rose with every fourth of 11-dihydro-thromboxane B2, with individuals in the top fourth section having a 1.9-fold greater threat than those from the lower portion (“OR, 1.9; 95% CI, 1.3 to 2.8; p=0.009). The upper quartile showed a 2-fold increased myocardial infarction risk ("OR, 2.1; 95% CI, 1.3 to 3.5; p=0.07) and a 3.6-fold elevated risk of cardiac death ("OR, 3.6; 95% CI, 1.78to 7.5; p=0.01) than the lower quartile. Conclusions: the 11-dehydro thromboxane B2 level in urine, better determine the risk of cardiovascular events or cardiovascular death in aspirin-treated patients. These findings also depicts that patients with elevated urine 11-dehydro thromboxane B2 concentrations are more impervious to aspirin, and could profit from greater antiplatelet medications or therapies that even more efficiently stop thromboxane generation in vivo or activities.

P809: MODULATION OF ARACHIDONIC ACID PATHWAY BY IBUPROFEN RESULTS IN COMPLETE HEMATOLOGICAL RESPONSE IN GHOSAL HEMATODIAPHYSEAL DYSPLASIA WITHOUT NEED FOR CORTICOSTEROID

Background: Ghosal hematodiaphyseal dysplasia (GHDD) is a rare autosomal recessive disorder characterized by pancytopenia and increased bone density of the long bones. First described in families of Indian and Middle Eastern descent, subsequent studies identified the genetic lesion in this disease as due to loss of function mutations in the TBXAS1 gene encoding thromboxane synthase, a key component of the arachidonic acid pathway responsible for the formation of thromboxane A2 from prostaglandin H2. As well as pancytopenia, laboratory features include platelet aggregation defects and increase in osteoblastic activity, the latter being the basis of increased bone density in patients with Ghosal syndrome. Simultaneously, loss of thromboxane synthase activity may be associated with shunting of prostaglandin precursors away from production of thromboxane into production of pro-inflammatory prostaglandins. This may be the mechanism responsible for the observed marrow suppression seen in these patients. We describe a 3 year old female of non-consanguineous parents of Filipino origin who presented with marked pancytopenia. Next Generation Sequencing bone marrow failure gene panel revealed a novel homozygous mutation in TBXAS1. Subsequent DXA scanning revealed increased bone mineral density consistent with the diagnosis (Z -score +2.4 for lumbar spine (L1-4)) although clinical sequelae of bony disease were not apparent. Aims: While multiple case reports document that these patients have hematological response to long term corticosteroid therapy, we hypothesized that inhibition of cyclooxygenase (COX) upstream of thromboxane synthase in the arachidonic acid pathway may be effective in this condition. Methods: Patient was treated with ibuprofen at regular therapeutic doses (approximately 30 mg/kg/24 hours daily initially) and serial full blood counts were monitored. Results: The patient exhibited a rapid and complete response to ibuprofen with normalization of full blood counts. The dose of ibuprofen was reduced to 10 mg/kg/day, and hematologic response is maintained on low dose after one year.The treatment is well tolerated with no side effects. Image:Summary/Conclusion: Treatment of GHDD with ibuprofen is a novel approach that offers clear potential benefits in comparison to the known adverse effects profile of long term corticosteroids. Bone density scan and markers are in process to ascertain the impact of this treatment on bone density, although this may take longer to show beneficial effects. The treatment was easily tolerated and well managed by the patient and family at home with minimum disruption to her quality of life.

Low-dose aspirin for the prevention of atherothrombosis across the cardiovascular risk continuum

Abstract At the 2021 International Aspirin Foundation Symposium of Oriental Congress of Cardiology, a panel of distinguished cardiologists from around the world gathered to present their recent research findings and discuss viewpoints of aspirin use along the entire continuum of cardiovascular disease (CVD) prevention in the general population as well as in specific patient groups. Aspirin produces long-lasting effects on platelet function and cumulative inhibition of platelet thromboxane production by irreversibly inactivating the prostaglandin H-synthase (PGHS). Consistent with saturability of platelet cyclooxygenase 1 (COX-1) inactivation and thromboxane A2 (TXA2) suppression at low doses, a body of convincing evidence showed no additional benefit from high versus low-dose aspirin. Trials of aspirin as primary prevention trials are challenging due to the low event rate and reduced patient compliance over time. Nevertheless, evidence from the ASCEND and TIPS3 trials supported the benefit of aspirin in primary cardiovascular prevention. The Chinese population has among the highest CVD risk in the world. Significant achievement has been made in this respect. For example, the benefit of aspirin use as primary prevention is now recognized in the Chinese guidelines similar to the US, European guidelines, with some unique features that are helpful for the Chinese population (eg, greater emphasis on dynamical reassessment of risk versus benefit). As secondary prevention in patients with transient ischaemic attack (TIA) and minor stroke, low-dose aspirin reduces the risk of major recurrent stroke as well as stroke severity. Peripheral arterial disease (PAD) management and screening is of growing importance. The COMPASS and VOYAGER studies provide new evidence for dual-pathway inhibition (DPI) antithrombotic therapy with low-dose aspirin and reduced-dose rivaroxaban. A major concern with the use of aspirin is the risk of gastrointestinal (GI) bleeding. Strategies to protect patients include eradication of Helicobacter pylori infection and co-prescription of proton pump inhibitors. Different P2Y12 inhibitors and low-dose aspirin have similar levels of bleeding risk, but the risk is magnified when these agents are taken together.

Analysis of the Cochrane Review: Antiplatelet Agents for Preventing Pre-Eclampsia and Its Complications. Cochrane Database Syst Rev. 2019;10:CD004659.

Pre-eclampsia is associated with deficient intravascular production of prostacyclin, a vasodilator, and excessive production of thromboxane, a vasoconstrictor and stimulant of platelet aggregation. These observations led to the hypotheses that antiplatelet agents, low-dose aspirin in particular, might prevent or delay development of pre-eclampsia. This Cochrane review aimed to assess the effectiveness and safety of antiplatelet agents, such as aspirin and dipyridamole, when given to women at risk of developing preeclampsia. A systematic review of literature was carried out by searching the following databases up to September 2019: Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP), and reference lists of retrieved studies. Seventy-seven trials were included, including 40 249 women at risk of developing pre-eclampsia. About 80% of these women were evaluated in nine of the 77 trials included, with eight of these nine trials providing individual data. Interventions were administration of an antiplatelet agent, and comparisons were either placebo or no antiplatelet. The present review provides high-quality evidence that administering low-dose aspirin (50 - 150 mg) to pregnant women led to small-to-moderate benefits, including reductions in the risk of pre-eclampsia, preterm birth, small-for-gestational age fetus, and fetal or neonatal death. Overall, administering antiplatelet agents to 1000 women led to 20 fewer pregnancies with serious adverse outcomes.

Urinary 11-dehydrothromboxane B2 aspirin efficacy testing is sensitive to perioperative inflammation in pediatric solid-organ transplant patients.

Evidence for aspirin efficacy testing in pediatrics is limited, especially outside of cardiology, yet thrombotic events have high morbidity in other areas such as pediatric transplant surgery. Debates about whether thromboembolic events while on aspirin represent "aspirin resistance" or "high on-treatment platelet reactivity" persist, given the poor intertest agreement between testing platforms. This prospective observational study involved measuring aspirin efficacy using ex vivo testing of platelet aggregation (VerifyNow-Aspirin, VN) and urine 11-dehydrothromboxane B2 (AsprinWorks, UTxB2) contemporaneously at up to three time points after major noncardiac organ transplant surgery. The collection days (CD) were the second and seventh days after stable aspirin dosing and then a convalescent time point 2-9 months later. Fifty-five participants (age range, 0-21 years) were enrolled, having undergone total pancreatectomy with islet autotransplantation (N=36), orthotopic liver transplantation (N=18), and combined liver-kidney transplantation (N=1). Platelet reactivity measured by VN remained unchanged, whereas UTxB2, which was elevated postoperatively, decreased significantly from CD1 to CD2 and CD3. Discordance in therapeutic efficacy was noted per manufacturer cutoffs, with therapeutic VN results in 86% of tests, whereas 12% of UTxB2 were therapeutic. Age-based stratification of UTxB2 results using previously published pediatric median levels increased overall UTxB2 therapeutic rates (80%) and intertest concordance (67% vs 27% if using adult range). No thrombotic events were observed. Our data suggest that urine thromboxane production may be an underappreciated reflection of postoperative inflammation. Validation of pediatric normal ranges for UTxB2 is a critical next step.

Characterization of an Unknown Impurity in Indobufen Tablets by HPLC-Q-TOF MS and NMR

Background: Indobufen is a drug that hinders the aggregation of platelets by reversibly repressing the cyclooxygenase enzyme, further bringing about diminished thromboxane production. During quality control of indobufen tablets, an unknown impurity was detected. Objective: To characterize an unknown impurity in indobufen tablets. Methods: A new method compatible with mass spectrometry detection was set up. A C18 column at 35 °C with a mobile phase consisting of aqueous buffer (including ammonium formate) and methanol (35: 65, v/v) was used at a flow rate of 1.0 mL/min at 228 nm. High-performance liquid chromatography quadrupole time-of-flight mass spectrometry mass spectrometry (HPLC-Q-TOF MS) was used to identify the impurity with the electrospray ionization (ESI) source in the positive ionization mode. Results: The results of HPLC-Q-TOF MS analysis indicated that the protonated molecule ions [M + H]+ of the unknown impurity was at m/z 312. Preparative LC method was put into practice with a Prep- C18 column with a mobile phase consisting of water and methanol (20: 80, v/v) at a flow rate of 20.0 mL/min at 228 nm. The assignment of the 1D and 2D NMR signals was performed for the unknown impurity. In addition, possible formation of the novel impurity was also studied. Conclusion: An unknown impurity in indobufen tablets was characterized. The impurity was assigned as 2-(4-(1-hydroxy-3-oxoisoindolin-2-yl) phenyl) butanoic acid.

TULA-2 Deficiency Enhances Platelet Response to CLEC-2 Agonists

Background: Platelet activation is essential for hemostasis. Central to platelet activation are the signals transmitted through surface receptors like GPVI, the protease activated receptors (PARs), and C-type lectin-like receptor 2 (CLEC-2). Clec-2 is a HemITAM-bearing receptor that binds podoplanin and signals through spleen tyrosine kinase (Syk). Syk activity is dependent on phosphorylation of several residues including Y348, Y352, and Y525/526 (Y342, Y346, and Y519/520 in mice). TULA-2 is a protein tyrosine phosphatase that is highly expressed in platelets, and targets phosphorylated Y352 of Syk. Therefore, we used TULA-2 knockout mouse platelets to determine whether or not TULA-2 regulates Syk phosphorylation and activity downstream of CLEC-2.Results: Using washed platelets from WT and TULA-2 KO mice we determined that TULA-2 deficiency enhances the aggregation and secretion response following stimulation with an excitatory CLEC-2 antibody (Figure 1) or a CLEC-2 agonist rhodocytin. Consistently, Syk phosphorylation of Y346 is enhanced, as well as phosphorylation of the Syk substrate PLCγ2, in TULA-2 KO platelets treated with either CLEC-2 antibody or rhodocytin, compared to WT control platelets. Furthermore, the kinetics of Syk phosphorylation, as well as that of PLCγ2 and SLP-76 are enhanced in TULA-2 KO platelets treated with 2.5 μg/mL CLEC-2 antibody compared to WT platelets. Platelet activation results in secretion of granular contents as well as production of thromboxane, which serves to reinforce the primary excitatory signal and to activate other platelets. Similar to our results above, thromboxane production was enhanced, in both amount and kinetics, in TULA-2 KO platelets treated with 2.5 μg/mL CLEC-2 antibody (Figure 2).Conclusions: TULA-2 acts as a negative regulator of CLEC-2 signaling by dephosphorylating Syk on Y352 and restraining subsequent Syk-mediated signaling. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Persistent long-term platelet activation and endothelial perturbation in women with Takotsubo syndrome

BackgroundTakotsubo (TTS) syndrome is an acute cardiac condition characterized by transient and reversible left ventricle dysfunction that mainly affects postmenopausal women. Catecholamine burst is the most accredited mechanism underpinning TTS onset and leading to endothelial dysfunction and platelet activation. Even if the use of low dose acetylsalycilic acid (ASA) in this clinical setting is based on both clinical presentation and unfavorable long-term prognosis, its efficacy has been recently challenged. AimThis study was designed to assess endothelial function, residual thromboxane formation and platelet aggregation in TTS women on low-dose ASA treatment at long-term follow-up. MethodsTwenty-eight females with previously diagnosis of TTS syndrome were enrolled. Data were compared to those obtained from 23 coronary artery disease (CAD) women with a history of acute myocardial infarction, and 26 control subjects with no TTS or clinically evident CAD. Psychological and clinical profile were assessed in all study groups at the enrollment. Main metabolites involved in L-arginine/nitric oxide pathway, urinary prostacyclin, serum and urine thromboxane metabolites were measured by LCMS/MS methods. Thrombomodulin levels were quantified using an ELISA kit, and platelet aggregation, carried out on platelet rich-plasma, was induced by ADP or by epinephrine (EPI), norepinephrine (NORE) and TRAP-6, alone or in association with ADP and evaluated by Born’s method. ResultsIn TTS women an endothelial derangement, characterized by reduced citrulline production and increased thrombomodulin concentration, with no perturbation in prostacyclin levels, was evidenced. In addition, despite ASA treatment, TTS displayed a higher residual thromboxane formation, in parallel with an enhanced platelet response to compared to CAD. ConclusionsOur study highlighted the presence of endothelial perturbation in TTS patients even at long-term from the index event. The residual thromboxane production and platelet aggregation still leave open the question about the use of low dose ASA in this clinical setting.

The Emerging Role of the Double-Edged Impact of Arachidonic Acid- Derived Eicosanoids in the Neuroinflammatory Background of Depression.

Eicosanoids are arachidonic acid (AA) derivatives belonging to a family of lipid signalling mediators that are engaged in both physiological and pathological processes in the brain. Recently, their implication in the prolonged inflammatory response has become a focus of particular interest because, in contrast to acute inflammation, chronic inflammatory processes within the central nervous system (CNS) are crucial for the development of brain pathologies including depression.The synthesis of eicosanoids is catalysed primarily by cyclooxygenases (COX), which are involved in the production of pro-inflammatory AA metabolites, including prostaglandins and thromboxanes. Moreover, eicosanoid synthesis is catalysed by lipoxygenases (LOXs), which generate both leukotrienes and anti-inflammatory derivatives such as lipoxins. Thus, AA metabolites have double-edged pro-inflammatory and anti-inflammatory, pro-resolving properties, and an imbalance between these metabolites has been proposed as a contributor or even the basis for chronic neuroinflammatory effects.This review focuses on important evidence regarding eicosanoid-related pathways (with special emphasis on prostaglandins and lipoxins) that has added a new layer of complexity to the idea of targeting the double-edged AA-derivative pathways for therapeutic benefits in depression. We also sought to explore future research directions that can support a pro-resolving response to control the balance between eicosanoids and thus to reduce the chronic neuroinflammation that underlies at least a portion of depressive disorders.

Profiling the eicosanoid networks that underlie the anti- and pro-thrombotic effects of aspirin.

Aspirin prevents thrombosis by inhibiting platelet cyclooxygenase (COX)-1 activity and the production of thromboxane (Tx)A2, a pro-thrombotic eicosanoid. However, the non-platelet actions of aspirin limit its antithrombotic effects. Here, we used platelet-COX-1-ko mice to define the platelet and non-platelet eicosanoids affected by aspirin. Mass-spectrometry analysis demonstrated blood from platelet-COX-1-ko and global-COX-1-ko mice produced similar eicosanoid profiles in vitro: for example, formation of TxA2, prostaglandin (PG) F2α, 11-hydroxyeicosatraenoic acid (HETE), and 15-HETE was absent in both platelet- and global-COX-1-ko mice. Conversely, in vivo, platelet-COX-1-ko mice had a distinctly different profile from global-COX-1-ko or aspirin-treated control mice, notably significantly higher levels of PGI2 metabolite. Ingenuity Pathway Analysis (IPA) predicted that platelet-COX-1-ko mice would be protected from thrombosis, forming less pro-thrombotic TxA2 and PGE2. Conversely, aspirin or lack of systemic COX-1 activity decreased the synthesis of anti-aggregatory PGI2 and PGD2 at non-platelet sites leading to predicted thrombosis increase. In vitro and in vivo thrombosis studies proved these predictions. Overall, we have established the eicosanoid profiles linked to inhibition of COX-1 in platelets and in the remainder of the cardiovascular system and linked them to anti- and pro-thrombotic effects of aspirin. These results explain why increasing aspirin dosage or aspirin addition to other drugs may lessen antithrombotic protection.

Placental Production of Eicosanoids and Sphingolipids in Women Who Developed Preeclampsia on Low-Dose Aspirin.

Low-dose aspirin, which selectively inhibits thromboxane synthesis, is now standard of care for the prevention of preeclampsia in at risk women, but some women still develop preeclampsia despite an aspirin regimen. To explore the "aspirin failures," we undertook a comprehensive evaluation of placental lipids to determine if abnormalities in non-aspirin sensitive lipids might help explain why some women on low-dose aspirin develop preeclampsia. We studied placentas from women with normal pregnancies and women with preeclampsia. Placental villous explants were cultured and media analyzed by mass spectrometry for aspirin-sensitive and non-aspirin-sensitive lipids. In women who developed severe preeclampsia and delivered preterm, there were significant elevations in non-aspirin-sensitive lipids with biologic actions that could cause preeclampsia. There were significant increases in 15- and 20-hydroxyeicosatetraenoic acids and sphingolipids: D-e-C18:0 ceramide, D-e-C18:0 sphingomyelin, D-e-sphingosine-1-phosphate, and D-e-sphinganine-1-phosphate. With regard to lipids sensitive to aspirin, there was no difference in placental production of thromboxane or prostacyclin, but prostaglandins were lower. There was no difference for isoprostanes, but surprisingly, anti-inflammatory omega 3 and 6 PUFAs were increased. In total, 10 of 30 eicosanoids and 5 of 42 sphingolipids were abnormal in women with severe early onset preeclampsia. Lipid changes in women with mild preeclampsia who delivered at term were of lesser magnitude with few significant differences. The placenta produces many aspirin-sensitive and non-aspirin-sensitive lipids. Abnormalities in eicosanoids and sphingolipids not sensitive to aspirin might explain why some aspirin-treated women develop preeclampsia.

Urinary Thromboxane Production in Diabetic and Non-Diabetic Patients of Acute Coronary Syndrome

Urinary Thromboxane Production in Diabetic and Non-Diabetic Patients of Acute Coronary Syndrome

Increased Thromboxane in Patients with Polycythemia Vera and Thrombosis: Evidence for Aspirin-Unsuppressible Platelet Activation In Vivo

Polycyhemia vera (PV) is a myeloproliferative neoplasm characterized by increased thromboxane (TX) production and thrombotic risk. It is reported that serum TXB2 concentrations in PV patients are twofold higher than healthy controls and that low-dose aspirin (ASA) therapy reduces the risk of major vascular events by 50 to 60%. To evaluate this unusual size of the effect of ASA we have studied platelet count, hematocrit (HCT), β-thromboglobulin (β-TG) and platelet factor 4 (PF4), as markers of platelet activation, TXB2, as primary indicator of platelet activation, the platelet function activity (PFA), as indicator of ASA platelet sensitivity, and the clotting time (CT), as parameter of thrombin formation. We studied 60 patients (38 men, 22 women; mean age 51 years, range 32-70) with PV according to WHO criteria. The mean duration of disease was 12 years. All patients were on ASA 100 mg once daily. All patients were on phlebotomy. None had inherited or acquired thrombotic risk factors. Of 60 patients, 30 had thrombosis (20 men, 10 women) and 30 had no thrombosis. Of 30 with thrombosis, 15 developed nonfatal myocardial infarction (10 men, 5 women) defined by chest pain of typical intensity and duration and ST-segment elevation in any limb lead on electrocardiography, 10 had nonfatal stroke (8 men, 2 women) confirmed with the use of magnetic resonance imaging, and 5 (2 men , 3 women) had deep venous thrombosis confirmed by ultrasonography. Platelet count and HCT were measured by automated analyzer. β-TG and PF4 were determined by ELISA. TXB2 was measured by radioimmunoassay technique. ASA platelet sensitivity was measured by Platelet Function Analyzer (PFA-100). CT was measured by thromboelastometry. The mean platelet count was 430±170x109/L. The mean HCT value was 42±3%. The patients with thrombosis had high β-TG, PF4 and TXB2 (110±45 IU/ml, 45±21 IU/ml, and 1.700±1.990 nmol/L, respectively), shortened C/EPI closure time (T, unit: s, n.v. 84-160 s) (55±10 s) and shortened CT (CT, unit: s. n.v. 100-240 s) (45±20 s) whereas the patients without thrombosis had normal β-TG, PF4 and TXB2 (20±11 IU/ml, 6±2 IU/ml, and 800±280 nmpl/L, respectively), prolonged C/EPI closure time (249±40 s) and normal CT (110±20 s). These findings might suggest that in PV patients and thrombotic complications might need a platelet-selective dosage of ASA. Disclosures No relevant conflicts of interest to declare.

Antiplatelet agents for preventing pre-eclampsia and its complications.

Antiplatelet agents for preventing pre-eclampsia and its complications.