Urinary 11-dehydro thromboxane B₂ levels in type 2 diabetic patients before and during aspirin intake

Cardiovascular Pharmacogenomics: An Update on Clinical Studies of Antithrombotic Drugs in Brazilian Patients

Anticoagulant and antiplatelet drugs effectively prevent thrombotic events in patients with cardiovascular diseases, ischemic stroke, peripheral vascular diseases, and other thromboembolic diseases. However, genetic and non-genetic factors affect the response to antithrombotic therapy and can increase the risk of adverse events. This narrative review discusses pharmacogenomic studies on antithrombotic drugs commonly prescribed in Brazil. Multiple Brazilian studies assessed the impact of pharmacokinetic (PK) and pharmacodynamic (PD) gene variants on warfarin response. The reduced function alleles CYP2C9*2 and CYP2C9*3, and VKORC1 rs9923231 (c.-1639G>A) are associated with increased sensitivity to warfarin and a low dose requirement to prevent bleeding episodes, whereas CYP4F2 rs2108622 (p.Val433Met) carriers have higher dose requirements (warfarin resistance). These deleterious variants and non-genetic factors (age, gender, body weight, co-administered drugs, food interactions, and others) account for up to 63% of the warfarin dose variability. Few pharmacogenomics studies have explored antiplatelet drugs in Brazilian cohorts, finding associations between CYP2C19*2, PON1 rs662 and ABCC3 rs757421 genotypes and platelet responsiveness or clopidogrel PK in subjects with coronary artery disease (CAD) or acute coronary syndrome (ACS), whereas ITGB3 contributes to aspirin PK but not platelet responsiveness in diabetic patients. Brazilian guidelines on anticoagulants and antiplatelets recommend the use of a platelet aggregation test or genotyping only in selected cases of ACS subjects without ST-segment elevation taking clopidogrel, and also suggest CYP2C9 and VKORC1 genotyping before starting warfarin therapy to assess the risk of bleeding episodes or warfarin resistance.

Untargeted metabolomics reveals alterations in metabolites of lipid metabolism and immune pathways in the serum of rats after long-term oral administration of Amalaki rasayana

Amalaki rasayana, a traditional preparation, is widely used by Ayurvedic physicians for the treatment of inflammatory conditions, cardiovascular diseases, and cancer. Metabolic alterations induced by Amalaki rasayana intervention are unknown. We investigated the modulations in serum metabolomic profiles in Wistar rats following long-term oral administration of Amalaki rasayana. Global metabolic profiling was performed of the serum of rats administered with either Amalaki rasayana (AR) or ghee + honey (GH) for 18 months and control animals which were left untreated. Amalaki rasayana components were confirmed from AR extract using HR-LCMS analysis. Significant reductions in prostaglandin J2, 11-dehydrothromboxane B2, and higher levels of reduced glutathione and glycitein metabolites were observed in the serum of AR administered rats compared to the control groups. Eleven different metabolites classified as phospholipids, glycerophospholipids, glucoside derivatives, organic acids, and glycosphingolipid were exclusively observed in the AR administered rats. Pathway analysis suggests that altered metabolites in AR administered rats are those associated with different biochemical pathways of arachidonic acid metabolism, fatty acid metabolism, leukotriene metabolism, G-protein mediated events, phospholipid metabolism, and the immune system. Targeted metabolomics confirmed the presence of gallic acid, ellagic acid, and arachidonic acid components in the AR extract. The known activities of these components can be correlated with the altered metabolic profile following long-term AR administration. AR also activates IGF1R-Akt-Foxo3 signaling axis in heart tissues of rats administered with AR. Our study identifies AR components that induce alterations in lipid metabolism and immune pathways in animals which consume AR for an extended period.

Platelet thromboxane (11-dehydro-Thromboxane B2) and aspirin response in patients with diabetes and coronary artery disease

Aspirin (ASA) irreversibly inhibits platelet cyclooxygenase-1 (COX-1) leading to decreased thromboxane-mediated platelet activation. The effect of ASA ingestion on thromboxane generation was evaluated in patients with diabetes (DM) and cardiovascular disease. Thromboxane inhibition was assessed by measuring the urinary excretion of 11-dehydro-thromboxane B₂ (11dhTxB₂), a stable metabolite of thromboxane A₂. The mean baseline urinary 11dhTxB₂ of DM was 69.6% higher than healthy controls (P = 0.024): female subjects (DM and controls) had 50.9% higher baseline 11dhTxB₂ than males (P = 0.0004), while age or disease duration had no influence. Daily ASA ingestion inhibited urinary 11dhTxB₂ in both DM (71.7%) and controls (75.1%, P < 0.0001). Using a pre-established cut-off of 1500 pg/mg of urinary 11dhTxB₂, there were twice as many ASA poor responders (ASA “resistant”) in DM than in controls (14.8% and 8.4%, respectively). The rate of ASA poor responders in two populations of acute coronary syndrome (ACS) patients was 28.6 and 28.7%, in spite of a significant (81.6%) inhibition of urinary 11dhTxB₂ (P < 0.0001). Both baseline 11dhTxB₂ levels and rate of poor ASA responders were significantly higher in DM and ACS compared to controls. Underlying systemic oxidative inflammation may maintain platelet function in atherosclerotic cardiovascular disease irrespective of COX-1 pathway inhibition and/or increase systemic generation of thromboxane from non-platelet sources.

Should diabetes still be considered a coronary artery disease equivalent?

Diabetes is well established as a cardiovascular risk factor and is currently regarded as a coronary artery disease equivalent. However, some recent data have contradicted the concept. We review the currently available data and usefulness or otherwise of this concept. While the concept of coronary artery disease equivalence has served to highlight the importance of diabetes as a risk factor, it has a number of problems. We propose that it would be more useful to consider diabetes as a myocardial infarction risk equivalent. This is not only more precise and in line with the literature but also conveys better the message that patients with diabetes and one or more previous myocardial infarction(s) are at even higher risk.

Aspirin insensitive thromboxane generation is associated with oxidative stress in type 2 diabetes mellitus

INTRODUCTION

Aspirin (ASA) irreversibly inhibits platelet cyclooxygenase-1 (COX-1) leading to decreased thromboxane-mediated platelet activation. The effect of ASA ingestion on platelet activation, thromboxane generation, oxidative stress and anti-oxidant biomarkers was studied in type 2 diabetes mellitus (DM).

MATERIAL AND METHODS

Baseline and post-ASA samples (100/325 mg x 7 days) were obtained from 75 DM patients and 86 healthy controls for urinary 11-dehydro-thromboxane B2 (11 dhTxB2), 8-iso-prostaglandin-F2α (8-isoPGF2α) and serum sP-Selectin, nitrite (NO(2)(-)), nitrate (NO(3)(-)) and paraoxonase 1 (PON1) activity.

RESULTS

Compared to baseline controls, baseline DM had higher mean levels of 11 dhTxB2 (3,665 ± 2,465 vs 2,450 ± 1,572 pg/mg creatinine, p=0.002), 8-isoPGF2α (1,457 ± 543 vs 1,009 ± 412 pg/mg creatinine, p<0.0001), NO(2)(-) (11.8 ± 7.3 vs 4.8 ± 5.3 μM, p<0.0001), NO(3)(-) (50.4 ± 39.3 vs 20.9 ± 16.7 μM, p<0.0001) and sP-Selectin (120.8 ± 56.7 vs 93.0 ± 26.1 ng/mL, p=0.02), and the same held for post-ASA levels (p<0.0001). ASA demonstrated no effect on 8-isoPGF2α, NO(2)(-), NO(3)(-), sP-Selectin or PON1 activity in either DM or controls. Post ASA inhibition of urinary 11 dhTxB2 was 71.5% in DM and 75.1% in controls. There were twice as many ASA poor responders in DM than in controls (14.8% and 8.4%) based on systemic thromboxane reduction. Urinary 8-isoPGF2α excretion was greater in DM ASA poor responders than good responders (p<0.009).

CONCLUSIONS

This suggests that oxidative stress may maintain platelet function irrespective of COX-1 pathway inhibition and/or increase systemic generation of thromboxane from non-platelet sources.