Anti-TBXA2R (N-terminal) polyclonal antibody

Patients with high on-treatment platelet reactivity (HPR) against aspirin or clopidogrel are at increased risk for adverse cardiovascular events. In this study, we explored the predictive value of common SNPs for the on-treatment platelet reactivity (OPR) against aspirin and clopidogrel assessed by VerifyNow assays. This study recruited 286 Han Chinese individuals undergoing antiplatelet treatment, including 159 cases with aspirin only (100 mg/day) and 127 cases with dual therapy (aspirin 100 mg/day plus clopidogrel 75 mg/day) for at least 2 weeks. The OPR against aspirin and clopidogrel were assessed by VerifyNow Aspirin (ARU) and P2Y12 assays (PRU), respectively. Genotyping for the selected 25 SNPs within 11 genes and 2 GWAS loci was carried out by ABI multiplex SNaPshot method. The results indicated that rs4244285 (CYP2C19) and rs342293 (7q22.3) were significantly associated with PRU value (both P < 0.01). As for the OPR to aspirin, a weak statistical significance was observed in rs5445 (GNB3) (P = 0.049) and rs5758 (TBXA2R) (P = 0.045). After adjusting for the covariates including gender, age and smoking, carriers of allele A of rs4244285 remained as a strong predictor for HPR against clopidogrel. The current study suggests that common SNPs may predict OPR against clopidogrel as assessed by VerifyNow P2Y12, but are less likely to respond against aspirin as assessed by VerifyNow Aspirin.

Background The thromboxane A2 receptor (TBXA2R) gene is associated with asthma, but no functional genetic variations are known to associate with the disease or its related phenotypes. Objective To investigate the association of TBXA2R polymorphisms with asthma susceptibility and related phenotypes and to identify functionally relevant polymorphisms. Methods We performed comprehensive sequencing of the TBXA2R gene in 48 Japanese control subjects and found a set of variants (SNP1G>T rs2238634, SNP2 T>G rs2238633, SNP3 C>T rs2238632 and SNP4G>A rs2238631) in intron 1 in linkage disequilibrium with c.795 T>C rs1131882, which was previously reported to be associated with asthma and related phenotypes. To investigate the effect of four common haplotypes (H1, H2, H3 and H4) on transcriptional activity, we performed a luciferase assay in primary bronchial smooth muscle cells (BSMCs) and human airway epithelial cells (BEAS-2B). We also studied the haplotype association with lung function, TBXA2R mRNA levels, and eosinophil fraction/count in peripheral blood in childhood-onset asthma patients and/or controls. Results H2 and H4, containing minor alleles of SNP2 and SNP3, had significantly higher transcriptional activities than H1 consisting of major alleles (P < 0.001 in BSMCs and BEAS-2B). Homozygotes for redefined haplotype h2 corresponding to minor alleles of SNP2 and SNP3 were associated with lower lung function in childhood-onset asthma patients compared to other zygotes (baseline Forced expiratory volume in one second (FEV1)/ Forced vital capacity (FVC) and Forced expiratory flow between 25% and 75% of the FVC (%FEF2575%): P=0.00201 and 0.0128, respectively, and post-bronchodilator FEV1/FVC and %FEF2575%: P=0.00224 and 0.0393 respectively). Haplotype h2 was also associated with higher mRNA levels in control peripheral blood cells and higher blood eosinophil fractions and counts in female controls. Conclusions and Clinical Relevance Genetic variants were identified in the TBXA2R gene that influenced transcriptional activity and were associated with asthma-related phenotypes. Thromboxane pathways may therefore play important roles in airway inflammation and remodelling in asthma patients.