ABCB1 hypomethylation is associated with decreased antiplatelet effects of clopidogrel in Chinese ischemic stroke patients.

Current predictive models including the CYP2C19 polymorphism and clinical factors still explain only about 12% of variability of clopidogrel responsiveness. Up until recently, the precise mechanism of clopidogrel resistance remains unclear. P-glycoprotein (P-gp) encoded by ABCB1, a transmembrane calcium-dependent efflux pump for clopidogrel, implicated a role in clopidogrel resistance. In this present study, we investigated the methylation status of ABCB1 gene promoter in relation to ABCB1 mRNA expressions and the antiplatelet effects of clopidogrel. This study was a prospective cohort analysis of eligible stroke patients (n = 183, aged 18-75 years) who received clopidogrel (75 mg/day) for at least 5 days before discharge. A final subcohort of 87 patients with CYP2C19*1/*1 genotype were enrolled in the study population. Patients were grouped in quartiles of maximum platelet aggregation (MPA values (Q1, Q2, Q3 and Q4, MPA(Q1) < 14.1%, MPA(Q4) > 35.4%). The methylation status of the ABCB1 promoter was 1.8 times in the Q1 MPA group (10.1 ± 2.4%) than in the Q4 MPA group (5.5 ± 2.1%) (P < 0.001). ABCB1 methylation correlated inversely with MPA (R = - 0.764, P < 0.001) and mRNA expression (R = - 0.839, P < 0.001). Results of a multivariate linear regression model demonstrated that ABCB1 methylation was independently associated with MPA (ß(coef ficient) = - 4.71, P < 0.001). ABCB1 expression was 0.62 times in the Q1 MPA group (5.3 ± 1.4 per thousand) than in the Q4 MPA (8.5 ± 2.5%o), and the expression of ABCB1 correlated positively with ADP-induced MPA (R = 0.791, P < 0.001). ABCB1 promoter methylation status in whole blood appears to be inversely associated with ABCB1 mRNA expressions and MPA. In conclusions, hypomethylation of ABCB1 promoter is associated with a decreased response to clopidogrel in ischemic stroke patients via increased ABCB1 mRNA expression.

Bacterial Composition and Diversity in Breast Milk Samples from Mothers Living in Taiwan and Mainland China.

Human breast milk is widely recognized as the best source of nutrients for healthy growth and development of infants; it contains a diverse microbiota. Here, we characterized the diversity of the microbiota in the breast milk of East Asian women and assessed whether delivery mode influenced the microbiota in the milk of healthy breast-feeding mothers. We profiled the microbiota in breast milk samples collected from 133 healthy mothers in Taiwan and in six regions of mainland China (Central, East, North, Northeast, South, and Southwest China) by using 16S rRNA pyrosequencing. Lactation stage (months postpartum when the milk sample was collected) and maternal body mass index did not influence the breast milk microbiota. Bacterial composition at the family level differed significantly among samples from the seven geographical regions. The five most predominant bacterial families were Streptococcaceae (mean relative abundance: 24.4%), Pseudomonadaceae (14.0%), Staphylococcaceae (12.2%), Lactobacillaceae (6.2%), and Oxalobacteraceae (4.8%). The microbial profiles were classified into three clusters, driven by Staphylococcaceae (abundance in Cluster 1: 42.1%), Streptococcaceae (Cluster 2: 48.5%), or Pseudomonadaceae (Cluster 3: 26.5%). Microbial network analysis at the genus level revealed that the abundances of the Gram-positive Staphylococcus, Streptococcus, and Rothia were negatively correlated with those of the Gram-negative Acinetobacter, Bacteroides, Halomonas, Herbaspirillum, and Pseudomonas. Milk from mothers who had undergone Caesarian section (C-section group) had a significantly higher abundance of Lactobacillus (P < 0.05) and a higher number of unique unclassified operational taxonomic units (OTUs) (P < 0.001) than that from mothers who had undergone vaginal delivery (vaginal group). These findings revealed that (i) geographic differences in the microbial profiles were found in breast milk from mothers living in Taiwan and mainland China, (ii) the predominant bacterial families Streptococcaceae, Staphylococcaceae, and Pseudomonadaceae were key components for forming three respective clusters, and (iii) a significantly greater number of unique OTUs was found in the breast milk from mothers who had undergone C-section than from those who had delivered vaginally.