Blood L-cystine levels positively related to increased risk of hypertension.

Hypertension is one component of metabolic syndrome (MetS). Here, the study evaluated hypertension-associated metabolites in relation to other MetS components. Fasting plasma samples were collected from 22 hypertensive and 63 normotensive subjects for non-targeted metabolomics. Compared with normotensive subjects, hypertensive patients were more diabetic (6.3% vs. 36.4%) and had dyslipidemia (27.0% vs. 63.6%) (both p < .05). By non-targeted metabolomics, 758 metabolites in 22 classes were identified and 56 were differentially regulated between hypertensive and normotensive groups. Amongst these 56 metabolites, receiver operating characteristic analysis showed that 14 had an area under the curve above 0.6. Multivariate-adjusted logistic regression analysis demonstrated that per one-fold increase of L-glutmatic acid, L-cystine, (9S,10E,12Z,15Z)-9-Hydroxy-10,12,15-octadecatrienoic acid, deoxyribose 5-phosphate, and falcarinolone, the odds ratios were 3.64, 4.61, 0.26, 0.26, and 0.37 for having the risk of hypertension, respectively. Of five metabolites, by Spearman's correlation analysis, only L-glutmatic acid and L-cystine levels were positively associated with systolic and diastolic blood pressure (all p < .05). Spearman's correlation analysis further revealed that L-glutmatic acid levels were positively correlated with to body mass index (BMI), fasting blood glucose, and serum triglyceride but negatively associated with HDL-c (all p < .05) whereas L-cystine levels were not related to any of these components (p ≥ .13). Multivariate-adjusted linear regression analysis confirmed the positive correlation between L-cystine levels and systolic or diastolic blood pressure (β = 2.66 for SBP; β = 2.50 for DBP; both p < .05). In conclusion, L-cystine could be a potent metabolite for increased risk of hypertension.