IDENTIFYING A METABOLOMICS PROFILE ASSOCIATED WITH MASKED HYPERTENSION IN TWO INDEPENDENT COHORTS: DATA FROM THE AFRICAN-PREDICT AND SABPA STUDIES

Objective: Individuals with masked hypertension (MHT) have a greater risk of adverse cardiovascular outcomes compared to normotensives (NT). Exploring metabolomic differences between NT and MHT individuals may help provide a better understanding of the aetiology of MHT. Design and method: We analysed the data of N = 910 young apparently healthy participants (83% NT and 17% MHT) (mean age 24 ± 3 years) from the African-PREDICT and N = 210 older participants (63% NT and 37% MHT) from the SABPA (mean age 42 ± 9.6 years) studies. Clinic and ambulatory blood pressures (BPs) were used to define BP phenotypes. Urinary amino acids and acylcarnitines were measured using liquid chromatography time-of-flight mass spectrometry in the SABPA and liquid chromatography tandem mass spectrometry in the African-PREDICT studies. Results: Clinic and 24hr BPs were higher in MHT compared to NT adults (all p < 0.001). In the SABPA study, amino acids (leucine/isoleucine, valine, methionine and phenylalanine) and acylcarnitines (C0-, C3-, C4- and total acylcarnitines) were more abundant in MHT than NT adults. In the African-PREDICT study, only C0- and C5-carnitines were higher in MHT. When adjusting for waist circumference, all differences between NT and MHT individuals became non-significant for both studies (all q> 0.05). With unadjusted analyses in NT adults from the SABPA study, 24hr SBP correlated positively with only C3-carnitine. Conversely in MHT, positive correlations of 24hr SBP with leucine/isoleucine, valine, methionine, phenylalanine, C0- and C3-carnitine were evident (all p < 0.05). In the African-PREDICT study, 24hr SBP correlated positively with C0- (r = 0.101; p = 0.006) and C5-carnitine (r = 0.195; p < 0.001) in NT adults, and C5-carrnitine in MHT (r = 0.169; p = 0.034). Conclusions: Using two independent cohorts, we demonstrated significant differences between the metabolomic profiles of NT and MHT adults, which may reflect different stages in the alteration of branched-chain amino acid (BCAA) metabolism early on and later in life. These changes in BCAA metabolism are also likely modulated by central adiposity.