Metabolome-wide association study identifies multiple biomarkers that discriminate north and south Chinese populations at differing risks of cardiovascular disease: INTERMAP study

Abstract

Rates of heart disease and stroke vary markedly between north and south China. A (1)H NMR spectroscopy-based metabolome-wide association approach was used to identify urinary metabolites that discriminate between southern and northern Chinese population samples, to investigate population biomarkers that might relate to the difference in cardiovascular disease risk. NMR spectra were acquired from two 24-h urine specimens per person for 523 northern and 244 southern Chinese participants in the INTERMAP Study of macro/micronutrients and blood pressure. Discriminating metabolites were identified using orthogonal partial least squares discriminant analysis and assessed for statistical significance with conservative family wise error rate < 0.01 to minimize false positive findings. Urinary metabolites significantly (P < 1.2 × 10(-16) to 2.9 × 10(-69)) higher in northern than southern Chinese populations included dimethylglycine, alanine, lactate, branched-chain amino acids (isoleucine, leucine, valine), N-acetyls of glycoprotein fragments (including uromodulin), N-acetyl neuraminic acid, pentanoic/heptanoic acid, and methylguanidine; metabolites significantly (P < 1.1 × 10(-12) to 2 × 10(-127)) higher in the south were gut microbial cometabolites (hippurate, 4-cresyl sulfate, phenylacetylglutamine, 2-hydroxyisobutyrate), succinate, creatine, scyllo-inositol, prolinebetaine, and trans-aconitate. These findings indicate the importance of environmental influences (e.g., diet), endogenous metabolism, and mammalian-gut microbial cometabolism, which may help explain north-south China differences in cardiovascular disease risk.

Figure 1

Median urinary ¹H NMR spectrum of INTERMAP Chinese population samples, based on the first urine collection (N=747). Key: 1, Pentanoic/heptanoic acid; 2, Branched-chain amino acids (leucine, isoleucine, valine); 3, D-3-hydroxybutyrate; 4, Lactate; 5, 2-hydroxyisobutyrate; 6, Alanine; 7, Acetate; 8, N-acetyls of glycoprotein fragments (including uromodulin); 9, N-acetyl neuraminic acid; 10, Phenylacetylglutamine; 11, 4-cresyl sulfate; 12, Succinate; 13, Glutamine; 14, Citrate; 15, Dimethylamine; 16, Methylguanidine; 17, Trimethylamine; 18, Dimethylglycine; 19, Creatine; 20, Creatinine; 21, Prolinebetaine; 22, Trimethylamine N-oxide; 23, Scyllo-inositol; 24, Glycine; 25, Guanidinoacetate; 26, Hippurate; 27, N-methyl nicotinic acid; 28, Trans-aconitate; 29, Tyrosine; 30, Formate.

Figure 2

(A) Cross-validated OPLS-DA scores plot derived from urinary NMR spectra of northern and southern Chinese population samples, based on the first urine collection; (B) Covariance plot showing color-coded significance of urinary metabolite differences between northern and southern Chinese populations, based on the first urine collection. Mean north-south differences in peak intensity for 7,100 spectral variables were assessed for statistical significance using Family Wise Error Rate <0.01, corresponding to P <4×10⁻⁶ for group mean north-south differences by Student's t, for the two urine collections considered separately; (C) Cross-validated OPLS-DA scores plot derived from urinary NMR spectra of northern and southern Chinese population samples, based on the second urine collection; (D) Covariance plot showing color-coded significance of urinary metabolite differences between northern and southern Chinese populations, based on the second urine collection. Key: 1, Pentanoic/heptanoic acid; 2, Branched-chain amino acids; 4, Lactate; 5, 2-hydroxyisobutyrate; 6, Alanine; 8, N-acetyls of glycoprotein fragments (including uromodulin); 9, N-acetyl neuraminic acid; 11, 4-cresyl sulfate; 12, Succinate; 16, Methylguanidine; 18, Dimethylglycine; 19, Creatine; 21, Prolinebetaine; 23, Scyllo-inositol; 10, Phenylacetylglutamine; 26, Hippurate; 28, Trans-aconitate.