Lipidomic profiling of plasma in a healthy Singaporean population to identify ethnic specific differences in lipid levels and associations with disease risk factors.

Background: Plasma lipids (i.e., cholesterol, low density lipoprotein (LDL-C), high density lipoprotein (HDL-C) and triglycerides) are linked to a range of metabolic diseases, including heart disease and diabetes. Plasma have similarly been associated with the same diseases. However, neither abundance profiling of plasma in healthy populations, nor differences between ethnic groups has not been reported.

Methods: In this study, we have profiled over 280 using liquid chromatography-tandem mass spectrometry, independently across two sites, in 359 healthy Singaporean individuals of Chinese (n = 122), Indian (n = 120) and Malay (n = 117) ethnicity.

Results: We found variations in abundance (defined as % coefficient of variation) of plasma that fluctuated between 13 and 120%. Analysis of covariance (ANCOVA) identified differences between ethnic groups, particularly among alkyl and alkenylphosphatidylethanolamine species, as well as in two species of sphingosine-1-phosphate (i.e., d18:0 and d18:1), which were elevated in the Chinese group. Regression analysis identified ethnic-specific differences in the association of plasma lipids and with age, gender and body mass index (BMI). Chinese and Malay groups showed a positive association of glycerolipids (i.e., diglycerides (DG), triglycerides (TG)) and cholesteryl esters (CE) with BMI, but this was not seen in the Indian group. Furthermore, Indian and Malay groups showed a positive association between the abundance of sphingolipids and age, which was absent in the Chinese group.

Conclusions: This study provides baseline characterisation of the natural biological variation of plasma in three healthy ethnic groups, and identifies important differences in plasma lipid levels and their association with known disease risk factors.