Metabolomics assessment of vitamin D impact in Pam₃CSK₄ stimulation

Bacteria are amongst the leading causes of mortality worldwide. Although several studies have proposed the possible therapeutic role of vitamin D in bacterial infection, the exact mechanism through which vitamin D functions in antibacterial immunity remains elusive. The metabolic reconfigurations induced by vitamin D in bacterial infection can therefore be explored through metabolomics, a multidisciplinary 'omics' science that evaluates the metabolic changes of a biological system by identifying and quantifying metabolites under specific conditions. In the present study, cultured U937 macrophages were treated with Pam₃CSK₄/mL, 1,25(OH)₂D₃ and a combination of Pam₃CSK₄/mL and 1,25(OH)₂D₃. These treatment/stimulated U937 cells were compared to untreated cells in order to measure the metabolic effect of vitamin D (1,25(OH)₂D₃). Intracellular metabolomics was performed using nuclear magnetic resonance. The obtained data were subjected to chemometric modelling and statistical analyses, which revealed a clear distinction between the metabolic profiles of Pam₃CSK₄ stimulated cells, 1.25(OH)₂D₃ supplemented cells and cells supplemented with a combination of Pam₃CSK₄/1.25(OH)₂D₃ as compared to the untreated cells. Significant differences (p < 0.05) were identified in 32 metabolites linked to bioenergy production, redox reaction regulation, inflammation and protein synthesis. The generated results illustrate that 1.25(OH)₂D₃ reprogrammes the metabolic profile of U937 cells stimulated with Pam₃CSK₄.