Intralipid is a fat emulsion that is regularly infused into humans and animals. Despite its routine use, Intralipid infusion can cause serious adverse reactions including immunosuppression. Intralipid is a complex mix of proteins, lipids and other small molecules and the effect of its infusion on the human plasma metabolome is unknown. We hypothesized that untargeted metabolomics of human plasma after an Intralipid infusion would reveal novel insights into its effects. We infused Intralipid and saline into ten healthy men in a double-blind, placebo-controlled experiment and used GC/MS, LC/MS and NMR to profile the small molecule composition of their plasma, before and after infusion. Multivariate statistical analysis of the 40 resulting plasma samples revealed that, after Intralipid infusion, a less-well characterized pathway of linoleic acid metabolism had resulted in the appearance of (9Z)-12,13-dihydroxyoctadec-9-enoic acid (12,13-DHOME, p < 10-3), a leukotoxin that has powerful physiological effects and is known to inhibit the neutrophil respiratory burst. Conclusions: Intralipid infusion caused increased plasma 12,13-DHOME. Given that 12,13-DHOME is known to directly affect neutrophil function we conclude that untargeted metabolomics may have revealed a hitherto unknown mechanism of Intralipid-induced immunosuppression.
The article is published online in the Journal of Lipid Research and is free to access.