Background and aims: Studies have suggested that 100% long-chain triacylglycerols (LCTs) lipid emulsions exhibit immunosuppressive effects, sometimes suspected to favor infectious complications in patients receiving parenteral nutrition. Newer emulsions, in particular olive oil-based emulsions, seem to have lesser immunosuppressive effects. We studied the in vitro effect of 100% LCTs (Intralipide), 50% LCTs-50% medium chain triacylglycerols (Medialipide), and 80% olive oil-based lipid emulsions (ClinOleic) on inflammatory cytokines production by peripheral blood mononuclear cells (PBMCs).
Methods: PBMCs separated by gradient centrifugation, or whole blood, were incubated with 0.001%, 0.01%, 0.1% and 1% of the three tested lipid emulsions during 24h in the presence or absence of activation by lipopolysaccharide and phytohemagglutinin. Then, supernatants were collected and cytokines measured (ELISA).
Results: The three lipid emulsions reduced basal TNF-alpha and IL-1beta production in PBMCs and whole blood cultures. However, ClinOleic was significantly less powerful in TNF-alpha and IL-1beta inhibition by isolated PBMCs than Intralipide and Medialipide. Basal TNF-alpha production was equally inhibited by the three emulsions in whole blood, but IL-1beta production was not significantly modified by ClinOleic. Interleukin-6 and -8 were not affected. After cell activation, lipid emulsions exhibit no effect on cytokines production.
Conclusion: ClinOleic induces a significantly lower in vitro inhibition of TNF-alpha and IL-1beta production by PBMCs than 100% LCTs or 50% LCTs-50% MCTs emulsions, and therefore might be more immune neutral. These effects vary from one subject to another, and disappeared after cell activation. Therefore, caution must be taken before extrapolation in vivo. Provided information should be taken into account for future design of clinical trials studying the immune modulating properties of lipid emulsions.