Olive oil-based lipid emulsion's neutral effects on neutrophil functions and leukocyte-endothelial cell interactions

Background: Infection remains a drawback of parenteral nutrition (PN), probably related, among other factors, to immunosuppressive effects of its lipid component. Newer preparations may have lesser immunosuppressive impact. This study examines the effects of an olive oil-based lipid emulsion (long-chain triacylglycerols-monounsaturated fatty acids [LCT-MUFA]; ClinOleic) on various functions of human neutrophils in vitro and on rat leukocyte-endothelial cell interactions in vivo compared with LCT (Intralipid) and 50% LCT-50% medium-chain triacylglycerols (MCT; Lipofundin) mixture. Methods: Neutrophils isolated from healthy donors were incubated with concentrations (0.03-3 mmol/L) of lipid emulsions encompassing clinically relevant levels. In vivo leukocyte recruitment was studied with intravital microscopy within rat mesenteric microcirculation. Results: LCT-MUFA (3 mmol/L) did not alter the N-formyl-Met-LeuPhe (FMLP)-induced rise in [Ca2+](i), oxidative burst, chemotaxis, and elastase release, whereas LCT-MCT decreased [Ca2+](i) and chemotaxis and increased oxidative burst. FMLP-induced LTB, production was augmented by lipid emulsions. Serum-opsonized zymosan-induced phagocytosis was unaltered by lipid emulsions. Basal and FMLP-induced CD11b expression was unaffected by lipid emulsions. Lipopolysaccharide (LPS)-induced TNF-alpha, IL-1 beta and IL-8 mRNA, and protein expression was unaltered by LCT-MUFA, whereas LCT and LCT-MCT decreased IL-beta mRNA and protein. LCT-MUFA did not alter apoptosis, but LCT increased apoptosis in absence and presence of GM-CSF. LPS (1 mu g/mL)-induced increase in leukocyte rolling flux, adhesion, and emigration was inhibited by LCT and LCT-MCT but unaffected in LCT-MUFA-treated rats. Immunohistochemistry showed LPS-induced increase in P-selectin expression attenuated by LCT and LCT-MCT but not LCT-MUFA. Conclusions: LCT-MUFA showed lower in vitro and in vivo impact on neutrophil function compared with LCT and LCT-MCT.