Effects of structurally different lipid emulsions on human neutrophil migration

Abstract

Aim: To test the hypothesis that structurally different lipid emulsions have distinct immunomodulatory properties, we analysed neutrophil migration in the presence of various lipid emulsions. Method: Neutrophils of 8 volunteers were pre-incubated in medium or physiological 2.5 mM emulsions containing long-chain (LCT), medium-chain (MCT), mixed LCT/MCT, α -tocopherol-enriched LCT/MCT (LCT/MCT-E) or structured triglycerides (SL). Thereafter, the cells were put on top of 3 μm-pore-sized cell culture filters and incubated for one hour in the presence or absence of a chemo-attractant. Neutrophil migration was measured as the percentage of cells that had passed the filter in the presence (chemotaxis) or absence (random migration) of a chemotactic factor. Results: Compared to lipid-free incubation (19±1%) random neutrophil migration significantly decreased with LCT/MCT (11±2%), LCT/MCT-E (12±2) and MCT (5±2%), while LCT (18±3%) and SL (20±1%) had no effect. N-formyl-methionyl-leucyl-phenylalanine- (fMLP, 10−8M) or zymosan-activated-serum-induced (ZAS, 10%) filter passage under lipid-free conditions amounted to 61±14% and 70±13%, respectively. These values decreased with LCT/MCT to 11±9% and 15±7%; with LCT/MCT-E to 18±10% and 28±12%; with SL to 39±18% and 57±14%, and with MCT to 5±2% and 10±6%, (all P<0.01), while LCT had no effect. Compared to LCT/MCT, the α -tocopherol-enriched formulation significantly increased ZAS- and fMLP-induced chemotaxis. fMLP-induced chemotaxis decreased in direct proportion to LCT/MCT triglyceride concentration. Conclusions: Human neutrophil migration is distinctively inhibited by structurally different lipid emulsions, depending on triglyceride chain-length and concentration as well asα -tocopherol content.