Medium-chain, triglyceride-containing lipid emulsions increase human neutrophil beta2 integrin expression, adhesion, and degranulation.
BACKGROUND
To test the hypothesis that lipid emulsions with different triglyceride structures have distinct immunomodulatory properties, we analyzed human neutrophil adhesion and degranulation after lipid incubation.


METHODS
Neutrophils, isolated from the blood of 10 healthy volunteers, were incubated in medium or physiologic (2.5 mmol/L) emulsions containing long-chain (LCT), medium-chain (MCT), mixed LCT/MCT, or structured (SL) triglycerides. Expression of adhesion molecules and degranulation markers was evaluated by flow cytometry. Also, functional adhesion was investigated by means of a flow cytometric assay using fluorescent beads coated with the integrin ligand intercellular adhesion molecule (ICAM)-1.


RESULTS
Although LCT and SL had no effect, LCT/MCT significantly increased expression of the beta2 integrins lymphocyte-function-associated antigen 1 (+18%), macrophage antigen 1 (+387%), p150,95 (+82%), and (alphaDbeta2 (+230%). Degranulation marker expression for azurophilic (CD63, +210%) and specific granules (CD66b, +370%) also significantly increased, whereas L-selectin (CD62L, -70%) decreased. The effects of LCT/MCT were mimicked by the MCT emulsion. ICAM-1 adhesion (% beads bound) was increased by LCT/MCT (34% +/- 4%), whereas LCT (19% +/-3%) and SL (20% +/- 2%) had no effect compared with medium (17% +/- 3%).


CONCLUSIONS
LCT/MCT and MCT, contrary to LCT and SL emulsions, increased neutrophil beta2 integrin expression, adhesion, and degranulation. Apart from other emulsion constituents, triglyceride chain length might therefore be a key feature in the interaction of lipid emulsions and the phagocyte immune system.
Wanten
G J
GJ
Department of Gastroenterology, University Hospital, Nijmegen, The Netherlands. g.wanten@gastro.azn.nl
Geijtenbeek
T B
TB
Raymakers
R A
RA
van Kooyk
Y
Y
Roos
D
D
Jansen
J B
JB
Naber
A H
AH
D000328:Adult; D018821:CD18 Antigens / Q000378:metabolism; D002448:Cell Adhesion / Q000502:physiology; D015550:Cell Degranulation / Q000502:physiology; D005217:Fat Emulsions, Intravenous / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009504:Neutrophils / Q000187:drug effects / Q000502:physiology*; D014280:Triglycerides / Q000008:administration & dosage* / Q000494:pharmacology
D018821:CD18 Antigens; D005217:Fat Emulsions, Intravenous; D014280:Triglycerides; D018799:Intercellular Adhesion Molecule-1