Lipid effects on neutrophil calcium signaling induced by opsonized particles: platelet activating factor is only part of the story.
METHODS
Total parenteral nutrition is frequently used in clinical practice to improve the nutritional status of patients. However, the risk for infectious complications remains a drawback in which immune-modulating effects of the lipid component may play a role. To characterize these lipid effects we investigated neutrophil activation by opsonized yeast particles under influence of lipid emulsions derived from fish oil (VLCT), olive oil (LCT-MUFA), soybean oil (LCT), and a physical mixture of coconut and soybean oil (LCT-MCT).


RESULTS
Serum-treated zymosan (STZ) evoked a biphasic increase in cytosolic Ca2+ concentration ([Ca2+]c) with an initial slow rise that turned into a second fast rise until a plateau was reached. LCT-MCT (5 mM) pretreatment markedly increased the rate of [Ca2+]c rise during the initial phase, abolished the second phase and lowered the plateau. These effects of LCT-MCT were mimicked by the protein kinase C (PKC) activating phorbol ester PMA. LCT, LCT-MUFA and VLCT, on the other hand, decreased the rate of [Ca2+]c rise during both phases and lowered the plateau. The platelet-activating factor (PAF) receptor antagonist WEB 2086 inhibited the second phase, demonstrating that PAF acts as an intercellular messenger in STZ-induced Ca2+ mobilization, but did not interfere with the stimulatory effect of LCT-MCT or PMA on the initial rate of [Ca2+]c rise.


CONCLUSIONS
Structurally different lipids act only in part through PAF to distinctively modulate neutrophil calcium signaling in response to activation by opsonized particles.
Department of Gastroenterology and Hepatology, University Medical Centre, Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands. g.wanten@mdl.umcn.nl
Geert
G
Wanten
Anneke
A
Kusters
Sjenet E
SE
van Emst-de Vries
Anton
A
Tool
Dirk
D
Roos
Ton
T
Naber
Peter
P
Willems
D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects*; D004655:Emulsions; D005217:Fat Emulsions, Intravenous / Q000737:chemistry / Q000494:pharmacology*; D005395:Fish Oils; D006801:Humans; D018375:Neutrophil Activation; D009504:Neutrophils / Q000378:metabolism*; D000069463:Olive Oil; D010938:Plant Oils; D010972:Platelet Activating Factor / Q000378:metabolism*; D010980:Platelet Membrane Glycoproteins / Q000037:antagonists & inhibitors; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors; D013024:Soybean Oil; D015054:Zymosan / Q000494:pharmacology
D004655:Emulsions; D005217:Fat Emulsions, Intravenous; D005395:Fish Oils; D000069463:Olive Oil; D010938:Plant Oils; D010972:Platelet Activating Factor; D010980:Platelet Membrane Glycoproteins; D043562:Receptors, G-Protein-Coupled; C039351:platelet activating factor receptor; D013024:Soybean Oil; D015054:Zymosan; D002118:Calcium