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Long-chain predominant lipid emulsions inhibit in vitro macrophage tumor necrosis factor production
W D Vazquez1, G Arya, V F Garcia
1Children's Hospital Medical Center, Cincinnati.
Abstract:
Intravenous lipid emulsions are an important component of parenteral nutrition. Despite their benefits, lipid emulsions have been associated with higher rates of bacteremia in neonates. Therefore we investigated the effect of lipid emulsions on the inflammatory response by examining their effect on in vitro macrophage tumor necrosis factor (TNF) production of two distinct macrophage populations. Through the use of endotoxin-free phosphate buffered saline, peritoneal (PER) and alveolar (ALV) macrophages were isolated from male Sprague-Dawley rats (weighing 125 to 150 g) with endotoxin-free phosphate buffered saline. Cell counts were adjusted to 2 x 10(6) cells/mL in RPMI with 2% fetal calf serum. Three hundred microliters of the cells were incubated in a 24-well culture dish with media or media with intralipid (100 micrograms/dL) for 16 hours. After washing each well three times, the cells were stimulated for 2 or 16 hours with Escherichia coli lipopolysaccharide (150 microL of 1 microgram/mL). The supernatants were assayed for TNF using the WEHI 164:13 bioassay and TNF levels were expressed as picograms per milliliter. Student's unpaired t test was used for data analysis. Lipid-exposed PER and ALV macrophages in vitro TNF levels were significantly lower-after 2 hours (12,591 pg/mL +/- 3837 vs 20,591 pg/mL +/- 6344 for PER, 3894 pg/mL +/- 1258 vs 13,177 pg/mL +/- 3266 for ALV) and 16 hours (6427 pg/mL +/- 3050 vs 12,353 pg/mL +/- 4877 for PER; 131,6000 pg/mL +/- 7317 vs 354,680 pg/mL +/- 31,605 for ALV) of endotoxin stimulation. TNF production seems to be impaired in macrophages exposed to a .1% lipid emulsion for 16 hours.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Intravenous lipid emulsions may suppress macrophage inflammatory responses. This study found that lipid exposure reduced tumor necrosis factor (TNF) production in rat macrophages, potentially impacting neonatal immune defense.
Area of Science:
- Immunology
- Cell Biology
Background:
- Intravenous lipid emulsions are crucial for parenteral nutrition.
- Lipid emulsions are linked to increased bacteremia risk in neonates.
Purpose of the Study:
- To investigate the impact of lipid emulsions on macrophage inflammatory response.
- To examine the effect of lipid emulsions on in vitro tumor necrosis factor (TNF) production by peritoneal (PER) and alveolar (ALV) macrophages.
Main Methods:
- Isolated rat PER and ALV macrophages.
- Incubated macrophages with or without intralipid (100 µg/dL) for 16 hours.
- Stimulated macrophages with lipopolysaccharide and measured TNF levels via WEHI 164:13 bioassay.
Main Results:
- Lipid-exposed PER and ALV macrophages showed significantly lower TNF levels after 2 and 16 hours of endotoxin stimulation.
- TNF production was notably impaired in macrophages exposed to a 0.1% lipid emulsion for 16 hours.
Conclusions:
- Lipid emulsion exposure appears to impair macrophage TNF production in vitro.
- This finding may offer insights into the increased bacteremia risk associated with lipid emulsions in neonates.