Arachidonic acid (AA) present in lung and liver immune cell phospholipids is the precursor of eicosanoids that promote neutrophil margination, leading to tissue injury and inflammation. Administration of novel enteral formulations low in linoleic acid (LA) and containing eicosapentaenoic acid (EPA) from fish oil and gamma-linolenic acid (GLA) from borage oil displaces AA and promotes cell formation of eicosanoids with reduced inflammatory potential. The present study was undertaken to determine whether or not short-term provision of enteral diets containing GLA, EPA, or both in a cyclic fashion modulated the fatty acid composition of rat alveolar macrophage (AM) and liver Kupffer and endothelial (K&E) cell phospholipids in vivo to the extent achieved during continuous feeding.

METHODS

Rats were isocalorically fed through a gastrostomy catheter for 3 or 6 days with high-fat, low-carbohydrate diets that were enriched with either LA (diet A), EPA (diet B), or EPA + GLA (diet C). The rats were randomized by infusion modality, ie, continuous vs cyclic (14 hours feeding with 10 hours fasting daily) feeding. AM and K&E were isolated and phospholipid fatty acid profiles were determined by gas chromatography.

RESULTS

The dietary effects on AM and K&E cell phospholipid fatty acids for a given feeding period were not significantly influenced by the infusion modality. AM and K&E cells from rats receiving either diet B or diet C for 3 days had significantly lower AA and LA and higher EPA and dihomo-GLA (DHGLA), respectively, than rats given diet A regardless of the infusion modality. The mole % of EPA and DHGLA in K&E cells were higher after 6 vs 3 days of cyclic feeding with diet C. Using the eicosanoid precursor ratio (EPA + DHGLA/AA), the potential for generation of AA-derived eicosanoids was lower in rats given die B or C vs diet A regardless of infusion modality.

CONCLUSIONS

Given the rapid changes in lung and liver immune cell phospholipid fatty acids, short-term provision of EPA and GLA-enriched diets cyclically or continuously may prove clinically relevant for modulating the fatty acid composition and potential eicosanoid formation by these cells.