Influence of dietary n-3 fatty acids on macrophage glycerophospholipid molecular species and peptidoleukotriene synthesis.

Rs Chapkin,Cc Miller,Cc Akoh

doi:10.1016/s0022-2275(20)41983-2

Abstract

The study examined the ability of dietary n-3 fatty acids to modify mouse peritoneal macrophage glycerophospholipid molecular species and peptidoleukotriene synthesis. After a 2-week feeding period, fish versus corn oil feeding significantly (P less than 0.01) lowered n-6 polyunsaturated fatty acid (PUFA) mol % levels, i.e., arachidonic acid (20:4n-6) in diacylphosphatidylserine (PtdSer), diacylphosphatidylinositol (PtdIns), diacylglycerophosphoethanolamine (PtdEtn), alkenylacylglycerophosphoethanolamine (PlsEtn), and diacylglycerophosphocholine (PtdCho). A notable exception was alkylacylglycerophosphocholine (PakCho), where only moderate decreases in 16:0-20:4n-6 and 18:0-20:4n-6 species were observed after fish oil supplementation. The predominant n-3 PUFA in macrophage phospholipid subclasses was docosapentaenoic acid (22:5n-3). The major n-3 species were 18:0-22:5n-3 in PtdIns, PtdSer, glycerophosphoethanolamines (EtnGpl) and 16:0-22:5n-3 in PtdCho and PlsEtn. The major n-3-containing species in PakCho were 16:0-20:5n-3 and 18:1-22:6n-3. These findings indicate that n-3 PUFA are differentially incorporated into macrophage phospholipid subclasses after dietary fish oil supplementation, and suggest that phospholipid remodeling enzymes selectively discriminate between substrates based on compatibility of sn-1 covalent linkage and the composition of the sn-1 and sn-2 aliphatic chains. Macrophage peptidoleukotriene synthesis was also strongly influenced after fish oil feeding; the LTC5/LTC4 ratio was significantly higher (P less than 0.01) in fish oil-fed animals than in corn oil-fed animals, 0.85 versus 0.01, respectively. These ratios were subsequently compared to phospholipid molecular species 20:5n-3/20:4n-6 ratios in order to determine potential sources of eicosanoid precursors.

Highlights

% levels, i.e., arachidonic acid (20:4n-6) in diacylphosphatidylserine (PtdSer), diacylphosphatidylinositol (PtdIns), diacylglycerophosphoethanolamine (PtdEtn), alkenylacylglycerophosphoethanolamine (PlsEtn), and diacylglycerophosphocholine(PtdCho)
A mechanism by which fish oil constituents are believed to exert their effect is by altering membrane phospholipid polyunsaturated fatty acid (PUFA) composition, such that the profde and character of the biologically active products derived from these phospholipids are altered
The modified release of these products from fish oilenriched cells presumably leads to a diminished macrophage response as evidenced by studies showing that fish oil-derived PUFAs can, influence macrophage function [11, 12]

Summary

Introduction

% levels, i.e., arachidonic acid (20:4n-6) in diacylphosphatidylserine (PtdSer), diacylphosphatidylinositol (PtdIns), diacylglycerophosphoethanolamine (PtdEtn), alkenylacylglycerophosphoethanolamine (PlsEtn), and diacylglycerophosphocholine(PtdCho). The major n-3-containing species in PakCho were 16:0-20:5n-3 and 18:1-22:6n-3 These findings indicate that n-3 PUFA are differentially incorporated into macrophage phospholipid subclasses after dietary fish oil supplementation, and suggest that phospholipid remodeling enzymes selectively discriminate between substrates based on compatibilitiy of sn-l covalent linkage and the composition of the sn-1 and sn-2 aliphatic chains. Macrophage peptidoleukotriene synthesis was strongly influenced after fish oil feeding; the LTC5/LTC4 ratio was significantly higher (P < 0.01) in fish oil-fed animals than in com oil-fed animals, 0.85 versus 0.01, respectively. These ratios were subsequently compared to phospholipid molecular species 20:5n-3/ 20:4n-6 ratios in order to determine potential sources of eicosanoid precursors.-Chapkin, R. PUFAs of the n-3 family are primarily of marine origin while members of the n-6 family are primarily of terrene plant origin

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