Maternal fish oil supplementation in pregnancy modifies neonatal leukotriene production by cord-blood-derived neutrophils

Fish oil supplementation has been shown to reduce neutrophil production of inflammatory LTB₄ (leukotriene B₄) in adults. The present study is the first to examine the effects on neonatal neutrophil function following supplementation in pregnancy. Pregnant women with allergic disease (n=98) were randomized to receive either fish oil [3.7 g of n−3 long-chain PUFAs (polyunsaturated fatty acids)/day] or a placebo supplement for the final 20 weeks of pregnancy. Leukotriene production by neonatal neutrophils was measured after stimulation with the calcium ionophore A23187. This was examined in relation to supplementation, cell membrane fatty acid levels and mononuclear cytokine production. Neutrophil LTB₄ production was significantly reduced in neonates whose mothers had received fish oil in pregnancy. This was most evident for isomer 2 of LTB₄ (P=0.031), although this was also observed for total LTB₄ (P=0.051) and isomer 1 (P=0.088). There was also a trend for lower production of other PUFA metabolites, namely 5-HETE (5-hydroxyeicosatetraenoic acid; P=0.054) in the fish oil group. Accordingly, LTB₄ levels were inversely related to membrane n−3 PUFA levels. Less inflammatory products (LTB₅) were only produced at very low levels, although there was a trend for higher levels of this metabolite in the fish oil group. Consistent with this, LTB₅ levels were positively correlated with n−3 PUFA membrane levels, particularly EPA (eicosapentanoic acid) and negatively correlated with n−6 PUFAs. Neonates with lower neutrophil LTB₄ production also had lower production of pro-inflammatory IL (interleukin)-6 responses (r=0.35, P=0.005) and regulatory IL-10 responses (r=0.37, P=0.003) by LPS (lipopolysaccharide)-stimulated neonatal mononuclear cells. In conclusion, maternal dietary changes can modify neonatal neutrophil function. This has implications for the early immune programming, which can be influenced by the inflammatory milieu of local tissues during initial antigen encounter. It also provides evidence of another pathway through which long-chain PUFAs status can influence early immune development.