Feeding a Bioactive Oil Enriched in Stearidonic Acid during Early Life Influences Immune System Maturation in Neonatal Sprague-Dawley Rats

Abstract

Long-chain n-3 PUFAs (LCPUFAs) improve immune development and reduce atopic disease risk in infants. Stearidonic acid (SDA) can be a substrate for biosynthesis of n-3 LCPUFAs. We aimed to determine the effect of feeding an SDA-enriched diet during suckling and weaning on offspring immunity and ability to develop oral tolerance (OT). Pregnant Sprague-Dawley rats were randomly assigned to consume either SDA (3g SDA/100g fat) or a control (no SDA) diet, 5 d before parturition and through lactation (21 d). For the OT treatment, 10-d-old pups were fed ovalbumin (Ova; 200 μL of 8mg/mL) or placebo daily for 5 d. At 21 d, pups (both sexes) were weaned to their respective maternal diet until 6 wk of age or killed. Systemic immunization was induced using Ova (in 3-wk-old pups) or Ova+adjuvant (in 6-wk-old pups). The effect of suckling diet (in 3-wk-old pups) or weaning diet (in 6-wk-old pups) and OT treatment on immune function (main outcome) in spleen and blood was compared using 2-factor ANOVA. An SDA-enriched maternal diet, compared with the control diet, resulted in higher plasma phospholipid (PL) EPA (15 times higher), docosapentaenoic acid (DPA; 3 times higher), and DHA (1.3 times higher) content in 3-wk-old pups, accompanied by higher B-cell function [plasma ovalbumin-specific IgG1 (Ova-IgG1), 2 times higher] ( P<0.05). Compared with pups fed a control diet, the splenocytes from these pups had more (23%) helper T (Th) cells (CD3+CD4+) and activated (12%) Th cells (CD4+CD28+) (P<0.02) than controls. At 6 wk, the SDA group had 30% more CD4+CD25+splenocytes, and when stimulated ex vivo with LPS, produced less inflammatory IL-6 (50%) and TNF-α (30%) and more immunoregulatory IL-10 (45%) cytokines (P<0.05) than the control group. The Ova-exposed group had less (30%) plasma Ova-IgG1 than the placebo group. Splenocytes and plasma PLs from the 6-wk-old SDA group had more EPA (2x) and DPA (3.5x) (P<0.05), but not DHA, than the control group. Feeding SDA during lactation and weaning altered immune responses in directions believed to be beneficial.