Supplementing Docosahexaenoic Acid and Arachidonic Acid During Suckling Period Is Beneficial for Developing Tolerance to Egg Protein in Allergy Prone Brown Norway Rats

Abstract

ObjectivesWe aimed to study the effect of supplementing arachidonic acid (ARA) and docosahexaenoic acid (DHA) during suckling (through Suckling Diet, SD) and weaning (through weaning diet, WD) on oral tolerance (OT) development in allergy susceptible Brown Norway rats. MethodsDams were assigned to consume either ARA+DHA (0.4% ARA, 0.8% DHA w/w total fat) SD or control SD (0% ARA, DHA) for 21d during the pups’ suckling period. At 21d, pups from each SD group were randomized to receive ARA + DHA WD (0.5% ARA, 0.5% DHA w/w total fat) or control WD (0% ARA, DHA) until 8wk. Between 21–25 d, pups from each of the 4 diet groups were randomized to receive ovalbumin (Ova, 3 mg) or a placebo (8% sucrose) for OT induction. At 7 wk, pups received an Ova + alum injection IP to induce systemic immunization. In necropsy, plasma was collected and splenocytes were isolated to determine immune cell types and ex-vivo cytokine production to phorbol myristate acetate + ionomycin (PMAi). ResultsAlthough higher DHA levels in dams’ breastmilk were seen with ARA+DHA SD, this SD effect was not seen in the 8wk pups. At 8wks, ARA+DHA WD resulted in significantly higher DHA level in (1.5x) plasma phospholipids (PL) and (2x) splenocytes. ARA composition in pups’ plasma and splenocytes PL was not different among SD and WD groups. OT development was confirmed by a significantly lower plasma level of Ova-IgG1 and Ova-IgE in Ova OT groups. Further, SD ARA+DHA supplementation also had 30% lower plasma Ova-IgG1 than control SD (P = 0.02) but the SD had no effect on production of IL2, IL4, IL10, IFNg, TNFα and IL13 by PMAi stimulated splenocytes. However, pups from Ova group that received ARA+DHA SD and control WD produced more TGFβ than control for SD and WD (P = 0.05). Pups from sucrose OT groups, when supplemented with ARA+DHA SD had 50% higher T regulatory cells (CD3+CD4+CD25+FoxP3+, Tregs) than controls SD in spleen. In pups that received control SD groups, the Ova group had lower activated T helper (CD3+CD4+CD28+) than sucrose, however, when pups received ARA+DHA SD, OT effect was absent. ConclusionsARA and DHA in WD increased DHA status without affecting ARA status in plasma. ARA and DHA provided in SD was beneficial for OT development shown by lowered ova-IgG1, which may be due to higher Tregs and TGFβ produced by splenocytes in brown Norway offspring. Funding SourcesNSERC, AGES-ALES (Patel).