Obese and insulin resistant JCR:LA‐cp rats fed eicosapentaenoic acid and docosahexaenoic acid have higher IL‐2 and lower TNF‐α production

Abstract

The effects of dietary eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on the aberrant immune function in obesity and insulin resistance have not been established. To determine the impact of EPA and DHA on splenocyte phospholipid (PL) fatty acid composition, phenotypes and cytokine production, 8 wk old male obese/insulin resistant JCR:LA‐cp (cp/cp) rats (n=8/group) were fed one of the following nutritionally complete, isoenergetic diets for 16 wk: control (Ctl, 0% EPA+DHA), low fish oil (LFO, 0.8%w/w EPA+DHA) or high FO (HFO, 1.4%w/w EPA+DHA). Splenocytes from HFO rats produced more IL‐2 (concanavalin A (ConA)) and less TNF‐α (lipopolysaccharide (LPS)) compared to Ctl cells (p<0.05). FO fed rats had a higher % of n‐3 PUFA and lower % of n‐6 PUFA and n‐6:n‐3 PUFA ratio in phosphatidylcholine and phosphatidylethanolamine splenocyte PL compared to Ctl (p<0.05). HFO fed rats had a lower % of CD3+CD8+, CD8+CD28+CD25+ and CD11b/c+OX6+CD80+ splenocytes after ConA stimulation (p<0.05). We hypothesize that the higher T cell proliferative response by cells from cp/cp rats fed the HFO diet is related to the higher % of n‐3 PUFA in PL. The lower TNF‐α production in the HFO group may be partly explained by the lower % of activated innate antigen presenting cells. Overall, the HFO diet, but not the LFO diet, improved T‐cell and inflammatory responses in the obese JCR:LA‐cp rat.