Effects of omega-3 and omega-6 fatty acids on human placental cytokine production.

Introduction: Dietary supplementation with omega-3 long chain polyunsaturated fatty acids (n-3 PUFAs) may exert benefits in pregnancy through inhibition of placental inflammation. However, studies on the anti-inflammatory effects of n-3 PUFAs in the placenta are lacking. We compared the cytokine responses of human placental explants in vitro after 4 days pre-incubation with either: a) individual n-3 or n-6 PUFAs (20 μM), or b) physiologically relevant combinations of low, medium or high n-3 or n-6 PUFA concentrations.

Methods: Placental cytokine (IL-6 and TNF-α) mRNA expression and protein production were assessed at 4 h and 12 h, respectively. Cytokine and fatty acid concentrations were also measured in placentas delivered at term by women who ingested either low (n = 12) or high (n = 10) amounts of fish/fish oil in the month prior to delivery.

Results: Pre-exposure to n-3 PUFAs as individual fatty acids results in reduced placental IL-6 production (P < 0.05), whereas exposure to complex fatty acid mixtures enriched in n-3 PUFAs (high n-3:n-6 ratios) results in a significant stimulation of IL-6 production (P < 0.05). There were no differences in placental n-3 or n-6 PUFA levels between women with either high or low dietary fish oil intake and no differences in cytokine expression.

Discussion: In summary, data from our complex lipid explant model and an observational cohort study do not support a role for n3 PUFAs in the suppression of pro-inflammatory cytokine expression in the human placenta. Results from studies of placental tissues exposed to single n-3 and n-6 PUFAs should be interpreted with considerable caution.