Background: Proinflammatory cytokines may contribute to clinical complications in heart transplant (HTx) recipients. Previous studies have shown immunomodulating effects of omega-3 fatty acids, but the results are somewhat conflicting. In this study, we examined plasma levels of tumor necrosis factor alpha (TNF-alpha), interleukin (IL) 10, and their relations to antioxidant vitamins in 45 HTx recipients before and after treatment with omega-3 fatty acids or placebo.
Methods: The patients were long-time survivors of heart transplantation, randomized in a double-blind fashion to receive omega-3 fatty acids (3.4 g/day) or placebo for 1 year. Plasma levels of cytokines were measured by enzyme immunoassays and vitamin A, vitamin E, and beta-carotene by high-performance liquid chromatography.
Results: In the omega-3, but not in the placebo group, there was a rise in the proinflammatory cytokine TNF-alpha (P<0.05), a decrease in the anti-inflammatory cytokine IL-10 (P=0.07), and a rise in TNF/IL-10 ratio (P<0.05) after 12 months, suggesting a proinflammatory net effect. In the omega-3 group, the increase in TNF-alpha was associated with an increase in eicosapentaenoic acid in plasma (r=0.58, P<0.02). During omega-3 fatty-acid treatment, but not during placebo, there was a decrease in vitamin E (P<0.05) and beta-carotene (P<0.05) levels, and the decrease in vitamin E was inversely correlated with the increase in TNF-alpha (r= -0.56, P<0.01). The rise in TNF-alpha levels during omega-3 fatty acids treatment was most pronounced in those patients with transplant coronary artery disease (P<0.04).
Conclusion: Our data suggest that omega-3 fatty acids in HTx recipients may change the balance between proinflammatory and anti-inflammatory cytokines in an inflammatory direction, possibly related to prooxidative effects of these fatty acids.