Immune modulation by polyunsaturated fatty acids

Objectives and Study: In recent decades there has been a dramatic increase in the prevalence of atopic disease, which is characterized by a bias in favour of a Th2-cytokine profile. Since sensitization may occur at an early age, early exposure to factors that favor this bias might predispose individuals to develop atopic responses. The increase in atopic disease coincides with changes in the intake of polyunsaturated fatty acids (PUFAs), which makes these compounds very interesting candidates for dietary intervention studies. Polyunsaturated fatty acids (PUFAs) are precursor-molecules for eicosanoids such as leukotriens, prostaglandins andresolvins. Furthermore, PUFAs can alter immune cell function via various mechanisms, including modulation of receptor functions and activation of transcription factors. Methods: The effects of different dietary fatty acids (FA) (saturated and \omega-3/\omega-6 poly-unsaturated) were investigated in two mouse models: (1) the vaccination model, in which the Delayed Type Hypersensitivity (DTH) response and other immune parameters were studied in C57BL/6 mice, and (2) the ovalbumine (OVA)-induced model for experimental allergic asthma in BALB/c mice. 3 wk-old mice were put on different diets two weeks before vaccination (model 1) or sensitization (model 2) until the end of the experiment. Results: In model 1, the DTH-response was most profound in mice fed the diet with the highest\omega-3 PUFA content. In model 2, mice fed this diet had a less severe acute allergic skin response (ASR). In addition, the most severe ASR was observed in mice fed a saturated FA diet. Conclusion: Results obtained from model 1 indicate that a high \omega-3 PUFA diet contributes to a increased Th1-response to vaccination. Additionally, results from model 2 suggest that this diet lessens the Th2-response. Furthermore, results obtained from the latter model indicate a diet with high levels of saturated FA may contribute to an increased severity of allergic symptoms.