(n-3) Polyunsaturated Fatty Acids Modulate the Expression of Functionally Associated Molecules on Human Monocytes in Vitro

Abstract

Diets rich in (n-3) polyunsaturated fatty acids (PUFA) are associated with suppression of the immune system, but the mechanisms are unclear. Specific immune responses are initiated by antigen-presenting cells. This study examines the in vitro effect of the (n-3) PUFA eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on the expression of cell surface molecules required for normal antigen-presenting cell function on human blood monocytes. Monocytes were incubated with or without EPA or DHA for 48 h at 37 degrees C. Following incubation, expression of major histocompatibility complex (MHC) class II molecules (HLA-DR, -DP and -DQ) and adhesion molecules [intercellular adhesion molecule-1 (ICAM-1) and leucocyte function associated antigen-1] was quantified by flow cytometry. In the presence of EPA alone there was a significantly lower median intensity of expression of HLA-DR and ICAM-1 relative to incubations without EPA. In contrast, significantly greater median intensities of expression of HLA-DR and -DP were observed following incubation with DHA. In parallel experiments, where monocytes were simultaneously activated by the addition of interferon-gamma to the cultures, median expression intensities of HLA-DR, -DP and ICAM-1 were significantly lower in the presence of either EPA or DHA compared with incubations without the (n-3) PUFA. These findings support previous animal studies that suggest that (n-3) PUFA can influence immune reactivity by modulating antigen-presenting cell function.

N-3 polyunsaturated fatty acids modulate the expression of functionally associated molecules on human monocytes and inhibit antigen presentation in vitro

“…Since it has been reported that synovial fluid monocytes obtained from patients with RA express elevated levels of MHC class II molecules [9], we also examined the effect of n-3 PUFA on activated monocytes, cultured in the presence of interferon-gamma (IFN-g), to up-regulate the expression of MHC class II molecules on the monocytes. Both EPA and DHA significantly inhibited the expression of HLA-DR, -DP and ICAM-1 on the activated monocytes [8]. We have also shown that dietary fish oil supplementation (containing a mixture of EPA and DHA) can inhibit the expression of these molecules on human peripheral blood monocytes [10].…”

“…In a previous study we observed that EPA and DHA can inhibit the expression of the adhesion molecule ICAM-1 on both resting and IFN-g-activated monocytes [8]. In contrast, these n-3 fatty acids exhibited opposing effects on the expression of the MHC class II molecules, HLA-DR and HLA-DP; EPA inhibited their expression whilst DHA enhanced.…”

“…The intensity of expression of the cell surface markers on monocytes was determined using a previously reported method [8]. The anti-log of the green (530 nm) fluorescence emission was used to calculate the linear median intensity value for the monocytes stained with MoAb and for the controls without MoAb.…”

Lipid metabolism and the risk factors of cardiovascular disease: implication of dietary omega-3 polyunsaturated fatty acids

“…Studies have reported the ability of n-3 PUFA to reduce the expression of adhesion molecules on macrophages (Hughes et al, 1996) and endothelial cells (Weber et al, 1995), thereby preventing the atherosclerotic plaque progression. N-3 PUFA also prevents CVD by maintaining vascular endothelial function.…”

Omega-3 Polyunsaturated Fatty Acid and Coronary Atherosclerotic Plaques

“…8,9) In humans consuming typical Western diets, the membrane phospholipids of inflammatory cells are rich in AA, which is an n-6 PUFA, and poor in EPA and DHA, which are n-3 PUFAs. [10][11][12] The content of n-3 PUFAs in inflammatory cells was reported to be augmented by the increased intakes of EPA and DHA.…”