Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czech Republic.
Eur J Nutr. 2010 Apr;49(3):133-9. doi: 10.1007/s00394-009-0057-3. Epub 2009 Sep 26.
Polyunsaturated fatty acids (PUFAs) can affect various functions of the immune system including inflammatory responses. An oxidative burst of phagocytes accompanied by reactive oxygen species (ROS) and reactive nitrogen species (RNS) formation is one of the phagocyte functions that could be modulated by PUFAs.
To investigate the effects of omega-3 (alpha-linolenic, docosahexaenoic, eicosapentaenoic) and omega-6 (arachidonic, linoleic) PUFAs on lipopolysaccharide (LPS)-stimulated ROS and RNS production by the murine macrophage cell line RAW 264.7.
Murine peritoneal macrophages RAW 264.7 were stimulated with LPS (0.1 microg/ml) and treated with 0.1-100 microM omega-3 or omega-6 PUFAs for either 8 (ROS production) or 20 h (RNS production). The cytotoxicity of PUFAs was evaluated by an ATP (adenosine triphosphate) test after both 8 and 20 h of treatment with PUFAs. Changes in ROS production by LPS-treated macrophages subsequently activated with phorbol myristate acetate (PMA) or opsonized zymosan particles (OZP) were determined by luminol-enhanced chemiluminescence, whilst the production of RNS was determined as the concentration of nitrites in cell supernatants (Griess reaction). Changes in inducible nitric oxide synthase (iNOS) expression were evaluated by Western blot analysis. The antioxidant properties of PUFAs were tested by TRAP (total peroxyl radical-trapping antioxidant parameter) assay.
All PUFAs in 100 microM concentration except eicosapentaenoic acid decreased ROS production. The effect was most significant when docosahexaenoic acid was used. Arachidonic acid decreased PMA-activated ROS production even in 1 and 10 microM concentrations. On the other hand, 10 and 100 microM eicosapentaenoic acid potentiated ROS production. As concerns RNS production, all the fatty acids that were tested in a concentration of 100 microM decreased iNOS expression and nitrite accumulation. Fatty acids had no significant effect on the viability and proliferation of RAW 264.7 cells. The TRAP assay confirmed that none of the tested PUFAs exerted any significant antioxidant properties.
High concentrations of PUFAs of both omega-3 and omega-6 groups can inhibit ROS and RNS formation by stimulated macrophages. The expression of iNOS can also be inhibited. This effect, together with the absence of antioxidant activity and cytotoxic properties, indicates that PUFAs can participate in the regulation of enzymes responsible for reactive species production.
多不饱和脂肪酸（PUFAs）可以影响免疫系统的各种功能，包括炎症反应。吞噬细胞的氧化爆发伴随着活性氧（ROS）和活性氮（RNS）的形成，是吞噬细胞功能之一，可以通过 PUFAs 进行调节。
研究 ω-3（α-亚麻酸、二十二碳六烯酸、二十碳五烯酸）和 ω-6（花生四烯酸、亚油酸）多不饱和脂肪酸对脂多糖（LPS）刺激的 RAW 264.7 鼠巨噬细胞系 ROS 和 RNS 产生的影响。
用 LPS（0.1μg/ml）刺激鼠腹腔巨噬细胞 RAW 264.7，并在 8 小时（ROS 产生）或 20 小时（RNS 产生）内用 0.1-100μM 的 ω-3 或 ω-6 PUFAs 处理。用 ATP（三磷酸腺苷）试验在处理 PUFAs 8 和 20 小时后评估 PUFAs 的细胞毒性。通过鲁米诺增强化学发光法测定 LPS 处理的巨噬细胞随后用佛波醇肉豆蔻酸酯（PMA）或包被的酵母聚糖颗粒（OZP）激活后 ROS 的产生变化，同时通过格里斯反应测定细胞上清液中 RNS 的浓度（亚硝酸盐）。通过 Western blot 分析评估诱导型一氧化氮合酶（iNOS）的表达变化。用 TRAP（总过氧自由基捕获抗氧化参数）测定法测试 PUFAs 的抗氧化性能。
除二十碳五烯酸外，所有浓度为 100μM 的 PUFAs 均降低了 ROS 的产生。当使用二十二碳六烯酸时，效果最为显著。花生四烯酸甚至在 1 和 10μM 浓度下降低了 PMA 激活的 ROS 产生。另一方面，10 和 100μM 的二十碳五烯酸增强了 ROS 的产生。至于 RNS 的产生，在 100μM 浓度下测试的所有脂肪酸均降低了 iNOS 的表达和亚硝酸盐的积累。脂肪酸对 RAW 264.7 细胞的活力和增殖没有显著影响。TRAP 测定证实，所测试的 PUFAs 均无明显的抗氧化性能。
ω-3 和 ω-6 组的高浓度 PUFAs 可抑制刺激巨噬细胞的 ROS 和 RNS 的形成。iNOS 的表达也可以被抑制。这种效应，加上缺乏抗氧化活性和细胞毒性特性，表明 PUFAs 可以参与调节负责活性物质产生的酶。
