Commensal bacteria and polyunsaturated fatty acids (PUFAs) have both been shown independently to modulate immune responses. This study tested the hypothesis that the different colonic immunomodulatory responses to commensal (Lactobacillus gasseri) and pathogenic bacteria (Escherichia coli and Staphylococcus aureus) may be modified by PUFAs. Experiments used a Transwell system combining the colorectal cell line HT29, or its mucous secreting sub‐clone HT29‐MTX, with peripheral blood mononuclear cells to analyse immunomodulatory signalling in response to bacteria, with and without prior treatment with arachidonic acid, eicosapentaenoic acid or docosahexaenoic acid. L. gasseri increased transforming growth factor β1 (TGF‐β1) mRNA and protein secretion in colonic cell lines when compared with controls, an effect that was enhanced by pre‐treatment with eicosapentaenoic acid. In contrast, the Gram‐negative pathogen E. coli LF82 had no significant effect on TGF‐β1 protein. L. gasseri also increased IL‐8 mRNA but not protein while E. coli increased both; although differences between PUFA treatments were detected, none were significantly different to controls. Colonic epithelial cells show different immunomodulatory signalling patterns in response to the commensal L. gasseri compared to E. coli and S. aureus and pre‐treatment of these cells with PUFAs can modify responses. Practical applications: We have demonstrated an interaction between dietary PUFAs and epithelial cell response to both commensal and pathogenic bacteria found in the gastrointestinal tract by utilising in vitro co‐culture models. The data suggest that n‐3 PUFAs may provide some protection against the potentially damaging effects of pathogens. Furthermore, the beneficial effects of combining n‐3 PUFAs and the commensal bacteria, and potential probiotic, L. gasseri are illustrated by the increased expression of immunoregulatory TGF‐β1.

中文翻译：

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多不饱和脂肪酸在共培养模型中改变 TGF-β 的表达，该模型利用暴露于格氏乳杆菌、大肠杆菌和金黄色葡萄球菌的人结肠直肠细胞和人外周血单核细胞

共生细菌和多不饱和脂肪酸 (PUFA) 均已被证明可独立调节免疫反应。本研究验证了对共生菌（格氏乳杆菌）和致病菌（大肠杆菌和金黄色葡萄球菌）的不同结肠免疫调节反应可能被多不饱和脂肪酸修饰的假设。实验使用了 Transwell 系统，将结肠直肠细胞系 HT29 或其粘液分泌亚克隆 HT29-MTX 与外周血单核细胞相结合，以分析对细菌的免疫调节信号传导，无论是否事先用花生四烯酸、二十碳五烯酸或二十二碳六烯酸处理酸。与对照相比，L.gasseri 增加了结肠细胞系中转化生长因子 β1 (TGF-β1) 的 mRNA 和蛋白质分泌，通过用二十碳五烯酸进行预处理可以增强这种效果。相比之下，革兰氏阴性病原体大肠杆菌 LF82 对 TGF-β1 蛋白没有显着影响。L.gasseri 也增加了 IL-8 mRNA 但不增加蛋白质，而大肠杆菌增加了两者；尽管检测到 PUFA 处理之间的差异，但没有一个与对照组有显着差异。与大肠杆菌和金黄色葡萄球菌相比，结肠上皮细胞对共生 L.gasseri 的反应表现出不同的免疫调节信号模式，并且用 PUFA 预处理这些细胞可以改变反应。实际应用：我们利用体外共培养模型证明了膳食 PUFA 与上皮细胞对胃肠道中发现的共生细菌和病原菌的反应之间的相互作用。数据表明，n-3 PUFA 可能对病原体的潜在破坏性影响提供一些保护。此外，免疫调节 TGF-β1 的表达增加说明了 n-3 PUFA 与共生细菌和潜在的益生菌 L.gasseri 结合的有益效果。