Adler N, Schoeniger A, Fuhrmann H
Institute of Biochemistry, Faculty of Veterinary Medicine, University of Leipzig, Leipzig, Germany.
J Anim Physiol Anim Nutr (Berl). 2018 Apr;102(2):e623-e632. doi: 10.1111/jpn.12804. Epub 2017 Oct 13.
Although it is well recognized that dietary supplementation with fish oil improves clinical symptoms in dogs suffering from osteoarthritis, the molecular basis for the dietary benefit is not yet completely resolved in dogs. This study was designed to further clarify how polyunsaturated fatty acids (PUFA) affect key factors of cartilage degeneration in a canine cell culture system mimicking osteoarthritis. Canine chondrocytes were incubated either without or with 10 μm of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), arachidonic acid (AA) or 3.6 μm ibuprofen (Ibu) as positive control for 6 days. After the supplementation, cells were stimulated with 10 ng/ml interleukin-1β (IL-1β) for another 48 hr to induce osteoarthritic changes, or left unstimulated. We analysed fatty acid uptake via gas-liquid chromatography, nitric oxide (NO) production via Griess assay, prostaglandin E (PGE) production via ELISA and relative gene expression of several cartilage matrix proteinases, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 via RT-qPCR. After supplementation, the chondrocytes rapidly incorporated the PUFA into their fatty acid pools. The stimulation with IL-1β caused a marked increase of most of the inflammatory markers measured. N-3 PUFA EPA reduced IL-induced gene expression of iNOS and corresponding production of NO. N-6 PUFA AA also decreased iNOS and NO, but furthermore lowered gene expression of matrix metalloproteinase-3. On the other hand, AA upregulated the aggrecanase ADAMTS-5 and augmented the release of PGE. The effect of n-3 PUFA DHA turned out to be negligible. Our results reveal molecular mechanisms by which PUFA affect degenerative joint disease in dogs. Of particular importance is that not only EPA but also AA decreased several inflammatory markers in our model. Thus, we conclude that an appropriate balance of both n-3 and n-6 fatty acids deserves more attention in dietary interventions.
尽管人们已经充分认识到，在患有骨关节炎的犬类中，补充鱼油可改善临床症状，但在犬类中，饮食益处的分子基础尚未完全明确。本研究旨在进一步阐明多不饱和脂肪酸（PUFA）如何在模拟骨关节炎的犬类细胞培养系统中影响软骨退变的关键因素。将犬软骨细胞在无添加物的情况下培养，或分别与10 μM的二十碳五烯酸（EPA）、二十二碳六烯酸（DHA）、花生四烯酸（AA）或3.6 μM布洛芬（Ibu，作为阳性对照）一起培养6天。补充后，用10 ng/ml白细胞介素-1β（IL-1β）刺激细胞另外48小时以诱导骨关节炎变化，或不进行刺激。我们通过气液色谱法分析脂肪酸摄取，通过格里斯试剂法分析一氧化氮（NO）生成，通过酶联免疫吸附测定法分析前列腺素E（PGE）生成，并通过逆转录定量聚合酶链反应（RT-qPCR）分析几种软骨基质蛋白酶、诱导型一氧化氮合酶（iNOS）和环氧化酶-2的相对基因表达。补充后，软骨细胞迅速将PUFA纳入其脂肪酸池。IL-1β刺激导致所测量到的大多数炎症标志物显著增加。N-3多不饱和脂肪酸EPA降低了IL诱导的iNOS基因表达和相应的NO生成。N-6多不饱和脂肪酸AA也降低了iNOS和NO，但进一步降低了基质金属蛋白酶-3的基因表达。另一方面，AA上调了聚集蛋白聚糖酶ADAMTS-5并增加了PGE的释放。n-3多不饱和脂肪酸DHA的作用可忽略不计。我们的结果揭示了PUFA影响犬类退行性关节疾病的分子机制。特别重要的是，在我们的模型中，不仅EPA而且AA都降低了几种炎症标志物。因此，我们得出结论，在饮食干预中，n-3和n-6脂肪酸的适当平衡值得更多关注。
