Abstract Excessive production of nitric oxide (NO) during the lactation period of cows leads to oxidative stress and inflammatory reactions. Chitosan has enhanced effects on antioxidant and immune function, but the mechanism of this effect is unclear. The current study investigated the underlying mechanism of the protective effect chitosan oligosaccharides (COS) exert against oxidative damage of peripheral blood mononuclear cells (PBMCs) in dairy cows. PBMCs were allocated to receive one of treatments: CTR: control treatment without COS addition; COS40, COS80, COS160, and COS320 received 40, 80, 160, and 320 μg/mL of COS; PBMCs were then treated with 200 μmol/L diethylenetriamine/nitric oxide (DETA/NO) for 4 h. Compared to the CTR group, the cell viability of the COS pre-treated group increased with increasing COS concentration. The activities of antioxidant enzymes including superoxide dismutase, catalase, and glutathione peroxidase and the thioredoxin reductase content showed an upward trend in a dose-dependent manner and COS at a concentration of 160 μg/mL exhibited the strongest effect. COS decreased the content and gene expressions of interleukin-1β and tumour necrosis factor-α, the mRNA and protein expression and activity of the inducible nitric oxide synthase, and NO production compared with the values observed in the CTR group. The expression of genes and proteins related to the nuclear factor kappa-B (NF-κB) pathway also showed a downward trend. Based on these indicators, we concluded COS has a protective effect against oxidative damage caused by DETA/NO, and we speculated that COS may play a protective role by inhibiting the NF-κB pathway. Highlights In vitro experiments simulated changes in antioxidant and immune functions caused by increased NO in dairy cows’ PBMCs in vivo. We showed that chitosan has a protective effect against oxidative damage and a regulatory effect on immune function in vitro. The regulation of chitosan against oxidative stress and immune responses may be related to the NF-KB signalling pathway.

中文翻译：

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壳寡糖对二乙烯三胺/一氧化氮通过NF-κB信号通路诱导奶牛外周血单个核细胞氧化损伤的保护作用

摘要 奶牛泌乳期产生过多的一氧化氮（NO）会导致氧化应激和炎症反应。壳聚糖对抗氧化和免疫功能有增强作用，但这种作用的机制尚不清楚。目前的研究调查了壳寡糖 (COS) 对奶牛外周血单核细胞 (PBMC) 氧化损伤的保护作用的潜在机制。PBMC 被分配接受以下治疗之一： CTR：不添加 COS 的对照治疗；COS40、COS80、COS160 和 COS320 接受 40、80、160 和 320 μg/mL 的 COS；然后用 200 μmol/L 二亚乙基三胺/一氧化氮 (DETA/NO) 处理 PBMC 4 小时。与CTR组相比，COS预处理组的细胞活力随着COS浓度的增加而增加。超氧化物歧化酶、过氧化氢酶、谷胱甘肽过氧化物酶等抗氧化酶的活性和硫氧还蛋白还原酶的含量呈剂量依赖性上升趋势，160 μg/mL 浓度的COS 作用最强。与 CTR 组观察到的值相比，COS 降低了白细胞介素 1β 和肿瘤坏死因子 α 的含量和基因表达，诱导型一氧化氮合酶的 mRNA 和蛋白质表达和活性，以及​​ NO 的产生。与核因子κ-B（NF-κB）通路相关的基因和蛋白质的表达也呈下降趋势。基于这些指标，我们推断COS对DETA/NO引起的氧化损伤具有保护作用，推测COS可能通过抑制NF-κB通路发挥保护作用。亮点 体外实验模拟了体内奶牛 PBMC 中 NO 增加引起的抗氧化和免疫功能的变化。我们在体外表明壳聚糖具有抗氧化损伤的保护作用和对免疫功能的调节作用。壳聚糖对氧化应激和免疫反应的调节可能与 NF-KB 信号通路有关。