Key Laboratory of Dairy Science, Ministry of Education, Northeast Agricultural University, Harbin 150030, China.
School of Biology and Food Engineering, Guangdong University of Petrochemical Technology, Maoming 525000, China.
Nutrients. 2022 Feb 6;14(3):686. doi: 10.3390/nu14030686.
In this study, milk protein casein was glycated by oligochitosan through the catalysis of transglutaminase (TGase) and then hydrolyzed by trypsin. The obtained glycated casein hydrolysates (GCNH) were assessed for their anti-inflammatory activities, using the lipopolysaccharide (LPS)-stimulated rat intestinal epithelial cells (IEC-6) as cell models and the casein hydrolysates (CNH) without TGase catalysis as controls. The results showed that GCNH had oligochitosan incorporation and thus possessed a glucosamine content of 5.74 g/kg protein. In general, GCNH at dose levels of 25-100 μg/mL could elevate IEC-6 cell growth, and at dose levels of 25-50 μg/mL, they were also able to alleviate the LPS-induced cytotoxicity by increasing cell viability efficiently. Although LPS caused clear inflammation in the LPS-stimulated cells, GCNH were capable of reducing the secretion of three pro-inflammatory mediators including interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α, or promoting the secretion of two anti-inflammatory mediators like IL-10 and transforming growth factor-β, demonstrating their anti-inflammatory activities to the stimulated cells. Moreover, GCNH also could down-regulate the expression of three inflammation-related proteins including TLR4, p-p38, and p-p65 in the stimulated cells, and thus possessed a capacity to suppress the phosphorylation of p38 and p65 proteins as well as to inactivate the NF-κB and MAPK signaling pathways. Additionally, a higher GCNH dose level consistently led to higher anti-inflammatory effect in the cells, while GCNH were always more potent than CNH at performing anti-inflammatory function targets. It is thus suggested that the TGase-catalyzed casein oligochitosan-glycation could enhance the anti-inflammatory activities of casein hydrolysates efficiently. TGase-catalyzed protein glycation thus might enhance the healthcare function of protein ingredients in the body.
在这项研究中，通过转谷氨酰胺酶（TGase）的催化，将乳蛋白酪蛋白与低聚壳聚糖糖化，然后用胰蛋白酶水解。所得的糖化酪蛋白水解物（GCNH）用于评估其抗炎活性，使用脂多糖（LPS）刺激的大鼠肠上皮细胞（IEC-6）作为细胞模型，并将未经 TGase 催化的酪蛋白水解物（CNH）作为对照。结果表明，GCNH 具有低聚壳聚糖掺入，因此具有 5.74 g/kg 蛋白质的氨基葡萄糖含量。通常，GCNH 在 25-100 μg/mL 的剂量水平下可以提高 IEC-6 细胞的生长，在 25-50 μg/mL 的剂量水平下，还可以通过有效提高细胞活力来减轻 LPS 诱导的细胞毒性。尽管 LPS 在 LPS 刺激的细胞中引起明显的炎症，但 GCNH 能够降低三种促炎介质（包括白细胞介素-1β（IL-1β）、IL-6 和肿瘤坏死因子-α）的分泌，或促进两种抗炎介质（如 IL-10 和转化生长因子-β）的分泌，从而表现出对刺激细胞的抗炎活性。此外，GCNH 还可以下调刺激细胞中三种与炎症相关的蛋白质（包括 TLR4、p-p38 和 p-p65）的表达，从而具有抑制 p38 和 p65 蛋白磷酸化以及失活 NF-κB 和 MAPK 信号通路的能力。此外，较高的 GCNH 剂量水平始终会导致细胞中更高的抗炎效果，而 GCNH 在发挥抗炎功能目标方面总是比 CNH 更有效。因此，TGase 催化的酪蛋白低聚壳聚糖糖化可以有效地增强酪蛋白水解物的抗炎活性。TGase 催化的蛋白质糖化因此可能增强蛋白质成分在体内的保健功能。
