ObjectivesWe investigated the protective effect of Rehmannia glutinosa oligosaccharides (RGO) on lipopolysaccharide (LPS)-induced intestinal inflammation and barrier injury among mice.MethodsRGO is prepared from fresh rehmannia glutinosa by water extraction, active carbon decolorization, ion exchange resin impurity removal, macroporous adsorption resin purification, and decompression drying. LPS could establish the model for intestinal inflammation and barrier injury in mice. Three different doses of RGO were administered for three consecutive weeks. Then the weight, feces, and health status of the mice were recorded. After sacrificing the mice, their colon length and immune organ index were determined. The morphological changes of the ileum and colon were observed using Hematoxylin-eosin (H&E) staining, followed by measuring the villus length and recess depth. RT-qPCR was utilized to detect the relative mRNA expression of intestinal zonula occludens-1 (ZO-1) and occludin. The expression of inflammatory factors and oxidation markers within ileum and colon tissues and the digestive enzyme activities in the ileum contents were detected using ELISA. The content of short-chain fatty acids (SCFAs) in the colon was determined with GC. The gut microbial composition and diversity changes were determined with 16S-rRNA high-throughput sequencing. The association between intestinal microorganisms and SCFAs, occludins, digestive enzymes, inflammatory factor contents, and antioxidant indexes was also analyzed.ResultsRGO significantly increased the weight, pancreatic index, thymus index, and colon length of mice compared with the model group. Moreover, it also improved the intestinal tissue structure and increased the expression of intestinal barrier-related junction proteins ZO-1 and Occludin. The contents of IL-6, IL-17, IL-1β, and TNF-α in the intestinal tissues of mice were significantly reduced. Additionally, the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) were elevated. In contrast, the malondialdehyde (MDA) content decreased. Trypsin and pancreatic lipase activities in the ileum enhanced, and the SCFA contents such as acetic acid, propionic acid, and butyric acid in the colon increased. The study on intestinal flora revealed that RGO could enhance the abundance of intestinal flora and improve the flora structure. After RGO intervention, the relative abundance of Firmicutes, Lactobacillus, and Akkermania bacteria in the intestinal tract of mice increased compared with the model group, while that of Actinomycetes decreased. The intestinal microbiota structure changed to the case, with probiotics playing a dominant role. The correlation analysis indicated that Lactobacillus and Ackermann bacteria in the intestinal tract of mice were positively associated with SCFAs, Occludin, ZO-1, pancreatic amylase, SOD, and CAT activities. Moreover, they were negatively correlated with inflammatory factors IL-6, IL-17, IL-1β, and TNF-α.ConclusionsRGO can decrease LPS-induced intestinal inflammation and intestinal barrier injury in mice and protect their intestinal function. RGO can ameliorate intestinal inflammation and maintain the intestinal barrier by regulating intestinal flora.

中文翻译：

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从地黄中分离出的低聚糖可保护 LPS 诱导的小鼠肠道炎症和屏障损伤

目的我们研究了地黄低聚糖 (RGO) 对脂多糖 (LPS) 诱导的小鼠肠道炎症和屏障损伤的影响。地黄经水提、活性炭脱色、离子交换树脂除杂、大孔吸附树脂提纯、减压干燥。LPS可以建立小鼠肠道炎症和屏障损伤模型。连续三周施用三种不同剂量的RGO。然后记录小鼠的体重、粪便和健康状况。处死小鼠后，测定其结肠长度和免疫器官指数。使用苏木精-伊红(H&E)染色观察回肠和结肠的形态变化，然后测量绒毛长度和隐窝深度。利用RT-qPCR检测小肠zonula occludens-1的相对mRNA表达(ZO-1)和闭合蛋白. 采用ELISA法检测回肠和结肠组织中炎症因子和氧化标志物的表达以及回肠内容物中消化酶的活性。结肠中短链脂肪酸（SCFAs）的含量用气相色谱法测定。通过 16S-rRNA 高通量测序确定肠道微生物组成和多样性变化。分析肠道微生物与SCFAs、occludins、消化酶、炎症因子含量、抗氧化指标的相关性。结果与模型组相比，RGO显着增加了小鼠的体重、胰腺指数、胸腺指数和结肠长度。此外，它还改善了肠道组织结构，增加了肠屏障相关连接蛋白 ZO-1 和 Occludin 的表达。IL-6、IL-17、小鼠肠道组织中IL-1β、TNF-α显着降低。此外，超氧化物歧化酶 (SOD)、谷胱甘肽过氧化物酶 (GSH-Px) 和过氧化氢酶 (CAT) 的活性升高。相反，丙二醛（MDA）含量下降。回肠胰蛋白酶和胰脂肪酶活性增强，结肠中乙酸、丙酸、丁酸等SCFA含量增加。对肠道菌群的研究表明，RGO可以增强肠道菌群的丰度，改善菌群结构。RGO 干预后，厚壁菌门的相对丰度，丙二醛（MDA）含量下降。回肠胰蛋白酶和胰脂肪酶活性增强，结肠中乙酸、丙酸、丁酸等SCFA含量增加。对肠道菌群的研究表明，RGO可以增强肠道菌群的丰度，改善菌群结构。RGO 干预后，厚壁菌门的相对丰度，丙二醛（MDA）含量下降。回肠胰蛋白酶和胰脂肪酶活性增强，结肠中乙酸、丙酸、丁酸等SCFA含量增加。对肠道菌群的研究表明，RGO可以增强肠道菌群的丰度，改善菌群结构。RGO 干预后，厚壁菌门的相对丰度，乳酸菌， 和阿克曼尼亚与模型组相比，小鼠肠道细菌增多，放线菌减少。肠道菌群结构发生变化，益生菌占主导地位。相关性分析表明，小鼠肠道中的乳酸菌和阿克曼菌与SCFAs呈正相关，闭合蛋白，ZO-1、胰淀粉酶、SOD 和 CAT 活性。且与炎症因子IL-6、IL-17、IL-1β、TNF-α呈负相关。RGO可以通过调节肠道菌群来改善肠道炎症并维持肠道屏障。