Inflammatory bowel disease, a gut disease that is prevalent worldwide, is characterized by chronic intestinal inflammation, such as colitis, and disorder of the gut microbiome. Glycine (Gly) is the simplest amino acid and functions as an anti-inflammatory immune-nutrient and intestinal microbiota regulator. This study aimed at investigating the effect of Gly on colitis induced in mice by intrarectal administration of 5% acetic acid (AA). Bodyweight and survival rates were monitored, and colonic length and weight, serum amino acid concentrations, intestinal inflammation-related gene expression, and colonic microbiota abundances were analyzed. The results showed that Gly dietary supplementation had no effect on the survival rate or the ratio of colonic length to weight. However, Gly supplementation reversed the AA-induced increase in serum concentrations of amino acids such as glutamate, leucine, isoleucine, and valine. Furthermore, Gly inhibited colonic gene expression of interleukin- (IL-) 1β and promoted IL-10 expression in colitis mice. Gly supplementation also reversed the AA-induced reduction in the abundance of bacteria such as Clostridia, Ruminococcaceae, and Clostridiales. This change in the intestinal microbiota was possibly attributable to the changes in colonic IL-10 expression and serum concentrations of valine and leucine. In sum, Gly supplementation regulated the serum concentrations of amino acids, the levels of colonic immune-associated gene expression, and the intestinal microbiota in a mouse model of colitis. These findings enhance our understanding of the role of Gly in regulating metabolism, intestinal immunity, and the gut microbiota in animals afflicted with colitis.

中文翻译：

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日粮甘氨酸对乙酸诱发的结肠炎小鼠模型的影响。

炎症性肠病是一种全球范围内普遍存在的肠道疾病，其特征在于慢性肠道炎症（例如结肠炎）和肠道微生物组失调。甘氨酸（Gly）是最简单的氨基酸，具有抗炎免疫营养和肠道菌群调节剂的功能。这项研究旨在研究Gly对通过直肠内施用5％乙酸（AA）诱导的小鼠结肠炎的作用。监测体重和存活率，并分析结肠长度和重量，血清氨基酸浓度，肠道炎症相关基因表达以及结肠微生物群丰度。结果表明，Gly膳食补充剂对成活率或结肠长度与体重的比率没有影响。然而，补糖可以逆转AA引起的血清中谷氨酸，亮氨酸，异亮氨酸和缬氨酸等氨基酸浓度的增加。此外，Gly抑制结肠基因表达白介素-（IL-）1β并促进结肠炎小鼠的IL-10表达。补糖还可以逆转AA诱导的细菌（如梭状芽胞杆菌，瘤胃球菌和梭状芽孢杆菌）丰度的降低。肠道菌群的这种变化可能归因于结肠IL-10表达的变化以及缬氨酸和亮氨酸的血清浓度。总之，Gly补充剂可调节结肠炎小鼠模型中的血清氨基酸浓度，结肠免疫相关基因表达水平和肠道菌群。这些发现增强了我们对Gly在患结肠炎的动物中调节代谢，肠道免疫和肠道菌群的作用的理解。