Background. Clinical data suggest that enteral nutrition (EN) effectively decreases disease activity and maintains remission in patients with inflammatory bowel disease (IBD). However, the modulatory effects of EN on the intestinal mucosal immune system remain unclear. Aims. This study first aimed at comparing the therapeutic effects of three EN formulas on ameliorating dextran sulfate sodium- (DSS-) induced chronic colitis; with the most effective formula, we then examined its influence on the mucosal inflammatory response and epithelial barrier function. Methods. The effect of EN formulas on colitis in mice was assessed by body weight, disease activity index scores, colon length, and H&E staining for pathological examination. Colonic and circulating cytokine expression levels and the frequencies of immune cells were also analyzed. Intestinal epithelial barrier function was evaluated by detecting tight junction proteins. Results. We found that among the three EN formulas, an elemental diet (ED) containing enriched amino acids restored the colitis-related reduction in body weight better than the other two EN formulas. ED amino acids suppressed the release of colonic proinflammatory mediators and maintained the expression of tight junction proteins in these mice. ED amino acid treatment mitigated the colitis-induced increase in CD103⁺CD11b⁺ dendritic cells and CD4⁺ and CD8⁺ T cells and inhibited the predominant Th1/Th17 responses particularly in the colonic mucosal lamina propria of mice with colitis. Conclusions. We showed that ED amino acids can be an effective immunomodulatory agent to reduce colitis-related inflammation by inhibiting proinflammatory mediators and Th1/Th17 cell responses and by repairing the disrupted epithelial barrier.

中文翻译：

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富含氨基酸的元素饮食可减轻 DSS 诱导的慢性结肠炎小鼠的粘膜炎症反应并预防结肠上皮屏障功能障碍。

背景。临床数据表明，肠内营养 (EN) 可有效降低炎症性肠病 (IBD) 患者的疾病活动性并维持缓解。然而，EN 对肠黏膜免疫系统的调节作用仍不清楚。目标。本研究首先旨在比较三种EN配方对改善葡聚糖硫酸钠（DSS-）诱发的慢性结肠炎的治疗作用；使用最有效的配方，我们随后检查了它对粘膜炎症反应和上皮屏障功能的影响。方法. 通过体重、疾病活动指数评分、结肠长度和病理检查的 H&E 染色评估 EN 配方对小鼠结肠炎的影响。还分析了结肠和循环细胞因子的表达水平以及免疫细胞的频率。通过检测紧密连接蛋白评估肠上皮屏障功能。结果。我们发现，在三种 EN 配方中，含有丰富氨基酸的元素饮食 (ED) 比其他两种 EN 配方更好地恢复了与结肠炎相关的体重减轻。ED 氨基酸抑制结肠促炎介质的释放并维持这些小鼠中紧密连接蛋白的表达。ED 氨基酸治疗减轻了结肠炎引起的 CD103 ⁺ CD11b增加⁺树突状细胞和 CD4 ⁺和 CD8 ⁺ T 细胞并抑制主要的 Th1/Th17 反应，特别是在结肠炎小鼠的结肠粘膜固有层中。结论。我们发现 ED 氨基酸可以成为一种有效的免疫调节剂，通过抑制促炎介质和 Th1/Th17 细胞反应以及修复破坏的上皮屏障来减少结肠炎相关炎症。