Intensive production can cause immunological stress in commercial broilers. Chlorogenic acid (CGA) regulates the intestinal microbiota, barrier function, and immune function in chickens. As complex interrelations regulate the dynamic interplay between gut microbiota, the host, and diverse health outcomes, the aim of this study was to elucidate the immunoregulatory mechanisms of CGA using multi-omics approaches. A total of 240 one-day-old male broilers were assigned to a 2 × 2 factorial design with 2 CGA levels (0 or 500 mg/kg) either with or without dexamethasone (DEX) injection for a 21-day experimental period. Therefore, there were 4 dietary treatments: control, DEX, CGA, and DEX + CGA, with 6 replicates per treatment. CGA supplementation improved (P < 0.05) growth performance, jejunal morphology, jejunal barrier function, and immune function in DEX-treated broilers. Moreover, in DEX + CGA-treated broilers, the increase in gut microbiome diversity (P < 0.05) was consistent with a change in taxonomic composition, especially in the Clostridiales vadin BB60_group. Additionally, the levels of short-chain fatty acids increased remarkably (P < 0.01) after CGA supplementation. This was consistent with the Kyoto Encyclopedia of Genes and Genomes analysis results that the “pyruvate fermentation to butanoate” pathway was more enriched (P < 0.01) in the DEX + CGA group than in the DEX group. Proteomics revealed that CGA treatment increased the expression of several health-promoting proteins, thymosin beta (TMSB4X) and legumain (LGMN), which were verified by multiple reaction monitoring. Metabolomics revealed that CGA treatment increased the expression of health-promoting metabolites (2,4-dihydroxy benzoic acid and homogentisic acid). Proteomic and metabolic analyses showed that CGA treatment regulated the peroxisome proliferator-activated receptor (PPAR) and mitogen-activated protein kinase (MAPK) pathways. Western blotting results support these findings. Pearson’s correlation analyses showed correlations (P < 0.01) between altered immune function, jejunal barrier function, different microbiota, proteins, and metabolites parameters. Overall, our data indicate that CGA treatment increased growth performance and improved the immunological functions of DEX-treated broilers by regulating gut microbiota and the PPAR and MAPK pathways. The results offer novel insights into a CGA-mediated improvement in immune function and intestinal health.

集约化生产可能会导致商业肉鸡的免疫应激。绿原酸 (CGA) 调节鸡的肠道微生物群、屏障功能和免疫功能。由于复杂的相互关系调节着肠道微生物群、宿主和不同健康结果之间的动态相互作用，本研究的目的是利用多组学方法阐明 CGA 的免疫调节机制。总共 240 只一日龄雄性肉鸡被分配到 2 × 2 析因设计，具有 2 个 CGA 水平（0 或 500 mg/kg），注射或不注射地塞米松 (DEX)，实验期为 21 天。因此，有 4 种饮食治疗：对照、DEX、CGA 和 DEX + CGA，每个治疗 6 个重复。CGA 补充剂改善了 DEX 处理的肉鸡的生长性能、空肠形态、空肠屏障功能和免疫功能。此外，在 DEX + CGA 处理的肉鸡中，肠道微生物组多样性的增加 ( P  < 0.05) 与分类组成的变化一致，特别是在 Clostridiales vadin BB60_group 中。 此外，补充CGA后，短链脂肪酸的水平显着增加（P <0.01）。这与京都基因与基因组百科全书分析结果一致，即 DEX+CGA组的“丙酮酸发酵为丁酸”途径比DEX组更富集（ P <0.01）。蛋白质组学显示，CGA 治疗增加了几种促进健康的蛋白质、胸腺素β (TMSB4X) 和legumain (LGMN) 的表达，这已通过多重反应监测得到验证。代谢组学显示，CGA 治疗增加了促进健康的代谢物（2,4-二羟基苯甲酸和黑黑酸）的表达。蛋白质组学和代谢分析表明，CGA 治疗可调节过氧化物酶体增殖物激活受体 (PPAR) 和丝裂原激活蛋白激酶 (MAPK) 途径。蛋白质印迹结果支持这些发现。Pearson 相关分析显示 免疫功能改变、空肠屏障功能、不同微生物群、蛋白质和代谢物参数之间存在相关性（ P < 0.01）。总体而言，我们的数据表明，CGA 处理通过调节肠道微生物群以及 PPAR 和 MAPK 途径，提高了 DEX 处理肉鸡的生长性能并改善了免疫功能。这些结果为 CGA 介导的免疫功能和肠道健康改善提供了新的见解。