Caffeoylquinic acids and their microbiota-derived metabolites ameliorate hepatic lipid metabolism disorders and egg yolk lipid composition via the gut-liver axis

Background: Fatty Liver Hemorrhagic Syndrome (FLHS) is currently the most prevalent lipid metabolism disorders disease in laying hens. Although FLHS has been studied for a long time, there are currently no effective therapeutic strategies. The regulation of gut microbiota is an important strategy and novel target for the treatment of fatty liver disease with good prospects. Caffeoylquinic acids (CQAs) may be potential gut microbiota modulators due to their extremely low bioavailability. However, the effects of CQAs on gut microbiota structure, hepatic lipid metabolism, and egg yolk fatty acids composition in laying hens, as well as their underlying mechanisms, remain poorly understood. Results: In this study, we used aged laying hens as a model to investigate the effect of CQAs on ameliorating FLHS, and the treatment groups were added with differential proportions of Artemisia argyi extract (SAE, rich in CQAs), and chlorogenic acid (CGA, used to verify the effects of CQAs). Our multi-omics approach (metagenomics, transcriptomics, and metabolite analysis) yielded several key findings: (1) CQAs significantly ameliorated FLHS, improving laying performance and egg quality while reducing hepatic lipid storage; (2) Metagenomic analysis identified Bacteroides and Phocaeicola as key bacterial genera mediating the anti-FLHS effects; (3) Microbial metabolites analysis revealed that CQAs supplementation reshaped the gut microbial ecosystem, increasing the levels of short-chain fatty acids (SCFAs) and specific microbial catabolites of CQAs (e.g., caffeic acid (CA), 3-(3'-hydroxyphenyl)propionic acid (3-HPP), 3-hydroxybenzoic acid (3-HBA), syringic acid, and vanillic acid); (4) Hepatic transcriptomics revealed that CQAs downregulated key lipogenic genes (e.g., ACLY , FASN , ACACA , SCD1 ) and upregulated genes involved in lipid transport and oxidation (e.g., ApoB , CPT1A , FABPs , CD36 , ACOX1 , SCP2 ); (5) Mechanistically, CQAs treatment markedly activated the ADPN-AMPK-PPARα pathway, thereby ameliorating lipid metabolism disorders and improving laying performance. Conclusions: Our findings indicate that CQAs and their microbiota-derived metabolites ameliorate hepatic lipid metabolism disorders and egg yolk lipid composition via the gut-liver axis. Crucially, we traced these metabolites from the gut to the systemic circulation and liver, establishing them as the primary effectors that activate the hepatic ADPN-AMPK-PPARα pathway. This activation coordinately downregulates lipogenesis and upregulates fatty acid transport and oxidation, thereby alleviating hepatic steatosis. This coordinated response alleviates hepatic steatosis and, notably, redirects lipids towards the ovary, enhancing the deposition of nutritionally beneficial fatty acids in egg yolk, which is a finding with significant implications for egg quality. Our work highlights gut microbiota metabolites as a promising therapeutic target for lipid metabolism disorders and transforms the understanding of how low-bioavailability substances exert their systemic effects.