Integrated analysis of microbiome and transcriptome reveals the mechanisms underlying the chlorogenic acid-mediated attenuation of oxidative stress and systemic inflammatory responses via gut-liver axis in post-peaking laying hens.

BACKGROUND: Systemic inflammatory responses and oxidative stress occur in laying hens during the aging process, particularly during the post-peaking laying period, which generally result in multi-organ damages, leading to significant declines in egg performance and quality. Chlorogenic acid (CGA)-enriched extract from Eucommia ulmoides leaves has anti-inflammatory and antioxidant activities. However, the mechanisms underlying whether and how CGA alleviates systemic inflammatory responses and oxidative stress to improve egg performance and quality in post-peaking laying hens remain unclear. In this study, the potential regulatory mechanisms of CGA in alleviating inflammatory responses and oxidative stress along the gut-liver axis were investigated. A total of 360 55-week-old Hy-line white-laying hens were randomly selected and divided into four groups. The hens in the four groups were fed a basal diet (CON) or basal diets supplemented with 200, 400, and 800 mg/kg of CGA (CGA200, CGA400, and CGA800, respectively) for 10 weeks. RESULTS: The results demonstrated that CGA significantly alleviated intestinal and hepatic damages resulting from systemic inflammatory responses and oxidative stress, thereby improving the laying performance and egg quality of post-peaking laying hens. CGA reduced systemic inflammation by improving intestinal barrier function and modulating inflammation-associated microbiota (Blautia and Megamonas), thus inhibiting endotoxin translocation. CGA can also reduce oxidative stress by upregulating the NRF-2 pathway-related genes and increasing antioxidant enzyme activities in the liver. The results of transcriptome sequencing revealed that CGA promoted lipid metabolism by regulating hepatic adipocytokine pathway-related genes/protein and reduced the inflammatory responses and apoptosis in liver by regulating PI3K/AKT pathway-related genes/proteins, which was also verified by qPCR and western blotting. CONCLUSION: CGA alleviated multi-organ damages and dysfunction by suppressing the systemic inflammatory responses and oxidative stress in post-peaking laying hens, thereby improving egg performance and quality. The optimal dose of CGA is 400 mg/kg in this experiment. These results provide a sound theoretical basis for the application of CGA as an exogenous animal feed additive for laying hens.