Berberine Reveals Anticoccidial Activity by Influencing Immune Responses in Eimeria acervulina-Infected Chickens

Serious enteric disease caused by seven species of Eimeira continues to cause significant economic damage to the poultry industry. E. acervulina is one of the most widespread strains in farms and has a significant impact on chicken weight loss. Currently, the use of anticoccidial agents to suppress the occurrence of coccidiosis in farms is considerably restricted due to public health and environmental pollution issues. It is important to understand the protective immunity of the host against Eimeria infections with regard to natural products that could be used as alternatives to anticoccidial agents. Berberine chloride is known for its various biological functions, including its anti-parasite activity. However, its impact on intestinal morphology and immune-related activity in broilers infected with Eimeria still remains unclear. The aim of this study is to evaluate the anticoccidial effects of a berberine-based diet in broilers infected with E. acervulina and to monitor the host immune phenomenon using transcriptomic analysis. Administration of berberine to chickens infected with E. acervulina significantly reduced fecal oocyst production and intestinal lesion scores, and increased duodenal villus height, indicating anticoccidial activity and positive effects on intestinal morphology. Transcriptomic analysis of chickens infected with E. acervulina generally observed the down-regulation of metabolism-related genes and the up-regulation of cell integrity-related genes at day 4 post-infection. At day 6 post-infection, an increase in immune-related genes and cellular-homeostasis-related genes was generally observed. Berberine-treated and E. acervulina-infected chickens showed cytokine-cytokine receptor interaction in the second term in a Kyoto Encyclopedia of Genes and Genomes pathway analysis at day 4 post-infection, but not in chickens infected with E. acervulina alone, suggesting host immune changes induced by berberine. These results suggest that berberine, which exhibits anticoccidial effects, may have therapeutic and/or prophylactic potential in protecting the host from infectious and economic-loss-causing diseases, such as Eimeria infection.