Modulation of pathogenesis-related gene expression by Curcumin and probiotics during Salmonella Typhimurium infection in broiler chickens: Implications as antibiotic alternatives

Abstract

This study evaluated the mechanistic effects of dietary curcumin combined with probiotics on bacterial burden, inflammatory signaling, and oxidative stress responses in the liver and spleen of Salmonella Typhimurium-challenged broiler chickens. Broiler chicks were experimentally infected with S. Typhimurium following dietary supplementation with curcumin and probiotics. Clinical outcomes, bacterial recovery from immune organs, antioxidant status, and expression of key inflammatory mediators were assessed to elucidate host-pathogen interactions. S. Typhimurium challenge triggered severe clinical disease, high mortality, increased bacterial colonization, and pronounced oxidative and inflammatory responses characterized by elevated total oxidant status and upregulation of IL-6, IL-8, IL-17A, and iNOS. Combined curcumin-probiotic supplementation significantly reduced bacterial loads in the liver and spleen and attenuated disease severity. These protective effects were associated with enhanced antioxidant enzyme activity, restoration of redox homeostasis, and marked suppression of proinflammatory gene expression. Mechanistically, curcumin in combination with probiotics likely modulated pathogen-induced TLR4/MyD88 signaling, thereby limiting downstream NF-?B and MAPK activation and reducing cytokine-driven reactive oxygen species amplification. This antibiotic-free strategy represents a promising nutritional approach for improving poultry health, enhancing disease resilience, and reduce the risk of Salmonella transmission through the food chain.