High Dietary Iron Differentially Influences the Iron Distribution in the Livers and the Spleens of Laying Hens After Salmonella Typhimurium Infection.

Salmonella and the host battle for iron (Fe), due to its importance for fundamental cellular processes. To investigate Fe redistribution of Salmonella-infected hens and the effects of high dietary Fe on it, Salmonella-free hens were randomly assigned to 1 of 4 treatments in 2 (two dietary Fe level) × 2 (Salmonella-inoculation or -noninoculation) factorial assignment. After feeding a basal diet supplemented with 60 (adequate, control) or 300 mg Fe/kg (high-Fe) for 4 weeks, 59-week-old Salmonella-free hens were orally inoculated with 5 × 107 colony-forming units of Salmonella Typhimurium (infection) or PBS (vehicle). Blood, spleen, and liver samples (n = 8) were collected at 14 days post-inoculation to determine Fe concentration and Fe transporters expression. Salmonella infection decreased (P < 0.05) hematocrit, serum Fe concentration, and splenic Fe concentration regardless of high-Fe or control hens, whereas increased (P < 0.05) Fe centration in the livers of high-Fe-treated hens. High dietary Fe increased hematocrit and serum Fe concentration, but did not affect (P = 0.11) splenic Fe concentration in Salmonella-infected hens. Salmonella infection did not influence (P = 0.31) liver Fe centration in control hens, but increased (P = 0.04) it in high-Fe-treated hens. High dietary Fe decreased (P < 0.01) the mRNA abundance of divalent metal transporter 1 and transferrin receptor, but increased (P < 0.02) ferroportin-1 (FPN1) mRNA and protein in the spleens and the livers regardless of Salmonella-infected or vehicle hens. Salmonella infection increased (P < 0.02) FPN1 mRNA and protein expression in the spleens, but did not influence its expression in the livers. These results suggested Salmonella infection and high dietary Fe differently influence the Fe distribution in the spleen and the liver of Salmonella-infected hens.