Dual Impact of Iron Deficiency and Antibiotics on Host Metabolism: A Tissue-Level Analysis

<b>Background/Objectives</b>: Iron deficiency (ID) is a common nutritional deficiency in infancy and early childhood associated with increased risk of infection and increased likelihood of receiving antibiotic intervention. In the context of ID, antibiotics have been shown to exaggerate the growth impairments and negative impacts on metabolic health of ID itself. The objective of this research was to assess the tissue-level impact of antibiotics when provided during ID. <b>Methods</b>: ID was induced in piglets by withholding an iron dextran shot shortly after birth, and iron deficiency was maintained after weaning by providing an iron-deficient diet starting on postnatal day (PD) 25. Half of the ID piglets received a 3-day antibiotic course (ID + Abx) consisting of spectinomycin and gentamicin from PD34-36. The kidney, liver, skeletal muscle, and hippocampal metabolomes, as well as activity of proteins in the mTOR signaling pathway, were assessed on PD43. <b>Results</b>: While ID had minimal impacts on the liver, kidney, and skeletal muscle metabolomes, ID + Abx impaired energy metabolism and increased ketosis and oxidative stress in peripheral tissues. Hippocampal metabolites involved in neurotransmitter synthesis pathways were affected by ID and ID + Abx to a greater extent. Additionally, the activities of several proteins in the mTOR pathway were upregulated in the hippocampi of ID + Abx piglets compared to both ID and control piglets. Abx provided to iron-sufficient piglets had minimal effects on tissue metabolomes and did not alter the activity of proteins in the mTOR pathway. <b>Conclusions</b>: These results highlight that antibiotic treatment in ID alters metabolism in peripheral tissues and the developing hippocampus beyond those induced by ID alone. Considering that infants and children are develop rapidly, the combination of ID and antibiotics may have lasting impacts on neurodevelopment and cognition.