Infantile Anemia and Iron Treatments Affect the Gut Microbiome of Young Rhesus Monkeys

The influence of iron deficiency anemia and iron treatments on the gut microbiome was evaluated in young rhesus monkeys. First, the hindgut bacterial profiles of 12 iron-deficient anemic infants were compared to those of 9 iron-sufficient infants at 6 months of age, a time when the risk of anemia is high due to rapid growth. After this screening, the anemic monkeys were treated with either parenteral or enteral iron. Seven monkeys were injected intramuscularly with iron dextran, the typical weekly treatment used in veterinary practice. Four other anemic infants were treated with a novel oral supplement daily: yeast genetically modified to express ferritin. Fecal specimens were analyzed using 16S ribosomal RNA (rRNA) gene amplicon sequencing. Bacterial species richness in anemic infants was not different from that of iron-sufficient infants, but beta diversity and LEfSe analyses of bacterial composition indicated that the microbiota profiles were associated with iron status. Both systemic and oral iron increased alpha and beta diversity metrics. The relative abundance of Ruminococcaceae and other Firmicutes shifted in the direction of an iron-sufficient host, but many different bacteria, including Mollicutes, Tenericutes, and Archaea, were also enriched. Collectively, the findings affirm the important influence of the host's iron status on commensal bacteria in the gut and concur with clinical concerns about the possibility of adverse consequences after iron supplementation in low-resource settings where children may be carriers of iron-responsive bacterial pathogens.