Early-Life Iron Status Modulates Metabolomics Profiles of Plasma and Cerebrospinal Fluid in a Piglet Model

The study aims to determine the impact of iron status on plasma and cerebrospinal fluid (CSF) metabolites in a piglet model. On postnatal day (PD) 1, 30 crossbred piglets (15 male/female) were blocked by sex and randomized to treatments by receiving no (N), low (L) or high (H) dose of iron supplement during pre- (PD1–21) and post-weaning period (PD22–35). Pigs in N, L, and H group orally received 0, 1, and 30 mg iron/(kg BW· d) as ferrous sulfate solution pre-weaning and were fed a solid diet containing 30, 125, and 1000 mg iron/kg post-weaning, respectively. Concentration of iron in colon content, liver and lung were determined using atomic absorption spectrophotometry. Plasma samples from PD21 and PD35 and CSF samples from PD35 were analyzed for ferritin using ELISA and untargeted metabolomics using gas chromatography coupled with time-of-flight mass spectrometry. Hemoglobin content of N pigs dropped below 11 g/dL on PD14 and decreased to the lowest level (8.2 ± 0.5 g/dL) on PD35, suggesting deteriorating iron deficiency. In contrast, H pigs had iron overload in liver (6 – 7 folds greater compared to L and N group; P < 0.05). Iron content in lung, spleen and colon content were also greater in H than L and N (P < 0.05). Plasma ferritin was higher on PD35 compared to PD21 (P < 0.01), but was not affected by treatment. In contrast, CSF ferritin tended to be higher in H (6.4 ± 0.9 g/L) and L (6.8 ± 0.8 g/L) than that in N group (3.9 ± 0.5 g/L; P < 0.10). In CSF, 24 metabolites were altered (FDR < 0.10) by iron in a dose-dependent manner. Pathway analysis underscored phenylalanine metabolism and biosynthesis of unsaturated fatty acids (P < 0.05). Iron had no effect on any plasma metabolite on PD 21 (FDR ≥ 0.10), but dose-dependently changed 24 metabolites on PD35 (FDR < 0.10). Six metabolites decreased with the increase of iron, while opposite pattern was observed in the other 18 metabolites. There was significant enrichment in phenylalanine metabolism, arginine biosynthesis, and pentose and glucoronate interconversions (P < 0.05). Our study suggests strong implication of dietary iron in systemic and brain metabolism in early postnatal life in a piglet model. NIFA Hatch/Multistate Research Fund.