Intravenous ferric carboxymaltose and ferric derisomaltose alter the intestinal microbiome in female iron-deficient anemic mice

Abstract

Iron deficiency anemia (IDA) is a leading global health concern affecting approximately 30% of the population. Treatment for IDA consists of replenishment of iron stores, either by oral or intravenous (IV) supplementation. There is a complex bidirectional interplay between the gut microbiota, the host's iron status, and dietary iron availability. Dietary iron deficiency and supplementation can influence the gut microbiome; however, the effect of IV iron on the gut microbiome is unknown. We studied how commonly used IV iron preparations, ferric carboxymaltose (FCM) and ferric derisomaltose (FDI), affected the gut microbiome in female iron-deficient anemic mice. At the phylum level, vehicle-treated mice showed an expansion in Verrucomicrobia, mostly because of the increased abundance of Akkermansia muciniphila, along with contraction in Firmicutes, resulting in a lower Firmicutes/Bacteroidetes ratio (indicator of dysbiosis). Treatment with either FCM or FDI restored the microbiome such that Firmicutes and Bacteroidetes were the dominant phyla. Interestingly, the phyla Proteobacteria and several members of Bacteroidetes (e.g., Alistipes) were expanded in mice treated with FCM compared with those treated with FDI. In contrast, several Clostridia class members were expanded in mice treated with FDI compared with FCM (e.g., Dorea spp., Eubacterium). Our data demonstrate that IV iron increases gut microbiome diversity independently of the iron preparation used; however, differences exist between FCM and FDI treatments. In conclusion, replenishing iron stores with IV iron preparations in clinical conditions, such as inflammatory bowel disease or chronic kidney disease, could affect gut microbiome composition and consequently contribute to an altered disease outcome.

Keywords: anemia; chronic kidney disease; inflammatory bowel disease; iron; microbiome.

Figure 1. FCM and FDI administration correct iron deficiency anemia

At baseline, prior to switching from normal chow to a low iron diet, no differences were observed in hematocrit (A) or red blood cell count (RBC; B) between the vehicle, FCM, and FDI treatment groups. Bleeding-induced anemia, as seen by reduced hematocrit (A) and RBC (B), to similar levels in all groups. After 14 days, mice treated with FCM and FDI showed increases in their hematocrit (A) and RBC (B), whereas vehicle-treated mice remained anemic with low hematocrit (A) and further decreased RBC (B). Data are expressed as mean±SEM and were analyzed by repeated measures two-way ANOVA followed by Tukey’s multiple comparison test. *P<0.05, vs. vehicle, same condition; ^#P<0.05, vs. previous condition in the same treatment group. N = 8–9/group.

Figure 2. β-Diversity principal coordinates analysis (PCoA) in vehicle-, FCM-, and FDI-treated mice

Microbiota composition was significantly different among the three treatment groups (n = 8–9/group) according to three different measures of beta diversity: (A) Bray–Curtis, (B) Jaccard, and (C) Gower distances (PERMANOVA P-value displayed per panel). The percentage of variation explained per PCoA axis is displayed with the title axis.

Figure 3. Differential α-diversity levels in vehicle-, FCM- and FDI-treated mice

α-Diversity analysis suggests significant differences in otus (A) and chao1 (B) richness estimators and Shannon diversity (C) between vehicle-treated mice (n=8) and FCM- (n=9) or FDI-treated (n=8) mice (Mann–Whitney U-test). *P<0.05 vs. vehicle; ^†P<0.05 vs. FCM.

Figure 4. Taxonomic composition distribution histograms of gut microbiota from vehicle-, FCM-, and FDI-treated mice

Composition of gut microbiota at the phylum (A), class (B), order (C), family (D), genus (E), and species (F) levels in vehicle- (n=8), FCM- (n=9), and FDI-treated (n=8) mice.

Figure 5. LEfSe analysis of gut microbiota from vehicle- and FCM-treated mice

Cladograms (A) show the microbial clades with the greatest differences in the abundance of microbiota between vehicle- and FCM-treated mice. LDA scores (B) of microbial clades differing in abundance between vehicle- and FCM-treated mice (LDA score >0.1 and significance of P<0.05, determined using Kruskal–Wallis test); N=8–9/genotype.

Figure 6. LEfSe analysis of gut microbiota from vehicle- and FDI-treated mice

Cladograms (A) show the microbial clades with the greatest differences in the abundance of microbiota between vehicle- and FDI-treated mice. LDA scores (B) of microbial clades differing in abundance between vehicle- and FDI-treated mice (LDA score >0.1 and significance of P<0.05, determined using the Kruskal–Wallis test); N=8–9/genotype.

Figure 7. LEfSe analysis of gut microbiota from FCM- and FDI-treated mice

Cladograms (A) show the microbial clades with the greatest differences in abundance in the microbiota from FCM- and FDI-treated mice. LDA scores (B) of microbial clades differing in abundance between FCM- and FDI-treated mice (LDA score >0.1 and significance of P<0.05, determined using the Kruskal–Wallis test); N=8–9/genotype.