Ferritin H deficiency deteriorates cellular iron handling and worsens Salmonella typhimurium infection by triggering hyperinflammation
David Haschka, Piotr Tymoszuk, Verena Petzer, Richard Hilbe, Simon Heeke, Stefanie Dichtl, Sergej Skvortsov, Egon Demetz, Sylvia Berger, Markus Seifert, Anna-Maria Mitterstiller, Patrizia Moser, Dirk Bumann, Manfred Nairz, Igor Theurl, Guenter Weiss
David Haschka, Piotr Tymoszuk, Verena Petzer, Richard Hilbe, Simon Heeke, Stefanie Dichtl, Sergej Skvortsov, Egon Demetz, Sylvia Berger, Markus Seifert, Anna-Maria Mitterstiller, Patrizia Moser, Dirk Bumann, Manfred Nairz, Igor Theurl, Guenter Weiss
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Research Article Immunology Infectious disease

Ferritin H deficiency deteriorates cellular iron handling and worsens Salmonella typhimurium infection by triggering hyperinflammation

Abstract

Iron is an essential nutrient for mammals as well as for pathogens. Inflammation-driven changes in systemic and cellular iron homeostasis are central for host-mediated antimicrobial strategies. Here, we studied the role of the iron storage protein ferritin H (FTH) for the control of infections with the intracellular pathogen Salmonella enterica serovar Typhimurium by macrophages. Mice lacking FTH in the myeloid lineage (LysM-Cre+/+Fthfl/fl mice) displayed impaired iron storage capacities in the tissue leukocyte compartment, increased levels of labile iron in macrophages, and an accelerated macrophage-mediated iron turnover. While under steady-state conditions, LysM-Cre+/+Fth+/+ and LysM-Cre+/+Fthfl/fl animals showed comparable susceptibility to Salmonella infection, i.v. iron supplementation drastically shortened survival of LysM-Cre+/+Fthfl/fl mice. Mechanistically, these animals displayed increased bacterial burden, which contributed to uncontrolled triggering of NF-κB and inflammasome signaling and development of cytokine storm and death. Importantly, pharmacologic inhibition of the inflammasome and IL-1β pathways reduced cytokine levels and mortality and partly restored infection control in iron-treated ferritin-deficient mice. These findings uncover incompletely characterized roles of ferritin and cellular iron turnover in myeloid cells in controlling bacterial spread and for modulating NF-κB and inflammasome-mediated cytokine activation, which may be of vital importance in iron-overloaded individuals suffering from severe infections and sepsis.

Authors

David Haschka, Piotr Tymoszuk, Verena Petzer, Richard Hilbe, Simon Heeke, Stefanie Dichtl, Sergej Skvortsov, Egon Demetz, Sylvia Berger, Markus Seifert, Anna-Maria Mitterstiller, Patrizia Moser, Dirk Bumann, Manfred Nairz, Igor Theurl, Guenter Weiss

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Figure 3

S. Typhimurium triggers unrestrained expression of proinflammatory NF-κB targets in iron-loaded FthΔ/Δ mice.

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S. Typhimurium triggers unrestrained expression of proinflammatory NF-κ...
Fthfl/fl (Fth+/+) and LysM-Cre Fthfl/fl (FthΔ/Δ) mice were i.v. administered PBS or iron isomaltoside (2 mg elementary Fe per animal) and infected 3 days later with 500 CFU GFP-expressing S. Typhimurium (STG) (n = 3 mice per group). Twelve hours after infection, total spleen RNA was isolated and subjected to a whole transcriptome measurement with gene microarrays. Genes significantly downregulated (PANOVA iron/genotype < 0.05 and estimateiron/genotype < -1.5, n = 893 genes) and upregulated (PANOVA iron/genotype < 0.05 and estimateiron/genotype > 1.5, n = 271 genes) were identified by 2-way ANOVA and linear regression as described in Methods and Supplemental Figure 5. For a list of significant genes with ANOVA P values and regression estimates, see Supplemental Table 1. (A and B) GO term enrichment analysis for genes significantly downregulated (A) and upregulated (B) by the iron/genotype interaction. Significant GO terms are highlighted in blue and red, respectively (downregulated genes: n = 10 significant GO terms, upregulated genes: n = 31 significant GO terms), 10 most significantly enriched GO terms are labeled with their names. For full results of GO term enrichment analysis, see Supplemental Tables 2 and 3. (C and D) Heatmap representation of normalized gene expression values (z score) for genes assigned to selected significantly enriched GO terms. (C) Significantly downregulated genes.(D) Significantly upregulated genes. Color scale corresponds to normalized expression. (E and F) Transcription factor (TF) binding site enrichment analysis for genes significantly downregulated (E) and upregulated (F) by the iron/genotype interaction. For each TF-binding motif, the Benjamini-Hochberg-corrected P value and fold enrichment are plotted. Significant TF-binding motifs are highlighted in blue and red (downregulated genes: n = 35, upregulated genes: n = 5 significant TF binding motifs), 10 most significantly enriched TF-binding motifs are labeled with their names.