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Staphylococcus aureus Growth using Human Hemoglobin as an Iron Source
Published on: February 7, 2013
Candidozyma auris utilizes transferrin, but not heme-bound iron for in vivo virulence
Abstract:
Candidozyma auris (C. auris) is an emerging multidrug-resistant fungal pathogen, and its dissemination to the bloodstream and deep-seated organs is associated with high mortality. The limited antifungal armory and pipelines against C. auris pose a major challenge in disease management. Addressing this threat requires a deeper understanding of fungal virulence mechanisms that promote persistence and of host factors that drive susceptibility. Previous in vitro studies showed that iron enhances C. auris resistance to azoles and echinocandins, whereas iron chelation mitigates this effect. Here, we demonstrate that C. auris does not utilize cell-free heme or induce hemolysis but instead extracts and uses iron from transferrin to support growth and virulence. Deletion of the SIT1 siderophore transporter in C. auris attenuated fungal growth and reduced renal injury, while increased transferrin-iron saturation worsened disease outcomes in immunocompetent mice, highlighting the importance of transferrin-bound iron uptake. Mechanistically, C. auris exploits transferrin-bound iron to enhance ergosterol biosynthesis and activate antioxidant defenses, promoting resistance to neutrophil- and caspofungin-mediated killing. These findings identify elevated transferrin saturation as a novel host susceptibility risk factor for disseminated C. auris infection and reveal how iron availability reshapes fungal physiology to drive infection persistence.
Insights
Candida auris uses host transferrin-bound iron for growth and virulence, increasing infection severity. Targeting iron uptake may offer new strategies against this multidrug-resistant fungus.
Area of Science:
- Mycology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Candida auris is a multidrug-resistant fungus causing life-threatening bloodstream infections.
- Limited treatment options and understanding of virulence mechanisms hinder effective disease management.
- Previous studies suggested iron influences C. auris antifungal resistance.
Purpose of the Study:
- To investigate how C. auris acquires and utilizes iron.
- To determine the role of transferrin-bound iron in C. auris pathogenesis.
- To identify host factors influencing susceptibility to C. auris infection.
Main Methods:
- Investigated C. auris iron acquisition mechanisms, including heme utilization and transferrin uptake.
- Generated a C. auris mutant lacking the SIT1 siderophore transporter.
- Assessed the impact of iron availability and SIT1 deletion on fungal growth and virulence in a murine model.
- Analyzed ergosterol biosynthesis and antioxidant defenses in response to iron.
Main Results:
- C. auris utilizes transferrin-bound iron, not cell-free heme, for growth and virulence.
- Deletion of SIT1 attenuated fungal growth and reduced kidney injury in mice.
- Increased transferrin saturation worsened disease outcomes in immunocompetent mice.
- Iron acquisition enhances ergosterol biosynthesis and antioxidant defenses, promoting resistance to killing.
Conclusions:
- Transferrin-bound iron is crucial for C. auris virulence and persistence.
- Elevated transferrin saturation is a novel host risk factor for disseminated C. auris infections.
- Understanding iron metabolism in C. auris provides insights into fungal pathogenesis and potential therapeutic targets.
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