Cellular iron governs the host response to malaria

Area of Science:

• Immunology
• Parasitology
• Nutritional Science

Background:

• Malaria and iron deficiency are significant global health issues with overlapping prevalence.
• Iron deficiency anemia can offer some protection against malaria by hindering parasite growth, but also impairs immune function.
• The specific effects of host cell iron scarcity on immune cells beyond anemia in malaria are not well understood.

Purpose of the Study:

• To investigate the impact of limited cellular iron uptake on host immune responses and disease pathology during malaria infection.
• To elucidate the role of host cell iron availability in balancing malaria protection and pathology.

Main Methods:

• Utilized a transgenic mouse model (TfrcY20H/Y20H) with impaired transferrin receptor function, limiting cellular iron internalization.
• Infected mice with Plasmodium chabaudi chabaudi AS and monitored parasitemia, body weight, anemia, and immune cell function (proliferation, cytokine production).
• Assessed liver damage and parasite sequestration, and performed ex vivo iron supplementation experiments on immune cells.

Main Results:

• TfrcY20H/Y20H mice exhibited higher peak parasitemia and greater body weight loss compared to wild-type mice during malaria infection.
• Despite similar anemia trajectories, these mice showed impaired innate and adaptive immune responses, including reduced T cell and B cell proliferation and cytokine production.
• Cell-intrinsic iron deficiency in immune cells was confirmed by ex vivo iron supplementation restoring function.
• Notably, TfrcY20H/Y20H mice displayed reduced liver damage, characterized by decreased parasite sequestration and attenuated hepatic immune response.

Conclusions:

• Host cell iron scarcity during malaria infection suppresses immune responses, leading to increased parasite burdens.
• Despite immune suppression, limited cellular iron availability protects against excessive hepatic tissue damage.
• These findings reveal a complex role for iron in modulating the balance between protective immunity and malaria-induced pathology.