Physiological implications of NTBI uptake by T lymphocytes

Area of Science:

• Hematology
• Cell Biology
• Toxicology

Background:

• Non-transferrin-bound iron (NTBI) contributes to organ toxicity in iron overload disorders.
• NTBI is preferentially cleared by the liver and myocardium, key targets in iron overload.
• Previous studies indicated T lymphocytes uptake NTBI in vitro.

Purpose of the Study:

• To investigate if the T lymphocyte pool acts as a significant NTBI storage compartment.
• To determine if T lymphocytes modify NTBI deposition in target organs.
• To elucidate the role of T lymphocytes in systemic iron homeostasis and protection against iron toxicity.

Main Methods:

• Assessed NTBI uptake by human T lymphocytes in vitro.
• Analyzed ferritin and ferroportin expression changes in T lymphocytes post-NTBI uptake.
• Utilized a T lymphocyte-deficient mouse model (Foxn1nu) to study iron accumulation patterns.
• Investigated the effect of T lymphocyte reconstitution via adoptive transfer in mice.

Main Results:

• NTBI uptake by T lymphocytes upregulates ferritin and ferroportin via an IRE-dependent mechanism.
• Hepcidin-mediated ferroportin modulation controls NTBI retention in T lymphocytes.
• T lymphocyte-deficient mice showed increased liver and pancreas iron accumulation.
• Reconstitution with T lymphocytes prevented NTBI accumulation in the liver and spleen.

Conclusions:

• T lymphocytes function as a critical circulating NTBI storage compartment.
• This T lymphocyte-mediated NTBI storage is physiologically relevant in modifying tissue iron overload.
• T lymphocytes play a protective role against systemic iron toxicity by managing NTBI.