Thyroid Hormone, Thyroid Hormone Metabolites and Mast Cells: A Less Explored Issue

Area of Science:

• Neuroscience
• Immunology
• Endocrinology

Background:

• Mast cells are key immune cells in the brain, located at the blood-brain barrier (BBB) and involved in neuroinflammation.
• Brain mast cells store histamine and other mediators, influencing glial cell-neuron communication.
• Thyroid hormones (T3) and their metabolites are present in mast cells, suggesting bidirectional communication.

Purpose of the Study:

• To explore the role of mast cells in neuroendocrine pathways.
• To investigate the connection between thyroid function and mast cell activity.
• To highlight the potential role of mast cell histamine in linking the thyroid and nervous systems.

Main Methods:

• Review of existing pharmacological and experimental evidence.
• Analysis of novel findings on endogenous thyroid hormone metabolites.
• Hypothesizing a novel neuroendocrine pathway involving mast cells.

Main Results:

• Thyroid hormone metabolites (3,5-T2, T1AM, TA1) are found in mast cells and increase during inflammation.
• These metabolites, like T3, can induce neuroprotective effects, itch, and hyperalgesia.
• Their rapid action suggests they trigger histamine release from mast cells.

Conclusions:

• Mast cell histamine may act as a crucial link in a novel neuroendocrine pathway.
• This pathway connects the thyroid system with mast cells and potentially the brain.
• Further research is warranted to elucidate this thyroid-mast cell-brain axis.