Immune-enhancing effects of glucocorticoids in response to day–night cycles and stress

Environmental cues can trigger the production of glucocorticoids (GCs), which may enhance adaptive immune responses.

• Glucocorticoids are known for their anti-inflammatory effects, but recent findings indicate they can also have pro-inflammatory roles.
• The daily variation of GCs influences the expression of specific receptors in T cells, promoting their movement into lymphoid organs during active phases.
• This movement of T cells at the active phase boosts their priming against bacterial infections and increases the production of effector CD8 T cells and antibodies.
• Moderate stress-induced GCs facilitate the migration of memory CD8 T cells to the bone marrow, aiding in their maintenance and responsiveness.
• In contrast, high levels of GCs due to strong stress may lead to chronic inflammation and autoimmunity, potentially through the promotion of Th17 cell differentiation.
• The dual effects of GCs may play a critical role in balancing normal immune responses and the risk of infections and inflammatory diseases.

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