Glucocorticoid regulation of the mTORC1 pathway modulates CD4⁺ T cell responses during infection

Area of Science:

• Immunology
• Cellular Biology
• Pharmacology

Background:

• Conventional glucocorticoid (GC) therapy can suppress CD4+ T cell function, increasing susceptibility to opportunistic infections.
• Understanding the precise mechanisms of GC-induced immunomodulation in CD4+ T cells is crucial for mitigating adverse effects.

Purpose of the Study:

• To investigate how GCs modulate CD4+ T cell functionality during infection.
• To elucidate the role of the mechanistic target of rapamycin complex 1 (mTORC1) pathway in GC-mediated effects on CD4+ T cells.

Main Methods:

• Measurement of FOXP3, inflammatory cytokines, and phospho-S6 ribosomal protein in CD4+ T cells from patients on GC treatment.
• Utilizing Foxp3EGFP reporter mice to dynamically assess mTORC1 pathway activation and its correlation with CD4+ T cell function under GC influence.

Main Results:

• GCs induced a T regulatory (Treg) cell phenotype in CD4+ T cells by altering FOXP3 expression.
• GCs impaired the kinetics of the mTORC1 pathway, which correlated with changes in CD4+ T cell phenotype and function.
• Targeting the mTORC1 pathway modulated the GC-impaired immunoregulatory capacity of CD4+ T cells, enhancing Treg cell function.

Conclusions:

• A novel mTORC1-mediated mechanism contributes to CD4+ T cell immune responses during conventional GC treatment.
• Modulation of the mTORC1 pathway represents a potential therapeutic strategy to restore immune function compromised by GC therapy.