Azithromycin suppresses CD4(+) T-cell activation by direct modulation of mTOR activity

Area of Science:

• Immunology
• Pharmacology
• Cell Biology

Background:

• Advanced macrolides, including azithromycin (AZM) and clarithromycin (CLM), possess known immunomodulatory properties.
• The specific impact of these macrolides on CD4(+) T-cell activation requires further investigation.

Purpose of the Study:

• To evaluate the in vitro effects of AZM and CLM on CD4(+) T-cell activation and function.
• To elucidate the molecular mechanisms underlying the immunomodulatory actions of these macrolides.

Main Methods:

• CD4(+) T-cells were stimulated with anti-CD3/anti-CD28 antibodies in the presence of varying concentrations of AZM or CLM.
• Assessed cell proliferation, cytokine secretion, cell viability, and intracellular signaling pathways (mTOR).
• Utilized techniques including FACS analysis, immunoblotting, and in vitro kinase assays.

Main Results:

• AZM demonstrated dose-dependent inhibition of CD4(+) T-cell proliferation and cytokine secretion.
• High concentrations of CLM (40 mg/L) also suppressed T-cell functions.
• AZM was found to inhibit mTOR activity, reducing S6 ribosomal protein phosphorylation, an effect also seen with 40 mg/L CLM.

Conclusions:

• Azithromycin and, to a lesser extent, clarithromycin exhibit immunosuppressive effects on CD4(+) T-cells by inhibiting mTOR activity.
• These findings suggest potential clinical implications for macrolide use, particularly in contexts requiring immune modulation.