The 5-HT3 receptor antagonist tropisetron inhibits T cell activation by targeting the calcineurin pathway

Area of Science:

• Immunology
• Pharmacology
• Molecular Biology

Background:

• T cells are crucial in inflammatory diseases.
• Tropisetron, a serotonin type 3 receptor antagonist, has potential anti-inflammatory applications.
• Understanding tropisetron's mechanism in T cells is key for therapeutic development.

Purpose of the Study:

• To evaluate the immunosuppressive activity of tropisetron on human T cell activation.
• To elucidate the molecular mechanisms underlying tropisetron's effects on T cell signaling pathways.
• To identify potential therapeutic targets for tropisetron in inflammatory conditions.

Main Methods:

• Investigated tropisetron's effects on T cell receptor (TCR)-mediated activation.
• Assessed IL-2 gene transcription and synthesis in stimulated T cells.
• Analyzed DNA binding and transcriptional activity of NF-κB, NFAT, and AP-1 in Jurkat T cells.
• Utilized calcineurin overexpression to identify molecular targets.

Main Results:

• Tropisetron potently inhibited early and late TCR-mediated T cell activation events.
• Tropisetron specifically suppressed IL-2 gene transcription and synthesis.
• Tropisetron inhibited DNA binding and transcriptional activity of NFAT and AP-1.
• Tropisetron inhibited PMA/ionomycin-induced NF-κB activation but not TNFα-mediated activation.
• Calcineurin was identified as a potential molecular target.

Conclusions:

• Tropisetron exhibits significant immunosuppressive activity on human T cells, independent of serotonin receptor signaling.
• Tropisetron's inhibition of NFAT and AP-1 transcription factors contributes to its anti-inflammatory effects.
• Calcineurin may be a key target for tropisetron's immunosuppressive action.
• These findings support tropisetron's potential for novel therapeutic strategies in inflammatory diseases.