Human Oral Epithelial Cells Suppress T Cell Function via Prostaglandin E2 Secretion

Area of Science:

• Immunology
• Oral Biology
• Cellular Immunology

Background:

• The oral mucosa requires specialized immune responses to constant environmental stimuli.
• Human oral epithelial cells (OECs) were previously shown to suppress immune responses to bacteria.
• OECs reduce dendritic cell (DC) co-stimulatory molecule expression and cytokine release, impairing T cell activation.

Purpose of the Study:

• To further evaluate the immunosuppressive properties of OECs.
• To investigate the underlying molecular mechanisms of OEC-mediated immunosuppression.
• To determine if OEC immunosuppression can be modulated by external factors.

Main Methods:

• Co-culture of OECs with DCs and T cells.
• Analysis of T cell polarization (FoxP3 expression) and activation markers (T-bet/IFNγ).
• Investigation of signaling pathways including CD40/CD40L, CD58/CD2, PD-L1/PD-1, and prostaglandin E2 (PGE2) signaling.

Main Results:

• OECs suppressed T cell activation and IFNγ production at the transcriptional level, dependent on OEC:T cell ratio.
• OEC-mediated suppression was primarily dependent on prostaglandin E2 (PGE2) synthesis and its binding to EP2/EP4 receptors.
• OEC immunosuppression was reduced when OECs were stimulated with poly(I:C), mimicking viral infection.

Conclusions:

• OECs possess an intrinsic capacity to suppress T cell-mediated immune responses.
• Prostaglandin E2 (PGE2) is a key mediator of OEC-induced immunosuppression.
• OEC immunosuppressive function can be modulated, suggesting potential therapeutic targets for oral immune disorders.