Podoplanin negatively regulates CD4+ effector T cell responses.

Area of Science:

• Immunology
• Molecular Biology
• Autoimmunity

Background:

• Podoplanin (PDPN) is known for its role in lymphatic endothelial cells.
• Its function on effector T cells during autoimmune inflammation is largely unknown.

Purpose of the Study:

• To investigate the role of Podoplanin (PDPN) in T cell function and autoimmune diseases.
• To elucidate the molecular mechanisms by which PDPN influences T cell responses.

Main Methods:

• Generation of genetically modified mice with global, T cell-specific deletion, or overexpression of PDPN.
• Induction and assessment of experimental autoimmune encephalomyelitis (EAE) as a model for autoimmune inflammation.
• Transcriptional profiling of T cells to identify gene expression changes.

Main Results:

• Global PDPN deletion led to exaggerated T cell responses and spontaneous EAE.
• T cell-specific PDPN overexpression impaired IL-7-mediated T cell expansion and survival, reducing CNS inflammation.
• T cell-specific PDPN deletion exacerbated EAE with increased CD4+ T cell accumulation in the CNS.
• PDPN+ effector T cells showed increased expression of inhibitory receptors (e.g., PD-1, TIM-3) and decreased prosurvival factors (e.g., IL-7Rα).

Conclusions:

• Podoplanin (PDPN) acts as an inhibitory molecule on T cells.
• PDPN limits the long-term survival and maintenance of CD4+ effector T cells in target organs.
• PDPN contributes to tissue tolerance by regulating T cell responses in autoimmune settings.