The immunoreceptor TIGIT regulates antitumor and antiviral CD8(+) T cell effector function

Area of Science:

• Immunology
• Cancer Biology
• Virology

Background:

• Tumors create suppressive microenvironments that exhaust T cells via inhibitory receptors like PD-1.
• CD8(+) T cell exhaustion limits effective immune responses against cancer and chronic infections.

Purpose of the Study:

• To identify novel coinhibitory receptors that regulate CD8(+) T cell exhaustion in chronic immune responses.
• To investigate the role of TIGIT in antitumor immunity and chronic viral infections.
• To evaluate the therapeutic potential of targeting TIGIT in combination with PD-1 blockade.

Main Methods:

• Expression analysis of TIGIT on tumor-infiltrating T cells in human and murine models.
• In vivo studies using antibody coblockade of TIGIT and PD-L1 in cancer and chronic viral infection models.
• Assessment of CD8(+) T cell effector function and immune response.
• Investigation of the interaction between TIGIT and its costimulatory receptor CD226.

Main Results:

• TIGIT is highly expressed on tumor-infiltrating CD8(+) T cells, indicating its role in immune suppression.
• Antibody coblockade of TIGIT and PD-L1 synergistically enhanced CD8(+) T cell effector function.
• Combined blockade resulted in significant tumor clearance in cancer models and viral clearance in chronic viral infection models.
• Blockade of TIGIT's interaction with CD226 abrogated the synergistic therapeutic effect, highlighting the importance of this interaction.

Conclusions:

• TIGIT is a critical coinhibitory receptor that limits chronic CD8(+) T cell-dependent immune responses.
• Combined blockade of TIGIT and PD-L1 represents a promising therapeutic strategy for enhancing antitumor immunity and controlling chronic infections.
• The interaction between TIGIT and CD226 is crucial for regulating T cell responses and represents a key target for immunotherapy.