Molecular Recalibration of PD-1+ Antigen-Specific T Cells from Blood and Liver

Area of Science:

• Immunology
• Oncology
• Gene Therapy

Background:

• Checkpoint inhibitors and adoptive cell therapy show promise for solid cancers like HBV-related HCC but have limitations.
• T cell exhaustion, characterized by PD-1 upregulation, hinders effective anti-tumor immunity.

Purpose of the Study:

• To genetically reprogram T cells targeting HBV-associated HCC viral antigens to overcome exhaustion by down-modulating PD-1.
• To evaluate the functional consequences of PD-1 knockdown on antitumor immunity in a relevant microenvironment.

Main Methods:

• Developed a novel lentiviral transduction protocol for shRNA knockdown of PD-1 in antigen-specific CD8 T cells.
• Utilized a 3D microdevice mimicking the liver microenvironment to assess T cell function and hepatoma cell killing.
• Analyzed T cell responses, including PD-1 expression, effector function, senescence, and co-inhibitory pathway engagement.

Main Results:

• Lentiviral-mediated PD-1 knockdown significantly reduced PD-1 expression in antigen-specific CD8 T cells.
• PD-1 knockdown enhanced T cell effector function and promoted killing of hepatoma cells in a 3D liver microenvironment model.
• Repetitive stimulation of PD-1 knockdown T cells led to T cell senescence and induction of alternative co-inhibitory pathways.

Conclusions:

• Demonstrated proof of principle for functional genetic editing of T cells targeting HBV-associated HCC.
• PD-1 knockdown enhances immediate tumor cell killing but is limited by compensatory mechanisms and senescence upon sustained stimulation.