Opto-CD28-REACT: optogenetic co-stimulatory receptor activation on non-engineered human T cells

Area of Science:

• Immunology
• Synthetic Biology
• Optogenetics

Background:

• T-cell activation requires T-cell receptor (TCR) and co-stimulatory signals, primarily from CD28.
• Current methods for T-cell manipulation often involve genetic modification, limiting applications.
• Precise control over T-cell signaling pathways is crucial for understanding immune responses and developing therapies.

Purpose of the Study:

• To develop a non-genetic, optogenetic platform for reversible and tunable activation of human T cells.
• To investigate the synergistic effects of optogenetically controlled TCR and CD28 signaling.
• To provide a tool for dissecting T-cell activation dynamics and advancing synthetic immunology.

Main Methods:

• Engineered opto-CD28-REACT, a recombinant protein binding CD28 and linking it to light-sensitive PIF6.
• Utilized red light (630 nm) to induce PIF6 binding to PhyB beads, triggering CD28 signaling.
• Employed far-red light (780 nm) for rapid attenuation of the signaling pathway.
• Combined opto-CD28-REACT with opto-CD3ϵ-REACT for simultaneous optical control of TCR and CD28.

Main Results:

• Opto-CD28-REACT and opto-CD3ϵ-REACT induced light-dependent T-cell activation in Jurkat and primary human T cells.
• Co-stimulation via opto-REACT systems promoted ERK phosphorylation, CD69/CD25 upregulation, IL-2 secretion, and T-cell proliferation.
• Achieved T-cell activation levels comparable to conventional antibody-mediated stimulation.
• Demonstrated reversible and tunable control over T-cell signaling using light.

Conclusions:

• The opto-REACT platform offers precise optical control over T-cell activation without genetic modification.
• This system provides a powerful tool for studying T-cell signaling and immune regulation.
• Enables new avenues in synthetic immunology and the development of light-controlled immunotherapies.