Development of Stable Chimeric IL-15 for Trans-Presentation by the Antigen Presenting Cells

Area of Science:

• Biotechnology
• Immunology
• Protein Engineering

Background:

• Interleukin-15 (IL-15) is crucial for vaccine adjuvants and cancer treatment but suffers from short half-life and poor bioavailability.
• Limited therapeutic efficacy of native IL-15 necessitates protein engineering for improved pharmacokinetic and pharmacodynamic properties.

Purpose of the Study:

• To engineer a chimeric IL-15 protein with enhanced stability and bioavailability for improved therapeutic potential.
• To evaluate the efficacy of the chimeric IL-15 in promoting antigen-specific memory CD8+ T cell responses.

Main Methods:

• Covalent linkage of IL-15 to an IgG2 Fc fragment to create a stable chimeric protein.
• Assessment of serum half-life, receptor binding affinity (IL-15Rβ), and biological activity in vitro and in vivo.
• Evaluation of chimeric IL-15's role in antigen-presenting cell (APC) mediated transpresentation to T cells.

Main Results:

• The chimeric IL-15 exhibited a 40-fold increase in serum half-life compared to native IL-15.
• The engineered protein maintained affinity for IL-15Rβ and formed stable dimers, enhancing proteolytic resistance.
• In vitro and in vivo studies confirmed chimeric IL-15's ability to induce IL-15 signaling and promote CD8+ T cell memory generation.

Conclusions:

• Engineered chimeric IL-15 demonstrates significantly improved pharmacokinetics and retains biological function.
• The chimeric protein acts as a super-agonist for memory CD8+ T cell responses, offering potential for enhanced cancer immunotherapy and vaccine development.
• Focused transpresentation by APCs contributes to the superior generation of antigen-specific memory T cells.