Optimized expression and specific activity of IL-12 by directed molecular evolution.

Area of Science:

• Biotechnology
• Immunology
• Gene Therapy

Background:

• Recombinant human IL-12 (hIL-12) protein therapy shows promise for cancer treatment but is limited by toxic side effects.
• DNA delivery of IL-12 offers a potential alternative with reduced toxicity while maintaining anti-tumor effects.

Purpose of the Study:

• To develop a more potent and effective version of IL-12 using DNA shuffling and screening.
• To improve IL-12 expression and specific activity in human cells and T cells for enhanced therapeutic potential.

Main Methods:

• DNA shuffling and screening of mammalian genes encoding IL-12 subunits (p35 and p40).
• In vitro assays to compare the proliferation and Th1 differentiation activity of evolved IL-12 (EvIL-12) against native hIL-12.
• Analysis of EvIL-12 expression levels and heterodimer homogeneity in transfected human embryonic kidney cells.

Main Results:

• EvIL-12 demonstrated a 128-fold improvement in human T cell proliferation compared to native hIL-12 in initial screenings.
• Purified EvIL-12 protein showed a 10-fold increase in specific activity in T cell proliferation and Th1 differentiation assays.
• DNA shuffling led to at least a 10-fold increase in EvIL-12 expression and heterodimer homogeneity.

Conclusions:

• The enhanced expression and biological activity of EvIL-12 offer a promising alternative to hIL-12 protein therapy.
• EvIL-12 may improve the effectiveness of IL-12 gene-based vaccines and therapeutics with potentially fewer toxic side effects.
• Strategic amino acid substitutions in EvIL-12 likely facilitate improved heterodimer formation and expression.