AI Summary
The article discusses the development of novel designer IL2 mutations for clinical use. The researchers aimed to improve specificity for Tregs or CD8 T cells while maintaining bioactivity and production capacity. By considering bound and unbound structures, they addressed common issues with IL2 mutations. Specifically, they designed a block between IL2 and IL2RB that moves after IL2 binds IL2RA, allowing the full trimer to form for optimal signal. Additionally, they identified and changed aggregation-prone regions to be aggregation-resistant, resulting in more specific, cheaper, and easier to produce IL2 muteins. The research highlights the importance of considering production, aggregation, and bioactivity when engineering proteins for therapeutic use.
We have a new pre-print out, on novel designer IL2 mutations!
IL2 is a powerful immunomodulator, but the dual roles make it complex to use, and many designer mutations reduce bioactivity or result in poor production. This makes it much harder to move these muteins to the clinic.
Rob van der Kant, Joost Schymkowitz and Frederic Rousseau from the VIB Switch lab took up the challenge of designing new IL2 mutants that not only improve the specificity for Tregs or CD8 T cells, but also maintain bioactivity and actually improve production capacity. They sent the designs over to us to test!
Great work from Amy Dashwood screened these mutations designs in vitro, with in vivo testing by Ntombizodwa Makuyana resulting in a set of mouse and human IL2 muteins with the desired biological properties. In particular we solve some of the common issues with IL2 muteins by considering the bound and unbound structures. For example, to make IL2 specific for Tregs, the approach is to allow binding to IL2RA, the high affinity receptor sub-unit used by Tregs, while block binding to the IL2RB used by CD8 T cells. The problem is that Tregs also need the full IL2RA-IL2RB-IL2RG trimer to assemble for optimal signal. So the typical Treg mutein is more specific, but also has poorer bioactivity. We solved this by creating a block between IL2 and IL2RB that moves out of the way after IL2 binds IL2RA, allowing the full trimer to form. These muteins are not only superior to the original IL2 in terms of cellular specificity, but by removing the aggregation-prone regions. By identifiying the aggregation gateway residues and changing them to be aggregation-resistant, we can further improve these muteins by making them aggregation resistance. The net effect is that the IL2 muteins we made are more specific for either Tregs or CD8 T cells, and will also be cheaper and easier to produce – the perfect combo for biologic drugs!
Our take-home message: if you are engineering proteins for therapeutic use, remember to take into account production, aggregation and bioactivity. These factors count when it comes to making a drug!
Take a look at the full paper on BioRxiv.