Congratulations to Dan Osipovitch, graduate student in the PEMM program, who was one of four winners of the Graduate Poster Session held recently at the Top of the Hop! Enjoy your winnings, Dan! (Read on for a summary of Osipovitch’s poster.)
“Towards Better Protein Therapeutics: Reducing Immunogenicity”
Throughout history we have used small molecules to treat disease: pop an aspirin, take your antibiotic, gulp some NyQuil. But in more recent years, people have discovered the utility of enzymes as therapeutics. Unlike most small molecules, enzymes have the capability of chemically modifying a system—breaking bonds or putting bonds back together. Enzymes can detoxify poisons, eat the cell walls of bacteria and cause them to die, and specifically target cancer cells, to name a few functions. But if enzymes are so great, why hasn’t there been a complete revolution towards protein-based therapeutics?
Well, thousands of years of evolution are to blame. The immune system protects us from disease and foreign proteins. When a protein is injected into the blood stream, there is a cascade of events that lead to the recognition and removal of the protein. This causes therapeutic proteins/enzymes to be quickly degraded, killing any therapeutic potential they once had.
So what can we do to try to trick the immune system? We, the protein engineers, teamed up with computer scientists to try to tackle this problem; we hypothesize that if we can keep the immune system from seeing the therapeutic protein, no immunogenicity (immune response) will develop.
The computer scientists study our candidate enzyme and use various algorithms and databases to decide what regions on the protein (epitopes) will elicit an immune response. To do this, the algorithms decide how well epitopes interact with MHC II proteins—these are the proteins in antigen-presenting immune cells that display epitopes to the immune system.
If we can disrupt the interaction between the epitopes and the MHC IIs, then there is a much smaller chance for the immune system to see the proteins. Their algorithms then predict, using multiple sequence alignments, what mutations can be made to disrupt these interactions.
In the lab, we want to make sure that these mutations don’t harm the therapeutic potential of the enzyme. I use techniques of recombinant DNA/protein to develop and purify the mutant proteins. I can then do kinetic and thermodynamic studies to see how the mutations may have affected the therapeutic potential of the enzymes.
We then work with DartLab to test how these new enzymes stimulate the immune system. We are currently working on a protein called beta-lactamase that has potential anti-cancer uses and we have constructed and characterized a handful of mutants to test kinetics and thermodynamics. The immune studies are ongoing. In the future, we hope to move to high-throughput strategies to find the best possible mutants.
Our hope is to validate the algorithms and then be able to use them on a wide range of protein therapeutics. This work will hopefully help the huge and growing field of protein/enzyme based therapeutics. But, we must remain humble and realize we’re trying to trick that which has protected us for thousands of years—the immune system.
poster summary by Dan Osipovitch
photo by Erin O’Flaherty