Projects

FcγRIIIa has 98% sequence identity with FcγRIIIb and has been a known therapeutic target since the 1990s, yet has no commercially-available specific monoclonal antibodies. We have described Affimers (artificial non-antibody binding proteins) with different modes of action that inhibit the interaction between IgG and FcγRIIIa. These Affimers block the production of TNF by THP1 cells after stimulation with heat aggregated IgG (HAG), which they can also displace. To date these represent the most specific recognition proteins, but there is still room for improvement. We are currently developing enhancements to specificity and affinity, and optimising formats for potential therapeutic use.

FcγRIIa is an intriguing receptor. It is described as a ligand for IgG antibodies and pentraxins (serum amyloid P component and C-reactive protein), it is widely expressed on myeloid cells, is polymorphic in two positions of the ectodomain in some populations, and is capable of delivering activatory and inhibitory signals. Genetic associations between FCGR2A and infection and autoimmunity are complex. The gene sits across a segmental duplication boundary and is partly involved in genomic structural variation. We have collaborated with researchers working on a range of autoimmune disorders to describe FCGR2A associations and have conducted preliminary analysis on the polymorphic receptor variants to try to explain the functional effects underpinned by the genetics. We continue to develop our understanding of FcγRIIa variants on receptor function at the cellular level.

Reductionist biophysical protein interaction analyses (e.g. surface plasmon resonance - SPR) are good for measuring the molecular interactions between individual domains, but lack the complexity required to describe physiologically relevant interactions which often include oligomerisation, allostery and variable avidity. Traditionally the cellular analyses of more complex interactions involves crosslinking/fixation which "kills" the system, which in practice must be stopped at certain time points.

We believe that time is an important parameter in cellular systems and we are developing reproducible and parallel methods to report protein-protein interactions in living cells in real-time. Collaborations with industry (Ridgeview Instruments) and physicists at Leeds are enabling us to develop novel technology to measure protein-cell interactions, signalling outcomes and systems that we can use to test novel therapeutic candidates.