MRC Transition Support CSF David Owen

1) OVERARCHING AIMS

Microglia - cells of the immune system that live in the brain - contain a protein called TSPO. Drugs which target TSPO change microglial behaviour and protect nerve cells in animal models of neurodegenerative disease. However, the function of TSPO is unknown. Therefore, the aim of this project is to understand how TSPO protects nerve cells, and hence to pave the way for novel treatments of neurodegenerative disease.

Scientific Progress
I have set up an immunology laboratory and a facility to grow human microglia from stem cells (IPS cells). I then characterised the cells and showed they behave similarly to human microglia derived from patients undergoing biopsies and hence they are fit-for-purpose. We next identified which proteins TSPO associates with, which is a vital question when trying to understand the function of a protein. We also showed how removing TSPO from the cells affects their immune function.

Non-Scientific Progress
Chair of NW London IVIG panel (IVIG is a lifesaving but scares resource).
Invited to chair NW London Integrated GP Formulary Panel (makes decisions covering 2 million people).
Paid scientific advisory board member of Nodthera and INmune Bio.
Rising Star Award (ONO Pharmaceuticals - including a small grant (£91,000)).
Invited to speak (expenses paid) at 4 international (highly reputable) conferences .

We have:

Set up an immunology laboratory and dedicated iPSC facility
Derived microglia-like cells from iPSC cultures
Characterised the bioenergetics profile
Demonstrated equivalence with primary microglia
Identified the effect TSPO KO has on microglial bioenergetics and TNF-a production
Identified novel TSPO binding partners

We now need to demonstrate the molecular mechanism underlying how the interaction with the binding partners mediates the effect of TSPO on microglial bioenergetics and microglial immunophenotype.

Aim 1
Complete the immunological characterisation of TSPO KO cells and show that expression of wildtype TSPO in TSPO KO cell lines rescues the immune phenotype.

Aim 2
From our newly discovered binding partners, we are initially prioritising MTCH2 (see CfS to explain why). We will test the hypothesis that the effect of TSPO KO on the immunophenotype is mediated by the increased leak currents across the mitochondrial inner membrane, itself mediated by downregulation of MTCH2. We will therefore overexpress MTCH2 in TSPO KO cells to determine if this partially rescues both the bioenergetic changes (associated with the increased leak) and the immunophenotype. We expect that the changes in mitochondrial energetics, in general or by overexpression of MTCH2, mediate the immunomodulatory effects of TSPO.

Modulation of the immune phenotype by mitochondria is likely to involve a molecular complex that interacts with TSPO. We will therefore also focus on HK1, as another player in this paradigm (again, see CfS to explain why). We will test the hypothesis that HK1 activity is directly reduced in TSPO KO, and that expression of wildtype TSPO in the TSPO KO restores HK1 activity and rescues the immune phenotype. If so, we will test the hypothesis that the effect of TSPO KO on the immunophenotype is mediated by a reduction in HK1 activity. We will therefore overexpress HK1 in TSPO KO cells to determine if this partially rescues the phenotype.

The primary purpose of the project is to better understand a potential novel therapeutic pathway for modulation of microglial phenotype and therefore a potential slowing of neurodegeneration. I will work closely with staff of Imperial Innovations to secure patent protection for therapeutic concepts where possible. With success of this project, I would look forward to subsequent new funding for experimental medicine proof of concept studies and ultimate development of a medicine. As highlighted in the application, there are no marketed modern drugs that primarily modulate the microglia for direct impact on this compartmentalized brain inflammation. Successful validation of TSPO as a target will immediately identify a broad range of chemical structures from which an optimised therapeutic candidate could be developed. While the chemical space is broadly covered by patents, chemical novelty is achievable, especially with exploitation of the human genetic variation in TSPO for screening and design, uses of which are covered broadly by a patent application that I have previously filed with Imperial (WO2012168697 A1).