Ryan Brown

Doctoral Researcher
Physical Sciences of Imaging in the Biomedical Sciences CDT

Thesis project - "Design, Synthesis and Characterisation of CCL2 Constructs: Selective Delivery of Fluorophores to Monocytes"

Dr Sam Butterworth, School of Chemistry
Professor Robin May, School of Biosciences
Dr Iain Styles, School of Computer Science

This project utilises the chemokine, CCL2, to build a selective delivery platform to target disease-causing monocyte subsets. Monocytes are white blood cells which form part of the innate immune system and are primarily responsible for pathogen engulfment and antigen presentation towards members of the adaptive immune system. Monocytes have been identified in a number of diseases such as liver fibrosis, rheumatoid arthritis and can even be recruited by cancers leading to tumour-protection from the immune system through so-called Tumour-Associated Macrophages (TAMs) and Myeloid-Derived Suppressor Cells (MDSCs). Interestingly, many of these diseases are caused by specific subsets of monocytes which express high levels of the chemokine receptor CCR2. This project has developed CCL2 as a delivery vehicle such that these monocyte subsets can be selectively targeted for fluorophore delivery.

A series of CCL2 mutant sequences were conjugated with a range of fluorophores using click chemistry and these conjugates exhibited retained chemotactic function. This chemotaxis and internalisation of the ligand is CCR2-mediated and disease-causing monocyte subsets were also shown to be targeted with the fluorescent chemokines. Finally, fluorescence microsocpy demonstrated that physicochemical variations of the fluorophore and linker allowed the subcellular localisation of fluorophores to be modulated, post ligand-receptor internalisation.