Blocking complement with small antibodies

Eva Struijf

Unwanted complement activation is the root cause of many serious inflammatory diseases and there is an urgent medical need to develop more effective complement inhibitors. With this proposal we aim to develop antibodies targeting neoepitopes present in C5 convertase enzymes. The fact that these multi-molecular complexes are exclusively formed on cell surfaces makes them ideal targets for effective therapeutic inhibition. Using newly developed technologies to generate C5 convertases in purified forms, we here propose to generate llama-derived single domain antibodies (VHH) against C5 convertases. Since VHHs are small and have high targeting precision they are ideal to specifically target conformation specific neoepitopes. Via chemical labelling we will form C5 convertases on cell surfaces that are amenable for immunization of llamas. Following immunization, VHH antibodies will be selected via a combination of phage display, smart binding selection procedures coupled to functional inhibition studies. Finally, we will perform mode of action studies (in vitro) and determine the in vivo activity of VHHs in animal models of inflammation. We will use biochemical and structural approaches to elucidate the precise molecular mechanisms of VHHs targeting C5 convertases. Altogether this proposal presents an innovative approach to develop novel complement inhibitory therapies and will lead to new strategies to interfere with undesired complement activation during inflammatory processes.