Nano-agents for the manipulation of innate immunity

In the first funding phase of SFB 1032 we developed RNA based nano agents that were modified with arachidonic acids using copper(I) catalysed click reactions in order to enable specific delivery of our nano agents into immune cells and neurons. In the second funding phase we further explored click chemistry for the development of dendrimeric nano agents able to detect cell proliferation. We synthesized mesoporous nano silica particles that were equipped with switchable carbonic anhydrase enzymes that were click modified with folate targeting units. These nano particles with switchable closing and opening devices and had tumour targeting functions were again constructed by click chemistry. In the second funding phase we also went into a new field with the aim to develop nano agents able to modulate the inert immune response.

In the third funding phase of SFB 1032 we now want to continue the development of immuno modulated nano agents. To this end we are planning to synthesize various cGAMP derivatives. These are cyclic adenosine and guanosine containing nucleotide structures that bind to the STING receptor in order to initiate an interferon response. Activation of this pathway leads to immune stimulation, which is important in the context of tumour immuno oncology. Inhibiting the pathway may be beneficial for the treatment of autoimmune diseases and for anti-aging research.
Based on the developments in the first and second funding phases we are now planning to develop cGAMP derivatives that are again modified with arachidonic acid using the copper(I) catalysed click reaction in order to create nano agents that can be specifically delivered into immune cells. This is particularly desired in the context of modulating T-cells activity against tumours. The nano agents are multifunctional. 1. They will be able to penetrate cells and in cells based on available proteases they will feature elements that contain 2. Specific trigger-groups are cleaved-off and lead in a cascade reaction to the liberation of the original cGAMP molecule. 3. In order to allow visualisation of the cell penetrating activity and to study distribution of the compounds in cells we are planning in addition to incorporate fluorescent substructures into cGAMP by specifically exchanging the guanine heterocycle with a thiophene containing heterocycle that allows in principle even two-photon excitation. The final idea developed in the proposal is to turn these nano agents into compounds able to downregulate the STING activation pathway.
This will be done by incorporating the nano agents into the PROTAC concept by linking an E2/E3 ligase ligand to the cGAMP nano agents via a polyethylene glycol tether. These ultimate goals of our research are planned to be able to enter cells. They are planned to have targeting properties to immune cells. They will feature the fragmentation properties able to liberate the cGAMP ligand now connected to the E2/E3 ligand. Upon binding of this unit to the cGAMP receptor the E2/E3 ligase complex will be dragged towards STING to initiate polyubiquitination and subsequent proteasomal degradation of the STING receptor. Cellular tracking of these multifunctional nano agents will be performed in the SFB 1032 in collaboration with Hanna Engelke and Don Lamb. Biological test regarding interferon response will be performed in my own lab or in collaboration with the group of V. Hornung in the Faculty for Chemistry and Pharmacy. The project requires intensive synthetic expertise, cell culture experimentation and single molecule spectroscopy. This multi-facetted research approach will consequently strongly benefit from the environment provided by SFB 1032.