Analyzing the function of the endocytic receptor DEC205 in vitro and in vivo during delivery and presentation of antigens in brain endothelial cells.

• Applicant: Professor Dr. Karsten Mahnke
• Subject Area: Immunology ; Dermatology
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 459618779

The antigen uptake receptor DEC205 was originally described in dendritic cells (DCs). Within the intracellular domain we characterized three defined sequences, mediating (a) the uptake of ligands, (b) the targeting to deeper endosomal compartments and (c) the recycling back to the surface of DCs. This makes DEC205 a highly specialized receptor for absorptive endocytosis. Beyond DCs, DEC205 is exclusively expressed by endothelial cells (ECs) of the brain. While ECs are not classical antigen presenting cells, our preliminary data show that DEC205 mediates uptake of ligands into ECs, followed by presentation to T cells. Thus, DEC205 may serve as “linker” molecule connecting the function of ECs with those of the immune system. To analyze the functions of DEC205 in ECs in detail, we will introduce targeted mutations into its domains and follow the intracellular routing of DEC205 and its ligands through endosomal compartments. Possible adapter molecules of DEC205, i.e. members of the endosomal sorting complexes will be analyzed by co-labeling and immunoprecipitation with anti-DEC205 antibodies. For in vivo investigations of normal and inflamed brain endothelia, we will make use of the experimental allergic encephalomyelitis (EAE) model. We will couple surrogate ligands to anti-DEC205 antibodies and target brain ECs in normal and EAE induced mice. Thereafter, we will analyze the antigen uptake by ECs, the presentation of antigens to T cells, as well as their differentiation (i.e. Treg, Th1, Th2, anergy) during EAE or healthy conditions. In summary, we will define the functions of the DEC205 receptor at the interface of the vascular endothelium and the immune system.

• DFG Programme: Research Grants