Novel strategy to cross BBB by glycodesigned antibody

With the aging population diseases connected to neurodegeneration are increasing. Thus, the development of effective substances for their prevention and treatment is of utmost priority. However most recently developed medically interesting products, like monoclonal antibodies (mAbs), lack or exhibit poor central nervous system (CNS) penetration. This makes its application difficult. The aim of this proposal is to modulate the biological activity of therapeutically interesting products to efficiently cross the brain-blood-barrier (BBB). An approach that neuroinvasive bacteria use to evade the human immune system and cross the BBB, will be applied. This is achieved by certain sugar polymers, so called polysialic acid (polySia), which forms large negatively-charged hydrodynamic volumes thereby altering bio- chemical, -physical properties of target products. It is hypothesized that target molecules that form micelles (or nano-particle-like structures) and carry polySia with a controlled length, so called low molecular weight (LMW) polySia, are especially effective to cross BBB. To reach the aim a two-tier strategy is applied using a therapeutic monoclonal IgG antibody (mAb) for Alzheimer Disease treatment and the sustainable expression host Nioctiana benthamiana as models. (i) Transfer the LMW-polySia pathway into Nioctiana benthamiana. The approach is based on extensive cross phylum genetics which refers to the transfer of genetic information and the molecular interactions thereof between organisms with large evolutionarily distance. In silico studies suggests that by the co-expression of genetic elements that originate from bacteria, lower and higher eukaryotes in plants allows the assembly of the LMW polySia pathway. (ii) Engineering of mAbs: mAbs are glycoproteins with a single conserved glycosylation site. To design mAbs with altered BBB features two modifications are envisaged (a) enhancing overall glycosylation content by the generation of additional glycosites and (b) design for multimeric IgG formation, to form nanoparticle-like structures. Merging (i) and (ii): Recombinant expression of mutated mAbs in glycoengineered plants. It is expected that recombinant mAbs will carry LMW polySia and form nano-particle-like structures, thereby exhibit efficient CNS penetration. Collectively, by extensive protein and cell engineering products with novel features are generated. The approach may serve as model for other products that need to be delivered to the CNS and generally boosts the engineering of “designer cells” with specified features.