Background
Drug delivery to the brain is a major roadblock to treatment of Alzheimer's disease. Recent
Conclusions
These results support a model in which surface-sialylated 4G8 inhibits its own efflux and that of asialylated 4G8. General significance: Glycan modification has the potential to increase antibody drug penetration into the brain through efflux inhibition.
Methods
The blood-brain barrier permeability coefficient Pe of different glycosylated states of anti-amyloid IgG was measured using in vitro models of brain microvascular endothelial cells. Monoclonal antibodies 4G8, with sialic acid, and 6E10, lacking sialic acid, were studied. The amount of sialic acid was determined using quantitative and semi-quantitative surface plasmon resonance methods.
Results
Influx of IgG was not saturable and was largely insensitive to IgG species and glycosylation state. By contrast, efflux of 4G8 efflux was significantly lower than both albumin controls and 6E10. Removal of α2,6-linked sialic acid group present on 12% of 4G8 completely restored efflux to that of 6E10 but increasing the α2,6-sialylated fraction to 15% resulted in no change. Removal of the Fc glycan from 4G8 partially restored efflux. Alternate sialic acid groups with α2,3 and α2,8 linkages, nor on the Fc glycan, were not detected at significant levels on either 4G8 or 6E10. Conclusions: These results support a model in which surface-sialylated 4G8 inhibits its own efflux and that of asialylated 4G8. General significance: Glycan modification has the potential to increase antibody drug penetration into the brain through efflux inhibition.
Significance
Glycan modification has the potential to increase antibody drug penetration into the brain through efflux inhibition.