Combination stroke therapy in the mouse with blood–brain barrier penetrating IgG–GDNF and IgG–TNF decoy receptor fusion proteins

Abstract

Stroke therapy may be optimized by combination therapy with both a neuroprotective neurotrophin and an anti-inflammatory agent. In the present work, the model neurotrophin is glial cell line-derived neurotrophic factor (GDNF), and the model anti-inflammatory agent is the type II tumor necrosis factor receptor (TNFR) decoy receptor. Both the GDNF and the TNFR are large molecules that do not cross the blood–brain barrier (BBB), which is intact in the early hours after stroke when neural rescue is still possible. The GDNF and the TNFR decoy receptor were re-engineered for BBB transport as IgG fusion proteins, wherein the GDNF or the TNFR are fused to the heavy chain of a chimeric monoclonal antibody (MAb) against the mouse transferrin receptor (TfR), and these fusion proteins are designated cTfRMAb–GDNF and cTfRMAb–TNFR, respectively. Mice were treated intravenously with (a) saline, (b) GDNF alone, (c) the cTfRMAb–GDNF fusion protein alone, or (d) the combined cTfRMAb–GDNF and cTfRMAb–TNFR fusion proteins, following a 1-h reversible middle cerebral artery occlusion (MCAO). The cTfRMAb–GDNF fusion protein alone caused a significant 25% and 30% reduction in hemispheric and cortical stroke volumes. Combined treatment with the cTfRMAb–GDNF and cTfRMAb–TNFR fusion proteins caused a significant 54%, 69% and 30% reduction in hemispheric, cortical and subcortical stroke volumes. Conversely, intravenous GDNF had no therapeutic effect. In conclusion, combination treatment with BBB penetrating IgG–GDNF and IgG–TNFR fusion proteins enhances the therapeutic effect of single treatment with the IgG–GDNF fusion protein following delayed intravenous administration in acute stroke.