Abstract
Most lysosomal storage disorders affect the central nervous system. However, lysosomal enzymes do not cross the blood-brain barrier (BBB), and intravenous enzyme infusion is not effective for the brain. Lysosomal enzymes can be re-engineered for BBB transport as IgG-enzyme fusion proteins, where the IgG domain is a monoclonal antibody (MAb) against an endogenous BBB receptor/transporter, and which acts as a molecular Trojan horse to deliver the enzyme to brain. However, the problem is retention of high enzyme activity following enzyme fusion to the IgG. The present investigation shows this is possible with a versatile approach that employs fusion of the enzyme to either the IgG heavy chain or light chain using a long flexible linker. The model IgG is a chimeric monoclonal antibody (MAb) against the human insulin receptor (HIR). The enzyme activity of the HIRMAb-enzyme fusion protein is preserved for hexosaminidase A, which is mutated in Tay Sachs disease, for protein palmitoylthioesterase-1, which is mutated in Batten disease type 1, acid sphingomyelinase, which is mutated in Niemann Pick disease type A, and beta galactosidase-1, which is mutated in GM1 gangliosidosis.
Highlights
Most lysosomal storage disorders affect the central nervous system
This study shows that hexosaminidase A (HEXA), protein palmitoylthioesterase-1 (PPT1), acid sphingomyelinase (ASM), or GLB1 can be fused to the carboxyl terminus (CT) of either the heavy chain (HC) or light chain (LC) of the HIRMAb, and enzyme activity is comparable to the native enzyme with the use of a long flexible linker
The fusion proteins are designated as HIRMAb-LC-LL-HEXA, HIRMAb-HC-SL-PPT1, HIRMAb-HC-LL-PPT1, HIRMAb-LC-LL-ASM, HIRMAb-HC-SL-GLB1, and HIRMAb-HC-LL-GLB1, where the LC or HC designation indicates if the enzyme was fused to the CT of the heavy chain or the light chain, respectively, and the SL and LL designation refers to the presence of either the 3-amino acid (AA) short linker, or the 31-AA long linker, respectively
Summary
Most lysosomal storage disorders affect the central nervous system. lysosomal enzymes do not cross the blood-brain barrier (BBB), and intravenous enzyme infusion is not effective for the brain. Lysosomal enzymes can be re-engineered for BBB transport as IgG-enzyme fusion proteins, where the IgG domain is a monoclonal antibody (MAb) against an endogenous BBB receptor/transporter, and which acts as a molecular Trojan horse to deliver the enzyme to brain. Tay Sachs disease (TSD)[2] is caused by mutations in the gene encoding the hexosaminidase A (HEXA) enzyme[3], but HEXA does not cross the BBB4. The lysosomal enzymes can be re-engineered to enable BBB transport with the genetic engineering of an IgG-lysosomal enzyme fusion protein, where the IgG domain is a monoclonal antibody (MAb) directed against an endogenous BBB receptor-mediated transport system, such as the insulin receptor or the transferrin receptor[14]. The challenge in engineering IgG-lysosomal enzyme fusion proteins is the retention of high lysosomal enzyme activity following fusion of the enzyme to the IgG. The model IgG domain is a chimeric MAb against the human insulin receptor (HIR), designated the HIRMAb14
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
