Enzyme replacement therapy for CLN1 batten disease that crosses the blood-brain-barrier

Area of Science:

• Biochemistry
• Genetics
• Neurology

Background:

• CLN1 Batten disease is a severe pediatric neurodegenerative disorder caused by mutations in the CLN1 gene, leading to a deficiency in the lysosomal enzyme palmitoyl-protein thioesterase-1 (PPT1).
• Current treatment options for CLN1 Batten disease are limited, with no approved therapies available to halt or reverse disease progression.
• The lack of effective treatments highlights the urgent need for novel therapeutic strategies, such as enzyme replacement therapy (ERT).

Purpose of the Study:

• To develop and characterize a recombinant human PPT1 (rhPPT1) enzyme for potential use as a clinical enzyme replacement therapy in patients with CLN1 Batten disease.
• To investigate the cellular uptake mechanisms and blood-brain barrier (BBB) penetration of the developed rhPPT1.
• To explore the potential of rhPPT1 as a therapeutic agent for CLN1 Batten disease and other related lysosomal storage disorders.

Main Methods:

• Development and purification of recombinant human PPT1 (rhPPT1).
• Assessment of rhPPT1 uptake kinetics in neuronal cell lines from various species (human, rat, non-human primate, mouse) using mannose-6-phosphate receptor (M6PR)-dependent mechanisms.
• Evaluation of rhPPT1's ability to cross the blood-brain barrier (BBB) in adult mice.
• Analytical characterization of rhPPT1's glycosylation patterns, including M6P and sialic acid content.

Main Results:

• The developed rhPPT1 demonstrated M6PR-dependent uptake in neuronal cells from human, rat, and non-human primate, but not in mouse cells.
• rhPPT1 successfully crossed the blood-brain barrier (BBB) in adult mice, a significant finding for an unmodified lysosomal enzyme.
• Despite analytical characterization revealing complex M6P and sialic acid containing glycans, BBB penetration was independent of these receptors.

Conclusions:

• The development of rhPPT1 offers a promising new avenue for enzyme replacement therapy in CLN1 Batten disease.
• The ability of rhPPT1 to cross the BBB suggests potential efficacy through intravenous administration, possibly complementing other therapeutic strategies.
• These findings may also open doors for rhPPT1's application in other lysosomal storage disorders with similar pathologies.