Intracerebroventricular enzyme replacement therapy with β-galactosidase reverses brain pathologies due to GM1 gangliosidosis in mice

Abstract

Autosomal recessive mutations in the galactosidase beta 1 (GLB1) gene cause lysosomal βgalactosidase (Beta-Gal) deficiency, resulting in accumulation of galactose-containing substrates and onset of the progressive and fatal neurodegenerative lysosomal storage disease, GM1 gangliosidosis. Here, an enzyme replacement therapy (ERT) approach in fibroblasts from GM1 gangliosidosis patients with recombinant human Beta-Gal (rhBeta-Gal) produced in Chinese hamster ovary cells enabled direct and precise rhBeta-Gal delivery to acidified lysosomes. A single, low dose (3 nM) of rhBeta-Gal was sufficient for normalizing Beta-Gal activity and mediating substrate clearance for several weeks. We found that rhBeta-Gal uptake by the fibroblasts is dose dependent and saturable, and can be competitively inhibited by mannose-6-phophate, suggesting cation-independent, mannose-6phophate receptor-mediated endocytosis from the cell-surface. A single intracerebroventricular (ICV)-administered dose of rhBeta-Gal (100 micrograms) resulted in broad bilateral ____________________________ GM1 gangliosidosis exhibits an autosomal recessive mode of inheritance and arises from http://www.jbc.org/cgi/

Targeting Macromolecules to CNS and Other Hard-to-Treat Organs Using Lectin-Mediated Delivery

“…Delivery to these sites is challenging due to presence of biological barriers that support them and the limited accessibility or absence of target receptors in the endothelium of these organs. Out of all LSDs described up to date, the majority display pathological manifestations in these hard-to-treat organs and treatment options using intravenous administration of the enzyme has shown very limited success or failed to prevent these devastating aspects of disease progression [11][12][13]. Even specialized cells within organs where the enzyme is distributed can remain untreated, as is often the case for heart cardiomyocytes and podocytes of the kidney [14].…”

GM1 Gangliosidosis: Mechanisms and Management

“…stem cell transplantation, [83][84][85][86] enzyme replacement therapy (ERT), 56,[87][88][89][90] and treatment with pharmacological chaperones, 55,[91][92][93][94][95][96][97][98] while substrate reduction is mediated through inhibition of ceramide glucosyltransferase, 30,[99][100][101][102] the enzyme that catalyzes the first committed step of GSL biosynthesis. For treatment of symptomatic individuals, substrate reduction therapy relies on residual β-gal activity to remove ganglioside that has already accumulated.…”

“…There are no current effective FDA-approved treatments for GM1, though advances in gene therapy are rapidly gaining traction with human clinical trials underway. Targeted research approaches for the treatment of GM1 typically align with one of the following areas: substrate reduction therapy (SRT), 30,[99][100][101][102]167,168 enzyme enhancement therapy (EET), 55,91,93,94,[169][170][171] stem cell transplantation, [83][84][85][86] enzyme replacement therapy (ERT), 56,87,89,90 or gene therapy 48,57,[60][61][62][63][64] (Figure 3). These therapeutic approaches aim to slow clinical progression, increase quality of life, and extend life expectancy through reduction of GM1 ganglioside content, enhancement of residual β-gal activity, or introduction of an exogenous active β-gal cDNA or enzyme.…”

“…Recent work by Chen et al (2019) showcased the cationindependent mannose-6-phosphate receptor-mediated endocytosis of recombinant human beta-gal (rhBeta-Gal) in a vehicle-free treatment of both human fibroblasts and βgal -/mice. 90 In fibroblasts, a single 3nM dose of rhBeta-Gal was sufficient to normalize enzyme activity for up to six weeks. Intracerebroventricular (ICV) injection of rhBeta-Gal to β-gal -/mice over the course of eight weeks revealed normalization of secondary neuropathology including LAMP2 expression, astrogliosis, and microgliosis.…”

“…RhBeta-Gal was detected in the vasculature of all cohorts and in the liver and bone marrow of mice treated for eight weeks, further supporting ICV administration of rhBeta-Gal as an ERT strategy for GM1 CNS and peripheral pathology. 90…”