Enhanced efficacy of enzyme replacement therapy in Pompe disease through mannose-6-phosphate receptor expression in skeletal muscle
Introduction
Pompe disease (glycogen storage disease type II; acid maltase deficiency; MIM 232300) ranges in severity from a severe, infantile-onset hypertrophic cardiomyopathy to a late-onset myopathy, which is caused by a defect in acid α-glucosidase (GAA) varying from complete to partial deficiency of GAA. Infantile-onset Pompe disease affects the heart and skeletal muscle primarily, and causes death early in childhood from cardiorespiratory failure, if initiation of ERT is delayed or the patient fails to respond to ERT due to high, sustained anti-GAA antibodies [1], [2], [3]. However, enzyme replacement therapy (ERT) with recombinant human (rh) GAA has been effective for the long-term only in a subset of patients with infantile-onset Pompe disease.
GAA normally functions as an acid hydrolase that metabolizes lysosomal glycogen, and deficient GAA causes lysosomal glycogen accumulation in virtually all tissues [4]. The availability of ERT with rhGAA has prolonged survival and ameliorated the cardiomyopathy in the majority of patients with infantile-onset Pompe disease [2]. In late-onset Pompe disease the clinical response to ERT has been less dramatic than in the infantile-onset presentation, and ERT has largely resulted in stabilization of the disease process from a pulmonary and motor perspective [5]. Many individuals with late-onset Pompe disease have residual gait abnormalities despite adherence to ERT, indicating a relative lack of response of limb-girdle and leg muscles [5]. Muscle weakness was stabilized by ERT in one small series following 5 patients with juvenile-onset Pompe disease, although only one subject approached the normal range for muscle strength as quantified by hand-held dynamometry following 3 years of ERT [6]. A 3 month trial of ERT in 44 subjects with late-onset Pompe disease demonstrated significant improvement in the 6 minute walk test, modified Gowers' test, and creatine kinase levels, whereas stair climbing and serial arm function tests remained unchanged [5]. Another series of 11 subjects with late-onset Pompe disease was evaluated with dynamometry and quantitative magnetic resonance imaging of leg muscles over the course of 2 years on ERT, and both muscle mass and strength in the anterior thigh improved; however, progression of intramuscular fat accumulation during ERT emphasized the limited efficacy from ERT and the need for early treatment [7]. Taken together, these studies of ERT in juvenile and late-onset Pompe disease emphasized the limited responsiveness of skeletal muscle to the only available therapy.
Documented limitations of ERT in Pompe disease include the requirement for frequent intravenous infusions of high doses of GAA to achieve efficacy, degree of pre-ERT muscle damage, and the possibility of humoral immunity [2], [3], [8]. The rhGAA doses are markedly higher than those required for ERT in other lysosomal storage disorders, possibly reflecting the higher threshold for correction of GAA deficiency in the skeletal muscle of Pompe disease patients [9]. The paucity of cation-independent mannose-6-phosphate receptor (CI-MPR) in adult mammals' muscle has underscored the concept that CI-MPR is limiting for ERT in Pompe disease. Previously, low levels of CI-MPR were demonstrated in skeletal muscle of GAA-KO mice, specifically in muscles comprised primarily of type II myofibers [10], [11]. Further evidence for the importance of CI-MPR expression to ERT in Pompe disease was demonstrated by the increased efficacy of rhGAA modified to increase mannose-6-phosphate content [12], [13], [14]. Furthermore, Pompe disease patient fibroblasts were found to be deficient in CI-MPR recycling and uptake of rhGAA was impaired [15]. However, until now the effect of CI-MPR manipulation in vivo has never been analyzed in Pompe disease.
In order to gain understanding of the influence of CI-MPR expression upon therapy in Pompe disease, we have characterized muscle-specific CI-MPR-KO/GAA-KO mice, evaluating ERT in these double (D) KO mice and demonstrating impaired responsiveness of skeletal muscle in DKO mice. In order to confirm the relevance of CI-MPR to ERT in Pompe disease, we sought to upregulate expression of CI-MPR in skeletal muscle. The only drug known to have this effect was β2-agonist therapy with clenbuterol, which increased insulin-like growth factor 2 (IGF-2) receptor (also known as CI-MPR) expression in the masseter muscle of mice, along with IGF-1 and IGF-2 [16]. Therefore, we chose to evaluate the effect of clenbuterol treatment upon receptor-mediated uptake and biochemical correction of skeletal muscle during ERT in GAA-KO mice. The effectiveness of clenbuterol in increasing the response to ERT suggests that this might be valuable as an adjunctive therapy for Pompe disease.
Section snippets
Evaluation of GAA uptake and glycogen clearance in the absence of CI-MPR expression
To understand the role of CI-MPR in recombinant human GAA (rhGAA) uptake and glycogen clearance specifically in Pompe disease, muscle-specific CI-MPR-KO mice were crossed with GAA-KO (Pompe disease) mice [17]. Evaluation of GAA activity demonstrated no significant differences in Pompe disease characteristics between the GAA-KO and the DKO mouse strains (Fig. 1A). GAA-KO and DKO mice were administered four weekly doses of rhGAA (20 mg/kg body weight), and euthanized three days after the last
Discussion
The modulating effect of CI-MPR has now been confirmed by analyzing the efficacy from GAA replacement therapy in mice with Pompe disease, either when expression was depleted or enhanced. DKO mice featured defective rhGAA uptake in skeletal muscle during ERT. Decreased rhGAA uptake in DKO mice resulted in residual glycogen storage, in comparison with GAA-KO mice treated simultaneously with ERT. The upregulation of CI-MPR by treatment with clenbuterol enhanced the response to ERT in GAA-KO mice.
Generation of muscle-specific CI-MPR-KO and DKO mouse models
CI-MPR-KO mice were generated using a muscle-specific promoter (muscle creatine kinase; CK) and the cre/loxP conditional knock out system as described previously [32]. The muscle-specific CI-MPR-KO mice were crossed with GAA-KO mice to generate muscle specific DKO mice. This mouse colony was subsequently screened to be GAA−/−, M6PR flox/flox and MCK-cre positive. These DKO mice and age matched Pompe mice were administered four weekly doses of 20 or 100 mg/kg rhGAA and sacrificed 3 days after the
Conflict of interest
YT, DB and DDK have received research/grant support from Genzyme Corporation in the past. rhGAA, in the form of Genzyme's products, Myozyme™ and Lumizyme™ is now approved by the US FDA and the European Union as a therapy for Pompe disease. Duke University and inventors for the method of treatment and predecessors of the cell lines used to generate the enzyme (rhGAA) used in various clinical trials will receive royalty payments pursuant to the University's Policy on Inventions, Patents and
Acknowledgments
This work was supported by NIH Grant R01 HL081122 from the National Heart, Lung, and Blood Institute. Partial research grant support from the Genzyme Corporation to YT Chen (DB and AMW did this work under this sponsored research agreement) is highly appreciated. BS was supported by a Development Grant from the Muscular Dystrophy Association. GAA-KO mice were provided courtesy of Dr. Nina Raben at the National Institutes of Health (Bethesda, MD). Muscle specific CI-MPR-KO mice were provided
References (34)
- et al.
Cross-reactive immunologic material status affects treatment outcomes in Pompe disease infants
Mol. Genet. Metab.
(2010) - et al.
Murine acid α-glucosidase: cell-specific mRNA differential expression during development and maturation
Am. J. Pathol.
(1999) - et al.
Effect of enzyme therapy in juvenile patients with Pompe disease: a three-year open-label study
Neuromuscul. Disord.
(2010) - et al.
Recombinant human acid α-glucosidase enzyme therapy for infantile glycogen storage disease type II: results of a phase I/II clinical trial
Genet. Med.
(2001) - et al.
Enzyme replacement therapy in the mouse model of Pompe disease
Molecr Genet Metab
(2003) - et al.
Replacing acid alpha-glucosidase in Pompe disease: recombinant and transgenic enzymes are equipotent, but neither completely clears glycogen from type II muscle fibers
Mol. Ther.
(2005) - et al.
Biochemical and pharmacological characterization of different recombinant acid alpha-glucosidase preparations evaluated for the treatment of Pompe disease
Mol. Genet. Metab.
(2008) - et al.
Glycoengineered acid alpha-glucosidase with improved efficacy at correcting the metabolic aberrations and motor function deficits in a mouse model of Pompe disease
Mol. Ther.
(2009) - et al.
The expressions of insulin-like growth factors, their receptors, and binding proteins are related to the mechanism regulating masseter muscle mass in the rat
Arch. Oral Biol.
(2006) - et al.
Targeted disruption of the acid α-glucosidase gene in mice causes an illness with critical features of both infantile and adult human glycogen storage disease type II
J. Biol. Chem.
(1998)
A muscle-specific insulin receptor knockout exhibits features of the metabolic syndrome of NIDDM without altering glucose tolerance
Mol. Cell
Tissue-specific inactivation of murine M6P/IGF2R
Am. J. Pathol.
Efficacy of an adeno-associated virus 8-pseudotyped vector in glycogen storage disease type II
Mol. Ther.
Glycogen storage disease type II: acid α-glucosidase (acid maltase) deficiency
Recombinant human acid {alpha}-glucosidase: major clinical benefits in infantile-onset Pompe disease
Neurology
Enzyme replacement therapy with alglucosidase alfa in 44 patients with late-onset glycogen storage disease type 2: 12-month results of an observational clinical trial
J. Neurol.
Changes in nutritional status and body composition during enzyme replacement therapy in adult-onset type II glycogenosis
Eur. J. Neurol.
Cited by (67)
Cation-independent mannose 6-phosphate receptor: From roles and functions to targeted therapies
2024, Journal of Controlled ReleasePhase I study of liver depot gene therapy in late-onset Pompe disease
2023, Molecular TherapyCell type-selective targeted delivery of a recombinant lysosomal enzyme for enzyme therapies
2021, Molecular TherapyImproved muscle function in a phase I/II clinical trial of albuterol in Pompe disease
2020, Molecular Genetics and MetabolismEvaluation of antihypertensive drugs in combination with enzyme replacement therapy in mice with Pompe disease
2020, Molecular Genetics and Metabolism
- 1
Current address: Genzyme Corporation, Framingham, MA 01701-9322.