Effects of enzyme replacement therapy started late in a murine model of mucopolysaccharidosis type I

Lentiviral Gene Therapy for Mucopolysaccharidosis II with Tagged Iduronate 2-Sulfatase Prevents Life-Threatening Pathology in Peripheral Tissues But Fails to Correct Cartilage

Deficiency of iduronate 2-sulfatase (IDS) causes Mucopolysaccharidosis type II (MPS II), a lysosomal storage disorder characterized by systemic accumulation of glycosaminoglycans (GAGs), leading to a devastating cognitive decline and life-threatening respiratory and cardiac complications. We previously found that hematopoietic stem and progenitor cell-mediated lentiviral gene therapy (HSPC-LVGT) employing tagged IDS with insulin-like growth factor 2 (IGF2) or ApoE2, but not receptor-associated protein minimal peptide (RAP12x2), efficiently prevented brain pathology in a murine model of MPS II. In this study, we report on the effects of HSPC-LVGT on peripheral pathology and we analyzed IDS biodistribution. We found that HSPC-LVGT with all vectors completely corrected GAG accumulation and lysosomal pathology in liver, spleen, kidney, tracheal mucosa, and heart valves. Full correction of tunica media of the great heart vessels was achieved only with IDS.IGF2co gene therapy, while the other vectors provided near complete (IDS.ApoE2co) or no (IDSco and IDS.RAP12x2co) correction. In contrast, tracheal, epiphyseal, and articular cartilage remained largely uncorrected by all vectors tested. These efficacies were closely matched by IDS protein levels following HSPC-LVGT. Our results demonstrate the capability of HSPC-LVGT to correct pathology in tissues of high clinical relevance, including those of the heart and respiratory system, while challenges remain for the correction of cartilage pathology.

Efficacy of a Combination Therapy with Laronidase and Genistein in Treating Mucopolysaccharidosis Type I in a Mouse Model

Mucopolysaccharidosis type I (MPS I) is a lysosomal storage disorder caused by α-L-iduronidase deficiency. The standard treatment, enzyme replacement therapy with laronidase, has limited effectiveness in treating neurological symptoms due to poor blood-brain barrier penetration. An alternative is substrate reduction therapy using molecules, such as genistein, which crosses this barrier. This study evaluated the effectiveness of a combination of laronidase and genistein in a mouse model of MPS I. Over 12 weeks, MPS I and wild-type mice received laronidase, genistein, or both. Glycosaminoglycan (GAG) storage in visceral organs and the brain, its excretion in urine, and the serum level of the heparin cofactor II-thrombin (HCII-T) complex, along with behavior, were assessed. The combination therapy resulted in reduced GAG storage in the heart and liver, whereas genistein alone reduced the brain GAG storage. Laronidase and combination therapy decreased liver and spleen weights and significantly reduced GAG excretion in the urine. However, this therapy negated some laronidase benefits in the HCII-T levels. Importantly, the combination therapy improved the behavior of female mice with MPS I. These findings offer valuable insights for future research to optimize MPS I treatments.

Neurologic Recovery in MPS I and MPS II Mice by AAV9-Mediated Gene Transfer to the CNS After the Development of Cognitive Dysfunction

The mucopolysaccharidoses (MPS) are a group of recessively inherited conditions caused by deficiency of lysosomal enzymes essential to the catabolism of glycosaminoglycans (GAG). MPS I is caused by deficiency of the lysosomal enzyme alpha-L-iduronidase (IDUA), while MPS II is caused by a lack of iduronate-2-sulfatase (IDS). Lack of these enzymes leads to early mortality and morbidity, often including neurological deficits. Enzyme replacement therapy has markedly improved the quality of life for MPS I and MPS II affected individuals but is not effective in addressing neurologic manifestations. For MPS I, hematopoietic stem cell transplant has shown effectiveness in mitigating the progression of neurologic disease when carried out in early in life, but neurologic function is not restored in patients transplanted later in life. For both MPS I and II, gene therapy has been shown to prevent neurologic deficits in affected mice when administered early, but the effectiveness of treatment after the onset of neurologic disease manifestations has not been characterized. To test if neurocognitive function can be recovered in older animals, human IDUA or IDS-encoding AAV9 vector was administered by intracerebroventricular injection into MPS I and MPS II mice, respectively, after the development of neurologic deficit. Vector sequences were distributed throughout the brains of treated animals, associated with high levels of enzyme activity and normalized GAG storage. Two months after vector infusion, treated mice exhibited spatial navigation and learning skills that were normalized, that is, indistinguishable from those of normal unaffected mice, and significantly improved compared to untreated, affected animals. We conclude that cognitive function was restored by AAV9-mediated, central nervous system (CNS)-directed gene transfer in the murine models of MPS I and MPS II, suggesting that gene transfer may result in neurodevelopment improvements in severe MPS I and MPS II when carried out after the onset of cognitive decline.

Brain and visceral gene editing of mucopolysaccharidosis I mice by nasal delivery of the CRISPR/Cas9 system

INTRODUCTION

Mucopolysaccharidosis type I (MPS I) is an inherited disease caused by deficiency of the enzyme alpha-L-iduronidase (IDUA). MPS I affects several tissues, including the brain, leading to cognitive impairment in the severe form of the disease. Currently available treatments do not reach the brain. Therefore, in this study, we performed nasal administration (NA) of liposomal complexes carrying two plasmids encoding for the CRISPR/Cas9 system and for the IDUA gene targeting the ROSA26 locus, aiming at brain delivery in MPS I mice.

METHODS

Liposomes were prepared by microfluidization and the plasmids were complexed to the formulations by adsorption. Physicochemical characterization of the formulations and complexes, in vitro permeation, and mucoadhesion in porcine nasal mucosa (PNM) were assessed. We performed NA repeatedly for 30 days in young MPS I mice, which were euthanized at 6 months of age after performing behavioral tasks, and biochemical and molecular aspects were evaluated.

RESULTS

Monodisperse mucoadhesive complexes around 110nm, which are able to efficiently permeate the PNM. In animals the treatment led to a modest increase in IDUA activity in the lung, heart and brain areas, with reduction of glycosaminoglycan (GAG) levels in serum, urine, tissues and brain cortex. Furthermore, treated mice showed improvement in behavioral tests, suggesting prevention of the cognitive damage.

CONCLUSION

Non-viral gene editing performed through nasal route represents a potential therapeutic alternative for the somatic and neurologic symptoms of MPS I and possibly to other neurological disorders.

Mechanisms of demyelination and neurodegeneration in globoid cell leukodystrophy

Globoid cell leukodystrophy (GLD), also known as Krabbe disease, is a lysosomal storage disorder causing extensive demyelination in the central and peripheral nervous systems. GLD is caused by loss-of-function mutations in the lysosomal hydrolase, galactosylceramidase (GALC), which catabolizes the myelin sphingolipid galactosylceramide. The pathophysiology of GLD is complex and reflects the expression of GALC in a number of glial and neural cell types in both the central and peripheral nervous systems (CNS and PNS), as well as leukocytes and kidney in the periphery. Over the years, GLD has garnered a wide range of scientific and medical interests, especially as a model system to study gene therapy and novel preclinical therapeutic approaches to treat the spontaneous murine model for GLD. Here, we review recent findings in the field of Krabbe disease, with particular emphasis on novel aspects of GALC physiology, GLD pathophysiology, and therapeutic strategies.

Mucopolysaccharidosis Type I: Current Treatments, Limitations, and Prospects for Improvement

Mucopolysaccharidosis type I (MPS I) is a lysosomal disease, caused by a deficiency of the enzyme alpha-L-iduronidase (IDUA). IDUA catalyzes the degradation of the glycosaminoglycans dermatan and heparan sulfate (DS and HS, respectively). Lack of the enzyme leads to pathologic accumulation of undegraded HS and DS with subsequent disease manifestations in multiple organs. The disease can be divided into severe (Hurler syndrome) and attenuated (Hurler-Scheie, Scheie) forms. Currently approved treatments consist of enzyme replacement therapy (ERT) and/or hematopoietic stem cell transplantation (HSCT). Patients with attenuated disease are often treated with ERT alone, while the recommended therapy for patients with Hurler syndrome consists of HSCT. While these treatments significantly improve disease manifestations and prolong life, a considerable burden of disease remains. Notably, treatment can partially prevent, but not significantly improve, clinical manifestations, necessitating early diagnosis of disease and commencement of treatment. This review discusses these standard therapies and their impact on common disease manifestations in patients with MPS I. Where relevant, results of animal models of MPS I will be included. Finally, we highlight alternative and emerging treatments for the most common disease manifestations.

Evidence that glycosaminoglycan storage and collagen deposition in the cauda epididymidis does not impair sperm viability in the Mucopolysaccharidosis type I mouse model

Mucopolysaccharidosis type I (MPS I) is a lysosomal storage disease caused by a deficiency of the lysosomal hydrolase, α-L-iduronidase (IDUA). IDUA degrades heparan and dermatan sulfates, two types of glycosaminoglycan (GAG), important signalling and structural molecules of the extracellular matrix. Because many cell types store GAGs, MPS I has been investigated in human and animal models. Enzyme replacement therapy is available for MPS I patients and has improved their life expectancy, allowing them to achieve reproductive age. The aim of this study was to evaluate epididymal and sperm morphology and function in a murine model of MPS I. We used C57BL Idua+/+ and Idua-/- adult male mice (6 months old) to investigate epididymal morphology, sperm ultrastructure, GAG characterisation and mating competence. Epithelial GAG storage, especially in the cauda epididymidis, was seen in Idua-/- mice. Regardless of the morphologic change and GAG storage found in the cauda epididymis, sperm morphology and motility were normal, similar to wild types. In the interstitium, vacuolated cells were found in addition to deposits of GAGs. Mating was not impaired in Idua-/- males and litter sizes were similar between groups. At the time point of the disease evaluated, the deficiency in IDUA affected the morphology of the epididymis in male Idua-/- mice, whereas sperm appearance and motility and the male's capacity to mate and impregnate females were preserved.

Neonatal combination therapy improves some of the clinical manifestations in the Mucopolysaccharidosis type I murine model

Mucopolysaccharidosis type I (MPS-I), a lysosomal storage disorder caused by a deficiency of alpha-L-iduronidase enzyme, results in the progressive accumulation of glycosaminoglycans and consequent multiorgan dysfunction. Despite the effectiveness of hematopoietic stem cell transplantation (HSCT) and enzyme replacement therapy (ERT) in correcting clinical manifestations related to visceral organs, complete improvement of musculoskeletal and neurocognitive defects remains an unmet challenge and provides an impact on patients' quality of life. We tested the therapeutic efficacy of combining HSCT and ERT in the neonatal period. Using a mouse model of MPS-I, we demonstrated that the combination therapy improved clinical manifestations in organs usually refractory to current treatment. Moreover, combination with HSCT prevented the production of anti-IDUA antibodies that negatively impact ERT efficacy. The added benefits of combining both treatments also resulted in a reduction of skeletal anomalies and a trend towards decreased neuroinflammation and metabolic abnormalities. As currently there are limited therapeutic options for MPS-I patients, our findings suggest that the combination of HSCT and ERT during the neonatal period may provide a further step forward in the treatment of this rare disease.

Cathepsins in the Pathophysiology of Mucopolysaccharidoses: New Perspectives for Therapy

Cathepsins (CTSs) are ubiquitously expressed proteases normally found in the endolysosomal compartment where they mediate protein degradation and turnover. However, CTSs are also found in the cytoplasm, nucleus, and extracellular matrix where they actively participate in cell signaling, protein processing, and trafficking through the plasma and nuclear membranes and between intracellular organelles. Dysregulation in CTS expression and/or activity disrupts cellular homeostasis, thus contributing to many human diseases, including inflammatory and cardiovascular diseases, neurodegenerative disorders, diabetes, obesity, cancer, kidney dysfunction, and others. This review aimed to highlight the involvement of CTSs in inherited lysosomal storage disorders, with a primary focus to the emerging evidence on the role of CTSs in the pathophysiology of Mucopolysaccharidoses (MPSs). These latter diseases are characterized by severe neurological, skeletal and cardiovascular phenotypes, and no effective cure exists to date. The advance in the knowledge of the molecular mechanisms underlying the activity of CTSs in MPSs may open a new challenge for the development of novel therapeutic approaches for the cure of such intractable diseases.

Pre-clinical Mouse Models of Neurodegenerative Lysosomal Storage Diseases

There are over 50 lysosomal hydrolase deficiencies, many of which cause neurodegeneration, cognitive decline and death. In recent years, a number of broad innovative therapies have been proposed and investigated for lysosomal storage diseases (LSDs), such as enzyme replacement, substrate reduction, pharmacologic chaperones, stem cell transplantation, and various forms of gene therapy. Murine models that accurately reflect the phenotypes observed in human LSDs are critical for the development, assessment and implementation of novel translational therapies. The goal of this review is to summarize the neurodegenerative murine LSD models available that recapitulate human disease, and the pre-clinical studies previously conducted. We also describe some limitations and difficulties in working with mouse models of neurodegenerative LSDs.

Cathepsin B-associated Activation of Amyloidogenic Pathway in Murine Mucopolysaccharidosis Type I Brain Cortex

Mucopolysaccharidosis type I (MPS I) is caused by genetic deficiency of α-l-iduronidase and impairment of lysosomal catabolism of heparan sulfate and dermatan sulfate. In the brain, these substrates accumulate in the lysosomes of neurons and glial cells, leading to neuroinflammation and neurodegeneration. Their storage also affects lysosomal homeostasis-inducing activity of several lysosomal proteases including cathepsin B (CATB). In the central nervous system, increased CATB activity has been associated with the deposition of amyloid plaques due to an alternative pro-amyloidogenic processing of the amyloid precursor protein (APP), suggesting a potential role of this enzyme in the neuropathology of MPS I. In this study, we report elevated levels of protein expression and activity of CATB in cortex tissues of 6-month-old MPS I (Idua -/- mice. Besides, increased CATB leakage from lysosomes to the cytoplasm of Idua -/- cortical pyramidal neurons was indicative of damaged lysosomal membranes. The increased CATB activity coincided with an elevated level of the 16-kDa C-terminal APP fragment, which together with unchanged levels of β-secretase 1 was suggestive for the role of this enzyme in the amyloidogenic APP processing. Neuronal accumulation of Thioflavin-S-positive misfolded protein aggregates and drastically increased levels of neuroinflammatory glial fibrillary acidic protein (GFAP)-positive astrocytes and CD11b-positive activated microglia were observed in Idua -/- cortex by confocal fluorescent microscopy. Together, our results point to the existence of a novel CATB-associated alternative amyloidogenic pathway in MPS I brain induced by lysosomal storage and potentially leading to neurodegeneration.

Progressive eye pathology in mucopolysaccharidosis type I mice and effects of enzyme replacement therapy

BACKGROUND

Mucopolysaccharidosis type I (MPS I) is a lysosomal storage disorder caused by α-L-iduronidase deficiency, resulting in accumulation of glycosaminoglycans (GAG). Ophthalmological manifestations are common in MPS I patients and often lead to visual impairment. Accumulation of GAG in corneal or retinal tissues reduces vision causing corneal opacity and neurosensory complications. One available treatment for MPS I patients is enzyme replacement therapy (ERT), but the results of such treatment on eye disease are still debatable. Therefore, we aimed to determine the progression of ocular manifestations as well as the effectiveness of intravenous ERT in MPS I.

METHODS

Corneal and retinal analyses were perform in eyes from 2- to 8-month normal and MPS I mice. Some MPS I mice received ERT (1.2 mg/kg of laronidase) every 2 weeks from 6 to 8 months and histological findings were compared with controls. Additionally, cornea from two MPS I patients under ERT were evaluated.

RESULTS

Mouse corneal tissues had GAG accumulation early in life. In the retina, we found a progressive loss of photoreceptor cells, starting at 6 months. ERT did not improve or stabilize the histological abnormalities. MPS I patients, despite being on ERT for over a decade, presented GAG accumulation in the cornea, corneal thickening, visual loss and needed corneal transplantation.

CONCLUSION

We provide data on the time course of ocular alteration in MPS I mice. Our results also suggest that ERT is not effective in treating the progressive ocular manifestations in MPS I mice and fails to prevent corneal abnormalities in patients.

Chondrogenic effect of liquid and gelled platelet lysate on canine adipose-derived mesenchymal stromal cells

Osteoarthritis associated with hip dysplasia is one of the most common orthopedic abnormalities in dogs, with an incidence of up to 40% in some breeds. Tissue therapy of cartilage has received great attention, with use of mesenchymal stromal cells and different types of biomaterials. The present study aimed to evaluate the effect of platelet lysate (PL) on the proliferation and differentiation of canine adipose tissue-derived mesenchymal stromal cells (ASCs), in liquid culture or hydrogels. PL was prepared from blood collected from healthy dogs and submitted to freezing-thawing cycles, and hydrogel was formed with canine thrombin. The effect of PL on the proliferation and differentiation of canine ASCs was evaluated in liquid and hydrogel systems, with microscopy, quantification of dsDNA, histology and quantification of glycosaminoglycans. The addition of 5% or 10% PL to the culture medium induced a greater proliferation rate than the presence of 10% fetal bovine serum. The cultivation of ASCs in PL gel, with normal or chondrogenic medium, resulted in maintenance of proliferation level similar to the conventional 2D cultivation, and induction of chondrogenic differentiation, especially in the presence of the chondrogenesis induction medium.

P-Tau and Subunit c Mitochondrial ATP Synthase Accumulation in the Central Nervous System of a Woman with Hurler-Scheie Syndrome Treated with Enzyme Replacement Therapy for 12 Years

We report an autopsy case of a woman with mucopolysaccharidosis type I (MPS I) Hurler-Scheie syndrome who was treated with enzyme replacement therapy (ERT) for 12 years. This was the first case of MPS I treated with ERT in Japan. Pathological analysis showed no glycosaminoglycan accumulation in the liver and spleen as a result of long-term ERT, although severe aortic stenosis, diffuse intimal hyperplasia of the coronary artery, and fibrous hypertrophy of the endocardium were observed. Additionally, we detected subunit c mitochondrial ATP synthase (SCMAS) accumulation and mild tauopathy (hyperphosphorylated tau or p-tau, both 3-repeat and 4-repeat tau accumulation) in the same area of the cerebral limbic system and central gray matter of the mid brain and pons. Tauopathy is an important pathological finding in Alzheimer's disease and other neurodegenerative disorders; however, in MPS I, it is unclear whether tauopathy is a primary or secondary phenomenon. Thus, in this report, we describe pathological accumulation of p-tau and SCMAS in the context of MPS I and discuss the mechanisms and importance of these findings in the pathogenesis of MPS I.

Glycosaminoglycan fragments as a measure of disease burden in the mucopolysaccharidosis type I mouse

Glycosaminoglycan (GAG) catabolism involves endo-hydrolysis of polysaccharides followed by the sequential removal of the non-reducing end residue from the resulting oligosaccharides by exo-enzymes. In the inherited metabolic disorder, mucopolysaccharidosis type I (MPS I), a deficiency in the exo-enzyme, α-l-iduronidase, prevents removal of α-l-iduronic acid residues from the non-reducing end of the GAGs, heparan sulphate (HS) and dermatan sulphate (DS). The excretion of partially degraded HS and DS in urine of MPS I patients has long been recognized, but the question of whether they do indeed reflect GAG load in a particular tissue has not been addressed - an important issue in the context of biomarkers for assessment of disease burden in MPS I. Therefore, we measured specific low molecular weight HS and DS oligosaccharides with terminal α-l-iduronic acid residues, in the brain, liver, kidney, serum and urine, and correlated these findings with total GAG in the MPS I mouse model. Six oligosaccharides were identified in the urine, ranging from di- to pentasaccharides. Of these, five were observed in the kidney, four in the liver and brain, with the three most abundant in urine also seen in serum. These oligosaccharides accounted for just 0.1-2% of total GAG, with a disaccharide showing the best correlation with total GAG. The oligosaccharides and total GAG were most abundant in the liver, with the least observed in the brain. The concentration of oligosaccharides as a percentage of total GAG in urine was similar to that observed in the kidney, and both revealed a similar ratio of HS:DS, suggesting that the oligosaccharide storage pattern in urine is a reflection of that in the kidney. Serum, liver and brain had a similar ratio of HS:DS, which was lower to that seen in the urine and kidney. The distribution of oligosaccharides when ranked from most to least abundant, was also the same between serum, liver and brain suggesting that serum more closely reflects the oligosaccharides of the brain and liver and may therefore be a more informative measurement of disease burden than urine. The accumulation of HS and DS oligosaccharides was observed in the brain as early as one month of age, with the disaccharide showing a continuous increase with age. This demonstrates the progressive nature of the disease and as such this disaccharide could prove to be a useful biomarker to measure disease burden in MPS I.

Deleterious effects of interruption followed by reintroduction of enzyme replacement therapy on a lysosomal storage disorder

Temporary interruption of enzyme replacement therapy (ERT) in patients with different lysosomal storage disorders may happen for different reasons (adverse reactions, issues with reimbursement, logistic difficulties, and so forth), and the impact of the interruption is still uncertain. In the present work, we studied the effects of the interruption of intravenous ERT (Laronidase, Genzyme) followed by its reintroduction in mice with the prototypical lysosomal storage disorder mucopolysaccharidosis type I, comparing to mice receiving continuous treatment, untreated mucopolysaccharidosis type I mice, and normal mice. In the animals which treatment was temporarily interrupted, we observed clear benefits of treatment in several organs (liver, lung, heart, kidney, and testis) after reintroduction, but a worsening in the thickness of the aortic wall was detected. Furthermore, these mice had just partial improvements in behavioral tests, suggesting some deterioration in the brain function. Despite worsening is some disease aspects, urinary glycosaminoglycans levels did not increase during interruption, which indicates that this biomarker commonly used to monitor treatment in patients should not be used alone to assess treatment efficacy. The deterioration observed was not caused by the development of serum antienzyme antibodies. All together our results suggest that temporary ERT interruption leads to deterioration of function in some organs and should be avoided whenever possible.

Residual glycosaminoglycan accumulation in mitral and aortic valves of a patient with attenuated MPS I (Scheie syndrome) after 6 years of enzyme replacement therapy: Implications for early diagnosis and therapy

Mucopolysaccharidosis (MPS) is an inherited metabolic disease caused by deficiency of the enzymes needed for glycosaminoglycan (GAG) degradation. MPS type I is caused by the deficiency of the lysosomal enzyme alpha-l-iduronidase and is classified into Hurler syndrome, Scheie syndrome, and Hurler–Scheie syndrome based on disease severity and onset. Cardiac complications such as left ventricular hypertrophy, cardiac valve disease, and coronary artery disease are often observed in MPS type I. Enzyme replacement therapy (ERT) has been available for MPS type I, but the efficacy of this treatment for cardiac valve disease is unknown. We report on a 56-year-old female patient with attenuated MPS I (Scheie syndrome) who developed aortic and mitral stenosis and coronary artery narrowing. The cardiac valve disease progressed despite ERT and she finally underwent double valve replacement and coronary artery bypass grafting. The pathology of the cardiac valves revealed GAG accumulation and lysosomal enlargement in both the mitral and aortic valves. Zebra body formation was also confirmed using electron microscopy. Our results suggest that ERT had limited efficacy in previously established cardiac valve disease. Early diagnosis and initiation of ERT is crucial to avoid further cardiac complications in MPS type I.