Clinical Improvement of Alpha-mannosidosis Cat Following a Single Cisterna Magna Infusion of AAV1.

Lysosomal storage diseases (LSDs) are debilitating neurometabolic disorders for most of which long-term effective therapies have not been developed. Gene therapy is a potential treatment but a critical barrier to treating the brain is the need for global correction. We tested the efficacy of cisterna magna infusion of adeno-associated virus type 1 (AAV1) expressing feline alpha-mannosidase gene in the postsymptomatic alpha-mannosidosis (AMD) cat, a homologue of the human disease. Lysosomal alpha-mannosidase (MANB) activity in the cerebrospinal fluid (CSF) and serum were increased above the control values in untreated AMD cats. Clinical neurological signs were delayed in onset and reduced in severity. The lifespan of the treated cats was significantly extended. Postmortem histopathology showed resolution of lysosomal storage lesions throughout the brain. MANB activity in brain tissue was significantly above the levels of untreated tissues. The results demonstrate that a single cisterna magna injection of AAV1 into the CSF can mediate widespread neuronal transduction of the brain and meaningful clinical improvement. Thus, cisterna magna gene delivery by AAV1 appears to be a viable strategy for treatment of the whole brain in AMD and should be applicable to many of the neurotropic LSDs as well as other neurogenetic disorders.

Alpha-mannosidosis.

Alpha-mannosidosis is an inherited lysosomal storage disorder characterized by immune deficiency, facial and skeletal abnormalities, hearing impairment, and intellectual disability. It occurs in approximately 1 of 500,000 live births. The children are often born apparently normal, and their condition worsens progressively. Some children are born with ankle equinus or develop hydrocephalus in the first year of life. Main features are immune deficiency (manifested by recurrent infections, especially in the first decade of life), skeletal abnormalities (mild-to-moderate dysostosis multiplex, scoliosis and deformation of the sternum), hearing impairment (moderate-to-severe sensorineural hearing loss), gradual impairment of mental functions and speech, and often, periods of psychosis. Associated motor function disturbances include muscular weakness, joint abnormalities and ataxia. The facial trait include large head with prominent forehead, rounded eyebrows, flattened nasal bridge, macroglossia, widely spaced teeth, and prognathism. Slight strabismus is common. The clinical variability is significant, representing a continuum in severity. The disorder is caused by lysosomal alpha-mannosidase deficiency. Alpha-mannosidosis is inherited in an autosomal recessive fashion and is caused by mutations in the MAN2B1 gene located on chromosome 19 (19 p13.2-q12). Diagnosis is made by measuring acid alpha-mannosidase activity in leukocytes or other nucleated cells and can be confirmed by genetic testing. Elevated urinary secretion of mannose-rich oligosaccharides is suggestive, but not diagnostic. Differential diagnoses are mainly the other lysosomal storage diseases like the mucopolysaccharidoses. Genetic counseling should be given to explain the nature of the disease and to detect carriers. Antenatal diagnosis is possible, based on both biochemical and genetic methods. The management should be pro-active, preventing complications and treating manifestations. Infections must be treated frequently. Otolaryngological treatment of fluid in the middle ear is often required and use of hearing aids is invariably required. Early educational intervention for development of social skills is needed and physiotherapy is important to improve bodily function. Orthopedic surgery may be necessary. The long-term prognosis is poor. There is an insidiously slow progression of neuromuscular and skeletal deterioration over several decades, making most patients wheel-chair dependent. No patients manage to be completely socially independent. Many patients are over 50 years of age.

Destructive joint disease in alpha-mannosidosis. A case report and review of the literature.

Storage of oligosaccharides due to a deficiency of alpha-mannosidase can lead to joint destruction in children and young adults. Treating hip destruction with a prosthesis might be successful in some of these patients, although diminished bone quality increases the risk of loosening of the prosthesis.

Morphological and biochemical studies of human beta-mannosidosis: identification of a novel beta-mannosidase gene mutation.

BACKGROUND: There are seven well-known lysosomal storage diseases that produce angiokeratoma corporis diffusum clinically. beta-Mannosidosis (MANB1; OMIM248510), first reported in humans in 1986, is a rare hereditary lysosomal storage disease caused by a deficiency of the enzyme beta-mannosidase. Since then, 13 cases of beta-mannosidase deficiency in ten families have been described. A human beta-mannosidase mutation has been reported only by Alkhayat et al. in 1998. OBJECTIVES: To clarify its pathogenesis we did electron microscopic, biochemical and molecular biological investigations of a Japanese patient with beta-mannosidosis. METHODS: Ultrastructural analyses, enzyme assays, cell culture and mRNA and genomic DNA were sequenced to find mutations in the beta-mannosidase gene. RESULTS: Electron microscopy of skin biopsy specimens from the patient showed cytoplasmic vacuolation of lysosomes in blood and lymph vessels, endothelial cells, fibroblasts, secretory portions of eccrine sweat glands, neural cells and basal keratinocytes in the epidermis. This vacuolation was also observed in cultured keratinocytes and fibroblasts. Assays of seven enzyme activities in plasma and cultured skin fibroblasts showed a marked decrease of beta-mannosidase activity. Sequencing the beta-mannosidase cDNA revealed a four-base (ATAA) insertion between exons 7 and 8, resulting in a frameshift at codon 321 and termination at codon 325. Analysis of the patient's genomic DNA revealed a novel homozygous A(+1)-->G splice site mutation in intron 7. CONCLUSIONS: To our knowledge, this is the first case of beta-mannosidosis reported in Japan and the second report in which a gene mutation is identified. The biological importance of beta-mannose moieties in glycoproteins in basal keratinocytes is suggested.

Alpha-mannosidosis. Report of a case with morphologic, cytologic and immunohistochemical considerations.

We report the histopathologic features of the knee bone and synovium and the cytologic features of the synovial fluid from a patient with alpha-mannosidosis. The synovium showed marked papillary hyperplasia with infiltration of foamy histiocytes containing periodic acid-Schiff-positive, diastase-resistant material. Severe degenerative changes were seen in the knee bone. The synovial fluid showed increased numbers of macrophages containing periodic acid-Schiff-positive, diastase-resistant material. The differential diagnostic considerations in the synovial fluid are also discussed.

Bone marrow transplantation corrects the enzyme defect in neurons of the central nervous system in a lysosomal storage disease.

Neuronal storage disorders are fatal neurodegenerative diseases of humans and animals that are caused by inherited deficiencies of lysosomal hydrolase activity. Affected individuals often appear normal at birth but eventually develop progressive neurologic symptoms including sensory and motor deficits, mental retardation, and seizures. We have examined efficacy of bone marrow transplantation as a means of enzyme replacement, using cats with the lysosomal storage disease alpha-mannosidosis. Treated animals showed little or no progression of neurologic signs 1-2 years after transplant, whereas untreated cats became severely impaired and reached endstage disease by 6 months of age. Increased lysosomal alpha-mannosidase activity was found in brain tissue of the treated animals, and electron microscopy revealed no evidence of lysosomal storage within most neurons. Histochemical localization of acidic alpha-D-mannoside mannohydrolase (EC 3.2. 1.24), using 5-bromo-4-chloro-3-indolyl alpha-D-mannopyranoside, showed that functional enzyme was present in neurons, glial cells, and cells associated with blood vessels. This study provides direct evidence that bone marrow transplantation as treatment for a neuronal storage disease can lead to significant levels of a missing lysosomal hydrolase within neurons of the central nervous system and to compensation for the genetic metabolic defect.

[Changes in the organization of the intermediate filament system of human fibroblasts in lysosomal storage diseases and their modeling]. / Izmenenie organizatsii sistemy promezhutochnykh filamentov v fibroblastakh cheloveka pri lizosomnykh bolezniakh nakopleniia i ikh modelirovanii.

The organization of the system of the vimentin intermediate filaments (IFs) in human fibroblasts in lysosomal storage diseases (Fabry's disease, mannosidosis) and their modelling has been studied in vitro. It was shown that during accumulation of nonhydrolyzable compounds, hypertrophy of the lysosomal compartment is accompanied by formation of ring-shaped bundles IFs, surrounding apparently these increased organelles. The changed organization of IFs is characteristic of polarised pathological cells in monolayer, and after repassage it is retained only at the spreading state; on transition from the discoid to extended cellular form there occurred the centrifugal shift of ring-shaped structures of IFs to active cell border and gradual restoration of radial fibrillar state of IFs. It is suggested that on intralysosomal storage of unsplit compounds reorganization of the vimentin-type IFs in ring-shaped structure is necessary for optimal distribution and stabilization into the cytoplasm of large amounts of increased lysosomes with exo- and endogenous contents. In condition of free spreading (i. e. with diminished cell density) the restoration of normal fibrillar IF organization may be due to the loss of considerable number of hypertrophied lysosomes; the involvement of lysosomal membrane in formation of active cellular border is not to be ruled out.

Estimation and comparison of lysosomal and cytoplasmic pH of human fibroblasts from healthy donors and patients with lysosomal storage diseases.

Measurements were made of the pH of cytoplasm and lysosomes of cultured skin fibroblasts from healthy donors and from patients with lysosomal storage diseases (mannosidosis, Fabry's disease, and Krabbe's disease), and the effects of sucrose loading on normal fibroblasts were studied. The cytoplasmic pH of the pathological cells did not differ from control values, but the intralysosomal pH was significantly higher in sucrose-loaded normal fibroblasts and in cells from a patient with mannosidosis and from another with Fabry's disease. The change in pH observed accorded with an increase in size of the organelles, owing to accumulation of nonhydrolyzable compounds. In fibroblasts from a patient with Krabbe's disease, which do not store nonhydrolyzable compounds, there was no increase either in intralysosomal pH or in lysosome size. It is suggested that the decrease in the pH difference between the cytoplasm and lysosomes in the pathological cells leads to inhibition of catabolic processes in lysosomes and to some changes in the intracellular transport of these vesicles.

Otic pathology of caprine beta-mannosidosis.

Caprine beta-mannosidosis is an autosomal recessive defect of glycoprotein catabolism with a deficiency of tissue and plasma beta-mannosidase activity and tissue accumulation of oligosaccharides within lysosomes. This rapidly fatal genetic disorder of Nubian goats is expressed at birth by a variety of clinical signs including deafness. Affected goats had folded pinnas, and the tympanic cavity was decreased due to multiple, polypoid projections of bone covered by middle ear mucosa which obstructed the view of the cochlear promontory. Numerous cells of the cochlear duct including mesothelial and epithelial cells of Reissner's membrane, mesothelial cells lining the scala tympani, cells of the stria vascularis, numerous supportive cells of the organ of Corti, cochlear hair cells, endothelial cells, perithelial cells, fibroblasts, macrophages, and neurons of the spiral ganglion contained numerous nonstaining intracytoplasmic vacuoles which resulted in distention of affected cells and caused thickening of involved structures. Ultrastructurally, the vacuoles were membrane-bound and consistent with lysosomes. Vacuolated cells were desquamated into the scala vestibuli and scala tympani. This is one of few reports describing light and electron microscopic otic alterations of a storage disease. Goats with beta-mannosidosis appear to be good models of hearing loss in patients with storage disease.

Bone marrow transplantation in the treatment of alpha-mannosidosis.

Bone marrow transplantation was performed in a patient with alpha-mannosidosis. To our knowledge this is the first time such treatment has been attempted. The patient died 18 weeks after successful grafting and specimens of tissues were obtained at necropsy. Alpha-mannosidase activity in spleen and liver was just below normal (spleen 102 mumol/g/hour, control 113-330; liver 29 mumol/g/hour, control 30-131). Splenic alpha-mannosidase activity was indistinguishable from the control enzyme with respect to the Michaelis constant, heat stability, and inhibition by cobalt ions, as was 86% of the liver enzyme. In brain tissue alpha-mannosidase activity was 7% of controls, and less than one third had the properties of the normal enzyme. Oligosaccharides were present only in small amounts in liver and spleen, whereas they were greatly increased in brain tissue. Electron microscopic pictures of liver and spleen tissue showed normal morphology, but brain tissue showed definite vacuolation. These findings suggest that transplantation reversed the somatic changes of alpha-mannosidosis but did not affect lysosomal storage within brain tissue. It is concluded that marrow transplantation may not be a suitable treatment for alpha-mannosidosis.

Lysosomal storage in human skeletal muscle.

Skeletal muscle is involved symptomatically in two lysosomal storage diseases, acid maltase deficiency and a similar condition in which enzyme levels are normal. Asymptomatic storage in skeletal muscle cells is found in Batten-Kufs' disease (ceroid lipofuscinosis), Fabry's disease, and mannosidosis, as well as in rare patients with an unidentified storage disease. Other cell types (vascular endothelium, smooth muscle, fibroblasts, satellite cells) within the confines of the biopsy specimen may reveal storage in other diseases. The differential diagnosis involves predominantly both normal and abnormal conditions in which acid phosphatase activity is prominent in cells.

Skeletal muscle pathology of mannosidosis in two siblings with spastic paraplegia.

Deficiency of alpha-D-mannosidase was found in two siblings with muscle weakness and spastic paraplegia. A biopsy of the vastus lateralis muscle was studied by light and electron microscopy. Cryostat sections showed mild fiber size variation but no necrosis. Semithin Epon sections revealed many vacuoles in the muscle cells and fibroblasts. Electron microscopy showed that the vacuoles, presumably lysosomal, had a single limiting membrane and contained finely granular or granulo-reticular material, membranous structures, and electron-dense ovoids. The vacuoles were identical with those in lymphocytes and other cells of patients with mannosidosis. Disorganization of sarcomere alignment and widening of intermyofibrillar spaces were also observed. Deficiency of alpha-D-mannosidase is considered to cause slowly progressing degeneration of muscle fibers.