Long term follow-up after haematopoietic stem cell transplantation for mucopolysaccharidosis type I-H: a retrospective study of 51 patients.

Mucopolysaccharidosis type I-H (MPS I-H) is a rare lysosomal storage disorder caused by α-L-Iduronidase deficiency. Early haematopoietic stem cell transplantation (HSCT) is the sole available therapeutic option to preserve neurocognitive functions. We report long-term follow-up (median 9 years, interquartile range 8-16.5) for 51 MPS I-H patients who underwent HSCT between 1986 and 2018 in France. 4 patients died from complications of HSCT and one from disease progression. Complete chimerism and normal α-L-Iduronidase activity were obtained in 84% and 71% of patients respectively. No difference of outcomes was observed between bone marrow and cord blood stem cell sources. All patients acquired independent walking and 91% and 78% acquired intelligible language or reading and writing. Intelligence Quotient evaluation (n = 23) showed that 69% had IQ ≥ 70 at last follow-up. 58% of patients had normal or remedial schooling and 62% of the 13 adults had good socio-professional insertion. Skeletal dysplasia as well as vision and hearing impairments progressed despite HSCT, with significant disability. These results provide a long-term assessment of HSCT efficacy in MPS I-H and could be useful in the evaluation of novel promising treatments such as gene therapy.

First phenotypic description of a female patient with c.610 T > C variant of GLA: a renal-predominant presentation of Fabry disease.

BACKGROUND: Fabry disease (FD) is an X-linked lysosomal storage disorder due to deficient alpha-galactosidase activity leading to intracellular glycosphingolipid accumulation. Multiple variants have been reported in the GLA gene coding for alpha-galactosidase, and the question of the pathogenicity of rare variants needs to be addressed, especially in patients with mild phenotypes. CASE PRESENTATION: The patient, a 37-year-old female, presented with a persistent proteinuria after an otherwise uncomplicated first pregnancy. Renal biopsy showed both mild mesangial IgA deposits, and a striking vacuolization of podocytes and tubular cells consistent with Fabry disease. On electron microscopy, discrete but characteristic pseudo-myelinic lamellar inclusions were observed in the podocytes' lysosomes. A more detailed physical examination revealed an angiokeratoma, and medical history ancient acroparesthesia. There was no cardiac or cerebral involvement of Fabry disease on magnetic resonance imaging. While blood enzymatic activity of alpha-ga lactosidase was normal in this patient, lysoGb3 was elevated (3 N), and a rare heterozygous variant called c.610 T > C was documented in GLA gene. The patient was treated with an ACE inhibitor, with a rapid decrease in proteinuria. After a 5-year follow-up, her renal function has remained normal, with mild proteinuria, and normal cardiac echography. CONCLUSIONS: We report and phenotypically describe the first case of a Fabry disease female patient carrying the GLA c.610 T > C variant associated with a renal-predominant clinical presentation.

Cornea verticillata and acroparesthesia efficiently discriminate clusters of severity in Fabry disease.

BACKGROUD: Fabry disease (OMIM #301 500), the most prevalent lysosomal storage disease, is caused by enzymatic defects in alpha-galactosidase A (GLA gene; Xq22.1). Fabry disease has historically been characterized by progressive renal failure, early stroke and hypertrophic cardiomyopathy, with a diminished life expectancy. A nonclassical phenotype has been described with an almost exclusive cardiac involvement. Specific therapies with enzyme substitution or chaperone molecules are now available depending on the mutation carried. Numerous clinical and fundamental studies have been conducted without stratifying patients by phenotype or severity, despite different prognoses and possible different pathophysiologies. We aimed to identify a simple and clinically relevant way to classify and stratify patients according to their disease severity. METHODS: Based on data from the French Fabry Biobank and Registry (FFABRY; n = 104; 54 males), we applied unsupervised multivariate statistics to determine clusters of patients and identify clinical criteria that would allow an effective classification of adult patients. Thanks to these criteria and empirical clinical considerations we secondly elaborate a new score that allow the severity stratification of patients. RESULTS: We observed that the absence of acroparesthesia or cornea verticillata is sufficient to classify males as having the nonclassical phenotype. We did not identify criteria that significantly cluster female patients. The classical phenotype was associated with a higher risk of severe renal (HR = 35.1; p <10-3) and cardiac events (HR = 4.8; p = 0.008) and a trend toward a higher risk of severe neurological events (HR = 7.7; p = 0.08) compared to nonclassical males. Our simple, rapid and clinically-relevant FFABRY score gave concordant results with the validated MSSI. CONCLUSION: Acroparesthesia and cornea verticillata are simple clinical criteria that efficiently stratify Fabry patients, defining 3 different groups: females and males with nonclassical and classical phenotypes of significantly different severity. The FFABRY score allows severity stratification of Fabry patients.

Deep characterization of the anti-drug antibodies developed in Fabry disease patients, a prospective analysis from the French multicenter cohort FFABRY.

BACKGROUND: Fabry disease (OMIM #301500) is an X-linked disorder caused by alpha-galactosidase A deficiency with two major clinical phenotypes: classic and non-classic of different prognosis. From 2001, enzyme replacement therapies (ERT) have been available. We aimed to determine the epidemiology and the functional characteristics of anti-drug antibodies. Patients from the French multicenter cohort FFABRY (n = 103 patients, 53 males) were prospectively screened for total anti-agalsidase IgG and IgG subclasses with a home-made enzyme-linked immunosorbent assay (ELISA), enzyme-inhibition assessed with neutralization assays and lysoGb3 plasma levels, and compared for clinical outcomes. RESULTS: Among the patients exposed to agalsidase, 40% of men (n = 18/45) and 8% of women (n = 2/25) had antibodies with a complete cross-reactivity towards both ERTs. Antibodies developed preferentially in men with non-missense GLA mutations (relative risk 2.88, p = 0.006) and classic phenotype (58.6% (17/29) vs 6.7% (1/16), p = 0.0005). Specific anti-agalsidase IgG1 were the most frequently observed (16/18 men), but the highest concentrations were observed for IgG4 (median 1.89 µg/ml, interquartile range (IQR) [0.41-12.24]). In the men exposed to agalsidase, inhibition was correlated with the total IgG titer (r = 0.67, p < 0.0001), especially IgG4 (r = 0.75, p = 0.0005) and IgG2 (r = 0.72, p = 0.001). Inhibition was confirmed intracellularly in Fabry patient leucocytes cultured with IgG-positive versus negative serum (median: 42.0 vs 75.6%, p = 0.04), which was correlated with IgG2 (r = 0.67, p = 0.017, n = 12) and IgG4 levels (r = 0.59, p = 0.041, n = 12). Plasma LysoGb3 levels were correlated with total IgG (r = 0.66, p = 0.001), IgG2 (r = 0.72, p = 0.004), IgG4 (r = 0.58, p = 0.03) and IgG1 (r = 0.55, p = 0.04) titers. Within the classic group, no clinical difference was observed but lysoGb3 levels were higher in antibody-positive patients (median 33.2 ng/ml [IQR 20.6-55.6] vs 12.5 [10.1-24.0], p = 0.005). CONCLUSION: Anti-agalsidase antibodies preferentially develop in the severe classic Fabry phenotype. They are frequently associated with enzyme inhibition and higher lysoGb3 levels. As such, they could be considered as a hallmark of severity associated with the classic phenotype. The distinction of the clinical phenotypes should now be mandatory in studies dealing with Fabry disease and its current and future therapies.

Intravenous administration of scAAV9-Hexb normalizes lifespan and prevents pathology in Sandhoff disease mice.

Sandhoff disease (SD) is a rare inherited disorder caused by a deficiency of ß-hexosaminidase activity which is fatal because no effective treatment is available. A mouse model of Hexb deficiency reproduces the key pathognomonic features of SD patients with severe ubiquitous lysosomal dysfunction, GM2 accumulation, neuroinflammation and neurodegeneration, culminating in death at 4 months. Here, we show that a single intravenous neonatal administration of a self-complementary adeno-associated virus 9 vector (scAAV9) expressing the Hexb cDNA in SD mice is safe and sufficient to prevent disease development. Importantly, we demonstrate for the first time that this treatment results in a normal lifespan (over 700 days) and normalizes motor function assessed by a battery of behavioral tests, with scAAV9-treated SD mice being indistinguishable from wild-type littermates. Biochemical analyses in multiple tissues showed a significant increase in hexosaminidase A activity, which reached 10-15% of normal levels. AAV9 treatment was sufficient to prevent GM2 and GA2 storage almost completely in the cerebrum (less so in the cerebellum), as well as thalamic reactive gliosis and thalamocortical neuron loss in treated Hexb-/- mice. In summary, this study demonstrated a widespread protective effect throughout the entire CNS after a single intravenous administration of the scAAV9-Hexb vector to neonatal SD mice.

A Review of Gaucher Disease Pathophysiology, Clinical Presentation and Treatments.

Gaucher disease (GD, ORPHA355) is a rare, autosomal recessive genetic disorder. It is caused by a deficiency of the lysosomal enzyme, glucocerebrosidase, which leads to an accumulation of its substrate, glucosylceramide, in macrophages. In the general population, its incidence is approximately 1/40,000 to 1/60,000 births, rising to 1/800 in Ashkenazi Jews. The main cause of the cytopenia, splenomegaly, hepatomegaly, and bone lesions associated with the disease is considered to be the infiltration of the bone marrow, spleen, and liver by Gaucher cells. Type-1 Gaucher disease, which affects the majority of patients (90% in Europe and USA, but less in other regions), is characterized by effects on the viscera, whereas types 2 and 3 are also associated with neurological impairment, either severe in type 2 or variable in type 3. A diagnosis of GD can be confirmed by demonstrating the deficiency of acid glucocerebrosidase activity in leukocytes. Mutations in the GBA1 gene should be identified as they may be of prognostic value in some cases. Patients with type-1 GD-but also carriers of GBA1 mutation-have been found to be predisposed to developing Parkinson's disease, and the risk of neoplasia associated with the disease is still subject to discussion. Disease-specific treatment consists of intravenous enzyme replacement therapy (ERT) using one of the currently available molecules (imiglucerase, velaglucerase, or taliglucerase). Orally administered inhibitors of glucosylceramide biosynthesis can also be used (miglustat or eliglustat).

Obstructive sleep apnea syndrome after hematopoietic stem cell transplantation in children with mucopolysaccharidosis type I.

BACKGROUND: Obstructive sleep apnea syndrome (OSAS) is very common in mucopolysaccharidosis I (MPS I). Hematopoietic stem cell transplantation (HSCT) is the preferred treatment for patients with severe MPS I diagnosed early in life. The protective effect of HSCT on the development of long term OSAS is not known. METHODS: Overnight polysomnography (PSG) and biomarker data were analyzed during the annual follow-up in consecutive MPS I patients treated with HSCT. RESULTS: The data of 13 patients (6 boys) were analyzed. Median age at HSCT was 17 (range 14-19) months, median age at PSG was 9.0 (4.5-14.5) years, and median time elapsed since HSCT was 7.6 (2.4-13.2) years. A significant correlation was observed between time elapsed since HSCT and the apnea-hypopnea index (AHI, r(2)=0.493, p=+0.003) and the oxygen desaturation index (r(2)=0.424, p=+0.02). Patients older than 10 years of age had a higher mean AHI (25.8/h vs 1.4/h, p=0.0008), a lower mean pulse oximetry (94.7% vs 97.2%, p=0.01) and a higher mean hypopnea index (18.8 vs 0.71/h, p=0.016) as compared to those younger than 10 years of age. No correlation was observed between the AHI and the metabolic clearance, assessed by urine glycosaminoglycan (GAG) excretion and residual enzyme activity, although there was a positive trend for the urinary GAG/higher normal value for age ratio (p=0.09). CONCLUSION: HSCT does not offer long term protection against OSAS in MPS I with OSAS being documented in all patients after a time elapse since HSCT exceeding 10 years. The potential benefit of additional enzyme replacement therapy needs to be assessed.

Neuroblastoma Amplified Sequence (NBAS) mutation in recurrent acute liver failure: Confirmatory report in a sibship with very early onset, osteoporosis and developmental delay.

BACKGROUND: Recently, biallelic mutations in the Neuroblastoma Amplified Sequence NBAS gene have been identified in ten patients that present recurrent acute liver failure (RALF) in early infancy. In addition to severe liver dysfunction, some of these individuals also suffered from other comorbidities including cardiomyopathy, neurologic phenotypes and gastrointestinal immune defects. Here we report on a consanguineous Lebanese family with three siblings affected by RALF. Of note, neonatal spontaneous fractures, developmental delay, prominent eyes, generalized hirsutism, gum hypertrophy, and hepato-splenomegaly ​were also present. METHODS: Whole-genome SNP genotyping in all the patients, followed by exome sequencing was performed in one of the affected siblings. RESULTS: A homozygous c.409C > T (p.Arg137Trp) missense mutation in NBAS was identified in all patients. CONCLUSION: Overall, our findings confirm the involvement of NBAS in the pathogenesis of this condition characterized by severe liver dysfunction and help expand its phenotypical spectrum.

A prospective study of bone marrow hematopoietic and mesenchymal stem cells in type 1 Gaucher disease patients.

Gaucher disease (GD) is an autosomal recessive disorder characterized by lysosomal glucocerebrosidase (GBA) deficiency leading to hematological and skeletal manifestations. Mechanisms underlying these symptoms have not yet been elucidated. In vivo, bone marrow (BM) mesenchymal stem cells (MSCs) have important role in the regulation of bone mass and in the support of hematopoiesis, thus representing potential candidate that could contribute to the disease. GBA deficiency may also directly impair hematopoietic stem/progenitors cells (HSPCs) intrinsic function and induce hematological defect. In order to evaluate the role of BM stem cells in GD pathophysiology, we prospectively analyzed BM-MSCs and HSPCs properties in a series of 10 patients with type 1 GD. GBA activity was decreased in all tested cell subtypes. GD-MSCs had an impaired growth potential, morphological and cell cycle abnormalities, decreased capacities to differentiate into osteoblasts. Moreover, GD-MSCs secreted soluble factors that stimulated osteoclasts resorbing activities. In vitro and in vivo primitive and mature hematopoiesis were similar between patients and controls. However, GD-MSCs had a lower hematopoietic supportive capacity than those from healthy donors. These data suggest that BM microenvironment is altered in GD and that MSCs are key components of the manifestations observed in GD.

Defects of Vps15 in skeletal muscles lead to autophagic vacuolar myopathy and lysosomal disease.

The complex of Vacuolar Protein Sorting 34 and 15 (Vps34 and Vps15) has Class III phosphatidylinositol 3-kinase activity and putative roles in nutrient sensing, mammalian Target Of Rapamycin (mTOR) activation by amino acids, cell growth, vesicular trafficking and autophagy. Contrary to expectations, here we show that Vps15-deficient mouse tissues are competent for LC3-positive autophagosome formation and maintain mTOR activation. However, an impaired lysosomal function in mutant cells is traced by accumulation of adaptor protein p62, LC3 and Lamp2 positive vesicles, which can be reverted to normal levels after ectopic overexpression of Vps15. Mice lacking Vps15 in skeletal muscles, develop a severe myopathy. Distinct from the autophagy deficient Atg7(-/-) mutants, pathognomonic morphological hallmarks of autophagic vacuolar myopathy (AVM) are observed in Vps15(-/-) mutants, including elevated creatine kinase plasma levels, accumulation of autophagosomes, glycogen and sarcolemmal features within the fibres. Importantly, Vps34/Vps15 overexpression in myoblasts of Danon AVM disease patients alleviates the glycogen accumulation. Thus, the activity of the Vps34/Vps15 complex is critical in disease conditions such as AVMs, and possibly a variety of other lysosomal storage diseases.

The French Gaucher's disease registry: clinical characteristics, complications and treatment of 562 patients.

BACKGROUND: Clinical features, complications and treatments of Gaucher's disease (GD), a rare autosomal-recessive disorder due to a confirmed lysosomal enzyme (glucocerebrosidase) deficiency, are described. METHODS: All patients with known GD, living in France, with ≥ 1 consultations (1980-2010), were included in the French GD registry, yielding the following 4 groups: the entire cohort, with clinical description; and its subgroups: patients with ≥ 1 follow-up visits, to investigate complications; recently followed (2009-2010) patients; and patients treated during 2009-2010, to examine complications before and during treatment. Data are expressed as medians (range) for continuous variables and numbers (%) for categorical variables. RESULTS: Among the 562 registry patients, 265 (49.6%) were females; 454 (85.0%) had type 1, 22 (4.1%) type 2, 37 (6.9%) perinatal-lethal type and 21 (3.9%) type 3. Median ages at first GD symptoms and diagnosis, respectively, were 15 (0-77) and 22 (0-84) years for all types. The first symptom diagnosing GD was splenomegaly and/or thrombocytopenia (37.6% and 26.3%, respectively). Bone-marrow aspiration and/or biopsy yielded the diagnosis for 54.7% of the patients, with enzyme deficiency confirming GD for all patients. Birth incidence rate was estimated at 1/50,000 and prevalence at 1/136,000. For the 378 followed patients, median follow-up was 16.2 (0.1-67.6) years. Major clinical complications were bone events (BE; avascular necrosis, bone infarct or pathological fracture) for 109 patients, splenectomy for 104, and Parkinson's disease for 14; 38 patients died (neurological complications for 15 type-2 and 3 type-3 patients, GD complications for 11 type-1 and another disease for 9 type-1 patients). Forty-six had monoclonal gammopathy. Among 283 recently followed patients, 36 were untreated and 247 had been treated during 2009-2010; 216 patients received treatment in December 2010 (126 with imiglucerase, 45 velaglucerase, 24 taliglucerase, 21 miglustat). BE occurred before (130 in 67 patients) and under treatment (60 in 41 patients) with respective estimated frequencies (95% CI) of first BE at 10 years of 20.3% (14.1%-26.5%) and 19.8% (13.5%-26.1%). CONCLUSION: This registry enabled the epidemiological description of GD in France and showed that BE occur even during treatment.

A new lysosomal storage disorder resembling Morquio syndrome in sibs.

We report two male sibs, born from unrelated French Caribbean parents, presenting with an unclassifiable storage disorder. Pregnancy and delivery were uneventful. Stunted growth was noted during the first year of life. Both children have short stature (below - 4SD) with short trunk, barrel chest, micromelia with rhizomelic shortening, severe kyphoscoliosis, pectus carinatum, short hands and feet with metatarsus adductus, and excessive joint laxity of the small joints. Learning difficulties with borderline intelligence quotient (IQ) were noted in one of them. They had no hepatomegaly, no splenomegaly, and no dysmorphism. Skeletal X-rays survey demonstrated generalized platyspondyly with tongue-like deformity of the anterior part of the vertebral bodies, hypoplasia of the odontoid process, generalized epiphyseal dysplasia and abnormally shaped metaphyses. The acetabular roofs had a trident aspect. Ophthalmologic and cardiac examinations were normal. Spine deformity required surgical correction in one of the patient at age 4 years. Lysosomal enzymes assays including N-acetylgalactosamine-6-sulfate sulfatase and ß-galactosidase were normal, excluding mucopolysaccharidoses type IV A and IV B (Morquio syndrome), respectively. Qualitative analysis found traces of dermatan and chondroitin-sulfates in urine, but quantitative glycosaminoglycan excretion fell within normal limits. They were no vacuolated lymphocytes. Abnormal coarse inclusions were present in eosinophils. Mild Alder anomaly was observed in polymorphonuclears. Granulations were discretely metachromatic with toluidine blue. Those morphological anomalies are in favor of a lysosomal storage disease. No inclusions were found in skin fibroblasts. We hypothesize that these two boys have a distinct autosomal recessive or X-linked lysosomal storage disorder of unknown origin that shares clinical and radiological features with Morquio disease.

Bone marrow microenvironment in an in vitro model of Gaucher disease: consequences of glucocerebrosidase deficiency.

Gaucher disease (GD) is a lysosomal storage disorder due to glucocerebrosidase (GBA) deficiency. Mechanisms leading to the emergence of hematological and skeletal manifestations observed in GD are poorly explained. Bone marrow (BM) mesenchymal stem cells (MSCs) are multipotent progenitors that participate in the regulation of bone mass. MSCs should thus represent a cell population involved in the development or progression of bone disease in GD. In a chemical model of GD obtained with Conduritol ß epoxide (CBE), a specific inhibitor of GBA activity, we functionally characterized BM MSCs and specifically analyzed their capacity to differentiate into osteoblasts. GBA deficiency obtained with CBE treatment, leads to a dramatic impairment of MSCs proliferation and to morphological abnormalities. Although the capacity of MSCs to differentiate into osteoblasts was not modified, the levels of several soluble factors that regulate bone metabolism were increased in MSCs treated with CBE, compared with untreated MSCs. Moreover, addition of conditioned media from CBE-treated MSCs on monocyte-derived osteoclasts cultured on bone matrix leads to an increase of resorption areas. These data suggested that, in GD, MSCs represents a stem cell population that is likely to be involved in bone pathogenesis.

Lentiviral vector delivery of shRNA into cultured primary myogenic cells: a tool for therapeutic target validation.

RNA interference has emerged as a powerful technique to down-regulate gene expression. The lentiviral vector-mediated expression of small hairpin RNAs (shRNAs) from polymerase III promoters allows permanent down-regulation of a specific gene in a wide range of cell types both in vitro and in vivo. In this chapter, we describe a method permitting the expression of shRNA from lentiviral vectors in primary murine myogenic cells. We designed shRNAs targeted to the muscular glycogen synthase isoform (shGYS1), a highly regulated enzyme responsible for glycogen synthesis, in order to modulate the muscle glycogen biosynthetic pathway and to improve the phenotype in primary myogenic cells from a murine model of glycogen storage disease type II (GSDII). This method based on shRNA-mediated down-regulation could be applied to other muscular disorders to evaluate new therapeutic options.

Glucocerebrosidase deficiency dramatically impairs human bone marrow haematopoiesis in an in vitro model of Gaucher disease.

One of the cardinal symptoms of type 1 Gaucher Disease (GD) is cytopenia, usually explained by bone marrow (BM) infiltration by Gaucher cells and hypersplenism. However, some cases of cytopenia in splenectomized or treated patients suggest possible other mechanisms. To evaluate intra-cellular glucocerebrosidase (GlcC) activity in immature progenitors and to prove the conduritol B epoxide (CBE)-induced inhibition of the enzyme, we used an adapted flow cytometric technique before assessing the direct effect of GlcC deficiency in functional assays. Among haematopoietic cells from healthy donors, monocytes showed the highest GlcC activity but immature CD34(+) and mesenchymal cells also had significant GlcC activity. CBE greatly inhibited the enzyme activity of all cell categories. GlcC-deficient CD34(+) cells showed impaired ability to proliferate and differentiate in the expansion assay and had lower frequency of erythroid burst-forming units, granulocyte colony-forming units (CFU) and macrophage CFU progenitors, but the effect of GlcC deficiency on megakaryocyte CFU lineage was not significant. GlcC deficiency strongly impaired primitive haematopoiesis in long-term culture. Furthermore, GlcC deficiency progressively impaired proliferation of mesenchymal progenitors. These data suggest an intrinsic effect of GlcC deficiency on BM immature cells that supplements the pathophysiology of GD and opens new perspectives of therapeutic approach.

Rigid spine syndrome revealing late-onset Pompe disease.

The authors describe a 50-year-old man who was evaluated for a rigid spine syndrome with onset at age 15, and subsequent walking difficulties. Cardiac and pulmonary functions were normal. Deltoid biopsy revealed the presence of small vacuoles and increased glycogen with Periodic Acid Schiff staining in a limited number of fibers. Acid alpha-glucosidase staining was decreased in leucocytes, and genetic analysis identified the presence of two mutations in that gene. This observation suggests that Pompe disease should be considered in the differential diagnosis of rigid spine syndrome, even in patients without respiratory involvement or with a muscle biopsy showing only mild histopathological changes.

Partial phenotypic correction and immune tolerance induction to enzyme replacement therapy after hematopoietic stem cell gene transfer of alpha-glucosidase in Pompe disease.

BACKGROUND: Glycogen storage disease type II (GSDII) or Pompe disease is an inherited disease of glycogen metabolism caused by a lack of functional lysosomal acid alpha-glucosidase (GAA). Affected individuals store glycogen in lysosomes resulting in fatal hypertrophic cardiomyopathy and respiratory failure in the most severe form. Even if enzyme replacement therapy (ERT) has already proven some efficacy, its results remain heterogeneous in skeletal muscle, especially in cross reactive immunological material (CRIM)-negative patients. We investigated for the first time the use of hematopoietic stem cell (HSC) gene therapy in a murine model of GSDII. METHODS: Deficient HSC were transduced with a lentiviral vector expressing human GAA or enhanced green fluorescent protein (GFP) under the control of the retroviral MND promoter and transplanted into lethally irradiated GSDII mice. Animals were then subjected to an ERT protocol for 5 weeks and monitored for metabolic correction and GAA-induced immune reaction. RESULTS: GAA was expressed as a correctly processed protein, allowing a complete enzymatic correction in transduced deficient cells without toxicity. Seventeen weeks after transplantation, a partial restoration of the GAA enzymatic activity was observed in bone marrow and peripheral blood cells of GSDII mice, allowing a significant glycogen clearance in skeletal muscle. ERT induced a robust antibody response in GFP-transplanted mice, whereas no immune reaction could be detected in GAA-transplanted mice. CONCLUSIONS: Lentiviral vector-mediated HSC gene therapy leads to a partial metabolic correction and induces a tolerance to ERT in GSDII mice. This strategy could enhance the efficacy of ERT in CRIM-negative Pompe patients.

Lysosomal serine protease CLN2 regulates tumor necrosis factor-alpha-mediated apoptosis in a Bid-dependent manner.

Apoptosis is a highly organized, energy-dependent program by which multicellular organisms eliminate damaged, superfluous, and potentially harmful cells. Although caspases are the most prominent group of proteases involved in the apoptotic process, the role of lysosomes has only recently been unmasked. This study investigated the role of the lysosomal serine protease CLN2 in apoptosis. We report that cells isolated from patients affected with late infantile neuronal ceroid lipofuscinosis (LINCL) having a deficient activity of CLN2 are resistant to the toxic effect of death ligands such as tumor necrosis factor (TNF), CD95 ligand, or tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) but not to receptor-independent stress agents. CLN2-deficient cells exhibited a defect in TNF-induced Bid cleavage, release of cytochrome c, and caspase-9 and -3 activation. Moreover, extracts from CLN2-overexpressing cells or a CLN2 recombinant protein were able to catalyze the in vitro cleavage of Bid. Noteworthy, correction of the lysosomal enzyme defect of LINCL fibroblasts using a medium enriched in CLN2 protein enabled restoration of TNF-induced Bid and caspase-3 processing and toxicity. Conversely, transfection of CLN2-corrected cells with small interfering RNA targeting Bid abrogated TNF-induced cell death. Altogether, our study demonstrates that genetic deletion of the lysosomal serine protease CLN2 and the subsequent loss of its catalytic function confer resistance to TNF in non-neuronal somatic cells, indicating that CLN2 plays a yet unsuspected role in TNF-induced cell death.

Modulation of glycogen synthesis by RNA interference: towards a new therapeutic approach for glycogenosis type II.

Glycogen storage disease type II (GSDII) or Pompe disease is an autosomal recessive disorder caused by defects in the acid alpha-glucosidase gene, which leads to lysosomal glycogen accumulation and enlargement of the lysosomes mainly in cardiac and muscle tissues, resulting in fatal hypertrophic cardiomyopathy and respiratory failure in the most severely affected patients. Enzyme replacement therapy has already proven to be beneficial in this disease, but correction of pathology in skeletal muscle still remains a challenge. As substrate deprivation was successfully used to improve the phenotype in other lysosomal storage disorders, we explore here a novel therapeutic approach for GSDII based on a modulation of muscle glycogen synthesis. Short hairpin ribonucleic acids (shRNAs) targeted to the two major enzymes involved in glycogen synthesis, i.e. glycogenin (shGYG) and glycogen synthase (shGYS), were selected. C2C12 cells and primary myoblasts from GSDII mice were stably transduced with lentiviral vectors expressing both the shRNAs and the enhanced green fluorescent protein (EGFP) reporter gene. Efficient and specific inhibition of GYG and GYS was associated not only with a decrease in cytoplasmic and lysosomal glycogen accumulation in transduced cells, but also with a strong reduction in the lysosomal size, as demonstrated by confocal microscopy analysis. A single intramuscular injection of recombinant AAV-1 (adeno-associated virus-1) vectors expressing shGYS into newborn GSDII mice led to a significant reduction in glycogen accumulation, demonstrating the in vivo therapeutic efficiency. These data offer new perspectives for the treatment of GSDII and could be relevant to other muscle glycogenoses.

The pulvinar sign: frequency and clinical correlations in Fabry disease.

UNLABELLED: Fabry disease is an X-linked lysosomal deficiency of alpha-galactosidase A that results in cellular accumulation of galactoconjugates, mainly globotriaosylceramide, particularly in blood vessels. Neuroradiological findings include ischemic stroke, white matter lesions, vascular abnormalities (vertebrobasilar dolichoectasia and vessel tortuosity), and posterior thalamus involvement (the so called pulvinar sign). The purpose of our study was to investigate the presence of the increased pulvinar signal intensity on T1-weighted imaging - pulvinar sign and its relationship with other clinical findings, in a non-selected cohort of Fabry patients. METHODS: We performed a prospective analysis of two populations of patients (36 subjects) with Fabry disease. Patients were followed-up at the Department of Internal Medicine of the Bichat Hospital in Paris (France) and at the Neurological Clinic of the University Hospital of Padova (Italy). Brain MR studies of each patient included T1- and T2- weighted images, FLAIR sequences, and in some cases diffusion weighted images. RESULTS: A total of 36 patients (16 males, 20 females) were investigated in 14 families. The pulvinar sign was found in 5 male patients, but not in female patients. Seven patients had had at least one stroke (territorial or lacunar). There was no correlation between stroke and the pulvinar sign. All patients with the pulvinar sign had hypertrophic cardiomyopathy. Four patients out of five with the pulvinar sign were on dialysis or had a kidney transplantation. CONCLUSIONS: Our findings suggest that the pulvinar sign is a highly specific sign of Fabry disease, found in male patients with cardiac signs and severe kidney involvement.