Lysosomal and network alterations in human mucopolysaccharidosis type VII iPSC-derived neurons.

Mucopolysaccharidosis type VII (MPS VII) is a lysosomal storage disease caused by deficient ß-glucuronidase (ß-gluc) activity. Significantly reduced ß-gluc activity leads to accumulation of glycosaminoglycans (GAGs) in many tissues, including the brain. Numerous combinations of mutations in GUSB (the gene that codes for ß-gluc) cause a range of neurological features that make disease prognosis and treatment challenging. Currently, there is little understanding of the molecular basis for MPS VII brain anomalies. To identify a neuronal phenotype that could be used to complement genetic analyses, we generated two iPSC clones derived from skin fibroblasts of an MPS VII patient. We found that MPS VII neurons exhibited reduced ß-gluc activity and showed previously established disease-associated phenotypes, including GAGs accumulation, expanded endocytic compartments, accumulation of lipofuscin granules, more autophagosomes, and altered lysosome function. Addition of recombinant ß-gluc to MPS VII neurons, which mimics enzyme replacement therapy, restored disease-associated phenotypes to levels similar to the healthy control. MPS VII neural cells cultured as 3D neurospheroids showed upregulated GFAP gene expression, which was associated with astrocyte reactivity, and downregulation of GABAergic neuron markers. Spontaneous calcium imaging analysis of MPS VII neurospheroids showed reduced neuronal activity and altered network connectivity in patient-derived neurospheroids compared to a healthy control. These results demonstrate the interplay between reduced ß-gluc activity, GAG accumulation and alterations in neuronal activity, and provide a human experimental model for elucidating the bases of MPS VII-associated cognitive defects.

[Is there a risk of zoonotic disease due to adenoviruses?]. / Les adénovirus non-humains - Un risque zoonotique ?

Every year brings another round of zoonotic viral infections. Usually they fall under the radar, but the occasional lethal epidemic brings another scare to the public and new urgency to the medical community. The types of these viruses (DNA vs. RNA genomes, enveloped vs. proteinaceous) as well as the preceding host(s) vary. Over the last 20 years, bats have been identified as an enigmatic carrier for several pathogens that have jumped the species barrier and infected humans. Factors that favour the emergence of zoonotic pathogens include the increasing overlap of the human and animal habitats, cultural activities, and the host reservoir. In this context, we asked whether bat and/or nonhuman primate adenoviruses are a risk for human health.

Corrective GUSB transfer to the canine mucopolysaccharidosis VII cornea using a helper-dependent canine adenovirus vector.

Corneal transparency is maintained, in part, by specialized fibroblasts called keratocytes, which reside in the fibrous lamellae of the stroma. Corneal clouding, a condition that impairs visual acuity, is associated with numerous diseases, including mucopolysaccharidosis (MPS) type VII. MPS VII is due to deficiency in ß-glucuronidase (ß-glu) enzymatic activity, which leads to accumulation of glycosaminoglycans (GAGs), and secondary accumulation of gangliosides. Here, we tested the efficacy of canine adenovirus type 2 (CAV-2) vectors to transduce keratocyte in vivo in mice and nonhuman primates, and ex vivo in dog and human corneal explants. Following efficacy studies, we asked if we could treat corneal clouding by the injection a helper-dependent (HD) CAV-2 vector (HD-RIGIE) harboring the human cDNA coding for ß-glu (GUSB) in the canine MPS VII cornea. ß-Glu activity, GAG content, and lysosome morphology and physiopathology were analyzed. We found that HD-RIGIE injections efficiently transduced coxsackievirus adenovirus receptor-expressing keratocytes in the four species and, compared to mock-injected controls, improved the pathology in the canine MPS VII cornea. The key criterion to corrective therapy was the steady controlled release of ß-glu and its diffusion throughout the collagen-dense stroma. These data support the continued evaluation of HD CAV-2 vectors to treat diseases affecting corneal keratocytes.