Gene therapy for aromatic L-amino acid decarboxylase deficiency by MR-guided direct delivery of AAV2-AADC to midbrain dopaminergic neurons.

Aromatic L-amino acid decarboxylase (AADC) deficiency is a rare genetic disorder characterized by deficient synthesis of dopamine and serotonin. It presents in early infancy, and causes severe developmental disability and lifelong motor, behavioral, and autonomic symptoms including oculogyric crises (OGC), sleep disorder, and mood disturbance. We investigated the safety and efficacy of delivery of a viral vector expressing AADC (AAV2-hAADC) to the midbrain in children with AADC deficiency (ClinicalTrials.gov Identifier NCT02852213). Seven (7) children, aged 4-9 years underwent convection-enhanced delivery (CED) of AAV2-hAADC to the bilateral substantia nigra (SN) and ventral tegmental area (VTA) (total infusion volume: 80 µL per hemisphere) in 2 dose cohorts: 1.3 × 1011 vg (n = 3), and 4.2 × 1011 vg (n = 4). Primary aims were to demonstrate the safety of the procedure and document biomarker evidence of restoration of brain AADC activity. Secondary aims were to assess clinical improvement in symptoms and motor function. Direct bilateral infusion of AAV2-hAADC was safe, well-tolerated and achieved target coverage of 98% and 70% of the SN and VTA, respectively. Dopamine metabolism was increased in all subjects and FDOPA uptake was enhanced within the midbrain and the striatum. OGC resolved completely in 6 of 7 subjects by Month 3 post-surgery. Twelve (12) months after surgery, 6/7 subjects gained normal head control and 4/7 could sit independently. At 18 months, 2 subjects could walk with 2-hand support. Both the primary and secondary endpoints of the study were met. Midbrain gene delivery in children with AADC deficiency is feasible and safe, and leads to clinical improvements in symptoms and motor function.

Targeted Treatments for Inherited Neuromuscular Diseases of Childhood.

In the past decade, the number of genes linked to neuromuscular diseases of childhood has expanded dramatically, and this genetic information is forming the basis for gene-specific and even mutation-specific therapies. At the forefront of these advances are the two recently approved treatments for spinal muscular atrophy: one, an antisense oligonucleotide that modifies splicing of the SMN2 gene, and, the other, a gene therapy vector that delivers the SMN1 gene to motor neurons, both of which are allowing patients to acquire developmental milestones previously unseen in this fatal disease. This review highlights these advances and emerging targeted therapies for Duchenne muscular dystrophy and centronuclear myopathy, while also covering enzyme replacement therapy and small molecule-based targeted therapies for conditions such as Pompe's disease and congenital myasthenic syndromes. With these and other newer techniques for targeted correction of genetic defects, such as CRISPR/Cas9, there is now hope that treatments for many more genetic diseases of the nervous system will follow in the near future.

Neuromuscular Diseases of the Newborn.

The peripheral nervous system (PNS) is composed of motor neurons, nerve roots, plexuses, peripheral nerves (motor, sensory and autonomic), neuromuscular junction, and skeletal muscles. Disorders of the PNS in neonates most frequently cause weakness, hypotonia, and contractures, which may be generalized or focal. Since these findings may also occur with brain and spinal cord lesions, key features of the history and neurologic exam, together with diagnostic testing, are helpful in reaching a diagnosis. This review covers the diagnostic approach to PNS disorders in the neonate and includes a discussion of representative diseases of the motor neuron, brachial plexus, peripheral nerves, neuromuscular junction, and muscles. The importance of reaching a precise genetic diagnosis is highlighted with a discussion of current and emerging treatments for neonatal PNS diseases, particularly spinal muscular atrophy.

Treatment of Leukoencephalopathy With Calcifications and Cysts With Bevacizumab.

BACKGROUND: Leukoencephalopathy with calcifications and cysts is a rare, autosomal recessive cerebral microangiopathy that causes progressive white matter disease, calcifications, and cysts within the brain. It is typically associated with slowly progressive psychomotor regression, seizures, and movement disorders. Although leukoencephalopathy with calcifications and cysts affects only the central nervous system, it demonstrates remarkable neuropathologic and radiologic overlap with Coats plus, a disorder of small vessels of the brain, eyes, gastrointestinal tract, and bone. Coats disease without extraocular involvement, a genetically distinct disorder from Coats plus, is characterized by retinal telangiectasias and exudative retinopathy, accompanied by neovascularization. Inhibition of vascular endothelial growth factor (VEGF) signaling with the monoclonal anti-VEGF antibody bevacizumab can improve retinal edema and exudates in Coats disease. Given these observations, we reasoned that VEGF inhibition might also be effective in treating leukoencephalopathy with calcifications and cysts and Coats plus, neither of which has any known therapy. METHODS: We treated an 18-year-old man with leukoencephalopathy with calcifications and cysts using biweekly infusions of the VEGF inhibitor bevacizumab for more than one year and performed clinical examinations and brain imaging at three month intervals. RESULTS: After treatment for more than one year, the patient showed improved bradykinesia and range of motion, and brain magnetic resonance imaging demonstrated a marked reduction in cyst volume and white matter lesions. CONCLUSIONS: Further studies in a cohort of patients are warranted to investigate the efficacy of VEGF inhibition as a treatment for leukoencephalopathy with calcifications and cysts.

Pediatric Hemorrhagic Brainstem Encephalitis Associated With HHV-7 Infection.

BACKGROUND: Human herpesviruses-6 and -7 have been associated with febrile seizures and with encephalitis, the latter predominantly in immunocompromised individuals. Acute hemorrhagic encephalitis is frequently a fatal disease that can occur in the setting of viral infection or can be a postinfectious phenomenon, often with no cause identified. Although hemorrhagic encephalitis has been reported with human herpesvirus-6 infection, only one individual, an immunocompromised child, has been documented with human herpesvirus-7 infection. The role of immunosuppression is not well-established in the management of this rare condition. PATIENT DESCRIPTION: We present an 11-year-old boy with hemorrhagic brainstem encephalitis who underwent extensive infectious and autoimmune testing, positive only for human herpesvirus-7 in the cerebrospinal fluid. The patient recovered after treatment with intravenous immunoglobulin, high-dose steroids, and plasma exchange. CONCLUSION: This is the first report of hemorrhagic brainstem encephalitis with human herpesvirus-7 in a previously healthy individual, adding to existing reports of late-onset human herpesvirus-7 infection associated with encephalitis in children. It also underscores that aggressive immunosuppression may be used early in the course of this disorder and may be beneficial for recovery.

Relapse severity and recovery in early pediatric multiple sclerosis.

BACKGROUND: Factors determining severity and recovery of early demyelinating events in pediatric multiple sclerosis (MS) patients are unknown. OBJECTIVE: The objective of this study was to characterize the severity and recovery of early demyelinating events in pediatric MS. METHODS: Multivariate logistic regression was performed to determine predictors of severe (versus mild/moderate) relapses and poor or fair (versus complete) recovery in patients aged 18 years or less with MS or clinically isolated syndrome (CIS). RESULTS: Optic nerve involvement (OR 4.30, 95% CI 1.50-12.3, p = 0.007) was associated with a severe initial demyelinating event (IDE), while non-White race (OR 2.55, 95% CI 0.87-7.49, p = 0.088), localization to the cerebral hemispheres (OR 7.94, 95% CI 0.86-73.8, p = 0.068), or encephalopathy (OR 8.70, 95% CI 0.86-88.0, p = 0.067) showed a trend towards increased IDE severity. A similar association with race was found for severe second events. A severe IDE (OR 6.90, 95% CI 2.47-19.3, p < 0.001) was associated with incomplete IDE recovery, with similar trends for second and third events. Incomplete recovery from the first event predicted incomplete second event recovery (OR 3.36, 95% CI 0.98-11.6, p = 0.055). CONCLUSIONS: These results may help identify children at risk for a more aggressive disease course.

Microtubule plus-end-tracking proteins target gap junctions directly from the cell interior to adherens junctions.

Gap junctions are intercellular channels that connect the cytoplasms of adjacent cells. For gap junctions to properly control organ formation and electrical synchronization in the heart and the brain, connexin-based hemichannels must be correctly targeted to cell-cell borders. While it is generally accepted that gap junctions form via lateral diffusion of hemichannels following microtubule-mediated delivery to the plasma membrane, we provide evidence for direct targeting of hemichannels to cell-cell junctions through a pathway that is dependent on microtubules; through the adherens-junction proteins N-cadherin and beta-catenin; through the microtubule plus-end-tracking protein (+TIP) EB1; and through its interacting protein p150(Glued). Based on live cell microscopy that includes fluorescence recovery after photobleaching (FRAP), total internal reflection fluorescence (TIRF), deconvolution, and siRNA knockdown, we propose that preferential tethering of microtubule plus ends at the adherens junction promotes delivery of connexin hemichannels directly to the cell-cell border. These findings support an unanticipated mechanism for protein delivery to points of cell-cell contact.

SK channels mediate NADPH oxidase-independent reactive oxygen species production and apoptosis in granulocytes.

Neutrophils are immune cells that bind to, engulf, and destroy bacterial and fungal pathogens in infected tissue, and their clearance by apoptosis is essential for the resolution of inflammation. Killing involves both oxidative and nonoxidative processes, the oxidative pathway requiring electrogenic production of superoxide by the membrane-bound NADPH oxidase complex. A variety of stimuli, from bacterial chemotactic peptides to complement- or IgG-opsonized microbes, can induce the production of reactive oxygen species (ROS) by neutrophils, presumably by means of NADPH oxidase. We report here that 1-ethyl-2-benzimidazolinone (1-EBIO), an activator of Ca2+-activated potassium channels of small conductance (SK) and intermediate conductance (IK), causes production of superoxide and hydrogen peroxide by neutrophils and granulocyte-differentiated PLB-985 cells. This response can be partially inhibited by the SK blocker apamin, which inhibits a Ca2+-activated K+ current in these cells. Analysis of RNA transcripts indicates that channels encoded by the SK3 gene carry this current. The effects of 1-EBIO and apamin are independent of the NADPH oxidase pathway, as demonstrated by using a PLB-985 cell line lacking the gp91phox subunit. Rather, 1-EBIO and apamin modulate mitochondrial ROS production. Consistent with the enhanced ROS production and K+ efflux mediated by 1-EBIO, we found that this SK opener increased apoptosis of PLB-985 cells. Together, these findings suggest a previously uncharacterized mechanism for the regulation of neutrophil ROS production and programmed cell death.