Neuroscience
Abstract
BACKGROUND Spinal muscular atrophy (SMA) is caused by deficient expression of survival motor neuron (SMN) protein. New SMN-enhancing therapeutics are associated with variable clinical benefits. Limited knowledge of baseline and drug-induced SMN levels in disease-relevant tissues hinders efforts to optimize these treatments.METHODS SMN mRNA and protein levels were quantified in human tissues isolated during expedited autopsies.RESULTS SMN protein expression varied broadly among prenatal control spinal cord samples, but was restricted at relatively low levels in controls and SMA patients after 3 months of life. A 2.3-fold perinatal decrease in median SMN protein levels was not paralleled by comparable changes in SMN mRNA. In tissues isolated from nusinersen-treated SMA patients, antisense oligonucleotide (ASO) concentration and full-length (exon 7 including) SMN2 (SMN2-FL) mRNA level increases were highest in lumbar and thoracic spinal cord. An increased number of cells showed SMN immunolabeling in spinal cord of treated patients, but was not associated with an increase in whole-tissue SMN protein levels.CONCLUSIONS A normally occurring perinatal decrease in whole-tissue SMN protein levels supports efforts to initiate SMN-inducing therapies as soon after birth as possible. Limited ASO distribution to rostral spinal and brain regions in some patients likely limits clinical response of motor units in these regions for those patients. These results have important implications for optimizing treatment of SMA patients and warrant further investigations to enhance bioavailability of intrathecally administered ASOs.FUNDING SMA Foundation, SMART, NIH (R01-NS09677, R01-NS062269), Ionis Pharmaceuticals, and PTC Therapeutics. Biogen provided support for absolute real-time RT-PCR.
Authors
Daniel M. Ramos, Constantin d’Ydewalle, Vijayalakshmi Gabbeta, Amal Dakka, Stephanie K. Klein, Daniel A. Norris, John Matson, Shannon J. Taylor, Phillip G. Zaworski, Thomas W. Prior, Pamela J. Snyder, David Valdivia, Christine L. Hatem, Ian Waters, Nikhil Gupte, Kathryn J. Swoboda, Frank Rigo, C. Frank Bennett, Nikolai Naryshkin, Sergey Paushkin, Thomas O. Crawford, Charlotte J. Sumner
Abstract
Multiple sclerosis (MS) is a disabling disease of the CNS. Inflammatory features of MS include lymphocyte accumulations in the CNS and cerebrospinal fluid (CSF). The preclinical events leading to established MS are still enigmatic. Here we compared gene expression patterns of CSF cells from MS-discordant monozygotic twin pairs. Six “healthy” co-twins, who carry a maximal familial risk for developing MS, showed subclinical neuroinflammation (SCNI) with small MRI lesions. Four of these subjects had oligoclonal bands (OCBs). By single-cell RNA sequencing of 2752 CSF cells, we identified clonally expanded CD8+ T cells, plasmablasts, and, to a lesser extent, CD4+ T cells not only from MS patients but also from subjects with SCNI. In contrast to nonexpanded T cells, clonally expanded T cells showed characteristics of activated tissue-resident memory T (TRM) cells. The TRM-like phenotype was detectable already in cells from SCNI subjects but more pronounced in cells from patients with definite MS. Expanded plasmablast clones were detected only in MS and SCNI subjects with OCBs. Our data provide evidence for very early concomitant activation of 3 components of the adaptive immune system in MS, with a notable contribution of clonally expanded TRM-like CD8+ cells.
Authors
Eduardo Beltrán, Lisa Ann Gerdes, Julia Hansen, Andrea Flierl-Hecht, Stefan Krebs, Helmut Blum, Birgit Ertl-Wagner, Frederik Barkhof, Tania Kümpfel, Reinhard Hohlfeld, Klaus Dornmair
Abstract
Gene therapy approaches are being deployed to treat recessive genetic disorders by restoring the expression of mutated genes. However, the feasibility of these approaches for dominantly-inherited diseases—where treatment may require reduction in the expression of a toxic mutant protein resulting from a gain-of-function (GoF) allele—is unclear. Here we show the efficacy of allele-specific RNAi as a potential therapeutic for Charcot-Marie-Tooth type 2D (CMT2D), caused by dominant mutations in glycyl tRNA-synthetase (GARS). A de novo mutation in GARS was identified in a patient with a severe peripheral neuropathy, and a mouse model precisely recreating the mutation was produced. These mice developed a neuropathy by 3-4 weeks-of-age, validating the pathogenicity of the mutation. RNAi sequences targeting mutant GARS mRNA, but not wild-type, were optimized and then packaged into AAV9 for in vivo delivery. This almost completely prevented the neuropathy in mice treated at birth. Delaying treatment until after disease onset showed modest benefit, though this effect decreased the longer treatment was delayed. These outcomes were reproduced in a second mouse model of CMT2D using a vector specifically targeting that allele. The effects were dose dependent, and persisted for at least one year. Our findings demonstrate the feasibility of AAV9-mediated allele-specific knockdown and provide proof-of-concept for gene therapy approaches for dominant neuromuscular diseases.
Authors
Kathryn H. Morelli, Laurie B. Griffin, Nettie K. Pyne, Lindsay M. Wallace, Allison M. Fowler, Stephanie N. Oprescu, Ryuichi Takase, Na Wei, Rebecca Meyer-Schuman, Dattatreya Mellacheruvu, Jacob O. Kitzman, Samuel G. Kocen, Timothy J. Hines, Emily L. Spaulding, James R. Lupski, Alexey Nesvizhskii, Pedro Mancias, Ian J. Butler, Xiang-Lei Yang, Ya-Ming Hou, Anthony Antonellis, Scott Q. Harper, Robert W. Burgess
Abstract
Arcuate nucleus agouti-related peptide (AgRP) neurons play a central role in feeding and are under complex regulation by both homeostatic hormonal and nutrient signals and hypothalamic neuronal pathways. Feeding may also be influenced by environmental cues, sensory inputs and other behaviors implying the involvement of higher brain regions. However, whether such pathways modulate feeding through direct synaptic control of AgRP neuron activity is unknown. Here we show that nociceptin-expressing neurons in the anterior bed nuclei of the stria terminalis (aBNST) make direct GABAergic inputs onto AgRP neurons. We found that activation of these neurons inhibited AgRP neurons and feeding. Activity of these neurons increased upon food availability and their ablation resulted in obesity. Furthermore, these neurons received afferent inputs from a range of upstream brain regions as well as hypothalamic nuclei. Therefore, aBNST nociceptin/GABAergic neurons may act as a gateway to feeding behavior by connecting AgRP neurons to both homeostatic and non-homeostatic neuronal inputs.
Authors
Mark A. Smith, Agharul I. Choudhury, Justyna A. Glegola, Paulius Viskaitis, Elaine E. Irvine, Pedro Caldas Custodio de Campos Silva, Sanjay Khadayate, Hanns Ulrich Zeilhofer, Dominic J. Withers
Abstract
Parkinson’s disease (PD) is a common neurodegenerative disease that lacks therapies to prevent progressive neurodegeneration. Impaired energy metabolism and reduced ATP levels are common features of PD. Previous studies revealed that terazosin (TZ) enhances the activity of phosphoglycerate kinase 1 (PGK1), thereby stimulating glycolysis and increasing cellular ATP levels. Therefore, we asked whether enhancement of PGK1 activity would change the course of PD. In toxin-induced and genetic PD models in mice, rats, flies, and induced pluripotent stem cells, TZ increased brain ATP levels and slowed or prevented neuron loss. The drug increased dopamine levels and partially restored motor function. Because TZ is prescribed clinically, we also interrogated 2 distinct human databases. We found slower disease progression, decreased PD-related complications, and a reduced frequency of PD diagnoses in individuals taking TZ and related drugs. These findings suggest that enhancing PGK1 activity and increasing glycolysis may slow neurodegeneration in PD.
Authors
Rong Cai, Yu Zhang, Jacob E. Simmering, Jordan L. Schultz, Yuhong Li, Irene Fernandez-Carasa, Antonella Consiglio, Angel Raya, Philip M. Polgreen, Nandakumar S. Narayanan, Yanpeng Yuan, Zhiguo Chen, Wenting Su, Yanping Han, Chunyue Zhao, Lifang Gao, Xunming Ji, Michael J. Welsh, Lei Liu
Abstract
Angelman syndrome (AS) is a neurodevelopmental disorder characterized by intellectual disability, lack of speech, ataxia, EEG abnormalities, and epilepsy. Seizures in AS individuals are common, debilitating, and often drug-resistant. Therefore, there is an unmet need for better treatment options. Cannabidiol (CBD), a major phytocannabinoid constituent of cannabis, has antiseizure activity and behavioral benefits in preclinical and clinical studies for some disorders associated with epilepsy, suggesting that the same could be true for AS. Here we show that acute CBD (100 mg/kg) attenuated hyperthermia- and acoustically-induced seizures in a mouse model of AS. However, neither acute CBD nor a two-weeklong course of CBD administered immediately after a kindling protocol could halt the pro-epileptogenic plasticity observed in AS model mice. CBD had a dose-dependent sedative effect, but did not have an impact on motor performance. CBD abrogated the enhanced intracortical local field potential power, including delta and theta rhythms observed in AS model mice, indicating that CBD administration could also help normalize the EEG deficits observed in individuals with AS. Our results provide critical preclinical evidence supporting CBD treatment of seizures and alleviation of EEG abnormalities in AS, and will thus help guide the rational development of CBD as an AS treatment.
Authors
Bin Gu, Manhua Zhu, Madison R. Glass, Marie Rougié, Viktoriya D. Nikolova, Sheryl S. Moy, Paul R. Carney, Benjamin D. Philpot
Abstract
Growing evidence shows that alterations occurring at early developmental stages contribute to symptoms manifested in adulthood in the setting of neurodegenerative diseases. Here, we studied the molecular mechanisms causing giant axonal neuropathy (GAN), a severe neurodegenerative disease due to loss-of-function of the gigaxonin-E3 ligase. We showed that gigaxonin governs Sonic Hedgehog (Shh) induction, the developmental pathway patterning the dorso-ventral axis of the neural tube and muscles, by controlling the degradation of the Shh-bound Patched receptor. Similarly to Shh inhibition, repression of gigaxonin in zebrafish impaired motor neuron specification and somitogenesis and abolished neuromuscular junction formation and locomotion. Shh signaling was impaired in gigaxonin null zebrafish and was corrected by both pharmacological activation of the Shh pathway and human gigaxonin, pointing to an evolutionary-conserved mechanism regulating Shh signaling. Gigaxonin-dependent inhibition of Shh activation was also demonstrated in primary fibroblasts from GAN patients and in a Shh activity reporter line depleted in gigaxonin. Our findings establish gigaxonin as a key E3 ligase that positively controls the initiation of Shh transduction, reveal the causal role of Shh dysfunction in motor deficits, thus highlighting the developmental origin of GAN.
Authors
Yoan Arribat, Karolina S Mysiak, Léa Lescouzères, Alexia Boizot, Maxime Ruiz, Mireille Rossel, Pascale Bomont
Abstract
Inflammatory destruction of iron-rich myelin is characteristic of multiple sclerosis (MS). Although iron is needed for oligodendrocytes to produce myelin during development, its deposition has also been linked to neurodegeneration and inflammation, including in MS. We report perivascular iron deposition in multiple sclerosis lesions that was mirrored in 72 lesions from 13 marmosets with experimental autoimmune encephalomyelitis. Iron accumulated mainly inside microglia/macrophages from 6 weeks after demyelination. Consistently, expression of transferrin receptor, the brain’s main iron-influx protein, increased as lesions aged. Iron was uncorrelated with inflammation and postdated initial demyelination, suggesting that iron is not directly pathogenic. Iron homeostasis was at least partially restored in remyelinated, but not persistently demyelinated, lesions. Taken together, our results suggest that iron accumulation in the weeks after inflammatory demyelination may contribute to lesion repair rather than inflammatory demyelination per se.
Authors
Nathanael J. Lee, Seung-Kwon Ha, Pascal Sati, Martina Absinta, Govind Nair, Nicholas J. Luciano, Emily C. Leibovitch, Cecil C. Yen, Tracey A. Rouault, Afonso C. Silva, Steven Jacobson, Daniel S. Reich
Abstract
Reactive astrocytes are associated with every form of neurological injury. Despite their ubiquity, the molecular mechanisms controlling their production and diverse functions remain poorly defined. Because many features of astrocyte development are recapitulated in reactive astrocytes, we investigated the role of nuclear factor I-A (NFIA), a key transcriptional regulator of astrocyte development whose contributions to reactive astrocytes remain undefined. Here, we show that NFIA is highly expressed in reactive astrocytes in human neurological injury and identify unique roles across distinct injury states and regions of the CNS. In the spinal cord, after white matter injury (WMI), NFIA-deficient astrocytes exhibit defects in blood-brain barrier remodeling, which are correlated with the suppression of timely remyelination. In the cortex, after ischemic stroke, NFIA is required for the production of reactive astrocytes from the subventricular zone (SVZ). Mechanistically, NFIA directly regulates the expression of thrombospondin 4 (Thbs4) in the SVZ, revealing a key transcriptional node regulating reactive astrogenesis. Together, these studies uncover critical roles for NFIA in reactive astrocytes and illustrate how region- and injury-specific factors dictate the spectrum of reactive astrocyte responses.
Authors
Dylan Laug, Teng-Wei Huang, Navish A. Bosquez Huerta, Anna Yu-Szu Huang, Debosmita Sardar, Joshua Ortiz-Guzman, Jeffrey C. Carlson, Benjamin R. Arenkiel, Chay T. Kuo, Carrie A. Mohila, Stacey M. Glasgow, Hyun Kyoung Lee, Benjamin Deneen
Abstract
Excessive alcohol consumption is associated with spontaneous burning pain, hyperalgesia and allodynia. Although acetaldehyde has been implicated in the painful alcoholic neuropathy, the mechanism by which the ethanol metabolite causes pain symptoms is unknown. Acute ethanol ingestion caused delayed mechanical allodynia in mice. Inhibition of alcohol dehydrogenase (ADH) or deletion of transient receptor potential ankyrin 1 (TRPA1), a sensor for oxidative and carbonyl stress, prevented allodynia. Acetaldehyde generated by ADH in both liver and Schwann cells surrounding nociceptors was required for TRPA1-induced mechanical allodynia. Plp1-Cre;Trpa1fl/fl mice with a tamoxifen-inducible specific deletion of TRPA1 in Schwann cells revealed that channel activation by acetaldehyde in these cells initiates a NADPH oxidase-1 (NOX-1)-dependent production of hydrogen peroxide (H2O2) and 4-hydroxynonenal (4-HNE), which sustains allodynia by paracrine targeting of nociceptor TRPA1. Chronic ethanol ingestion caused prolonged mechanical allodynia and loss of intraepidermal small nerve fibers in WT mice. While Trpa1-/- or Plp1-Cre;Trpa1fl/fl mice did not develop mechanical allodynia, they did not show any protection from the small fiber neuropathy. Human Schwann cells express ADH/TRPA1/NOX1 and recapitulate the proalgesic functions of mouse Schwann cells. TRPA1 antagonists might attenuate some symptoms of alcohol-related pain.
Authors
Francesco De Logu, Simone Li Puma, Lorenzo Landini, Francesca Portelli, Alessandro Innocenti, Daniel Souza Monteiro de Araújo, Malvin N. Janal, Riccardo Patacchini, Nigel W. Bunnett, Pierangelo Geppetti, Romina Nassini
Copyright © 2019 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)