Neuroscience
Abstract
Pridopidine is currently under clinical development for Huntington disease (HD), with on-going studies to better characterize its therapeutic benefit and mode of action. Pridopidine was administered either prior to the appearance of disease phenotypes or in advanced stages of disease in the YAC128 mouse model of HD. In the early treatment cohort, animals received 0, 10, or 30 mg/kg pridopidine for a period of 10.5 months. In the late treatment cohort, animals were treated for 8 weeks with 0 mg/kg or an escalating dose of pridopidine (10 to 30 mg/kg over 3 weeks). Early treatment improved motor coordination and reduced anxiety- and depressive-like phenotypes in YAC128 mice, but it did not rescue striatal and corpus callosum atrophy. Late treatment, conversely, only improved depressive-like symptoms. RNA-seq analysis revealed that early pridopidine treatment reversed striatal transcriptional deficits, upregulating disease-specific genes that are known to be downregulated during HD, a finding that is experimentally confirmed herein. This suggests that pridopidine exerts beneficial effects at the transcriptional level. Taken together, our findings support continued clinical development of pridopidine for HD, particularly in the early stages of disease, and provide valuable insight into the potential therapeutic mode of action of pridopidine.
Authors
Marta Garcia-Miralles, Michal Geva, Jing Ying Tan, Nur Amirah Binte Mohammad Yusof, Yoonjeong Cha, Rebecca Kusko, Liang Juin Tan, Xiaohong Xu, Iris Grossman, Aric Orbach, Michael R. Hayden, Mahmoud A. Pouladi
Abstract
Neutrophils contribute to demyelinating autoimmune diseases, yet their phenotype and functions have been elusive to date. Here, we demonstrate that ICAM1 surface expression distinguishes extra- from intravascular neutrophils in the mouse CNS during experimental autoimmune encephalomyelitis (EAE). Transcriptomic analysis of these 2 subpopulations indicated that neutrophils, once extravasated, acquire macrophage-like properties, including the potential for immunostimulation and MHC class II–mediated antigen presentation. In corroboration, super-resolution (3D stimulated emission-depletion [STED]) microscopy revealed neutrophils forming synapses with T and B cells in situ. Further, neutrophils specifically express the aspartic retroviral-like protease ASPRV1, which increases in the CNS during EAE and severe cases of multiple sclerosis. Without ASPRV1, mice immunized with a new B cell–dependent myelin antigen (but not with the traditional myelin oligodendrocyte glycoprotein peptide) develop a chronic phase of EAE that is less severe and even completely fades in many individuals. Therefore, ICAM1+ macrophage–like neutrophils can play both shared and nonredundant roles in autoimmune demyelination, among them perpetuating inflammation via ASPRV1.
Authors
Ryder F. Whittaker Hawkins, Alexandre Patenaude, Aline Dumas, Rajiv Jain, Yodit Tesfagiorgis, Steven Kerfoot, Takeshi Matsui, Matthias Gunzer, Patrice E. Poubelle, Catherine Larochelle, Martin Pelletier, Luc Vallières
Abstract
A role of B cells in multiple sclerosis (MS) is well established, but there is limited understanding of their involvement during active disease. Here, we examined cerebrospinal fluid (CSF) and peripheral blood (PB) B cells in treatment-naive patients with MS or high-risk clinically isolated syndrome. Using flow cytometry, we found increased CSF lymphocytes with a disproportionate increase of B cells compared with T cells in patients with gadolinium-enhancing (Gd+) lesions on brain MRI. Ig gene heavy chain variable region (Ig-VH) repertoire sequencing of CSF and PB B cells revealed clonal relationships between intrathecal and peripheral B cell populations, which could be consistent with migration of B cells to and activation in the CNS in active MS. In addition, we found evidence for bystander immigration of B cells from the periphery, which could be supported by a CXCL13 gradient between CSF and blood. Understanding what triggers B cells to migrate and home to the CNS may ultimately aid in the rational selection of therapeutic strategies to limit progression in MS.
Authors
Erica L. Eggers, Brady A. Michel, Hao Wu, Sheng-zhi Wang, Carolyn J. Bevan, Aya Abounasr, Natalie S. Pierson, Antje Bischof, Max Kazer, Elizabeth Leitner, Ariele L. Greenfield, Stanislas Demuth, Michael R. Wilson, Roland G. Henry, Bruce A.C. Cree, Stephen L. Hauser, H.-Christian von Büdingen
Abstract
W-18 (4-chloro-N-[1-[2-(4-nitrophenyl)ethyl]-2-piperidinylidene]-benzenesulfonamide) and W-15 (4-chloro-N-[1-(2-phenylethyl)-2-piperidinylidene]-benzenesulfonamide) represent two emerging drugs of abuse chemically related to the potent opioid agonist fentanyl (N-(1-(2-phenylethyl)-4-piperidinyl)-N-phenylpropanamide). Here, we describe the comprehensive pharmacological profiles of W-18 and W-15, as examination of their structural features predicted that they might lack opioid activity. We found W-18 and W-15 to be without detectible activity at μ, δ, κ, and nociception opioid receptors in a variety of assays. We also tested W-18 and W-15 for activity as allosteric modulators at opioid receptors and found them devoid of significant positive or negative allosteric modulatory activity. Comprehensive profiling at essentially all the druggable GPCRs in the human genome using the PRESTO-Tango platform revealed no significant activity. Weak activity at the sigma receptors and the peripheral benzodiazepine receptor was found for W-18 (Ki = 271 nM). W-18 showed no activity in either the radiant heat tail-flick or the writhing assays and also did not induce classical opioid behaviors. W-18 is extensively metabolized, but its metabolites also lack opioid activity. Thus, although W-18 and W-15 have been suggested to be potent opioid agonists, our results reveal no significant activity at these or other known targets for psychoactive drugs.
Authors
Xi-Ping Huang, Tao Che, Thomas J. Mangano, Valerie Le Rouzic, Ying-Xian Pan, Michael D. Cameron, Michael H. Baumann, Gavril W. Pasternak, Bryan L. Roth
Abstract
Amyotrophic lateral sclerosis (ALS) is a rapidly progressing, fatal disorder with no effective treatment. We used simple genetic models of ALS to screen phenotypically for potential therapeutic compounds. We screened libraries of compounds in C. elegans, validated hits in zebrafish, and tested the most potent molecule in mice and in a small clinical trial. We identified a class of neuroleptics that restored motility in C. elegans and in zebrafish, and the most potent was pimozide, which blocked T-type Ca2+ channels in these simple models and stabilized neuromuscular transmission in zebrafish and enhanced it in mice. Finally, a short randomized controlled trial of sporadic ALS subjects demonstrated stabilization of motility and evidence of target engagement at the neuromuscular junction. Simple genetic models are, thus, useful in identifying promising compounds for the treatment of ALS, such as neuroleptics, which may stabilize neuromuscular transmission and prolong survival in this disease.
Authors
Shunmoogum A. Patten, Dina Aggad, Jose Martinez, Elsa Tremblay, Janet Petrillo, Gary A.B. Armstrong, Alexandre La Fontaine, Claudia Maios, Meijiang Liao, Sorana Ciura, Xiao-Yan Wen, Victor Rafuse, Justin Ichida, Lorne Zinman, Jean-Pierre Julien, Edor Kabashi, Richard Robitaille, Lawrence Korngut, J. Alexander Parker, Pierre Drapeau
Abstract
Evidence indicates that neuroinflammation contributes to motor neuron degeneration in amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease leading to progressive muscular paralysis. However, it remains elusive whether inflammatory cells can interact with degenerating distal motor axons, influencing the progressive denervation of neuromuscular junctions (NMJs). By analyzing the muscle extensor digitorum longus (EDL) following paralysis onset in the SOD1G93A rat model, we have observed a massive infiltration and degranulation of mast cells, starting after paralysis onset and correlating with progressive NMJ denervation. Remarkably, mast cells accumulated around degenerating motor axons and NMJs, and were also associated with macrophages. Mast cell accumulation and degranulation in paralytic EDL muscle was prevented by systemic treatment over 15 days with masitinib, a tyrosine kinase inhibitor currently in clinical trials for ALS exhibiting pharmacological activity affecting mast cells and microglia. Masitinib-induced mast cell reduction resulted in a 35% decrease in NMJ denervation and reduced motor deficits as compared with vehicle-treated rats. Masitinib also normalized macrophage infiltration, as well as regressive changes in Schwann cells and capillary networks observed in advanced paralysis. These findings provide evidence for mast cell contribution to distal axonopathy and paralysis progression in ALS, a mechanism that can be therapeutically targeted by masitinib.
Authors
Emiliano Trias, Sofía Ibarburu, Romina Barreto-Núñez, Valentina Varela, Ivan C. Moura, Patrice Dubreuil, Olivier Hermine, Joseph S. Beckman, Luis Barbeito
Abstract
In a rodent model of Parkinson’s disease (PD), levodopa-induced involuntary movements have been linked to striatal angiogenesis — a process that is difficult to document in living human subjects. Angiogenesis can be accompanied by localized increases in cerebral blood flow (CBF) responses to hypercapnia. We therefore explored the possibility that, in the absence of levodopa, local hypercapnic CBF responses are abnormally increased in PD patients with levodopa-induced dyskinesias (LID) but not in their nondyskinetic (NLID) counterparts. We used H215O PET to scan 24 unmedicated PD subjects (12 LID and 12 NLID) and 12 matched healthy subjects in the rest state under normocapnic and hypercapnic conditions. Hypercapnic CBF responses were compared to corresponding levodopa responses from the same subjects. Group differences in hypercapnic vasoreactivity were significant only in the posterior putamen, with greater CBF responses in LID subjects compared with the other subjects. Hypercapnic and levodopa-mediated CBF responses measured in this region exhibited distinct associations with disease severity: the former correlated with off-state motor disability ratings but not symptom duration, whereas the latter correlated with symptom duration but not motor disability. These are the first in vivo human findings linking LID to microvascular changes in the basal ganglia.
Authors
Vincent A. Jourdain, Katharina A. Schindlbeck, Chris C. Tang, Martin Niethammer, Yoon Young Choi, Daniel Markowitz, Amir Nazem, Dominic Nardi, Nicholas Carras, Andrew Feigin, Yilong Ma, Shichun Peng, Vijay Dhawan, David Eidelberg
Abstract
In rodent models, obesity and hyperglycemia alter cerebral glucose metabolism and glucose transport into the brain, resulting in disordered cerebral function as well as inappropriate responses to homeostatic and hedonic inputs. Whether similar findings are seen in the human brain remains unclear. In this study, 25 participants (9 healthy participants; 10 obese nondiabetic participants; and 6 poorly controlled, insulin- and metformin-treated type 2 diabetes mellitus (T2DM) participants) underwent 1H magnetic resonance spectroscopy scanning in the occipital lobe to measure the change in intracerebral glucose levels during a 2-hour hyperglycemic clamp (glucose ~220 mg/dl). The change in intracerebral glucose was significantly different across groups after controlling for age and sex, despite similar plasma glucose levels at baseline and during hyperglycemia. Compared with lean participants, brain glucose increments were lower in participants with obesity and T2DM. Furthermore, the change in brain glucose correlated inversely with plasma free fatty acid (FFA) levels during hyperglycemia. These data suggest that obesity and poorly controlled T2DM progressively diminish brain glucose responses to hyperglycemia, which has important implications for understanding not only the altered feeding behavior, but also the adverse neurocognitive consequences associated with obesity and T2DM.
Authors
Janice J. Hwang, Lihong Jiang, Muhammad Hamza, Elizabeth Sanchez Rangel, Feng Dai, Renata Belfort-DeAguiar, Lisa Parikh, Brian B. Koo, Douglas L. Rothman, Graeme Mason, Robert S. Sherwin
Abstract
Genetic defects in the synaptic scaffolding protein gene, SHANK2, are linked to a variety of neuropsychiatric disorders, including autism spectrum disorders, schizophrenia, intellectual disability, and bipolar disorder, but the molecular mechanisms underlying the pleotropic effects of SHANK2 mutations are poorly understood. We generated and characterized a line of Shank2 mutant mice by deleting exon 24 (Δe24). Shank2Δe24–/– mice engage in significantly increased locomotor activity, display abnormal reward-seeking behavior, are anhedonic, have perturbations in circadian rhythms, and show deficits in social and cognitive behaviors. While these phenotypes recapitulate the pleotropic behaviors associated with human SHANK2-related disorders, major behavioral features in these mice are reminiscent of bipolar disorder. For instance, their hyperactivity was augmented with amphetamine but was normalized with the mood stabilizers lithium and valproate. Shank2 deficiency limited to the forebrain recapitulated the bipolar mania phenotype. The composition and functions of NMDA and AMPA receptors were altered at Shank2-deficient synapses, hinting toward the mechanism underlying these behavioral abnormalities. Human genetic findings support construct validity, and the behavioral features in Shank2 Δe24 mice support face and predictive validities of this model for bipolar mania. Further genetic studies to understand the contribution of SHANK2 deficiencies in bipolar disorder are warranted.
Authors
Andrea L. Pappas, Alexandra L. Bey, Xiaoming Wang, Mark Rossi, Yong Ho Kim, Haidun Yan, Fiona Porkka, Lara J. Duffney, Samantha M. Phillips, Xinyu Cao, Jin-dong Ding, Ramona M. Rodriguiz, Henry H. Yin, Richard J. Weinberg, Ru-Rong Ji, William C. Wetsel, Yong-hui Jiang
Abstract
BACKGROUND. Our goal was to identify changes in the metabolome in multiple sclerosis (MS) and how vitamin D supplementation alters metabolic profiles in MS patients and healthy controls. METHODS. We applied global untargeted metabolomics to plasma from a cross-sectional cohort of age- and sex-matched MS patients and controls and a second longitudinal cohort of MS patients and healthy controls who received 5,000 IU cholecalciferol daily for 90 days. We applied partial least squares discriminant analysis, weighted correlation network analysis (WGCNA), and pathway analysis to the metabolomics data. Generalized estimating equations models were used to assess change in WGCNA-identified module scores or metabolite pathways with vitamin D supplementation. RESULTS. Utilizing multiple analytical techniques, we identified metabolic alterations in oxidative stress (γ-glutamyl amino acid, glutathione) and xenobiotic metabolism (benzoate, caffeine) in MS patients compared with healthy controls in the first cohort. In the vitamin D supplementation cohort, we identified two sets of metabolites altered differentially between MS patients and healthy controls with vitamin D supplementation. The first included markers of oxidative stress and protein oxidation (P = 0.006), while the second contained lysolipids and fatty acids (P = 0.03). CONCLUSIONS. Using metabolomics, we identified alterations in oxidative stress and xenobiotic metabolism in MS patients and subsequently demonstrated a reduction of oxidative stress markers with vitamin D supplementation in healthy controls but not in MS patients. We demonstrate the utility of metabolomics in identifying aberrant metabolic processes and in monitoring the ability of therapeutic interventions to correct these abnormalities. TRIAL REGISTRATION. ClinicalTrials.gov NCT01667796. FUNDING. This study was supported by NIH grant K23 NS067055, grants from the Race to Erase MS, the National Multiple Sclerosis Society, the American Academy of Neurology, and North American Research Committee on Multiple Sclerosis.
Authors
Pavan Bhargava, Kathryn C. Fitzgerald, Peter A. Calabresi, Ellen M. Mowry
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