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Chambel SS, Cruz CD. Axonal growth inhibitors and their receptors in spinal cord injury: from biology to clinical translation. Neural Regen Res 2023; 18:2573-2581. [PMID: 37449592 DOI: 10.4103/1673-5374.373674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2023] Open
Abstract
Axonal growth inhibitors are released during traumatic injuries to the adult mammalian central nervous system, including after spinal cord injury. These molecules accumulate at the injury site and form a highly inhibitory environment for axonal regeneration. Among these inhibitory molecules, myelin-associated inhibitors, including neurite outgrowth inhibitor A, oligodendrocyte myelin glycoprotein, myelin-associated glycoprotein, chondroitin sulfate proteoglycans and repulsive guidance molecule A are of particular importance. Due to their inhibitory nature, they represent exciting molecular targets to study axonal inhibition and regeneration after central injuries. These molecules are mainly produced by neurons, oligodendrocytes, and astrocytes within the scar and in its immediate vicinity. They exert their effects by binding to specific receptors, localized in the membranes of neurons. Receptors for these inhibitory cues include Nogo receptor 1, leucine-rich repeat, and Ig domain containing 1 and p75 neurotrophin receptor/tumor necrosis factor receptor superfamily member 19 (that form a receptor complex that binds all myelin-associated inhibitors), and also paired immunoglobulin-like receptor B. Chondroitin sulfate proteoglycans and repulsive guidance molecule A bind to Nogo receptor 1, Nogo receptor 3, receptor protein tyrosine phosphatase σ and leucocyte common antigen related phosphatase, and neogenin, respectively. Once activated, these receptors initiate downstream signaling pathways, the most common amongst them being the RhoA/ROCK signaling pathway. These signaling cascades result in actin depolymerization, neurite outgrowth inhibition, and failure to regenerate after spinal cord injury. Currently, there are no approved pharmacological treatments to overcome spinal cord injuries other than physical rehabilitation and management of the array of symptoms brought on by spinal cord injuries. However, several novel therapies aiming to modulate these inhibitory proteins and/or their receptors are under investigation in ongoing clinical trials. Investigation has also been demonstrating that combinatorial therapies of growth inhibitors with other therapies, such as growth factors or stem-cell therapies, produce stronger results and their potential application in the clinics opens new venues in spinal cord injury treatment.
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Affiliation(s)
- Sílvia Sousa Chambel
- Experimental Biology Unit, Department of Biomedicine, Faculty of Medicine of Porto; Translational NeuroUrology, Instituto de Investigação e Inovação em Saúde-i3S and IBMC, Universidade do Porto, Porto, Portugal
| | - Célia Duarte Cruz
- Experimental Biology Unit, Department of Biomedicine, Faculty of Medicine of Porto; Translational NeuroUrology, Instituto de Investigação e Inovação em Saúde-i3S and IBMC, Universidade do Porto, Porto, Portugal
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Systems biology analysis of human genomes points to key pathways conferring spina bifida risk. Proc Natl Acad Sci U S A 2021; 118:2106844118. [PMID: 34916285 PMCID: PMC8713748 DOI: 10.1073/pnas.2106844118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/20/2021] [Indexed: 12/15/2022] Open
Abstract
Genetic investigations of most structural birth defects, including spina bifida (SB), congenital heart disease, and craniofacial anomalies, have been underpowered for genome-wide association studies because of their rarity, genetic heterogeneity, incomplete penetrance, and environmental influences. Our systems biology strategy to investigate SB predisposition controls for population stratification and avoids much of the bias inherent in candidate gene searches that are pervasive in the field. We examine both protein coding and noncoding regions of whole genomes to analyze sequence variants, collapsed by gene or regulatory region, and apply machine learning, gene enrichment, and pathway analyses to elucidate molecular pathways and genes contributing to human SB. Spina bifida (SB) is a debilitating birth defect caused by multiple gene and environment interactions. Though SB shows non-Mendelian inheritance, genetic factors contribute to an estimated 70% of cases. Nevertheless, identifying human mutations conferring SB risk is challenging due to its relative rarity, genetic heterogeneity, incomplete penetrance, and environmental influences that hamper genome-wide association studies approaches to untargeted discovery. Thus, SB genetic studies may suffer from population substructure and/or selection bias introduced by typical candidate gene searches. We report a population based, ancestry-matched whole-genome sequence analysis of SB genetic predisposition using a systems biology strategy to interrogate 298 case-control subject genomes (149 pairs). Genes that were enriched in likely gene disrupting (LGD), rare protein-coding variants were subjected to machine learning analysis to identify genes in which LGD variants occur with a different frequency in cases versus controls and so discriminate between these groups. Those genes with high discriminatory potential for SB significantly enriched pathways pertaining to carbon metabolism, inflammation, innate immunity, cytoskeletal regulation, and essential transcriptional regulation consistent with their having impact on the pathogenesis of human SB. Additionally, an interrogation of conserved noncoding sequences identified robust variant enrichment in regulatory regions of several transcription factors critical to embryonic development. This genome-wide perspective offers an effective approach to the interrogation of coding and noncoding sequence variant contributions to rare complex genetic disorders.
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In vivo functions of p75 NTR: challenges and opportunities for an emerging therapeutic target. Trends Pharmacol Sci 2021; 42:772-788. [PMID: 34334250 DOI: 10.1016/j.tips.2021.06.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 05/31/2021] [Accepted: 06/28/2021] [Indexed: 12/24/2022]
Abstract
The p75 neurotrophin receptor (p75NTR) functions at the molecular nexus of cell death, survival, and differentiation. In addition to its contribution to neurodegenerative diseases and nervous system injuries, recent studies have revealed unanticipated roles of p75NTR in liver repair, fibrinolysis, lung fibrosis, muscle regeneration, and metabolism. Linking these various p75NTR functions more precisely to specific mechanisms marks p75NTR as an emerging candidate for therapeutic intervention in a wide range of disorders. Indeed, small molecule inhibitors of p75NTR binding to neurotrophins have shown efficacy in models of Alzheimer's disease (AD) and neurodegeneration. Here, we outline recent advances in understanding p75NTR pleiotropic functions in vivo, and propose an integrated view of p75NTR and its challenges and opportunities as a pharmacological target.
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Muheremu A, Shu L, Liang J, Aili A, Jiang K. Sustained delivery of neurotrophic factors to treat spinal cord injury. Transl Neurosci 2021; 12:494-511. [PMID: 34900347 PMCID: PMC8633588 DOI: 10.1515/tnsci-2020-0200] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 11/04/2021] [Accepted: 11/05/2021] [Indexed: 12/16/2022] Open
Abstract
Acute spinal cord injury (SCI) is a devastating condition that results in tremendous physical and psychological harm and a series of socioeconomic problems. Although neurons in the spinal cord need neurotrophic factors for their survival and development to reestablish their connections with their original targets, endogenous neurotrophic factors are scarce and the sustainable delivery of exogeneous neurotrophic factors is challenging. The widely studied neurotrophic factors such as brain-derived neurotrophic factor, neurotrophin-3, nerve growth factor, ciliary neurotrophic factor, basic fibroblast growth factor, and glial cell-derived neurotrophic factor have a relatively short cycle that is not sufficient enough for functionally significant neural regeneration after SCI. In the past decades, scholars have tried a variety of cellular and viral vehicles as well as tissue engineering scaffolds to safely and sustainably deliver those necessary neurotrophic factors to the injury site, and achieved satisfactory neural repair and functional recovery on many occasions. Here, we review the neurotrophic factors that have been used in trials to treat SCI, and vehicles that were commonly used for their sustained delivery.
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Affiliation(s)
- Aikeremujiang Muheremu
- Department of Spine Surgery, Sixth Affiliated Hospital of Xinjiang Medical University, 39 Wuxing Nan Rd, Tianshan District, Urumqi, Xinjiang, 86830001, People’s Republic of China
| | - Li Shu
- Department of Orthopedics, Sixth Affiliated Hospital of Xinjiang Medical University, Urumqi, Xinjiang, 86830001, People’s Republic of China
| | - Jing Liang
- Department of Laboratory Medicine, Sixth Affiliated Hospital of Xinjiang Medical University, 39, Wuxing Nan Rd, Tianshan District, Urumqi, Xinjiang, 86830001, People’s Republic of China
| | - Abudunaibi Aili
- Department of Spine Surgery, Sixth Affiliated Hospital of Xinjiang Medical University, 39 Wuxing Nan Rd, Tianshan District, Urumqi, Xinjiang, 86830001, People’s Republic of China
| | - Kan Jiang
- Department of Orthopedics, Sixth Affiliated Hospital of Xinjiang Medical University, Urumqi, Xinjiang, 86830001, People’s Republic of China
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Xie Y, Seawell J, Boesch E, Allen L, Suchy A, Longo FM, Meeker RB. Small molecule modulation of the p75 neurotrophin receptor suppresses age- and genotype-associated neurodegeneration in HIV gp120 transgenic mice. Exp Neurol 2020; 335:113489. [PMID: 33007293 DOI: 10.1016/j.expneurol.2020.113489] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 09/07/2020] [Accepted: 09/28/2020] [Indexed: 12/21/2022]
Abstract
The persistence of HIV in the central nervous system leads to cognitive deficits in up to 50% of people living with HIV even with systemic suppression by antiretroviral treatment. The interaction of chronic inflammation with age-associated degeneration places these individuals at increased risk of accelerated aging and other neurodegenerative diseases and no treatments are available that effectively halt these processes. The adverse effects of aging and inflammation may be mediated, in part, by an increase in the expression of the p75 neurotrophin receptor (p75NTR) which shifts the balance of neurotrophin signaling toward less protective pathways. To determine if modulation of p75NTR could modify the disease process, we treated HIV gp120 transgenic mice with a small molecule ligand designed to engage p75NTR and downregulate degenerative signaling. Daily treatment with 50 mg/kg LM11A-31 for 4 months suppressed age- and genotype-dependent activation of microglia, increased microtubule associated protein-2 (MAP-2), reduced dendritic varicosities and slowed the loss of parvalbumin immunoreactive neurons in the hippocampus. An age related accumulation of microtubule associated protein Tau was identified in the hippocampus in extracellular clusters that co-expressed p75NTR suggesting a link between Tau and p75NTR. Although the significance of the relationship between p75NTR and Tau is unclear, a decrease in Tau-1 immunoreactivity as gp120 mice entered old age (>16 months) suggests that the Tau may transition to more pathological modifications; a process blocked by LM11A-31. Overall, the effects of LM11A-31 are consistent with strong neuroprotective and anti-inflammatory actions that have significant therapeutic potential.
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Affiliation(s)
- Youmie Xie
- Department of Neurology, University of North Carolina, Chapel Hill, NC 27599, United States of America
| | - Jaimie Seawell
- Department of Neurology, University of North Carolina, Chapel Hill, NC 27599, United States of America; The Edward Via College of Osteopathic Medicine, Spartanburg, SC 29303, United States of America
| | - Emily Boesch
- School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599, United States of America
| | - Lauren Allen
- Department of Neurology, University of North Carolina, Chapel Hill, NC 27599, United States of America
| | - Ashley Suchy
- Department of Neurology, University of North Carolina, Chapel Hill, NC 27599, United States of America
| | - Frank M Longo
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, United States of America
| | - Rick B Meeker
- Department of Neurology, University of North Carolina, Chapel Hill, NC 27599, United States of America; Neurobiology Curriculum, University of North Carolina, Chapel Hill, NC 27599, United States of America.
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Telegin GB, Chernov AS, Konovalov NA, Belogurov AA, Balmasova IP, Gabibov AG. Cytokine Profile As a Marker of Cell Damage and Immune Dysfunction after Spinal Cord Injury. Acta Naturae 2020; 12:92-101. [PMID: 33173599 PMCID: PMC7604889 DOI: 10.32607/actanaturae.11096] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 09/08/2020] [Indexed: 12/30/2022] Open
Abstract
This study reviews the findings of recent experiments designed to investigate the cytokine profile after a spinal cord injury. The role played by key cytokines in eliciting the cellular response to trauma was assessed. The results of the specific immunopathogenetic interaction between the nervous and immune systems in the immediate and chronic post-traumatic periods are summarized. It was demonstrated that it is reasonable to use the step-by-step approach to the assessment of the cytokine profile after a spinal cord injury and take into account the combination of the pathogenetic and protective components in implementing the regulatory effects of individual cytokines and their integration into the regenerative processes in the injured spinal cord. This allows one to rationally organize treatment and develop novel drugs.
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Affiliation(s)
- G. B. Telegin
- Branch of Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences, Pushchino, 142290 Russia
| | - A. S. Chernov
- Branch of Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences, Pushchino, 142290 Russia
| | - N. A. Konovalov
- N.N. Burdenko National Scientific and Practical Center for Neurosurgery, RF Health Ministry, Moscow, 125047 Russia
| | - A. A. Belogurov
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences, Moscow, 117997 Russia
| | - I. P. Balmasova
- Evdokimov Moscow State University of Medicine and Dentistry of Russia’s Ministry of Health, Moscow, 127473 Russia
| | - A. G. Gabibov
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences, Moscow, 117997 Russia
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7
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Katoh H, Yokota K, Fehlings MG. Regeneration of Spinal Cord Connectivity Through Stem Cell Transplantation and Biomaterial Scaffolds. Front Cell Neurosci 2019; 13:248. [PMID: 31244609 PMCID: PMC6563678 DOI: 10.3389/fncel.2019.00248] [Citation(s) in RCA: 104] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 05/17/2019] [Indexed: 12/20/2022] Open
Abstract
Significant progress has been made in the treatment of spinal cord injury (SCI). Advances in post-trauma management and intensive rehabilitation have significantly improved the prognosis of SCI and converted what was once an “ailment not to be treated” into a survivable injury, but the cold hard fact is that we still do not have a validated method to improve the paralysis of SCI. The irreversible functional impairment of the injured spinal cord is caused by the disruption of neuronal transduction across the injury lesion, which is brought about by demyelination, axonal degeneration, and loss of synapses. Furthermore, refractory substrates generated in the injured spinal cord inhibit spontaneous recovery. The discovery of the regenerative capability of central nervous system neurons in the proper environment and the verification of neural stem cells in the spinal cord once incited hope that a cure for SCI was on the horizon. That hope was gradually replaced with mounting frustration when neuroprotective drugs, cell transplantation, and strategies to enhance remyelination, axonal regeneration, and neuronal plasticity demonstrated significant improvement in animal models of SCI but did not translate into a cure in human patients. However, recent advances in SCI research have greatly increased our understanding of the fundamental processes underlying SCI and fostered increasing optimism that these multiple treatment strategies are finally coming together to bring about a new era in which we will be able to propose encouraging therapies that will lead to appreciable improvements in SCI patients. In this review, we outline the pathophysiology of SCI that makes the spinal cord refractory to regeneration and discuss the research that has been done with cell replacement and biomaterial implantation strategies, both by itself and as a combined treatment. We will focus on the capacity of these strategies to facilitate the regeneration of neural connectivity necessary to achieve meaningful functional recovery after SCI.
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Affiliation(s)
- Hiroyuki Katoh
- Division of Genetics and Development, Krembil Research Institute, Toronto, ON, Canada.,Department of Orthopaedic Surgery - Surgical Sciences, School of Medicine, Tokai University, Tokyo, Japan
| | - Kazuya Yokota
- Division of Genetics and Development, Krembil Research Institute, Toronto, ON, Canada.,Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Michael G Fehlings
- Division of Genetics and Development, Krembil Research Institute, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada.,Division of Neurosurgery, University of Toronto, Toronto, ON, Canada.,Spine Program, Toronto Western Hospital, University Health Network, Toronto, ON, Canada
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8
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Bianco J, De Berdt P, Deumens R, des Rieux A. Taking a bite out of spinal cord injury: do dental stem cells have the teeth for it? Cell Mol Life Sci 2016; 73:1413-37. [PMID: 26768693 PMCID: PMC11108394 DOI: 10.1007/s00018-015-2126-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 12/16/2015] [Accepted: 12/22/2015] [Indexed: 12/15/2022]
Abstract
Dental stem cells are an emerging star on a stage that is already quite populated. Recently, there has been a lot of hype concerning these cells in dental therapies, especially in regenerative endodontics. It is fitting that most research is concentrated on dental regeneration, although other uses for these cells need to be explored in more detail. Being a true mesenchymal stem cell, their capacities could also prove beneficial in areas outside their natural environment. One such field is the central nervous system, and in particular, repairing the injured spinal cord. One of the most formidable challenges in regenerative medicine is to restore function to the injured spinal cord, and as yet, a cure for paralysis remains to be discovered. A variety of approaches have already been tested, with graft-based strategies utilising cells harbouring appropriate properties for neural regeneration showing encouraging results. Here we present a review focusing on properties of dental stem cells that endorse their use in regenerative medicine, with particular emphasis on repairing the damaged spinal cord.
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Affiliation(s)
- John Bianco
- Louvain Drug Research Institute, Advanced Drug Delivery and Biomaterials, Université catholique de Louvain, Avenue Mounier, 73, B1 73.12, 1200, Brussels, Belgium.
- Integrated Center for Cell Therapy and Regenerative Medicine, International Clinical Research Center (FNUSA-ICRC), St. Anne's University Hospital Brno, Pekařská 53, 656 91, Brno, Czech Republic.
| | - Pauline De Berdt
- Louvain Drug Research Institute, Advanced Drug Delivery and Biomaterials, Université catholique de Louvain, Avenue Mounier, 73, B1 73.12, 1200, Brussels, Belgium
| | - Ronald Deumens
- Institute of Neuroscience, Université catholique de Louvain, Avenue Hippocrate B1.54.10, 1200, Brussels, Belgium
| | - Anne des Rieux
- Louvain Drug Research Institute, Advanced Drug Delivery and Biomaterials, Université catholique de Louvain, Avenue Mounier, 73, B1 73.12, 1200, Brussels, Belgium
- Institute of Condensed Matter and Nanosciences, Université catholique de Louvain, 1348, Louvain-La-Neuve, Belgium
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Meeker RB, Williams KS. The p75 neurotrophin receptor: at the crossroad of neural repair and death. Neural Regen Res 2015; 10:721-5. [PMID: 26109945 PMCID: PMC4468762 DOI: 10.4103/1673-5374.156967] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/07/2015] [Indexed: 12/14/2022] Open
Abstract
The strong repair and pro-survival functions of neurotrophins at their primary receptors, TrkA, TrkB and TrkC, have made them attractive candidates for treatment of nervous system injury and disease. However, difficulties with the clinical implementation of neurotrophin therapies have prompted the search for treatments that are stable, easier to deliver and allow more precise regulation of neurotrophin actions. Recently, the p75 neurotrophin receptor (p75NTR) has emerged as a potential target for pharmacological control of neurotrophin activity, supported in part by studies demonstrating 1) regulation of neural plasticity in the mature nervous system, 2) promotion of adult neurogenesis and 3) increased expression in neurons, macrophages, microglia, astrocytes and/or Schwann cells in response to injury and neurodegenerative diseases. Although the receptor has no intrinsic catalytic activity it interacts with and modulates the function of TrkA, TrkB, and TrkC, as well as sortilin and the Nogo receptor. This provides substantial cellular and molecular diversity for regulation of neuron survival, neurogenesis, immune responses and processes that support neural function. Upregulation of the p75NTR under pathological conditions places the receptor in a key position to control numerous processes necessary for nervous system recovery. Support for this possibility has come from recent studies showing that small, non-peptide p75NTR ligands can selectively modify pro-survival and repair functions. While a great deal remains to be discovered about the wide ranging functions of the p75NTR, studies summarized in this review highlight the immense potential for development of novel neuroprotective and neurorestorative therapies.
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Affiliation(s)
- Rick B Meeker
- Department of Neurology, University of North Carolina, Chapel Hill, NC, USA
| | - Kimberly S Williams
- Curriculum in Neurobiology, University of North Carolina, Chapel Hill, NC, USA
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Siddiqui AM, Khazaei M, Fehlings MG. Translating mechanisms of neuroprotection, regeneration, and repair to treatment of spinal cord injury. PROGRESS IN BRAIN RESEARCH 2015; 218:15-54. [PMID: 25890131 DOI: 10.1016/bs.pbr.2014.12.007] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
One of the big challenges in neuroscience that remains to be understood is why the central nervous system is not able to regenerate to the extent that the peripheral nervous system does. This is especially problematic after traumatic injuries, like spinal cord injury (SCI), since the lack of regeneration leads to lifelong deficits and paralysis. Treatment of SCI has improved during the last several decades due to standardized protocols for emergency medical response teams and improved medical, surgical, and rehabilitative treatments. However, SCI continues to result in profound impairments for the individual. There are many processes that lead to the pathophysiology of SCI, such as ischemia, vascular disruption, neuroinflammation, oxidative stress, excitotoxicity, demyelination, and cell death. Current treatments include surgical decompression, hemodynamic control, and methylprednisolone. However, these early treatments are associated with modest functional recovery. Some treatments currently being investigated for use in SCI target neuroprotective (riluzole, minocycline, G-CSF, FGF-2, and polyethylene glycol) or neuroregenerative (chondroitinase ABC, self-assembling peptides, and rho inhibition) strategies, while many cell therapies (embryonic stem cells, neural stem cells, induced pluripotent stem cells, mesenchymal stromal cells, Schwann cells, olfactory ensheathing cells, and macrophages) have also shown promise. However, since SCI has multiple factors that determine the progress of the injury, a combinatorial therapeutic approach will most likely be required for the most effective treatment of SCI.
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Affiliation(s)
- Ahad M Siddiqui
- Department of Genetics and Development, Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Mohamad Khazaei
- Department of Genetics and Development, Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Michael G Fehlings
- Department of Genetics and Development, Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada; Department of Surgery, University of Toronto, Toronto, Ontario, Canada; Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada.
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Ameliorative Effects of p75NTR-ED-Fc on Axonal Regeneration and Functional Recovery in Spinal Cord-Injured Rats. Mol Neurobiol 2014; 52:1821-1834. [DOI: 10.1007/s12035-014-8972-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2014] [Accepted: 10/29/2014] [Indexed: 11/25/2022]
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12
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Steuer E, Schaefer ML, Belluscio L. Using the olfactory system as an in vivo model to study traumatic brain injury and repair. J Neurotrauma 2014; 31:1277-91. [PMID: 24694002 DOI: 10.1089/neu.2013.3296] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Loss of olfactory function is an early indicator of traumatic brain injury (TBI). The regenerative capacity and well-defined neural maps of the mammalian olfactory system enable investigations into the degeneration and recovery of neural circuits after injury. Here, we introduce a unique olfactory-based model of TBI that reproduces many hallmarks associated with human brain trauma. We performed a unilateral penetrating impact to the mouse olfactory bulb and observed a significant loss of olfactory sensory neurons (OSNs) in the olfactory epithelium (OE) ipsilateral to the injury, but not contralateral. By comparison, we detected the injury markers p75(NTR), β-APP, and activated caspase-3 in both the ipsi- and contralateral OE. In the olfactory bulb (OB), we observed a graded cell loss, with ipsilateral showing a greater reduction than contralateral and both significantly less than sham. Similar to OE, injury markers in the OB were primarily detected on the ipsilateral side, but also observed contralaterally. Behavioral experiments measured 4 days after impact also demonstrated loss of olfactory function, yet following a 30-day recovery period, we observed a significant improvement in olfactory function and partial recovery of olfactory circuitry, despite the persistence of TBI markers. Interestingly, by using the M71-IRES-tauLacZ reporter line to track OSN organization, we further determined that inducing neural activity during the recovery period with intense odor conditioning did not enhance the recovery process. Together, these data establish the mouse olfactory system as a new model to study TBI, serving as a platform to understand neural disruption and the potential for circuit restoration.
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Affiliation(s)
- Elizabeth Steuer
- 1 Developmental Neural Plasticity Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health , Bethesda, Maryland
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Weight-bearing locomotion in the developing opossum, Monodelphis domestica following spinal transection: remodeling of neuronal circuits caudal to lesion. PLoS One 2013; 8:e71181. [PMID: 23951105 PMCID: PMC3741377 DOI: 10.1371/journal.pone.0071181] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 06/26/2013] [Indexed: 12/17/2022] Open
Abstract
Complete spinal transection in the mature nervous system is typically followed by minimal axonal repair, extensive motor paralysis and loss of sensory functions caudal to the injury. In contrast, the immature nervous system has greater capacity for repair, a phenomenon sometimes called the infant lesion effect. This study investigates spinal injuries early in development using the marsupial opossum Monodelphis domestica whose young are born very immature, allowing access to developmental stages only accessible in utero in eutherian mammals. Spinal cords of Monodelphis pups were completely transected in the lower thoracic region, T10, on postnatal-day (P)7 or P28 and the animals grew to adulthood. In P7-injured animals regrown supraspinal and propriospinal axons through the injury site were demonstrated using retrograde axonal labelling. These animals recovered near-normal coordinated overground locomotion, but with altered gait characteristics including foot placement phase lags. In P28-injured animals no axonal regrowth through the injury site could be demonstrated yet they were able to perform weight-supporting hindlimb stepping overground and on the treadmill. When placed in an environment of reduced sensory feedback (swimming) P7-injured animals swam using their hindlimbs, suggesting that the axons that grew across the lesion made functional connections; P28-injured animals swam using their forelimbs only, suggesting that their overground hindlimb movements were reflex-dependent and thus likely to be generated locally in the lumbar spinal cord. Modifications to propriospinal circuitry in P7- and P28-injured opossums were demonstrated by changes in the number of fluorescently labelled neurons detected in the lumbar cord following tracer studies and changes in the balance of excitatory, inhibitory and neuromodulatory neurotransmitter receptors’ gene expression shown by qRT-PCR. These results are discussed in the context of studies indicating that although following injury the isolated segment of the spinal cord retains some capability of rhythmic movement the mechanisms involved in weight-bearing locomotion are distinct.
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Montazeri F, Esmaeili A, Miroliaei M, Moshtaghian SJ. Messenger RNA expression patterns of p75 neurotrophin receptor and tropomyosin-receptor-kinase A following spinal cord injury. J Spinal Cord Med 2013; 36:231-6. [PMID: 23809594 PMCID: PMC3654450 DOI: 10.1179/2045772312y.0000000077] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
BACKGROUND Induction of p75 neurotrophin receptor (p75NTR) could be one of the first steps that initiate apoptotic cascade after injury, or it may indicate regeneration responses undertaken by the injured system, possibly in collaboration with resident tropomyosin-receptor-kinase (Trk). OBJECTIVE To measure quantitative changes in messenger RNA (mRNA) expression levels of p75NTR, Trk A, and caspase-9 in rat's injured spinal cord (SCI). The reciprocal interaction between Trk and p75NTR signaling pathways can dictate cellular responses to neurotrophins. p75NTR can regulate Trk-dependent responses, but the role of Trk in regulating p75NTR-dependent signaling is not well documented. DESIGN Using real-time polymerase chain reaction, this study analyzed changes in the mRNA abundance of the mentioned genes at 6, 24, and 72 hours and 7 and 10 days after SCI in adult male rats. SCI was induced at T9 level by transsection. RESULTS Results show a complicated temporal and spatial pattern of alteration with different degrees and direction (up- or down-regulation) in p75NTR, Trk A, and caspase-9 mRNA expression levels after SCI. The greatest variation was seen in center regions following SCI. This study shows that alteration in p75NTR, Trk A, and caspase-9 expression starts as early as 6 hours after SCI. Alterations in p75NTR, Trk A, and caspase-9 expression within the spinal cord may play a key role in the apoptotic cell death. CONCLUSION Results suggest that the role of p75NTR is to eliminate damaged cells by activating the apoptotic machinery, especially at the center of damage and during first week after injury.
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Affiliation(s)
| | - Abolghasem Esmaeili
- Correspondence to: Abolghasem Esmaeili, Department of Biology, Faculty of Sciences, University of Isfahan, postal code 8174673441, Isfahan, Iran.;
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15
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Forgione N, Fehlings MG. Rho-ROCK inhibition in the treatment of spinal cord injury. World Neurosurg 2013; 82:e535-9. [PMID: 23298675 DOI: 10.1016/j.wneu.2013.01.009] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 01/03/2013] [Indexed: 11/18/2022]
Abstract
BACKGROUND The Rho pathway has been shown to have a role in the pathophysiology of spinal cord injury (SCI). Upregulation of the Rho signaling pathway occurs as a result of SCI. Activation of Rho and its downstream effector kinases triggers growth cone collapse and represents a significant barrier to axon regeneration. Furthermore, there is evidence that Rho-ROCK signaling mediates the inhibitory effects of chondroitin sulfate proteoglycans on neurons, and that inhibition of Rho and ROCK can reverse chondroitin sulfate proteoglycan-mediated inhibition of neurite outgrowth. Work building on these findings suggests that inhibition of this pathway may boost neuroprotection and axonal regeneration after SCI. METHODS A narrative review. RESULTS Investigators have identified a C3 transferase, which selectively inhibits Rho without affecting other guanine triphosphatases. This has been shown to promote axonal sprouting and recovery of locomotor function after hemisection of the thoracic spinal cord in a mouse model of SCI. The neuroprotective properties of Rho inhibitors in animal models of SCI have been reinforced by studies carried out in vitro using retinal ganglion cells. In light of this, a Rho inhibitor known as Cethrin has been evaluated as a therapeutic intervention for SCI in a phase I/IIa clinical trial with promising results. CONCLUSIONS The Rho pathway has been shown to have a role in the pathophysiology of SCI and preclinical and clinical work and is currently a promising target for the treatment of patients with SCI.
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Affiliation(s)
- Nicole Forgione
- Division of Genetics and Development, Toronto Western Research Institute, Toronto, Ontario, Canada
| | - Michael G Fehlings
- Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada.
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16
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The retrograde delivery of adenovirus vector carrying the gene for brain-derived neurotrophic factor protects neurons and oligodendrocytes from apoptosis in the chronically compressed spinal cord of twy/twy mice. Spine (Phila Pa 1976) 2012; 37:2125-35. [PMID: 22648027 DOI: 10.1097/brs.0b013e3182600ef7] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN The twy/twy mouse undergoes spontaneous chronic mechanical compression of the spinal cord; this in vivo model system was used to examine the effects of retrograde adenovirus (adenoviral vector [AdV])-mediated brain-derived neurotrophic factor (BDNF) gene delivery to spinal neural cells. OBJECTIVE To investigate the targeting and potential neuroprotective effect of retrograde AdV-mediated BDNF gene transfection in the chronically compressed spinal cord in terms of prevention of apoptosis of neurons and oligodendrocytes. SUMMARY OF BACKGROUND DATA Several studies have investigated the neuroprotective effects of neurotrophins, including BDNF, in spinal cord injury. However, no report has described the effects of retrograde neurotrophic factor gene delivery in compressed spinal cords, including gene targeting and the potential to prevent neural cell apoptosis. METHODS AdV-BDNF or AdV-LacZ (as a control gene) was injected into the bilateral sternomastoid muscles of 18-week old twy/twy mice for retrograde gene delivery via the spinal accessory motor neurons. Heterozygous Institute of Cancer Research mice (+/twy), which do not undergo spontaneous spinal compression, were used as a control for the effects of such compression on gene delivery. The localization and cell specificity of β-galactosidase expression (produced by LacZ gene transfection) and BDNF expression in the spinal cord were examined by coimmunofluorescence staining for neural cell markers (NeuN, neurons; reactive immunology protein, oligodendrocytes; glial fibrillary acidic protein, astrocytes; OX-42, microglia) 4 weeks after gene injection. The possible neuroprotection afforded by retrograde AdV-BDNF gene delivery versus AdV-LacZ-transfected control mice was assessed by scoring the prevalence of apoptotic cells (terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling-positive cells) and immunoreactivity to active caspases -3, -8, and -9, p75, neurofilament 200 kD (NF), and for the oligodendroglial progenitor marker, NG2. RESULTS.: Four weeks after injection, the retrograde delivery of the LacZ marker gene was identified in cervical spinal neurons and some glial cells, including oligodendrocytes in the white matter of the spinal cord, in both the twy/twy mouse and the heterozygous Institute of Cancer Research mouse (+/twy). In the compressed spinal cord of twy/twy mouse, AdV-BDNF gene transfection resulted in a significant decrease in the number of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling-positive cells present in the spinal cord and a downregulation in the caspase apoptotic pathway compared with AdV-LacZ (control) gene transfection. There was a marked and significant increase in the areas of the spinal cord of AdV-BDNF-injected mice that were NF- and NG2-immunopositive compared with AdV-LacZ-injected mice, indicating the increased presence of neurons and oligodendrocytes in response to BDNF transfection. CONCLUSION Our results demonstrate that targeted retrograde BDNF gene delivery suppresses apoptosis in neurons and oligodendrocytes in the chronically compressed spinal cord of twy/twy mouse. Further work is required to establish whether this method of gene delivery may provide neuroprotective effects in other situations of compressive spinal cord injury.
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Wang J, Ma C, Rong W, Jing H, Hu X, Liu X, Jiang L, Wei F, Liu Z. Bog bilberry anthocyanin extract improves motor functional recovery by multifaceted effects in spinal cord injury. Neurochem Res 2012; 37:2814-25. [PMID: 23001399 DOI: 10.1007/s11064-012-0883-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Revised: 08/09/2012] [Accepted: 08/13/2012] [Indexed: 11/29/2022]
Abstract
The aim of this study was to determine the therapeutic efficiency of bog bilberry anthocyanin extract (BBAE) treatment starting 1 d after spinal cord injury (SCI) in rats and to investigate the underlying mechanism. The BBAE contained cyanidin-3-glucoside, malvidin-3-galactoside and malvidin-3-glucoside. SCI models were induced using the weight-drop method in Sprague-Dawley rats and additionally with sham group (laminectomy only). The animals were divided into four groups: vehicle-treated group; 10 mg/kg BBAE-treated group; 20 mg/kg BBAE-treated group; sham group. BBAE-treated or vehicle-treated group was administered orally at one day after SCI and then daily for 8 weeks. Locomotor functional recovery was assessed during the 8 weeks post operation period by performing a Basso, Beattie, and Bresnahan (BBB) locomotor score test. At the end of study, the animals were killed, and 1.5 cm segments of spinal cord encompassing the injury site were removed for immunohistochemistry, histopathological and western blotting analysis. Immunohistochemistry for GFAP, aggrecan, neurocan and NeuN was used to assess the degree of astrocytic glial scar formation and neuron survival. Immunohistochemistry and western blotting analysis for TNF-α, IL-6, IL-1β was used to evaluate the anti-inflammation effect of BBAE. To evaluate its inhibition effect on the astrocytes, we performed the MTT assay and immunohistochemistry for Ki67 in vitro. Results show that the BBAE-treated animals showed significantly better locomotor functional recovery, neuron death and smaller glial scar formation after spinal cord injury in vivo. In addition, BBAE administration could inhibit astrocyte proliferation in vivo and vitro. Therefore, BBAE may be useful as a promising therapeutic agent for SCI.
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Affiliation(s)
- Jun Wang
- Department of Orthopedics, Peking University Third Hospital, 49 North Garden Rd, Haidian, Beijing 100191, People's Republic of China.
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18
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Otsuka S, Adamson C, Sankar V, Gibbs KM, Kane-Goldsmith N, Ayer J, Babiarz J, Kalinski H, Ashush H, Alpert E, Lahav R, Feinstein E, Grumet M. Delayed intrathecal delivery of RhoA siRNA to the contused spinal cord inhibits allodynia, preserves white matter, and increases serotonergic fiber growth. J Neurotrauma 2012; 28:1063-76. [PMID: 21443453 DOI: 10.1089/neu.2010.1568] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
RhoA is a key regulator of the actin cytoskeleton that is upregulated after spinal cord injury (SCI). We analyzed different methods for siRNA delivery and developed siRNAs targeting RhoA (siRhoA) for SCI treatment. Cy 3.5-labeled siRNA delivered at the time of SCI yielded fluorescence in several cell types in the injury site. Intraspinal injections of chemically stabilized siRhoA into the spinal cord of injured rats reduced RhoA protein levels after 1 week and improved hindlimb walking over 6 weeks. To explore a less invasive route, we tested intrathecal injection of Cy 3.5-labeled siRNA via lumbar puncture 1 day after SCI, which resulted in robust uptake in the T9-T10 injury site. Lumbar injection of siRhoA 1 day after SCI reduced RhoA mRNA and protein levels 3 days after injection. Although siRhoA treatment did not yield significant improvement in locomotion, it decreased tactile hypersensitivity significantly compared to controls. Histological analysis at 8 weeks showed significant improvement in white matter sparing with siRhoA compared to control siRNA. siRhoA treatment also resulted in less accumulation of ED1+macrophages, increased PKC-γ immunoreactivity in the corticospinal tract rostral to the injury site, and increased serotonergic fiber growth 12 mm caudal to the contusion site. The ability of siRhoA to preserve white matter and promote serotonergic axonal regrowth caudal to the injury site is likely to suppress allodynia. This provides justification for considering clinical development of RhoA inhibitors to treat SCI sub-acutely to reduce allodynia, which occurs frequently in SCI patients.
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Affiliation(s)
- Seiji Otsuka
- W.M. Keck Center for Collaborative Neuroscience, Rutgers Stem Cell Research Center, Department of Cell Biology & Neuroscience, Rutgers, State University of New Jersey, Piscataway, New Jersey 08854-8082, USA
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Abstract
Spinal cord injury (SCI) has multiple consequences, ranging from molecular imbalances to glial scar formation to functional impairments. It is logical to think that a combination of single treatments implemented in the right order and at the right time will be required to repair the spinal cord. However, the single treatments that compose the combination therapy will need to be chosen with caution as many have multiple outcomes that may or may not be synergistic. Single treatments may also elicit unwanted side-effects and/or effects that would decrease the repair potential of other components and/or the entire combination therapy. In this chapter a number of single treatments are discussed with respect to their multiplicity of action. These include strategies to boost growth and survival (such as neurotrophins and cyclic AMP) and strategies to reduce inhibitory factors (such as antimyelin-associated growth inhibitors and digestion of glial scar-associated inhibitors). We also present an overview of combination therapies that have successfully or unsuccessfully been tested in the laboratory using animal models. To effectively design a combination therapy a number of considerations need to be made such as the nature and timing of the treatments and the method for delivery. This chapter discusses these issues as well as considerations related to chronic SCI and the logistics of bringing combination therapies to the clinic.
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Affiliation(s)
- M Oudega
- Departments of Physical Medicine and Rehabilitation, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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Geremia NM, Bao F, Rosenzweig TE, Hryciw T, Weaver L, Dekaban GA, Brown A. CD11d Antibody Treatment Improves Recovery in Spinal Cord-Injured Mice. J Neurotrauma 2011; 29:539-50. [PMID: 22044160 DOI: 10.1089/neu.2011.1976] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Acute administration of a monoclonal antibody (mAb) raised against the CD11d subunit of the leukocyte CD11d/CD18 integrin after spinal cord injury (SCI) in the rat greatly improves neurological outcomes. This has been chiefly attributed to the reduced infiltration of neutrophils into the injured spinal cord in treated rats. More recently, treating spinal cord-injured mice with a Ly-6G neutrophil-depleting antibody was demonstrated to impair neurological recovery. These disparate results could be due to different mechanisms of action utilized by the two antibodies, or due to differences in the inflammatory responses between mouse and rat that are triggered by SCI. To address whether the anti-CD11d treatment would be effective in mice, a CD11d mAb (205C) or a control mAb (1B7) was administered intravenously at 2, 24, and 48 h after an 8-g clip compression injury at the fourth thoracic spinal segment. The anti-CD11d treatment reduced neutrophil infiltration into the injured mouse spinal cord and was associated with increased white matter sparing and reductions in myeloperoxidase (MPO) activity, reactive oxygen species, lipid peroxidation, and scar formation. These improvements in the injured spinal cord microenvironment were accompanied by increased serotonin (5-HT) immunoreactivity below the level of the lesion and improved locomotor recovery. Our results with the 205C CD11d mAb treatment complement previous work using this anti-integrin treatment in a rat model of SCI.
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Affiliation(s)
- Nicole M Geremia
- The Spinal Cord Injury Team, Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada.
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21
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Uchida K, Nakajima H, Watanabe S, Yayama T, Guerrero AR, Inukai T, Hirai T, Sugita D, Johnson WE, Baba H. Apoptosis of neurons and oligodendrocytes in the spinal cord of spinal hyperostotic mouse (twy/twy): possible pathomechanism of human cervical compressive myelopathy. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2011; 21:490-7. [PMID: 21935678 PMCID: PMC3296863 DOI: 10.1007/s00586-011-2025-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Revised: 08/14/2011] [Accepted: 09/08/2011] [Indexed: 02/03/2023]
Abstract
Introduction Cervical compressive myelopathy is the most serious complication of cervical spondylosis or ossification of the posterior longitudinal ligament (OPLL) and the most frequent cause of spinal cord dysfunction. There is little information on the exact pathophysiological mechanism responsible for the progressive loss of neural tissue in the spinal cord of such patients. In this study, we used the spinal hyperostotic mouse (twy/twy) as a suitable model of human spondylosis, and OPLL to investigate the cellular and molecular changes in the spinal cord. Mutant twy/twy mouse developed ossification of the ligamentum flavum at C2–C3 and exhibited progressive paralysis. Materials and methods The mutant twy/twy mice, aged 16 and 24 weeks, were used in the present study. The cervical spinal cord was analyzed histologically and immunohistochemically. Results We observed that a significant correlation between the proportion of apoptotic oligodendrocytes in the compressed area of the spinal cord and the magnitude of cord compression. Immunohistochemical analysis indicated overexpression of TNFR1, CD95, and p75NTR in the twy/twy mice, which was localized by the immunofluorescence in the neurons and oligodendrocytes. Conclusion The expression of such factors seems to play at least some role in the apoptotic process, which probably contributes to axonal degeneration and demyelination in the twy/twy mice spinal cords with severe compression. Electronic supplementary material The online version of this article (doi:10.1007/s00586-011-2025-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kenzo Uchida
- Department of Orthopaedics and Rehabilitation Medicine, Faculty of Medical Sciences, University of Fukui, Matsuoka Shimoaizuki 23-3, Eiheiji, Fukui, 910-1193, Japan.
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22
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Tan J, Clarke M, Barrett G, Millard R. The p75 neurotrophin receptor protects primary auditory neurons against acoustic trauma in mice. Hear Res 2010; 268:46-59. [PMID: 20466052 DOI: 10.1016/j.heares.2010.04.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 04/27/2010] [Accepted: 04/28/2010] [Indexed: 12/19/2022]
Abstract
In the adult rodent inner ear, p75NTR is weakly expressed in primary auditory neurons (PANs) and cochlear Schwann cells. When the organ of Corti is damaged during trauma, its expression dramatically increases. It is unclear what role p75NTR plays under these conditions. Characterisation of p75NTR mutant mice reveals that altering genetic backgrounds can differentially affect the survival of PANs in mutant mice. To conclusively elucidate the physiological role of p75NTR in the cochlea, we challenged wild type (p75NTR +/+) and mutant (p75NTR -/-) mice with an acoustic trauma at 130 dB SPL, 10 kHz for 2 h. This produces a permanent auditory threshold shift >40 dB SPL, damages the organ of Corti and causes secondary degeneration of PANs. After exposure, mice were maintained for 3-9 weeks. Interestingly, survival of PANs in p75NTR -/- mice was significantly compromised in all time-points when compared to wild type mice: 15% reduction after 3 weeks (n = 6), 32% reduction after 6 weeks (n = 6) and 26% reduction after 9 weeks (n = 6-8). Therefore, our data do not support a role of p75NTR as a death inducer in PANs but show its crucial role in protecting PANs.
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MESH Headings
- Acoustic Stimulation
- Animals
- Auditory Threshold
- Cell Death
- Cochlea/innervation
- Cochlear Nerve/injuries
- Cochlear Nerve/metabolism
- Cochlear Nerve/pathology
- Disease Models, Animal
- Evoked Potentials, Auditory, Brain Stem
- Genotype
- Hearing Loss, Noise-Induced/genetics
- Hearing Loss, Noise-Induced/metabolism
- Hearing Loss, Noise-Induced/pathology
- Hearing Loss, Noise-Induced/physiopathology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Noise/adverse effects
- Phenotype
- Receptors, Nerve Growth Factor/deficiency
- Receptors, Nerve Growth Factor/genetics
- Receptors, Nerve Growth Factor/metabolism
- Schwann Cells/metabolism
- Species Specificity
- Time Factors
- Up-Regulation
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Affiliation(s)
- Justin Tan
- The Bionic Ear Institute, 384-388 Albert St, East Melbourne, Victoria 3002, Australia.
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23
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Tumor necrosis factor-alpha and its receptors contribute to apoptosis of oligodendrocytes in the spinal cord of spinal hyperostotic mouse (twy/twy) sustaining chronic mechanical compression. Spine (Phila Pa 1976) 2009; 34:2848-57. [PMID: 19949368 DOI: 10.1097/brs.0b013e3181b0d078] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN.: To examine the distribution of apoptotic cells and expression of tumor necrosis factor (TNF)-alpha and its receptors in the spinal hyperostotic mouse (twy/twy) with chronic cord compression using immunohistochemical methods. OBJECTIVE.: To study the mechanisms of apoptosis, particularly in oligodendrocytes, which could contribute to degenerative change and demyelination in chronic mechanical cord compression. SUMMARY OF BACKGROUND DATA.: TNF-alpha acts as an external signal initiating apoptosis in neurons and oligodendrocytes after spinal cord injury. Chronic spinal cord compression caused neuronal loss, myelin destruction, and axonal degeneration. However, the biologic mechanisms of apoptosis in chronically compressed spinal cord remain unclear. METHODS.: The cervical spinal cord of 34 twy mice aged 20 to 24 weeks and 11 control animals were examined. The apoptotic cells were detected by the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) staining. The expression and the localization of TNF-alpha, TNF receptor 1 (TNFR1), and TNF receptor 2 (TNFR2) were examined using immunoblot and immnohistochemical analysis. RESULTS.: The number of TUNEL-positive cells in the white matter increased with the severity of compression, which was further increased bilaterally in the white matter of twy/twy mice. Double immunofluorescence staining showed that the number of cells positive for TUNEL and RIP, a marker of oligodendrocytes, increased in the white matter with increased severity of cord compression. Immunoblot analysis demonstrated overexpression of TNF-alpha, TNFR1, and TNFR2 in severe compression. The expression of TNF-alpha appeared in local cells including microglia while that of TNFR1 and TNFR2 was noted in apoptotic oligodendrocytes. CONCLUSION.: Our results suggested that the proportion of apoptotic oligodendrocytes, causing spongy axonal degeneration and demyelination, correlated with the magnitude of cord compression and that overexpression of TNF-alpha, TNFR1, and TNFR2 seems to participate in apoptosis of such cells in the chronically compressed spinal cord.
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Rowland JW, Hawryluk GWJ, Kwon B, Fehlings MG. Current status of acute spinal cord injury pathophysiology and emerging therapies: promise on the horizon. Neurosurg Focus 2009; 25:E2. [PMID: 18980476 DOI: 10.3171/foc.2008.25.11.e2] [Citation(s) in RCA: 502] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
This review summarizes the current understanding of spinal cord injury pathophysiology and discusses important emerging regenerative approaches that have been translated into clinical trials or have a strong potential to do so. The pathophysiology of spinal cord injury involves a primary mechanical injury that directly disrupts axons, blood vessels, and cell membranes. This primary mechanical injury is followed by a secondary injury phase involving vascular dysfunction, edema, ischemia, excitotoxicity, electrolyte shifts, free radical production, inflammation, and delayed apoptotic cell death. Following injury, the mammalian central nervous system fails to adequately regenerate due to intrinsic inhibitory factors expressed on central myelin and the extracellular matrix of the posttraumatic gliotic scar. Regenerative approaches to block inhibitory signals including Nogo and the Rho-Rho-associated kinase pathways have shown promise and are in early stages of clinical evaluation. Cell-based strategies including using neural stem cells to remyelinate spared axons are an attractive emerging approach.
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Affiliation(s)
- James W Rowland
- Division of Genetics and Development, Toronto Western Research Institute, Institute of Medical Science, University of Toronto, Canada
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25
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Xu M, Remillard CV, Sachs BD, Makino A, Platoshyn O, Yao W, Dillmann WH, Akassoglou K, Yuan JXJ. p75 neurotrophin receptor regulates agonist-induced pulmonary vasoconstriction. Am J Physiol Heart Circ Physiol 2008; 295:H1529-38. [PMID: 18689502 PMCID: PMC2593496 DOI: 10.1152/ajpheart.00115.2008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Accepted: 07/29/2008] [Indexed: 11/22/2022]
Abstract
A member of the TNF receptor family, the p75 neurotrophin receptor (p75(NTR)) has been previously shown to play a role in the regulation of fibrin deposition in the lung. However, the role of p75(NTR) in the regulation of pulmonary vascular tone in the lung is unknown. In the present study, we evaluated the expression of p75(NTR) in mouse pulmonary arteries and the putative role of p75(NTR) in modulating pulmonary vascular tone and agonist responsiveness using wild-type (WT) and p75(NTR) knockout (p75(-/-)) mice. Our data indicated that p75(NTR) is expressed in both smooth muscle and endothelial cells within the pulmonary vascular wall in WT mice. Pulmonary artery rings from p75(-/-) mice exhibited significantly elevated active tension due to endothelin-1-mediated Ca(2+) influx. Furthermore, the contraction due to capacitative Ca(2+) entry (CCE) in response to phenylephrine-mediated active depletion of intracellular Ca(2+) stores was significantly enhanced compared with WT rings. The contraction due to CCE induced by passive store depletion, however, was comparable between WT and p75(-/-) rings. Active tension induced by serotonin, U-46619 (a thromboxane A(2) analog), thrombin, 4-aminopyridine (a K(+) channel blocker), and high extracellular K(+) in p75(-/-) rings was similar to that in WT rings. Deletion of p75(NTR) did not alter pulmonary vasodilation to sodium nitroprusside (a nitric oxide donor). These data suggest that intact p75(NTR) signaling may play a role in modulating pulmonary vasoconstriction induced by endothelin-1 and by active store depletion.
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Affiliation(s)
- Minlin Xu
- Departments of Medicine, University of California-San Diego, La Jolla, California 92093-0725, USA
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Hajebrahimi Z, Mowla SJ, Movahedin M, Tavallaei M. Gene expression alterations of neurotrophins, their receptors and prohormone convertases in a rat model of spinal cord contusion. Neurosci Lett 2008; 441:261-6. [PMID: 18585435 DOI: 10.1016/j.neulet.2008.06.046] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2008] [Revised: 06/14/2008] [Accepted: 06/18/2008] [Indexed: 12/17/2022]
Abstract
We have used a semi-quantitative RT-PCR approach to investigate the alterations in the expression of the main regulators of neuronal survival and death, neurotrophins (NTs), NT receptors, and prohormone convertases (PC), in a rat model of spinal cord contusion. Our results revealed that the expression of the members of NT family (Nerve-Growth Factor (NGF), Brain-Derived Neurotrophic Factor (BDNF), and Neurotrophin-3 (NT-3)) is significantly declined in the injured spinal cord, as early as 6h after the induction of the contusion. The expression was recovered afterward to that of the control levels. Furthermore, the expression of all NTs high-affinity Trk receptors decreased severely after the contusion. While the expression of TrkA and TrkC were completely shut down after 6 and 12h after injury respectively, the expression of TrkB receptor declined at 12h after injury and remained at this low level thereafter. In contrast to the pattern of Trk receptor expression, p75NTR receptor showed a significant upregulation after contusion. The expression of PC members functioning in the constitutive secretory pathway, i.e. furin, PACE4 and PC7, increased after damage, while the expression of PC members acting in regulated secretory pathway, PC1 and PC2, reduced after spinal cord injury. All together, the down-regulation of NTs, their designated Trk receptors and PC1/PC2 enzymes along with an upregulation of p75NTR promote neuronal death after injury. Our results suggest that either overexpression of NTs, Trk receptors and PC1/PC2 or interfering with the expression of p75NTR in host and/or grafted cells before transplantation could increase the success of the transplantation.
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Affiliation(s)
- Zahra Hajebrahimi
- Department of Genetics, Faculty of Basic Sciences, Tarbiat Modares University, P.O. Box: 14115-175, Tehran, Iran
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Andrade MSR, Hanania FR, Daci K, Leme RJA, Chadi G. Contuse lesion of the rat spinal cord of moderate intensity leads to a higher time-dependent secondary neurodegeneration than severe one. An open-window for experimental neuroprotective interventions. Tissue Cell 2008; 40:143-56. [PMID: 18207478 DOI: 10.1016/j.tice.2007.11.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Revised: 11/12/2007] [Accepted: 11/14/2007] [Indexed: 11/27/2022]
Abstract
Secondary neurodegeneration takes place in the surrounding tissue of spinal cord trauma and modifies substantially the prognosis, considering the small diameter of its transversal axis. We analyzed neuronal and glial responses in rat spinal cord after different degree of contusion promoted by the NYU Impactor. Rats were submitted to vertebrae laminectomy and received moderate or severe contusions. Control animals were sham operated. After 7 and 30 days post surgery, stereological analysis of Nissl staining cellular profiles showed a time progression of the lesion volume after moderate injury, but not after severe injury. The number of neurons was not altered cranial to injury. However, same degree of diminution was seen in the caudal cord 30 days after both severe and moderate injuries. Microdensitometric image analysis demonstrated a microglial reaction in the white matter 30 days after a moderate contusion and showed a widespread astroglial reaction in the white and gray matters 7 days after both severities. Astroglial activation lasted close to lesion and in areas related to Wallerian degeneration. Data showed a more protracted secondary degeneration in rat spinal cord after mild contusion, which offered an opportunity for neuroprotective approaches. Temporal and regional glial responses corroborated to diverse glial cell function in lesioned spinal cord.
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Affiliation(s)
- M S R Andrade
- Neuroregeneration Center, Experimental Neurology, Department of Neurology, University of São Paulo School of Medicine, Av. Dr. Arnaldo, 455, CEP: 01246-903, São Paulo, Brazil
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