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Bou Ghanem GO, Wareham LK, Calkins DJ. Addressing neurodegeneration in glaucoma: Mechanisms, challenges, and treatments. Prog Retin Eye Res 2024; 100:101261. [PMID: 38527623 DOI: 10.1016/j.preteyeres.2024.101261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 03/15/2024] [Accepted: 03/19/2024] [Indexed: 03/27/2024]
Abstract
Glaucoma is the leading cause of irreversible blindness globally. The disease causes vision loss due to neurodegeneration of the retinal ganglion cell (RGC) projection to the brain through the optic nerve. Glaucoma is associated with sensitivity to intraocular pressure (IOP). Thus, mainstay treatments seek to manage IOP, though many patients continue to lose vision. To address neurodegeneration directly, numerous preclinical studies seek to develop protective or reparative therapies that act independently of IOP. These include growth factors, compounds targeting metabolism, anti-inflammatory and antioxidant agents, and neuromodulators. Despite success in experimental models, many of these approaches fail to translate into clinical benefits. Several factors contribute to this challenge. Firstly, the anatomic structure of the optic nerve head differs between rodents, nonhuman primates, and humans. Additionally, animal models do not replicate the complex glaucoma pathophysiology in humans. Therefore, to enhance the success of translating these findings, we propose two approaches. First, thorough evaluation of experimental targets in multiple animal models, including nonhuman primates, should precede clinical trials. Second, we advocate for combination therapy, which involves using multiple agents simultaneously, especially in the early and potentially reversible stages of the disease. These strategies aim to increase the chances of successful neuroprotective treatment for glaucoma.
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Affiliation(s)
- Ghazi O Bou Ghanem
- Vanderbilt Eye Institute, Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Lauren K Wareham
- Vanderbilt Eye Institute, Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - David J Calkins
- Vanderbilt Eye Institute, Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, TN, USA.
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2
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Basavarajappa D, Galindo-Romero C, Gupta V, Agudo-Barriuso M, Gupta VB, Graham SL, Chitranshi N. Signalling pathways and cell death mechanisms in glaucoma: Insights into the molecular pathophysiology. Mol Aspects Med 2023; 94:101216. [PMID: 37856930 DOI: 10.1016/j.mam.2023.101216] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 09/25/2023] [Accepted: 10/02/2023] [Indexed: 10/21/2023]
Abstract
Glaucoma is a complex multifactorial eye disease manifesting in retinal ganglion cell (RGC) death and optic nerve degeneration, ultimately causing irreversible vision loss. Research in recent years has significantly enhanced our understanding of RGC degenerative mechanisms in glaucoma. It is evident that high intraocular pressure (IOP) is not the only contributing factor to glaucoma pathogenesis. The equilibrium of pro-survival and pro-death signalling pathways in the retina strongly influences the function and survival of RGCs and optic nerve axons in glaucoma. Molecular evidence from human retinal tissue analysis and a range of experimental models of glaucoma have significantly contributed to unravelling these mechanisms. Accumulating evidence reveals a wide range of molecular signalling pathways that can operate -either alone or via intricate networks - to induce neurodegeneration. The roles of several molecules, including neurotrophins, interplay of intracellular kinases and phosphates, caveolae and adapter proteins, serine proteases and their inhibitors, nuclear receptors, amyloid beta and tau, and how their dysfunction affects retinal neurons are discussed in this review. We further underscore how anatomical alterations in various animal models exhibiting RGC degeneration and susceptibility to glaucoma-related neuronal damage have helped to characterise molecular mechanisms in glaucoma. In addition, we also present different regulated cell death pathways that play a critical role in RGC degeneration in glaucoma.
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Affiliation(s)
- Devaraj Basavarajappa
- Macquarie Medical School, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia.
| | - Caridad Galindo-Romero
- Experimental Ophthalmology Group, Instituto Murciano de Investigación Biosanitaria Virgen de la Arrixaca (IMIB-Arrixaca) & Ophthalmology Department, Universidad de Murcia, Murcia, Spain
| | - Vivek Gupta
- Macquarie Medical School, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| | - Marta Agudo-Barriuso
- Experimental Ophthalmology Group, Instituto Murciano de Investigación Biosanitaria Virgen de la Arrixaca (IMIB-Arrixaca) & Ophthalmology Department, Universidad de Murcia, Murcia, Spain
| | - Veer B Gupta
- School of Medicine, Deakin University, Melbourne, VIC, Australia
| | - Stuart L Graham
- Macquarie Medical School, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| | - Nitin Chitranshi
- Macquarie Medical School, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia.
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3
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Mirzahosseini G, Adam JM, Nasoohi S, El-Remessy AB, Ishrat T. Lost in Translation: Neurotrophins Biology and Function in the Neurovascular Unit. Neuroscientist 2023; 29:694-714. [PMID: 35769016 DOI: 10.1177/10738584221104982] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The neurovascular unit (NVU) refers to the functional building unit of the brain and the retina, where neurons, glia, and microvasculature orchestrate to meet the demand of the retina's and brain's function. Neurotrophins (NTs) are structural families of secreted proteins and are known for exerting neurotrophic effects on neuronal differentiation, survival, neurite outgrowth, synaptic formation, and plasticity. NTs include several molecules, such as nerve growth factor, brain-derived neurotrophic factor, NT-3, NT-4, and their precursors. Furthermore, NTs are involved in signaling pathways such as inflammation, apoptosis, and angiogenesis in a nonneuronal cell type. Interestingly, NTs and the precursors can bind and activate the p75 neurotrophin receptor (p75NTR) at low and high affinity. Mature NTs bind their cognate tropomyosin/tyrosine-regulated kinase receptors, crucial for maintenance and neuronal development in the brain and retina axis. Activation of p75NTR results in neuronal apoptosis and cell death, while tropomysin receptor kinase upregulation contributes to differentiation and cell growth. Recent findings indicate that modulation of NTs and their receptors contribute to neurovascular dysfunction in the NVU. Several chronic metabolic and acute ischemic diseases affect the NVU, including diabetic and ischemic retinopathy for the retina, as well as stroke, acute encephalitis, and traumatic brain injury for the brain. This work aims to review the current evidence through published literature studying the impact of NTs and their receptors, including the p75NTR receptor, on the injured and healthy brain-retina axis.
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Affiliation(s)
- Golnoush Mirzahosseini
- Department of Anatomy and Neurobiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, USA
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Justin Mark Adam
- Department of Medicine, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Sanaz Nasoohi
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | | - Tauheed Ishrat
- Department of Anatomy and Neurobiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, USA
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, TN, USA
- Neuroscience Institute, University of Tennessee Health Science Center, Memphis, TN, USA
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4
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Alarcon-Martinez L, Shiga Y, Villafranca-Baughman D, Cueva Vargas JL, Vidal Paredes IA, Quintero H, Fortune B, Danesh-Meyer H, Di Polo A. Neurovascular dysfunction in glaucoma. Prog Retin Eye Res 2023; 97:101217. [PMID: 37778617 DOI: 10.1016/j.preteyeres.2023.101217] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 09/23/2023] [Accepted: 09/25/2023] [Indexed: 10/03/2023]
Abstract
Retinal ganglion cells, the neurons that die in glaucoma, are endowed with a high metabolism requiring optimal provision of oxygen and nutrients to sustain their activity. The timely regulation of blood flow is, therefore, essential to supply firing neurons in active areas with the oxygen and glucose they need for energy. Many glaucoma patients suffer from vascular deficits including reduced blood flow, impaired autoregulation, neurovascular coupling dysfunction, and blood-retina/brain-barrier breakdown. These processes are tightly regulated by a community of cells known as the neurovascular unit comprising neurons, endothelial cells, pericytes, Müller cells, astrocytes, and microglia. In this review, the neurovascular unit takes center stage as we examine the ability of its members to regulate neurovascular interactions and how their function might be altered during glaucomatous stress. Pericytes receive special attention based on recent data demonstrating their key role in the regulation of neurovascular coupling in physiological and pathological conditions. Of particular interest is the discovery and characterization of tunneling nanotubes, thin actin-based conduits that connect distal pericytes, which play essential roles in the complex spatial and temporal distribution of blood within the retinal capillary network. We discuss cellular and molecular mechanisms of neurovascular interactions and their pathophysiological implications, while highlighting opportunities to develop strategies for vascular protection and regeneration to improve functional outcomes in glaucoma.
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Affiliation(s)
- Luis Alarcon-Martinez
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada; Centre for Eye Research Australia, University of Melbourne, Melbourne, Australia
| | - Yukihiro Shiga
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Deborah Villafranca-Baughman
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Jorge L Cueva Vargas
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Isaac A Vidal Paredes
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Heberto Quintero
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada
| | - Brad Fortune
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Healthy, Portland, OR, USA
| | - Helen Danesh-Meyer
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Adriana Di Polo
- Department of Neuroscience, Université de Montréal, PO Box 6128, Station centre-ville, Montreal, QC, Canada; Neuroscience Division, Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), 900 Saint Denis Street, Montreal, QC, Canada.
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5
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Subirada PV, Tovo A, Vaglienti MV, Luna Pinto JD, Saragovi HU, Sánchez MC, Anastasía A, Barcelona PF. Etiological Roles of p75 NTR in a Mouse Model of Wet Age-Related Macular Degeneration. Cells 2023; 12:cells12020297. [PMID: 36672232 PMCID: PMC9856885 DOI: 10.3390/cells12020297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 01/04/2023] [Accepted: 01/06/2023] [Indexed: 01/13/2023] Open
Abstract
Choroidal neovascularization (CNV) is a pathological angiogenesis of the choroidal plexus of the retina and is a key feature in the wet form of age-related macular degeneration. Mononuclear phagocytic cells (MPCs) are known to accumulate in the subretinal space, generating a chronic inflammatory state that promotes the growth of the choroidal neovasculature. However, how the MPCs are recruited and activated to promote CNV pathology is not fully understood. Using genetic and pharmacological tools in a mouse model of laser-induced CNV, we demonstrate a role for the p75 neurotrophin receptor (p75NTR) in the recruitment of MPCs, in glial activation, and in vascular alterations. After laser injury, expression of p75NTR is increased in activated Muller glial cells near the CNV area in the retina and the retinal pigmented epithelium (RPE)-choroid. In p75NTR knockout mice (p75NTR KO) with CNV, there is significantly reduced recruitment of MPCs, reduced glial activation, reduced CNV area, and the retinal function is preserved, as compared to wild type mice with CNV. Notably, a single intravitreal injection of a pharmacological p75NTR antagonist in wild type mice with CNV phenocopied the results of the p75NTR KO mice. Our results demonstrate that p75NTR is etiological in the development of CNV.
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Affiliation(s)
| | - Albana Tovo
- Departamento de Bioquímica Clínica, Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET), Universidad Nacional de Córdoba, Córdoba 5016, Argentina
| | - María Victoria Vaglienti
- Departamento de Bioquímica Clínica, Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET), Universidad Nacional de Córdoba, Córdoba 5016, Argentina
| | | | - Horacio Uri Saragovi
- Lady Davis Research Institute-Jewish General Hospital, Center for Experimental Therapeutics, Department of Pharmacology and Therapeutics, Department of Ophthalmology and Vision Sciences, McGill University, Montreal, QC H3T 1E2, Canada
| | - Maria Cecilia Sánchez
- Departamento de Bioquímica Clínica, Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET), Universidad Nacional de Córdoba, Córdoba 5016, Argentina
| | - Agustín Anastasía
- Instituto Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba 5016, Argentina
- Instituto Universitario de Ciencias Biomédicas de Córdoba (IUCBC), Córdoba 5016, Argentina
- Correspondence: (A.A.); (P.F.B.)
| | - Pablo Federico Barcelona
- Departamento de Bioquímica Clínica, Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET), Universidad Nacional de Córdoba, Córdoba 5016, Argentina
- Correspondence: (A.A.); (P.F.B.)
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Zhao L, Hou C, Yan N. Neuroinflammation in retinitis pigmentosa: Therapies targeting the innate immune system. Front Immunol 2022; 13:1059947. [PMID: 36389729 PMCID: PMC9647059 DOI: 10.3389/fimmu.2022.1059947] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Accepted: 10/17/2022] [Indexed: 11/13/2022] Open
Abstract
Retinitis pigmentosa (RP) is an important cause of irreversible blindness worldwide and lacks effective treatment strategies. Although mutations are the primary cause of RP, research over the past decades has shown that neuroinflammation is an important cause of RP progression. Due to the abnormal activation of immunity, continuous sterile inflammation results in neuron loss and structural destruction. Therapies targeting inflammation have shown their potential to attenuate photoreceptor degeneration in preclinical models. Regardless of variations in genetic background, inflammatory modulation is emerging as an important role in the treatment of RP. We summarize the evidence for the role of inflammation in RP and mention therapeutic strategies where available, focusing on the modulation of innate immune signals, including TNFα signaling, TLR signaling, NLRP3 inflammasome activation, chemokine signaling and JAK/STAT signaling. In addition, we describe epigenetic regulation, the gut microbiome and herbal agents as prospective treatment strategies for RP in recent advances.
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Affiliation(s)
- Ling Zhao
- Research Laboratory of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China,Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
| | - Chen Hou
- Research Laboratory of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China,Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
| | - Naihong Yan
- Research Laboratory of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China,*Correspondence: Naihong Yan,
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7
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Wong KA, Benowitz LI. Retinal Ganglion Cell Survival and Axon Regeneration after Optic Nerve Injury: Role of Inflammation and Other Factors. Int J Mol Sci 2022; 23:ijms231710179. [PMID: 36077577 PMCID: PMC9456227 DOI: 10.3390/ijms231710179] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 08/29/2022] [Accepted: 09/02/2022] [Indexed: 11/24/2022] Open
Abstract
The optic nerve, like most pathways in the mature central nervous system, cannot regenerate if injured, and within days, retinal ganglion cells (RGCs), the neurons that extend axons through the optic nerve, begin to die. Thus, there are few clinical options to improve vision after traumatic or ischemic optic nerve injury or in neurodegenerative diseases such as glaucoma, dominant optic neuropathy, or optic pathway gliomas. Research over the past two decades has identified several strategies to enable RGCs to regenerate axons the entire length of the optic nerve, in some cases leading to modest reinnervation of di- and mesencephalic visual relay centers. This review primarily focuses on the role of the innate immune system in improving RGC survival and axon regeneration, and its synergy with manipulations of signal transduction pathways, transcription factors, and cell-extrinsic suppressors of axon growth. Research in this field provides hope that clinically effective strategies to improve vision in patients with currently untreatable losses could become a reality in 5-10 years.
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Affiliation(s)
- Kimberly A. Wong
- Department of Neurosurgery, Boston Children’s Hospital and Harvard Medical School, Boston, MA 02115, USA
- Correspondence: (K.A.W.); (L.I.B.)
| | - Larry I. Benowitz
- Department of Neurosurgery, Boston Children’s Hospital and Harvard Medical School, Boston, MA 02115, USA
- F.M. Kirby Neurobiology Center, Boston Children’s Hospital, Boston, MA 02115, USA
- Department of Ophthalmology, Harvard Medical School, Boston, MA 02115, USA
- Correspondence: (K.A.W.); (L.I.B.)
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Statins Inhibit the Gliosis of MIO-M1, a Müller Glial Cell Line Induced by TRPV4 Activation. Int J Mol Sci 2022; 23:ijms23095190. [PMID: 35563594 PMCID: PMC9100994 DOI: 10.3390/ijms23095190] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 05/03/2022] [Accepted: 05/04/2022] [Indexed: 11/17/2022] Open
Abstract
We characterized Müller cell gliosis induced by the activation of transient receptor potential vanilloid-type 4 (TRPV4) and assessed whether statins could modulate the gliosis. The human Müller cell line, MIO-M1, was used to analyze the gliosis caused by glaucomatous stimulation. To induce Müller gliosis in MIO-M1 cells, GSK101 was used to activate TRPV4, and Müller gliosis was evaluated by analyzing vimentin, nestin, and glial fibrillary acidic protein (GFAP) expression. The expression level of TNF-α was determined by ELISA. To evaluate the GSK101 activation of the NF-κB pathway, p65 phosphorylation was measured by Western blotting, and the nuclear translocation of p65 and IκBα phosphorylation were assessed by immunostaining. To assess the effect of statins on MIO-M1 gliosis, cells were pretreated for 24 h with statins before GSK101 treatment. Vimentin, nestin, and GFAP expression were upregulated by GSK101, while statins effectively inhibited them. The expression of TNF-α was increased by GSK101. The phosphorylation and nuclear translocation of p65 and IκBα phosphorylation, which occurs prior to p65 activation, were induced. Statins suppressed the GSK101-mediated phosphorylation of IκBα and p65 translocation. Statins can mitigate gliosis in the human Müller cell line. Because TRPV4 activation in Müller cells reflects glaucoma pathophysiology, statins may have the potential to prevent RGC death.
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Qin X, Wang J, Chen S, Liu G, Wu C, Lv Q, He X, Bai X, Huang W, Liao H. Astrocytic p75 NTR expression provoked by ischemic stroke exacerbates the blood-brain barrier disruption. Glia 2022; 70:892-912. [PMID: 35064700 DOI: 10.1002/glia.24146] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 01/07/2022] [Accepted: 01/09/2022] [Indexed: 12/16/2022]
Abstract
The disruption of the blood-brain barrier (BBB) plays a critical role in the pathology of ischemic stroke. p75 neurotrophin receptor (p75NTR ) contributes to the disruption of the blood-retinal barrier in retinal ischemia. However, whether p75NTR influences the BBB permeability after acute cerebral ischemia remains unknown. The present study investigated the role and underlying mechanism of p75NTR on BBB integrity in an ischemic stroke mouse model, middle cerebral artery occlusion (MCAO). After 24 h of MCAO, astrocytes and endothelial cells in the infarct-affected brain area up-regulated p75NTR . Genetic p75NTR knockdown (p75NTR+/- ) or pharmacological inhibition of p75NTR using LM11A-31, a selective inhibitor of p75NTR , both attenuated brain damage and BBB leakage in MCAO mice. Astrocyte-specific conditional knockdown of p75NTR mediated with an adeno-associated virus significantly ameliorated BBB disruption and brain tissue damage, as well as the neurological functions after stroke. Further molecular biological examinations indicated that astrocytic p75NTR activated NF-κB and HIF-1α signals, which upregulated the expression of MMP-9 and vascular endothelial growth factor (VEGF), subsequently leading to tight junction degradation after ischemia. As a result, increased leukocyte infiltration and microglia activation exacerbated brain injury after stroke. Overall, our results provide novel insight into the role of astrocytic p75NTR in BBB disruption after acute cerebral ischemia. The p75NTR may therefore be a potential therapeutic target for the treatment of ischemic stroke.
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Affiliation(s)
- Xiaoying Qin
- New drug screening center, Jiangsu Center for Pharmacodynamics Research and Evaluation, China Pharmaceutical University, Nanjing, China
| | - Jianing Wang
- New drug screening center, Jiangsu Center for Pharmacodynamics Research and Evaluation, China Pharmaceutical University, Nanjing, China
| | - Shujian Chen
- New drug screening center, Jiangsu Center for Pharmacodynamics Research and Evaluation, China Pharmaceutical University, Nanjing, China
| | - Gang Liu
- New drug screening center, Jiangsu Center for Pharmacodynamics Research and Evaluation, China Pharmaceutical University, Nanjing, China
| | - Chaoran Wu
- New drug screening center, Jiangsu Center for Pharmacodynamics Research and Evaluation, China Pharmaceutical University, Nanjing, China
| | - Qunyu Lv
- New drug screening center, Jiangsu Center for Pharmacodynamics Research and Evaluation, China Pharmaceutical University, Nanjing, China
| | - Xinran He
- New drug screening center, Jiangsu Center for Pharmacodynamics Research and Evaluation, China Pharmaceutical University, Nanjing, China
| | - Xianshu Bai
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Wenhui Huang
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Hong Liao
- New drug screening center, Jiangsu Center for Pharmacodynamics Research and Evaluation, China Pharmaceutical University, Nanjing, China
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Li Q, Cheng Y, Zhang S, Sun X, Wu J. TRPV4-induced Müller cell gliosis and TNF-α elevation-mediated retinal ganglion cell apoptosis in glaucomatous rats via JAK2/STAT3/NF-κB pathway. J Neuroinflammation 2021; 18:271. [PMID: 34789280 PMCID: PMC8596927 DOI: 10.1186/s12974-021-02315-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 11/01/2021] [Indexed: 01/22/2023] Open
Abstract
Background Glaucoma, the leading cause of irreversible blindness worldwide, is a type of retinal disease characterized by the selective death of retinal ganglion cells (RGCs). However, the pathogenesis of glaucoma has not been fully elucidated. Transient receptor potential vanilloid 4 (TRPV4) is a pressure-sensitive and calcium-permeable cation channel. TRPV4 is widely distributed in the retina and its sustained activation leads to RGC death; indicating that TRPV4 may be a possible target for glaucoma treatment. Here, we investigated the effects of TRPV4 on RGC apoptosis in a rat model of chronic ocular hypertension (COH), then examined the mechanism underlying these effects. Methods The COH model was established by injection of micro-magnetic beads into the anterior chamber of adult male rats. The expression levels of TRPV4, glial fibrillary acidic protein, and inflammatory factors were assessed by immunohistochemistry and immunoblotting. RGC apoptosis and visual dysfunction were evaluated by TUNEL assay and photopic negative response. Functional expression of TRPV4 was examined by electrophysiology and calcium imaging. Real-time polymerase chain reaction and immunoblotting were employed to investigate the molecular mechanism underlying the effects of TRPV4 on tumor necrosis factor-α (TNF-α) release. Results We found that TRPV4 played an essential role in glaucoma, such that high levels of TRPV4 expression were associated with elevated intraocular pressure. Furthermore, TRPV4 activation was involved in glaucoma-induced RGC apoptosis and RGC-related reductions in visual function. Mechanistic investigation demonstrated that TRPV4 activation led to enhanced Müller cell gliosis and TNF-α release via the JAK2/STAT3/NF-kB pathway, while TRPV4 inhibition could reverse these effects. Finally, TRPV4 activation could lead to elevated expression of TNF receptor 1 in RGCs, while inhibition of TNF-α could reduce TRPV4-mediated RGC apoptosis. Conclusions TRPV4 activation induces Müller cell gliosis and TNF-α elevation via the JAK2/STAT3/NF-κB pathway, which may exacerbate RGC apoptosis in glaucoma; these results suggest that TRPV4 can serve as a therapeutic target in glaucoma treatment. Supplementary Information The online version contains supplementary material available at 10.1186/s12974-021-02315-8.
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Affiliation(s)
- Qian Li
- Eye Institute, Eye and ENT Hospital, College of Medicine, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China.,NHC Key Laboratory of Myopia, Fudan University, Shanghai, China.,Key Laboratory of Myopia, Chinese Academy of Medical Sciences, National Health Commission, #83 Fenyang Road, 200031, Shanghai, China
| | - Yun Cheng
- Eye Institute, Eye and ENT Hospital, College of Medicine, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China.,NHC Key Laboratory of Myopia, Fudan University, Shanghai, China.,Key Laboratory of Myopia, Chinese Academy of Medical Sciences, National Health Commission, #83 Fenyang Road, 200031, Shanghai, China
| | - Shenghai Zhang
- Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China.,NHC Key Laboratory of Myopia, Fudan University, Shanghai, China.,Key Laboratory of Myopia, Chinese Academy of Medical Sciences, National Health Commission, #83 Fenyang Road, 200031, Shanghai, China
| | - Xinghuai Sun
- Eye Institute, Eye and ENT Hospital, College of Medicine, Fudan University, Shanghai, China. .,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China. .,NHC Key Laboratory of Myopia, Fudan University, Shanghai, China. .,Key Laboratory of Myopia, Chinese Academy of Medical Sciences, National Health Commission, #83 Fenyang Road, 200031, Shanghai, China.
| | - Jihong Wu
- Eye Institute, Eye and ENT Hospital, College of Medicine, Fudan University, Shanghai, China. .,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China. .,NHC Key Laboratory of Myopia, Fudan University, Shanghai, China. .,Key Laboratory of Myopia, Chinese Academy of Medical Sciences, National Health Commission, #83 Fenyang Road, 200031, Shanghai, China.
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Brahimi F, Galan A, Siegel S, Szobota S, Sarunic MV, Foster AC, Saragovi HU. Therapeutic Neuroprotection by an Engineered Neurotrophin that Selectively Activates Tropomyosin Receptor Kinase (Trk) Family Neurotrophin Receptors but Not the p75 Neurotrophin Receptor. Mol Pharmacol 2021; 100:491-501. [PMID: 34470776 DOI: 10.1124/molpharm.121.000301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 08/12/2021] [Indexed: 11/22/2022] Open
Abstract
The neurotrophin growth factors bind and activate two types of cell surface receptors: the tropomyosin receptor kinase (Trk) family and p75. TrkA, TrkB, and TrkC are bound preferentially by nerve growth factor, brain-derived neurotrophic factor, and neurotrophin 3 (NT3), respectively, to activate neuroprotective signals. The p75 receptors are activated by all neurotrophins, and paradoxically in neurodegenerative disease p75 is upregulated and mediates neurotoxic signals. To test neuroprotection strategies, we engineered NT3 to broadly activate Trk receptors (mutant D) or to reduce p75 binding (mutant RK). We also combined these features in a molecule that activates TrkA, TrkB, and TrkC but has reduced p75 binding (mutant DRK). In neurodegenerative disease mouse models in vivo, the DRK protein is a superior therapeutic agent compared with mutant D, mutant RK, and wild-type neurotrophins and protects a broader range of stressed neurons. This work rationalizes a therapeutic strategy based on the biology of each type of receptor, avoiding activation of p75 toxicity while broadly activating neuroprotection in stressed neuronal populations expressing different Trk receptors. SIGNIFICANCE STATEMENT: The neurotrophins nerve growth factor, brain-derived neurotrophic factor, and neurotrophin 3 each can activate a tropomyosin receptor kinase (Trk) A, TrkB, or TrkC receptor, respectively, and all can activate a p75 receptor. Trks and p75 mediate opposite signals. We report the engineering of a protein that activates all Trks, combined with low p75 binding, as an effective therapeutic agent in vivo.
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Affiliation(s)
- Fouad Brahimi
- Lady Davis Institute-Jewish General Hospital (F.B., A.G., H.U.S.), Pharmacology and Therapeutics (H.U.S.), and Ophthalmology and Vision Science (H.U.S.), McGill University, Montreal, Quebec, Canada; Otonomy, Inc., San Diego, California (S.Si., S.Sz., A.C.F.); and School of Engineering Science, Simon Fraser University, British Columbia, Canada (M.V.S.)
| | - Alba Galan
- Lady Davis Institute-Jewish General Hospital (F.B., A.G., H.U.S.), Pharmacology and Therapeutics (H.U.S.), and Ophthalmology and Vision Science (H.U.S.), McGill University, Montreal, Quebec, Canada; Otonomy, Inc., San Diego, California (S.Si., S.Sz., A.C.F.); and School of Engineering Science, Simon Fraser University, British Columbia, Canada (M.V.S.)
| | - Sairey Siegel
- Lady Davis Institute-Jewish General Hospital (F.B., A.G., H.U.S.), Pharmacology and Therapeutics (H.U.S.), and Ophthalmology and Vision Science (H.U.S.), McGill University, Montreal, Quebec, Canada; Otonomy, Inc., San Diego, California (S.Si., S.Sz., A.C.F.); and School of Engineering Science, Simon Fraser University, British Columbia, Canada (M.V.S.)
| | - Stephanie Szobota
- Lady Davis Institute-Jewish General Hospital (F.B., A.G., H.U.S.), Pharmacology and Therapeutics (H.U.S.), and Ophthalmology and Vision Science (H.U.S.), McGill University, Montreal, Quebec, Canada; Otonomy, Inc., San Diego, California (S.Si., S.Sz., A.C.F.); and School of Engineering Science, Simon Fraser University, British Columbia, Canada (M.V.S.)
| | - Marinko V Sarunic
- Lady Davis Institute-Jewish General Hospital (F.B., A.G., H.U.S.), Pharmacology and Therapeutics (H.U.S.), and Ophthalmology and Vision Science (H.U.S.), McGill University, Montreal, Quebec, Canada; Otonomy, Inc., San Diego, California (S.Si., S.Sz., A.C.F.); and School of Engineering Science, Simon Fraser University, British Columbia, Canada (M.V.S.)
| | - Alan C Foster
- Lady Davis Institute-Jewish General Hospital (F.B., A.G., H.U.S.), Pharmacology and Therapeutics (H.U.S.), and Ophthalmology and Vision Science (H.U.S.), McGill University, Montreal, Quebec, Canada; Otonomy, Inc., San Diego, California (S.Si., S.Sz., A.C.F.); and School of Engineering Science, Simon Fraser University, British Columbia, Canada (M.V.S.)
| | - H Uri Saragovi
- Lady Davis Institute-Jewish General Hospital (F.B., A.G., H.U.S.), Pharmacology and Therapeutics (H.U.S.), and Ophthalmology and Vision Science (H.U.S.), McGill University, Montreal, Quebec, Canada; Otonomy, Inc., San Diego, California (S.Si., S.Sz., A.C.F.); and School of Engineering Science, Simon Fraser University, British Columbia, Canada (M.V.S.)
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12
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Cheng S, Wang HN, Xu LJ, Li F, Miao Y, Lei B, Sun X, Wang Z. Soluble tumor necrosis factor-alpha-induced hyperexcitability contributes to retinal ganglion cell apoptosis by enhancing Nav1.6 in experimental glaucoma. J Neuroinflammation 2021; 18:182. [PMID: 34419081 PMCID: PMC8380326 DOI: 10.1186/s12974-021-02236-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 08/09/2021] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Neuroinflammation plays an important role in the pathogenesis of glaucoma. Tumor necrosis factor-alpha (TNF-α) is a major pro-inflammatory cytokine released from activated retinal glial cells in glaucoma. Here, we investigated how TNF-α induces retinal ganglion cell (RGC) hyperexcitability and injury. METHODS Whole-cell patch-clamp techniques were performed to explore changes in spontaneous firing and evoked action potentials, and Na+ currents in RGCs. Both intravitreal injection of TNF-α and chronic ocular hypertension (COH) models were used. Western blotting, immunofluorescence, quantitative real-time polymerase chain reaction (q-PCR), and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) techniques were employed to investigate the molecular mechanisms of TNF-α effects on RGCs. RESULTS Intravitreal injection of soluble TNF-α significantly increased the spontaneous firing frequencies of RGCs in retinal slices. When the synaptic transmissions were blocked, more than 90% of RGCs still showed spontaneous firing; both the percentage of cells and firing frequency were higher than the controls. Furthermore, the frequency of evoked action potentials was also higher than the controls. Co-injection of the TNF-α receptor 1 (TNFR1) inhibitor R7050 eliminated the TNF-α-induced effects, suggesting that TNF-α may directly act on RGCs to induce cell hyperexcitability through activating TNFR1. In RGCs acutely isolated from TNF-α-injected retinas, Na+ current densities were upregulated. Perfusing TNF-α in RGCs of normal rats mimicked this effect, and the activation curve of Na+ currents shifted toward hyperpolarization direction, which was mediated through p38 MAPK and STAT3 signaling pathways. Further analysis revealed that TNF-α selectively upregulated Nav1.6 subtype of Na+ currents in RGCs. Similar to observations in retinas of rats with COH, intravitreal injection of TNF-α upregulated the expression of Nav1.6 proteins in both total cell and membrane components, which was reversed by the NF-κB inhibitor BAY 11-7082. Inhibition of TNFR1 blocked TNF-α-induced RGC apoptosis. CONCLUSIONS TNF-α/TNFR1 signaling induces RGC hyperexcitability by selectively upregulating Nav1.6 Na+ channels, thus contributing to RGC apoptosis in glaucoma.
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Affiliation(s)
- Shuo Cheng
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032 China
| | - Hong-Ning Wang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032 China
| | - Lin-Jie Xu
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032 China
| | - Fang Li
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032 China
| | - Yanying Miao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032 China
| | - Bo Lei
- Institute of Neuroscience and Third Affiliated Hospital, Henan Provincial People’s Hospital, Henan Eye Institute, Henan Eye Hospital, People’s Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, 450003 China
| | - Xinghuai Sun
- Department of Ophthalmology at Eye & ENT Hospital, Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, 200031 China
| | - Zhongfeng Wang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032 China
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13
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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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14
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Luo M, Shi X, Guo Q, Li S, Zhang Q, Sun X, Piao F. 2,5-Hexanedione induced apoptosis in rat spinal cord neurons and VSC4.1 cells via the proNGF/p75NTR and JNK pathways. Biosci Rep 2021; 41:BSR20204264. [PMID: 33792642 PMCID: PMC8035625 DOI: 10.1042/bsr20204264] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 02/04/2021] [Accepted: 03/31/2021] [Indexed: 01/10/2023] Open
Abstract
Increasing evidence suggests that n-hexane induces nerve injury via neuronal apoptosis induced by its active metabolite 2,5-hexanedione (HD). However, the underlying mechanism remains unknown. Studies have confirmed that pro-nerve growth factor (proNGF), a precursor of mature nerve growth factor (mNGF), might activate apoptotic signaling by binding to p75 neurotrophin receptor (p75NTR) in neurons. Therefore, we studied the mechanism of the proNGF/p75NTR pathway in HD-induced neuronal apoptosis. Sprague-Dawley (SD) rats were injected with 400 mg/kg HD once a day for 5 weeks, and VSC4.1 cells were treated with 10, 20, and 40 mM HD in vitro. Results showed that HD effectively induced neuronal apoptosis. Moreover, it up-regulated proNGF and p75NTR levels, activated c-Jun N-terminal kinase (JNK) and c-Jun, and disrupted the balance between B-cell lymphoma-2 (Bcl-2) and Bcl-2-associated X protein (Bax). Our findings revealed that the proNGF/p75NTR signaling pathway was involved in HD-induced neuronal apoptosis; it can serve as a theoretical basis for further exploration of the neurotoxic mechanisms of HD.
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Affiliation(s)
- Mengxin Luo
- Department of Occupational and Environmental Health, school of public health, Dalian Medical University, Dalian 116044, China
| | - Xiaoxia Shi
- Department of Occupational and Environmental Health, school of public health, Dalian Medical University, Dalian 116044, China
| | - Qi Guo
- Department of Environment Hygiene Division, Dalian Center for Disease Control and Prevention, Dalian 116021, China
| | - Shuangyue Li
- Department of Occupational and Environmental Health, school of public health, Dalian Medical University, Dalian 116044, China
| | - Qing Zhang
- Department of Integrative Laboratory, Affiliated Zhongshan Hospital of Dalian University, Dalian 116001, China
| | - Xiuyan Sun
- Department of Integrative Laboratory, Affiliated Zhongshan Hospital of Dalian University, Dalian 116001, China
| | - Fengyuan Piao
- Department of Integrative Laboratory, Affiliated Zhongshan Hospital of Dalian University, Dalian 116001, China
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15
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Sugimoto J, Satoyoshi H, Takahata K, Muraoka S. Fabry disease-associated globotriaosylceramide induces mechanical allodynia via activation of signaling through proNGF-p75 NTR but not mature NGF-TrkA. Eur J Pharmacol 2021; 895:173882. [PMID: 33482180 DOI: 10.1016/j.ejphar.2021.173882] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 01/12/2021] [Accepted: 01/14/2021] [Indexed: 01/14/2023]
Abstract
Fabry disease (FD) is an X-linked metabolic storage disorder arising from the deficiency of lysosomal α-galactosidase A, which leads to the gradual accumulation of glycosphingolipids, mainly globotriaosylceramide (Gb3), throughout the body. Pain in the extremities is an early symptom of FD; however, the underlying pathophysiological mechanisms remain unknown. α-Galactosidase A knockout animals exhibit nociceptive behaviors, with enhanced expression levels of several ion channels. These characteristics are observed in animals treated with nerve growth factor (NGF). Here, we aimed to elucidate the potential of NGF signaling as a cause of FD-associated pain, using intraplantar Gb3-treated mice displaying mechanical allodynia. Treatment with a neutralizing antibody against a precursor of NGF (proNGF) or its receptor, p75 neurotrophin receptor (p75NTR), resulted in the recovery from Gb3-induced pain. Conversely, anti-NGF and anti-tropomyosin receptor kinase A antibodies failed to exert analgesic effects. Gb3 injection had no effects on the expression levels of proNGF and p75NTR in the plantar skin and dorsal root ganglia, suggesting that Gb3 activates the pain pathway, possibly mediated through functional up-regulation of proNGF-p75NTR signaling. Furthermore, by pharmacological approaches using a protein kinase A (PKA) inhibitor and a cholesterol-removing agent, we found that p75NTR-phosphorylating PKA and lipid rafts for phosphorylated p75NTR translocation were required for Gb3-induced pain. These results suggest that acute exposure to Gb3 induces mechanical allodynia via activation of the proNGF-p75NTR pathway, which involves lipid rafts and PKA. Our findings provide new pathological insights into FD-associated pain, and suggest the need to develop therapeutic interventions targeting proNGF-p75NTR signaling.
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Affiliation(s)
- Junya Sugimoto
- Department of Scientific Research, Fujimoto Pharmaceutical Corporation, 1-3-40 Nishiotsuka, Matsubara, Osaka, 580-8503, Japan
| | - Hiroshi Satoyoshi
- Department of Scientific Research, Fujimoto Pharmaceutical Corporation, 1-3-40 Nishiotsuka, Matsubara, Osaka, 580-8503, Japan
| | - Kazue Takahata
- Department of Scientific Research, Fujimoto Pharmaceutical Corporation, 1-3-40 Nishiotsuka, Matsubara, Osaka, 580-8503, Japan.
| | - Shizuko Muraoka
- Department of Scientific Research, Fujimoto Pharmaceutical Corporation, 1-3-40 Nishiotsuka, Matsubara, Osaka, 580-8503, Japan
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16
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Forouzanfar F, Shojapour M, Aghili ZS, Asgharzade S. Growth Factors as Tools in Photoreceptor Cell Regeneration and Vision Recovery. Curr Drug Targets 2021; 21:573-581. [PMID: 31755378 DOI: 10.2174/1389450120666191121103831] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 10/04/2019] [Accepted: 10/18/2019] [Indexed: 02/08/2023]
Abstract
Photoreceptor loss is a major cause of blindness around the world. Stem cell therapy offers a new strategy in retina degenerative disease. Retinal progenitors can be derived from embryonic stem cells (ESC) in vitro, but cannot be processed to a mature state. In addition, the adult recipient retina presents a very different environment than the photoreceptor precursor donor. It seems that modulation of the recipient environment by ectopic development regulated growth factors for transplanted cells could generate efficient putative photoreceptors. The purpose of this review article was to investigate the signaling pathway of growth factors including: insulin-like growth factors (IGFs), fibroblast growth factors (FGF), Nerve growth factor (NGF), Brain-derived neurotrophic factor (BDNF), Taurin and Retinoic acid (RA) involved in the differentiation of neuroretina cell, like; photoreceptor and retinal progenitor cells. Given the results available in the related literature, the differentiation efficacy of ESCs toward the photoreceptor and retinal neurons and the important role of growth factors in activating signaling pathways such as Akt, Ras/Raf1/ and ERKs also inhibit the ASK1/JNK apoptosis pathway. Manipulating differentiated culture, growth factors can influence photoreceptor transplantation efficiency in retinal degenerative disease.
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Affiliation(s)
- Fatemeh Forouzanfar
- Neuroscience Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.,Department of Neuroscience, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Mana Shojapour
- Molecular and Medicine Research Center, Arak University of Medical Sciences, Arak, Iran
| | - Zahra Sadat Aghili
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | - Samira Asgharzade
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences, Shahrekord, Iran
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17
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Mossa AH, Abdaem J, Cammisotto P, Campeau L. Deleterious impact of nerve growth factor precursor (proNGF) on bladder urothelial and smooth muscle cells. Cell Signal 2021; 81:109936. [PMID: 33529756 DOI: 10.1016/j.cellsig.2021.109936] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 01/28/2021] [Accepted: 01/28/2021] [Indexed: 12/21/2022]
Abstract
The nerve growth factor precursor (proNGF) activates p75NTR receptor and promotes cell death in different tissues, yet this pathophysiological effect is not fully described in the bladder. The aim of this study was to identify the biological effect of proNGF/p75NTR activation on urothelial and smooth muscle (SM) cells of rodents' bladder. Cell viability was assessed by MTT assay which showed a significant reduction in urothelial viability after 24 h of incubation with proNGF in culture medium [5 or 10 nM], an effect not seen in SM cells. Western blot analysis on cellular protein extracts showed increased expression of the transmembrane TNF-α and activation of RhoA in urothelial cells exposed to proNGF with no evidence of a nuclear translocation of NF-κB assessed by western blotting on nuclear extracts and immunofluorescence. The activation of p75NTR-death domain related pathways in urothelial cells such as TNF-α or RhoA had a downstream effect on NO release and the junctional protein occludin, as estimated respectively by colorimetric and western blotting. On the other hand, proNGF did not induce TNF-α or RhoA expression in SM cells, but induced a significant NF-κB nuclear translocation. ProNGF had a different impact on SM as evidenced by a significant dose- and time-dependent increase in SM proliferation and migration examined by MTT test and cell migration assay. Together, our results indicate that activation of proNGF/p75NTR axis induces degenerative changes to the urothelial layer impacting its barrier and signaling integrity, while promoting adaptive proliferative changes in detrusor SM cells that can interfere with the contractile phenotype essential for proper bladder function.
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Affiliation(s)
- Abubakr H Mossa
- Lady Davis Institute, McGill University, 3755, Chemin de la cote-Ste-Catherine, Montreal, QC H3T 1E2, Canada
| | - Jacob Abdaem
- School of Medicine, McGill University, 3605 Rue de la Montagne, Montréal, QC H3G 2M1, Canada
| | - Philippe Cammisotto
- Lady Davis Institute, McGill University, 3755, Chemin de la cote-Ste-Catherine, Montreal, QC H3T 1E2, Canada
| | - Lysanne Campeau
- Lady Davis Institute, McGill University, 3755, Chemin de la cote-Ste-Catherine, Montreal, QC H3T 1E2, Canada; Urology Department, Jewish General Hospital, 3755, Chemin de la cote-Ste-Catherine, Montreal, QC H3T 1E2, Canada.
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18
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The innate immune system in diabetic retinopathy. Prog Retin Eye Res 2021; 84:100940. [PMID: 33429059 DOI: 10.1016/j.preteyeres.2021.100940] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 12/24/2020] [Accepted: 01/03/2021] [Indexed: 12/20/2022]
Abstract
The prevalence of diabetes has been rising steadily in the past half-century, along with the burden of its associated complications, including diabetic retinopathy (DR). DR is currently the most common cause of vision loss in working-age adults in the United States. Historically, DR has been diagnosed and classified clinically based on what is visible by fundoscopy; that is vasculature alterations. However, recent technological advances have confirmed pathology of the neuroretina prior to any detectable vascular changes. These, coupled with molecular studies, and the positive impact of anti-inflammatory therapeutics in DR patients have highlighted the central involvement of the innate immune system. Reminiscent of the systemic impact of diabetes, immune dysregulation has become increasingly identified as a key element of the pathophysiology of DR by interfering with normal homeostatic systems. This review uses the growing body of literature across various model systems to demonstrate the clear involvement of all three pillars of the immune system: immune-competent cells, mediators, and the complement system. It also demonstrates how the relative contribution of each of these requires more extensive analysis, including in human tissues over the continuum of disease progression. Finally, although this review demonstrates how the complex interactions of the immune system pose many more questions than answers, the intimately connected nature of the three pillars of the immune system may also point to possible new targets to reverse or even halt reverse retinopathy.
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19
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Chung DY, Song KM, Choi MJ, Limanjaya A, Ghatak K, Ock J, Yin GN, Hong CH, Hong SS, Suh JK, Ryu JK. Neutralizing antibody to proNGF rescues erectile function by regulating the expression of neurotrophic and angiogenic factors in a mouse model of cavernous nerve injury. Andrology 2021; 9:329-341. [PMID: 32696589 DOI: 10.1111/andr.12873] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 07/07/2020] [Accepted: 07/16/2020] [Indexed: 12/14/2022]
Abstract
BACKGROUND Radical prostatectomy induces some degree of cavernous nerve injury (CNI) and causes denervation-induced pathologic changes in cavernous vasculature, regardless of the advances in surgical techniques and robotic procedures. The precursor for nerve growth factor (proNGF) is known to be involved in neuronal cell apoptosis and microvascular dysfunction through its receptor p75NTR . OBJECTIVES To determine the expression of proNGF/p75NTR and the efficacy of proNGF neutralizing antibody (anti-proNGF-Ab) in a mouse model of ED induced by CNI. MATERIALS AND METHODS Age-matched 12-week-old C57BL/6 mice were distributed into three groups: sham group and bilateral CNI group treated with intracavernous injections of PBS (20 μL) or of anti-proNGF-Ab (20 µg in 20 μL of PBS) on days -3 and 0. Two weeks after treatment, erectile function was measured by electrical stimulation of cavernous nerve. Penis tissues from a separate group of animals were harvested for further analysis. We also determined the efficacy of anti-proNGF-Ab on neural preservation in major pelvic ganglion (MPG) ex vivo. RESULTS We observed increased penile expression of proNGF and p75NTR after CNI. Intracavernous administration of anti-proNGF-Ab increased nNOS and neurofilament expression probably by enhancing the production of neurotrophic factors, such as neurotrophin-3, NGF, and brain-derived neurotrophic factor. Anti-proNGF-Ab preserved the integrity of cavernous sinusoids, such as pericytes, endothelial cells, and endothelial cell-to-cell junctions, possibly by controlling angiogenic factors (angiopoietin-1, angiopoietin-2, and vascular endothelial growth factor) and induced endogenous eNOS phosphorylation in CNI mice. And finally, treatment with anti-proNGF-Ab rescued erectile function in CNI mice. Anti-proNGF-Ab also enhanced neurite sprouting from MPG exposed to lipopolysaccharide. DISCUSSION AND CONCLUSION The preservation of damaged cavernous neurovasculature through inhibition of the proNGF/p75NTR pathway may be a novel strategy to treat radical prostatectomy-induced erectile dysfunction.
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Affiliation(s)
- Doo Yong Chung
- National Research Center for Sexual Medicine and Department of Urology, Inha University College of Medicine, Incheon, Korea
- Department of Urology, Urological Science Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Kang-Moon Song
- National Research Center for Sexual Medicine and Department of Urology, Inha University College of Medicine, Incheon, Korea
| | - Min-Ji Choi
- National Research Center for Sexual Medicine and Department of Urology, Inha University College of Medicine, Incheon, Korea
| | - Anita Limanjaya
- National Research Center for Sexual Medicine and Department of Urology, Inha University College of Medicine, Incheon, Korea
| | - Kalyan Ghatak
- National Research Center for Sexual Medicine and Department of Urology, Inha University College of Medicine, Incheon, Korea
| | - Jiyeon Ock
- National Research Center for Sexual Medicine and Department of Urology, Inha University College of Medicine, Incheon, Korea
| | - Guo Nan Yin
- National Research Center for Sexual Medicine and Department of Urology, Inha University College of Medicine, Incheon, Korea
| | - Chang Hee Hong
- Department of Urology, Urological Science Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Soon-Sun Hong
- Department of Drug Development, Inha University School of Medicine, Incheon, Korea
| | - Jun-Kyu Suh
- National Research Center for Sexual Medicine and Department of Urology, Inha University College of Medicine, Incheon, Korea
| | - Ji-Kan Ryu
- National Research Center for Sexual Medicine and Department of Urology, Inha University College of Medicine, Incheon, Korea
- Department of Urology, Inha University Hospital, Incheon, Korea
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20
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Mossa AH, Galan A, Cammisotto PG, Velasquez Flores M, Shamout S, Barcelona P, Saragovi HU, Campeau L. Antagonism of proNGF or its receptor p75 NTR reverses remodelling and improves bladder function in a mouse model of diabetic voiding dysfunction. Diabetologia 2020; 63:1932-1946. [PMID: 32699962 DOI: 10.1007/s00125-020-05222-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 05/18/2020] [Indexed: 10/23/2022]
Abstract
AIMS/HYPOTHESIS Although 80% of diabetic patients will suffer from voiding difficulties and urinary symptoms, defined as diabetic voiding dysfunction (DVD), therapeutic targets and treatment options are limited. We hypothesise that the blockade of the pro-nerve growth factor (NGF)/p75 neurotrophin receptor (p75NTR) axis by an anti-proNGF monoclonal antibody or by a small molecule p75NTR antagonist (THX-B) can restore bladder remodelling (represented by bladder weight) in an animal model of DVD. Secondary outcomes of the study include improvements in bladder compliance, contractility and morphology, as well as in voiding behaviour, proNGF/NGF balance and TNF-α expression. METHODS In a streptozotocin-induced mouse model of diabetes, diabetic mice received either a blocking anti-proNGF monoclonal antibody or a p75NTR antagonist small molecule as weekly systemic injections for 4 weeks. Animals were tested at baseline (at 2 weeks of diabetes induction), and after 2 and 4 weeks of treatment. Outcomes measured were voiding function with voiding spot assays and cystometry. Bladders were assessed by histological, contractility and protein expression assays. RESULTS Diabetic mice showed features of DVD as early as 2 weeks after diabetes diagnosis (baseline) presented by hypertrophy, reduced contractility and abnormal cystometric parameters. Following treatment initiation, a twofold increase (p < 0.05) in untreated diabetic mouse bladder weight and thickness compared with non-diabetic controls was observed, and this change was reversed by p75NTR antagonism (37% reduction in bladder weight compared with untreated diabetic mice [95% CI 14%, 60%]) after 4 weeks of treatment. However, blocking proNGF did not help to reverse bladder hypertrophy. While diabetic mice had significantly worse cystometric parameters and contractile responses than non-diabetic controls, proNGF antagonism normalised bladder compliance (0.007 [Q1-Q3; 0.006-0.009] vs 0.015 [Q1-Q3; 0.014-0.029] ml/cmH2O in untreated diabetic mice, representing 62% reduction [95% CI 8%, 110%], p < 0.05) and contractility to KCl, carbachol and electrical field stimulation (p < 0.05 compared with the diabetic group) after 2 weeks of treatment. These effects were not observed after 4 weeks of treatment with proNGF antagonist. p75NTR antagonism did not show important improvements in cystometric parameters after 2 weeks of treatment. Slightly improved bladder compliance (0.01 [Q1-Q3; 0.009-0.012] vs 0.013 [Q1-Q3; 0.011-0.016] ml/cmH2O for untreated diabetic mice) was seen in the p75NTR antagonist-treated group after 4 weeks of treatment with significantly stabilised contractile responses to KCl, carbachol and electric field stimulation (p < 0.05 for each) compared with diabetic mice. Bladder dysfunction observed in diabetic mice was associated with a significant increase in bladder proNGF/NGF ratio (3.1 [±1.2] vs 0.26 [±0.04] ng/pg in control group, p < 0.05 at week 2 of treatment) and TNF-α (p < 0.05). The proNGF/NGF ratio was partially reduced (about 60% reduction) with both treatments (1.03 [±0.6] ng/pg for proNGF antibody-treated group and 1.4 [±0.76] ng/pg for p75NTR blocker-treated group after 2 weeks of treatment), concomitant with a significant decrease in the bladder levels of TNF-α (p < 0.05), despite persistent hyperglycaemia. CONCLUSIONS/INTERPRETATION Our findings indicate that blockade of proNGF and the p75NTR receptor in diabetes can impede the development and progression of DVD. The reported improvements in morphological and functional features in our DVD model validates the proNGF/p75NTR axis as a potential therapeutic target in this pathology. Graphical abstract.
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Affiliation(s)
- Abubakr H Mossa
- Lady Davis Research Institute, McGill University, 3755 Chemin de la Cote-Ste-Catherine, Montreal, QC, H3T 1E2, Canada
| | - Alba Galan
- Lady Davis Research Institute, McGill University, 3755 Chemin de la Cote-Ste-Catherine, Montreal, QC, H3T 1E2, Canada
| | - Philippe G Cammisotto
- Lady Davis Research Institute, McGill University, 3755 Chemin de la Cote-Ste-Catherine, Montreal, QC, H3T 1E2, Canada
| | - Monica Velasquez Flores
- Lady Davis Research Institute, McGill University, 3755 Chemin de la Cote-Ste-Catherine, Montreal, QC, H3T 1E2, Canada
| | - Samer Shamout
- Lady Davis Research Institute, McGill University, 3755 Chemin de la Cote-Ste-Catherine, Montreal, QC, H3T 1E2, Canada
- Division of Urology, Department, of Surgery, McGill University, Montreal, QC, Canada
| | - Pablo Barcelona
- Lady Davis Research Institute, McGill University, 3755 Chemin de la Cote-Ste-Catherine, Montreal, QC, H3T 1E2, Canada
| | - H Uri Saragovi
- Lady Davis Research Institute, McGill University, 3755 Chemin de la Cote-Ste-Catherine, Montreal, QC, H3T 1E2, Canada
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, Canada
- Center for Experimental Therapeutics, Jewish General Hospital, Montreal, QC, Canada
- Department of Ophthalmology and Vision Sciences, McGill University, Montreal, QC, Canada
| | - Lysanne Campeau
- Lady Davis Research Institute, McGill University, 3755 Chemin de la Cote-Ste-Catherine, Montreal, QC, H3T 1E2, Canada.
- Division of Urology, Department, of Surgery, McGill University, Montreal, QC, Canada.
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Ding XW, Li R, Geetha T, Tao YX, Babu JR. Nerve growth factor in metabolic complications and Alzheimer's disease: Physiology and therapeutic potential. Biochim Biophys Acta Mol Basis Dis 2020; 1866:165858. [PMID: 32531260 DOI: 10.1016/j.bbadis.2020.165858] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 05/11/2020] [Accepted: 06/02/2020] [Indexed: 02/07/2023]
Abstract
As the population ages, obesity and metabolic complications as well as neurological disorders are becoming more prevalent, with huge economic burdens on both societies and families. New therapeutics are urgently needed. Nerve growth factor (NGF), first discovered in 1950s, is a neurotrophic factor involved in regulating cell proliferation, growth, survival, and apoptosis in both central and peripheral nervous systems. NGF and its precursor, proNGF, bind to TrkA and p75 receptors and initiate protein phosphorylation cascades, resulting in changes of cellular functions, and are associated with obesity, diabetes and its complications, and Alzheimer's disease. In this article, we summarize changes in NGF levels in metabolic and neuronal disorders, the signal transduction initiated by NGF and proNGF, the physiological and pathophysiological relevance, and therapeutic potential in treating chronic metabolic diseases and cognitive decline.
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Affiliation(s)
- Xiao-Wen Ding
- Department of Nutrition, Dietetics, and Hospitality Management, Auburn University, Auburn, AL 36849, USA
| | - Rongzi Li
- Department of Nutrition, Dietetics, and Hospitality Management, Auburn University, Auburn, AL 36849, USA
| | - Thangiah Geetha
- Department of Nutrition, Dietetics, and Hospitality Management, Auburn University, Auburn, AL 36849, USA; Boshell Metabolic Diseases and Diabetes Program, Auburn University, Auburn, AL 36849, USA
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA.
| | - Jeganathan Ramesh Babu
- Department of Nutrition, Dietetics, and Hospitality Management, Auburn University, Auburn, AL 36849, USA; Boshell Metabolic Diseases and Diabetes Program, Auburn University, Auburn, AL 36849, USA.
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Arutjunyan AV, Milyutina YP, Shcherbitskaia AD, Kerkeshko GO, Zalozniaia IV, Mikhel AV. Neurotrophins of the Fetal Brain and Placenta in Prenatal Hyperhomocysteinemia. BIOCHEMISTRY (MOSCOW) 2020; 85:213-223. [PMID: 32093597 DOI: 10.1134/s000629792002008x] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Prenatal hyperhomocysteinemia (PHHC) in pregnant rats was induced by chronic L-methionine loading, resulting in a significant increase in the L-homocysteine content both in the mothers' blood and blood and brain of fetuses. Significant decrease in the weight of the placenta, fetus, and fetal brain was detected by the morphometric studies on day 20 of pregnancy. PHHC also activated maternal immune system due to the increase in the content of proinflammatory interleukin-1β in the rat blood and fetal part of the placenta. PHHC elevated the levels of the brain-derived neurotrophic factor (BDNF, 29 kDa) and nerve growth factor (NGF, 31 kDa) precursors in the placenta and the content of the BDNF isoform (29 kDa) in the fetal brain. The content of neuregulin 1 (NRG1) decreased in the placenta and increased in the fetal brain on day 20 of embryonic development. An increase in the caspase-3 activity was detected in the brains of fetuses subjected to PHHC. It was suggested that changes in the processing of neurotrophins induced by PPHC, oxidative stress, and inflammatory processes initiated by it, as well as apoptosis, play an important role in the development of brain disorders in the offspring.
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Affiliation(s)
- A V Arutjunyan
- Ott Institute of Obstetrics, Gynecology, and Reproductology, St. Petersburg, 199034, Russia.
| | - Yu P Milyutina
- Ott Institute of Obstetrics, Gynecology, and Reproductology, St. Petersburg, 199034, Russia
| | - A D Shcherbitskaia
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, 194223, Russia
| | - G O Kerkeshko
- Ott Institute of Obstetrics, Gynecology, and Reproductology, St. Petersburg, 199034, Russia
| | - I V Zalozniaia
- Ott Institute of Obstetrics, Gynecology, and Reproductology, St. Petersburg, 199034, Russia
| | - A V Mikhel
- Ott Institute of Obstetrics, Gynecology, and Reproductology, St. Petersburg, 199034, Russia
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Elshaer SL, Alwhaibi A, Mohamed R, Lemtalsi T, Coucha M, Longo FM, El-Remessy AB. Modulation of the p75 neurotrophin receptor using LM11A-31 prevents diabetes-induced retinal vascular permeability in mice via inhibition of inflammation and the RhoA kinase pathway. Diabetologia 2019; 62:1488-1500. [PMID: 31073629 PMCID: PMC8808141 DOI: 10.1007/s00125-019-4885-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 03/28/2019] [Indexed: 02/07/2023]
Abstract
AIMS/HYPOTHESIS Breakdown of the inner blood-retinal barrier (BRB) is an early event in the pathogenesis of diabetic macular oedema, that eventually leads to vision loss. We have previously shown that diabetes causes an imbalance of nerve growth factor (NGF) isoforms resulting in accumulation of its precursor proNGF and upregulation of the p75 neurotrophin receptor (p75NTR), with consequent increases in the activation of Ras homologue gene family, member A (RhoA). We also showed that genetic deletion of p75NTR in diabetes preserved the BRB and prevented inflammatory mediators in retinas. This study aims to examine the therapeutic potential of LM11A-31, a small-molecule p75NTR modulator and proNGF antagonist, in preventing diabetes-induced BRB breakdown. The study also examined the role of p75NTR/RhoA downstream signalling in mediating cell permeability. METHODS Male C57BL/6 J mice were rendered diabetic using streptozotocin injection. After 2 weeks of diabetes, mice received oral gavage of LM11A-31 (50 mg kg-1 day-1) or saline (NaCl 154 mmol/l) for an additional 4 weeks. BRB breakdown was assessed by extravasation of BSA-AlexaFluor-488. Direct effects of proNGF were examined in human retinal endothelial (HRE) cells in the presence or absence of LM11A-31 or the Rho kinase inhibitor Y-27632. RESULTS Diabetes triggered BRB breakdown and caused significant increases in circulatory and retinal TNF-α and IL-1β levels. These effects coincided with significant decreases in retinal NGF and increases in vascular endothelial growth factor and proNGF expression, as well as activation of RhoA. Interventional modulation of p75NTR activity through treatment of mouse models of diabetes with LM11A-31 significantly mitigated proNGF accumulation and preserved BRB integrity. In HRE cells, treatment with mutant proNGF (10 ng/ml) triggered increased cell permeability with marked reduction of expression of tight junction proteins, zona occludens-1 (ZO-1) and claudin-5, compared with control, independent of inflammatory mediators or cell death. Modulating p75NTR significantly inhibited proNGF-mediated RhoA activation, occludin phosphorylation (at serine 490) and cell permeability. ProNGF induced redistribution of ZO-1 in the cell wall and formation of F-actin stress fibres; these effects were mitigated by LM11A-31. CONCLUSIONS/INTERPRETATION Targeting p75NTR signalling using LM11A-31, an orally bioavailable receptor modulator, may offer an effective, safe and non-invasive therapeutic strategy for treating macular oedema, a major cause of blindness in diabetes.
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Affiliation(s)
- Sally L Elshaer
- Augusta Biomedical Research Corporation, Augusta, GA, USA
- Charlie Norwood VA Medical Center, Augusta, GA, USA
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
| | - Abdulrahman Alwhaibi
- Augusta Biomedical Research Corporation, Augusta, GA, USA
- Charlie Norwood VA Medical Center, Augusta, GA, USA
| | - Riyaz Mohamed
- Augusta Biomedical Research Corporation, Augusta, GA, USA
- Charlie Norwood VA Medical Center, Augusta, GA, USA
| | - Tahira Lemtalsi
- Augusta Biomedical Research Corporation, Augusta, GA, USA
- Charlie Norwood VA Medical Center, Augusta, GA, USA
| | - Maha Coucha
- Augusta Biomedical Research Corporation, Augusta, GA, USA
- Charlie Norwood VA Medical Center, Augusta, GA, USA
| | - Frank M Longo
- Department of Neurology and Neurological Sciences, Stanford University, Palo Alto, CA, USA
| | - Azza B El-Remessy
- Augusta Biomedical Research Corporation, Augusta, GA, USA.
- Charlie Norwood VA Medical Center, Augusta, GA, USA.
- Department of the Pharmacy, Doctors Hospital of Augusta, Augusta, GA, 30909, USA.
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Bahr HI, Abdelghany AA, Galhom RA, Barakat BM, Arafa ESA, Fawzy MS. Duloxetine protects against experimental diabetic retinopathy in mice through retinal GFAP downregulation and modulation of neurotrophic factors. Exp Eye Res 2019; 186:107742. [PMID: 31344388 DOI: 10.1016/j.exer.2019.107742] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 07/19/2019] [Accepted: 07/19/2019] [Indexed: 12/23/2022]
Abstract
Diabetic retinopathy (DR) is recognized as one of the leading causes of blindness worldwide. Searching and validation for a novel therapeutic strategy to prevent its progress are promising. This work aimed to assess the retinal protective effects of duloxetine (DLX) in Alloxan-induced diabetic mice model. Animals were equally and randomly divided to four groups (eight mice per group); group 1: is the control group, 2: diabetic group, 3&4: diabetic and after 9 weeks received DLX for 4 weeks (15 mg/kg and 30 mg/kg), respectively. Quantitative real-time PCR (qPCR) analysis revealed nerve growth factor (NGF), inducible nitric oxide synthase (iNOS) and transforming growth factor beta (TGF-β) genes upregulation in the diabetic group compared to controls. Also, increased retinal malondialdehyde (MDA) and the decline of reduced glutathione (GSH) levels were observed. The morphometric analysis of diabetic retina revealed a significant reduction in total retinal thickness compared to control. Diabetic retinal immunostaining and Western blot analyses displayed glial fibrillary acidic protein (GFAP) and vascular endothelial cell growth factor (VEGF) proteins expression upregulation as well as glucose transporter-1 (GLUT-1) downregulation comparing to controls. However, DLX-treated groups showed downregulated NGF, iNOS, and TGF-β that was more obviously seen in the DLX-30 mg/kg group than DLX-15 mg/kg group. Furthermore, these groups showed amelioration of the oxidative markers; MDA and GSH, retaining the total retinal thickness nearly to control, GFAP and VEGF downregulation, and GLUT-1 upregulation compared to diabetic group. Taken together, it could be summarized that duloxetine can attenuate DR via the anti-inflammatory and the anti-oxidative properties as well as modulating the angiogenic and the neurotrophic factors expressions. This could hopefully pave the road to be included in the novel list of the therapeutic regimen for DR after validation in the clinic.
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Affiliation(s)
- Hoda I Bahr
- Department of Biochemistry, Faculty of Veterinary Medicine, Suez Canal University, Ismailia, 41522, Egypt.
| | - Ahmed A Abdelghany
- Department of Ophthalmology, Faculty of Medicine, Suez Canal University, Ismailia, 41522, Egypt.
| | - Rania A Galhom
- Department of Human Anatomy and Embryology, Faculty of Medicine, Suez Canal University, Ismailia, 41522, Egypt.
| | - Bassant M Barakat
- Department of Pharmacology and Toxicology, Faculty of Pharmacy (Girls), Al-Azhar University, Cairo, Egypt; Department of Clinical Pharmacy, College of Clinical Pharmacy, Al-Baha University, Al-Baha, Saudi Arabia.
| | - El-Shaimaa A Arafa
- Department of Clinical Sciences, College of Pharmacy and Health Sciences, Ajman University, Ajman, 346, United Arab Emirates; Department of Pharmacology and Toxicology, Faculty of Pharmacy, Beni-Suef University, Beni-Suef, 62514, Egypt.
| | - Manal S Fawzy
- Department of Biochemistry, Faculty of Medicine, Northern Border University, Arar, Saudi Arabia; Department of Medical Biochemistry and Molecular Biology, Faculty of Medicine, Suez Canal University, Ismailia, 41522, Egypt.
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Saragovi HU, Galan A, Levin LA. Neuroprotection: Pro-survival and Anti-neurotoxic Mechanisms as Therapeutic Strategies in Neurodegeneration. Front Cell Neurosci 2019; 13:231. [PMID: 31244606 PMCID: PMC6563757 DOI: 10.3389/fncel.2019.00231] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 05/08/2019] [Indexed: 12/14/2022] Open
Abstract
Neurotrophins (NTs) are a subset of the neurotrophic factor family. These growth factors were originally named based on the nerve growth functional assays used to identify them. NTs act as paracrine or autocrine factors for cells expressing NT receptors. The receptors and their function have been studied primarily in cells of the nervous system, but are also present in the cardiovascular, endocrine, and immune systems, as well as in many neoplastic cells. The signals activated by NTs can be varied, depending on cellular stage and context, healthy or disease states, and depending on whether the specific NTs and their receptors are expressed in the relevant cells. In the healthy central and peripheral adult nervous systems, NTs drive neuronal survival, phenotype, synaptic maintenance, and function. Deficiencies of the NT/NT receptor axis are causally associated with disease onset or disease progression. Paradoxically, NTs can also drive synaptic loss and neuronal death. In the embryonic stage this activity is essential for proper developmental pruning of the nervous system, but in the adult it can be associated with neurodegenerative disease. Given their key role in neuronal survival and death, NTs and NT receptors have long been considered therapeutic targets to achieve neuroprotection. The first neuroprotective approaches consisted of enhancing neuronal survival signals using NTs. Later strategies selectively targeted receptors to induce survival signals specifically, while avoiding activation of death signals. Recently, the concept of selectively targeting receptors to reduce neuronal death signals has emerged. Here, we review the rationale of each neuroprotective strategy with respect to the complex cell biology and pharmacology of each target receptor.
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Affiliation(s)
- Horacio Uri Saragovi
- Lady Davis Institute, Montreal, QC, Canada.,Jewish General Hospital, Montreal, QC, Canada.,Department of Ophthalmology and Visual Sciences, McGill University, Montreal, QC, Canada
| | - Alba Galan
- Lady Davis Institute, Montreal, QC, Canada.,Jewish General Hospital, Montreal, QC, Canada
| | - Leonard A Levin
- Department of Ophthalmology and Visual Sciences, McGill University, Montreal, QC, Canada.,McGill University Health Centre, Montreal, QC, Canada.,Montreal Neurological Institute, Mcgill University, Montreal, QC, Canada
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Nguyen NM, Song KM, Choi MJ, Ghatak K, Kwon MH, Ock J, Yin GN, Ryu JK, Suh JK. Inhibition of proNGF and p75NTR Pathway Restores Erectile Function Through Dual Angiogenic and Neurotrophic Effects in the Diabetic Mouse. J Sex Med 2019; 16:351-364. [DOI: 10.1016/j.jsxm.2019.01.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 12/24/2018] [Accepted: 01/16/2019] [Indexed: 01/24/2023]
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Fisetin rescues retinal functions by suppressing inflammatory response in a DBA/2J mouse model of glaucoma. Doc Ophthalmol 2019; 138:125-135. [PMID: 30756213 DOI: 10.1007/s10633-019-09676-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 01/26/2019] [Indexed: 12/13/2022]
Abstract
PURPOSE Glaucoma is a common chronic neurodegenerative disease, which could lead to visual loss. In this study, we aimed to investigate whether fisetin, a natural flavone with anti-inflammatory and antioxidant properties, is able to alleviate glaucoma. METHODS We employed a DBA/2J mouse model which was treated with or without fisetin. Pattern electroretinogram (P-ERG), visual evoked potentials (VEPs) and intraocular pressure (IOP) were evaluated. Quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA) were used to measure the expression levels of TNF-α, IL-1β and IL-6. Western blotting was performed to assess the activation of nuclear factor kappa-B (NF-κB). RESULTS We found that DBA/2J mice treated with fisetin (10-30 mg/kg) showed improved P-ERG and VEP amplitudes and reduced IOP compared to untreated DBA/2J mice. In addition, there were more survived retinal ganglion cells (RGCs) and less activated microglia in fisetin-treated DBA/2J mice than those in untreated mice. Furthermore, secreted protein levels and mRNA levels of TNF-α, IL-1β and IL-6 were significantly repressed by fisetin. The phosphorylated p65 level in the nucleus was dramatically reduced in fisetin-treated mice compared to it in untreated mice. Our results demonstrate that fisetin may exert its function through regulating cytokine productions and inhibiting NF-κB activation in the retina. CONCLUSION In conclusion, fisetin is able to promote the visual functions of DBA/2J mice by inhibiting NF-κB activation.
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Wilson AM, Mazzaferri J, Bergeron É, Patskovsky S, Marcoux-Valiquette P, Costantino S, Sapieha P, Meunier M. In Vivo Laser-Mediated Retinal Ganglion Cell Optoporation Using K V1.1 Conjugated Gold Nanoparticles. NANO LETTERS 2018; 18:6981-6988. [PMID: 30285455 DOI: 10.1021/acs.nanolett.8b02896] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Vision loss caused by retinal diseases affects hundreds of millions of individuals worldwide. The retina is a delicate central nervous system tissue stratified into layers of cells with distinct roles. Currently, there is a void in treatments that selectively target diseased retinal cells, and current therapeutic paradigms present complications associated with off-target effects. Herein, as a proof of concept, we introduce an in vivo method using a femtosecond laser to locally optoporate retinal ganglion cells (RGCs) targeted with functionalized gold nanoparticles (AuNPs). We provide evidence that AuNPs functionalized with an antibody toward the cell-surface voltage-gated K+ channel subunit KV1.1 can selectively deliver fluorescently tagged siRNAs or fluorescein isothiocyanate-dextran dye into retinal cells when irradiated with an 800 nm 100 fs laser. Importantly, neither AuNP administration nor irradiation resulted in RGC death. This system provides a novel, non-viral-based approach that has the potential to selectively target retinal cells in diseased regions while sparing healthy areas and may be harnessed in future cell-specific therapies for retinal degenerative diseases.
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Affiliation(s)
- Ariel M Wilson
- Department of Engineering Physics , Polytechnique Montréal , Montreal , Quebec , Canada , H3C 3A7
| | | | - Éric Bergeron
- Department of Engineering Physics , Polytechnique Montréal , Montreal , Quebec , Canada , H3C 3A7
| | - Sergiy Patskovsky
- Department of Engineering Physics , Polytechnique Montréal , Montreal , Quebec , Canada , H3C 3A7
| | - Paule Marcoux-Valiquette
- Department of Engineering Physics , Polytechnique Montréal , Montreal , Quebec , Canada , H3C 3A7
| | | | | | - Michel Meunier
- Department of Engineering Physics , Polytechnique Montréal , Montreal , Quebec , Canada , H3C 3A7
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A central role for glial CCR5 in directing the neuropathological interactions of HIV-1 Tat and opiates. J Neuroinflammation 2018; 15:285. [PMID: 30305110 PMCID: PMC6180355 DOI: 10.1186/s12974-018-1320-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 09/19/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The collective cognitive and motor deficits known as HIV-associated neurocognitive disorders (HAND) remain high even among HIV+ individuals whose antiretroviral therapy is optimized. HAND is worsened in the context of opiate abuse. The mechanism of exacerbation remains unclear but likely involves chronic immune activation of glial cells resulting from persistent, low-level exposure to the virus and viral proteins. We tested whether signaling through C-C chemokine receptor type 5 (CCR5) contributes to neurotoxic interactions between HIV-1 transactivator of transcription (Tat) and opiates and explored potential mechanisms. METHODS Neuronal survival was tracked in neuronal and glial co-cultures over 72 h of treatment with HIV-1 Tat ± morphine using cells from CCR5-deficient and wild-type mice exposed to the CCR5 antagonist maraviroc or exogenously-added BDNF (analyzed by repeated measures ANOVA). Intracellular calcium changes in response to Tat ± morphine ± maraviroc were assessed by ratiometric Fura-2 imaging (analyzed by repeated measures ANOVA). Release of brain-derived neurotrophic factor (BDNF) and its precursor proBDNF from CCR5-deficient and wild-type glia was measured by ELISA (analyzed by two-way ANOVA). Levels of CCR5 and μ-opioid receptor (MOR) were measured by immunoblotting (analyzed by Student's t test). RESULTS HIV-1 Tat induces neurotoxicity, which is greatly exacerbated by morphine in wild-type cultures expressing CCR5. Loss of CCR5 from glia (but not neurons) eliminated neurotoxicity due to Tat and morphine interactions. Unexpectedly, when CCR5 was lost from glia, morphine appeared to entirely protect neurons from Tat-induced toxicity. Maraviroc pre-treatment similarly eliminated neurotoxicity and attenuated neuronal increases in [Ca2+]i caused by Tat ± morphine. proBDNF/BDNF ratios were increased in conditioned media from Tat ± morphine-treated wild-type glia compared to CCR5-deficient glia. Exogenous BDNF treatments mimicked the pro-survival effect of glial CCR5 deficiency against Tat ± morphine. CONCLUSIONS Our results suggest a critical role for glial CCR5 in mediating neurotoxic effects of HIV-1 Tat and morphine interactions on neurons. A shift in the proBDNF/BDNF ratio that favors neurotrophic support may occur when glial CCR5 signaling is blocked. Some neuroprotection occurred only in the presence of morphine, suggesting that loss of CCR5 may fundamentally change signaling through the MOR in glia.
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Postmortem Brain, Cerebrospinal Fluid, and Blood Neurotrophic Factor Levels in Alzheimer's Disease: A Systematic Review and Meta-Analysis. J Mol Neurosci 2018; 65:289-300. [PMID: 29956088 DOI: 10.1007/s12031-018-1100-8] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 06/12/2018] [Indexed: 01/02/2023]
Abstract
Accumulating evidence suggest that aberrations of neurotrophic factors are involved in the etiology and pathogenesis of Alzheimer's disease (AD), but clinical data were inconsistent. Therefore, a meta-analysis on neurotrophic factor levels in AD is necessary. We performed a systematic review of blood, CSF, and post-mortem brain neurotrophic factor levels in patients with AD compared with controls and quantitatively summarized the clinical data in blood and CSF with a meta-analytical technique. A systematic search of PubMed and Web of Science identified 98 articles in this study (with samples more than 9000). Random effects meta-analysis demonstrated that peripheral blood BDNF levels were significantly decreased in AD patients compared with controls. However, blood NGF, IGF, and VEGF did not show significant differences between cases and controls. In CSF, random effects meta-analysis showed significantly deceased BDNF and increased NGF levels in patients with AD, whereas IGF and VEGF did not show significant differences between the AD group and control group. In addition, 23 post-mortem studies were included in the systematic review. Although data from post-mortem brains were not always consistent across studies, most studies suggested decreased BDNF and increased (pro)NGF levels in hippocampus and neocortex of patients with AD. These results provide strong clinical evidence that AD is accompanied by an aberrant neurotrophin profile, and future investigations into neurotrophins as biomarkers (especially CSF BDNF and NGF) and therapeutic targets for AD may be warranted.
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31
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Nogo-A inactivation improves visual plasticity and recovery after retinal injury. Cell Death Dis 2018; 9:727. [PMID: 29950598 PMCID: PMC6021388 DOI: 10.1038/s41419-018-0780-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 06/02/2018] [Accepted: 06/06/2018] [Indexed: 12/24/2022]
Abstract
Myelin-associated proteins such as Nogo-A are major inhibitors of neuronal plasticity that contribute to permanent neurological impairments in the injured CNS. In the present study, we investigated the influence of Nogo-A on visual recovery after retinal injuries in mice. Different doses of N-methyl-d-aspartate (NMDA) were injected in the vitreous of the left eye to induce retinal neuron death. The visual function was monitored using the optokinetic response (OKR) as a behavior test, and electroretinogram (ERG) and local field potential (LFP) recordings allowed to assess changes in retinal and cortical neuron activity, respectively. Longitudinal OKR follow-ups revealed reversible visual deficits after injection of NMDA ≤ 1 nmole in the left eye and concomitant functional improvement in the contralateral visual pathway of the right eye that was let intact. Irreversible OKR loss observed with NMDA ≥ 2 nmol was correlated with massive retinal cell death and important ERG response decline. Strikingly, the OKR mediated by injured and intact eye stimulation was markedly improved in Nogo-A KO mice compared with WT animals, suggesting that the inactivation of Nogo-A promotes visual recovery and plasticity. Moreover, OKR improvement was associated with shorter latency of the N2 wave of Nogo-A KO LFPs relative to WT animals. Strikingly, intravitreal injection of anti-Nogo-A antibody (11C7) in the injured eye exerted positive effects on cortical LFPs. This study presents the intrinsic ability of the visual system to recover from NMDA-induced retinal injury and its limitations. Nogo-A neutralization may promote visual recovery in retinal diseases such as glaucoma.
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Becker K, Cana A, Baumgärtner W, Spitzbarth I. p75 Neurotrophin Receptor: A Double-Edged Sword in Pathology and Regeneration of the Central Nervous System. Vet Pathol 2018; 55:786-801. [PMID: 29940812 DOI: 10.1177/0300985818781930] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The low-affinity nerve growth factor receptor p75NTR is a major neurotrophin receptor involved in manifold and pleiotropic functions in the developing and adult central nervous system (CNS). Although known for decades, its entire functions are far from being fully elucidated. Depending on the complex interactions with other receptors and on the cellular context, p75NTR is capable of performing contradictory tasks such as mediating cell death as well as cell survival. In parallel, as a prototype marker for certain differentiation stages of Schwann cells and related CNS aldynoglial cells, p75NTR has recently gained increasing notice as a marker for cells with proposed regenerative potential in CNS diseases, such as demyelinating disease and traumatic CNS injury. Besides its pivotal role as a marker for transplantation candidate cells, recent studies in canine neuroinflammatory CNS conditions also highlight a spontaneous endogenous occurrence of p75NTR-positive glia, which potentially play a role in Schwann cell-mediated CNS remyelination. The aim of the present communication is to review the pleiotropic functions of p75NTR in the CNS with a special emphasis on its role as an immunohistochemical marker in neuropathology. Following a brief illustration of the expression of p75NTR in neurogenesis and in developed neuronal populations, the implications of p75NTR expression in astrocytes, oligodendrocytes, and microglia are addressed. A special focus is put on the role of p75NTR as a cell marker for specific differentiation stages of Schwann cells and a regeneration-promoting CNS population, collectively referred to as aldynoglia.
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Affiliation(s)
- Kathrin Becker
- 1 Department of Pathology, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Armend Cana
- 1 Department of Pathology, University of Veterinary Medicine Hannover, Hannover, Germany.,2 Center for Systems Neuroscience, Hannover, Germany
| | - Wolfgang Baumgärtner
- 1 Department of Pathology, University of Veterinary Medicine Hannover, Hannover, Germany.,2 Center for Systems Neuroscience, Hannover, Germany
| | - Ingo Spitzbarth
- 1 Department of Pathology, University of Veterinary Medicine Hannover, Hannover, Germany.,2 Center for Systems Neuroscience, Hannover, Germany
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Subirada PV, Paz MC, Ridano ME, Lorenc VE, Vaglienti MV, Barcelona PF, Luna JD, Sánchez MC. A journey into the retina: Müller glia commanding survival and death. Eur J Neurosci 2018; 47:1429-1443. [PMID: 29790615 DOI: 10.1111/ejn.13965] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 04/19/2018] [Accepted: 05/03/2018] [Indexed: 12/12/2022]
Abstract
Müller glial cells (MGCs) are known to participate actively in retinal development and to contribute to homoeostasis through many intracellular mechanisms. As there are no homologous cells in other neuronal tissues, it is certain that retinal health depends on MGCs. These macroglial cells are located at the centre of the columnar subunit and have a great ability to interact with neurons, astrocytes, microglia and endothelial cells in order to modulate different events. Several investigations have focused their attention on the role of MGCs in diabetic retinopathy, a progressive pathology where several insults coexist. As expected, data suggest that MGCs display different responses according to the severity of the stimulus, and therefore trigger distinct events throughout the course of the disease. Here, we describe physiological functions of MGCs and their participation in inflammation, gliosis, synthesis and secretion of trophic and antioxidant factors in the diabetic retina. We invite the reader to consider the protective/deleterious role of MGCs in the early and late stages of the disease. In the light of the results, we open up the discussion around and ask the question: Is it possible that the modulation of a single cell type could improve or even re-establish retinal function after an injury?
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Affiliation(s)
- Paula V Subirada
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - María C Paz
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Magali E Ridano
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Valeria E Lorenc
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.,Department of Ophthalmology, The Johns Hopkins School of Medicine, Baltimore, Maryland
| | - María V Vaglienti
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Pablo F Barcelona
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - José D Luna
- Centro Privado de Ojos Romagosa-Fundación VER, Córdoba, Argentina
| | - María C Sánchez
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
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Chitranshi N, Dheer Y, Abbasi M, You Y, Graham SL, Gupta V. Glaucoma Pathogenesis and Neurotrophins: Focus on the Molecular and Genetic Basis for Therapeutic Prospects. Curr Neuropharmacol 2018; 16:1018-1035. [PMID: 29676228 PMCID: PMC6120108 DOI: 10.2174/1570159x16666180419121247] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2017] [Revised: 04/10/2018] [Accepted: 04/18/2018] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Retinal ganglion cell (RGC) degeneration is a major feature of glaucoma pathology. Neuroprotective approaches that delay or halt the progression of RGC loss are needed to prevent vision loss which can occur even after conventional medical or surgical treatments to lower intraocular pressure. OBJECTIVE The aim of this review was to examine the progress in genetics and cellular mechanisms associated with endoplasmic reticulum (ER) stress, RGC dysfunction and cell death pathways in glaucoma. MATERIALS AND METHODS Here, we review the involvement of neurotrophins like brain derived neurotrophic factor (BDNF) and its high affinity receptor tropomyosin receptor kinase (TrkB) in glaucoma. The role of ER stress markers in human and animal retinas in health and disease conditions is also discussed. Further, we analysed the literature highlighting genetic linkage in the context of primary open angle glaucoma and suggested mechanistic insights into potential therapeutic options relevant to glaucoma management. RESULTS The literature review of the neurobiology underlying neurotrophin pathways, ER stress and gene associations provide critical insights into association of RGCs death in glaucoma. Alteration in signalling pathway is associated with increased risk of misfolded protein aggregation in ER promoting RGC apoptosis. Several genes that are linked with neurotrophin signalling pathways have been reported to be associated with glaucoma pathology. CONCLUSION Understanding genetic heterogeneity and involvement of neurotrophin biology in glaucoma could help to understand the complex pathophysiology of glaucoma. Identification of novel molecular targets will be critical for drug development and provide neuroprotection to the RGCs and optic nerve.
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Affiliation(s)
- Nitin Chitranshi
- Address correspondence to this author at the Faculty of Medicine and Health Sciences, 75, Talavera Road, Macquarie University, Sydney, NSW 2109, Australia; Tel: +61-298502760; E-mail:
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Mohamed R, Shanab AY, El Remessy AB. Deletion of the Neurotrophin Receptor p75 NTR Prevents Diabetes-Induced Retinal Acellular Capillaries in Streptozotocin-Induced Mouse Diabetic Model. ACTA ACUST UNITED AC 2017; 4. [PMID: 29658956 DOI: 10.15406/jdmdc.2017.04.00129] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Diabetic retinopathy is characterized by early stage of retinal neuro-inflammation that triggers development of acellular capillaries and a late stage of pathological neovascularization. Due to limited treatment options, there is a pressing need to develop new therapeutics. Our group discovered that diabetes-impaired processing of the nerve growth factor precursor (proNGF) resulting in its accumulation and its receptor p75NTR. Here, we examine the protective effects of modulating p75NTR in experimental model of diabetic retinopathy. Diabetes was induced using streptozotocin in both wild type (WT) and p75NTR knockout (p75KO) mice. Retinal inflammation and microvascular dysfunction were assessed. Western blot analysis was performed to assess expression of apoptotic and inflammatory markers and levels of the neurotrophin, p75NTR and ephrin-B2. Deletion of p75NTR did not alter body weight or diabetes status compared to WT mice. In WT-mice, diabetes triggered retinal inflammation, significant decrease in pericyte count and marked increase in development of occluded (acellular) capillary formation after 24-weeks. Deletion of p75NTR prevented acellular capillary, restored pericyte count, and inhibited the retinal Ephrin-B2, activation of the stress-kinase JNK and apoptotic marker cleaved caspase-3 in the diabetic retina. Deletion of p75NTR reduced retinal inflammation, and proNGF expression. These effects coincided with increased NGF level and TrkA activation in the diabetic retina. Targeting p75NTR using genetic approach protected the retina from the impact of long-term diabetes in mediating microvascular degeneration and maintains the balance of NGF/proNGF level. Together, these results provide rationale that targeting p75NTR may offer novel and effective therapeutic strategy to combat diabetic retinopathy.
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Affiliation(s)
- Riyaz Mohamed
- Charlie Norwood Veterans Affairs Medical Center, USA
| | | | - Azza B El Remessy
- Charlie Norwood Veterans Affairs Medical Center, USA.,Augusta Biomedical Research Foundation, USA
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36
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Bomba M, Granzotto A, Castelli V, Massetti N, Silvestri E, Canzoniero LMT, Cimini A, Sensi SL. Exenatide exerts cognitive effects by modulating the BDNF-TrkB neurotrophic axis in adult mice. Neurobiol Aging 2017; 64:33-43. [PMID: 29331730 DOI: 10.1016/j.neurobiolaging.2017.12.009] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 12/07/2017] [Accepted: 12/08/2017] [Indexed: 12/16/2022]
Abstract
Modulation of insulin-dependent signaling is emerging as a valuable therapeutic tool to target neurodegeneration. In the brain, the activation of insulin receptors promotes cell growth, neuronal repair, and protection. Altered brain insulin signaling participates in the cognitive decline seen in Alzheimer's disease patients and the aging brain. Glucagon-like peptide-1 (GLP-1) regulates insulin secretion and, along with GLP-1 analogues, enhances neurotrophic signaling and counteracts cognitive deficits in preclinical models of neurodegeneration. Moreover, recent evidence indicates that GLP-1 modulates the activity of the brain-derived neurotrophic factor (BDNF). In this study, in adult wild-type mice, here employed as a model of mid-life brain aging, we evaluated the effects of a 2-month treatment with exenatide, a GLP-1 analogue. We found that exenatide promotes the enhancement of long-term memory performances. Biochemical and imaging analyses show that the drug promotes the activation of the BDNF-TrkB neurotrophic axis and inhibits apoptosis by decreasing p75NTR-mediated signaling. The study provides preclinical evidence for the use of exenatide to delay age-dependent cognitive decline.
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Affiliation(s)
- Manuela Bomba
- Center of Excellence on Aging and Translational Medicine - CeSI-MeT, University G. d'Annunzio of Chieti-Pescara, Italy; Department of Neuroscience, Imaging, and Clinical Sciences, University G. d'Annunzio of Chieti-Pescara, Italy
| | - Alberto Granzotto
- Center of Excellence on Aging and Translational Medicine - CeSI-MeT, University G. d'Annunzio of Chieti-Pescara, Italy; Department of Neuroscience, Imaging, and Clinical Sciences, University G. d'Annunzio of Chieti-Pescara, Italy
| | - Vanessa Castelli
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Italy
| | - Noemi Massetti
- Center of Excellence on Aging and Translational Medicine - CeSI-MeT, University G. d'Annunzio of Chieti-Pescara, Italy
| | - Elena Silvestri
- Division of Pharmacology, Department of Science and Technology, University of Sannio, Benevento, Italy
| | - Lorella M T Canzoniero
- Division of Pharmacology, Department of Science and Technology, University of Sannio, Benevento, Italy
| | - Annamaria Cimini
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Italy; Sbarro Institute for Cancer Research and Molecular Medicine and Center for Biotechnology, Temple University, Philadelphia, USA; National Institute for Nuclear Physics (INFN), Gran Sasso National Laboratory (LNGS), Assergi, Italy
| | - Stefano L Sensi
- Center of Excellence on Aging and Translational Medicine - CeSI-MeT, University G. d'Annunzio of Chieti-Pescara, Italy; Department of Neuroscience, Imaging, and Clinical Sciences, University G. d'Annunzio of Chieti-Pescara, Italy; Departments of Neurology and Pharmacology, Institute for Mind Impairments and Neurological Disorders, University of California - Irvine, Irvine, USA.
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Inducible overexpression of endothelial proNGF as a mouse model to study microvascular dysfunction. Biochim Biophys Acta Mol Basis Dis 2017; 1864:746-757. [PMID: 29253516 DOI: 10.1016/j.bbadis.2017.12.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 12/07/2017] [Accepted: 12/13/2017] [Indexed: 12/14/2022]
Abstract
Impaired maturation of nerve growth factor precursor (proNGF) and its accumulation has been reported in several neurodegenerative diseases, myocardial infarction and diabetes. To elucidate the direct impact of proNGF accumulation identified the need to create a transgenic model that can express fully mutated cleavage-resistant proNGF. Using Cre-Lox technology, we developed an inducible endothelial-specific proNGF transgenic mouse (proNGFLoxp) that overexpresses GFP-conjugated cleavage-resistant proNGF123 when crossed with VE-cadherin-CreERT2 (Cre). Expression of proNGF, inflammatory mediators, NGF and VEGF was evaluated by PCR, Western blot and immunohistochemistry. EC-proNGF overexpression was confirmed using colocalization of anti-proNGF within retinal vasculature. EC-proNGF did not cause retinal neurotoxicity or marked glial activation at 4-weeks. Microvascular preparation from Cre-proNGF mice showed significant imbalance of proNGF/NGF ratio, enhanced expression of TNF-α and p75NTR, and tendency to impair TrkA phosphorylation compared to controls. EC-proNGF overexpression triggered mRNA expression of p75NTR and inflammatory mediators in both retina and renal cortex compared to controls. EC-proNGF expression induced vascular permeability including breakdown of BRB and albuminuria in the kidney without affecting VEGF level at 4-weeks. Histopathological changes were assessed after 8-weeks and the results showed that EC-proNGF triggered formation of occluded (acellular) capillaries, hall mark of retinal ischemia. EC-proNGF resulted in glomerular enlargement and kidney fibrosis, hall mark of renal dysfunction. We have successfully created an inducible mouse model that can dissect the contribution of autocrine direct action of cleavage-resistant proNGF on systemic microvascular abnormalities in both retina and kidney, major targets for microvascular complication.
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Galán A, Jmaeff S, Barcelona PF, Brahimi F, Sarunic MV, Saragovi HU. In retinitis pigmentosa TrkC.T1-dependent vectorial Erk activity upregulates glial TNF-α, causing selective neuronal death. Cell Death Dis 2017; 8:3222. [PMID: 29242588 PMCID: PMC5870594 DOI: 10.1038/s41419-017-0074-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 07/26/2017] [Accepted: 08/04/2017] [Indexed: 12/13/2022]
Abstract
In some diseases the TrkC.T1 isoform is upregulated in glia, associated with glial TNF-α production and neuronal death. What remains unknown are the activating signals in glia, and how paracrine signals may be selective for a targeted neuron while sparing other proximate neurons. We studied these questions in the retina, where Müller glia contacts photoreceptors on one side and retinal ganglion cells on the other. In a mutant Rhodopsin mouse model of retinitis pigmentosa (RP) causing progressive photoreceptor death—but sparing retinal ganglion cells—TrkC.T1 and NT-3 ligand are upregulated in Müller glia. TrkC.T1 activity generates p-Erk, which causes increased TNF-α. These sequential events take place predominantly in Müller fibers contacting stressed photoreceptors, and culminate in selective death. Each event and photoreceptor death can be prevented by reduction of TrkC.T1 expression, by pharmacological antagonism of TrkC or by pharmacological inhibition Erk. Unmasking the sequence of non-cell autologous events and mechanisms causing selective neuronal death may help rationalize therapies.
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Affiliation(s)
- Alba Galán
- Lady Davis Institute-Jewish General Hospital, McGill University, Montréal, QC, H3T 1E2, Canada
| | - Sean Jmaeff
- Lady Davis Institute-Jewish General Hospital, McGill University, Montréal, QC, H3T 1E2, Canada.,Department of Pharmacology and Therapeutics, McGill University, Montréal, QC, Canada
| | - Pablo F Barcelona
- Lady Davis Institute-Jewish General Hospital, McGill University, Montréal, QC, H3T 1E2, Canada
| | - Fouad Brahimi
- Lady Davis Institute-Jewish General Hospital, McGill University, Montréal, QC, H3T 1E2, Canada
| | - Marinko V Sarunic
- School of Engineering Science, Simon Fraser University, Burnaby, BC, Canada
| | - H Uri Saragovi
- Lady Davis Institute-Jewish General Hospital, McGill University, Montréal, QC, H3T 1E2, Canada. .,Department of Pharmacology and Therapeutics, McGill University, Montréal, QC, Canada. .,Department of Ophthalmology, McGill University, Montréal, QC, Canada.
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Livne-Bar I, Wei J, Liu HH, Alqawlaq S, Won GJ, Tuccitto A, Gronert K, Flanagan JG, Sivak JM. Astrocyte-derived lipoxins A4 and B4 promote neuroprotection from acute and chronic injury. J Clin Invest 2017; 127:4403-4414. [PMID: 29106385 DOI: 10.1172/jci77398] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 09/26/2017] [Indexed: 12/31/2022] Open
Abstract
Astrocytes perform critical non-cell autonomous roles following CNS injury that involve either neurotoxic or neuroprotective effects. Yet the nature of potential prosurvival cues has remained unclear. In the current study, we utilized the close interaction between astrocytes and retinal ganglion cells (RGCs) in the eye to characterize a secreted neuroprotective signal present in retinal astrocyte conditioned medium (ACM). Rather than a conventional peptide neurotrophic factor, we identified a prominent lipid component of the neuroprotective signal through metabolomics screening. The lipoxins LXA4 and LXB4 are small lipid mediators that act locally to dampen inflammation, but they have not been linked directly to neuronal actions. Here, we determined that LXA4 and LXB4 are synthesized in the inner retina, but their levels are reduced following injury. Injection of either lipoxin was sufficient for neuroprotection following acute injury, while inhibition of key lipoxin pathway components exacerbated injury-induced damage. Although LXA4 signaling has been extensively investigated, LXB4, the less studied lipoxin, emerged to be more potent in protection. Moreover, LXB4 neuroprotection was different from that of established LXA4 signaling, and therapeutic LXB4 treatment was efficacious in a chronic model of the common neurodegenerative disease glaucoma. Together, these results identify a potential paracrine mechanism that coordinates neuronal homeostasis and inflammation in the CNS.
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Affiliation(s)
- Izhar Livne-Bar
- Department of Vision Sciences, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada.,Department of Ophthalmology and Vision Science, University of Toronto, Toronto, Ontario, Canada
| | - Jessica Wei
- Vision Science Program, School of Optometry, University of California at Berkeley, Berkeley, California, USA
| | - Hsin-Hua Liu
- Vision Science Program, School of Optometry, University of California at Berkeley, Berkeley, California, USA
| | - Samih Alqawlaq
- Department of Vision Sciences, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada.,Department of Ophthalmology and Vision Science, University of Toronto, Toronto, Ontario, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Gah-Jone Won
- Department of Vision Sciences, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada.,Department of Ophthalmology and Vision Science, University of Toronto, Toronto, Ontario, Canada
| | - Alessandra Tuccitto
- Department of Vision Sciences, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada.,Department of Ophthalmology and Vision Science, University of Toronto, Toronto, Ontario, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Karsten Gronert
- Vision Science Program, School of Optometry, University of California at Berkeley, Berkeley, California, USA
| | - John G Flanagan
- Vision Science Program, School of Optometry, University of California at Berkeley, Berkeley, California, USA
| | - Jeremy M Sivak
- Department of Vision Sciences, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada.,Department of Ophthalmology and Vision Science, University of Toronto, Toronto, Ontario, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
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40
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Tse DY, Kim SJ, Chung I, He F, Wensel TG, Wu SM. The ocular toxicity and pharmacokinetics of simvastatin following intravitreal injection in mice. Int J Ophthalmol 2017; 10:1361-1369. [PMID: 28944193 DOI: 10.18240/ijo.2017.09.05] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 04/21/2017] [Indexed: 11/23/2022] Open
Abstract
AIM To investigate the retinal toxicity and pharmacokinetics of simvastatin intravitreally injected into mice. METHODS Forty-eight 6-8-week-old C57BL/6J mice were used in this study. Simvastatin was intravitreally injected into the right eye of each mouse; the left eye was injected with vehicle and was used as a control. Bilateral dark-adapted electroretinography (ERG) was performed 1 and 7d following injection. Histology was examined using a combination of light, fluorescence and electron microscopy. High-performance liquid chromatography (HPLC) was used to determine the decay in the retinal simvastatin concentration. RESULTS ERG revealed no significant changes in the simvastatin-injected eyes compared to control. Histologic studies showed normal retinal morphology in eyes injected with simvastatin up to a final vitreal concentration of 200 µmol/L. No significant changes in the number of photoreceptors, bipolar cells or ganglion cells were found. The retinal simvastatin concentration decayed exponentially, with a half-life of 1.92-2.41h. CONCLUSION Intravitreal injection of up to 200 µmol/L simvastatin produced no signs of adverse effects in the mouse retina. Simvastatin reaches the retina shortly after intravitreal injectionand has a short half-life.
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Affiliation(s)
- Dennis Y Tse
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX 77030, USA.,School of Optometry, the Hong Kong Polytechnic University, Hong Kong, China
| | - Seong Jae Kim
- Department of Ophthalmology, Institute of Health Sciences, College of Medicine, Gyeongsang National University, Jinju 52727, Korea
| | - Inyoung Chung
- Department of Ophthalmology, Institute of Health Sciences, College of Medicine, Gyeongsang National University, Jinju 52727, Korea
| | - Feng He
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Theodore G Wensel
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Samuel M Wu
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX 77030, USA
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Bachis A, Campbell LA, Jenkins K, Wenzel E, Mocchetti I. Morphine Withdrawal Increases Brain-Derived Neurotrophic Factor Precursor. Neurotox Res 2017; 32:509-517. [PMID: 28776309 DOI: 10.1007/s12640-017-9788-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 06/28/2017] [Accepted: 07/21/2017] [Indexed: 11/30/2022]
Abstract
Morphine has been shown to increase the expression of brain-derived neurotrophic factor (BDNF) in the brain. However, little is known about the effect of morphine withdrawal on BDNF and its precursor protein, or proBDNF, which induces neuronal apoptosis. In this work, we examined whether BDNF and proBDNF levels change in rats chronically injected with escalating doses of morphine and those who undergo spontaneous withdrawal for 60 h. We observed, in the frontal cortex and striatum, that the ratio of BDNF to proBDNF changed depending upon the experimental paradigm. Morphine treatment and morphine withdrawal increased both BDNF and proBDNF levels. However, the increase in proBDNF immunoreactivity in withdrawal rats was more robust than that observed in morphine-treated rats. proBDNF is processed either intracellularly by furin or extracellularly by the tissue plasminogen activator (tPA)/plasminogen system or matrix metalloproteases (MMPs). To examine the mechanisms whereby chronic morphine treatment and morphine withdrawal differentially affects BDNF/proBDNF, the levels MMP-3 and MMP-7, furin, and tPA were analyzed. We found that morphine increases tPA levels, whereas withdrawal causes a decrease. To confirm the involvement of tPA in the morphine-mediated effect on BDNF/proBDNF, we exposed cortical neurons to morphine in the presence of the tPA inhibitor plasminogen activator inhibitor-1 (PAI-1). This inhibitor reversed the morphine-mediated decrease in proBDNF, supporting the hypothesis that morphine increases the availability of BDNF by promoting the extracellular processing of proBDNF by tPA. Because proBDNF could negatively influence synaptic repair, preventing withdrawal is crucial for reducing neurotoxic mechanisms associated with opioid abuse.
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Affiliation(s)
- Alessia Bachis
- Laboratory of Preclinical Neurobiology, Department of Neuroscience, Georgetown University Medical Center, 3970 Reservoir Rd NW, Washington, DC, 20057, USA
| | - Lee A Campbell
- Laboratory of Preclinical Neurobiology, Department of Neuroscience, Georgetown University Medical Center, 3970 Reservoir Rd NW, Washington, DC, 20057, USA.,Medical Development Program, National Institute on Drug Abuse, Intramural Research Program, National Institute of Health, DHHS, Baltimore, MD, 21224, USA
| | - Kierra Jenkins
- Laboratory of Preclinical Neurobiology, Department of Neuroscience, Georgetown University Medical Center, 3970 Reservoir Rd NW, Washington, DC, 20057, USA
| | - Erin Wenzel
- Laboratory of Preclinical Neurobiology, Department of Neuroscience, Georgetown University Medical Center, 3970 Reservoir Rd NW, Washington, DC, 20057, USA.,Department of Pharmacology, Georgetown University Medical Center, Washington, DC, 20057, USA
| | - Italo Mocchetti
- Laboratory of Preclinical Neurobiology, Department of Neuroscience, Georgetown University Medical Center, 3970 Reservoir Rd NW, Washington, DC, 20057, USA.
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Platón-Corchado M, Barcelona PF, Jmaeff S, Marchena M, Hernández-Pinto AM, Hernández-Sánchez C, Saragovi HU, de la Rosa EJ. p75 NTR antagonists attenuate photoreceptor cell loss in murine models of retinitis pigmentosa. Cell Death Dis 2017; 8:e2922. [PMID: 28703796 PMCID: PMC5550853 DOI: 10.1038/cddis.2017.306] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 04/26/2017] [Accepted: 05/29/2017] [Indexed: 12/23/2022]
Abstract
ProNGF signaling through p75NTR has been associated with neurodegenerative disorders. Retinitis pigmentosa (RP) comprises a group of inherited retinal dystrophies that causes progressive photoreceptor cell degeneration and death, at a rate dependent on the genetic mutation. There are more than 300 mutations causing RP, and this is a challenge to therapy. Our study was designed to explore a common mechanism for p75NTR in the progression of RP, and assess its potential value as a therapeutic target. The proNGF/p75NTR system is present in the dystrophic retina of the rd10 RP mouse model. Compared with wild-type (WT) retina, the levels of unprocessed proNGF were increased in the rd10 retina at early degenerative stages, before the peak of photoreceptor cell death. Conversely, processed NGF levels were similar in rd10 and WT retinas. ProNGF remained elevated throughout the period of photoreceptor cell loss, correlating with increased expression of α2-macroglobulin, an inhibitor of proNGF processing. The neuroprotective effect of blocking p75NTR was assessed in organotypic retinal cultures from rd10 and RhoP mouse models. Retinal explants treated with p75NTR antagonists showed significantly reduced photoreceptor cell death, as determined by the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay and by preservation of the thickness of the outer nuclear layer (ONL), where photoreceptor nuclei are located. This effect was accompanied by decreased retinal-reactive gliosis and reduced TNFα secretion. Use of p75NTR antagonist THX-B (1,3-diisopropyl-1-[2-(1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-purin-7-yl)-acetyl]-urea) in vivo in the rd10 and RhoP mouse models, by a single intravitreal or subconjunctival injection, afforded neuroprotection to photoreceptor cells, with preservation of the ONL. This study demonstrates a role of the p75NTR/proNGF axis in the progression of RP, and validates these proteins as therapeutic targets in two different RP models, suggesting utility irrespective of etiology.
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Affiliation(s)
| | - Pablo F Barcelona
- Lady Davis Institute-Jewish General Hospital, McGill University, Montreal, QC, Canada
| | - Sean Jmaeff
- Lady Davis Institute-Jewish General Hospital, McGill University, Montreal, QC, Canada
| | | | | | | | - H Uri Saragovi
- Lady Davis Institute-Jewish General Hospital, McGill University, Montreal, QC, Canada
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Danford ID, Verkuil LD, Choi DJ, Collins DW, Gudiseva HV, Uyhazi KE, Lau MK, Kanu LN, Grant GR, Chavali VRM, O'Brien JM. Characterizing the "POAGome": A bioinformatics-driven approach to primary open-angle glaucoma. Prog Retin Eye Res 2017; 58:89-114. [PMID: 28223208 PMCID: PMC5464971 DOI: 10.1016/j.preteyeres.2017.02.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 02/03/2017] [Accepted: 02/10/2017] [Indexed: 01/10/2023]
Abstract
Primary open-angle glaucoma (POAG) is a genetically, physiologically, and phenotypically complex neurodegenerative disorder. This study addressed the expanding collection of genes associated with POAG, referred to as the "POAGome." We used bioinformatics tools to perform an extensive, systematic literature search and compiled 542 genes with confirmed associations with POAG and its related phenotypes (normal tension glaucoma, ocular hypertension, juvenile open-angle glaucoma, and primary congenital glaucoma). The genes were classified according to their associated ocular tissues and phenotypes, and functional annotation and pathway analyses were subsequently performed. Our study reveals that no single molecular pathway can encompass the pathophysiology of POAG. The analyses suggested that inflammation and senescence may play pivotal roles in both the development and perpetuation of the retinal ganglion cell degeneration seen in POAG. The TGF-β signaling pathway was repeatedly implicated in our analyses, suggesting that it may be an important contributor to the manifestation of POAG in the anterior and posterior segments of the globe. We propose a molecular model of POAG revolving around TGF-β signaling, which incorporates the roles of inflammation and senescence in this disease. Finally, we highlight emerging molecular therapies that show promise for treating POAG.
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Affiliation(s)
- Ian D Danford
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Lana D Verkuil
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Daniel J Choi
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - David W Collins
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Harini V Gudiseva
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Katherine E Uyhazi
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Marisa K Lau
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Levi N Kanu
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Gregory R Grant
- Department of Genetics, University of Pennsylvania, Philadelphia, PA, USA, Penn Center for Bioinformatics, University of Pennsylvania, Philadelphia, PA, USA
| | - Venkata R M Chavali
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA.
| | - Joan M O'Brien
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, 19104, USA
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Garcia TB, Hollborn M, Bringmann A. Expression and signaling of NGF in the healthy and injured retina. Cytokine Growth Factor Rev 2017; 34:43-57. [PMID: 27964967 DOI: 10.1016/j.cytogfr.2016.11.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 11/28/2016] [Indexed: 01/02/2023]
Abstract
This review summarizes the present knowledge concerning the retinal localization of the nerve growth factor (NGF), its precursor proNGF, and the receptors TrkA and p75NTR in the developing and mature rodent retina. We further discuss the changes in the expression of NGF and the receptors in experimental models of retinal disorders and diseases like inherited retinitis pigmentosa, retinal detachment, glaucoma, and diabetic retinopathy. Since proNGF is now recognized as a bioactive signaling molecule which induces cell death through p75NTR activation, the role of proNGF in the induction of retinal cell loss under neurodegenerative conditions is also highlighted. In addition, we present the evidences for a potential therapeutic intervention with NGF for the treatment of retinal neurodegenerative diseases. Different strategies have been developed and experimentally tested in mice and rats in order to reduce cell loss and Müller cell gliosis, e.g., increasing the availability of endogenous NGF, administration of exogenous NGF, activation of TrkA, and inhibition of p75NTR. Here, we discuss the several lines of evidence supporting a protective effect of NGF on retinal cell loss, with specific emphasis on photoreceptor and retinal ganglion cell degeneration. A better understanding of the mechanisms underlying the effects of NGF and proNGF in the modulation of neurodegeneration and gliosis in the retina will help to develop efficient therapeutic strategies for various retinal diseases.
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Affiliation(s)
| | - Margrit Hollborn
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany
| | - Andreas Bringmann
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany
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Time-Dependent Nerve Growth Factor Signaling Changes in the Rat Retina During Optic Nerve Crush-Induced Degeneration of Retinal Ganglion Cells. Int J Mol Sci 2017; 18:ijms18010098. [PMID: 28067793 PMCID: PMC5297732 DOI: 10.3390/ijms18010098] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 12/20/2016] [Accepted: 12/24/2016] [Indexed: 01/06/2023] Open
Abstract
Nerve growth factor (NGF) is suggested to be neuroprotective after nerve injury; however, retinal ganglion cells (RGC) degenerate following optic-nerve crush (ONC), even in the presence of increased levels of endogenous NGF. To further investigate this apparently paradoxical condition, a time-course study was performed to evaluate the effects of unilateral ONC on NGF expression and signaling in the adult retina. Visually evoked potential and immunofluorescence staining were used to assess axonal damage and RGC loss. The levels of NGF, proNGF, p75NTR, TrkA and GFAP and the activation of several intracellular pathways were analyzed at 1, 3, 7 and 14 days after crush (dac) by ELISA/Western Blot and PathScan intracellular signaling array. The progressive RGC loss and nerve impairment featured an early and sustained activation of apoptotic pathways; and GFAP and p75NTR enhancement. In contrast, ONC-induced reduction of TrkA, and increased proNGF were observed only at 7 and 14 dac. We propose that proNGF and p75NTR contribute to exacerbate retinal degeneration by further stimulating apoptosis during the second week after injury, and thus hamper the neuroprotective effect of the endogenous NGF. These findings might aid in identifying effective treatment windows for NGF-based strategies to counteract retinal and/or optic-nerve degeneration.
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Elshaer SL, El-Remessy AB. Implication of the neurotrophin receptor p75 NTR in vascular diseases: beyond the eye. EXPERT REVIEW OF OPHTHALMOLOGY 2016; 12:149-158. [PMID: 28979360 DOI: 10.1080/17469899.2017.1269602] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
INTRODUCTION The p75 neurotrophin receptor (p75NTR) is a member of TNF-α receptor superfamily that bind all neurotrophins, mainly regulating their pro-apoptotic actions. Ischemia is a common pathology in different cardiovascular diseases affecting multiple organs, however the contribution of p75NTR remains not fully addressed. The aim of this work is to review the current evidence through published literature studying the impact of p75NTR receptor in ischemic vascular diseases. AREAS COVERED In the eye, several ischemic ocular diseases are associated with enhanced p75NTR expression. Ischemic retinopathy including diabetic retinopathy, retinopathy of prematurity and retinal vein occlusion are characterized initially by ischemia followed by excessive neovascularization. Beyond the eye, cerebral ischemia, myocardial infarction and critical limb ischemia are ischemic cardiovascular diseases that are characterized by altered expression of neurotrophins and p75NTR expression. We surveyed both clinical and experimental studies that examined the impact of p75NTR receptor in ischemic diseases of eye, heart, brain and peripheral limbs. EXPERT COMMENTARY p75NTR receptor is a major player in multiple ischemic vascular diseases affecting the eye, brain, heart and peripheral limbs with significant increases in its expression accompanying neuro-vascular injury. This has been addressed in the current review along with the beneficial vascular outcomes of p75NTR inhibition.
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Affiliation(s)
- Sally L Elshaer
- Program in Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia, Augusta, GA, USA.,Research Service, Charlie Norwood VA Medical Center, Augusta, GA
| | - Azza B El-Remessy
- Program in Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia, Augusta, GA, USA.,Research Service, Charlie Norwood VA Medical Center, Augusta, GA.,Augusta Biomedical Research Corporation, Augusta, GA, USA
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Mysona BA, Zhao J, Bollinger KE. Role of BDNF/TrkB pathway in the visual system: Therapeutic implications for glaucoma. EXPERT REVIEW OF OPHTHALMOLOGY 2016; 12:69-81. [PMID: 28751923 DOI: 10.1080/17469899.2017.1259566] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
INTRODUCTION Neuroprotective therapeutics are needed to treat glaucoma, an optic neuropathy that results in death of retinal ganglion cells (RGCs). AREAS COVERED The BDNF/TrkB pathway is important for RGC survival. Temporal and spatial alterations in the BDNF/TrkB pathway occur in development and in response to acute optic nerve injury and to glaucoma. In animal models, BDNF supplementation is successful at slowing RGC death after acute optic nerve injury and in glaucoma, however, the BDNF/TrkB signaling is not the only pathway supporting long term RGC survival. EXPERT COMMENTARY Much remains to be discovered about the interaction between retrograde, anterograde, and retinal BDNF/TrkB signaling pathways in both neurons and glia. An ideal therapeutic agent for glaucoma likely has several modes of action that target multiple mechanisms of neurodegeneration including the BDNF/TrkB pathway.
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Affiliation(s)
- B A Mysona
- Augusta University Department of Cellular Biology and Anatomy, James and Jean Culver Vision Discovery Institute. Address: Augusta University Department of Cellular Biology and Anatomy, Health Sciences Campus, 1120 15th Street, Augusta, GA 30912, USA,
| | - J Zhao
- Medical College of Georgia, Department of Ophthalmology at Augusta University, James and Jean Culver Vision Discovery Institute. Address: Medical College of Georgia, Department of Ophthalmology at Augusta University, 1120 15th Street, Augusta, GA 30912, USA,
| | - K E Bollinger
- Medical College of Georgia, Department of Ophthalmology at Augusta University, Augusta University Department of Cellular Biology and Anatomy, James and Jean Culver Vision Discovery Institute. Address: Medical College of Georgia, Department of Ophthalmology at Augusta University, 1120 15th Street, Augusta, GA 30912, USA,
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Pramanik S, Sulistio YA, Heese K. Neurotrophin Signaling and Stem Cells-Implications for Neurodegenerative Diseases and Stem Cell Therapy. Mol Neurobiol 2016; 54:7401-7459. [PMID: 27815842 DOI: 10.1007/s12035-016-0214-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 10/11/2016] [Indexed: 02/07/2023]
Abstract
Neurotrophins (NTs) are members of a neuronal growth factor protein family whose action is mediated by the tropomyosin receptor kinase (TRK) receptor family receptors and the p75 NT receptor (p75NTR), a member of the tumor necrosis factor (TNF) receptor family. Although NTs were first discovered in neurons, recent studies have suggested that NTs and their receptors are expressed in various types of stem cells mediating pivotal signaling events in stem cell biology. The concept of stem cell therapy has already attracted much attention as a potential strategy for the treatment of neurodegenerative diseases (NDs). Strikingly, NTs, proNTs, and their receptors are gaining interest as key regulators of stem cells differentiation, survival, self-renewal, plasticity, and migration. In this review, we elaborate the recent progress in understanding of NTs and their action on various stem cells. First, we provide current knowledge of NTs, proNTs, and their receptor isoforms and signaling pathways. Subsequently, we describe recent advances in the understanding of NT activities in various stem cells and their role in NDs, particularly Alzheimer's disease (AD) and Parkinson's disease (PD). Finally, we compile the implications of NTs and stem cells from a clinical perspective and discuss the challenges with regard to transplantation therapy for treatment of AD and PD.
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Affiliation(s)
- Subrata Pramanik
- Graduate School of Biomedical Science and Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 133-791, Republic of Korea
| | - Yanuar Alan Sulistio
- Graduate School of Biomedical Science and Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 133-791, Republic of Korea
| | - Klaus Heese
- Graduate School of Biomedical Science and Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 133-791, Republic of Korea.
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Livne-Bar I, Lam S, Chan D, Guo X, Askar I, Nahirnyj A, Flanagan JG, Sivak JM. Pharmacologic inhibition of reactive gliosis blocks TNF-α-mediated neuronal apoptosis. Cell Death Dis 2016; 7:e2386. [PMID: 27685630 PMCID: PMC5059876 DOI: 10.1038/cddis.2016.277] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 07/25/2016] [Accepted: 07/29/2016] [Indexed: 01/03/2023]
Abstract
Reactive gliosis is an early pathological feature common to most neurodegenerative diseases, yet its regulation and impact remain poorly understood. Normally astrocytes maintain a critical homeostatic balance. After stress or injury they undergo rapid parainflammatory activation, characterized by hypertrophy, and increased polymerization of type III intermediate filaments (IFs), particularly glial fibrillary acidic protein and vimentin. However, the consequences of IF dynamics in the adult CNS remains unclear, and no pharmacologic tools have been available to target this mechanism in vivo. The mammalian retina is an accessible model to study the regulation of astrocyte stress responses, and their influence on retinal neuronal homeostasis. In particular, our work and others have implicated p38 mitogen-activated protein kinase (MAPK) signaling as a key regulator of glutamate recycling, antioxidant activity and cytokine secretion by astrocytes and related Müller glia, with potent influences on neighboring neurons. Here we report experiments with the small molecule inhibitor, withaferin A (WFA), to specifically block type III IF dynamics in vivo. WFA was administered in a model of metabolic retinal injury induced by kainic acid, and in combination with a recent model of debridement-induced astrocyte reactivity. We show that WFA specifically targets IFs and reduces astrocyte and Müller glial reactivity in vivo. Inhibition of glial IF polymerization blocked p38 MAPK-dependent secretion of TNF-α, resulting in markedly reduced neuronal apoptosis. To our knowledge this is the first study to demonstrate that pharmacologic inhibition of IF dynamics in reactive glia protects neurons in vivo.
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Affiliation(s)
- Izhar Livne-Bar
- Department of Vision Sciences, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada.,School of Optometry, University of California at Berkeley, Berkeley, CA, USA
| | - Susy Lam
- Department of Vision Sciences, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Darren Chan
- Department of Vision Sciences, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Xiaoxin Guo
- Department of Vision Sciences, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Idil Askar
- Department of Vision Sciences, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Adrian Nahirnyj
- Department of Vision Sciences, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada
| | - John G Flanagan
- School of Optometry, University of California at Berkeley, Berkeley, CA, USA
| | - Jeremy M Sivak
- Department of Vision Sciences, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada.,Department of Ophthalmology and Vision Science, University of Toronto, Toronto, Ontario, Canada
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50
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Luke MPS, LeVatte TL, Rutishauser U, Tremblay F, Clarke DB. Polysialylated Neural Cell Adhesion Molecule Protects Against Light-Induced Retinal Degeneration. Invest Ophthalmol Vis Sci 2016; 57:5066-5075. [PMID: 27661859 PMCID: PMC6012193 DOI: 10.1167/iovs.16-19499] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Purpose We previously demonstrated that neural cell adhesion molecule (NCAM) plays an important role in supporting the survival of injured retinal ganglion cells. In the current study, we used light-induced retinal degeneration (LIRD) as a model to investigate whether NCAM plays a functional role in neuroprotection and whether NCAM influences p75NTR signaling in modulating retinal cell survival. Methods Retinas from wild-type (WT) and NCAM deficient (−/−) mice were tested by electroretinogram before and after LIRD, and changes in the protein expressions of NCAM, polysialic acid (PSA)-NCAM, p75NTR, and active caspase 3 were measured by immunoblot from 0 to 4 days after light induction. The effects of NCAM and PSA-NCAM on p75NTR were examined by intraocular injections of the p75NTR function-blocking antibody and/or the removal of PSA with endoneuraminidase-N prior to LIRD. Results In WT mice, low levels of active caspase 3 activation were detected on the first day, followed by increases up to 4 days after LIRD. Conversely, in NCAM−/− mice, higher cleaved caspase 3 levels along with rapid reductions in electroretinogram amplitudes were found earlier at day 1, followed by reduced levels by day 4. The removal of PSA prior to LIRD induced earlier onset of retinal cell death, an effect delayed by the coadministration of endoneuraminidase-N and the p75NTR function-blocking antibody antiserum. Conclusions These results indicate that NCAM protects WT retinas from LIRD; furthermore, the protective effect of NCAM is, at least in part, attributed to its effects on p75NTR.
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Affiliation(s)
- Margaret Po-Shan Luke
- Department of Medical Neuroscience, Dalhousie University, Life Science Research Institute, Halifax, Nova Scotia, Canada
| | - Terry L LeVatte
- Department of Medical Neuroscience, Dalhousie University, Life Science Research Institute, Halifax, Nova Scotia, Canada
| | - Urs Rutishauser
- Cellular and Developmental Neuroscience, Department of Cell Biology, Sloan-Kettering Institute, Memorial Sloan-Kettering Cancer Center, New York, New York, United States
| | - François Tremblay
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada 4Department of Ophthalmology & Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada
| | - David B Clarke
- Department of Medical Neuroscience, Dalhousie University, Life Science Research Institute, Halifax, Nova Scotia, Canada 4Department of Ophthalmology & Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada 5Department of Surgery (Neurosurgery), Dalhousie University, Halifax, Nova Scotia, Canada
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