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Wu S, Su Y, Wang Y, Wang J, Xu D, Liu Y, Yang K, Gao J, Cui J, Bai W. Region-specific response of central microglial cells to sciatic nerve demyelination through sensory and motor pathways. Histol Histopathol 2024; 39:771-781. [PMID: 38051019 DOI: 10.14670/hh-18-681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
Peripheral nerve injury can cause changes in microglial cells on the spinal dorsal and ventral horns. This region-specific response implies that central microglial cells could be activated through both sensory and motor pathways. In order to further determine how peripheral nerve injury activates central microglial cells through neural pathways, the sciatic nerve was selected as the target for neural tract tracing and demyelination. Firstly, we used cholera toxin subunit B (CTB) to map the central sensory and motor territories of the sciatic nerve. Secondly, we applied lysophosphatidylcholine to establish the model of sciatic nerve demyelination and examined the distribution of activated microglial cells via immunofluorescence with ionized calcium-binding adapter molecule 1. It was shown that CTB labeling included the transganglionically labeled sensory afferents and retrogradely labeled somata of motor neurons along the sensory and motor pathways of the sciatic nerve ipsilateral to the injection, in which sensory afferents terminated on the gracile nucleus, Clarke's nucleus, and spinal dorsal horn, while motor neurons located on the spinal ventral horn. Consistently, after sciatic nerve demyelination, the activated microglial cells were observed in the same territories as CTB-labeling, showing shortened processes and enlarged cell bodies. These results support the idea that central microglia might be activated by signals from the demyelinated sciatic nerve through both sensory and motor pathways.
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Affiliation(s)
- Shuang Wu
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, PR China
| | - Yuxin Su
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, PR China
| | - Yuqing Wang
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, PR China
| | - Jia Wang
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, PR China
| | - Dongsheng Xu
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, PR China
| | - Yihan Liu
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, PR China
| | - Kunwu Yang
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, PR China
| | - Junhong Gao
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, PR China
| | - Jingjing Cui
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, PR China.
| | - Wanzhu Bai
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, PR China.
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2
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Yang Q, Vazquez AL, Cui XT. Revealing in vivo cellular mechanisms of cerebral microbleeds on neurons and microglia across cortical layers. iScience 2024; 27:109371. [PMID: 38510113 PMCID: PMC10951986 DOI: 10.1016/j.isci.2024.109371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 12/28/2023] [Accepted: 02/26/2024] [Indexed: 03/22/2024] Open
Abstract
Cerebral microbleeds (CMBs) are associated with higher risk for various neurological diseases including stroke, dementia, and Alzheimer's disease. However, the understanding of cellular pathology of CMBs, particularly in deep brain regions, remains limited. Utilizing two-photon microscopy and microprism implantation, we longitudinally imaged the impact of CMBs on neuronal and microglial activities across cortical depths in awake mice. A temporary decline in spontaneous neuronal activity occurred throughout cortical layers, followed by recovery within a week. However, significant changes of neuron-neuron activity correlations persisted for weeks. Moreover, microglial contact with neuron soma significantly increased post-microbleeds, indicating an important modulatory role of microglia. Notably, microglial contact, negatively correlated with neuronal firing rate in normal conditions, became uncorrelated after microbleeds, suggesting a decreased neuron-microglia inhibition. These findings reveal chronic alterations in cortical neuronal networks and microglial-neuronal interactions across cortical depths, shedding light on the pathology of CMBs.
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Affiliation(s)
- Qianru Yang
- Department of Neurosurgery, Stanford University, Palo Alto, CA, USA
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, Pittsburgh, PA, USA
| | - Alberto L. Vazquez
- Center for Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, Pittsburgh, PA, USA
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - X. Tracy Cui
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, Pittsburgh, PA, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA
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3
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Fisher KM, Garner JP, Darian-Smith C. Chronic Adaptations in the Dorsal Horn Following a Cervical Spinal Cord Injury in Primates. J Neurosci 2024; 44:e0877232023. [PMID: 38233220 PMCID: PMC10860610 DOI: 10.1523/jneurosci.0877-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 11/21/2023] [Accepted: 12/01/2023] [Indexed: 01/19/2024] Open
Abstract
Spinal cord injury (SCI) is devastating, with limited treatment options and variable outcomes. Most in vivo SCI research has focused on the acute and early post-injury periods, and the promotion of axonal growth, so little is understood about the clinically stable chronic state, axonal growth over time, and what plasticity endures. Here, we followed animals into the chronic phase following SCI, to address this gap. Male macaques received targeted deafferentation, affecting three digits of one hand, and were divided into short (4-6 months) or long-term (11-12 months) groups, based on post-injury survival times. Monkeys were assessed behaviorally, where possible, and all exhibited an initial post-injury deficit in manual dexterity, with gradual functional recovery over 2 months. We previously reported extensive sprouting of somatosensory corticospinal (S1 CST) fibers in the dorsal horn in the first five post-injury months. Here, we show that by 1 year, the S1 CST sprouting is pruned, with the terminal territory resembling control animals. This was reflected in the number of putatively "functional" synapses observed, which increased over the first 4-5 months, and then returned to baseline by 1 year. Microglia density also increased in the affected dorsal horn at 4-6 months and then decreased, but did not return to baseline by 1 year, suggesting refinement continues beyond this time. Overall, there is a long period of reorganization and consolidation of adaptive circuitry in the dorsal horn, extending well beyond the initial behavioral recovery. This provides a potential window to target therapeutic opportunities during the chronic phase.
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Affiliation(s)
- Karen M Fisher
- Department of Comparative Medicine, Stanford University School of Medicine, Stanford 94305-5342, California
| | - Joseph P Garner
- Department of Comparative Medicine, Stanford University School of Medicine, Stanford 94305-5342, California
| | - Corinna Darian-Smith
- Department of Comparative Medicine, Stanford University School of Medicine, Stanford 94305-5342, California
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4
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Castro R, Lopes M, De Biase L, Valdez G. Aging spinal cord microglia become phenotypically heterogeneous and preferentially target motor neurons and their synapses. Glia 2024; 72:206-221. [PMID: 37737058 PMCID: PMC10773989 DOI: 10.1002/glia.24470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 08/07/2023] [Accepted: 09/03/2023] [Indexed: 09/23/2023]
Abstract
Microglia have been found to acquire unique region-dependent deleterious features with age and diseases that contribute to neuronal dysfunction and degeneration in the brain. However, it remains unknown whether microglia exhibit similar phenotypic heterogeneity in the spinal cord. Here, we performed a regional analysis of spinal cord microglia in 3-, 16-, 23-, and 30-month-old mice. Using light and electron microscopy, we discovered that spinal cord microglia acquire an increasingly activated phenotype during the course of aging regardless of regional location. However, aging causes microglia in the ventral but not dorsal horn to lose their spatial organization. Aged ventral horn microglia also aggregate around the somata of motor neurons and increase their contacts with motor synapses, which have been shown to be lost with age. These findings suggest that microglia may affect the ability of motor neurons to receive and relay motor commands during aging. To generate additional insights about aging spinal cord microglia, we performed RNA-sequencing on FACS-isolated microglia from 3-, 18-, 22-, and 29-month-old mice. We found that spinal cord microglia acquire a similar transcriptional identity as those in the brain during aging that includes altered expression of genes with roles in microglia-neuron interactions and inflammation. By 29 months of age, spinal cord microglia exhibit additional and unique transcriptional changes known and predicted to cause senescence and to alter lysosomal and ribosomal regulation. Altogether, this work provides the foundation to target microglia to ameliorate aged-related changes in the spinal cord, and particularly on the motor circuit.
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Affiliation(s)
- Ryan Castro
- Neuroscience Graduate Program, Brown University, Providence, Rhode Island, USA
| | - Mikayla Lopes
- Molecular Biology, Cell Biology & Biochemistry Graduate Program, Brown University, Providence, Rhode Island, USA
| | - Lindsay De Biase
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, USA
| | - Gregorio Valdez
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, USA
- Center for Translational Neuroscience, Robert J. and Nancy D. Carney Institute for Brain Science and Brown Institute for Translational Science, Brown University, Providence, Rhode Island, USA
- Department of Neurology, Warren Alpert Medical School of Medicine, Brown University, Providence, USA
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5
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Starinets A, Ponomarenko A, Tyrtyshnaia A, Manzhulo I. Synaptamide modulates glial and neurotransmitter activity in the spinal cord during neuropathic pain. J Chem Neuroanat 2023; 134:102361. [PMID: 37935251 DOI: 10.1016/j.jchemneu.2023.102361] [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: 09/11/2023] [Revised: 11/03/2023] [Accepted: 11/03/2023] [Indexed: 11/09/2023]
Abstract
N-docosahexaenoylethanolamine, or synaptamide, is an endogenous metabolite of docosahexaenoic acid that is known for synaptogenic and neurogenic effects. In our previous studies we have shown that synaptamide attenuates neuropathic pain, facilitates remyelination, and reduces neuroinflammation after the chronic constriction injury (CCI) of the sciatic nerve in rats. In the current study, we show that daily synaptamide administration (4 mg/kg/day) within 14 days post-surgery: (1) decreases micro- and astroglia activity in the dorsal and ventral horns of the lumbar spinal cord; (2) modulates pro-inflammatory (IL1β, IL6) and anti-inflammatory (IL4, IL10) cytokine level in the serum and spinal cord; (3) leads to a rise in synaptamide and anandamide concentration in the spinal cord; (4) enhances IL10, CD206 and N-acylethanolamine-hydrolyzing acid amidase synthesis in macrophage cell culture following LPS-induced inflammation. Thus, the ability of synaptamide to modulate glial and cytokine activity indicates its potential for implementation in the treatment peripheral nerve injury.
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Affiliation(s)
- Anna Starinets
- A.V. Zhirmunsky National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok 690041, Russia
| | - Arina Ponomarenko
- A.V. Zhirmunsky National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok 690041, Russia
| | - Anna Tyrtyshnaia
- A.V. Zhirmunsky National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok 690041, Russia
| | - Igor Manzhulo
- A.V. Zhirmunsky National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok 690041, Russia.
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6
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Arbat-Plana A, Bolívar S, Navarro X, Udina E, Alvarez FJ. Massive Loss of Proprioceptive Ia Synapses in Rat Spinal Motoneurons after Nerve Crush Injuries in the Postnatal Period. eNeuro 2023; 10:ENEURO.0436-22.2023. [PMID: 36759186 PMCID: PMC9948128 DOI: 10.1523/eneuro.0436-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 12/15/2022] [Accepted: 01/26/2023] [Indexed: 02/11/2023] Open
Abstract
Peripheral nerve injuries (PNIs) induce the retraction from the ventral horn of the synaptic collaterals of Ia afferents injured in the nerve, effectively removing Ia synapses from α-motoneurons. The loss of Ia input impairs functional recovery and could explain, in part, better recovery after PNIs with better Ia synaptic preservation. Synaptic losses correlate with injury severity, speed, and efficiency of muscle reinnervation and requires ventral microglia activation. It is unknown whether this plasticity is age dependent. In neonates, axotomized motoneurons and sensory neurons undergo apoptosis, but after postnatal day 10 most survive. The goal of this study was to analyze vesicular glutamate transporter 1 (VGluT1)-labeled Ia synapses (which also include II afferents) after nerve crush in 10 day old rats, a PNI causing little Ia/II synapse loss in adult rats. We confirmed fast and efficient reinnervation of leg muscles; however, a massive number of VGluT1/Ia/II synapses were permanently lost. This synapse loss was similar to that after more severe nerve injuries involving full transection in adults. In adults, disappearance of ventrally directed Ia/II collaterals targeting α-motoneurons was associated with a prolonged microglia reaction and a CCR2 mechanism that included infiltration of CCR2 blood immune cells. By contrast, microgliosis after P10 injuries was fast, resolved in about a week, and there was no evidence of peripheral immune cell infiltration. We conclude that VGluT1/Ia/II synapse loss in young animals differs in mechanism, perhaps associated with higher microglia synaptic pruning activity at this age and results in larger losses after milder nerve injuries.
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Affiliation(s)
- Ariadna Arbat-Plana
- Department of Cell Biology, Physiology and Immunology, Institute of Neurosciences, Universitat Autònoma de Barcelona, 08028 Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 08193 Bellaterra, Spain
- Department of Physiology, Emory University, Atlanta, Georgia 30322
| | - Sara Bolívar
- Department of Cell Biology, Physiology and Immunology, Institute of Neurosciences, Universitat Autònoma de Barcelona, 08028 Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 08193 Bellaterra, Spain
- Department of Physiology, Emory University, Atlanta, Georgia 30322
| | - Xavier Navarro
- Department of Cell Biology, Physiology and Immunology, Institute of Neurosciences, Universitat Autònoma de Barcelona, 08028 Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 08193 Bellaterra, Spain
| | - Esther Udina
- Department of Cell Biology, Physiology and Immunology, Institute of Neurosciences, Universitat Autònoma de Barcelona, 08028 Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 08193 Bellaterra, Spain
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7
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Zhang Y, Xu L, Li X, Chen Z, Chen J, Zhang T, Gu X, Yang J. Deciphering the dynamic niches and regeneration-associated transcriptional program of motoneurons following peripheral nerve injury. iScience 2022; 25:104917. [PMID: 36051182 PMCID: PMC9424597 DOI: 10.1016/j.isci.2022.104917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 07/10/2022] [Accepted: 08/08/2022] [Indexed: 11/25/2022] Open
Abstract
Robust axon regeneration of motoneurons (MNs) occurs in rodent models upon peripheral nerve injury (PNI). However, genome-wide dynamic molecules and permissive microenvironment following insult in MNs remain largely unknown. Here, we firstly tackled by high-coverage and massive sequencing of laser-dissected individual ChAT+ cells to uncover molecules and pro-regenerative programs of MNs from injury to the regenerating phase after PNI. "Injured" populations at 1d∼7d were well distinguished and three response phases were well defined by elucidating with several clues (Gap43, etc). We found remarkable changes of genes expressed by injured motoneurons to activate and enhance intrinsic axon regrowth or crosstalk with other cellular or non-cellular counterpart in the activated regenerative microenvironment, specifically microglia/macrophage. We also identified an injury and regeneration-associated module and critical regulators including core transcription factors (Atf3, Arid5a, Klf6, Klf7, Jun, Stat3, and Myc). This study provides a vital resource and critical molecules for studying neural repair of axotomized motoneurons.
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Affiliation(s)
- Yu Zhang
- School of Medicine and Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing 210000, China
| | - Lian Xu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Nantong University, Nantong 226001, China
| | - Xiaodi Li
- School of Medicine and Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing 210000, China
| | - Zhifeng Chen
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Nantong University, Nantong 226001, China
| | - Jing Chen
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Nantong University, Nantong 226001, China
| | - Tao Zhang
- School of Medicine and Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing 210000, China
| | - Xiaosong Gu
- School of Medicine and Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing 210000, China.,Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Nantong University, Nantong 226001, China
| | - Jian Yang
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Nantong University, Nantong 226001, China
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8
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Pottorf TS, Rotterman TM, McCallum WM, Haley-Johnson ZA, Alvarez FJ. The Role of Microglia in Neuroinflammation of the Spinal Cord after Peripheral Nerve Injury. Cells 2022; 11:cells11132083. [PMID: 35805167 PMCID: PMC9265514 DOI: 10.3390/cells11132083] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 06/26/2022] [Accepted: 06/27/2022] [Indexed: 12/12/2022] Open
Abstract
Peripheral nerve injuries induce a pronounced immune reaction within the spinal cord, largely governed by microglia activation in both the dorsal and ventral horns. The mechanisms of activation and response of microglia are diverse depending on the location within the spinal cord, type, severity, and proximity of injury, as well as the age and species of the organism. Thanks to recent advancements in neuro-immune research techniques, such as single-cell transcriptomics, novel genetic mouse models, and live imaging, a vast amount of literature has come to light regarding the mechanisms of microglial activation and alluding to the function of microgliosis around injured motoneurons and sensory afferents. Herein, we provide a comparative analysis of the dorsal and ventral horns in relation to mechanisms of microglia activation (CSF1, DAP12, CCR2, Fractalkine signaling, Toll-like receptors, and purinergic signaling), and functionality in neuroprotection, degeneration, regeneration, synaptic plasticity, and spinal circuit reorganization following peripheral nerve injury. This review aims to shed new light on unsettled controversies regarding the diversity of spinal microglial-neuronal interactions following injury.
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Affiliation(s)
- Tana S. Pottorf
- Department of Cell Biology, Emory University, Atlanta, GA 30322, USA; (T.S.P.); (W.M.M.); (Z.A.H.-J.)
| | - Travis M. Rotterman
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30318, USA;
| | - William M. McCallum
- Department of Cell Biology, Emory University, Atlanta, GA 30322, USA; (T.S.P.); (W.M.M.); (Z.A.H.-J.)
| | - Zoë A. Haley-Johnson
- Department of Cell Biology, Emory University, Atlanta, GA 30322, USA; (T.S.P.); (W.M.M.); (Z.A.H.-J.)
| | - Francisco J. Alvarez
- Department of Cell Biology, Emory University, Atlanta, GA 30322, USA; (T.S.P.); (W.M.M.); (Z.A.H.-J.)
- Correspondence:
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9
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Salvany S, Casanovas A, Piedrafita L, Gras S, Calderó J, Esquerda JE. Accumulation of misfolded SOD1 outlines distinct patterns of motor neuron pathology and death during disease progression in a SOD1 G93A mouse model of amyotrophic lateral sclerosis. Brain Pathol 2022; 32:e13078. [PMID: 35584812 PMCID: PMC9616096 DOI: 10.1111/bpa.13078] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 04/11/2022] [Indexed: 12/12/2022] Open
Abstract
Early misfolded superoxide dismutase 1 (mfSOD1) accumulation, motor neuron (MN) degeneration, and microgliosis are hallmark pathological features in SOD1G93A amyotrophic lateral sclerosis (ALS) mice. Because of the different vulnerabilities of distinct MN subtypes, degenerating and surviving MNs coexist in different proportions during disease progression. By examining the expression of misfolded conformers of SOD1 using specific antibodies, we defined distinct MN phenotypes that were evaluated during disease progression and the local neuroinflammatory reaction. The most severe phenotype corresponded to somata of fast‐twitch subtype MNs, which exhibited highly positive mfSOD1 immunostaining and an extreme degree of vacuolar degeneration. Vacuoles, which are of mitochondrial origin, contain mfSOD1 in conjunction with nonmitochondrial proteins, such as chromogranin, CD81, and flotillin. The fusion of ER‐derived vesicles enriched in mfSOD1 with outer mitochondrial membranes is thought to be the primary mechanism for vacuole formation. In addition, the ulterior coalescence of enlarged mitochondria may lead to the formation of giant vacuoles. Vacuolar degeneration is a transient degenerative process occurring early during the presymptomatic stages of the disease in ALS mice. Some vacuolated MNs are also positive for pMLKL, the effector protein of necroptosis. This indicates a newly described mechanism in which extracellular vesicles derived from damaged MNs, via cellular secretion or necroptotic disruption, may be the triggers for initiating neuroinflammation, glial‐mediated neurotoxicity, and disease spreading. Furthermore, as MN degeneration in mutant SOD1 mice is noncell autonomous, the effects of experimentally increasing or decreasing the microglial response on the expression of MN phenotypes were also evaluated, demonstrating bidirectional cross talk signaling between the degree of expression of mfSOD1 and local neuroinflammation. More detailed knowledge regarding these processes occurring long before the end stages of the disease is necessary to identify novel molecular targets for future preclinical testing.
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Affiliation(s)
- Sara Salvany
- Patologia Neuromuscular Experimental, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida and Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Catalonia, Spain
| | - Anna Casanovas
- Patologia Neuromuscular Experimental, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida and Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Catalonia, Spain
| | - Lídia Piedrafita
- Patologia Neuromuscular Experimental, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida and Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Catalonia, Spain
| | - Sílvia Gras
- Patologia Neuromuscular Experimental, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida and Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Catalonia, Spain
| | - Jordi Calderó
- Patologia Neuromuscular Experimental, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida and Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Catalonia, Spain
| | - Josep E Esquerda
- Patologia Neuromuscular Experimental, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida and Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Catalonia, Spain
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10
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Molnár K, Nógrádi B, Kristóf R, Mészáros Á, Pajer K, Siklós L, Nógrádi A, Wilhelm I, Krizbai IA. Motoneuronal inflammasome activation triggers excessive neuroinflammation and impedes regeneration after sciatic nerve injury. J Neuroinflammation 2022; 19:68. [PMID: 35305649 PMCID: PMC8934511 DOI: 10.1186/s12974-022-02427-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 03/01/2022] [Indexed: 12/12/2022] Open
Abstract
Background Peripheral nerve injuries are accompanied by inflammatory reactions, over-activation of which may hinder recovery. Among pro-inflammatory pathways, inflammasomes are one of the most potent, leading to release of active IL-1β. Our aim was to understand how inflammasomes participate in central inflammatory reactions accompanying peripheral nerve injury. Methods After axotomy of the sciatic nerve, priming and activation of the NLRP3 inflammasome was examined in cells of the spinal cord. Regeneration of the nerve was evaluated after coaptation using sciatic functional index measurements and retrograde tracing. Results In the first 3 days after the injury, elements of the NLRP3 inflammasome were markedly upregulated in the L4–L5 segments of the spinal cord, followed by assembly of the inflammasome and secretion of active IL-1β. Although glial cells are traditionally viewed as initiators of neuroinflammation, in this acute phase of inflammation, inflammasome activation was found exclusively in affected motoneurons of the ventral horn in our model. This process was significantly inhibited by 5-BDBD, a P2X4 receptor inhibitor and MCC950, a potent NLRP3 inhibitor. Although at later time points the NLRP3 protein was upregulated in microglia too, no signs of inflammasome activation were detected in these cells. Inhibition of inflammasome activation in motoneurons in the first days after nerve injury hindered development of microgliosis in the spinal cord. Moreover, P2X4 or inflammasome inhibition in the acute phase significantly enhanced nerve regeneration on both the morphological and the functional levels. Conclusions Our results indicate that the central reaction initiated by sciatic nerve injury starts with inflammasome activation in motoneurons of the ventral horn, which triggers a complex inflammatory reaction and activation of microglia. Inhibition of neuronal inflammasome activation not only leads to a significant reduction of microgliosis, but has a beneficial effect on the recovery as well. Supplementary Information The online version contains supplementary material available at 10.1186/s12974-022-02427-9.
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Affiliation(s)
- Kinga Molnár
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network (ELKH), Temesvári krt. 62, 6726, Szeged, Hungary
| | - Bernát Nógrádi
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network (ELKH), Temesvári krt. 62, 6726, Szeged, Hungary.,Theoretical Medicine Doctoral School, University of Szeged, Szeged, Hungary.,Department of Neurology, University of Szeged, Szeged, Hungary
| | - Rebeka Kristóf
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network (ELKH), Temesvári krt. 62, 6726, Szeged, Hungary.,Theoretical Medicine Doctoral School, University of Szeged, Szeged, Hungary
| | - Ádám Mészáros
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network (ELKH), Temesvári krt. 62, 6726, Szeged, Hungary.,Doctoral School of Biology, University of Szeged, Szeged, Hungary
| | - Krisztián Pajer
- Department of Anatomy, Histology and Embryology, University of Szeged, Szeged, Hungary
| | - László Siklós
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network (ELKH), Temesvári krt. 62, 6726, Szeged, Hungary
| | - Antal Nógrádi
- Department of Anatomy, Histology and Embryology, University of Szeged, Szeged, Hungary
| | - Imola Wilhelm
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network (ELKH), Temesvári krt. 62, 6726, Szeged, Hungary. .,Institute of Life Sciences, Vasile Goldiş Western University of Arad, Arad, Romania.
| | - István A Krizbai
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network (ELKH), Temesvári krt. 62, 6726, Szeged, Hungary. .,Institute of Life Sciences, Vasile Goldiş Western University of Arad, Arad, Romania.
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11
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Cartarozzi LP, Perez M, Fernandes GG, Chiarotto GB, Luzo ÂCM, Campos AC, Kirchhoff F, de Oliveira ALR. Neuroprotection and gliosis attenuation by intravenous application of human mesenchymal stem cells (hMSC) following ventral root crush in mice. Mol Cell Neurosci 2021; 118:103694. [PMID: 34954382 DOI: 10.1016/j.mcn.2021.103694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 12/13/2021] [Accepted: 12/17/2021] [Indexed: 11/15/2022] Open
Abstract
Rupture and stretching of spinal roots are common incidents that take place in high-energy accidents. The proximal axotomy of motoneurons by crushing of ventral roots is directly related to the degeneration of half of the lesioned population within the first two weeks. Moreover, only a small percentage of surviving motoneurons can successfully achieve regeneration after such a proximal lesion, and new treatments are necessary to improve this scenario. In this sense, mesenchymal stem cells (MSC) are of great interest once they secrete a broad spectrum of bioactive molecules that are immunomodulatory and can restore the environment after a lesion. The present work aimed at studying the effects of human mesenchymal stem cells (hMSC) therapy after ventral root crush (VRC) in mice. We evaluated motoneuron survival, glial reaction, and synapse preservation at the ventral horn. For this purpose, C57BL/6 J were submitted to a crush procedure of L4 to L6 ventral roots and treated with a single intravenous injection of adipose-derived hMSC. Evaluation of the results was carried out at 7, 14, and 28 days after injury. Analysis of motoneuron survival and astrogliosis showed that hMSC treatment resulted in higher motoneuron preservation (motoneuron survival ipsi/contralateral ratio: VRC group = 53%, VRC + hMSC group = 66%; p < 0.01), combined with reduction of astrogliosis (ipsi/contralateral GFAP immunolabeling: VRC group = 470%, VRC + hMSC group = 250%; p < 0.001). The morphological classification and Sholl analysis of microglial activation revealed that hMSC treatment reduced type V and increased type II profiles, indicating an enhancement of surveying over activated microglial cells. The glial reactivity modulation directly influenced synaptic inputs in apposition to axotomized motoneurons. In the hMSC-treated group, synaptic maintenance was increased (ipsi/contralateral synaptophysin immunolabeling: VRC group = 53%, VRC + hMSC group = 64%; p < 0.05). Overall, the present data show that intravenous injection of hMSC has neuroprotective and anti-inflammatory effects, decreasing reactive astrogliosis, and microglial reaction. Also, such cell therapy results in motoneuron preservation, combined with significant maintenance of spinal cord circuits, in particular those related to the ventral horn.
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Affiliation(s)
- Luciana Politti Cartarozzi
- Laboratory of Nerve Regeneration, University of Campinas - UNICAMP, Cidade Universitaria "Zeferino Vaz", Rua Monteiro Lobato, 255, 13083-970 Campinas, SP, Brazil
| | - Matheus Perez
- School of Physical Education and Sport of Ribeirão Preto, University of São Paulo, Av. Bandeirantes, 3900, 14040-907 Ribeirão Preto, SP, Brazil
| | - Gabriel Gripp Fernandes
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Av. Bandeirantes, 3900, 14040-907 Ribeirão Preto, SP, Brazil
| | - Gabriela Bortolança Chiarotto
- Laboratory of Nerve Regeneration, University of Campinas - UNICAMP, Cidade Universitaria "Zeferino Vaz", Rua Monteiro Lobato, 255, 13083-970 Campinas, SP, Brazil
| | - Ângela Cristina Malgeiros Luzo
- Hematology and Hemotherapy Center, University of Campinas/Hemocentro-Unicamp, Instituto Nacional de Ciência e Tecnologia do Sangue, Campinas, São Paulo, Brazil
| | - Alline Cristina Campos
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Av. Bandeirantes, 3900, 14040-907 Ribeirão Preto, SP, Brazil
| | - Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Building 48, 66421 Homburg, Germany
| | - Alexandre Leite Rodrigues de Oliveira
- Laboratory of Nerve Regeneration, University of Campinas - UNICAMP, Cidade Universitaria "Zeferino Vaz", Rua Monteiro Lobato, 255, 13083-970 Campinas, SP, Brazil.
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12
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Dyne E, Cawood M, Suzelis M, Russell R, Kim MH. Ultrastructural analysis of the morphological phenotypes of microglia associated with neuroinflammatory cues. J Comp Neurol 2021; 530:1263-1275. [PMID: 34773250 DOI: 10.1002/cne.25274] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 11/04/2021] [Accepted: 11/05/2021] [Indexed: 12/15/2022]
Abstract
Microglia are the primary resident immune cells of the central nervous system that are responsible for the maintenance of brain homeostasis. There is a plethora of evidence to suggest that microglia display distinct phenotypes that are associated with the alteration of cell morphology under varying environmental cues. However, it has not been fully explored how the varying states of microglial activation are linked to the alteration of microglia morphology, especially in the microdomain. The objective of this study was to quantitatively characterize the ultrastructural morphology of human microglia under neuroinflammatory cues. To address this, a human cell line of microglia was stimulated by antiinflammatory (IL-4), proinflammatory (TNF-α), and Alzheimer's disease (AD)-associated cues (Aβ, Aβ + TNF-α). The resulting effects on microglia morphology associated with changes in microdomain were analyzed using a high-resolution scanning electron microscopy. Our findings demonstrated that microglial activation under proinflammatory and AD-cues were closely linked to changes not only in cell shape but also in cell surface topography and higher-order branching of processes. Furthermore, our results revealed that microglia under proinflammatory cues exhibited unique morphological features involving cell-to-cell contact and the formation of vesicle-like structures. Our study provides insight into the fine details of microglia morphology associated with varying status of microglial activation.
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Affiliation(s)
- Eric Dyne
- School of Biomedical Sciences, Kent State University, Kent, Ohio, USA
| | - Meghan Cawood
- Department of Biological Sciences, Kent State University, Kent, Ohio, USA
| | - Matthew Suzelis
- Department of Biological Sciences, Kent State University, Kent, Ohio, USA
| | - Reagan Russell
- Department of Biological Sciences, Kent State University, Kent, Ohio, USA
| | - Min-Ho Kim
- School of Biomedical Sciences, Kent State University, Kent, Ohio, USA.,Department of Biological Sciences, Kent State University, Kent, Ohio, USA
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13
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Krukowski K, Nolan A, Becker M, Picard K, Vernoux N, Frias ES, Feng X, Tremblay ME, Rosi S. Novel microglia-mediated mechanisms underlying synaptic loss and cognitive impairment after traumatic brain injury. Brain Behav Immun 2021; 98:122-135. [PMID: 34403733 PMCID: PMC9119574 DOI: 10.1016/j.bbi.2021.08.210] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 08/03/2021] [Accepted: 08/06/2021] [Indexed: 12/30/2022] Open
Abstract
Traumatic brain injury (TBI) is one of the leading causes of long-term neurological disability in the world. Currently, there are no therapeutics for treating the deleterious consequences of brain trauma; this is in part due to a lack of complete understanding of cellular processes that underlie TBI-related pathologies. Following TBI, microglia, the brain resident immune cells, turn into a "reactive" state characterized by the production of inflammatory mediators that contribute to the development of cognitive deficits. Utilizing multimodal, state-of-the-art techniques that widely span from ultrastructural analysis to optogenetic interrogation of circuit function, we investigated the reactive microglia phenotype one week after injury when learning and memory deficits are also measured. Microglia displayed increased: (i) phagocytic activity in vivo, (ii) synaptic engulfment, (iii) increased neuronal contact, including with dendrites and somata (termed 'satellite microglia'). Functionally, satellite microglia might impact somatic inhibition as demonstrated by the associated reduction in inhibitory synaptic drive. Cumulatively, here we demonstrate novel microglia-mediated mechanisms that may contribute to synaptic loss and cognitive impairment after traumatic brain injury.
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Affiliation(s)
- Karen Krukowski
- Department of Physical Therapy and Rehabilitation Science, University of California, San Francisco, CA, USA, Brain and Spinal Injury Center, University of California, San Francisco, CA, USA
| | - Amber Nolan
- Department of Physical Therapy and Rehabilitation Science, University of California, San Francisco, CA, USA, Brain and Spinal Injury Center, University of California, San Francisco, CA, USA
| | - McKenna Becker
- Department of Physical Therapy and Rehabilitation Science, University of California, San Francisco, CA, USA, Brain and Spinal Injury Center, University of California, San Francisco, CA, USA
| | - Katherine Picard
- Axe Neurosciences, CRCHU de Québec-Université Laval, Québec, QC, Canada
| | - Nathalie Vernoux
- Axe Neurosciences, CRCHU de Québec-Université Laval, Québec, QC, Canada
| | - Elma S. Frias
- Department of Physical Therapy and Rehabilitation Science, University of California, San Francisco, CA, USA, Brain and Spinal Injury Center, University of California, San Francisco, CA, USA, Department of Biomedical Sciences, University of California, San Francisco, CA, USA
| | - Xi Feng
- Department of Physical Therapy and Rehabilitation Science, University of California, San Francisco, CA, USA, Brain and Spinal Injury Center, University of California, San Francisco, CA, USA
| | - Marie-Eve Tremblay
- Axe Neurosciences, CRCHU de Québec-Université Laval, Québec, QC, Canada; Molecular Medicine Department, Université Laval, Québec, QC, Canada; Division of Medical Sciences, University of Victoria, Victoria, BC, Canada; Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, BC, Canada.
| | - Susanna Rosi
- Department of Physical Therapy and Rehabilitation Science, University of California, San Francisco, CA, USA; Brain and Spinal Injury Center, University of California, San Francisco, CA, USA; Department of Biomedical Sciences, University of California, San Francisco, CA, USA; Department of Neurological Surgery, University of California, San Francisco, CA, USA; Weill Institute for Neuroscience, University of California San Francisco, CA, USA; Kavli Institute of Fundamental Neuroscience, University of California San Francisco, CA, USA.
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14
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Gras S, Blasco A, Mòdol-Caballero G, Tarabal O, Casanovas A, Piedrafita L, Barranco A, Das T, Rueda R, Pereira SL, Navarro X, Esquerda JE, Calderó J. Beneficial effects of dietary supplementation with green tea catechins and cocoa flavanols on aging-related regressive changes in the mouse neuromuscular system. Aging (Albany NY) 2021; 13:18051-18093. [PMID: 34319911 PMCID: PMC8351677 DOI: 10.18632/aging.203336] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 06/19/2021] [Indexed: 12/17/2022]
Abstract
Besides skeletal muscle wasting, sarcopenia entails morphological and molecular changes in distinct components of the neuromuscular system, including spinal cord motoneurons (MNs) and neuromuscular junctions (NMJs); moreover, noticeable microgliosis has also been observed around aged MNs. Here we examined the impact of two flavonoid-enriched diets containing either green tea extract (GTE) catechins or cocoa flavanols on age-associated regressive changes in the neuromuscular system of C57BL/6J mice. Compared to control mice, GTE- and cocoa-supplementation significantly improved the survival rate of mice, reduced the proportion of fibers with lipofuscin aggregates and central nuclei, and increased the density of satellite cells in skeletal muscles. Additionally, both supplements significantly augmented the number of innervated NMJs and their degree of maturity compared to controls. GTE, but not cocoa, prominently increased the density of VAChT and VGluT2 afferent synapses on MNs, which were lost in control aged spinal cords; conversely, cocoa, but not GTE, significantly augmented the proportion of VGluT1 afferent synapses on aged MNs. Moreover, GTE, but not cocoa, reduced aging-associated microgliosis and increased the proportion of neuroprotective microglial phenotypes. Our data indicate that certain plant flavonoids may be beneficial in the nutritional management of age-related deterioration of the neuromuscular system.
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Affiliation(s)
- Sílvia Gras
- Unitat de Neurobiologia Cel·lular, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida and Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Spain
| | - Alba Blasco
- Unitat de Neurobiologia Cel·lular, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida and Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Spain
| | - Guillem Mòdol-Caballero
- Grup de Neuroplasticitat i Regeneració, Institut de Neurociències, Departament de Biologia Cellular, Fisiologia i Immunologia, Universitat Autònoma de Barcelona and CIBERNED, Bellaterra, Spain
| | - Olga Tarabal
- Unitat de Neurobiologia Cel·lular, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida and Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Spain
| | - Anna Casanovas
- Unitat de Neurobiologia Cel·lular, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida and Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Spain
| | - Lídia Piedrafita
- Unitat de Neurobiologia Cel·lular, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida and Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Spain
| | - Alejandro Barranco
- Department of Biochemistry and Molecular Biology II, School of Pharmacy, University of Granada, Granada, Spain
| | - Tapas Das
- Abbott Nutrition, Research and Development, Columbus, OH 43215, USA
| | - Ricardo Rueda
- Abbott Nutrition, Research and Development, Granada, Spain
| | | | - Xavier Navarro
- Grup de Neuroplasticitat i Regeneració, Institut de Neurociències, Departament de Biologia Cellular, Fisiologia i Immunologia, Universitat Autònoma de Barcelona and CIBERNED, Bellaterra, Spain
| | - Josep E. Esquerda
- Unitat de Neurobiologia Cel·lular, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida and Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Spain
| | - Jordi Calderó
- Unitat de Neurobiologia Cel·lular, Departament de Medicina Experimental, Facultat de Medicina, Universitat de Lleida and Institut de Recerca Biomèdica de Lleida (IRBLleida), Lleida, Spain
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15
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Campos RM, Barbosa-Silva MC, Ribeiro-Resende VT. Comparison of effect of crush or transection peripheral nerve lesion on lumbar spinal cord synaptic plasticity and microglial dynamics. IBRO Neurosci Rep 2021; 10:225-235. [PMID: 34179871 PMCID: PMC8211924 DOI: 10.1016/j.ibneur.2021.05.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 05/10/2021] [Accepted: 05/12/2021] [Indexed: 11/22/2022] Open
Abstract
In an injury to the peripheral nervous system, the spinal cord and brain structure reorganize connections to optimize the function of the remaining parts. Many cell events are triggered in the spinal cord to support changes in the synaptic connections around motoneurons, where old connections are removed, and new ones created. Microglial cells are primitive macrophages that invade the central nervous system in early stages of neurodevelopment and have several functions, such as eliminating synapses. We investigated the synaptic plasticity after different types of peripheral (sciatic) nerve injury (crush or total transection), as well as the behavior of microglial cells for 2 weeks after a peripheral lesion. As expected, sciatic-nerve injury reduced motor performance in mice, but crushed animals regained partial motor control. Because of sciatic-nerve injury, pre-synaptic inputs decreased around the motoneurons in the ventro-lateral horn, while microglial cells increased around these cells. Microglial cells also exhibited altered morphology in both types of peripheral lesion, indicating a similar underlying mechanism of plasticity. To investigate the involvement of microglia in this scenario, microglial activation was modulated by daily administration of minocycline. The minocycline treatment directly affected the microglial response and impacted the synapse rearrangement in the spinal cord. Together, these results demonstrate that microglia cells are involved in synaptic plasticity in the lumbar spinal cord in both nerve-injury scenarios. SUMMARY OF STATEMENT Here, we demonstrated that acute plasticity in the lumbar spinal cord (LSC) did not differ between crush and transection of peripheral nerve, and that microglial reactivity in the LSC was important after both injury types.
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Affiliation(s)
- Raquel M.P. Campos
- Instituto de Biofísica Carlos Chagas Filho, Laboratório de Neuroquímica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil
| | - Maria Carolina Barbosa-Silva
- Instituto de Biofísica Carlos Chagas Filho, Laboratório de Neuroquímica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil
| | - Victor T. Ribeiro-Resende
- Instituto de Biofísica Carlos Chagas Filho, Laboratório de Neuroquímica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil
- Núcleo Multidisciplinar de Pesquisa em Biologia (Numpex-Bio), Campus de Duque de Caxias Geraldo Guerra Cidade, Universidade Federal do Rio de Janeiro, Duque de Caxias, RJ 25255-030, Brazil
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16
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Andoh M, Koyama R. Assessing Microglial Dynamics by Live Imaging. Front Immunol 2021; 12:617564. [PMID: 33763064 PMCID: PMC7982483 DOI: 10.3389/fimmu.2021.617564] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 02/16/2021] [Indexed: 12/13/2022] Open
Abstract
Microglia are highly dynamic in the brain in terms of their ability to migrate, proliferate, and phagocytose over the course of an individual's life. Real-time imaging is a useful tool to examine how microglial behavior is regulated and how it affects the surrounding environment. However, microglia are sensitive to environmental stimuli, so they possibly change their state during live imaging in vivo, mainly due to surgical damage, and in vitro due to various effects associated with culture conditions. Therefore, it is difficult to perform live imaging without compromising the properties of the microglia under physiological conditions. To overcome this barrier, various experimental conditions have been developed; recently, it has become possible to perform live imaging of so-called surveillant microglia in vivo, ex vivo, and in vitro, although there are various limitations. Now, we can choose in vivo, ex vivo, or in vitro live imaging systems according to the research objective. In this review, we discuss the advantages and disadvantages of each experimental system and outline the physiological significance and molecular mechanisms of microglial behavior that have been elucidated by live imaging.
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Affiliation(s)
- Megumi Andoh
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Ryuta Koyama
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
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17
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Abstract
The muscle spindle is an important sense organ for motor control and proprioception. Specialized intrafusal fibers are innervated by both stretch sensitive afferents and γ motor neurons that control the length of the spindle and tune the sensitivity of the muscle spindle afferents to both dynamic movement and static length. γ motor neurons share many similarities with other skeletal motor neurons, making it challenging to identify and specifically record or stimulate them. This short review will discuss recent advances in genetic and molecular biology techniques, electrophysiological recording, optical imaging, computer modelling, and stem cell culture techniques that have the potential to help answer important questions about fusimotor function in motor control and disease.
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18
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Nógrádi B, Nyúl-Tóth Á, Kozma M, Molnár K, Patai R, Siklós L, Wilhelm I, Krizbai IA. Upregulation of Nucleotide-Binding Oligomerization Domain-, LRR- and Pyrin Domain-Containing Protein 3 in Motoneurons Following Peripheral Nerve Injury in Mice. Front Pharmacol 2020; 11:584184. [PMID: 33328988 PMCID: PMC7732612 DOI: 10.3389/fphar.2020.584184] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 10/21/2020] [Indexed: 12/17/2022] Open
Abstract
Neuronal injuries are accompanied by release and accumulation of damage-associated molecules, which in turn may contribute to activation of the immune system. Since a wide range of danger signals (including endogenous ones) are detected by the nucleotide-binding oligomerization domain-, LRR- and pyrin domain-containing protein 3 (NLRP3) pattern recognition receptor, we hypothesized that NLRP3 may become activated in response to motor neuron injury. Here we show that peripheral injury of the oculomotor and the hypoglossal nerves results in upregulation of NLRP3 in corresponding motor nuclei in the brainstem of mice. Although basal expression of NLRP3 was observed in microglia, astroglia and neurons as well, its upregulation and co-localization with apoptosis-associated speck-like protein containing a caspase activation and recruitment domain, suggesting inflammasome activation, was only detected in neurons. Consequently, increased production of active pro-inflammatory cytokines interleukin-1β and interleukin-18 were detected after hypoglossal nerve axotomy. Injury-sensitive hypoglossal neurons responded with a more pronounced NLRP3 upregulation than injury-resistant motor neurons of the oculomotor nucleus. We further demonstrated that the mitochondrial protector diazoxide was able to reduce NLRP3 upregulation in a post-operative treatment paradigm. Our results indicate that NLRP3 is activated in motoneurons following acute nerve injury. Blockade of NLRP3 activation might contribute to the previously observed anti-inflammatory and neuroprotective effects of diazoxide.
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Affiliation(s)
- Bernát Nógrádi
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary.,Foundation for the Future of Biomedical Sciences in Szeged, Szeged Scientists Academy, Szeged, Hungary
| | - Ádám Nyúl-Tóth
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary.,Department of Biochemistry and Molecular Biology, Vascular Cognitive Impairment and Neurodegeneration Program, Reynolds Oklahoma Center on Aging/Oklahoma Center for Geroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Mihály Kozma
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary.,Theoretical Medicine Doctoral School, University of Szeged, Szeged, Hungary
| | - Kinga Molnár
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary.,Theoretical Medicine Doctoral School, University of Szeged, Szeged, Hungary
| | - Roland Patai
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
| | - László Siklós
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
| | - Imola Wilhelm
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary.,Institute of Life Sciences, Vasile Goldiş Western University of Arad, Arad, Romania
| | - István A Krizbai
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary.,Institute of Life Sciences, Vasile Goldiş Western University of Arad, Arad, Romania
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