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Herman J, Rittenhouse N, Mandino F, Majid M, Wang Y, Mezger A, Kump A, Kadian S, Lake EMR, Verardi PH, Conover JC. Ventricular-subventricular zone stem cell niche adaptations in a mouse model of post-infectious hydrocephalus. Front Neurosci 2024; 18:1429829. [PMID: 39145299 PMCID: PMC11322059 DOI: 10.3389/fnins.2024.1429829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2024] [Accepted: 07/02/2024] [Indexed: 08/16/2024] Open
Abstract
Congenital post-infectious hydrocephalus (PIH) is a condition characterized by enlargement of the ventricular system, consequently imposing a burden on the associated stem cell niche, the ventricular-subventricular zone (V-SVZ). To investigate how the V-SVZ adapts in PIH, we developed a mouse model of influenza virus-induced PIH based on direct intracerebroventricular injection of mouse-adapted influenza virus at two distinct time points: embryonic day 16 (E16), when stem cells line the ventricle, and postnatal day 4 (P4), when an ependymal monolayer covers the ventricle surface and stem cells retain only a thin ventricle-contacting process. Global hydrocephalus with associated regions of astrogliosis along the lateral ventricle was found in 82% of the mice infected at P4. Increased ependymogenesis was observed at gliotic borders and throughout areas exhibiting intact ependyma based on tracking of newly divided cells. Additionally, in areas of intact ependyma, stem cell numbers were reduced; however, we found no significant reduction in new neurons reaching the olfactory bulb following onset of ventriculomegaly. At P4, injection of only the non-infectious viral component neuraminidase resulted in limited, region-specific ventriculomegaly due to absence of cell-to-cell transmission. In contrast, at E16 intracerebroventricular injection of influenza virus resulted in death at birth due to hypoxia and multiorgan hemorrhage, suggesting an age-dependent advantage in neonates, while the viral component neuraminidase resulted in minimal, or no, ventriculomegaly. In summary, we tracked acute adaptations of the V-SVZ stem cell niche following onset of ventriculomegaly and describe developmental changes that help mitigate the severity of congenital PIH.
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Affiliation(s)
- Julianna Herman
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
| | - Nicole Rittenhouse
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
| | - Francesca Mandino
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, United States
| | - Mushirah Majid
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
| | - Yuxiang Wang
- Department of Pathobiology and Veterinary Science, University of Connecticut, Storrs, CT, United States
| | - Amelia Mezger
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
| | - Aidan Kump
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
| | - Sumeet Kadian
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
| | - Evelyn M. R. Lake
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, United States
- Department of Biomedical Engineering, Yale University, New Haven, CT, United States
- Wu Tsai Institute, Yale University, New Haven, CT, United States
| | - Paulo H. Verardi
- Department of Pathobiology and Veterinary Science, University of Connecticut, Storrs, CT, United States
| | - Joanne C. Conover
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
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Visser VL, Caçoilo A, Rusinek H, Weickenmeier J. Mechanical loading of the ventricular wall as a spatial indicator for periventricular white matter degeneration. J Mech Behav Biomed Mater 2023; 143:105921. [PMID: 37269602 PMCID: PMC10266836 DOI: 10.1016/j.jmbbm.2023.105921] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 05/15/2023] [Accepted: 05/18/2023] [Indexed: 06/05/2023]
Abstract
Progressive white matter degeneration in periventricular and deep white matter regions appears as white matter hyperintensities (WMH) on MRI scans. To date, periventricular WMHs are often associated with vascular dysfunction. Here, we demonstrate that ventricular inflation resulting from cerebral atrophy and hemodynamic pulsation with every heartbeat leads to a mechanical loading state of periventricular tissues that significantly affects the ventricular wall. Specifically, we present a physics-based modeling approach that provides a rationale for ependymal cell involvement in periventricular WMH formation. Building on eight previously created 2D finite element brain models, we introduce novel mechanomarkers for ependymal cell loading and geometric measures that characterize lateral ventricular shape. We show that our novel mechanomarkers, such as maximum ependymal cell deformations and maximum curvature of the ventricular wall, spatially overlap with periventricular WMH locations and are sensitive predictors for WMH formation. We also explore the role of the septum pellucidum in mitigating mechanical loading of the ventricular wall by constraining the radial expansion of the lateral ventricles during loading. Our models consistently show that ependymal cells are stretched thin only in the horns of the ventricles irrespective of ventricular shape. We therefore pose that periventricular WMH etiology is strongly linked to the deterioration of the over-stretched ventricular wall resulting in CSF leakage into periventricular white matter. Subsequent secondary damage mechanisms, including vascular degeneration, exacerbate lesion formation and lead to progressive growth into deep white matter regions.
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Affiliation(s)
- Valery L Visser
- Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, United States of America; Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
| | - Andreia Caçoilo
- Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, United States of America
| | - Henry Rusinek
- Department of Radiology, New York University Grossman School of Medicine, New York, NY 10016, United States of America
| | - Johannes Weickenmeier
- Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, United States of America.
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Caçoilo A, Rusinek H, Weickenmeier J. 3D finite-element brain modeling of lateral ventricular wall loading to rationalize periventricular white matter hyperintensity locations. ENGINEERING WITH COMPUTERS 2022; 38:3939-3955. [PMID: 37485473 PMCID: PMC10361695 DOI: 10.1007/s00366-022-01700-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 06/19/2022] [Indexed: 07/25/2023]
Abstract
Aging-related periventricular white matter hyperintensities (pvWMHs) are a common observation in medical images of the aging brain. The underlying tissue damage is part of the complex pathophysiology associated with age-related microstructural changes and cognitive decline. PvWMH formation is linked to blood-brain barrier dysfunction from cerebral small vessel disease as well as the accumulation of cerebrospinal fluid in periventricular tissue due to progressive denudation of the ventricular wall. In need of a unifying theory for pvWMH etiology, image-based finite-element modeling is used to demonstrate that ventricular expansion from age-related cerebral atrophy and hemodynamic loading leads to maximum mechanical loading of the ventricular wall in the same locations that show pvWMHs. Ventricular inflation, induced via pressurization of the ventricular wall, creates significant ventricular wall stretch and stress on the ependymal cells lining the wall, that are linked to cerebrospinal fluid leaking from the lateral ventricles into periventricular white matter tissue. Eight anatomically accurate 3D brain models of cognitively healthy subjects with a wide range of ventricular shapes are created. For all models, our simulations show that mechanomarkers of mechanical wall loading are consistently highest in pvWMHs locations (p < 0.05). Maximum principal strain, the ependymal cell thinning ratio, and wall curvature are on average 14%, 8%, and 24% higher in pvWMH regions compared to the remaining ventricular wall, respectively. Computational modeling provides a powerful framework to systematically study pvWMH formation and growth with the goal to develop pharmacological interventions in the future.
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Affiliation(s)
- Andreia Caçoilo
- Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, USA
| | - Henry Rusinek
- Department of Radiology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Johannes Weickenmeier
- Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, USA
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Anxiety-like behavior and microglial activation in the amygdala after acute neuroinflammation induced by microbial neuraminidase. Sci Rep 2022; 12:11581. [PMID: 35803999 PMCID: PMC9270343 DOI: 10.1038/s41598-022-15617-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Accepted: 06/27/2022] [Indexed: 11/08/2022] Open
Abstract
Short-term behavioral alterations are associated with infection and aid the recovery from sickness. However, concerns have raised that sustained behavioral disturbances after acute neuroinflammation could relate to neurological diseases in the long run. We aimed to explore medium- and long-term behavioral disturbances after acute neuroinflammation in rats, using a model based on the intracerebroventricular administration of the enzyme neuraminidase (NA), which is part of some pathogenic bacteria and viruses. Neurological and behavioral assessments were performed 2 and 10 weeks after the injection of NA, and neuroinflammation was evaluated by gene expression and histology. No alterations were observed regarding basic neurological functions or locomotor capacity in NA-injected rats. However, they showed a reduction in unsupported rearing, and increased grooming and freezing behaviors, which indicate anxiety-like behavior. A principal component analysis including a larger set of parameters further supported such anxiety-like behavior. The anxiety profile was observed 2 weeks after NA-injection, but not after 10 weeks. Concomitantly, the amygdala presented increased number of microglial cells showing a morphologic bias towards an activated state. A similar but subtler tendency was observed in hypothalamic microglia located in the paraventricular nucleus. Also, in the hypothalamus the pattern recognition receptor toll-like receptor 4 (TLR4) was slightly overexpressed 2 weeks after NA injection. These results demonstrate that NA-induced neuroinflammation provokes anxiety-like behavior in the medium term, which disappears with time. Concurrent microgliosis in the amygdala could explain such behavior. Further experiments should aim to explore subtle but long-lasting alterations observed 10 weeks after NA injection, both in amygdala and hypothalamus, as well as mild behavioral changes.
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Fernández‐Arjona MDM, León‐Rodríguez A, Grondona JM, López‐Ávalos MD. Long-term priming of hypothalamic microglia is associated with energy balance disturbances under diet-induced obesity. Glia 2022; 70:1734-1761. [PMID: 35603807 PMCID: PMC9540536 DOI: 10.1002/glia.24217] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 04/13/2022] [Accepted: 05/06/2022] [Indexed: 12/16/2022]
Abstract
Exposure of microglia to an inflammatory environment may lead to their priming and exacerbated response to future inflammatory stimuli. Here we aimed to explore hypothalamic microglia priming and its consequences on energy balance regulation. A model of intracerebroventricular administration of neuraminidase (NA, which is present in various pathogens such as influenza virus) was used to induce acute neuroinflammation. Evidences of primed microglia were observed 3 months after NA injection, namely (1) a heightened response of microglia located in the hypothalamic arcuate nucleus after an in vivo inflammatory challenge (high fat diet [HFD] feeding for 10 days), and (2) an enhanced response of microglia isolated from NA‐treated mice and challenged in vitro to LPS. On the other hand, the consequences of a previous NA‐induced neuroinflammation were further evaluated in an alternative inflammatory and hypercaloric scenario, such as the obesity generated by continued HDF feeding. Compared with sham‐injected mice, NA‐treated mice showed increased food intake and, surprisingly, reduced body weight. Besides, NA‐treated mice had enhanced microgliosis (evidenced by increased number and reactive morphology of microglia) and a reduced population of POMC neurons in the basal hypothalamus. Thus, a single acute neuroinflammatory event may elicit a sustained state of priming in microglial cells, and in particular those located in the hypothalamus, with consequences in hypothalamic cytoarchitecture and its regulatory function upon nutritional challenges.
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Affiliation(s)
- María del Mar Fernández‐Arjona
- Instituto de Investigación Biomédica de Málaga‐IBIMAMálagaSpain
- Grupo de investigación en Neuropsicofarmacología, Laboratorio de Medicina RegenerativaHospital Regional Universitario de MálagaMálagaSpain
| | - Ana León‐Rodríguez
- Instituto de Investigación Biomédica de Málaga‐IBIMAMálagaSpain
- Departamento de Biología Celular, Genética y Fisiología, Facultad de CienciasUniversidad de Málaga, Campus de TeatinosMálagaSpain
| | - Jesús M. Grondona
- Instituto de Investigación Biomédica de Málaga‐IBIMAMálagaSpain
- Departamento de Biología Celular, Genética y Fisiología, Facultad de CienciasUniversidad de Málaga, Campus de TeatinosMálagaSpain
| | - María D. López‐Ávalos
- Instituto de Investigación Biomédica de Málaga‐IBIMAMálagaSpain
- Departamento de Biología Celular, Genética y Fisiología, Facultad de CienciasUniversidad de Málaga, Campus de TeatinosMálagaSpain
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Microglia activated by microbial neuraminidase contributes to ependymal cell death. Fluids Barriers CNS 2021; 18:15. [PMID: 33757539 PMCID: PMC7986511 DOI: 10.1186/s12987-021-00249-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 03/10/2021] [Indexed: 11/10/2022] Open
Abstract
The administration of microbial neuraminidase into the brain ventricular cavities of rodents represents a model of acute aseptic neuroinflammation. Ependymal cell death and hydrocephalus are unique features of this model. Here we demonstrate that activated microglia participates in ependymal cell death. Co-cultures of pure microglia with ependymal cells (both obtained from rats) were performed, and neuraminidase or lipopolysaccharide were used to activate microglia. Ependymal cell viability was unaltered in the absence of microglia or inflammatory stimulus (neuraminidase or lipopolysaccharide). The constitutive expression by ependymal cells of receptors for cytokines released by activated microglia, such as IL-1β, was demonstrated by qPCR. Besides, neuraminidase induced the overexpression of both receptors in ventricular wall explants. Finally, ependymal viability was evaluated in the presence of functional blocking antibodies against IL-1β and TNFα. In the co-culture setting, an IL-1β blocking antibody prevented ependymal cell death, while TNFα antibody did not. These results suggest that activated microglia are involved in the ependymal damage that occurs after the administration of neuraminidase in the ventricular cavities, and points to IL-1β as possible mediator of such effect. The relevance of these results lies in the fact that brain infections caused by neuraminidase-bearing pathogens are frequently associated to ependymal death and hydrocephalus.
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Liao H, Klaus C, Neumann H. Control of Innate Immunity by Sialic Acids in the Nervous Tissue. Int J Mol Sci 2020; 21:ijms21155494. [PMID: 32752058 PMCID: PMC7432451 DOI: 10.3390/ijms21155494] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 07/27/2020] [Accepted: 07/28/2020] [Indexed: 12/11/2022] Open
Abstract
Sialic acids (Sias) are the most abundant terminal sugar residues of glycoproteins and glycolipids on the surface of mammalian cells. The nervous tissue is the organ with the highest expression level of Sias. The ‘sialylation’ of glycoconjugates is performed via sialyltransferases, whereas ‘desialylation’ is done by sialidases or is a possible consequence of oxidative damage. Sialic acid residues on the neural cell surfaces inhibit complement and microglial activation, as well as phagocytosis of the underlying structures, via binding to (i) complement factor H (CFH) or (ii) sialic acid-binding immunoglobulin-like lectin (SIGLEC) receptors. In contrast, activated microglial cells show sialidase activity that desialylates both microglia and neurons, and further stimulates innate immunity via microglia and complement activation. The desialylation conveys neurons to become susceptible to phagocytosis, as well as triggers a microglial phagocytosis-associated oxidative burst and inflammation. Dysfunctions of the ‘Sia–SIGLEC’ and/or ‘Sia–complement’ axes often lead to neurological diseases. Thus, Sias on glycoconjugates of the intact glycocalyx and its desialylation are major regulators of neuroinflammation.
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Affiliation(s)
| | | | - Harald Neumann
- Correspondence: ; Tel.: +49-228-6885-500; Fax: +49-228-6885-501
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8
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Brucato FH, Benjamin DE. Synaptic Pruning in Alzheimer's Disease: Role of the Complement System. GLOBAL JOURNAL OF MEDICAL RESEARCH 2020; 20:10.34257/gjmrfvol20is6pg1. [PMID: 32982106 PMCID: PMC7518506 DOI: 10.34257/gjmrfvol20is6pg1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Alz heimer’s disease (AD) continues to threaten aged individuals and health care systems around the world. Human beings have been trying to postpone, reduce, or eliminate the primary risk factor for AD, aging, throughout history. Despite this, there is currently only symptomatic treatment for AD and this treatment is limited to only a handful of FDA approved AD drugs.
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Affiliation(s)
- Frederic H Brucato
- Cascade Biotechnology Inc., Princeton Corporate Plaza 1 Deer Park Dr., Suite D5. Monmouth Junction NJ 08852
| | - Daniel E Benjamin
- Cascade Biotechnology Inc., Princeton Corporate Plaza 1 Deer Park Dr., Suite D5. Monmouth Junction NJ 08852
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9
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Fernández-Arjona MDM, Grondona JM, Fernández-Llebrez P, López-Ávalos MD. Microglial activation by microbial neuraminidase through TLR2 and TLR4 receptors. J Neuroinflammation 2019; 16:245. [PMID: 31791382 PMCID: PMC6889729 DOI: 10.1186/s12974-019-1643-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 11/18/2019] [Indexed: 12/31/2022] Open
Abstract
Background Neuraminidase (NA) is a sialidase present, among various locations, in the envelope/membrane of some bacteria/viruses (e.g., influenza virus), and is involved in infectiveness and/or dispersion. The administration of NA within the brain lateral ventricle represents a model of acute sterile inflammation. The relevance of the Toll-like receptors TLR2 and TLR4 (particularly those in microglial cells) in such process was investigated. Methods Mouse strains deficient in either TLR2 (TLR2-/-) or TLR4 (TLR4-/-) were used. NA was injected in the lateral ventricle, and the inflammatory reaction was studied by immunohistochemistry (IBA1 and IL-1β) and qPCR (cytokine response). Also, microglia was isolated from those strains and in vitro stimulated with NA, or with TLR2/TLR4 agonists as positive controls (P3C and LPS respectively). The relevance of the sialidase activity of NA was investigated by stimulating microglia with heat-inactivated NA, or with native NA in the presence of sialidase inhibitors (oseltamivir phosphate and N-acetyl-2,3-dehydro-2-deoxyneuraminic acid). Results In septofimbria and hypothalamus, IBA1-positive and IL-1β-positive cell counts increased after NA injection in wild type (WT) mice. In TLR4-/- mice, such increases were largely abolished, while were only slightly diminished in TLR2-/- mice. Similarly, the NA-induced expression of IL-1β, TNFα, and IL-6 was completely blocked in TLR4-/- mice, and only partially reduced in TLR2-/- mice. In isolated cultured microglia, NA induced a cytokine response (IL-1β, TNFα, and IL-6) in WT microglia, but was unable to do so in TLR4-/- microglia; TLR2 deficiency partially affected the NA-induced microglial response. When WT microglia was exposed in vitro to heat-inactivated NA or to native NA along with sialidase inhibitors, the NA-induced microglia activation was almost completely abrogated. Conclusions NA is able to directly activate microglial cells, and it does so mostly acting through the TLR4 receptor, while TLR2 has a secondary role. Accordingly, the inflammatory reaction induced by NA in vivo is partially dependent on TLR2, while TLR4 plays a crucial role. Also, the sialidase activity of NA is critical for microglial activation. These results highlight the relevance of microbial NA in the neuroinflammation provoked by NA-bearing pathogens and the possibility of targeting its sialidase activity to ameliorate its impact.
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Affiliation(s)
- María Del Mar Fernández-Arjona
- Dpto. de Biología Celular, Genética y Fisiología, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos, 29071, Málaga, Spain.,Instituto de Investigación Biomédica de Málaga-IBIMA, Málaga, Spain
| | - Jesús M Grondona
- Dpto. de Biología Celular, Genética y Fisiología, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos, 29071, Málaga, Spain.,Instituto de Investigación Biomédica de Málaga-IBIMA, Málaga, Spain
| | - Pedro Fernández-Llebrez
- Dpto. de Biología Celular, Genética y Fisiología, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos, 29071, Málaga, Spain.,Instituto de Investigación Biomédica de Málaga-IBIMA, Málaga, Spain
| | - María Dolores López-Ávalos
- Dpto. de Biología Celular, Genética y Fisiología, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos, 29071, Málaga, Spain. .,Instituto de Investigación Biomédica de Málaga-IBIMA, Málaga, Spain.
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Granados-Durán P, López-Ávalos MD, Cifuentes M, Pérez-Martín M, Fernández-Arjona MDM, Hughes TR, Johnson K, Morgan BP, Fernández-Llebrez P, Grondona JM. Microbial Neuraminidase Induces a Moderate and Transient Myelin Vacuolation Independent of Complement System Activation. Front Neurol 2017; 8:78. [PMID: 28326060 PMCID: PMC5339270 DOI: 10.3389/fneur.2017.00078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 02/20/2017] [Indexed: 02/05/2023] Open
Abstract
AIMS Some central nervous system pathogens express neuraminidase (NA) on their surfaces. In the rat brain, a single intracerebroventricular (ICV) injection of NA induces myelin vacuolation in axonal tracts. Here, we explore the nature, the time course, and the role of the complement system in this damage. METHODS The spatiotemporal analysis of myelin vacuolation was performed by optical and electron microscopy. Myelin basic protein-positive area and oligodendrocyte transcription factor (Olig2)-positive cells were quantified in the damaged bundles. Neuronal death in the affected axonal tracts was assessed by Fluoro-Jade B and anti-caspase-3 staining. To evaluate the role of the complement, membrane attack complex (MAC) deposition on damaged bundles was analyzed using anti-C5b9. Rats ICV injected with the anaphylatoxin C5a were studied for myelin damage. In addition, NA-induced vacuolation was studied in rats with different degrees of complement inhibition: normal rats treated with anti-C5-blocking antibody and C6-deficient rats. RESULTS The stria medullaris, the optic chiasm, and the fimbria were the most consistently damaged axonal tracts. Vacuolation peaked 7 days after NA injection and reverted by day 15. Olig2+ cell number in the damaged tracts was unaltered, and neurodegeneration associated with myelin alterations was not detected. MAC was absent on damaged axonal tracts, as revealed by C5b9 immunostaining. Rats ICV injected with the anaphylatoxin C5a displayed no myelin injury. When the complement system was experimentally or constitutively inhibited, NA-induced myelin vacuolation was similar to that observed in normal rats. CONCLUSION Microbial NA induces a moderate and transient myelin vacuolation that is not caused either by neuroinflammation or complement system activation.
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Affiliation(s)
- Pablo Granados-Durán
- Laboratorio de Fisiología Animal, Facultad de Ciencias, Departamento de Biología Celular, Genética y Fisiología, Instituto de Investigación Biomédica de Málaga (IBIMA), Universidad de Málaga , Málaga , Spain
| | - María Dolores López-Ávalos
- Laboratorio de Fisiología Animal, Facultad de Ciencias, Departamento de Biología Celular, Genética y Fisiología, Instituto de Investigación Biomédica de Málaga (IBIMA), Universidad de Málaga , Málaga , Spain
| | - Manuel Cifuentes
- Laboratorio de Fisiología Animal, Facultad de Ciencias, Departamento de Biología Celular, Genética y Fisiología, Instituto de Investigación Biomédica de Málaga (IBIMA), Universidad de Málaga, Málaga, Spain; Centro de Investigaciones Biomédicas en Red de Bioingeniería, Biomateriales y Nanomedicina, CIBER BBN, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
| | - Margarita Pérez-Martín
- Laboratorio de Fisiología Animal, Facultad de Ciencias, Departamento de Biología Celular, Genética y Fisiología, Instituto de Investigación Biomédica de Málaga (IBIMA), Universidad de Málaga , Málaga , Spain
| | - María Del Mar Fernández-Arjona
- Laboratorio de Fisiología Animal, Facultad de Ciencias, Departamento de Biología Celular, Genética y Fisiología, Instituto de Investigación Biomédica de Málaga (IBIMA), Universidad de Málaga , Málaga , Spain
| | - Timothy R Hughes
- Division of Infection and Immunity, School of Medicine, Cardiff University , Cardiff , UK
| | | | - B Paul Morgan
- Division of Infection and Immunity, School of Medicine, Cardiff University , Cardiff , UK
| | - Pedro Fernández-Llebrez
- Laboratorio de Fisiología Animal, Facultad de Ciencias, Departamento de Biología Celular, Genética y Fisiología, Instituto de Investigación Biomédica de Málaga (IBIMA), Universidad de Málaga , Málaga , Spain
| | - Jesús M Grondona
- Laboratorio de Fisiología Animal, Facultad de Ciencias, Departamento de Biología Celular, Genética y Fisiología, Instituto de Investigación Biomédica de Málaga (IBIMA), Universidad de Málaga , Málaga , Spain
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