Browsing by Subject "Optic nerve injury"

Now showing 1 - 4 of 4
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    Annexin-V binds subpopulation of immune cells altering its interpretation as an in vivo biomarker for apoptosis in the retina
    (Ivyspring International Publisher., 2024-11-11) Miyagishima, Kiyoharu J.; Ma, Wenxin; Li, Wei ; Nadal-Nicolás, Francisco Manuel; Oftalmología, Optometría, Otorrinolaringología y Anatomía Patológica; Facultades de la UMU::Facultad de Medicina
    In cells undergoing apoptosis phosphatidylserine, a major component of the plasma membrane, translocates to the outer leaflet where it provides eat-me signals for phagocytic recognition and is bound by annexin-V, an apoptotic marker. The need to track retinal ganglion cell death (RGC) in response to glaucomatous damage or optic neuropathy has led to the development of DARC (detection of apoptosing retinal cells) imaging, providing non-invasive, in vivo assessment of RGC death. Although the eye is an immune privileged site, resident and infiltrating immune cells are known to respond quickly to trauma or infection. Some immune cells have binding sites for annexin homologs; thus, their presence may confound estimates of apoptosis measured by annexin-V labeling. The purpose of this study was to re-examine the accuracy of annexin-V apoptotic labeling in the posterior eye and to temporally characterize contributions of non-apoptotic labeling in response to optic nerve (ON) injury. Here, we found annexin-V labeling consists of two phases. Initially, there is a rapid phase matching the time course of apoptotic cell death indicated by cleaved caspase-3 immunostaining observed ex vivo. This is followed by a sustained plateau phase that persists long after the peak of degeneration. We demonstrate that annexin-V binds to a specific subpopulation of myeloid cells in the retina, which were identified using simultaneous confocal scanning laser ophthalmoscopy. Optical coherence tomography and confocal imaging reveal these cells occupy the posterior hyaloid space above the retinal nerve fiber layer and at various retinal depths. Our results highlight the cellular morphological heterogeneity of non-apoptotic annexin-V labeling of retinal microglia. Accordingly, pharmacological depletion of microglia abolishes annexin-V labeling of elongated microglia in vivo revealing fainter labeling of round RGCs. Thus, consideration should be given to the time course of the immune response when interpreting fluorescently labeled annexin-V to visualize retinal cell apoptosis for clinical diagnosis.
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    Complementary research models and methods to study axonal regeneration in the vertebrate retinofugal system
    (Springer, 2018) Bollaerts, Ilse; Veys, Lien; Geeraerts, Emiel; Andries, Lien; De Groef, Lies; Buyens, Tom; Moons, Lieve; Van Hove, Inge; Salinas Navarro, Manuel Ángel; Anatomía Humana y Psicobiología
    Due to the lack of axonal regeneration, age-related deterioration in the central nervous system (CNS) poses a significant burden on the wellbeing of a growing number of elderly. To overcome this regenerative failure and to improve the patient’s life quality, the search for novel regenerative treatment strategies requires valuable (animal) models and techniques. As an extension of the CNS, the retinofugal system, consisting of retinal ganglion cells that send their axons along the optic nerve to the visual brain areas, has importantly contributed to the current knowledge on mechanisms underlying the restricted regenerative capacities and to the development of novel strategies to enhance axonal regeneration. It provides an extensively used research tool, not only in amniote vertebrates including rodents, but also in anamniote vertebrates, such as zebrafish. Indeed, the latter show robust regeneration capacities, thereby providing insights into the factors that contribute to axonal regrowth and proper guidance, complementing studies in mammals. This review provides an integrative and critical overview of the classical and state-of-the-art models and methods that have been employed in the retinofugal system to advance our knowledge on the signaling pathways underlying the restricted versus robust axonal regeneration in rodents and zebrafish, respectively. In vitro, ex vivo and in vivo models and techniques to improve the visualization and analysis of regenerating axons are summarized. As such, the retinofugal system is presented as a valuable model to further facilitate research on axonal regeneration and to open novel therapeutic avenues for CNS pathologies.
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    MMP2 Modulates Inflammatory Response during Axonal Regeneration in the Murine Visual System
    (MDPI, 2021-07-02) Andries, Lien; Masin, Luca; Salinas Navarro, Manuel Ángel; Zaunz, Samantha; Claes, Marie; Bergmans, Steven; Brouwers, Véronique; Lefevere, Evy; Verfaillie, Catherine; Movahedi, Kiavash; De Groef, Lies ; Moons, Lieve; Anatomía Humana y Psicobiología; Facultades de la UMU::Facultad de Medicina
    Neuroinflammation has been put forward as a mechanism triggering axonal regrowth in the mammalian central nervous system (CNS), yet little is known about the underlying cellular and molecular players connecting these two processes. In this study, we provide evidence that MMP2 is an essential factor linking inflammation to axonal regeneration by using an in vivo mouse model of inflammation-induced axonal regeneration in the optic nerve. We show that infiltrating myeloid cells abundantly express MMP2 and that MMP2 deficiency results in reduced long-distance axonal regeneration. However, this phenotype can be rescued by restoring MMP2 expression in myeloid cells via a heterologous bone marrow transplantation. Furthermore, while MMP2 deficiency does not affect the number of infiltrating myeloid cells, it does determine the coordinated expression of pro- and anti-inflammatory molecules. Altogether, in addition to its role in axonal regeneration via resolution of the glial scar, here, we reveal a new mechanism via which MMP2 facilitates axonal regeneration, namely orchestrating the expression of pro- and anti-inflammatory molecules by infiltrating innate immune cells.
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    Time-course of the retinal nerve fibre layer degeneration after complete intra-orbital optic nerve transection or crush: a comparative study
    (Elsevier, 2009-11-23) Parrilla Reverter, Guillermo; Agudo Barriuso, Marta; Nadal-Nicolás, Francisco Manuel; Jiménez López, Manuel; Salinas Navarro, Manuel Ángel; Sobrado Calvo, Paloma; Bernal Garro, José M.; Villegas Pérez, Maria Paz; Vidal Sanz, Manuel; Alarcón Martínez, Luis; Oftalmología, Optometría, Otorrinolaringología y Anatomía Patológica; Facultades de la UMU::Facultad de Medicina
    We examined qualitatively and quantitatively in adult rat retinas the temporal degeneration of the nerve fibre layer after intra-orbital optic nerve transection (IONT) or crush (IONC). Retinal ganglion cell (RGC) axons were identified by their heavy neurofilament subunit phosphorylated isoform (pNFH) expression. Optic nerve injury induces a progressive axonal degeneration which after IONT proceeds mainly with abnormal pNFH-accumulations in RCG axons and after IONC in RGCs somas and dendrites. Importantly, this aberrant pNFH-expression pattern starts earlier and is more dramatic after IONT than after IONC, highlighting the importance that the type of injury has on the time-course of RGC degeneration.