Browsing by Subject "Retinal degeneration"

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    The roles of microglia in neural remodeling during retinal degeneration
    (Retina remodeling is a consequence of many retinal degenerative diseases that are characterized by progressive photoreceptor death. Retina remodeling involves a series of complex pathological processes, consisting of photoreceptor degeneration and death, as well as retinal cell reprogramming and "rewiring". This rewiring alters retinal neural circuits that are centered on synaptic connections and lead to widespread death of retinal cells. Retinal remodeling, especially inner retinal remodeling, is the major factor that limits the effectiveness of various treatment strategies, including cell therapy; thus, it is important to elucidate the mechanisms involved in retinal remodeling during retinal degeneration. Microglia are the dominant immune cells in the retina. Microglia monitor the retinal microenvironment, are activated following retinal injury or degeneration, have powerful phagocytosis capabilities, and play a critical role in synaptic pruning during central neural system development. Analogously, microglia have been found to participate in the clearance of synaptic elements in a complement-dependent manner in the classic retinitis pigmentosa (RP) model, Royal College of Surgeons (RCS) rats, and retard the formation of ectopic neuritogenesis and the deterioration of visual function during retinal degeneration. Since previous research on microglia has rarely concentrated on synaptic remodeling during retinal degeneration, summarizing the microglial mechanisms involved in retinal remodeling is necessary in order to design compounds targeting microglia and retinal remodeling that might be promising therapeutic strategies for treating retinal degeneration., 2022) Gao, Hui; Huang, Xiaona; He, Juncai; Zou, Ting; Chen, Xuan; Xu, Haiwei
    Retina remodeling is a consequence of many retinal degenerative diseases that are characterized by progressive photoreceptor death. Retina remodeling involves a series of complex pathological processes, consisting of photoreceptor degeneration and death, as well as retinal cell reprogramming and "rewiring". This rewiring alters retinal neural circuits that are centered on synaptic connections and lead to widespread death of retinal cells. Retinal remodeling, especially inner retinal remodeling, is the major factor that limits the effectiveness of various treatment strategies, including cell therapy; thus, it is important to elucidate the mechanisms involved in retinal remodeling during retinal degeneration. Microglia are the dominant immune cells in the retina. Microglia monitor the retinal microenvironment, are activated following retinal injury or degeneration, have powerful phagocytosis capabilities, and play a critical role in synaptic pruning during central neural system development. Analogously, microglia have been found to participate in the clearance of synaptic elements in a complement-dependent manner in the classic retinitis pigmentosa (RP) model, Royal College of Surgeons (RCS) rats, and retard the formation of ectopic neuritogenesis and the deterioration of visual function during retinal degeneration. Since previous research on microglia has rarely concentrated on synaptic remodeling during retinal degeneration, summarizing the microglial mechanisms involved in retinal remodeling is necessary in order to design compounds targeting microglia and retinal remodeling that might be promising therapeutic strategies for treating retinal degeneration.
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    Understanding glaucomatous damage: Anatomical and functional data from ocular hypertensive rodent retinas
    (Elsevier, 2012-01-27) Miralles de Imperial, Jaime; Vidal Sanz, Manuel; Salinas Navarro, Manuel Ángel; Nadal-Nicolás, Francisco Manuel; Valiente Soriano, Francisco Javier; Agudo Barriuso, Marta; Villegas Pérez, Maria Paz; Avilés Trigueros, Marcelino; Alarcón Martínez, Luis; Oftalmología, Optometría, Otorrinolaringología y Anatomía Patológica; Facultades de la UMU::Facultad de Medicina
    Glaucoma, the second most common cause of blindness, is characterized by a progressive loss of retinal ganglion cells and their axons, with a concomitant loss of the visual field. Although the exact pathogenesis of glaucoma is not completely understood, a critical risk factor is the elevation, above normal values, of the intraocular pressure. Consequently, deciphering the anatomical and functional changes occurring in the rodent retina as a result of ocular hypertension has potential value, as it may help elucidate the pathology of retinal ganglion cell degeneration induced by glaucoma in humans. This paper predominantly reviews the cumulative information from our laboratory’s previous, recent and ongoing studies, and discusses the deleterious anatomical and functional effects of ocular hypertension on retinal ganglion cells (RGCs) in adult rodents. In adult rats and mice, perilimbar and episcleral vein photocauterization induces ocular hypertension, which in turn results in devastating damage of the RGC population. In wide triangular sectors, preferentially located in the dorsal retina, RGCs lose their retrograde axonal transport, first by a functional impairment and after by mechanical causes. This axonal damageaffects up to 80% of the RGC population, and eventuallycauses their death, with somal and intraretinal axonal degeneration that resembles that observed after optic nerve crush. Importantly, while ocular hypertension affects the RGC population, it spares non-RGC neurons located in the ganglion cell layer of the retina. In addition, functional and morphological studies show permanent alterations of the inner and outer retinal layers, indicating that further to a crush-like injury of axon bundles in the optic nerve head there may by additional insults to the retina, perhaps of ischemic nature.
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    Upregulation of vascular endothelial growth factor (VEGF) in the retinas of transgenic mice overexpressing interleukin-1ß (IL-1ß) in the lens and mice undergoing retinal degeneration
    (Murcia : F. Hernández, 2003) Vinores, S.A.; Xiao, W.H.; Zimmerman, R.; Whitcup, S.M.; Wawrousek, E.F.
    IL-1ß is a pro-inflammatory agent associated with angiogenesis and increased vascular permeability. To determine whether IL-1ß elicits these responses through an upregulation of VEGF, transgenic mice that overexpress IL-1ß in the lens were evaluated at various time points for the localization of VEGF, the location and extent of blood-retinal barrier (BRB) breakdown, and the origin and extent of neovascularization (NV). In homozygous and heterozygous transgenic mice, but not controls, intense VEGF immunoreactivity was scattered throughout the retina at postnatal days 5-7 (P5-7), just after the onset of inflammatory cell infiltration. VEGF staining in the retina remained widespread, but weak from P9-15. Beginning at P15, the intensity of VEGF immunoreactivity achieved a second peak, which it maintained through adulthood. This peak coincided with significant retinal destruction due to massive inflammation. The onset of BRB breakdown coincided with the upregulation of VEGF (P5-7) and widespread BRB breakdown was demonstrated from about P9. From P9-12, aggregates of cells positive for Griffonia simplicifolia isolectin-B4, a marker for vascular endothelial cells, formed on the retinal surface. These cells migrated into the retina at P12-15 with the more superficial cells forming a network of vessels and the deeper cells remaining in small clusters, thus demonstrating that NV occurs much later than BRB breakdown. Non-transgenic FVB/N mice, which undergo retinal degeneration beginning at about P9, also demonstrate the latter peak of VEGF upregulation and the accompanying BRB breakdown, but not the early upregulation. VEGF immunostaining of transgenic and non-transgenic mouse retinas was eliminated by preincubation of the VEGF antibodies with VEGF peptide. The data suggest that the early peak of VEGF upregulation (P5-7) and its accompanying BRB breakdown is due to IL-1ß expression and is likely to be dependent on inflammatory cell infiltration. The latter peak appears to be related to retinal destruction.