RESUMEN
PURPOSE: The complement system is involved in the pathogenesis of age-related macular degeneration (AMD). Because activated microglia are also associated with AMD, we studied the relationship between complement anaphylatoxin receptors and microglial recruitment. METHODS: We assessed the effect of anaphylatoxin C3a receptor (C3aR) and C5a receptor (C5aR) knockout (KO) on light damage-induced migration of microglia/macrophages into the mouse outer retina via immunofluorescence and real-time quantitative PCR. RESULTS: We found that the mRNA levels of C3, C5, C3aR, C5aR, and two activators of the complement alternative pathway, Cfb and Cfd, were all upregulated after light exposure. Retinal Iba1-positive microglia/macrophages express receptors for C3a and C5a. Light damage increased the number of retinal Iba1-positive cells and the mRNA levels of Iba1. Compared with the wild-type (WT) mice, these increases were attenuated in the C5aR KO mice but not in the C3aR KO mice. CONCLUSIONS: C5aR but not C3aR promoted the recruitment of microglia/macrophages. These divergent properties of complement anaphylatoxins in the light damage model provide a rationale for testing the differential effects of these receptors in additional retinal and neurodegeneration models.
Asunto(s)
Movimiento Celular/efectos de la radiación , Técnicas de Inactivación de Genes , Luz/efectos adversos , Macrófagos/fisiología , Microglía/fisiología , Receptor de Anafilatoxina C5a/genética , Degeneración Retiniana/patología , Animales , Proteínas de Unión al Calcio/metabolismo , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Noqueados , Proteínas de Microfilamentos/metabolismo , ARN Mensajero/genética , Traumatismos Experimentales por Radiación/etiología , Traumatismos Experimentales por Radiación/patología , Reacción en Cadena en Tiempo Real de la Polimerasa , Receptores Acoplados a Proteínas G/genética , Retina/efectos de la radiación , Degeneración Retiniana/etiologíaRESUMEN
Complement dysregulation plays a key role in the pathogenesis of age-related macular degeneration (AMD), but the specific mechanisms are incompletely understood. Complement also potentiates retinal degeneration in the murine light damage model. To test the retinal function of CD59a, a complement inhibitor, CD59a knockout (KO) mice were used for light damage (LD) experiments. Retinal degeneration and function were compared in WT versus KO mice following light damage. Gene expression changes, endoplasmic reticulum (ER) stress, and glial cell activation were also compared. At baseline, the ERG responses and rhodopsin levels were lower in CD59aKO compared to wild-type (WT) mice. Following LD, the ERG responses were better preserved in CD59aKO compared to WT mice. Correspondingly, the number of photoreceptors was higher in CD59aKO retinas than WT controls after LD. Under normal light conditions, CD59aKO mice had higher levels than WT for GFAP immunostaining in Müller cells, mRNA and protein levels of two ER-stress markers, and neurotrophic factors. The reduction in photon capture, together with the neurotrophic factor upregulation, may explain the structural and functional protection against LD in the CD59aKO.
Asunto(s)
Antígenos CD59/genética , Luz , Células Fotorreceptoras de Vertebrados/efectos de la radiación , Degeneración Retiniana/patología , Animales , Antígenos CD59/metabolismo , Citocinas/genética , Citocinas/metabolismo , Modelos Animales de Enfermedad , Electrorretinografía , Chaperón BiP del Retículo Endoplásmico , Estrés del Retículo Endoplásmico/efectos de la radiación , Células Ependimogliales/metabolismo , Enucleación del Ojo , Proteínas de Choque Térmico/genética , Proteínas de Choque Térmico/metabolismo , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Noqueados , Microscopía Fluorescente , Factores de Crecimiento Nervioso/genética , Factores de Crecimiento Nervioso/metabolismo , Neuroglía/citología , Neuroglía/metabolismo , Neuroglía/efectos de la radiación , Fagocitosis/efectos de la radiación , Células Fotorreceptoras de Vertebrados/metabolismo , ARN Mensajero/metabolismo , Retina/diagnóstico por imagen , Retina/metabolismo , Degeneración Retiniana/metabolismo , Degeneración Retiniana/veterinaria , Retinaldehído/análisis , Rodopsina/genética , Rodopsina/metabolismo , Regulación hacia Arriba/efectos de la radiaciónRESUMEN
PURPOSE: To investigate the effect of the iron chelator deferiprone (DFP) on sodium iodate (NaIO3)-induced retinal degeneration and on the hereditary retinal degeneration caused by the rd6 mutation. METHODS: Retinas from NaIO3-treated C57BL/6J mice, with or without DFP cotreatment, were analyzed by histology, immunofluorescence, and quantitative PCR to investigate the effect of DFP on retinal degeneration. To facilitate photoreceptor quantification, we developed a new function of MATLAB to perform this task in a semiautomated fashion. Additionally, rd6 mice treated with or without DFP were analyzed by histology to assess possible protection. RESULTS: In NaIO3-treated mice, DFP protected against retinal degeneration and significantly decreased expression of the oxidative stress-related gene heme oxygenase-1 and the complement gene C3. DFP treatment partially protected against NaIO3-induced reduction in the levels of mRNAs encoded by visual cycle genes rhodopsin (Rho) and retinal pigment epithelium-specific 65 kDa protein (Rpe65), consistent with the morphological data indicating preservation of photoreceptors and RPE, respectively. DFP treatment also protected photoreceptors in rd6 mice. CONCLUSIONS: The oral iron chelator DFP provides significant protection against retinal degeneration induced through different modalities. This suggests that iron chelation could be useful as a treatment for retinal degeneration even when the main etiology does not appear to be iron dysregulation. TRANSLATIONAL RELEVANCE: These data provide proof of principle that the oral iron chelator DFP can protect the retina against diverse insults. Further testing of DFP in additional animal retinal degeneration models at a range of doses is warranted.
RESUMEN
PURPOSE: To investigate the effect of the iron chelator deferiprone (DFP) on sodium iodate (NaIO3)-induced retinal degeneration and on the hereditary retinal degeneration caused by the rd6 mutation. METHODS: Retinas from NaIO3-treated C57BL/6J mice, with or without DFP cotreatment, were analyzed by histology, immunofluorescence, and quantitative PCR to investigate the effect of DFP on retinal degeneration. To facilitate photoreceptor quantification, we developed a new function of MATLAB to perform this task in a semiautomated fashion. Additionally, rd6 mice treated with or without DFP were analyzed by histology to assess possible protection. RESULTS: In NaIO3-treated mice, DFP protected against retinal degeneration and significantly decreased expression of the oxidative stress-related gene heme oxygenase-1 and the complement gene C3. DFP treatment partially protected against NaIO3-induced reduction in the levels of mRNAs encoded by visual cycle genes rhodopsin (Rho) and retinal pigment epithelium-specific 65 kDa protein (Rpe65), consistent with the morphological data indicating preservation of photoreceptors and RPE, respectively. DFP treatment also protected photoreceptors in rd6 mice. CONCLUSIONS: The oral iron chelator DFP provides significant protection against retinal degeneration induced through different modalities. This suggests that iron chelation could be useful as a treatment for retinal degeneration even when the main etiology does not appear to be iron dysregulation. TRANSLATIONAL RELEVANCE: These data provide proof of principle that the oral iron chelator DFP can protect the retina against diverse insults. Further testing of DFP in additional animal retinal degeneration models at a range of doses is warranted.