Search

Leber congenital amaurosis type nine is an autosomal recessive retinopathy caused by mutations of the NAD + synthesis enzyme NMNAT1. Despite the ubiquitous expression of NMNAT1, patients do not manifest pathologies other than retinal degeneration. Here we demonstrate that widespread NMNAT1 depletion in adult mice mirrors the human pathology, with selective loss of photoreceptors highlighting the exquisite vulnerability of these cells to NMNAT1 loss. Conditional deletion demonstrates that NMNAT1 is required within the photoreceptor. Mechanistically, loss of NMNAT1 activates the NADase SARM1, the central executioner of axon degeneration, to trigger photoreceptor death and vision loss. Hence, the essential function of NMNAT1 in photoreceptors is to inhibit SARM1, highlighting an unexpected shared mechanism between axonal degeneration and photoreceptor neurodegeneration. These results define a novel SARM1-dependent photoreceptor cell death pathway and identifies SARM1 as a therapeutic candidate for retinopathies., Competing Interests: YS YS is a consultant to Disarm Therapeutics. HK, SK, AS, TL, NB, ZD, JL, SB, SB, RA No competing interests declared, AD AD is a co-founder and shareholder in Disarm Therapeutics. JM JM is a co-founder and shareholder in Disarm Therapeutics., (© 2020, Sasaki et al.)

Retinal degenerative diseases are a major cause of morbidity in modern society because visual impairment significantly decreases the quality of life of patients. A significant challenge in treating retinal degenerative diseases is their genetic and phenotypic heterogeneity. However, despite this diversity, many of these diseases share a common endpoint involving death of light-sensitive photoreceptors. Identifying common pathogenic mechanisms that contribute to photoreceptor death in these diverse diseases may lead to a unifying therapy for multiple retinal diseases that would be highly innovative and address a great clinical need. Because the retina and photoreceptors, in particular, have immense metabolic and energetic requirements, many investigators have hypothesized that metabolic dysfunction may be a common link unifying various retinal degenerative diseases. Here, we discuss a new area of research examining the role of NAD + and sirtuins in regulating retinal metabolism and in the pathogenesis of retinal degenerative diseases. Indeed, the results of numerous studies suggest that NAD + intermediates or small molecules that modulate sirtuin function could enhance retinal metabolism, reduce photoreceptor death, and improve vision. Although further research is necessary to translate these findings to the bedside, they have strong potential to truly transform the standard of care for patients with retinal degenerative diseases., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Biallelic mutations in the RPE65 gene are associated with inherited retinal degenerations/dystrophies (IRD) and disrupt the visual cycle, leading to loss of vision. A new adenoviral vector-based gene therapy surgically delivered to retinal cells provides normal human RPE65 protein that can restore the visual cycle and some vision. To view this Bench to Bedside, open or download the PDF., (Copyright © 2018. Published by Elsevier Inc.)

Photoreceptor death is the endpoint of many blinding diseases. Identifying unifying pathogenic mechanisms in these diseases may offer global approaches for facilitating photoreceptor survival. We found that rod or cone photoreceptor-specific deletion of nicotinamide phosphoribosyltransferase (Nampt), the rate-limiting enzyme in the major NAD(+) biosynthetic pathway beginning with nicotinamide, caused retinal degeneration. In both cases, we could rescue vision with nicotinamide mononucleotide (NMN). Significantly, retinal NAD(+) deficiency was an early feature of multiple mouse models of retinal dysfunction, including light-induced degeneration, streptozotocin-induced diabetic retinopathy, and age-associated dysfunction. Mechanistically, NAD(+) deficiency caused metabolic dysfunction and consequent photoreceptor death. We further demonstrate that the NAD(+)-dependent mitochondrial deacylases SIRT3 and SIRT5 play important roles in retinal homeostasis and that NAD(+) deficiency causes SIRT3 dysfunction. These findings demonstrate that NAD(+) biosynthesis is essential for vision, provide a foundation for future work to further clarify the mechanisms involved, and identify a unifying therapeutic target for diverse blinding diseases., (Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.)

Oxidative stress plays a critical role in accelerating retinal pigment epithelial dysfunction and death in degenerative retinal diseases, including age-related macular degeneration. Given the key role of oxidative stress-induced retinal pigment epithelial cell death and secondary photoreceptor loss in the pathogenesis of age-related macular degeneration, we hypothesized that a novel thiol antioxidant, N-acetylcysteine amide (NACA), might ameliorate cellular damage and subsequent loss of vision. Treatment of human retinal pigment epithelial cells with NACA protected against oxidative stress-induced cellular injury and death. NACA acted mechanistically by scavenging existing reactive oxygen species while halting production of reactive oxygen species by reversing lipid peroxidation. Furthermore, NACA functioned by increasing the levels of reduced glutathione and the phase II detoxification enzyme glutathione peroxidase. Treatment of mice exposed to phototoxic doses of light with NACA maintained retinal pigment epithelial cell integrity and prevented outer nuclear layer cell death as examined by histopathologic methods and rescued photoreceptor function as measured by electroretinography. These observations indicate that NACA protects against oxidative stress-induced retinal pigment epithelial and photoreceptor cell death in vitro and in vivo. The data suggest that NACA may be a novel treatment in rescuing retinal function and preventing vision loss secondary to retinal degenerative diseases, including age-related macular degeneration., (Copyright © 2011 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Retinal degenerative diseases are a major cause of morbidity in modern society because visual impairment significantly decreases the quality of life of patients. A significant challenge in treating retinal degenerative diseases is their genetic and phenotypic heterogeneity. However, despite this diversity, many of these diseases share a common endpoint involving death of light-sensitive photoreceptors. Identifying common pathogenic mechanisms that contribute to photoreceptor death in these diverse diseases may lead to a unifying therapy for multiple retinal diseases that would be highly innovative and address a great clinical need. Because the retina and photoreceptors, in particular, have immense metabolic and energetic requirements, many investigators have hypothesized that metabolic dysfunction may be a common link unifying various retinal degenerative diseases. Here, we discuss a new area of research examining the role of NAD+ and sirtuins in regulating retinal metabolism and in the pathogenesis of retinal degenerative diseases. Indeed, the results of numerous studies suggest that NAD+ intermediates or small molecules that modulate sirtuin function could enhance retinal metabolism, reduce photoreceptor death, and improve vision. Although further research is necessary to translate these findings to the bedside, they have strong potential to truly transform the standard of care for patients with retinal degenerative diseases. [ABSTRACT FROM AUTHOR]

Purpose To evaluate the relative efficacy of as needed versus treat and extend regimen for the treatment of neovascular age-related macular degeneration (AMD). Methods We conducted a systematic review of studies that evaluated the efficacy of as needed or treat and extend regimen for neovascular AMD by searching multiple databases up to December 2013. Included studies were selected based on study duration of no less than 12 months, availability of outcome data, treatment protocol for as needed groups or pro re nata (PRN) receiving bevacizumab or ranibizumab, and all studies with treat extend protocols following the 'inject and extend' regimen. The outcome data were pooled and analysed. Results 1046 peer reviewed articles meeting our initia search criteria were returned. After further review by two independent reviewers, 8 studies meeting treat and extend protocol and 62 studies meeting PRN protocol were included. The mean improvement in visual acuity in the PRN group was 5.4 ETDRS letters compared with 10.4 ETDRS letters in the treat and extend group. The PRN group received an average of 5.60 injections at 1 year compared with 8.09 in the treat and extend group. Central retinal thickness improved on average by 100.32 μ in the PRN group compared with 87.7 μ in the treat and extend group. Conclusions Though our study suggests superiority of the treat and extend regimen to PRN treatment in a 12-month period, this review demonstrates the need for randomised clinical trials to confirm our findings and to evaluate long-term efficacy outcomes with these regimens compared with monthly therapy. [ABSTRACT FROM AUTHOR]

Summary: Pathologic angiogenesis mediated by abnormally polarized macrophages plays a central role in common age-associated diseases such as atherosclerosis, cancer, and macular degeneration. Here we demonstrate that abnormal polarization in older macrophages is caused by programmatic changes that lead to reduced expression of ATP binding cassette transporter ABCA1. Downregulation of ABCA1 by microRNA-33 impairs the ability of macrophages to effectively efflux intracellular cholesterol, which in turn leads to higher levels of free cholesterol within senescent macrophages. Elevated intracellular lipid polarizes older macrophages to an abnormal, alternatively activated phenotype that promotes pathologic vascular proliferation. Mice deficient for Abca1, but not Abcg1, demonstrate an accelerated aging phenotype, whereas restoration of cholesterol efflux using LXR agonists or miR-33 inhibitors reverses it. Monocytes from older humans with age-related macular degeneration showed similar changes. These findings provide an avenue for therapeutic modulation of macrophage function in common age-related diseases. [ABSTRACT FROM AUTHOR]

Age-related macular degeneration (AMD) is a major cause of blindness in the developed world. Oxidative stress and inflammation are implicated in AMD, but precise mechanisms remain poorly defined. Carboxyethylpyrrole (CEP) is an AMD-associated lipid peroxidation product. We previously demonstrated that mice immunized with CEP-modified albumin developed AMD-like degenerative changes in the outer retina. Here, we examined the kinetics of lesion development in immunized mice and the presence of macrophages within the interphotoreceptor matrix (IPM), between the retinal pigment epithelium and photoreceptor outer segments. We observed a significant and time-dependent increase in the number of macrophages in immunized mice relative to young age-matched controls prior to overt pathology. These changes were more pronounced in BALB/c mice than in C57BL/6 mice. Importantly, IPM-infiltrating macrophages were polarized toward the M1 phenotype but only in immunized mice. Moreover, when Ccr2-deficient mice were immunized, macrophages were not present in the IPM and no retinal lesions were observed, suggesting a deleterious role for these cells in our model. This work provides mechanistic evidence linking immune responses against oxidative damage with the presence of proinflammatory macrophages at sites of future AMD and experimentally demonstrates that manipulating immunity may be a target for modulating the development of AMD. [ABSTRACT FROM AUTHOR]

: PurposeTo report a case of presumed congenital hypertrophy of the retinal pigment epithelium in the fovea of an 88-year-old woman in the setting of geographic atrophy from age-related macular degeneration.: DesignObservational case report.: MethodsAn 88-year-old woman was examined.: ResultsBest-corrected visual acuity was 20/63 in the right eye and 20/50 in the left eye. Multifocal areas of geographic atrophy and large-sized drusen were seen in the maculae of both eyes. Biomicroscopic examination of the right eye showed hyperpigmentation consistent with congenital hypertrophy of the retinal pigment epithelium through the center of the macula. No prior photographic documentation of the retina was available.: ConclusionThis case suggests that foveal congenital hypertrophy of the retinal pigment epithelium may be seen in the setting of macular geographic atrophy. Although it is theoretically possible that the hyperpigmentation is reactive rather than congenital, the pigmentation is typical for congenital hypertrophy and is unlike any reactive pigmentation in our experience or described in a MEDLINE search of features of age-related macular degeneration. The case suggests that a hypertrophic process of the retinal pigment epithelium may coexist within or immediately adjacent to the anatomic boundaries of an atrophic process such as geographic atrophy from age-related macular degeneration. [Copyright &y& Elsevier]

Background: Age-related macular degeneration (AMD) is the leading cause of blindness in people over 50 y of age in at least three continents. Choroidal neovascularization (CNV) is the process by which abnormal blood vessels develop underneath the retina. CNV develops in 10% of patients with AMD but accounts for up to 90% of the blindness from AMD. Although the precise etiology of CNV in AMD remains unknown, the macrophage component of the inflammatory response, which has been shown to promote tumor growth and support atherosclerotic plaque formation, is thought to stimulate aberrant angiogenesis in blinding eye diseases. The current theory is that macrophage infiltration promotes the development of neovascularization in CNV.Methods and Findings: We examined the role of macrophages in a mouse model of CNV. IL-10(-/-) mice, which have increased inflammation in response to diverse stimuli, have significantly reduced CNV with increased macrophage infiltrates compared to wild type. Prevention of macrophage entry into the eye promoted neovascularization while direct injection of macrophages significantly inhibited CNV. Inhibition by macrophages was mediated by the TNF family death molecule Fas ligand (CD95-ligand).Conclusions: Immune vascular interactions can be highly complex. Normal macrophage function is critical in controlling pathologic neovascularization in the eye. IL-10 regulates macrophage activity in the eye and is an attractive therapeutic target in order to suppress or inhibit CNV in AMD that can otherwise lead to blindness. [ABSTRACT FROM AUTHOR]

Leber congenital amaurosis type nine is an autosomal recessive retinopathy caused by mutations of the NAD+ synthesis enzyme NMNAT1. Despite the ubiquitous expression of NMNAT1, patients do not manifest pathologies other than retinal degeneration. Here we demonstrate that widespread NMNAT1 depletion in adult mice mirrors the human pathology, with selective loss of photoreceptors highlighting the exquisite vulnerability of these cells to NMNAT1 loss. Conditional deletion demonstrates that NMNAT1 is required within the photoreceptor. Mechanistically, loss of NMNAT1 activates the NADase SARM1, the central executioner of axon degeneration, to trigger photoreceptor death and vision loss. Hence, the essential function of NMNAT1 in photoreceptors is to inhibit SARM1, highlighting an unexpected shared mechanism between axonal degeneration and photoreceptor neurodegeneration. These results define a novel SARM1-dependent photoreceptor cell death pathway and identifies SARM1 as a therapeutic candidate for retinopathies. [ABSTRACT FROM AUTHOR]

Purpose: To determine whether the complement factor H (CFH) Y402H variant is associated with specific age-related macular degeneration (AMD) clinical phenotypes.Design: Retrospective, case-control study.Methods: One hundred and eighty-eight white subjects with AMD and 189 control subjects were genotyped for the T-to-C polymorphism in exon 9 of the CFH gene by restriction-fragment length analysis and deoxyribonucleic acid (DNA) sequencing using genomic DNA from mouthwash samples. AMD phenotypes were characterized by clinical examination, fundus photography, and fluorescein angiography.Results: Heterozygosity for the at-risk genotype (TC) increased the likelihood for AMD 2.1-fold (95% confidence interval [CI], 1.3 to 3.3), whereas homozygosity for the genotype (CC) increased the likelihood for AMD 6.5-fold (95% CI, 3.4 to 12.5) in our population. The C allele was associated significantly with predominantly classic choroidal neovascularization (odds ratio [OR], 2.01; 95% CI, 1.34 to 3.30). Neovascular lesion size was similar among the three genotypes (P = .67).Conclusions: The Y402H CFH variant carried a significantly increased risk for developing AMD in our population. Genotype and phenotype correlations regarding choroidal neovascular lesion type were observed. [ABSTRACT FROM AUTHOR]

Purpose: To report two cases of a retinal pigment epithelial tear after intravitreal injection of pegaptanib sodium. To our knowledge, this is the first report of this finding after intraocular antivascular endothelial growth factor therapy.Design: Observational case reports.Methods: Two patients presented with occult choroidal neovascularization and associated serous pigment epithelial detachment that was a result of age-related macular degeneration. Both patients were treated with an intravitreal injection of pegaptanib sodium.Results: One patient developed a retinal pigment epithelium tear one week after the intravitreal injection. The second patient developed a retinal pigment epithelium tear eight weeks after treatment.Conclusions: Although these cases may represent natural history, there should be a high index of suspicion for retinal pigment epithelium tears in patients who report significant visual deterioration after intravitreal injection of pegaptanib sodium. Further studies are needed to determine whether angiographic subtypes of choroidal neovascular membranes are more susceptible to developing retinal pigment epithelium tears after treatment with antivascular endothelial growth factor agents. [ABSTRACT FROM AUTHOR]

Cell-autonomous endothelial cell (EC) fibroblast growth factor receptor (FGFR) signaling through FGFR1/2 is essential for injury-induced wound vascularization and pathologic neovascularization as in blinding eye diseases such as age-related macular degeneration. Which FGF ligand(s) is critical in regulating angiogenesis is unknown. Utilizing ex vivo models of choroidal endothelial sprouting and in vivo models of choroidal neovascularization (CNV), we demonstrate here that only FGF2 is the essential ligand. Though FGF-FGFR signaling can activate multiple intracellular signaling pathways, we show that FGF2 regulates pathogenic angiogenesis via STAT3 activation. The identification of FGF2 as a critical mediator in aberrant neovascularization provides a new opportunity for developing multi-target therapies in blinding eye diseases especially given the limitations of anti-VEGF monotherapy. • Fibroblast growth factor-2 (FGF-2) regulates choroidal neovascularization. • FGF-2 activates intracellular stat3. • The identification of the fgf-2/stat3 axis presents novel therapeutic opportunities. [ABSTRACT FROM AUTHOR]