Cytoplasmic synthesis of endogenous Alu complementary DNA via reverse transcription and implications in age-related macular degeneration.

Alu retroelements propagate via retrotransposition by hijacking long interspersed nuclear element-1 (L1) reverse transcriptase (RT) and endonuclease activities. Reverse transcription of Alu RNA into complementary DNA (cDNA) is presumed to occur exclusively in the nucleus at the genomic integration site. Whether Alu cDNA is synthesized independently of genomic integration is unknown. Alu RNA promotes retinal pigmented epithelium (RPE) death in geographic atrophy, an untreatable type of age-related macular degeneration. We report that Alu RNA-induced RPE degeneration is mediated via cytoplasmic L1-reverse-transcribed Alu cDNA independently of retrotransposition. Alu RNA did not induce cDNA production or RPE degeneration in L1-inhibited animals or human cells. Alu reverse transcription can be initiated in the cytoplasm via self-priming of Alu RNA. In four health insurance databases, use of nucleoside RT inhibitors was associated with reduced risk of developing atrophic macular degeneration (pooled adjusted hazard ratio, 0.616; 95% confidence interval, 0.493-0.770), thus identifying inhibitors of this Alu replication cycle shunt as potential therapies for a major cause of blindness.

Chronic Dicer1 deficiency promotes atrophic and neovascular outer retinal pathologies in mice.

Degeneration of the retinal pigmented epithelium (RPE) and aberrant blood vessel growth in the eye are advanced-stage processes in blinding diseases such as age-related macular degeneration (AMD), which affect hundreds of millions of people worldwide. Loss of the RNase DICER1, an essential factor in micro-RNA biogenesis, is implicated in RPE atrophy. However, the functional implications of DICER1 loss in choroidal and retinal neovascularization are unknown. Here, we report that two independent hypomorphic mouse strains, as well as a separate model of postnatal RPE-specific DICER1 ablation, all presented with spontaneous RPE degeneration and choroidal and retinal neovascularization. DICER1 hypomorphic mice lacking critical inflammasome components or the innate immune adaptor MyD88 developed less severe RPE atrophy and pathological neovascularization. DICER1 abundance was also reduced in retinas of the JR5558 mouse model of spontaneous choroidal neovascularization. Finally, adenoassociated vector-mediated gene delivery of a truncated DICER1 variant (OptiDicer) reduced spontaneous choroidal neovascularization in JR5558 mice. Collectively, these findings significantly expand the repertoire of DICER1 in preserving retinal homeostasis by preventing both RPE degeneration and pathological neovascularization.

Suppression of Retinal Neovascularization by Anti-CCR3 Treatment in an Oxygen-Induced Retinopathy Model in Mice.

PURPOSE: To investigate the association between retinal neovascularization and the CC chemokine receptor-3 (CCR3) in a mouse model of oxygen-induced retinopathy (OIR). METHODS: An OIR model in C57BL/6J mice was used as a retinal neovascularization model. An enzyme-linked immunosorbent assay was performed to evaluate the chronological change in vascular endothelial growth factor A (VEGF-A) and eotaxin expressions. CCR3 and VEGF subtype expression in the retina was examined using real-time RT-PCR, and CCR3, eotaxin, VEGF-A, and CD31 expression was examined immunohistochemically. A CCR3 neutralizing antibody (Ab) was injected into the vitreous humor on both postnatal days 12 (P12) and 14 (P14). Retinal neovascularizations were quantified by measurement of the percentages of neovascular area. RESULTS: The mean eotaxin and VEGF-A protein level was significantly downregulated at P10 and P12 and was significantly upregulated at P14 and P17 (p < 0.05). CCR3 mRNA expression was significantly upregulated at P12 (p < 0.05). VEGF164 mRNA expression was significantly upregulated at P14 (p < 0.05). The areas of vaso-obliteration and neovascularization were significantly suppressed in anti-CCR3 Ab-treated eyes (p < 0.05). Anti-CCR3 Ab treatment suppressed VEGF and eotaxin but not monocyte chemoattractant protein-1. And VEGF 164 mRNA but not VEGF120 mRNA was suppressed by anti-CCR3 Ab treatment. CONCLUSIONS: The present data suggest that anti-CCR3 treatment can suppress retinal neovascularization. Anti-CCR3 treatment may have potential as a new therapy for retinopathies with retinal neovascularization such as diabetic retinopathy and retinopathy of prematurity.

[Evaluation of Diabetic Retinopathy with Ultra-wide Field Fluorescein Angiography].

PURPOSE: The ultra-wide field scanning laser ophthalmoscope (Optos 200Tx, Optos, Scotland, UK) provides retinal images of 200 degrees in a single capture which covers more than 80% of the retina. Fluorescein angiography with Optos 200Tx is useful to visualize the microcirculations of peripheral retina. It allows to evaluate peripheral pathology more precisely than conventional fundus photography. The purpose of this study was to evaluate the fluorescein angiography findings of eyes in diabetic retinopathy patients by using ultra-wide field fluoresrein angiography. SUBJECTS AND METHODS: Ultra-wide field fluoresrein angiography was performed on 154 eyes of 77 patients with diabetic retinopathy. We divided the fundus into three zones, the posterior pole, the mid-periphery and the far-periphery. Capillary non-perfusion areas and retinal neovascularization in each zone were evaluated. RESULTS: One hundred thirty eyes (84%) exhibited capillary non-perfusion areas. Ten eyes (7.7%) were found to have a capillary non-perfusion area only in the far-periphery. Seventy two eyes (47%) exhibited retinal neovascularization. Retinal neovascularization was observed most in the mid-periphery (58 eyes; 81%); 8 eyes (11%) were found to have retinal neovascularization in the far-periphery. CONCLUSION: Ultra-wide field fluorescein angiography revealed the microcirculatory disturbance in the peripheral retina of diabetic patients not evident by conventional fundus photography and it was useful for evaluating the status of the diabetic retinopathy.

Long-Term Prognosis of Patients with Polypoidal Choroidal Vasculopathy Treated with Photodynamic Therapy.

We evaluated the long-term prognosis of the eyes of patients with polypoidal choroidal vasculopathy (PCV) treated with photodynamic therapy (PDT). In total, 60 eyes of 57 patients diagnosed with PCV and treated with PDT were reviewed retrospectively in real-world settings. The best-corrected visual acuity (BCVA), central retinal thickness (CRT), anatomical findings (vision-threatening findings), and treatment history were assessed. In total, 38 eyes underwent PDT as the initial treatment (initial PDT group) and 22 eyes underwent PDT as a rescue treatment (rescue PDT group). In the initial PDT group, 11 eyes (29%) did not require additional therapy throughout the observation period and maintained good BCVA. A total of 27 eyes (71%) underwent additional treatments and the mean BCVA was only stabilized for 2 years; thereafter, decreased vision occurred even with additional treatments. In the rescue PDT group, 22 eyes (95%) required additional treatment. Hard exudate, serous pigment epithelial detachment, and the total vision-threatening score were related to worse BCVA. Initial PDT may be effective in about 30% of cases with preservation of good vision and no need for additional treatment. However, patients with received rescue PDT needed additional treatment in most cases and the vision decreased in many cases.

Nucleoside reverse transcriptase inhibitors and Kamuvudines inhibit amyloid-ß induced retinal pigmented epithelium degeneration.

Nonfibrillar amyloid-ß oligomers (AßOs) are a major component of drusen, the sub-retinal pigmented epithelium (RPE) extracellular deposits characteristic of age-related macular degeneration (AMD), a common cause of global blindness. We report that AßOs induce RPE degeneration, a clinical hallmark of geographic atrophy (GA), a vision-threatening late stage of AMD that is currently untreatable. We demonstrate that AßOs induce activation of the NLRP3 inflammasome in the mouse RPE in vivo and that RPE expression of the purinergic ATP receptor P2RX7, an upstream mediator of NLRP3 inflammasome activation, is required for AßO-induced RPE degeneration. Two classes of small molecule inflammasome inhibitors-nucleoside reverse transcriptase inhibitors (NRTIs) and their antiretrovirally inert modified analog Kamuvudines-both inhibit AßOs-induced RPE degeneration. These findings crystallize the importance of P2RX7 and NLRP3 in a disease-relevant model of AMD and identify inflammasome inhibitors as potential treatments for GA.

DDX17 is an essential mediator of sterile NLRC4 inflammasome activation by retrotransposon RNAs.

Detection of microbial products by multiprotein complexes known as inflammasomes is pivotal to host defense against pathogens. Nucleotide-binding domain leucine-rich repeat (NLR) CARD domain containing 4 (NLRC4) forms an inflammasome in response to bacterial products; this requires their detection by NLR family apoptosis inhibitory proteins (NAIPs), with which NLRC4 physically associates. However, the mechanisms underlying sterile NLRC4 inflammasome activation, which is implicated in chronic noninfectious diseases, remain unknown. Here, we report that endogenous short interspersed nuclear element (SINE) RNAs, which promote atrophic macular degeneration (AMD) and systemic lupus erythematosus (SLE), induce NLRC4 inflammasome activation independent of NAIPs. We identify DDX17, a DExD/H box RNA helicase, as the sensor of SINE RNAs that licenses assembly of an inflammasome comprising NLRC4, NLR pyrin domain­containing protein 3, and apoptosis-associated speck-like protein­containing CARD and induces caspase-1 activation and cytokine release. Inhibiting DDX17-mediated NLRC4 inflammasome activation decreased interleukin-18 release in peripheral blood mononuclear cells of patients with SLE and prevented retinal degeneration in an animal model of AMD. Our findings uncover a previously unrecognized noncanonical NLRC4 inflammasome activated by endogenous retrotransposons and provide potential therapeutic targets for SINE RNA­driven diseases.

Alu complementary DNA is enriched in atrophic macular degeneration and triggers retinal pigmented epithelium toxicity via cytosolic innate immunity.

Long interspersed nuclear element-1 (L1)­mediated reverse transcription (RT) of Alu RNA into cytoplasmic Alu complementary DNA (cDNA) has been implicated in retinal pigmented epithelium (RPE) degeneration. The mechanism of Alu cDNA­induced cytotoxicity and its relevance to human disease are unknown. Here we report that Alu cDNA is highly enriched in the RPE of human eyes with geographic atrophy, an untreatable form of age-related macular degeneration. We demonstrate that the DNA sensor cGAS engages Alu cDNA to induce cytosolic mitochondrial DNA escape, which amplifies cGAS activation, triggering RPE degeneration via the inflammasome. The L1-extinct rice rat was resistant to Alu RNA­induced Alu cDNA synthesis and RPE degeneration, which were enabled upon L1-RT overexpression. Nucleoside RT inhibitors (NRTIs), which inhibit both L1-RT and inflammasome activity, and NRTI derivatives (Kamuvudines) that inhibit inflammasome, but not RT, both block Alu cDNA toxicity, identifying inflammasome activation as the terminal effector of RPE degeneration.

Three-dimensional analysis of choroidal vessels in eyes with Vogt-Koyanagi-Harada disease before and after treatment.

OBJECTIVE: To investigate a 3-dimensional analysis of choroidal vessels using binarization of ultrawide-field indocyanine green angiography (UWFICGA) images and swept-source optical coherence tomography (SS-OCT) images before and after treatment in eyes with Vogt-Koyanagi-Harada (VKH) disease. METHODS: Seven eyes of 7 patients (2 men and 5 women; mean age, 48.3 years) with VKH disease and 8 control eyes of 8 patients (4 men and 4 women; mean age, 47.6 years) who visited from August 1, 2015, through July 31, 2017, were enrolled. UWF fluorescein angiography images were subtracted from UWFICGA images in all patients to evaluate the choroidal vessel densities. A vertical analysis of the choroid also was performed in the same way with SS-OCT images. RESULTS: At the acute stage of VKH disease, the mean choroidal vascular densities in both posterior and mid-peripheral areas were significantly (p < 0.01) lower than in control eyes, and recovered after the treatment. In addition, the choroidal stroma significantly (p < 0.01) decreased after the treatment and the choroidal lumina significantly (p < 0.01) increased. CONCLUSIONS: Current results suggest that diffuse cellular infiltration into the choroidal stroma might compress choroidal vessels and the change would resolve after treatment.

Voluntary Exercise Suppresses Choroidal Neovascularization in Mice.

Purpose: To determine the effect of voluntary exercise on choroidal neovascularization (CNV) in mice. Methods: Age-matched wild-type C57BL/6J mice were housed in cages equipped with or without running wheels. After four weeks of voluntary running or sedentariness, mice were subjected to laser injury to induce CNV. After surgical recovery, mice were placed back in cages with or without exercise wheels for seven days. CNV lesion volumes were measured by confocal microscopy. The effect of wheel running only in the seven days after injury was also evaluated. Macrophage abundance and cytokine expression were quantified. Results: In the first study, exercise-trained mice exhibited a 45% reduction in CNV volume compared to sedentary mice. In the replication study, a 32% reduction in CNV volume in exercise-trained mice was observed (P = 0.029). Combining these two studies, voluntary exercise was found to reduce CNV by 41% (P = 0.0005). Exercise-trained male and female mice had similar CNV volumes (P = 0.99). The daily running distance did not correlate with CNV lesion size. Exercise only after the laser injury without a preconditioning period did not reduce CNV size (P = 0.41). CNV lesions of exercise-trained mice also exhibited significantly lower F4/80+ macrophage staining and Vegfa and Ccl2 mRNA expression. Conclusions: These findings provide the first experimental evidence that voluntary exercise improves CNV outcomes. These studies indicate that exercise before laser treatment is required to improve CNV outcomes.

Repurposing anti-inflammasome NRTIs for improving insulin sensitivity and reducing type 2 diabetes development.

Innate immune signaling through the NLRP3 inflammasome is activated by multiple diabetes-related stressors, but whether targeting the inflammasome is beneficial for diabetes is still unclear. Nucleoside reverse-transcriptase inhibitors (NRTI), drugs approved to treat HIV-1 and hepatitis B infections, also block inflammasome activation. Here, we show, by analyzing five health insurance databases, that the adjusted risk of incident diabetes is 33% lower in patients with NRTI exposure among 128,861 patients with HIV-1 or hepatitis B (adjusted hazard ratio for NRTI exposure, 0.673; 95% confidence interval, 0.638 to 0.710; P < 0.0001; 95% prediction interval, 0.618 to 0.734). Meanwhile, an NRTI, lamivudine, improves insulin sensitivity and reduces inflammasome activation in diabetic and insulin resistance-induced human cells, as well as in mice fed with high-fat chow; mechanistically, inflammasome-activating short interspersed nuclear element (SINE) transcripts are elevated, whereas SINE-catabolizing DICER1 is reduced, in diabetic cells and mice. These data suggest the possibility of repurposing an approved class of drugs for prevention of diabetes.

cGAS drives noncanonical-inflammasome activation in age-related macular degeneration.

Geographic atrophy is a blinding form of age-related macular degeneration characterized by retinal pigmented epithelium (RPE) death; the RPE also exhibits DICER1 deficiency, resultant accumulation of endogenous Alu-retroelement RNA, and NLRP3-inflammasome activation. How the inflammasome is activated in this untreatable disease is largely unknown. Here we demonstrate that RPE degeneration in human-cell-culture and mouse models is driven by a noncanonical-inflammasome pathway that activates caspase-4 (caspase-11 in mice) and caspase-1, and requires cyclic GMP-AMP synthase (cGAS)-dependent interferon-ß production and gasdermin D-dependent interleukin-18 secretion. Decreased DICER1 levels or Alu-RNA accumulation triggers cytosolic escape of mitochondrial DNA, which engages cGAS. Moreover, caspase-4, gasdermin D, interferon-ß, and cGAS levels were elevated in the RPE in human eyes with geographic atrophy. Collectively, these data highlight an unexpected role of cGAS in responding to mobile-element transcripts, reveal cGAS-driven interferon signaling as a conduit for mitochondrial-damage-induced inflammasome activation, expand the immune-sensing repertoire of cGAS and caspase-4 to noninfectious human disease, and identify new potential targets for treatment of a major cause of blindness.

Densitometry of Choroidal Vessels in Eyes With and Without Central Serous Chorioretinopathy by Wide-Field Indocyanine Green Angiography.

PURPOSE: To develop a new method to quantify the choroidal vessel density by binarizing ultra-wide-field indocyanine green angiography (ICGA) images and determine whether values are altered in diseased eyes. DESIGN: Reliability and validity analysis. METHODS: Ultra-wide-field fluorescein angiography (FA) and ICGA images were obtained using an ultra-wide-field imaging device (Optos California ultra-wide-field imaging device; Dunfermline, Scotland, UK) in 11 eyes of 11 patients without chorioretinal diseases. The angiographic signals of the choroidal vessels were determined by subtracting those of the retinal vasculature and optic disc on the FA images from the ICGA images, binarized by Niblack's method, and the choroidal vessel density calculated. Reproducibility of the method was assessed by calculating the coefficient of variance, coefficient of repeatability, and intraclass correlation coefficient. The relationships between age, spherical equivalent refractive error (SERE), and intraocular pressure and the vasculature density were assessed. To investigate possible impacts of chorioretinal diseases on the vasculature density, 10 eyes of 7 patients with central serous chorioretinopathy (CSC) were compared with the 11 control eyes. RESULTS: Choroidal vessels were contrasted by binarizing ICGA images. The method to quantify the choroidal vessel density showed high reproducibility. The SERE was correlated significantly (r = 0.573, P < .05) with the vasculature density. In the 11 control eyes, the vasculature density was 34.26% ± 0.77% in the entire area, 31.37% ± 0.97% in the superior portion, 36.98% ± 0.88% in the inferior portion, 37.01% ± 1.44% in the posterior portion, and 34.17% ± 0.77% in the peripheral portion. In eyes with CSC, the density was significantly (P < .05) higher: 36.46% ± 0.49%, 34.02% ± 0.97%, 38.65% ± 0.27%, 41.04% ± 0.82%, and 36.36% ± 0.51%, respectively. CONCLUSIONS: Binarization of ultra-wide-field ICGA images enabled quantification of the choroidal vessel density, which was altered in eyes with CSC. This method of measuring the choroidal vessel density may provide new insights into diagnosing and treating chorioretinal diseases.

Areas of nonperfusion in peripheral retina of eyes with pathologic myopia detected by ultra-widefield fluorescein angiography.

PURPOSE: We investigated the vascular system in the far peripheral retina in eyes with pathologic myopia by ultra-widefield fluorescein angiography (FA). METHODS: We analyzed retrospectively 230 with pathologic myopia (myopic refractive error >8 diopters [D] or axial length >26.5 mm) and 42 emmetropic (refractive error < ± 2 D) controls who were examined with ultra-widefield FA by the Optos P200 system. Far peripheral retina was defined as the area anterior to the ampullae of the vortex veins. RESULTS: Retinal capillary telangiectasia was observed in the far periphery of 34 of 42 (81.0%) emmetropic eyes and in 90 of 115 (78.3%) highly myopic eyes. Retinal capillary microaneurysms were observed in 13 of 42 (31.0%) emmetropic eyes and in 60 of 115 (52.2%) eyes with pathologic myopia. The differences in the incidences of these two lesions were not significant. Areas of nonperfusion in the far periphery were found in two of 42 (4.8%) emmetropic eyes and in 95 of 115 (82.6%) eyes with pathologic myopia. In these myopic eyes, the arterioles and venules had an abrupt ending, and in advanced cases, the perfused area was limited to just beyond the staphyloma border. None of the eyes developed retinal neovascularization. Statistical analyses showed that the highly myopic patients with avascular areas in the far periphery were significantly older, and had significantly longer axial length. CONCLUSIONS: Areas of nonperfusion in the far periphery are common in eyes with pathologic myopia. Retinal vasculature in the far periphery is significantly altered in eyes with pathologic myopia, and this may be due to a mechanical stretching.

A case of retinopathy of prematurity treated by pattern scan laser photocoagulation.

We experienced a case of retinopathy of prematurity that was successfully treated with pattern scan laser. Pattern scan laser treatment should be considered as one treatment option for Retinopathy of Prematurity.

Transient tractional retinal detachment in an eye with retinitis pigmentosa.

We present a case of retinitis pigmentosa with vitreoretinal traction-associated retinal detachment. The retinal detachment was detected in the nasal periphery. No retinal breaks and no active vascular leakage were observed by fundus scopy and fluorescein angiography, respectively. However, 8 months later, the tractional retinal detachment was spontaneously resolved with posterior vitreous detachment.