Lamivudine Inhibits Alu RNA-induced Retinal Pigment Epithelium Degeneration via Anti-inflammatory and Anti-senescence Activities.

Purpose: Accumulation of the long noncoding Alu element RNA activates the NLRP3 inflammasome and leads to retinal pigment epithelium (RPE) cell death, a key event in the pathogenesis of geographic atrophy during late-stage age-related macular degeneration. Lamivudine (3TC) is a nucleoside analog reverse transcriptase inhibitor known to inhibit the NLRP3 inflammasome. Currently, the intracellular response of the senescence marker p16Ink4a to the long noncoding RNA is being actively studied. The present study aimed to assess the efficacy of 3TC against Alu RNA-induced RPE inflammation and senescence by evaluating changes in expression of the proinflammatory cytokines IL-18 and IL-1ß and of p16INK4a in RPE cells. Methods: Cultured human RPE cells and in vivo mouse RPE cells were transfected with an in vitro-transcribed Alu RNA, and changes in IL-18, IL-1ß, and p16Ink4a expression measured in the presences of 3TC or 3,4-(M)CA as a negative control. Results: Treatment with 3TC markedly reduced Alu RNA-induced expression of IL-18 and IL-1ß in human and mouse RPE cells compared with the negative control. Further, Alu RNA-induced p16INK4a expression was suppressed by 3TC in human RPE cells. Conclusions: Our data suggest that Alu RNA accumulation contributes to RPE cell senescence in age-related macular degeneration and that this pathogenic process can be suppressed by 3TC. Translational Relevance: Further verifying this study leads to potential targets for age-related macular degeneration therapy.

Diacron reactive oxygen metabolites and biological antioxidant potential tests for patients with age-related macular degeneration.

BACKGROUND: Previously, we showed that serum malondialdehyde (MDA) was significantly higher in patients with neovascular age-related macular degeneration (nAMD) than in those without AMD. The Diacron reactive oxygen metabolites (d-ROMs) and biological antioxidant potential (BAP) tests are known markers of oxidative stress. The aim of this study was to use d-ROMs and BAP tests to evaluate changes in systemic oxidative stress in patients with nAMD. METHODS: Blood serum samples were collected from 34 patients with nAMD (mean age: 76.5 ± 7.7 years; 22 men) and 20 control subjects (mean age: 62.9 ± 14.0 years; 10 men), and d-ROMs and BAP tests were examined. RESULTS: In men, the mean level of d-ROMs for the nAMD patients was significantly higher than that for the controls (312.0 ± 52.4 vs. 275.1 ± 45.5 U.CARR, respectively; P < .05). There was a significant correlation between d-ROM level and CNV lesion area in the male nAMD group (r = .42, P = .05). There were no significant differences in mean BAP test results between the nAMD patients and controls for either sex (men: 2241 ± 549 vs. 2136 ± 246 µmol/L; women: 2263 ± 292 vs. 2335 ± 161 µmol/L). CONCLUSION: The d-ROMs test may provide a useful indicator of nAMD in men but not in women.

n-3 Fatty Acid and Its Metabolite 18-HEPE Ameliorate Retinal Neuronal Cell Dysfunction by Enhancing Müller BDNF in Diabetic Retinopathy.

Diabetic retinopathy (DR) is a widespread vision-threatening disease, and neuroretinal abnormality should be considered as an important problem. Brain-derived neurotrophic factor (BDNF) has recently been considered as a possible treatment to prevent DR-induced neuroretinal damage, but how BDNF is upregulated in DR remains unclear. We found an increase in hydrogen peroxide (H2O2) in the vitreous of patients with DR. We confirmed that human retinal endothelial cells secreted H2O2 by high glucose, and H2O2 reduced cell viability of MIO-M1, Müller glia cell line, PC12D, and the neuronal cell line and lowered BDNF expression in MIO-M1, whereas BDNF administration recovered PC12D cell viability. Streptozocin-induced diabetic rats showed reduced BDNF, which is mainly expressed in the Müller glia cell. Oral intake of eicosapentaenoic acid ethyl ester (EPA-E) ameliorated BDNF reduction and oscillatory potentials (OPs) in electroretinography (ERG) in DR. Mass spectrometry revealed an increase in several EPA metabolites in the eyes of EPA-E-fed rats. In particular, an EPA metabolite, 18-hydroxyeicosapentaenoic acid (18-HEPE), induced BDNF upregulation in Müller glia cells and recovery of OPs in ERG. Our results indicated diabetes-induced oxidative stress attenuates neuroretinal function, but oral EPA-E intake prevents retinal neurodegeneration via BDNF in Müller glia cells by increasing 18-HEPE in the early stages of DR.

In Vitro Epiretinal Membrane Model and Antibody Permeability: Relationship With Anti-VEGF Resistance in Diabetic Macular Edema.

Purpose: Diabetic macular edema (DME) is characterized by an accumulation of fluid in the macula due to diabetic retinopathy. Currently, anti-VEGF drugs are the standard treatment worldwide for DME. This study aimed to assess whether the existence of epiretinal membrane (ERM) affects anti-VEGF efficacy, due to reduced permeability of the antibody through the ERM. Methods: We retrospectively examined clinical data of DME patients who underwent anti-VEGF treatment and evaluated whether clinical differences existed between DME eyes with ERM and those without ERM. We then created an in vitro ERM model using MIO-M1, ARPE-19, and NTI-4 cells on Transwell membranes and evaluated antibody permeability through this in vitro ERM model using fluorescently labeled antibodies. Results: Central retinal thickness (CRT) change between before and 1 month after first anti-VEGF treatment, as well as final CRT and final visual acuity 12 months after first anti-VEGF treatment, significantly differed between DME eyes with ERM and those without ERM. The in vitro ERM model led to production of collagen I in a manner similar to that of human ERM specimens. Fluorescence intensity of the lower chamber of the in vitro ERM model was significantly reduced in a dose-dependent manner. Conclusions: Clinical data analysis indicated that the existence of ERM in DME eyes lowered the efficacy of anti-VEGF treatment. Reduced antibody permeability through the in vitro ERM model suggested ERM presence was associated with resistance to anti-VEGF treatment in DME eyes with ERM.

Biological Characteristics of Subsilicone Oil Fluid and Differences With Other Ocular Humors.

PURPOSE: Subsilicone oil fluid (SOF) in eyes with silicone oil (SO) endotamponade possibly has a role in complications (e.g., vision loss); thus, we aimed to examine inflammatory cytokine and electrolyte levels and retinal glial cell viability in SOF. METHODS: We measured major inflammatory cytokine levels and electrolytes in SOF and compared them with those in vitreous fluid (VF) and anterior chamber fluid (ACF). We analyzed the correlation between inflammatory cytokines and retinal thickness in SO-filled eyes. Further, we measured the MIO-M1 cell viability in medium with SOF and compared it with that containing VF. RESULTS: We collected and examined 57 SOF, 22 ACF, and 21 VF samples from eyes with PVR, PDR, RD, and MH. Interleukin (IL)-8 and monocyte chemoattractant protein (MCP)-1 levels in SOF were significantly higher than those in ACF. There was no significant difference for all cytokines between SOF and VF. Retinal thickness changes during SO endotamponade were not correlated with the presence of any inflammatory cytokines. Levels of ferrous iron, but not of potassium, showed a significant decrease in SOF compared with VF. The WST-1 assay showed that SOF-added medium induced higher MIO-M1 cell viability than VF-added medium. CONCLUSIONS: We found no significant correlation between the change in the retinal thickness and cytokine levels, but SOF contains higher concentrations of cytokines and lower concentrations of ferrous iron and can be biologically distinguished from ACF and VF. TRANSLATIONAL RELEVANCE: Novel knowledge of inflammatory cytokine levels and electrolytes in SOF provides better understanding of pathology of SO-filled eyes.