Systemic levels of interleukin-6 in patients with age-related macular degeneration: a systematic review and meta-analysis

A Systematic Review and Meta-Analysis Association Between Periodontitis and Age-Related Macular Degeneration: Potential for Personalized Approach

Background/Objectives: Periodontitis is a chronic inflammatory disease that leads to systemic low-grade inflammation. Systemic low-grade inflammation has been found in patients with age-related macular degeneration (AMD). In this systematic review and meta-analysis, we evaluated the association between periodontitis and AMD. Methods: We searched 11 scientific literature databases on 16th December 2024 for studies of a diagnosis of periodontitis and prevalent or incident AMD. Eligible studies underwent a qualitative review and meta-analysis of the association. Study selection, data extraction, and risk of bias within studies were made in duplicate by two authors and conferred with a senior author. Results: Seven studies eligible for review included in total 149,217 individuals. Across the seven studies, different study designs, diagnoses and definitions of periodontitis, and diagnosis and definitions of AMD were employed. Our meta-analysis showed an association between periodontitis and AMD with an odds ratio of 1.42 (95% CI: 1.12 to 1.78; p = 0.003). Conclusions: Periodontitis is significantly associated with AMD. Unlike genetic predisposition and high age, which are important risk factors of AMD that cannot be modified, periodontitis is a risk factor that can be treated and potentially eliminated, thus allowing for a personalized approach for risk elimination in AMD. Attention should be given to the dental health of patients at risk of AMD.

Systemic inflammatory response index as a novel biomarker for age-related macular degeneration: a cross-sectional study from NHANES (2005-2008)

Background

Chronic low-grade systemic inflammation plays a significant role in age-related macular degeneration (AMD) pathogenesis. The systemic inflammatory response index (SIRI), a novel inflammatory marker, may predict various diseases. However, data on the relationship between SIRI and AMD are limited. This study examines the relationship between SIRI and AMD and assesses its potential as a predictive biomarker.

Methods

A cross-sectional analysis of the National Health and Nutrition Examination Survey (NHANES) data from 2005 to 2008 was conducted on participants aged ≥40 years with SIRI and AMD status data. Multivariable logistic regression models adjusted for confounders were used to assess the association. Sensitivity and subgroup analyses, along with restricted cubic spline (RCS) curve analysis, were performed.

Results

Among 5,365 participants, 425 (7.9%) had AMD. The median SIRI was higher in AMD patients (1.23 vs. 1.04, p < 0.001). Higher SIRI was independently associated with increased odds (adjusted OR: 1.18, 95% CI:1.07-1.29, p = 0.001). RCS analyses revealed a dose-response relationship (p = 0.002). Subgroup analyses showed a positive association in male participants, individuals with hypertension, individuals with obesity, and non-smokers. Higher SIRI levels were independently associated with increased AMD risk (adjusted OR: 1.27, 95% CI: 1.03-1.56, p = 0.023).

Conclusion

Elevated SIRI is independently associated with increased AMD risk in the U.S. population. SIRI may serve as a biomarker for identifying high-risk individuals, enabling early intervention. The cross-sectional design limits causal inference, and unmeasured confounders may affect the results. SIRI could potentially serve as a non-invasive biomarker for AMD risk, pending further validation through longitudinal studies.

Treatment Interval Progression and Adherence to Observe-and-Plan Regimen for Neovascular Age-Related Macular Degeneration Treated with Aflibercept 2 mg

INTRODUCTION

Treatment burden of anti-vascular endothelial growth factor (VEGF) therapy for neovascular age-related macular degeneration (AMD) can be reduced with the Observe-and-Plan (O&P) regimen, which allows for an individualized treatment while reducing the number of injections and assessment visits. In this study, we evaluate detailed characteristics of treatment interval adjustment through individual follow-ups and evaluate adherence to the O&P regimen in a real-world setting in one of the largest centers in Europe.

METHODS

This was a retrospective cohort study of treatment-naïve eyes with neovascular AMD that were treated with intravitreal aflibercept 2 mg in an O&P regimen who had persisting exudation after completion of loading dose. We evaluated decisions on adjustment of treatment intervals and adherence to the O&P regimen from a total of 5 follow-up visits. Data from visits and decision on treatment intervals were extracted from a treatment database.

RESULTS

A total of 561 eyes were eligible for this study. Treatment intervals gradually increased from a 4-weeks interval (loading dose) to a wide distribution of intervals from 4-weeks to 12-weeks, and at the 5th follow-up 24.9% were followed without any treatment. In total, 209 eyes (49.5%) at the 5th follow-up (of 422 eyes present at the 5th follow-up) adhered to the treatment algorithm.

CONCLUSION

Aflibercept 2 mg in an O&P treatment regimen leads to a variety of treatment intervals, and some eyes may be overtreated. An important proportion of eyes deviate from the intended O&P treatment regimen. Our study contributes to understanding real-world implications of personalized treatment regimens.

Systemic oxidative stress levels and their associations with the risk of neovascular age-related macular degeneration and treatment response

PURPOSE

To investigate the association between oxidative stress (OS) and both the risk of neovascular age-related macular degeneration (nAMD) and the treatment response to intravitreal anti-vascular endothelial growth factor injections (anti-VEGF IVIs).

METHODS

This retrospective study included 46 treatment-naïve nAMD eyes of 46 patients (26 male and 20 female) who received anti-VEGF IVIs with a "treat-and-extend" regimen following an initial loading phase for one year. The patients were divided into two groups according to the total number of anti-VEGF IVIs administered during the year: the "effective" group and the "resistant" group. OS was evaluated by diacron reactive oxygen metabolites (d-ROMs), biological antioxidant potential (BAP), and skin autofluorescence (SAF) at baseline. For comparison, 54 control subjects were recruited.

RESULTS

There were no significant differences in d-ROM or BAP levels between control subjects and nAMD patients, regardless of sex, whereas SAF levels were higher in nAMD patients overall and in male nAMD patients than in controls (P < 0.001 for both). The effective and resistant groups included 30 and 16 eyes, respectively. Among the male nAMD patients, the effective and resistant groups had similar baseline characteristics, including age, smoking history, visual acuity, and central macular thickness; however, the resistant group had higher SAF levels (effective vs. resistant: 2.3 vs. 2.6 arbitrary units [AU]; P = 0.02). This finding was further supported by a multiple logistic regression analysis, which showed that the odds ratio for SAF was 1.57 per 0.1 AU increase (P = 0.01).

CONCLUSION

SAF levels were significantly higher in nAMD patients than in controls. The total number of anti-VEGF IVIs required over one year in male nAMD patients depended on SAF levels, suggesting that the SAF levels may serve as a potential biomarker for the response to anti-VEGF IVIs in nAMD.

IL-6 Exacerbates Oxidative Damage of RPE Cells by Indirectly Destabilizing the mRNA of DNA Repair Genes

Chronic inflammation has been associated with the progression of age-related macular degeneration (AMD) and diabetic retinopathy (DR), and the levels of various inflammatory factors are significantly increased in intraocular fluids of patients with AMD and DR. Therefore, elucidating the roles of inflammatory factors in the oxidative damage of RPE cells will help uncover the pathogenesis of AMD and DR. We have previously demonstrated that E2F1 plays an important role in the antioxidant capacity of RPE cells. Here, our transcriptome analysis shows that E2F1 affected the expressions of DNA repair genes in RPE cells. In addition, we found that E2F1 transactivated the splicing factor SRSF1. SRSF1 knockdown promoted DNA oxidative damage and apoptosis and decreased the mRNA stability of DNA repair genes XRCC2, POLK and LIG4 in RPE cells. Moreover, we found that SRSF1 could bind to the RNA stabilizing factor MATR3, and knockdown of the latter affected the mRNA stability of these DNA repair genes. Notably, interleukin-6 (IL-6), an inflammatory factor upregulated in intraocular fluids of patients with AMD and DR, decreased SRSF1 expression by inducing acetylation of E2F1 at the K125 position. Consistently, SRSF1 overexpression relieved IL-6-induced DNA oxidative damage and apoptosis in RPE cells. In vivo experiment results also confirmed that IL-6 could aggravate retinal oxidative damage. In conclusion, high levels of IL-6 in the eyes of patients with AMD and DR destabilize the mRNAs of DNA repair genes by disrupting the expression of SRSF1, leading to abnormal repair of DNA oxidative damage in RPE cells.

Intravitreal Metformin Protects Against Choroidal Neovascularization and Light-Induced Retinal Degeneration

Neovascular age-related macular degeneration (nAMD), a leading cause of blindness in older adults, presents a challenging pathophysiology involving choroidal neovascularization (CNV) and retinal degeneration. Current treatments relying on intravitreal (IVT) administration of anti-angiogenic agents are costly and of moderate effectiveness. Metformin, the common anti-diabetic drug, has been associated with decreased odds of developing AMD. Studies have shown that metformin can mitigate cellular aging, neoangiogenesis, and inflammation across multiple diseases. This preclinical study assessed metformin's impact on vessel growth using choroidal explants before exploring IVT metformin's effects on laser-induced CNV and light-induced retinal degeneration in C57BL/6J and BALB/cJ mice, respectively. Metformin reduced new vessel growth in choroidal explants in a dose-dependent relationship. Following laser induction, IVT metformin suppressed CNV and decreased peripheral infiltration of IBA1+ macrophages/microglia. Furthermore, IVT metformin protected against retinal thinning in response to light-induced degeneration. IVT metformin downregulated genes in the choroid and retinal pigment epithelium which are associated with angiogenesis and inflammation, two key processes that drive nAMD progression. These findings underscore metformin's capacity as an anti-angiogenic and neuroprotective agent, demonstrating this drug's potential as an accessible option to help manage nAMD.

Long-acting delivery and therapies for neovascular age-related macular degeneration

INTRODUCTION

Neovascular age-related macular degeneration (nAMD) represents a leading cause of severe visual impairment in individuals over 50 years of age in developed nations. Intravitreal anti-vascular endothelial growth factor (VEGF) injections have become the standard of care for treating nAMD; however, monthly or bimonthly dosing represents significant time and cost burden due to the disease's chronic nature and limited medication half-life.

AREAS COVERED

This review summarizes innovative therapeutics and delivery methods for nAMD. Emerging methods for extended drug delivery include high molar concentration anti-VEGF drugs, intravitreal sustained-release polymers and devices, reservoirs for intravitreal delivery, suprachoroidal delivery of small molecular suspensions and gene therapy biofactories. In addition to VEGF-A, therapies targeting inhibition of VEGF-C and D, the angiopoetin-2 (Ang-2)/Tie-2 pathway, tyrosine kinases, and integrins are reviewed.

EXPERT OPINION

The evolving therapeutic landscape of nAMD is rapidly expanding our toolkit for effective and durable treatment. Recent FDA approvals of faricimab (Vabysmo) and high-dose aflibercept (Eylea HD) for nAMD with potential extension of injection intervals up to four months have been promising developments for patients and providers alike. Further research and innovation, including novel delivery techniques and pharmacologic targets, is necessary to validate the efficacy of developing therapeutics and characterize real-world outcomes, demonstrating promise in expanding treatment durability.

An examination of the mechanisms driving the therapeutic effects of an AAV expressing a soluble variant of VEGF receptor-1

In previous animal model studies, we demonstrated the potential of rAAV2-sVEGFRv-1, which encodes a truncated variant of the alternatively spliced soluble version of VEGF receptor-1 (VEGFR1), as a human gene therapy for age-related macular degeneration (AMD) and diabetic retinopathy (DR). Here, we elucidate in vitro some of the mechanisms by which rAAV2-sVEGFRv-1 exerts its therapeutic effects. Human umbilical vein endothelial cells (HUVECs) were infected with rAAV2-sVEGFRv-1 or a control virus vector in the presence of members of the VEGF family to identify potential binding partners via ELISA, which showed that VEGF-A, VEGF-B, and placental growth factor (PlGF) are all ligands of its transgene product. In order to determine the effects of rAAV2-sVEGFRv-1 on cell proliferation and permeability, processes that are important to the progression AMD and DR, HUVECs were infected with the therapeutic virus vector under the stimulation of VEGF-A, the major driver of the neovascularization that characterizes the forms of these conditions most associated with vision loss. rAAV2-sVEGFRv-1 treatment, as a result, markedly reduced the extent to which these processes occurred, with the latter determined by measuring zonula occludens 1 expression. Finally, the human microglial HMC3 cell line was used to show the effects of the therapeutic virus vector upon inflammatory processes, another major contributor to angiogenic eye disease pathophysiology, with rAAV2-sVEGFRv-1 reducing therein the secretion of pro-inflammatory cytokines interleukin (IL)-1β and IL-6. Combined with our previously published in vivo data, the in vitro activity of the expressed transgene here further demonstrates the great promise of rAAV2-sVEGFRv-1 as a potential human gene therapeutic for addressing angiogenic ocular conditions.

Glycative stress as a cause of macular degeneration

People are living longer and rates of age-related diseases such as age-related macular degeneration (AMD) are accelerating, placing enormous burdens on patients and health care systems. The quality of carbohydrate foods consumed by an individual impacts health. The glycemic index (GI) is a kinetic measure of the rate at which glucose arrives in the blood stream after consuming various carbohydrates. Consuming diets that favor slowly digested carbohydrates releases sugar into the bloodstream gradually after consuming a meal (low glycemic index). This is associated with reduced risk for major age-related diseases including AMD, cardiovascular disease, and diabetes. In comparison, consuming the same amounts of different carbohydrates in higher GI diets, releases glucose into the blood rapidly, causing glycative stress as well as accumulation of advanced glycation end products (AGEs). Such AGEs are cytotoxic by virtue of their forming abnormal proteins and protein aggregates, as well as inhibiting proteolytic and other protective pathways that might otherwise selectively recognize and remove toxic species. Using in vitro and animal models of glycative stress, we observed that consuming higher GI diets perturbs metabolism and the microbiome, resulting in a shift to more lipid-rich metabolomic profiles. Interactions between aging, diet, eye phenotypes and physiology were observed. A large body of laboratory animal and human clinical epidemiologic data indicates that consuming lower GI diets, or lower glycemia diets, is protective against features of early AMD (AMDf) in mice and AMD prevalence or AMD progression in humans. Drugs may be optimized to diminish the ravages of higher glycemic diets. Human trials are indicated to determine if AMD progression can be retarded using lower GI diets. Here we summarized the current knowledge regarding the pathological role of glycative stress in retinal dysfunction and how dietary strategies might diminish retinal disease.

Metformin protects retinal pigment epithelium cells against H2O2-induced oxidative stress and inflammation via the Nrf2 signaling cascade

PURPOSE

Dysfunctions of retinal pigment epithelium (RPE) attributed to oxidative stress and inflammation are implicated with age-related macular degeneration (AMD). A debate on the curative role of metformin in AMD has been raised, though several recent clinical studies support the lower odds by using metformin. This study aimed to determine whether metformin could exert cytoprotection against RPE oxidative damages and the potential mechanisms.

METHODS

A cellular AMD model was established by treating ARPE-19 cells with hydrogen peroxide (H2O2) for 24 h. The reactive oxygen species (ROS) generation, expression of antioxidant enzymes, and levels of pro-inflammatory cytokines were monitored under administrations with H2O2 with/without metformin. The expression and DNA-binding activity of transcription factor erythroid-related factor 2 (Nrf2) were determined by western blot, immunofluorescence, and electrophoretic mobility shift assay. Knockout of Nrf2 was conducted by CRISPR/Cas9 gene deletion system.

RESULTS

Metformin pretreatment significantly improved the H2O2-induced low viability of ARPE-19 cells, reduced ROS production, and increased contents of antioxidative molecules. Concurrently, metformin also suppressed levels of pro-inflammatory cytokines caused by H2O2. The metformin-augmented nuclear translocation and DNA-binding activity of Nrf2 were further verified by the increased expression of its downstream targets. Genetic deletion of Nrf2 blocked the cytoprotective role of metformin.

CONCLUSION

Metformin possesses antioxidative and anti-inflammatory properties in ARPE-19 cells by activating the Nrf2 signaling. It supports the potential use for the control and prevention of AMD.

Clinical Trials and Future Outlooks of the Port Delivery System with Ranibizumab: A Narrative Review

The port delivery system (PDS) of anti-VEGF therapy provides continuous delivery of ranibizumab (RBZ). In October of 2021, the American Food and Drug Administration (FDA) approved the PDS with RBZ as a treatment option for neovascular age-related macular degeneration (nAMD). As the field of PDS with RBZ is progressing rapidly, this narrative review provides a much-needed overview of existing clinical trials as well as ongoing and upcoming trials investigating PDS with RBZ. The phase 2 LADDER trial reported that the mean time to first refill with RBZ PDS 100 mg/ml was 15.8 months (80% CI 12.1-20.6), and pharmacokinetic profiling revealed a sustained concentration of RBZ in serum and aqueous humor. Later, the phase 3 ARCHWAY trial reported that PDS with RBZ (100 mg/ml) refilled every 24 weeks was non-inferior to monthly intravitreal injection (IVI) with RBZ (0.5 mg) in patients with nAMD over 9 months and 2 years. However, patients with PDS had a higher rate of adverse events including vitreous hemorrhage and endophthalmitis. Patients indicate high treatment satisfaction with both PDS and IVI, but the lower number of treatments with PDS was reported as a preferred choice. Several ongoing and future clinical trials, of which details are discussed in this paper, are further exploring the potentials of PDS with RBZ. We conclude that the PDS provides continuous deliverance of RBZ and that clinical efficacy levels are non-inferior to IVI therapy for nAMD. Yet, a higher rate of adverse events remains a concerning detail for widespread implementation. Future studies are warranted to better understand which patients may benefit best from this treatment approach, if long-term efficacy can be sustained, and if safety of PDS can be further improved.

Exudative Progression of Treatment-Naïve Nonexudative Macular Neovascularization in Age-Related Macular Degeneration: A Systematic Review With Meta-Analyses

PURPOSE

To systematically review and report the rate of exudative progression over time in patients with nonexudative macular neovascularization (MNV) in age-related macular degeneration (AMD).

DESIGN

Systematic review with prevalence meta-analyses and individual participant meta-analysis.

METHODS

We searched 10 literature databases on March 26, 2023, for studies of consecutive patients with treatment-naïve nonexudative MNV in AMD. The primary outcome of interest was time from diagnosis to exudative progression. We conducted meta-analyses on the prevalence of exudative progression at 1 and 2 years. Where possible, we extracted individual participant data from studies and conducted an individual participant meta-analysis and explored the exudative progression using a time-to-event curve.

RESULTS

We identified 16 eligible studies with a total of 384 eyes with nonexudative MNV. Exudative progression had occurred in 20.9% (95% CI 13.1%-29.8%) of eyes at 1 year and in 30.7% (95% CI 21.8%-40.4%) at 2 years. Similar results were observed in the individual participant meta-analysis, showing exudative progression in 18.9% (95% CI 13.5%-26.3%) of eyes at 1 year and 31.3% (95% CI 24.2%-40.0%) at 2 years. Risk factors for a fast exudative progression were the presence of subretinal lipid globules, large MNV areas, rapid MNV growth, growth in pigment epithelium detachment height and width, appearance of a branching pattern, and development of a hyporeflective halo around the MNV.

CONCLUSIONS

Nonexudative MNVs in AMD are at high risk of exudative progression. Recognition of these lesions may allow for better individualized follow-up regimens in which closer monitoring may facilitate earlier diagnosis of exudative progression.

Biomarkers for the Progression of Intermediate Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a leading cause of severe vision loss worldwide, with a global prevalence that is predicted to substantially increase. Identifying early biomarkers indicative of progression risk will improve our ability to assess which patients are at greatest risk of progressing from intermediate AMD (iAMD) to vision-threatening late-stage AMD. This is key to ensuring individualized management and timely intervention before substantial structural damage. Some structural biomarkers suggestive of AMD progression risk are well established, such as changes seen on color fundus photography and more recently optical coherence tomography (drusen volume, pigmentary abnormalities). Emerging biomarkers identified through multimodal imaging, including reticular pseudodrusen, hyperreflective foci, and drusen sub-phenotypes, are being intensively explored as risk factors for progression towards late-stage disease. Other structural biomarkers merit further research, such as ellipsoid zone reflectivity and choriocapillaris flow features. The measures of visual function that best detect change in iAMD and correlate with risk of progression remain under intense investigation, with tests such as dark adaptometry and cone-specific contrast tests being explored. Evidence on blood and plasma markers is preliminary, but there are indications that changes in levels of C-reactive protein and high-density lipoprotein cholesterol may be used to stratify patients and predict risk. With further research, some of these biomarkers may be used to monitor progression. Emerging artificial intelligence methods may help evaluate and validate these biomarkers; however, until we have large and well-curated longitudinal data sets, using artificial intelligence effectively to inform clinical trial design and detect outcomes will remain challenging. This is an exciting area of intense research, and further work is needed to establish the most promising biomarkers for disease progression and their use in clinical care and future trials. Ultimately, a multimodal approach may yield the most accurate means of monitoring and predicting future progression towards vision-threatening, late-stage AMD.

Prevalence of geographic atrophy in Nordic countries and number of patients potentially eligible for intravitreal complement inhibitor treatment: A systematic review with meta-analyses and forecasting study

We systematically reviewed the literature on the prevalence of geographic atrophy (GA) in Nordic populations, conducted meta-analyses on age-stratified estimates, and calculated current and future number of patients and those potentially eligible for intravitreal complement inhibitor treatment. We followed the PRISMA guidelines, and our protocol was registered in PROSPERO. Ten databases were searched on 22 April 2023 for population-based studies of GA prevalence. Based on clinical descriptive analyses of GA and eligibility criteria of the phase III studies for intravitreal pegcetacoplan (complement C3 and C3b inhibitor), we were able to calculate the proportion of patients with GA potentially eligible for therapy. Finally, we extracted population data for Nordic countries (Denmark, Finland, Iceland, Norway, and Sweden) from Eurostat, applied prevalence statistics to the extracted census and forecasting data to estimate the number of patients with GA, and then applied the proportion eligible for intravitreal pegcetacoplan therapy. We identified six studies with a total of 10 159 individuals. Prevalence of GA was estimated to 0.4% (95% confidence intervals [CI]: 0.2%-0.8%), 1.5% (95% CI: 0.7%-2.6%), and 7.6% (95% CI: 4.6%-11.3%) for individuals aged 60-69, 70-79, and 80+ years, respectively. In Nordic countries, we estimate a total of 166 307 individuals with GA in 2023, increasing to 277 893 in 2050. Of these, 90 803 individuals in 2023, increasing to 151 730 in 2050, are potentially eligible for intravitreal complement inhibitor treatment. Considering these large numbers, our study highlights the importance of this topic in the coming years and its potential to significantly impact our clinical practice, organization, and staffing.

Assessment of aggregate index of systemic inflammation and systemic inflammatory response index in dry age-related macular degeneration: a retrospective study

Introduction

Inflammation is known to contribute to the development of age-related macular degeneration (AMD). Several inflammatory indices derived from routine complete blood counts have been proposed as biomarkers in multiple disorders.

Methods

In this study, clinical and laboratory data were retrospectively collected from medical records to assess the aggregate index of systemic inflammation (AISI) and the systemic inflammatory response index (SIRI) as potential biomarkers of systemic inflammation in patients with early diagnosis of dry AMD.

Results

The study included 90 patients with dry AMD and 270 age/sex-matched patients with cataracts as a control group. There were no significant differences in the AISI and SIRI results between the cases and controls (p = 0.16 and 0.19, respectively).

Conclusion

This suggests that AISI and SIRI may be inadequate metrics for AMD or lack sensitivity in detecting inflammatory changes. Exploring other routine blood markers may help to identify and prevent the early stages of AMD.

Association between oral metformin use and the risk of age-related macular degeneration: A systematic review with meta-analysis

Rodent studies demonstrate that oral metformin use may reduce chronic low-grade inflammation, downregulate apoptosis and extend life span. Emerging epidemiological evidence suggests that oral metformin use may protect against development of age-related macular degeneration (AMD) in humans. In this study, we systematically reviewed the literature on the association between oral metformin use and AMD in patients with type 2 diabetes and conducted a quantitative meta-analysis to provide a summary estimate of the association. We searched 12 literature databases on 10 August 2022 and identified nine eligible studies with data on a total of 1 427 074 individuals with diabetes. We found that patients with diabetes using metformin had a significantly lower odds ratio (OR) of having or developing AMD (OR 0.63; 95% CI: 0.46-0.86; p = 0.004). Our analyses also revealed that although the findings were robust in the sensitivity analysis, the Funnel plot indicated a certain publication bias towards finding a protective effect. Results of individual studies suggested inconsistent findings, as some studies found lower risk of AMD from higher total metformin exposure, whereas other studies found a higher risk of AMD from higher total metformin exposure. Taken together, there may be a link between metformin use and lower risk of AMD, but the relationship is only studied in observational studies, various sources of bias can be speculated to influence, and careful interpretation is warranted.

Is Erythrocyte Sedimentation Rate Necessary for the Initial Diagnosis of Giant Cell Arteritis?

Giant cell arteritis (GCA) is an ophthalmological emergency that can be difficult to diagnose and prompt treatment is vital. We investigated the sequential diagnostic value for patients with suspected GCA using three biochemical measures as they arrive to the clinician: first, platelet count, then C-reactive protein (CRP), and lastly, erythrocyte sedimentation rate (ESR). This retrospective cross-sectional study of consecutive patients with suspected GCA investigated platelet count, CRP, and ESR using diagnostic test accuracy statistics and odds ratios (ORs) in a sequential fashion. The diagnosis was established by experts at follow-up, considering clinical findings and tests including temporal artery biopsy. A total of 94 patients were included, of which 37 (40%) were diagnosed with GCA. Compared with those without GCA, patients with GCA had a higher platelet count (p < 0.001), CRP (p < 0.001), and ESR (p < 0.001). Platelet count demonstrated a low sensitivity (38%) and high specificity (88%); CRP, a high sensitivity (86%) and low specificity (56%); routine ESR, a high sensitivity (89%) and low specificity (47%); and age-adjusted ESR, a moderate sensitivity (65%) and moderate specificity (65%). Sequential analysis revealed that ESR did not provide additional value in evaluating risk of GCA. Initial biochemical evaluation can be based on platelet count and CRP, without waiting for ESR, which allows faster initial decision-making in GCA.

Interleukin-6 and Macular Edema: A Review of Outcomes with Inhibition

This paper describes the current literature on the molecular pathophysiology of interleukin-6 (IL-6) in the genesis of macular edema and on the outcomes with IL-6 inhibitors in the treatment of non-infectious macular edema. The role of IL-6 in the development of macular edema has been well elucidated. IL-6 is produced by multiple cells of the innate immune system and leads to a higher likelihood of developing autoimmune inflammatory diseases, such as non-infectious uveitis, through a variety of mechanisms. These include increasing the helper T-cell population over the regulatory T-cell population and leading to the increased expression of inflammatory cytokines, such as tumor necrosis factor-alpha. In addition to being key in the generation of uveitis and subsequent macular edema through these inflammatory pathways, IL-6 also can lead to the development of macular edema through other pathways. IL-6 induces the production of vascular endothelial growth factor (VEGF) and facilitates vascular leakage by downregulating tight junction proteins in retinal endothelial cells. Clinically, the use of IL-6 inhibitors has been found to be efficacious primarily in the context of treatment-resistant non-infectious uveitis and secondary macular edema. IL-6 is a key cytokine in retinal inflammation and macular edema. It is thus not surprising that the use of IL-6 inhibitors in treatment-resistant macular edema in the setting of non-infectious uveitis has been well documented as an effective treatment option. The use of IL-6 inhibitors in macular edema secondary to non-uveitic processes has only begun to be explored.

An Exploratory Study Provides Insights into MMP9 and Aβ Levels in the Vitreous and Blood across Different Ages and in a Subset of AMD Patients

Matrix metalloproteinase-9 (MMP9) and total amyloid-beta (Aβ) are prospective biomarkers of ocular ageing and retinopathy. These were quantified by ELISA in the vitreous and blood from controls (n = 55) and in a subset of age-related macular degeneration (AMD) patients (n = 12) for insights and possible additional links between the ocular and systemic compartments. Vitreous MMP9 levels in control and AMD groups were 932.5 ± 240.9 pg/mL and 813.7 ± 157.6 pg/mL, whilst serum levels were 2228 ± 193 pg/mL and 2386.8 ± 449.4 pg/mL, respectively. Vitreous Aβ in control and AMD groups were 1173.5 ± 117.1 pg/mL and 1275.6 ± 332.9 pg/mL, whilst plasma Aβ were 574.3 ± 104.8 pg/mL and 542.2 ± 139.9 pg/mL, respectively. MMP9 and Aβ showed variable levels across the lifecourse, indicating no correlation to each other or with age nor AMD status, though the smaller AMD cohort was a limiting factor. Aβ and MMP9 levels in the vitreous and blood were unrelated to mean arterial pressure. Smoking, another modifiable risk, showed no association with vitreous Aβ. However, smoking may be linked with vitreous (p = 0.004) and serum (p = 0.005) MMP9 levels in control and AMD groups, though this did not reach our elevated (p = 0.001) significance. A bioinformatics analysis revealed promising MMP9 and APP/Aβ partners for further scrutiny, many of which are already linked with retinopathy.

A Linkage between Angiogenesis and Inflammation in Neovascular Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the leading cause of visual impairment in the aging population with a limited understanding of its pathogenesis and the number of patients are all the time increasing. AMD is classified into two main forms: dry and neovascular AMD (nAMD). Dry AMD is the most prevalent form (80–90%) of AMD cases. Neovascular AMD (10–20% of AMD cases) is treated with monthly or more sparsely given intravitreal anti-vascular endothelial growth factor inhibitors, but unfortunately, not all patients respond to the current treatments. A clinical hallmark of nAMD is choroidal neovascularization. The progression of AMD is initially characterized by atrophic alterations in the retinal pigment epithelium, as well as the formation of lysosomal lipofuscin and extracellular drusen deposits. Cellular damage caused by chronic oxidative stress, protein aggregation and inflammatory processes may lead to advanced geographic atrophy and/or choroidal neovascularization and fibrosis. Currently, it is not fully known why different AMD phenotypes develop. In this review, we connect angiogenesis and inflammatory regulators in the development of nAMD and discuss therapy challenges and hopes.

Macrophage-derived interleukin-6 is necessary and sufficient for choroidal angiogenesis

Neovascular age-related macular degeneration (nAMD) commonly causes vision loss from aberrant angiogenesis, termed choroidal neovascularization (CNV). Interleukin-6 (IL6) is a pro-inflammatory and pro-angiogenic cytokine that is correlated with AMD progression and nAMD activity. We hypothesize that anti-IL6 therapy is a potential nAMD therapeutic. We found that IL6 levels were increased after laser injury and expressed by macrophages. Il6-deficiency decreased laser-induced CNV area and exogenous IL6 addition increased choroidal sprouting angiogenesis. Il6-null mice demonstrated equally increased macrophage numbers as wildtype mice. At steady state, IL6R expression was detected on peripheral blood and ocular monocytes. After laser injury, the number of IL6R⁺Ly6C⁺ monocytes in blood and IL6R⁺ macrophages in the eye were increased. In human choroid, macrophages expressed IL6, IL6R, and IL6ST. Furthermore, IL6R⁺ macrophages displayed a transcriptional profile consistent with STAT3 (signal transducer and activator of transcription 3) activation and angiogenesis. Our data show that IL6 is both necessary and sufficient for choroidal angiogenesis. Macrophage-derived IL6 may stimulate choroidal angiogenesis via classical activation of IL6R⁺ macrophages, which then stimulate angiogenesis. Targeting IL6 or the IL6R could be an effective adjunctive therapy for treatment-resistant nAMD patients.

CFH Loss in Human RPE Cells Leads to Inflammation and Complement System Dysregulation via the NF-κB Pathway

Age-related macular degeneration (AMD), the leading cause of vision loss in the elderly, is a degenerative disease of the macula, where retinal pigment epithelium (RPE) cells are damaged in the early stages of the disease, and chronic inflammatory processes may be involved. Besides aging and lifestyle factors as drivers of AMD, a strong genetic association to AMD is found in genes of the complement system, with a single polymorphism in the complement factor H gene (CFH), accounting for the majority of AMD risk. However, the exact mechanism of CFH dysregulation confers such a great risk for AMD and its role in RPE cell homeostasis is unclear. To explore the role of endogenous CFH locally in RPE cells, we silenced CFH in human hTERT-RPE1 cells. We demonstrate that endogenously expressed CFH in RPE cells modulates inflammatory cytokine production and complement regulation, independent of external complement sources, or stressors. We show that loss of the factor H protein (FH) results in increased levels of inflammatory mediators (e.g., IL-6, IL-8, GM-CSF) and altered levels of complement proteins (e.g., C3, CFB upregulation, and C5 downregulation) that are known to play a role in AMD. Moreover, our results identify the NF-κB pathway as the major pathway involved in regulating these inflammatory and complement factors. Our findings suggest that in RPE cells, FH and the NF-κB pathway work in synergy to maintain inflammatory and complement balance, and in case either one of them is dysregulated, the RPE microenvironment changes towards a proinflammatory AMD-like phenotype.

The potential of marine resources for retinal diseases: a systematic review of the molecular mechanisms

We rely on vision more than on any other sense to obtain information about our environment. Hence, the loss or even impairment of vision profoundly affects our quality of life. Diet or food components have already demonstrated beneficial effects on the development of retinal diseases. Recently, there has been a growing interest in resources from marine animals and plants for the prevention of retinal diseases through nutrition. Especially fish intake and omega-3 fatty acids have already led to promising results, including associations with a reduced incidence of retinal diseases. However, the underlying molecular mechanisms are insufficiently explained. The aim of this review was to summarize the known mechanistic effects of marine resources on the pathophysiological processes in retinal diseases. We performed a systematic literature review following the PRISMA guidelines and identified 107 studies investigating marine resources in the context of retinal diseases. Of these, 46 studies described the underlying mechanisms including anti-inflammatory, antioxidant, antiangiogenic/vasoprotective, cytoprotective, metabolic, and retinal function effects, which we critically summarize. We further discuss perspectives on the use of marine resources for human nutrition to prevent retinal diseases with a particular focus on regulatory aspects, health claims, safety, and bioavailability.

Exacerbation of AMD Phenotype in Lasered CNV Murine Model by Dysbiotic Oral Pathogens

Emerging evidence underscores an association between age-related macular degeneration (AMD) and periodontal disease (PD), yet the biological basis of this linkage and the specific role of oral dysbiosis caused by PD in AMD pathophysiology remains unclear. Furthermore, a simple reproducible model that emulates characteristics of both AMD and PD has been lacking. Hence, we established a novel AMD+PD murine model to decipher the potential role of oral infection (ligature-enhanced) with the keystone periodontal pathogen Porphyromonas gingivalis, in the progression of neovasculogenesis in a laser-induced choroidal-neovascularization (Li-CNV) mouse retina. By a combination of fundus photography, optical coherence tomography, and fluorescein angiography, we documented inflammatory drusen-like lesions, reduced retinal thickness, and increased vascular leakage in AMD+PD mice retinae. H&E further confirmed a significant reduction of retinal thickness and subretinal drusen-like deposits. Immunofluorescence microscopy revealed significant induction of choroidal/retinal vasculogenesis in AMD+PD mice. qPCR identified increased expression of oxidative-stress, angiogenesis, pro-inflammatory mediators, whereas antioxidants and anti-inflammatory genes in AMD+PD mice retinae were notably decreased. Through qPCR, we detected Pg and its fimbrial 16s-RrNA gene expression in the AMD+PD mice retinae. To sum-up, this is the first in vivo study signifying a role of periodontal infection in augmentation of AMD phenotype, with the aid of a pioneering AMD+PD murine model established in our laboratory.

Complement-mediated release of fibroblast growth factor 2 from human RPE cells

PURPOSE

Complement activation is associated with choroidal neovascularization (CNV) in age-related macular degeneration (AMD). Fibroblast growth factor 2 (FGF2) and membrane attack complex (MAC) are present in eyes of patients with CNV. Herein, we investigated the effect of complement activation on FGF2 release in human retinal pigment epithelial (RPE) cells.

METHODS

Cultured human RPE cells were primed with an anti-RPE antibody and then treated with C1q-depleted human serum in the presence or absence of Tec kinases inhibitor (LFM-A13). 38 cytokines/chemokines levels were measured by Luminex technology. Secretion of FGF2 and interleukin (IL)-6 was assessed by ELISA. Tec protein was measured by Western blot. mRNA expression of FGF2, chemokine (C-X-C motif) ligand 1 (CXCL-1), and family members of Tec kinases was evaluated by qPCR. Cell viability and MAC deposition were determined by WST-1 assay and flow cytometry, respectively.

RESULTS

Complement activation caused increased FGF2 and IL-6 release. FGF2 was released when C6-depleted human serum was reconstituted with C6. Anti-C5 antibody significantly attenuated complement-mediated FGF2 release, but not IL-6. FGF2 mRNA levels were not affected, while CXCL-1 mRNA levels were increased by complement activation. FGF2-containing extracellular vesicles were detected in response to complement challenge. Tec mRNA and protein were expressed in RPE cells. In the presence of LFM-A13, secretion of FGF2, but not IL-6, and MAC deposition were significantly decreased and cell viability was significantly increased in complement-treated cells when compared to controls.

CONCLUSIONS

Complement plays an important role to release FGF2 from RPE cells. Tec kinase is involved in MAC formation and complement-mediated FGF2 release. This information suggests a role for complement activation to mediate neovascularization in conditions such as AMD, and may elucidate potential therapeutic targets.

Basolateral activation with TLR agonists induces polarized cytokine release and reduces barrier function in RPE in vitro

PURPOSE

Systemic inflammation may be of importance in the development of AMD. RPE cells can recognize danger signals with toll-like receptors (TLR) and may react in a pro-inflammatory manner. In this study, we evaluated the basal and apical secretions of TNFα, IL-6, and IL-1β in primary RPE cells and RPE/choroid explant cells under basolateral stimulation of TLR2, 3, and 4; the effects on barrier function; and their influence on neuronal cell viability.

METHODS

RPE/choroid tissue explants were prepared from porcine eyes and cultivated in modified Ussing chambers; primary porcine RPE cells on transwell plates. Cells were basally stimulated with agonists Pam2CSK4 (Pam; TLR2), polyinosinic/polycytidylic acid (Poly I:C; TLR3), and lipopolysaccharide (LPS; TLR4) for 24 h. Supernatants were evaluated with ELISA for cytokines TNFα, IL-6, and IL-1β. Apical supernatants were applied to SHSY-5Y cells, and cell viability was evaluated in MTT assay. Barrier function was tested by measuring transepithelial electrical resistance (TER) and occludin immunostaining.

RESULTS

None of the tested TLR agonists was toxic on RPE cells after 24 h of exposure. Unstimulated RPE cells secreted hardly any cytokines. Pam induced IL-6, IL-1ß, and TNFα on the basal and apical sides at all concentrations tested. Poly I:C induced IL-6 and TNFα primarily at the basal side at lower but on both sides at higher concentrations. LPS induced IL-6, IL-1ß, and TNFα apically and basally at all concentrations tested. In the RPE/choroid, a strong difference between apical and basal secretions could be found. IL-6 was constitutively secreted basally, but not apically, but was induced by all agonists on both sides. IL-1ß and TNFα alpha were strongly induced on the basal side by all agonists. TER was reduced by all agonists, with Pam and LPS being effective in all concentrations tested. Occludin expression was unaltered, but the distribution was influenced by the agonists, with a less distinct localization at the cell borders after treatment. None of the agonists or supernatants of treated RPE and RPE/choroid organ cultures exerted any effect on viability of SHSY-5Y cells.

CONCLUSIONS

Danger signals activating TLRs can induce polarized cytokine expression and contribute to the loss of barrier function in the RPE.

Plasma level of lipocalin 2 is increased in neovascular age-related macular degeneration patients, particularly those with macular fibrosis

Background

Previously, we and others have reported higher populations of circulating neutrophils in patients with neovascular age-related macular degeneration (nAMD). Neutrophil gelatinase-associated lipocalin (NGAL, also known as lipocalin-2, LCN2), an important innate immune mediator, is known to be critically involved in sterile inflammation-mediated organ failure, fibrosis, cancer progression and retinal degeneration. This study investigated the plasma levels of LCN2, matrix metalloproteinase 9 (MMP9) and LCN2/MMP9 complex in different types of nAMD and examined whether the levels were related to patients’ responsiveness to anti-VEGF therapy.

Results

One hundred and seventy-four nAMD patients, including 108 with choroidal neovascularisation (CNV), 32 with retinal angiomatous proliferation (RAP), 23 with polypoidal choroidal vasculopathy (PCV) and 11 unclassified patients, and 43 healthy controls were recruited to this case-control study. Fifty-eight nAMD patients had macular fibrosis and 110 patients did not. Out of the 174 nAMD patients, 80 patients responded completely, 90 responded partially, and 4 did not respond to the anti-VEGF therapy. The plasma levels of LCN2 in nAMD patients (181.46 ± 73.62 ng/ml) was significantly higher than that in healthy controls (152.24 ± 49.55 ng/ml, P = 0.047). However, the difference disappeared after adjusting for age. A positive correlation between plasma level of LCN2 and age was observed in nAMD patients (r = 0.29, P = 0.0002) but not in healthy controls. The plasma level of LCN2 was also positively correlated with circulating neutrophils in nAMD patients (r = 0.34, p = 0.0007) but not in healthy controls (r = 0.057, p = 0.77). No correlation was observed between age and circulating neutrophils. Further analysis of nAMD subtypes uncovered a significantly higher level of LCN2 in patients with macular fibrosis even after adjusting for age. No relationship was observed between plasma levels of LCN2 and patients’ responsiveness to anti-VEGF therapy. The plasma levels of MMP9 and LCN2/MMP9 complex were comparable between nAMD and controls.

Conclusions

Our results suggest that higher plasma levels of LCN2 in nAMD are related to ageing and increased population of circulating neutrophils. Our results also suggest that higher levels of LCN2 may increase the risk of macular fibrosis in nAMD.

Novel Programmed Cell Death as Therapeutic Targets in Age-Related Macular Degeneration?

Age-related macular degeneration (AMD) is a leading cause of severe visual loss among the elderly. AMD patients are tormented by progressive central blurring/loss of vision and have limited therapeutic options to date. Drusen accumulation causing retinal pigment epithelial (RPE) cell damage is the hallmark of AMD pathogenesis, in which oxidative stress and inflammation are the well-known molecular mechanisms. However, the underlying mechanisms of how RPE responds when exposed to drusen are still poorly understood. Programmed cell death (PCD) plays an important role in cellular responses to stress and the regulation of homeostasis and diseases. Apart from the classical apoptosis, recent studies also discovered novel PCD pathways such as pyroptosis, necroptosis, and ferroptosis, which may contribute to RPE cell death in AMD. This evidence may yield new treatment targets for AMD. In this review, we summarized and analyzed recent advances on the association between novel PCD and AMD, proposing PCD's role as a therapeutic new target for future AMD treatment.

Dietary Patterns, Carbohydrates, and Age-Related Eye Diseases

Over a third of older adults in the U.S. experience significant vision loss, which decreases independence and is a biomarker of decreased health span. As the global aging population is expanding, it is imperative to uncover strategies to increase health span and reduce the economic burden of this age-related disease. While there are some treatments available for age-related vision loss, such as surgical removal of cataracts, many causes of vision loss, such as dry age-related macular degeneration (AMD), remain poorly understood and no treatments are currently available. Therefore, it is necessary to better understand the factors that contribute to disease progression for age-related vision loss and to uncover methods for disease prevention. One such factor is the effect of diet on ocular diseases. There are many reviews regarding micronutrients and their effect on eye health. Here, we discuss the impact of dietary patterns on the incidence and progression of age-related eye diseases, namely AMD, cataracts, diabetic retinopathy, and glaucoma. Then, we focus on the specific role of dietary carbohydrates, first by outlining the physiological effects of carbohydrates on the body and then how these changes translate into eye and age-related ocular diseases. Finally, we discuss future directions of nutrition research as it relates to aging and vision loss, with a discussion of caloric restriction, intermittent fasting, drug interventions, and emerging randomized clinical trials. This is a rich field with the capacity to improve life quality for millions of people so they may live with clear vision for longer and avoid the high cost of vision-saving surgeries.