Inflammation, complement factor h, and age-related macular degeneration: the Multi-ethnic Study of Atherosclerosis

The role of immune modulators in age-related macular degeneration

We provide an overview of the expanding literature on the role of cytokines and immune mediators in pathophysiology of age-related macular degeneration (AMD). Although many immunological mediators have been linked to AMD pathophysiology, the broader mechanistic picture remains unclear with substantial variations in the levels of evidence supporting these mediators. Therefore, we reviewed the literature considering the varying levels of supporting evidence. A Medical Subject Headings (MeSH) term-based literature research was conducted in September, 2023, consisting of the MeSH terms "cytokine" and "Age-related macular degeneration" connected by the operator "AND". After screening the publications by title, abstract, and full text, a total of 146 publications were included. The proinflammatory cytokines IL-1β (especially in basic research studies), IL-6, IL-8, IL-18, TNF-α, and MCP-1 are the most extensively characterised cytokines/chemokines, highlighting the role of local inflammasome activation and altered macrophage function in the AMD pathophysiology. Among the antiinflammatory mediators IL-4, IL-10, and TGF-β were found to be the most extensively characterised, with IL-4 driving and IL-10 and TGF-β suppressing disease progression. Despite the extensive literature on this topic, a profound understanding of AMD pathophysiology has not yet been achieved. Therefore, further studies are needed to identify potential therapeutic targets, followed by clinical studies.

Associations of drusen location with risk factors and incidence of late age-related macular degeneration in the Alienor study

PURPOSE

To test the hypothesis that central drusen location is strongly linked with known Age-related Macular Degeneration (AMD) risk factors and risk of incident late AMD.

METHODS

The Alienor study is a prospective population-based cohort study of residents of Bordeaux, France, followed from 2009 to 2017. On retinal photographs, we defined central drusen as at least one soft drusen (>63 μm) within 500 μm from fovea and pericentral drusen as at least one drusen 500-3000 μm from fovea, in the absence of any central drusen. Late AMD (atrophic and/or neovascular) was diagnosed using multimodal imaging. In total, 481 eyes were included in the analysis: 160 central and 321 pericentral. We investigated associations with systemic (age, sex, smoking, medical prescriptions, plasma concentrations of lipids and nutrients, UV exposure, blood pressure), ocular (retinal thickness, cataract extraction) and genetic risk scores (GRS).

RESULTS

In multivariate logistic regression central drusen were associated with smoking (OR, 2.95 for smoking more than 20 pack-years, p = 0.02), HDL-cholesterol (OR, 1.57 for 1 standard deviation (SD) increase, p = 0.0048), pulse pressure (OR, 0.77 for 1 SD increase, p = 0.04), Age-Related Maculopathy Susceptibility 2 (ARMS2) GRS (OR, 1.42; 95% CI, 1.11-1.83) and complement GRS (OR, 1.55; 95% CI, 1.15-2.10). In Cox modelling, the central location of drusen (at baseline or during the follow-up) was associated with a 4.41-fold increased risk (95% CI,1.98-9.81) for an incident late AMD.

CONCLUSION

Central drusen were strongly associated with AMD risk factors and incident late AMD, suggesting that it represents a key marker for AMD progression.

Potential Causal Association between C-Reactive Protein Levels in Age-Related Macular Degeneration: A Two-Sample Mendelian Randomization Study

Researchers have proposed a possible correlation between age-related macular degeneration (AMD) and inflammation or C-reactive protein (CRP) levels. We investigated the potential causal relationship between CRP levels and AMD. Single-nucleotide polymorphisms (SNPs) associated with CRP exposure were selected as the instrumental variables (IVs) with significance (p < 5 × 10-8) from the genome-wide association study (GWAS) meta-analysis data of Biobank Japan and the UK Biobank. GWAS data for AMD were obtained from 11 International AMD Genomics Consortium studies. An evaluation of causal estimates, utilizing the inverse-variance-weighted (IVW), weighted-median, MR-Egger, MR-Pleiotropy-Residual-Sum, and Outlier tests, was conducted in a two-sample Mendelian randomization (MR) study. We observed significant causal associations between CRP levels and AMD (odds ratio [OR] = 1.13, 95% CI = [1.02-1.24], and p = 0.014 in IVW; OR = 1.18, 95% CI = [1.00-1.38], and p = 0.044 in weight median; OR = 1.31, 95% CI = [1.13-1.52], and p < 0.001 in MR-Egger). The causal relationship between CRP and AMD warrants further research to address the significance of inflammation as a risk factor for AMD.

Elevated tumor necrosis factor alpha and vascular endothelial growth factor in intermediate age-related macular degeneration and geographic atrophy

Introduction

Tumor necrosis factor alpha (TNF-α) is an inflammatory cytokine implicated in pathological changes to the retinal pigment epithelium that are similar to changes in geographic atrophy (GA), an advanced form of age related macular degeneration (AMD). TNF-α also modulates expression of other cytokines including vascular endothelial growth factor (VEGF), leading to choroidal atrophy in models of AMD. The purpose of this study was to investigate systemic TNF-α and VEGF in patients with GA and intermediate AMD (iAMD) compared to controls without AMD.

Methods

We examined plasma levels of TNF-α and VEGF in patients with GA, iAMD, and controls without AMD from the University of Colorado AMD registry (2014 to 2021). Cases and controls were characterized by multimodal imaging. TNF-α and VEGF were measured via multiplex immunoassay and data were analyzed using a non-parametric rank based linear regression model fit to plasma biomarkers.

Results

There were 97 GA, 199 iAMD patients and 139 controls. TNF-α was significantly increased in GA (Median:9.9pg/ml, IQR:7.3-11.8) compared to iAMD (Median:7.4, IQR:5.3-9.1) and in both GA and iAMD compared to controls (Median:6.4, IQR:5.3-7.8), p<0.01 for all comparisons. VEGF was significantly increased in iAMD (Median:8.9, IQR:4.8-14.3) compared to controls (Median:7.7, IQR:4.6-11.1), p<0.01. There was a significant positive correlation between TNF-α and VEGF in GA (0.46, p<0.01), and iAMD (0.20, p=0.01) with no significant interaction between TNF-α and VEGF in any group.

Discussion

These findings suggest TNF-α and VEGF may contribute to systemic inflammatory processes associated with iAMD and GA. TNF-α and VEGF may function as systemic biomarkers for disease development.

Association of APOE Haplotypes With Common Age-Related Ocular Diseases in 412,171 Individuals

Purpose

Apolipoprotein E4 (APOE4), a known risk factor for Alzheimer's disease, has controversially been associated with reduced risk of primary open-angle glaucoma (POAG) and age-related macular degeneration (AMD). Here, we sought to systematically quantify the associations of APOE haplotypes with age-related ocular diseases and to assess their scope and age-dependency.

Methods

We included genetic and registry data from 412,171 Finnish individuals in the FinnGen study. Disease endpoints were defined using nationwide registries. APOE genotypes were directly genotyped using Illumina and Affymetrix arrays or imputed using a custom Finnish reference panel. We evaluated the disease associations of APOE genotypes containing ε2 (without ε4) and ε4 (without ε2) compared with the ε3ε3 genotype using logistic regressions stratified by age.

Results

APOE ε4 enriched haplotypes were inversely associated with overall glaucoma (odds ratio [OR] = 0.95, 95% confidence interval [CI] = 0.92-0.99, P = 0.0047), and its subtypes POAG (OR = 0.95, P = 0.027), normal-tension glaucoma (OR = 0.87, P = 0.0058), and suspected glaucoma (OR = 0.95, P = 0.014). Individuals with the ε4 allele also had lower odds for AMD (OR = 0.80, 95% CI = 0.76-0.84, P < 0.001), seen both in dry and neovascular subgroups. A slight negative association was also detected in senile cataract, but this was not reproducible in age-group analyses.

Conclusions

Our results support prior evidence of the inverse association of APOE ε4 with glaucoma, but the association was weaker than for AMD. We could not show an association with exfoliation glaucoma, supporting the hypothesis that APOE may be involved in regulating retinal ganglion cell degeneration rather than intraocular pressure.

Physicochemical, Pre-Clinical, and Biological Evaluation of Viscosity Optimized Sodium Iodide-Incorporated Paste

This study aimed to investigate the impact of different viscosities of silicone oil on the physicochemical, pre-clinical usability, and biological properties of a sodium iodide paste. Six different paste groups were created by mixing therapeutic molecules, sodium iodide (D30) and iodoform (I30), with calcium hydroxide and one of the three different viscosities of silicone oil (high (H), medium (M), and low (L)). The study evaluated the performance of these groups, including I30H, I30M, I30L, D30H, D30M, and D30L, using multiple parameters such as flow, film thickness, pH, viscosity, and injectability, with statistical analysis (p < 0.05). Remarkably, the D30L group demonstrated superior outcomes compared to the conventional iodoform counterpart, including a significant reduction in osteoclast formation, as examined through TRAP, c-FOS, NFATc1, and Cathepsin K (p < 0.05). Additionally, mRNA sequencing showed that the I30L group exhibited increased expression of inflammatory genes with upregulated cytokines compared to the D30L group. These findings suggest that the optimized viscosity of the sodium iodide paste (D30L) may lead to clinically favorable outcomes, such as slower root resorption, when used in primary teeth. Overall, the results of this study suggest that the D30L group shows the most satisfactory outcomes, which may be a promising root-filling material that could replace conventional iodoform-based pastes.

MAPK Pathways in Ocular Pathophysiology: Potential Therapeutic Drugs and Challenges

Mitogen-activated protein kinase (MAPK) pathways represent ubiquitous cellular signal transduction pathways that regulate all aspects of life and are frequently altered in disease. Once activated through phosphorylation, these MAPKs in turn phosphorylate and activate transcription factors present either in the cytoplasm or in the nucleus, leading to the expression of target genes and, as a consequence, they elicit various biological responses. The aim of this work is to provide a comprehensive review focusing on the roles of MAPK signaling pathways in ocular pathophysiology and the potential to influence these for the treatment of eye diseases. We summarize the current knowledge of identified MAPK-targeting compounds in the context of ocular diseases such as macular degeneration, cataract, glaucoma and keratopathy, but also in rare ocular diseases where the cell differentiation, proliferation or migration are defective. Potential therapeutic interventions are also discussed. Additionally, we discuss challenges in overcoming the reported eye toxicity of some MAPK inhibitors.

Retinal and choroidal changes in AMD: A systematic review and meta-analysis of spectral-domain optical coherence tomography studies

Optical coherence tomography is a noninvasive imaging technology using the optical reflectivity of tissues that is capable of detecting quantitative and qualitative biomarkers of age-related macular degeneration (AMD) that cannot be similarly recognized in conventional imaging. We systematically searched PubMed and Embase databases to identify relevant articles to this subject. A fixed-effect or random-effect model was applied for the meta-analysis based on the heterogeneity level. In addition, subgroup analyses, meta-regression, publication bias, and quality assessment were also performed. Twenty-five studies with 1,632 cases and 1,445 healthy controls in total were included. Our results revealed that, when compared to controls, AMD subjects showed a significantly lower thickness in the choroid at 500 µm temporal, 1,500 µm nasal, and temporal to the fovea, subfoveal choroid, average peripapillary retinal nerve fiber layer, and average macular ganglion cell complex (GCC); however, average and central choroidal thickness 500 µm nasal, 1,000 µm nasal and temporal to the fovea, central and parafoveal macular GCC, retinal nerve fiber layer, and inner plexiform layer, and central macular thickness did not change significantly. Various regional analyses showed several other significant differences. The findings of the current study confirm that some retinal layers are altered in AMD patients compared to healthy controls. Thus, future studies are required to derive more definitive conclusions.

Proteomic genotyping of SNP of Complement Factor H (CFH) Y402H and I62V using multiple reaction monitoring (MRM) assays

The single nucleotide polymorphisms (SNPs) of complement factor H (CFH) gene are well-known genetic risk factors for age-related macular degeneration (AMD). To identify whether the measurement of plasma protein concentrations of CFH variants using the multiple reaction monitoring (MRM) assay can determine the genotypes of CFH SNP rs1061170 and rs800292, 120 patients with AMD and 26 controls were included in this study. The number of cases were TT:TC:CC = 121:24:1 in CFH SNP Y402H and GG:AG:AA = 72:57:17 in CFH SNP I62V. Plasma concentrations of tryptic peptides were measured using the MRM assay, and tyrosine/histidine (Y/H) and valine/isoleucine (V/I) CFH variant protein ratios were obtained. To discriminate the genotypes by the plasma protein ratios, cut-off values were set for Y/H ratios (TT: > 4.428; TC: 1.00-4.428; CC: < 1.00) and V/I ratios (GG: > 1.09; AG: 0.0089-1.08; AA: < 0.0089). Correlation analysis revealed that the plasma CFH variant protein ratios and genotypes of CFH were exactly matched (100%) without overlap in the total patients and controls. The measurement of plasma protein CFH variants using the MRM assay can accurately identify the genotypes of CFH SNPs of Y402H and I62V.

Osteoarthritis Is Associated With an Increased Risk of Age-Related Macular Degeneration: A Population-Based Longitudinal Follow-Up Study

Aims

To investigate the long-term risk of age-related macular degeneration (AMD) in persons with osteoarthritis (OA).

Methods

This retrospective cohort study first enrolled 71,609 subjects diagnosed with OA, and 236,169 without such a diagnosis between January 1, 2002 and December 31, 2005, from the Longitudinal Health Insurance Database 2005. All were aged 40–69. After excluding subjects who had pre-existing AMD and/or who had missing socioeconomic data, frequency matching by sex and age was performed. This resulted in there being 60,274 subjects in each of the final matched OA and non-OA groups. The study participants were followed up to the occurrence of AMD, death, or the end of 2011. We used Cox proportional-hazards regression to estimate the impact of OA on the risk of developing AMD, and performed subgroup analyses stratified by sex and age.

Results

The median follow-up time was 8.9 years, with an interquartile range of 1.4 years. The incidence rate of AMD in the OA group was 2.77 per 1,000 person-years [95% confidence interval (CI), 2.62–2.92], and in the non-OA group, 2.06 per 1,000 person-years (95% CI, 1.94–2.19). The adjusted hazard ratio (HR) of AMD for the OA group was therefore 1.30 (95% CI, 1.20–1.41). In the subgroup analysis stratified by sex for the OA group, the adjusted HRs of AMD were 1.29 in the women's stratum and 1.31 in the men's. When stratified by age, the adjusted HRs of AMD for the younger (40–54 years) and older (55–69 years) strata were 1.28 and 1.31, respectively.

Conclusions

Persons with OA have an increased risk of developing AMD, regardless of age and sex.

Oleuropein Protects Human Retinal Pigment Epithelium Cells from IL-1β-Induced Inflammation by Blocking MAPK/NF-κB Signaling Pathways

Proinflammatory mediators such as interleukin (IL)-1β cause retinal pigment epithelium (RPE) inflammation, which is related to visual deterioration, including age-related macular degeneration and diabetic retinopathy. Oleuropein is a polyphenol compound that shows potent anti-inflammatory, antioxidant, and anti-cancer activities, but its effects on IL-1β-induced inflammation have not been examined in the adult RPE cell line ARPE-19. Here, we assessed the ability of oleuropein to attenuate this inflammation in ARPE-19 cells. IL-1β induced secretion of the inflammatory cytokines IL-6, monocyte chemoattractant protein-1 (MCP)-1, and soluble intercellular adhesion molecule (sICAM)-1. As measured by enzyme-linked immunosorbent assay, oleuropein significantly inhibited levels of all three proteins and led to decreased monocyte adhesiveness to ARPE-19 cells. To clarify the underlying anti-inflammatory mechanisms, we used western blots to evaluate the effect of oleuropein on inactivation of the nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways. The results showed that oleuropein significantly decreased levels of the inflammatory mediator cyclooxygenase-2 and increased anti-inflammatory protein HO-1 expression. We next examined if the anti-inflammatory activity of oleuropein arises via inactivated NF-κB. We found that suppressing phosphorylation of the JNK1/2 and p38 MAPK signaling pathways inhibited IL-6, MCP-1, and sICAM-1 secretion, implicating these pathways and NF-κB suppression in the effects of oleuropein. These results indicate that oleuropein shows potential for the prevention and treatment of inflammatory diseases of the retina.

Peptide Location Fingerprinting Reveals Tissue Region-Specific Differences in Protein Structures in an Ageing Human Organ

In ageing tissues, long-lived extracellular matrix (ECM) proteins are susceptible to the accumulation of structural damage due to diverse mechanisms including glycation, oxidation and protease cleavage. Peptide location fingerprinting (PLF) is a new mass spectrometry (MS) analysis technique capable of identifying proteins exhibiting structural differences in complex proteomes. PLF applied to published young and aged intervertebral disc (IVD) MS datasets (posterior, lateral and anterior regions of the annulus fibrosus) identified 268 proteins with age-associated structural differences. For several ECM assemblies (collagens I, II and V and aggrecan), these differences were markedly conserved between degeneration-prone (posterior and lateral) and -resistant (anterior) regions. Significant differences in peptide yields, observed within collagen I α2, collagen II α1 and collagen V α1, were located within their triple-helical regions and/or cleaved C-terminal propeptides, indicating potential accumulation of damage and impaired maintenance. Several proteins (collagen V α1, collagen II α1 and aggrecan) also exhibited tissue region (lateral)-specific differences in structure between aged and young samples, suggesting that some ageing mechanisms may act locally within tissues. This study not only reveals possible age-associated differences in ECM protein structures which are tissue-region specific, but also highlights the ability of PLF as a proteomic tool to aid in biomarker discovery.

Proteomics-based approach for differentiation of age-related macular degeneration sub-types

Purpose:

Age-related macular degeneration (AMD) is one of the leading causes of irreversible central vision loss in the elderly population. The current study aims to find non-invasive prognostic biomarkers in the urine specimens of the AMD patients.

Methods:

Peripheral blood and urine samples were collected from 23 controls and 61 AMD patients. Genomic DNA was extracted from the buffy coat of peripheral blood. Allele specific PCR was used to assay SNPs in complement factor H (CFH), complement component 3 (C3). Comparative proteomic analysis of urine samples from early AMD, choroidal neovascular membrane (CNVM), geographic atrophy (GA), and healthy controls was performed using isobaric labelling followed by mass spectrometry. Validation was performed using enzyme-linked immunosorbent assay (ELISA).

Results:

Comparative proteomic analysis of urine samples identified 751 proteins, of which 383 proteins were found to be differentially expressed in various groups of AMD patients. Gene ontology classification of differentially expressed proteins revealed the majority of them were involved in catalytic functions and binding activities. Pathway analysis showed cell adhesion molecule pathways (CAMs), Complement and coagulation cascades, to be significantly deregulated in AMD. Upon validation by ELISA, SERPINA-1 (Alpha1 antitrypsin), TIMP-1 (Tissue inhibitor of matrix metaloprotease-1), APOA-1 (Apolipoprotein A-1) were significantly over-expressed in AMD (n = 61) patients compared to controls (n = 23). A logistic model of APOA-1 in combination with CFH and C3 polymorphisms predicted the risk of developing AMD with 82% accuracy.

Conclusion:

This study gives us a preliminary data on non-invasive predictive biomarkers for AMD, which can be further validated in a large cohort and translated for diagnostic use.

Is there a relationship between hematological inflammatory parameters and age-related macular degeneration?

Purpose

We aimed to analyze blood inflammation parameters in patients with age-related macular degeneration (AMD).

Methods

In this retrospective study, patients were divided into three groups: wet-type AMD (n = 60), dry-type AMD (n = 60), and healthy controls (n = 71). The laboratory and demographic data of the patients were analyzed. Neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and monocyte-to-lymphocyte ratio (MLR) were calculated manually.

Results

The mean NLR was 2.26 ± 1.42 in the dry-type AMD group, 3.90 ± 1.65 in the wet-type AMD group, and 1.84 ± 0.61 in the control group (p < 0.001). The mean MLR was 0.30 ± 0.20 in the dry-type AMD group, 0.47 ± 0.31 in the wet-type AMD group, and 0.28 ± 0.14 in the control group (p < 0.001). The mean PLR was 129.31 ± 79.82 in the dry-type AMD group, 156.67 ± 83.99 in the wet-type AMD group, and 135.59 ± 58.68 in the control group (p = 0.101). Receiver operating characteristic (ROC) curve analyses revealed that the area under the curve (AUC) for NLR and MLR was 0.920 and 0.717, respectively, for wet-type AMD. The sensitivity and specificity of NLR for wet-type AMD were 64% and 93%, respectively, whereas MLR was 63% and 75%, respectively.

Conclusion

Simple blood tests revealed that NLR and MLR were significantly higher in patients with wet-type AMD than in patients with dry-type AMD and healthy controls, which implies low-grade inflammation.

miR-106b suppresses pathological retinal angiogenesis

MicroRNAs are small non-coding RNAs that post-transcriptionally regulate gene expression. We recently demonstrated that levels of miR-106b were significantly decreased in the vitreous and plasma of patients with neovascular age-related macular degeneration (AMD). Here we show that expression of the miR-106b-25 cluster is negatively regulated by the unfolded protein response pathway of protein kinase RNA-like ER kinase (PERK) in a mouse model of neovascular AMD. A reduction in levels of miR-106b triggers vascular growth both in vivo and in vitro by inducing production of pro-angiogenic factors. We demonstrate that therapeutic delivery of miR-106b to the retina with lentiviral vectors protects against aberrant retinal angiogenesis in two distinct mouse models of pathological retinal neovascularization. Results from this study suggest that miRNAs such as miR-106b have the potential to be used as multitarget therapeutics for conditions characterized by pathological retinal angiogenesis.

Cross-sectional study of the association between age-related macular degeneration and arthritis in the National Health and Nutrition Examination Survey 2005-2008

OBJECTIVE

To explore the association between age-related macular degeneration (AMD) and arthritis in a representative sample of the US population.

DESIGN

Population-based, cross-sectional study.

SETTING

The National Health and Nutrition Examination Survey (NHANES) 2005-2008.

PARTICIPANTS

A total of 4813 participants aged 40 years and older with available information on AMD and arthritis in the 2005-2008 NHANES.

METHODS

The status and types of arthritis were obtained from questionnaires. Non-mydriatic fundus photographs were collected. The types of AMD were assessed using the modified Wisconsin Age-Related Maculopathy Grading Classification Scheme. The association between arthritis and AMD was evaluated using logistic regression models.

RESULTS

After adjusting for covariates, participants with any or early AMD had significantly lower odds of having any type of arthritis (any AMD: OR=0.56, 95% CI: 0.36-0.86; early AMD: OR=0.55, 95% CI: 0.34-0.88) or osteoarthritis (OA) (any AMD: OR=0.43, 95% CI: 0.26-0.71; early AMD: OR=0.44, 95% CI: 0.25-0.76) compared with those without AMD. When considering AMD as the outcome, significant negative associations were also found between any arthritis or OA and any (any arthritis: OR=0.64, 95% CI: 0.43-0.94; OA: OR=0.52, 95% CI: 0.33-0.82) or early AMD (any arthritis: OR=0.61, 95% CI: 0.40-0.93; OA: OR=0.51, 95% CI: 0.31-0.86) in the multivariable logistic models. There was no significant association between different types of arthritis and late AMD.

CONCLUSIONS

People with arthritis, especially those with OA, were less likely to have AMD compared with those without arthritis and vice versa. Further studies are needed to confirm this potential protective effect of arthritis and/or arthritis treatment on AMD and to explore the underlying mechanisms.

Revisiting the role of factor H in age-related macular degeneration: Insights from complement-mediated renal disease and rare genetic variants

Ophthalmologists are long familiar with the eye showing signs of systemic disease, but the association between age-related macular degeneration and abnormal complement activation, common to several renal disorders, has only recently been elucidated. Although complement activation products were identified in drusen almost three decades ago, it was not until the early 21st century that a single-nucleotide polymorphism in the complement factor H gene was identified as a major heritable determinant of age-related macular degeneration, galvanizing global efforts to unravel the pathogenesis of this common disease. Advances in proteomic analyses and familial aggregation studies have revealed distinctive clinical phenotypes segregated by the functional effects of common and rare genetic variants on the mature protein and its splice variant, factor H-like protein 1. The predominance of loss-of-function, N-terminal mutations implicate age-related macular degeneration as a disease of general complement dysregulation, offering several therapeutic avenues for its modulation. Here, we explore the molecular impact of these mutations/polymorphisms on the ability of variant factor H/factor H-like protein 1 to localize to polyanions, pentraxins, proinflammatory triggers, and cell surfaces across ocular and renal tissues and exert its multimodal regulatory functions and their clinical implications. Finally, we critically evaluate key therapeutic and diagnostic efforts in this rapidly evolving field.

Periodontal Disease and Age-Related Macular Degeneration: A Meta-Analysis of 112,240 Participants

OBJECTIVE

Epidemiological studies have shown a correlation between periodontal disease (PD) and age-related macular degeneration (AMD). However, the results have been inconsistent, and no relevant meta-analysis has been performed on this topic. Hence, we performed a meta-analysis to evaluate whether the two diseases are related. Material and Methods. The PubMed, Embase, Cochrane Library, and Web of Science databases were searched up to April 20, 2020, for related articles. Two authors independently conducted literature screening and data extraction and then used the Stata 15.1 software to calculate the relative risk (RRs) and 95% confidence intervals (CIs) to assess the association between PD and AMD.

RESULTS

A total of 5 observational studies involving 112,240 participants and 5,005 AMD patients were included. The results of meta-analysis using the random-effects model showed that the incidence of AMD in PD patients was 1.35 times that of non-PD patients; the difference was statistically significant (RR = 1.35, 95%CI = 1.07-1.70, P = 0.011). Sensitivity analysis showed that the results were stable.

CONCLUSIONS

PD patients have a higher risk of AMD, but the causal relationship between PD and AMD has not been confirmed. Further research should be carried out to verify the exact relationship between the two.

Systemic levels of C-reactive protein in patients with age-related macular degeneration: A systematic review with meta-analyses

Ageing of the retina is associated with the gradual accumulation of basal deposits and the formation of drusen. However, in some individuals this process is exacerbated and causes development of age-related macular degeneration. Late features of age-related macular degeneration include geographic atrophy of the neuroretina or choroidal neovascularization. Such changes lead to blurred vision, metamorphopsia, and scotoma, and is the leading cause of vision loss in developed countries. Chronic low-grade inflammation has been investigated because of its relationship to ageing and its role in the gap between chronological and biological ageing. Here, we systematically reviewed studies investigating systemic C-reactive protein in patients with age-related macular degeneration. We identified 53 studies with 60,598 participants (10,392 patients and 38,901 controls). Our meta-analyses revealed that early age-related macular degeneration was not associated to systemic C-reactive protein (Cohen's d = 0.03 [-0.04 to 0.10]; OR = 1.06 [0.93-1.20]; P = 0.39) whereas late age-related macular degeneration (Cohen's d = 0.38 [0.24 to 0.51]; OR = 1.99 [1.55-2.52]; P < 0.0001), and neovascular age-related macular degeneration (Cohen's d = 0.40 [0.24 to 0.56]; OR = 2.07 [1.55-2.76]; P < 0.0001) was associated with a small-to-moderate increase in systemic C-reactive protein. Our review provides an overview of this extensively studied field, provide summary estimates that provide insight into when and to what extent systemic C-reactive protein is associated with age-related macular degeneration, and help in distinguishing the potentially reversible disease processes from that of irreversible retinal ageing.

Geographic distributions of age-related macular degeneration incidence: a systematic review and meta-analysis

PURPOSE

We performed a systematic review and meta-analysis to summarise the geographic distribution of age-related macular degeneration (AMD) incidence.

METHODS

Databases including PubMed, Embase and Web of Science were searched for publications of early and late AMD before September 2019. Studies were included if they applied a standardised photographic assessment and classification system. The proportion of participants with AMD in each eligible study was combined to obtain a pooled incidence from all studies using a random effects model. We also assessed sources of potential heterogeneity in the incidence of AMD using meta-regression analyses for both late and early AMD.

RESULTS

Twenty-four population-based studies (70 123 individuals aged 55 years or older) were included in the meta-analysis. The pooled global annual incidences of early and late AMD were 1.59% (95% CI 1.12% to 2.10%) and 0.19% (95% CI: 0.13% to 0.28%), respectively. Individuals of European descent had the highest annual incidence of both early (2.73%, 95% CI 1.63% to 4.57%) and late (0.36%, 95% CI 0.17% to 0.75%) AMD than other ethnic groups. Average age (p=0.001) at baseline, ethnicity (p=0.001), region (p=0.043) and gender (p=0.011) were predictors for incident late AMD, while only average age (p=0.01) at baseline and ethnicity (p=0.025) was associated with incidence of early AMD.

CONCLUSIONS

This meta-analysis offers an up-to-date overview of AMD globally, which may provide scientific guidance for the design and implementation of public health strategies such as screening programmes for AMD in both specific geographic locations and ethnic groups, as well as worldwide.

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

Age-related macular degeneration (AMD) is the most prevalent cause of irreversible vision loss in industrialized countries. Several studies have investigated systemic interleukin-6 (IL-6) levels of patients with AMD. In this study, we systemically reviewed the literature to provide an overview of the field and used meta-analyses to provide a summary estimate of the standardized mean difference (SMD) of systemic IL-6 between patients with AMD and control individuals. We searched the literature databases PubMed/MEDLINE, Embase, Web of Science and the Cochrane Central on 1 June 2019 for relevant studies on humans. Two authors independently extracted data and evaluated risk of bias. We identified 19 studies for the qualitative review with a total of more than 3586 individuals (1865 controls and 1721 with AMD). We found an overall random-effects SMD in systemic IL-6 levels 0.63 (95% CI: 0.28 to 0.99, p = 0.0005) corresponding to a medium effect size. In a subgroup analysis, we found that early AMD was not strongly associated with elevated IL-6 levels (0.12, 95% CI: -0.01 to 0.24, p = 0.06), which was in contrast to the significantly elevated IL-6 levels in patients with geographic atrophy (1.21, 95% CI: 0.41 to 2.01, p = 0.003) and patients with neovascular AMD (0.99, 95% CI: 0.34 to 1.63, p = 0.003). Our results show that the evidence today suggests an increased systemic IL-6 in patients with AMD, but that this may be a phenomenon more closely related to the late subtypes of AMD.

Using Mendelian randomization to evaluate the causal relationship between serum C-reactive protein levels and age-related macular degeneration

Serum C-reactive protein (CRP), an important inflammatory marker, has been associated with age-related macular degeneration (AMD) in observational studies; however, the findings are inconsistent. It remains unclear whether the association between circulating CRP levels and AMD is causal. We used two-sample Mendelian randomization (MR) to evaluate the potential causal relationship between serum CRP levels and AMD risk. We derived genetic instruments for serum CRP levels in 418,642 participants of European ancestry from UK Biobank, and then conducted a genome-wide association study for 12,711 advanced AMD cases and 14,590 controls of European descent from the International AMD Genomics Consortium. Genetic variants which predicted elevated serum CRP levels were associated with advanced AMD (odds ratio [OR] for per standard deviation increase in serum CRP levels: 1.31, 95% confidence interval [CI]: 1.19-1.44, P = 5.2 × 10^-8). The OR for the increase in advanced AMD risk when moving from low (< 3 mg/L) to high (> 3 mg/L) CRP levels is 1.29 (95% CI: 1.17-1.41). Our results were unchanged in sensitivity analyses using MR models which make different modelling assumptions. Our findings were broadly similar across the different forms of AMD (intermediate AMD, choroidal neovascularization, and geographic atrophy). We used multivariable MR to adjust for the effects of other potential AMD risk factors including smoking, body mass index, blood pressure and cholesterol; this did not alter our findings. Our study provides strong genetic evidence that higher circulating CRP levels lead to increases in risk for all forms of AMD. These findings highlight the potential utility for using circulating CRP as a biomarker in future trials aimed at modulating AMD risk via systemic therapies.

Neutrophil-to-lymphocyte ratio in ocular diseases: a systematic review

AIM

To summarize the results of studies investigating neutrophil-to-lymphocyte ratio (NLR) and to identify the role of NLR in ocular diseases.

METHODS

With the aim of identifying the studies related to NLR, a search was conducted on http://www.ncbi.nlm.nih.gov/pubmed by utilizing the key words "neutrophil lymphocyte ratio, ocular diseases, and eye diseases" up to February 2018. All of the original articles were assessed according to date of publications, countries, clinics and topics. Studies about ocular inflammatory diseases were evaluated according to their qualifications, review methods and results.

RESULTS

A total of 4473 publications, including original research articles and reviews were screened. The number of publications was shown a regular logarithmic increase over the years. The majority of studies were performed by clinics in Turkey and many of these publications were performed by oncology and cardiology clinics. A total of 75 publications were identified to be about ocular diseases.

CONCLUSION

Elevated NLR as a cheap, reproducible, and readily available marker could be used as a diagnostic and/or prognostic marker in ocular diseases.

Plasma markers of chronic low-grade inflammation in polypoidal choroidal vasculopathy and neovascular age-related macular degeneration

PURPOSE

Ageing is the strongest predictor of neovascular age-related macular degeneration (AMD), where neuroinflammation is known to play a major role. Less is known about polypoidal choroidal vasculopathy (PCV), which is an important differential diagnosis to neovascular AMD. Here, we report plasma markers of inflammation with age (inflammaging) in patients with PCV, patients with neovascular AMD and a healthy age-matched control group.

METHODS

We isolated plasma from fresh venous blood obtained from participants (n = 90) with either PCV, neovascular AMD, or healthy maculae. Interleukin(IL)-1β, IL-6, IL-8, IL-10 and tumour necrosis factor receptor 2 (TNF-R2) were measured using U-PLEX Human Assays. Routine plasma C-reactive protein (CRP) was measured using Dimension Vista 1500.

RESULTS

Patients with PCV had plasma levels of IL-1β, IL-6, IL-8, IL-10 and TNF-R2 similar to that in healthy controls. Patients with neovascular AMD had significantly higher plasma IL-1β, IL-6 and IL-10 than healthy controls, whereas no significant differences were observed for plasma IL-8 and TNF-R2. Differences between plasma IL-1β, IL-6 and IL-10 possessed a positive but weak ability in discriminating neovascular AMD from PCV. Both patients with PCV and patients with neovascular AMD had significantly higher levels of routine plasma CRP.

CONCLUSION

Patients with PCV differ from patients with neovascular AMD in terms of plasma inflammaging profile. Apart from increased CRP, no signs of inflammaging were observed in patients with PCV. In patients with neovascular AMD, we find a specific angiogenesis-twisted inflammaging profile.

Gout and the risk of age-related macular degeneration in the elderly

Objective

To assess whether gout is associated with incident age-related macular degeneration (AMD)

Methods

We used the 5% Medicare claims data from 2006–12 for all beneficiaries who were enrolled in Medicare fee-for-service (Parts A, B) and not enrolled in a Medicare Advantage Plan, and resided in the U.S. People were censored at the occurrence of new diagnosis of AMD, death or the end of study (12/31/2012), whichever occurred first. We used multivariable-adjusted Cox regression analyses to assess the association of gout with incident AMD, adjusted for demographics, comorbidity, and use of medications for cardiovascular disease and gout. Hazard ratios and 95% confidence intervals were calculated.

Results

In this observational cohort study, of the 1,684,314 eligible people, 116,097 developed incident AMD (6.9%). Incidence rates of AMD per 1,000 person-years were 20.1 for people with gout and 11.7 for people without gout. In multivariable-adjusted analyses, a diagnosis of gout was significantly associated with a higher risk of incident AMD with a hazard ratio of 1.39 (95% CI, 1.35, 1.43). This association was confirmed in sensitivity analyses that substituted Charlson-Romano comorbidity index continuous score with either a categorical Charlson-Romano comorbidity index score or individual Charlson-Romano index comorbidities plus hypertension, hyperlipidemia and coronary artery disease. Other covariates significantly associated with higher hazards of incident AMD were older age, female gender, White race/ethnicity, and higher Charlson-Romano comorbidity index score.

Conclusions

We noted a novel association of gout with AMD in the elderly. Future studies should investigate the pathways that mediate this association.

Inhibition of Proteasome Activity Upregulates IL-6 Expression in RPE Cells through the Activation of P38 MAPKs

Purpose

As far as we know, during the development of age-related macular degeneration (AMD), the activity of proteasome in retinal pigment epithelium cells (RPE) gradually decreases. And a lot of research has shown that age-related macular degeneration is closely related to inflammation and autoimmune. Moreover, there are many cytokines (CKs) involved in the course of inflammation. In this study, we are going to investigate how the decrease of proteasome activity affects the production of interleukin-6 (IL-6) in human retinal pigment epithelium cells (ARPE-19).

Methods

Cultured ARPE-19 was treated with or without MG132, a proteasome inhibitor, and the levels of IL-6 mRNA (messenger ribonucleic acid) in RPE at 1 h, 4 h, 8 h, and IL-6 protein in the culture medium at 2 h, 4 h, 6 h, 8 h, 10 h, and 12 h were measured by real-time polymerase chain reaction (real-time PCR) and enzyme-linked immunosorbent assay (ELISA). The protein levels of MCP-1 (monocyte chemoattractant protein-1) in the culture medium at 2 h, 4 h, 6 h, 8 h, 10 h, and 12 h were also measured by ELISA. Then we tested which of cell signal pathways regulating the production of IL-6 were activated when we added MG132 into the medium by Western blot and electrophoretic mobility shift assays (EMSA). After that, we put the inhibitors of these activated cell signal pathways into the medium individually to see which inhibitor can counteract the effect of upregulating the levels of IL-6 in the culture medium of RPE.

Results

MG132 decreased the secretion of MCP-1 in the culture medium of RPE, but it increased the expression of IL-6 mRNA in RPE and IL-6 protein level in the culture medium of RPE. MG132 treatment was also found to enhance the level of phosphorylated p38 mitogen-activated protein kinases (MAPKs) and c-Jun N-terminal Kinase (JNK) by Western blotting. More importantly, the effect of MG132 on upregulating the levels of IL-6 was inhibited by SB203580, an inhibitor of P38 MAP kinases. But the JNK inhibitor, SP600125, cannot prevent the effect of upregulating the levels of IL-6 by MG132 in the RPE culture medium.

Conclusions

We concluded that the proteasome inhibitor, MG132, upregulates IL-6 production in RPE cells through the activation of P38 MAPKs.

Association of C-Reactive Protein Genetic Polymorphisms With Late Age-Related Macular Degeneration

Importance

C-reactive protein (CRP) is a circulating inflammatory marker associated with late age-related macular degeneration (AMD). It remains uncertain whether the association between CRP concentrations and AMD is causal.

Objective

To assess whether CRP (OMIM 123260) single-nucleotide polymorphisms that influence circulating CRP concentrations are associated with late AMD.

Design, Setting, and Participants

Participants in 2 UK, hospital-based, case-control studies (Cambridge AMD study and Moorfields Eye Hospital AMD study) and 1 pan-European, cross-sectional, population-based study (the European Eye [EUREYE] Study) were recruited between November 6, 2000, and April 30, 2007. Participants underwent dilated stereo-digital fundus photography graded according to the International Classification of Age-related Maculopathy and Macular Degeneration. There were 1727 cases of late AMD (1151 neovascular, 384 geographic atrophy, and 192 mixed [neovascular AMD and geographic atrophy]) and 1153 controls. Early AMD cases (n = 574) were included only from the EUREYE Study. Data analysis was performed from August 1 to November 30, 2016. Four common single-nucleotide polymorphisms (rs1205, rs1130864, rs1800947, and rs3093077) were selected based on demonstrated influence on circulating CRP concentrations in the literature. In one study, genotyping of rs3093077 failed, and rs1800947 was typed in only 1 study.

Main Outcomes and Measures

A genetic multiplicative model was used for the association of single-nucleotide polymorphisms with late AMD adjusted for age and sex.

Results

Among the 1727 patients with late AMD, the mean (SD) age was 78.7 (7.4) years, and 668 (38.7%) were men. The mean (SD) age of the controls was 74.9 (7.0) years, and 510 (44.2%) were men. In the pooled results of all 3 studies, neither rs1205 (odds ratio [OR], 0.99; 95% CI, 0.86-1.14) nor rs1130864 (OR, 0.96; 95% CI, 0.83-1.11) was associated with late AMD. For geographic atrophy, rs1205 had an OR of 0.91 (95% CI, 0.74-1.13) and rs1130864 had an OR of 0.94 (95% CI, 0.76-1.16). For neovascular AMD, rs1205 had an OR of 1.01 (95% CI, 0.87-1.19) and rs1130864 had an OR of 0.99 (95% CI, 0.84-1.16). There was no association of rs3093077 and rs1800947 with late AMD or any late AMD phenotype. There were no significant findings for early AMD.

Conclusions and Relevance

Our results do not support a causal association between CRP concentrations and AMD.

Correlation of neutrophil/lymphocyte and platelet/lymphocyte ratio with visual acuity and macular thickness in age-related macular degeneration

AIM

To investigate the place of neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) in the diagnosis of and prognosis for neovascular age-related macular degeneration (AMD).

METHODS

One hundred AMD patients and 100 healthy controls were included in the study. Blood samples were obtained from the venous blood, which is used for routine analysis, and these samples were subjected to complete blood count. NLR was defined as the neutrophil count divided by the number of lymphocytes, and PLR was defined as the platelet count divided by the number of lymphocytes.

RESULTS

No statistically significant difference was observed between the two groups under consideration in terms of demographic features (P>0.05). The average NLR in the patient group was found to be significantly higher than that in the healthy control group (P<0.05). The average PLR was significantly higher in the patient group as compared to the control group (P<0.05). As best corrected visual acuity (BCVA) increased, both NLR and PLR decreased (significant negative correlations at 49.8% and 63.0%, respectively), whereas as central macular thickness (CMT) increased, both NLR and PLR increased (significant positive correlations at 59.3% and 70.0%, respectively).

CONCLUSION

NLR and PLR levels are higher among neovascular AMD patients as compared to healthy control group. NLR and PLR levels were found to be inversely proportional to BCVA and directly proportional to CMT.

Systemic and ocular fluid compounds as potential biomarkers in age-related macular degeneration

Biomarkers can help unravel mechanisms of disease and identify new targets for therapy. They can also be useful in clinical practice for monitoring disease progression, evaluation of treatment efficacy, and risk assessment in multifactorial diseases, such as age-related macular degeneration (AMD). AMD is a highly prevalent progressive retinal disorder for which multiple genetic and environmental risk factors have been described, but the exact etiology is not yet fully understood. Many compounds have been evaluated for their association with AMD. We performed an extensive literature review of all compounds measured in serum, plasma, vitreous, aqueous humor, and urine of AMD patients. Over 3600 articles were screened, resulting in more than 100 different compounds analyzed in AMD studies, involved in neovascularization, immunity, lipid metabolism, extracellular matrix, oxidative stress, diet, hormones, and comorbidities (such as kidney disease). For each compound, we provide a short description of its function and discuss the results of the studies in relation to its usefulness as AMD biomarker. In addition, biomarkers identified by hypothesis-free techniques, including metabolomics, proteomics, and epigenomics, are covered. In summary, compounds belonging to the oxidative stress pathway, the complement system, and lipid metabolism are the most promising biomarker candidates for AMD. We hope that this comprehensive survey of the literature on systemic and ocular fluid compounds as potential biomarkers in AMD will provide a stepping stone for future research and possible implementation in clinical practice.

Gut microbiota influences pathological angiogenesis in obesity-driven choroidal neovascularization

Age-related macular degeneration in its neovascular form (NV AMD) is the leading cause of vision loss among adults above the age of 60. Epidemiological data suggest that in men, overall abdominal obesity is the second most important environmental risk factor after smoking for progression to late-stage NV AMD To date, the mechanisms that underscore this observation remain ill-defined. Given the impact of high-fat diets on gut microbiota, we investigated whether commensal microbes influence the evolution of AMD Using mouse models of NV AMD, microbiotal transplants, and other paradigms that modify the gut microbiome, we uncoupled weight gain from confounding factors and demonstrate that high-fat diets exacerbate choroidal neovascularization (CNV) by altering gut microbiota. Gut dysbiosis leads to heightened intestinal permeability and chronic low-grade inflammation characteristic of inflammaging with elevated production of IL-6, IL-1β, TNF-α, and VEGF-A that ultimately aggravate pathological angiogenesis.

Aged complement factor H knockout mice kept in a clean barriered environment have reduced retinal pathology

Age-related macular degeneration (AMD) is the largest cause of visual loss in those over 60 years in the West and is a condition increasing in prevalence. Many diseases result from genetic/environmental interactions and 50% of AMD cases have an association with polymorphisms of the complement system including complement factor H. Here we explore interactions between genetic predisposition and environmental conditions in triggering retinal pathology in two groups of aged complement factor H knock out (Cfh(-/-)) mice. Mice were maintained over 9 months in either a conventional open environment or a barriered pathogen free environment. Open environment Cfh(-/-) mice had significant increases in subretinal macrophage numbers, inflammatory and stress responses and reduced photoreceptor numbers over mice kept in a pathogen free environment. Hence, environmental factors can drive retinal disease in these mice when linked to complement deficits impairing immune function. Both groups of mice had similar levels of retinal amyloid beta accumulation. Consequently there is no direct link between this and inflammation in Cfh(-/-) mice.

ASSOCIATIONS BETWEEN AGE-RELATED MACULAR DEGENERATION, OSTEOARTHRITIS AND RHEUMATOID ARTHRITIS: RECORD LINKAGE STUDY

PURPOSE

The epidemiologic relationship between age-related macular degeneration (AMD) and arthritis is unknown and has implications for understanding disease pathogenesis and treatment strategies.

METHODS

An AMD cohort of 245,912 people was constructed from English linked hospital episode statistics (1999-2011), principally comprising neovascular AMD patients undergoing anti-vascular endothelial growth factor therapy. We compared the AMD cohort with a reference cohort (2,134,771 people) for rates of subsequent osteoarthritis (OA) and rheumatoid arthritis. Osteoarthritis (2,032,472 people) and rheumatoid arthritis (261,232 people) cohorts were also constructed and compared with the reference cohort for rates of subsequent AMD.

RESULTS

Risk of arthritis after AMD was not elevated. The rate ratio for OA was 0.96 (95% confidence interval 0.95-0.97) and for rheumatoid arthritis was 0.98 (0.94-1.02). However, risk of AMD after arthritis was modestly raised. For OA, the rate ratio was 1.06 (1.04-1.08), but risk increased with longer OA duration, for example, 1.15 (1.08-1.23) for >10 years. For rheumatoid arthritis, the rate ratio was also modestly elevated at 1.15 (1.12-1.19).

CONCLUSION

Age-related macular degeneration and arthritis are degenerative aging conditions that share some disease mechanisms and extracellular matrix involvement. However, considering arthritis after AMD, they are not positively associated. By contrast, people with OA experience modestly increased AMD risk, perhaps owing to medical treatments for OA.

The broad-spectrum chemokine inhibitor NR58-3.14.3 modulates macrophage-mediated inflammation in the diseased retina

Background

The activity of macrophages is implicated in the progression of retinal pathologies such as atrophic age-related macular degeneration (AMD), where they accumulate among the photoreceptor layer and subretinal space. This process is aided by the local expression of chemokines, which furnish these cells with directional cues that augment their migration to areas of retinal injury. While these qualities make chemokines a potential therapeutic target in curtailing damaging retinal inflammation, their wide variety and signalling redundancy pose challenges in broadly modulating their activity. Here, we examine the efficacy of the broad-spectrum chemokine inhibitor NR58-3.14.3—a suppressor of Ccl- and Cxcl- chemokine pathways—in suppressing macrophage activity and photoreceptor death, using a light-induced model of outer retinal atrophy and inflammation.

Methods

Photo-oxidative damage was induced in SD rats via exposure to 1000 lux of light for 24 h, after which animals were euthanized at 0- or 7-day post-exposure time points. Prior to damage, NR58-3.14.3 was injected intravitreally. Retinas were harvested and evaluated for the effect of NR58-3.14.3 on subretinal macrophage accumulation and cytokine expression profile, as well as photoreceptor degeneration.

Results

We report that intravitreal administration of NR58-3.14.3 reduces the accumulation of macrophages in the outer retina following exposure to light damage, at both 0- and 7-day post-exposure time points. Injection of NR58-3.14.3 also reduced the up-regulation of inflammatory markers including of Il6, Ccl3, and Ccl4 in infiltrating macrophages, which are promoters of their pathogenic activity in the retina. Finally, NR58-3.14.3-injected retinas displayed markedly reduced photoreceptor death following light damage, at both 0 and 7 days post-exposure.

Conclusions

Our findings indicate that NR58-3.14.3 is effective in inhibiting subretinal macrophage accumulation in light-induced retinal degeneration and illustrate the potential of broad-spectrum chemokine inhibitors as novel therapeutic agents in thwarting retinal inflammation. Although broad-spectrum chemokine inhibitors may not be appropriate for all retinal inflammatory conditions, our results suggest that they may be beneficial for retinal dystrophies in which chemokine expression and subretinal macrophage accumulation are implicated, such as advanced AMD.

Incidence of Age-Related Macular Degeneration in a Multi-Ethnic United States Population: The Multi-Ethnic Study of Atherosclerosis

PURPOSE

To describe the incidence of age-related macular degeneration (AMD) and associated risk factors in 4 racial/ethnic groups (white, black, Hispanic, and Chinese) residing in the United States.

DESIGN

Prospective cohort study.

PARTICIPANTS

A total of 3811 participants, aged 46 to 86 years, from the Multi-Ethnic Study of Atherosclerosis (MESA) cohort, with retinal data collected twice, on average, 8 years apart.

METHODS

Fundus images, taken using a digital camera through dark-adapted pupils using a standard protocol and the same equipment at both study visits, were graded centrally for early and late AMD on the basis of drusen size, type and area, increased retinal pigment, retinal pigment epithelial depigmentation, neovascular lesions, and geographic atrophy using the modified Wisconsin Age-Related Maculopathy Grading System. Demographic, clinical, and laboratory measures were included in multivariable regression models to determine their impact on the variation in AMD incidence among racial/ethnic groups.

MAIN OUTCOME MEASURES

Incident early and late AMD.

RESULTS

The overall 8-year age- and sex-standardized incidence of early and late AMD were 4.1% and 2.3%, respectively, with incidence of early and late AMD highest in whites (5.3% and 4.1%, respectively), intermediate in Chinese (4.5% and 2.2%, respectively) and Hispanics (3.3% and 0.8%, respectively), and lowest in blacks (1.6% and 0.4%, respectively). By adjusting for age and sex, blacks had a 70% lower risk of developing early AMD than whites, and this decreased only slightly to a 67% lower risk after multivariable adjustment. By adjusting for age, sex, and race/ethnicity, hyperopia was associated with early AMD (odds ratio [OR], 1.51; 95% confidence interval [CI], 1.04-2.20), as was astigmatism (OR, 1.47; 95% CI, 1.00-2.16), but not myopia (P = 0.29). Age, race/ethnicity, current smoking, hyperopia, and AMD-susceptibility genotypes Complement Factor H (CFH) RS1061170 and Age Related Maculopathy Susceptibility 2 (ARMS2) RS3793917 were independently associated with incident early AMD in multivariable models for the combined sample. However, the only statistically significant factor consistently associated with incident early AMD across the 4 racial/ethnic groups was increasing age. Risk factors for late AMD were not assessed because of its low incidence, particularly across racial/ethnic groups.

CONCLUSIONS

Variation in the incidence of early AMD exists among racial/ethnic groups in the United States and is not explained by the clinical, genetic, and environmental factors included in this study.

Tumor Necrosis Factor Gene Polymorphisms in Advanced Non-exudative Age-related Macular Degeneration

Purpose:

To investigate tumor necrosis factor (TNF)-α gene polymorphisms in advanced dry-type age-related macular degeneration (AMD) in a population from Northeastern Iran.

Methods:

In this case-control study, 50 patients with geographic macular atrophy and 73 gender-matched controls were enrolled. Genomic deoxyribonucleic acid (DNA) was extracted from the peripheral blood. Polymerase chain reaction was performed to analyze 2 candidate single nucleotide polymorphisms in the TNF-α gene, namely −1031 thymine (T)/cytosine (C) and −308 guanine (G)/adenine (A).

Results:

The distribution of the - 1031 T/C genotype was TT, 62%; TC, 36%; CC, 2% in the patients and TT, 60%; TC, 36%; CC, 4% in the controls (P = 0.94). Genotype analysis of TNF-α −308 also revealed no significant difference in distribution between patients (G, 78%; GA, 22%; AA, 0%) and controls (GG, 74%; GA, 23%; AA, 3%) (P = 0.51). None of the haplotypes nor alleles of studied TNF-α polymorphisms were significantly associated with advanced dry-type AMD.

Conclusion:

The findings of this study show that polymorphisms in the TNF-α gene, do not play an important role in dry-type AMD in the studied population.

Apolipoprotein E promotes subretinal mononuclear phagocyte survival and chronic inflammation in age-related macular degeneration

Physiologically, the retinal pigment epithelium (RPE) expresses immunosuppressive signals such as FAS ligand (FASL), which prevents the accumulation of leukocytes in the subretinal space. Age-related macular degeneration (AMD) is associated with a breakdown of the subretinal immunosuppressive environment and chronic accumulation of mononuclear phagocytes (MPs). We show that subretinal MPs in AMD patients accumulate on the RPE and express high levels of APOE. MPs of Cx3cr1(-/-) mice that develop MP accumulation on the RPE, photoreceptor degeneration, and increased choroidal neovascularization similarly express high levels of APOE. ApoE deletion in Cx3cr1(-/-) mice prevents pathogenic age- and stress-induced subretinal MP accumulation. We demonstrate that increased APOE levels induce IL-6 in MPs via the activation of the TLR2-CD14-dependent innate immunity receptor cluster. IL-6 in turn represses RPE FasL expression and prolongs subretinal MP survival. This mechanism may account, in part, for the MP accumulation observed in Cx3cr1(-/-) mice. Our results underline the inflammatory role of APOE in sterile inflammation in the immunosuppressive subretinal space. They provide rationale for the implication of IL-6 in AMD and open avenues toward therapies inhibiting pathogenic chronic inflammation in late AMD.

Early and exudative age-related macular degeneration is associated with increased plasma levels of soluble TNF receptor II

PURPOSE

We have recently identified homeostatic alterations in the circulating T cells of patients with age-related macular degeneration (AMD). In cultures of retinal pigment epithelial cells, we have demonstrated that T-cell-derived cytokines induced the upregulation of complement, chemokines and other proteins implicated in AMD pathogenesis. The purpose of this study was to test whether increased plasma levels of cytokines were present in patients with AMD.

METHODS

We conducted a case-control study. Age-related macular degeneration status was assessed using standardized multimodal imaging techniques. Plasma was isolated from freshly drawn peripheral venous blood samples and analysed for interleukin (IL)15, IL18, interferon (IFN)γ, soluble tumour necrosis factor (TNF) receptor II (sTNFRII) and complement factor H (CFH) Y402H genotype.

RESULTS

We included 136 individuals with early or late forms of AMD and 74 controls. Significantly increased levels of sTNFRII were observed in patients with early or exudative AMD (p < 0.01). After adjusting for CFH Y402H genotype, age, sex and smoking history, the level of sTNFRII remained a significant predictor for prevalence of AMD with odds ratios at 3.0 in the middle and 3.6 in the highest tertiles. Levels of IL15, IL18 and IFNγ were low and not associated with AMD.

CONCLUSIONS

Increased plasma level of sTNFRII is found to be associated with AMD. The data supports the observations of low-grade, systemic inflammatory alterations in patients with AMD. However, it remains to be determined whether increased levels of TNFα can be found, which directly reflects an increased activity of macrophages and T cells.

Reduced photoreceptor death and improved retinal function during retinal degeneration in mice lacking innate immunity adaptor protein MyD88

The injury inflammatory response mediated by the innate immune system is an important contributor to neurodegeneration in the central nervous system (CNS) and retina. A major branch of the innate immune system is regulated by the Toll-like receptors (TLRs), which are receptors for endogenous damage associated molecules released from injured cells as well as pathogen-derived molecules, and interleukin-1 receptors (IL-1R), which are activated by IL-1α, IL-1β and IL-18 cytokines. TLRs and IL-1R are expressed on immune and non-immune cell types and act as first responders to cell damage, which results in tissue repair, or inflammation and apoptosis. Both TLR and IL-1R require the adaptor protein myeloid differentiation primary response gene 88 (MyD88) for signaling. Although inflammation is implicated in neuronal death in the retina, the role of MyD88-dependent TLR and IL-1R signaling in retinal degeneration is unknown. Therefore, the purpose of this study was to investigate the role of MyD88-mediated signaling in neuronal degeneration in the retinal degeneration 1 (rd1) mouse model, which exhibits a phenotype of rapid photoreceptor death and inflammation. To generate rd1 mice lacking the MyD88 gene, rd1 were bred with MyD88 knockout mice (MyD88(-/-)) for several generations to produce rd1/MyD88(+/+) and rd1/MyD88(-/-) genotypes. Chemokine mRNA expression levels were analyzed by qRT-PCR, and recruitment of activated microglia was quantified by immunodetection of the IBA-1 protein. Retinal outer nuclear layer cell counts were performed to quantify photoreceptor degeneration, and retinal function was assessed using electroretinograms (ERG). Our results revealed that retinal expression of Ccl2, Ccl4, Ccl7 and Cxcl10 was reduced by 2 to 8-fold in rd1/MyD88(-/-) mice compared with rd1/MyD88(+/+) mice (p<0.05), which coincided with attenuated microglial activation, higher numbers of photoreceptors and higher retina responses to photopic and scotopic stimuli. At later ages, rd1/MyD88(-/-) had reduced chemokine expression and higher photopic responses but no change in microglial recruitment compared with rd1 mice with functional MyD88. In conclusion, lack of MyD88-mediated signaling increased photoreceptor survival and retina function in rd1 mice, which implicates MyD88-mediated innate immunity pathways as an important pathogenic factor during retinal degeneration.

Genetic determinants of age-related macular degeneration in diverse populations from the PAGE study

PURPOSE

Substantial progress has been made in identifying susceptibility variants for AMD in European populations; however, few studies have been conducted to understand the role these variants play in AMD risk in diverse populations. The present study aims to examine AMD risk across diverse populations in known and suspected AMD complement factor and lipid-related loci.

METHODS

Targeted genotyping was performed across study sites for AMD and lipid trait-associated single nucleotide polymorphism (SNPs). Genetic association tests were performed at individual sites and then meta-analyzed using logistic regression assuming an additive genetic model stratified by self-described race/ethnicity. Participants included cases with early or late AMD and controls with no signs of AMD as determined by fundus photography. Populations included in this study were European Americans, African Americans, Mexican Americans, and Singaporeans from the Population Architecture using Genomics and Epidemiology (PAGE) study.

RESULTS

Index variants of AMD, rs1061170 (CFH) and rs10490924 (ARMS2), were associated with AMD at P=3.05×10(-8) and P=6.36×10(-6), respectively, in European Americans. In general, none of the major AMD index variants generalized to our non-European populations with the exception of rs10490924 in Mexican Americans at an uncorrected P value<0.05. Four lipid-associated SNPS (LPL rs328, TRIB1 rs6987702, CETP rs1800775, and KCTD10/MVK rs2338104) were associated with AMD in African Americans and Mexican Americans (P<0.05), but these associations did not survive strict corrections for multiple testing.

CONCLUSIONS

While most associations did not generalize in the non-European populations, variants within lipid-related genes were found to be associated with AMD. This study highlights the need for larger well-powered studies in non-European populations.

Is age-related macular degeneration a manifestation of systemic disease? New prospects for early intervention and treatment

Age-related macular degeneration (AMD) is a common vision-threatening condition affecting the elderly. AMD shares common risk factors and processes, including vascular and inflammatory pathways, with many systemic disorders. Associations have been reported between AMD and hypertension, cardiovascular disease, cerebrovascular disease, dyslipidaemia, chronic kidney disease and neurodegenerative disorders. An increasing amount of evidence suggests that individuals with AMD are also at risk of systemic diseases such as stroke. In this review, we summarize the latest evidence to support the notion that AMD is an ocular manifestation of systemic disease processes, and discuss the potential systemic side effects of ocular AMD therapy of which general physicians should be aware. Recent genetic discoveries and understanding of the pathogenic pathways in AMD in relation to systemic disorders are also highlighted.

Markers of inflammation, oxidative stress, and endothelial dysfunction and the 20-year cumulative incidence of early age-related macular degeneration: the Beaver Dam Eye Study

IMPORTANCE Modifying levels of factors associated with age-related macular degeneration (AMD) may decrease the risk for visual impairment in older persons. OBJECTIVE To examine the relationships of markers of inflammation, oxidative stress, and endothelial dysfunction to the 20-year cumulative incidence of early AMD. DESIGN, SETTING, AND PARTICIPANTS This longitudinal population-based cohort study involved a random sample of 975 persons in the Beaver Dam Eye Study without signs of AMD who participated in the baseline examination in 1988-1990 and up to 4 follow-up examinations in 1993-1995, 1998-2000, 2003-2005, and 2008-2010. EXPOSURES Serum markers of inflammation (high-sensitivity C-reactive protein, tumor necrosis factor-α receptor 2, interleukin-6, and white blood cell count), oxidative stress (8-isoprostane and total carbonyl content), and endothelial dysfunction (soluble vascular cell adhesion molecule-1 and soluble intercellular adhesion molecule-1) were measured. Interactions with complement factor H (rs1061170), age-related maculopathy susceptibility 2 (rs10490924), complement component 3 (rs2230199), and complement component 2/complement factor B (rs4151667) were examined using multiplicative models. Age-related macular degeneration was assessed from fundus photographs. MAIN OUTCOMES AND MEASURES Early AMD defined by the presence of any size drusen and the presence of pigmentary abnormalities or by the presence of large-sized drusen (≥125-μm diameter) in the absence of late AMD. RESULTS The 20-year cumulative incidence of early AMD was 23.0%. Adjusting for age, sex, and other risk factors, high-sensitivity C-reactive protein (odds ratio comparing fourth with first quartile, 2.18; P = .005), tumor necrosis factor-α receptor 2 (odds ratio, 1.78; P = .04), and interleukin-6 (odds ratio, 1.78; P = .03) were associated with the incidence of early AMD. Increased incidence of early AMD was associated with soluble vascular cell adhesion molecule-1 (odds ratio per SD on the logarithmic scale, 1.21; P = .04). CONCLUSIONS AND RELEVANCE We found modest evidence of relationships of serum high-sensitivity C-reactive protein, tumor necrosis factor-α receptor 2, interleukin-6, and soluble vascular cell adhesion molecule-1 to the 20-year cumulative incidence of early AMD independent of age, smoking status, and other factors. It is not known whether these associations represent a cause and effect relationship or whether other unknown confounders accounted for the findings. Even if inflammatory processes are a cause of early AMD, it is not known whether interventions that reduce systemic inflammatory processes will reduce the incidence of early AMD.

Consumption of dairy products and the 15-year incidence of age-related macular degeneration

Habitual consumption of dairy products has been shown to play an important role in the prevention of several chronic diseases. We aimed to prospectively assess the relationship between the change in dairy product consumption (both regular fat and low/reduced fat) and the 15-year incidence of age-related macular degeneration (AMD). In the Blue Mountains Eye Study, 2037 participants aged 49 years or above at baseline were re-examined at follow-up in 1997-9, 2002-4 and/or 2007-9. AMD was assessed from retinal photographs. Dietary data were collected using a semi-quantitative FFQ, and servings of dairy product consumption calculated. Over the 15-year follow-up, there were 352, 268 and eighty-four incident cases of any, early and late AMD, respectively. After adjusting for age, sex, current smoking, white cell count and fish consumption, a significant linear trend (P for trend = 0·003) was observed with decreasing consumption of total dairy foods and the 15-year incidence of late AMD, comparing the lowest v. highest quintile of intake (OR 2·80, 95 % CI 1·21, 3·04). Over the 15 years, decreased consumption of reduced-fat dairy foods was associated with an increased risk of incident late AMD, comparing the lowest to highest quintile of intake (OR 3·10, 95 % CI 1·18, 8·14, P for trend = 0·04). Decreasing total dietary Ca intake over the 15 years was also associated with an increased risk of developing incident late AMD (multivariable-adjusted P for trend = 0·03). A lower consumption of dairy products (regular and low fat) and Ca was independently associated with a higher risk of developing incident late AMD in the long term. Additional cohort studies are needed to confirm these findings.

CFH haplotypes and ARMS2, C2, C3, and CFB alleles show association with susceptibility to age-related macular degeneration in Mexicans

PURPOSE

To evaluate the contribution of genetic variants of complement factor H (CFH), complement component 2 and 3 (C2 and C3), complement factor B (CFB), and age-related maculopathy susceptibility 2 (ARMS2) to age-related macular degeneration (AMD) risk in the Mexican Mestizo population.

METHODS

Analysis included 282 unrelated Mexican patients with advanced AMD, 205 healthy controls, and 280 population controls. Stereoscopic fundus images were graded on the Clinical Age-Related Maculopathy System (CARMS). We designed a resequencing strategy using primers with M13 adaptor for the 23 exons of the CFH gene in a subgroup of 96 individuals clinically evaluated: 48 AMD cases and 48 age- and sex-matched healthy controls. Single nucleotide polymorphisms (SNPs) in C3 (Arg80Gly and Pro292Leu), C2 (rs547154), CFB (Leu9His), and ARMS2 (Ala69Ser) were genotyped in all patients, healthy and population controls using TaqMan assay.

RESULTS

All evaluated individuals were Mexican Mestizos, and their genetic ancestry was validated using 224 ancestry informative markers and calculating F(st) values. The CFH resequencing revealed 19 SNPs and a common variant in the intron 2 splice acceptor site; three CFH haplotypes inferred from individual genotypes, showed significant differences between cases and controls. The risk alleles in C3 (rs1047286, odds ratio [OR]=2.48, 95% confidence interval [CI]=1.64-3.75, p=1.59E-05; rs2230199, OR=2.15, 95% CI=1.48-3.13, p=6.28E-05) and in ARMS2 (rs10490924, OR=3.09, 95% CI=2.48-3.86, p=5.42E-23) were strongly associated with risk of AMD. The protective effect of alleles in C2 (rs547154) and CFB (rs4151667) showed a trend but was not significantly associated after correction for multiple testing.

CONCLUSIONS

Our results show that ARMS2 and C3 are major contributors to advanced AMD in Mexican patients, while the contributions of CFH, C2, and CFB are minor to those of other populations, reveling significant ethnic differences in minor allele frequencies. We provide evidence that two specific common haplotypes in the CFH gene predispose individuals to AMD, while another may confer reduced risk of disease in this admixed population.

Associations of candidate genes to age-related macular degeneration among racial/ethnic groups in the multi-ethnic study of atherosclerosis

PURPOSE

To describe the relationships of selected candidate genes to the prevalence of early age-related macular degeneration (AMD) in a cohort of whites, blacks, Hispanics, and Chinese Americans.

DESIGN

Cross-sectional study.

METHODS

setting: Multicenter study. study population: A total of 2456 persons aged 45-84 years with genotype information and fundus photographs. procedures: Twelve of 2862 single nucleotide polymorphisms (SNPs) from 11 of 233 candidate genes for cardiovascular disease were selected for analysis based on screening with marginal unadjusted P value <.001 within 1 or more racial/ethnic groups. Logistic regression models tested for association in case-control samples. main outcome measure: Prevalence of early AMD.

RESULTS

Early AMD was present in 4.0% of the cohort and varied from 2.4% in blacks to 6.0% in whites. The odds ratio increased from 2.3 for 1 to 10.0 for 4 risk alleles in a joint effect analysis of Age-Related Maculopathy Susceptibility 2 rs10490924 and Complement Factor H Y402H (P for trend = 4.2×10(-7)). Frequencies of each SNP varied among the racial/ethnic groups. Adjusting for age and other factors, few statistically significant associations of the 12 SNPs with AMD were consistent across all groups. In a multivariate model, most candidate genes did not attenuate the comparatively higher odds of AMD in whites. The higher frequency of risk alleles for several SNPs in Chinese Americans may partially explain their AMD frequency's approaching that of whites.

CONCLUSIONS

The relationships of 11 candidate genes to early AMD varied among 4 racial/ethnic groups, and partially explained the observed variations in early AMD prevalence among them.