Association of Smoking, Alcohol Consumption, Blood Pressure, Body Mass Index, and Glycemic Risk Factors With Age-Related Macular Degeneration: A Mendelian Randomization Study

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.

THE USE OF NON-PERSON-FIRST LANGUAGE IN CONSECUTIVE GENERAL OPHTHALMOLOGY REFERRALS

PURPOSE

To investigate the prevalence of non-person-first language (PFL) in consecutive general ophthalmology referrals to a single tertiary ophthalmology clinic.

DESIGN

Retrospective cross-sectional study.

METHODS

Participants included Ophthalmology patients seen for their initial visit to a single tertiary ophthalmology clinic from July 2018 to December 2022. Ten randomly selected referrals from each day were screened for non-PFL as per the American Medical Association and American Psychological Association guidelines. Non-PFL was further categorized into general, diabetes, stigma, obesity, or ageism subcategories. The Chi-square test was used to evaluate associations between non-PFL use and referring provider gender and specialty, length of referral, and patient age and gender.

RESULTS

A total of 2625 referrals were included in the study and 136 (5.2%) used non-PFL, such as referring to a person with diabetes as a "diabetic". Error types included Diabetes (38.2%), Stigma (30.9%), General (23.5%), Disability (8.8%), and Obesity (4.4%). Year of referral was predictive of non-PFL (p=0.0016), with most occurring in 2020 (9.5%). Non-PFL was significantly more likely to occur in long length referrals compared to medium and short length referrals (16.2% vs. 5.1% vs. 3.5%, p<0.001). Referring provider specialty was also predictive of non-PFL (p<0.001) with most received by Family Medicine (8.3%), Optometry (4.4%), Emergency Medicine (0.62%), Ophthalmology (4.2%), Others (2.9%). Patient gender (p=0.5563), patient age (p=0.3466), and referring provider gender (p=0.9057) were not predictive of non-PFL.

CONCLUSIONS

Non-PFL use was most prevalent in 2020, with the most common referral sources being Family Medicine and Optometry. The highest proportions of non-PFL errors made were diabetes and stigma errors. Increased use of PFL in physician-physician communication can decrease intersectional stigma and promote inclusive patient care for ophthalmology patients.

Application of mendelian randomization in ocular diseases: a review

Ocular disorders can significantly lower patients' quality of life and impose an economic burden on families and society. However, for the majority of these diseases, their prevalence and mechanisms are yet unknown, making prevention, management, and therapy challenging. Although connections between exposure factors and diseases can be drawn through observational research, it is challenging to rule out the interference of confounding variables and reverse causation. Mendelian Randomization (MR), a method of research that combines genetics and epidemiology, has its advantage to solve this problem and thus has been extensively utilized in the etiological study of ophthalmic diseases. This paper reviews the implementation of MR in the research of ocular diseases and provides approaches for the investigation of related mechanisms as well as the intervention strategies.

Predictors and consequences of visual trajectories in Chinese older population: A growth mixture model

Background

Given the relatively high prevalence of vision impairment and the heterogeneity of visual changes among the elderly population, we aimed to identify the visual trajectories and to examine the predictors and consequences associated with each trajectory class.

Methods

We analysed data from 2235 participants involved in the 5th, 6th, 7th, and 8th waves of the Chinese Longitudinal Healthy Longevity Survey (CLHLS), where vision impairment was evaluated using an adapted Landolt-C chart during each wave. We employed a growth mixture model (GMM) to identify distinct visual trajectories and logistic regression analysis to examine the predictors associated with each trajectory class. Furthermore, we investigated the effect of visual trajectories on distal consequences, including cognitive function, activities of daily living (ADL), instrumental activities of daily living (IADL), depression, anxiety, and fall risk. Within the CLHLS study, cognitive function was assessed using the Chinese version of the Mini-Mental State Examination (CMMSE), ADL via the Katz index, and IADL through a modified version of Lawton's scale. Lastly, depression was assessed using the 10-item version of the Centre for Epidemiologic Studies (CES-D-10), while anxiety was measured using the Generalized Anxiety Disorder scale (GAD-7). Fall risk was determined by asking the question: 'Have you experienced any falls within the past year?'

Results

We identified two distinct visual trajectories in our analysis. Most older adults (n = 1830, 81.9%) initially had a good vision level that diminished ('high-baseline decline' group). Conversely, the remaining participants (n = 405, 18.1%) initially had a lower vision level that improved over time ('low-baseline improvement' group). The 'high-baseline decline' group was more likely to include older adults with relatively higher body mass index (BMI) (odds ratio (OR) = 1.086; 95% confidence interval (CI) = 1.046, 1.127), individuals with higher formal educational qualifications (OR = 1.411; 95% CI = 1.068, 1.864), those current engaging in exercise (OR = 1.376; 95% CI = 1.046, 1.811), and individuals reporting more frequent consumption of fruit (OR = 1.357; 95% CI = 1.053, 1.749). Conversely, the 'low-baseline improvement' group had a higher likelihood of including older individuals (OR = 0.947; 95% CI = 0.934, 0.961), residents of nursing homes (OR = 0.340; 95% CI = 0.116, 0.993) and those self-reporting cataracts (OR = 0.268; 95% CI = 0.183, 0.391) and glaucoma (OR = 0.157; 95% CI = 0.079, 0.315). Furthermore, the 'high-baseline decline' group showed a positive impact on distal consequences, adjusting for sex, birthplace, residence, main occupation, education, economic status, and marital status. This impact included cognitive function (correlation coefficient (β) = 2.092; 95% CI = 1.272, 2.912), ADL (β  = -0.362; 95% CI = -0.615, -0.108), IADL (β  = -1.712; 95% CI = -2.304, -1.121), and reported lower levels of depression (β  = 0.649; 95% CI = 0.013, 1.285). We observed no significant influence on fall risk and anxiety within the identified visual trajectories in the adjusted model.

Conclusions

Vision in older adults with ocular disease could potentially be improved. Having formal education, maintaining an appropriate BMI, engaging in exercise, and consuming fruit more frequently appear to be beneficial for the visual health of the elderly. Considering the negative impact of visual impairment experience on distal cognition, self-care ability, and depression symptoms, stakeholder should prioritise long-term monitoring and management of vision impairment among older adults.

Alcohol Exposure and Disease Associations: A Mendelian Randomization and Meta-Analysis on Weekly Consumption and Problematic Drinking

Alcohol consumption significantly impacts disease burden and has been linked to various diseases in observational studies. However, comprehensive meta-analyses using Mendelian randomization (MR) to examine drinking patterns are limited. We aimed to evaluate the health risks of alcohol use by integrating findings from MR studies. A thorough search was conducted for MR studies focused on alcohol exposure. We utilized two sets of instrumental variables-alcohol consumption and problematic alcohol use-and summary statistics from the FinnGen consortium R9 release to perform de novo MR analyses. Our meta-analysis encompassed 64 published and 151 de novo MR analyses across 76 distinct primary outcomes. Results show that a genetic predisposition to alcohol consumption, independent of smoking, significantly correlates with a decreased risk of Parkinson's disease, prostate hyperplasia, and rheumatoid arthritis. It was also associated with an increased risk of chronic pancreatitis, colorectal cancer, and head and neck cancers. Additionally, a genetic predisposition to problematic alcohol use is strongly associated with increased risks of alcoholic liver disease, cirrhosis, both acute and chronic pancreatitis, and pneumonia. Evidence from our MR study supports the notion that alcohol consumption and problematic alcohol use are causally associated with a range of diseases, predominantly by increasing the risk.

Causal Associations of Glaucoma and Age-Related Macular Degeneration with Cataract: A Bidirectional Two-Sample Mendelian Randomisation Study

Common age-related eye disorders include glaucoma, cataract, and age-related macular degeneration (AMD); however, little is known about their relationship with age. This study investigated the potential causal relationship between glaucoma and AMD with cataract using genetic data from multi-ethnic populations. Single-nucleotide polymorphisms (SNPs) associated with exposure to cataract were selected as instrumental variables (IVs) from genome-wide association studies using meta-analysis data from BioBank Japan and UK Biobank. A bidirectional two-sample Mendelian randomisation (MR) study was conducted to assess the causal estimates using inverse variance weighted, MR-Egger, and MR pleiotropy residual sum and outlier tests. SNPs with (p < 5.0 × 10-8) were selected as IVs for cataract, primary open-angle glaucoma, and AMD. We found no causal effects of cataract on glaucoma or AMD (all p > 0.05). Furthermore, there were no causal effects of AMD on cataract (odds ratio [OR] = 1.02, p = 0.400). However, glaucoma had a substantial causal effect on cataract (OR = 1.14, p = 0.020). Our study found no evidence for a causal relationship of cataract on glaucoma or AMD and a casual effect of AMD on cataract. Nonetheless, glaucoma demonstrates a causal link with cataract formation, indicating the need for future investigations of age-related eye diseases.

Impact of smoking on glaucoma

PURPOSE OF REVIEW

Assessing whether lifestyle related factors play a role in causing primary open-angle glaucoma (POAG) is of great value to clinicians, public health experts and policy makers. Smoking is a major global public health concern and contributes to ocular diseases such as cataracts, and age-related macular degeneration through ischemic and oxidative mechanisms. Recently, smoking has been investigated as a modifiable risk factor for glaucoma. In the presence of an association with glaucoma, provision of advice and information regarding smoking to patients may help reduce the burden of disease caused by POAG. Therefore, the aim of this review is to summarize the current evidence regarding the effect of smoking in the pathogenesis of glaucoma and its incidence, progression as well as the benefits of smoking cessation.

RECENT FINDINGS

While the association between glaucoma development and smoking history is controversial, in the last decade, several recent studies have helped to identify possible effects of smoking, especially heavy smoking, in regard to glaucomatous progression. Smoking cessation may possibly be protective against glaucoma progression.

SUMMARY

Smoking may play a role in glaucoma progression and long-term smoking cessation may be associated with lower glaucoma progression. The dose-response relationship between smoking and glaucoma as well as therapeutic potential of smoking cessation needs to be further validated with both preclinical and rigorous clinical studies.

AMD and Stem Cell-Based Therapies

Age-related macular degeneration (AMD) is a prevalent and complex disease leading to severe vision loss. Stem cells offer promising prospects for AMD treatment as they can be differentiated into critical retinal cell types that could replace lost host retinal cells or provide trophic support to promote host retinal cell survival. However, challenges such as immune rejection, concerns regarding tumorigenicity, and genomic integrity must be addressed. Clinical trials with stem cell-derived retinal pigment epithelial cells have shown preliminary safety in treating dry AMD, but improvements in manufacturing and surgical techniques cell delivery are needed. Late-stage AMD poses additional hurdles, possibly requiring multi-layered grafts. Advancements in automation technologies and gene correction strategies show potential to enhance iPSC-based therapies. Stem cell-based treatments offer hope for AMD management, but further research and optimization are essential for successful clinical implementation.

Causality of Diabetic Nephropathy and Age-Related Macular Degeneration: A Mendelian Randomization Study

PURPOSE

Age-related macular degeneration (AMD) currently stands as the leading cause of irreversible vision loss in the present era. The primary objective of this study was to investigate the causal relationships between diabetic nephropathy (DN), its associated risk factors, and AMD among participants of European descent.

METHODS

Genetic variants associated with DN and its risk factors, encompassing glycemic traits, lipidemic traits, systolic/diastolic blood pressure, obesity, and urate, were obtained from previously published genome-wide association studies. Summary-level statistics for AMD were acquired from the FinnGen database. Univariable and multivariable Mendelian randomization (MR) were employed to conduct this investigation.

RESULTS

Our MR analyses indicated that per 1-standard deviation (SD) increase of DN heightened the risk of overall AMD (p = 1.03 × 10-8, OR = 1.24). And these findings remained consistent when examining both dry AMD (p = 2.27 × 10-4, OR = 1.17) and wet AMD (p = 5.15 × 10-6, OR = 1.33). Additionally, there was a causal association between high-density lipoprotein-cholesterol (HDL-C) levels and an increased risk of AMD (p = 2.69 × 10-3, OR = 1.23), while triglycerides were found to mitigate the risk (p = 0.02, OR = 0.83). Notably, no significant associations were observed between other risk factors of DN and AMD.

CONCLUSIONS

These findings suggest that the impact of DN on the development of AMD may be more substantial than previously believed. Furthermore, elevated HDL-C levels appear to heighten the risk of AMD, whereas triglycerides may provide a protective effect.

Sialic Acid Mimetic Microglial Sialic Acid-Binding Immunoglobulin-like Lectin Agonism: Potential to Restore Retinal Homeostasis and Regain Visual Function in Age-Related Macular Degeneration

Age-related macular degeneration (AMD), a leading cause of visual loss and dysfunction worldwide, is a disease initiated by genetic polymorphisms that impair the negative regulation of complement. Proteomic investigation points to altered glycosylation and loss of Siglec-mediated glyco-immune checkpoint parainflammatory and inflammatory homeostasis as the main determinant for the vision impairing complications of macular degeneration. The effect of altered glycosylation on microglial maintained retinal para-inflammatory homeostasis and eventual recruitment and polarization of peripheral blood monocyte-derived macrophages (PBMDMs) into the retina can explain the phenotypic variability seen in this clinically heterogenous disease. Restoring glyco-immune checkpoint control with a sialic acid mimetic agonist targeting microglial/macrophage Siglecs to regain retinal para-inflammatory and inflammatory homeostasis is a promising therapeutic that could halt the progression of and improve visual function in all stages of macular degeneration.

Genetic variants in the adenosine triphosphate-binding cassette transporter A1 and risk of age-related macular degeneration

Genetic variants in ABCA1 are associated with higher concentrations of high-density lipoprotein (HDL) cholesterol. Higher HDL cholesterol concentrations are observationally and genetically associated with higher risk of age-related macular degeneration (AMD). However, whether amino acid-changing genetic variants in ABCA1 associated with high HDL cholesterol concentrations confer a higher risk of AMD in the general population is currently unknown. We tested this hypothesis. The study included 80,972 individuals (1,370 AMD cases) from the Copenhagen General Population Study (CGPS) and 9,584 individuals (142 AMD cases) from the Copenhagen City Heart Study (CCHS) with 10 to 18 years of follow-up. We created an HDL cholesterol weighted allele score based on amino acid-changing ABCA1 variants with a minor allele frequency above 0.001 and divided it into tertiles. The study included 55% women. Mean age was 58 years. The ABCA1 allele score for the third versus the first tertile was associated with HRs (95% confidence intervals (CIs)) of 1.30 (1.14-1.49) for all-cause AMD, 1.26 (1.06-1.50) for nonneovascular AMD, and 1.31 (1.12-1.53) for neovascular AMD in a multivariable adjusted model. On a continuous scale, higher concentrations of genetically determined HDL cholesterol were associated with higher risk of all-cause AMD, nonneovascular AMD, and neovascular AMD in an age- and sex adjusted model and in a multivariable adjusted model. In conclusion, amino acid-changing genetic variants in ABCA1 associated with higher HDL cholesterol concentrations were also associated with higher risk of AMD, suggesting a role for ABCA1 in AMD pathogenesis.

Minimal effect of sleep on the risk of age-related macular degeneration: a Mendelian randomization study

Aims

Observational studies have shown that sleep pattern is associated with age-related macular degeneration (AMD), but whether sleep pattern is a causal factor for AMD remains unclear. This study aims to use Mendelian randomization (MR) analysis to investigate the potential causal relationship between sleep traits and AMD.

Methods

This is a two-sample MR study. The single-nucleotide polymorphisms associated with AMD and early AMD were selected as the outcome from two different genome-wide association studies (GWAS): the early AMD GWAS with 14,034 cases and 91,214 controls, and AMD GWAS with 3,553 cases and 147,089 controls. The datasets of sleep duration, daytime dozing, and sleeplessness were used as exposure, which comprised nearly 0.46 million participants. Inverse-variance weighted method was used as the main result, and comprehensive sensitivity analyses were conducted to estimate the robustness of identified associations and the impact of potential horizontal pleiotropy.

Results

Through MR analysis, we found that sleep duration was significantly associated with AMD (OR = 0.983, 95% CI = 0.970-0.996, P-value = 0.01). We also found suggestive evidence for the association of genetically predicted sleep duration with early AMD, which showed a consistent direction of effect with a marginal significance (OR = 0.724, 95% CI = 0.503-1.041, P-value = 0.08). Sensitivity analyses further supported the robustness of the causal relationship between sleep duration and AMD. However, we were unable to determine the relationship between daytime dozing or sleeplessness and AMD (including early AMD) (P-value > 0.05).

Conclusion

Sleep duration affects the causal risk for AMD; that is, longer sleep duration reduces the risk of AMD, while shorter sleep duration increases the risk of AMD. Although the influence is minimal, keeping adequate sleep duration is recommended, especially for patients with intermediate or advanced AMD.

Association of Behavioral and Clinical Risk Factors With Cataract: A Two-Sample Mendelian Randomization Study

Purpose

To investigate the association of genetically determined primary open-angle glaucoma (POAG), myopic refractive error (RE), type 2 diabetes (T2D), blood pressure (BP), body mass index (BMI), cigarette smoking, and alcohol consumption with the risk of age-related cataract.

Methods

To assess potential causal effects of clinical or behavioral factors on cataract risk, we conducted two-sample Mendelian randomization analyses. Genetic instruments, based on common genetic variants associated with risk factors at genome-wide significance (P < 5 × 10-8), were derived from published genome-wide association studies (GWAS). For age-related cataract, we used GWAS summary statistics from our previous GWAS conducted in the Genetic Epidemiology Research on Adult Health and Aging (GERA) cohort (28,092 cataract cases and 50,487 controls; all non-Hispanic whites) or in the UK Biobank (31,852 cataract cases and 428,084 controls; all European-descent individuals). We used the inverse-variance weighted (IVW) method as our primary source of Mendelian randomization estimates and conducted common sensitivity analyses.

Results

We found that genetically determined POAG and mean spherical equivalent RE were significantly associated with cataract risk (IVW model: odds ratio [OR] = 1.04; 95% confidence interval [CI], 1.01-1.08; P = 0.018; per diopter more hyperopic: OR = 0.92; 95% CI, 0.89-0.93; P = 6.51 × 10-13, respectively). In contrast, genetically determined T2D, BP, BMI, cigarette smoking, or alcohol consumption were not associated with cataract risk (P > 0.05).

Conclusions

Our results provide evidence that genetic risks for POAG and myopia may be causal risk factors for age-related cataract. These results are consistent with previous observational studies reporting associations of myopia with cataract risk. This information may support population cataract risk stratification and screening strategies.

Inhibiting HIF-1 signaling alleviates HTRA1-induced RPE senescence in retinal degeneration

BACKGROUND

Age-related macular degeneration (AMD), characterized by the degeneration of retinal pigment epithelium (RPE) and photoreceptors, is the leading cause of irreversible vision impairment among the elderly. RPE senescence is an important contributor to AMD and has become a potential target for AMD therapy. HTRA1 is one of the most significant susceptibility genes in AMD, however, the correlation between HTRA1 and RPE senescence hasn't been investigated in the pathogenesis of AMD.

METHODS

Western blotting and immunohistochemistry were used to detect HTRA1 expression in WT and transgenic mice overexpressing human HTRA1 (hHTRA1-Tg mice). RT-qPCR was used to detect the SASP in hHTRA1-Tg mice and ARPE-19 cells infected with HTRA1. TEM, SA-β-gal was used to detect the mitochondria and senescence in RPE. Retinal degeneration of mice was investigated by fundus photography, FFA, SD-OCT and ERG. The RNA-Seq dataset of ARPE-19 cells treated with adv-HTRA1 versus adv-NC were analyzed. Mitochondrial respiration and glycolytic capacity in ARPE-19 cells were measured using OCR and ECAR. Hypoxia of ARPE-19 cells was detected using EF5 Hypoxia Detection Kit. KC7F2 was used to reduce the HIF1α expression both in vitro and in vivo.

RESULTS

In our study, we found that RPE senescence was facilitated in hHTRA1-Tg mice. And hHTRA1-Tg mice became more susceptible to NaIO₃ in the development of oxidative stress-induced retinal degeneration. Similarly, overexpression of HTRA1 in ARPE-19 cells accelerated cellular senescence. Our RNA-seq revealed an overlap between HTRA1-induced differentially expressed genes associated with aging and those involved in mitochondrial function and hypoxia response in ARPE-19 cells. HTRA1 overexpression in ARPE-19 cells impaired mitochondrial function and augmented glycolytic capacity. Importantly, upregulation of HTRA1 remarkably activated HIF-1 signaling, shown as promoting HIF1α expression which mainly located in the nucleus. HIF1α translation inhibitor KC7F2 significantly prevented HTRA1-induced cellular senescence in ARPE-19 cells, as well as improved the visual function in hHTRA1-Tg mice treated with NaIO₃.

CONCLUSIONS

Our study showed elevated HTRA1 contributes to the pathogenesis of AMD by promoting cellular senescence in RPE through damaging mitochondrial function and activating HIF-1 signaling. It also pointed out that inhibition of HIF-1 signaling might serve as a potential therapeutic strategy for AMD. Video Abstract.

Genome-Wide Association Study of Age-Related Macular Degeneration Reveals 2 New Loci Implying Shared Genetic Components with Central Serous Chorioretinopathy

PURPOSE

To investigate the genetic architecture of age-related macular degeneration (AMD) in a Japanese population.

DESIGN

Genome-wide association study (GWAS).

PARTICIPANTS

Three thousand seven hundred seventy-two patients with AMD and 16 770 control participants from the Japanese population were enrolled in the association analyses.

METHODS

We conducted a meta-analysis of 2 independent GWASs that included a total of 2663 patients with AMD and 9471 control participants using the imputation reference panel for genotype imputation specified for the Japanese population (n = 3541). A replication study was performed using an independent set of 1109 patients with AMD and 7299 control participants.

MAIN OUTCOME MEASURES

Associations of genetic variants with AMD.

RESULTS

A meta-analysis of the 2 GWASs identified 6 loci significantly associated with AMD (P < 5.0 × 10^-8). Of these loci, 4 were known to be associated with AMD (CFH, C2/FB, TNFRSF10A, and ARMS2), and 2 were novel (rs4147157 near WBP1L and rs76228488 near GATA5). The newly identified associations were confirmed in a replication study (P < 0.01). After the meta-analysis of all datasets, we observed strong associations in these loci (P = 1.88 × 10^-12 and P = 1.35 × 10^-9 for meta-analysis for rs4147157 and rs76228488, respectively). When we looked up the associations in the reported central serous chorioretinopathy (CSC) GWAS conducted in the Japanese population, both loci were associated significantly with CSC (P = 4.86 × 10^-3 and P = 4.28 × 10^-3 for rs4147157 and rs76228488, respectively). We performed a genetic colocalization analysis for these loci and estimated that the posterior probabilities of shared causal variants between AMD and CSC were 0.39 and 0.60 for WBP1L and GATA5, respectively. Genetic correlation analysis focusing on the epidemiologically suggested clinical risk factors implicated shared polygenic architecture between AMD and smoking cessation (r_g [the measure of genetic correlation] = -0.33; P = 0.01; false discovery rate, 0.099).

CONCLUSIONS

Our findings imply shared genetic components conferring the risk of both AMD and CSC.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Protective effects of Lycium barbarum L. berry extracts against oxidative stress-induced damage of the retina of aging mouse and ARPE-19 cells

In this study, we investigated the preventive effect of Lycium barbarum L. berry extract on age-related macular degeneration (AMD) and the main components responsible for its antioxidant activity. An AMD mouse model was developed by feeding 18-month-old mice with a 1% hydroquinone diet. Meanwhile, the model mice were treated with water extract (LBW) and alcohol extract (LBE) of L. barbarum berries respectively for 3 months. It was found that the retinal structural abnormalities were improved and the oxidation stress and inflammatory imbalance were both attenuated in model mice treated with the extracts of L. barbarum berries. According to the metabolomics analysis of the serum of model mice, LBW regulated the metabolism of unsaturated fatty acids and sphingolipids, while LBE extracts tended to regulate taurine metabolism. On sodium iodate induced oxidative injury of ARPE-19 cells, water extracts of L. barbarum berries eluted with 95% ethanol (LBW-95E) on AB-8 macroporous resin significantly improved the cell viability and attenuated oxidative stress by increasing the superoxide dismutase (SOD) activity and glutathione (GSH) content, decreasing the reactive oxygen species (ROS) content, promoting the entry of nuclear factor erythroid-derived 2-like 2 (Nrf2) into the nucleus and up-regulating the heme oxygenase-1 (HO-1) expression. Scopoletin, N-trans-feruloyltyramine and perlolyrine were identified as the main components of LBW-95E. These results demonstrated that L. barbarum berry extracts protected the retina of aging AMD model mice from degeneration and LBW-95E was the vital antioxidant activity fraction of LBW. These findings suggest that L. barbarum berry extracts might be an excellent natural source for the development of retinal protection-related drugs or dietary supplements.

[Exogenously induced retinopathies]

Exogenously induced retinopathies can be caused by consumation of stimulating substances, systemic or ocular medications, vaccinations, light or irradiation. Some of the effects are transient, whereas other effects induce irreversible toxic reactions. Retinal damage may develop either acutely with obvious relation to the damaging cause, but often may take a long duration of repeated use of a substance or medication. External stimulants (e.g. nicotine, alcohol, poppers, methanol) are the most frequent cause of exogenously induced retinal damage. Side effects from systemic drugs (e.g. hydroxychloroquine, ethambutol, MEK-, ERK-, FLT3-, checkpoint inhibitors, didanosin, pentosanpolysulfat sodium) or intravitreally applied drugs (e.g. antibiotics, VEGF-inhibitors) are less frequent. Ocular side effects associated with vaccinations are rare. Ambient light sources induce no damaging effects on the retina. Incorrect use of technical or medical light sources (e.g. laser pointers) without adherence to safety recommendations or unshielded observation of the sun might induce permanent retinal damage. Local or external irradiation might induce retinal vascular damage resulting in radiation retinopathy.

Association Between Oral Metformin Use and the Development of Age-Related Macular Degeneration in Diabetic Patients: A Systematic Review and Meta-Analysis

Purpose

Metformin is a biguanide derivative that is commonly used for the treatment of diabetes mellitus (DM). It demonstrates antioxidative, anti-inflammatory, and antiangiogenic activity within the ocular tissue and thus may be implicated in the treatment of age-related macular degeneration (AMD). However, epidemiological studies have shown conflicting results.

Methods

The Ovid MEDLINE/Embase, Cochrane Library, and Web of Science databases were systematically searched from inception through August 3, 2022. Studies reporting the association between metformin use and odds of AMD were enrolled. Adjusted odds ratios (ORs) of AMD were extracted and pooled with random-effects model meta-analysis. Subgroup analyses based on AMD subtypes, ethnicity, study design, sex, and confirmation of AMD diagnosis were conducted.

Results

A total of 9 observational studies with 1,446,284 participants were included in the analysis. The meta-analysis showed that metformin use was associated with a significant reduction in the odds of AMD (pooled ORs = 0.81, 95% confidence interval [CI] = 0.70-0.93). Subgroup analyses revealed that metformin use was not significantly associated with dry or wet AMD. Black (pooled ORs = 0.61, 95% CI = 0.58-0.64) and Hispanic populations (pooled ORs = 0.85, 95% CI = 0.81-0.89) demonstrated significantly lower odds of AMD.

Conclusions

This systematic review and meta-analysis found that patients with DM with metformin usage were at lower odds of developing AMD. Future prospective clinical trials are needed to confirm this association.

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.

Exogen bedingte Retinopathien

Exogen bedingte Retinopathien werden am häufigsten durch externe Stimulanzien, seltener durch unerwünschte Arzneimittelwirkungen systemisch oder intravitreal eingesetzter Medikamente und noch seltener durch Impfungen oder die Einwirkung von Lichtstrahlung verursacht. Die Kenntnis exogener Ursachen und ihre mögliche Symptomatik ist zur Prophylaxe oder zur Früherkennung schädigender Wirkungen und zur adäquaten Beratung der Patienten wichtig.

Inside out: Relations between the microbiome, nutrition, and eye health

Age-related macular degeneration (AMD) is a complex disease with increasing numbers of individuals being afflicted and treatment modalities limited. There are strong interactions between diet, age, the metabolome, and gut microbiota, and all of these have roles in the pathogenesis of AMD. Communication axes exist between the gut microbiota and the eye, therefore, knowing how the microbiota influences the host metabolism during aging could guide a better understanding of AMD pathogenesis. While considerable experimental evidence exists for a diet-gut-eye axis from murine models of human ocular diseases, human diet-microbiome-metabolome studies are needed to elucidate changes in the gut microbiome at the taxonomic and functional levels that are functionally related to ocular pathology. Such studies will reveal new ways to diminish risk for progression of- or incidence of- AMD. Current data suggest that consuming diets rich in dark fish, fruits, vegetables, and low in glycemic index are most retina-healthful during aging.

Targeting the Complement Cascade for Treatment of Dry Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the leading cause of irreversible vision loss in the elderly population. AMD is characterized in its late form by neovascularization (wet type) or geographic atrophy of the retinal pigment epithelium cell layer (dry type). Regarding the latter type, there is growing evidence supporting an association between the pathophysiology of dry AMD and key proteins in the complement cascade. The complement cascade works as a central part of the innate immune system by defending against foreign pathogens and modified self-tissues. Through three distinct pathways, a series of plasma and membrane-associated serum proteins are activated upon identification of a foreign entity. Several of these proteins have been implicated in the development and progression of dry AMD. Potential therapeutic targets include C1q, C3, C5, complement factors (B, D, H, I), membrane attack complex, and properdin. In this review, we provide an understanding of the role of the complement system in dry AMD and discuss the emerging therapies in early phase clinical trials. The tentative hope is that these drugs may offer the potential to intervene at earlier stages in dry AMD pathogenesis, thereby preventing progression to late disease.

Appraising the causal role of smoking in multiple diseases: A systematic review and meta-analysis of Mendelian randomization studies

BACKGROUND

The causal association between cigarette smoking and several diseases remains equivocal. The purpose of this study was to appraise the causal role of smoking in a wide range of diseases by summarizing the evidence from Mendelian randomization (MR) studies.

METHODS

MR studies on genetic liability to smoking initiation or lifetime smoking (composite of smoking initiation, heaviness, duration, and cessation) in relation to circulatory system, digestive system, nervous system, musculoskeletal system, endocrine, metabolic, and eye diseases, and neoplasms published until February 15, 2022, were identified in PubMed. De novo MR analyses were performed using summary statistics data from genome-wide association studies. Meta-analysis was applied to combine study-specific estimates.

FINDINGS

Meta-analyses of findings of 29 published MR studies and 123 de novo MR analyses of 57 distinct primary outcomes showed that genetic liability to smoking (smoking initiation or lifetime smoking) was associated with increased risk of 13 circulatory system diseases, several digestive system diseases (including diverticular, gallstone, gastroesophageal reflux, and Crohn's disease, acute pancreatitis, and periodontitis), epilepsy, certain musculoskeletal system diseases (including fracture, osteoarthritis, and rheumatoid arthritis), endocrine (polycystic ovary syndrome), metabolic (type 2 diabetes) and eye diseases (including age-related macular degeneration and senile cataract) as well as cancers of the lung, head and neck, esophagus, pancreas, bladder, kidney, cervix, and ovaries, and myeloid leukemia. Smoking liability was associated with decreased risk of Parkinson's disease and prostate cancer.

INTERPRETATION

This study found robust evidence that cigarette smoking causes a wide range of diseases.

FUNDING

This work was supported by research grants from the Swedish Cancer Society (Cancerfonden), the Swedish Heart Lung Foundation (Hjärt-Lungfonden, 20210351), the Swedish Research Council for Health, Working Life and Welfare (Forte, 2018-00123), and the Swedish Research Council (Vetenskapsrådet, 2019-00977). Stephen Burgess is supported by Sir Henry Dale Fellowship jointly funded by the Wellcome Trust and the Royal Society (204623/Z/16/Z) and the National Institute for Health Research Cambridge Biomedical Research Centre (BRC-1215-20014). The views expressed are those of the authors and not necessarily those of the National Institute for Health Research or the Department of Health and Social Care.

Genetic Association Analysis of Anti-VEGF Treatment Response in Neovascular Age-Related Macular Degeneration

Anti-VEGF treatment for neovascular age-related macular degeneration (nAMD) has been FDA-approved in 2004, and since then has helped tens of thousands of patients worldwide to preserve vision. Still, treatment responses vary widely, emphasizing the need for genetic biomarkers to robustly separate responders from non-responders. Here, we report the findings of an observational study compromising 179 treatment-naïve nAMD patients and their reaction to treatment after three monthly doses of anti-VEGF antibodies. We show that established criteria of treatment response such as visual acuity and central retinal thickness successfully divides our cohort into 128 responders and 51 non-responders. Nevertheless, retinal thickness around the fovea revealed significant reaction to treatment even in the formally categorized non-responders. To elucidate genetic effects underlying our criteria, we conducted an undirected genome-wide association study followed by a directed replication study of 30 previously reported genetic variants. Remarkably, both approaches failed to result in significant findings, suggesting study-specific effects were confounding the present and previous discovery studies. Of note, all studies so far are greatly underpowered, hampering interpretation of genetic findings. In consequence, we highlight the need for an extensive phenotyping study with sample sizes exceeding at least 15,000 to reliably assess anti-VEGF treatment responses in nAMD.

Causal Associations of Obesity With Achilles Tendinopathy: A Two-Sample Mendelian Randomization Study

BACKGROUND

Achilles tendinopathy (AT) is associated with severe pain and is the cause of dysfunction and disability that are associated with significant reduction in social and economic benefits. Several potential risk factors have been proposed to be responsible for AT development; however, the results of observational epidemiological studies remain controversial, presumably because the designs of these studies are subject to residual confounding and reverse causality. Mendelian randomization (MR) can infer the causality between exposure and disease outcomes using genetic variants as instrumental variables, and identification of the causal risk factors for AT is beneficial for early intervention. Thus, we employed the MR strategy to evaluate the causal associations between previously reported risk factors (anthropometric parameters, lifestyle factors, blood biomarkers, and systemic diseases) and the risk of AT.

METHODS

Univariable MR was performed to screen for potential causal associations between the putative risk factors and AT. Bidirectional MR was used to infer reverse causality. Multivariable MR was conducted to investigate the body mass index (BMI)-independent causal effect of other obesity-related traits, such as the waist-hip ratio, on AT.

RESULTS

Univariable MR analyses with the inverse-variance weighted method indicated that the genetically predicted BMI was significantly associated with the risk of AT (P=2.0×10^-3), and the odds ratios (95% confidence intervals) is 1.44 (1.14-1.81) per 1-SD increase in BMI. For the other tested risk factors, no causality with AT was identified using any of the MR methods. Bidirectional MR suggested that AT was not causally associated with BMI, and multivariable MR indicated that other anthropometric parameters included in this study were not likely to causally associate with the risk of AT after adjusting for BMI.

CONCLUSIONS

The causal association between BMI and AT risk suggests that weight control is a promising strategy for preventing AT and alleviating the corresponding disease burden.