Nutrient Supplementation for Age-related Macular Degeneration, Cataract, and Dry Eye

Baicalein improves Na2SeO3 induced cataract by enhancing the antioxidant capacity of juvenile Sprague Dawley Rat

ETHNOPHARMACOLOGICAL RELEVANCE

Baicalein (BAI) is the crucial flavonoid component in Scutellaria baicalensis Georgi, possessing biological functions such as anti-oxidant, anti-apoptotic, and anti-inflammatory. However, there is limited intensive pharmacological and mechanistic research on the therapeutic effects of BAI for cataract treatment.

AIM OF THE STUDY

This study aimed to investigate the effects and mechanisms of BAI on Na2SeO3-induced cataract in juvenile rats.

MATERIALS AND METHODS

The cataract model was established by a single subcutaneous injection of 3.46 mg/kg Na2SeO3 on the back of 10-day-old rats. The BAI (25 mg/kg, 50 mg/kg, 100 mg/kg) was administered to the 8-day-old rats and continued until they reached 30 days of age, and the opacity of the lens was observed using a slit lamp microscope every 3 days. Pathological changes in the lens were observed using hematoxylin-eosin (HE) staining to investigate the effects of BAI on Na2SeO3-induced cataract in rats. The levels of antioxidant substances in rat serum and the lens, as well as the levels of soluble and insoluble proteins in rat lens, were measured by the reagent kit. Furthermore, the mechanism of BAI on Na2SeO3-induced cataract rats was analyzed by network pharmacology, molecular docking, and Western blot.

RESULTS

BAI significantly increased the content of soluble proteins in the lens, mitigated the dense opacity of rat lens and reduced the damage to lens epithelial cells, reduced the levels of malondialdehyde (MDA) in rat serum and lens, increased the levels of total superoxide dismutase (T-SOD) and Glutathione peroxidase (GSH-PX). The improvement effects of BAI on Na2SeO3-induced cataract may related to the mitogen-activated protein kinase (MAPK) and the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathways.

CONCLUSION

In conclusion, this study demonstrated that BAI could mitigate the dense opacity of rat lens in Na2SeO3-induced cataract rats, which may be achieved through the MAPK signaling pathway and the PI3K/AKT signaling pathway.

Ergonomic lighting considerations for the home office workplace

BACKGROUND: The COVID-19 pandemic has resulted in a large increase in the use of the home office environment. Compared to traditional commercial offices, home offices typically have more variable lighting conditions that can affect the worker’s performance and well-being. OBJECTIVE: To review and discuss various lighting sources and their ergonomic impacts on the population of office employees now working from home. Specifically addressing the impacts of electronic light from screens, daylight, and task lighting’s impact on health and well-being in the frame of the COVID-19 pandemic. METHODS: Over 75 ergonomic and lighting literature publications covering various work environments were reviewed, with a focus on the health effects of screen light, daylight, and task light. RESULTS: Resulting from the literature review, design recommendations regarding the safety and health of home office lighting conditions are discussed. CONCLUSION: As COVID-19 continues to encourage remote working, individuals will be exposed to daylight and screen light in different ways compared to a traditional office environment. The impact of these different lighting conditions should be further studied to understand best design and well-being practices.

Environmental and Nutritional Determinants of Macular Pigment in a Mexican Population

Purpose

The carotenoids lutein (L), zeaxanthin (Z), and meso-zeaxanthin deposit at the macula as macular pigment (MP) and provide visual benefits and protection against macular diseases. The present study investigated MP, its nutritional and environmental determinants, and its constituent carotenoids in serum from a Mexican sample, in healthy participants and with metabolic diseases. Additionally, we compared these variables with an Irish sample.

Methods

MP was measured in 215 subjects from a rural community in Mexico with dual-wavelength autofluorescence imaging reported as MP optical volume (MPOV). Dietary intake and serum concentrations of L and Z were evaluated.

Results

The mean MPOV was 8429 (95% confidence interval, 8060-8797); range. 1171-15,976. The mean L and Z serum concentrations were 0.25 ± 0.15 µmol/L and 0.09 ± 0.04 µmol/L, respectively. The MPOV was positively correlated with L and Z serum concentrations (r = 0.347; P < 0.001 and r = 0.311; P < 0.001, respectively), but not with L + Z dietary estimates. Subjects with daily sunlight exposure of more than 50% were found to have significantly higher MPOV than those with less than 50% (P = 0.005). MPOV and serum concentrations of L and Z were significantly higher in the Mexican sample compared with the Irish sample, but this difference was not reflected in dietary analysis.

Conclusions

These new data from a Mexican sample provide evidence of the multifactorial interactions and environmental determinants of MP such as sunlight exposure and dietary patterns. These findings will be essential for future studies in Mexico for eye health, visual function, and ocular pathology.

Deep Learning Applied to Automated Segmentation of Geographic Atrophy in Fundus Autofluorescence Images

Purpose

This study describes the development of a deep learning algorithm based on the U-Net architecture for automated segmentation of geographic atrophy (GA) lesions in fundus autofluorescence (FAF) images.

Methods

Image preprocessing and normalization by modified adaptive histogram equalization were used for image standardization to improve effectiveness of deep learning. A U-Net-based deep learning algorithm was developed and trained and tested by fivefold cross-validation using FAF images from clinical datasets. The following metrics were used for evaluating the performance for lesion segmentation in GA: dice similarity coefficient (DSC), DSC loss, sensitivity, specificity, mean absolute error (MAE), accuracy, recall, and precision.

Results

In total, 702 FAF images from 51 patients were analyzed. After fivefold cross-validation for lesion segmentation, the average training and validation scores were found for the most important metric, DSC (0.9874 and 0.9779), for accuracy (0.9912 and 0.9815), for sensitivity (0.9955 and 0.9928), and for specificity (0.8686 and 0.7261). Scores for testing were all similar to the validation scores. The algorithm segmented GA lesions six times more quickly than human performance.

Conclusions

The deep learning algorithm can be implemented using clinical data with a very high level of performance for lesion segmentation. Automation of diagnostics for GA assessment has the potential to provide savings with respect to patient visit duration, operational cost and measurement reliability in routine GA assessments.

Translational Relevance

A deep learning algorithm based on the U-Net architecture and image preprocessing appears to be suitable for automated segmentation of GA lesions on clinical data, producing fast and accurate results.

Artificial Intelligence Algorithms for Analysis of Geographic Atrophy: A Review and Evaluation

Purpose

The purpose of this study was to summarize and evaluate artificial intelligence (AI) algorithms used in geographic atrophy (GA) diagnostic processes (e.g. isolating lesions or disease progression).

Methods

The search strategy and selection of publications were both conducted in accordance with the Preferred of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. PubMed and Web of Science were used to extract literary data. The algorithms were summarized by objective, performance, and scope of coverage of GA diagnosis (e.g. lesion automation and GA progression).

Results

Twenty-seven studies were identified for this review. A total of 18 publications focused on lesion segmentation only, 2 were designed to detect and classify GA, 2 were designed to predict future overall GA progression, 3 focused on prediction of future spatial GA progression, and 2 focused on prediction of visual function in GA. GA-related algorithms reported sensitivities from 0.47 to 0.98, specificities from 0.73 to 0.99, accuracies from 0.42 to 0.995, and Dice coefficients from 0.66 to 0.89.

Conclusions

Current GA-AI publications have a predominant focus on lesion segmentation and a minor focus on classification and progression analysis. AI could be applied to other facets of GA diagnoses, such as understanding the role of hyperfluorescent areas in GA. Using AI for GA has several advantages, including improved diagnostic accuracy and faster processing speeds.

Translational Relevance

AI can be used to quantify GA lesions and therefore allows one to impute visual function and quality-of-life. However, there is a need for the development of reliable and objective models and software to predict the rate of GA progression and to quantify improvements due to interventions.

The Impact of Formulation on Lutein, Zeaxanthin, and meso-Zeaxanthin Bioavailability: A Randomised Double-Blind Placebo-Controlled Study

Lutein (L), zeaxanthin (Z), and meso-zeaxanthin (MZ) have been the focus of research and commercial interest for their applications in human health. Research into formulations to enhance their bioavailability is merited. This 6 month randomised placebo-controlled trial involving 81 healthy volunteers compared the bioavailability of different formulations of free L, Z, and MZ in sunflower or omega-3 oil versus L, Z, and MZ diacetates (Ld, Zd, and MZd) in a micromicellar formulation. Fasting serum carotenoids, macular pigment, and skin carotenoid score were analysed at baseline and 6 months. Serum L, Z, and MZ concentrations increased in all active interventions compared to placebo (p < 0.001 to p = 0.008). The diacetate micromicelle formulation exhibited a significantly higher mean response in serum concentrations of Z and MZ compared to the other active interventions (p = 0.002 to 0.019). A micromicellar formulation with solubilised Z and MZ diacetates is a promising technology advancement that enhances the bioavailability of these carotenoids when compared to traditional carotenoid formulations (ISRCTN clinical trial registration number: ISRCTN18206561).

Nutritional Strategies to Prevent Lens Cataract: Current Status and Future Strategies

Oxidative stress and the subsequent oxidative damage to lens proteins is a known causative factor in the initiation and progression of cataract formation, the leading cause of blindness in the world today. Due to the role of oxidative damage in the etiology of cataract, antioxidants have been prompted as therapeutic options to delay and/or prevent disease progression. However, many exogenous antioxidant interventions have to date produced mixed results as anti-cataract therapies. The aim of this review is to critically evaluate the efficacy of a sample of dietary and topical antioxidant interventions in the light of our current understanding of lens structure and function. Situated in the eye behind the blood-eye barrier, the lens receives it nutrients and antioxidants from the aqueous and vitreous humors. Furthermore, being a relatively large avascular tissue the lens cannot rely of passive diffusion alone to deliver nutrients and antioxidants to the distinctly different metabolic regions of the lens. We instead propose that the lens utilizes a unique internal microcirculation system to actively deliver antioxidants to these different regions, and that selecting antioxidants that can utilize this system is the key to developing novel nutritional therapies to delay the onset and progression of lens cataract.

Lanosterol and 25-hydroxycholesterol dissociate crystallin aggregates isolated from cataractous human lens via different mechanisms

Cataract, a crystallin aggregation disease, is the leading cause of human blindness worldwide. Surgery is the only established treatment of cataracts and no anti-cataract drugs are available thus far. Recently lanosterol and 25-hydroxycholesterol have been reported to redissolve crystallin aggregates and partially restore lens transparency in animals. However, the efficacies of these two compounds have not been quantitatively studied ex vivo using patient tissues. In this research, we developed a quantitative assay applicable to efficacy validations and mechanistic studies by a protocol to isolate protein aggregates from the surgically removed cataractous human lens. Our results showed that both compounds were effective for human cataractous samples with EC50 values at ten micromolar level. The efficacies of both compounds strongly depended on cataract severity. Lanosterol and 25-hydroxycholesterol were two mechanistically different lead compounds of anti-cataract drug design.

Changing vision: a review of pharmacogenetic studies for treatment response in age-related macular degeneration patients

Nonresponsiveness to age-related macular degeneration (AMD) treatments has become a growing concern in ophthalmology. Disparity among publications that have assessed pharmacogenetic (PGx) connections between AMD disease genes and treatments has delayed the implementation of PGx testing in AMD. We assessed all AMD PGx publications to identify the degree of agreement for publications within similar ethnic cohorts and worldwide, and the causes for differences in study outcomes. There are no accepted genotype–phenotype correlations, either within similar ethnic cohorts or worldwide. The diversity of measured outcomes, treatment protocols and statistical methods used may be causing this discrepancy. A universally accepted treatment protocol and the creation of agreed response group classification may bridge the gap between AMD PGx publications.

Therapeutic potential of omega-3 fatty acid-derived epoxyeicosanoids in cardiovascular and inflammatory diseases

Numerous benefits have been attributed to dietary long-chain omega-3 polyunsaturated fatty acids (n-3 LC-PUFAs), including protection against cardiac arrhythmia, triglyceride-lowering, amelioration of inflammatory, and neurodegenerative disorders. This review covers recent findings indicating that a variety of these beneficial effects are mediated by "omega-3 epoxyeicosanoids", a class of novel n-3 LC-PUFA-derived lipid mediators, which are generated via the cytochrome P450 (CYP) epoxygenase pathway. CYP enzymes, previously identified as arachidonic acid (20:4n-6; AA) epoxygenases, accept eicosapentaenoic acid (20:5n-3; EPA) and docosahexaenoic acid (22:6n-3; DHA), the major fish oil n-3 LC-PUFAs, as efficient alternative substrates. In humans and rodents, dietary EPA/DHA supplementation causes a profound shift of the endogenous CYP-eicosanoid profile from AA- to EPA- and DHA-derived metabolites, increasing, in particular, the plasma and tissue levels of 17,18-epoxyeicosatetraenoic acid (17,18-EEQ) and 19,20-epoxydocosapentaenoic acid (19,20-EDP). Based on preclinical studies, these omega-3 epoxyeicosanoids display cardioprotective, vasodilatory, anti-inflammatory, and anti-allergic properties that contribute to the beneficial effects of n-3 LC-PUFAs in diverse disease conditions ranging from cardiac disease, bronchial disorders, and intraocular neovascularization, to allergic intestinal inflammation and inflammatory pain. Increasing evidence also suggests that background nutrition as well as genetic and disease state-related factors could limit the response to EPA/DHA-supplementation by reducing the formation and/or enhancing the degradation of omega-3 epoxyeicosanoids. Recently, metabolically robust synthetic analogs mimicking the biological activities of 17,18-EEQ have been developed. These drug candidates may overcome limitations of dietary EPA/DHA supplementation and provide novel options for the treatment of cardiovascular and inflammatory diseases.

Lutein and Zeaxanthin-Food Sources, Bioavailability and Dietary Variety in Age-Related Macular Degeneration Protection

Lutein and zeaxanthin (L/Z) are the predominant carotenoids which accumulate in the retina of the eye. The impact of L/Z intake on the risk and progression of age-related macular degeneration (AMD), a leading cause of blindness in the developed world, has been investigated in cohort studies and clinical trials. The aims of this review were to critically examine the literature and evaluate the current evidence relating to L/Z intake and AMD, and describe important food sources and factors that increase the bioavailability of L/Z, to inform dietary models. Cohort studies generally assessed L/Z from dietary sources, while clinical trials focused on providing L/Z as a supplement. Important considerations to take into account in relation to dietary L/Z include: nutrient-rich sources of L/Z, cooking methods, diet variety and the use of healthy fats. Dietary models include examples of how suggested effective levels of L/Z can be achieved through diet alone, with values of 5 mg and 10 mg per day described. These diet models depict a variety of food sources, not only from dark green leafy vegetables, but also include pistachio nuts and other highly bioavailable sources of L/Z such as eggs. This review and the diet models outlined provide information about the importance of diet variety among people at high risk of AMD or with early signs and symptoms of AMD.

Cognitive Function and Its Relationship with Macular Pigment Optical Density and Serum Concentrations of its Constituent Carotenoids

Background: Macular pigment (MP) levels correlate with brain concentrations of lutein (L) and zeaxanthin (Z), and have also been shown to correlate with cognitive performance in the young and elderly.

Objective: To investigate the relationship between MP, serum concentrations of L and Z, and cognitive function in subjects free of retinal disease with low MP (Group 1, n = 105) and in subjects with AMD (Group 2, n = 121).

Methods: MP was measured using customized heterochromatic flicker photometry and dual-wavelength autofluorescence; cognitive function was assessed using a battery of validated cognition tests; serum L and Z concentrations were determined by HPLC.

Results: Significant correlations were evident between MP and various measures of cognitive function in both groups (r = –0.273 to 0.261, p≤0.05, for all). Both serum L and Z concentrations correlated significantly (r = 0.187, p≤0.05 and r = 0.197, p≤0.05, respectively) with semantic (animal) fluency cognitive scores in Group 2 (the AMD study group), while serum L concentrations also correlated significantly with Verbal Recognition Memory learning slope scores in the AMD study group (r = 0.200, p = 0.031). Most of the correlations with MP, but not serum L or Z, remained significant after controlling for age, gender, diet, and education level.

Conclusion: MP offers potential as a non-invasive clinical biomarker of cognitive health, and appears more successful in this role than serum concentrations of L or Z.

ZEAXANTHIN EPOXIDASE Activity Potentiates Carotenoid Degradation in Maturing Seed

Elucidation of the carotenoid biosynthetic pathway has enabled altering the composition and content of carotenoids in various plants, but to achieve desired nutritional impacts, the genetic components regulating carotenoid homeostasis in seed, the plant organ consumed in greatest abundance, must be elucidated. We used a combination of linkage mapping, genome-wide association studies (GWAS), and pathway-level analysis to identify nine loci that impact the natural variation of seed carotenoids in Arabidopsis (Arabidopsis thaliana). ZEAXANTHIN EPOXIDASE (ZEP) was the major contributor to carotenoid composition, with mutants lacking ZEP activity showing a remarkable 6-fold increase in total seed carotenoids relative to the wild type. Natural variation in ZEP gene expression during seed development was identified as the underlying mechanism for fine-tuning carotenoid composition, stability, and ultimately content in Arabidopsis seed. We previously showed that two CAROTENOID CLEAVAGE DIOXYGENASE enzymes, CCD1 and CCD4, are the primary mediators of seed carotenoid degradation, and here we demonstrate that ZEP acts as an upstream control point of carotenoid homeostasis, with ZEP-mediated epoxidation targeting carotenoids for degradation by CCD enzymes. Finally, four of the nine loci/enzymatic activities identified as underlying natural variation in Arabidopsis seed carotenoids also were identified in a recent GWAS of maize (Zea mays) kernel carotenoid variation. This first comparison of the natural variation in seed carotenoids in monocots and dicots suggests a surprising overlap in the genetic architecture of these traits between the two lineages and provides a list of likely candidates to target for selecting seed carotenoid variation in other species.

Targeting MAPK Signaling in Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a major cause of irreversible blindness affecting elderly people in the world. AMD is a complex multifactorial disease associated with demographic, genetics, and environmental risk factors. It is well established that oxidative stress, inflammation, and apoptosis play critical roles in the pathogenesis of AMD. The mitogen-activated protein kinase (MAPK) signaling pathways are activated by diverse extracellular stimuli, including growth factors, mitogens, hormones, cytokines, and different cellular stressors such as oxidative stress. They regulate cell proliferation, differentiation, survival, and apoptosis. This review addresses the novel findings from human and animal studies on the relationship of MAPK signaling with AMD. The use of specific MAPK inhibitors may represent a potential therapeutic target for the treatment of this debilitating eye disease.

AMD and the alternative complement pathway: genetics and functional implications

Age-related macular degeneration (AMD) is an ocular neurodegenerative disorder and is the leading cause of legal blindness in Western societies, with a prevalence of up to 8 % over the age of 60, which continues to increase with age. AMD is characterized by the progressive breakdown of the macula (the central region of the retina), resulting in the loss of central vision including visual acuity. While its molecular etiology remains unclear, advances in genetics and genomics have illuminated the genetic architecture of the disease and have generated attractive pathomechanistic hypotheses. Here, we review the genetic architecture of AMD, considering the contribution of both common and rare alleles to susceptibility, and we explore the possible mechanistic links between photoreceptor degeneration and the alternative complement pathway, a cascade that has emerged as the most potent genetic driver of this disorder.

Gene expression changes in the retina following subretinal injection of human neural progenitor cells into a rodent model for retinal degeneration

PURPOSE

Retinal degenerative diseases (RDDs) affect millions of people and are the leading cause of vision loss. Although treatment options for RDDs are limited, stem and progenitor cell-based therapies have great potential to halt or slow the progression of vision loss. Our previous studies have shown that a single subretinal injection of human forebrain derived neural progenitor cells (hNPCs) into the Royal College of Surgeons (RCS) retinal degenerate rat offers long-term preservation of photoreceptors and visual function. Furthermore, neural progenitor cells are currently in clinical trials for treating age-related macular degeneration; however, the molecular mechanisms of stem cell-based therapies are largely unknown. This is the first study to analyze gene expression changes in the retina of RCS rats following subretinal injection of hNPCs using high-throughput sequencing.

METHODS

RNA-seq data of retinas from RCS rats injected with hNPCs (RCS(hNPCs)) were compared to sham surgery in RCS (RCS(sham)) and wild-type Long Evans (LE(sham)) rats. Differential gene expression patterns were determined with in silico analysis and confirmed with qRT-PCR. Function, biologic, cellular component, and pathway analyses were performed on differentially expressed genes and investigated with immunofluorescent staining experiments.

RESULTS

Analysis of the gene expression data sets identified 1,215 genes that were differentially expressed between RCS(sham) and LE(sham) samples. Additionally, 283 genes were differentially expressed between the RCS(hNPCs) and RCS(sham) samples. Comparison of these two gene sets identified 68 genes with inverse expression (termed rescue genes), including Pdc, Rp1, and Cdc42ep5. Functional, biologic, and cellular component analyses indicate that the immune response is enhanced in RCS(sham). Pathway analysis of the differential expression gene sets identified three affected pathways in RCS(hNPCs), which all play roles in phagocytosis signaling. Immunofluorescent staining detected the increased presence of macrophages and microglia in RCS(sham) retinas, which decreased in RCS(hNPCs) retinas similar to the patterns detected in LE(sham).

CONCLUSIONS

The results from this study provide evidence of the gene expression changes that occur following treatment with hNPCs in the degenerating retina. This information can be used in future studies to potentially enhance or predict responses to hNPC and other stem cell therapies for retinal degenerative diseases.