Retinal Degeneration and Alzheimer's Disease: An Evolving Link

Extracellular vesicles as therapeutic modulators of neuroinflammation in Alzheimer's disease: a focus on signaling mechanisms

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by the accumulation of amyloid-beta (Aβ) plaques and tau tangles, which contribute significantly to neuroinflammation, a central driver of disease pathogenesis. The activation of microglia and astrocytes, coupled with the complex interactions between Aβ and tau pathologies and the innate immune response, leads to a cascade of inflammatory events. This process triggers the release of pro-inflammatory cytokines and chemokines, exacerbating neuronal damage and fostering a cycle of chronic inflammation that accelerates neurodegeneration. Key signaling pathways, such as nuclear factor-kappa B (NF-κB), Janus kinase/signal transducer and activator of transcription (JAK/STAT), mitogen-activated protein kinase (MAPK), and phosphoinositide 3-kinase/protein kinase B (PI3K/Akt), are involved in regulating the production of these inflammatory mediators, offering potential therapeutic targets for AD. Recently, extracellular vesicles (EVs) have emerged as a promising tool for AD therapy, due to their ability to cross the blood-brain barrier (BBB) and deliver therapeutic agents. Despite challenges in standardizing EV-based therapies and ensuring their safety, EVs offer a novel approach to modulating neuroinflammation and promoting neuroregeneration. This review aims to highlight the intricate relationship between neuroinflammation, signaling pathways, and the emerging role of EV-based therapeutics in advancing AD treatment strategies.

Exploring Retinal Neurodegeneration in Alzheimer's Disease: A Molecular and Cellular Perspective

Increasing evidence of ocular impairments in Alzheimer's disease (AD) has drawn the attention of researchers worldwide towards retinal neurodegeneration in AD. The AD-associated changes observed in the retina include visual discrepancies, pupil size modulations, retinal nerve layer changes, retinal blood flow alterations and histopathological changes. The brain cells that act as pathological triggers for the progression of retinal neurodegeneration associated with AD are microglia, astrocytes and neurons. Various molecular pathways lead to structural and functional abnormalities in the retina, significantly affecting the brain including Aβ accumulation, apoptosis, inflammation and oxidative stress. Therapeutic agents under development that ameliorate disease conditions by targeting retinal anomalies include mesenchymal stem cell-conditioned media, BDNF, glatiramer acetate, salvianolic acid B, Lycium barbarum extract and exosomes. Investigating real-time alterations in the retina in AD may not only affect diagnostic approaches but also help to clarify neuropathological pathways and offer helpful measurements for assessing novel therapeutic approaches for AD.

Earlier diagnosis of Alzheimer's disease by dynamic light scattering spectroscopy

Dynamic light scattering (DLS) spectroscopy measures changes in the Brownian movement of particles at the molecular level. Since the retina of the eye is a neural tissue and an outgrowth of the brain, a clinical instrument was developed capable of making DLS measurements from the retina in patients with mild cognitive impairment undergoing positron emission tomography nuclide imaging for the presence of cerebral amyloid.

Medical Benefits and Polymer Applications of Grapes

Grapes are a fruit with origins dating back to ancient times. Their first recorded use, as mentioned in the Bible, was in winemaking. The abundance of bioactive compounds in grapes makes them highly valuable. So far, many varieties of cultivated grapes have been developed for table grapes, wine grapes, and raisin production. In addition to these uses, since grapes contain a variety of nutrients, including resveratrol, flavonoids (such as flavonols, anthocyanins, and catechins), melatonin, vitamins, acids, tannins, and other antioxidants, grape extracts have been widely studied for medical applications. This paper reviews the medical effects of these compounds on cancer, cardiovascular disease, brain and neurological disorders, eye diseases, skin disorders, kidney health, diabetes, and gastric diseases, along with the medical applications of grapes in drug delivery, wound dressing, and tissue engineering. In addition, the limitations of the grapes-derived polymers and future research perspectives are discussed. These benefits highlight that the value of grapes extends far beyond their traditional use in wine and raisin production.

Increasing residential greenness attenuates the hazard of ultraviolet radiation on age-related macular degeneration in the elderly: A nationwide study in China

BACKGROUND

Exposure to ultraviolet (UV) radiation may increase the risk of age-related macular degeneration (AMD), the leading cause of blindness in the elderly. However, prevention measures of UV radiation at population-level remain lacking, exacerbating the health inequity. Given the protective effect of residential greenness on human health, we aim to identify the impact of greenness on the UV-AMD association.

METHODS

We used data from 19,832 participants in a national cohort in China conducted from 2018 to 2023. Satellite-based models and ophthalmological fundus images were used to evaluate the exposures (UV radiation and residential greenness) and outcome (incident AMD), respectively. The effects of UV radiation, residential greenness, and their interplay on incident AMD were furtherly estimated through multiple Cox proportional hazard models.

RESULTS

A total of 3800 incident AMD cases were diagnosed during follow-up. Higher UV radiation elevated the hazard of incident AMD, while excessive greenness showed a significant protective effect, with hazard ratios of 1.35 (1.29, 1.41) and 0.90 (0.86, 0.94) for per tertile increment, respectively. These relationships remained consistent in two-exposure models, and a significant modification effect of greenness on the UV-AMD association was observed. Notably, when the residential greenness over 0.4, the hazard of UV on incident AMD became non-significant. This greenness threshold remained consistent across rural-urban and south-north subgroups.

CONCLUSION

Maintaining the residential greenness above 0.4, as a low-cost measure at population-level, could mitigate the UV-AMD association and facilitate the health equity in China, regardless of the regions.

Causal Relationships Between Retinal Diseases and Psychiatric Disorders Have Implications for Precision Psychiatry

Observational studies and clinical trials have reported potential associations between retinal diseases and psychiatric disorders. However, the causal associations between them have remained elusive. In this study, we used bi-directional two-sample Mendelian randomization (MR) analysis to explore unconfounded causal relationships between retinal diseases and psychiatric disorders using large-scale genome-wide association study (GWAS) summary statistics of over 500,000 participants of European ancestry from the FinnGen project, the Psychiatric Genomics Consortium, the European Bioinformatics Institute, and the UK Biobank. Our MR analysis revealed significant causal relationships between major retinal diseases and specific psychiatric disorders. Specifically, susceptibility to dry age-related macular degeneration was associated with a reduced risk of anorexia nervosa (OR = 0.970; 95% CI = 0.930 ~ 0.994; P = 0.025). Furthermore, we found some evidence that exposure to diabetic retinopathy was associated with an increased risk of schizophrenia (OR = 1.021; 95% CI 1.012 ~ 1.049; P = 0.001), and exposure to retinal detachments and breaks was associated with an increased risk of attention deficit hyperactivity disorder (OR = 1.190; 95% CI 1.063 ~ 1.333; P = 0.003). These causal relationships were not confounded by biases of pleiotropy and reverse causation. Our study highlights the importance of preventing and managing retinal disease as a potential avenue for improving the prevention, management and treatment of major psychiatric disorders.

Glymphatic system impairment in normal tension glaucoma evaluated by diffusion tensor image analysis along the perivascular space

Disruption of the glymphatic system plays a vital role in pathogenesis of neurodegeneration in normal tension glaucoma (NTG). We evaluated the impairment of glymphatic system of NTG patients by diffusion tensor image analysis along the perivascular space (DTI-ALPS), and explored the correlation between the ALPS index and dysfunction of visual cortices in resting state. DTI-ALPS was applied to 37 normal controls (NCs) and 37 NTG patients. Multidirectional diffusivity maps and fractional anisotropy (FA) maps were reconstructed to calculate ALPS index. The Amplitude of low-frequency fluctuation (ALFF) in visual cortices (V1-V5) were calculated using resting-state fMRI. Clinical data and ALPS indexes were compared between the groups. Lateralization of ALPS indexes and differences in visual field of two eyes were analyzed. Subsequently, regression analyses between ALPS indexes and mean deviation (MD) values of bilateral eyes and ALFF of visual cortices were performed. The bilateral ALPS indexes of NTG patients decreased significantly. In NCs and NTG patients, ALPS indexes in right hemisphere were lower than that in left hemisphere. The right ALPS indexes of NTG patients were positively correlated with the MD values of the left eyes. In NTG patients, decreased ALFF was detected in right V1 and bilateral V2-5, and the left ALPS indexes were positively correlated with ALFF in bilateral V1, V2, V5, and right V3V area. The ALPS index decreased in NTG patients, correlated with visual defects and ALFF, indicating impairment of the glymphatic system and the potential to be a biomarker in the future.

Exogenous hydrogen sulfide and NOX2 inhibition mitigate ferroptosis in pressure-induced retinal ganglion cell damage

Glaucoma, a leading cause of irreversible blindness worldwide, is characterized by the progressive degeneration of retinal ganglion cells (RGCs). While elevated intraocular pressure (IOP) significantly contributes to disease progression, managing IOP alone does not completely halt it. The mechanisms underlying RGCs loss in glaucoma remain unclear, but ferroptosis-an iron-dependent form of oxidative cell death-has been implicated, particularly in IOP-induced RGCs loss. There is an urgent need for neuroprotective treatments. Our previous research showed that hydrogen sulfide (H2S) protects RGCs against glaucomatous injury. This study aims to investigate the interplay between elevated pressure, mitochondrial dysfunction, iron homeostasis, and ferroptosis in RGCs death, focusing on how H2S may mitigate pressure-induced ferroptosis and protect RGCs. We demonstrate alterations in iron metabolism and mitochondrial function in a subacute IOP elevation model in vivo. In vitro, we confirm that elevated pressure, iron overload, and mitochondrial dysfunction lead to RGCs loss, increased retinal ferrous iron and total iron content, and heightened reactive oxygen species (ROS). Notably, pressure increases NADPH oxidase 2 (NOX2) and decreases glutathione peroxidase 4 (GPX4), a key regulator of ferroptosis. NOX2 deletion or inhibition by H2S prevents pressure-induced RGCs loss and ferroptosis. Our findings reveal that H2S chelates iron, regulates iron metabolism, reduces oxidative stress, and mitigates ferroptosis, positioning slow-releasing H2S donors are positioning as a promising multi-target therapy for glaucoma, with NOX2 emerging as a key regulator of ferroptosis.

Therapeutic effect of dihydroartemisinin on Alzheimer's disease model mice with senile macular degeneration

OBJECTIVES

This study focuses on the preventive and therapeutic effects of Dihydroartemisinin (DHA) on Alzheimer's disease (AD) model mice and the effects of DHA and donepezil on amyloid β-protein deposition and autophagy in nerve cells.

METHODS

Six autophagy related targets were selected for molecular docking with DHA to predict the affinity between DHA and the target. The AD mouse model was established and treated with donepezil and DHA, respectively. Morris water maze was used to detect the spatial learning and memory ability of AD mice. Hematoxylin eosin (he) staining was used to observe the structural changes of cerebral cortical neurons and retina, and transmission electron microscope was used to observe the structural changes of mitochondria and synapses. Immunohistochemistry (IHC) and immunofluorescence staining were used to detect the deposition of amyloid beta protein. Western blot was used to detect the expression of apoptosis and autophagy related proteins in the brain tissue of mice in each group.

RESULTS

The results of molecular docking showed that the selected active compounds had good binding activity with the target. The binding energy between DHA and Aβ, Bcl-2, ATG5, LC3, Caspase3, LAMP1 is -5.7, -7.0, -5.8, -7.2, -6.9 kcal/mol. The water maze test showed that compared with the wild type (WT) group, the spatial memory ability of AD model group mice (5× FAD) was significantly decreased, and the search time (27.62 ± 6.51 s vs. 282.80 ± 17.15 s) and average path (106.30 ± 29.65 cm vs. 993.20 ± 135.80 cm) were significantly prolonged. The application of donepezil and DHA significantly shortened the exploration time and average path (donepezil: 116.10 ± 10.58 s, 529.40 ± 106.00 cm; DHA: 99.71 ± 14.22 s, 373.30 ± 60.97 cm). The path to find the platform in DHA treatment group was shorter than donepezil treatment group (P < 0.05). HE staining showed that the arrangement of nerve cells in 5× FAD mice was disordered, and IHC showed that amyloid β-protein deposition was obvious. DHA and donepezil could improve the damage of cerebral cortex structure and reduce the deposition of extracellular amyloid β-protein in AD mice. Transmission electron microscopy showed that DHA and donepezil could reduce mitochondrial vacuolation and synaptic edema. The above results showed that DHA treatment effect was better than donepezil. Compared with the conventional feeding group, autophagy and apoptosis related proteins B-cell lymphoma-2 (BCL2) and anti-thymocyte globulin (ATG) were significantly down regulated in the 5× FAD group, and the expressions of BCL2 and ATG were increased after treatment with DHA and donepezil.

CONCLUSIONS

DHA combined with BCL2 and ATG protein, through promoting autophagy protein, can reduce the damage of cerebral cortex structure in AD mice, reduce the deposition of extracellular β-amyloid protein, and then improve the memory ability of AD model mice. DHA treatment is superior to donepezil monotherapy.

Non-Invasive Retinal Biomarkers for Early Diagnosis of Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder of the brain associated with ageing and is the most prevalent form of dementia, affecting an estimated 55 million people worldwide, with projections suggesting this number will exceed 150 million by 2050. With its increasing prevalence, AD represents a significant global health challenge with potentially serious social and economic consequences. Diagnosing AD is particularly challenging as it requires timely recognition. Currently, there is no effective therapy for AD; however, certain medications may help slow its progression. Existing diagnostic methods such as magnetic resonance imaging (MRI), computed tomography (CT), positron emission tomography (PET), and biomarker analysis in cerebrospinal fluid tend to be expensive and invasive, making them impractical for widespread use. Consequently, research into non-invasive biomarkers that enable early detection and screening for AD is a crucial area of contemporary clinical investigation. One promising approach for the early diagnosis of AD may be retinal imaging. As an extension of the central nervous system, the retina offers a distinctive opportunity for non-invasive brain structure and function assessment. Considering their shared embryological origins and the vascular and immunological similarities between the eye and brain, alterations in the retina may indicate pathological changes in the brain, including those specifically related to AD. Studies suggest that structural and vascular changes in the retina, particularly within the neuronal network and blood vessels, may act as markers of cerebral changes caused by AD. These retinal alterations have the potential to act as biomarkers for early diagnosis. Since AD is typically diagnosed only after a significant neuronal loss has occurred, identifying early diagnostic markers could enable timely intervention and help prevent disease progression. Non-invasive retinal imaging techniques, such as optical coherence tomography (OCT) and OCT angiography, provide accessible methods for the early detection of changes linked to AD. This review article focuses on the potential of retinal imaging as a non-invasive biomarker for early diagnosis of AD. Investigating the ageing of the retina and its connections to neurodegenerative processes could significantly enhance the diagnosis, monitoring, and treatment of AD, paving the way for new diagnostic and therapeutic approaches.

Dynamic light scattering of the eye in the diagnosis of Alzheimer's disease

The early detection of Alzheimer's disease, before symptoms have appeared, is integral to the development of effective treatments. Dynamic light scattering spectroscopy measures the Brownian movement of proteins at the molecular level. This technique may facilitate early Alzheimer's disease diagnosis and the discovery of pharmaceuticals that may prevent symptom development.

[Study on the regulatory effect of low intensity retinal ultrasound stimulation on the neural activity of visual cortex]

Low-intensity ultrasound stimulation of the retina has the ability to modulate neural activity in the primary visual cortex (V1), however, it is currently unclear how different intensities and durations of ultrasonic stimulation of the retina modulate neural activity in V1. In this paper, we recorded local field potential (LFP) signals in the V1 brain region of mice under different ultrasound intensities and different stimulation times. The amplitude of LFP corresponding to 1 s before ultrasound stimulation to 2 s after stimulation (-1-2 s) was analyzed, including the power and sample entropy of delta, theta, alpha beta, and low gamma frequency bands. The experimental results showed that, as the stimulation intensity increased, the peak value of the LFP in the visual cortex showed a linear upward trend; the power in the delta and theta frequency bands showed a linear upward trend, and the sample entropy showed a linear downward trend. With increases of stimulation duration, the peak value of the LFP in the visual cortex showed an upward trend, and the upward trend gradually weakened; the power in the delta frequency band showed an upward trend, the sample entropy showed a linear upward trend, and the sample entropy in the theta frequency band showed a downward trend. The results show that low-intensity ultrasonic stimulation of the retina has a significant modulatory effect on neural activity in the visual cortex. The study provides insights into the mechanisms by which ultrasonic stimulation regulates visual system function. Furthermore, it clarifies the patterns of parameter selection, facilitating the development of personalized multi-parameter modulation for the treatment of visual neural degeneration, retinal disorders and related research areas.

Amyloid beta biomarker for dementia detection by hyperspectral ophthalmoscope images

The escalating prevalence and economic burden of dementia underscore the urgency for innovative detection methods. This study investigates the potential of hyperspectral imaging (HSI) to detect dementia by analyzing retinal changes associated with amyloid beta (Aβ) formations. Leveraging a dataset of 3,256 ophthalmoscopic images from 137 participants aged 60 to 85 years, categorized into dementia and non-dementia groups via the Mini-Mental State Examination (MMSE), we extracted features from five key regions of interest (ROIs) identified for their pronounced changes in Aβ biomarkers. The analysis revealed that gender does not significantly influence dementia levels, and no substantial spectral differences were observed within the 380 nm to 600 nm wavelength range. However, significant variations in spectral reflection intensity were noted between 600 nm and 780 nm across both genders, suggesting a potential avenue for distinguishing stages of dementia. Despite the impact of diabetes on the vascular system, its stages did not significantly influence dementia development. This research highlights the utility of HSI in identifying dementia-related retinal changes and calls for further exploration into its effectiveness as a diagnostic tool, potentially offering a non-invasive method for early detection of dementia.

Associations Between Retinal Vascular Occlusions and Dementia

BACKGROUND/OBJECTIVES

Retinal vascular occlusions, such as retinal vein occlusion (RVO) and retinal artery occlusion (RAO), are associated with cognitive impairment, including dementia. Our objective was to examine the odds of dementia among patients with retinal vascular occlusion.

METHODS

This cross-sectional study included 474 patients with retinal vascular occlusion and 948 patients without retinal vascular occlusion (comparison group). Patients in the comparison group were age- and sex-matched to those with vascular occlusion. Logistic regression was used to analyze the odds of all-cause dementia, vascular dementia, and Alzheimer's disease after adjusting for demographic, clinical, and ophthalmic covariates. Main outcome measures included the presence of all-cause dementia, vascular dementia, and Alzheimer's disease.

RESULTS

Patients with RVO (n = 413) had increased odds for all-cause dementia (odds ratio (OR) = 2.32; 95% confidence interval (CI): 1.44-3.75; p < 0.001) and vascular dementia (OR = 3.29; 95% CI: 1.41-7.68; p = 0.006) relative to the comparison group. Patients with central RVO (n = 192) (OR = 2.32; 95% CI: 1.19-4.54; p = 0.014) or branch RVO (n = 221) (OR = 2.68; 95% CI: 1.30-5.50; p = 0.007) had increased odds for all-cause dementia relative to the comparison group. Patients with RAO (n = 61) did not have increased odds of all-cause dementia (OR = 1.01; 95% CI: 0.32-3.26; p = 0.983), vascular dementia (OR = 1.54; 95% CI: 0.22-10.81; p = 0.663), or Alzheimer's disease (OR = 0.32; 95% CI: 0.05-2.20; p = 0.244).

CONCLUSIONS

A history of any RVO is associated with increased rates of all-cause dementia and vascular dementia independent of shared cardiovascular risk factors. These associations are not seen with a history of RAO, or between any subtype of vascular occlusions and Alzheimer's disease.

Protective effect of zinc against A2E-induced toxicity in ARPE-19 cells: Possible involvement of lysosomal acidification

A key pathogenic mechanism of dry age-related macular degeneration (AMD) is lysosomal dysfunction in retinal pigment epithelium (RPE) cells, which results in the accumulation of lipofuscins such as A2E (N-retinylidene-N-retinylethanolamine) that further compromises lysosomal function. This vicious cycle leads to cell death and poor visual acuity. Here, we established an in vitro model of AMD by treating a human RPE cell line (ARPE-19) with A2E and examined whether raising zinc levels confers protective effects against lysosomal dysfunction and cytotoxicity. MTT assay showed that A2E induced apoptosis in ARPE-19 cells. pHrodo™ Red fluorescence staining showed that lysosomal pH increased in A2E-treated ARPE-19 cells. Treatment with a zinc ionophore (clioquinol) reduced A2E accumulation, restored lysosomal pH to the acidic range, and reduced A2E-induced cell death, all of which were reversed by the addition of a zinc chelator (TPEN). Consistent with the in vitro results, subretinal injections of A2E in mouse eyes resulted in the death of RPE cells as well as lysosomal dysfunction, all of which were reversed by co-treatment with clioquinol. Our results suggest that restoring the levels of intracellular zinc, especially in lysosomes, would be helpful in mitigating A2E-induced cytotoxic changes including lysosomal dysfunction in RPE cells in the pathogenesis of AMD.

Associations between vision impairment and eye diseases with dementia, dementia subtypes and cognitive impairment: An umbrella review

Vision impairment (VI) and eye diseases such as age-related macular degeneration (AMD), diabetic retinopathy (DR), glaucoma and cataract have been reported to be associated with cognitive impairment and dementia, however, to date, very little attempt has been made to collate and synthesizes such literature. Therefore, the aim of this umbrella review is to systematically assesses the credibility and certainty of evidence of associations between vision impairment (VI) and eye diseases with cognitive impairment, dementia and dementia subtypes. We conducted an umbrella review of meta-analyses by screening articles in any language in PubMed, MEDLINE (Ovid), EMBASE, Web of Science, Cochrane CENTRAL and CDSR published from database inception up to May 30, 2024. Quality appraisal of each included original meta-analysis was assessed using A Measurement Tool for Assessing Systematic Reviews 2 (AMSTAR2). The certainty of the evidence was based on statistical significance, study size, heterogeneity, small study effects, prediction intervals (PI), and bias. We followed an a-priori protocol registered with PROSPERO (CRD42024564249). We identified 13 meta-analyses (AMSTAR 2; high accuracy of the findings 1, moderate 10, and low 2) that included 232 original articles based on 99,337,354 participants. Overall, no evidence was highly suggestive or convincing. Suggestive evidence was found for associations between cataract and dementia (equivalent odds ratio [eOR] 1.20, 95 %CI, 1.16-1.25), cataract and Alzheimer's disease (eOR 1.21, 95 %CI, 1.15-1.28), and AMD and Alzheimer's disease (eOR 1.27, 95 %CI, 1.27-1.27). Weak evidence was found for associations between VI and dementia (eOR 1.50, 95 %CI, 1.23-1.84), DR and dementia (eOR 1.33, 95 %CI, 1.17-1.50), cataract and vascular dementia (eOR 1.26, 95 %CI, 1.09-1.45), VI identified by cross-sectional studies and cognitive impairment (eOR 2.37, 95 %CI, 2.31-2.44), and VI identified by objective measures and cognitive impairment (eOR 1.56, 95 %CI, 1.12-2.18). The observed suggestive level of evidence for the relationship between eye disease and dementia (as well as dementia subtypes) suggests that policy and interventions to aid in the prevention and management of eye disease may also aid in the prevention of dementia syndrome. Where the level of evidence is weak, further studies are needed with stronger methodological approaches.

Transgenic sensors reveal compartment-specific effects of aggregation-prone proteins on subcellular proteostasis during aging

Loss of proteostasis is a hallmark of aging that underlies many age-related diseases. Different cell compartments experience distinctive challenges in maintaining protein quality control, but how aging regulates subcellular proteostasis remains underexplored. Here, by targeting the misfolding-prone FlucDM luciferase to the cytoplasm, mitochondria, and nucleus, we established transgenic sensors to examine subcellular proteostasis in Drosophila. Analysis of detergent-insoluble and -soluble levels of compartment-targeted FlucDM variants indicates that thermal stress, cold shock, and pro-longevity inter-organ signaling differentially affect subcellular proteostasis during aging. Moreover, aggregation-prone proteins that cause different neurodegenerative diseases induce a diverse range of outcomes on FlucDM insolubility, suggesting that subcellular proteostasis is impaired in a disease-specific manner. Further analyses with FlucDM and mass spectrometry indicate that pathogenic tauV337M produces an unexpectedly complex regulation of solubility for different FlucDM variants and protein subsets. Altogether, compartment-targeted FlucDM sensors pinpoint a diverse modulation of subcellular proteostasis by aging regulators.

Disease Associations among Patients Afflicted with Both Glaucoma and Age-Related Macular Degeneration

Background/Objectives: This study investigates whether there is an increased propensity to systemic conditions in patients with both age-related macular degeneration (AMD) and glaucoma in order to provide greater insight into patients' overall health and response to physiologic stress. Methods: A large retrospective dataset review was conducted between April 2004 and June 2018, distinguishing four groups based on international classification of diseases (ICD) codes: glaucoma only, AMD only, glaucoma and AMD, and cataracts only (as an age-matched control). The systemic disease prevalence of each group was calculated, and a Friedman analysis was used to compare the prevalence between the groups. Results: This study identified 5243 patients with glaucoma only, 6726 with AMD only, 402 with combined disease, and 25,450 with cataracts only. Age and racial distributions varied between groups in a predictable manner. Two conditions, heart failure (HF) and dementia, had a statistically higher prevalence in patients with both glaucoma and AMD compared to those with glaucoma alone (HF p = 0.036, dementia p = 0.024) and cataracts alone (HF p = 0.003, dementia p = 0.036). There was no significant difference observed in terms of ethnicity and gender among the different disease groups (p > 0.05). Conclusions: Both AMD and glaucoma individually portend a higher rate of comorbidities than age-matched controls. Patients with concomitant AMD and glaucoma demonstrate a uniquely higher prevalence of heart failure and dementia than those with either disease alone. The underlying association and pathologic mechanisms warrant further investigation to improve the overall health management and prognostication for these individuals.

Erigeron breviscapus: A Promising Medication for Protecting the Optic Nerve in Glaucoma

Glaucoma is a common eye condition characterized by the loss of retinal ganglion cells and their axons, optic nerve damage, and visual field defects, which seriously affect a patient's quality of life. The pathogenesis of glaucoma is still unclear at present. It presents as damage to retinal ganglion cells, and the main treatment is primarily to reduce intraocular pressure by surgery or taking medication. However, even with well-controlled intraocular pressure, retinal ganglion cells still undergo degeneration, progressive apoptosis, and axonal loss. Therefore, protecting the optic nerve and inhibiting the apoptosis of retinal ganglion cells are the current hot topic for prevention and treatment of glaucoma. Recently, Erigeron breviscapus, originating from Yunnan province in China, has been shown to be a promising herb with neuroprotective effects to treat glaucoma. Therefore, the traditional usage, botanical characteristics, and phytochemical composition of E. breviscapus were explored through a literature review. Furthermore, we have summarized the pharmacological mechanisms of E. breviscapus and its active components in inhibiting the apoptosis of retinal ganglion cells. These research findings can not only provide guidance and recommendations for the protection of retinal ganglion cells but also further explore the potential of E. breviscapus in the treatment of glaucoma.

Increased Intestinal Inflammation and Permeability in Glaucoma

Objective

Evidence suggests that dysbiosis of the gut microbiota plays a pivotal role in the development of glaucoma. This dysbiosis is commonly associated with chronic intestinal inflammation and increased intestinal permeability. However, the understanding of intestinal inflammation and permeability in glaucoma remains insufficient. This study aims to investigate the potential relationship between fecal inflammation and permeability markers and glaucoma.

Methods

We recruited 114 glaucoma patients and 75 healthy controls. Levels of fecal lactoferrin (Lf) and alpha-1 antitrypsin (AAT) were quantified using enzyme linked immunosorbent assay (ELISA) to compare both biomarkers between groups and across different severity grades of glaucoma. Logistic regression analysis was used to assess the association between these fecal biomarkers and glaucoma. The severity of glaucoma was assessed based on the mean deviation (MD) in the visual field.

Results

In this study, we observed elevated levels of fecal Lf and AAT in glaucoma patients. The proportion of glaucoma patients with abnormal fecal Lf levels (≥ 7.25 µg/g) was significantly higher than that of the controls (p = 0.012). A positive correlation was noted between fecal Lf and AAT (rho = 0.20, p = 0.006). After adjusting for age and sex, multivariable logistic regression analysis indicated that both fecal Lf (OR = 1.11, 95% CI: 1.01-1.21, p = 0.026) and AAT (OR = 1.01, 95% CI: 1.01-1.02, p < 0.001) positively correlated with glaucoma. These biomarkers might reflect glaucoma severity, with significant differences in fecal Lf levels observed between moderate and severe stages, but not in the early stage. Furthermore, increasing levels of fecal AAT correlated with greater severity of glaucomatous injury and a larger vertical cup-to-disc ratio (VCDR) (p < 0.05).

Conclusion

This study suggests an increase in intestinal inflammation and permeability in glaucoma, further indicating the importance of the 'gut-retina axis' in the pathogenesis of the disease and potentially offering new therapeutic avenues.

The unique properties of Big tau in the visual system

Tau is a microtubule associated protein that plays important roles in regulating the properties of microtubules and axonal transport, as well as tauopathies associated with toxic aggregates leading to neurodegenerative diseases. It is encoded by the MAPT gene forming multiple isoforms (45-60 kDa) by alternative splicing which are developmentally regulated. The high molecular weight (MW) tau isoform of 105 kDa, termed Big tau, was originally discovered in the peripheral nervous system (PNS) but later found in selective CNS areas. It contains an additional large exon 4a generating a long projecting domain of about 250 amino acids. Here we investigated the properties of Big tau in the visual system of rats, its distribution in retinal ganglion cells and the optic nerve as well as its developmental regulation using biochemical, molecular and histological analyses. We discovered that Big tau is expresses as a 95 kDa protein (termed middle MW) containing exons 4a, 6 as well as exon 10 which defines a 4 microtubule-binding repeats (4R). It lacks exons 2/3 but shares the extensive phosphorylation characteristic of other tau isoforms. Importantly, early in development the visual system expresses only the low MW isoform (3R) switching to both the low and middle MW isoforms (4R) in adult retinal ganglion neurons and their corresponding axons. This is a unique structure and expression pattern of Big tau, which we hypothesize is associated with the specific properties of the visual system different from what has been previously described in the PNS and other areas of the nervous system.

A Comprehensive Evaluation of Serum Iron Status Indicators in Patients with Age-Related Macular Degeneration

Objectives

Iron is recognized as a significant contributor to oxidative damage, and its levels tend to rise with age, potentially worsening age-related diseases. The aim of this study was to investigate the role of serum iron metabolism markers in the pathogenesis of age-related macular degeneration (AMD).

Methods

The files of all AMD patients in Kocaeli University School of Medicine between January 2017 and March 2020 were reviewed retrospectively. By examining the files of AMD patients who applied to the eye outpatient clinic on the same dates, those dry AMD (dAMD) and neovascular AMD (nAMD) were recorded. As a control group, the records of patients without any AMD findings were obtained from the files of all patients who visited the clinic during the same time period. All records were recorded for analysis, including a comprehensive ophthalmological examination, laboratory data of fasting blood tests, and an internal medicine outpatient examination.

Results

Of the 164 participants, 50 were dAMD patients, 51 were nAMD patients, and 63 were patients non-AMD (control group). There was a significant difference between the groups' mean corpuscular volume (MCV), serum ferritin, and total iron-binding capacity (TIBC) (p<0.050). It was observed that the ferritin of those with AMD was significantly higher than the control group, whereas MCV and TIBC were found to be significantly lower (p<0.050). There was no significant difference in serum iron marker levels between nAMD and dAMD patients (p>0.05).

Conclusion

Assessing serum iron status indicators during the routine monitoring of AMD may provide insights into the associated risk profile of the condition.

Carotenoid Supplementation for Alleviating the Symptoms of Alzheimer's Disease

Alzheimer's disease (AD) is characterized by, among other things, dementia and a decline in cognitive performance. In AD, dementia has neurodegenerative features and starts with mild cognitive impairment (MCI). Research indicates that apoptosis and neuronal loss occur in AD, in which oxidative stress plays an important role. Therefore, reducing oxidative stress with antioxidants is a natural strategy to prevent and slow down the progression of AD. Carotenoids are natural pigments commonly found in fruits and vegetables. They include lipophilic carotenes, such as lycopene, α- and β-carotenes, and more polar xanthophylls, for example, lutein, zeaxanthin, canthaxanthin, and β-cryptoxanthin. Carotenoids can cross the blood-brain barrier (BBB) and scavenge free radicals, especially singlet oxygen, which helps prevent the peroxidation of lipids abundant in the brain. As a result, carotenoids have neuroprotective potential. Numerous in vivo and in vitro studies, as well as randomized controlled trials, have mostly confirmed that carotenoids can help prevent neurodegeneration and alleviate cognitive impairment in AD. While carotenoids have not been officially approved as an AD therapy, they are indicated in the diet recommended for AD, including the consumption of products rich in carotenoids. This review summarizes the latest research findings supporting the potential use of carotenoids in preventing and alleviating AD symptoms. A literature review suggests that a diet rich in carotenoids should be promoted to avoid cognitive decline in AD. One of the goals of the food industry should be to encourage the enrichment of food products with functional substances, such as carotenoids, which may reduce the risk of neurodegenerative diseases.

α-1 antitrypsin is promising for the identification of glaucoma severity and is associated with glaucomatous neural damage

Aim: To investigate the association between plasma AAT level and glaucoma.Methods: 163 glaucoma patients and 111 healthy controls were recruited. The plasma AAT levels were measured by ELISA.Results: Plasma AAT level was significantly higher in glaucoma patients than those in healthy controls (p < 0.001). Patients with higher plasma AAT level exhibited severer disease stage (early vs. severe: p < 0.05; H-P-A; early vs. severe: p < 0.05; early vs. end-stage: p < 0.01; AGIS). ROC curves yielded that AAT can distinguish patients with early glaucoma from those with advanced glaucoma (early vs. severe: AUC: 0.616; H-P-A; early vs. severe: AUC: 0.763; early vs. end-stage: AUC: 0.660; AGIS).Conclusion: Plasma AAT is a useful biomarker for the identification of glaucoma severity.

Retinal imaging and Alzheimer's disease: a future powered by Artificial Intelligence

Alzheimer's disease (AD) is a neurodegenerative condition that primarily affects brain tissue. Because the retina and brain share the same embryonic origin, visual deficits have been reported in AD patients. Artificial Intelligence (AI) has recently received a lot of attention due to its immense power to process and detect image hallmarks and make clinical decisions (like diagnosis) based on images. Since retinal changes have been reported in AD patients, AI is being proposed to process images to predict, diagnose, and prognosis AD. As a result, the purpose of this review was to discuss the use of AI trained on retinal images of AD patients. According to previous research, AD patients experience retinal thickness and retinal vessel density changes, which can occasionally occur before the onset of the disease's clinical symptoms. AI and machine vision can detect and use these changes in the domains of disease prediction, diagnosis, and prognosis. As a result, not only have unique algorithms been developed for this condition, but also databases such as the Retinal OCTA Segmentation dataset (ROSE) have been constructed for this purpose. The achievement of high accuracy, sensitivity, and specificity in the classification of retinal images between AD and healthy groups is one of the major breakthroughs in using AI based on retinal images for AD. It is fascinating that researchers could pinpoint individuals with a positive family history of AD based on the properties of their eyes. In conclusion, the growing application of AI in medicine promises its future position in processing different aspects of patients with AD, but we need cohort studies to determine whether it can help to follow up with healthy persons at risk of AD for a quicker diagnosis or assess the prognosis of patients with AD.

SIRT4 Protects Müller Glial Cells Against Apoptosis by Mediating Mitochondrial Dynamics and Oxidative Stress

SIRT4 is a member of the sirtuin family, which is related to mitochondrial function and possesses antioxidant and regulatory redox effects. Currently, the roles of SIRT4 in retinal Müller glial cells, oxidative stress, and mitochondrial function are still unclear. We confirmed, by immunofluorescence staining, that SIRT4 is located mainly in the mitochondria of retinal Müller glial cells. Using flow cytometry and Western blotting, we analyzed cell apoptosis, intracellular reactive oxygen species (ROS) levels, apoptotic and proapoptotic proteins, mitochondrial dynamics-related proteins, and mitochondrial morphology and number after the overexpression and downregulation of SIRT4 in rMC-1 cells. Neither the upregulation nor the downregulation of SIRT4 alone affected apoptosis. SIRT4 overexpression reduced intracellular ROS, reduced the BAX/BCL2 protein ratio, and increased the L-OPA/S-OPA1 ratio and the levels of the mitochondrial fusion protein MFN2 and the mitochondrial cleavage protein FIS1, increasing mitochondrial fusion. SIRT4 downregulation had the opposite effect. Mitochondria tend to divide after serum starvation for 24 h, and SIRT4 downregulation increases mitochondrial fragmentation and oxidative stress, leading to aggravated cell damage. The mitochondrial division inhibitor Mdivi-1 reduced oxidative stress levels and thus reduced cell damage caused by serum starvation. The overexpression of SIRT4 in rMC-1 cells reduced mitochondrial fragmentation caused by serum starvation, leading to mitochondrial fusion and reduced expression of cleaved caspase-3, thus alleviating the cellular damage caused by oxidative stress. Thus, we speculate that SIRT4 may protect retinal Müller glial cells against apoptosis by mediating mitochondrial dynamics and oxidative stress.

Ventriculoperitoneal shunt patients and glaucoma: a cohort analysis of the NPH registry

BACKGROUND

Idiopathic Normal Pressure Hydrocephalus (iNPH) is a chronic condition affecting the elderly. It is characterized by a triad of symptoms and radiological findings. Glaucoma is the leading cause of irreversible blindness worldwide. Earlier studies have proposed that the rate of glaucoma is higher in iNPH patients, and of a possible link between ventriculoperitoneal shunt (VP) treatment and the development of glaucoma.

OBJECTIVES

This study aimed to determine the prevalence of glaucoma among iNPH patients and assess the impact of VPs on glaucoma prevalence.

METHODS

A cohort study was conducted at Kuopio University Hospital (KUH), including 262 patients with a ventriculoperitoneal shunt. Clinical data were obtained from the Kuopio NPH Registry and medical records. Patients were grouped by iNPH status: iNPH (+) - probable/possible iNPH (n = 192), and iNPH (-) - other causes of hydrocephalus (congenital, secondary, obstructive) (n = 70). We conducted statistical analysis using the Independent Samples T-test, Fisher's exact test, and Pearson Chi-Square. We compared demographics, glaucoma prevalence, brain biopsies positive for Amyloid-β (Aβ) and hyperphosphorylated tau (HPτ) as well as comorbidities for hypertension and diabetes medication. Age stratification assessed glaucoma prevalence in the full cohort.

RESULTS

Both iNPH (+) and iNPH (-) groups had comparable demographic and comorbidity profiles. The prevalence of glaucoma in the iNPH (+) group was 11.5% (n = 22) and 11.4% (n = 8) in the iNPH (-) group without a statistically significant difference (p = 1.000). Brain biopsies positive for Amyloid-β (Aβ) and hyperphosphorylated tau (HPτ) were similar.

CONCLUSIONS

Neither shunted iNPH patients nor those with a comorbid condition other than iNPH showed a markedly higher prevalence of glaucoma. Instead, both groups exhibited age-related increases in glaucoma prevalence, similar to the trends observed in population-based studies. Our data does not suggest a correlation between VP shunts and an elevated rate of glaucoma.

The Prodrug DHED Delivers 17β-Estradiol into the Retina for Protection of Retinal Ganglion Cells and Preservation of Visual Function in an Animal Model of Glaucoma

We report a three-pronged phenotypic evaluation of the bioprecursor prodrug 10β,17β-dihydroxyestra-1,4-dien-3-one (DHED) that selectively produces 17β-estradiol (E2) in the retina after topical administration and halts glaucomatous neurodegeneration in a male rat model of the disease. Ocular hypertension (OHT) was induced by hyperosmotic saline injection into an episcleral vein of the eye. Animals received daily DHED eye drops for 12 weeks. Deterioration of visual acuity and contrast sensitivity by OHT in these animals were markedly prevented by the DHED-derived E2 with concomitant preservation of retinal ganglion cells and their axons. In addition, we utilized targeted retina proteomics and a previously established panel of proteins as preclinical biomarkers in the context of OHT-induced neurodegeneration as a characteristic process of the disease. The prodrug treatment provided retina-targeted remediation against the glaucomatous dysregulations of these surrogate endpoints without increasing circulating E2 levels. Collectively, the demonstrated significant neuroprotective effect by the DHED-derived E2 in the selected animal model of glaucoma supports the translational potential of our presented ocular neuroprotective approach owing to its inherent therapeutic safety and efficacy.

Transcriptome Study of rd1Mouse Brain and Association with Parkinson's Disease

Degeneration of the retina is intrinsically associated with the pathogenesis and progression of neurodegenerative diseases. However, the cellular and molecular mechanisms underlying the association between neurodegeneration and retinal degeneration are still under exploration due to the complexity of the connectivity network of the nervous system. In this study, RNA-seq data from the brains of model retinitis pigmentosa (RP) mice and previously studied Parkinson's disease (PD) mice were analyzed to explore the commonalities between retinal degenerative and neurodegenerative diseases. Differentially expressed genes in RP were compared with neurodegenerative disease-related genes and intersecting genes were identified, including Cnr1 and Septin14. These genes were verified by quantitative real-time reverse transcription PCR and Western blotting experiments. The key proteins CNR1 and SEPTIN14 were found to be potential cotherapeutic targets for retinal degeneration and neurodegenerative disease. In conclusion, understanding the commonalities between retinal degenerative diseases and neurodegenerative processes in the brain will not only facilitate the interpretation of the underlying pathomechanisms but also contribute to early diagnosis and the development of new therapeutic strategies.

Molecular mechanisms of secretory autophagy and its potential role in diseases

Autophagy is a cellular degradation system that recycles or degrades damaged organelles, viral particles, and aggregated proteins through the lysosomal pathway. Autophagy plays an indispensable role in cellular homeostasis and communication processes. An interesting aspect is that autophagy also mediates the secretion of cellular contents, a process known as secretory autophagy. Secretory autophagy differs from macroautophagy, which sequesters recruited proteins, organelles, or viral particles into autophagosomes and degrades these sequesters in lysosomes, while the secretory autophagy pathway participates in the extracellular export of cellular contents sequestered by autophagosomes through autophagy and endosomal modulators. Recent evidence reveals that secretory autophagy is pivotal in the occurrence and progression of diseases. In this review, we summarize the molecular mechanisms of secretory autophagy. Furthermore, we review the impact of secretory autophagy on diseases, including cancer, viral infectious diseases, neurodegenerative diseases, and cardiovascular diseases. Considering the pleiotropic actions of secretory autophagy on diseases, studying the mechanism of secretory autophagy may help to understand the relevant pathophysiological processes.

Small extracellular vesicles of organoid-derived human retinal stem cells remodel Müller cell fate via miRNA: A novel remedy for retinal degeneration

Remodeling retinal Müller glial fate, including gliosis inhibition and pro-reprogramming, represents a crucial avenue for treating degenerative retinal diseases. Stem cell transplantation exerts effects on modulating retinal Müller glial fate. However, the optimized stem cell products and the underlying therapeutic mechanisms need to be investigated. In the present study, we found that retinal progenitor cells from human embryonic stem cell-derived retinal organoids (hERO-RPCs) transferred extracellular vesicles (EVs) into Müller cells following subretinal transplantation into RCS rats. Small EVs from hERO-RPCs (hERO-RPC-sEVs) were collected and were found to delay photoreceptor degeneration and protect retinal function in RCS rats. hERO-RPC-sEVs were taken up by Müller cells both in vivo and in vitro, and inhibited gliosis while promoting early dedifferentiation of Müller cells. We further explored the miRNA profiles of hERO-RPC-sEVs, which suggested a functional signature associated with neuroprotection and development, as well as the regulation of stem cell and glial fate. Mechanistically, hERO-RPC-sEVs might regulate the fate of Müller cells by miRNA-mediated nuclear factor I transcription factors B (NFIB) downregulation. Collectively, our findings offer novel mechanistic insights into stem cell therapy and promote the development of EV-centered therapeutic strategies.

Amyloid-beta and tau protein beyond Alzheimer's disease

ABSTRACT

The aggregation of amyloid-beta peptide and tau protein dysregulation are implicated to play key roles in Alzheimer's disease pathogenesis and are considered the main pathological hallmarks of this devastating disease. Physiologically, these two proteins are produced and expressed within the normal human body. However, under pathological conditions, abnormal expression, post-translational modifications, conformational changes, and truncation can make these proteins prone to aggregation, triggering specific disease-related cascades. Recent studies have indicated associations between aberrant behavior of amyloid-beta and tau proteins and various neurological diseases, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, as well as retinal neurodegenerative diseases like Glaucoma and age-related macular degeneration. Additionally, these proteins have been linked to cardiovascular disease, cancer, traumatic brain injury, and diabetes, which are all leading causes of morbidity and mortality. In this comprehensive review, we provide an overview of the connections between amyloid-beta and tau proteins and a spectrum of disorders.

Iron chelators: as therapeutic agents in diseases

The concentration of iron is tightly regulated, making it an essential element. Various cellular processes in the body rely on iron, such as oxygen sensing, oxygen transport, electron transfer, and DNA synthesis. Iron excess can be toxic because it participates in redox reactions that catalyze the production of reactive oxygen species and elevate oxidative stress. Iron chelators are chemically diverse; they can coordinate six ligands in an octagonal sequence. Because of the ability of chelators to trap essential metals, including iron, they may be involved in diseases caused by oxidative stress, such as infectious diseases, cardiovascular diseases, neurodegenerative diseases, and cancer. Iron-chelating agents, by tightly binding to iron, prohibit it from functioning as a catalyst in redox reactions and transfer iron and excrete it from the body. Thus, the use of iron chelators as therapeutic agents has received increasing attention. This review investigates the function of various iron chelators in treating iron overload in different clinical conditions.

Altered functional connectivity between the default mode network in primary angle-closure glaucoma patients

Previous studies have recognized glaucoma as a neurodegenerative disease that causes extensive brain damage and is closely associated with cognitive function. In this study, we employed functional MRI to examine the intrinsic functional connectivity patterns of the default mode network (DMN) in patients diagnosed with primary angle-closure glaucoma (PACG), exploring its association with cognitive dysfunction. A total of 34 patients diagnosed with PACG and 34 healthy controls (HC), who were matched in terms of sex, age, and education, were included in the control group. The posterior cingulate cortex (PCC) was selected as the region of interest to examine functional connectivity alterations. Compared with the HC group, functional connectivity was attenuated in left anterior cingulum cortex and left paracentral lobule between with PCC in the PACG group, the results are statistically significant. Our study revealed that patients with PACG exhibit weakened functional connectivity within the DMN. This finding suggests the presence of a neurological mechanism that is associated with both visual dysfunction and cognitive impairments in PACG patients. Furthermore, our study provides neuroimaging evidence that can aid in the exploration of spontaneous neurological alterations and facilitate a deeper investigation of alterations in the visual conduction pathways of PACG patients.

Fractal Phototherapy in Maximizing Retina and Brain Plasticity

The neuroplasticity potential is reduced with aging and impairs during neurodegenerative diseases and brain and visual system injuries. This limits the brain's capacity to repair the structure and dynamics of its activity after lesions. Maximization of neuroplasticity is necessary to provide the maximal CNS response to therapeutic intervention and adaptive reorganization of neuronal networks in patients with degenerative pathology and traumatic injury to restore the functional activity of the brain and retina.Considering the fractal geometry and dynamics of the healthy brain and the loss of fractality in neurodegenerative pathology, we suggest that the application of self-similar visual signals with a fractal temporal structure in the stimulation therapy can reactivate the adaptive neuroplasticity and enhance the effectiveness of neurorehabilitation. This proposition was tested in the recent studies. Patients with glaucoma had a statistically significant positive effect of fractal photic therapy on light sensitivity and the perimetric MD index, which shows that methods of fractal stimulation can be a novel nonpharmacological approach to neuroprotective therapy and neurorehabilitation. In healthy rabbits, it was demonstrated that a long-term course of photostimulation with fractal signals does not harm the electroretinogram (ERG) and retina structure. Rabbits with modeled retinal atrophy showed better dynamics of the ERG restoration during daily stimulation therapy for a week in comparison with the controls. Positive changes in the retinal function can indirectly suggest the activation of its adaptive plasticity and the high potential of stimulation therapy with fractal visual stimuli in a nonpharmacological neurorehabilitation, which requires further study.

Markers and mechanisms of death in Drosophila

Parameters correlated with age and mortality in Drosophila melanogaster include decreased negative geotaxis and centrophobism behaviors, decreased climbing and walking speed, and darkened pigments in oenocytes and eye. Cessation of egg laying predicts death within approximately 5 days. Endogenous green fluorescence in eye and body increases hours prior to death. Many flies exhibit erratic movement hours before death, often leading to falls. Loss of intestinal barrier integrity (IBI) is assayed by feeding blue dye ("Smurf" phenotype), and Smurf flies typically die within 0-48 h. Some studies report most flies exhibit Smurf, whereas multiple groups report most flies die without exhibiting Smurf. Transgenic reporters containing heat shock gene promoters and innate immune response gene promoters progressively increase expression with age, and partly predict remaining life span. Innate immune reporters increase with age in every fly, prior to any Smurf phenotype, in presence or absence of antibiotics. Many flies die on their side or supine (on their back) position. The data suggest three mechanisms for death of Drosophila. One is loss of IBI, as revealed by Smurf assay. The second is nervous system malfunction, leading to erratic behavior, locomotor malfunction, and falls. The aged fly is often unable to right itself after a fall to a side-ways or supine position, leading to inability to access the food and subsequent dehydration/starvation. Finally, some flies die upright without Smurf phenotype, suggesting a possible third mechanism. The frequency of these mechanisms varies between strains and culture conditions, which may affect efficacy of life span interventions.

Bridging Retinal and Cerebral Neurodegeneration: A Focus on Crosslinks between Alzheimer-Perusini's Disease and Retinal Dystrophies

In the early stages of Alzheimer-Perusini's disease (AD), individuals often experience vision-related issues such as color vision impairment, reduced contrast sensitivity, and visual acuity problems. As the disease progresses, there is a connection with glaucoma and age-related macular degeneration (AMD) leading to retinal cell death. The retina's involvement suggests a link with the hippocampus, where most AD forms start. A thinning of the retinal nerve fiber layer (RNFL) due to the loss of retinal ganglion cells (RGCs) is seen as a potential AD diagnostic marker using electroretinography (ERG) and optical coherence tomography (OCT). Amyloid beta fragments (Aβ), found in the eye's vitreous and aqueous humor, are also present in the cerebrospinal fluid (CSF) and accumulate in the retina. Aβ is known to cause tau hyperphosphorylation, leading to its buildup in various retinal layers. However, diseases like AD are now seen as mixed proteinopathies, with deposits of the prion protein (PrP) and α-synuclein found in affected brains and retinas. Glial cells, especially microglial cells, play a crucial role in these diseases, maintaining immunoproteostasis. Studies have shown similarities between retinal and brain microglia in terms of transcription factor expression and morphotypes. All these findings constitute a good start to achieving better comprehension of neurodegeneration in both the eye and the brain. New insights will be able to bring the scientific community closer to specific disease-modifying therapies.

Novel frontiers in neuroprotective therapies in glaucoma: Molecular and clinical aspects

In the last years, neuroprotective therapies have attracted the researcher interests as modern and challenging approach for the treatment of neurodegenerative diseases, aimed at protecting the nervous system from injuries. Glaucoma is a neurodegenerative disease characterized by progressive excavation of the optic nerve head, retinal axonal injury and corresponding vision loss that affects millions of people on a global scale. The molecular basis of the pathology is largely uncharacterized yet, and the therapeutic approaches available do not change the natural course of the disease. Therefore, in accordance with the therapeutic regimens proposed for other neurodegenerative diseases, a modern strategy to treat glaucoma includes prescription of drugs with neuroprotective activities. With respect to this, several preclinical and clinical investigations on a plethora of different drugs are currently ongoing. In this review, first, the conceptualization of the rationale for the adoption of neuroprotective strategies for retina is summarized. Second, the molecular aspects highlighting glaucoma as a neurodegenerative disease are reported. In conclusion, the molecular and pharmacological properties of most promising direct neuroprotective drugs used to delay glaucoma progression are examined, including: neurotrophic factors, NMDA receptor antagonists, the α2-adrenergic agonist, brimonidine, calcium channel blockers, antioxidant agents, nicotinamide and statins.

Iron derived from NCOA4-mediated ferritinophagy causes cellular senescence via the cGAS-STING pathway

Cellular senescence is a hallmark of aging and has been linked to age-related diseases. Age-related macular degeneration (AMD), the most common aging-related retinal disease, is prospectively associated with retinal pigment epithelial (RPE) senescence. However, the mechanism of RPE cell senescence remains unknown. In this study, tert-butyl hydroperoxide (TBH)-induced ARPE-19 cells and D-galactose-treated C57 mice were used to examine the cause of elevated iron in RPE cell senescence. Ferric ammonium citrate (FAC)-treated ARPE-19 cells and C57 mice were used to elucidated the mechanism of iron overload-induced RPE cell senescence. Molecular biology techniques for the assessment of iron metabolism, cellular senescence, autophagy, and mitochondrial function in vivo and in vitro. We found that iron level was increased during the senescence process. Ferritin, a major iron storage protein, is negatively correlated with intracellular iron levels and cell senescence. NCOA4, a cargo receptor for ferritinophagy, mediates degradation of ferritin and contributes to iron accumulation. Besides, we found that iron overload leads to mitochondrial dysfunction. As a result, mitochondrial DNA (mtDNA) is released from damaged mitochondria to cytoplasm. Cytoplasm mtDNA activates the cGAS-STING pathway and promotes inflammatory senescence-associated secretory phenotype (SASP) and cell senescence. Meanwhile, iron chelator Deferoxamine (DFO) significantly rescues RPE senescence and retinopathy induced by FAC or D-gal in mice. Taken together, these findings imply that iron derived from NCOA4-mediated ferritinophagy causes cellular senescence via the cGAS-STING pathway. Inhibiting iron accumulation may represent a promising therapeutic approach for age-related diseases such as AMD.

Glaucoma as a Tauopathy-Is It the Missing Piece in the Glaucoma Puzzle?

Glaucoma is a chronic neurodegenerative disorder affecting the visual system which can result in vision loss and blindness. The pathogenetic mechanisms underlying glaucomatous optic neuropathy are ultimately enigmatic, prompting ongoing investigations into its potential shared pathogenesis with other neurodegenerative neurological disorders. Tauopathies represent a subclass of neurodegenerative diseases characterized by the abnormal deposition of tau protein within the brain and consequent microtubule destabilization. The extended spectrum of tauopathies includes conditions such as frontotemporal dementias, progressive supranuclear palsy, chronic traumatic encephalopathy, and Alzheimer's disease. Notably, recent decades have witnessed emerging documentation of tau inclusion among glaucoma patients, providing substantiation that this ocular disease may similarly manifest features of tauopathies. These studies found that: (i) aggregated tau inclusions are present in the somatodendritic compartment of RGCs in glaucoma patients; (ii) the etiology of the disease may affect tau splicing, phosphorylation, oligomerization, and subcellular localization; and (iii) short interfering RNA against tau, administered intraocularly, significantly decreased retinal tau accumulation and enhanced RGC somas and axon survival, demonstrating a crucial role for tau modifications in ocular hypertension-induced neuronal injury. Here, we examine the most recent evidence surrounding the interplay between tau protein dysregulation and glaucomatous neurodegeneration. We explore the novel perspective of glaucoma as a tau-associated disorder and open avenues for cross-disciplinary collaboration and new treatment strategies.

Potential Retinal Biomarkers in Alzheimer's Disease

Alzheimer's disease (AD) represents a major diagnostic challenge, as early detection is crucial for effective intervention. This review examines the diagnostic challenges facing current AD evaluations and explores the emerging field of retinal alterations as early indicators. Recognizing the potential of the retina as a noninvasive window to the brain, we emphasize the importance of identifying retinal biomarkers in the early stages of AD. However, the examination of AD is not without its challenges, as the similarities shared with other retinal diseases introduce complexity in the search for AD-specific markers. In this review, we address the relevance of using the retina for the early diagnosis of AD and the complex challenges associated with the search for AD-specific retinal biomarkers. We provide a comprehensive overview of the current landscape and highlight avenues for progress in AD diagnosis by retinal examination.

Neodymium acetate as a contrast agent for X-ray phase-contrast tomography

Purpose

X-ray phase-contrast tomography (XPCT) is a non-destructive, three-dimensional imaging modality that provides higher contrast in soft tissue than absorption-based CT and allows one to cover the cytoarchitecture from the centi- and millimeter scale down to the nanoscale. To further increase contrast and resolution of XPCT, for example, in view of addressing connectivity issues in the central nervous system (CNS), metal staining is indispensable. However, currently used protocols, for example, based on osmium and/or uranium are less suited for XPCT, due to an excessive β / δ -ratio. In this work, we explore the suitability of different staining agents for XPCT. Particularly, neodymium(III)-acetate (NdAc), which has recently been proposed as a non-toxic, non-radioactive easy to use alternative contrast agent for uranyl acetate (UAc) in electron microscopy, is investigated. Due to its vertical proximity to UAc in the periodic table, similar chemical but better suited optical properties for phase contrast can be expected.

Approach

Differently stained whole eye samples of wild type mouse and tissues of the CNS are embedded into EPON epoxy resin and scanned using synchrotron as well as with laboratory radiation. Phase retrieval is performed on the projection images, followed by tomographic reconstruction, which enables a quantitative analysis based on the reconstructed electron densities. Segmentation techniques and rendering software is used to visualize structures of interest in the sample.

Results

We show that staining neuronal samples with NdAc enhances contrast, in particular for laboratory scans, allowing high-resolution imaging of biological soft tissue in-house. For the example of murine retina, specifically rods and cones as well as the sclera and the Ganglion cell layer seem to be targeted by the stain. A comparison of electron density by the evaluation of histograms allowed to determine quantitative measures to describe the difference between the examined stains.

Conclusion

The results suggest NdAc to be an effective stain for XPCT, with a preferential binding to anionic groups, such as phosphate and carboxyl groups at cell surfaces, targeting certain layers of the retina with a stronger selectivity compared to other staining agents. Due to the advantageous X-ray optical properties, the stain seems particularly well-suited for phase contrast, with a comparably small number density and an overall superior image quality at laboratory sources.

The impact of Alzheimer's disease risk factors on the pupillary light response

Alzheimer's disease (AD) is the leading cause of dementia, and its prevalence is increasing and is expected to continue to increase over the next few decades. Because of this, there is an urgent requirement to determine a way to diagnose the disease, and to target interventions to delay and ideally stop the onset of symptoms, specifically those impacting cognition and daily livelihood. The pupillary light response (PLR) is controlled by the sympathetic and parasympathetic branches of the autonomic nervous system, and impairments to the pupillary light response (PLR) have been related to AD. However, most of these studies that assess the PLR occur in patients who have already been diagnosed with AD, rather than those who are at a higher risk for the disease but without a diagnosis. Determining whether the PLR is similarly impaired in subjects before an AD diagnosis is made and before cognitive symptoms of the disease begin, is an important step before using the PLR as a diagnostic tool. Specifically, identifying whether the PLR is impaired in specific at-risk groups, considering both genetic and non-genetic risk factors, is imperative. It is possible that the PLR may be impaired in association with some risk factors but not others, potentially indicating different pathways to neurodegeneration that could be distinguished using PLR. In this work, we review the most common genetic and lifestyle-based risk factors for AD and identify established relationships between these risk factors and the PLR. The evidence here shows that many AD risk factors, including traumatic brain injury, ocular and intracranial hypertension, alcohol consumption, depression, and diabetes, are directly related to changes in the PLR. Other risk factors currently lack sufficient literature to make any conclusions relating directly to the PLR but have shown links to impairments in the parasympathetic nervous system; further research should be conducted in these risk factors and their relation to the PLR.

Apolipoprotein ε in Brain and Retinal Neurodegenerative Diseases

Alzheimer's disease (AD) is the most common form of dementia that remains incurable and has become a major medical, social, and economic challenge worldwide. AD is characterized by pathological hallmarks of senile plaques (SP) and neurofibrillary tangles (NFTs) that damage the brain up to twenty years before a clinical diagnosis is made. Interestingly these pathological features have also been observed in retinal neurodegenerative diseases including age related macular degeneration (ARMD), glaucoma and diabetic retinopathy (DR). An association of AD with these diseases has been suggested in epidemiological studies and several common pathological events and risk factors have been identified between these diseases. The E4 allele of Apolipoprotein E (APOE) is a well-established genetic risk factor for late onset AD. The ApoE ε4 allele is also associated with retinal neurodegenerative diseases however in contrast to AD, it is considered protective in AMD, likewise ApoE E2 allele, which is a protective factor for AD, has been implicated as a risk factor for AMD and glaucoma. This review summarizes the evidence on the effects of ApoE in retinal neurodegenerative diseases and discusses the overlapping molecular pathways in AD. The involvement of ApoE in regulating amyloid beta (Aβ) and tau pathology, inflammation, vascular integrity, glucose metabolism and vascular endothelial growth factor (VEGF) signaling is also discussed.

Age-related macular degeneration is associated with probable cerebral amyloid angiopathy: A case-control study

BACKGROUND

Age-related macular degeneration (AMD) is a common retinal degenerative disorder among older individuals. Amyloid deposits, a hallmark of cerebral amyloid angiopathy (CAA), may be involved in the pathogenesis of AMD. Since amyloid deposits may contribute to the development of both AMD and CAA, we hypothesized that patients with AMD have a higher prevalence of CAA.

OBJECTIVE

To compare the prevalence of CAA in patients with or without AMD matched for age.

METHODS

We conducted a cross-sectional, 1:1 age-matched, case-control study of patients ≥40 years of age at the Mayo Clinic who had undergone both retinal optical coherence tomography and brain MRI from 2011 to 2015. Primary dependent variables were probable CAA, superficial siderosis, and lobar and deep cerebral microbleeds (CMBs). The relationship between AMD and CAA was assessed using multivariable logistic regression and was compared across AMD severity (none vs early vs late AMD).

RESULTS

Our analysis included 256 age-matched pairs (AMD 126, no AMD 130). Of those with AMD, 79 (30.9%) had early AMD and 47 (19.4%) had late AMD. The mean age was 75±9 years, and there was no significant difference in vascular risk factors between groups. Patients with AMD had a higher prevalence of CAA (16.7% vs 10.0%, p=0.116) and superficial siderosis (15.1% vs 6.2%, p=0.020), but not deep CMB (5.2% vs 6.2%, p=0.426), compared to those without AMD. After adjusting for covariates, having late AMD was associated with increased odds of CAA (OR 2.83, 95% CI 1.10-7.27, p=0.031) and superficial siderosis (OR 3.40, 95%CI 1.20-9.65, p=0.022), but not deep CMB (OR 0.7, 95%CI 0.14-3.51, p=0.669).

CONCLUSIONS

AMD was associated with CAA and superficial siderosis but not deep CMB, consistent with the hypothesis that amyloid deposits play a role in the development of AMD. Prospective studies are needed to determine if features of AMD may serve as biomarkers for the early diagnosis of CAA.

Alzheimer's disease-associated complement gene variants influence plasma complement protein levels

BACKGROUND

Alzheimer's disease (AD) has been associated with immune dysregulation in biomarker and genome-wide association studies (GWAS). GWAS hits include the genes encoding complement regulators clusterin (CLU) and complement receptor 1 (CR1), recognised as key players in AD pathology, and complement proteins have been proposed as biomarkers.

MAIN BODY

To address whether changes in plasma complement protein levels in AD relate to AD-associated complement gene variants we first measured relevant plasma complement proteins (clusterin, C1q, C1s, CR1, factor H) in a large cohort comprising early onset AD (EOAD; n = 912), late onset AD (LOAD; n = 492) and control (n = 504) donors. Clusterin and C1q were significantly increased (p < 0.001) and sCR1 and factor H reduced (p < 0.01) in AD plasma versus controls. ROC analyses were performed to assess utility of the measured complement biomarkers, alone or in combination with amyloid beta, in predicting AD. C1q was the most predictive single complement biomarker (AUC 0.655 LOAD, 0.601 EOAD); combining C1q with other complement or neurodegeneration makers through stepAIC-informed models improved predictive values slightly. Effects of GWS SNPs (rs6656401, rs6691117 in CR1; rs11136000, rs9331888 in CLU; rs3919533 in C1S) on protein concentrations were assessed by comparing protein levels in carriers of the minor vs major allele. To identify new associations between SNPs and changes in plasma protein levels, we performed a GWAS combining genotyping data in the cohort with complement protein levels as endophenotype. SNPs in CR1 (rs6656401), C1S (rs3919533) and CFH (rs6664877) reached significance and influenced plasma levels of the corresponding protein, whereas SNPs in CLU did not influence clusterin levels.

CONCLUSION

Complement dysregulation is evident in AD and may contribute to pathology. AD-associated SNPs in CR1, C1S and CFH impact plasma levels of the encoded proteins, suggesting a mechanism for impact on disease risk.

β-secretase 1 overexpression by AAV-mediated gene delivery prevents retina degeneration in a mouse model of age-related macular degeneration

We reported previously that β-site amyloid precursor protein cleaving enzyme (BACE1) is strongly expressed in the normal retina and that BACE1-/- mice develop pathological phenotypes associated with age-related macular degeneration (AMD). BACE1 expression is increased within the neural retina and retinal pigment epithelium (RPE) in AMD donor eyes suggesting that increased BACE1 is compensatory. We observed that AAV-mediated BACE1 overexpression in the RPE was maintained up to 6 months after AAV1-BACE1 administration. No significant changes in normal mouse visual function or retinal morphology were observed with low-dose vector while the high-dose vector demonstrated some early pathology which regressed with time. No increase in β-amyloid was observed. BACE1 overexpression in the RPE of the superoxide dismutase 2 knockdown (SOD2 KD) mouse, which exhibits an AMD-like phenotype, prevented loss of retinal function and retinal pathology, and this was sustained out to 6 months. Furthermore, BACE1 overexpression was able to inhibit oxidative stress, microglial changes, and loss of RPE tight junction integrity (all features of AMD) in SOD2 KD mice. In conclusion, BACE1 plays a key role in retina/RPE homeostasis, and BACE1 overexpression offers a novel therapeutic target in the treatment of AMD.

Imaging Amyloid and Tau in the Retina: Current Research and Future Directions

BACKGROUND

The retina is a key focus in the search for biomarkers of Alzheimer's disease (AD) because of its accessibility and shared development with the brain. The pathological hallmarks of AD, amyloid beta (Aβ), and hyperphosphorylated tau (pTau) have been identified in the retina, although histopathologic findings have been mixed. Several imaging-based approaches have been developed to detect retinal AD pathology in vivo. Here, we review the research related to imaging AD-related pathology in the retina and implications for future biomarker research.

EVIDENCE ACQUISITION

Electronic searches of published literature were conducted using PubMed and Google Scholar.

RESULTS

Curcumin fluorescence and hyperspectral imaging are both promising methods for detecting retinal Aβ, although both require validation in larger cohorts. Challenges remain in distinguishing curcumin-labeled Aβ from background fluorescence and standardization of dosing and quantification methods. Hyperspectral imaging is limited by confounding signals from other retinal features and variability in reflectance spectra between individuals. To date, evidence of tau aggregation in the retina is limited to histopathologic studies. New avenues of research are on the horizon, including near-infrared fluorescence imaging, novel Aβ labeling techniques, and small molecule retinal tau tracers. Artificial intelligence (AI) approaches, including machine learning models and deep learning-based image analysis, are active areas of investigation.

CONCLUSIONS

Although the histopathological evidence seems promising, methods for imaging retinal Aβ require further validation, and in vivo imaging of retinal tau remains elusive. AI approaches may hold the greatest promise for the discovery of a characteristic retinal imaging profile of AD. Elucidating the role of Aβ and pTau in the retina will provide key insights into the complex processes involved in aging and in neurodegenerative disease.