Nerve Growth Factor-Based Therapy in Alzheimer's Disease and Age-Related Macular Degeneration

Unscrambling the cellular and molecular threads of Neuroplasticity: Insights into Alzheimer's disease pathogenesis

Alzheimer's disease (AD) is predominantly the most recurring and devastating neurological condition among the elderly population, characterized by the accumulation of amyloid-β (Aβ) and phosphorylated tau proteins, and is accompanied by progressive decline of learning and memory. Due to its complex and multifactorial etiology, a wide variety of therapeutic interventions have been developed. Despite constant advancements in the field, effective treatments that ameliorate the severity of Alzheimer's symptoms or cease their progression are still insufficient. Mounting evidence suggests that synaptic dysfunction could be an essential component of AD pathogenesis as synapse signaling is impaired in the aging brain, which contributes to synaptic decline. Therefore, improving neuroplasticity such as synaptic plasticity or neurogenesis could be a promising therapeutic approach for alleviating the effects of AD. This article reviews the cellular and molecular threads of neuroplasticity as well as targets that restore neuronal survival and plasticity to provide functional recoveries, including receptors, downstream signaling pathways, ion channels, transporters, enzymes, and neurotrophic factors.

Liposomal topical drug administration surpasses alternative methods in glaucoma therapeutics: a novel paradigm for enhanced treatment

OBJECTIVES

Glaucoma is a leading cause of permanent blindness. Despite therapeutic advancements, glaucoma management remains challenging due to limitations of conventional drug delivery, primarily topical eye drops, resulting in suboptimal outcomes and a global surge in cases. To address these issues, liposomal drug delivery has emerged as a promising approach.

KEY FINDINGS

This review explores the potential of liposomal-based medications, with a particular focus on topical administration as a superior alternative to enhance therapeutic efficacy and improve patient compliance compared to existing treatments. This writing delves into the therapeutic prospects of liposomal formulations across different administration routes, as evidenced by ongoing clinical trials. Additionally, critical aspects of liposomal production and market strategies are discussed herein.

SUMMARY

By overcoming ocular barriers and optimizing drug delivery, liposomal topical administration holds the key to significantly improving glaucoma treatment outcomes.

Nerve growth factor signaling tunes axon maintenance protein abundance and kinetics of Wallerian degeneration

Neurotrophic factors are critical for establishing functional connectivity in the nervous system and sustaining neuronal survival through adulthood. As the first neurotrophic factor purified, nerve growth factor (NGF) is extensively studied for its prolific role in axon outgrowth, pruning, and survival. Applying NGF to diseased neuronal tissue is an exciting therapeutic option and understanding how NGF regulates local axon susceptibility to pathological degeneration is critical for exploiting its full potential. Our study identifies surprising connections between NGF signaling and proteostasis of axon maintenance factors. NGF deprivation increases Nmnat2 and Stmn2 protein levels in axon segments with a corresponding delay in Wallerian degeneration. Conversely, acute NGF stimulation reduces local abundance of these axon maintenance factors and accelerates Wallerian degeneration. Pharmacological studies implicate phospholipase C as the key effector in tropomyosin-related kinase A (TrkA) activation, which drives degradation of palmitoylated Stmn2. While seemingly opposed to neuroprotective activities well-documented for NGF, downregulating Nmnat2 and Stmn2 favors axonal outgrowth over transient hypersusceptibility to Sarm1-dependent degeneration. This new facet of NGF biology has important implications for axonal remodeling during development and sustained integrity through adulthood.

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.

Association of a multiplex immune marker panel with incident cognitive impairment and dementia: The Northern Manhattan Study

Objective

To determine whether a panel of immune markers adds significant information to known correlates of risk of dementia and cognitive impairment.

Background

The impact of immune mechanisms on dementia risk is incompletely characterized.

Design/methods

A subsample of the Northern Manhattan Study, a prospective cohort study in the racially/ethnically diverse population of New York City, underwent comprehensive neuropsychological testing up to three times, at approximately 5-year intervals. Cognitive outcomes were adjudicated as no cognitive impairment, mild cognitive impairment (MCI), or dementia. Immune markers were assessed using a multiplex immunoassay on plasma samples collected at the time of the first neuropsychological test. Least absolute shrinkage and selection operator (LASSO) techniques were employed to yield a panel of immune markers linearly related to the outcome of dementia/MCI vs. no cognitive impairment. Nested logistic regression models were run to determine the independent association of the immune marker panel with dementia/MCI after adjusting for other predictors of risk.

Results

Among 1179 participants (mean age 70.0 ± 8.9 years, 60% women, 68% Hispanic), immune markers improved model fit above demographic and vascular risk factors (p-value for likelihood ratio test <0.0001) as correlates of MCI/dementia. Individual immune markers found to be associated with dementia/MCI were C-X-C Motif Chemokine Ligand 9 (CXCL9) and C-C Motif Chemokine Ligand 2 (CCL2). The effect of the immune markers was comparable to traditional risk factors, with CCL2 (per SD) having almost the same effect as 1 year of aging and CXCL9 (per SD) showing approximately twice this magnitude.

Conclusion

Immune markers are associated with cognitive decline and dementia outcomes in a multi-ethnic cohort. More work is needed to further characterize these associations and determine therapeutic strategies. (Funded by the National Institute of Health/National Institute of Neurological Disorders and Stroke; grant number R01 29993 (Sacco/Elkind)).

Single-cell spatial transcriptomics reveals distinct patterns of dysregulation in non-neuronal and neuronal cells induced by the Trem2R47H Alzheimer's risk gene mutation

The R47H missense mutation of the TREM2 gene is a known risk factor for development of Alzheimer's Disease. In this study, we analyze the impact of the Trem2R47H mutation on specific cell types in multiple cortical and subcortical brain regions in the context of wild-type and 5xFAD mouse background. We profile 19 mouse brain sections consisting of wild-type, Trem2R47H, 5xFAD and Trem2R47H; 5xFAD genotypes using MERFISH spatial transcriptomics, a technique that enables subcellular profiling of spatial gene expression. Spatial transcriptomics and neuropathology data are analyzed using our custom pipeline to identify plaque and Trem2R47H-induced transcriptomic dysregulation. We initially analyze cell type-specific transcriptomic alterations induced by plaque proximity. Next, we analyze spatial distributions of disease associated microglia and astrocytes, and how they vary between 5xFAD and Trem2R47H; 5xFAD mouse models. Finally, we analyze the impact of the Trem2R47H mutation on neuronal transcriptomes. The Trem2R47H mutation induces consistent upregulation of Bdnf and Ntrk2 across many cortical excitatory neuron types, independent of amyloid pathology. Spatial investigation of genotype enriched subclusters identified spatially localized neuronal subpopulations reduced in 5xFAD and Trem2R47H; 5xFAD mice. Overall, our MERFISH spatial transcriptomics analysis identifies glial and neuronal transcriptomic alterations induced independently by 5xFAD and Trem2R47H mutations, impacting inflammatory responses in microglia and astrocytes, and activity and BDNF signaling in neurons.

Nerve Growth Factor Signaling Tunes Axon Maintenance Protein Abundance and Kinetics of Wallerian Degeneration

Neurotrophic factors are critical for establishing functional connectivity in the nervous system and sustaining neuronal survival through adulthood. As the first neurotrophic factor purified, nerve growth factor (NGF) is extensively studied for its prolific role in axon outgrowth, pruning, and survival. Applying NGF to diseased neuronal tissue is an exciting therapeutic option and understanding how NGF regulates local axon susceptibility to pathological degeneration is critical for exploiting its full potential. Our study identifies surprising connections between NGF signaling and proteostasis of axon maintenance factors. NGF deprivation increases Nmnat2 and Stmn2 protein levels in axon segments with a corresponding delay in Wallerian degeneration. Conversely, acute NGF stimulation reduces local abundance of these axon maintenance factors and accelerates Wallerian degeneration. Pharmacological studies implicate phospholipase C as the key effector in TrkA activation, which drives degradation of palmitoylated Stmn2. While seemingly opposed to neuroprotective activities well-documented for NGF, downregulating Nmnat2 and Stmn2 favors axonal outgrowth over transient hyper-susceptibility to Sarm1-dependent degeneration. This new facet of NGF biology has important implications for axonal remodeling during development and sustained integrity through adulthood.

Activation of the Gut-Brain Interaction by Urolithin A and Its Molecular Basis

Background: Urolithin A (Uro-A), a type of polyphenol derived from pomegranate, is known to improve memory function when ingested, in addition to its direct effect on the skin epidermal cells through the activation of longevity gene SIRT1. However, the molI ecular mechanism by which orally ingested Uro-A inhibits cognitive decline via the intestine remains unexplored. Objectives: This study aimed to evaluate the role of Uro-A in improving cognitive function via improved intestinal function and the effect of Uro-A on the inflammation levels and gene expression in hippocampus. Methods: Research to clarify the molecular basis of the functionality of Uro-A was also conducted. Results: The results demonstrated that Uro-A suppressed age-related memory impairment in Aged mice (C57BL/6J Jcl, male, 83 weeks old) by reducing inflammation and altering hippocampal gene expression. Furthermore, exosomes derived from intestinal cells treated with Uro-A and from the serum of Aged mice fed with Uro-A both activated neuronal cells, suggesting that exosomes are promising candidates as mediators of the Uro-A-induced activation of gut-brain interactions. Additionally, neurotrophic factors secreted from intestinal cells may contribute to the Uro-A-induced activation of gut-brain interactions. Conclusions: This study suggests that Uro-A suppresses age-related cognitive decline and that exosomes and other secreted factors may contribute to the activation of the gut-brain interaction. These findings provide new insights into the therapeutic potential of Uro-A for cognitive health.

NLRP3 and autophagy in retinal ganglion cell inflammation in age-related macular degeneration: potential therapeutic implications

Retinal degenerative diseases were a large group of diseases characterized by the primary death of retinal ganglion cells (RGCs). Recent studies had shown an interaction between autophagy and nucleotide-binding oligomerization domain-like receptor 3 (NLRP3) inflammasomes, which may affect RGCs in retinal degenerative diseases. The NLRP3 inflammasome was a protein complex that, upon activation, produces caspase-1, mediating the apoptosis of retinal cells and promoting the occurrence and development of retinal degenerative diseases. Upregulated autophagy could inhibit NLRP3 inflammasome activation, while inhibited autophagy can promote NLRP3 inflammasome activation, which leaded to the accelerated emergence of drusen and lipofuscin deposition under the neurosensory retina. The activated NLRP3 inflammasome could further inhibit autophagy, thus forming a vicious cycle that accelerated the damage and death of RGCs. This review discussed the relationship between NLRP3 inflammasome and autophagy and its effects on RGCs in age-related macular degeneration, providing a new perspective and direction for the treatment of retinal diseases.

Astrocytic NMDA Receptors

Astrocytic NMDA receptors (NMDARs) are heterotetramers, whose expression and properties are largely determined by their subunit composition. Astrocytic NMDARs are characterized by a low sensitivity to magnesium ions and low calcium conductivity. Their activation plays an important role in the regulation of various intracellular processes, such as gene expression and mitochondrial function. Astrocytic NMDARs are involved in calcium signaling in astrocytes and can act through the ionotropic and metabotropic pathways. Astrocytic NMDARs participate in the interactions of the neuroglia, thus affecting synaptic plasticity. They are also engaged in the astrocyte-vascular interactions and contribute to the regulation of vascular tone. Astrocytic NMDARs are involved in various pathologies, such as ischemia and hyperammonemia, and their blockade prevents negative changes in astrocytes during these diseases.

BDNF- and VEGF-Responsive Stimulus to an NGF Mimic Cyclic Peptide with Copper Ionophore Capability and Ctr1/CCS-Driven Signaling

Neurotrophins are a family of growth factors that play a key role in the development and regulation of the functioning of the central nervous system. Their use as drugs is made difficult by their poor stability, cellular permeability, and side effects. Continuing our effort to use peptides that mimic the neurotrophic growth factor (NGF), the family model protein, and specifically the N-terminus of the protein, here we report on the spectroscopic characterization and resistance to hydrolysis of the 14-membered cyclic peptide reproducing the N-terminus sequence (SSSHPIFHRGEFSV (c-NGF(1-14)). Far-UV CD spectra and a computational study show that this peptide has a rigid conformation and left-handed chirality typical of polyproline II that favors its interaction with the D5 domain of the NGF receptor TrkA. c-NGF(1-14) is able to bind Cu2+ with good affinity; the resulting complexes have been characterized by potentiometric and spectroscopic measurements. Experiments on PC12 cells show that c-NGF(1-14) acts as an ionophore, influencing the degree and the localization of both the membrane transporter (Ctr1) and the copper intracellular transporter (CCS). c-NGF(1-14) induces PC12 differentiation, mimics the protein in TrkA phosphorylation, and activates the kinase cascade, inducing Erk1/2 phosphorylation. c-NGF(1-14) biological activities are enhanced when the peptide interacts with Cu2+ even with the submicromolar quantities present in the culture media as demonstrated by ICP-OES measurements. Finally, c-NGF(1-14) and Cu2+ concur to activate the cAMP response element-binding protein CREB that, in turn, induces the brain-derived neurotrophic factor (BDNF) and the vascular endothelial growth factor (VEGF) release.

Advances and Challenges in Gene Therapy for Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline, memory loss, and behavioral impairments. Despite extensive research efforts, effective treatment options for AD remain limited. Recently, gene therapy has emerged as a promising avenue for targeted intervention in the pathogenesis of AD. This review will provide an overview of clinical and preclinical studies where gene therapy techniques have been utilized in the context of AD, highlighting their potential as novel therapeutic strategies. While challenges remain, ongoing research and technological advancement continue to enhance the potential of gene therapy as a targeted and personalized therapeutic approach for AD.

Single cell spatial transcriptomics reveals distinct patterns of dysregulation in non-neuronal and neuronal cells induced by the Trem2R47H Alzheimer's risk gene mutation

INTRODUCTION

The R47H missense mutation of the TREM2 gene is a strong risk factor for development of Alzheimer's Disease. We investigate cell-type-specific spatial transcriptomic changes induced by the Trem2R47H mutation to determine the impacts of this mutation on transcriptional dysregulation.

METHODS

We profiled 15 mouse brain sections consisting of wild-type, Trem2R47H, 5xFAD and Trem2R47H; 5xFAD genotypes using MERFISH spatial transcriptomics. Single-cell spatial transcriptomics and neuropathology data were analyzed using our custom pipeline to identify plaque and Trem2R47H induced transcriptomic dysregulation.

RESULTS

The Trem2R47H mutation induced consistent upregulation of Bdnf and Ntrk2 across many cortical excitatory neuron types, independent of amyloid pathology. Spatial investigation of genotype enriched subclusters identified spatially localized neuronal subpopulations reduced in 5xFAD and Trem2R47H; 5xFAD mice.

CONCLUSION

Spatial transcriptomics analysis identifies glial and neuronal transcriptomic alterations induced independently by 5xFAD and Trem2R47H mutations, impacting inflammatory responses in microglia and astrocytes, and activity and BDNF signaling in neurons.

Alzheimer's disease: The role of proteins in formation, mechanisms, and new therapeutic approaches

Alzheimer's disease (AD) is a progressive neurological disorder that affects the central nervous system (CNS), leading to memory and cognitive decline. In AD, the brain experiences three main structural changes: a significant decrease in the quantity of neurons, the development of neurofibrillary tangles (NFT) composed of hyperphosphorylated tau protein, and the formation of amyloid beta (Aβ) or senile plaques, which are protein deposits found outside cells and surrounded by dystrophic neurites. Genetic studies have identified four genes associated with autosomal dominant or familial early-onset AD (FAD): amyloid precursor protein (APP), presenilin 1 (PS1), presenilin 2 (PS2), and apolipoprotein E (ApoE). The formation of plaques primarily involves the accumulation of Aβ, which can be influenced by mutations in APP, PS1, PS2, or ApoE genes. Mutations in the APP and presenilin (PS) proteins can cause an increased amyloid β peptides production, especially the further form of amyloidogenic known as Aβ42. Apart from genetic factors, environmental factors such as cytokines and neurotoxins may also have a significant impact on the development and progression of AD by influencing the formation of amyloid plaques and intracellular tangles. Exploring the causes and implications of protein aggregation in the brain could lead to innovative therapeutic approaches. Some promising therapy strategies that have reached the clinical stage include using acetylcholinesterase inhibitors, estrogen, nonsteroidal anti-inflammatory drugs (NSAIDs), antioxidants, and antiapoptotic agents. The most hopeful therapeutic strategies involve inhibiting activity of secretase and preventing the β-amyloid oligomers and fibrils formation, which are associated with the β-amyloid fibrils accumulation in AD. Additionally, immunotherapy development holds promise as a progressive therapeutic approach for treatment of AD. Recently, the two primary categories of brain stimulation techniques that have been studied for the treatment of AD are invasive brain stimulation (IBS) and non-invasive brain stimulation (NIBS). In this article, the amyloid proteins that play a significant role in the AD formation, the mechanism of disease formation as well as new drugs utilized to treat of AD will be reviewed.

Efficacy of a Spearmint (Mentha spicata L.) Extract as Nutritional Support in a Rat Model of Hypertensive Glaucoma

Purpose

Glaucoma is an eye-brain axis disorder characterized by loss of retinal ganglion cells (RGCs). Although the role of intraocular pressure (IOP) elevation in glaucoma has been established, the reduction of oxidative stress and inflammation has emerged as a promising target for neuronal tissue-supporting glaucoma management. Therefore, we evaluated the effect of a proprietary spearmint extract (SPE) on RGC density, activity, and neuronal health markers in a rat model of hypertensive glaucoma.

Methods

Animals were divided in four groups: untreated healthy control and three glaucomatous groups receiving orally administered vehicle, SPE-low dose, or SPE-high dose for 28 days. Ocular hypertension was induced through intracameral injection of methylcellulose at day 15. At day 29, rats underwent electroretinogram (ERG) recordings, and retinas were analyzed for RGC density and markers of neural trophism, oxidative stress, and inflammation.

Results

SPE exerted dose-dependent response benefits on all markers except for IOP elevation. SPE significantly improved RGC-related ERG responses, cell density, neurotrophins, oxidative stress, and inflammation markers. Also, in SPE-high rats, most of the parameters were not statistically different from those of healthy controls.

Conclusions

SPE, a plant-based, polyphenolic extract, could be an effective nutritional support for neuronal tissues.

Translational Relevance

These results suggest that SPE not only may be a complementary approach in support to hypotensive treatments for the management of glaucoma but may also serve as nutritional support in other ocular conditions where antioxidant, anti-inflammatory, and neuroprotective mechanism are often disrupted.

Improvement of Cognitive Function by Fermented Panax ginseng C.A. Meyer Berries Extracts in an AF64A-Induced Memory Deficit Model

This study investigated the potential therapeutic properties of fermented ginseng berry extract (GBE) for Alzheimer's disease (AD). Fermented GBE was examined for its ginsenoside content and physiological properties, which have been suggested to have neuroprotective effects and improve cognitive function. The results showed that fermented GBE contains high levels of major active ginsenosides and exhibits antioxidant and acetylcholinesterase inhibitory activities. Post-fermented GBE demonstrated therapeutic potential in AF64A-induced damaged neural stem cells and an animal model of AD. These findings suggest that fermented GBE may hold promise as a candidate for developing new therapeutic interventions for memory deficits and cognitive disorders associated with AD and other neurodegenerative conditions. However, further studies are needed to evaluate the safety, tolerability, and efficacy of fermented GBE in human subjects and to determine its clinical applications. In conclusion, our study provides evidence that fermented GBE has potential as a natural product for the prevention and treatment of AD. The high levels of active ginsenosides and antioxidant and acetylcholinesterase inhibitory activities of fermented GBE suggest that it may be a promising therapeutic agent for improving cognitive function and reducing neurodegeneration.

An update on stem cell and stem cell-derived extracellular vesicle-based therapy in the management of Alzheimer's disease

Globally, neurological diseases pose a major burden to healthcare professionals in terms of the management and prevention of the disorder. Among neurological diseases, Alzheimer's disease (AD) accounts for 50%-70% of dementia and is the fifth leading cause of mortality worldwide. AD is a progressive, degenerative neurological disease, with the loss of neurons and synapses in the cerebral cortex and subcortical regions. The management of AD remains a debate among physicians as no standard and specific "disease-modifying" modality is available. The concept of 'Regenerative Medicine' is aimed at regenerating the degenerated neural tissues to reverse the pathology in AD. Genetically modified engineered stem cells modify the course of AD after transplantation into the brain. Extracellular vesicles (EVs) are an emerging new approach in cell communication that involves the transfer of cellular materials from parental cells to recipient cells, resulting in changes at the molecular and signaling levels in the recipient cells. EVs are a type of vesicle that can be transported between cells. Many have proposed that EVs produced from mesenchymal stem cells (MSCs) may have therapeutic promise in the treatment of AD. The biology of AD, as well as the potential applications of stem cells and their derived EVs-based therapy, were explored in this paper.

Adsorption of the rhNGF Protein on Polypropylene with Different Grades of Copolymerization

The surface properties of drug containers should reduce the adsorption of the drug and avoid packaging surface/drug interactions, especially in the case of biologically-derived products. Here, we developed a multi-technique approach that combined Differential Scanning Calorimetry (DSC), Atomic Force Microscopy (AFM), Contact Angle (CA), Quartz Crystal Microbalance with Dissipation monitoring (QCM-D), and X-ray Photoemission Spectroscopy (XPS) to investigate the interactions of rhNGF on different pharma grade polymeric materials. Polypropylene (PP)/polyethylene (PE) copolymers and PP homopolymers, both as spin-coated films and injected molded samples, were evaluated for their degree of crystallinity and adsorption of protein. Our analyses showed that copolymers are characterized by a lower degree of crystallinity and lower roughness compared to PP homopolymers. In line with this, PP/PE copolymers also show higher contact angle values, indicating a lower surface wettability for the rhNGF solution on copolymers than PP homopolymers. Thus, we demonstrated that the chemical composition of the polymeric material and, in turn, its surface roughness determine the interaction with the protein and identified that copolymers may offer an advantage in terms of protein interaction/adsorption. The combined QCM-D and XPS data indicated that protein adsorption is a self-limiting process that passivates the surface after the deposition of roughly one molecular layer, preventing any further protein adsorption in the long term.

Age-Related Macular Degeneration and Its Association With Neurodegenerative Disorders

Age-related macular degeneration (AMD) is a highly prevalent macular condition that primarily affects the older population. It is the primary cause of blindness amongst the elderly population. It is an inflammatory disease that characteristically shows choroidal neovascularization and geographic atrophy. The exact pathomechanism of developing AMD is not known. However, certain factors such as increased age, smoking, genetic factors and certain environmental factors are usually associated with the development of the disease. AMD also involves oxidative stress-mediated destruction of retinal pigment epithelial cells and, consequently, that of retinal photoreceptors. Alzheimer's disease (AD) is a degenerative disorder involving the nervous system that usually affects people aged 65 and over. Both AMD and AD are age-related, degenerative conditions that have several similarities and share many of the same risk factors such as vascular conditions like arteriosclerosis, high blood pressure and obesity. It is believed that the early emergence of the clinical manifestations of AMD and AD may also be significantly influenced by oxidative stress and genetic polymorphism in complement factor H. A common pathogenic pathway between AD and AMD is quite likely. Amyloid-β is an aberrant protein that accumulates within the brains of Alzheimer's patients and appears as plaques on magnetic resonance imaging (MRI). These plaques are a pathognomonic sign of Alzheimer's disease. Similar to this, amyloid-β deposits are reported to build up beneath the retina of AMD patients, which appear as tiny clusters of protein-lipid substances known as drusen. It has also been found that individuals suffering from AMD exhibit an increased chance of developing AD than those with no AMD.

Morphological and biomolecular targets in retina and vitreous from Reelin-deficient mice (Reeler): Potential implications for age-related macular degeneration in Alzheimer’s dementia

The neurosensory retina is an outgrowth of the Central Nervous System (CNS), and the eye is considered “a window to the brain.” Reelin glycoprotein is directly involved in neurodevelopment, in synaptic plasticity, learning and memory. Consequently, abnormal Reelin signaling has been associated with brain neurodegeneration but its contributing role in ocular degeneration is still poorly explored. To this aim, experimental procedures were assayed on vitreous or retinas obtained from Reeler mice (knockout for Reelin protein) at different postnatal days (p) p14, p21 and p28. At p28, a significant increase in the expression of Amyloid Precursor Protein (APP) and its amyloidogenic peptide (Aβ1-42 along with truncated tau fragment (i.e., NH2htau)- three pathological hallmarks of Alzheimer’s disease (AD)-were found in Reeler mice when compared to their age-matched wild-type controls. Likewise, several inflammatory mediators, such as Interleukins, or crucial biomarkers of oxidative stress were also found to be upregulated in Reeler mice by using different techniques such as ELLA assay, microchip array or real-time PCR. Taken together, these findings suggest that a dysfunctional Reelin signaling enables the expression of key pathological features which are classically associated with AD neurodegenerative processes. Thus, this work suggests that Reeler mouse might be a suitable animal model to study not only the pathophysiology of developmental processes but also several neurodegenerative diseases, such as AD and Age-related Macular Degeneration (AMD), characterized by accumulation of APP and/or Aβ1-42, NH2htau and inflammatory markers.

Amyloidogenesis and Neurotrophic Dysfunction in Alzheimer’s Disease: Do They have a Common Regulating Pathway?

The amyloid cascade hypothesis has predominately been used to describe the pathogenesis of Alzheimer’s disease (AD) for decades, as Aβ oligomers are thought to be the prime cause of AD. Meanwhile, the neurotrophic factor hypothesis has also been proposed for decades. Accumulating evidence states that the amyloidogenic process and neurotrophic dysfunction are mutually influenced and may coincidently cause the onset and progress of AD. Meanwhile, there are intracellular regulators participating both in the amyloidogenic process and neurotrophic pathways, which might be the common original causes of amyloidogenesis and neurotrophic dysfunction. In this review, the current understanding regarding the role of neurotrophic dysfunction and the amyloidogenic process in AD pathology is briefly summarized. The mutual influence of these two pathogenesis pathways and their potential common causal pathway are further discussed. Therapeutic strategies targeting the common pathways to simultaneously prevent amyloidogenesis and neurotrophic dysfunction might be anticipated for the disease-modifying treatment of AD.

Microglia Impairs Proliferation and Induces Senescence In-Vitro in NGF Releasing Cells Used in Encapsulated Cell Biodelivery for Alzheimer's Disease Therapy

There is no cure yet available for Alzheimer's disease (AD). We recently optimized encapsulated cell biodelivery (ECB) devices releasing human mature nerve growth factor (hmNGF), termed ECB-NGF, to the basal forebrain of AD patients. The ECB-NGF delivery resulted in increased CSF cholinergic markers, improved glucose metabolism, and positive effects on cognition in AD patients. However, some ECB-NGF implants showed altered hmNGF release post-explantation. To optimize the ECB-NGF platform for future therapeutic purposes, we initiated in-vitro optimization studies by exposing ECB-NGF devices to physiological factors present within the AD brain. We report here that microglia cells can impair hmNGF release from ECB-NGF devices in-vitro, which can be reversed by transferring the devices to fresh culture medium. Further, we exposed the hmNGF secreting human ARPE-19 cell line (NGC0211) to microglia (HMC3) conditioned medium (MCM; untreated or treated with IL-1β/IFNγ/Aβ₄₀/Aβ₄₂), and evaluated biochemical stress markers (ROS, GSH, ΔΨ_m, and Alamar Blue assay), cell death indicators (Annexin-V/PI), cell proliferation (CFSE retention and Ki67) and senescence markers (SA-β-gal) in NGC0211 cells. MCMs from activated microglia reduced cell proliferation and induced cell senescence in NGC0211 cells, which otherwise resist biochemical alterations and cell death. These data indicate a critical but reversible impact of activated microglia on NGC0211 cells.

Physical Activity Rewires the Human Brain against Neurodegeneration

Physical activity may offset cognitive decline and dementia, but the molecular mechanisms by which it promotes neuroprotection remain elusive. In the absence of disease-modifying therapies, understanding the molecular effects of physical activity in the brain may be useful for identifying novel targets for disease management. Here we employed several bioinformatic methods to dissect the molecular underpinnings of physical activity in brain health. Network analysis identified 'switch genes' associated with drastic hippocampal transcriptional changes in aged cognitively intact individuals. Switch genes are key genes associated with dramatic transcriptional changes and thus may play a fundamental role in disease pathogenesis. Switch genes are associated with protein processing pathways and the metabolic control of glucose, lipids, and fatty acids. Correlation analysis showed that transcriptional patterns associated with physical activity significantly overlapped and negatively correlated with those of neurodegenerative diseases. Functional analysis revealed that physical activity might confer neuroprotection in Alzheimer's (AD), Parkinson's (PD), and Huntington's (HD) diseases via the upregulation of synaptic signaling pathways. In contrast, in frontotemporal dementia (FTD) its effects are mediated by restoring mitochondrial function and energy precursors. Additionally, physical activity is associated with the downregulation of genes involved in inflammation in AD, neurogenesis in FTD, regulation of growth and transcriptional repression in PD, and glial cell differentiation in HD. Collectively, these findings suggest that physical activity directs transcriptional changes in the brain through different pathways across the broad spectrum of neurodegenerative diseases. These results provide new evidence on the unique and shared mechanisms between physical activity and neurodegenerative diseases.