Rescue of a lysosomal storage disorder caused by Grn loss of function with a brain penetrant progranulin biologic.

GRN mutations cause frontotemporal dementia (GRN-FTD) due to deficiency in progranulin (PGRN), a lysosomal and secreted protein with unclear function. Here, we found that Grn-/- mice exhibit a global deficiency in bis(monoacylglycero)phosphate (BMP), an endolysosomal phospholipid we identified as a pH-dependent PGRN interactor as well as a redox-sensitive enhancer of lysosomal proteolysis and lipolysis. Grn-/- brains also showed an age-dependent, secondary storage of glucocerebrosidase substrate glucosylsphingosine. We investigated a protein replacement strategy by engineering protein transport vehicle (PTV):PGRN-a recombinant protein linking PGRN to a modified Fc domain that binds human transferrin receptor for enhanced CNS biodistribution. PTV:PGRN rescued various Grn-/- phenotypes in primary murine macrophages and human iPSC-derived microglia, including oxidative stress, lysosomal dysfunction, and endomembrane damage. Peripherally delivered PTV:PGRN corrected levels of BMP, glucosylsphingosine, and disease pathology in Grn-/- CNS, including microgliosis, lipofuscinosis, and neuronal damage. PTV:PGRN thus represents a potential biotherapeutic for GRN-FTD.

Loss of TAX1BP1-Directed Autophagy Results in Protein Aggregate Accumulation in the Brain.

Protein aggregates disrupt cellular homeostasis, causing toxicity linked to neurodegeneration. Selective autophagic elimination of aggregates is critical to protein quality control, but how aggregates are selectively targeted for degradation is unclear. We compared the requirements for autophagy receptor proteins: OPTN, NBR1, p62, NDP52, and TAX1BP1 in clearance of proteotoxic aggregates. Endogenous TAX1BP1 is recruited to and required for the clearance of stress-induced aggregates, whereas ectopic expression of TAX1BP1 increases clearance through autophagy, promoting viability of human induced pluripotent stem cell-derived neurons. In contrast, TAX1BP1 depletion sensitizes cells to several forms of aggregate-induced proteotoxicity. Furthermore, TAX1BP1 is more specifically expressed in the brain compared to other autophagy receptor proteins. In vivo, loss of TAX1BP1 results in accumulation of high molecular weight ubiquitin conjugates and premature lipofuscin accumulation in brains of young TAX1BP1 knockout mice. TAX1BP1 mediates clearance of a broad range of cytotoxic proteins indicating therapeutic potential in neurodegenerative diseases.

Chemiexcitation and melanin in photoreceptor disc turnover and prevention of macular degeneration.

Age-related macular degeneration, Stargardt disease, and their Abca4-/- mouse model are characterized by accelerated accumulation of the pigment lipofuscin, derived from photoreceptor disc turnover in the retinal pigment epithelium (RPE); lipofuscin accumulation and retinal degeneration both occur earlier in albino mice. Intravitreal injection of superoxide (O2•-) generators reverses lipofuscin accumulation and rescues retinal pathology, but neither the target nor mechanism is known. Here we show that RPE contains thin multi-lamellar membranes (TLMs) resembling photoreceptor discs, which associate with melanolipofuscin granules in pigmented mice but in albinos are 10-fold more abundant and reside in vacuoles. Genetically over-expressing tyrosinase in albinos generates melanosomes and decreases TLM-related lipofuscin. Intravitreal injection of generators of O2•- or nitric oxide (•NO) decreases TLM-related lipofuscin in melanolipofuscin granules of pigmented mice by ~50% in 2 d, but not in albinos. Prompted by evidence that O2•- plus •NO creates a dioxetane on melanin that excites its electrons to a high-energy state (termed "chemiexcitation"), we show that exciting electrons directly using a synthetic dioxetane reverses TLM-related lipofuscin even in albinos; quenching the excited-electron energy blocks this reversal. Melanin chemiexcitation assists in safe photoreceptor disc turnover.

Autophagy in dry AMD: A promising therapeutic strategy for retinal pigment epithelial cell damage.

Dry age-related macular degeneration (AMD) is a prevalent clinical condition that leads to permanent damage to central vision and poses a significant threat to patients' visual health. Although the pathogenesis of dry AMD remains unclear, there is consensus on the role of retinal pigment epithelium (RPE) damage. Oxidative stress and chronic inflammation are major contributors to RPE cell damage, and the NOD-like receptor thermoprotein structural domain-associated protein 3 (NLRP3) inflammasome mediates the inflammatory response leading to apoptosis in RPE cells. Furthermore, lipofuscin accumulation results in oxidative stress, NLRP3 activation, and the development of vitelliform lesions, a hallmark of dry AMD, all of which may contribute to RPE dysfunction. The process of autophagy, involving the encapsulation, recognition, and transport of accumulated proteins and dead cells to the lysosome for degradation, is recognized as a significant pathway for cellular self-protection and homeostasis maintenance. Recently, RPE cell autophagy has been discovered to be closely linked to the development of macular degeneration, positioning autophagy as a cutting-edge research area in the realm of dry AMD. In this review, we present an overview of how lipofuscin, oxidative stress, and the NLRP3 inflammasome damage the RPE through their respective causal mechanisms. We summarized the connection between autophagy, oxidative stress, and NLRP3 inflammatory cytokines. Our findings suggest that targeting autophagy improves RPE function and sustains visual health, offering new perspectives for understanding the pathogenesis and clinical management of dry AMD.

Autophagy and UPS pathway contribute to nicotine-induced protection effect in Parkinson's disease.

The gradual nature of age-related neurodegeneration causes Parkinson's disease (PD) and impairs movement, memory, intellectual ability, and social interaction. One of the most prevalent neurodegenerative conditions affecting the central nervous system (CNS) among the elderly is PD. PD affects both motor and cognitive functions. Degeneration of dopaminergic (DA) neurons and buildup of the protein α-synuclein (α-Syn) in the substantia nigra pars compacta (SNpc) are two major causes of this disorder. Both UPS and ALS systems serve to eliminate α-Syn. Autophagy and UPS deficits, shortened life duration, and lipofuscin buildup accelerate PD. This sickness has no cure. Innovative therapies are halting PD progression. Bioactive phytochemicals may provide older individuals with a natural substitute to help delay the onset of neurodegenerative illnesses. This study examines whether nicotine helps transgenic C. elegans PD models. According to numerous studies, nicotine enhances synaptic plasticity and dopaminergic neuronal survival. Upgrades UPS pathways, increases autophagy, and decreases oxidative stress and mitochondrial dysfunction. At 100, 150, and 200 µM nicotine levels, worms showed reduced α-Syn aggregation, repaired DA neurotoxicity after 6-OHDA intoxication, increased lifetime, and reduced lipofuscin accumulation. Furthermore, nicotine triggered autophagy and UPS. We revealed nicotine's potential as a UPS and autophagy activator to prevent PD and other neurodegenerative diseases.

Sertraline Promotes Health and Longevity in Caenorhabditis elegans.

INTRODUCTION: While several antidepressants have been identified as potential geroprotectors, the effect and mechanism of sertraline on healthspan remain to be elucidated. Here, we explored the role of sertraline in the lifespan and healthspan of Caenorhabditis elegans. METHODS: The optimal effect concentration of sertraline was first screened in wild-type N2 worms under heat stress conditions. Then, we examined the effects of sertraline on lifespan, reproduction, lipofuscin accumulation, mobility, and stress resistance. Finally, the expression of serotonin signaling and aging-related genes was investigated to explore the underlying mechanism, and the lifespan assays were performed in ser-7 RNAi strain, daf-2, daf-16, and aak-2 mutants. RESULTS: Sertraline extended the lifespan in C. elegans with concomitant extension of healthspan as indicated by increasing mobility and reducing fertility and lipofuscin accumulation, as well as enhanced resistance to different abiotic stresses. Mechanistically, ser-7 orchestrated sertraline-induced longevity via the regulation of insulin and AMPK pathways, and sertraline-induced lifespan extension in nematodes was abolished in ser-7 RNAi strain, daf-2, daf-16, and aak-2 mutants. CONCLUSION: Sertraline promotes health and longevity in C. elegans through ser-7-insulin/AMPK pathways.

Lipofuscin causes atypical necroptosis through lysosomal membrane permeabilization.

Lipofuscin granules enclose mixtures of cross-linked proteins and lipids in proportions that depend on the tissue analyzed. Retinal lipofuscin is unique in that it contains mostly lipids with very little proteins. However, retinal lipofuscin also presents biological and physicochemical characteristics indistinguishable from conventional granules, including indigestibility, tendency to cause lysosome swelling that results in rupture or defective functions, and ability to trigger NLRP3 inflammation, a symptom of low-level disruption of lysosomes. In addition, like conventional lipofuscins, it appears as an autofluorescent pigment, considered toxic waste, and a biomarker of aging. Ocular lipofuscin accumulates in the retinal pigment epithelium (RPE), whereby it interferes with the support of the neuroretina. RPE cell death is the primary cause of blindness in the most prevalent incurable genetic and age-related human disorders, Stargardt disease and age-related macular degeneration (AMD), respectively. Although retinal lipofuscin is directly linked to the cell death of the RPE in Stargardt, the extent to which it contributes to AMD is a matter of debate. Nonetheless, the number of AMD clinical trials that target lipofuscin formation speaks for the potential relevance for AMD as well. Here, we show that retinal lipofuscin triggers an atypical necroptotic cascade, amenable to pharmacological intervention. This pathway is distinct from canonic necroptosis and is instead dependent on the destabilization of lysosomes. We also provide evidence that necroptosis is activated in aged human retinas with AMD. Overall, this cytotoxicity mechanism may offer therapeutic targets and markers for genetic and age-related diseases associated with lipofuscin buildups.

Retinal Pigment Epithelium Pigment Granules: Norms, Age Relations and Pathology.

The retinal pigment epithelium (RPE), which ensures the normal functioning of the neural retina, is a pigmented single-cell layer that separates the retina from the Bruch's membrane and the choroid. There are three main types of pigment granules in the RPE cells of the human eye: lipofuscin granules (LG) containing the fluorescent "age pigment" lipofuscin, melanoprotein granules (melanosomes, melanolysosomes) containing the screening pigment melanin and complex melanolipofuscin granules (MLG) containing both types of pigments simultaneously-melanin and lipofuscin. This review examines the functional role of pigment granules in the aging process and in the development of oxidative stress and associated pathologies in RPE cells. The focus is on the process of light-induced oxidative degradation of pigment granules caused by reactive oxygen species. The reasons leading to increased oxidative stress in RPE cells as a result of the oxidative degradation of pigment granules are considered. A mechanism is proposed to explain the phenomenon of age-related decline in melanin content in RPE cells. The essence of the mechanism is that when the lipofuscin part of the melanolipofuscin granule is exposed to light, reactive oxygen species are formed, which destroy the melanin part. As more melanolipofuscin granules are formed with age and the development of degenerative diseases, the melanin in pigmented epithelial cells ultimately disappears.

Effects of short-term exposure to low doses of bisphenol A on cellular senescence in the adult rat kidney.

Bisphenol A (BPA) is one of the primary chemicals produced by volume worldwide. Extensive literature has raised many concerns about its possible involvement in the pathogenesis of kidney diseases, but its contribution has not been extensively studied. During cellular senescence, the interference of lipofuscin with cellular functions promotes further senescence, causing cellular malfunction. Insulin-like growth factor-1 (IGF-1) plays an important protective role in the setting of kidney injury. The goal of the present work was to evaluate the effects of short-term treatment with low doses of BPA on cellular senescence in adult rat kidneys. Male Wistar rats were injected with vehicle (CONTROL group) or 50 or 500 µg/kg/day of BPA for 1 week (BPA50 and BPA500 groups, respectively). The kidneys were fixed in 4% buffered formaldehyde and embedded in paraffin. Immunohistochemical analyses were performed, and an immunoreactive score (IRS) was calculated. Lipofuscin autofluorescence was used for the study of cellular senescence. The renal cortex showed diffuse autofluorescent lipofuscin signal in the proximal convoluted tubules (PCTs) of males in the BPA50-treated (weak intensity) and BPA500-treated (strong intensity) groups, but not in CONTROL males. Labeling of cortical PCTs with anti-IGF-1 antibodies showed an IRS of 0 in the CONTROL group, but IRSs of 4 and 6 in the BPA50- and BPA500-treated groups, respectively. The present results suggest that low, "safe" doses of BPA induce renal injury, as measured by histological signs of renal changes, increased cellular senescence, and activation of cellular repair systems in PCTs.

SCA34 caused by ELOVL4 L168F mutation is a lysosomal lipid storage disease sharing pathology features with neuronal ceroid lipofuscinosis and peroxisomal disorders.

Spinocerebellar ataxia 34 (SCA34) is a late-onset progressive ataxia caused by a mutation in ELOVL4, a gene involved in the biosynthesis of very long-chain fatty acids (VLCFAs). We performed post-mortem neuropathological examinations on four SCA34 patients with the ELOVL4 L168F mutation and compared the findings to age-matched controls. Specific gross findings of SCA34 were limited to pontocerebellar atrophy. On light microscopy, pontine base showed neuronal loss and storage of an autofluorescent lipopigment positive on oil red O, PAS and Hale's colloidal iron and negative on Alcian blue and Luxol fast blue (LFB). Among the swollen neurons were abundant CD68+ /CD163+ /IBA1- macrophages laden with a material with similar histochemical profile as in neurons except for the lack of autofluorescence and oil red O positivity and the presence of needle-like birefringent inclusions. Normal resting IBA1 + microglia were generally absent from pontine base nuclei but present in normal numbers elsewhere in the pons. In dentate nucleus neurons, atrophy was milder than in the pontine base and the coarser storage material was LFB-positive, closely resembling lipofuscin. On electron microscopy, dentate nucleus neurons showed neuronal storage of tridimensionally organized trilaminar spicules within otherwise normal lipofuscin, while in the more affected pontine base neurons, lipofuscin was almost completely replaced by the storage material. Storage macrophages were tightly packed with stacks of unorganized trilaminar spicules, reminiscent of the storage material seen in peroxisomal disorders and thought to represent VLCFAs incorporated in complex polar lipids. In summary, we provide histochemical and ultrastructural evidence that SCA34 is a lipid storage disease, the first among the currently known SCAs, and that the storage lipid is accumulating within neuronal lipofuscin. Our findings suggest that the storage lipid is similar to the one accumulating in non-neuronal cells in peroxisomal disorders and provide the first ultrastructural description of this type of material within neurons.

Lipofuscin, amyloids, and lipid peroxidation as potential markers of aging in Daphnia.

Accumulation of autofluorescent waste products, amyloids, and products of lipid peroxidation (LPO) are important hallmarks of aging. Until now, these processes have not been documented in Daphnia, a convenient model organism for longevity and senescence studies. We conducted a longitudinal cohort study of autofluorescence and Congo Red (CR) fluorescent staining for amyloids in four clones of D. magna. Additionally, we used a single time point cross-sectional common garden experiment within a single clone in which autofluorescence and BODIPY C11 fluorescence were measured. We observed a robust increase in autofluorescent spots that show diagnostic co-staining by Sudan Black indicating lipofuscin aggregates, particularly in the upper body region. There was also a significant clone-by-age interaction indicating that some genotypes accumulated lipofuscins faster than others. Contrary to predictions, CR fluorescence and lipid peroxidation did not consistently increase with age. CR fluorescence demonstrated a slight non-monotonous relationship with age, achieving the highest values at intermediate ages, possibly due to elimination of physiological heterogeneity in our genetically uniform cohorts. LPO demonstrated a significant ovary status-by-age interaction, decreasing with age when measured in Daphnia with full ovaries (late phase ovarian cycle) and showing no significant trend or slight increase with age when measured during the early phase in the ovarian cycle.

Ultrastructural evidence of four types of lipofuscins in the melanomacrophagic centers in hepatocytes of zebrafish (Denio rerio).

Melanomacrophagic centers (MMCs) were studied in the hepatocytes of zebrafish using transmission electron microscope (TEM). The MMCs with irregular or amoeboid nucleus were located in the hepatocytes adjacent to the bile canaliculi. Several engulfed structures were present in the cytoplasm of MMCs. The most frequent observation was the presence of mitochondria, ranging in size from small to giant, with distorted shape and inconspicuous cristae. Occasionally the fragments of erythrocytes were found. The rough endoplasmic reticulum (rER) showed whirling around the mitochondria and lipid droplets, forming membrane-like structures. The damaged mitochondria were invaded by the lysosomes, and this was covered by a membrane led to the formation of lipofuscin. Four different types of lipofuscins were observed; namely, (1) granular with/without vacuoles of high electron-density, (2) homogenous surrounded by indistinct limiting membrane, (3) lamellated structures similar to inner matrix and cristae of mitochondria, and, (4) compound structure made by the combinations of first 3 types, (granular and homogenous, granular and lamellated, homogenous and lamellated). The present evidence suggests that MMCs in the hepatocytes of zebrafish perform continuous functions of removal of the damaged cellular organelles. The lipofuscin formation work in coordination with the cellular players of immune system and remove pathogens and maintain the internal homeostasis of cells.

Altered photoreceptor metabolism in mouse causes late stage age-related macular degeneration-like pathologies.

Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly. While the histopathology of the different disease stages is well characterized, the cause underlying the progression, from the early drusen stage to the advanced macular degeneration stage that leads to blindness, remains unknown. Here, we show that photoreceptors (PRs) of diseased individuals display increased expression of two key glycolytic genes, suggestive of a glucose shortage during disease. Mimicking aspects of this metabolic profile in PRs of wild-type mice by activation of the mammalian target of rapamycin complex 1 (mTORC1) caused early drusen-like pathologies, as well as advanced AMD-like pathologies. Mice with activated mTORC1 in PRs also displayed other early disease features, such as a delay in photoreceptor outer segment (POS) clearance and accumulation of lipofuscin in the retinal-pigmented epithelium (RPE) and of lipoproteins at the Bruch's membrane (BrM), as well as changes in complement accumulation. Interestingly, formation of drusen-like deposits was dependent on activation of mTORC1 in cones. Both major types of advanced AMD pathologies, including geographic atrophy (GA) and neovascular pathologies, were also seen. Finally, activated mTORC1 in PRs resulted in a threefold reduction in di-docosahexaenoic acid (DHA)-containing phospholipid species. Feeding mice a DHA-enriched diet alleviated most pathologies. The data recapitulate many aspects of the human disease, suggesting that metabolic adaptations in photoreceptors could contribute to disease progression in AMD. Identifying the changes downstream of mTORC1 that lead to advanced pathologies in mouse might present new opportunities to study the role of PRs in AMD pathogenesis.

Understanding the Mechanism of Light-Induced Age-Related Decrease in Melanin Concentration in Retinal Pigment Epithelium Cells.

It is known that during the process of aging, there is a significant decrease in the number of melanosomes in the retinal pigment epithelium (RPE) cells in the human eye. Melanosomes act as screening pigments in RPE cells and are fundamentally important for protection against the free radicals generated by light. A loss or change in the quality of melanin in melanosomes can lead to the development of senile pathologies and aggravation in the development of various retinal diseases. We have previously shown that the interaction between melanin melanosomes and superoxide radicals results in oxidative degradation with the formation of water-soluble fluorescent products. In the present study, we show, using fluorescence analysis, HPLC, and mass spectrometry, that visible light irradiation on melanolipofuscin granules isolated from RPE cells in the human eye results in the formation of water-soluble fluorescent products from oxidative degradation of melanin, which was in contrast to lipofuscin granules and melanosomes irradiation. The formation of these products occurs as a result of the oxidative degradation of melanin by superoxide radicals, which are generated by the lipofuscin part of the melanolipofuscin granule. We identified these products both in the composition of melanolipofuscin granules irradiated with visible light and in the composition of melanosomes that were not irradiated but were, instead, oxidized by superoxide radicals. In the melanolipofuscin granules irradiated by visible light, ions that could be associated with melanin oxidative degradation products were identified by applying the principal component analysis of the time-of-flight secondary ion mass spectrometry (ToF-SIMS) data. Degradation of the intact melanosomes by visible light is also possible; however, this requires significantly higher irradiation intensities than for melanolipofuscin granules. It is concluded that the decrease in the concentration of melanin in RPE cells in the human eye with age is due to its oxidative degradation by reactive oxygen species generated by lipofuscin, as part of the melanolipofuscin granules, under the action of light.

Characterizing and Quenching Autofluorescence in Fixed Mouse Adrenal Cortex Tissue.

Tissue autofluorescence of fixed tissue sections is a major concern of fluorescence microscopy. The adrenal cortex emits intense intrinsic fluorescence that interferes with signals from fluorescent labels, resulting in poor-quality images and complicating data analysis. We used confocal scanning laser microscopy imaging and lambda scanning to characterize the mouse adrenal cortex autofluorescence. We evaluated the efficacy of tissue treatment methods in reducing the intensity of the observed autofluorescence, such as trypan blue, copper sulfate, ammonia/ethanol, Sudan Black B, TrueVIEWTM Autofluorescence Quenching Kit, MaxBlockTM Autofluorescence Reducing Reagent Kit, and TrueBlackTM Lipofuscin Autofluorescence Quencher. Quantitative analysis demonstrated autofluorescence reduction by 12-95%, depending on the tissue treatment method and excitation wavelength. TrueBlackTM Lipofuscin Autofluorescence Quencher and MaxBlockTM Autofluorescence Reducing Reagent Kit were the most effective treatments, reducing the autofluorescence intensity by 89-93% and 90-95%, respectively. The treatment with TrueBlackTM Lipofuscin Autofluorescence Quencher preserved the specific fluorescence signals and tissue integrity, allowing reliable detection of fluorescent labels in the adrenal cortex tissue. This study demonstrates a feasible, easy-to-perform, and cost-effective method to quench tissue autofluorescence and improve the signal-to-noise ratio in adrenal tissue sections for fluorescence microscopy.

Juniper berry extract containing Anthricin and Yatein suppresses lipofuscin accumulation in human epidermal keratinocytes through proteasome activation, increases brightness and decreases spots in human skin.

OBJECTIVE: Skin brightness and spot have a significant impact on youthful and beautiful appearance. One important factor influencing skin brightness is the amount of internal reflected light from the skin. Observers recognize the total surface-reflected light and internal reflected light as skin brightness. The more internal reflected light from the skin, the more attractive and brighter the skin appears. This study aims to identify a new natural cosmetic ingredient that increases the skin's internal reflected light, decreases spot and provides a youthful and beautiful skin appearance. METHODS: Lipofuscin in epidermal keratinocytes, the aggregating complex of denatured proteins and peroxidized lipids, is one factor that decreases skin brightness and causes of spot. Aggregates block light transmission, and peroxidized lipids lead to skin yellowness, dullness and age spot. Lipofuscin is known to accumulate intracellularly with ageing. Rapid removal of intracellular denatured proteins prevents lipofuscin formation and accumulation in cells. We focused a proteasome system that efficiently removes intracellular denatured proteins. To identify natural ingredients that increase proteasome activity, we screened 380 extracts derived from natural products. The extract with the desired activity was fractionated and purified to identify active compounds that lead to proteasome activation. Finally, the efficacy of the proteasome-activating extract was evaluated in a human clinical study. RESULTS: We discovered that Juniperus communis fruits (Juniper berry) extract (JBE) increases proteasome activity and suppresses lipofuscin accumulation in human epidermal keratinocytes. We found Anthricin and Yatein, which belong to the lignan family, to be major active compounds responsible for the proteasome-activating effect of JBE. In a human clinical study, an emulsion containing 1% JBE was applied to half of the face twice daily for 4 weeks, resulting in increased internal reflected light, brightness improvement (L-value) and reduction in yellowness (b-value) and spot in the cheek area. CONCLUSION: This is the first report demonstrating that JBE containing Anthricin and Yatein decreases lipofuscin accumulation in human epidermal keratinocytes through proteasome activation, increases brightness and decreases surface spots in human skin. JBE would be an ideal natural cosmetic ingredient for creating a more youthful and beautiful skin appearance with greater brightness and less spot.

OBJECTIF: La luminosité et les taches de peau ont un impact significatif sur la jeunesse et la beauté de l'apparence. L'un des facteurs importants influençant la luminosité de la peau est la quantité de lumière interne réfléchie par la peau. Pour les observateurs, la luminosité de la peau correspond à la somme de la lumière réfléchie par la surface et de la lumière réfléchie par l'intérieur de la peau. Plus la quantité de lumière interne réfléchie par la peau est importante, plus la peau semble attrayante et lumineuse. Cette étude vise à identifier un nouvel ingrédient cosmétique naturel qui augmente la lumière interne réfléchie par la peau, diminue les taches et donne à la peau une apparence jeune et belle. MÉTHODES: La lipofuscine dans les kératinocytes de l'épiderme, le complexe agrégé de protéines dénaturées et de lipides peroxydés, est un facteur qui diminue l'éclat de la peau et qui est à l'origine des taches. Les agrégats bloquent la transmission de la lumière et les lipides peroxydés entraînent une coloration jaune de la peau, un aspect terne et des taches de vieillesse. On sait que la lipofuscine s'accumule au niveau intracellulaire avec le vieillissement. L'élimination rapide des protéines dénaturées intracellulaires empêche la formation et l'accumulation de lipofuscine dans les cellules. Nous avons mis l'accent sur un système de protéasome qui élimine efficacement les protéines dénaturées intracellulaires. Pour identifier les ingrédients naturels qui augmentent l'activité du protéasome, nous avons passé au crible 380 extraits dérivés de produits naturels. L'extrait présentant l'activité souhaitée a été fractionné et purifié afin d'identifier les composés actifs qui conduisent à l'activation du protéasome. Enfin, l'efficacité de l'extrait activant le protéasome a été évaluée dans une étude clinique humaine. RÉSULTATS: Nous avons découvert que l'extrait de Juniperus communis fruits (baie de genièvre) augmente l'activité du protéasome et supprime l'accumulation de lipofuscine dans les kératinocytes épidermiques humains. Nous avons découvert que l'anthricine et la yateine, qui appartiennent à la famille des lignanes, sont les principaux composés actifs responsables de l'effet activateur du protéasome de l'extrait de baies de genévrier. Dans une étude clinique humaine, une émulsion contenant 1 % de JBE a été appliquée sur la moitié du visage deux fois par jour pendant 4 semaines, ce qui a entraîné une augmentation de la lumière interne réfléchie, une amélioration de la luminosité (valeur L) et une réduction de la jaunisse (valeur b) et des taches dans la zone des joues. CONCLUSION: Il s'agit du premier rapport démontrant que l'EBJ contenant de l'anthricine et de la yateine diminue l'accumulation de lipofuscine dans les kératinocytes épidermiques humains par l'activation du protéasome, augmente la luminosité et diminue les taches superficielles de la peau humaine. Le JBE serait un ingrédient cosmétique naturel idéal pour créer une peau plus jeune et plus belle, plus lumineuse et moins tachetée.

[The study of lipofuscin levels in the 5xFAD mouse model of Alzheimer's disease.]

In this study, we evaluated the change in the level of lipofuscin, an autofluorescent aging pigment, in brain and peripheral tissues in a transgenic mouse model of Alzheimer's disease (AD) - 5xFAD. A comparative analysis of the content of lipofuscin in homogenates of the liver, kidneys, heart, and various parts of the brain of 5xFAD mice, as well as control mice from the same litters of different ages, was carried out. The data obtained correlate well with the concept of lipofuscin as an aging pigment - its amount increases with age in both control and 5xFAD mice. We noted accumulation of lipofuscin progressive with age in 5xFAD mice, which is detected both in different parts of the brain and in peripheral organs. At the same time, the level of lipofuscin was increased even in newborn day-old mice 5xFAD. Thus, an increase in the level of lipofuscin in 5xFAD mice is one of the earliest disorders that manifests itself not only in the brain, but also in other organs.

Catabolism of the Lipofuscin Cycloretinal by MsP1.

Age-related macular degeneration (AMD) is a debilitating eye disease that tends to affect people over the age of 55. Lipofuscins are autofluorescent, toxic byproducts of the visual cycle thought to contribute toward the progression of the disease. Targeting the accumulation of lipofuscin through catabolism may serve as a method for the early treatment of AMD. Thus, an enzymatic approach capable of degrading lipofuscin, cycloretinal (all-trans retinal dimer), was examined. A peroxidase from the organism Marasmius scorodonius (MsP1) has shown capability of degrading this toxic metabolite into nontoxic byproducts. A catalytic triad within MsP1 (D228, H365, and R388) was identified through multiple-sequence alignment and homology modeling and confirmed by kinetic analysis. MsP1-associated cleavage products were detected by gas chromatography-mass spectrometry (GC-MS), high-performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry (LC-MS), and liquid chromatography-tandem mass spectrometry (LC-MSMS). MsP1 degradation byproducts of cycloretinal show reduced cytotoxicity within cell culture (ARPE-19), demonstrating its potential as a gene therapeutic to alleviate the buildup of lipofuscin within AMD.

Citrulline protects human retinal pigment epithelium from hydrogen peroxide and iron/ascorbate induced damages.

Oxidative stress plays an important role in the ageing of the retina and in the pathogenesis of retinal diseases such as age-related macular degeneration (ARMD). Hydrogen peroxide is a reactive oxygen species generated by the photo-excited lipofuscin that accumulates during ageing in the retinal pigment epithelium (RPE), and the age-related accumulation of lipofuscin is associated with ARMD. Iron also accumulates with age in the RPE that may contribute to ARMD as an important source of oxidative stress. The aim of this work was to investigate the effects of L-Citrulline (CIT), a naturally occurring amino acid with known antioxidant properties, on oxidative stressed cultured RPE cells. Human RPE (ARPE-19) cells were exposed to hydrogen peroxide (H2 O2 ) or iron/ascorbate (I/A) for 4 h, either in the presence of CIT or after 24 h of pretreatment. Here, we show that supplementation with CIT protects ARPE-19 cells against H2 O2 and I/A. CIT improves cell metabolic activity, decreases ROS production, limits lipid peroxidation, reduces cell death and attenuates IL-8 secretion. Our study evidences that CIT is able to protect human RPE cells from oxidative damage and suggests potential protective effect for the treatment of retinal diseases associated with oxidative stress.

Tissue-Specific Gamma-Flicker Light Noninvasively Ameliorates Retinal Aging.

Aging is a risk factor for multiple retinal degeneration diseases. Entraining brain gamma oscillations with gamma-flicker light (γFL) has been confirmed to coordinate pathological changes in several Alzheimer's disease mouse models and aged mice. However, the direct effect of γFL on retinal aging remains unknown. We assessed retinal senescence-associated beta-galactosidase (ß-gal) and autofluorescence in 20-month-old mice and found reduced ß-gal-positive cells in the inner retina and diminished lipofuscin accumulation around retinal vessels after 6 days of γFL. In immunofluorescence, γFL was further demonstrated to ameliorate aging-related retinal changes, including a decline in microtubule-associated protein 1 light chain 3 beta expression, an increase in complement C3 activity, and an imbalance between the anti-oxidant factor catalase and pro-oxidant factor carboxymethyl lysine. Moreover, we found that γFL can increase the expression of activating transcription factor 4 (ATF4) in the inner retina, while revealing a decrease of ATF4 expression in the inner retina and positive expression in the outer segment of photoreceptor and RPE layer for aged mice. Western blotting was then used to confirm the immunofluorescence results. After mRNA sequencing (NCBI Sequence Read Archive database: PRJNA748184), we found several main mechanistic clues, including mitochondrial function and chaperone-mediated protein folding. Furthermore, we extended γFL to aged Apoe-/- mice and showed that 1-m γFL treatment even improved the structures of retinal-pigment-epithelium basal infolding and Bruch's membrane. Overall, γFL can orchestrate various pathological characteristics of retinal aging in mice and might be a noninvasive, convenient, and tissue-specific therapeutic strategy for retinal aging.