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Investigative Ophthalmology & Visual... Nov 2023The purpose of this study was to describe the presence of choroidal hyper-reflective foci (HRF) on optical coherence tomography (OCT) in patients with geographic atrophy...
PURPOSE
The purpose of this study was to describe the presence of choroidal hyper-reflective foci (HRF) on optical coherence tomography (OCT) in patients with geographic atrophy (GA). The relationship between the presence and quantity of choroidal HRF and other clinical and imaging factors was also investigated.
METHODS
A total of 40 participants (40 eyes) with GA and age-related macular degeneration (AMD) were retrospectively analyzed. OCT images were reviewed for the presence, characteristics, and localization of choroidal HRF. The amount of choroidal HRF was quantified in different choroidal layers by two different (i.e. threshold reflectivity and manual counting) methodologies. The primary outcome was to describe and quantify choroidal HRF and correlate them with GA lesion size.
RESULTS
Structural OCT images showed that all patients had multiple hyper-reflective deposits in different layers of the choroid. These hyper-reflective deposits in the choroid were located near Bruch's membrane or the edges of the blood vessels, particularly in the Sattler's layer, and none were observed inside the vessels. Choroidal HRF exhibited variable size and shape and varying effects on the posterior signal, including shadowing or hypertransmission. Mean ± SD number of choroidal HRF per B-scan was 21.5 ± 15.4 using the threshold reflectivity methodology and 25.1 ± 16.0 using the manual counting methodology. A significant correlation between the untransformed GA size and number of HRF was found, considering both quantitative strategies.
CONCLUSIONS
Hyper-reflective dots in the choroid of subjects with GA may be readily identified with structural OCT. These HRF might represent a natural component of the choroid that becomes more visible due to the absence of the retinal pigment epithelium.
Topics: Humans; Geographic Atrophy; Retrospective Studies; Choroid; Macular Degeneration; Bruch Membrane; Retinal Pigment Epithelium; Tomography, Optical Coherence; Fluorescein Angiography
PubMed: 37922157
DOI: 10.1167/iovs.64.14.5 -
Proceedings of the National Academy of... Oct 2023Retinal pigment epithelium (RPE) cells have to phagocytose shed photoreceptor outer segments (POS) on a daily basis over the lifetime of an organism, but the mechanisms...
Retinal pigment epithelium (RPE) cells have to phagocytose shed photoreceptor outer segments (POS) on a daily basis over the lifetime of an organism, but the mechanisms involved in the digestion and recycling of POS lipids are poorly understood. Although it was frequently assumed that peroxisomes may play an essential role, this was never investigated. Here, we show that global as well as RPE-selective loss of peroxisomal β-oxidation in multifunctional protein 2 (MFP2) knockout mice impairs the digestive function of lysosomes in the RPE at a very early age, followed by RPE degeneration. This was accompanied by prolonged mammalian target of rapamycin activation, lipid deregulation, and mitochondrial structural anomalies without, however, causing oxidative stress or energy shortage. The RPE degeneration caused secondary photoreceptor death. Notably, the deterioration of the RPE did not occur in an mutant mouse line, characterized by absent POS shedding. Our findings prove that peroxisomal β-oxidation in the RPE is essential for handling the polyunsaturated fatty acids present in ingested POS and shed light on retinopathy in patients with peroxisomal disorders. Our data also have implications for gene therapy development as they highlight the importance of targeting the RPE in addition to the photoreceptor cells.
Topics: Mice; Humans; Animals; Retinal Pigment Epithelium; Lysosomes; Phagocytosis; Oxidative Stress; Mice, Knockout; Mammals
PubMed: 37862382
DOI: 10.1073/pnas.2301733120 -
European Journal of Ophthalmology Sep 2023Pigmented paravenous chorioretinal atrophy (PPCRA) is an uncommon form of chorioretinal atrophy characterized by perivenous aggregations of pigment clumps associated... (Review)
Review
Pigmented paravenous chorioretinal atrophy (PPCRA) is an uncommon form of chorioretinal atrophy characterized by perivenous aggregations of pigment clumps associated with peripapillary and radial zones of retinal pigment epithelial atrophy that are distributed along the retinal veins. Most patients are asymptomatic, and evidence suggest that PPCRA is slowly progressing. Unless macular involvement is present, the majority of patients usually retain a normal visual function. Our ability to diagnose PPCRA has recently improved thanks to multimodal imaging, especially with the advent of ultra-widefield (UWF) imaging. Blood tests and functional and genetic testing can help with the correct differential diagnosis of pseudo-PPCRA or other disorders with similar characteristics. Although the cause of PPCRA is unknown, it is possible that it has a genetic basis. In this review we provide a summary of the multimodal imaging characteristics of PPCRA, and discuss its possible pathogenesis, based on the genes that have been associated with this disease.
PubMed: 37670517
DOI: 10.1177/11206721231199118 -
World Journal of Stem Cells Jul 2023In recent years, mesenchymal stem cells (MSC) have been considered the most effective source for regenerative medicine, especially due to released soluble paracrine... (Review)
Review
In recent years, mesenchymal stem cells (MSC) have been considered the most effective source for regenerative medicine, especially due to released soluble paracrine bioactive components and extracellular vesicles. These factors, collectively called the secretome, play crucial roles in immunomodulation and in improving survival and regeneration capabilities of injured tissue. Recently, there has been a growing interest in the secretome released by retinal cytotypes, especially retinal pigment epithelium and Müller glia cells. The latter trophic factors represent the key to preserving morphofunctional integrity of the retina, regulating biological pathways involved in survival, function and responding to injury. Furthermore, these factors can play a pivotal role in onset and progression of retinal diseases after damage of cell secretory function. In this review, we delineated the importance of cross-talk between MSCs and retinal cells, focusing on common/induced secreted factors, during experimental therapy for retinal diseases. The cross-link between the MSC and retinal cell secretomes suggests that the MSC secretome can modulate the retinal cell secretome and vice versa. For example, the MSC secretome can protect retinal cells from degeneration by reducing oxidative stress, autophagy and programmed cell death. Conversely, the retinal cell secretome can influence the MSC secretome by inducing changes in MSC gene expression and phenotype.
PubMed: 37545752
DOI: 10.4252/wjsc.v15.i7.665 -
Ceska a Slovenska Oftalmologie :... 2024Central serous chorioretinopathy (CSC) is a disease characterized by serous detachment of the neuroretina, especially in the posterior pole of the eye. It is often... (Review)
Review
Central serous chorioretinopathy (CSC) is a disease characterized by serous detachment of the neuroretina, especially in the posterior pole of the eye. It is often accompanied by serous detachment of the retinal pigment epithelium (RPE) and associated with the leakage of fluid into the subretinal space through the defective RPE. CSC most often affects men of working age. The exact pathophysiology of the disease is not completely known. Based on indocyanine green angiography (ICG), which revealed increased permeability of choroidal vessels, and optical coherence tomography (OCT) showing increased choroidal thickness, choroidal vasculopathy is assumed to be the primary cause of CSC. In most cases, CSC has a good prognosis with spontaneous resorption of the subretinal fluid (SRF) and improvement of visual functions. However, in a small percentage of patients the disease progresses to a chronic or recurrent course, and can lead to irreversible functional and anatomical changes of the retina with a final clinical picture of diffuse retinal pigment epitheliopathy (DRPE). The optimal treatment approach for patients with CSC remains controversial. In recent decades, myriad therapeutic approaches have been used in the treatment of chronic forms of CSC (cCSC); these included for example laser photocoagulation, pharmaceutical treatment, standard photodynamic therapy (PDT) or anti-VEGF. In recent years a less destructive method, specifically PDT in reduced dose regimens, either with a reduced dose of verteporfin or the laser beam energy used, has been preferred in the treatment of cCSC. Comparable efficacy and safety has been demonstrated using reduced-dose or reduced-fluence PDT regimens in patients with cCSC, with an improvement in best-corrected visual acuity and reduction of SRF.
Topics: Male; Humans; Central Serous Chorioretinopathy; Photosensitizing Agents; Photochemotherapy; Visual Acuity; Fluorescein Angiography; Tomography, Optical Coherence; Retrospective Studies; Porphyrins
PubMed: 38531681
DOI: 10.31348/2023/27 -
Nature Communications Oct 2023The retina is an important target organ of diabetes mellitus, with increasing evidence from patients and animal models suggesting that retinal pigment epithelium (RPE)...
The retina is an important target organ of diabetes mellitus, with increasing evidence from patients and animal models suggesting that retinal pigment epithelium (RPE) may serve as an early marker for diabetes-related damages. However, their longitudinal relationship and the biological underpinnings remain less well understood. Here, we demonstrate that reduced in vivo measurements of RPE thickness (RPET) represents a significant risk factor for future type 2 diabetes mellitus (T2DM) and its microvascular phenotypes. After performing systematic analyses of circulating plasma metabolites using two complementary approaches, we identify a wide range of RPET metabolic fingerprints that are independently associated with reduced RPET. These fingerprints hold their potential to improve predictability and clinical utility for stratifying future T2DM and related microvascular phenotypes beyond traditional clinical indicators, providing insights into the promising role of retinas as a window to systemic health.
Topics: Animals; Humans; Retinal Pigment Epithelium; Diabetes Mellitus, Type 2; Retina; Phenotype; Risk Assessment
PubMed: 37852995
DOI: 10.1038/s41467-023-42404-1 -
International Journal of Molecular... Mar 2024The 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... (Review)
Review
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.
Topics: Humans; Retinal Pigment Epithelium; Melanins; Lipofuscin; Reactive Oxygen Species; Retina
PubMed: 38612421
DOI: 10.3390/ijms25073609 -
World Journal of Diabetes Jul 2023Klotho (Kl) is considered an antiaging gene, mainly for the inhibition of the insulin-like growth factor-1 signaling. Kl exists as full-length transmembrane, which acts... (Review)
Review
Klotho (Kl) is considered an antiaging gene, mainly for the inhibition of the insulin-like growth factor-1 signaling. Kl exists as full-length transmembrane, which acts as co-receptor for fibroblast growth factor receptor, and in soluble forms (sKl). The sKl may exert pleiotropic effects on organs and tissues by regulating several pathways involved in the pathogenesis of diseases associated with oxidative and inflammatory state. In diabetic Patients, serum levels of Kl are significantly decreased compared to healthy subjects, and are related to duration of diabetes. In diabetic retinopathy (DR), one of the most common microvascular complications of type 2 diabetes, serum Kl levels are negatively correlated with progression of the disease. A lot of evidences showed that Kl regulates several mechanisms involved in maintaining homeostasis and functions of retinal cells, including phagocytosis, calcium signaling, secretion of vascular endothelial growth factor A (VEGF-A), maintenance of redox status, and melanin biosynthesis. Experimental data have been shown that Kl exerts positive effects on several mechanisms involved in onset and progression of DR. In particular, treatment with Kl: (1) Prevents apoptosis induced by oxidative stress in human retinal endothelial cells and in retinal pigment epithelium (RPE) cells; (2) reduces secretion of VEGF-A by RPE cells; and (3) decreases subretinal fibrosis and preserves autophagic activity. Therefore, Kl may become a novel biomarker and a good candidate for the treatment of DR.
PubMed: 37547589
DOI: 10.4239/wjd.v14.i7.1027 -
Disease Models & Mechanisms Jul 2023Oxidative stress has been implicated in the pathogenesis of age-related macular degeneration, the leading cause of blindness in older adults, with retinal pigment...
Oxidative stress has been implicated in the pathogenesis of age-related macular degeneration, the leading cause of blindness in older adults, with retinal pigment epithelium (RPE) cells playing a key role. To better understand the cytotoxic mechanisms underlying oxidative stress, we used cell culture and mouse models of iron overload, as iron can catalyze reactive oxygen species formation in the RPE. Iron-loading of cultured induced pluripotent stem cell-derived RPE cells increased lysosomal abundance, impaired proteolysis and reduced the activity of a subset of lysosomal enzymes, including lysosomal acid lipase (LIPA) and acid sphingomyelinase (SMPD1). In a liver-specific Hepc (Hamp) knockout murine model of systemic iron overload, RPE cells accumulated lipid peroxidation adducts and lysosomes, developed progressive hypertrophy and underwent cell death. Proteomic and lipidomic analyses revealed accumulation of lysosomal proteins, ceramide biosynthetic enzymes and ceramides. The proteolytic enzyme cathepsin D (CTSD) had impaired maturation. A large proportion of lysosomes were galectin-3 (Lgals3) positive, suggesting cytotoxic lysosomal membrane permeabilization. Collectively, these results demonstrate that iron overload induces lysosomal accumulation and impairs lysosomal function, likely due to iron-induced lipid peroxides that can inhibit lysosomal enzymes.
Topics: Mice; Animals; Proteomics; Oxidative Stress; Lysosomes; Iron; Iron Overload; Epithelial Cells; Retinal Pigments; Retinal Pigment Epithelium
PubMed: 37401371
DOI: 10.1242/dmm.050066 -
Genes & Diseases Nov 2023The retinal pigment epithelium (RPE) and choroid are located behind the human retina and have multiple functions in the human visual system. Knowledge of the RPE and...
The retinal pigment epithelium (RPE) and choroid are located behind the human retina and have multiple functions in the human visual system. Knowledge of the RPE and choroid cells and their gene expression profiles are fundamental for understanding retinal disease mechanisms and therapeutic strategies. Here, we sequenced the RNA of about 0.3 million single cells from human RPE and choroids across two regions and seven ages, revealing regional and age differences within the human RPE and choroid. Cell-cell interactions highlight the broad connectivity networks between the RPE and different choroid cell types. Moreover, the transcription factors and their target genes change during aging. The coding of somatic variations increases during aging in the human RPE and choroid at the single-cell level. Moreover, we identified as a candidate for improving RPE degeneration and choroidal structure during aging. The mapping of the molecular architecture of the human RPE and choroid improves our understanding of the human vision support system and offers potential insights into the intervention targets for retinal diseases.
PubMed: 37554187
DOI: 10.1016/j.gendis.2022.11.007