-
ELife Apr 2024Retinitis pigmentosa (RP), a heterogenous group of inherited retinal disorder, causes slow progressive vision loss with no effective treatments available. Mutations in...
Retinitis pigmentosa (RP), a heterogenous group of inherited retinal disorder, causes slow progressive vision loss with no effective treatments available. Mutations in the rhodopsin gene () account for ~25% cases of autosomal dominant RP (adRP). In this study, we describe the disease characteristics of the first-ever reported mono-allelic copy number variation (CNV) in as a novel cause of adRP. We (a) show advanced retinal degeneration in a male patient (68 years of age) harboring four transcriptionally active intact copies of rhodopsin, (b) recapitulated the clinical phenotypes using retinal organoids, and (c) assessed the utilization of a small molecule, Photoregulin3 (PR3), as a clinically viable strategy to target and modify disease progression in RP patients associated with -CNV. Patient retinal organoids showed photoreceptors dysgenesis, with rod photoreceptors displaying stunted outer segments with occasional elongated cilia-like projections (microscopy); increased mRNA expression (quantitative real-time PCR [qRT-PCR] and bulk RNA sequencing); and elevated levels and mislocalization of rhodopsin protein (RHO) within the cell body of rod photoreceptors (western blotting and immunohistochemistry) over the extended (300 days) culture time period when compared against control organoids. Lastly, we utilized PR3 to target , an upstream regulator of , to alter expression and observed a partial rescue of RHO protein localization from the cell body to the inner/outer segments of rod photoreceptors in patient organoids. These results provide a proof-of-principle for personalized medicine and suggest that expression requires precise control. Taken together, this study supports the clinical data indicating that RHO-CNV associated adRPdevelops as a result of protein overexpression, thereby overloading the photoreceptor post-translational modification machinery.
Topics: Aged; Humans; Male; DNA Copy Number Variations; Organoids; Retinitis Pigmentosa; Rhodopsin
PubMed: 38661530
DOI: 10.7554/eLife.90575 -
BioRxiv : the Preprint Server For... Apr 2024Age is the principal risk factor for neurodegeneration in both the retina and brain. The retina and brain share many biological properties; thus, insights into retinal...
BACKGROUND
Age is the principal risk factor for neurodegeneration in both the retina and brain. The retina and brain share many biological properties; thus, insights into retinal aging and degeneration may shed light onto similar processes in the brain. Genetic makeup strongly influences susceptibility to age-related retinal disease. However, studies investigating retinal aging have not sufficiently accounted for genetic diversity. Therefore, examining molecular aging in the retina across different genetic backgrounds will enhance our understanding of human-relevant aging and degeneration in both the retina and brain-potentially improving therapeutic approaches to these debilitating conditions.
METHODS
Transcriptomics and proteomics were employed to elucidate retinal aging signatures in nine genetically diverse mouse strains (C57BL/6J, 129S1/SvlmJ, NZO/HlLtJ, WSB/EiJ, CAST/EiJ, PWK/PhK, NOD/ShiLtJ, A/J, and BALB/cJ) across lifespan. These data predicted human disease-relevant changes in WSB and NZO strains. Accordingly, B6, WSB and NZO mice were subjected to human-relevant examinations at 4, 8, 12, and/or 18M, including: slit lamp, fundus imaging, optical coherence tomography, fluorescein angiography, and pattern/full-field electroretinography. Retinal morphology, vascular structure, and cell counts were assessed
RESULTS
We identified common molecular aging signatures across the nine mouse strains, which included genes associated with photoreceptor function and immune activation. Genetic background strongly modulated these aging signatures. Analysis of cell type-specific marker genes predicted age-related loss of photoreceptors and retinal ganglion cells (RGCs) in WSB and NZO, respectively. Fundus exams revealed retinitis pigmentosa-relevant pigmentary abnormalities in WSB retinas and diabetic retinopathy (DR)-relevant cotton wool spots and exudates in NZO retinas. Profound photoreceptor dysfunction and loss were confirmed in WSB. Molecular analyses indicated changes in photoreceptor-specific proteins prior to loss, suggesting photoreceptor-intrinsic dysfunction in WSB. In addition, age-associated RGC dysfunction, loss, and concomitant microvascular dysfunction was observed in NZO mice. Proteomic analyses revealed an early reduction in protective antioxidant processes, which may underlie increased susceptibility to DR-relevant pathology in NZO.
CONCLUSIONS
Genetic context is a strong determinant of retinal aging, and our multi-omics resource can aid in understanding age-related diseases of the eye and brain. Our investigations identified and validated WSB and NZO mice as improved preclinical models relevant to common retinal neurodegenerative diseases.
PubMed: 38659747
DOI: 10.1101/2024.04.16.589625 -
The Journal of Neuroscience : the... Jun 2024Hexanucleotide repeat expansions within the gene are the most common cause of the neurodegenerative diseases amyotrophic lateral sclerosis (ALS) and frontotemporal...
Hexanucleotide repeat expansions within the gene are the most common cause of the neurodegenerative diseases amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). This disease-causing expansion leads to a reduction in C9ORF72 expression levels in patients, suggesting loss of C9ORF72 function could contribute to disease. To further understand the consequences of C9ORF72 deficiency in vivo, we generated a mutant zebrafish line. Analysis of the adult female spinal cords revealed no appreciable neurodegenerative pathology such as loss of motor neurons or increased levels of neuroinflammation. However, detailed examination of adult female retinas showed prominent neurodegenerative features, including a decrease in retinal thickness, gliosis, and an overall reduction in neurons of all subtypes. Analysis of rod and cone cells within the photoreceptor layer showed a disturbance in their outer segment structure and rhodopsin mislocalization from rod outer segments to their cell bodies and synaptic terminals. Thus, C9ORF72 may play a previously unappreciated role in retinal homeostasis and suggests C9ORF72 deficiency can induce tissue specific neuronal loss.
Topics: Animals; Zebrafish; Female; C9orf72 Protein; Retina; Animals, Genetically Modified; Zebrafish Proteins; Proteins; Retinal Degeneration; Neurodegenerative Diseases; Spinal Cord
PubMed: 38658168
DOI: 10.1523/JNEUROSCI.2128-23.2024 -
The Journal of Clinical Investigation Apr 2024While dysfunction and death of light-detecting photoreceptor cells underlie most inherited retinal dystrophies, knowledge of the species-specific details of human rod...
While dysfunction and death of light-detecting photoreceptor cells underlie most inherited retinal dystrophies, knowledge of the species-specific details of human rod and cone photoreceptor cell development remains limited. Here, we generated retinal organoids carrying retinal disease-causing variants in NR2E3, as well as isogenic and unrelated controls. Organoids were sampled using single-cell RNA sequencing (scRNA-Seq) across the developmental window encompassing photoreceptor specification, emergence, and maturation. Using scRNA-Seq data, we reconstruct the rod photoreceptor developmental lineage and identify a branch point unique to the disease state. We show that the rod-specific transcription factor NR2E3 is required for the proper expression of genes involved in phototransduction, including rhodopsin, which is absent in divergent rods. NR2E3-null rods additionally misexpress several cone-specific phototransduction genes. Using joint multimodal single-cell sequencing, we further identify putative regulatory sites where rod-specific factors act to steer photoreceptor cell development. Finally, we show that rod-committed photoreceptor cells form and persist throughout life in a patient with NR2E3-associated disease. Importantly, these findings are strikingly different from those observed in Nr2e3 rodent models. Together, these data provide a road map of human photoreceptor development and leverage patient induced pluripotent stem cells to define the specific roles of rod transcription factors in photoreceptor cell emergence and maturation in health and disease.
Topics: Humans; Organoids; Retinal Rod Photoreceptor Cells; Orphan Nuclear Receptors; Retinal Cone Photoreceptor Cells; Retina; Cell Differentiation; Light Signal Transduction; Single-Cell Analysis
PubMed: 38652563
DOI: 10.1172/JCI173892 -
Indian Journal of Ophthalmology May 2024This study aims to establish DROL (disruption of retinal outer layers), PROS (photoreceptor outer segment length), SND (subfoveal neuroretinal detachment), and...
Optical coherence tomography biomarkers DROL, PROS, SND, hyperreflective walls of foveal cystoid spaces as predictors of central macular thickness and visual acuity in diabetic macular edema treated with intravitreal ranibizumab.
PURPOSE
This study aims to establish DROL (disruption of retinal outer layers), PROS (photoreceptor outer segment length), SND (subfoveal neuroretinal detachment), and hyperreflective walls of foveal cystoid spaces (HRW) as optical coherence tomography (OCT) biomarkers and predictors of central macular thickness (CMT) and visual acuity in diabetic macular edema (DME) treated with intravitreal ranibizumab (IVR).
METHODS
In this prospective, interventional study performed at a tertiary care center over a span of 1 year from December 2021 to December 2022, 50 eyes of 46 patients of DME were included. Visual acuity and spectral domain OCT imaging were performed at baseline. Using inbuilt calipers on SD-OCT, the horizontal extent of DROL and the vertical extent of PROS were measured manually. SND and HRW were assessed qualitatively. IVR was administered and patients were followed up at 4, 8, and 12 weeks.
RESULTS
The eyes without DROL had statistically significant (P < 0.05) lesser CMT and better BCVA (best-corrected visual acuity) (P < 0.05) after pro re nata injection of IVR. There was a positive correlation between the extent of baseline DROL with final CMT (P < 0.05) and final logMAR BCVA (P > 0.05), whereas negative correlation with the extent of baseline PROS with final CMT (P < 0.05) and final logMAR BCVA (P > 0.05). The presence of HRW and SND predicted non-resolution of CMT and worse visual acuity after treatment with IVR in DME.
CONCLUSION
DROL, PROS, SND, and hyperreflective walls of foveal cystoid spaces may be utilized as qualitative as well as quantitative biomarkers to predict the post-treatment CMT and visual acuity in DME.
Topics: Humans; Tomography, Optical Coherence; Ranibizumab; Macular Edema; Intravitreal Injections; Visual Acuity; Male; Diabetic Retinopathy; Prospective Studies; Angiogenesis Inhibitors; Female; Middle Aged; Fovea Centralis; Vascular Endothelial Growth Factor A; Follow-Up Studies; Macula Lutea; Biomarkers; Aged; Retinal Photoreceptor Cell Outer Segment
PubMed: 38648434
DOI: 10.4103/IJO.IJO_903_23 -
JCI Insight Apr 2024Inherited retinal dystrophies (IRDs) are progressive diseases leading to vision loss. Mutation in the eyes shut homolog (EYS) gene is one of the most frequent causes of...
Inherited retinal dystrophies (IRDs) are progressive diseases leading to vision loss. Mutation in the eyes shut homolog (EYS) gene is one of the most frequent causes of IRD. However, the mechanism of photoreceptor cell degeneration by mutant EYS has not been fully elucidated. Here, we generated retinal organoids from induced pluripotent stem cells (iPSCs) derived from patients with EYS-associated retinal dystrophy (EYS-RD). In photoreceptor cells of RD organoids, both EYS and G protein-coupled receptor kinase 7 (GRK7), one of the proteins handling phototoxicity, were not in the outer segment, where they are physiologically present. Furthermore, photoreceptor cells in RD organoids were vulnerable to light stimuli, and especially to blue light. Mislocalization of GRK7, which was also observed in eys-knockout zebrafish, was reversed by delivering control EYS into photoreceptor cells of RD organoids. These findings suggest that avoiding phototoxicity would be a potential therapeutic approach for EYS-RD.
Topics: Animals; Humans; Eye Proteins; Induced Pluripotent Stem Cells; Light; Mutation; Organoids; Retina; Retinal Dystrophies; Zebrafish
PubMed: 38646933
DOI: 10.1172/jci.insight.174179 -
BioRxiv : the Preprint Server For... Apr 2024Dysfunction of the retinal pigment epithelium (RPE) is a common shared pathology in major degenerative retinal diseases despite variations in the primary etiologies of...
Dysfunction of the retinal pigment epithelium (RPE) is a common shared pathology in major degenerative retinal diseases despite variations in the primary etiologies of each disease. Due to their demanding and indispensable functional roles throughout the lifetime, RPE cells are vulnerable to genetic predisposition, external stress, and aging processes. Building upon recent advancements in stem cell technology for differentiating healthy RPE cells and recognizing the significant roles of small extracellular vesicles (sEV) in cellular paracrine and autocrine actions, we investigated the hypothesis that the RPE-secreted sEV alone can restore essential RPE functions and rescue photoreceptors in RPE dysfunction-driven retinal degeneration. Our findings support the rationale for developing intravitreal treatment of sEV. We demonstrate that intravitreally delivered sEV effectively penetrate the full thickness of the retina. Xenogenic intraocular administration of human-derived EVs did not induce acute immune reactions in rodents. sEV derived from human embryonic stem cell (hESC)-derived fully differentiated RPE cells, but not sEV-depleted conditioned cell culture media (CCM minus sEV), rescued photoreceptors and their function in a Royal College of Surgeons (RCS) rat model. This model is characterized by photoreceptor death and retinal degeneration resulting from a mutation in the gene in RPE cells. From the bulk RNA sequencing study, we identified 447 differently expressed genes in the retina after hESC-RPE-sEV treatment compared with the untreated control. Furthermore, 394 out of 447 genes (88%) showed a reversal in expression toward the healthy state in Long-Evans (LE) rats after treatment compared to the diseased state. Particularly, detrimental alterations in gene expression in RCS rats, including essential RPE functions such as phototransduction, vitamin A metabolism, and lipid metabolism were partially reversed. Defective photoreceptor outer segment engulfment due to intrinsic mutation was partially ameliorated. These findings suggest that RPE-secreted sEV may play a functional role similar to that of RPE cells. Our study justifies further exploration to fully unlock future therapeutic interventions with sEV in a broad array of degenerative retinal diseases.
PubMed: 38645051
DOI: 10.1101/2024.04.09.588773 -
Frontiers in Pharmacology 2023Our research was performed in order to explore the effects of molecular hydrogen (H), a novelly-established antioxidant, on the retinal degeneration in mice, an animal...
Our research was performed in order to explore the effects of molecular hydrogen (H), a novelly-established antioxidant, on the retinal degeneration in mice, an animal model of inherited retinitis pigmentosa (RP). The mice were divided randomly into control and H intervention groups. Mice from other groups received H intervention in three modes, two modes of the hydrogen gas (HG) and one model of hydrogen-rich saline (HRS). At 14 days post born (P14) and P21, various indicators were detected in all mice, including eletroretinogram (ERG), fundus phography, optical coherence tomography (OCT), and retinal immunotaining of microglia cells' marker, Iba1. The ERG amplitude in mice from the control and H intervention groups showed no statistical differences ( 0.05). At P14 and P21, no significant difference in the distance from the retinal pigment epithelium to the outer plexiform layer on OCT from mice of the above two groups was found ( 0.05). The thickness of the outer nuclear layer (ONL) in mice at P14 and P21 showed no statistical differences between the control group and the H intervention group ( 0.05). In the aspect of the number of Iba1-positive cells, we did not found any significant differences between the two groups ( 0.05). Different forms of H intervention (hydrogen-rich saline and hydrogen gas) had no obvious effects on the course of retinal degeneration in mice. The specific mechanism of photoreceptor degeneration in the hereditary RP mouse model may be different, requiring different medical interventions.
PubMed: 38638334
DOI: 10.3389/fphar.2023.1294315 -
American Journal of Ophthalmology Case... Jun 2024We report a case of laser-induced retinopathy that posed diagnostic challenges with conventional spectral domain optical coherence tomography (SD-OCT), but was...
PURPOSE
We report a case of laser-induced retinopathy that posed diagnostic challenges with conventional spectral domain optical coherence tomography (SD-OCT), but was successfully diagnosed using adaptive optics-optical coherence tomography (AO-OCT).
OBSERVATIONS
A 27-year-old man with a history of occupational laser device use presented with central scotoma and visual disturbances in the right eye. Conventional SD-OCT only revealed decreased reflectivity in parts of the foveal ellipsoidal zone band. However, other multimodal observations indicated damage to the retinal pigment epithelium (RPE) and choriocapillaris. Additionally, a well-defined circular, dark lesion, approximately 80 μm in diameter, was identified in the outer retina. AO-OCT demonstrated the absence of the RPE and Bruch's membrane, accompanied by the loss of inner and outer segments of cone photoreceptors and dropout of cone cell nuclei, with Müller cells remaining unaffected.
CONCLUSIONS AND IMPORTANCE
This case of laser-induced retinopathy advances our understanding of the pathophysiological effect of laser exposure on the retina, suggesting a higher incidence of laser-induced retinopathy than previously diagnosed. It also serves as a crucial reminder for laser users to exercise caution and highlights the necessity for ophthalmologists to carefully observe and examine such cases.
PubMed: 38633002
DOI: 10.1016/j.ajoc.2024.102052