Retinitis Pigmentosa: Progress in Molecular Pathology and Biotherapeutical Strategies

Generation of a human iPSC line with heterozygous PRPF8 c.5792C > T, p. T1931M mutation to model retinitis pigmentosa using CRISPR/Cas9 technology

Mutations in the PRPF8 gene frequently result in retinitis pigmentosa (RP), an autosomal dominant inherited retinal disease that can lead to nyctalopia and progressive vision loss. Currently, no effective treatment is available. In this study, we used CRISPR/Cas9 technology to introduce a heterozygous point mutation inthe PRPF8 gene of a normal induced pluripotent stem cell (iPSC) line. This mutation mirrors that found in a previously reportedRP patient-derived iPSC line (CSUASOi006-A) from our group. Establishing the PRPF8 gene mutation cell line (CSUASOi012-A-2) provides a valuable cellular resource for studying the pathogenesis of RP.

Enhancing ophthalmology students' awareness of retinitis pigmentosa: assessing the efficacy of ChatGPT in AI-assisted teaching of rare diseases-a quasi-experimental study

Background

Retinitis pigmentosa (RP) is a rare retinal dystrophy often underrepresented in ophthalmology education. Despite advancements in diagnostics and treatments like gene therapy, RP knowledge gaps persist. This study assesses the efficacy of AI-assisted teaching using ChatGPT compared to traditional methods in educating students about RP.

Methods

A quasi-experimental study was conducted with 142 medical students randomly assigned to control (traditional review materials) and ChatGPT groups. Both groups attended a lecture on RP and completed pre- and post-tests. Statistical analyses compared learning outcomes, review times, and response accuracy.

Results

Both groups significantly improved in post-test scores (p < 0.001), but the ChatGPT group required less review time (24.29 ± 12.62 vs. 42.54 ± 20.43 min, p < 0.0001). The ChatGPT group also performed better on complex questions regarding advanced RP treatments, demonstrating AI's potential to deliver accurate and current information efficiently.

Conclusion

ChatGPT enhances learning efficiency and comprehension of rare diseases like RP. A hybrid educational model combining AI with traditional methods can address knowledge gaps, offering a promising approach for modern medical education.

Reporting a Homozygous Case of Neurodevelopmental Disorder Associated With a Novel PRPF8 Variant

BACKGROUND

While recently identified heterozygous PRPF8 variants have been linked to various human diseases, their role in neurodevelopmental disorders (NDDs) remains ambiguous. This study investigates the potential association between homozygous PRPF8 variants and NDDs. Most PRPF8 variants are primarily associated with retinal diseases; however, we analyze a family with multiple members diagnosed with NDDs.

METHODS

Using exome sequencing (ES), the cause of behavioral problems and intellectual disabilities (IDs) of two sisters from a consanguineous parents was solved, and the results confirmed by direct sanger sequencing method likewise protein modeling to assess the structural impact of the identified variant on the PRPF8 protein has been done.

RESULTS

ES identified a novel homozygous variant, PRPF8 c.257G>T, p.R86M. To the best of our knowledge at the time of writing this manuscript, the mentioned variant has not been reported in relation to NDDs. Protein modeling provided another line of evidence proving the pathogenicity of the novel variant.

CONCLUSION

Our findings indicate that the p.R86M variant may disrupt normal protein function by changing its structure and probably its interaction, potentially leading to the observed neurodevelopmental phenotypes. This study highlights the first link between the PRPF8 variant and NDDs, suggesting a distinct role for specific PRPF8 variants in the etiology of NDDs. These results warrant further investigation into the mechanisms by which PRPF8 variants contribute to NDDs, emphasizing the need for comprehensive genetic screening in families with unexplained neurodevelopmental conditions.

Mesenchymal stem cells and mesenchymal stem cell-derived exosomes: a promising strategy for treating retinal degenerative diseases

Mesenchymal stem cells (MSCs) have emerged as a promising therapeutic strategy in regenerative medicine, demonstrating significant potential for clinical applications. Evidence suggests that MSCs not only exhibit multipotent differentiation potential but also exert critical therapeutic effects in retinal degenerative diseases via robust paracrine mechanisms. MSCs protect retinal cells from degenerative damage by modulating inflammation, inhibiting apoptosis, alleviating oxidative stress, and suppressing cell death pathways. Furthermore, MSCs contribute to retinal structural and functional stability by facilitating vascular remodeling and donating mitochondria to retinal cells. Of particular interest, MSC-derived exosomes have gained widespread attention as a compelling cell-free therapy. Owing to their potent anti-inflammatory, anti-apoptotic, and vascular-stabilizing properties, exosomes show significant promise for the treatment of retinal degenerative diseases.

New perspectives on DNA methylation modifications in ocular diseases

The methylation of DNA is a prevalent epigenetic modification that plays a crucial role in the pathological progression of ocular diseases. DNA methylation can regulate gene expression, thereby affecting cell function and signal transduction. Ophthalmic diseases are a kind of complex diseases, and their pathogenesis involves many factors such as genetic, environmental and individual differences. In addition, inflammation, oxidative stress and lipid metabolism, which abnormal DNA methylation is closely related to, are also considered to be major factors in eye diseases. The current understanding of DNA methylation in eye diseases is becoming more complex and comprehensive. In addition to the simple suppression of gene expression by hypermethylation, factors such as hypomethylation or demethylation, DNA methylation in non-promoter regions, interactions with other epigenetic modifications, and dynamic changes in DNA methylation must also be considered. Interestingly, although some genes are at abnormal methylation levels, their expression is not significantly changed, which indirectly reflects the complexity of gene regulation. This review aims to summarize and compare some relevant studies, and provide with new ideas and methods for the prevention and treatment of different eye diseases, such as glaucoma, retinoblastoma, and diabetic retinopathy.

Effect of Dync1h1 on Phototransduction Protein Transport and the Development and Maintenance of Photoreceptor Cells in Zebrafish

Purpose

Retinitis pigmentosa (RP) is a hereditary retinal disease characterized by progressive degeneration of photoreceptor cells (PRCs). Identifying potential pathogenic genes and understanding the mechanisms of PRC degeneration are essential for improving diagnosis and treatment. Cytoplasmic dynein 1, responsible for retrograde axonal transport along microtubules, plays critical roles in neuronal function. This study utilized dync1h1-deficient zebrafish to investigate its roles in PRC morphogenesis and degeneration.

Methods

Heterozygous and homozygous dync1h1-deficient zebrafish were confirmed through Sanger sequencing. Morphological changes and retinal phenotypes were assessed through histological analysis. RNA sequencing and bioinformatics were used to explore molecular mechanisms in dync1h1-/- zebrafish, with endoplasmic reticulum (ER) stress and apoptosis pathways validated in vivo.

Results

Dync1h1-/- zebrafish exhibit severe developmental defects, including microphthalmia, disorganized retinal lamination, and PRC apoptosis. In dync1h1+/-, mild but progressive growth retardation and PRC defects were observed. Dync1h1 loss impaired retrograde axonal transport, leading to defects in cilium biogenesis and transport disorder of phototransduction proteins in PRCs. This triggered ER stress, activating BiP-ATF4-CHOP signaling pathway and leading to PRC degeneration.

Conclusions

Dync1h1 is essential for maintaining retrograde axonal transport and proper trafficking of phototransduction proteins in PRCs. Non-resolving ER stress-induced PRC apoptosis is a key factor in DYNC1H1-associated retinal degeneration. This study provides important insights into the precise diagnosis and may help in the development of targeted therapies for retinal degenerative diseases.

Genetically predicted inflammatory cytokine levels and risk of retinitis pigmentosa

PURPOSE

This study aims to estimate the potential causal relationship between genetically predicted levels of inflammatory cytokine and retinitis pigmentosa (RP) by performing Mendelian randomization (MR).

METHODS

Single nucleotide polymorphisms (SNPs) were identified as instrumental variables (IVs) from publicly available genome-wide association study datasets. Inverse-variance weighted (IVW), MR-Egger, weighted median, simple mode, and weighted mode methods were applied in this MR analysis. IVW and MR-Egger were used to confirm heterogeneity and pleiotropy of identified IVs. Leave-one-SNP-out analysis was used to identify SNPs with potential impact.

RESULTS

IVW results revealed that elevated levels of Tumor Necrosis Factor Alpha (TNF-α), Macrophage Inflammatory Protein-1a (MIP1a), and Monokine Induced by Gamma Interferon (MIG) were associated with higher RP risk (OR = 2.358, p = 0.050; OR = 2.583, p = 0.013; OR = 1.851, p = 0.015), while elevated levels of Interleukin-16 (IL-16) were associated with reduced RP risk (OR = 0.723, p = 0.019). The results of heterogeneity and pleiotropy (p > 0.05) confirmed there was no pleiotropy and heterogeneity in our IVW analysis. The association of TNF-α, MIP1a, MIG and IL-16 with RP from sensitivity analyses using these two sets of restricted IVs remained stable.

CONCLUSION

Our study provides evidence of potential causal relationships between several circulating cytokine levels and RP. Elevated levels of TNF-α, MIP1a, and MIG are associated with a higher risk of RP, while elevated levels of IL-16 are associated with a lower risk of RP. These cytokines may be novel biomarkers and therapeutic targets for RP.

Plasmid Gene Therapy for Monogenic Disorders: Challenges and Perspectives

Monogenic disorders are a group of human diseases caused by mutations in single genes. While some disease-altering treatments offer relief and slow the progression of certain conditions, the majority of monogenic disorders still lack effective therapies. In recent years, gene therapy has appeared as a promising approach for addressing genetic disorders. However, despite advancements in gene manipulation tools and delivery systems, several challenges remain unresolved, including inefficient delivery, lack of sustained expression, immunogenicity, toxicity, capacity limitations, genomic integration risks, and limited tissue specificity. This review provides an overview of the plasmid-based gene therapy techniques and delivery methods currently employed for monogenic diseases, highlighting the challenges they face and exploring potential strategies to overcome these barriers.

Retinitis Pigmentosa and Therapeutic Candidates

Retinitis pigmentosa (RP) is a class of inherited retinal dystrophies (IRDs) that involves the degeneration of retinal photoreceptor cells and results in progressive vision loss. It was identified and named in 1857. For over 100 years, treatment of RP was generally limited to modifications in diet, management of cystoid macular edema, and supportive care for low vision. Over the last several decades, advances in technology and our understanding of the human genome have led to a host of new therapeutic candidates for the treatment of RP. This includes gene and cell therapy, optogenetics, neuroprotective agents, and electronic retinal implants. In this article, we summarize both the traditional and novel therapeutic modalities for the treatment of retinitis pigmentosa.

In vivo adenine base editing ameliorates Rho-associated autosomal dominant retinitis pigmentosa

Mutations in the Rhodopsin (RHO) gene are the main cause of autosomal dominant retinitis pigmentosa (adRP), 84% of which are pathogenic gain-of-function point mutations. Treatment strategies for adRP typically involve silencing or ablating the pathogenic allele, while normal RHO protein replacement has no meaningful therapeutic benefit. Here, we present an adenine base editor (ABE)-mediated therapeutic approach for adRP caused by RHO point mutations in vivo. The correctable pathogenic mutations are screened and verified, including T17M, Q344ter, and P347L. Two adRP animal models are created carrying the class 1 (Q344ter) and class 2 (T17M) mutations, and dual AAV-delivered ABE can effectively repair both mutations in vivo. The early intervention of ABE8e efficiently corrects the Q344ter mutation that causes a severe form of adRP, delays photoreceptor death, and restores retinal function and visual behavior. These results suggest that ABE is a promising alternative to treat RHO mutation-associated adRP. Our work provides an effective spacer-mediated point mutation correction therapy approach for dominantly inherited ocular disorders.

From bench to bedside: cutting-edge applications of base editing and prime editing in precision medicine

CRISPR-based gene editing technology theoretically allows for precise manipulation of any genetic target within living cells, achieving the desired sequence modifications. This revolutionary advancement has fundamentally transformed the field of biomedicine, offering immense clinical potential for treating and correcting genetic disorders. In the treatment of most genetic diseases, precise genome editing that avoids the generation of mixed editing byproducts is considered the ideal approach. This article reviews the current progress of base editors and prime editors, elaborating on specific examples of their applications in the therapeutic field, and highlights opportunities for improvement. Furthermore, we discuss the specific performance of these technologies in terms of safety and efficacy in clinical applications, and analyze the latest advancements and potential directions that could influence the future development of genome editing technologies. Our goal is to outline the clinical relevance of this rapidly evolving scientific field and preview a roadmap for successful DNA base editing therapies for the treatment of hereditary or idiopathic diseases.

Short-Term Results of Multiwavelength Photobiomodulation in Retinitis Pigmentosa

Objective

To assess the short-term effects of Multiwavelength Photobiomodulation (LumiThera Valeda Light Delivery System) on retinal functional behavior in patients with retinitis pigmentosa (RP).

Materials and Methods

Twelve RP patients (24 eyes) underwent treatment involving nine photobiomodulation (PBM) sessions using the Valeda system, which emits three distinct wavelengths within the yellow (590 nm; 4 mW/cm2), red (660 nm; 65 mW/cm2), and near-infrared (NIR) (850 nm; 0.6 mW/cm2) spectrum. All evaluations were conducted four weeks post-therapy. The treated eye was compared with baseline (pre-therapy). Following nine PBM sessions, assessments included best-corrected visual acuity (BCVA), retinal sensitivity, and characteristics of the correction area via fundus automated perimetry using the Compass system. Additionally, a functional and structural assessment of the retina was performed using multifocal electroretinography (ERG), optical coherence tomography (OCT), fluorescence retinography (FR), and autofluorescence (AF). Statistical analysis employed the Student's t-test for paired samples at a 95% confidence level (p-value ≤ 0.05).

Results

LogMAR-based visual acuity assessment demonstrated an improvement in mean value from 0.62 to 0.53 logMAR, with a statistically significant p-value of 0.001. Visual field examination, based on mean deviation (MD), pattern standard deviation (PSD), and fundal perimeter deviation index (FPDI) parameters, showed improvement from -19.87 dB to -19.45 dB, 9.77 dB to 9.76 dB, and 37% to 39%, respectively, although with non-significant p-values of 0.366, 0.446, and 0.245, respectively. No adverse effects or abnormalities in optical coherence tomography (OCT) and electroretinogram (ERG) were observed during the follow-up period.

Conclusion

In this short-term study, PBM appeared to have the potential to enhance BCVA and fundus automated perimeter in RP patients without causing significant adverse events. However, further assessment with a larger patient cohort and longer follow-up is warranted to ascertain the efficacy of this technique in these patients.

A Case of Autosomal Recessive Retinitis Pigmentosa with Vitelliform-Like Appearance at the Macula Associated with Novel MYO7A Variant P.Ser383TrpfsTer64

Retinitis pigmentosa (RP) is an inherited disease involving progressive degeneration of rod and cone photoreceptors. It is highly heterogeneous and the resulting clinical phenotypes may differ in age at onset, progression, and severity. Mutations in the myosin VIIA (MYO7A) gene have been known to cause Usher syndrome, a condition characterized by RP and deafness. In this report, we present a rare case of RP without hearing loss associated with a novel MYO7A variant, p.Ser383TrpfsTer64. With this case, we also wanted to draw attention to the rare vitelliform-like appearance in the macula in patients with RP.

CRISPR/Cas9-mediated generation of a human induced pluripotent stem cell line with PRPF6 c.2699 G > A mutation to model retinitis pigmentosa

PRPF6, located on chromosome 20, is required for the formation of the spliceosome. Mutations in the PRPF6 gene can lead to retinitis pigmentosa (RP), a common inherited retinal disease characterized by progressive degeneration of retinal pigment epithelium and photoreceptors. Here, we generated an induced pluripotent stem cell (iPSC) line carrying the PRPF6 c.2699 G > A mutation using CRISPR/Cas9 technology, which will provide a valuable resource for RP pathogenesis and treatment research.

TraceEyeDisease: a web-based database for investigating trace elements and their imbalances in eye diseases

Eye diseases remain a significant global health concern, with trace elements crucial in maintaining ocular health and preventing ocular disorders. In ocular health, trace elements have been recognized as critical factors influencing the development and progression of multiple eye diseases. In this study, we conducted a thorough literature search through PubMed to acquire data concerning different eye diseases associated with trace elements. These diseases are essential in trace element imbalances or deficiencies in their progression. Our approach included a meticulous compilation of information from various databases, systematically integrated into a carefully curated database. In total, we identified 178 distinct genes that encode proteins linked to fourteen trace elements in this comprehensive list. A web-based database designed to formulate evidence-based hypotheses regarding the impact of trace element deficiency and imbalance on eye diseases was presented using Shiny R. This study underscores the vital role of trace elements in preserving ocular health. The Shiny R application facilitates subsequent investigations, fostering enhanced insights into public health, clinical practices, and eye disease research. The URL of TraceEyeDiseas is https://tredis.shinyapps.io/TraceEyeDisease/ .

Clinical and molecular findings in children with retinitis pigmentosa

PURPOSE

To study the clinical and genetic features of a cohort of RP children.

METHODS

We identified 46 RP patients with pathogenic or likely pathogenic mutations among 96 patients with a clinical diagnosis of retinitis pigmentosa. All of the patients underwent comprehensive clinical examinations and genetic testing. A retrospective study was conducted on 46 children with retinitis pigmentosa. The genetic and clinical characteristics of children with different genotypes were analyzed.

RESULTS

Among the 46 children, 13 inherited X-linked gene mutations, including 9 RPGR and 4 RP2 mutations. There were 10 cases of autosomal dominant genes and 23 cases of autosomal recessive genes. XLRP accounted for a larger proportion of children, as observed in previous studies on RP. We found that RPGR genes were the most commonly mutated genes in RP children. The most frequently mutated gene was RPGR (9.3%), followed by RP2 (4.2%) and RPE65 (4.2%). Forty-six patients had mutations in 21 different genes, 19 of which were novel mutations.Most children with XLRP have a high degree of myopia, poor vision, and severe clinical symptoms. Frameshift mutations were more common in XLRP, followed by nonsense mutations. The onset of XLRP is relatively serious since childhood. Most children with ADRP have relatively good visual acuity and mild clinical symptoms, and missense mutations are common. The clinical manifestations of ARRP in children are more severe than those of ADRP in children but milder than those of XLRP in children, and missense mutations are common. The manifestations of RPE65 mutations are also severe and appear early.

CONCLUSIONS

Our results revealed that XLRP gene mutations were more common in children than in adults, as observed in previous studies on RP. The proportion of RP children with ADRP is relatively small. The new findings in our study polished the spectrum of novel mutations and the proportions of different genotypes in pediatric patients. The onset of XLRP occurred earlier. The genes with a high incidence in children were all relatively severe gene types of RP. This comprehensive database may provide essential information regarding the initial stage of RP.

Therapeutic Effects of Metformin on Central Nervous System Diseases: A Focus on Protection of Neurovascular Unit

Metformin is one of the most commonly used oral hypoglycemic drugs in clinical practice, with unique roles in neurodegeneration and vascular lesions. Neurodegeneration and vasculopathy coexist in many diseases and typically affect the neurovascular unit (NVU), a minimal structural and functional unit in the central nervous system. Its components interact with one another and are indispensable for maintaining tissue homeostasis. This review focuses on retinal (diabetic retinopathy, retinitis pigmentosa) and cerebral (ischemic stroke, Alzheimer's disease) diseases to explore the effects of metformin on the NVU. Metformin has a preliminarily confirmed therapeutic effect on the retinal NUV, affecting many of its components, such as photoreceptors (cones and rods), microglia, ganglion, Müller, and vascular endothelial cells. Since it rapidly penetrates the blood-brain barrier (BBB) and accumulates in the brain, metformin also has an extensively studied neuronal protective effect in neuronal diseases. Its mechanism affects various NVU components, including pericytes, astrocytes, microglia, and vascular endothelial cells, mainly serving to protect the BBB. Regulating the inflammatory response in NVU (especially neurons and microglia) may be the main mechanism of metformin in improving central nervous system related diseases. Metformin may be a potential drug for treating diseases associated with NVU deterioration, however, more trials are needed to validate its timing, duration, dose, clinical effects, and side effects.

Targeting Relevant HDACs to Support the Survival of Cone Photoreceptors in Inherited Retinal Diseases: Identification of a Potent Pharmacological Tool with In Vitro and In Vivo Efficacy

Inherited retinal diseases, which include retinitis pigmentosa, are a family of genetic disorders characterized by gradual rod-cone degeneration and vision loss, without effective pharmacological treatments. Experimental approaches aim to delay disease progression, supporting cones' survival, crucial for human vision. Histone deacetylases (HDACs) mediate the activation of epigenetic and nonepigenetic pathways that modulate cone degeneration in RP mouse models. We developed new HDAC inhibitors (5a-p), typified by a tetrahydro-γ-carboline scaffold, characterized by high HDAC6 inhibition potency with balanced physicochemical properties for in vivo studies. Compound 5d (repistat, IC50 HDAC6 = 6.32 nM) increased the levels of acetylated α-tubulin compared to histone H3 in ARPE-19 and 661W cells. 5d promoted vision rescue in the atp6v0e1-/- zebrafish model of photoreceptor dysfunction. A single intravitreal injection of 5d in the rd10 mouse model of RP supported morphological and functional preservation of cone cells and maintenance of the retinal pigment epithelium array.

RHO Variants and Autosomal Dominant Retinitis Pigmentosa: Insights from the Italian Genetic Landscape

Autosomal dominant retinitis pigmentosa (AD-RP) is caused by several genes, among which RHO is one of the most investigated. This article will be focused on RHO and its role in explaining AD-RP cases in the Italian population, taking advantage of the experience of the Genomic Medicine Laboratory UILDM at the Santa Lucia Foundation IRCCS. The retrospective evaluation of the distribution of RHO variants in the Italian patients with a clinical suspicion of RP pointed out eight variants. Of them, four variants (c.632A>T, c.1040C>T, c.1030C>T, c.383_392del) were pathogenic and made it possible to confirm the diagnosis of AD-RP in nine affected patients, highlighting a lower frequency (17%) of RHO variants compared to previous studies (30-40%). In addition, this study identified four variants classified as Variants of Uncertain Significance (VUS). In conclusion, the experience of the Genomic Medicine Laboratory provides an overview of the distribution of RHO variants in the Italian population, highlighting a slightly lower frequency of these variants in our cases series compared to previous reports. However, further studies on RHO variants are essential to characterize peculiar RP phenotypes and extend the spectrum of disease associated with this gene.

Research Progress on the Role of Ubiquitination in Eye Diseases

The occurrence and development of ophthalmic diseases are related to the dysfunction of eye tissues. Ubiquitin is an important form of protein post-translational modification, which plays an essential role in the occurrence and development of diseases through specific modification of target proteins. Ubiquitination governs a variety of intracellular signal transduction processes, including proteasome degradation, DNA damage repair, and cell cycle progression. Studies have found that ubiquitin can play a role in eye diseases such as cataracts, glaucoma, keratopathy, retinopathy, and eye tumors. In this paper, the role of protein ubiquitination in eye diseases was reviewed.

Current developments of gene therapy in human diseases

Gene therapy has witnessed substantial advancements in recent years, becoming a constructive tactic for treating various human diseases. This review presents a comprehensive overview of these developments, with a focus on their diverse applications in different disease contexts. It explores the evolution of gene delivery systems, encompassing viral (like adeno-associated virus; AAV) and nonviral approaches, and evaluates their inherent strengths and limitations. Moreover, the review delves into the progress made in targeting specific tissues and cell types, spanning the eye, liver, muscles, and central nervous system, among others, using these gene technologies. This targeted approach is crucial in addressing a broad spectrum of genetic disorders, such as inherited lysosomal storage diseases, neurodegenerative disorders, and cardiovascular diseases. Recent clinical trials and successful outcomes in gene therapy, particularly those involving AAV and the clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated proteins, are highlighted, illuminating the transformative potentials of this approach in disease treatment. The review summarizes the current status of gene therapy, its prospects, and its capacity to significantly ameliorate patient outcomes and quality of life. By offering comprehensive analysis, this review provides invaluable insights for researchers, clinicians, and stakeholders, enriching the ongoing discourse on the trajectory of disease treatment.

A novel compound heterozygous PCDH15 variants is associated with arRP in a Chinese pedigree

BACKGROUND

Retinitis pigmentosa (RP) is a heterogeneous group of inherited retinal diseases. However, it is still not well understand about the relationship between PCDH15 variants and RP.

METHODS

In this study, we enrolled a Chinese autosomal recessive retinitis pigmentosa (arRP) pedigree and identified the causative gene in the proband by targeted whole exome sequencing (WES). The variants were validated in the family members by Sanger sequencing and co-segregation analysis.

RESULTS

Novel compound heterozygous, Frame shift variants of the PCDH15 gene, NM_001384140.1:c.4368 - 2147_4368-2131del and NM_001384140.1:c exon19:c.2505del: p. T836Lfs*6 were identified in the arRP pedigree, which co-segregated with the clinical RP phenotypes. The PCDH15 protein is highly conserved among species.

CONCLUSION

This is the first study to identify novel compound heterozygous variants c.4368 - 2147_4368-2131del and c.2505del(p.T836Lfs*6) in the PCDH15 gene which might be disease-causing variants, and extending the variant spectra. All above findings may be contribute to genetic counseling, molecular diagnosis and clinical management of arRP disease.

Analysis of PDE6G mutations in a patient with retinitis pigmentosa

BACKGROUND

Mutations in PDE6A and PDE6B are known to cause autosomal recessive RP in humans, On the other hand, mutations in PDE6G are rare but can lead to severe early-onset RP.

CASE PRESENTATION

An 8-year-old Chinese boy was referred to our hospital for poor vision issues. Refraction with cycloplegia showed high hyperopia with astigmatism both eyes. Funduscopic examination revealed typical bone spicule-type pigment deposits in the periphery and midperiphery. The patient was given glasses and a whole exome sequencing containing mitochondrial genes was performed. The results of genetic testing showed that there was a heterozygous frameshift mutation and a segment deletion in the proband's PDE6G gene. Analysis of the parental genes showed that frameshift mutation was inherited from the proband's mother and segment deletion from his father.

CONCLUSIONS

In this paper, we give a firsthand report that the complex heterozygous mutations of PDE6G gene can causes autosomal recessiveRP (arRP), which expands the understanding of the pathogenic genes of RP.

The principles and promising future of sonogenetics for precision medicine

Sonogenetics is an emerging medical technology that uses acoustic waves to control cells through sonosensitive mediators (SSMs) that are genetically encoded, thus remotely and non-invasively modulating specific molecular events and/or biomolecular functions. Sonogenetics has opened new opportunities for targeted spatiotemporal manipulation in the field of gene and cell-based therapies due to its inherent advantages, such as its noninvasive nature, high level of safety, and deep tissue penetration. Sonogenetics holds impressive potential in a wide range of applications, from tumor immunotherapy and mitigation of Parkinsonian symptoms to the modulation of neural reward pathway, and restoration of vision. This review provides a detailed overview of the mechanisms and classifications of established sonogenetics systems and summarizes their applications in disease treatment and management. The review concludes by highlighting the challenges that hinder the further progress of sonogenetics, paving the way for future advances.

Retinitis Pigmentosa and Therapeutic Approaches: A Systematic Review

Background: Retinitis pigmentosa (RP) is a group of hereditary retinal dystrophies characterized by progressive degeneration of photoreceptor cells, which results in debilitating visual impairment. This systematic review aims to evaluate the efficacy and safety of emerging treatment modalities for RP, including gene therapy, mesenchymal-cell-based approaches, and supplementary interventions. Methods: A comprehensive search of electronic databases was conducted to identify relevant studies published up to February 2024. Studies reporting outcomes of treatment interventions for RP, including randomized controlled trials, non-randomized studies, and case series, were included. Data extraction and synthesis were performed according to predefined criteria, focusing on assessing the quality of evidence and summarizing key findings. Results: The search yielded 13 studies meeting inclusion criteria, encompassing diverse treatment modalities and study designs. Gene therapy emerged as a promising therapeutic approach, with several studies reporting favorable outcomes regarding visual function preservation and disease stabilization. Mesenchymal-cell-based therapies also demonstrated potential benefits, although evidence remains limited and heterogeneous. Supplementary interventions, including nutritional supplements and neuroprotective agents, exhibited variable efficacy, with conflicting findings across studies. Conclusions: Despite the lack of definitive curative treatments, emerging therapeutic modalities promise to slow disease progression and preserve visual function in individuals with RP. However, substantial gaps in evidence and heterogeneity in study methodologies underscore the need for further research to elucidate optimal treatment strategies, refine patient selection criteria, and enhance long-term outcomes. This systematic review provides a comprehensive synthesis of current evidence and highlights directions for future research to advance the care and management of individuals with RP.

Gene therapy for retinal diseases: From genetics to treatment

The gene therapy approach for retinal disorders has been considered largely over the last decade owing to the favorable outcomes of the US Food and Drug Administration-approved commercial gene therapy, Luxturna. Technological advances in recent years, such as next-generation sequencing, research in molecular pathogenesis of retinal disorders, and precise correlations with their clinical phenotypes, have contributed to the progress of gene therapies for various diseases worldwide, and more recently in India as well. Thus, considerable research is being conducted for the right choice of vectors, transgene engineering, and accessible and cost-effective large-scale vector production. Many retinal disease-specific clinical trials are presently being conducted, thereby necessitating the collation of such information as a ready reference for the scientific and clinical community. In this article, we present an overview of existing gene therapy research, which is derived from an extensive search across PubMed, Google Scholar, and clinicaltrials.gov sources. This contributes to prime the understanding of basic aspects of this cutting-edge technology and information regarding current clinical trials across many different conditions. This information will provide a comprehensive evaluation of therapies in existing use/research for personalized treatment approaches in retinal disorders.

The genomic mosaic of mitochondrial dysfunction: Decoding nuclear and mitochondrial epigenetic contributions to maternally inherited diabetes and deafness pathogenesis

Aims

Maternally inherited diabetes and deafness (MIDD) is a complex disorder characterized by multiorgan clinical manifestations, including diabetes, hearing loss, and ophthalmic complications. This pilot study aimed to elucidate the intricate interplay between nuclear and mitochondrial genetics, epigenetic modifications, and their potential implications in the pathogenesis of MIDD.

Main methods

A comprehensive genomic approach was employed to analyze a Sicilian family affected by clinically characterized MIDD, negative to the only known causative m.3243 A > G variant, integrating whole-exome sequencing and whole-genome bisulfite sequencing of both nuclear and mitochondrial analyses.

Key findings

Rare and deleterious variants were identified across multiple nuclear genes involved in retinal homeostasis, mitochondrial function, and epigenetic regulation, while complementary mitochondrial DNA analysis revealed a rich tapestry of genetic diversity across genes encoding components of the electron transport chain and ATP synthesis machinery. Epigenetic analyses uncovered significant differentially methylated regions across the genome and within the mitochondrial genome, suggesting a nuanced landscape of epigenetic modulation.

Significance

The integration of genetic and epigenetic data highlighted the potential crosstalk between nuclear and mitochondrial regulation, with specific mtDNA variants influencing methylation patterns and potentially impacting the expression and regulation of mitochondrial genes. This pilot study provides valuable insights into the complex molecular mechanisms underlying MIDD, emphasizing the interplay between nucleus and mitochondrion, tracing the way for future research into targeted therapeutic interventions and personalized approaches for disease management.

Gene Therapy for Retinitis Pigmentosa: Current Challenges and New Progress

Retinitis pigmentosa (RP) poses a significant threat to eye health worldwide, with prevalence rates of 1 in 5000 worldwide. This genetically diverse retinopathy is characterized by the loss of photoreceptor cells and atrophy of the retinal pigment epithelium. Despite the involvement of more than 3000 mutations across approximately 90 genes in its onset, finding an effective treatment has been challenging for a considerable time. However, advancements in scientific research, especially in gene therapy, are significantly expanding treatment options for this most prevalent inherited eye disease, with the discovery of new compounds, gene-editing techniques, and gene loci offering hope for more effective treatments. Gene therapy, a promising technology, utilizes viral or non-viral vectors to correct genetic defects by either replacing or silencing disease-causing genes, potentially leading to complete recovery. In this review, we primarily focus on the latest applications of gene editing research in RP. We delve into the most prevalent genes associated with RP and discuss advancements in genome-editing strategies currently employed to correct various disease-causing mutations.

Intensity-based optoretinography reveals sub-clinical deficits in cone function in retinitis pigmentosa

Introduction

Clinical tools have been widely used in the diagnosis, description, and monitoring the progression of retinitis pigmentosa (RP); however, many of these methods have inherently low sensitivity and specificity, and significant photoreceptor disruption can occur before RP progression has clinically manifest. Adaptive optics scanning light ophthalmoscopy (AOSLO) has shown promise as a powerful tool for assessing photoreceptor disruption both structurally and functionally due to its increased resolution.

Methods

Here we assess photoreceptor structure and function at the cellular level through AOSLO by acquiring intensity based optoretinography (iORG) in 15 individuals with no reported retinal pathology and 7 individuals with a prior clinical diagnosis of RP. Photoreceptor structure was quantified by calculating cone nearest neighbor distance (NND) across different retinal eccentricities from the AOSLO images. Cone outer segment length was measured across different retinal eccentricities using optical coherence tomography (OCT) derived longitudinal reflectivity profiles (LRPs). Finally, iORG measures of photoreceptor function were compared to retinal sensitivity as measured using the macular integrity assessment (MAIA) microperimeter.

Results

Broadly, participants with RP exhibited increasing cone nearest neighbor distances and decreasing cone outer segment length as a function of retinal eccentricity, consistent with prior reports for both controls and individuals with RP. Nearly all individuals with RP had reduced iORG amplitudes for all retinal eccentricities when compared to the control cohort, and the reduction was greater in eccentricities further from the fovea. Comparing iORG amplitudes to MAIA retinal sensitivity, we found that the iORG was more sensitive to early changes in photoreceptor function whereas MAIA was more sensitive to later stages of disease.

Discussion

This highlights the utility of iORG as a method to detect sub-clinical deficits in cone function in all stages of disease progression and supports the future use of iORG for identifying cells that are candidates for cellular based therapies.

VDAC in Retinal Health and Disease

The retina, a tissue of the central nervous system, is vital for vision as its photoreceptors capture light and transform it into electrical signals, which are further processed before they are sent to the brain to be interpreted as images. The retina is unique in that it is continuously exposed to light and has the highest metabolic rate and demand for energy amongst all the tissues in the body. Consequently, the retina is very susceptible to oxidative stress. VDAC, a pore in the outer membrane of mitochondria, shuttles metabolites between mitochondria and the cytosol and normally protects cells from oxidative damage, but when a cell's integrity is greatly compromised it initiates cell death. There are three isoforms of VDAC, and existing evidence indicates that all three are expressed in the retina. However, their precise localization and function in each cell type is unknown. It appears that most retinal cells express substantial amounts of VDAC2 and VDAC3, presumably to protect them from oxidative stress. Photoreceptors express VDAC2, HK2, and PKM2-key proteins in the Warburg pathway that also protect these cells. Consistent with its role in initiating cell death, VDAC is overexpressed in the retinal degenerative diseases retinitis pigmentosa, age related macular degeneration (AMD), and glaucoma. Treatment with antioxidants or inhibiting VDAC oligomerization reduced its expression and improved cell survival. Thus, VDAC may be a promising therapeutic candidate for the treatment of these diseases.

New Improved cGMP Analogues to Target Rod Photoreceptor Degeneration

Retinitis pigmentosa (RP) is a form of retinal degeneration affecting a young population with an unmet medical need. Photoreceptor degeneration has been associated with increased guanosine 3',5'-cyclic monophosphate (cGMP), which reaches toxic levels for photoreceptors. Therefore, inhibitory cGMP analogues attract interest for RP treatments. Here we present the synthesis of dithio-CN03, a phosphorodithioate analogue of cGMP, prepared using the H-phosphonothioate route. Two crystal modifications were identified as a trihydrate and a tetrahydrofuran monosolvates. Dithio-CN03 featured a lower aqueous solubility than its RP-phosphorothioate counterpart CN03, a drug candidate, and this characteristic might be favorable for sustained-release formulations aimed at retinal delivery. Dithio-CN03 was tested in vitro for its neuroprotective effects in photoreceptor models of RP. The comparison of dithio-CN03 to CN03 and its diastereomer SP-CN03, and to their phosphate derivative oxo-CN03 identifies dithio-CN03 as the compound with the highest efficacy in neuroprotection and thus as a promising new candidate for the treatment of RP.

Effect of molecular hydrogen, a novelly-established antioxidant, on the retinal degeneration of hereditary retinitis pigmentosa: an in-vivo study

Objective Our research was performed in order to explore the effects of molecular hydrogen (H2), a novelly-established antioxidant, on the retinal degeneration in rd1 mice, an animal model of inherited retinitis pigmentosa (RP). Methods The rd1 mice were divided randomly into control and H2 intervention groups. Mice from other groups received H2 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. Results The ERG amplitude in mice from the control and H2 intervention groups showed no statistical differences (p > 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 (p > 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 H2 intervention group (p > 0.05). In the aspect of the number of Iba1-positive cells, we did not found any significant differences between the two groups (p > 0.05). Conclusion Different forms of H2 intervention (hydrogen-rich saline and hydrogen gas) had no obvious effects on the course of retinal degeneration in rd1 mice. The specific mechanism of photoreceptor degeneration in the hereditary RP mouse model may be different, requiring different medical interventions.

Mutation analysis of RHO in patients with non-syndromic retinitis pigmentosa

PURPOSE

To identify RHO mutations in patients with non-syndromic retinitis pigmentosa (NS-RP).

METHODS

A total of 143 probands (46 family history and 97 sporadic cases) with NS-RP were recruited from Southeast China. The coding exons and adjacent intronic regions of RHO were PCR-amplified and sequenced by Sanger sequencing. The candidate variant was evaluated by the guidelines of American College of Medical Genetics and further validated through co-segregation analysis within the family.

RESULTS

Five heterozygous mutations in RHO were detected in 5 out of 143 probands, where the frequency of RHO mutations in our cohort was approximately 3.5% (5/143) and 10.8% (5/46) for probands and families with NS-RP, respectively. Three known disease-causing mutations including c.C1030T (p.Q344X), c.C173G (p.T58R), and c.G266A (p.G89D) were identified in three unrelated families. The other two previously unreported mutations c.557C>A (p.S186X) and c.944delA (p.N315TfsX43) were confirmed in Family RP-087 and Family RP-139, respectively. These mutations co-segregated with available affected individuals in each family were not observed in the unaffected family members or in the 112 unrelated controls.

CONCLUSIONS

This report expands the mutational spectrum of RHO gene associated with NS-RP and demonstrates the frequency of RP RHO mutations in Southeast Chinese populations.

Emerging role of ferroptosis in diabetic retinopathy: a review

BACKGROUND

Diabetic retinopathy (DR) is a significant complication of diabetes and the primary cause of blindness among working age adults globally. The development of DR is accompanied by oxidative stress, characterised by an overproduction of reactive oxygen species (ROS) and a compromised antioxidant system. Clinical interventions aimed at mitigating oxidative stress through ROS scavenging or elimination are currently available. Nevertheless, these treatments merely provide limited management over the advanced stage of the illness. Ferroptosis is a distinctive form of cell death induced by oxidative stress, which is characterised by irondependent phospholipid peroxidation.

PURPOSE

This review aims to synthesise recent experimental evidence to examine the involvement of ferroptosis in the pathological processes of DR, as well as to explicate the regulatory pathways governing oxidative stress and ferroptosis in retina.

METHODS

We systematically reviewed literature available up to 2023.

RESULTS

This review included 12 studies investigating the involvement of ferroptosis in DR.

Navigating the future of retinitis pigmentosa treatments: A comprehensive analysis of therapeutic approaches in rd10 mice

Retinitis pigmentosa (RP) is a degenerative disease, caused by genetic mutations that lead to a loss in photoreceptors. For research on RP, rd10 mice, which carry mutations in the phosphodiesterase (PDE) gene, exhibit degenerative patterns comparable to those of patients with RP, making them an ideal model for investigating potential treatments. Although numerous studies have reported the potential of biochemical drugs, gene correction, and stem cell transplantation in decelerating rd10 retinal degeneration, a comprehensive review of these studies has yet to be conducted. Therefore, here, a comparative analysis of rd10 mouse treatment research over the past decade was performed. Our findings suggest that biochemical drugs capable of inhibiting the inflammatory response may be promising therapeutics. Additionally, significant progress has been made in the field of gene therapy; nevertheless, challenges such as strict delivery requirements, bystander editing, and off-target effects still need to be resolved. Nevertheless, secretory function is the only unequivocal protective effect of stem cell transplantation. In summary, this review presents a comprehensive analysis and synthesis of the treatment approaches employing rd10 mice as experimental subjects, describing a clear pathway for future RP treatment research and identifies potential clinical interventions.

Cell therapy for retinal degenerative disorders: a systematic review and three-level meta-analysis

BACKGROUND

Retinal degenerative disorders (RDDs) cause vision loss by damaging retinal neurons and photoreceptors, affecting individuals of all ages. Cell-based therapy has emerged as an effective approach for the treatment of RDDs with promising results. This meta-analysis aims to comprehensively evaluate the efficacy of cell therapy in treating age-related macular degeneration (AMD), retinitis pigmentosa (RP), and Stargardt macular degeneration (SMD) as the most prevalent RDDs.

METHODS

PubMed, Scopus, Web of Science, and Embase were searched using keywords related to various retinal diseases and cell therapy treatments until November 25th, 2023. The studies' quality was evaluated using the Joanna Briggs Institute's (JBI) checklist for quasi-experimental studies. Visual acuity measured as LogMAR score was used as our main outcome. A three-level random-effect meta-analysis was used to explore the visual acuity in patients who received cell-based therapy. Heterogeneity among the included studies was evaluated using subgroup and sensitivity analyses. Moreover, meta-regression for the type of cells, year of publication, and mean age of participants were performed.

RESULTS

Overall, 8345 studies were retrieved by the search, and 39 met the eligibility criteria, out of which 18 studies with a total of 224 eyes were included in the meta-analysis. There were 12 studies conducted on AMD, 7 on SMD, and 2 on RP. Cell therapy for AMD showed significant improvement in LogMAR (p < 0.05). Also, cell therapy decreased the LogMAR score in SMD and RP (p < 0.01 and p < 0.0001, respectively). Across all conditions, no substantial publication bias was detected (p < 0.05).

CONCLUSION

The findings of the study highlight that the application of cell therapy can enhance the visual acuity in AMD, SMD, and RP.

Stop codon readthrough as a treatment option for epidermolysis bullosa-Where we are and where we are going

In the context of rare genetic diseases caused by nonsense mutations, the concept of induced stop codon readthrough (SCR) represents an attractive avenue in the ongoing search for improved treatment options. Epidermolysis bullosa (EB)-exemplary for this group of diseases-describes a diverse group of rare, blistering genodermatoses. Characterized by extreme skin fragility upon minor mechanical trauma, the most severe forms often result from nonsense mutations that lead to premature translation termination and loss of function of essential proteins at the dermo-epidermal junction. Since no curative interventions are currently available, medical care is mainly limited to alleviating symptoms and preventing complications. Complementary to attempts of gene, cell and protein therapy in EB, SCR represents a promising medical alternative. While gentamicin has already been examined in several clinical trials involving EB, other potent SCR inducers, such as ataluren, may also show promise in treating the hitherto non-curative disease. In addition to the extensively studied aminoglycosides and their derivatives, several other substance classes-non-aminoglycoside antibiotics and non-aminoglycoside compounds-are currently under investigation. The extensive data gathered in numerous in vitro experiments and the perspectives they reveal in the clinical setting will be discussed in this review.

Open-Angle and Steroid-Induced Glaucoma in Patients With Retinitis Pigmentosa: A Dangerous Liaison

Previous studies have reported that patients with retinitis pigmentosa (RP) may develop open-angle and angle-closure glaucoma. We conducted a chart review of patients with RP. Two siblings with RP associated with a mutation in the PDE6B gene (c. 1540del, p.Leu514Trpfs*61) developed cystoid macular edema (CME) as part of the disease. For this reason, they both underwent intravitreal steroid injections. Both brothers developed steroid-induced glaucoma (SIG). Despite undergoing maximal medical therapy, they underwent seton implants to control their intraocular pressure. A third female patient with RP due to a mutation in the RPGR gene underwent cataract surgery. Topical steroids were prescribed and developed SIG. Increased intraocular pressure remains a complication of topical, injected, and systemic steroids. However, steroids may be needed to treat post-operatively and patients with CME. This case series unveils a complex association between RP and key comorbidities in these patients, with a focus on cataracts, glaucoma, and macular edema. Cataract surgery in patients with RP shows a link to the emergence of glaucoma, particularly in those with RPGR and PDE6B gene mutations, revealing a novel association with PDE6B mutations not previously documented. Furthermore, the paper explores a unique parallel with Schwartz-Matsuo syndrome, suggesting that patients with RP undergoing cataract surgery may develop increased intraocular pressure due to an outflow disturbance akin to Schwartz syndrome. This novel perspective deepens our understanding of the pathophysiological mechanisms governing intraocular pressure dynamics in patients with RP. To our knowledge, this is the first report of steroid-induced glaucoma in patients with RP due to mutations in the PDE6B gene. Intraocular pressure evaluation remains of utmost importance in the follow-up of patients with the disease.

Understanding the prion-like behavior of mutant p53 proteins in triple-negative breast cancer pathogenesis: The current therapeutic strategies and future directions

Breast cancer (BC) is viewed as a significant public health issue and is the primary cause of cancer-related deaths among women worldwide. Triple-negative breast cancer (TNBC) is a particularly aggressive subtype that predominantly affects young premenopausal women. The tumor suppressor p53 playsa vital role in the cellular response to DNA damage, and its loss or mutations are commonly present in many cancers, including BC. Recent evidence suggests that mutant p53 proteins can aggregate and form prion-like structures, which may contribute to the pathogenesis of different types of malignancies, such as BC. This review provides an overview of BC molecular subtypes, the epidemiology of TNBC, and the role of p53 in BC development. We also discuss the potential implications of prion-like aggregation in BC and highlight future research directions. Moreover, a comprehensive analysis of the current therapeutic approaches targeting p53 aggregates in BC treatment is presented. Strategies including small molecules, chaperone inhibitors, immunotherapy, CRISPR-Cas9, and siRNA are discussed, along with their potential benefits and drawbacks. The use of these approaches to inhibit p53 aggregation and degradation represents a promising target for cancer therapy. Future investigations into the efficacy of these approaches against various p53 mutations or binding to non-p53 proteins should be conducted to develop more effective and personalized therapies for BC treatment.

The mechanistic functional landscape of retinitis pigmentosa: a machine learning-driven approach to therapeutic target discovery

BACKGROUND

Retinitis pigmentosa is the prevailing genetic cause of blindness in developed nations with no effective treatments. In the pursuit of unraveling the intricate dynamics underlying this complex disease, mechanistic models emerge as a tool of proven efficiency rooted in systems biology, to elucidate the interplay between RP genes and their mechanisms. The integration of mechanistic models and drug-target interactions under the umbrella of machine learning methodologies provides a multifaceted approach that can boost the discovery of novel therapeutic targets, facilitating further drug repurposing in RP.

METHODS

By mapping Retinitis Pigmentosa-related genes (obtained from Orphanet, OMIM and HPO databases) onto KEGG signaling pathways, a collection of signaling functional circuits encompassing Retinitis Pigmentosa molecular mechanisms was defined. Next, a mechanistic model of the so-defined disease map, where the effects of interventions can be simulated, was built. Then, an explainable multi-output random forest regressor was trained using normal tissue transcriptomic data to learn causal connections between targets of approved drugs from DrugBank and the functional circuits of the mechanistic disease map. Selected target genes involvement were validated on rd10 mice, a murine model of Retinitis Pigmentosa.

RESULTS

A mechanistic functional map of Retinitis Pigmentosa was constructed resulting in 226 functional circuits belonging to 40 KEGG signaling pathways. The method predicted 109 targets of approved drugs in use with a potential effect over circuits corresponding to nine hallmarks identified. Five of those targets were selected and experimentally validated in rd10 mice: Gabre, Gabra1 (GABARα1 protein), Slc12a5 (KCC2 protein), Grin1 (NR1 protein) and Glr2a. As a result, we provide a resource to evaluate the potential impact of drug target genes in Retinitis Pigmentosa.

CONCLUSIONS

The possibility of building actionable disease models in combination with machine learning algorithms to learn causal drug-disease interactions opens new avenues for boosting drug discovery. Such mechanistically-based hypotheses can guide and accelerate the experimental validations prioritizing drug target candidates. In this work, a mechanistic model describing the functional disease map of Retinitis Pigmentosa was developed, identifying five promising therapeutic candidates targeted by approved drug. Further experimental validation will demonstrate the efficiency of this approach for a systematic application to other rare diseases.

Posterior Polar Annular Choroidal Dystrophy: Genetic Insights and Differential Diagnosis in Inherited Retinal Diseases

Posterior polar annular choroidal dystrophy (PPACD) is a rare ocular disorder and presents as symmetric degeneration of the retinal pigment epithelium (RPE) and the underlying choriocapillaris, encircling the retinal vascular arcades and optic disc. This condition distinctively preserves the foveal region, optic disc, and the outermost regions of the retina. Despite its distinct clinical presentation, due to the infrequency of its occurrence and the limited number of reported cases, the pathophysiology, and the genetic foundations of PPACD are still largely uncharted. This review aims to bridge this knowledge gap by investigating potential genetic contributors to PPACD, assessing current findings, and identifying genes that warrant further study. Emphasis is also placed on the crucial role of multimodal imaging in diagnosing PPACD, highlighting its importance in understanding disease pathophysiology. By analyzing existing case reports and drawing comparisons with similar retinal disorders, this paper endeavors to delineate the possible genetic correlations in PPACD, providing a foundation for future genetic research and the development of targeted diagnostic strategies.

Piceid Octanoate Protects Retinal Cells against Oxidative Damage by Regulating the Sirtuin 1/Poly-ADP-Ribose Polymerase 1 Axis In Vitro and in rd10 Mice

Retinitis pigmentosa is a common cause of inherited blindness in adults, which in many cases is associated with an increase in the formation of reactive oxygen species (ROS) that induces DNA damage, triggering Poly-ADP-Ribose Polymerase 1 (PARP1) activation and leading to parthanatos-mediated cell death. Previous studies have shown that resveratrol (RSV) is a promising molecule that can mitigate PARP1 overactivity, but its low bioavailability is a limitation for medical use. This study examined the impact of a synthesized new acylated RSV prodrug, piceid octanoate (PIC-OCT), in the 661W cell line against H2O2 oxidative stress and in rd10 mice. PIC-OCT possesses a better ADME profile than RSV. In response to H2O2, 661W cells pretreated with PIC-OCT preserved cell viability in more than 38% of cells by significantly promoting SIRT1 nuclear translocation, preserving NAD+/NADH ratio, and suppressing intracellular ROS formation. These effects result from expressing antioxidant genes, maintaining mitochondrial function, reducing PARP1 nuclear expression, and preventing AIF nuclear translocation. In rd10 mice, PIC-OCT inhibited PAR-polymer formation, increased SIRT1 expression, significantly reduced TUNEL-positive cells in the retinal outer nuclear layer, preserved ERGs, and enhanced light chamber activity (all p values < 0.05). Our findings corroborate that PIC-OCT protects photoreceptors by modulating the SIRT1/PARP1 axis in models of retinal degeneration.

Retinitis Pigmentosa: From Pathomolecular Mechanisms to Therapeutic Strategies

Retinitis pigmentosa is an inherited disease, in which mutations in different types of genes lead to the death of photoreceptors and the loss of visual function. Although retinitis pigmentosa is the most common type of inherited retinal dystrophy, a clear line of therapy has not yet been defined. In this review, we will focus on the therapeutic aspect and attempt to define the advantages and disadvantages of the protocols of different therapies. The role of some therapies, such as antioxidant agents or gene therapy, has been established for years now. Many clinical trials on different genes and mutations causing RP have been conducted, and the approval of voretigene nepavorec by the FDA has been an important step forward. Nonetheless, even if gene therapy is the most promising type of treatment for these patients, other innovative strategies, such as stem cell transplantation or hyperbaric oxygen therapy, have been shown to be safe and improve visual quality during clinical trials. The treatment of this disease remains a challenge, to which we hope to find a solution as soon as possible.

Beyond Vision: An Overview of Regenerative Medicine and Its Current Applications in Ophthalmological Care

Regenerative medicine (RM) has emerged as a promising and revolutionary solution to address a range of unmet needs in healthcare, including ophthalmology. Moreover, RM takes advantage of the body's innate ability to repair and replace pathologically affected tissues. On the other hand, despite its immense promise, RM faces challenges such as ethical concerns, host-related immune responses, and the need for additional scientific validation, among others. The primary aim of this review is to present a high-level overview of current strategies in the domain of RM (cell therapy, exosomes, scaffolds, in vivo reprogramming, organoids, and interspecies chimerism), centering around the field of ophthalmology. A search conducted on clinicaltrials.gov unveiled a total of at least 209 interventional trials related to RM within the ophthalmological field. Among these trials, there were numerous early-phase studies, including phase I, I/II, II, II/III, and III trials. Many of these studies demonstrate potential in addressing previously challenging and degenerative eye conditions, spanning from posterior segment pathologies like Age-related Macular Degeneration and Retinitis Pigmentosa to anterior structure diseases such as Dry Eye Disease and Limbal Stem Cell Deficiency. Notably, these therapeutic approaches offer tailored solutions specific to the underlying causes of each pathology, thus allowing for the hopeful possibility of bringing forth a treatment for ocular diseases that previously seemed incurable and significantly enhancing patients' quality of life. As advancements in research and technology continue to unfold, future objectives should focus on ensuring the safety and prolonged viability of transplanted cells, devising efficient delivery techniques, etc.

A pedigree with retinitis pigmentosa and its concomitant ophthalmic diseases

AIM

To characterize the ophthalmic clinical phenotype of a family with retinitis pigmentosa (RP) and closed-angle glaucoma and to detect pathogenic genes and mutation sites causing RP in this family.

METHODS

Ophthalmic clinic performance was examined in detail in 8 enrolled family members. Genomic DNA was extracted from the peripheral blood of 4 family members for whole-exome sequencing (WES) to select potential genetic mutations whose structures were identified by bioinformatics analysis. Then, Sanger sequencing was used in 12 family members and control group members to validate and confirm the disease-causing mutation loci, and we analyzed the genotype-phenotype relationships.

RESULTS

The known c.512C>T (p.P171L) mutation in the rhodopsin (RHO) gene was only found in afflicted family members and was confirmed by WES and Sanger sequencing as the pathogenic mutation in this family. In addition to being diagnosed with RP, family member III:4 was found to have bilateral closed-angle glaucoma, high myopia, and concurrent cataracts, and family members II:2 and II:4 had pathological changes of anterior chamber angle narrowing. Family members IV:3 and IV:4 were found to have retinoschisis.

CONCLUSION

Glaucoma and related pathological changes, such as retinoschisis, in family members are preliminarily considered RP complications caused by RHO mutation.

Oxidative stress in the eye and its role in the pathophysiology of ocular diseases

Oxidative stress occurs through an imbalance between the generation of reactive oxygen species (ROS) and the antioxidant defense mechanisms of cells. The eye is particularly exposed to oxidative stress because of its permanent exposure to light and due to several structures having high metabolic activities. The anterior part of the eye is highly exposed to ultraviolet (UV) radiation and possesses a complex antioxidant defense system to protect the retina from UV radiation. The posterior part of the eye exhibits high metabolic rates and oxygen consumption leading subsequently to a high production rate of ROS. Furthermore, inflammation, aging, genetic factors, and environmental pollution, are all elements promoting ROS generation and impairing antioxidant defense mechanisms and thereby representing risk factors leading to oxidative stress. An abnormal redox status was shown to be involved in the pathophysiology of various ocular diseases in the anterior and posterior segment of the eye. In this review, we aim to summarize the mechanisms of oxidative stress in ocular diseases to provide an updated understanding on the pathogenesis of common diseases affecting the ocular surface, the lens, the retina, and the optic nerve. Moreover, we discuss potential therapeutic approaches aimed at reducing oxidative stress in this context.

Application of patient-derived induced pluripotent stem cells and organoids in inherited retinal diseases

Inherited retinal diseases (IRDs) can induce severe sight-threatening retinal degeneration and impose a considerable economic burden on patients and society, making efforts to cure blindness imperative. Transgenic animals mimicking human genetic diseases have long been used as a primary research tool to decipher the underlying pathogenesis, but there are still some obvious limitations. As an alternative strategy, patient-derived induced pluripotent stem cells (iPSCs), particularly three-dimensional (3D) organoid technology, are considered a promising platform for modeling different forms of IRDs, including retinitis pigmentosa, Leber congenital amaurosis, X-linked recessive retinoschisis, Batten disease, achromatopsia, and best vitelliform macular dystrophy. Here, this paper focuses on the status of patient-derived iPSCs and organoids in IRDs in recent years concerning disease modeling and therapeutic exploration, along with potential challenges for translating laboratory research to clinical application. Finally, the importance of human iPSCs and organoids in combination with emerging technologies such as multi-omics integration analysis, 3D bioprinting, or microfluidic chip platform are highlighted. Patient-derived retinal organoids may be a preferred choice for more accurately uncovering the mechanisms of human retinal diseases and will contribute to clinical practice.

An update on visual prosthesis

PURPOSE

To review the available evidence on the different retinal and visual prostheses for patients with retinitis pigmentosa and new implants for other indications including dry age-related macular degeneration.

METHODS

The PubMed, GoogleScholar, ScienceDirect, and ClinicalTrials databases were the main resources used to conduct the medical literature search. An extensive search was performed to identify relevant articles concerning the worldwide advances in retinal prosthesis, clinical trials, status of devices and potential future directions up to December 2022.

RESULTS

Thirteen devices were found to be current and were ordered by stimulation location. Six have active clinical trials. Four have been discontinued, including the Alpha IMS, Alpha AMS, IRIS II, and ARGUS II which had FDA and CE mark approval. Future directions will be presented in the review.

CONCLUSION

This review provides an update of retinal prosthetic devices, both current and discontinued. While some devices have achieved visual perception in animals and/or humans, the main issues impeding the commercialization of these devices include: increased length of time to observe outcomes, difficulties in finding validated meaures for use in studies, unknown long-term effects, lack of funding, and a low amount of patients simultaneously diagnosed with RP lacking other comorbid conditions. The ARGUS II did get FDA and CE mark approval so it was deemed safe and also effective. However, the company became more focused on a visual cortical implant. Future efforts are headed towards more biocompatible, safe, and efficacious devices.

Endothelial Notch Signaling Regulates the Function of the Retinal Pigment Epithelial Barrier via EC Angiocrine Signaling

The outer blood-retina barrier (oBRB), comprises tightly connected retinal pigment epithelium (RPE) cells, Bruch's membrane, and choroid blood vessels, and is essential for retinal health and normal visual function. Disruption of the RPE barrier and its dysfunction can lead to retinal disorders such as age-related macular degeneration (AMD). In the present study, we investigated the essential role of choroid endothelial cells (ECs) in the RPE barrier formation process and its dysfunction. We discovered that ECs promoted RPE barrier formation through angiocrine signaling. Through blocking or activating endothelial Notch signaling and conducting experiments in vitro and in vivo, we confirmed that endothelial Notch signaling regulated the expression of heparin-binding epidermal growth factor (HBEGF) and consequently impacted the expression and activity of matrix metalloproteinases (MMP)-9 in RPE cells. This modulation influenced the RPE extracellular matrix deposition, tight junctions and RPE barrier function. In in vivo experiments, the intravitreal administration of recombinant HBEGF (r-HBEGF) alleviated the RPE barrier disruption induced by subretinal injection (SI) or laser treatment and also rescued RPE barrier disruption in endothelial Notch-deficient mice. Our results showed that the endothelial Notch signaling drove HBEGF expression through angiocrine signaling and effectively improved RPE barrier function by regulating the MMP-9 expression in RPE cells. It suggests that the modulation of Notch signaling in the choroidal endothelium may offer a novel therapeutic strategy for retinal degenerative diseases.

Human Neural Progenitors Expressing GDNF Enhance Retinal Protection in a Rodent Model of Retinal Degeneration

Stem cell therapy for retinal degenerative diseases has been extensively tested in preclinical and clinical studies. However, preclinical studies performed in animal models at the early stage of disease do not optimally translate to patients that present to the clinic at a later stage of disease. As the retina degenerates, inflammation and oxidative stress increase and trophic factor support declines. Testing stem cell therapies in animal models at a clinically relevant stage is critical for translation to the clinic. Human neural progenitor cells (hNPC) and hNPC engineered to stably express GDNF (hNPCGDNF) were subretinally injected into the Royal College of Surgeon (RCS) rats, a well-established model for retinal degeneration, at early and later stages of the disease. hNPCGDNF treatment at the early stage of retinal degeneration provided enhanced visual function compared to hNPC alone. Treatment with both cell types resulted in preserved retinal morphology compared to controls. hNPCGDNF treatment led to significantly broader photoreceptor protection than hNPC treatment at both early and later times of intervention. The phagocytic role of hNPC appears to support RPE cell functions and the secreted GDNF offers neuroprotection and enables the extended survival of photoreceptor cells in transplanted animal eyes. Donor cells in the RCS rat retina survived with only limited proliferation, and hNPCGDNF produced GDNF in vivo. Cell treatment led to significant changes in various pathways related to cell survival, antioxidative stress, phagocytosis, and autophagy. A combined stem cell and trophic factor therapy holds great promise for treating retinal degenerative diseases including retinitis pigmentosa and age-related macular degeneration.