Molecular Vision最新文献

Bietti crystalline dystrophy (BCD), an autosomal recessive inherited retinal disorder caused by mutations in the CYP4V2 gene, has long remained therapeutically challenging. Recent advances in adeno-associated virus-based gene therapy have emerged as promising therapeutic strategies for patients with BCD. This review synthesizes current knowledge regarding the molecular genetic mechanisms underlying BCD pathogenesis and examines recent developments in diagnostic approaches and gene therapeutic interventions. We specifically analyze the clinical outcomes of three investigational gene therapy products-ZVS101e, NGGT001, and VGR-R01-focusing on their preliminary efficacy, safety profiles, and tolerability. Key parameters evaluated include dosing strategies, routes of administration, adverse event profiles, and improvements in best-corrected visual acuity. The collective evidence suggests these therapeutic candidates show potential for decelerating disease progression and enhancing visual function. Future optimization of these approaches should carefully consider administration sites and modalities, injection volumes, and disease severity at intervention. With gene replacement therapy for BCD advancing through late-stage clinical development, regulatory approval and clinical implementation may be anticipated in the near future.

Purpose: Cysteinyl leukotriene receptor 1 (CysLTR1), originally described as a proinflammatory G protein-coupled receptor, has been shown to possess diverse nonimmunological properties. One of these functions is to modulate glucose-stimulated insulin secretion in β cells. Furthermore, the inhibition of CysLTR1 increases retinal cell survival in early diabetic retinopathy. Nevertheless, the potential of CysLTR1 to modulate glucose levels in retinal vascular cells, such as endothelial cells (ECs) and pericytes (PCs), is unknown. Therefore, we determined the intracellular glucose levels in retinal cells in vitro after the inhibition of CysLTR1 under standard and high-glucose culture conditions.

Methods: Primary human ECs, PCs, and the ARPE-19 cell line were cultured under standard (5.5 mmol/l glucose + 27.5 mmol/l mannitol) and high-glucose (33.0 mmol/l) conditions in the absence and presence of the specific CysLTR1 antagonists montelukast and zafirlukast for 1, 3, and 7 days. CysLTR1 expression was determined by immunofluorescence microscopy. CysLT secretion was measured by enzyme-linked immunosorbent assay. The effects of high glucose and CysLTR1 inhibition on cell viability and intracellular glucose levels were analyzed by luminescence-based assays. Furthermore, the transendothelial and transepithelial electrical resistance of the ECs and ARPE-19 monolayers was measured.

Results: CysLTR1 inhibition under standard glucose culture conditions increased the cellular glucose levels in retinal ECs, PCs, and ARPE-19 cells after 1 and 3 days of treatment. Under high-glucose culture conditions, CysLTR1 inhibition for 1 day reduced the intracellular glucose level in ARPE-19 cells. However, CysLTR1 inhibition for 3 days increased the level of intracellular glucose in ARPE-19 cells under high-glucose culture conditions. Furthermore, CysLTR1 inhibition reduced the tightness of the EC and ARPE-19 monolayers under standard culture conditions but increased the tightness of the ARPE-19 monolayers under high-glucose conditions.

Conclusions: CysLTR1 is considered a potential target for the treatment of type 2 diabetes and early diabetic retinopathy. Our data revealed that CysLTR1 activity directly regulates cellular glucose levels in retinal cells, supporting these hypotheses. Interestingly, the effect of CysLTR1 activity on glucose levels was reversed under acute metabolic stress. Thus, the activity of CysLTR1 appears to be more complex in terms of glucose metabolism and needs to be studied in more detail.

Purpose: Hair anomalies represent a common associated symptom of congenital cataracts. Early diagnosis is crucial for treatment and predicting prognosis. However, the insidious and nonspecific nature of the symptoms in young children makes diagnosis challenging, often necessitating tools such as whole-exome sequencing (WES) for accurate assessment. This study aims to propose a simple and expedient approach to guide clinical management by analyzing phenotype-genotype correlations.

Methods: A prospective cohort study was conducted among participants who underwent clinical examinations and WES between 2021 and 2023. Bioinformatic analysis was performed. In total, 170 unrelated congenital cataract probands were tested. The suspected pathogenic variants were validated through Sanger sequencing in both the probands and available family members. Correlation analyses were then performed, integrating clinical characteristics, cataract phenotype, and genotype data.

Results: Nine probands presented with both cataracts and hair anomalies. Potential pathogenic variants were detected in all patients with hair anomalies, including a novel variant in LSS. Phenotype-genotype analysis supports the classification of patients into two groups: hypotrichosis 14 and ichthyosis follicularis with atrichia and photophobia syndrome 2, based on the cataract phenotype, severity of the hair anomalies, and the presence of corneal pannus. These patients should be monitored closely for the development and progression of glaucoma and corneal lesions.

Conclusions: We identified nine probands with hair anomalies in our large cohort of congenital cataract probands. Using WES and comprehensive clinical examinations, we established definitive diagnoses, broadened the phenotype and genotype, and proposed phenotype-genotype correlations.

Purpose: To characterize the aggregation behavior of the γD-crystallin protein in an acidic environment with a focus on the formation of intermediate species. The research employs fluorescence correlation spectroscopy to unravel the intricate molecular events leading to aggregation, contributing to a comprehensive understanding of cataract formation.

Methods: The kinetics of γD-crystallin protein aggregation were studied with a reversed-phase high-performance liquid chromatography sedimentation assay, a ThT binding assay, and light scattering. We used fluorescence correlation spectroscopy (FCS) to recognize intermediate aggregate species and characterized them with Fourier transform infrared spectroscopy (FTIR). Further, the morphologic characterization of aggregates was done by transmission electron microscopy (TEM), and their hydrophobic characteristics were analyzed using the 8-anilino-1-naphthalenesulfonic acid binding assay.

Results: A negligible lag phase was observed in the aggregation kinetic experiments of the γD-crystallin protein. Pentamer, 25-mer, and higher oligomer intermediates were formed on the aggregation pathway. Conformation studies by FCS and FTIR have shown that oligomers are rich in cross-β sheet and random coil structure; however, they constitute more α-helix and less cross-β sheet structure than fibrils. TEM analysis revealed the approximate size of oligomers (diameter ~10 nm), protofibrils (~15 nm), and fibrils (~15 to ~35 nm).

Conclusions: In this study, we reported the presence of various intermediate aggregate species formed on the aggregation pathway of γD-crystallin protein at low pH. This will open new areas of research in understanding the detailed aggregation mechanism and aggregation hotspot within unfolded γD-crystallin monomers. The insights gained will also pave the way for future research in the realm of amyloid formation in cataract.

Purpose: Cyclic nucleotide-gated (CNG) channels are ligand-gated ion channels that transduce light signals into electrical signals in the retinal photoreceptors. Pathogenic variants in CNG channel genes are reported to cause inherited retinal dystrophies (IRDs). The current study used targeted panel sequencing to describe the mutational spectrum of CNG channel genes in familial cases of IRDs from eight consanguineous Pakistani families.

Methods: The current study included consanguineous Pakistani families with at least two affected members. DNA was extracted from whole blood samples by the phenol-chloroform method. Two affected members from each family were initially analyzed using targeted panel sequencing of 344 known IRD genes. The pathogenicity of candidate variants was assessed using the American College of Medical Genetics and Genomics guidelines. Segregation testing was performed by Sanger sequencing.

Results: Results of eight IRD families revealed a total of four reported variants in CNGA3 (c.827A>G, c.955T>C, c.1641C>A, c.1810C>T) and three novel variants, including c.1633A>T, c.800G>T, and c.1153T>C in CNGA1, CNGA3, and CNGB3 genes, respectively, segregating in each respective family. Among disease-causing variants identified in our study cohort, 87.5% were missense. Furthermore, one of the reported missense variants (i.e., c.1641C>A in CNGA3) was segregating in two unrelated families. All identified variants were homozygous and segregated in an autosomal recessive form.

Conclusions: CNGA3 was the most frequently mutated gene in our study cohort. Only the c.1641C>A variant of CNGA3 was repeated in two families, showing genetic diversity. The identification of three novel pathogenic variants in CNG channel genes in the present study reaffirms the allelic and genetic heterogeneity of IRDs in the Pakistani population.

Purpose: To characterize the aggregation behavior of the γD-crystallin protein in an acidic environment with a focus on the formation of intermediate species. The research employs fluorescence correlation spectroscopy to unravel the intricate molecular events leading to aggregation, contributing to a comprehensive understanding of cataract formation.

Methods: The kinetics of γD-crystallin protein aggregation were studied with a reversed-phase high-performance liquid chromatography sedimentation assay, a ThT binding assay, and light scattering. We used fluorescence correlation spectroscopy (FCS) to recognize intermediate aggregate species and characterized them with Fourier transform infrared spectroscopy (FTIR). Further, the morphologic characterization of aggregates was done by transmission electron microscopy (TEM), and their hydrophobic characteristics were analyzed using the 8-anilino-1-naphthalenesulfonic acid binding assay.

Results: A negligible lag phase was observed in the aggregation kinetic experiments of the γD-crystallin protein. Pentamer, 25-mer, and higher oligomer intermediates were formed on the aggregation pathway. Conformation studies by FCS and FTIR have shown that oligomers are rich in cross-β sheet and random coil structure; however, they constitute more α-helix and less cross-β sheet structure than fibrils. TEM analysis revealed the approximate size of oligomers (diameter ~10 nm), protofibrils (~15 nm), and fibrils (~15 to ~35 nm).

Conclusions: In this study, we reported the presence of various intermediate aggregate species formed on the aggregation pathway of γD-crystallin protein at low pH. This will open new areas of research in understanding the detailed aggregation mechanism and aggregation hotspot within unfolded γD-crystallin monomers. The insights gained will also pave the way for future research in the realm of amyloid formation in cataract.

Purpose: Members of a multigenerational Canadian family presented to an inherited retinal degeneration (IRD) clinic with retinitis pigmentosa (RP) and sensorineural hearing loss, reminiscent of an Usher syndrome phenotype. Biallelic disease-causing variants in the known Usher syndrome genes were not identified. Therefore, we enrolled further family members in this study and examined whether other IRD gene variants could explain the phenotype in the family.

Methods: Family members underwent a comprehensive ophthalmic examination, including best-corrected visual acuity, direct and indirect ophthalmoscopy, fundus photography, visual field testing, spectral-domain optical coherence tomography, audiological examination, and genetic testing. Some patients also had autofluorescence imaging. Loss-of-function testing was initiated by antisense morpholino knockdown of tubb4b in zebrafish.

Results: Multimodal clinical testing in affected patients revealed an autosomal dominant late-onset presentation of RP associated with progressive, bilateral sensorineural hearing loss that occurred in the second to third decades of life with no vestibular involvement. Panel-based genetic testing revealed a heterozygous c.1168C>T, p.Arg390Trp variant in the beta-tubulin 4B gene (TUBB4B) only in affected family members. Based on in silico analysis, segregation analysis through the family, and literature evaluation, this variant is likely to be the disease-causing variant inherited in an autosomal dominant manner. We searched our local database of ~1,000 patients with IRD, and no other TUBB4B variants were identified, confirming this is a rare disease variant. Knockdown of tubb4b in zebrafish revealed cone and rod photoreceptor abnormalities in the retina and hydrocephalus in the developing brain, resulting in early larval lethality.

Conclusions: For the first time, we describe a multigenerational family with a TUBB4B gene variant p.(Arg390Trp) segregating with deaf-blindness, establishing autosomal dominant inheritance. This further confirms that the Arg390 codon is a mutation hotspot. We also expand the range of phenotypes seen with the p.(Arg390Trp) TUBB4B gene variant to include typical RP as well as a milder, pericentral RP. Furthermore, our studies suggest there is conservation of TUBB4B ciliary function between zebrafish and humans, making zebrafish a better model system for studying vision loss than the mouse model.

Objective: This study aimed to explore the effects and mechanisms of ursolic acid (UA) on oxygen-induced retinal neovascularization (RNV) in mice and its inhibitory effects on human retinal capillary endothelial cells (HRCECs) under high-glucose conditions.

Methods: Neonatal mice were divided into five groups: one normal group and four with oxygen-induced retinopathy (OIR), including OIR, phosphate-buffered saline, UA and Lucentis groups. On postnatal day 17 (P17), mice were euthanized and one eye was collected for retinal analysis using fluorescence microscopy. Protein and messenger ribonucleic acid (mRNA) levels of vascular endothelial growth factor (VEGF), matrix metalloproteinase (MMP)-2, MMP-9 and cyclo-oxygenase-2 (COX-2) were detected. HRCECs cultured under high-glucose conditions were treated with UA to assess its effects on proliferation and molecular expression.

Results: UA significantly reduced RNV area in OIR mice and protected astrocytes from hypoxia-induced damage (p<0.01). VEGF, MMP-2, MMP-9 and COX-2 levels were lower in the UA group compared with the OIR and phosphate-buffered saline groups (p<0.05), but slightly higher than in normal controls (p<0.01). Lucentis reduced VEGF levels but did not significantly affect MMP-2, MMP-9 or COX-2. In HRCECs, UA inhibited high-glucose-induced proliferation and reduced VEGF, MMP-2, MMP-9 and COX-2 expression in a time- and dose-dependent manner.

Conclusions: UA inhibits RNV by reducing VEGF, MMP-2, MMP-9 and COX-2 expression, protecting astrocytes and suppressing HRCEC proliferation under high-glucose conditions, highlighting its therapeutic potential for retinal neovascular diseases.

Purpose: A genetic disorder that affects the beta subunit of cyclic guanosine monophosphate-phosphodiesterase type 6 (PDE6B) in humans leads to autosomal recessive retinitis pigmentosa (RP). This condition causes severe vision loss in early life due to fast deterioration of photoreceptors. This study evaluated the therapeutic potential of subretinal delivery of the adeno-associated virus (AAV)5-mediated human Pde6b gene in an RP rat model caused by Pde6b gene knockout (KO).

Methods: We compared the transduction efficiency and tropism of different AAV serotypes (2, 5 and 8) in Pde6b KO rats and found that AAV5 had the highest and most specific expression in photoreceptors. We injected AAV5-Pde6b into the subretinal space of Pde6b KO rats on postnatal day 21. We assessed the protective effects six weeks postinjection by measuring PDE6B protein expression, photoreceptor structure, retinal morphology and thickness, retinal pigment epithelium integrity and visual function.

Results: AAV5-Pde6b treatment ameliorated the disease phenotype in Pde6b KO rats by restoring PDE6B protein expression, preserving photoreceptor structure, improving retinal morphology and thickness, and maintaining retinal pigment epithelium integrity. Functional analysis of vision by scotopic electroretinogram (ERG) and optokinetic nystagmus revealed that AAV5-Pde6b treatment significantly improved the visual function of Pde6b gene KO rats compared with AAV5-GFP-injected Pde6b KO rats.

Conclusions: Our results demonstrate that AAV5-Pde6b may be a potential therapeutic gene candidate for RP caused by Pde6b mutations.