Visual Acuity-Related Outer Retinal Structural Parameters on Swept Source Optical Coherence Tomography and Angiography in XLRS Patients and Carriers

Purpose

To assess the quantitative differences in vessel density and retinal thickness of X-linked retinoschisis (XLRS) patients and RS1 mutation carriers, and the correlation with best-corrected visual acuity (BCVA) with swept source optical coherence tomography (SS-OCT) and OCT angiography (OCTA).

Methods

We analyzed the correlation between the BCVA of XLRS patients and the SS-OCT and OCTA findings including the detailed structural characteristics of XLRS patients.

Results

Besides the schitic changes in various retinal layers, the structural disturbance of outer retina was universally found. In 29 eyes included in the quantitative analysis, XLRS patients showed lower vessel density of the superficial capillary plexus, deep capillary plexus and lower thickness of the outer nuclear layer. BCVA was correlated with the thickness of the outer plexiform layer and outer nuclear layer and the thickness from the outer limiting membrane to the retinal pigment epithelium. Carriers showed higher thickness of outer plexiform layer and smaller foveal avascular zone area.

Conclusions

SS-OCT and OCTA could identify the pathological alterations of the individual retinal layers and capillaries, which could pinpoint the exact location of the damages related to visual impairment. In the carriers, the subtle alterations that can be detected with SS-OCT, despite their normal visual acuity, may be caused by the lyonization.

Translational Relevance

Swept source optical coherence tomography can be used as an efficient technique to expose the retinal damage related to visual impairment for prognosis and follow-up.

Blocking Th2 Signaling Pathway Alleviates the Clinical Symptoms and Inflammation in Allergic Conjunctivitis

Purpose

To explore the role of Th2 signaling pathway in allergic conjunctivitis (AC).

Methods

Serum Th2 cytokines IL-4 or IL-13 of patients with AC were detected using the Meso scale discovery assay to verify the correlation of Th2 immunity and AC pathogenesis. Wistar Han rats were intraperitoneally and subcutaneously injected with ovalbumin (OVA) to establish an experimental AC model and the Th2 signaling pathway was blocked by an investigational neutralizing antibody (CM310). Serum IgE and OVA-specific IgE were detected by ELISA. Conjunctivitis inflammation, infiltration of eosinophils, and mast cell degranulation were detected by histological examination. Immortalized human conjunctival epithelial cells, a conjunctival epithelial cell line, and peripheral blood mononuclear cells of patients with AC were used as the target cells to study the impact of IL-4 or IL-13 on AC progression. Finally, a STAT6 reporter gene system was constructed using immortalized human conjunctival epithelial cells to confirm whether the downstream signaling pathway activated by IL-4 or IL-13.

Results

Serum IL-4 or IL-13 were increased in patients with AC versus healthy individuals. In an OVA-induced rat experimental AC model, blocking the Th2 signaling pathway with CM310, an investigational neutralizing antibody, alleviated the conjunctival symptoms, and decreased serum IgE, suppressed infiltration of eosinophils and mast cell degranulation. Further, an in vitro model showed CM310 suppressed the secretion of inflammatory cytokine from both immune cells and epithelial cells in both patients peripheral blood mononuclear cells and cell line.

Conclusions

Blocking Th2 signaling pathway alleviates the clinical symptoms and inflammation in AC.

Split AAV8 Mediated ABCA4 Expression for Gene Therapy of Mouse Stargardt Disease (STGD1)

AAV-based gene therapy has been shown to be safe and effective in numerous animal models and clinical trials for various ophthalmic diseases. Stargardt disease (STGD1; MIM #248200) is the most common autosomal recessive macular dystrophy disease, and the most common form is caused by mutations in the ABCA4 gene, a gene with 6.8 kb coding sequence. Split intein approaches increase the capacity of dual AAV gene therapy, but at the cost of reduced protein expression, which may be insufficient to achieve a therapeutic effect. Here we designed various dual split intein ABCA4 vectors and showed that the efficiency of expression of full-length ABCA4 protein is dependent on combinations of types and split sites of the intein system. The most efficient vectors were identified through in vitro screening, and a novel dual AAV8-ABCA4 vector was constructed and subsequently proven to express full-length ABCA4 protein at a high level, reducing bisretinoid formation and correcting the visual function of ABCA4-knockout mice. Furthermore, we evaluated therapeutic effects of different dosages by subretinal injection in mice model. Both therapeutic effects and safety were guaranteed under the treatment of 1.00 × 109 GC/eye. These results support the optimized dual AAV8-ABCA4 approach in future clinical translation for treatment of Stargardt disease.

In vivo base editing rescues photoreceptors in a mouse model of retinitis pigmentosa

Retinitis pigmentosa (RP) is a group of retinal diseases that cause the progressive death of retinal photoreceptor cells and eventually blindness. Mutations in the β-domain of the phosphodiesterase 6 (Pde6b) gene are the most identified causes of autosomal recessive RP. Clinically, there is no effective treatment so far that can stop the progression of RP and restore the vision. Here, we report a base editing approach in which adeno-associated virus (AAV)-mediated adenine base editor (ABE) delivering to postmitotic photoreceptors was conducted to correct the Pde6b mutation in a retinal degeneration 10 (rd10) mouse model of RP. Subretinal delivery of AAV8-ABE corrected Pde6b mutation with averaging up to 20.79% efficiency at the DNA level and 54.97% efficiency at the cDNA level without bystanders, restored PDE6B expression, preserved photoreceptors, and rescued visual function. RNA-seq revealed the preservation of genes associated with phototransduction and photoreceptor survival. Our data have demonstrated that base editing is a potential gene therapy that could provide durable protection against RP.

In vivo adenine base editing corrects newborn murine model of Hurler syndrome

Mucopolysaccharidosis type I (MPS I) is a severe disease caused by loss-of-function mutation variants in the α-L-iduronidase (Idua) gene. In vivo genome editing represents a promising strategy to correct Idua mutations, and has the potential to permanently restore IDUA function over the lifespan of patients. Here, we used adenine base editing to directly convert A > G (TAG>TGG) in a newborn murine model harboring the Idua-W392X mutation, which recapitulates the human condition and is analogous to the highly prevalent human W402X mutation. We engineered a split-intein dual-adeno-associated virus 9 (AAV9) adenine base editor to circumvent the package size limit of AAV vectors. Intravenous injection of the AAV9-base editor system into MPS IH newborn mice led to sustained enzyme expression sufficient for correction of metabolic disease (GAGs substrate accumulation) and prevention of neurobehavioral deficits. We observed a reversion of the W392X mutation in 22.46 ± 6.74% of hepatocytes, 11.18 ± 5.25% of heart and 0.34 ± 0.12% of brain, along with decreased GAGs storage in peripheral organs (liver, spleen, lung and kidney). Collectively, these data showed the promise of a base editing approach to precisely correct a common genetic cause of MPS I in vivo and could be broadly applicable to the treatment of a wide array of monogenic diseases.

Dual-AAV split prime editor corrects the mutation and phenotype in mice with inherited retinal degeneration

The prime editor (PE) can edit genomes with almost any intended changes, including all 12 possible types of base substitutions, small insertions and deletions, and their combinations, without the requirement for double strand breaks or exogenous donor templates. PE demonstrates the possibility of correcting a variety of disease-causing mutations and might expand the therapeutic application of gene editing. In this study, PE was optimized based on a dual-adeno-associated virus (AAV) split-intein system in vitro by screening different split sites and split inteins. We found that splitting PE before amino acid 1105(Ser) of SpCas9 with Rma intein resulted in the highest on-target editing. The orientations of pegRNA and nicking sgRNA in the AAV vector were further optimized. To test the in vivo performance of the optimized dual-AAV split-PE3, it was delivered by subretinal injection in rd12 mice with inherited retinal disease Leber congenital amaurosis. The prime editors corrected the pathogenic mutation with up to 16% efficiency in a precise way, with no detectable off-target edits, restored RPE65 expression, rescued retinal and visual function, and preserved photoceptors. Our findings establish a framework for the preclinical development of PE and motivate further testing of PE for the treatment of inherited retinal diseases caused by various mutations.

CRISPR/Cas systems usher in a new era of disease treatment and diagnosis

The discovery and development of the CRISPR/Cas system is a milestone in precise medicine. CRISPR/Cas nucleases, base-editing (BE) and prime-editing (PE) are three genome editing technologies derived from CRISPR/Cas. In recent years, CRISPR-based genome editing technologies have created immense therapeutic potential with safe and efficient viral or non-viral delivery systems. Significant progress has been made in applying genome editing strategies to modify T cells and hematopoietic stem cells (HSCs) ex vivo and to treat a wide variety of diseases and disorders in vivo. Nevertheless, the clinical translation of this unique technology still faces many challenges, especially targeting, safety and delivery issues, which require further improvement and optimization. In addition, with the outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), CRISPR-based molecular diagnosis has attracted extensive attention. Growing from the specific set of molecular biological discoveries to several active clinical trials, CRISPR/Cas systems offer the opportunity to create a cost-effective, portable and point-of-care diagnosis through nucleic acid screening of diseases. In this review, we describe the development, mechanisms and delivery systems of CRISPR-based genome editing and focus on clinical and preclinical studies of therapeutic CRISPR genome editing in disease treatment as well as its application prospects in therapeutics and molecular detection.

Liver-directed gene therapy corrects neurologic disease in a murine model of mucopolysaccharidosis type I-Hurler

Mucopolysaccharidosis type I-Hurler (MPS I-H) is a neurodegenerative lysosomal storage disorder (LSD) caused by inherited defects of the α-L-iduronidase (IDUA) gene. Current treatments are ineffective for treating central nervous system (CNS) manifestations because lysosomal enzymes do not effectively cross the blood-brain barrier (BBB). To enable BBB transport of the enzyme, we engineered a modified IDUA protein by adding a brain-targeting peptide from melanotransferrin. We demonstrated that fusion of melanotransferrin peptide (MTfp) at the N terminus of human IDUA (hIDUA) was enzymatically active and could efficiently cross the BBB in vitro. Then, liver-directed gene therapy using the adeno-associated virus 8 (AAV8) vector, which encoded the modified hIDUA cDNA driven by a liver-specific expression cassette was evaluated in an adult MPS I-H mouse model. The results showed that intravenous (i.v.) infusion of AAV8 resulted in sustained supraphysiological levels of IDUA activity and normalized glycosaminoglycan (GAG) accumulation in peripheral tissues. Addition of MTfp to the hIDUA N terminus allowed efficient BBB transcytosis and IDUA activity restoration in the brain, resulting in significant improvements in brain pathology and neurobehavioral deficits. Our results provide a novel strategy to develop minimally invasive therapies for treatment of MPS I-H and other neurodegenerative LSDs.

Delivery of nVEGFi using AAV8 for the treatment of neovascular age-related macular degeneration

Inhibition of vascular endothelial growth factor (VEGF) is the standard therapy for neovascular age-related macular degeneration (nAMD). However, anti-VEGF agents used in the clinic require repeated injections, causing adverse effects. Gene therapy could provide sustained anti-VEGF levels after a single injection, thereby drastically decreasing the treatment burden and improving visual outcomes. In this study, we developed a novel VEGF Trap, nVEGFi, containing domains 1 and 2 of VEGFR1 and domain 3 of VEGFR2 fused to the Fc portion of human IgG. The nVEGFi had a higher expression level than aflibercept under the same expression cassettes of adeno-associated virus (AAV)8 in vitro and in vivo. nVEGFi was found to be noninferior to aflibercept in binding and blocking VEGF in vitro. AAV8-mediated expression of nVEGFi was maintained for at least 12 weeks by subretinal delivery in C57BL/6J mice. In a mouse laser-induced choroidal neovascularization (CNV) model, 4 × 10⁸ genome copies of AAV8-nVEGFi exhibited a significantly increased reduction in the CNV area compared with AAV8-aflibercept (78.1% vs. 63.9%, p < 0.05), while causing no structural or functional changes to the retina. In conclusion, this preclinical study showed that subretinal injection of AAV8-nVEGFi was long lasting, well tolerated, and effective for nAMD treatment, supporting future translation to the clinic.

Clinical and Echographic Features of Morning Glory Disc Anomaly in Children: A Retrospective Study of 249 Chinese Patients

Purpose

To report the clinical and echographic features, the prevalence of retinal detachment (RD), and associated visual acuity in a cohort of pediatric patients with morning glory disc anomaly (MGDA).

Methods

This was a retrospective review of 249 pediatric patients with MGDA (271 eyes) seen at the Dept. of Ophthalmology, Xinhua Hospital. Their medical records were reviewed for demographic data and ocular and systemic findings. The maximal depth and width of the cavity were measured using standardized echographic images. The ratios of cavitary depth to axial length, cavitary depth to maximal cavitary width, and the product of cavitary depth and width were calculated and used to indicate the relative size of the excavation. The clinical and echographic findings were correlated with visual acuity and the occurrence of RD of the patient.

Results

The relative size of the excavation and the presence of RD were positively associated with increased risk of poor vision (p < 0.05). The presence of persistent fetal vasculature was not associated with the risk of RD and poor vision. The ratio of cavitary depth to axial length more than or equal to 0.25 conferred an increased risk of RD (OR, 2.101; 95% CI, 1.469–3.003).

Conclusions

Clinical and echographic features of MGDA may be used in predicting the risk of RD. Measuring the relative size of excavation via echography may guide the follow-ups and assist in the early diagnosis of RD.

A case of anterior persistent hyperplastic primary vitreous associated with morning glory disc anomaly and retinopathy of prematurity like retinopathy in a term-born child

Background

Association of morning glory disc anomaly (MGDA) with persistent hyperplastic primary vitreous (PHPV) has been reported earlier. Retinopathy of prematurity (ROP) like retinopathy in preterm babies with optic disc anomalies has also been published. Our case is unique in terms of presence MGDA, PHPV, unilateral ROP like retinopathy in a term infant with normal birth weight.

Case presentation

A 5-month-old girl, born at term with a birth weight of 3750 g, presented with anterior PHPV, MGDA and ROP like retinopathy. In order to prevent retinal detachment, she received 360 degree barrage laser photocoagulation at the edge of the optic disc excavation of the left eye. In the follow-up a month later, laser scars were found in her left fundus without other complications.

Conclusion

PHPV and MGDA with ROP like retinopathy in term and normal weight baby is rare. The peripheral avascular retinal area, caused by the dragging of the defected optic disc, might have been more vulnerable to the oxygen change after birth which resulted in ROP like retinopathy. High sensitivity to oxygen results in a series of changes such as upregulation of VEGF and IGF-1 may cause ROP-like retinopathy.

Persistent anterior tunica vasculosa lentis in multisystemic smooth muscle dysfunction syndrome: A case report

RATIONALE

Multisystemic smooth muscle dysfunction syndrome (MSMDS) is a genetic disease that affects multiple organs. The report here concerns a patient with MSMDS, who is known so far as the youngest among all the reported patients. In addition to the typical manifestations, we observed previously unreported ocular abnormalities, including persistent anterior tunica vasculosa lentis (TVL) and early-onset retinal arteriolar tortuosity, by the fluorescein angiography (FA).

PATIENT CONCERNS

The patient was admitted to the neonatal intensive care unit immediately after birth for a diagnosis of urinary system dysplasia during fetal life. After a thorough examination, the patient was found with patent ductus arteriosus, pulmonary hypertension, cerebrovascular disease, hypotonic bladder, intestinal malrotation, and congenital mydriasis. The FA of the eyes undertaken in her 6-week demonstrated perfused vasculature in the persistent anterior TVL and prominent retinal arteriolar tortuosity. The whole exome sequencing revealed a de novo heterozygous ACTA2 gene missense mutation p.R179H.

DIAGNOSES

The patient was diagnosed with MSMDS.

INTERVENTIONS

Follow-up observation.

OUTCOMES

At the 3-month follow-up, no change of the ocular disease was observed.

LESSONS

The persistent anterior TVL in this case implies that ACTA2 p.R179H mutation affects not only the smooth muscle cells but also the pericytes, and further affects the TVL regression. The prominent retinal arteriolar tortuosity in this 6-week-old infant indicates that the retinal arteriolar tortuosity can present early in MSMDS.

Incontinentia pigmenti-associated ocular anomalies of paediatric incontinentia pigmenti patients in China

PURPOSE

To characterize ocular manifestations in a cohort of paediatric patients with incontinentia pigmenti (IP) and to define the guidelines for grading of IP-associated retinopathy (IPR).

METHODS

This retrospective review was performed on patients under the age of 18 years with a diagnosis of IP. Data included demographics, medical history, ocular examination, and accessory examination. Ocular and systemic physical examinations of the parents were carried out to determine the familial history.

RESULTS

Sixty-one children (58 females and three males) with median age of 3.7 months were observed consecutively. The median follow-up duration was 13.4 months (range: 6.5-75.0 months). A total of 47 patients had various ocular anomalies. Among them, 28 patients had bilateral ocular anomalies and 19 had unilateral anomalies. Vitreoretinal changes were noted in 73 of 122 eyes, including eight eyes with retinal pigment epithelium changes only (Stage 1), 22 eyes with retinal vascular abnormalities (Stage 2), five eyes with epiretinal membranes or fibrotic hyperplasia combined with avascularized zones (Stage 3), six eyes with retinal neovascularization (Stage 3), one eye with vitreous haemorrhage (Stage 3), 10 eyes with partial retinal detachment (RD) (Stage 4a), 15 eyes with total RD (Stage 4b) and eight eyes with phthisis bulbi and secondary glaucoma (Stage 5).

CONCLUSION

Various vitreoretinal manifestations can be found in paediatric patients with IP and classified into five stages, which are characterized by retinal vasculopathy.

Peripheral Retinal Nonperfusion in Pediatric Patients With Morning Glory Syndrome

BACKGROUND AND OBJECTIVE

To report the association of morning glory syndrome (MGS) with peripheral retinal nonperfusion in pediatric patients with MGS.

PATIENTS AND METHODS

The authors retrospectively analyzed the records of pediatric patients with MGS using fundus fluorescein angiography. The peripheral retinal vascular architecture was recorded and graded according to the severity of peripheral retinal nonperfusion.

RESULTS

Eighty-six eyes of 74 patients were enrolled. Seventy-three of 86 eyes (84.88%) had peripheral retinal nonperfusion, in which mild severity was found in 31 of 86 eyes (36.05%), moderate in 17 of 86 eyes (19.77%), severe in 18 of 86 eyes (20.93%), and extreme in seven of 86 eyes (8.14%). Secondary complications of nonperfusion included leakage in six of 73 eyes (8.22%), fibrovascular proliferation in two of 73 eyes (2.74%), and tractional retinal detachment in one of 73 eyes (1.34%).

CONCLUSION

There is a high prevalence of peripheral retinal nonperfusion in pediatric MGS eyes, with secondary complications in some, suggesting that more attention should be paid to the peripheral retina in MGS. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:674-679.].