PEDF-derived peptide protects against Amyloid-β toxicity in vitro and prevents retinal dysfunction in rats

Amyloid-beta (Aβ), a family of aggregation-prone and neurotoxic peptides, has been implicated in the pathophysiology of age-related macular degeneration (AMD). We have previously shown that oligomeric and fibrillar species of Aβ42 exerted retinal toxicity in rats, but while the consequences of exposure to amyloid were related to intracellular effects, the mechanism of Aβ42 internalization in the retina is not well characterized. In the brain, the 67 kDa laminin receptor (67LR) participates in Aβ-related neuronal cell death. A short peptide derived from pigment epithelium-derived factor (PEDF), formerly designated PEDF-335, was found to mitigate experimental models of ischemic retinopathy via targeting of 67LR. In the present study, we hypothesized that 67LR mediates the uptake of pathogenic Aβ42 assemblies in the retina, and that targeting of this receptor by PEDF-335 may limit the internalization of Aβ, thereby ameliorating its retinotoxicity. To test this assumption ARPE-19 cells in culture were incubated with PEDF-335 before treatment with fibrillar or oligomeric structures of Aβ42. Immunostaining confirmed that PEDF-335 treatment substantially prevented amyloid internalization into ARPE-19 cells and maintained their viability in the presence of toxic oligomeric and fibrillar Aβ42 entities in vitro. FRET competition assay was performed and confirmed the binding of PEDF-335 to 67LR in RPE-like cells. Wild-type rats were treated with intravitreal PEDF-335 in the experimental eye 2 days prior to administration of retinotoxic Aβ42 oligomers or fibrils to both eyes. Retinal function was assessed by electroretinography through 6 weeks post injection. The ERG responses in rats treated with oligomeric or fibrillar Aβ42 assemblies were near-normal in eyes previously treated with intravitreal PEDF-335, whereas those measured in the control eyes treated with injection of the Aβ42 assemblies alone showed pathologic attenuation of the retinal function through 6 weeks. The retinal presence of 67LR was determined ex vivo by immunostaining and western blotting. Retinal staining demonstrated the constitutional expression of 67LR mainly in the retinal nuclear layers. In the presence of Aβ42, the levels of 67LR were increased, although its retinal distribution remained largely unaltered. In contrast, no apparent differences in the retinal expression level of 67LR were noted following exposure to PEDF-335 alone, and its pattern of localization in the retina remained similarly concentrated primarily in the inner and outer nuclear layers. In summary, we found that PEDF-335 confers protection against Aβ42-mediated retinal toxicity, with significant effects noted in cells as well as in vivo in rats. The effects of PEDF-335 in the retina are potentially mediated via binding to 67LR and by at least partial inhibition of Aβ42 internalization. These results suggest that PEDF-335 may merit further consideration in the development of targeted inhibition of amyloid-related toxicity in the retina. More broadly, our observations provide evidence on the importance of extracellular versus intracellular Aβ42 in the retina and suggest concepts on the molecular mechanism of Aβ retinal pathogenicity.

Characteristics of pediatric ocular trauma in a tertiary hospital in Israel 2011-2020 - How can public prevention policy be improved?

PURPOSE

To describe and analyze characteristics and trends of pediatric ocular trauma during 2011-2020.

METHODS

Retrospective descriptive study. Data were collected on all pediatric ocular trauma cases that presented to a Rambam Health Care Campus during 2011-2020. Data included age, gender, visual acuity, diagnosis, injury mechanism and surgical repair.

RESULTS

Median BCVA at presentation was 0.96 (logMAR). Males and non-adolescent males specifically were the most prominent groups (70.6% and 44.7%, respectively). The ratio of ocular trauma cases to total pediatric emergency department (ED) visits was stable during 2011-2020 (p = 0.714) regardless of gender (p = 0.832 and p = 0.545 for boys and girls, respectively). The leading causes were partial thickness eyelid laceration, periorbital hematoma, and extraocular muscle contusion, all of which were stable over the study period (p = 0.678, p = 0.203 and p = 0.398, respectively). Falls and children play were the most common mechanisms (25.8% and 18.4%, respectively), but differed between age groups. Most patients did not require consecutive operation and were treated conservatively (p < 0.01).

CONCLUSION

Pediatric ocular injuries to pediatric ED visits ratio remained stable during 2011-2020, regardless of gender. Non-adolescent males accounted for nearly half of all cases, with different mechanisms for each age group. Consecutive surgery was rarely necessary.

The Surprising Nonlinear Effects of S100A9 Proteins in the Retina

Age-related macular degeneration (AMD) is a complex disease in which inflammation is implicated as a key factor but the precise molecular mechanisms are poorly understood. AMD lesions contain an excess of the pro-inflammatory S100A9 protein, but its retinal significance was yet unexplored. S100A9 was shown to be intrinsically amyloidogenic in vitro and in vivo. Here, we hypothesized that the retinal effects of S100A9 are related to its supramolecular conformation. ARPE-19 cultures were treated with native dimeric and fibrillar S100A9 preparations, and cell viability was determined. Wild-type rats were treated intravitreally with the S100A9 solutions in the right eye and with the vehicle in the left. Retinal function was assessed longitudinally by electroretinography (ERG), comparing the amplitudes and configurations for each intervention. Native S100A9 had no impact on cellular viability in vitro or on the retinal function in vivo. Despite dispersed intracellular uptake, fibrillar S100A9 did not decrease ARPE-19 cell viability. In contrast, S100A9 fibrils impaired retinal function in vivo following intravitreal injection in rats. Intriguingly, low-dose fibrillar S100A9 induced contrasting in vivo effects, significantly increasing the ERG responses, particularly over 14 days postinjection. The retinal effects of S100A9 were further characterized by glial and microglial cell activation. We provide the first indication for the retinal effects of S100A9, showing that its fibrils inflicted retinal dysfunction and glial activation in vivo, while low dose of the same assemblies resulted in an unpredicted enhancement of the ERG amplitudes. These nonlinear responses highlight the consequences of self-assembly of S100A9 and provide insight into its pathophysiological and possibly physiological roles in the retina.

Reduced Electroretinogram Responses in Morphologically Normal Retina in Patients with Primary Hyperoxaluria Type 1

Purpose

To describe ocular findings in individuals with primary hyperoxaluria type 1 (PH1), focusing on the correlations between retinal anatomy and retinal function. To characterize the retinal alterations that occur at different disease stages by evaluating individuals with diverse degrees of renal impairment associated with PH1.

Design

A cross-sectional study.

Participants

Patients diagnosed with PH1 based on clinical criteria and genetic testing, treated in the Pediatric Nephrology Unit of the Ruth Children's Hospital, Rambam Health Care Campus, Haifa, Israel between 2013 and 2021.

Methods

The ophthalmological assessment included a slit-lamp biomicroscopy of the anterior and posterior segment or indirect ophthalmoscopy. Electroretinography was employed for assessment of the retinal function, and retinal imaging included spectral-domain OCT and fundus autofluorescence. A systematic evaluation of the disease stage was based on clinical criteria including physical examination, purposeful imaging (X-ray, echocardiography, and US abdomen), and laboratory tests as needed.

Main Outcome Measures

Anatomical and functional assessment of the retina in patients with PH1, and the relationship between retinal dysfunction and kidney impairment.

Results

A total of 16 eyes were examined in the study of 8 children ranging in age from 4 to 19 years. Four eyes (25%) showed normal structural and functional retinal findings, 8 eyes (50%) presented functional impairment in the absence of pathological structural findings, and 4 eyes (25%) had advanced retinal damage that manifested as significant morphological and functional impairment. There was no direct relationship between the severity of the renal disease and the severity of the retinal phenotype.

Conclusions

Subjects with PH1 present varying severity levels of the retinal phenotype, with possible discrepancy between the clinical retinal morphology and the retinal function noted on electroretinography. These findings raise questions about the molecular basis of the retinal manifestations in PH1. The presence of functional impairment in the absence of evident crystal deposition in the retina suggests that, in addition to oxalate crystal accumulation, other biomolecular processes may play a role in the development of retinopathy.

Changes in chorioretinal flow index after cataract surgery: an optical coherence tomography angiography study

PURPOSE

Pseudophakic cystoid macular edema (CME) occurs in up to 2% of uneventful cataract surgeries. This study evaluates changes in macular blood flow succeeding uneventful phacoemulsification cataract extraction among otherwise visually healthy subjects.

METHODS

This prospective study included 18 eyes of 18 patients undergoing routine phacoemulsification. Optical coherence tomography angiography (OCT-A) was performed using the Angio-Retina 6 × 6 mm protocol with the XR Avanti Angio-Vue system (Optovue Inc., Fremont, California) prior to the surgery and 4-8 weeks thereafter. Exclusion criteria included motion artifacts, segmentation errors and signal strength index (SSI) < 40. The main outcome measure was change in flow index (FI) measured in all 4 retinal segmentation layers within an area of 1 mm diameter around the foveal center.

RESULTS

Following surgery, a significant increase in SSI (46.65 ± 8.62 versus 53.12 ± 8.07, p = 0.01), superficial plexus FI (0.98 ± 0.23 versus 1.16 ± 0.16, p = 0.02) and deep plexus FI (0.54 ± 0.46 versus 0.93 ± 0.39, p = 0.01) was found. No significant changes were noted in the outer retina or the choriocapillaris.

CONCLUSION

The study demonstrates a significant increase in FI in the superficial and deep retinal plexus following uneventful cataract surgery, with the greatest changes occurring in the latter. These findings corroborate evidence from structural imaging and support the vascular etiology of pseudophakic CME.

Severely Elevated Intraocular Pressure Following Traumatic Asphyxia: A Case Report

BACKGROUND

Traumatic asphyxia is a syndrome caused by a sudden pressure rise in the chest caused by crushing injury of the thorax or upper abdomen. It is associated with a variety of thoracic injuries, neurological symptoms, and ocular complications.

CASE REPORT

We report an unusual case of traumatic asphyxia complicated by severe, sight-threatening, elevation in intraocular pressure. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: After initial stabilization, the treatment of patients with traumatic asphyxia is supportive and is mainly directed toward the accompanying injuries and complications. A complete and prompt ophthalmologic examination, including tonometry, should be an integral part of the secondary survey. This is particularly important in patients who cannot report visual impairment, such as children or unconscious patients.

Minimally Invasive Technique for Choroidal Fluid Drainage

Background

This study describes a simple technique for the treatment of kissing choroidal detachment. In contrast to the commonly used technique, this technique is minimally invasive, fast, sutureless, and does not require access to the vitreous space.

Methods

A maintainer is inserted into the anterior chamber. A 25G trocar is inserted at the pars plana into the suprachoroidal space. Drainage is evident by the clear yellowish fluid freely emerging through the trocar, accompanied with deepening of the anterior chamber and an increase in the red reflex.

Results

Follow-up ultrasound 1 week after the surgery demonstrated resolution of the choroidal detachment. Net surgery time is about 10 minutes. No complications were noted.

Discussion

This is the first report of the technique performed in phakic eye, with video description of the steps and real-time clues for successful drainage even with reduced posterior segment visibility due to lens opacities.

Precision pulse capsulotomy complicated by radial tear of the anterior capsule: a proposed mechanism

Zepto precision pulsed capsulotomy is an emerging technology aimed at providing a safer and more reproducible anterior capsulorhexis, with potential advantages in challenging cases. Initial reports suggest high safety, and thus far to our knowledge, no complications have been reported. Herein we report an unexpected complication. After the pulse delivery phase on a routine cataract case, a radial tear of the anterior capsule was observed. Upon careful review of the surgery video, an air bubble was noted, at the precise clock hour of the radial tear, trapped between the device wire and capsule. This air bubble presumably prevented the transfer of rapid phase transition at this site, interfering with capsule cleavage, and resulting in incomplete capsulotomy. Based on this observation, if a trapped air bubble is observed after the vacuum phase, we recommend applying more vacuum or disengaging and reattaching, before proceeding to the pulse delivery stage.