Kinetics of Heterogeneous Background in Stargardt's Disease over Time.

Stargardt's disease (STGD1) is caused by mutations in the ABCA4 gene. Different lesions characterised by decreased autofluorescence levels are found in fundus autofluorescence (FAF) from STGD1 patients and could be used as outcome indicators for disease progression. We investigated the fate of foci with reduced autofluorescence (FRA) within the heterogeneous background of STGD1 patients using FAF imaging. Genetically confirmed STGD1 patients presenting heterogeneous background autofluorescence on high-quality FAF images at a minimum of two visits at least 12 months apart were chosen. A grid centred on the fovea was used to define five different zones. Within each zone, five FRA were randomly selected for each eye. The eccentricity of foci was determined at different time points for each patient. Analysis of 175 randomly chosen FRA showed consistent centrifugal displacement over time, most notably in eyes showing areas with definitely decreased autofluorescence. Interestingly, FRA did not leave an area of hypo-autofluorescence on FAF in locations where they were previously located. These findings may help to better understand STGD1 progression, improve FAF interpretation, and shed light on the nature of heterogeneous background.

Egg-derived anti-SARS-CoV-2 immunoglobulin Y (IgY) with broad variant activity as intranasal prophylaxis against COVID-19: preclinical studies and randomized controlled phase 1 clinical trial

COVID-19 emergency use authorizations and approvals for vaccines were achieved in record time. However, there remains a need to develop additional safe, effective, easy-to-produce, and inexpensive prevention to reduce the risk of acquiring SARS-CoV-2 infection. This need is due to difficulties in vaccine manufacturing and distribution, vaccine hesitancy, and, critically, the increased prevalence of SARS-CoV-2 variants with greater contagiousness or reduced sensitivity to immunity. Antibodies from eggs of hens (immunoglobulin Y; IgY) that were administered receptor-binding domain (RBD) of the SARS-CoV-2 spike protein were developed as nasal drops to capture the virus on the nasal mucosa. Although initially raised against the 2019 novel coronavirus index strain (2019- nCoV), these anti-SARS-CoV-2 RBD IgY surprisingly had indistinguishable enzyme-linked immunosorbent assay binding against variants of concern that have emerged, including Alpha (B.1.1.7), Beta (B.1.351), Delta (B.1.617.2), and Omicron (B.1.1.529). This is distinct for sera from immunized or convalescent patients. Culture neutralization titers against available Alpha, Beta, and Delta were also indistinguishable from the index SARS-CoV-2 strain. Efforts to develop these IgY for clinical use demonstrated that the intranasal anti-SARS-CoV-2 RBD IgY preparation showed no binding (cross-reactivity) to a variety of human tissues and had an excellent safety profile in rats following 28-day intranasal delivery of the formulated IgY. A double-blind, randomized, placebo- controlled phase 1 study evaluating single-ascending and multiple doses of anti-SARS-CoV-2 RBD IgY administered intranasally for 14 days in 48 healthy adults also demonstrated an excellent safety and tolerability profile, and no evidence of systemic absorption. As these antiviral IgY have broad selectivity against many variants of concern, are fast to produce, and are a low-cost product, their use as prophylaxis to reduce SARS-CoV-2 viral transmission warrants further evaluation. (ClinicalTrials.gov: NCT04567810, https://www.clinicaltrials.gov/ct2/show/NCT04567810)

Transplantation of Human Induced Pluripotent Stem Cell-Derived Retinal Pigment Epithelium in a Swine Model of Geographic Atrophy.

BACKGROUND: The aim of this study was to test the feasibility and safety of subretinal transplantation of human induced pluripotent stem cell (hiPSC)-derived retinal pigment epithelium (RPE) cells into the healthy margins and within areas of degenerative retina in a swine model of geographic atrophy (GA). METHODS: Well-delimited selective outer retinal damage was induced by subretinal injection of NaIO3 into one eye in minipigs (n = 10). Thirty days later, a suspension of hiPSC-derived RPE cells expressing green fluorescent protein was injected into the subretinal space, into the healthy margins, and within areas of degenerative retina. In vivo follow-up was performed by multimodal imaging. Post-mortem retinas were analyzed by immunohistochemistry and histology. RESULTS: In vitro differentiated hiPSC-RPE cells showed a typical epithelial morphology, expressed RPE-related genes, and had phagocytic ability. Engrafted hiPSC-RPE cells were detected in 60% of the eyes, forming mature epithelium in healthy retina extending towards the border of the atrophy. Histological analysis revealed RPE interaction with host photoreceptors in the healthy retina. Engrafted cells in the atrophic zone were found in a patchy distribution but failed to form an epithelial-like layer. CONCLUSIONS: These results might support the use of hiPSC-RPE cells to treat atrophic GA by providing a housekeeping function to aid the overwhelmed remnant RPE, which might improve its survival and therefore slow down the progression of GA.

Increased elastase sensitivity and decreased intramolecular interactions in the more transmissible SARS-CoV-2 variants' spike protein

Two SARS-CoV-2 variants showing increased transmissibility relative to the Wuhan virus have recently been identified. Although neither variant causes more severe illness or increased risk of death, the faster spread of the virus is a major threat. Using computational tools, we found that the new SARS-CoV-2 variants may acquire an increased transmissibility by increasing the propensity of its spike protein to expose the receptor binding domain. This information leads to the identification of potential treatments to avert the imminent threat of these more transmittable SARS-CoV-2 variants. TeaserThe more infective SARS-CoV-2 variants may expose its Achilles Heel - an opportunity to reduce their spreading.

Mitochondrial neurogastrointestinal encephalopathy: a clinicopathological mimic of Crohn's disease.

BACKGROUND: Mitochondrial neurogastrointestinal encephalopathy (MNGIE), due to mutations in TYMP, often presents with gastrointestinal symptoms. Two sisters, initially managed for Crohn's disease based upon clinical, imaging and pathological findings, were later found to have MNGIE. The cases provide novel clinicopathological insight, for two further reasons: both sisters remain ambulant and in employment in their late 20s and 30s; diagnosis in one sister was made after a suspected azathioprine-precipitated acute illness. CASE PRESENTATION: A 25-year-old female presented with diarrhoea, vomiting, abdominal pain, and bloating. Faecal calprotectin, colonic biopsies and magnetic resonance enterography were consistent with a diagnosis of Crohn's disease. Azathioprine initiation preceded admission with a sore throat, headache, myalgia, and pyrexia. Withdrawal led to rapid clinical improvement. MRI brain revealed persistent, extensive white matter changes. Elevated plasma and urine thymidine and deoxyuridine, and genetic testing for TYMP variants, confirmed MNGIE. Testing of the patient's sister, also diagnosed with Crohn's disease, revealed identical variants. In this context, retrospective review of colonic biopsies identified histological findings suggestive of MNGIE. CONCLUSIONS: Azathioprine interference in nucleic acid metabolism may interact with the mitochondrial DNA depletion of MNGIE. Nucleotide supplementation, proposed for treatment by manipulating mitochondrial nucleoside pools, may require caution. The late onset and mild phenotype observed confirms presentation can occur later in life, and may reflect residual thymidine phosphorylase activity. Clinicians should consider measuring plasma thymidine levels in suspected Crohn's disease to rule out MNGIE, particularly if white matter abnormalities are identified on neuroimaging.

Biodegradable collagen matrix implant versus mitomycin-C in trabeculectomy: five-year follow-up.

BACKGROUND: Clinical studies comparing trabeculectomy augmented with Ologen implant (OLO) versus trabeculectomy plus mitomycin-C (MMC) show contradictory results. To obtain long-term data, we report an extended 5-year follow-up trial evaluating the safety and efficacy of OLO as adjuvant compared to low-dosage MMC in trabeculectomy. METHODS: Forty glaucoma patients (40 eyes) assigned to trabeculectomy with MMC or Ologen. PRIMARY OUTCOME: target IOP at ≤21, ≤17 and ≤15 mmHg; complete and qualified success endpoint rates. SECONDARY OUTCOMES: visual acuity (VA), mean deviation (MD), bleb evaluation, according to Moorfields Bleb Grading System (MBGS); spectral domain OCT (SD-OCT) bleb examination; number of glaucoma medications; frequency of postoperative complications. RESULTS: The mean preoperative IOP was 26.7(±5.2) in MMC and 27.3(±6.0) in OLO eyes. Mean 60-month percentage reduction in IOP was significant in both groups [40.9 (±14.2) and 42.1(±13.3) P = 0.01], with an endpoint value of 15.2 (±3.2) and 15.8 (±2.3) mmHg in MMC and OLO, respectively. Complete success rates at ≤ 21 mmHg target IOP were 65% and 70%, at ≤17 mm Hg 60% and 55%, and at the ≤15 mm Hg target IOP 35% and 45% in MMC and OLO, respectively. The Kaplan-Meier curves did not differ both for complete and qualified success at any target IOP, with no significant endpoint intergroup difference at ≤ 15 mm Hg (log-rank P = 0.595).The intergroup MBGS scores differed due to reduced central and peripheral vascularity in MMC group (P = 0.027; P = 0.041). SD-OCT analysis denied differences in bleb height between MMC vs OLO (140.5 ± 20.3 µ vs 129.2 ± 19.3 µ respectively; P =0.079). Mean antiglaucoma medications were significantly reduced (P < 0.0005) from 2.5 (±0.3) to 1.2 (±0.4) in MMC and from 2.6 (±0.2) to 1.4 (±0.3) in OLO group, with no intergroup differences (P = 0.08). Six (30%) cystic thin avascular blebs without oozing were recorded in the MMC group and 2 (10%) in the OLO group, without intergroup difference (P = 0.235). CONCLUSIONS: Our extended follow-up results confirm that Ologen implant yields efficacy and long-term success rates quite similar to MMC, with at least equivalent safety.

TREATMENT OF PERSISTENTLY OPEN MACULAR HOLES WITH HEAVY SILICONE OIL (DENSIRON 68) VERSUS C2F6. A PROSPECTIVE RANDOMIZED STUDY.

PURPOSE: To compare the efficacy of a mixture of silicone oil and perfluorohexyloctane (Densiron 68) with C2F6 gas endotamponade in the retreatment of persistently open full-thickness macular holes. METHODS: In this prospective randomized study, 21 consecutive patients who were unsuccessfully operated on for large idiopathic full-thickness macular hole were randomly assigned to undergo a second vitrectomy with 20% perfluoroethane gas (C2F6, Group A) or with Densiron 68 tamponade (Group B). PRIMARY OUTCOMES: Endpoint (12 months) full-thickness macular hole closure rate by spectral domain optical coherence tomography and logMAR corrected distance visual acuity. SECONDARY OUTCOMES: postoperative adverse events. RESULTS: The mean diameter of macular holes before the second pars plana vitrectomy was 680.3 ± 120.8 µm and 740.5 ± 105.3 µm in Groups A and B, respectively (P = 0.237); mean preoperative corrected distance visual acuity was 0.96 ± 0.36 logMAR and 1.12 ± 0.35 logMAR, respectively (P = 0.315). Endpoint full-thickness macular hole closure was obtained in 30% of patients (3/10) in Group A and in 82% (9/11) in Group B (P = 0.030). Corrected distance visual acuities were, respectively, 0.80 ± 0.25 logMAR and 0.55 ± 0.20 logMAR, with significant intergroup difference (P = 0.019); corrected distance visual acuity increased in Group B only (P = 0.003). No differences in complications were found. CONCLUSION: The results indicate that Densiron 68 tamponade could be a useful, safe, and more efficacious method than gas tamponade to retreat persisting macular holes.