Endomucin selectively regulates vascular endothelial growth factor receptor-2 endocytosis through its interaction with AP2.

The endothelial glycocalyx, located at the luminal surface of the endothelium, plays an important role in the regulation of leukocyte adhesion, vascular permeability, and vascular homeostasis. Endomucin (EMCN), a component of the endothelial glycocalyx, is a mucin-like transmembrane glycoprotein selectively expressed by venous and capillary endothelium. We have previously shown that knockdown of EMCN impairs retinal vascular development in vivo and vascular endothelial growth factor 165 isoform (VEGF165)-induced cell migration, proliferation, and tube formation by human retinal endothelial cells in vitro and that EMCN is essential for VEGF165-stimulated clathrin-mediated endocytosis and signaling of VEGF receptor 2 (VEGFR2). Clathrin-mediated endocytosis is an essential step in receptor signaling and is of paramount importance for a number of receptors for growth factors involved in angiogenesis. In this study, we further investigated the molecular mechanism underlying EMCN's involvement in the regulation of VEGF-induced endocytosis. In addition, we examined the specificity of EMCN's role in angiogenesis-related cell surface receptor tyrosine kinase endocytosis and signaling. We identified that EMCN interacts with AP2 complex, which is essential for clathrin-mediated endocytosis. Lack of EMCN did not affect clathrin recruitment to the AP2 complex following VEGF stimulation, but it is necessary for the interaction between VEGFR2 and the AP2 complex during endocytosis. EMCN does not inhibit VEGFR1 and FGFR1 internalization or their downstream activities since EMCN interacts with VEGFR2 but not VEGFR1 or FGFR1. Additionally, EMCN also regulates VEGF121-induced VEGFR2 phosphorylation and internalization.

Real-world effects of anti-vascular endothelial growth factor injection frequency on visual outcomes in patients with diabetic macular oedema.

BACKGROUND AND OBJECTIVE: Anti-vascular endothelial growth factor (VEGF) injections are often administered less frequently in real-world treatment of diabetic macular oedema (DMO) than what was studied in clinical trials. This study aims to characterise real-world DMO treatment patterns and the effect of treatment intervals on patient outcomes. STUDY DESIGN/PATIENTS AND METHODS: This was a retrospective study of 291 patients with DMO treated with anti-VEGF therapy. 12- and 24-month best visual acuity (BVA) and central subfield thickness (CST) were compared between injection interval groups, which were determined by averaging the two most recent injection intervals. Multiple linear regressions were performed to identify factors associated with injection interval, BVA, and CST. RESULTS: 48.8% of patients received injections less than or equal to every 8 weeks (≤ q8w), 27.5% between every 8 to 12 weeks (q8-12w), and 23.7% greater than every 12 weeks (> q12w). Baseline CST was similar (p = 0.32), but BVA differed significantly in q8-12w patients (p = 0.0095). BVA and CST at 12 months were similar, but q8-12w patients experienced greater 12-month BVA improvement (7.36 ± 12.4 letters) than > q12w patients (1.26 ± 12.3 letters; p = 0.0056). 24-month BVA and CST changes were similar between groups (p = 0.30 and 0.87). Baseline BVA, HbA1c, and sex were associated with 12-month BVA, and baseline BVA and CST were associated with 12-month CST. CONCLUSION: Many patients experienced improvements in BVA and CST over 12 months of treatment despite receiving less frequent anti-VEGF therapy than recommended in the pivotal trials. The present study showed that extended treatment intervals with bevacizumab were effective in preserving vision of many individuals with high baseline BVA.

Characterizing the Journey of Geographic Atrophy Patients in Routine Ophthalmic Practice.

BACKGROUND AND OBJECTIVE: Geographic atrophy (GA) is a form of late-stage age-related macular degeneration (AMD). This study aims to characterize the journey of patients with GA in real-world ophthalmology practice. PATIENTS AND METHODS: This is a retrospective cohort study of 100 patients with GA and 100 with intermediate AMD (iAMD). RESULTS: Approximately one-third of GA patients' eyes had GA at the time of their initial AMD diagnosis, and nearly half of the iAMD patients' eyes had iAMD at that time. When holding confounders constant, GA patients experienced significantly worse visual acuity outcomes, and a significantly higher proportion required referrals for low vision evaluation, needed assistance for activities of daily living, failed to meet driving standards, and met criteria for legal blindness when compared to iAMD controls. CONCLUSIONS: Many patients have already progressed to GA by the time they receive an AMD diagnosis, emphasizing the importance of providing early detection and intervention, especially considering novel treatment options. [Ophthalmic Surg Lasers Imaging Retina 2024;55:204-210.].

Outcomes for maximal bilateral lateral rectus recession in large-angle exotropia.

BACKGROUND: Surgical treatment for large-angle exotropia can be challenging. The aim of this study was to evaluate short-term surgical outcomes of patients with large-angle exotropia (≥50Δ) undergoing maximal bilateral lateral rectus muscle recession of 10 mm. METHODS: This was a retrospective study of consecutive patients at our institution who underwent maximal bilateral lateral rectus muscle recession for exodeviation ≥50Δ from January 1, 2008, to July 22, 2022. We subdivided the cohort into large-angle exotropia (largest amount of exodeviation at near and/or distance ≥50Δ and <65Δ) and very large-angle exotropia (largest exodeviation ≥65Δ). Patients with a history of prior eye muscle surgery, neurologic deficits, and three- or four-muscle surgery were excluded. RESULTS: A total of 22 patients were included. Mean preoperative exodeviation at distance was 51.9Δ in the large-angle group and 67.5Δ in the very-large-angle group (P = 0.001). Outcomes for the large-angle and very-large angle groups were, respectively, as follows: mean follow-up, 31.1 weeks and 11.8 weeks (P = 0.97); success, 75.0% and 16.7% (P = 0.02); undercorrection rates, 18.7% and 83.3% (P = 0.01); and mean postoperative exodeviation at distance, 3.7Δ ± 6.3Δ and 28.0Δ ± 13.5Δ (P = 0.001). CONCLUSIONS: Our study identified good surgical outcomes (75%) with maximal bilateral lateral rectus muscle recession of 10 mm in treating patients with large-angle exotropia between 50Δ and <65Δ. Other surgical techniques such as recession-resection and three- or four-muscle surgery may result in better outcomes when treating patients with exotropia ≥65Δ.

SCAN for Abuse: Electronic Health Record-Based Universal Child Abuse Screening.

BACKGROUND: Identification of physical abuse at the point of care without a systematic approach remains inherently subjective and prone to judgement error. This study examines the implementation of an electronic health record (EHR)-based universal child injury screen (CIS) to improve detection rates of child abuse. METHODS: CIS was implemented in the EHR admission documentation for all patients age 5 or younger at a single medical center, with the following questions. 1) "Is this patient an injured/trauma patient?" 2) "If this is a trauma/injured patient, where did the injury occur?" A "Yes" response to Question 1 would alert a team of child abuse pediatricians and social workers to determine if a patient required formal child abuse clinical evaluation. Patients who received positive CIS responses, formal child abuse work-up, and/or reports to Child Protective Services (CPS) were reviewed for analysis. CPS rates from historical controls (2017-2018) were compared to post-implementation rates (2019-2021). RESULTS: Between 2019 and 2021, 14,150 patients were screened with CIS. 286 (2.0 %) patients screened received positive CIS responses. 166 (58.0 %) of these patients with positive CIS responses would not have otherwise been identified for child abuse evaluation by their treating teams. 18 (10.8 %) of the patients identified by the CIS and not by the treating team were later reported to CPS. Facility CPS reporting rates for physical abuse were 1.2 per 1000 admitted children age 5 or younger (pre-intervention) versus 4.2 per 1000 (post-intervention). CONCLUSIONS: Introduction of CIS led to increased detection suspected child abuse among children age 5 or younger. LEVEL OF EVIDENCE: Level II. TYPE OF STUDY: Study of Diagnostic Test.

Increased LCN2 (lipocalin 2) in the RPE decreases autophagy and activates inflammasome-ferroptosis processes in a mouse model of dry AMD.

In dry age-related macular degeneration (AMD), LCN2 (lipocalin 2) is upregulated. Whereas LCN2 has been implicated in AMD pathogenesis, the mechanism remains unknown. Here, we report that in retinal pigmented epithelial (RPE) cells, LCN2 regulates macroautophagy/autophagy, in addition to maintaining iron homeostasis. LCN2 binds to ATG4B to form an LCN2-ATG4B-LC3-II complex, thereby regulating ATG4B activity and LC3-II lipidation. Thus, increased LCN2 reduced autophagy flux. Moreover, RPE cells from cryba1 KO, as well as sting1 KO and Sting1Gt mutant mice (models with abnormal iron chelation), showed decreased autophagy flux and increased LCN2, indicative of CGAS- and STING1-mediated inflammasome activation. Live cell imaging of RPE cells with elevated LCN2 also showed a correlation between inflammasome activation and increased fluorescence intensity of the Liperfluo dye, indicative of oxidative stress-induced ferroptosis. Interestingly, both in human AMD patients and in mouse models with a dry AMD-like phenotype (cryba1 cKO and KO), the LCN2 homodimer variant is increased significantly compared to the monomer. Sub-retinal injection of the LCN2 homodimer secreted by RPE cells into NOD-SCID mice leads to retinal degeneration. In addition, we generated an LCN2 monoclonal antibody that neutralizes both the monomer and homodimer variants and rescued autophagy and ferroptosis activities in cryba1 cKO mice. Furthermore, the antibody rescued retinal function in cryba1 cKO mice as assessed by electroretinography. Here, we identify a molecular pathway whereby increased LCN2 elicits pathophysiology in the RPE, cells known to drive dry AMD pathology, thus providing a possible therapeutic strategy for a disease with no current treatment options.Abbreviations: ACTB: actin, beta; Ad-GFP: adenovirus-green fluorescent protein; Ad-LCN2: adenovirus-lipocalin 2; Ad-LCN2-GFP: adenovirus-LCN2-green fluorescent protein; LCN2AKT2: AKT serine/threonine kinase 2; AMBRA1: autophagy and beclin 1 regulator 1; AMD: age-related macular degeneration; ARPE19: adult retinal pigment epithelial cell line-19; Asp278: aspartate 278; ATG4B: autophagy related 4B cysteine peptidase; ATG4C: autophagy related 4C cysteine peptidase; ATG7: autophagy related 7; ATG9B: autophagy related 9B; BLOC-1: biogenesis of lysosomal organelles complex 1; BLOC1S1: biogenesis of lysosomal organelles complex 1 subunit 1; C57BL/6J: C57 black 6J; CGAS: cyclic GMP-AMP synthase; ChQ: chloroquine; cKO: conditional knockout; Cys74: cysteine 74; Dab2: DAB adaptor protein 2; Def: deferoxamine; DHE: dihydroethidium; DMSO: dimethyl sulfoxide; ERG: electroretinography; FAC: ferric ammonium citrate; Fe2+: ferrous; FTH1: ferritin heavy chain 1; GPX: glutathione peroxidase; GST: glutathione S-transferase; H2O2: hydrogen peroxide; His280: histidine 280; IFNL/IFNλ: interferon lambda; IL1B/IL-1ß: interleukin 1 beta; IS: Inner segment; ITGB1/integrin ß1: integrin subunit beta 1; KO: knockout; LC3-GST: microtubule associated protein 1 light chain 3-GST; C-terminal fusion; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; LCN2: lipocalin 2; mAb: monoclonal antibody; MDA: malondialdehyde; MMP9: matrix metallopeptidase 9; NLRP3: NLR family pyrin domain containing 3; NOD-SCID: nonobese diabetic-severe combined immunodeficiency; OS: outer segment; PBS: phosphate-buffered saline; PMEL/PMEL17: premelanosome protein; RFP: red fluorescent protein; rLCN2: recombinant LCN2; ROS: reactive oxygen species; RPE SM: retinal pigmented epithelium spent medium; RPE: retinal pigment epithelium; RSL3: RAS-selective lethal; scRNAseq: single-cell ribonucleic acid sequencing; SD-OCT: spectral domain optical coherence tomography; shRNA: small hairpin ribonucleic acid; SM: spent medium; SOD1: superoxide dismutase 1; SQSTM1/p62: sequestosome 1; STAT1: signal transducer and activator of transcription 1; STING1: stimulator of interferon response cGAMP interactor 1; TYR: tyrosinase; VCL: vinculin; WT: wild type.

Reducing Akt2 in retinal pigment epithelial cells causes a compensatory increase in Akt1 and attenuates diabetic retinopathy.

The retinal pigment epithelium (RPE) plays an important role in the development of diabetic retinopathy (DR), a leading cause of blindness worldwide. Here we set out to explore the role of Akt2 signaling-integral to both RPE homeostasis and glucose metabolism-to DR. Using human tissue and genetically manipulated mice (including RPE-specific conditional knockout (cKO) and knock-in (KI) mice), we investigate whether Akts in the RPE influences DR in models of diabetic eye disease. We found that Akt1 and Akt2 activities were reciprocally regulated in the RPE of DR donor tissue and diabetic mice. Akt2 cKO attenuated diabetes-induced retinal abnormalities through a compensatory upregulation of phospho-Akt1 leading to an inhibition of vascular injury, inflammatory cytokine release, and infiltration of immune cells mediated by the GSK3ß/NF-κB signaling pathway; overexpression of Akt2 has no effect. We propose that targeting Akt1 activity in the RPE may be a novel therapy for treating DR.