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Gaier ED, Rasool N, Rizzo JF. Sectoral Sparing Associated With a Cilioretinal Artery in Arteritic Anterior Ischemic Optic Neuropathy. J Neuroophthalmol 2022;42(2):e514-e516.Abstract
ABSTRACT: Giant cell arteritis (GCA) is a life-threatening vasculitis occurring in older adults that can cause blindness by ischemia of the choroid, retina, and optic nerve. We report a case of a patient who presented with "occult" GCA with severe anterior ischemic optic neuropathy affecting both optic nerves, delayed choroidal filling, and a concomitant cilioretinal artery occlusion in the left eye. The retinal territory supplied by the affected cilioretinal artery was hypoperfused, yet this retinal territory at least partially corresponded to the only preserved visual field in that eye. The sector of the optic disc corresponding to the emergence of the cilioretinal artery was the only sector spared by pallid edema. This pattern of sectoral sparing associated with a cilioretinal artery has been observed in other patients with GCA and in animal models of posterior ciliary artery occlusion. This case serves as a clear example of an incompletely understood phenomenon in posterior pole circulation in vascular occlusive disease that deserves further study.
Bora K, Wang Z, Yemanyi F, Maurya M, Blomfield AK, Tomita Y, Chen J. Endothelial Cell Transcytosis Assay as an In Vitro Model to Evaluate Inner Blood-Retinal Barrier Permeability. J Vis Exp 2022;(184)Abstract
Dysfunction of the blood-retinal barrier (BRB) contributes to the pathophysiology of several vascular eye diseases, often resulting in retinal edema and subsequent vision loss. The inner blood-retinal barrier (iBRB) is mainly composed of retinal vascular endothelium with low permeability under physiological conditions. This feature of low permeability is tightly regulated and maintained by low rates of paracellular transport between adjacent retinal microvascular endothelial cells, as well as transcellular transport (transcytosis) through them. The assessment of retinal transcellular barrier permeability may provide fundamental insights into iBRB integrity in health and disease. In this study, we describe an endothelial cell (EC) transcytosis assay, as an in vitro model for evaluating iBRB permeability, using human retinal microvascular endothelial cells (HRMECs). This assay assesses the ability of HRMECs to transport transferrin and horseradish peroxidase (HRP) in receptor- and caveolae-mediated transcellular transport processes, respectively. Fully confluent HRMECs cultured on porous membrane were incubated with fluorescent-tagged transferrin (clathrin-dependent transcytosis) or HRP (caveolae-mediated transcytosis) to measure the levels of transferrin or HRP transferred to the bottom chamber, indicative of transcytosis levels across the EC monolayer. Wnt signaling, a known pathway regulating iBRB, was modulated to demonstrate the caveolae-mediated HRP-based transcytosis assay method. The EC transcytosis assay described here may provide a useful tool for investigating the molecular regulators of EC permeability and iBRB integrity in vascular pathologies and for screening drug delivery systems.
Olsen MV, Lyngstadaas AV, Bair JA, Hodges RR, Utheim TP, Serhan CN, Dartt DA. Signaling Pathways Used by the Specialized Pro-Resolving Mediator Maresin 2 Regulate Goblet Cell Function: Comparison with Maresin 1. Int J Mol Sci 2022;23(11)Abstract
Specialized pro-resolving mediators (SPMs), including Maresins (MaR)-1 and 2, contribute to tear film homeostasis and resolve conjunctival inflammation. We investigated MaR2's signaling pathways in goblet cells (GC) from rat conjunctiva. Agonist-induced [Ca2+]i and high-molecular weight glycoconjugate secretion were measured. MaR2 increased [Ca2+]i and stimulated secretion. MaR2 and MaR1 stimulate conjunctival goblet cell function, especially secretion, by activating different but overlapping GPCR and signaling pathways, and furthermore counter-regulate histamine stimulated increase in [Ca2+]i. Thus, MaR2 and MaR1 play a role in maintaining the ocular surface and tear film homeostasis in health and disease. As MaR2 and MaR1 modulate conjunctival goblet cell function, they each may have potential as novel, but differing, options for the treatment of ocular surface inflammatory diseases including allergic conjunctivitis and dry eye disease. We conclude that in conjunctival GC MaR2 and MaR1, both increase the [Ca2+]i and stimulate secretion to maintain homeostasis by using one set of different, but overlapping, signaling pathways to increase [Ca2+]i and another set to stimulate secretion. MaR2 also resolves ocular allergy.
Huang X, Saki F, Wang M, Elze T, Boland MV, Pasquale LR, Johnson CA, Yousefi S. An Objective and Easy-to-Use Glaucoma Functional Severity Staging System Based on Artificial Intelligence. J Glaucoma 2022;Abstract
OBJECTIVE: To develop an objective and easy-to-use glaucoma staging system based on visual fields (VFs). SUBJECTS AND PARTICIPANTS: A total of 13,231 VFs from 8077 subjects were used to develop models and 8024 VFs from 4445 subjects were used to validate models. METHODS: We developed an unsupervised machine learning model to identify clusters with similar VF values. We annotated the clusters based on their respective mean deviation (MD). We computed optimal MD thresholds that discriminate clusters with highest accuracy based on Bayes minimum error principle. We evaluated the accuracy of the staging system and validated findings based on an independent validation dataset. RESULTS: The unsupervised k-means algorithm discovered four clusters with 6784, 4034, 1541, and 872 VFs and average MDs of 0.0▒dB (±1.4: Standard Deviation), -4.8▒dB (±1.9), -12.2▒dB (±2.9), and -23.0▒dB (±3.8), respectively. The supervised Bayes minimum error classifier identified optimal MD thresholds of -2.2▒dB, -8.0▒dB, and -17.3▒dB for discriminating normal eyes and eyes at the early, moderate, and advanced stages of glaucoma. The accuracy of the glaucoma staging system was 94%, based on identified MD thresholds with respect to the initial k-means clusters. CONCLUSIONS: We discovered that four severity levels based on MD thresholds of -2.2▒dB, -8.0▒dB, and -17.3▒dB, provides the optimal number of severity stages based on unsupervised and supervised machine learning. This glaucoma staging system is unbiased, objective, easy-to-use, and consistent, which makes it highly suitable for use in glaucoma research and for day-to-day clinical practice.
Karg MM, John L, Refaian N, Buettner C, Rottmar T, Sommer J, Bock B, Resheq YJ, Ksander BR, Heindl LM, Mackensen A, Bosch JJ. Midkine promotes metastasis and therapeutic resistance via mTOR/RPS6 in uveal melanoma. Mol Cancer Res 2022;Abstract
Uveal melanoma is a rare form of melanoma that originates in the eye, exerts widespread therapeutic resistance and displays an inherent propensity for hepatic metastases. Since metastatic disease is characterized by poor survival, there is an unmet clinical need to identify new therapeutic targets in uveal melanoma. Here, we show that the pleiotropic cytokine midkine is expressed in uveal melanoma. Midkine expression in primary uveal melanoma significantly correlates with poor survival and is elevated in patients that develop metastatic disease. Monosomy 3 and histopathological staging parameters are associated with midkine expression. In addition, we demonstrate that midkine promotes survival, migration across a barrier of hepatic sinusoid endothelial cells and resistance to AKT/mTOR inhibition. Furthermore, midkine is secreted and mediates mTOR activation by maintaining phosphorylation of the mTOR target RPS6 in uveal melanoma cells. Therefore, midkine is identified as a uveal melanoma cell survival factor that drives metastasis and therapeutic resistance, and could be exploited as a biomarker as well as a new therapeutic target. Implications: Midkine is identified as a survival factor that drives liver metastasis and therapeutic resistance in melanoma of the eye.
O'Hare M, Arboleda-Velasquez JF. Notch Signaling in Vascular Endothelial and Mural Cell Communications. Cold Spring Harb Perspect Med 2022;Abstract
The Notch signaling pathway is a highly versatile and evolutionarily conserved mechanism with an important role in cell fate determination. Notch signaling plays a vital role in vascular development, regulating several fundamental processes such as angiogenesis, arterial/venous differentiation, and mural cell investment. Aberrant Notch signaling can result in severe vascular phenotypes as observed in cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) and Alagille syndrome. It is known that vascular endothelial cells and mural cells interact to regulate vessel formation, cell maturation, and stability of the vascular network. Defective endothelial-mural cell interactions are a common phenotype in diseases characterized by impaired vascular integrity. Further refinement of the role of Notch signaling in the vascular junctions will be critical to attempts to modulate Notch in the context of human vascular disease. In this review, we aim to consolidate and summarize our current understanding of Notch signaling in the vascular endothelial and mural cells during development and in the adult vasculature.
Zhu S, Zidan A, Pang K, Musayeva A, Kang Q, Yin J. Promotion of corneal angiogenesis by sensory neuron-derived calcitonin gene-related peptide. Exp Eye Res 2022;220:109125.Abstract
The normal cornea has no blood vessels but has abundant innervation. There is emerging evidence that sensory nerves, originated from the trigeminal ganglion (TG) neurons, play a key role in corneal angiogenesis. In the current study, we examined the role of TG sensory neuron-derived calcitonin gene-related peptide (CGRP) in promoting corneal neovascularization (CNV). We found that CGRP was expressed in the TG and cultured TG neurons. In the cornea, minimal CGRP mRNA was detected and CGRP immunohistochemical staining was exclusively co-localized with corneal nerves, suggesting corneal nerves are likely the source of CGRP in the cornea. In response to intrastromal suture placement and neovascularization in the cornea, CGRP expression was increased in the TG. In addition, we showed that CGRP was potently pro-angiogenic, leading to vascular endothelial cell (VEC) proliferation, migration, and tube formation in vitro and corneal hemangiogenesis and lymphangiogenesis in vivo. In a co-culture system of TG neurons and VEC, blocking CGRP signaling in the conditioned media of TG neurons led to decreased VEC migration and tube formation. More importantly, subconjunctival injection of a CGRP antagonist CGRP8-37 reduced suture-induced corneal hemangiogenesis and lymphangiogenesis in vivo. Taken together, our data suggest that TG sensory neuron and corneal nerve-derived CGRP promotes corneal angiogenesis.

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