Publications

2018

Guo C, Cho KS, Li Y, Tchedre K, Antolik C, Ma J, Chew J, Utheim TP, Huang X, Yu H, Malik MT, Anzak N, Chen DF. IGFBPL1 Regulates Axon Growth through IGF-1-mediated Signaling Cascades. Sci Rep. 2018;8(1):2054.
Activation of axonal growth program is a critical step in successful optic nerve regeneration following injury. Yet the molecular mechanisms that orchestrate this developmental transition are not fully understood. Here we identified a novel regulator, insulin-like growth factor binding protein-like 1 (IGFBPL1), for the growth of retinal ganglion cell (RGC) axons. Expression of IGFBPL1 correlates with RGC axon growth in development, and acute knockdown of IGFBPL1 with shRNA or IGFBPL1 knockout in vivo impaired RGC axon growth. In contrast, administration of IGFBPL1 promoted axon growth. Moreover, IGFBPL1 bound to insulin-like growth factor 1 (IGF-1) and subsequently induced calcium signaling and mammalian target of rapamycin (mTOR) phosphorylation to stimulate axon elongation. Blockage of IGF-1 signaling abolished IGFBPL1-mediated axon growth, and vice versa, IGF-1 required the presence of IGFBPL1 to promote RGC axon growth. These data reveal a novel element in the control of RGC axon growth and suggest an unknown signaling loop in the regulation of the pleiotropic functions of IGF-1. They suggest new therapeutic target for promoting optic nerve and axon regeneration and repair of the central nervous system.
Katikireddy KR, White T, Miyajima T, Vasanth S, Raoof D, Chen Y, Price M, Price F, Jurkunas U. NQO1 downregulation potentiates menadione-induced endothelial-mesenchymal transition during rosette formation in Fuchs endothelial corneal dystrophy. Free Radic Biol Med. 2018;116:19–30.
Fuchs endothelial corneal dystrophy (FECD) is a genetic and oxidative stress disorder of post-mitotic human corneal endothelial cells (HCEnCs), which normally exhibit hexagonal shape and form a compact monolayer compatible with normal corneal functioning and clear vision. FECD is associated with increased DNA damage, which in turn leads to HCEnC loss, resulting in the formation rosettes and aberrant extracellular matrix (ECM) deposition in the form of pro-fibrotic guttae. Since the mechanism of ECM deposition in FECD is currently unknown, we aimed to investigate the role of endothelial-mesenchymal transition (EMT) in FECD using a previously established cellular in vitro model that recapitulates the characteristic rosette formation, by employing menadione (MN)-induced oxidative stress. We demonstrate that MN treatment alone, or a combination of MN and TGF-β1 induces reactive oxygen species (ROS), cell death, and EMT in HCEnCs during rosette formation, resulting in upregulation of EMT- and FECD-associated markers such as Snail1, N-cadherin, ZEB1, and transforming growth factor-beta-induced (TGFβI), respectively. Additionally, FECD ex vivo specimens displayed a loss of organized junctional staining of plasma membrane-bound N-cadherin, with corresponding increase in fibronectin and Snail1 compared to ex vivo controls. Addition of N-acetylcysteine (NAC) downregulated all EMT markers and abolished rosette formation. Loss of NQO1, a metabolizing enzyme of MN, led to greater increase in intracellular ROS levels as well as a significant upregulation of Snail1, fibronectin, and N-cadherin compared to normal cells, indicating that NQO1 regulates Snail1-mediated EMT. This study provides first line evidence that MN-induced oxidative stress leads to EMT in corneal endothelial cells, and the effect of which is further potentiated when redox cycling activity of MN is enhanced by the absence of NQO1. Given that NAC inhibits Snail-mediated EMT, this may be a potential therapeutic intervention for FECD.
Jakobiec F, Ma L, Wolkow N, Cameron D, Maltry A. Osseous and Adipocytic Differentiations in the Intraocular Lens and Vitreous. Am J Ophthalmol. 2018;186:77–88.
PURPOSE: To analyze 3 unusual mesenchymal transformations within the eye: adipose or osseous metaplasia of the lens and adipose tissue in the vitreous cavity. DESIGN: Observational case series. METHODS: Reevaluation of clinicopathologic diagnoses and histopathologic findings in sections stained with hematoxylin-eosin, periodic acid-Schiff (PAS) reaction, and Masson trichrome method. RESULTS: The 3 cases of mesenchymal transformation occurred in microphthalmic eyes with persistent hyperplastic primary vitreous (more recently termed persistent fetal vasculature). In 1 case there was total lens replacement with lamellar bone; in another, total replacement of the crystalline lens by adipose tissue; and in a third, an anomalous pocket of adipose tissue in the central vitreous. Multifocal remnants of the lens capsule were seen in the osseous case but were absent from the adipocytic cases. The vitreous adipose tissue was surrounded by an elaborate capillary plexus with an empty, collapsed PAS-positive lens capsule in the pupillary region. Anterior pigmented neuroectodermal disorganization, dysgenesis of angle structures, and a hypoplastic or disorganized iris were also observed in the 3 cases. CONCLUSIONS: After review of the literature, it appears that lenticular osseous replacement occurs more often than adipocytic. In addition to vascularization of the lens through a capsular dehiscence, other causes are explored, including direct epithelial-mesenchymal transformations of the lens epithelium or, less likely, of the disorganized adjacent neuroectoderm. The focus of vitreous adipose tissue may represent a transformed luxated lens extruded from its capsule, which was left behind in the pupillary zone.
BACKGROUND: Prosthetic replacement of the ocular surface ecosystem (PROSE) treatment is an effective, nonsurgical therapeutic option for patients with ocular surface disease related to cranial nerve deficits secondary to skull base tumor resection. METHODS: This case series describes the impact of PROSE treatment in patients with symptomatic exposure keratopathy or neurotrophic keratitis after skull base tumor surgery. RESULTS: All patients improved symptomatically and functionally with PROSE treatment, and have had sustained improvement for as long as 3 years. CONCLUSIONS: In postneurosurgical cases in which neurologic function may recover, PROSE treatment offers a safe, nonsurgical treatment option to support the ocular surface during the period of observation awaiting neurologic recovery.
Trakhtenberg E, Li Y, Feng Q, Tso J, Rosenberg P, Goldberg J, Benowitz L. Zinc chelation and Klf9 knockdown cooperatively promote axon regeneration after optic nerve injury. Exp Neurol. 2018;300:22–29.
The inability of axons to regenerate over long-distances in the central nervous system (CNS) limits the recovery of sensory, motor, and cognitive functions after various CNS injuries and diseases. Although pre-clinical studies have identified a number of manipulations that stimulate some degree of axon growth after CNS damage, the extent of recovery remains quite limited, emphasizing the need for improved therapies. Here, we used traumatic injury to the mouse optic nerve as a model system to test the effects of combining several treatments that have recently been found to promote axon regeneration without the risks associated with manipulating known tumor suppressors or oncogenes. The treatments tested here include TPEN, a chelator of mobile (free) zinc (Zn); shRNA against the axon growth-suppressing transcription factor Klf9; and the atypical growth factor oncomodulin combined with a cAMP analog. Whereas some combinatorial treatments produced only marginally stronger effects than the individual treatments alone, co-treatment with TPEN and Klf9 knockdown had a substantially stronger effect on axon regeneration than either one alone. This combination also promoted a high level of cell survival at longer time points. Thus, Znchelation in combination with Klf9 suppression holds therapeutic potential for promoting axon regeneration after optic nerve injury, and may also be effective for treating other CNS injuries and diseases.
Laíns I, Kelly R, Miller J, Silva R, Vavvas D, Kim I, Murta J, Lasky-Su J, Miller J, Husain D. Human Plasma Metabolomics Study across All Stages of Age-Related Macular Degeneration Identifies Potential Lipid Biomarkers. Ophthalmology. 2018;125(2):245–254.
PURPOSE: To characterize the plasma metabolomic profile of patients with age-related macular degeneration (AMD) using mass spectrometry (MS). DESIGN: Cross-sectional observational study. PARTICIPANTS: We prospectively recruited participants with a diagnosis of AMD and a control group (>50 years of age) without any vitreoretinal disease. METHODS: All participants underwent color fundus photography, used for AMD diagnosis and staging, according to the Age-Related Eye Disease Study classification scheme. Fasting blood samples were collected and plasma was analyzed by Metabolon, Inc. (Durham, NC), using ultrahigh-performance liquid chromatography (UPLC) and high-resolution MS. Metabolon's hardware and software were used to identify peaks and control quality. Principal component analysis and multivariate regression were performed to assess differences in the metabolomic profiles of AMD patients versus controls, while controlling for potential confounders. For biological interpretation, pathway enrichment analysis of significant metabolites was performed using MetaboAnalyst. MAIN OUTCOME MEASURES: The primary outcome measures were levels of plasma metabolites in participants with AMD compared with controls and among different AMD severity stages. RESULTS: We included 90 participants with AMD (30 with early AMD, 30 with intermediate AMD, and 30 with late AMD) and 30 controls. Using UPLC and MS, 878 biochemicals were identified. Multivariate logistic regression identified 87 metabolites with levels that differed significantly between AMD patients and controls. Most of these metabolites (82.8%; n = 72), including the most significant metabolites, belonged to the lipid pathways. Analysis of variance revealed that of the 87 metabolites, 48 (55.2%) also were significantly different across the different stages of AMD. A significant enrichment of the glycerophospholipids pathway was identified (P = 4.7 × 10) among these metabolites. CONCLUSIONS: Participants with AMD have altered plasma metabolomic profiles compared with controls. Our data suggest that the most significant metabolites map to the glycerophospholipid pathway. These findings have the potential to improve our understanding of AMD pathogenesis, to support the development of plasma-based metabolomics biomarkers of AMD, and to identify novel targets for treatment of this blinding disease.
Oellers P, Mowery Y, Perez B, Stinnett S, Mettu P, Vajzovic L, Light K, Steffey B, Cai J, Dutton J, Buckley E, Halperin E, Marks L, Kirsch D, Mruthyunjaya P. Efficacy and Safety of Low-Dose Iodine Plaque Brachytherapy for Juxtapapillary Choroidal Melanoma. Am J Ophthalmol. 2018;186:32–40.
PURPOSE: To evaluate low- vs high-dose plaque brachytherapy for juxtapapillary choroidal melanoma. DESIGN: Retrospective interventional case series. METHODS: Setting: Single institution. STUDY POPULATION: Forty-seven patients with juxtapapillary choroidal melanoma. INTERVENTION: Iodine-125 plaque brachytherapy. Eyes were divided into apex low-dose (LD) and high-dose (HD) groups (≤ or > median apex dose 84.35 Gy). Main outcome measures were time to distant failure, local failure, death, enucleation, radiation retinopathy, optic neuropathy, and best-corrected visual acuity (BCVA). RESULTS: Freedom from distant failure rates were 96% and 95% in apex LD and HD groups at 5 years and 77% and 95% at 10 years, respectively (P = .84). Freedom from local failure rates were 90% in the apex LD group vs 89% in the HD group at 5 and 10 years (P = .96). Apex LD and HD groups did not differ for time to death or enucleation. Five- and 10-year freedom from radiation retinopathy and optic neuropathy rates were higher in the apex LD than HD group. Loss of ≥3 BCVA lines, final BCVA 20/40 or better, and final BCVA 20/200 or worse were more favorable in the 5 mm LD compared to HD group. Visual acuity outcomes did not differ between apex LD and HD groups. CONCLUSIONS: Low-dose iodine-125 plaque brachytherapy (67.5-81 Gy at tumor apex) provides safe and effective tumor control for juxtapapillary choroidal melanoma and may be associated with reduced radiation toxicity. Larger trials are needed to determine the optimal therapeutic dose for juxtapapillary choroidal melanoma.
Li W, Webster K, LeBlanc M, Tian H. Secretogranin III: a diabetic retinopathy-selective angiogenic factor. Cell Mol Life Sci. 2018;75(4):635–647.
Secretogranin III (Scg3) is a member of the granin protein family that regulates the biogenesis of secretory granules. Scg3 was recently discovered as an angiogenic factor, expanding its functional role to extrinsic regulation. Unlike many other known angiogenic factors, the pro-angiogenic actions of Scg3 are restricted to pathological conditions. Among thousands of quantified endothelial ligands, Scg3 has the highest binding activity ratio to diabetic vs. healthy mouse retinas and lowest background binding to normal vessels. In contrast, vascular endothelial growth factor binds to and stimulates angiogenesis of both diabetic and control vasculature. Consistent with its role in pathological angiogenesis, Scg3-neutralizing antibodies alleviate retinal vascular leakage in mouse models of diabetic retinopathy and retinal neovascularization in oxygen-induced retinopathy mice. This review summarizes our current knowledge of Scg3 as a regulatory protein of secretory granules, highlights its new role as a highly disease-selective angiogenic factor, and envisions Scg3 inhibitors as "selective angiogenesis blockers" for targeted therapy.
Bauer C, Cattaneo Z, Merabet L. Early blindness is associated with increased volume of the uncinate fasciculus. Eur J Neurosci. 2018;47(5):427–432.
Growing evidence demonstrates dramatic structural and functional neuroplastic changes in individuals born with early-onset blindness. For example, cross-modal sensory processing at the level of the occipital cortex appears to be associated with adaptive behaviors in the blind. However, detailed studies examining the structural properties of key white matter pathways in other regions of the brain remain limited. Given that blind individuals rely heavily on their sense of hearing, we examined the structural properties of two important pathways involved with auditory processing, namely the uncinate and arcuate fasciculi. High angular resolution diffusion imaging (HARDI) tractography was used to examine structural parameters (i.e., tract volume and quantitative anisotropy, or QA) of these two fasciculi in a sample of 13 early blind individuals and 14 normally sighted controls. Compared to controls, early blind individuals showed a significant increase in the volume of the left uncinate fasciculus. A small area of increased QA was also observed halfway along the right arcuate fasciculus in the blind group. These findings contribute to our knowledge regarding the broad neuroplastic changes associated with profound early blindness.