Retina

Ma J, Mehta M, Lam G, Cyr D, Ng TF, Hirose T, Tawansy KA, Taylor AW, Lashkari K. Influence of subretinal fluid in advanced stage retinopathy of prematurity on proangiogenic response and cell proliferation. Mol Vis 2014;20:881-93.Abstract
PURPOSE: The clinical phenotype of advanced stage retinopathy of prematurity (ROP, stages 4 and 5) cannot be replicated in an animal model. To dissect the molecular events that can lead up to advanced ROP, we examined subretinal fluid (SRF) and surgically dissected retrolental membranes from patients with advanced ROP to evaluate its influences on cell proliferation, angiogenic properties, and macrophage polarity. METHODS: We compared our findings to SRF collected from patients with uncomplicated rhegmatogenous retinal detachment (RD) without proliferative vitreoretinopathy and surgically dissected epiretinal membrane from eyes with macular pucker. All subretinal fluid samples were equalized for protein. The angiogenic potential of SRF from ROP eyes was measured using a combination of capillary cord formation in a fibrin clot assay, and its proliferative effect was tested with a DNA synthesis of human retinal microvascular endothelial cells. Findings were compared with SRF collected from participants with uncomplicated rhegmatogenous RD without proliferative vitreoretinopathy. The ability of SRF to induce nitric oxide production was measured in vitro using murine J774A.1 macrophages. Cytokine profiles of SRF from ROP and RD eyes were measured using a multienzyme-linked immunosorbent assay (ELISA). Fluorescent immunohistochemistry of retrolental membranes from ROP was performed to detect the presence of leukocytes and the composition of tissue macrophages using markers for M1 and M2 differentiation. RESULTS: The cytokine composition in SRF revealed that in ROP, not only were several proangiogenic factors were preferentially elevated but also the profile of proinflammatory factors was also increased compared to the RD eyes. SRF from ROP eyes supported cell proliferation and endothelial cord formation while SRF from RD eyes had inhibitory effects. SRF from eyes with ROP but not RD robustly induced nitric oxide production in macrophages. Furthermore, fluorescent immunostaining revealed a preponderance of M1 over M2 macrophages in retrolental fibrous membranes from ROP eyes. The cytokine profile and biologic properties of SRF in ROP promote a proangiogenic environment, which supports the maintenance and proliferation of fibrous membranes associated with advanced stages of ROP. In contrast, SRF from RD eyes exhibits a suppressive environment for endothelial cell proliferation and angiogenesis. CONCLUSIONS: Our investigation demonstrates that the microenvironment in advanced ROP eyes is proangiogenic and proinflammatory. These findings suggest that management of advanced ROP should not be limited to the surgical removal of the fibrovascular membranes and antiangiogenic therapy but also directed to anti-inflammatory therapy and to promote M2 activation over M1 activity.
Cho HY, Nasir HH, Sobrin L. Focal laser photocoagulation and photodynamic therapy for lupus choroidopathy. Lupus 2014;23(4):412-6.Abstract
PURPOSE: To describe the results of photodynamic therapy (PDT) and/or focal laser photocoagulation in the treatment of serous retinal detachments secondary to lupus choroidopathy. METHODS: The medical records of three patients with serous detachments secondary to lupus choroidopathy who were treated with PDT and/or focal laser photocoagulation were reviewed. Concomitant systemic medical therapy as well as visual acuity and optical coherence tomography (OCT) outcomes were recorded. RESULTS: All patients received systemic immunosuppressive therapy and had control of their extraocular manifestations prior to PDT and/or laser photocoagulation. One patient received only focal laser photocoagulation and had complete resolution of the subretinal fluid on OCT. The two other patients received a combination of PDT and focal laser treatment. One had improvement in vision and resolution of subretinal fluid on OCT. The second patient, who had longstanding lupus choroidopathy and associated subretinal fluid and macular edema, had only a significant decrease in fluid on OCT but no vision improvement. CONCLUSION: In conjunction with control of systemic disease, PDT and/or focal laser photocoagulation can be successful in resolving subretinal fluid secondary to lupus choroidopathy.
Chen L, Kim IK, Lane AM, Gauthier D, Munzenrider JE, Gragoudas ES, Miller JW. Proton beam irradiation for non-AMD CNV: 2-year results of a randomised clinical trial. Br J Ophthalmol 2014;98(9):1212-7.Abstract
AIMS: To evaluate safety and visual outcomes after proton beam irradiation (PBI) therapy for subfoveal choroidal neovascularisation (CNV) secondary to causes other than age-related macular degeneration (AMD). METHODS: This study is a prospective, unmasked and randomised clinical trial using two dosage regimens, conducted in the Massachusetts Eye and Ear Infirmary. The study included 46 patients with CNV secondary to non-AMD and best-corrected visual acuity of 20/320 or better. Patients were randomly assigned to receive 16 or 24 cobalt gray equivalents (CGE) of PBI in two equal fractions. Complete ophthalmological examinations, fundus photography and fluorescein angiography were performed at baseline and 6, 12, 18 and 24 months after treatment. RESULTS: At 1 year after treatment, 82% and 72% lost fewer than 1.5 lines of vision in the 16 CGE and in 24 CGE groups, respectively. At 2 years after therapy, 77% in the lower dose group and 64% in the higher dose group lost fewer than 1.5 lines of vision. Mild radiation complications such as radiation vasculopathy developed in 17.6% of patients. CONCLUSIONS: PBI is a safe and efficacious treatment for subfoveal CNV not due to AMD. The data with respect to visual outcomes and radiation complications trend in favour of the 16 CGE group, although differences do not reach statistical significance. PBI may be considered as an alternative to current therapies.
Samuel MA, Voinescu EP, Lilley BN, de Cabo R, Foretz M, Viollet B, Pawlyk B, Sandberg MA, Vavvas DG, Sanes JR. LKB1 and AMPK regulate synaptic remodeling in old age. Nat Neurosci 2014;17(9):1190-7.Abstract
Age-related decreases in neural function result in part from alterations in synapses. To identify molecular defects that lead to such changes, we focused on the outer retina, in which synapses are markedly altered in old rodents and humans. We found that the serine/threonine kinase LKB1 and one of its substrates, AMPK, regulate this process. In old mice, synaptic remodeling was accompanied by specific decreases in the levels of total LKB1 and active (phosphorylated) AMPK. In the absence of either kinase, young adult mice developed retinal defects similar to those that occurred in old wild-type animals. LKB1 and AMPK function in rod photoreceptors where their loss leads to aberrant axonal retraction, the extension of postsynaptic dendrites and the formation of ectopic synapses. Conversely, increasing AMPK activity genetically or pharmacologically attenuates and may reverse age-related synaptic alterations. Together, these results identify molecular determinants of age-related synaptic remodeling and suggest strategies for attenuating these changes.
Alasil T, Wang K, Keane PA, Lee H, Baniasadi N, de Boer JF, Chen TC. Analysis of normal retinal nerve fiber layer thickness by age, sex, and race using spectral domain optical coherence tomography. J Glaucoma 2013;22(7):532-41.Abstract
PURPOSE: To determine the effects of age, sex, and race on the retinal nerve fiber layer (RNFL) in the normal human eye as measured by the spectral domain optical coherence tomography (SD-OCT) Spectralis machine (Heidelberg Engineering). METHODS: Peripapillary SD-OCT RNFL thickness measurements were determined in normal subjects seen at a university-based clinic. One randomly selected eye per subject was used for analysis in this cross-sectional study. Multiple regression analysis was applied to assess the effects of age, sex, ethnicity, and mean refractive error on peripapillary RNFL thickness. Results are expressed as means±SD wherever applicable. RESULTS: The study population consisted of 190 healthy participants from 9 to 86 years of age. Of the 190 participants, 62 (33%) were men, 125 (66%) Caucasians, 26 (14%) African Americans, 14 (7%) Hispanics, 16 (8%) Asians, and 9 (5%) other races. The mean RNFL thickness for the normal population studied was 97.3 ± 9.6 µm. Normal RNFL thickness values follow the ISNT rule with decreasing RNFL thickness values starting from the thickest quadrant inferiorly to the thinnest quadrant temporally: inferior quadrant (126 ± 15.8), superior quadrant (117.2±16.13), nasal quadrant (75 ± 13.9), and temporal quadrant (70.6 ± 10.8 µm). Thinner RNFL measurements were associated with older age (P<0.001); being Caucasian, versus being either Hispanic or Asian (P=0.02 and 0.009, respectively); or being more myopic (P<0.001). For every decade of increased age, mean RNFL thickness measured thinner by approximately 1.5 µm (95% confidence interval, 0.24-0.07). Comparisons between ethnic groups revealed that Caucasians had mean RNFL values (96 ± 9.2 µm) slightly thinner than those of Hispanics (102.9 ± 11 µm; P=0.02) or Asians (100.7 ± 8.5 µm; P=0.009). African Americans RNFL values (99.2 ± 10.2 µm) were not significantly different when compared with Caucasians. There was no relationship between RNFL thickness and sex. CONCLUSIONS: The thickest RNFL measurements were found in the inferior quadrant, followed by the superior, nasal, and temporal quadrants (ISNT rule applied to the RNFL). Thinner RNFL measurements were associated with older age and increasing myopia. Caucasians tend to have thinner RNFL values when compared with Hispanics and Asians. SD-OCT analysis of the normal RNFL showed results similar to time domain OCT studies.
Emerson MM, Surzenko N, Goetz JJ, Trimarchi J, Cepko CL. Otx2 and Onecut1 promote the fates of cone photoreceptors and horizontal cells and repress rod photoreceptors. Dev Cell 2013;26(1):59-72.Abstract
Cone photoreceptors carry out phototransduction in daylight conditions and provide the critical first step in color vision. Despite their importance, little is known about the developmental mechanisms involved in their generation, particularly how they are determined relative to rod photoreceptors, the cells that initiate vision in dim light. Here, we report the identification of a cis-regulatory module (CRM) for the thyroid hormone receptor beta (Thrb) gene, an early cone marker. We found that ThrbCRM1 is active in progenitor cells biased to the production of cones and an interneuronal cell type, the horizontal cell (HC). Molecular analysis of ThrbCRM1 revealed that it is combinatorially regulated by the Otx2 and Onecut1 transcription factors. Onecut1 is sufficient to induce cells with the earliest markers of cones and HCs. Conversely, interference with Onecut1 transcriptional activity leads to precocious rod development, suggesting that Onecut1 is critically important in defining cone versus rod fates.
Farkas MH, Grant GR, White JA, Sousa ME, Consugar MB, Pierce EA. Transcriptome analyses of the human retina identify unprecedented transcript diversity and 3.5 Mb of novel transcribed sequence via significant alternative splicing and novel genes. BMC Genomics 2013;14:486.Abstract
BACKGROUND: The retina is a complex tissue comprised of multiple cell types that is affected by a diverse set of diseases that are important causes of vision loss. Characterizing the transcripts, both annotated and novel, that are expressed in a given tissue has become vital for understanding the mechanisms underlying the pathology of disease. RESULTS: We sequenced RNA prepared from three normal human retinas and characterized the retinal transcriptome at an unprecedented level due to the increased depth of sampling provided by the RNA-seq approach. We used a non-redundant reference transcriptome from all of the empirically-determined human reference tracks to identify annotated and novel sequences expressed in the retina. We detected 79,915 novel alternative splicing events, including 29,887 novel exons, 21,757 3' and 5' alternate splice sites, and 28,271 exon skipping events. We also identified 116 potential novel genes. These data represent a significant addition to the annotated human transcriptome. For example, the novel exons detected increase the number of identified exons by 3%. Using a high-throughput RNA capture approach to validate 14,696 of these novel transcriptome features we found that 99% of the putative novel events can be reproducibly detected. Further, 15-36% of the novel splicing events maintain an open reading frame, suggesting they produce novel protein products. CONCLUSIONS: To our knowledge, this is the first application of RNA capture to perform large-scale validation of novel transcriptome features. In total, these analyses provide extensive detail about a previously uncharacterized level of transcript diversity in the human retina.
Chen J, Michan S, Juan AM, Hurst CG, Hatton CJ, Pei DT, Joyal J-S, Evans LP, Cui Z, Stahl A, Sapieha P, Sinclair DA, Smith LEH. Neuronal sirtuin1 mediates retinal vascular regeneration in oxygen-induced ischemic retinopathy. Angiogenesis 2013;16(4):985-92.Abstract
Regeneration of blood vessels in ischemic neuronal tissue is critical to reduce tissue damage in diseases. In proliferative retinopathy, initial vessel loss leads to retinal ischemia, which can induce either regrowth of vessels to restore normal metabolism and minimize damage, or progress to hypoxia-induced sight-threatening pathologic vaso-proliferation. It is not well understood how retinal neurons mediate regeneration of vascular growth in response to ischemic insults. In this study we aim to investigate the potential role of Sirtuin 1 (Sirt1), a metabolically-regulated protein deacetylase, in mediating the response of ischemic neurons to regulate vascular regrowth in a mouse model of oxygen-induced ischemic retinopathy (OIR). We found that Sirt1 is highly induced in the avascular ischemic retina in OIR. Conditional depletion of neuronal Sirt1 leads to significantly decreased retinal vascular regeneration into the avascular zone and increased hypoxia-induced pathologic vascular growth. This effect is likely independent of PGC-1α, a known Sirt1 target, as absence of PGC-1α in knockout mice does not impact vascular growth in retinopathy. We found that neuronal Sirt1 controls vascular regrowth in part through modulating deacetylation and stability of hypoxia-induced factor 1α and 2α, and thereby modulating expression of angiogenic factors. These results indicate that ischemic neurons induce Sirt1 to promote revascularization into ischemic neuronal areas, suggesting a novel role of neuronal Sirt1 in mediating vascular regeneration in ischemic conditions, with potential implications beyond retinopathy.
Englander M, Chen TC, Paschalis EI, Miller JW, Kim IK. Intravitreal injections at the Massachusetts Eye and Ear Infirmary: analysis of treatment indications and postinjection endophthalmitis rates. Br J Ophthalmol 2013;97(4):460-5.Abstract
AIM: To report the incidence rate of acute postoperative endophthalmitis secondary to therapeutic intravitreal injections. METHODS: A retrospective review of all consecutive eyes after intravitreal injections was performed at the Massachusetts Eye and Ear Infirmary, Boston, from 1 January 2007 to 31 December 2011. RESULTS: During the 5-year study interval, 10 208 intravitreal injections were performed. The overall incidence rate of endophthalmitis was 0.029% per injection (3 of 10 208 injections). In the three cases, in our series, the endophthalmitis occurred at an average of seven injections, which lies within the SD of the mean number of injections received by each eye in this study, suggesting approximately equal probability of infection for each eye after receiving multiple, sequential injections. Bacterial cultures and Gram stain revealed coagulase-negative Staphylococcus species (n=1), moderate bacteria with negative culture (n=1) and moderate Staphylococcus epidermidis (n=1). All cases were successfully treated using either intravitreal antibiotics and steroids or pars plana vitrectomy. Best-corrected visual acuity reduction was not clinically significant at the last visit (>7 months for all cases). CONCLUSIONS: Acute endophthalmitis is a rare potential complication after intravitreal injection. Further studies are required to elucidate the best prophylactic and aseptic techniques to prevent this rare complication.
Takeuchi K, Morizane Y, Kamami-Levy C, Suzuki J, Kayama M, Cai W, Miller JW, Vavvas DG. AMP-dependent kinase inhibits oxidative stress-induced caveolin-1 phosphorylation and endocytosis by suppressing the dissociation between c-Abl and Prdx1 proteins in endothelial cells. J Biol Chem 2013;288(28):20581-91.Abstract
Caveolin-1 is the primary structural component of endothelial caveolae that is essential for transcellular trafficking of albumin and is also a critical scaffolding protein that regulates the activity of signaling molecules in caveolae. Phosphorylation of caveolin-1 plays a fundamental role in the mechanism of oxidant-induced vascular hyper permeability. However, the regulatory mechanism of caveolin-1 phosphorylation remains unclear. Here we identify a previously unexpected role for AMPK in inhibition of caveolin-1 phosphorylation under oxidative stress. A pharmacological activator of AMPK, 5-amino-4-imidazole carboxamide riboside (AICAR), inhibited oxidative stress-induced phosphorylation of both caveolin-1 and c-Abl, which is the major kinase of caveolin-1, and endocytosis of albumin in human umbilical vein endothelial cell. These effects were abolished by treatment with two specific inhibitors of AICAR, dipyridamole, and 5-iodotubericidin. Consistently, knockdown of the catalytic AMPKα subunit by siRNA abolished the inhibitory effect of AICAR on oxidant-induced phosphorylation of both caveolin-1 and c-Abl. Pretreatment with specific c-Abl inhibitor, imatinib mesylate, and knock down of c-Abl significantly decreased the caveolin-1 phosphorylation after H2O2 exposure and abolished the inhibitory effect of AICAR on the caveolin-1 phosphorylation. Interestingly, knockdown of Prdx-1, an antioxidant enzyme associated with c-Abl, increased phosphorylation of both caveolin-1 and c-Abl and abolished the inhibitory effect of AICAR on the caveolin-1 phosphorylation. Furthermore, co-immunoprecipitation experiment showed that AICAR suppressed the oxidant-induced dissociation between c-Abl and Prdx1. Overall, our results suggest that activation of AMPK inhibits oxidative stress-induced caveolin-1 phosphorylation and endocytosis, and this effect is mediated in part by stabilizing the interaction between c-Abl and Prdx-1.
Yonekawa Y, MacDonald SM, Shildkrot Y, Mukai S. Standard fractionation low-dose proton radiotherapy for diffuse choroidal hemangiomas in pediatric Sturge-Weber syndrome. J AAPOS 2013;17(3):318-22.Abstract
Sturge-Weber syndrome is a nonhereditary congenital neurocutaneous syndrome characterized by leptomeningeal angiomatosis, facial nevus flammeus, and diffuse choroidal hemangioma, which when complicated by total retinal detachment, portend a poor prognosis. Management is often limited to salvage external beam irradiation. We present a modified proton therapy technique for young children with total bullous retinal detachments that uses standard fractionation low-dose proton radiotherapy to decrease the risk of radiation complications. Treatment techniques for young children who cannot cooperate with conventional radiation protocols are also described.
Theodoropoulou S, Brodowska K, Kayama M, Morizane Y, Miller JW, Gragoudas ES, Vavvas DG. Aminoimidazole carboxamide ribonucleotide (AICAR) inhibits the growth of retinoblastoma in vivo by decreasing angiogenesis and inducing apoptosis. PLoS One 2013;8(1):e52852.Abstract
5-Aminoimidazole-4-carboxamide-1-β-4-ribofuranoside (AICAR), an analog of AMP is widely used as an activator of AMP-kinase (AMPK), a protein that regulates the responses of the cell to energy change. Recently, we showed that AICAR-induced AMPK activation inhibits the growth of retinoblastoma cells in vitro by decreasing cyclins and by inducing apoptosis and S-phase arrest. In this study, we investigated the effects of AMPK activator AICAR on the growth of retinoblastoma in vivo. Intraperitoneal injection of AICAR resulted in 48% growth inhibition of Y79 retinoblastoma cell tumors in mice. Tumors isolated from mice treated with AICAR had decreased expression of Ki67 and increased apoptotic cells (TUNEL positive) compared with the control. In addition, AICAR treatment suppressed significantly tumor vessel density and macrophage infiltration. We also showed that AICAR administration resulted in AMPK activation and mTOR pathway inhibition. Paradoxically observed down-regulation of p21, which indicates that p21 may have a novel function of an oncogene in retinoblastoma tumor. Our results indicate that AICAR treatment inhibited the growth of retinoblastoma tumor in vivo via AMPK/mTORC1 pathway and by apoptogenic, anti-proliferative, anti-angiogenesis mechanism. AICAR is a promising novel non-chemotherapeutic drug that may be effective as an adjuvant in treating Retinoblastoma.
Yonekawa Y, Shildkrot Y, Eliott D. Inferior peripheral nonperfusion in bilateral diffuse uveal melanocytic proliferation. Ophthalmic Surg Lasers Imaging Retina 2013;44(2):190-2.Abstract
Bilateral diffuse uveal melanocytic proliferation (BDUMP) is a paraneoplastic syndrome characterized by cataract, photoreceptor loss and subretinal fluid overlying patchy areas of retinal pigment epithelium atrophy, and a diffusely thickened choroid with focal nodules. We present the case of a 64-year-old woman with a history of endometrial adenocarcinoma who developed BDUMP with bilateral exudative retinal detachments with inferior peripheral retinal ischemia. This new finding of peripheral nonperfusion expands the spectrum of BDUMP.

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